JP2002146515A - Hard film superior in slidableness and its coating tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hard film having fine holes on the surface such that the fine holes demonstrate a liquid holding effect, when a processing liquid or a lubricant is used for tools or parts whose surface is coated with the hard film having adequately arranged fine holes, and that, therefore, the film can extend a service life for tools including a tip, drill, metallic die, etc., and for sliding parts like bearings even under severe using conditions, and also to provide a coating device for this film. SOLUTION: The hard film, which is applied on the surface of a base material, is studded with such fine holes on the surface that have a depth of 1.0 μm or above, an average diameter of 0.5-5 μm, and a ratio between the total hole opening areas and the entire hard film surface area of 0.02-0.20. Consequently, compared with a conventional identical hard film, a lubricating ability is secured by the supply of the processing liquid or the lubricant through the liquid holding effect, thereby enabling the life of the tools or the sliding parts to be prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hard film coated on the surface of a base material and a tool coated with the hard film, and more particularly to a cutting tool such as a drill and an end mill, and a wear-resistant tool such as a drawing die. The present invention relates to a hard film and a coated tool exhibiting excellent slidability with a tool or a bearing bush.

[0002]

_2. Description of the Related Art TiN, TiCN, TiC, Al ₂ O ₃ ,
Hard films such as (TiAl) N are used for cutting tools, wear-resistant tool parts and sliding parts, and contribute to extending the life. Generally, a machining fluid or lubricating fluid is used, but depending on the work material and machining conditions or the sliding conditions of the mating material, the lubrication or cooling ability is reduced, so that the film peels due to increased frictional force and generates heat. There is a problem that it is difficult to extend the service life due to seizure due to increase, thermal deterioration and deformation of the base material.

In order to solve this problem, the type and amount of the extreme pressure additive or the solid lubricant in the working fluid are adjusted, the surface condition (mainly roughness) of the hard film is adjusted, and the type of the hard film is selected. , A solid lubricating film, and the like. In general, a smoothing process such as a lapping process or a blast polishing is performed as a roughness adjustment. Further, there is a method of preventing image sticking by providing fine holes on the surface and holding the working liquid in the fine holes (liquid pool effect). Further, as a selection of a hard film, there is a method of coating a compound having a relatively low friction coefficient, such as chromium nitride, chromium oxide, and vanadium nitride. Furthermore, molybdenum disulfide, tungsten disulfide, graphite,
There is a method of coating a solid lubricant such as diamond-like carbon (DLC) on a hard film.

[0004] As typical examples of the prior art, Japanese Patent Application Laid-Open No. H07-157962 for smoothing and Japanese Patent Application Laid-Open No. H7-216491 for providing a fine hole are disclosed.
JP-A-08-132310, JP-A-2000-107906 and the like for selecting a hard film and JP-A-2-221714 and JP-A-2000-001768 for coating a solid lubricating film are given. is there.

[0005]

[Problems to be Solved by the Invention] JP-A-07-157
No. 862 discloses a multi-component metal carbide, metal nitride, metal carbon / nitride film containing two or more metal elements, in which macro particles do not substantially protrude from the surface.
A wear-resistant and weld-resistant hard-coated tool coated with a hard coating having a crater depth of 2 to 2 μm and the production thereof are described. The hard coating described in this publication,
The removal of macro particles of about 1 to 5 μm attached to the surface of the coating prevents welding of the work material during cutting, and it is possible to improve cutting accuracy and tool life to some extent. However, there is a problem that welding is likely to occur because there is no lubricating effect under strict processing conditions using. In other words, the crater formed in the hard film described in this publication has a shape in which a liquid pool effect cannot be exhibited because the crater is formed when the macroparticles are removed.

[0006] Japanese Patent Application Laid-Open No. Hei 7-216491 discloses that the present inventors provide Ca, Sr, Ba oxides, carbides,
Containing 2 to 30% by volume of a dispersed phase composed of sulfide or the like;
In a sintered hard alloy using carbide, nitride, or boride of a, 5a, or 6a group metal as a hard phase and iron group metal as a binder phase,
A sintered body having fine pores in which a dispersed phase is removed from the surface to form fine pores and a method for producing the same are described. The sintered body described in this publication can reduce friction and abrasion due to the liquid pool effect of micropores present on the surface, but it is said that the abrasion resistance is insufficient compared with the strength reduction due to the dispersed phase and the hard film coated product. There's a problem.

Next, Japanese Patent Application Laid-Open No. 08-132310 discloses a CrNx of 0.05 to 5.0 μm (0.3 ≦ x ≦ 1.
No. 0) describes a lubricated hard film coated drill in which a hard surface coating of CrOy (0.3 ≦ y ≦ 1.5) of 0.01 to 2.0 μm is formed on the hard film. Japanese Patent Application Laid-Open No. 2000-107906 discloses that VCN or (TiV) CN is further coated on a coated hard alloy coated with nitride, carbonitride, and carbonitride containing Ti and Al as main components. A coated hard tool is described.

[0008] The hard multilayer films described in these publications are:
Cr (O) and V (CN) in the outer layer provide lubricity, while Cr in the inner layer
(N), (TiAl) N, etc. are used to improve the wear resistance, but the lubrication of the outer layer is insufficient or the outer layer is easily peeled off, so that the effect of extending the life is small. There's a problem.

Further, JP-A-2-221714 discloses that a sliding surface of a bearing is coated with a laminated film of TiC and a soft metal such as gold, silver or lead or a layered solid lubricant such as MoS ₂ or WS _2. Described solid lubricated bearings. Japanese Patent Application Laid-Open No. 2000-001768 discloses that at least one element selected from Group 4, 5, 6 and 6 of the periodic table, Al, Si, B and C and B, C, N and O are selected. In a multi-layer coating having a surface layer mainly composed of molybdenum disulfide and a base layer of a high-hardness coating composed of at least one of
% Abrasion resistant hard coatings having solid lubricity and containing from 10% to 10 at%.

The lubricating coatings described in these two publications are:
MoS ₂ lubricity is used to extend tool life, but MoS ₂ is soft and wears off or separates from the base film, so there is almost no life extension effect under cutting or severe sliding conditions. There is a problem to say.

[0011]

Means for Solving the Problems The inventors of the present invention have studied a hard film having characteristics that are simultaneously provided with contradictory characteristics such as wear resistance and slidability and lubricity over many years. The knowledge that the film has micropores that are open, the micropores hold a working fluid, and the frictional force is reduced by the micropores holding the working fluid, thereby significantly reducing the friction and wear of the hard film. It is obtained.

The hard film having excellent slidability and the coated tool according to the present invention are a single layer having a thickness of 1 to 20 μm or a multilayer having two or more layers, and have a periodic table of 4a (Ti, Zr, Hf),
At least one element selected from the group consisting of 5a (V, Nb, Ta) and 6a (Cr, Mo, W) elements, aluminum and silicon carbides, nitrides, oxides, borides, and mutual solid solutions thereof; Wherein the hard film has fine pores having an opening diameter of 0.5 to 5 μm.

The micropore has a depth of 1.0 μm,
And the micropore depth is 0.05% of the average thickness of the hard film.
By satisfying １．０1.00, excellent slidability is maintained. In addition, the total area of the openings of the micropores (the sum of the areas of the openings of the micropores) is 0.02 to 2.0 in terms of the total area of the hard film.
0.20 is satisfied.

When the surface roughness of the hard film surface excluding the micropores is 0.2 μm or less in Ra, the initial friction coefficient is reduced and a synergistic effect with the micropores is obtained.

The substrate coated with the hard film of the present invention exhibits excellent performance as a coated tool. Specific examples of the substrate include cemented carbide, cermet, ceramics, cubic boron nitride sintered body, and hard steel. , High-speed steel, and these substrates have particularly remarkable effects.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The hard film having excellent slidability according to the present invention is a group 4a, 5a, or 6a element of the periodic table, aluminum, silicon carbide, nitride, oxide, boride, and a mutual solid solution thereof. A hard film consisting of one or more selected from the group consisting of a single layer having a thickness of 1 to 20 μm or a multilayer having two or more layers, and an opening diameter of 0.5 to 5 μm
A hard film having excellent slidability, characterized by having fine pores. Specifically, as a single-layer film, TiC, TiN, TiB ₂ , TiCN, TiCNO, T
iBN, ZrN, HfN, VN, CrN, (TiAl)
N, (TiAl) CNO, (ZrV) CN, Si ₃ N ₄ ,
Al ₂ O ₃ , ZrO ₂ , Cr ₂ O _{3 and the} like can be given. The multilayer film is a combination of these single-layer film types,
Specifically, TiN / (TiAl) N, Ti
CN / TiB ₂ , TiN / (ZrV) CN / Al ₂ O _{3 and the} like can be given.

Among these, TiC, TiN, and TiN in which the outermost layer of the hard film is coated by a physical vapor deposition method.
It is preferable that at least one of B ₂ , TiCN, (TiAl) N, and (TiAl) CN be used because it is easy to form fine holes in a later step and a smooth plane can be easily obtained.

When the thickness of the hard film is less than 1 μm, the effect of improving the abrasion resistance is small.
When the thickness exceeds m, the residual stress due to the difference in thermal expansion coefficient from the substrate increases, thereby causing peeling of the film and a decrease in strength.

The micropores reduce the coefficient of friction by allowing the working fluid to enter and be held in the pores. Therefore, when the opening diameter is less than 0.5 μm, the working fluid does not easily enter the pores. Therefore, when the lubricating effect is not sufficient and the size exceeds 5 μm, the working fluid penetrating into the fine holes tends to flow out, and the liquid storage effect by holding the working fluid cannot be obtained. Was.

If the depth of the fine holes is less than 1 μm, the desired lubricity cannot be obtained, so that the depth is limited to 1 μm or more. ~
In the case where micropores having a depth exceeding the hard film thickness, that is, in other words, exceeding 1 in the above ratio, are formed, the strength of the entire substrate is reduced. It was set to 0.05 to 1.00 to invite.

Each of the micropores is limited as described above. The total area of the micropore openings (sum of the individual micropore opening areas) is 0.02 to 0.2 with respect to the area of the entire hard film.
0. This is because when the amount is less than 0.02, the effect of reducing the friction coefficient is small because the amount of liquid pool is small.
If it exceeds 20, the wear resistance decreases with a decrease in the ratio of the hard film surface area that relatively contributes to friction.
0.02 to 0.2. The measurement of the total area of the micropore opening is performed as follows. The hard film surface is magnified 300 to 1500 times with an optical microscope, and the image data is digitized. Further, by subjecting the image data to computer image processing, the total area in the image can be obtained.

Further, by controlling the surface roughness of the hard film, a synergistic effect can be obtained with the liquid pooling effect of the micropores, and the surface roughness of the hard film excluding the micropores is 0.2 μm or less in Ra. When, the desired lubricating effect is obtained.

By coating the substrate with these hard films, a coated tool having both abrasion resistance and contradictory lubricity can be obtained. Specific base materials are characterized by being made of at least one of cemented carbide, cermet, ceramics, cubic boron nitride sintered body, hard steel, and high-speed steel. A remarkable effect can be obtained.

The formation of micropores can be obtained by chemically or mechanically removing droplets or foreign particles dispersed in the coating after coating the hard film, or by irradiating a laser beam. If the droplet has a highly metallic granular structure, a concave portion from which the droplet has been removed by immersion in an acid, an alkali, or the like can be obtained as fine pores. Also, by spraying an aqueous solution in which fine alumina powder is suspended onto the film surface at a high pressure, droplets and foreign particles are removed, and a hard film having fine pores is obtained. Further, under the condition that the melting point of the droplet or the foreign particles is lower than the hard film by a certain degree or more, only the low melting point portion is selectively removed by laser beam irradiation, so that micropores can be obtained.

[0025]

According to the hard film having excellent slidability and the coated tool of the present invention, the hard film improves abrasion resistance, and the micropores have a liquid collecting effect, so that they act as lubricity and reduce frictional wear. To prevent image sticking and peeling of the film.

[0026]

Example 1 As a base material, a commercially available cemented carbide solid drill (8.0 mm, composition: WC-10 wt%)
Co, hardness: HRA = 91.5), and an arc ion plating apparatus capable of mounting a four-electrode target and spraying powder on the surface of the processed material was used as a hard coating apparatus. First, a substrate drill is inserted into the apparatus to make a vacuum of about 1 × 10 ⁻³ Pa, and then heated to 500 ° C. to make A
The drill surface was sufficiently cleaned by Ar sputtering by applying a bias voltage of -600 V and maintaining for 10 minutes while introducing r gas to about 0.1 Pa, followed by degassing. Next, the coating conditions (target type, gas component and flow rate, bias voltage, arc current,
By performing the coating process sequentially with (processing time)
The coated drill materials of A to D were obtained.

[0027]

[Table 1] * Note) IP: Ion plating (reactive deposition) PD: Particle deposition (lumped particle deposition)

Next, the coated drill materials of A to D were subjected to the surface treatments shown in Table 2 to obtain products 1 to 4 of the present invention and comparative products 1 to 3
A coated drill having micropores on the surface of was obtained. Then, the cutting edge of the coated drill after the pretreatment was observed with a scanning electron microscope, and the average diameter of the fine holes formed on the coating surface and the area ratio of the fine holes to the entire surface were determined. Further, the film configuration (component, film thickness) and the depth of the micropores were measured from the cross-sectional structure of the cutting edge. The results of these observations and measurements are also shown in Table 2.

[0029]

[Table 2] * Note) Liquid honing conditions: # 400 alumina powder suspension (3
0g / L) at 0.2MP Immersion conditions: 10% HCl in 10 minutes Electrolysis conditions: 5% H ₂ SO ₄ in 2.5V × 0.05A / cm ² × 2.0min

Using the obtained coated drills of the present invention products 1-4 and comparative products 1-3, a work material: S45C, a cutting outer peripheral speed: 80 m / min, a hole depth: 40 mm, a wet process (emulsion type) Drilling was continuously performed under the condition of using a working fluid). Table 3 shows the number of holes that can be machined until a sharp increase in torque occurs due to occurrence of chipping, breakage or clogging of chips. When the machining was normal up to 400 holes, the average flank wear of the cutting edge was also described.

[0031]

[Table 3]

[0032]

Embodiment 2 Cemented carbide materials for wear-resistant tools (JIS V3
0), the entire surface is rough- and finish-ground with 140 # and 800 # diamond grindstones to produce punches for punching, and then the same as the inventive product 3 of Example 1 and the comparative product 3 According to the method and conditions, coated punches of the present invention 5 and the comparative product 4 were obtained. Using these, a zinc steel plate having a thickness of 0.6 mm was punched out using a water-soluble working fluid, and the number of shots until a defective product was generated due to burrs was measured.
As a result, the product 3 of the present invention had about 1,000,000 shots, while the comparative product 3 had about 520,000 shots.

[0033]

As shown in the results of Table 3, the hard film having excellent slidability and the coated tool of the present invention act as lubricity because the micropores have a liquid storage effect, and reduce friction and wear. It was intended to reduce the amount of seizure and peeling of the film, and the life of the tool was remarkably increased. In addition, as is apparent from Example 2, the punch life in the punching process using the working fluid also provided about twice the tool life.

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Claims (7)

[Claims] 1. A hard film comprising at least one element selected from the group consisting of elements of groups 4a, 5a and 6a of the periodic table, aluminum, silicon carbide, nitride, oxide, boride and their mutual solid solutions. The thickness of the hard film is 1 to 20 μm
A single layer or two or more layers having an opening diameter of 0.5 to
A hard film having excellent slidability characterized by having fine pores of 5 μm. 2. The micropores have a depth of at least 1.0 μm and a micropore depth of 0.1 to the average thickness of the hard film.
2. The hard film having excellent slidability according to claim 1, wherein the thickness is in the range of 0.5 to 1.00. 3. The hard metal with excellent slidability according to claim 1, wherein the total area of the micropore openings is 0.02 to 0.20 as a ratio to the total area of the hard film. film 4. The hard film according to claim 1, wherein said hard film is made of at least one of titanium carbide, nitride, carbonitride, composite nitride of titanium and aluminum, and composite carbonitride. Or a hard film having excellent slidability according to 3. 5. The surface roughness of a hard film surface excluding micropores is R
a is 0.2 μm or less,
Hard film excellent in slidability according to 2, 3 or 4 6. A coated tool comprising a base material coated with the hard film according to claim 1, 2, 3, 4 or 5. 7. The coated tool according to claim 6, wherein the substrate is made of at least one of a cemented carbide, a cermet, a ceramic, a cubic boron nitride sintered body, a hard steel, and a high-speed steel.