Cutting tool antifriction coating and preparation method thereof

Abstract

The invention discloses a cutting tool antifriction coating and a preparation method, and belongs to the technical field of metal cutting tools. The cutting tool antifriction coating comprises a hard coating and a soft coating which are arranged from inside to outside, the hard coating comprises a plurality of hard coating textures arranged on the surface of the cutting tool at intervals, and the length direction of the hard coating textures is perpendicular to the chip friction direction; soft coatings are filled between the adjacent hard coating textures; the hard coating texture comprises a hard coating matrix and a strengthening phase dispersed and distributed in the hard coating matrix, and the soft coating comprises a lubricating material. And the soft coating material on the outermost surface effectively reduces the friction force in the cutting process, so that the generation of friction heat is reduced, and the formation of built-up edges is inhibited. The soft coating material and the hard coating texture material are arranged on the same plane at intervals below the soft coating, the hard coating texture mainly bears contact pressure and improves the wear resistance of the cutting tool in the friction process, and the soft coating can be extruded to a friction interface under the action of the contact pressure to continue the lubricating effect.

Description

Technical Field

[0001] The invention relates to the technical field of metal cutting tools, and in particular to a cutting tool friction reducing coating and a preparation method thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] As the "teeth" in the machining process, the performance of cutting tools directly affects the production efficiency and economic benefits of machining. Most of the energy involved in material removal during the cutting process will be converted into heat energy, especially into a large amount of frictional heat generated by the intense friction between the chips and the front face of the tool. A large amount of frictional heat will cause the chips to soften when passing through the front face of the tool, and then lead to the formation of built-up edge on the front face of the tool. In addition, during the metal cutting process, the tool-chip contact area on the front face of the tool will generate a large contact pressure, which is easy to cause the tool tip to break. Therefore, the tool material needs to have a high hardness while withstanding high temperatures to withstand large contact pressures. In the art, micro-textures or deposited coatings are often prepared on the front face of the tool to reduce the friction of the front face of the tool or improve the wear resistance of the tool. Micro-texture can reduce the friction of the front face of the tool, but its wear resistance and hardness still depend on the material properties of the tool itself. The types of deposited coatings mainly include hard coatings and soft coatings. Although hard coatings can improve hardness and wear resistance, they will still produce a large amount of frictional heat due to intense friction, while soft coatings have a low wear life due to their low bonding strength.

[0004] A Chinese patent application with application number 2017102879479 discloses a process for preparing a laminated composite coated tool, which has a laminated structure, high hardness, high wear resistance and oxidation resistance, can slow down the premature peeling of the coating and the expansion of cracks, and significantly improve the comprehensive performance of the coated tool, but there will still be severe friction in the tool-chip contact area. Summary of the invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a friction-reducing coating for cutting tools and a preparation method, in which a hard coating is prepared by intermittent cladding on the surface of the tool, and a soft coating is deposited between and above the hard coatings using electrohydrodynamic atomization technology, the hard coating is used to improve the wear resistance and impact resistance of the cutting tool, and the soft coating is used to reduce the friction in the tool-chip contact area, thereby inhibiting the formation of built-up edge.

[0006] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0007] The first aspect of the present invention provides a friction-reducing coating for cutting tools, comprising a hard coating and a soft coating arranged from the inside to the outside, wherein the hard coating comprises a plurality of hard coating textures arranged at intervals on the surface of the cutting tool, wherein the length direction of the hard coating texture is perpendicular to the chip friction direction; a soft coating is filled between adjacent hard coating textures; the components of the hard coating texture include a hard coating matrix and a reinforcing phase dispersed therein, and the components of the soft coating include a lubricating material.

[0008] Optionally, a main material of the hard coating includes one of a nickel-based alloy and a Co-based alloy.

[0009] Optionally, the strengthening phase includes one or more of Cr3C2, WC and TiC.

[0010] Optionally, the material of the lubricating material includes one or more of WS2, MoS2 and graphite.

[0011] Optionally, the hard coating texture is metallurgically bonded to the cutting tool.

[0012] The second aspect of the present invention provides a method for preparing the above-mentioned cutting tool friction reducing coating, comprising the steps of:

[0013] S1, ball-milling the hard coating matrix powder and the reinforcing phase powder to obtain a hard coating slurry;

[0014] S2, depositing the hard coating slurry on the surface of the cutting tool by electrohydrodynamic atomization technology to obtain a slurry layer;

[0015] S3, using laser micro-cladding technology to melt the slurry layer along a set path to obtain a hard coating texture and remove the un-clad slurry layer;

[0016] S4. Lubricating material is deposited on the tool surface using electrohydrodynamic atomization technology to obtain a friction-reducing coating for cutting tools.

[0017] Optionally, in S1, the hard coating matrix powder has a size of 10 to 20 μm, and the reinforcement phase powder has a size of 200 to 400 nm.

[0018] Optionally, in S1, the hard coating matrix powder and the reinforcing phase powder are subjected to intensive ball milling, and then ethyl cellulose and anhydrous ethanol are added and continued to be ball milled to obtain a hard coating slurry.

[0019] Optionally, in S2, in the electrohydrodynamic atomization technology, the slurry flow rate is 9 to 12 μL, the voltage is 3.5 to 4.1 kV, the metal spray needle moving speed is 15 to 30 mm / s, and the height of the spray needle from the substrate surface is 4 to 6 mm.

[0020] Optionally, in S3, in the laser micro-cladding technology, nitrogen is used as the protective atmosphere, the laser power is 2 to 6 W, the spot diameter is 15 to 25 μm, the laser scanning speed is 10 to 20 mm / s, and the laser frequency is 10 to 20 kHz.

[0021] Optionally, in S3, the method for removing the un-clad slurry layer is ultrasonic cleaning.

[0022] Optionally, in S4, the specification of the lubricating material raw material is powder of 1-2 μm.

[0023] Optionally, in S4, the lubricating material, ethyl cellulose and anhydrous ethanol are mixed evenly to obtain a lubricating material slurry.

[0024] Optionally, in S5, in the electrohydrodynamic atomization technology, the slurry flow rate is 9 to 12 μL, the voltage is 3.5 to 4.1 kV, the metal spray needle moving speed is 10 to 15 mm / s, and the height of the spray needle from the substrate surface is 4 to 6 mm.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1. The friction-reducing coating of the cutting tool provided by the present invention can effectively reduce the friction force in the cutting process due to the soft coating material deposited on the outermost surface, thereby reducing the generation of friction heat and inhibiting the formation of built-up edge. Below the soft coating, the soft coating material and the hard coating texture material are arranged in the same plane at intervals. During the friction process, the hard coating texture mainly bears the contact pressure and improves the wear resistance of the cutting tool, while the soft coating will be squeezed to the friction interface under the contact pressure, thereby continuing the lubrication effect. The friction-reducing and wear-resistant performance of the coated cutting tool prepared by this process is significantly enhanced compared with traditional single-coated tools or laminated coated tools, and the service life is greatly improved.

[0027] 2. The present invention adopts electrohydrodynamic atomization technology combined with laser micro-cladding technology to prepare hard coating texture, which has lower cost than other processes, high coating bonding strength and better wear resistance; electrohydrodynamic atomization technology is used to deposit and prepare soft coating. During the deposition process, the lubricating material will first fill the un-clad areas between the hard coatings, and then continue to deposit a layer of soft coating of a set thickness on the surface of the soft and hard coatings, which has a longer wear life than other processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0029] In order to show the positions of various parts, the distances or sizes between them are exaggerated in the figure, and the schematic diagram is for illustration only.

[0030] Figure 1Schematic diagram of the structure of the friction-reducing coating for cutting tools in Example 1.

[0031] Figure 2 1 is a graph showing the hardness and elastic modulus test results of the anti-friction coating of the cutting tool in Example 1.

[0032] Figure 3 1 is a graph showing the test results of the friction coefficient of the anti-friction coating of the cutting tool in Example 1.

[0033] Among them, 1. tool substrate; 2. hard coating texture; 3. soft coating. DETAILED DESCRIPTION

[0034] It should be noted that the following detailed descriptions are exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] A friction-reducing coating for cutting tools comprises a hard coating and a soft coating arranged from the inside outward, wherein the hard coating comprises a plurality of hard coating textures arranged at intervals on the surface of the cutting tool, wherein the length direction of the hard coating texture is perpendicular to the chip friction direction; a soft coating is filled between adjacent textures; the components of the hard coating texture comprise a hard coating matrix and a reinforcement phase dispersed therein, and the components of the soft coating comprise a lubricating material.

[0037] Through the above settings, the soft coating on the surface can effectively reduce cutting heat, and the internal soft coating material and hard coating texture material are arranged at intervals on the same plane. During the friction process, the hard coating texture mainly bears the contact pressure and improves the wear resistance of the cutting tool, while the soft coating will be squeezed to the friction interface under the contact pressure, thereby continuing the lubrication effect and greatly improving the service life of the tool.

[0038] Optionally, the material of the hard coating substrate includes one of a Ni-based alloy and a Co-based alloy, the Ni-based alloy is specifically Ni60, and most raw materials used for spraying can also be used.

[0039] Optionally, the reinforcing phase includes one or more of Cr3C2, WC and TiC, which are dispersed in the hard coating matrix to improve the impact resistance and wear resistance. The mass ratio of the reinforcing phase to the hard coating matrix is ​​(1-3): (7-9).

[0040] Optionally, the material of the lubricating material includes one or more of WS2, MoS2 and graphite, and common dry lubricant powder can be used.

[0041] Optionally, the cutting tool is one of cemented carbide and alloy steel, and can implement laser cladding process on the surface.

[0042] Optionally, the hard coating texture is metallurgically bonded to the cutting tool, the hard coating texture is mechanically bonded to the soft coating, and the soft coating is mechanically bonded to the cutting tool.

[0043] Optionally, the interval between adjacent textures in the hard coating is 50-200 μm, the width of the texture is 50-200 μm, the thickness is 10-30 μm, and the thickness of the soft coating above the texture is 5-10 μm.

[0044] A method for preparing the above-mentioned cutting tool friction reducing coating comprises the steps of:

[0045] S1, ball-milling the hard coating matrix powder and the reinforcing phase powder to obtain a hard coating slurry;

[0046] S2, depositing the hard coating slurry on the surface of the cutting tool by electrohydrodynamic atomization technology to obtain a slurry layer;

[0047] S3, using laser micro-cladding technology to melt the slurry layer along a set path to obtain a hard coating texture and remove the un-clad slurry layer;

[0048] S4. Lubricating material is deposited on the tool surface using electrohydrodynamic atomization technology to obtain a friction-reducing coating for cutting tools.

[0049] The method of combining electrohydrodynamic atomization and laser micro-cladding to prepare hard coating can achieve micron-sized structure and the hardness of the prepared hard coating is higher.

[0050] Optionally, in S1, the hard coating matrix powder has a size of 10 to 20 μm, and the reinforcement phase powder has a size of 200 to 400 nm.

[0051] Optionally, in S1, the hard coating matrix powder and the reinforcing phase powder are subjected to intensive ball milling. The particle size of the powder after intensive ball milling remains unchanged and only serves to mix evenly. Then, ethyl cellulose and anhydrous ethanol are added to continue ball milling to obtain a hard coating slurry, wherein ethyl cellulose and anhydrous ethanol are used to prepare a slurry with good dispersion effect to meet the raw material requirements of electrohydrodynamic atomization technology.

[0052] Optionally, in S2, in the electrohydrodynamic atomization technology, the slurry flow rate is 9-12 μL, the voltage is 3.5-4.1 kV, the metal spray needle moving speed is 10-15 mm / s, the height of the spray needle from the substrate surface is 4-6 mm, and a slurry layer with uniform thickness and density is prepared on the tool surface.

[0053] Optionally, in S3, in the laser micro-cladding technology, nitrogen is used as the protective atmosphere, the laser power is 2 to 6 W, the spot diameter is 15 to 30 μm, the laser scanning speed is 10 to 20 mm / s, the laser frequency is 10 to 20 kHz, and the slurry layer within the laser irradiation range is transformed into a molten state and forms a metallurgical bond with the tool surface; according to the planning of the cladding path, a protruding hard coating texture is formed on the tool surface.

[0054] Optionally, in S3, the method for removing the un-clad slurry layer is ultrasonic cleaning, which provides space for the deposition of the soft coating and prevents the powder that is not irradiated by the laser from affecting subsequent processing.

[0055] Optionally, in S4, the lubricating material powder, ethyl cellulose and anhydrous ethanol are mixed evenly to obtain a lubricating material slurry, wherein the specification of the lubricating material powder is 1-2 μm.

[0056] Optionally, in S4, in the electrohydrodynamic atomization technology, the slurry flow rate is 9-12 μL, the voltage is 3.5-4.1 kV, the metal spray needle moving speed is 10-15 mm / s, and the height of the spray needle from the substrate surface is 4-6 mm; during the deposition process, the lubricating material will first fill the un-clad areas between the hard coating textures, and then continue to deposit a layer of soft coating of a set thickness on the surface of the soft and hard coatings, finally forming a friction-reducing coating for cutting tools.

[0057] Example 1

[0058] A friction-reducing coating for cutting tools, such as Figure 1 As shown, cemented carbide YG8 is used as the tool substrate 1, and the cutting tool friction reduction coating includes a hard coating and a soft coating 3 arranged from the inside to the outside. The hard coating includes a plurality of hard coating textures 2 arranged at intervals on the surface of the cutting tool, and the length direction of the hard coating texture 2 is perpendicular to the chip friction direction; the soft coating 3 is filled between adjacent hard coating textures 2; the components of the hard coating texture 2 include a hard coating substrate and a reinforcing phase dispersed therein, and the components of the soft coating 3 include a lubricating material.

[0059] The method for preparing a cutting tool friction reducing coating on the surface of a cemented carbide tool comprises:

[0060] The carbide tool substrate was ground and polished, and ultrasonically cleaned in an alcohol solution for 20 minutes to remove oil stains;

[0061] Ni60 is used as a self-fluxing powder and Cr3C2 is used as a reinforcing phase. A Ni60 / Cr3C2 composite powder with a Cr3C2 content of 10% (mass percentage) is prepared; the prepared Ni60 / Cr3C2 composite powder is subjected to intensive ball milling for 2 hours until it is evenly mixed; 0.5g of ethyl cellulose and 25g of anhydrous ethanol are added to the ball-milled Ni60 / Cr3C2 composite powder and the mixture is ball milled again for 2 hours until it is fully mixed to obtain a hard coating slurry.

[0062] The ball-milled slurry was deposited on the surface of the tool substrate using electrohydrodynamic atomization technology. The slurry flow rate was 9 μL, the voltage was 3.7 kV, the metal spray needle moved at a speed of 10 mm / s, and the height of the spray needle from the substrate surface was 5 mm to obtain a slurry layer with a deposition thickness of 10 μm.

[0063] A laser irradiation area with a width of 100 μm and an interval of 100 μm was designed in the computer of the laser micro-cladding device. High-purity nitrogen was used as the protective atmosphere, and the laser irradiation area was irradiated until the powder of the slurry layer melted and formed a metallurgical bond with the tool matrix material. The laser processing times were 1, the laser power was 6 W, the spot diameter was 20 μm, the laser scanning speed was 180 mm / s, and the laser frequency was 20 kHz. Multiple strip-shaped hard coating textures were prepared on the surface of the tool. The spacing distance between adjacent hard coating textures was the same as that of the laser irradiation area, which was 100 μm. The width of the hard coating texture was the same as that of the laser irradiation area, which was 100 μm; the height was 10 μm; then the tool was placed in alcohol for ultrasonic cleaning for 10 minutes to remove the un-clad powder.

[0064] WS2 powder with an average particle size of 1 μm was used as a lubricating material. It was mixed with ethyl cellulose and anhydrous ethanol in a ratio of 0.5:0.1:2.5 (mass percentage), and stirred on a magnetic stirrer for 10 hours to obtain a soft coating slurry. The soft coating slurry was deposited on the surface of the hard coating and the tool substrate using electrohydrodynamic atomization technology. The electrohydrodynamic atomization parameters were: slurry flow rate of 9 μL, voltage of 3.7 kV, metal spray needle movement speed of 10 mm / s, and the height of the spray needle from the substrate surface was 5 mm. During the deposition process, MoS2 will first fill the gaps between the hard coating textures, and then continue to deposit a layer of soft coating with a thickness of 5 μm on the surface of the soft and hard coatings. At this time, the total thickness of the coating is 15 μm.

[0065] Example 2

[0066] A cutting tool friction reducing coating, using high-speed steel as the tool substrate, and a method for preparing a cutting tool friction reducing coating on the surface of a high-speed steel tool is different from that in Example 1 in that:

[0067] The slurry layer is prepared with Ni60 with a particle size of 10 μm as the self-fluxing powder and Cr3C2 with a particle size of 200 nm as the strengthening phase.

[0068] In the computer of the laser micro-cladding device, a laser irradiation area with a width of 200μm and an interval of 200μm was designed to prepare a hard coating. During the laser micro-cladding process, the laser power was 4W and the laser scanning speed was 200mm / s. Multiple strip-shaped hard coating textures were prepared on the tool surface. The distance between adjacent hard coatings was the same as the distance between the laser irradiation areas, which was 200μm. The width of the hard coating texture was the same as the width of the laser irradiation area, which was 200μm.

[0069] The soft coating was prepared using MoS2 powder with a particle size of 1-2 μm as the lubricating material, thereby obtaining a cutting tool anti-friction coating with a total thickness of 15 μm.

[0070] Test content

[0071] The performance of the anti-friction coating on the cutting tool prepared in Example 1 was tested, and a cemented carbide YG8 tool without the anti-friction coating was used as a control. The test contents included surface hardness, elastic modulus and friction coefficient.

[0072] The surface hardness test method is nanoindentation test; the elastic modulus test method is nanoindentation test; the results are as follows Figure 2 As shown, the hardness of the prepared coated tool (Example 1) is increased by 57% and the elastic modulus is increased by 9.6% compared with the cemented carbide (YG8).

[0073] The test methods of friction coefficient include: (friction and wear test); the results are as follows: Figure 3 As shown: the friction coefficient of the coating prepared on the coated tool is significantly reduced compared with the cemented carbide tool (YG8), and the low friction coefficient of 0.2 is maintained during the 30-min test.

[0074] The advantages of the cutting tool friction-reducing coating provided by the present invention are: improving the hardness and wear resistance of the tool; reducing the friction coefficient between the chips and the front cutting edge of the tool; increasing the wear life of the soft coating material during the friction process; during the processing, the soft coating material can be squeezed out to the friction interface under the action of contact pressure to achieve secondary lubrication.

[0075] The quality of the pre-set powder layer before laser cladding is also an important factor affecting the quality of the cladding layer. The pre-set powder layer prepared by electrohydrodynamic atomization can achieve controllable thickness preparation, and the surface of the powder layer is uniform, without obvious protrusions or depressions and other defects. In addition, laser micro-cladding has the characteristic of smaller spot diameter than traditional laser cladding. The spot diameter of the traditional laser cladding laser is basically millimeter-level, while the spot diameter of the laser micro-cladding laser is only 20μm, so the cladding layer can have a micron-level structure, thereby achieving better performance.

[0076] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A friction-reducing coating for cutting tools, characterized in that: It includes a hard coating and a soft coating arranged from the inside to the outside, wherein the hard coating comprises a hard coating matrix and a reinforcement phase dispersed therein, and the soft coating comprises a lubricating material; The hard coating comprises a plurality of textures arranged at intervals on the surface of the cutting tool, wherein the length direction of the textures is perpendicular to the chip friction direction; and the soft coating is filled between the adjacent textures.

2. The cutting tool friction reducing coating according to claim 1, characterized in that: The material of the hard coating substrate includes one of a Ni-based alloy and a Co-based alloy; optionally, the Ni-based alloy is specifically Ni60; Optionally, the strengthening phase includes one or more of Cr3C2, WC and TiC; Optionally, the material of the lubricating material includes one or more of WS2, MoS2 and graphite.

3. The cutting tool friction reducing coating according to claim 1, characterized in that: The hard coating is metallurgically bonded to the cutting tool.

4. The cutting tool friction reducing coating according to claim 1, characterized in that: The interval between adjacent textures in the hard coating is 50-200 μm, the width of the texture is 50-200 μm, the thickness is 10-15 μm, and the thickness of the soft coating above the texture is 5-10 μm.

5. A method for preparing a friction-reducing coating for cutting tools according to any one of claims 1 to 4, characterized in that: Includes steps: S1, ball-milling the hard coating matrix powder and the reinforcing phase powder to obtain a hard coating slurry; S2, depositing the hard coating slurry on the surface of the cutting tool by electrohydrodynamic atomization technology to obtain a slurry layer; S3, using laser micro-cladding technology to melt the slurry layer along a set path to obtain a hard coating and remove the un-clad slurry layer; S4. Lubricating material is deposited on the tool surface using electrohydrodynamic atomization technology to obtain a friction-reducing coating for cutting tools.

6. The method for preparing a friction-reducing coating for cutting tools according to claim 5, characterized in that: In S1, the hard coating matrix powder has a size of 10 to 20 μm, and the reinforcement phase powder has a size of 200 to 400 nm; Optionally, in S1, the hard coating matrix powder and the reinforcing phase powder are subjected to intensive ball milling, and then ethyl cellulose and anhydrous ethanol are added and continued to be ball milled to obtain a hard coating slurry.

7. The method for preparing a friction-reducing coating for cutting tools according to claim 8, characterized in that: In S2, in the electrohydrodynamic atomization technology, the slurry flow rate is 9-12 μL, the voltage is 3.5-4.1 kV, the metal spray needle moving speed is 10-15 mm / s, and the height of the spray needle from the substrate surface is 4-6 mm.

8. The method for preparing a friction-reducing coating for cutting tools according to claim 5, characterized in that: In S3, in the laser micro-cladding technology, nitrogen is used as the protective atmosphere, the laser power is 15-20 W, the spot diameter is 15-25 μm, the laser scanning speed is 10-20 mm / s, and the laser frequency is 10-30 kHz; Optionally, the method for removing the un-clad slurry layer is ultrasonic cleaning.

9. The method for preparing a friction-reducing coating for cutting tools according to claim 5, characterized in that: In S4, the specification of the lubricating material raw material is 1-2 μm powder; Optionally, in S4, the lubricating material, ethyl cellulose and anhydrous ethanol are mixed evenly to obtain a lubricating material slurry.

10. The method for preparing a friction-reducing coating for cutting tools according to claim 5, characterized in that: In S4, in the electrohydrodynamic atomization technology, the slurry flow rate is 9 to 12 μL, the voltage is 3.5 to 4.1 kV, the metal needle moving speed is 10 to 15 mm / s, and the height of the needle from the substrate surface is 4 to 6 mm.

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