JP2017226040A - Processing method and tool, and method of manufacturing power transmission component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a processing technique capable of reducing crater wear of a tool in cutting work.SOLUTION: A processing method of cutting a cut material with a tool having a first processing part having a first radius of curvature, a second processing part having a second radius of curvature larger than the first radius of curvature, and an inflection point as a boundary position between the first processing part and second processing part comprises, in a cutting process of cutting the cut material by a predetermined cutting quantity through feeding in a cutting direction, cutting the cut material under a processing condition so set that the position of the inflection point is equal to or larger than 50%×cutting quantity from the first surface, the cutting quantity being between a first surface including a bottom part of a surface of the cut material having been cut with the first processing part and second processing part and a second surface which is a surface of the cut material to be cut.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a machining method, a tool, and a power transmission component manufacturing method.

  Japanese Patent Application Laid-Open No. H10-228688 discloses a tool with an exchangeable cutting edge used for cutting. In the tool disclosed in Patent Document 1, the corner portion has a penetration portion for penetrating the work material, and a finishing portion for improving the surface roughness of the work material following the penetration portion. It has become.

International Publication No. WO95 / 00272 Pamphlet

  However, in cutting of a work material (for example, hardened steel) using a conventional tool, the cut thickness of the work material is increased, and the amount of heat generated during plastic deformation is increased. For this reason, the temperature of a tool becomes high in cutting, and wear of a tool (for example, crater wear in the rake face of a tool) may arise. Crater wear can be caused mainly by the temperature of the tool, and the temperature rise of the tool can be mainly caused by heat generation during plastic deformation of the work material.

  By reducing the peripheral speed of the work material and the feed amount of the tool in cutting, heat generation during plastic deformation of the work material can be suppressed, and the temperature of the tool can be lowered, but the cycle time becomes slow. Production capacity can be reduced.

  This invention is made | formed in view of said subject, and it aims at provision of the processing technique which can reduce the crater wear of a tool in cutting.

The processing method according to the first aspect of the present invention includes a first processing portion having a first curvature radius, a second processing portion having a second curvature radius larger than the first curvature radius, and the first processing portion. An inflection point that is a boundary position between the processing portion and the second processing portion, and a processing method of cutting a work material with a tool,
A step of cutting a predetermined cutting amount from the work material by feeding in a cutting direction from the outer periphery of the work material toward the rotation axis of the work material;
In the step, between the first surface including the bottom of the surface of the work material after cutting by the first work part and the second work part, and the second surface which is the surface of the work material before cutting In the cutting amount, the work material is cut under the processing conditions set so that the position of the inflection point is 50% × the cutting amount or more from the first surface.

  Further, according to the processing method of the second aspect of the present invention, the first processing portion and the second processing portion respectively cut different positions on the surface of the work material, and the work after the cutting On the surface of the material, a processed surface cut by the first processed portion having the first radius of curvature and a processed surface cut by the second processed portion having the second radius of curvature are described above. It is formed at different positions on the surface of the work material.

Moreover, the tool of the 3rd side surface of this invention is a tool for cutting a workpiece, Comprising: The 1st process part which has a 1st curvature radius,
A second processed portion having a second radius of curvature greater than the first radius of curvature;
An inflection point that is a boundary position between the first processed part and the second processed part,
The first processing unit and the second processing unit are:
It is configured to cut a predetermined cutting amount from the work material by feeding in a cutting direction from the outer periphery of the work material toward the rotation axis of the work material,
In the depth of cut between the first surface including the bottom of the surface of the work material after cutting and the second surface, which is the surface of the work material before cutting, the position of the inflection point is the first surface. From the above, the work material is cut according to the machining conditions set to be equal to or more than 50% × the depth of cut.

The power transmission component manufacturing method according to the fourth aspect of the present invention includes a first machining portion having a first curvature radius, and a second machining having a second curvature radius larger than the first curvature radius. And a power transmission component manufacturing method of cutting a power transmission component with a tool having an inflection point that is a boundary position between the first processing portion and the second processing portion, the manufacturing method Is
A step of cutting a predetermined cutting amount from the work material by feeding in a cutting direction from the outer periphery of the work material to form the power transmission component toward the rotation axis of the work material, ,
In the depth of cut between the first surface including the bottom of the surface of the work material after cutting by the first work part and the second work part, and the second surface which is the surface of the work material before cutting The work material is cut under a machining condition set so that the position of the inflection point is 50% × the depth of cut from the first surface.

  According to the first to fourth aspects of the present invention, the tool temperature can be reduced, and the crater wear of the tool can be suppressed by reducing the tool temperature.

  According to the first to fourth aspects of the present invention, it is possible to extend the tool life and reduce the machining cost while suppressing crater wear of the tool.

The figure which shows the outline | summary of the cutting by the tool which concerns on embodiment, and the function structure of a processing apparatus. The figure which shows the state by which the tool which concerns on embodiment was hold | maintained at the tool holding part. The figure which illustrates the structure of the tool which concerns on embodiment. The figure which shows the process example which changed the position of the inflection point with respect to the cutting depth. The figure which shows the change of the tool temperature when processing by changing the position of an inflection point with respect to the cutting depth. The figure which shows typically the surface shape of a workpiece when machining a workpiece with the tool which concerns on embodiment. The figure explaining the flow of the processing method of this embodiment. The figure which shows the comparative example of a tool life and processing cost.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. However, the components described in this embodiment are merely examples, and the technical scope of the present invention is determined by the scope of the claims, and is not limited by the following individual embodiments. Absent.

(Outline of cutting and functional configuration of processing equipment)
FIG. 1 is a diagram exemplarily showing an outline of cutting by a cutting edge-exchangeable tool of the present embodiment and a functional configuration of a processing apparatus. The tool of the present embodiment is a compound curvature-shaped tool having a plurality of machining portions with different curvature radii as a configuration for cutting the workpiece 10 (hereinafter referred to as “wiper insert tool”). The work material 10 is held by a fixed portion of the machining apparatus so as to be rotatable around the rotary shaft 15 in the direction of the arrow 17 at a predetermined peripheral speed.

  FIG. 2 is a view exemplarily showing a state in which a compound curvature-shaped tool (wiper insert tool) 20 is held by a tool holding portion 25, and the wiper insert tool 20 is inserted into the tool via a fixing mechanism 30 and a metal deposit 35. It is held by the holding unit 25. The wiper insert tool 20 is configured to be detachable from the tool holding portion 25 by the fixing mechanism 30. The wiper insert tool 20 includes a first processed portion 21 (nose portion) and a second processed portion 22 (wiper portion) as a configuration for processing the workpiece 10. The curvature radius of the 1st process part 21 (nose part) and the curvature radius of the 2nd process part 22 (wiper part) are each comprised differently.

  In FIG. 1, the feed direction 40 is a direction in which the wiper insert tool 20 advances in the horizontal direction with respect to the rotation shaft 15 every time the work material 10 rotates. The cutting direction 45 is a direction in which the wiper insert tool 20 is directed from the outer periphery of the work material 10 toward the center direction of the work material 10 (the direction of the rotation axis 15 of the work material 10). Further, the tool holding unit 25 is configured to be able to advance toward the rotating shaft 15 of the work material 10 so that the wiper insert tool 20 cuts the surface of the work material 10 over a certain depth. The cut amount 50 is an amount cut by the wiper insert tool 20. The tool holding unit 25 is configured to be movable a certain distance for each rotation of the work material 10 so that a material corresponding to the cutting amount 50 is cut off along the surface of the work material 10.

  The processing apparatus according to the present embodiment includes, as functional configurations, an apparatus control unit 100 that controls the entire processing apparatus, a spindle control unit 200 that controls the rotational drive of the work material 10, a tool feed, a cutting amount, and the like. A tool control unit 300 for controlling Connected to the apparatus control unit 100 are an input unit 110 that functions as a user interface, and a storage unit 120 that stores machining conditions and tool shape information input via the input unit 110. For example, when a machining condition is input from the input unit 110, the apparatus control unit 100 controls the spindle control unit 200 and the tool control unit 300 based on the input machining condition to control the machining of the workpiece 10. I do. Here, the machining conditions include, for example, the feed and cutting amount of a composite curvature shaped tool (wiper insert tool 20), the feed amount per revolution of the work material, and the composite curvature shaped tool (wiper insert tool 20). A condition relating to the position of the inflection point 60 (FIG. 3) is included.

(Configuration of wiper insert tool)
FIG. 3 is a diagram illustrating the configuration of the wiper insert tool 20. FIG. 3A shows the overall configuration of the wiper insert tool 20 when the wiper insert tool 20 held by the tool holding unit 25 shown in FIG. 2 is viewed from above. FIG. 3B is a diagram showing details of the processing portion 26 of FIG. 3A, and the configuration of the first processing portion 21 (nose portion) and the second processing portion 22 (wiper portion) of the wiper insert tool 20. Is shown enlarged.

  The wiper insert tool 20 of the present embodiment is a compound curvature shaped tool having a plurality of curvature radius machining portions, and the first machining portion 21 (nose portion) has a first curvature radius R1. The second processed portion 22 (wiper portion) has a radius of curvature R2 that is larger than the first radius of curvature R1. In FIG. 3, the inflection point 60 is the boundary position (boundary) between the first processing unit 21 and the second processing unit 22. The wiper insert tool 20 can be formed of, for example, cubic boron nitride (CBN). In addition, the material which comprises the wiper insert tool 20 is an illustration, and it is possible to comprise the wiper insert tool 20 using the material which can be used as a tool of cutting.

(Example of processing with the inflection point changed)
FIG. 4 is a diagram illustrating a processing example in which the position of the inflection point 60 is changed with respect to the cutting amount. For comparison, FIG. 4A shows an example of machining with a tool having a machining portion having a single curvature shape (shown as “single curvature insert” in FIG. 4A). A hatched area 411 indicates an area that is cut by a processing portion of a single curvature insert. In the hatched region 411, the arrow indicates the cut thickness cut by cutting.

  4 (b) to 4 (d) show an example of machining with the compound curvature shaped tool (wiper insert tool 20) of the present embodiment, and the hatched areas 412 to 414 are machining of the wiper insert tool 20. FIG. The area cut by the part is shown. In hatched regions 412 to 414, arrows indicate the cut thicknesses cut by cutting.

  4 (b) to 4 (d), the surface including the bottom (lowermost part) of the surface of the work material 10 after being cut by the wiper insert tool 20 is defined as a first surface (reference surface), and the surface before cutting is cut. Let the surface of the cutting material 10 be a 2nd surface. The thickness (distance) between the first surface and the second surface is defined as a cutting amount T. FIG. 4B shows a wiper so that the inflection point 60 is 10% × the cut amount T from the first surface (reference surface) at the cut amount T between the first surface and the second surface. The example of a process which set the process conditions of the cutting direction 45 of the insert tool 20 is shown. A region from the first surface (cutting amount T (0%)) to 10% × cutting amount T of the work material 10 after cutting is processed by the second processing portion 22 (wiper portion) of the wiper insert tool 20, A region from 10% × the depth of cut T to the second surface of the workpiece 10 before cutting (the depth of cut T (100%)) is machined by the first machining portion 21 (nose portion) of the wiper insert tool 20. .

  FIG. 4C shows a wiper so that the inflection point 60 is 50% × the cut amount T from the first surface (reference surface) at the cut amount T between the first surface and the second surface. The example of a process which set the process conditions of the cutting direction 45 of the insert tool 20 is shown. A region from the first surface (cutting amount T (0%)) to 50% × cutting amount T of the cut work material 10 after cutting is processed by the second processing portion 22 (wiper portion) of the wiper insert tool 20, The region from 50% × the depth of cut T to the second surface of the workpiece 10 before cutting (the depth of cut T (100%)) is machined by the first machining portion 21 (nose portion) of the wiper insert tool 20. .

  FIG. 4D shows that the position of the inflection point 60 is 100% × the cut amount T from the first surface (reference surface) in the cut amount T between the first surface and the second surface. The example of a process which set the process conditions of the cutting direction 45 of the wiper insert tool 20 is shown. In the case of FIG. 4D, since the position of the inflection point 60 is the position of the surface (second surface) of the work material 10 before cutting, the work material 10 is the second processed portion of the wiper insert. It is processed only by 22 (wiper part).

  FIG. 5 is a diagram showing a change in temperature (tool temperature) of the wiper insert tool 20 when machining is performed by changing the position of the inflection point 60 with respect to the cutting depth. Specifically, an inflection point is obtained at a cutting depth T between the first surface (reference surface) of the work material 10 after cutting by the wiper insert tool 20 and the second surface of the work material 10 before cutting. Temperature of the wiper insert tool 20 when the position of 60 is changed in the range from the first surface (reference surface: cutting depth T (0%)) to the second surface (cutting depth T (100%)) (tool temperature) Shows changes. In FIG. 5, the horizontal axis indicates the position (ratio (%)) of the inflection point 60 in the cutting depth T, and the vertical axis indicates the temperature (tool temperature) of the wiper insert tool 20. In the present embodiment, the temperature (tool temperature) of the wiper insert tool 20 is calculated using cutting simulation software.

  As shown in FIG. 4B to FIG. 4D, the cutting thickness decreases as the ratio of the inflection point 60 increases. If the cut thickness is reduced, heat generation during plastic deformation in cutting is suppressed, and the tool temperature is lowered. As shown in FIG. 5, when the inflection point 60 position ratio is 0% to 50%, the tool temperature tends to decrease as the inflection point 60 position ratio increases. And in the area | region where the ratio of the position of the inflection point 60 is 50% or more with respect to the cutting depth T, the tool temperature hardly changes around the temperature T3 (° C.). Between the 1st surface which contains the bottom part (lowermost part) of the surface of the work material after the cutting by the 1st processing part 21 and the 2nd processing part 22, and the 2nd surface which is the surface of the work material before cutting In cutting depth (T), the cutting temperature is set so that the position of the inflection point 60 is not less than 50% from the first surface × cutting depth. Can be achieved. By reducing the tool temperature, it is possible to suppress the occurrence of crater wear.

  FIG. 6 is a diagram schematically illustrating the surface shape of the work material 10 when the work material 10 is processed with the composite curvature tool (wiper insert tool 20) of the present embodiment. The wiper insert tool 20 is set with a cutting condition in a cutting direction 45 from the outer periphery of the work material 10 to the center direction of the work material 10 (the direction of the rotation axis 15 of the work material 10). Is rotating at a predetermined peripheral speed. For this reason, the surface of the work material 10 is cut on the order of microns, and the surface of the member is cut while forming a wavy surface shape as shown in FIG. In FIG. 6, a position indicated by a black circle is a position corresponding to the inflection point 60, and an area indicated by reference number 121 indicates an area processed by the first processing portion 21 (nose portion), and is indicated by reference number 122. The area | region has shown the area | region processed with the 2nd process part 22 (wiper part) of the wiper insert. The 1st process part 21 (nose part) and the 2nd process part 22 (wiper part) cut each different position of the surface of a work material. On the surface of the work material after cutting, a processed surface cut by a first processed portion 21 (nose portion) having a first radius of curvature, and a second processed portion 22 (wiper) having a second radius of curvature. Are formed at different positions on the surface of the work material.

  In FIG. 6, it is shown that the cutting amount shown in FIG. 4 is equal to the cutting thickness. Reference number 63 indicates the first surface (reference surface) of the work material 10 after cutting by the wiper insert tool 20, and reference number 64 indicates the surface (second surface) of the work material 10 before cutting. Show. The thickness (distance) between the first surface and the second surface is the depth of cut T. By processing so that the position of the inflection point 60 is 50% × the cutting depth T from the first surface (reference surface), the tool temperature can be reduced as shown in FIG. .

(Processing flow of processing method)
FIG. 7 is a diagram for explaining the flow of the processing method of the present embodiment. In step S1, processing conditions are set. In this step, for example, the cutting speed, the feed rate and cutting amount of the compound curvature shaped tool (wiper insert tool 20), the shape of the wiper insert tool 20, the position of the inflection point 60, and the wiper insert tool 20 are applied to the work material. Processing conditions related to the angle and the like are set. For example, when machining conditions are input from the input unit 110 illustrated in FIG. 1, the apparatus control unit 100 controls the spindle control unit 200 and the tool control unit 300 based on the input machining conditions to cut the workpiece. Processing control of the material 10 is performed.

  In step S <b> 2, the apparatus control unit 100 controls the rotation of the fixing unit that fixes the workpiece 10 via the spindle control unit 200 based on the set machining conditions (for example, the cutting speed).

  Next, in step S3, the apparatus control unit 100 sets the machining conditions (for example, feed (feed speed) and cutting amount of the compound curvature-shaped tool (wiper insert tool 20)), the cutting amount, and the shape and change of the wiper insert tool 20. A tool holding unit to which a tool having a combined curvature shape (wiper insert tool 20) is fixed via the tool control unit 300 based on the position of the bending point 60, the angle at which the wiper insert tool 20 is applied to the work material, and the like. 25 movements in the feeding direction 40 and movements in the cutting direction 45 are controlled. For example, when the position of the inflection point 60 is set (for example, set to 50% or more), the tool control unit 300 is stored in the storage unit 120 under the control of the apparatus control unit 100. Information of the cutting amount T of the work material 10 is calculated based on the tool shape of the tool (wiper insert tool 20), and based on the calculated information of the cutting amount T, the center direction of the work material 10 (cutting work) The movement of the tool holding portion 25 in the cutting direction 45 toward the rotation axis 15 of the material 10 is controlled. Based on the set machining conditions, the first machining unit 21 and the second machining unit 22 cause the surface of the workpiece after cutting by feeding in the cutting direction from the outer periphery of the workpiece to the rotation axis of the workpiece. In the depth of cut between the first surface including the bottom of the first surface and the second surface, which is the surface of the work material before cutting, the position of the inflection point 60 is 50% × the depth of cut from the first surface. Next, the work material is cut. In addition, the tool control unit 300 performs movement control of the tool holding unit 25 in the cutting direction 45 and also performs movement control of the tool holding unit 25 in the feed direction 40 of FIG. Steps S2 and S3 are not limited to the order of steps shown in the flowchart of FIG. 7, and the order of steps S3 and S2 may be reversed.

  According to the present embodiment, the workpiece 10 is processed so that the position of the inflection point 60 is 50% × the depth of cut from the first surface (reference surface), thereby performing plastic deformation in the cutting process. Is suppressed, and the tool temperature can be reduced. Further, by increasing the feed amount (movement amount in the feed direction 40 in FIG. 1) of the compound curvature shaped tool (wiper insert tool 20), the cutting length can be reduced (shortened) and the peripheral speed can be reduced. Become. By reducing the tool temperature, reducing (shortening) the cutting length, and reducing the peripheral speed, it is possible to extend the tool life while suppressing the occurrence of crater wear.

(Comparison of tool life and machining cost)
FIG. 8 is a diagram showing a comparative example of tool life and machining cost. FIG. 8A compares the tool life of a conventional tool having a single curvature-shaped machining portion (single curvature insert) and a composite curvature-shaped tool of this embodiment (wiper insert tool 20). It is a figure which shows an example. As shown in FIG. 8A, the life (N5) of the compound-curved shape tool (wiper insert tool 20) of the present embodiment is compared to the life (N1) of the conventional tool (single curvature insert). About 5 times.

  FIG. 8B shows the machining cost required when machining the workpiece 10 with a conventional tool having a single curvature-shaped machining portion (single curvature insert), and the compound curvature-shaped tool of this embodiment. It is a figure which shows the example which compared the processing cost required when the workpiece 10 is processed with the (wiper insert tool 20). As shown in FIG. 8 (b), the machining cost (C1) of the compound curvature-shaped tool (wiper insert tool 20) of this embodiment is compared to the machining cost (C5) of the conventional tool (single curvature insert). Is about 1/5.

(Manufacturing method of power transmission parts)
The processing method and tool described above can be applied to a method for manufacturing a power transmission component constituting a power train. For example, it can be applied as a process of hard turning processing of a pulley used for CVT. The power transmission component manufacturing method includes a step of cutting a predetermined cut amount from the work material by feeding in a cutting direction from the outer periphery of the work material to form the power transmission component toward the rotation axis of the work material. . Here, in the step of cutting a predetermined depth of cut from the work material, the first surface including the bottom of the surface of the work material after cutting by the first working portion 21 and the second work portion 22 and the work before cutting. The work material is cut according to the machining conditions set so that the inflection point 60 is 50% from the first surface and the depth of cut is greater than or equal to the second surface, which is the surface of the work material. To do.

(Summary of embodiment)
Configuration 1. The processing method of this embodiment has the following processes. That is, the machining method includes a first machining part (21) having a first radius of curvature, a second machining part (22) having a second radius of curvature larger than the first curvature radius, and the first A machining method for cutting a work material with a tool (20) having an inflection point (60) that is a boundary position between a machining part (21) and the second machining part (22),
A step (300, S3) of cutting a predetermined cutting amount from the work material by feeding in a cutting direction from the outer periphery of the work material toward the rotation axis of the work material;
In the process,
A first surface including a bottom of the surface of the work material after cutting by the first work part (21) and the second work part (22), and a second surface which is the surface of the work material before cutting In the cutting depth (T), the work material is cut according to the machining conditions set so that the position of the inflection point (60) is 50% × the cutting depth (T) or more from the first surface. It is characterized by processing.

  Configuration 2. It is a processing method of the structure 1, Comprising: The said 1st process part (21) and the said 2nd process part (22) cut each different position of the surface of the said work material, and the workpiece after the said cutting On the surface of the cutting material, a processed surface (121 in FIG. 6) cut by the first processed portion (21) having the first radius of curvature (R1) and the second radius of curvature (R2) are provided. The machined surface (122 in FIG. 6) machined by the second machined part (22) is formed at different positions on the surface of the work material.

Configuration 3. The tool of the present embodiment has the following configuration. That is, the tool is a tool (20) for cutting a work material,
A first working part (21) having a first radius of curvature;
A second processed portion (22) having a second radius of curvature greater than the first radius of curvature;
An inflection point (60) which is a boundary position between the first processed part (21) and the second processed part (22),
The first processed part (21) and the second processed part (22) are:
It is configured to cut a predetermined cutting amount from the work material by feeding in a cutting direction from the outer periphery of the work material toward the rotation axis of the work material,
In the incision amount (T) between the first surface including the bottom of the surface of the work material after cutting and the second surface that is the surface of the work material before cutting, the inflection point (60) The work material is machined by machining conditions set so that the position is 50% × cutting depth (T) or more from the first surface.

Configuration 4. The manufacturing method of the power transmission component of this embodiment has the following processes. That is, the power transmission component manufacturing method includes a first processed part (21) having a first radius of curvature, and a second processed part (22) having a second radius of curvature larger than the first radius of curvature. A power transmission component that cuts a power transmission component with a tool (20) having an inflection point (60) that is a boundary position between the first processing portion (21) and the second processing portion (22). The manufacturing method is as follows:
A step (300, S3) of cutting a predetermined cutting amount from the work material by feeding in a cutting direction from the outer periphery of the work material to form the power transmission component toward the rotation axis of the work material; In the above process,
A first surface including a bottom of the surface of the work material after cutting by the first work part (21) and the second work part (22), and a second surface which is the surface of the work material before cutting In the cutting depth (T), the work material is cut according to the machining conditions set so that the position of the inflection point (60) is 50% × the cutting depth (T) or more from the first surface. It is characterized by processing.

  According to the first configuration to the fourth configuration, it is possible to reduce the tool temperature, and it is possible to suppress tool wear (for example, occurrence of crater wear) by reducing the tool temperature. Become.

  Further, according to the first to fourth configurations, it is possible to extend the tool life and reduce the machining cost while suppressing the wear of the tool (for example, the occurrence of crater wear).

  20: Wiper insert tool, 21: 1st process part 21 (nose part), 22: 2nd process part 22 (wiper part), 60: Inflection point

Claims (4)

A boundary position between the first machining portion having the first curvature radius, the second machining portion having a second curvature radius larger than the first curvature radius, and the first machining portion and the second machining portion. An inflection point, and a machining method for cutting a work material with a tool having:
A step of cutting a predetermined cutting amount from the work material by feeding in a cutting direction from the outer periphery of the work material toward the rotation axis of the work material;
In the step, between the first surface including the bottom of the surface of the work material after cutting by the first work part and the second work part, and the second surface which is the surface of the work material before cutting The cutting method is characterized in that the work material is cut under the processing conditions set so that the position of the inflection point is 50% x the cut amount or more from the first surface at the cut amount.   The first processing portion and the second processing portion respectively cut different positions on the surface of the work material, and a first surface having the first curvature radius on the surface of the work material after the cutting. A machined surface cut by a machined part and a machined surface machined by the second machined part having the second radius of curvature are formed at different positions on the surface of the work material. The processing method according to claim 1. A tool for cutting a work material,
A first machining portion having a first radius of curvature;
A second processed portion having a second radius of curvature greater than the first radius of curvature;
An inflection point that is a boundary position between the first processed part and the second processed part,
The first processing unit and the second processing unit are:
It is configured to cut a predetermined cutting amount from the work material by feeding in a cutting direction from the outer periphery of the work material toward the rotation axis of the work material,
In the depth of cut between the first surface including the bottom of the surface of the work material after cutting and the second surface, which is the surface of the work material before cutting, the position of the inflection point is the first surface. A cutting tool for the work material according to the machining conditions set to be 50% × the depth of cut or more. A boundary position between the first machining portion having the first curvature radius, the second machining portion having a second curvature radius larger than the first curvature radius, and the first machining portion and the second machining portion. A power transmission component manufacturing method for cutting a power transmission component with a tool having an inflection point, wherein the manufacturing method includes:
A step of cutting a predetermined cutting amount from the work material by feeding in a cutting direction from the outer periphery of the work material to form the power transmission component toward the rotation axis of the work material, ,
In the depth of cut between the first surface including the bottom of the surface of the work material after cutting by the first work part and the second work part, and the second surface which is the surface of the work material before cutting The method of manufacturing a power transmission component, wherein the work material is cut under a machining condition set such that the position of the inflection point is 50% x the depth of cut from the first surface.

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