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CN-121992402-A - Manufacturing method of DLC coated milling cutter

CN121992402ACN 121992402 ACN121992402 ACN 121992402ACN-121992402-A

Abstract

The invention provides a manufacturing method of a DLC coated milling cutter, which comprises four steps of matrix gradient pretreatment, composite coating deposition, targeted sub-zero treatment and precise finishing detection, wherein gradient strengthening of quenching-tempering-sub-zero pretreatment is carried out on a WC-Co hard alloy matrix, gradient component DLC coating is deposited by adopting a PECVD and IBAD composite process, the carbon bond hybridization state is regulated and controlled by matching with-140 ℃ targeted sub-zero treatment, the microhardness of the milling cutter coating reaches 28-32GPa finally, the friction coefficient is reduced to 0.08-0.12, the critical load of film base binding force is more than or equal to 60N, and the service life of the milling cutter is prolonged by 2-3 times compared with that of the traditional DLC coated milling cutter under the high-speed cutting working condition of aluminum alloy and titanium alloy.

Inventors

  • ZHANG JUN
  • YANG XIAOSHAN

Assignees

  • 四川德克普数控机床有限公司

Dates

Publication Date
20260508
Application Date
20260129

Claims (10)

  1. 1. The manufacturing method of the DLC coated milling cutter is characterized by comprising the following steps of: The gradient pretreatment of a matrix comprises the steps of selecting a WC-Co hard alloy milling cutter matrix, sequentially carrying out quenching, tempering, cryogenic pretreatment and surface activation treatment, wherein the quenching temperature is 1420 ℃ to 1520 ℃, the temperature is kept for 1.5 to 3.5 hours, then the quenching is cooled to room temperature, tempering is carried out in two stages, the temperature is kept at 190 ℃ to 230 ℃ for 2.5 to 4.5 hours, the temperature is kept at 480 ℃ to 530 ℃ for 1.5 to 3 hours in the second stage, the quenching is carried out to room temperature, the cryogenic pretreatment temperature is minus 130 ℃ to 150 ℃, the temperature is kept at 24 to 36 hours, the natural temperature is raised to room temperature, and the surface activation treatment adopts plasma cleaning to remove oxides and pollutants on the surface of the matrix, so that the surface activity is improved; The method comprises the steps of depositing a composite coating, namely placing a pretreated milling cutter matrix in composite deposition equipment, depositing a transition layer and then depositing a DLC gradual change coating, wherein the transition layer is of a metal/metal nitride alternating stacked structure, and is prepared by adopting a magnetron sputtering process, and the deposition temperature is 170-210 ℃; The targeted cryogenic post-treatment, namely placing the milling cutter with the deposited coating in a cryogenic treatment device, cooling to a target cryogenic temperature at a speed of 4-9 ℃ per minute, preserving heat for 24-36 hours, and then heating to room temperature at a speed of 1.5-3.5 ℃ per minute. And (3) precision finishing and detection, namely performing cutting edge precision finishing on the milling cutter to ensure that the cutting edge radius and the surface roughness meet the high-precision cutting requirements, and screening qualified products through hardness detection, binding force detection and friction performance detection.
  2. 2. The DLC coated milling cutter manufacturing method according to claim 1, wherein the cryogenic pretreatment temperature is-140 ℃, the temperature is kept for 30 hours, the magnetic field interference is avoided in the whole process, the argon flow of the surface activation treatment is 20-30sccm, the vacuum degree is 0.5-1Pa, and the treatment time is 15-20min.
  3. 3. The method for manufacturing the DLC coated milling cutter according to claim 1, wherein the Co content in the WC-Co hard alloy matrix is 6-8wt%, the average grain diameter of WC is 0.4-0.8μm, the surface hardness of the matrix after gradient pretreatment is equal to or more than 1800HV, the core toughness is equal to or more than 15J/cm < 2 >, and the quenching adopts an oil cooling mode and an air cooling mode after tempering.
  4. 4. The DLC coated milling cutter manufacturing method according to claim 1, wherein the transition layer is of a Cr/CrN alternately stacked structure, the thickness of the Cr layer is 50-80nm, the thickness of the CrN layer is 80-120nm, 3-5 groups are alternately stacked, the power of the magnetron sputtering target is 1.2-1.5kW, and the transition layer can be of a Ti/TiN alternately stacked structure.
  5. 5. The DLC coated milling cutter manufacturing method according to claim 1, wherein the composite coating deposition adopts a PECVD-IBAD composite process, the carbon-containing gas is a mixture of methane and acetylene, the doping source is silane, the volume ratio of methane to acetylene in the deposition process is increased from 1:2 to 2:1, the silane flow is reduced from 10sccm to 2sccm, the IBAD energy is controlled to be 80-100eV, and the beam current density is 0.8-1.2mA/cm2.
  6. 6. The DLC coated milling cutter manufacturing method according to claim 1 or 5, wherein in the composite coating deposition process, the base pressure in the vacuum cavity is less than or equal to 5 x 10- 4 Pa, the working pressure is maintained at 1-3Pa, the bias voltage is controlled at-50 to-80V, and the deposition temperature is less than or equal to 220 ℃.
  7. 7. The DLC coated milling cutter manufacturing method according to claim 1, wherein the target temperature of the targeted cryogenic post-treatment is-140 ℃, the temperature is kept for 30 hours, the cooling rate is 5-8 ℃ per minute, the heating rate is 2-3 ℃ per minute, the vacuum environment is maintained in the whole process, and the vacuum degree is not less than 1 multiplied by 10 < -3 > Pa.
  8. 8. The method for manufacturing the DLC coated milling cutter according to claim 1 or 7, wherein after the targeted cryogenic post-treatment, the sp3/sp2 bond ratio in the DLC coating is more than or equal to 0.52, and the residual compressive stress is controlled to be-1.2 to-0.8 GPa, so that crack growth is effectively inhibited.
  9. 9. The DLC coated milling cutter manufacturing method according to claim 1, wherein the precise trimming adopts a mode of combining chemical mechanical polishing and laser micro-trimming, the polishing liquid is alkaline colloidal silica polishing liquid, the laser power is controlled to be 5-10W, the cutting edge radius after trimming is controlled to be 0.01-0.03mm, and the surface roughness Ra is less than or equal to 0.2 μm.
  10. 10. The method for manufacturing the DLC coated milling cutter according to claim 1, wherein the hardness test is to measure the hardness of the coating by a nanoindentation method, the binding force test is to measure the binding force of the film base by a scratch test, and the friction performance test is to measure the friction coefficient by a ball-disc friction test.

Description

Manufacturing method of DLC coated milling cutter Technical Field The invention relates to the technical field of numerical control cutter manufacturing and surface coating, in particular to a manufacturing method of a DLC coated milling cutter. Background DLC (diamond like carbon) coatings have become one of the core technologies for improving the performance of numerical control milling cutters by virtue of high hardness, low friction coefficient, excellent wear resistance and corrosion resistance. Along with the continuous improvement of requirements on cutting precision, efficiency and cutter service life in the field of high-end manufacturing, the application scene of the DLC coated milling cutter is continuously expanded, but a plurality of technical bottlenecks still exist in the existing manufacturing process. The traditional DLC coated milling cutter adopts a single PVD or CVD process to deposit a coating, has the problems of insufficient film base binding force and excessive internal stress of the coating, and is easy to crack, and the phenomenon of coating spalling and cutting edge breakage is easy to occur under the working condition of high-speed intermittent cutting. Meanwhile, the existing technology is difficult to combine the hardness and toughness of the coating, if the high hardness is pursued, the brittleness of the coating is increased, and if the toughness is emphasized, the hardness and the wear resistance are reduced. In addition, the high-temperature deposition or post-treatment mode adopted by part of the process can negatively influence the performance of the WC-Co hard alloy matrix, and further restricts the overall service life of the milling cutter. In the prior art, the cryogenic treatment proves that the structure and the performance of the DLC coating can be optimized, the hardness and the binding force are improved by regulating and controlling the hybridization state of carbon bonds, but the traditional cryogenic process parameters are extensive, the cryogenic treatment is mostly carried out by adopting liquid nitrogen at the temperature of-196 ℃, the stress mismatch between the coating and the substrate is easy to cause, and the cooperative optimization is not formed with the coating deposition process. Meanwhile, although the application of the gradient coating and the composite deposition process has advanced to a certain extent, the gradient coating and the composite deposition process still need to be improved in the aspects of ingredient gradual change regulation, transition layer suitability and the like, and the performance potential of the DLC coating cannot be fully exerted. Therefore, development of a DLC coating milling cutter manufacturing process with high film base binding force, high hardness and low internal stress becomes a technical problem to be solved urgently in the industry. Disclosure of Invention Aiming at the problems of insufficient film base binding force, excessive internal stress, poor performance cooperativity and the like in the existing DLC coated milling cutter manufacturing process, the invention provides the manufacturing method of the high-performance DLC coated milling cutter, and the optimal balance of coating hardness, toughness and binding force is realized through the cooperative design of matrix gradient pretreatment, composite coating deposition and targeted cryogenic post-treatment, so that the service life and stability of the milling cutter under the high-speed cutting working condition are obviously improved. In view of the above-described deficiencies of the prior art, In order to achieve the above purpose, the invention provides a DLC coated milling cutter manufacturing method, which comprises the following specific steps: The gradient pretreatment of a matrix comprises the steps of selecting a WC-Co hard alloy milling cutter matrix, sequentially carrying out quenching, tempering, cryogenic pretreatment and surface activation treatment, wherein the quenching temperature is 1420 ℃ to 1520 ℃, the temperature is kept for 1.5 to 3.5 hours, then the quenching is cooled to room temperature, tempering is carried out in two stages, the temperature is kept at 190 ℃ to 230 ℃ for 2.5 to 4.5 hours, the temperature is kept at 480 ℃ to 530 ℃ for 1.5 to 3 hours in the second stage, the quenching is carried out to room temperature, the cryogenic pretreatment temperature is minus 130 ℃ to 150 ℃, the temperature is kept at 24 to 36 hours, the natural temperature is raised to room temperature, and the surface activation treatment adopts plasma cleaning to remove oxides and pollutants on the surface of the matrix, so that the surface activity is improved; The method comprises the steps of depositing a composite coating, namely placing a pretreated milling cutter matrix in composite deposition equipment, depositing a transition layer and then depositing a DLC gradual change coating, wherein the transition layer is of a metal/metal nitride alter