CN100446901C - Coated surface-coated cutting tool with intensity distribution of compressive stress - Google Patents

Abstract

A surface-coated cutting tool (1) according to the present invention includes a base material (2) and a coating film (3) formed on the base material (2). The coating film (3) acts as the outermost layer on the base material (2) and has compressive stress. This compressive stress varies so as to have an intensity distribution in the thickness direction of the coating film (3). The intensity distribution is characterized in that the compressive stress on the surface of the coating film decreases continuously from the surface of the coating film towards a first intermediate point between the surface of the coating film and the bottom surface of the coating film and the compressive stress reaches at the first intermediate point Relatively low point.

Description

Coated surface-coated cutting tool with intensity distribution of compressive stress

technical field

The present invention relates to cutting tools such as drills, end mills, throw away tips for drills, throw away tips for end mills, milling throw away tips, turning throw away tips, metal saws, A gear cutting tool, a reamer, and a tap, and more specifically relates to a surface-coated cutting tool having a coating film for improving properties such as wear resistance formed on its surface (outermost layer).

Background technique

Generally, hard metals (WC-Co alloys or alloys obtained by adding carbonitrides of Ti (titanium), Ta (tantalum), Nb (niobium), etc. to WC-Co alloys) have been used for cutting tools. In recent years, the trend of high-speed cutting has increased, and cemented carbide tools are increasingly used, which are formed by using CVD (chemical vapor deposition) or PVD (physical vapor deposition) The surface of cermets or ceramics based on alumina or silicon nitride is coated with 3-20 μm thick metals of Group IVa, Va and VIa in the periodic table of elements or carbides, nitrides, and nitrides of Al (aluminum). Coating films composed of carbonitrides, boronitrides and oxides are obtained.

In particular, since the coating obtained by PVD can improve wear resistance without impairing the strength of the base material, it is widely used in cutting tools requiring strength, such as drills, end mills, and multi-edged inserts for milling or turning .

Recently, in order to further improve the efficiency in the cutting process, the cutting speed has been increased. Due to this trend, greater wear resistance is required in tools. However, if high wear resistance is required, the toughness will be reduced. Therefore, simultaneous realization of high wear resistance and high toughness has been demanded.

In order to meet this demand, a method of changing internal stress such as compressive stress in a coating film formed on the surface of a base material of a cutting tool continuously or in a stepwise manner has been proposed (Japanese Patent Laid-Open No. 2001-315006 (Patent Document 1)). This proposal has some effect in meeting the requirements for simultaneous realization of wear resistance and toughness.

In the cutting tool according to the above proposal, the compressive stress of the coating film increases or decreases uniformly from the surface side of the coating film toward the surface side of the base material. Therefore, in order to significantly improve the toughness, the compressive stress should increase from the surface side of the base material toward the surface side of the coating film. Meanwhile, in order to significantly improve wear resistance, compressive stress should increase from the surface side of the coating film toward the surface side of the base material.

In other words, if the maximum compressive stress is reached on the surface of the coating film, toughness is excellent and abrasion resistance is poor. This is because the compressive stress decreases uniformly (continuously or in a stepwise manner) towards the surface of the base material. On the contrary, if the maximum compressive stress is reached on the surface of the base material, wear resistance is excellent and toughness is poor. This is because the compressive stress decreases uniformly (continuously or in a stepwise manner) toward the surface of the coating film.

Especially, in cutting tools where the highest compressive stress is reached on the surface of the coating film, the coating film tends to self-destruct due to large compressive stress after the coating film is formed (after the coating is finished) or when impact stress is applied. Then, fine film peeling (hereinafter, referred to as film chipping) tends to occur, which adversely affects the appearance of the cutting tool and the cutting performance in high-precision machining.

Since simultaneous realization of both toughness and wear resistance is one of the most basic characteristics in cutting tools of this type, cutting tools that simultaneously obtain higher levels of these characteristics are required.

Patent Document 1: Japanese Patent Laid-Open No. 2001-315006

Contents of the invention

Problems solved by the present invention

The present invention has been accomplished in view of the circumstances as described above, and an object of the present invention is to provide a surface-coated cutting tool in which excellent toughness and wear resistance are obtained and suppression of film chipping is achieved.

way to solve the problem

As a result of conducting research to solve the above-mentioned problems, the present inventors conceived that if the compressive stress on the surface portion of the coating film formed as the outermost layer on the base material is increased and relatively formed in the intensity distribution of the compressive stress inside the coating film The lowest point, in the vicinity of the relatively lowest point, can suppress stress such as impact, etc., while maintaining high toughness on the surface, and can simultaneously improve the suppression of film chipping on the surface and wear resistance. The present invention has been accomplished based on this concept and intensive research.

Specifically, a surface-coated cutting tool according to the present invention includes a base material and a coating film formed on the base material. The coating film acts as the outermost layer on the base material and has compressive stress. The compressive stress is changed so as to have an intensity distribution in the thickness direction of the coating film, and the intensity distribution is characterized in that the compressive stress on the surface of the coating film will move from the surface of the coating film to the first layer between the surface of the coating film and the bottom surface of the coating film. An intermediate point decreases continuously and the compressive stress reaches a relative minimum at the first intermediate point. Since a relatively lowest point is reached at the first intermediate point at which self-destruction of the coating film or stress such as impact or the like is suppressed, the development of cracks toward the bottom surface of the coating film can be effectively suppressed. Therefore, the first intermediate point is not located on (overlapping) the bottom surface of the coating film, but is located between the surface of the coating film and the bottom surface of the coating film as described above.

The surface-coated cutting tool according to the present invention mainly includes four embodiments (i.e., the first to fourth embodiments described below), as embodiments of the intensity distribution (in particular, the direction from the first intermediate point toward the bottom surface of the coating film) intensity distribution).

The intensity distribution according to the first embodiment of the invention is characterized in that the highest compressive stress is reached on the surface of the coating film and that the compressive stress is maintained at a constant value from the first intermediate point to the bottom surface of the coating film.

Here, the compressive stress may be a stress ranging from at least −15 GPa to at most 0 GPa. In addition, the first intermediate point may be located at a distance corresponding to at least 0.1% to at most 50% of the thickness of the coating film from the surface of the coating film.

The compressive stress at the first intermediate point of the coating film may be set to a value corresponding to 20-90% of the compressive stress on the surface of the coating film.

Alternatively, the compressive stress at the first intermediate point of the coating film may be set to a value corresponding to 40-80% of the compressive stress on the surface of the coating film.

The compressive stress may reach a maximum value on the surface of the coating film, the highest compressive stress may be maintained over a prescribed distance from the surface of the coating film to the first intermediate point, and thereafter the compressive stress may continuously decrease toward the first intermediate point.

The intensity distribution according to the second embodiment of the invention is characterized in that the compressive stress increases continuously from the first intermediate point towards the bottom surface of the coating film.

Here, the compressive stress may be a stress ranging from at least −15 GPa to at most 0 GPa. In addition, the first intermediate point may be located at a distance corresponding to at least 0.1% to at most 50% of the thickness of the coating film from the surface of the coating film.

The compressive stress can reach a maximum on the surface of the coating film. The compressive stress at the first intermediate point of the coating film may be set to a value corresponding to 20-90% of the compressive stress on the surface of the coating film.

Alternatively, the compressive stress at the first intermediate point of the coating film may be set to a value corresponding to 40-80% of the compressive stress on the surface of the coating film.

The compressive stress on the surface of the coating film may be maintained over a prescribed distance from the surface of the coating film to the first intermediate point, and thereafter the compressive stress may be continuously decreased toward the first intermediate point.

The intensity distribution according to the third embodiment of the present invention is characterized in that the compressive stress increases continuously from the first intermediate point toward a second intermediate point located between the first intermediate point and the bottom surface of the coating film and reaches relative highest point.

Here, the compressive stress may be a stress ranging from at least −15 GPa to at most 0 GPa. In addition, the first intermediate point may be located at a distance corresponding to at least 0.1% to at most 50% of the thickness of the coating film from the surface of the coating film. The second intermediate point may be located at a distance corresponding to at least 0.2% to at most 95% of the thickness of the coating film from the surface of the coating film.

The compressive stress can reach a maximum on the surface of the coating film. In addition, the compressive stress at the first intermediate point of the coating film may be set to a value corresponding to 20-90% of the compressive stress on the surface of the coating film.

Alternatively, the compressive stress at the first intermediate point of the coating film may be set to a value corresponding to 40-80% of the compressive stress on the surface of the coating film.

The compressive stress on the surface of the coating film may be maintained for a prescribed distance from the surface of the coating film toward the first intermediate point, and thereafter the compressive stress may be continuously decreased toward the first intermediate point.

The intensity distribution according to the fourth embodiment of the present invention is characterized in that the compressive stress increases continuously from the first intermediate point toward a second intermediate point located between the first intermediate point and the bottom surface of the coating film and reaches The relative highest point, and intensity distribution has one or more similar relative lowest points between the second intermediate point and the bottom surface of the coating film.

Additionally, the intensity profile may have one or more similar relative peaks between the second intermediate point and the bottom surface of the coating film. The intensity distribution may have one or more similar relative lowest points and one or more similar relative highest points between the second intermediate point and the bottom surface of the coating film, in an alternating and repeating manner in this order.

All of the relative lowest points can reach substantially the same compressive stress and all of the relative highest points can reach substantially the same compressive stress. Additionally, all of the relative lowest points and all of the relative highest points may have different compressive stress values from one another.

Here, the compressive stress may be a stress ranging from at least −15 GPa to at most 0 GPa. In addition, the first intermediate point may be located at a distance corresponding to at least 0.1% to at most 40% of the thickness of the coating film from the surface of the coating film. The second intermediate point may be located at a distance corresponding to at least 0.2% to at most 80% of the thickness of the coating film from the surface of the coating film.

The highest compressive stress can be reached on the surface of the coating film, and the compressive stress at the first intermediate point of the coating film can be set to a value corresponding to 10-80% of the compressive stress on the surface of the coating film.

Alternatively, the compressive stress at the first intermediate point of the coating film may be set to a value corresponding to 20-60% of the compressive stress on the surface of the coating film.

The compressive stress on the surface of the coating film may be maintained for a prescribed distance from the surface of the coating film toward the first intermediate point, and thereafter the compressive stress may be continuously decreased toward the first intermediate point.

Effect of the present invention

Due to the structural design as described above, the surface-coated cutting tool according to the present invention achieves both excellent toughness and excellent wear resistance and improved resistance to chipping of the film layer.

In particular, it can be seen from the strength distribution according to the first embodiment as described above that the highest compressive stress is achieved on the surface of the coating film, which can effectively prevent chipping of tools and the like caused at the initial stage of cutting, and Improves the toughness of cutting tools. In addition, a relatively lowest point in the intensity distribution of compressive stress is formed in a portion near the surface inside the coating film, and this portion serves to effectively relieve self-destruction of the coating film or stress such as impact or the like. Therefore, the resistance to chipping of the film layer is significantly improved. Furthermore, the compressive stress remains constant from the relatively lowest point to the bottom surface of the coating film, whereby the abrasion resistance is remarkably improved.

In addition, as can be seen from the intensity distribution according to the second embodiment as described above, the compressive stress on the surface of the coating film is higher than the compressive stress inside the coating film, which can effectively prevent the Chipping of tools, etc., and improve the toughness of cutting tools. Also, because a relatively lowest point in the intensity distribution of compressive stress is formed in a portion close to the surface inside the coating film, and this portion serves to effectively relieve self-destruction of the coating film or stress such as impact or the like. Therefore, the resistance to chipping of the film layer is significantly improved, and the abrasion resistance is also improved at the same time. In addition, the compressive stress increases from the relatively lowest point to the bottom surface of the coating film, whereby more excellent toughness can be obtained.

In addition, as can be seen from the intensity distribution according to the third embodiment as described above, the compressive stress on the surface of the coating film is greater than that inside the coating film, which can effectively prevent damage caused at the initial stage of cutting. Chipping of tools, etc., and improvement of toughness of cutting tools. In addition, because a relatively lowest point in the intensity distribution of compressive stress is formed in a portion close to the surface inside the coating film, and this portion is used to effectively relieve self-destruction of the coating film or stress such as impact or the like. Therefore, the resistance to chipping of the film layer is significantly improved, and the abrasion resistance is also improved at the same time. In addition, not only the relative lowest point but also the relative highest point are provided, so that more excellent toughness is achieved in the vicinity of the relative highest point.

In addition, as can be seen from the intensity distribution according to the fourth embodiment as described above, the compressive stress on the surface of the coating film is greater than that inside the coating film, which can effectively prevent the damage caused at the initial stage of cutting. Chipping of tools, etc., and improvement of toughness of cutting tools. In addition, because a relatively lowest point in the intensity distribution of compressive stress is formed in a portion close to the surface inside the coating film, and this portion is used to effectively relieve self-destruction of the coating film or stress such as impact or the like. Therefore, the resistance to chipping of the film layer is significantly improved, and the abrasion resistance is also improved at the same time. In addition, not only the relative lowest point but also the relative highest point are provided, so that more excellent toughness is achieved in the vicinity of the relative highest point. In addition, a plurality of such relative minimums and relative maximums are formed, whereby the toughness and properties of abrasion resistance and film chipping resistance are further improved.

As described above, the present invention has succeeded in achieving both excellent toughness and excellent wear resistance and an improvement in resistance to chipping of the film layer due to the strength distribution of compressive stress as characterized above .

Description of drawings

Fig. 1 is a schematic cross-sectional view of a surface-coated cutting tool according to the present invention.

Fig. 2 is an enlarged schematic cross-sectional view of a portion in a coating film of a surface-coated cutting tool according to the present invention.

Fig. 3 is a graph showing the first embodiment of the intensity distribution of the compressive stress of the coating film.

Fig. 4 is a graph showing the first embodiment of the intensity distribution of the compressive stress of the coating film when the highest compressive stress on the surface of the coating film is maintained over a prescribed distance.

Fig. 5 is a schematic cross-sectional view of a surface-coated cutting tool according to the invention with a formed intermediate layer.

Fig. 6 is a graph showing a second embodiment of the intensity distribution of the compressive stress of the coating film.

Fig. 7 is a graph showing a second embodiment of the intensity distribution of the compressive stress of the coating film when the compressive stress on the surface of the coating film is maintained over a prescribed distance.

Fig. 8 is another enlarged schematic cross-sectional view of a portion in the coating film of the surface-coated cutting tool according to the present invention.

Fig. 9 is a graph showing a third embodiment of the intensity distribution of the compressive stress of the coating film.

Fig. 10 is a graph showing a third embodiment of the intensity distribution of the compressive stress of the coating film when the compressive stress on the surface of the coating film is maintained over a prescribed distance.

Fig. 11 is still another enlarged schematic cross-sectional view of a part in the coating film of the surface-coated cutting tool according to the present invention.

Fig. 12 is a graph showing a fourth embodiment of the intensity distribution of the compressive stress of the coating film.

Fig. 13 is a graph showing a fourth embodiment of the intensity distribution of the compressive stress of the coating film when the compressive stress on the surface of the coating film is maintained over a prescribed distance.

Expression of reference characters

1 surface coated cutting tool; 2 base material; 3 coating film; 4 surface of coating film; 5 first middle point; 6 bottom surface of coating film; 7 arrow; 8 middle layer; 9 second middle point; 10 third middle points; and 11 fourth intermediate points.

Detailed ways

The present invention is described in more detail below. The description of the embodiments will be made with reference to the drawings, and those having the same reference characters as specified represent the same or corresponding elements.

<Surface Coated Cutting Tools>

As shown in FIG. 1 , a surface-coated cutting tool 1 according to the present invention includes a base material 2 and a coating film 3 formed on the base material. Although in FIG. 1 the coating film 3 is in direct contact with the surface of the base material 2 after being formed, any intermediate layer to be described later may be formed between the coating film 3 and the base material 2 provided that the coating film 3 is the outermost layer . In the present application, "a coating film formed on a base material" is considered to include a case where any intermediate layer is formed.

Such surface-coated cutting tools according to the present invention can be suitably used as cutting tools such as drills, end mills, multi-edged inserts for drills, multi-edged inserts for end mills, multi-edged inserts for milling, multi-edged inserts for turning , metal saws, gear cutting tools, hole reamers, or taps, etc. In particular, it is suitable for finishing or precision cutting as well as in turning processes. In these applications, surface-coated cutting tools achieve excellent toughness and wear resistance. In addition, since the surface-coated cutting tool achieves excellent resistance to chipping of the film layer, the machined surface roughness of the material being cut is improved. In addition, since an excellent finish on the machined surface of the material being cut is also achieved, processing with rough machining is also allowed.

<basic material>

Any base material generally known as a base material for applications of the type described above may be used in the surface-coated cutting tool according to the invention. For example, it is preferable to use hard metals (such as WC type hard metals, materials containing Co in addition to WC, or materials with added carbonitrides of Ti, Ta, Nb or the like), cermets (mainly composed of TiC , TiN, TiCN or similar), high speed steel, ceramics (titanium carbide, silicon carbide, silicon nitride, aluminum nitride, aluminum oxide, or similar), sintered cubic boron nitride, or sintered diamond.

Among these various base materials, especially, WC-type hard metals, cermets or sintered cubic boron nitride are preferably selected. This is because these base materials are particularly excellent in the balance between hardness and strength at high temperatures, and have excellent characteristics as base materials for surface-coated cutting tools for the above-mentioned applications.

<coating film>

The coating film according to the present invention is formed on the base material and as the outermost layer. As long as the coating film is formed in this way, the coating film does not have to coat the entire surface of the base material, and portions where no coating film is formed or portions that do not satisfy the strength distribution of compressive stress to be described below may be included in the surface of the base material. It should be noted that the present invention includes the case in which, when once a coating film is formed and then a part of the surface of the coating film is removed by some post-processing process, the newly exposed layer can serve as a coating film satisfying the intensity distribution of the compressive stress of the present invention . In addition, the present invention also includes the case where, when an intermediate layer (to be described below) is formed between the base material and the coating film and the coating is removed by some post-processing and the intermediate layer is exposed also as the outermost layer , the intermediate layer in the exposed portion serves as a coating film satisfying the intensity distribution of the compressive stress of the present invention (if the intermediate layer is formed of a plurality of layers, the outermost layer (layer as the surface) among the plurality of layers as the coating film involved in the present invention).

The coating film is formed so as to obtain improvements in various characteristics for determining the used cutting edge portion, such as wear resistance, oxidation resistance, toughness of the tool, or color characteristics. The composition of the coating film is not particularly limited, and generally known compositions can be used. For example, an exemplary composition includes an element selected from Group IVa elements (Ti, Zr, Hf, etc.), Group Va elements (V, Nb, Ta, etc.), Group VIa elements (Cr, Mo, W, etc.) of the Periodic Table of Elements. Carbides, nitrides, oxides, carbonitrides, oxycarbides, oxynitrides, or carbides of at least one element, Al (aluminum), B (boron), Si (silicon), and Ge (germanium) - Nitride-oxides, or their solid solutions.

In particular, exemplary suitable compositions include Ti, Al, (Ti _1-x Al _x ), (Al _1-x V _x ), (Ti _1-x Six ₎ , (Al _1-x Cr _x ), (Ti _1-xy Al _x Si _y ), or (Al _1-xy Cr _x V _y ) (x or y represents any number not greater than 1) (further containing B, Cr or similar substances may also include) nitrides , carbonitrides, oxynitrides or carbide-nitride-oxides.

More preferably, exemplary compositions include TiCN, TiN, TiSiN, TiSiCN, TiAlN, TiAlCrN, TiAlSiN, TiAlSiCrN, AlCrN, AlCrCN, AlCrVN, TiBN, TiAlBN, TiSiBN, TiBCN, TiAlBCN, TiSiBCN, AlN, AlCN, AlVN, AlVCN and analog. In these compositions, the ratio of each atom follows the exemplary general formula as described above.

It can be assumed that such a coating film is formed as a single type layer. It should be noted that the single-type layer here refers to a structure in which the number of stacked layers can be set to one or more and the types of elements constituting the layer are the same for each layer. Therefore, as long as the types of elements are the same, a structure formed of a plurality of layers with different atomic ratios is also included in the single-type layer here.

In the coating film according to the present invention, the types of elements and the ratio of atoms are preferably the same, especially as a whole. However, the monotype layer as described above is considered to include a super multilayer film structure in which one layer has a thickness below 0.1 μm and different types of elements constitute the respective layers.

<Thickness of Coating Film>

Although not particularly limited, the coating film according to the present invention preferably has a thickness of not less than 0.1 μm and not more than 10 μm. If the thickness is less than 0.1 μm, improvement in various characteristics due to the formation of a coating film cannot be sufficiently obtained in some cases. Meanwhile, if the thickness exceeds 10 μm, the coating film itself can be easily peeled off.

<Method of forming coating film>

Although the method of forming the coating film according to the present invention is not particularly limited, the coating film is preferably formed by physical vapor deposition (PVD). By using physical vapor deposition, the compressive stress of the coating film can be easily changed to form an intensity distribution.

That is, according to studies conducted by the present inventors, it has been found that when a coating film is formed by a physical vapor deposition method, the compressive stress of the coating film is affected by temperature, reactive gas pressure, substrate bias voltage, etc., and particularly, wherein, in When forming a coating film, it is most affected by the substrate bias voltage.

The reason is considered to be as follows. Specifically, for example, when a large substrate bias voltage is applied to the base material, elements constituting the coating film are supplied to the base material in an ionized state at high energy. Then, the impact force when the elements collide with the base material becomes larger, and thus the compressive stress of the formed coating film becomes larger. On the contrary, it has been assumed that if the substrate bias voltage is low, the impact due to the collision between the base material and the element in the ionized state is also small, and thus the compressive stress is also small.

Therefore, by employing the physical vapor deposition method and by adjusting the substrate bias voltage when forming a coating film on a base material, the intensity distribution of the compressive stress of the coating film in the thickness direction of the coating film can be obtained. As described in detail below, conditioning by mechanical or thermal shock, or the phenomenon of annealing using heat is also possible.

Although physical vapor deposition is preferably employed as a method of forming the coating film of the present invention, it is not desirable to exclude chemical vapor deposition, which is known as another method of forming a coating film.

Exemplary physical vapor deposition methods include commonly known methods such as sputtering or ion plating where the substrate bias voltage can be adjusted. In particular, among various methods, ion plating or magnetron sputtering is preferably employed.

The ion plating method refers to the following method. Specifically, the metal is used as the cathode and the vacuum chamber as the anode. Then, the metal is evaporated and ionized, and at the same time a negative voltage (substrate bias voltage) is applied to the base material, so that ions are driven out and metal ions are deposited on the surface of the base material. In this method, if nitrogen is supplied into a vacuum and caused to react with a metal, a nitride of the metal is formed. For example, if titanium is used as a metal and caused to react with nitrogen, titanium nitrogen (TiN) is formed.

Various types of ion plating are available, however, cathodic arc ion plating to achieve a high ion ratio of raw elements is particularly preferably employed.

For use of the cathodic arc ion plating method, a metal ion bombardment method on the surface of a base material can be performed before forming a coating film. Therefore, a significant improvement in the adhesiveness of the coating film can also be effectively achieved. Therefore, cathodic arc ion plating is the preferred method from the viewpoint of adhesion.

Meanwhile, magnetron sputtering refers to the following methods. Specifically, after the vacuum chamber reaches a high vacuum, Ar gas is introduced and a high voltage is applied to the target, thereby causing glow discharge. The target is then irradiated with accelerated Ar ionized by glow discharge, and the target is sputtered. The punched and ionized target atoms are accelerated by the substrate bias voltage between the target and the substrate and deposited on the base material, thus forming a film. Exemplary magnetron sputtering methods include balanced magnetron sputtering, unbalanced magnetron sputtering, and the like.

The method of controlling the bias voltage of the substrate using the physical vapor deposition method has been shown as a method of forming the intensity distribution of the compressive stress of the coating film, however, the present invention is not limited thereto. For example, a method of applying compressive stress by mechanical impact such as sandblasting after coating film formation, a method of relieving compressive stress by using a heat source such as a heater, laser or the like, or a method of combining these methods is possible.

<Compressive stress of coating film>

The coating film according to the invention has compressive stress. Preferably, the compressive stress may be a stress ranging from not less than -15 GPa to not more than 0 GPa. More preferably, the lower limit of the compressive stress is set to -10 GPa and further preferably to -8 GPa, while its upper limit is more preferably set to -0.5 GPa and still more preferably to -1 GPa.

If the compressive stress of the coating film is lower than -15GPa, the coating film is peeled off especially on the ridge line portion of the cutting edge, depending on the shape of the cutting tool (such as a tool with a very small included angle on the cutting edge or a tool with a complex shape tool). At the same time, if the compressive stress of the coating film is higher than 0 GPa, the stress of the coating film enters a tension state. Then, cracks are caused in the coating film, resulting in chipping of the tool itself.

The compressive stress used here means one type of internal stress (intrinsic strain) existing in the coating film, and is expressed by a "-" (minus sign) numerical value (unit: GPa). Therefore, the expression "large compressive stress (internal stress)" means that the absolute value of the above values is large, and the expression "small compressive stress (internal stress)" means that the absolute value of the above values is small.

The compressive stress in the present invention is measured by the sin ² ψ method. The sin ² ψ method using X-rays is widely used as a method of measuring residual stress in polycrystalline materials. This measurement method is described in detail on pages 54-66 of "X-ray Stress Measurement" (The Society of Materials Science, Japan, 1981, published by Yokendo Co., Ltd). In the present invention, initially, the penetration depth of X-rays is fixed by combining the inclination calculation method and the side inclination calculation method, and various angles of the diffraction angle 2θ with respect to the ψ direction are included in the measured The direction of the stress is measured in a plane with the normal to the sample surface provided at the measurement position, thereby preparing a 2θ-sin ² ψ graph. The average compressive stress to this depth (distance calculated from the surface of the coating film) can be measured on the basis of the gradient of the graph. Similarly, the average compressive stress to different depths was measured sequentially and a mathematical method was used to find the intensity distribution of the compressive stress in the thickness direction of the coating film.

More specifically, in a method of measuring stress by means of X-rays in which X-rays from an X-ray light source enter a sample at a prescribed angle, X-rays diffracted by the sample are detected by an X-ray detector, and the internal stress Based on the measured value, the compressive stress inside the sample can be found as follows. X-rays from the X-ray source enter the surface of the sample at any part of the sample along an arbitrarily set angle. Rotation of the sample occurs along the ω-axis of the X-ray radiation point passing through the sample and forming a right angle to the incident X-rays on the sample surface and along the χ-axis coincident with the incident X-rays when the ω-axis is rotated parallel to the sample carrier When the sample is rotated, the angle between the surface of the sample and the incident X-ray is required to be kept constant, and the angle ψ between the normal on the diffraction surface and the normal on the sample surface is changed to measure the diffraction beam.

Here, synchrotron radiation (SR) is preferably used as the X-ray source to find the intensity distribution in the thickness direction of the coating film in view of the quality of the X-ray source (such as high luminosity, high parallelism, wavelength variability, etc.).

In order to find the compressive stress from the 2θ-sin ^2ψ graph as described above, the Young's modulus and Poisson's ratio of the coating film are necessary. Here, Young's modulus can be measured using a dynamic hardness tester or the like, and as Poisson's ratio, a value set at around 0.2 is used. This is because Poisson's ratio does not change significantly from one material to another. In the present invention, the intensity distribution of the compressive stress is important, not a particularly accurate value of the compressive stress. Therefore, in finding the compressive stress from the 2θ-sin ² ψ diagram, looking for the lattice constant and interplanar spacing instead of using Young's modulus measures can substitute for the intensity distribution of the compressive stress.

<Intensity distribution>

The compressive stress of the coating film according to the present invention varies so as to have an intensity distribution in the thickness direction of the coating film. Here, the thickness direction of the coating film refers to the direction from the surface of the coating film to the bottom surface of the coating film (because the coating film is the outermost layer on the base material, and the bottom surface refers to the surface of the outermost layer closest to the base material) and perpendicular to The direction of the surface of the coating film. A detailed description is given with reference to FIG. 2 showing an enlarged cross-sectional view of a part of the coating film 3 of FIG. 1 . Here, the direction in the thickness of the coating film is indicated by the arrow 7 from the surface 4 of the coating film towards the bottom surface 6 of the coating film. Although the arrow 7 is directed from the surface 4 of the coating film to the bottom surface 6 of the coating film for convenience, the direction is not necessarily limited to the top-down direction as long as the direction is perpendicular to the surface of the coating film. That is, the thickness direction of the coating film can be directed from the bottom surface 6 of the coating film to the surface 4 of the coating film.

The intensity distribution indicates a change in the magnitude of compressive stress in such a manner that a distribution is formed in the thickness direction of the coating film. In other words, the intensity distribution of compressive stress in the thickness direction of the coating film refers to a change in the magnitude of compressive stress not in a direction parallel to the surface of the coating film but in a direction perpendicular to the surface of the coating film.

The intensity distribution is characterized in that the compressive stress achieved on the surface of the coating film decreases continuously from the surface of the coating film towards a first intermediate point between the surface of the coating film and the bottom surface of the coating film and the compressive stress reaches at the first intermediate point Relatively low point. Hereinafter, the first to fourth embodiments of the intensity distribution are explained in detail.

<Intensity Distribution--First Embodiment>

A first embodiment of the intensity distribution is characterized in that the highest compressive stress (in other words, the compressive stress of maximum absolute value) is reached on the surface of the coating film, the compressive stress goes from the surface of the coating film towards the The first intermediate point between the bottom surfaces continuously decreases and reaches a relative lowest point at the first intermediate point, and the compressive stress maintains a constant value from the first intermediate point to the bottom surface of the coating film.

This characteristic will be described in detail with reference to FIGS. 2 and 3 showing a first embodiment of the intensity distribution of the present invention. Fig. 3 is a graph showing an intensity distribution in which the abscissa represents the distance from the surface of the coating film in the thickness direction of the coating film and the ordinate represents the compressive stress.

Initially, as shown in FIG. 2 , the first intermediate point 5 is located between the surface 4 of the coating film and the bottom surface 6 of the coating film. For the distance apart from the surface 4 of the coating film in the vertical direction, the first intermediate point 5 need not necessarily be located at a distance equivalent to the thickness of the coating film (from the surface 4 of the coating film to the bottom surface 6 of the coating film in the vertical direction) from the surface. The distance of 1/2 of the distance). Generally, the first intermediate point 5 is closer to the surface 4 of the coating film than the distance between the first intermediate point 5 and the bottom surface 6 of the coating film.

Preferably, the first intermediate point 5 is located at a distance from the surface 4 of the coating film equivalent to at least 0.1% of the thickness of the coating film (the distance between the surface 4 of the coating film and the bottom surface 6 of the coating film in the vertical direction) to at least 50% of the distance from the location. More preferably, the lower limit of the distance is set to 0.3% of the thickness and further preferably to 0.5% of the thickness, while the upper limit of the distance is suitably set to 40% of the thickness and further preferably to the thickness 35%. If the distance is set below 0.1% of thickness and when the tool is used for high-impact rough cutting such as interrupted cutting, the application of compressive stress is incomplete and the effect of film chipping suppression is not shown come out. In addition, if the distance is set to be greater than 50% of the thickness, the effect of reduction of compressive stress inside the coating film is reduced and improvement in resistance to chipping of the film layer does not appear.

Preferably, the compressive stress at the first intermediate point of the coating film is set to 20-90% of the compressive stress on the surface of the coating film. More preferably, the upper limit of the compressive stress at the first intermediate point is set to 85% of the compressive stress on the surface and more preferably to 80% of the compressive stress on the surface, while its lower limit is set to 30% of the upper compressive stress and more preferably set to 40% of it.

If the compressive stress at the first intermediate point of the coating film is set lower than 20% of the compressive stress on the surface, sufficient toughness cannot be obtained. Meanwhile, if the compressive stress on the first intermediate point of the coating film exceeds 90% of the compressive stress on the surface, impact absorption (stress relaxation) is not complete, and the inhibitory effect of film chipping does not appear.

The relative minimum point is observed on the first intermediate point 5 according to a position (in FIG. 3, a point about 0.1 μm away from the surface of the coating film), and shows that the compression of the highest value is reached on the surface of the coating film The stress (the compressive stress has a value of about -5 GPa in FIG. 3 ) decreases continuously toward the bottom surface 6 of the coating film and the degree of decrease changes at a relative minimum point. Here, the change in the degree of reduction means that the value of the compressive stress becomes constant toward the bottom surface of the coating film after reaching a relative minimum point, as shown in FIG. 3 . Accordingly, the meaning of relative nadir here is equivalent to, or broader than, the meaning of relative nadir as the term is used in connection with functions in mathematics.

There is a single relative minimum point in the intensity distribution described above, which is basically different from the change in a progressive manner in Patent Document 1.

In FIG. 3, the compressive stress reaches the highest only on the surface of the coating film (i.e., a point at a distance of 0 μm from the surface of the coating film), however, embodiments of the present invention are not limited to such a case, and only on the surface of the coating film The point where the surface is 0 μm apart reaches the highest compressive stress. That is, as shown in FIG. 4 , the present invention also includes the case where the highest compressive stress is maintained across a prescribed distance range (preferably not more than 0.5 μm) from the surface of the coating film to the bottom surface of the coating film. In other words, the present invention includes an embodiment wherein the compressive stress reaches its highest value on the surface of the coating film, the highest compressive stress is maintained across a specified distance (preferably not greater than 0.5 μm) from the surface of the coating film to the first intermediate point The stress, and then the compressive stress decrease continuously toward the first intermediate point.

As described above, particularly excellent toughness is achieved when the highest compressive stress on the surface of the coating film is maintained across a prescribed distance range from the surface of the coating film to the bottom surface of the coating film, which is preferable.

The case in which the compressive stress decreases continuously from the surface of the coating film to the first intermediate point includes not only the case in which the compressive stress decreases in a downwardly convex manner as shown in FIG. 3 but also the case in which the compressive stress decreases in an upwardly convex manner. decreasing or decreasing linearly. In addition, if the compressive stress decreases as a whole from the surface of the coating film to the first intermediate point, the case of continuous decrease here includes the case in which the compressive stress partially increases, or in which the degree of decrease (slope) is at a certain intermediate point A change occurs, or the change occurs in a graded manner (decreases in a graded manner).

The case where the compressive stress value remains constant from the first intermediate point to the bottom surface of the coating film includes not only the case where the compressive stress is set to an exact constant value but also the case where the compressive stress is set to a substantially constant value.

As described above, according to the first embodiment of the intensity distribution of the present invention, the compressive stress reaches the highest value on the surface of the coating film, and the compressive stress reaches the The first intermediate point decreases continuously and reaches a relative minimum at the first intermediate point. The highest compressive stress is achieved on the surface of the coating film, which suppresses the occurrence of cracks on the surface of the coating film as much as possible, prevents the self-destruction of the coating film due to the large compressive stress at the surface of the coating film near the relative lowest point , and relieve stress such as impact applied to the surface of the coating film. Therefore, particularly effective excellent toughness and resistance to chipping of the film layer are exhibited.

In addition, according to the first embodiment of the intensity distribution of the present invention, the compressive stress is maintained at a constant value from the first intermediate point to the bottom surface of the coating film, so as to suppress self-destruction of the coating film and provide extremely excellent abrasion resistance. In this way, the surface-coated cutting tool according to the present invention achieves extremely excellent effects in successfully attaining properties of toughness, wear resistance and film chipping resistance.

Such an excellent effect cannot be exhibited in an ordinary surface-coated cutting tool (Patent Document 1), which is characterized by the absence of a relative minimum point and compressive stress continuously or in a stepwise manner from the surface of the coating film to the bottom surface of the coating film raise or lower evenly.

<Intensity Distribution--Second Embodiment>

A second embodiment of the intensity distribution is characterized in that the compressive stress at the surface of the coating film decreases continuously from the surface of the coating film to a first intermediate point between the surface of the coating film and the bottom surface of the coating film, and the compressive stress at A relative minimum is reached at the first intermediate point, and the compressive stress increases continuously from the first intermediate point to the bottom surface of the coating film.

This characteristic will be described in detail with reference to FIGS. 2 and 6 showing a second embodiment of the intensity distribution of the present invention. Fig. 6 is a graph showing an intensity distribution in which the abscissa represents the distance from the surface of the coating film in the thickness direction of the coating film and the ordinate represents the compressive stress.

Initially, as shown in FIG. 2 , the first intermediate point 5 is located between the surface 4 of the coating film and the bottom surface 6 of the coating film. For the distance apart from the surface 4 of the coating film in the vertical direction, the first intermediate point 5 need not necessarily be located at a distance equivalent to the thickness of the coating film (from the surface 4 of the coating film to the bottom surface 6 of the coating film in the vertical direction) from the surface. The distance of 1/2 of the distance). Generally, the first intermediate point 5 is closer to the surface 4 of the coating film than the distance between the first intermediate point 5 and the bottom surface 6 of the coating film.

Preferably, the first intermediate point 5 is located at a distance from the surface of the coating film corresponding to at least 0.1% to at most 50% of the thickness of the coating film (the distance between the surface 4 of the coating film and the bottom surface 6 of the coating film in the vertical direction). % distance to the position. More preferably, the lower limit of the distance is set to 0.3% of the thickness and further preferably to 0.5% of the thickness, while the upper limit of the distance is suitably set to 40% of the thickness and further preferably to the thickness 35%. If the distance is set at less than 0.1% of thickness and when the tool is used for high-impact heavy cutting such as interrupted cutting, the application of compressive stress is incomplete and the film cracks The effect of desquamation inhibition may not be shown. In addition, if the distance is set to be greater than 50% of the thickness, the effect of reducing compressive stress inside the coating film is reduced and the improvement in resistance to chipping of the film layer does not appear.

In this intensity distribution, the compressive stress can reach the highest value on the surface 4 of the coating film (in other words, the compressive stress reaches the highest absolute value). Therefore, particularly excellent toughness can be obtained. At the same time, the compressive stress can also reach its highest value on the bottom surface 6 of the coating film (in other words, the compressive stress reaches its highest absolute value). Particularly excellent toughness can thus be obtained.

Preferably, the compressive stress at the first intermediate point of the coating film is set to 20-90% of the compressive stress at the surface of the coating film. More preferably, the upper limit of the compressive stress at the first intermediate point is set to 85% of the compressive stress on the surface and more preferably to 80% of the compressive stress on the surface, while its lower limit is set to 30% of the upper compressive stress and more preferably set to 40% of it.

If the compressive stress at the first intermediate point of the coating film is set lower than 20% of the compressive stress at the surface, sufficient toughness cannot be obtained. Meanwhile, if the compressive stress on the first intermediate point of the coating film exceeds 90% of the compressive stress on the surface, shock absorption (stress relaxation) is not complete and the inhibitory effect on film chipping does not appear.

The relative minimum point is observed on the first intermediate point according to a position (in FIG. 6, a point about 0.1 μm away from the surface of the coating film), and shows that the compressive stress on the surface of the coating film (in FIG. 6 with a value of about −5 GPa) continuously decreases toward the bottom surface 6 of the coating film, and the degree of decrease changes at the relative lowest point. Here, the change in the degree of decrease means that the value of the compressive stress starts to increase continuously toward the bottom surface of the coating film after reaching a relative minimum point, as shown in FIG. 6 .

In FIG. 6, the relative lowest point exists only at the first intermediate point, however, the embodiment of the present invention is not limited thereto, and also includes a case where the relative lowest point exists at a certain thickness in the coating film thickness direction. Here, the relative lowest point existing at a certain thickness refers to the case where the compressive stress at the relative lowest point remains substantially constant. As described above, the relatively lowest point exists with a certain thickness from the first intermediate point, so that the wear resistance can be further improved.

Accordingly, the meaning of relative nadir here is equal to, or broader than, the meaning of "relative nadir" as the term is used in connection with functions in mathematics.

In FIG. 6 , the compressive stress decreases continuously from the surface of the coating film (ie, a point at a distance of 0 μm from the surface of the coating film), however, embodiments of the present invention are not limited thereto. That is, for example, as shown in FIG. 7 , the present invention also includes the case where the compressive stress on the surface of the coating film is maintained toward the bottom surface of the coating film across a prescribed distance range (preferably not more than 0.5 μm). In other words, the present invention includes an embodiment in which the compressive stress at the surface of the coating film is greater than the compressive stress inside (in other words, the absolute value of the compressive stress on the surface is greater than the absolute value of the compressive stress inside), and The compressive stress is maintained across a prescribed distance (preferably not more than 0.5 μm) from the surface of the coating film to the first intermediate point and thereafter decreases continuously toward the first intermediate point.

As described above, particularly excellent toughness is achieved when the compressive stress on the surface of the coating film is maintained across a prescribed distance range from the surface of the coating film to the bottom surface of the coating film, which is preferable.

The case in which the compressive stress decreases continuously from the surface of the coating film to the first intermediate point includes not only the case in which the compressive stress decreases in a downwardly convex manner as shown in FIG. 6 but also the case in which the compressive stress decreases in an upwardly convex manner. decreasing or decreasing linearly. In addition, if the compressive stress generally decreases from the surface of the coating film to the first intermediate point, the case of continuous decrease here includes the case in which the compressive stress is partially increased, or in which the degree of decrease (slope) is at a certain intermediate point A change occurs, or the change occurs in a graded manner (decreases in a graded manner).

The case where the compressive stress increases continuously from the first intermediate point to the bottom surface of the coating film includes not only the case where the compressive stress increases in a downwardly convex manner as shown in FIG. 6 but also the case in which the compressive stress increases in an upwardly convex manner. The way to increase or increase linearly. In addition, if the compressive stress generally increases from the first intermediate point to the bottom surface of the coating film, the case where the continuous increase here includes the case where the compressive stress partially decreases, or where the degree of increase (slope) is at a certain A midpoint change occurs, or the change occurs in a stepwise manner (increases in a stepwise manner).

As described above, according to the second embodiment of the intensity distribution of the present invention, the compressive stress on the surface of the coating film is continuous from the surface of the coating film toward the first intermediate point between the surface of the coating film and the bottom surface of the coating film. decreases and the compressive stress reaches a relative minimum at the first intermediate point. The compressive stress on the surface of the coating film is greater than the compressive stress in the interior, so that the occurrence of cracks on the surface of the coating film is suppressed as much as possible, and the cracks caused by the large compressive stress at the surface of the coating film are prevented near the relative lowest point. Self-destruction of the coating film, and relief of stress such as impact applied to the surface of the coating film. Therefore, especially effective excellent toughness and performance against chipping of the film layer and abrasion resistance are exhibited.

In addition, according to the second embodiment of the intensity distribution of the present invention, the compressive stress increases continuously from the first intermediate point to the bottom surface of the coating film, which can suppress the self-destruction of the coating film and provide extremely excellent toughness and abrasion resistance. In this way, the surface-coated cutting tool according to the present invention achieves extremely excellent effects in successfully attaining properties of toughness, wear resistance and film chipping resistance.

Such an excellent effect cannot be exhibited in an ordinary surface-coated cutting tool (Patent Document 1), which is characterized by the absence of a relative minimum point and compressive stress continuously or in a stepwise manner from the surface of the coating film to the bottom surface of the coating film raise or lower evenly.

<Intensity Distribution--Third Embodiment>

A third embodiment of the intensity distribution is characterized in that the compressive stress at the surface of the coating film decreases continuously from the surface of the coating film to a first intermediate point between the surface of the coating film and the bottom surface of the coating film and the compressive stress at A relatively lowest point is reached at the first intermediate point, and the compressive stress increases continuously from the first intermediate point to a second intermediate point located between the first intermediate point and the bottom surface of the coating film and reaches a relative maximum at the second intermediate point point.

This characteristic will be described in detail with reference to FIGS. 8 and 9 showing a third embodiment of the intensity distribution of the present invention. Fig. 9 is a graph showing an intensity distribution in which the abscissa represents the distance from the surface of the coating film in the thickness direction of the coating film and the ordinate represents the compressive stress.

Initially, as shown in FIG. 8 , the first intermediate point 5 is located between the surface 4 of the coating film and the bottom surface 6 of the coating film. For the distance apart from the surface 4 of the coating film in the vertical direction, the first intermediate point 5 need not necessarily be located at a distance equivalent to the thickness of the coating film (from the surface 4 of the coating film to the bottom surface 6 of the coating film in the vertical direction) from the surface. The distance of 1/2 of the distance). Generally, the first intermediate point 5 is closer to the surface 4 of the coating film than the distance between the first intermediate point 5 and the bottom surface 6 of the coating film.

Preferably, the first intermediate point 5 is located at a distance from the surface 4 of the coating film equivalent to at least 0.1% of the thickness of the coating film (the distance between the surface 4 of the coating film and the bottom surface 6 of the coating film in the vertical direction) to at least 50% of the distance from the location. More preferably, the lower limit of the distance is set to 0.3% of the thickness and further preferably to 0.5% of the thickness, while the upper limit of the distance is suitably set to 40% of the thickness and further preferably to the thickness 35%. If the distance is set at less than 0.1% of thickness and when the tool is used for high impact rough cuts such as interrupted cuts, the application of compressive stress is incomplete and the effect of film chipping inhibition may not be display. In addition, if the distance is set to be greater than 50% of the thickness, the effect of reducing compressive stress inside the coating film is reduced and the improvement in resistance to chipping of the film layer does not appear.

In this intensity distribution, the compressive stress can reach its highest value on the surface 4 of the coating film (in other words, the compressive stress reaches its maximum absolute value). Therefore, particularly excellent toughness can be obtained.

Preferably, the compressive stress at the first intermediate point of the coating film is set to 20-90% of the compressive stress on the surface of the coating film. More preferably, the upper limit of the compressive stress at the first intermediate point is set to 85% of the compressive stress on the surface and more preferably to 80% of the compressive stress on the surface, while its lower limit is set to 30% of the upper compressive stress and more preferably set to 40% of it.

If the compressive stress on the surface of the coating film is set lower than 20% of the compressive stress at the first intermediate point, sufficient toughness cannot be obtained. Meanwhile, if the compressive stress on the first intermediate point of the coating film exceeds 90% of the compressive stress on the surface, the effect of impact absorption (stress relaxation) is incomplete and the inhibitory effect of film chipping may not be exhibited .

The relative minimum point is observed on the first intermediate point according to a position (in FIG. 9, a point about 0.1 μm away from the surface of the coating film), and indicates the compressive stress on the surface of the coating film (in FIG. 9 The compressive stress having a value of about -5 GPa in ) decreases continuously toward the bottom surface 6 of the coating film, and the degree of decrease changes at the relative lowest point. Here, the change in the degree of decrease means that the value of the compressive stress begins to increase continuously toward the second intermediate point after reaching the relative lowest point, as shown in FIG. 9 .

In FIG. 9, the relative lowest point exists only at the first intermediate point, however, the embodiment of the present invention is not limited thereto, and also includes a case where the relative lowest point exists at a certain thickness in the coating film thickness direction. Here, the relative lowest point existing at a certain thickness means that the compressive stress at the relative lowest point remains substantially constant across the thickness (preferably, not more than 1/2 of the coating film thickness) from the first intermediate point. As described above, the relative lowest point exists at a certain thickness from the first intermediate point, so that the toughness can be further improved.

Accordingly, the meaning of relative nadir here is equal to, or broader than, the meaning of the term "relative nadir" as used in connection with functions in mathematics.

Simultaneously, as shown in Fig. 8, the second intermediate point 9 is positioned between the first intermediate point 5 and the bottom surface 6 of the coating film, yet, the second intermediate point 9 does not necessarily have to be located at a distance equivalent to the first intermediate point 5 A position that is 1/2 of the distance from the first intermediate point 5 to the bottom surface 6 of the coating film in the vertical direction.

Preferably, the second intermediate point 9 is located at a distance from the surface of the coating film corresponding to at least 0.2% to at most 95% of the thickness of the coating film (the distance between the surface 4 of the coating film and the bottom surface 6 of the coating film in the vertical direction). % distance to the position. More preferably, the lower limit of the distance is set to 0.5% of the thickness and further preferably to 1% of the thickness, while the upper limit of the distance is suitably set to 90% of the thickness and further preferably to the thickness 80% of. If the distance is set to be lower than 0.2% of the thickness, the reduction in compressive stress is not sufficient and the improvement in film chipping resistance and abrasion resistance does not show. In addition, if the distance is set to be greater than 95% of the thickness, the effect of application of compressive stress inside the coating film is reduced, and the effect of toughness improvement cannot be exhibited.

Preferably, the compressive stress at the second intermediate point is set to 50-200% of the compressive stress on the surface of the coating film. More preferably, the upper limit of the compressive stress at the second intermediate point is set to 180% and more preferably to 150% of the compressive stress on the surface, while its lower limit is set to the compressive stress 60% of it and more preferably set to 70% of it.

If the compressive stress at the second intermediate point is set to be lower than 50% of the compressive stress at the first intermediate point, application of compressive stress is insufficient and sufficient toughness cannot be obtained. Meanwhile, if the compressive stress on the second intermediate point exceeds 200% of the compressive stress on the surface, shock absorption (stress relaxation) is excessive, and the effect of suppressing chipping of the film layer may decrease.

The relative highest point is observed on the second intermediate point according to a position (in FIG. 9, a point about 0.4 μm away from the surface of the coating film), and indicates the compressive stress on the first intermediate point 5 (in FIG. 9 having a value of about -1.8 GPa) continuously increases toward the bottom surface 6 of the coating film, and the degree of increase changes at the relatively highest point. Here, the change in the degree of increase means that the compressive stress starts to decrease continuously toward the bottom surface 6 of the coating film after reaching a relatively highest point, as shown in FIG. 9 .

In FIG. 9, the relative highest point exists only at the second intermediate point, however, the embodiment of the present invention is not limited thereto, and also includes the case where the relative highest point exists at a certain thickness in the coating film thickness direction. Here, the relative highest point existing at a certain thickness means that the compressive stress at the relative highest point remains substantially constant across the thickness (preferably, not more than 1/2 of the coating film thickness) from the second intermediate point. As described above, the relatively highest point exists at a certain thickness from the second intermediate point, so that the toughness can be further improved.

Accordingly, the meaning of relative apex here is equivalent to, or broader than, the meaning of relative apex as the term is used in connection with functions in mathematics.

Although FIG. 9 shows an embodiment in which the compressive stress decreases continuously from the second intermediate point to the bottom surface of the coating film, embodiments of the present invention are not limited thereto, and also include wherein the compressive stress decreases from the second intermediate point to the coating film. The case where the bottom surface of the sphere remains constant (substantially constant). Excellent abrasion resistance is obtained when the compressive stress decreases continuously from the second intermediate point to the bottom surface of the coating film. On the other hand, when the compressive stress was maintained at a constant value from the second intermediate point to the bottom surface of the coating film, an effect of further improving the toughness was exhibited.

In FIG. 9 , the compressive stress decreases continuously from the surface of the coating film (ie, a point 0 μm away from the surface of the coating film), however, embodiments of the present invention are not limited thereto. That is, for example, as shown in FIG. 10 , the present invention also includes the case in which the compressive stress on the surface of the coating film is maintained toward the bottom surface of the coating film across a prescribed distance range (preferably not more than 0.5 μm). In other words, the present invention includes an embodiment wherein the compressive stress on the surface of the coating film is greater than the compressive stress inside (in other words, the absolute value of the compressive stress on the surface is greater than the absolute value of the compressive stress on the inside) , and the compressive stress is maintained across a prescribed distance (preferably not more than 0.5 μm) from the surface of the coating film to the first intermediate point and thereafter continuously decreases toward the first intermediate point.

As described above, particularly excellent toughness is achieved when the compressive stress on the surface of the coating film is maintained across a prescribed distance range from the surface of the coating film to the bottom surface of the coating film, which is preferable.

The case where the compressive stress decreases continuously in the present application includes not only the case where the compressive stress decreases in a convex-up or downward-convex manner as shown in FIG. 9 but also the case where the compressive stress decreases linearly. In addition, if the compressive stress decreases as a whole, the case of continuous decrease in this application includes the case in which the compressive stress is partially increased, or in which the degree (slope) of the decrease changes at a certain midpoint, or the change changes by The case where it proceeds in a graded manner (declines in a graded manner).

The case where the compressive stress increases continuously in the present application includes not only the case where the compressive stress increases in a downwardly convex manner as shown in FIG. 9 but also the case where the compressive stress increases upwardly or linearly. In addition, if the compressive stress increases as a whole, the case of continuous increase in this application includes the case where the compressive stress partially decreases, or where the degree of increase (slope) changes at a certain midpoint, or the A situation where changes are made in a stepwise manner (increased in a stepwise manner).

As described above, according to the third embodiment of the intensity distribution of the present invention, the compressive stress on the surface of the coating film is continuous from the surface of the coating film toward the first intermediate point between the surface of the coating film and the bottom surface of the coating film decreases and the compressive stress reaches a relative minimum at the first intermediate point. The compressive stress on the surface of the coating film is greater than the compressive stress inside, which suppresses the occurrence of cracks on the surface of the coating film as much as possible, and prevents self-destruction due to large compressive stress at the surface of the coating film near the relative lowest point , In addition, stress such as impact force applied to the surface of the coating film is relieved. Therefore, a remarkable effect of excellent toughness, wear resistance, and resistance to chipping of the film layer is exhibited.

In addition, according to the third embodiment of the intensity distribution of the present invention, the compressive stress increases continuously from the first intermediate point to the second intermediate point and obtains a relatively highest point at the second intermediate point, which provides more excellent toughness. In this way, the surface-coated cutting tool according to the present invention achieves extremely excellent effects in successfully attaining properties of toughness, wear resistance and film chipping resistance.

Such an excellent effect cannot be exhibited in an ordinary surface-coated cutting tool (Patent Document 1), which is characterized by no relative lowest point and no relative highest point and compressive stress from the surface of the coating film to the bottom surface of the coating film Increasing or decreasing continuously or evenly in a stepwise manner.

<Intensity Distribution--Fourth Embodiment>

A fourth embodiment of the intensity distribution is characterized in that the compressive stress on the surface of the coating film decreases continuously from the surface of the coating film to a first intermediate point between the surface of the coating film and the bottom surface of the coating film and that the compressive stress at A relatively lowest point is reached at the first intermediate point, and the compressive stress increases continuously from the first intermediate point to a second intermediate point located between the first intermediate point and the bottom surface of the coating film and reaches a relative maximum at the second intermediate point point, and the intensity distribution has one or more similar relative minimums between the second intermediate point and the bottom surface of the coating film.

Here, the similar relative minimum point refers to the point where the compressive stress shows a behavior on the intensity distribution, the same as on the relative minimum point expressed as the first intermediate point, and refers to, for example, the point where the compressive stress starts from the second intermediate point To the point where the degree of reduction in compressive stress changes after the bottom surface of the coating film is continuously lowered. As mentioned above, one or more relative lowest points are provided between the second intermediate point and the bottom surface of the coating film, so that the development of cracks that have occurred on the coating film surface towards the interior of the coating film can be more effectively suppressed, and further improved Resistant to film chipping and exhibits excellent abrasion resistance.

At the same time, the intensity distribution may have one or more similar relative peaks between the second intermediate point and the bottom surface of the coating film.

Here, the similar relative highest point refers to the point where the compressive stress shows a behavior on the intensity distribution, the same as at the relative highest point expressed as the second intermediate point, and refers to, for example, the point where the compressive stress is from located at the second Between the intermediate point and the bottom surface of the coating film to the point at which the degree of increase in compressive stress changes after the bottom surface of the coating film continuously increases. As mentioned above, one or more relatively highest points are provided between the second intermediate point and the bottom surface of the coating film to exhibit more excellent toughness and further improve resistance to chipping of the film layer.

The intensity profile may have one or more similar relative lowest points and one or more similar relative highest points between the second intermediate point and the bottom surface of the coating film, in this order in an alternating and repeating manner. Here, the number of repetitions and the repetition interval are not particularly limited. If the relative lowest point (including the relative lowest point at the first intermediate point) and the relative highest point (including the relative highest point at the second intermediate point) exist at substantially equal intervals, the number of repetitions can be compared with the thickness of the coating film Correlationally determined, such that the distance between the relatively lowest points and the distance between the relative highest points is 0.1%-70% of the coating film thickness and the upper limit of the distance is preferably set to 60% and more of the coating film thickness It is preferably set to 50% of the coating film thickness, while the lower limit of the distance is preferably set to 0.15% of the thickness and more preferably set to 0.2% of the thickness.

If the distance is set lower than 0.1% of the thickness, the repeated interval is too short to obtain a stable stress state of the coating film, which leads to the susceptibility to chipping of the film layer. Meanwhile, if the distance is set to be greater than 70% of the thickness, the effect of forming multiple relative highest points or relative lowest points will be reduced.

As described above, a plurality of relative lowest points and relative highest points exist in this order in an alternate and repeated manner, so that the number of points where the development energy of cracks occurring on the surface of the coating film can be absorbed increases. . Therefore, the development of cracks toward the interior of the coating film can be more effectively suppressed, further improving the resistance to chipping of the film layer, and exhibiting more excellent wear resistance and toughness.

Various characteristics of the intensity distribution as described above will be discussed in detail with reference to Figures 11 and 12 showing a fourth embodiment of the intensity distribution of the present invention. Fig. 12 is a graph showing an intensity distribution in which the abscissa represents the distance from the surface of the coating film in the thickness direction of the coating film and the ordinate represents the compressive stress.

Initially, as shown in FIG. 11 , the first intermediate point 5 is located between the surface 4 of the coating film and the bottom surface 6 of the coating film. For the distance apart from the surface 4 of the coating film in the vertical direction, the first intermediate point 5 need not necessarily be located at a distance equivalent to the thickness of the coating film (from the surface 4 of the coating film to the bottom surface 6 of the coating film in the vertical direction) from the surface. The distance of 1/2 of the distance). Generally, the first intermediate point 5 is closer to the surface 4 of the coating film than the distance between the first intermediate point 5 and the bottom surface 6 of the coating film.

Preferably, the first intermediate point 5 is located at a distance from the surface 4 of the coating film equivalent to at least 0.1% of the thickness of the coating film (the distance between the surface 4 of the coating film and the bottom surface 6 of the coating film in the vertical direction) to at least 40% of the distance from the location. More preferably, the lower limit of the distance is set to 0.3% of the thickness and further preferably to 0.5% of the thickness, while the upper limit of the distance is suitably set to 35% of the thickness and further preferably to the thickness 30% of. If the distance is set at less than 0.1% of the thickness and when the tool is used for high-impact rough cutting such as interrupted cutting, the application of compressive stress is incomplete and the effect of suppressing film chipping cannot be obtained . In addition, if the distance is set to be greater than 40% of the thickness, the effect of reducing the compressive stress inside the coating film is reduced and the improvement in resistance to chipping of the film layer does not appear.

In this intensity distribution, the compressive stress can reach the maximum value at the surface 4 of the coating film (in other words, the compressive stress reaches the maximum absolute value). Therefore, particularly excellent toughness can be obtained.

Preferably, the compressive stress at the first intermediate point of the coating film is set to 10-80% of the compressive stress on the surface of the coating film. More preferably, the upper limit of the compressive stress at the first intermediate point is set to 70% of the compressive stress on the surface and more preferably to 60% of the compressive stress on the surface, while its lower limit is set to 15% of the upper compressive stress and more preferably set to 20% of it. The second or subsequent relatively lowest point from the surface 4 of the coating film preferably has a compressive stress within the above-mentioned range.

If the compressive stress at the first intermediate point is set lower than 10% of the compressive stress on the surface of the coating film, sufficient toughness cannot be obtained. Also, if the compressive stress at the first intermediate point of the coating exceeds 80% of the compressive stress at the surface, shock absorption (stress relaxation) is incomplete, and inhibition of film chipping cannot be exhibited Effect.

There are multiple relative lowest points between the surface 4 of the coating film and the bottom surface 6 of the coating film. As for the position, the first relative lowest point counted from the coating film surface 4 side occurs on the first intermediate point as described above, and any one or more points between the second intermediate point 9 and the bottom surface 6 of the coating film A relative nadir is observed at a point (eg, the third intermediate point 10 in FIG. 11 ). Here, the relative minimum point refers to a point where the compressive stress shows a behavior in the intensity distribution that the degree of compressive stress decrease changes after the compressive stress decreases continuously toward the bottom surface 6 of the coating film. Here, the change in the degree of reduction means that the compressive stress, which decreases toward the bottom surface 6 of the coating film, starts to increase continuously after reaching a relatively lowest point.

Although Figure 11 only shows the third intermediate point 10 as representing the second or subsequent relative lowest point, this representation is for convenience. The second or subsequent relative lowest point is likewise not limited.

In FIG. 12, the relative lowest point exists as a point having no width in the thickness direction of the coating film, however, the embodiment of the present invention is not limited thereto, and also includes a point in which the relative lowest point has a certain width in the thickness direction of the coating film. The case where thickness (width) exists. Here, the case where the relative minimum point exists at a certain thickness means that the compressive stress at the relative minimum point maintains a substantially constant value across the thickness (preferably, not more than 1/2 of the coating film thickness). As mentioned above, the relative lowest point exists in a certain thickness so that the wear resistance can be further improved.

Accordingly, the meaning of relative nadir here is equivalent to, or broader than, the meaning of relative nadir as the term is used in connection with functions in mathematics.

Simultaneously, as shown in Fig. 11, the second intermediate point 9 is positioned between the first intermediate point 5 and the bottom surface 6 of the coating film, however, the second intermediate point 9 does not necessarily have to be located at a distance equivalent to the first intermediate point 5 A position that is 1/2 of the distance from the first intermediate point 5 to the bottom surface 6 of the coating film in the vertical direction.

Preferably, the second intermediate point 9 is located at a distance from the surface of the coating film corresponding to at least 0.2% to at most 80% of the thickness of the coating film (the distance between the surface 4 of the coating film and the bottom surface 6 of the coating film in the vertical direction). % distance to the position. More preferably, the lower limit of the distance is set to 0.5% of the thickness and further preferably to 1% of the thickness, while the upper limit of the distance is suitably set to 75% of the thickness and further preferably to the thickness 70% of. If the distance is set to be lower than 0.2% of the thickness, the reduction in compressive stress is insufficient and the effect of improvement in suppressing chipping of the film layer and the effect of improving wear resistance are not exhibited. In addition, if the distance is set to be greater than 80% of the thickness, the effect of compressive stress applied inside the coating film is reduced, and excellent toughness cannot be exhibited.

Preferably, the compressive stress at the second intermediate point is set to 50-200% of the compressive stress on the surface of the coating film. More preferably, the upper limit of the compressive stress on the second intermediate point is set to 180% of the compressive stress on the surface of the coating film and more preferably set to 150% of the compressive stress on the surface, while its lower limit is set to 60% of the compressive stress on the surface and more preferably set to 70% of it. If there are two or more relative highest points, each relative highest point preferably has a compressive stress within the above range.

If the compressive stress at the second intermediate point is set to be lower than 50% of the compressive stress on the surface of the coating film, application of compressive stress is insufficient and sufficient toughness cannot be obtained. Meanwhile, if the compressive stress at the second intermediate point exceeds 200% of the compressive stress on the surface, the compressive stress is excessively applied, and the effect of suppressing chipping of the film layer may decrease.

There are one or more relatively highest points from the surface 4 of the coating film to the bottom surface 6 of the coating film. As for the position, the first relative highest point counted from the coating film surface 4 side appears at the second intermediate point 9 as described above. If there is a second or later relative highest point, the relative highest point is observed at any one or more points between the second intermediate point 9 and the bottom surface 6 of the coating film (for example, the fourth intermediate point in FIG. 11 point 11). The relative highest point refers to a point where the compressive stress shows a behavior in the intensity distribution that the degree of increase in the compressive stress varies after the compressive stress is continuously increased toward the bottom surface 6 of the coating film. Here, the change in the degree of increase means that the compressive stress that has increased toward the bottom surface 6 of the coating film starts to decrease continuously after reaching a relatively highest point.

Although FIG. 11 only shows the fourth intermediate point 11 as representing the second or subsequent relatively highest point, this representation is for convenience. The second or subsequent relative highest point is likewise not limited.

In FIG. 12, the relatively highest point exists as a point having no width in the thickness direction of the coating film, however, the embodiment of the present invention is not limited thereto, and also includes a point in which the relative highest point has a certain width in the thickness direction of the coating film. The case where thickness (width) exists. Here, the case where the relative highest point exists at a certain thickness means that the compressive stress at the relative highest point maintains a substantially constant value across the thickness (preferably, not more than 1/2 of the thickness of the coating film). As mentioned above, the relative highest point exists at a certain thickness, so that the toughness can be further improved.

Accordingly, the meaning of relative apex here is equivalent to, or broader than, the meaning of relative apex as the term is used in connection with functions in mathematics.

The relative lowest points and the relative highest points are preferably present in this order in an alternating and repeating manner between the surface 4 of the coating film and the bottom surface 6 of the coating film, as shown in FIG. 12 . In addition, preferably, the relative lowest point and the relative highest point exist at equal or unequal intervals, and the compressive stress exists as substantially the same value at each relative lowest point or at each relative highest point.

In FIG. 12 , the compressive stress decreases continuously from the surface of the coating film (ie, a point 0 μm away from the surface of the coating film), however, embodiments of the present invention are not limited thereto. That is, for example, as shown in FIG. 13 , the present invention also includes the case where the compressive stress on the surface of the coating film is maintained toward the bottom surface of the coating film across a prescribed distance range (preferably not more than 0.5 μm). In other words, the present invention includes an embodiment in which the compressive stress on the surface of the coating film is greater than the compressive stress inside (in other words, the absolute value of the compressive stress on the surface is greater than the absolute value of the compressive stress on the inside), and The compressive stress is maintained across a prescribed distance (preferably not more than 0.5 μm) from the surface of the coating film to the first intermediate point and thereafter decreases continuously toward the first intermediate point.

As described above, particularly excellent toughness is achieved when the compressive stress on the surface of the coating film is maintained across a prescribed distance range from the surface of the coating film to the bottom surface of the coating film, which is preferable.

The case where the compressive stress decreases continuously in the present application includes not only the case where the compressive stress decreases in a downwardly convex or upwardly convex manner as shown in FIG. 12 but also a case where the compressive stress decreases linearly. In addition, if the compressive stress decreases as a whole, the case of continuous decrease in the present application includes the case in which the compressive stress is partially increased, or in which the degree of decrease (slope) changes at a certain midpoint, or the change changes by The case where it proceeds in a graded manner (decreases in a graded manner).

The case where the compressive stress increases continuously in the present application includes not only the case where the compressive stress increases in a downwardly convex manner as shown in FIG. 12 but also the case where the compressive stress increases upwardly or linearly. In addition, if the compressive stress increases as a whole, the case of continuous increase in this application includes the case where the compressive stress is partially decreased, or where the degree of increase (slope) changes at a certain midpoint, or the change The case where it proceeds in a graded manner (increases in a graded manner).

It may be noted that in the intensity distribution as described above, the point closest to the bottom surface 6 of the coating film may be the relatively lowest point or the relatively highest point. Therefore, the compressive stress on the bottom surface 6 of the coating film may be in an increasing or decreasing trend, or alternatively, a relatively lowest point or a relatively highest point may coincide with the bottom surface 6 .

As described above, according to the fourth embodiment of the intensity distribution of the present invention, the compressive stress on the surface of the coating film is continuous from the surface of the coating film toward the first intermediate point between the surface of the coating film and the bottom surface of the coating film. decreases and the compressive stress reaches a relative minimum at the first intermediate point. The compressive stress on the surface of the coating film is greater than the compressive stress inside, which suppresses the occurrence of cracks on the surface of the coating film as much as possible, and prevents self-destruction due to large compressive stress at the surface of the coating film near the relative lowest point , In addition, stress such as impact force applied to the surface of the coating film is relieved. Therefore, a remarkable effect of excellent toughness, wear resistance, and resistance to chipping of the film layer is exhibited.

In addition, according to the fourth embodiment of the intensity distribution of the present invention, the compressive stress increases continuously from the first intermediate point to the second intermediate point and obtains a relatively highest point at the second intermediate point, which provides more excellent toughness. Furthermore, according to the fourth embodiment of the intensity distribution of the present invention, a plurality of relatively lowest points and relatively highest points exist between the second intermediate point and the bottom surface of the coating film in this order in an alternate and repeated manner. Therefore, the development of cracks occurring on the surface of the coating film toward the inside of the coating film can be more effectively suppressed, the resistance to chipping of the film layer is further improved, and more excellent wear resistance and toughness are exhibited.

In this way, the surface-coated cutting tool according to the present invention achieves extremely excellent effects in successfully attaining properties of toughness, wear resistance and film chipping resistance.

Such an excellent effect cannot be exhibited in an ordinary surface-coated cutting tool (Patent Document 1), which is characterized by no relative lowest point and no relative highest point and compressive stress from the surface of the coating film to the bottom surface of the coating film Increasing or decreasing continuously or uniformly in a stepwise manner.

<other>

In the surface-coated cutting tool according to the present invention, an arbitrary intermediate layer 8 may be formed between the base material 2 and the coating film 3, as shown in FIG. 5 . Such an intermediate layer 8 normally has the properties of improving wear resistance or improving adhesion between the base material and the coating film, and can be implemented by a single layer or by multiple layers. Here, the bottom surface 6 of the coating film serves as the contact surface between the coating film 3 and the intermediate layer 8 .

The intermediate layer can consist, for example, of TiN, TiCN, TiSiN, TiAlN, AlCrN, AlVN, TiAlCrN, TiAlSiN, TiAlSiCrN, AlCrVN or the like. In these compositions, the ratio of each atom is given after the example of the general formula exemplified as the composition of the coating film.

<Example>

Hereinafter, the present invention will be described in detail with reference to the following examples, however, the present invention is not limited to them. The compound composition of the coating film was confirmed by XPS (X-ray Photoelectron Spectroscopy Analyzer) in Examples. In addition, compressive stress and thickness (or distance from the surface of the coating film) were measured by the sin ² ψ method as described above.

In the measurement using the sin ² ψ method, the power of the X-ray used was set to 10keV, and the diffraction peak was set to that of Ti _0.5 Al _0.5 N (Example 1-6, Example 11-16, Example 21-26, and Examples 31-36), Al _0.7 Cr _0.3 N (Example 7-10), Al _0.6 Ti _0.35 Cr _0.05 N (Example 17-20), Al _0.6 Ti _0.3 Si _0.1 N (Examples 27-30), and (200) planes of Al _0.6 Ti _0.2 Si _0.1 Cr _0.1 N (Examples 37-40). Then, the measured diffraction peak positions were determined by fitting of a Gaussian function, and the slope of the 2θ-sin ² ψ diagram was obtained. In addition, a value measured by using a dynamic hardness tester (Nanoindenter manufactured by MTS Systems Corporation) was adopted as Young's modulus, and a value of TiN (0.19) was adopted as Poisson's ratio. Set the stress value as such.

The underlying coating film is formed by using cathodic arc ion plating, however, the film can also be formed by using balanced or unbalanced sputtering. In addition, although the coating film of a specific composition was formed below, the similar effect can be acquired similarly from the coating film of a different composition.

<Example 1-6>

<Manufacture of surface-coated cutting tools>

Initially, as the base material of the surface-coated cutting tool, a multi-edged insert for cutting having the material and tool shape shown in Table 1 below (varied according to the method of evaluating each characteristic to be described below) was prepared , and the multi-edged blade (base material) is installed on the cathodic arc ion plating device.

Table 1

Successively, the pressure inside the chamber of the device was lowered by a vacuum pump, and the temperature of the base material was heated to 450° C. using a heater provided in the device. The chamber was evacuated until the pressure in the chamber reached 1.0 x 10 ^-4 Pa.

Thereafter, argon gas was introduced and the pressure in the chamber was maintained at 3.0 Pa. The voltage of the substrate bias power supply of the base material was gradually increased to -1500 V, and cleaning of the surface of the base material was performed for 15 minutes. Thereafter, the argon gas was consumed.

Then, a target composed of an alloy as a metal evaporation source was set so that Ti _0.5 Al _0.5 N was formed to a thickness of 3 μm while the coating film on the base material was in direct contact therewith. Nitrogen as an active gas was introduced, the temperature of the base material (substrate) was set to 450° C., the active gas pressure was set to 4.0 Pa, and the substrate bias voltage was changed as shown in Table 2 below. In this way, an arc current of 100 A was supplied to the cathode and metal ions were generated from the arc-type evaporation source, whereby the samples according to the present invention of Examples 1-6 having the intensity distributions of compressive stresses shown in Table 3 were produced. Surface coated cutting tools.

Table 2

The times in Table 2 above show the elapsed time since the start of evaporation of the metal ions from the target composed of the alloy. In addition, the value of the voltage in each table box shows the set of substrate bias voltages during the elapsed time as described above. For example, if a single value such as "-50V" is given, this indicates that the substrate bias voltage is constant over the elapsed time. Here, the compressive stress of the coating film is also maintained at a constant value. Meanwhile, if a range such as "-50V to -150V" is given, it means that the substrate bias voltage gradually increases from -50V to -150V at a constant speed in the elapsed time. Here, the compressive stress of the coating film gradually increases, and a relatively lowest point of compressive stress is formed at the point where the voltage starts to rise.

The substrate bias voltage is varied or set to a constant value with respect to elapsed time, so that a relative minimum point or section where the compressive stress remains constant can be formed in the intensity distribution of the compressive stress in the coating film.

table 3

No. Compressive stress at the surface first intermediate point relative lowest point Example 1 -5.0GPa 43.3% (1.3μm) -1.8GPa Example 2 -5.1GPa 43.3% (1.3μm) -3.0GPa Example 3 -5.0GPa 43.3% (1.3μm) -4.0GPa Example 4 -4.9GPa 16.7% (0.5μm) -3.0GPa Example 5 -5.2GPa 3.3% (0.1μm) -3.2GPa Example 6 -5.0GPa 1.0% (0.03μm) -2.9GPa

It should be noted that the values in the box of compressive stress on surface in Table 3 above give the highest compressive stress exhibited on the surface of the coating film. In addition, the value in the table box of the first intermediate point shows the distance from the surface of the coating film to the first intermediate point in the thickness direction of the coating film (the value shown in "%" is relative to the thickness of the coating film value, with an indication of "μm"). In addition, the values in the table boxes for the relative minimum points show the compressive stresses at that relative minimum point. This compressive stress remains constant toward the bottom surface of the coating film.

The surface-coated cutting tool according to the present invention in Examples 1 to 6 includes a base material and a coating film formed on the base material. The coating film acts as the outermost layer on the base material and has compressive stress. The compressive stress changes so as to have an intensity distribution in the thickness direction of the coating film, and the intensity distribution is characterized in that the highest compressive stress is reached on the surface of the coating film, and the compressive stress is from the surface of the coating film to the The first intermediate point between the bottom surfaces of the film continuously decreases and reaches a relative minimum at the first intermediate point, and the compressive stress maintains a constant value from the first intermediate point to the bottom surface of the coating film. That is, this intensity distribution shows the intensity distribution according to the first embodiment as described above.

For comparison purposes, a surface-coated cutting tool was fabricated in a similar manner, except for the following condition: the substrate bias voltage was uniformly increased from -20 V to -150 V for 60 minutes after metal ions started to evaporate from the alloy-composed target (Comparative Example 1).

In the surface-coated cutting tool according to Comparative Example 1, the intensity distribution of the compressive stress of the coating film had no relative minimum point and the compressive stress increased uniformly from the bottom surface of the coating film to the surface of the coating film.

<Embodiments 7 to 10>

<Manufacture of surface-coated cutting tools>

Initially, the same base material as that used in Examples 1 to 6 was used as the base material of the surface-coated cutting tool, and this base material was attached in a cathodic arc ion plating apparatus.

Successively, the pressure inside the chamber of the device was lowered by a vacuum pump, and the temperature of the base material was heated to 450° C. using a heater provided in the device. The chamber was evacuated until the pressure in the chamber reached 1.0 x 10 ^-4 Pa.

Thereafter, argon gas was introduced and the pressure in the chamber was maintained at 3.0 Pa. The voltage of the substrate bias power supply of the base material was gradually increased to -1500 V, and cleaning of the surface of the base material was performed for 15 minutes. Thereafter, the argon gas was consumed.

Then, a target composed of an alloy as a metal evaporation source was set so that Al _0.7 Cr _0.3 N was formed to a thickness of 3 μm when the coating film formed on the base material was in contact therewith. Nitrogen as an active gas was introduced, the temperature of the base material (substrate) was set to 450° C., the active gas pressure was set to 4.0 Pa, and the substrate bias voltage was changed as shown in Table 4 below. In this way, an arc current of 100 A was supplied to the cathode and metal ions were generated from the arc-type evaporation source, whereby the samples according to the present invention of Examples 7-10 having the intensity distributions of compressive stresses shown in Table 5 were produced. Surface coated cutting tools.

Table 4

As in Table 2, the times in Table 4 above show the elapsed time since evaporation of the metal ions from the target composed of the alloy began. In addition, as in Table 2, the numerical value of the voltage in each table box shows the corresponding substrate bias voltage group in the elapsed time as described above.

table 5

No. Compressive stress at the surface first intermediate point relative lowest point Example 7 -8.2GPa 3.3% (0.1μm) -1.8GPa Example 8 -6.0GPa 3.3% (0.1μm) -2.0GPa Example 9 -4.1GPa 3.3% (0.1μm) -2.1GPa Example 10 -3.3GPa 3.3% (0.1μm) -2.2GPa

It should be noted that, as in Table 3, the values in the box of compressive stress on surface in Table 5 above give the highest compressive stress exhibited on the surface of the coating film. In addition, as in Table 3, the numerical values in the table box of the first intermediate point also show the distance from the surface of the coating film to the first intermediate point in the thickness direction of the coating film (shown in "%") The numerical values are relative to the thickness of the coating film, with an indication of "μm") attached. In addition, as in Table 3, the value in the box relative to the lowest point also shows the compressive stress at that point. This compressive stress maintains a constant value toward the bottom surface of the coating film.

The surface-coated cutting tool according to the present invention in Examples 7 to 10 includes a base material and a coating film formed on the base material. The coating film acts as the outermost layer on the base material and has compressive stress. The compressive stress changes so as to have an intensity distribution in the thickness direction of the coating film, and the intensity distribution is characterized in that the highest compressive stress is reached on the surface of the coating film, and the compressive stress is from the surface of the coating film to the The first intermediate point between the bottom surfaces of the film continuously decreases and reaches a relative minimum at the first intermediate point, and the compressive stress maintains a constant value from the first intermediate point to the bottom surface of the coating film. That is, this intensity distribution shows the intensity distribution according to the first embodiment as described above.

For comparison purposes, surface-coated cutting tools were fabricated in a similar manner, except for the following conditions: after metal ions started to evaporate from the alloy-composed target, the substrate bias voltage increased uniformly from -20 V to -200 V in 60 minutes (comparative Example 2).

In the surface-coated cutting tool according to Comparative Example 2, the intensity distribution of the compressive stress of the coating film did not have a relative minimum point and the compressive stress increased uniformly from the bottom surface of the coating film to the surface of the coating film.

<Evaluation of wear resistance of surface-coated cutting tools>

Each of the surface-coated cutting tools according to Examples 1 to 10 and Comparative Examples 1 and 2 manufactured as described above was subjected to a continuous cutting test and wet interruption under the conditions shown in Table 1 above. cutting test. Then, the time when the flank wear width on the cutting edge exceeded 0.2 mm was measured as the cutting time.

Tables 6 and 7 show, as the evaluation results of the wear resistance of the surface-coated cutting tools, the cutting time measured by the method described above. As the cutting time becomes longer, wear resistance is excellent. In addition, in the continuous cutting test, the brightness on the machined surface of the material to be cut was also observed. Tables 6 and 7 likewise show the observed results. Here, "bright" means that the machined surface of the material to be cut has brightness, and "dark" means that the machined surface of the material to be cut has no brightness but is dark.

As can be clearly seen from Tables 6 and 7, in both the continuous cutting test and the interrupted cutting test, compared with the surface-coated cutting tools in Comparative Examples 1 and 2, it has been confirmed that in Examples The surface-coated cutting tools according to the invention in 1-10 achieve a further improved wear resistance, a gloss on the final surface and a further improved lifetime.

<Evaluation of Toughness of Coated Cutting Tools>

Each of the surface-coated cutting tools according to Examples 1 to 10 and Comparative Examples 1 and 2 manufactured as described above was subjected to a test for evaluating toughness under the conditions shown below.

Regarding the cutting conditions, specifically, as shown in the above Table 1, a block (300 mm long by 150 mm wide) including 50 through holes in the S50C material was used as the material to be cut. The dry grinding test was carried out under the following conditions: the cutting speed was set to 180m/min, the feed rate was set to increase from 0.10mm/cutting edge to 0.05mm/cutting edge, and the cutting depth (cutting) was set to 0.5mm. The feed rate was increased for every 300mm of cutting length.

Tables 6 and 7 show the results of toughness evaluation of cutting tools coated on each surface. With greater maximum feed rate, excellent toughness.

As can be clearly seen from Tables 6 and 7, compared with the surface-coated cutting tools in Comparative Examples 1 and 2, it has been confirmed that the surface-coated cutting tools according to the present invention in Examples 1-10 obtain improved toughness.

Table 6

Table 7

<Examples 11 to 16>

<Manufacture of surface-coated cutting tools>

Initially, as the base material of the surface-coated cutting tool, a multi-edged insert for cutting having the material and tool shape shown in the above Table 1 (varied according to the method of evaluating each characteristic to be described below) was prepared , and the multi-edged blade (base material) is installed on the cathodic arc ion plating device.

Successively, the pressure inside the chamber of the device was lowered by a vacuum pump, and the temperature of the base material was heated to 450° C. using a heater provided in the device. The chamber was evacuated until the pressure in the chamber reached 1.0 x 10 ^-4 Pa.

Thereafter, argon gas was introduced and the pressure in the chamber was maintained at 3.0 Pa. The voltage of the substrate bias power supply of the base material was gradually increased to -1500 V, and cleaning of the surface of the base material was performed for 15 minutes. Thereafter, the argon gas was consumed.

Then, a target composed of an alloy as a metal evaporation source was set so that Ti _0.5 Al _0.5 N was formed to a thickness of 3 μm when the coating film formed on the base material was in direct contact therewith. Nitrogen as an active gas was introduced, the temperature of the base material (substrate) was set to 450° C., the active gas pressure was set to 4.0 Pa, and the substrate bias voltage was changed as shown in Table 8 below. In this way, an arc current of 100 A was supplied to the cathode and metal ions were generated from the arc-type evaporation source, whereby Examples 11-16 according to the present invention were produced having the intensity distribution of compressive stress shown in Table 9 below. Surface coated cutting tools.

Table 8

The times in Table 8 above show the elapsed time since the start of evaporation of the metal ions from the target composed of the alloy. In addition, the value of the voltage in each table box shows the set of substrate bias voltages during the elapsed time as described above. For example, if a range is given like "-130V to -50V", this indicates that the substrate bias voltage gradually decreases from -130V to -50V at a constant speed during the elapsed time. Here, the compressive stress of the coating film gradually decreases. Meanwhile, if a range such as "-50V to -160V" is given, it means that the substrate bias voltage gradually increases from -50V to -160V at a constant speed during the elapsed time. Here, the compressive stress of the coating film gradually rises, and a relatively lowest point of the compressive stress is formed at the point where the voltage starts to rise.

The variation of the substrate bias voltage with respect to elapsed time can create relative nadir or continuous increases and decreases in the intensity distribution of compressive stress in the coating film.

Table 9

No. Compressive stress at the surface first intermediate point relative lowest point Compressive stress on the bottom surface Example 11 -5.5GPa 33.3% (1.0μm) -2.0GPa -4.6GPa Example 12 -5.6GPa 33.3% (1.0μm) -3.1GPa -4.5GPa Example 13 -5.4GPa 36.7% (1.1μm) -4.0GPa -4.4GPa Example 14 -5.5GPa 16.7% (0.5μm) -3.0GPa -4.5GPa Example 15 -5.6GPa 3.3% (0.1μm) -3.1GPa -4.5GPa Example 16 -5.5GPa 1.7% (0.05μm) -2.9GPa -4.6GPa

It should be noted that the values in the boxes of compressive stress on the surface and on the bottom surface of Table 9 above show the values shown on the surface of the coating film and on the bottom surface of the coating film, respectively. of compressive stress. In addition, the value in the table box of the first intermediate point shows the distance from the surface of the coating film to the first intermediate point in the thickness direction of the coating film (the value shown in "%" is relative to the thickness of the coating film value, with an indication of "μm"). In addition, the values in the table boxes for the relative minimum points show the compressive stresses at that relative minimum point.

The surface-coated cutting tool according to the present invention in Examples 11 to 16 includes a base material and a coating film formed on the base material. The coating film acts as the outermost layer on the base material and has compressive stress. The compressive stress changes so as to have an intensity distribution in the thickness direction of the coating film, and the intensity distribution is characterized in that the compressive stress on the surface of the coating film goes from the surface of the coating film to the area between the surface of the coating film and the bottom surface of the coating film. The first intermediate point decreases continuously and the compressive stress reaches a relatively lowest point at the first intermediate point, and the compressive stress increases continuously from the first intermediate point to the bottom surface of the coating film. That is, this intensity distribution shows the intensity distribution according to the second embodiment as described above.

For comparative purposes, a surface-coated cutting tool was fabricated in a similar manner, except that the substrate bias voltage was raised from -20 V to -150 V in 60 minutes after metal ions started to evaporate from the alloy-composed target (Comparative Example 3).

In the surface-coated cutting tool according to Comparative Example 3, the intensity distribution of the compressive stress of the coating film had no relative minimum point and the compressive stress increased uniformly from the bottom surface of the coating film to the surface of the coating film.

<Embodiments 17 to 20>

<Manufacture of surface-coated cutting tools>

Initially, the same base material as that used in Examples 11 to 16 was used as the base material of the surface-coated cutting tool, and this base material was attached in a cathodic arc ion plating apparatus.

Successively, the pressure inside the chamber of the device was lowered by a vacuum pump, and the temperature of the base material was heated to 450° C. using a heater provided in the device. The chamber was evacuated until the pressure in the chamber reached 1.0 x 10 ^-4 Pa.

Thereafter, argon gas was introduced and the pressure in the chamber was maintained at 3.0 Pa. The voltage of the substrate bias power supply of the base material was gradually increased to -1500 V, and cleaning of the surface of the base material was performed for 15 minutes. Thereafter, the argon gas was consumed.

Then, a target composed of an alloy as a metal evaporation source was set so that Al _0.6 Ti _0.35 Cr _0.15 N was formed to a thickness of 3 μm when the coating film formed on the base material was in direct contact therewith. Nitrogen as an active gas was introduced, the temperature of the base material (substrate) was set to 450° C., the active gas pressure was set to 4.0 Pa, and the substrate bias voltage was changed as shown in Table 10 below. In this way, an arc current of 100 A was supplied to the cathode and metal ions were generated from the arc-type evaporation source, whereby Examples 17-20 according to the present invention were produced having the intensity distribution of compressive stress shown in Table 11 below. Surface coated cutting tools.

Table 10

As in Table 8, the times in Table 10 above show the elapsed time since evaporation of the metal ions from the target composed of the alloy began. In addition, as in Table 8, the numerical value of the voltage in each table box shows the set of substrate bias voltages during the elapsed time as described above.

Table 11

No. Compressive stress at the surface first intermediate point relative lowest point Compressive stress on the bottom surface Example 17 -8.0GPa 3.3% (0.1μm) -3.0GPa -4.5GPa Example 18 -6.8GPa 3.3% (0.1μm) -3.1GPa -4.3GPa Example 19 -4.6GPa 3.3% (0.1μm) -3.2GPa -4.4GPa Example 20 -3.5GPa 3.3% (0.1μm) -3.0GPa -4.3GPa

It should be noted that, as in Table 9, the values in the boxes for compressive stress on the surface and on the bottom in Table 11 above give The compressive stress exhibited on the bottom surface of the membrane. In addition, as in Table 9, the numerical values in the table box of the first intermediate point also show the distance from the surface of the coating film to the first intermediate point in the thickness direction of the coating film (shown in "%") The numerical values are relative to the thickness of the coating film, and are marked with "μm"). In addition, as in Table 9, the value in the box relative to the lowest point also shows the compressive stress at that point.

The surface-coated cutting tool according to the present invention in Examples 17 to 20 includes a base material and a coating film formed on the base material. The coating film acts as the outermost layer on the base material and has compressive stress. The compressive stress changes so as to have an intensity distribution in the thickness direction of the coating film, and the intensity distribution is characterized in that the compressive stress on the surface of the coating film goes from the surface of the coating film to the area between the surface of the coating film and the bottom surface of the coating film. The first intermediate point decreases continuously and the compressive stress reaches a relatively lowest point at the first intermediate point, and the compressive stress increases continuously from the first intermediate point to the bottom surface of the coating film. That is, this intensity distribution shows the intensity distribution according to the second embodiment as described above.

For comparison purposes, a surface-coated cutting tool was fabricated in a similar manner except that the substrate bias voltage was maintained at -75 V for 60 minutes after metal ions started to evaporate from the alloy-composed target (Comparative Example 4).

In the surface-coated cutting tool according to Comparative Example 4, there was no intensity distribution of compressive stress of the coating film and the compressive stress was constant from the bottom surface of the coating film to the surface of the coating film.

<Evaluation of wear resistance of surface-coated cutting tools>

Each of the surface-coated cutting tools according to Examples 11 to 20 and Comparative Examples 3 and 4 manufactured as described above were subjected to continuous cutting tests and wet interruption tests under the conditions shown in Table 1 above. cutting test. Then, the time when the flank wear width on the cutting edge exceeded 0.2 mm was measured as the cutting time.

Tables 12 and 13 show, as the evaluation results of the wear resistance of the surface-coated cutting tools, the cutting time measured by the method described above. As the cutting time becomes longer, wear resistance is excellent. In addition, in the continuous cutting test, the brightness on the machined surface of the material to be cut was also observed. Tables 12 and 13 likewise present the observations. Here, "bright" means that the machined surface of the material to be cut has brightness, and "dark" means that the machined surface of the material to be cut has no brightness but is dark.

As can be clearly seen from Tables 12 and 13, in both the continuous cutting test and the interrupted cutting test, compared with the surface-coated cutting tools in Comparative Examples 3 and 4, it has been confirmed that in Examples The surface-coated cutting tools according to the present invention in 11-20 achieved further improved wear resistance, had brightness on the machined surface, achieved excellent resistance to chipping of the film layer and further improved life.

<Evaluation of Toughness of Coated Cutting Tools>

Each of the surface-coated cutting tools according to Examples 11 to 20 and Comparative Examples 3 and 4 manufactured as described above was subjected to a test for evaluating toughness under the conditions shown below.

Regarding the cutting conditions, specifically, as shown in the above Table 1, a block (300 mm long by 150 mm wide) including 50 through holes in the S50C material was used as the material to be cut. The dry grinding test was carried out under the following conditions: the cutting speed was set to 180m/min, the cutting depth (cutting) was set to 2.0mm, and the feed rate was set to increase from 0.10mm/cutting edge by 0.05mm/cutting edge (for per 300mm cutting length).

Tables 12 and 13 show the results of toughness evaluation of cutting tools coated on each surface. With greater maximum feed rate, excellent toughness.

As can be clearly seen from Tables 12 and 13, compared with the surface-coated cutting tools in Comparative Examples 3 and 4, it has been confirmed that the surface-coated cutting tools according to the present invention in Examples 11-20 obtain improved toughness.

Table 12

Table 13

<Examples 21 to 26>

<Manufacture of surface-coated cutting tools>

Initially, as the base material of the surface-coated cutting tool, a multi-edged insert for cutting having the material and tool shape shown in the above Table 1 (varied according to the method of evaluating each characteristic to be described below) was prepared , and the multi-edged blade (base material) is installed on the cathodic arc ion plating device.

Successively, the pressure inside the chamber of the device was lowered by a vacuum pump, and the temperature of the base material was heated to 450° C. using a heater provided in the device. The chamber was evacuated until the pressure in the chamber reached 1.0 x 10 ^-4 Pa.

Thereafter, argon gas was introduced and the pressure in the chamber was maintained at 3.0 Pa. The voltage of the substrate bias power supply of the base material was gradually increased to -1500 V, and cleaning of the surface of the base material was performed for 15 minutes. Thereafter, the argon gas was consumed.

Then, a target composed of an alloy as a metal evaporation source was set so that Ti _0.5 Al _0.5 N was formed to a thickness of 3 μm when the coating film formed on the base material was in direct contact therewith. Nitrogen gas was introduced as an active gas, the temperature of the base material (substrate) was set to 450° C., the active gas pressure was set to 4.0 Pa, and the substrate bias voltage was changed as shown in Table 14 below. In this way, an arc current of 100 A was supplied to the cathode and metal ions were generated from the arc-type evaporation source, whereby Examples 21-26 according to the present invention were produced having the intensity distribution of compressive stress shown in Table 15 below. Surface coated cutting tools.

Table 14

The times in Table 14 above show the elapsed time since the start of evaporation of the metal ions from the target composed of the alloy. In addition, the value of the voltage in each table box shows the set of substrate bias voltages during the elapsed time as described above. For example, if a range such as "-30V to -130V" is given, this indicates that the substrate bias voltage gradually increases from -30V to -130V at a constant speed in elapsed time. Here, the compressive stress of the coating film gradually increases. Meanwhile, if a range such as "-130V to -50V" is given, it means that the substrate bias voltage gradually decreases from -130V to -50V at a constant speed in the elapsed time. Here, the compressive stress of the coating film gradually decreases. A relative maximum and a relative minimum of compressive stress are formed at the point at which the increase in voltage transitions to a decrease and at the point at which the decrease in voltage transitions into an increase, respectively.

The variation of the substrate bias voltage with respect to the elapsed time can form relative peaks and relative minimums or continuously increase or decrease in the intensity distribution of the compressive stress in the coating film.

Table 15

No. Compressive stress at the surface first intermediate point relative lowest point second intermediate point relative highest point Compressive stress on the bottom surface Example 21 -5.4GPa 36.7% (1.1μm) -2.1GPa 50.0% (1.5μm) -4.5GPa -0.9GPa Example 22 -5.6GPa 33.3% (1.0μm) -3.0GPa 50.0% (1.5μm) -4.6GPa -1.0GPa Example 23 -5.5GPa 33.3% (1.0μm) -4.1GPa 53.3% (1.6μm) -4.5GPa -1.0GPa Example 24 -5.5GPa 16.7% (0.5μm) -3.0GPa 50.0% (1.5μm) -4.4GPa -1.1GPa Example 25 -5.6GPa 3.3% (0.1μm) -3.0GPa 46.7% (1.4μm) -4.5GPa -1.0GPa Example 26 -5.5GPa 1.7% (0.05μm) -3.1GPa 50.0% (1.5μm) -4.5GPa -0.9GPa

It should be noted that the values in the table boxes of compressive stress on the surface and on the bottom surface in Table 15 above show the values shown on the surface of the coating film and on the bottom surface of the coating film, respectively. of compressive stress. In addition, the numerical values in the table frame of the first intermediate point and the numerical values in the table frame of the second intermediate point show the thickness direction of the coating film from the surface of the coating film to the first intermediate point and to the second intermediate point, respectively. (The value shown in "%" is relative to the thickness of the coating film, with an indication of "μm"). In addition, the values in the table boxes for relative lowest point and in the table box for relative highest point show the compressive stress at the relative lowest point and the relative highest point, respectively.

The surface-coated cutting tool according to the present invention in Examples 21 to 26 includes a base material and a coating film formed on the base material. The coating film acts as the outermost layer on the base material and has compressive stress. The compressive stress changes so as to have an intensity distribution in the thickness direction of the coating film, and the intensity distribution is characterized in that the compressive stress on the surface of the coating film goes from the surface of the coating film to the area between the surface of the coating film and the bottom surface of the coating film. The first intermediate point decreases continuously and the compressive stress reaches a relatively lowest point at the first intermediate point, and the compressive stress increases continuously from the first intermediate point to a second intermediate point located between the first intermediate point and the bottom surface of the coating film , reaches a relatively highest point at the second intermediate point, and decreases continuously from the second intermediate point to the bottom surface of the coating film. That is, this intensity distribution shows the intensity distribution according to the third embodiment as described above.

For comparison purposes, a surface-coated cutting tool was fabricated in a similar manner, except that the substrate bias voltage was raised from -20 V to -150 V in 60 minutes after metal ions started to evaporate from the alloy-composed target (Comparative Example 5 ).

In the surface-coated cutting tool according to Comparative Example 5, the intensity distribution of the compressive stress of the coating film has neither a relative minimum point nor a relative maximum point, and the compressive stress increases uniformly from the bottom surface of the coating film to the surface of the coating film big.

<Examples 27 to 30>

<Manufacture of surface-coated cutting tools>

Initially, the same base material as that used in Examples 21 to 26 was used as the base material of the surface-coated cutting tool, and this base material was attached in a cathodic arc ion plating apparatus.

Successively, the pressure inside the chamber of the device was lowered by a vacuum pump, and the temperature of the base material was heated to 450° C. using a heater provided in the device. The chamber was evacuated until the pressure in the chamber reached 1.0 x 10 ^-4 Pa.

Thereafter, argon gas was introduced and the pressure in the chamber was maintained at 3.0 Pa. The voltage of the substrate bias power supply of the base material was gradually increased to -1500 V, and cleaning of the surface of the base material was performed for 15 minutes. Thereafter, the argon gas was consumed.

Then, a target composed of an alloy as a metal evaporation source was set so that Al _0.6 Ti _0.3 Si _0.1 N was formed to a thickness of 3 μm when the coating film formed on the base material was in direct contact therewith. Nitrogen gas was introduced as an active gas, the temperature of the base material (substrate) was set to 450° C., the active gas pressure was set to 4.0 Pa, and the substrate bias voltage was changed as shown in Table 16 below. In this way, an arc current of 100 A was supplied to the cathode and metal ions were generated from the arc-type evaporation source, whereby Examples 27-30 according to the present invention were produced having the intensity distribution of compressive stress shown in Table 17 below. Surface coated cutting tools.

Table 16

As in Table 14, the times in Table 16 above show the elapsed time since evaporation of the metal ions from the target composed of the alloy began. In addition, as in Table 14, the numerical value of the voltage in each table box shows the set of substrate bias voltages during the elapsed time as described above.

Table 17

No. compressive stress at the surface first intermediate point relative lowest point second intermediate point Relative highest point Compressive stress at the bottom surface Example 27 -5.5GPa 3.3% (0.1μm) -3.1GPa 50.0% (1.5μm) -4.0GPa -1.0GPa Example 28 -5.5GPa 3.3% (0.1μm) -3.0GPa 46.7% (1.4μm) -5.5GPa -1.0GPa Example 29 -5.4GPa 3.3% (0.1μm) -3.0GPa 50.0% (1.5μm) -6.5GPa -0.9GPa Example 30 -5.6GPa 3.3% (0.1μm) -3.2GPa 53.3% (1.6μm) -8.0GPa -1.0GPa

It should be noted that, as in Table 15, the values in the boxes for compressive stress on the surface and on the bottom surface in Table 17 above give The compressive stress exhibited on the bottom surface of the membrane. In addition, as in Table 15, the values in the frame of the first intermediate point and the values in the frame of the second intermediate point also show the distance from the surface of the coating film to each intermediate point in the thickness direction of the coating film. (The value shown in "%" is relative to the thickness of the coating film, with an indication of "μm"). In addition, as in Table 15, the numerical values in the box of the relative lowest point and the box of the relative highest point also show the compressive stress at these points respectively.

The surface-coated cutting tool according to the present invention in Examples 27 to 30 includes a base material and a coating film formed on the base material. The coating film acts as the outermost layer on the base material and has compressive stress. The compressive stress changes so as to have an intensity distribution in the thickness direction of the coating film, and the intensity distribution is characterized in that the compressive stress on the surface of the coating film goes from the surface of the coating film to the area between the surface of the coating film and the bottom surface of the coating film. The first intermediate point decreases continuously and the compressive stress reaches a relatively lowest point at the first intermediate point, and the compressive stress increases continuously from the first intermediate point to a second intermediate point located between the first intermediate point and the bottom surface of the coating film , reaches a relatively highest point at the second intermediate point, and increases continuously from the second intermediate point to the bottom surface of the coating film. That is, this intensity distribution shows the intensity distribution according to the third embodiment as described above.

For comparison purposes, a surface-coated cutting tool was fabricated in a similar manner except that the substrate bias voltage was maintained at -70 V for 60 minutes after metal ions started to evaporate from the alloy-composed target (Comparative Example 6).

In the surface-coated cutting tool according to Comparative Example 6, there was no intensity distribution of the compressive stress of the coating film, and the compressive stress was kept constant from the bottom surface of the coating film to the surface of the coating film.

<Evaluation of wear resistance of surface-coated cutting tools>

Each of the surface-coated cutting tools according to Examples 21 to 30 and Comparative Examples 5 and 6 manufactured as described above received wet (water-soluble emulsion) under the conditions shown in Table 1 above. Continuous cutting test and wet interrupt cutting test. Then, the time when the flank wear width on the cutting edge exceeded 0.20 mm was measured as the cutting time.

Tables 18 and 19 show, as the evaluation results of the wear resistance of the surface-coated cutting tools, the cutting time measured by the method described above. As the cutting time becomes longer, wear resistance is excellent. In addition, in the continuous cutting test, the brightness on the machined surface of the material to be cut was also observed. Tables 18 and 19 likewise present the observations. Here, "bright" means that the machined surface of the material to be cut has brightness, and "dark" means that the machined surface of the material to be cut has no brightness but is dark.

As can be clearly seen from Tables 18 and 19, in both the continuous cutting test and the interrupted cutting test, compared with the surface-coated cutting tools in Comparative Examples 5 and 6, it has been confirmed that in Examples The surface-coated cutting tools according to the present invention in 21-30 obtained further improved wear resistance, had brightness on the machined surface, obtained excellent resistance to chipping of the film layer, and further improved life .

<Evaluation of toughness of surface-coated cutting tools>

Each of the surface-coated cutting tools according to Examples 21 to 30 and Comparative Examples 5 and 6 manufactured as described above was subjected to a test for evaluating toughness under the conditions shown below.

Regarding the cutting conditions, specifically, as shown in the above Table 1, a block (300 mm long by 150 mm wide) including 50 through holes in the S50C material was used as the material to be cut. The dry grinding test was carried out under the following conditions: the cutting speed was set to 180m/min, the cutting depth (cutting) was set to 2.0mm, and the feed rate was set to increase from 0.10mm/cutting edge by 0.05mm/cutting edge (for per 300mm cutting length).

Tables 18 and 19 show the results of toughness evaluation of cutting tools coated on each surface. Excellent toughness due to higher maximum feed rate.

As can be clearly seen from Tables 18 and 19, compared with the surface-coated cutting tools in Comparative Examples 5 and 6, it has been confirmed that the surface-coated cutting tools according to the present invention in Examples 21-30 obtain improved toughness.

Table 18

Table 19

<Examples 31 to 36>

<Manufacture of surface-coated cutting tools>

Initially, as the base material of the surface-coated cutting tool, a multi-edged insert for cutting having the material and tool shape shown in the above Table 1 (varied according to the method of evaluating each characteristic to be described below) was prepared , and the multi-edged blade (base material) is installed on the cathodic arc ion plating device.

Successively, the pressure inside the chamber of the device was lowered by a vacuum pump, and the temperature of the base material was heated to 450° C. using a heater provided in the device. The chamber was evacuated until the pressure in the chamber reached 1.0 x 10 ^-4 Pa.

Thereafter, argon gas was introduced and the pressure in the chamber was maintained at 3.0 Pa. The voltage of the substrate bias power supply of the base material was gradually increased to -1500 V, and cleaning of the surface of the base material was performed for 15 minutes. Thereafter, the argon gas was consumed.

Then, a target composed of an alloy as a metal evaporation source was set so that Ti _0.5 Al _0.5 N was formed to a thickness of 3 μm when the coating film formed on the base material was in direct contact therewith. Nitrogen as an active gas was introduced, the temperature of the base material (substrate) was set to 450° C., the active gas pressure was set to 4.0 Pa, and the substrate bias voltage was changed as shown in Table 20 below. In this way, an arc current of 100 A was supplied to the cathode for 60 minutes and metal ions were generated from an arc-type evaporation source, whereby samples of Examples 31-36 having the intensity distribution of compressive stress shown in Table 21 below were produced. Surface-coated cutting tool according to the invention.

Table 20

No. First cycle (time/substrate bias voltage) Second cycle (time/substrate bias voltage) Example 31 15 minutes -150V to -50V 15 minutes -50V to -150V Example 32 5 minutes -150V to -50V 5 minutes -50V to -150V Example 33 1 minute -150V to -50V 1 minute -50V to -150V Example 34 1 minute -150V to -50V 2 minutes -50V to -150V Example 35 12 minutes -20V to -210V 12 minutes -210V to -20V Example 36 12 minutes -75V to -150V 12 minutes -150V to -75V

"First cycle" and "second cycle" in Table 20 above indicate that the substrate bias voltage was applied as a result of alternately repeating (up to 60 minutes) these cycles lasting between the frame of the first cycle and the second cycle The length of time indicated in the table box of (the period begins with "Period 1", however, does not necessarily end with "Period 2"). That is, the time in each frame of the cycle shows the elapsed time during which metal ions evaporate from the target composed of the alloy. The value of the voltage in each box shows the set of substrate bias voltages during the elapsed time as described above. For example, if a range such as "-150V to -50V" is given, it means that the substrate bias voltage gradually decreases from -150V to -50V at a constant speed in the elapsed time. Here, the compressive stress of the coating film gradually decreases. Meanwhile, if a range such as "-50V to -150V" is given, it means that the substrate bias voltage gradually increases from -50V to -150V at a constant speed in the elapsed time. Here, the compressive stress of the coating film gradually increases. At the point where the drop in voltage transitions to an increase (i.e. at the point where the transition from the "first period" to the "second period") and at the point where the increase in voltage transitions to a decrease (i.e. at the point where the transition from the " At the point where the "second cycle" is converted into the "first cycle"), the relative minimum and relative maximum points of compressive stress are formed.

The variation of the substrate bias voltage with respect to the elapsed time can form relative peaks and relative minimums or continuously increase or decrease in the intensity distribution of the compressive stress in the coating film.

It should be noted that the values in the boxes of compressive stress on the surface and on the bottom surface of Table 21 above show the values shown on the surface of the coating film and on the bottom surface of the coating film, respectively. of compressive stress. In addition, the numerical values in the table frame of the first intermediate point and the numerical values in the table frame of the second intermediate point show the thickness direction of the coating film from the surface of the coating film to the first intermediate point and to the second intermediate point, respectively. (The value shown in "%" is relative to the thickness of the coating film, with an indication of "μm"). In addition, the values in the table boxes for the relative lowest point and the table boxes for the relative highest point show the compressive stress at the relative lowest point and the relative highest point respectively (although the value is shown as a range, it can be assumed that the compressive stress reaches any substantially the same value in this range). In addition, the relative minimum point count/distance and the relative maximum point count/distance represent the numbers of relative minimum points and relative maximum points occurring between the surface of the coating film and the bottom surface of the coating film, respectively, and the number of relative minimum points between the relative minimum points. Distance and distance between relative highest points.

The surface-coated cutting tools according to the present invention in Examples 31 to 36 include a base material and a coating film formed on the base material. The coating film acts as the outermost layer on the base material and has compressive stress. The compressive stress changes so as to have an intensity distribution in the thickness direction of the coating film, and the intensity distribution is characterized in that the compressive stress on the surface of the coating film goes from the surface of the coating film to the area between the surface of the coating film and the bottom surface of the coating film. The first intermediate point continuously decreases and the compressive stress reaches a relatively lowest point at the first intermediate point, and the compressive stress increases continuously from the first intermediate point to a second intermediate point located between the first intermediate point and the bottom surface of the coating film and A relative maximum is reached at the second intermediate point, and the intensity distribution has one or more similar relative minimums and one or more similar relative maximums between the second intermediate point and the bottom surface of the coating film. These relative minimums and relative maximums exist alternately and repeatedly in this order. In various embodiments, the compressive stress at each relatively lowest point reaches substantially the same value and the compressive stress at each relatively highest point reaches substantially the same value. The relative lowest points or the relative highest points exist at substantially equal intervals. That is, this intensity distribution shows an exemplary intensity distribution according to the fourth embodiment as described above.

For comparison purposes, surface-coated cutting tools were fabricated in a similar manner, except that the substrate bias voltage was uniformly increased from -20 V to -150 V in 60 minutes after metal ions started to evaporate from the alloy-composed target (comparison Example 7).

In the surface-coated cutting tool according to Comparative Example 7, the intensity distribution of the compressive stress of the coating film had neither a relative lowest point nor a relative highest point, and the compressive stress increased uniformly from the bottom surface of the coating film to the surface of the coating film .

<Examples 37 to 40>

<Manufacture of surface-coated cutting tools>

Initially, the same base material as that used in Examples 31 to 36 was used as the base material of the surface-coated cutting tool, and this base material was attached in a cathodic arc ion plating apparatus.

Successively, the pressure inside the chamber of the device was lowered by a vacuum pump, and the temperature of the base material was heated to 450° C. using a heater provided in the device. The chamber was evacuated until the pressure in the chamber reached 1.0 x 10 ^-4 Pa.

Thereafter, argon gas was introduced and the pressure in the chamber was maintained at 3.0 Pa. The voltage of the substrate bias power supply of the base material was gradually increased to -1500 V, and cleaning of the surface of the base material was performed for 15 minutes. Thereafter, the argon gas was consumed.

Then, a target composed of an alloy as a metal evaporation source was set so that Al _0.6 Ti _0.2 Si _0.1 Cr _0.1 N was formed to a thickness of 3 μm when the coating film formed on the base material was in direct contact therewith. Nitrogen gas was introduced as an active gas, the temperature of the base material (substrate) was set to 450° C., the active gas pressure was set to 4.0 Pa, and the substrate bias voltage was changed as shown in Table 22 below. In this way, an arc current of 100 A was supplied to the cathode for 60 minutes and metal ions were generated from an arc-type evaporation source, whereby samples of Examples 37-40 having an intensity distribution of compressive stress shown in Table 23 below were produced. Surface-coated cutting tool according to the invention.

Table 22

No. First cycle (time/substrate bias voltage) Second cycle (time/substrate bias voltage) Example 37 5 minutes -210V to -20V 5 minutes -20V to -210V Example 38 5 minutes -210V to -60V 5 minutes -60V to -210V Example 39 5 minutes -210V to -100V 5 minutes -100V to -210V Example 40 5 minutes -210V to -150V 5 minutes -150V to -210V

As in Table 20, "first cycle" and "second cycle" in Table 22 above indicate that the substrate bias voltage was applied as a result of alternately repeating (up to 60 minutes) these cycles, which lasted for the first cycle The length of time shown in the table boxes for and the second period (the period begins with "first period"). In addition, as in Table 20, the values of time and voltage in each table box show the set of substrate bias voltages in elapsed time.

It should be noted that, as in Table 21, the values in the boxes for the compressive stress on the surface and the box for the compressive stress on the bottom in Table 23 above give the The compressive stress exhibited on the bottom surface of the membrane. In addition, as in Table 21, the numerical values in the frame of the first intermediate point and the numerical values in the frame of the second intermediate point also show the distance from the surface of the coating film to each intermediate point in the thickness direction of the coating film. (The value shown in "%" is relative to the thickness of the coating film, with an indication of "μm"). In addition, as in Table 21, the values in the boxes for the relative lowest points and the boxes for the relative highest points also show the compressive stresses at these points respectively (although the values are shown as a range, it can be It is assumed that the compressive stress reaches any substantially the same value within this range). In addition, as in Table 21, the relative lowest point count/distance and the relative highest point count/distance respectively represent the numbers of relative lowest points and relative highest points occurring between the surface of the coating film and the bottom surface of the coating film, and The distance between the relative lowest points and the distance between the relative highest points.

The surface-coated cutting tool according to the present invention in Examples 37 to 40 includes a base material and a coating film formed on the base material. The coating film acts as the outermost layer on the base material and has compressive stress. The compressive stress changes so as to have an intensity distribution in the thickness direction of the coating film, and the intensity distribution is characterized in that the compressive stress on the surface of the coating film goes from the surface of the coating film to the area between the surface of the coating film and the bottom surface of the coating film. The first intermediate point continuously decreases and the compressive stress reaches a relatively lowest point at the first intermediate point, and the compressive stress increases continuously from the first intermediate point to a second intermediate point located between the first intermediate point and the bottom surface of the coating film and A relative maximum is reached at the second intermediate point, and the intensity distribution has one or more similar relative minimums and one or more similar relative maximums between the second intermediate point and the bottom surface of the coating film. These relative minimums and relative maximums exist alternately and repeatedly in this order. In various embodiments, the compressive stress at each relatively lowest point reaches substantially the same value and the compressive stress at each relatively highest point reaches substantially the same value. The relative lowest points or the relative highest points exist at substantially equal intervals. That is, this intensity distribution shows an exemplary intensity distribution according to the fourth embodiment as described above.

For comparison purposes, a surface-coated cutting tool was fabricated in a similar manner except that the substrate bias voltage was maintained at -75 V for 60 minutes after metal ions started to evaporate from the alloy-composed target (Comparative Example 8).

In the surface-coated cutting tool according to Comparative Example 8, there was no intensity distribution of the compressive stress of the coating film, and the compressive stress was constant from the bottom surface of the coating film to the surface of the coating film.

<Evaluation of wear resistance of surface-coated cutting tools>

Each of the surface-coated cutting tools according to Examples 31 to 40 and Comparative Examples 7 and 8 manufactured as described above received wet (water-soluble emulsion) under the conditions shown in Table 1 above. Continuous cutting test and wet interrupt cutting test. Then, the time when the flank wear width on the cutting edge exceeded 0.20 mm was measured as the cutting time.

Tables 24 and 25 show, as the evaluation results of the wear resistance of the surface-coated cutting tools, the cutting time measured by the method described above. As the cutting time becomes longer, wear resistance is excellent. In addition, in the continuous cutting test, the brightness on the machined surface of the material to be cut was also observed. Tables 24 and 25 similarly present the observations. Here, "bright" means that the machined surface of the material to be cut has brightness, and "dark" means that the machined surface of the material to be cut has no brightness but is dark.

As can be clearly seen from Tables 24 and 25, in both the continuous cutting test and the interrupted cutting test, compared with the surface-coated cutting tools in Comparative Examples 7 and 8, it has been confirmed that in the examples The surface-coated cutting tools according to the invention in 31-40 achieve further improved wear resistance, have a brilliance on the machined surface, achieve excellent resistance to chipping of the film layer, and further improve life .

<Evaluation of toughness of surface-coated cutting tools>

Each of the surface-coated cutting tools according to Examples 31 to 40 and Comparative Examples 7 and 8 manufactured as described above was subjected to a test for evaluating toughness under the conditions shown below.

Regarding the cutting conditions, specifically, as shown in the above Table 1, a block (300 mm long by 150 mm wide) including 50 through holes in the S50C material was used as the material to be cut. The dry grinding test was carried out under the following conditions: the cutting speed was set to 180m/min, the cutting depth (cutting) was set to 2.0mm, and the feed rate was set to increase from 0.10mm/cutting edge by 0.05mm/cutting edge (for per 300mm cutting length).

Tables 24 and 25 show the results of toughness evaluation of each surface-coated cutting tool. With greater maximum feed rate, excellent toughness.

As can be clearly seen from Tables 24 and 25, compared with the surface-coated cutting tools in Comparative Examples 7 and 8, it has been confirmed that the surface-coated cutting tools according to the present invention in Examples 31-40 obtain improved toughness.

Table 24

Table 25

The embodiments and examples disclosed above are for the purpose of illustration but not limitation. The spirit and scope of the present invention are not limited by the above embodiments and examples but by the claims and are intended to be included in the claims All improvements and changes in .

Claims (32)

1. surface coating cutting tool (1) comprising:

Basic material (2); With

Go up film (3) that form at described basic material (2); Wherein

These film (3) are as the outermost layer on described basic material (2) and have compression stress,

This compression stress changes so that have intensity distributions on the thickness direction of described filming (3), and

This intensity distributions is characterised in that: described compression stress of filming lowers continuously from described described surface (4) of filming towards being positioned at described described surface (4) of filming and first intermediate point (5) between the described bottom surface of filming (6), and this compression stress locates to reach relative minimum point at described first intermediate point (5).

2. according to the surface coating cutting tool (1) of claim 1, wherein

Described intensity distributions is characterised in that: locate to reach maximal pressure stress under compression and this compression stress on described described surface (4) of filming and keep steady state value from described first intermediate point (5) to described described bottom surface (6) of filming.

3. according to the surface coating cutting tool (1) of claim 2, wherein

Described compression stress be from least-stress of 15GPa in the 0GPa scope at the most.

4. according to the surface coating cutting tool (1) of claim 2, wherein

Described first intermediate point (5) be positioned at described described surface (4) of filming apart be equivalent to described filming (3) thickness at least 0.1% to the position of 50% distance at the most.

5. according to the surface coating cutting tool (1) of claim 2, wherein

The described compression stress of locating at described first intermediate point (5) is set to the value of the 20-90% that is equivalent to the compression stress located on described described surface (4) of filming.

6. according to the surface coating cutting tool (1) of claim 5, wherein

The described compression stress of locating at described first intermediate point (5) is set to the value of the 40-80% that is equivalent to the compression stress located on described described surface (4) of filming.

7. according to the surface coating cutting tool (1) of claim 1, wherein

Described intensity distributions is characterised in that: described compression stress increases towards described described bottom surface (6) of filming continuously from described first intermediate point (5).

8. according to the surface coating cutting tool (1) of claim 7, wherein

Described compression stress be from least-stress of 15GPa in the 0GPa scope at the most.

9. according to the surface coating cutting tool (1) of claim 7, wherein

Described first intermediate point (5) be positioned at described described surface (4) of filming at a distance of the thickness of described filming (3) at least 0.1% to the position of 50% distance at the most.

10. according to the surface coating cutting tool (1) of claim 7, wherein

Described compression stress locates to reach peak on described described surface (4) of filming.

11. according to the surface coating cutting tool (1) of claim 7, wherein

The described compression stress of locating at described first intermediate point (5) is set to the value of the 20-90% that is equivalent to the compression stress located on described described surface (4) of filming.

12. according to the surface coating cutting tool (1) of claim 11, wherein

The described compression stress of locating at described first intermediate point (5) is set to the value of the 40-80% that is equivalent to the compression stress located on described described surface (4) of filming.

13. according to the surface coating cutting tool (1) of claim 1, wherein

Described intensity distributions is characterised in that: described compression stress increases continuously and reaches relative peak at described second intermediate point (9) towards being positioned at second intermediate point (9) between described first intermediate point (5) and the described described bottom surface (6) of filming from described first intermediate point (5).

14. according to the surface coating cutting tool (1) of claim 13, wherein

Described compression stress be at least-stress of 15GPa in the 0GPa scope at the most.

15. according to the surface coating cutting tool (1) of claim 13, wherein

Described first intermediate point (5) be positioned at described described surface (4) of filming at a distance of described filming (3) thickness at least 0.1% to the position of 50% distance at the most.

16. according to the surface coating cutting tool (1) of claim 13, wherein

Described second intermediate point (9) be positioned at described described surface (4) of filming at a distance of described filming (3) thickness at least 0.2% to the position of 95% distance at the most.

17. according to the surface coating cutting tool (1) of claim 13, wherein

Described compression stress locates to reach peak on described described surface (4) of filming.

18. according to the surface coating cutting tool (1) of claim 13, wherein

The described compression stress of locating at described first intermediate point (5) is set to the value of the 20-90% that is equivalent to the compression stress located on described described surface (4) of filming.

19. according to the surface coating cutting tool (1) of claim 18, wherein

The described compression stress of locating at described first intermediate point (5) is set to the value of the 40-80% that is equivalent to the compression stress located on described described surface (4) of filming.

20. according to the surface coating cutting tool (1) of claim 1, wherein

Described intensity distributions is characterised in that: described compression stress increases continuously with second intermediate point (9) between the described described bottom surface (6) of filming and reaches relative peak at described second intermediate point (9) towards being positioned at described first intermediate point (5) from described first intermediate point (5), and this intensity distributions has one or more similar described relative minimum points between described second intermediate point (9) and described described bottom surface (6) of filming.

21. according to the surface coating cutting tool (1) of claim 20, wherein

Described intensity distributions has one or more similar described relative peaks between described second intermediate point (9) and described described bottom surface (6) of filming.

22. according to the surface coating cutting tool (1) of claim 20, wherein

Described intensity distributions has one or more described similar relative minimum points and one or more described similar relative peaks between described second intermediate point (9) and described described bottom surface (6) of filming, described relative minimum point and relative peak are according to this sequence alternate and repetition.

23. according to the surface coating cutting tool (1) of claim 20, wherein

Described compression stress be from least-stress of 15GPa in the 0GPa scope at the most.

24. according to the surface coating cutting tool (1) of claim 20, wherein

Described first intermediate point (5) be positioned at described described surface (4) of filming at a distance of described filming (3) thickness at least 0.1% to the position of 40% distance at the most.

25. according to the surface coating cutting tool (1) of claim 20, wherein

Described second intermediate point (9) be positioned at described described surface (4) of filming at a distance of described filming (3) thickness at least 0.2% to the position of 80% distance at the most.

26. according to the surface coating cutting tool (1) of claim 20, wherein

Described compression stress locates to reach peak on described described surface (4) of filming.

27. according to the surface coating cutting tool (1) of claim 20, wherein

The described compression stress of locating at described first intermediate point (5) is set to the value of the 10-80% that is equivalent to the compression stress located on described described surface (4) of filming.

28. according to the surface coating cutting tool (1) of claim 27, wherein

The described compression stress of locating at described first intermediate point (5) is set to the value of the 20-60% that is equivalent to the compression stress located on described described surface (4) of filming.

29. surface coating cutting tool (1) comprising:

Basic material (2); With

Go up film (3) that form at described basic material (2); Wherein

These film (3) are as the outermost layer on described basic material (2) and have compression stress,

This compression stress changes so that have intensity distributions on the thickness direction of described filming (3), and

This intensity distributions is characterised in that: described compression stress of filming lowers from described described surface (4) of filming towards being positioned at described described surface (4) of filming and first intermediate point (5) between the described bottom surface of filming (6), and this compression stress locates to reach relative minimum point at described first intermediate point (5)

Wherein said intensity distributions is characterised in that: locates to reach maximal pressure stress under compression and this compression stress on described described surface (4) of filming and keeps steady state value to described described bottom surface (6) of filming from described first intermediate point (5), and

Wherein said maximal pressure stress under compression is maintained at the predetermined distance from described described surface (4) of filming to described first intermediate point (5), and described afterwards compression stress lowers continuously towards described first intermediate point (5).

30. surface coating cutting tool (1) comprising:

Basic material (2); With

Go up film (3) that form at described basic material (2); Wherein

These film (3) are as the outermost layer on described basic material (2) and have compression stress,

This compression stress changes so that have intensity distributions on the thickness direction of described filming (3), and

This intensity distributions is characterised in that: described compression stress of filming lowers from described described surface (4) of filming towards being positioned at described described surface (4) of filming and first intermediate point (5) between the described bottom surface of filming (6), and this compression stress locates to reach relative minimum point at described first intermediate point (5)

Wherein said intensity distributions is characterised in that: described compression stress increases towards described described bottom surface (6) of filming continuously from described first intermediate point (5), and

Wherein said compression stress of filming is maintained at the predetermined distance from described described surface (4) of filming to described first intermediate point (5), and described afterwards compression stress lowers continuously towards described first intermediate point (5).

31. surface coating cutting tool (1) comprising:

Basic material (2); With

Go up film (3) that form at described basic material (2); Wherein

These film (3) are as the outermost layer on described basic material (2) and have compression stress,

This compression stress changes so that have intensity distributions on the thickness direction of described filming (3), and

This intensity distributions is characterised in that: described compression stress of filming lowers from described described surface (4) of filming towards being positioned at described described surface (4) of filming and first intermediate point (5) between the described bottom surface of filming (6), and this compression stress locates to reach relative minimum point at described first intermediate point (5)

Wherein said intensity distributions is characterised in that: described compression stress increases continuously and reaches relative peak at described second intermediate point (9) towards being positioned at second intermediate point (9) between described first intermediate point (5) and the described described bottom surface (6) of filming from described first intermediate point (5), and

Wherein said compression stress of filming is maintained at the predetermined distance from described described surface (4) of filming to described first intermediate point (5), and described afterwards compression stress lowers continuously towards described first intermediate point (5).

32. surface coating cutting tool (1) comprising:

Basic material (2); With

Go up film (3) that form at described basic material (2); Wherein

These film (3) are as the outermost layer on described basic material (2) and have compression stress,

This compression stress changes so that have intensity distributions on the thickness direction of described filming (3), and

This intensity distributions is characterised in that: described compression stress of filming lowers from described described surface (4) of filming towards being positioned at described described surface (4) of filming and first intermediate point (5) between the described bottom surface of filming (6), and this compression stress locates to reach relative minimum point at described first intermediate point (5)

Wherein said intensity distributions is characterised in that: described compression stress increases continuously with second intermediate point (9) between the described described bottom surface (6) of filming and reaches relative peak at described second intermediate point (9) towards being positioned at described first intermediate point (5) from described first intermediate point (5), and this intensity distributions has one or more similar described relative minimum points between described second intermediate point (9) and described described bottom surface (6) of filming, and

Wherein said compression stress of filming is maintained at the predetermined distance from described described surface (4) of filming to described first intermediate point (5), and described afterwards compression stress lowers continuously towards described first intermediate point (5).

Images