Processing methods

Abstract

To provide a processing method that can suppress tool wear resistance while reducing cutting resistance in cutting a hard-to-grinding material while heating it, and to provide a tool.SOLUTION: A processing method for processing a material to be ground includes: a heating step of heating the material to be ground; and a processing step of processing the material to be ground that has been heated in the heating step by pressing a blade tool thereon. In the processing step, processing is performed while a rake angle is negative.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a processing method. law, A processing method in which difficult-to-cut materials are cut while heated. By law Regarding. [Background technology]

[0002] In the additive manufacturing method, as disclosed in Patent Document 1, for example, a pulsed laser energy is applied to a raw material powder supplied to a substrate to repeatedly melt and solidify the raw material powder to obtain a three-dimensional additively manufactured object. According to the additive manufacturing method, a three-dimensional product can be obtained in a net shape or near net shape.

[0003] Additively manufactured bodies obtained by additive manufacturing methods can form near-net shapes that are close to the design dimensions, but as additively manufactured bodies, they cannot reach the dimensional accuracy and surface roughness that can be obtained by cutting or plastic processing. Therefore, depending on the application, additive manufacturing methods require machining as a subsequent process, and in order to enjoy the benefits of near-net shapes using additive manufacturing methods, machining must be performed without causing defects such as cracks or breaks in the additively manufactured body.

[0004] In addition, in additive manufacturing, materials with excellent properties such as high strength and high corrosion resistance are often used, but the machinability of additively manufactured objects made of these materials is poor, making it difficult to efficiently obtain the desired shape. Cutting is an example of mechanical processing, but if the additively manufactured object is made of a difficult-to-cut material, not only will the cutting tool have a short lifespan and the processing be inefficient, but continued unreasonable cutting conditions will cause abnormal wear of the tool during cutting, leading to increased cutting resistance and cutting temperature, which can cause defects in the additively manufactured object (surface scratches, cracks, and breaks).

[0005] Furthermore, as disclosed in Patent Document 2, for example, when the workpiece is a difficult-to-cut material, tool damage such as wear and chipping of the tool during cutting is severe, and therefore it is necessary to suppress this. Therefore, in order to reduce the processing load that causes tool damage, a cutting method has been proposed in which the workpiece is heated and processed in a softened state. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2016-502596 [Patent Document 2] WO2020 / 111231 publication Summary of the Invention [Problem to be solved by the invention]

[0007] However, although the cutting resistance is reduced by heating the workpiece, the temperature at the processing point remains high, and there is a need to improve the wear resistance of cutting tools. In particular, when cutting workpieces that contain hard ceramics such as cemented carbide and cermet-based materials, the blade design is important for improving the wear resistance of tools.

[0008] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a machining method and tool that can reduce cutting resistance and suppress tool wear when cutting difficult-to-cut materials and the like in a heated state. [Means for solving the problem]

[0009] The present invention relates to a method for machining a workpiece, the method comprising: a heating step of heating the workpiece; and a machining step of pressing a cutting tool against the workpiece heated in the heating step to machine the workpiece, the cutting tool being machined in a negative rake angle in the machining step. The heating temperature in the heating step is 300° C. or more and 800° C. or less, the rake angle is −30° or more and −5° or less, and the twist angle is 0° or more and 60° or less. This is a processing method characterized by the above.

[0010] In the machining step, it is preferable that the ratio (L / W) of the contact length L of the cutting edge of the cutting edge to the cutting width W of the workpiece is greater than 1 and is 2.0 or less. In addition, in the heating step, it is preferable that the workpiece is heated by high-frequency induction heating.

[0011] The work material preferably has a machinability index of 50 or less. It is also preferable that the heating temperature in the heating step is 300° C. or more and 600° C. or less, and the twist angle is 10° or more and 30° or less.

[0012] The work material is preferably a composite material of ceramics and metal.

[0013] Moreover, the cutting tool is preferably made of ceramics containing at least one of Ti, Si and Al.

[0014] It is also preferable that the heating temperature in the heating step is 50° C. to 800° C., and the cutting speed of the cutting tool is 10 to 60 m / min.

[0015] The present invention also provides This tool is used to cut a workpiece in a heated state with a negative rake angle, and is characterized in that it is made of ceramics containing at least one of Ti, Si, and Al, and has a twist angle of 0° or more and 60° or less.

[0016] In addition, the twist angle of the tool is more than 0° and less than 60°. It is also preferable that the twist angle is 10° or more and 30° or less.

[0017] Moreover, the tool is preferably made of ceramics containing at least one of Ti, Si and Al. The material is preferably an alumina-silicon carbide ceramic or a sialon ceramic.

[0018] The work material is preferably a composite material of ceramics and metal. Effect of the Invention

[0019] According to the present invention, it is possible to provide a machining method and a tool that can reduce cutting resistance and suppress tool wear resistance when cutting a difficult-to-cut material in a heated state. [Brief description of the drawings]

[0020] [Figure 1] FIG. 4 is a diagram showing the relationship between a workpiece and a rake angle. [Diagram 2] FIG. 4 is a diagram showing a method for setting a rake angle. [Diagram 3] FIG. 13 is a diagram showing the relationship between the twist angle, the contact length and the cutout width. [Figure 4] FIG. 1 is a diagram showing the relationship between rake angle and cutting resistance. [Diagram 5] FIG. 2 is a diagram showing the relationship between the rake angle and the amount of wear (flank wear, rake angle wear). [Figure 6] FIG. 1 is a diagram showing the relationship between flank wear and cutting resistance. [Figure 7] FIG. 13 is a diagram showing the relationship between the helix angle and cutting resistance. [Figure 8] FIG. 1 is a diagram showing the relationship between flank wear and cutting resistance. [Figure 9] FIG. 1 is a diagram showing the relationship between heating temperature and cutting resistance and flank wear. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] <Processing method> The processing method according to the present embodiment is a processing method for processing a workpiece, and includes a heating step for heating the workpiece, and a processing step for pressing a cutting tool against the workpiece heated in the heating step to process it, and is characterized in that the processing step is performed with a negative rake angle. With the processing method according to the present embodiment, wear of the tool can be suppressed when processing a heated workpiece.

[0022] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. First, the workpiece will be described, then an embodiment of the processing method will be described, and then the tool will be described. In this specification, the numerical range of "to" is a range that includes the numerical values ​​before and after it as "above" and "below".

[0023] [Work material] Examples of the workpiece include shaped bodies produced by casting, forging, padding, thermal spraying, and additive manufacturing.

[0024] The material constituting the workpiece is not limited as long as it can achieve its purpose, and for example, a metal material or a composite material of ceramics and metal can be used. Here, when heating by high-frequency induction heating, a material that can be heated by high-frequency induction heating is used. Therefore, the workpiece is basically preferably composed of a metal material, and among them, a material that is resistant in the range of heating temperatures and has small expansion and contraction due to heating is preferable. For example, a composite material of ceramics and metal such as cemented carbide and cermet, which have high hardness, is preferable. Specifically, Ni-based alloys, especially Ni-based superalloys, Co-based alloys, especially Co-based superalloys, Cr-based alloys, Mo-based alloys, and Fe-based superalloys are preferable.

[0025] The above-mentioned cemented carbide and cermet are composite materials consisting of a sintered body mainly composed of a hard phase containing at least one of carbides, nitrides, oxides, oxynitrides, carbonitrides, borides and silicides of Group 4 transition metals, Group 5 transition metals and Group 6 transition metals in the periodic table, and a binder phase containing at least one of Fe, Co, Ni, Cr and Mo.

[0026] The cemented carbide is typically a WC-Co alloy, but WC-TiC-Co alloys, WC-TaC-Co alloys, and WC-TiC-TaC-Co alloys are also used. The binder phase may contain other metal elements such as Cr and Cu. The cermet is typically a TiN-Ni alloy, TiN-TiC-Ni alloy, TiC-Ni-Mo2C alloy, etc.

[0027] Although cemented carbide is generally used as a cutting tool, in the case of an application requiring toughness such as a die described later, it is preferable to adopt a composition different from that used for cutting tools. The same applies to cermets.

[0028] That is, when an additively manufactured product made of cemented carbide is used as, for example, a mold, the amount of Co in the WC-Co alloy is preferably 20% by mass or more and 50% by mass or less. This amount of Co is higher than that of the WC-Co alloy used as a cutting tool. This provides the toughness, strength, and hardness suitable for use as a mold.

[0029] In addition to cemented carbide or cermet, high hardness materials and superalloys are also listed. High hardness materials refer to Fe-based materials with hardness exceeding 50HRC, such as JIS SKD11, SKH51, and SUS630. Superalloys are alloys mainly composed of elements other than Fe, such as Ni, Cr, Co, and Mo. Among them, Ni-based superalloys are alloys containing, for example, 50 mass% or more of Ni and also containing elements selected from chromium (Cr), cobalt (Co), molybdenum (Mo), tungsten (W), niobium (Nb), aluminum (Al), titanium (Ti), iron (Fe), zirconium (Zr), tantalum (Ta), vanadium (V), hafnium (Hf), manganese (Mn), silicon (Si), lanthanum (La), magnesium (Mg), carbon (C), boron (B), and the like.

[0030] In general, Ni-based superalloys are alloys whose main phase is the gamma phase. The gamma phase does not undergo phase transformation during the cooling process and maintains its crystal structure, so cracking is unlikely to occur. In addition, when a Ni-based superalloy is molded on steel or cemented carbide, an intermediate layer is formed near the interface. In this case, the gamma phase fraction of the intermediate layer is high, and a significant decrease in toughness can be suppressed. Furthermore, a Ti alloy (for example, Ti-6% by mass Al-4% by mass V) is an example of a difficult-to-cut material with a machinability index of 50 or less. The configuration according to this embodiment is particularly suitable for machining difficult-to-cut materials because it is excellent in reducing cutting resistance and improving wear resistance.

[0031] Here, the machinability index is calculated by cutting sulfur free-cutting steel (AISI-B1112), setting the cutting speed for a certain tool life at 100 and expressing the cutting speed for the same tool life of a comparative material as a percentage.

[0032] [Heating process] First, the heating step will be described. In a preferred embodiment of the present invention, the heating means for the workpiece and the reason for heating the workpiece will be described in that order.

[0033] The means for preheating the workpiece is not limited as long as it can achieve the purpose. For example, the workpiece can be heated by high-frequency induction heating, semiconductor laser, gas burner, infrared electric heater, heating furnace, electron beam or laser irradiation, halogen lamp irradiation, or a heating method using an electric heating wire as a heat source such as a hot plate. These means may be used alone or in combination.

[0034] As a preferred example of this embodiment, among the above heating means, energy input by high-frequency induction heating is effective in maintaining a stable heating temperature. This is because Joule heat is generated in the object due to eddy currents and the electrical resistance of the metal, causing the metal to self-heat, making it possible to sufficiently heat even members with a large heat capacity. In particular, by covering the parts other than the part to be heated with a heat insulating material, it is possible to stably maintain the heating temperature. Other heating methods, which are methods of heating the object from the outside, can input sufficient energy when heating members with a small heat capacity.

[0035] The heating temperature in the heating step is not limited as long as the object can be achieved. For example, when machining a workpiece made of a difficult-to-cut material, the temperature is preferably maintained in the range of 50°C to 800°C, more preferably in the range of 200°C to 800°C, and further preferably in the range of 250°C to 600°C, so as to ensure stable machining.

[0036] Specifically, when the workpiece is made of cemented carbide, the heating temperature is preferably maintained in the range of 200 to 600 ° C, and more preferably in the range of 300 to 400 ° C. If the heating temperature is 200 ° C or higher, the workpiece is likely to soften, and this, combined with the cutting heat during cutting, reduces the cutting resistance when chips are generated, further reducing the load on the tool and suppressing tool wear. For example, if the heating temperature exceeds 800 ° C, the workpiece becomes too soft, and burrs are generated during cutting, making it difficult to obtain a smooth machined surface or machined shape.

[0037] In a heated state, the hardness of the additively manufactured object decreases, even if the object is made of a material that is difficult to cut. Therefore, for example, when a cutting tool collides with the additively manufactured object, shear deformation is likely to occur, and the resistance when chips are generated is small. In addition, materials in which hard particles are dispersed are difficult to cut at room temperature, but chips are generated only when heated, and depending on the material composition, the hard particles can be the starting point for chip separation, making it easier to cut, leading to improved properties of the machined surface by preventing chips from adhering to the tool.

[0038] In an additive manufacturing process, which is one form of the manufacturing process of a workpiece, cutting is performed while maintaining the heated state, and this embodiment can be said to be a highly efficient process with less energy loss compared to removing the heated state and then reheating. The temperatures during additive manufacturing and machining can be controlled to their optimum states. Machining can cause residual stress, but it is possible to control the process by relaxing this, or conversely, by applying residual stress to harden the surface or improve chipping resistance.

[0039] [Processing process] Next, the machining process will be described. The machining process is a process in which a cutting tool (tool) is pressed against a heated workpiece to machine it. Machining methods include, for example, turning, in which the workpiece is rotated and machined with the tool fixed, and milling, in which the workpiece is fixed and a cutting tool is rotated. In both cases, the relative motion between the tool and the workpiece is used to generate chips. By optimizing the tool shape, chip generation can be made easier and the load on the tool can be reduced. In other words, tool wear is suppressed.

[0040] [Rake angle] The rake angle will be explained. As shown in FIG. 1, the rake angle 150 is the angle between the perpendicular line and the rake face 140 of the shape of the tool 120 when the surface of the workpiece 110 is used as a reference. The rake angle 150 can be a positive or negative angle. The position of the perpendicular line is set to 0, and a positive angle is set in the opposite direction to the traveling direction of the tool. If the rake angle 150 is large, the cutting resistance is reduced by increasing the sharpness, but the thickness of the tool cutting edge is reduced and the cutting edge strength is reduced, increasing the risk of chipping. If the rake angle 150 is small and a negative angle, the cutting resistance increases, but the thickness of the tool cutting edge increases, increasing the cutting edge strength and improving the chipping resistance of the tool.

[0041] From the above, by making the rake angle a negative value, the rigidity of the blade is increased, and tool wear can be easily suppressed. Here, the lower limit of the rake angle is preferably -60°, more preferably -45°, and even more preferably -30°. It is also preferably less than -0°, more preferably -1° or less, and even more preferably -5° or less.

[0042] As described above, the rake angle represents the inclination of the rake face relative to the machining surface. As a method for setting (controlling) the rake angle, for example, as shown in Fig. 2, a compound lathe is used as a test machine, the X and Y axes are controlled by NC (Numerical Control) operation, and two-dimensional cutting is performed from the machining start point 240 (pre-machining position) of the tool (bite) 230 toward the center of the workpiece 210. A negative rake angle 250 or a positive rake angle 260 can be set by controlling the Y axis without changing the shapes of the tool (bite) 230 or the insert (cutting tool) 220. The arrow in Fig. 2 indicates the direction of travel of the tool.

[0043] [The ratio (L / W) of the helix angle, the contact length of the cutting edge (L) and the cutting width (W) of the workpiece] Next, the ratio (L / W) of the contact length (L) of the cutting edge of the cutting edge to the cutting width (W) of the workpiece will be explained using Fig. 3. The contact length (L) of the cutting edge of the cutting edge (tool cutting edge) 320 is the length of the cutting edge in contact with the workpiece when chips are generated, and the cutting width (W) of the workpiece 310 is the length machined in the direction perpendicular to the traveling direction of the tool cutting edge 320.

[0044] When the ratio (L / W) of the cutting width (W) to the contact length (L) of the cutting edge is increased, the load per unit area of ​​the cutting edge when chips are generated can be reduced. Therefore, it may be effective in suppressing tool breakage. On the other hand, if this ratio is too large, the load from the direction perpendicular to the tool travel direction increases, causing chatter vibration of the tool, making the tool more likely to break. Therefore, it is preferable to perform processing when the ratio (L / W) of the contact length (L) of the cutting edge of the cutting edge to the cutting width (W) of the workpiece is more than 1 and is 2.0 or less.

[0045] A method for setting (controlling) the ratio (L / W) between the contact length (L) of the cutting edge of the cutting edge and the cutting width (W) of the workpiece will also be described. As shown in FIG. 3, when a tool having a rotating part that can rotate the insert 320 by 0 to 45° with respect to the XZ plane of the machine coordinate system is used, for example, as shown in FIG. 3(a), if the rotation angle β of the insert 320 is set to 0°, the ratio (L / W) between the contact length (L) of the cutting edge of the cutting edge and the cutting width (W) of the workpiece will be 1. Also, for example, as shown in FIG. 3(b), (c), and (d), if the rotation angle β is changed to 10°, 30°, and 45°, the ratio (L / W) between the contact length L and the cutting width W can be adjusted to be greater than 1 and less than 1.41. Also, although not shown, if the rotation angle β is changed to 60°, the ratio (L / W) between the contact length L and the cutting width W can be adjusted to 2.0. In addition, when the tool is a rotating tool, the ratio (L / W) of the contact length (L) of the cutting edge of the cutting edge to the cutting width (W) of the workpiece corresponds to the twist angle.

[0046] The tool shape and machining conditions can be determined by performing cutting tests and evaluating tool wear, cutting resistance, and the like. In this embodiment, these evaluations were performed using two-dimensional cutting. Two-dimensional cutting is a method in which the cutting edge of the tool is perpendicular to the direction of cutting motion (cutting direction). In this case, the cutting resistance has two components: a principal force (component parallel to the cutting direction) and a thrust force (component perpendicular to the cutting direction). When the ratio (L / W) of the contact length (L) of the cutting edge of the cutting edge to the cutting width (W) of the workpiece exceeds 1, the cutting resistance has three components, including the feed force (component perpendicular to the end face of the workpiece). The cutting resistance can be evaluated by the resultant force of these two or three components.

[0047] [Cutting conditions] Since cutting conditions, such as cutting speed, affect the cutting mechanism, it is preferable to optimize them in order to stabilize tool life and achieve high-efficiency machining. For example, when machining difficult-to-machine materials, the cutting speed is preferably 10 to 60 m / min, and more preferably 20 to 50 m / min.

[0048] It is even more preferable to combine the heating temperature of the workpiece with the cutting speed, for example, by setting the heating temperature of the workpiece to 350°C or higher and the cutting speed to 60 m / min or lower, or by setting the heating temperature of the workpiece to 250°C or higher and the cutting speed to 50 m / min or lower.

[0049] <Tools> Next, an embodiment of a tool according to the present invention will be described. The embodiment of the tool is a tool for cutting a workpiece in a heated state, and one of the features of the tool is that the rake angle is negative.

[0050] The rake angle, twist angle, and ratio of the contact length (L) of the cutting edge of the cutting edge to the cutting width (W) of the workpiece are as described above. Here, when the tool is a rotary tool, the ratio (L / W) of the contact length L of the cutting edge of the cutting edge to the cutting width W of the workpiece corresponds to the twist angle, and as shown in Fig. 3(a), when the twist angle β is 0°, the contact length of the cutting edge of the cutting edge of the cutting edge and the cutting width W of the workpiece are the same value, that is, the ratio (L / W) of the contact length L to the cutting width W is 1. For example, as shown in Fig. 3(b), (c), and (d), by changing the twist angle β to 10°, 30°, and 45°, the ratio (L / W) of the contact length L to the cutting width W can be made to be greater than 1 and less than 1.5. Although not shown, if the twist angle β is changed to 60°, the ratio (L / W) of the contact length L to the cutting width W can be made to be 2.0.

[0051] [Tool material] Cutting is performed by taking advantage of the difference in hardness between the tool material and the workpiece. When the workpiece is heated, it becomes softer and easier to machine, but the cutting tool that comes into contact with it also heats up, so the tool material must be hard at high temperatures. Therefore, when machining a heated workpiece, it is preferable to use ceramics as the tool material.

[0052] In particular, when the workpiece is a difficult-to-cut material such as cemented carbide or cermet (a composite material of ceramics and metal), cutting the workpiece in a heated state enables highly efficient machining. Note that ceramic cutting tools are less likely to adhere to metal materials when in contact with them, and can stably discharge chips from cemented carbide and cermet, making them preferable for cutting heated workpieces.

[0053] Ceramic materials applicable to cutting tools include titanium carbide ceramics, alumina ceramics, alumina-silicon carbide ceramics, silicon nitride ceramics, zirconia ceramics, and sialon ceramics. Ceramics containing at least one of Ti, Si, and Al are preferred. Alumina-silicon carbide ceramics and sialon ceramics are particularly preferred as tool materials with excellent impact resistance and wear resistance at high temperatures. The heat resistance of alumina-silicon carbide ceramics and sialon ceramics can be further improved by adding yttrium, ytterbium, zirconium, etc. EXAMPLES

[0054] An embodiment will be described.

[0055] [Experimental equipment and measuring instruments] To evaluate the machinability, an NC lathe (Okuma, LB4000EXII) was used. The test was carried out in a dry environment.

[0056] A cutting dynamometer (KISTLER, 9129AA) was used to measure the cutting resistance. The cutting dynamometer was attached to the turret of the NC lathe, and the cutting tool was attached to the cutting dynamometer using a jig (KISTLER, 9129AE25). A measuring microscope (Olympus, STM7) was used to measure the amount of tool wear.

[0057] [Work material] The following workpiece was prepared and machined to a diameter of φ100 mm and a thickness of 2 mm. In addition, a mounting hole for a jig was machined and the workpiece was attached to an NC lathe via the jig. Material: cemented carbide (WC-Co alloy), WC grain size: 2.0 μm, WC content: 60 mass%, Co content: 40 mass%, hardness: 78.9 HRA, manufacturing method: sintering.

[0058] [insert] The tool shape was TCGN160308FN, and the tool material was Sialon. The tool was attached to an NC lathe using a bit.

[0059] The cutting resistance, tool wear, and chatter vibration occurrence were evaluated when machining the workpiece under the following cutting conditions. The results are shown in Table 1. (1) Cutting conditions The cutting width was 2 mm, the cutting distance was approximately 1500 mm, and the feed rate was 0.05 mm / REV. Other cutting speeds, workpiece temperatures, helix angles, and rake angles are shown in Table 1. [Table 1]

[0060] As shown in Table 1 and Figure 4, it was confirmed that there is a tendency for cutting resistance to increase with increasing rake angle when cutting a workpiece in a heated state. The principal force (component parallel to the cutting direction) shows a larger value as the rake angle increases, and there is a positive correlation, whereas the thrust force (component perpendicular to the cutting direction) is hardly affected by changes in the rake angle and shows a constant value.

[0061] As shown in Table 1 and Figure 5, the amount of wear on the flank was positively correlated with the rake angle, while the wear on the rake face was constant. It is believed that the negative rake angle increased the rigidity of the cutting edge, suppressing wear and allowing cutting to continue. On the other hand, when the rake angle was positive, it is believed that wear progressed due to the reduced rigidity of the cutting edge.

[0062] As shown in Table 1 and Fig. 6, a rake angle of -10° to -5° was a condition that could suppress flank wear and cutting resistance. It was confirmed that in hot cutting, it is effective to set a negative rake angle to increase the rigidity of the cutting edge.

[0063] It was confirmed that the effect of the helix angle on cutting resistance and flank wear was small, as shown in Table 1 and Figures 7 and 8. In this example, cutting resistance and tool wear were most suppressed when the helix angle was 30°.

[0064] As shown in Table 1 and Fig. 9, there was a negative correlation between heating temperature and cutting resistance. On the other hand, there was a positive correlation between heating temperature and flank wear. When cutting the workpiece at a high temperature, cutting resistance is reduced, but it is thought that the excessive heat effect accelerates tool wear. In addition, when the heating temperature was 200°C or less, chatter vibration of the cutting tool occurred. Although suppressing chatter vibration is not essential, the occurrence of chatter vibration is thought to make cutting conditions unstable.

[0065] In this example, when the heating temperature was 300°C, the cutting resistance was reduced by about 35% compared to room temperature (21°C). Also, when the heating temperature was 400°C, the amount of wear was reduced by about 20% compared to other conditions. In other words, it was found that a heating temperature in the range of 300 to 400°C is particularly suitable. [Explanation of symbols]

[0066] 10: Work material 20: Tools 30: Machining surface 40:Scooping surface 50: Rake angle 60: Clearance angle 210: Work material 220: Insert (tool) 230: Tools (bites) 240: Machining start point 250: Negative rake angle 260: Positive rake angle 310: Work material 320: Insert

Claims

1. A method for machining a workpiece, comprising the steps of: a heating step of heating the workpiece; A processing step of pressing a cutting tool against the workpiece heated in the heating step, In the machining step, machining is performed with a negative rake angle, The heating temperature in the heating step is 300° C. or more and 800° C. or less, The rake angle is -30° or more and -5° or less, The twist angle is 0° or more and 60° or less, In the heating step, the workpiece is heated using high-frequency induction heating. A processing method characterized by the above.

2. The heating temperature of the heating step is 300°C or higher and 600°C or lower, The twist angle is 10° or more and 30° or less. The processing method according to claim 1 .

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