JP4936703B2 - Surface coated cutting tool - Google Patents

Description

  The present invention relates to a surface-coated cutting tool formed by forming a hard coating layer on the surface of a substrate.

  Currently, cutting tools are used to improve slidability, wear resistance, and fracture resistance by forming various hard coating layers on the surface of hard materials such as WC-based cemented carbide and TiCN-based cermet. In particular, a hard coating layer formed by a physical vapor synthesis method has high hardness and high wear resistance, and is widely used in various applications. Among such physical vapor phase synthesis methods, particularly in the arc ion plating method suitably used as a method for forming a hard coating layer, coarse molten particles called droplets are generated during film formation, It is known that macro particles flying over the surface and having a diameter of 1 μm or more are dispersed in the hard coating layer. In particular, in the arc ion plating method suitably used as a method for forming a hard coating layer, the generation of macro particles having a diameter of 1 μm or more called droplets may cause chipping or chipping of the cutting edge, As a result, the smoothness of the machined surface is impaired and the tool life is reduced.

  Therefore, for example, in Patent Document 1, the ratio of coarse particles (macro particles) in the hard coating (hard coating layer) formed to 5 area% or less is controlled by controlling the film forming conditions of the arc ion plating method. It is disclosed that the surface roughness of the hard coating surface can be smoothed to 0.1 μm or less in Ra and 1 μm or less in Rz, and the welding resistance and wear resistance can be increased.

Further, in Patent Document 2, when a hard coating layer is formed by an arc ion plating method, a first layer is first formed, and the surface of the first layer is hardened by machining such as blasting. After removing the macro particles existing on the surface of the film, the second layer is formed to reduce the generation of macro particles on the surface of the second layer, which is the surface of the hard coating layer. It is disclosed that the abnormal wear due to can be suppressed.
JP 2002-346812 A JP 2005-28544 A

  However, when the macro particles generated on the surface of the hard coating layer are completely eliminated as in Patent Document 1 and Patent Document 2, the lubricity between the hard coating layer and the chips on the rake face where chips are discharged. Will not be enough, the frictional resistance of the hard coating layer will increase, and chemical wear due to rubbing wear and heat of cutting will be promoted, or the work material will weld to the cutting edge and wear resistance will be reduced. Decrease or film peeling at the time of weld dropout occurred.

  The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a surface-coated cutting tool that is excellent in chip disposal and has high fracture resistance and wear resistance.

  In the present invention, it is better to eliminate macro particles generated on the surface of the hard coating layer as much as possible in order to increase the fracture resistance and the roughness of the machined surface in the cutting edge, but the hard coating when discharging chips on the rake surface. This is based on the knowledge that it is better to have macro particles on the surface of the hard coating layer in order to lower the friction coefficient of the layer.

That is, the surface-coated cutting tool of the present invention is a cutting tool in which a hard coating layer is coated on the surface of a substrate, and macro particles are dispersed on at least the surface of the hard coating layer, and the surface of the hard coating layer is machined. it not, the area ratio of the macro-particles present in the cutting edge position of the surface of the hard coating layer is not more than 5 area% or less, the area ratio 5 of the macro-particles present in the rake face position of the surface of the hard coating layer It is characterized in that it is composed less than ˜30 area% .

Here, the area ratio of the macro particles present at the cutting edge position on the surface of the hard coating layer is 5% by area or less in that the wear resistance and fracture resistance of the cutting edge can be further improved. Is important .

Moreover, it is important that the area ratio of the macro particles existing at the rake face position on the surface of the hard coating layer is 5 to 30 area% in that the frictional resistance during chip treatment on the rake face can be reduced. There is .

  Note that the film thickness at the cutting edge position of the hard coating layer is thinner than the film thickness at the rake face position is high in chipping resistance at the cutting edge, and the hard coating layer is also caused by rubbing wear due to chips on the rake face. It is desirable in that a good chip disposal can be achieved without wear.

  Further, when the cutting edge has an R honing with a radius of curvature R = 0.005 to 0.1 mm, the distribution of the macro particles can be easily realized.

  Furthermore, it is desirable that the macro particles are made of a metal or alloy whose surface is nitrided, because the function of the macro particles on the rake face can be maintained and the effect of reducing the frictional resistance of chip treatment can be exhibited over a long period of time. .

  According to the present invention, the cutting blade has a low presence ratio of macro particles on the surface of the hard coating layer and high fracture resistance and processed surface roughness, and the rake face has macro particles on the surface of the hard coating layer. The friction coefficient of the hard coating layer when discharging chips is low, and as a result, excellent cutting performance can be exhibited.

  Here, when the area ratio of the macro particles present at the cutting edge position on the surface of the hard coating layer is 5 area% or less, the chipping resistance of the cutting edge can be further improved.

  Moreover, the frictional resistance at the time of the chip processing in a rake face can be reduced because the area ratio of the macro particle which exists in the rake face position of the surface of the said hard coating layer is 5-30 area%.

  In addition, by making the film thickness at the cutting edge position of the hard coating layer thinner than the film thickness at the rake face position, the chipping edge has high chipping resistance, and the rake face is hard coated even by rubbing wear caused by chips. Good chip disposal without erosion of the layer.

  Furthermore, when the cutting edge has an R honing with a radius of curvature R = 0.005 to 0.1 mm, the macro particle distribution tends to be easily realized.

  Furthermore, since the macro particles are made of a metal or alloy whose surface is nitrided, the wear resistance on the surface of the macro particles is high, and the macro particles as a whole can be deformed into a shape along the flow of chips. The function of the macro particles in the surface can be maintained, and the effect of reducing the frictional resistance of the chip treatment is exhibited over a long period of time.

  As for an example of the surface-coated cutting tool of the present invention, (a) a schematic perspective view of the surface-coated cutting tool of the present invention, (b) FIG. 1 which is a schematic sectional view, and a microscope showing an example of the surface-coated cutting tool of the present invention This will be described with reference to FIG.

  1 and 2, a surface-coated cutting tool (hereinafter simply referred to as a tool) 1 according to the present invention includes a rake face 3 on a main surface, a flank face 4 on a side face, a rake face 3 and a flank face 4. A cutting edge 5 is provided at the crossing ridge line, and a hard coating layer 6 is formed on the surface of the substrate 2.

  The hard coating layer 6 includes one or more metal elements selected from Group 4, 5 and 6 elements of the periodic table, Al and Si, and one or more non-metal elements selected from nitrogen, carbon, boron and oxygen. It is comprised by the at least 1 layer of these compounds.

  According to the present invention, the macro particles 8 are dispersed on at least the surface of the hard coating layer 6, and the area ratio of the macro particles 8 existing on the surface of the cutting blade 5 of the hard coating layer 6 is the surface ratio of the hard coating layer 6. The area ratio of the macro particles 8 existing at the rake face 3 position is small.

  As a result, the cutting edge 5 has a high chipping resistance and a high surface roughness, and the rake face 3 has a low friction coefficient of the hard coating layer 6 when chips are discharged due to the presence of the macro particles 8, resulting in excellent results. Cutting performance can be demonstrated.

  That is, when the macro particles 8 are present on the entire surface of the hard coating layer 6, the macro particles 8 are likely to be the starting point of cracks, and the fracture resistance of the cutting blade 5 is reduced. On the contrary, when the macro particles 6 are not present on the entire surface of the hard coating layer 6, the frictional resistance of the chips on the rake face 3 increases, and wear progresses or the chips are welded to the rake face 3. There is. That is, in any case, cutting performance cannot be improved.

  In addition, the area ratio of the macro particles 8 existing on the surface of the hard coating layer 6 is a macro particle 8 observed in a region of 5 μm or more × 10 μm or more of a tissue photograph such as a scanning micrograph on the surface of the hard coating layer 6. The area ratio can be determined by measuring by the Luzex image analysis method. In addition, about calculation of an area ratio, it measures about three or more places of arbitrary areas, and calculates from the average value.

  The macro particle 8 includes a metal of a metal element constituting the hard coating layer 6, an alloy of two or more metal elements constituting the hard coating layer 6, or a compound of a metal element and a nonmetallic element constituting the hard coating layer 6. And a mixture thereof, for example, one or more (1) metals selected from Group 4, 5, 6 elements of the periodic table, Al and Si, (2) alloys of these two or more metals, ( 3) It is comprised with the compound with 1 or more types of nonmetallic elements chosen from nitrogen, carbon, boron, and oxygen, or the mixture of (1)-(3).

  Here, when the area ratio of the macro particles 8 existing at the position of the cutting edge 5 on the surface of the hard coating layer 6 is 5% by area or less, the macro particles 8 serving as the starting point of the crack in the cutting edge 5 to which the impact is most applied. This is desirable in that the influence of the above can be reduced and the fracture resistance of the cutting blade 5 can be further improved. Furthermore, since the arithmetic average roughness (Ra) at the position of the cutting edge 5 of the hard coating layer 6 is 0.12 μm or less, the cutting edge 5 has high chipping resistance, and the cutting resistance during cutting can be reduced. Is desirable. In addition, arithmetic mean roughness (Ra) in the position of the cutting edge 5 of the hard coating layer 6 is based on JIS B0601'01 using a stylus type surface roughness measuring device, cut-off value: 0.25 mm, It can be measured at a reference length of 0.8 mm and a scanning speed of 0.1 mm / second.

In addition, the fact that the area ratio of the macro particles 8 existing at the position of the rake face 3 on the surface of the hard coating layer 6 is 5 to 30% by area can reduce the frictional resistance during chip treatment on the rake face 3. Is important .

  Further, the cutting edge 5 may be a sharp edge with a radius of curvature R of less than 0.005 mm, but the above specification is more effective when the cutting edge 5 has an R honing with a radius of curvature R = 0.005 to 0.1 mm. The distribution of the macro particles 8 tends to be easily realized.

  Further, the macro particles 8 are made of a metal or alloy whose surface is nitrided, the surface of the macro particles 8 is formed with a nitride having high hardness and high wear resistance, and the inside of the macro particles 8 is deformed. As a result of being a metal or alloy that is easy to wear, the overall shape of the macro particles 8 can be deformed into a shape along the flow of chips, so that the function of the macro particles 8 on the rake face 3 can be maintained, and the frictional resistance of chip treatment over a long period of time. It is desirable in that it exhibits a reduction effect.

  Furthermore, when the film thickness of the hard coating layer 6 is 0.2 to 5.0 μm, the hard coating layer 6 has high fracture resistance and can prevent film peeling, and the hard coating layer 6 has sufficient lubricity. Desirable because it has wear resistance. In addition, by making the film thickness at the position of the cutting edge 5 of the hard coating layer 6 smaller than the film thickness at the position of the rake face 3, the chipping resistance at the cutting edge 5 with the greatest impact of the work material is high, and Even on the rake face 3, even with rubbing wear caused by chips, the hard coating layer 6 is not worn away and good chip treatment can be performed. A preferable range of the film thickness at the position of the cutting edge 5 of the hard coating layer 6 is 0.5 to 2 μm, and a preferable range of the film thickness at the position of the rake face 3 of the hard coating layer 6 is 1 to 2.5 μm.

  In addition, as the substrate 2, cemented carbide, cermet, silicon nitride, and oxide composed of a hard phase mainly composed of tungsten carbide or titanium carbonitride and a binder phase mainly composed of an iron group metal such as cobalt or nickel. Hard materials such as ceramics mainly composed of aluminum, a hard phase made of polycrystalline diamond or cubic boron nitride and a binder phase such as ceramics or iron group metal are fired under an ultra-high pressure, etc. used.

(Production method)
Next, the manufacturing method of the surface coating cutting tool of this invention is demonstrated.

  First, a tool-shaped substrate is produced using a conventionally known method.

  Next, on the surface of the substrate, one or more metal elements selected from Group 4, 5, 6 elements of the periodic table, Al and Si, and one or more non-metal elements selected from nitrogen, carbon, and oxygen, A hard coating layer made of the above compound is formed.

Note that a physical vapor phase synthesis (PVD) method such as an ion plating method or a sputtering method is used as a film forming method. The details of several examples of the film formation method will be described. When a composite hard layer containing titanium (Ti) and aluminum (Al) is produced by an ion plating method, two types of metal targets, namely metal titanium and metal aluminum, are used. Are used independently, or a titanium aluminum (TiAl) alloy is used as a target, and a metal source is evaporated and ionized by arc discharge or glow discharge, and at the same time, nitrogen (N ₂ ) gas as a nitrogen source or methane (CH as a carbon source) ₄ ) Reacted with acetylene (C ₂ H ₂ ) gas to form a film. At this time, in order to increase the density of the hard coating layer and the adhesion to the substrate, and to disperse the predetermined macro particles 8 in the hard coating layer 6, the film is formed while applying a bias voltage of 30 to 200V. It is desirable.

Here, as an example of a method of implementing the distribution of macroparticles 8 hard in the coating layer 6 in the present invention is suitable method of performing the gas bombarded during or at the end of film formation, the edges in gas bombarded Since the portion is selectively polished, the macro particles 8 on the surface of the cutting edge 5 of the hard coating layer 6 that has been formed can be selectively removed. The area ratio of the macro particles 8 existing on the surface of the blade 5 can be made smaller than the area ratio of the macro particles 8 existing at the position of the rake face 3 on the surface of the hard coating layer 6.

Mainly composed of tungsten carbide (WC) powder having an average particle diameter of 0.8 μm, 10% by mass of metallic cobalt (Co) powder having an average particle diameter of 1.2 μm, and vanadium carbide (VC) powder having an average particle diameter of 1.0 μm. Add 0.2% by mass of chromium carbide (Cr ₃ C ₂ ) powder with an average particle size of 1.0 μm at a ratio of 0.6% by mass and mix it into a grooved cutting tool shape (GBA43R300NY) by press molding. After that, a binder removal treatment was performed, and firing was performed at 1500 ° C. for 1 hour in a vacuum of 0.01 Pa to produce a cemented carbide. Further, the prepared cemented carbide was subjected to blade edge processing (honing) by brushing.

  Hard coating layers having various compositions shown in Table 1 were formed on the substrate thus prepared by arc ion plating. Further, for some samples, bombardment using a mixed gas of nitrogen gas and argon gas was performed in the middle or at the end of film formation under the conditions shown in Table 1, and on the surface of the cutting edge of the formed hard coating layer Macro particles were removed.

  With respect to the obtained sample, the surface of the hard coating layer at the land position of the cutting edge and the rake face was observed with a scanning electron microscope (SEM), and the area ratio of the macro particles was measured. In addition, the area ratio of the macro particles in Table 1 is the area of the macro particles in a region of 100 μm in the direction parallel to the ridge line of the cutting edge × 5 μm in the direction perpendicular to the ridge line of the cutting edge. The ratio was determined by a Luzex image analysis method, and the average value at three arbitrary locations was shown in Table 1 as the area ratio of macro particles. Moreover, the film thickness of the hard coating layer was calculated | required from the cross-sectional SEM photograph of the cutting tool. Further, the arithmetic average roughness Ra at the cutting edge position on the surface of the hard coating layer was measured at three arbitrary positions with a contact-type surface roughness meter, and obtained from the average value. A specific measuring method is based on JIS B0601'01 using a stylus type surface roughness measuring device, cut-off value: 0.25 mm, reference length: 0.8 mm, scanning speed: 0.1 mm / Measured in seconds.

  Next, a cutting test was performed under the following cutting conditions using the obtained grooved cutting tool-shaped throw-away tip (cutting tool). The results are shown in Table 2.

Cutting method: Intermittent turning work material: SCM440, four 5mm wide grooved cutting speed: 120m / min
Feeding: 0.2mm / rev
Cutting depth: 2mm
Cutting state: Dry evaluation method: State of cutting edge and rake face at the stage where 2000 impacts were applied, and the number of impacts until failure

  From Tables 1 and 2, Sample No. in which a large amount of macro particles were generated on the entire surface of the hard coating layer without performing bombardment during or during the film formation. No. 11 had a short tool life due to early chipping. In addition, sample No. 1 in which macro particles are uniformly formed on the entire surface of the hard coating layer without performing bombarding during or after the film formation is formed by sputtering. No. 12, chipping occurred early and the tool life was short. Further, in place of the bombarding process during or at the end of the film formation, a blasting process was performed after the film formation to uniformly reduce the macro particles on the entire surface of the hard coating layer. No. 13, chip welding occurred on the rake face and the tool life was short.

  On the other hand, Sample No. in which the area ratio of macro particles at the rake face position on the surface of the hard coating layer within the scope of the present invention is larger than that at the cutting edge position. Nos. 1 to 10 exhibited good cutting performance with low frictional resistance and good chip disposal and excellent chipping resistance at the cutting edge. Among them, the area ratio of the macro particles existing at the cutting edge position on the surface of the hard coating layer is 5 area% or less, and the area ratio of the macro particles existing at the rake face position on the surface of the hard coating layer is 10 to 30 area%. Sample No. 1 to 3, 6, 7, 9, and 10, particularly, the number of impacts could be extended and the tool life was long.

It is a schematic perspective view of the surface coating cutting tool of this invention. It is a drawing substitute photograph which shows an example of the surface coating cutting tool of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface coating cutting tool 2 Base | substrate 3 Rake face 4 Flank 5 Cutting edge 6 Hard coating layer 8 Macro particle

Claims (4)

In a cutting tool in which the surface of a base is coated with a hard coating layer, macro particles are dispersed on at least the surface of the hard coating layer, and the surface of the hard coating layer is cut without machining the surface of the hard coating layer. The area ratio of the macro particles existing at the blade position is 5 area% or less, and the structure is smaller than the area ratio of the macro particles existing at the rake face position of the surface of the hard coating layer is 5 to 30 area%. A surface-coated cutting tool characterized by that. Claim 1 surface-coated cutting tool according to the film thickness at the cutting edge position of the hard coating layer, characterized in that thinner than in the rake face position. Claim 1 or 2 surface-coated cutting tool, wherein said cutting edge has a R honing radius of curvature R = 0.005~0.1mm. The surface-coated cutting tool according to any one of claims 1 to 3 , wherein the macro particles are made of a metal or alloy whose surface is nitrided.

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