Tool manufacturing methods

Abstract

To provide a tool processing method that can further improve life of a tool.SOLUTION: A processing method for a tool 1 includes a process in which compressive residual stress is applied to the tool 1 by laser peening with use of pulse laser. In the application process, a laser irradiation time difference between adjacent laser irradiation points is controlled, whereby occurring anisotropy in the compressive residual stress applied to the tool 1.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This disclosure relates to a method for processing tools.

Background Art

[0002] Patent Document 1 describes a method for improving the wear resistance of cemented carbide using laser peening. In the tool processed by this method, the fracture toughness increases, resulting in an improved service life.

Prior Art Documents

Patent Documents

[0003] <00oooo24>

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of this disclosure is to provide a method for processing tools that can further improve the service life of the tools.

Means for Solving the Problems

[0005] The method for processing a tool according to one aspect of this disclosure includes a step of applying compressive residual stress to the tool by laser peening using a pulsed laser. The tool includes a substrate and a coating layer that covers at least a part of the surface of the substrate. In the applying step, compressive residual stress is applied to the tool such that the difference in compressive residual stress at the interface between the substrate and the coating layer is 100 MPa or less.

Effects of the Invention

[0006] According to this disclosure, a method for processing tools that can further improve the service life of the tools is provided.

Brief Description of the Drawings

[0007] [Figure 1]Figure 1 is a plan view showing an example of a tool prepared in the preparation process. [Figure 2] Figure 2 is a diagram showing the configuration of the laser irradiation device used in the stress application process. [Figure 3] Figure 3 is a diagram illustrating the direction of laser peening application to the tool. [Figure 4] Figure 4 is a diagram illustrating the direction of laser peening application to the tool. [Figure 5] Figure 5 shows an EDS elemental mapping image of the tool after machining. [Figure 6] Figure 6 shows an SEM image of the tool after machining. [Modes for carrying out the invention]

[0008] [Summary of the embodiments of this disclosure] First, an overview of the embodiments of this disclosure will be provided.

[0009] (Clause 1) A method for processing a tool according to one aspect of the present disclosure includes a step of imparting compressive residual stress to a tool by laser peening using a pulsed laser. The tool comprises a base material and a coating layer covering at least a portion of the surface of the base material. In the imparting step, compressive residual stress is applied to the tool such that the difference in compressive residual stress at the interface between the base material and the coating layer is 100 MPa or less.

[0010] In the above-described tool processing method, compressive residual stress is applied to the tool in such a way that the difference in compressive residual stress at the interface between the substrate and the coating layer is suppressed, thereby preventing the peeling of the coating layer. This further improves the tool's lifespan.

[0011] (Clause 2) In the tool processing method described in Clause 1 above, the base material is made of a sintered body or carbide having a hardness of 4000 HV or more and 8000 HV or less, and the coating layer may be made of carbide, nitride, and carbonitride.

[0012] (Clause 3) In the method for machining a tool described in Clause 1 or 2 above, in the step of applying, anisotropy may be induced in the compressive residual stress applied to the tool by controlling the difference in laser irradiation time between adjacent laser irradiation points. In this case, since anisotropy can be induced in the compressive residual stress applied to the tool, for example, if laser peening is performed so that the compressive residual stress reaches the maximum value in the direction that becomes the feed force or the back force of the cutting resistance when the tool is used for cutting, the tool life can be further improved.

[0013] (Clause 4) In the method for machining a tool described in any one of Clauses 1 to 3 above, in the step of applying, a pulsed laser with a power density on the surface of the tool of 10 GW / cm 2 or less may be irradiated. In this case, surface damage of the tool is suppressed.

[0014] (Clause 5) In the method for machining a tool described in Clause 4 above, in the step of applying, a pulsed laser with a power density on the surface of the tool of 0.2 GW / cm 2 or more may be irradiated. In this case, laser ablation can be surely generated, and compressive residual stress can be applied to the tool.

[0015] (Clause 6) In the method for machining a tool described in any one of Clauses 1 to 5 above, in the step of applying, the tool may be irradiated with a pulsed laser having a pulse width of 5 nsec or more. In this case, laser ablation can be surely generated, and compressive residual stress can be applied to the tool.

[0016] (Clause 7) In the method for machining a tool described in any one of Clauses 1 to 6 above, in the step of applying, laser peening may be performed on the entire surface of the coating layer. In this case, if a coating layer is provided on the cutting edge portion where actual cutting or the like is performed, the defect resistance of the cutting edge portion can be surely improved.

[0017] (Article 8) In the method for machining a tool according to any one of the above Articles 1 to 7, in the step of applying, laser peening may be performed so that the laser irradiation points are arranged in a square lattice. In this case, the laser application area can be completely laser-peened.

[0018] [Examples of Embodiments of the Present Disclosure] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals will be used for the same elements or elements having the same function, and redundant descriptions will be omitted.

[0019] The method for machining a tool according to the embodiment is a method for improving the defect resistance of the tool and further improving the tool life by applying compressive residual stress to the tool. Examples of the tool to be machined include cutting tools and stamping tools. The method for machining a tool according to the embodiment includes a preparation step of preparing a tool and a stress application step of applying compressive residual stress to the tool.

[0020] FIG. 1 is a plan view showing an example of a tool prepared by the preparation step. The tool 1 in this example is a cutting tool. More specifically, the tool 1 is a throw-away tip that is used by being attached to a holder and is configured to be replaceable. The tool 1 is, for example, a lathe tip or a milling cutter tip. The tool 1 includes a base material 2 and a coating layer 3.

[0021] The base material 2 is made of a sintered body or a carbide. The base material 2 is made of, for example, cBN, WC, ceramic, or carbon steel. The hardness of the base material 2 is 4000 HV or more and 8000 HV or less. The base material 2 has a substantially rhombic shape with the direction D1 as the short axis direction and the direction D2 as the long axis direction in a plan view. The base material 2 has a pair of corner portions 2a that are diagonally located with respect to each other in the direction D1. The pair of corner portions 2a constitute a cutting edge portion that actually performs cutting or the like. A circular through hole 2b is provided at the center of the base material 2. The through hole 2b is used when attaching the tool 1 to a holder.

[0022] The coating layer 3 covers at least a portion of the surface of the substrate 2. In this embodiment, the coating layer 3 covers the surface of a pair of corners 2a. The coating layer 3 is made of carbide, nitride, or carbonitride. For example, the coating layer 3 is made of TiAlN, TiN, TiCN, ZrN, or DLC. The coating layer 3 has a hardness equal to or greater than the hardness of the substrate 2. The coating layer 3 is formed, for example, by chemical vapor deposition or physical vapor deposition. The thickness of the coating layer 3 is 0.5 μm or more, for example, 3 μm. The coating layer 3 is provided for the purpose of suppressing adhesion of the workpiece to the tool 1 and improving the wear resistance of the tool 1. The coating layer 3 may be provided on the entire surface of the substrate 2, but by providing it only on the pair of corners 2a, processing time and processing costs can be reduced.

[0023] During cutting, tool 1 experiences cutting resistance (stress) due to the workpiece. When tool 1 is a lathe insert or milling machine insert, the cutting resistance can be divided into three components: a principal force, a feed force, and a back force, all of which are orthogonal to each other. The principal force is a force that occurs in the opposite direction to the rotation of the lathe or milling machine. The feed force is a force that occurs in the feed direction of the workpiece relative to tool 1. The back force is a force that occurs in the radial direction of the workpiece in the case of a lathe insert, and a force that occurs in the axial direction of the milling machine in the case of a milling machine insert.

[0024] The magnitudes of the main force, feed force, and back force vary depending on the material of the workpiece, cutting speed, depth of cut, and cutting edge angle. Typically, the main force is larger than the feed force and back force. In tool 1 shown in Figure 1, the main force occurs in the thickness direction of tool 1, i.e., in a direction perpendicular to directions D1 and D2. The feed force occurs in the short axis direction of tool 1, i.e., along direction D1. The back force occurs in the long axis direction of tool 1, i.e., along direction D2.

[0025] The stress application process involves applying compressive residual stress to the tool 1 by laser peening using a pulsed laser. Laser peening allows compressive residual stress to be applied to the surface layer 1a of the tool 1 without causing plastic deformation of the tool 1. Here, the surface layer 1a is a region with a depth from the surface of the tool 1 of, for example, 100 μm or less. The thickness of the surface layer 1a is greater than the thickness of the coating layer 3.

[0026] The stress application process is carried out using shock waves generated by laser ablation. Laser peening is a method of applying compressive residual stress to the inside of a material, similar to shot peening and burnishing. In shot peening and burnishing, the media or tool is brought into physical contact with the material surface, whereas in laser peening, there is no such physical contact. In laser peening, by using shock waves, plastic strain can be generated in tool 1 without changing the crystalline state of tool 1. The plastic strain caused by the shock wave is generated by the propagation of a pressure wave inside tool 1, so no deformation or refinement of crystal grains occurs. Therefore, the shock wave only generates plastic strain inside the crystal grains. Thus, compressive residual stress can be applied without transforming the microstructure.

[0027] The stress application process is carried out with the tool 1 in a cooled state. Examples of cooling methods include water cooling and air cooling. Cooling may also be carried out using liquids other than water and gases other than air. The stress application process is carried out, for example, with the tool 1 placed in a liquid. The stress application process is carried out, for example, at room temperature.

[0028] Laser peening is performed, for example, on the entire surface of the coating layer 3. As described above, the thickness of the surface layer 1a to which compressive residual stress is applied is greater than the thickness of the coating layer 3. Therefore, compressive residual stress is applied not only to the coating layer 3 but also to the surface layer of the substrate 2 covered by the coating layer 3. In other words, in this case, the surface layer 1a includes both the coating layer 3 and the surface layer of the substrate 2.

[0029] In the stress application step, residual compressive stress is applied to the surface layer 1a, including the coating layer 3 and the surface layer of the substrate 2, without damaging the coating layer 3. In the stress application step, compressive residual stress is applied to the tool 1 such that the difference (absolute value) of compressive residual stress at the interface between the substrate 2 and the coating layer 3 is 100 MPa or less, preferably 50 MPa or less, and more preferably 10 MPa or less.

[0030] Figure 2 is a diagram showing the configuration of a laser irradiation device used in the stress application process. As shown in Figure 2, the laser irradiation device 10 comprises a laser oscillator 11, reflective mirrors 12 and 13, a focusing lens 14, a water tank 15, a holding unit 16, and a control device 17. The laser oscillator 11 is a device that emits laser light L. The reflective mirrors 12 and 13 transmit the laser light L emitted by the laser oscillator 11 to the focusing lens 14. The focusing lens 14 concentrates the laser light L at a high density to the processing position of the tool 1. The water tank 15 is filled with a transparent liquid 18 such as water. The holding unit 16 holds the tool 1 and places the tool 1 in the water tank 15. The holding unit 16 is an actuator or a robot.

[0031] The laser irradiation device 10 is controlled by a control device 17. The control device 17 is configured as a motion controller, such as a PLC (Programmable Logic Controller) or a DSP (Digital Signal Processor). The control device 17 may also be configured as a computer system including a processor such as a CPU (Central Processing Unit), memory such as RAM (Random Access Memory) and ROM (Read Only Memory), input / output devices such as a touch panel, mouse, keyboard, and display, and communication devices such as a network card. The control device 17 realizes its functions by operating each piece of hardware under the control of the processor based on a computer program stored in memory.

[0032] When performing the stress application process using the laser irradiation device 10, first, the tool 1 is placed in the holding unit 16. Next, the holding unit 16 moves the tool 1 into the water tank 15, placing the tool 1 in the liquid 18. Then, with the tool 1 cooled by the liquid 18, the tool 1 is irradiated with laser light L. The laser light L is a pulsed laser that is irradiated at regular time intervals. The pulse width of the laser light L is 5 nsec or more.

[0033] The laser beam L is emitted by the laser oscillator 11 and then transmitted to the focusing lens 14 via an optical system consisting of reflective mirrors 12 and 13. The laser beam L is focused to high density by the focusing lens 14 and irradiated onto the surface of the tool 1 through the liquid 18. The power density of the laser beam L is 0.2 GW / cm². 2 More than 10GW / cm 2 The following settings will be applied.

[0034] In tool 1, the peening effect by laser peening occurs as follows. First, when the laser beam L is irradiated onto the surface of tool 1, laser ablation occurs on the surface of tool 1, generating plasma. In the atmosphere, the material at the irradiation point vaporizes. Since the irradiation point on tool 1 is covered with liquid 18, the expansion of the plasma is suppressed. As a result, the plasma becomes high pressure, and a shock wave is generated by the pressure of the plasma. As the shock wave propagates, a plastic deformation region is created inside tool 1. In the plastic deformation region, compressive residual stress is generated due to constraint from the undeformed portion. As described above, plastic deformation due to the shock wave is not plastic working, so no deformation or refinement of crystal grains occurs. To suppress ablation of tool 1, a sacrificial layer (not shown) may be provided on tool 1. The sacrificial layer is, for example, black PVC tape.

[0035] The irradiation of the laser beam L is performed in accordance with the operation of the holding unit 16, shifting the laser irradiation point on the tool 1. The holding unit 16 moves the tool 1 each time the laser beam L is irradiated, thereby shifting the laser irradiation point on the tool 1.

[0036] Figures 3 and 4 illustrate the direction of laser peening on a tool. In Figures 3 and 4, the area where laser peening is performed (laser application area) is shown in magnified view. In both Figures 3 and 4, laser peening is performed on tool 1 while moving the laser irradiation point in a zigzag pattern. In Figures 3 and 4, the arrows indicating the direction of laser peening are magnified and shown extending beyond the coating layer 3, but in reality, the laser application area is set to coincide with the area where the coating layer 3 is applied.

[0037] In Figure 3, at regular time intervals, the pulsed laser is irradiated while sequentially moving the laser irradiation point along direction D1 within the laser treatment area. When the laser irradiation point reaches the end of direction D1 in the laser treatment area, the laser irradiation point is moved once along direction D2 and the pulsed laser is irradiated again. Subsequently, the process of sequentially moving the laser irradiation point in the opposite direction along direction D1 and irradiating with the pulsed laser is repeated. In other words, in direction D1, laser peening is performed continuously while scanning the laser irradiation point, while in direction D2, laser peening is performed intermittently.

[0038] Here, "continuous" means that laser peening is performed at intervals corresponding to the pulse laser irradiation intervals. "Intermittent" means that laser peening is performed at intervals that are not continuous. Therefore, if there are areas where laser peening is performed at time intervals different from the pulse laser irradiation intervals, it is considered "intermittent."

[0039] In the case of Figure 3, the difference in laser irradiation time between adjacent laser irradiation points in direction D1 is less than or equal to the difference in laser irradiation time between adjacent laser irradiation points in direction D2. Excluding the laser irradiation point located at the end of direction D1 within the laser treatment area, the difference in laser irradiation time between adjacent laser irradiation points in direction D1 is shorter than the difference in laser irradiation time between adjacent laser irradiation points in direction D2. Due to this difference in laser irradiation time, anisotropy is introduced to the compressive residual stress, and the residual compressive stress in direction D2 becomes greater than the residual compressive stress in direction D1.

[0040] In Figure 4, the pulsed laser is irradiated while sequentially moving the laser irradiation point along direction D2 within the laser treatment area at each pulsed laser irradiation interval. When the laser irradiation point reaches the end of direction D2 in the laser treatment area, the laser irradiation point is moved once along direction D1 and the pulsed laser is irradiated. Subsequently, the process of sequentially moving the laser irradiation point in the opposite direction along direction D2 and irradiating with the pulsed laser is repeated. In other words, in direction D2, laser peening is performed continuously while scanning the laser irradiation point, while in direction D1, laser peening is performed intermittently.

[0041] In the case of Figure 4, the difference in laser irradiation time between adjacent laser irradiation points in direction D2 is less than or equal to the difference in laser irradiation time between adjacent laser irradiation points in direction D1. Excluding the laser irradiation point located at the end of direction D2 within the laser treatment area, the difference in laser irradiation time between adjacent laser irradiation points in direction D2 is shorter than the difference in laser irradiation time between adjacent laser irradiation points in direction D1. Due to this difference in laser irradiation time, anisotropy is imparted to the compressive residual stress, and the residual compressive stress in direction D1 becomes greater than the residual compressive stress in direction D2.

[0042] In the stress application process, anisotropy is created in the compressive residual stress applied to tool 1 by controlling the difference in laser irradiation time between adjacent laser irradiation points. In Figures 3 and 4, for example, laser peening is performed so that the laser irradiation points are arranged in a square grid. That is, the distance between adjacent laser irradiation points in direction D1 is equal to the distance between adjacent laser irradiation points in direction D2.

[0043] According to the application direction in Figure 3, residual compressive stress is applied more strongly in the back force direction (direction D2) than in the feed force direction (direction D1) of the cutting resistance. According to the application direction in Figure 4, residual compressive stress is applied more strongly in the feed force direction (direction D1) of the cutting resistance than in the back force direction (direction D2) of the cutting resistance. Therefore, by selecting the application direction of laser peening according to the operating conditions of tool 1, the lifespan of tool 1 can be further improved. For example, for operating conditions where the back force is greater than the feed force, the application direction in Figure 3 can be selected, and for operating conditions where the feed force is greater than the back force, the application direction in Figure 4 can be selected to effectively strengthen tool 1. The compressive residual stress introduced into tool 1 is difficult to release in the thickness direction of tool 1, but is easily released in the in-plane direction of tool 1. From this point of view as well, it is important to apply residual compressive stress to tool 1 that has anisotropy in the feed force direction and the back force direction of the cutting resistance.

[0044] As described above, in the tool processing method according to the embodiment, compressive residual stress is applied to the tool 1 in the stress application step such that the difference in compressive residual stress at the interface between the base material 2 and the coating layer 3 is 100 MPa or less, thereby suppressing the peeling of the coating layer 3. This further improves the lifespan of the tool 1.

[0045] The base material 2 consists of a sintered body or carbide with a hardness of 4000 HV to 8000 HV. The coating layer 3 consists of carbides, nitrides, and carbonitrides, and covers a pair of corners 2a that constitute the cutting edge of the base material 2. In this way, since the base material 2 is made of a hard material and the cutting edge is covered by the coating layer 3, the lifespan of the tool 1 can be further improved.

[0046] In the tool processing method according to this embodiment, anisotropy can be introduced into the compressive residual stress applied to the tool 1 by controlling the difference in laser irradiation time between adjacent laser irradiation points. For example, the lifespan of the tool 1 can be further improved by performing laser peening such that the compressive residual stress is maximized in the direction that is the main component of the cutting force when the tool 1 is used for cutting.

[0047] During the stress application process, the power density on the surface of tool 1 is 0.2 GW / cm². 2 More than 10GW / cm 2 The following pulsed laser is used: 10 GW / cm² 2 The following conditions suppress surface damage to tool 1: 0.2 GW / cm² 2 As a result of the above, laser ablation can be reliably generated and compressive residual stress can be applied.

[0048] The pulse width of the pulsed laser used in the stress application process is 5 nsec or more. Therefore, laser ablation can be reliably generated, and compressive residual stress can be applied to tool 1.

[0049] In the stress application process, laser peening is performed on the entire surface of the coating layer 3 provided on the cutting edge of the base material 2, thereby reliably improving the chipping resistance of the cutting edge.

[0050] In the stress application process, laser peening is performed so that the laser irradiation points are arranged in a square grid, ensuring that the entire laser treatment area is laser peened.

[0051] The present invention is not necessarily limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention.

[0052] The following describes an example of an experiment.

[0053] (Experimental Examples 1-4) First, a TiAlN coating was applied to a cBN cutting tip, and a tool comprising a cBN substrate and a TiAlN coating layer was prepared. Next, to suppress ablation of the substrate and coating layer, a black PVC tape serving as a sacrificial layer was applied to the coating layer. Subsequently, laser peening was performed on the sacrificial layer under the conditions shown in Table 1, and tools relating to Experimental Examples 1-4 were obtained. The processing direction for Experimental Examples 1 and 3 corresponds to the processing direction shown in Figure 3 (continuous with direction D1), and the processing direction for Experimental Examples 2 and 4 corresponds to the processing direction shown in Figure 4 (continuous with direction D2).

[0054] [Table 1]

[0055] (Experimental Example 5) Uncoated tools were prepared using cBN cutting tips without TiAlN coating. Next, a black PVC tape, which would serve as a sacrificial layer, was directly applied to the substrate. Then, laser peening was performed under the same conditions as in Experimental Example 1 regarding pulse energy, spot diameter, power density, coverage, and application direction, to obtain the tool described in Experimental Example 5.

[0056] (Experimental Example 6) As a non-LP product that does not undergo laser peening, the tool for Experimental Example 6 was prepared. The tool for Experimental Example 6 has a base material made of cBN and a coating layer made of TiAlN, similar to the tool for Experimental Example 1.

[0057] (cutting) Using the tools from Experimental Examples 1-6, S55C material was machined on a lathe for 300 seconds. The cutting edge of each tool was observed after machining. In Experimental Examples 1-3 and 6, the coating layer peeled off. In Experimental Example 4, the coating layer did not peel off. In Experimental Example 5, since the tool was uncoated, coating layer peeling was not a problem, but cemented carbide adhesion occurred to the cBN substrate.

[0058] Figure 5 shows the EDS (Energy Dispersive X-ray Spectroscopy) elemental mapping image of a tool after machining. In Figure 5, the EDS elemental mapping images are shown as observation results for tools in Experimental Examples 1, 4, and 6. In the tools of Experimental Examples 1 and 6, it was confirmed that the amount of Ti and Al elements in the coating layer decreased due to peeling, and areas where B element from the substrate was detected were observed. In the tool of Experimental Example 4, it was confirmed that there was little elemental bias and no peeling occurred.

[0059] Figure 6 shows SEM images of tools after machining. Figure 6 shows the SEM images of the tools from Experimental Examples 1, 4, and 6. The SEM images confirmed that delamination of the coating layer occurred in the tools from Experimental Examples 1 and 6. No delamination of the coating layer occurred in the tool from Experimental Example 4.

[0060] (Measurement of residual stress) For the tools in Experimental Examples 1 and 2, residual stress measurements were performed before and after laser peening. An X-ray diffractometer manufactured by Rigagu Co., Ltd. was used for the measurements. Table 2 shows the measurement conditions, and Table 3 shows the measurement results at the interface between the cBN substrate and the TiAlN layer. Since X-ray diffraction is used for residual stress measurement, the X-ray diffraction peaks overlap. Therefore, the residual stress values ​​of the cBN substrate and the TiAlN layer were calculated from the measurement conditions and phase fractions shown in Table 2.

[0061] [Table 2]

[0062] [Table 3]

[0063] As can be calculated from the results in Table 3, in Experimental Example 1, the change in residual stress of the cBN substrate was -113 MPa when the X-ray incidence direction was D1, and -34 MPa when the X-ray incidence direction was D2. In Experimental Example 2, the change in residual stress of the cBN substrate was -35 MPa when the X-ray incidence direction was D1, and -162 MPa when the X-ray incidence direction was D2. As shown in Table 1, in Experimental Example 1, laser peening was performed continuously in direction D1. In Experimental Example 2, laser peening was performed continuously in direction D2. In other words, it was confirmed that when the X-ray incidence direction coincided with the laser peening direction, the change in residual stress was larger than when these directions did not coincide. [Explanation of Symbols]

[0064] 1...Tool, 2...Base material, 3...Coating layer.

Claims

1. The process includes a step of applying compressive residual stress to a tool by laser peening using a pulsed laser, The tool comprises a base material and a coating layer covering at least a portion of the surface of the base material. In the aforementioned step of applying compressive residual stress, compressive residual stress is applied to the tool such that the difference in compressive residual stress at the interface between the substrate and the coating layer is 100 MPa or less. In the above-mentioned application step, the tool is irradiated with a pulsed laser having a pulse width of 5 nsec or more. Methods for manufacturing tools.

2. The process includes a step of applying compressive residual stress to a tool by laser peening using a pulsed laser, The tool comprises a base material and a coating layer covering at least a portion of the surface of the base material. In the aforementioned step of applying compressive residual stress, compressive residual stress is applied to the tool such that the difference in compressive residual stress at the interface between the substrate and the coating layer is 100 MPa or less. In the above-mentioned process, a pulsed laser having a power density of 10 GW / cm² or less on the surface of the tool is irradiated. Methods for manufacturing tools.

3. In the aforementioned process, the power density on the surface of the tool is 0.2 GW / cm². ２ The pulsed laser described above is used to irradiate the area. The method for machining the tool described in claim 2.

4. The aforementioned substrate is made of a sintered body or carbide having a hardness of 4000 HV or more and 8000 HV or less. The coating layer consists of carbides, nitrides, and carbonitrides. A method for machining a tool according to any one of claims 1 to 3.

5. In the aforementioned process of applying the stress, anisotropy is created in the compressive residual stress applied to the tool by controlling the difference in laser irradiation time between adjacent laser irradiation points. A method for machining a tool according to any one of claims 1 to 3.

6. In the aforementioned application step, laser peening is performed on the entire surface of the coating layer. A method for machining a tool according to any one of claims 1 to 3.

7. In the aforementioned application process, laser peening is performed so that the laser irradiation points are arranged in a square grid pattern. A method for machining a tool according to any one of claims 1 to 3.

Images