Chamfering tool

Abstract

This chamfering tool rotates about the axis. The chamfering tool comprises a rake face, a front flank face, a rear flank face, a front cutting edge, and a rear cutting edge. The front flank face is continuous with the rake face. The rear flank face is located rearward in the axial direction with respect to the front flank face, and is continuous with the rake face and the front flank face. The front cutting edge is constituted by a ridge line between the rake face and the front flank face. The rear cutting edge is constituted by a ridge line between the rake face and the rear flank face. In the radial direction of the chamfering tool, the front end of the front cutting edge is disposed inward of the rear end of the front cutting edge. In the radial direction of the chamfering tool, the front end of the rear cutting edge is disposed outward of the rear end of the rear cutting edge. The true rake angle of the front cutting edge is greater than 0°. The true rake angle of the rear cutting edge is greater than 0°.

Description

Chamfering tool

[0001] This disclosure relates to a chamfering tool.

[0002] Japanese Patent Application Laid-Open No. 2021-74798 (Patent Document 1) discloses a chamfering tool that can chamfer the end of the upper surface of a workpiece to be machined.

[0003] Japanese Patent Application Laid-Open No. 2021-74798

[0004] The chamfering tool according to this disclosure rotates around an axis. The chamfering tool includes a rake face, a front relief face, a rear relief face, a front cutting edge, and a rear cutting edge. The front relief face is continuous with the rake face. The rear relief face is located axially rearward with respect to the front relief face and is continuous with the rake face and the front relief face. The front cutting edge is formed by the ridge line between the rake face and the front relief face. The rear cutting edge is formed by the ridge line between the rake face and the rear relief face. In the radial direction of the chamfering tool, the front end of the front cutting edge is arranged inside the rear end of the front cutting edge. In the radial direction of the chamfering tool, the front end of the rear cutting edge is arranged outside the rear end of the rear cutting edge. The true rake angle of the front cutting edge is greater than 0°. The true rake angle of the rear cutting edge is greater than 0°.

[0005] FIG. 1 is a front view of the chamfering tool according to the first embodiment. FIG. 2 is a side view of the chamfering tool according to the first embodiment. FIG. 3 is a partially enlarged side view in region III of FIG. 2. FIG. 4 is a perspective view showing the true rake angle of the front cutting edge. FIG. 5 is a perspective view showing the true rake angle of the rear cutting edge. FIG. 6 is a schematic view showing the state of chamfering the upper surface of the workpiece using the front cutting edge. FIG. 7 is a schematic view showing the state of chamfering the lower surface of the workpiece using the rear cutting edge.

[0006] [Problems to be Solved by the Present Disclosure] There is known a chamfering tool having a front cutting edge for chamfering the end of the upper surface of a workpiece to be machined and a rear cutting edge for chamfering the end of the lower surface of the workpiece to be machined. In such a chamfering tool, generally, the radial rake angle is less than 0°, and the axial rake angle is greater than 0°. However, when chamfering is performed using such a chamfering tool, the cutting resistance is large.

[0007] The purpose of this disclosure is to provide a chamfering tool with reduced cutting resistance. [Effects of this disclosure] According to this disclosure, a chamfering tool with reduced cutting resistance can be provided.

[0008] [Outline of Embodiments] First, an outline of the embodiments of this disclosure will be described.

[0009] (1) The chamfering tool according to the present disclosure rotates about an axis. The chamfering tool comprises a rake face, a front relief face, a rear relief face, a front cutting edge, and a rear cutting edge. The front relief face is connected to the rake face. The rear relief face is located axially rearward with respect to the front relief face and is connected to the rake face and the front relief face. The front cutting edge is formed by the ridge line between the rake face and the front relief face. The rear cutting edge is formed by the ridge line between the rake face and the rear relief face. In the radial direction of the chamfering tool, the front end of the front cutting edge is positioned inward from the rear end of the front cutting edge. In the radial direction of the chamfering tool, the front end of the rear cutting edge is positioned outward from the rear end of the rear cutting edge. The true rake angle of the front cutting edge is greater than 0°. The true rake angle of the rear cutting edge is greater than 0°.

[0010] The chamfering tool described herein reduces cutting resistance when chamfering a workpiece. As a result, the generation of secondary burrs and altered processing layers that occur during chamfering can be suppressed. Furthermore, the reduced cutting resistance improves the lifespan of the chamfering tool.

[0011] (2) In the chamfering tool described in (1) above, the radial rake angle may be greater than 0°. This results in both the true rake angle of the front cutting edge and the true rake angle of the rear cutting edge being greater than 0°.

[0012] (3) In the case of the chamfering tool according to (1) or (2) above, the radial rake angle may be 1° or more. This makes the true rake angle of both the front cutting edge and the rear cutting edge greater than 0°.

[0013] (4) In the case of a chamfering tool according to any of (1) to (3) above, the rake angle in the axial direction may be -10° or more and 10° or less. This makes the true rake angle of both the front cutting edge and the rear cutting edge greater than 0°.

[0014] (5) In the case of a chamfering tool according to any of (1) to (4) above, the rake angle in the axial direction may be -5° or more and 5° or less. This makes the true rake angle of both the front cutting edge and the rear cutting edge greater than 0°.

[0015] (6) In the case of a chamfering tool according to any of (1) to (5) above, the number of front cutting edges may be 3 or more and 6 or less. This reduces the cutting resistance when chamfering the upper surface of the workpiece.

[0016] (7) In the case of a chamfering tool according to any of (1) to (6) above, the number of rear cutting edges may be 3 or more and 6 or less. This reduces the cutting resistance when chamfering the lower surface of the workpiece.

[0017] [Details of Embodiments] The details of embodiments of the present disclosure (hereinafter also referred to as these embodiments) will be described below with reference to the drawings. In the following drawings, identical or corresponding parts will be given the same reference numerals, and their descriptions will not be repeated.

[0018] (First Embodiment) First, the chamfering tool 100 according to the first embodiment will be described.

[0019] Figure 1 is a front view of the chamfering tool 100 according to the first embodiment. Figure 2 is a side view of the chamfering tool 100 according to the first embodiment. Figure 3 is a partially enlarged side view of area III in Figure 2.

[0020] The chamfering tool 100 rotates around axis A. Specifically, as shown in Figure 1, the chamfering tool 100 rotates counterclockwise around axis A. The direction perpendicular to axis A and radiating outward from axis A is defined as the radial direction.

[0021] As shown in Figure 2, the chamfering tool 100 has a front end 4 and a rear end 5. The axis A extends from the front end 4 along the rear end 5. The direction from the front end 4 towards the rear end 5 is the rearward direction along the axis. The direction from the rear end 5 towards the front end 4 is the forward direction along the axis. The front end 4 and the rear end 5 are planes perpendicular to the axis A.

[0022] The chamfering tool 100 has a cutting section 1 and a main body section 2. The cutting section 1 is connected to the main body section 2. The cutting section 1 is located axially forward of the main body section 2. Specifically, the main body section 2 includes a shank region 2a and a narrow region 2b. In the radial direction, the diameter of the narrow region 2b is smaller than the diameter of the shank region 2a.

[0023] The rear end portion 5 is formed by the shank region 2a. The narrow region 2b is connected to the shank region 2a. The narrow region 2b is located axially forward of the shank region 2a. The cutting portion 1 is connected to the narrow region 2b. The cutting portion 1 is located axially forward of the narrow region 2b. The front end portion 4 is formed by the cutting portion 1.

[0024] As shown in Figure 3, the chamfering tool 100 has a front relief face 10, a rear relief face 20, a rake face 30, a front cutting edge 13, and a rear cutting edge 23. The front relief face 10, the rear relief face 20, the rake face 30, the front cutting edge 13, and the rear cutting edge 23 are formed in the cutting portion 1.

[0025] The scoop face 30 is connected to the front relief face 10, the rear relief face 20, and the front end portion 4. The front relief face 10 is connected to the front end portion 4, the scoop face 30, and the rear relief face 20. The rear relief face 20 is connected to the scoop face 30 and the front relief face 10.

[0026] As shown in Figure 3, the front relief surface 10 is positioned so as to be sandwiched between the front end 4 and the rear relief surface 20 in the axial direction. In other words, the front relief surface 10 is located axially forward of the rear relief surface 20, and the rear relief surface 20 is located axially rearward of the front relief surface 10.

[0027] The front relief surface 10 includes a first front relief surface 11 and a second front relief surface 12. The first front relief surface 11 is located forward in the rotational direction relative to the second front relief surface 12 (see Figure 1). The rear relief surface 20 includes a first rear relief surface 21 and a second rear relief surface 22. The first rear relief surface 21 is located forward in the rotational direction relative to the second rear relief surface 22.

[0028] The front cutting edge 13 is formed by the ridge line between the rake face 30 and the first front relief face 11 of the front relief face 10. By rotating the chamfering tool 100 according to this embodiment 1 and bringing the front cutting edge 13 into contact with the end 201 of the upper surface of the workpiece 200, the end 201 of the upper surface of the workpiece 200 can be chamfered (see Figure 6).

[0029] The rear cutting edge 23 is formed by the ridge line between the rake face 30 and the first rear relief face 21 of the rear relief face 20. By rotating the chamfering tool 100 according to this embodiment 1 and bringing the rear cutting edge 23 into contact with the end 202 of the lower surface of the workpiece 200, the end 202 of the lower surface of the workpiece 200 can be chamfered (see Figure 7).

[0030] As shown in Figure 1, the chamfering tool 100 has an outer peripheral end 40. The outer peripheral end 40 is located at the position furthest from the axis A in the radial direction within the cutting portion 1.

[0031] As shown in Figure 3, the front end 13a of the front cutting edge 13 is connected to the front end 4. The rear end 13b of the front cutting edge 13 is connected to the outer peripheral end 40. In other words, in the radial direction of the chamfering tool 100, the front end 13a of the front cutting edge 13 is positioned inward from the rear end 13b of the front cutting edge 13.

[0032] The front end 23a of the rear cutting edge 23 is connected to the outer peripheral end 40. In other words, in the radial direction of the chamfering tool 100, the front end 23a of the rear cutting edge 23 is positioned further outward than the rear end 23b of the rear cutting edge 23.

[0033] In this way, the front cutting edge 13 and the rear cutting edge 23 are connected via the outer peripheral end 40. As a result, the number of front cutting edges 13 and rear cutting edges 23 can be increased to three or more. Furthermore, the strength of the chamfering tool 100 is improved.

[0034] The number of front cutting edges 13 and rear cutting edges 23 configured as described above may be between 3 and 6. In the chamfering tool 100 according to this embodiment 1, the number of front cutting edges 13 and rear cutting edges 23 is 3. By increasing the number of front cutting edges 13 and rear cutting edges 23 in this way, the cutting resistance of each cutting edge when chamfering the workpiece 200 is reduced.

[0035] Figure 4 is a perspective view showing the true rake angle θ1 of the front cutting edge 13. Figure 5 is a perspective view showing the true rake angle θ2 of the rear cutting edge 23. In this specification, "true rake angle θ1 of the front cutting edge 13" is the angle between axis A and the rear cutting edge 23 when viewed from a direction perpendicular to the rear cutting edge 23 (along the direction of arrow D1 in Figure 3) at a position where the outer peripheral end 40 (rear end 13b of the front cutting edge 13) coincides with axis A, as shown in Figure 4. In this specification, "true rake angle θ2 of the rear cutting edge 23" is the angle between axis A and the front cutting edge 13 when viewed from a direction perpendicular to the front cutting edge 13 (along the direction of arrow D2 in Figure 3) at a position where the outer peripheral end 40 (front end 23a of the rear cutting edge 23) coincides with axis A, as shown in Figure 5.

[0036] As shown in Figure 4, when the rear end 23b of the rear cutting edge 23 is located behind the axis A in the rotational direction, the true rake angle θ1 is positive. As shown in Figure 5, when the front end 13a of the front cutting edge 13 is located behind the axis A in the rotational direction, the true rake angle θ2 is positive.

[0037] In the chamfering tool 100 according to this embodiment 1, as shown in Figure 4, the true rake angle θ1 of the front cutting edge 13 is greater than 0°. The true rake angle θ1 may be 3° or more, or 7° or more. Also, in the chamfering tool 100 according to this embodiment 1, as shown in Figure 5, the true rake angle θ2 of the rear cutting edge 23 is greater than 0°. The true rake angle θ2 may be 3° or more, or 7° or more. When both the true rake angle θ1 and the true rake angle θ2 are greater than 0°, the cutting resistance is reduced when chamfering the end 201 of the upper surface and the end 202 of the lower surface of the workpiece 200. As a result, the generation of secondary burrs and processed altered layers that occur during chamfering can be suppressed. Furthermore, by reducing the cutting resistance, the amount of wear on the front cutting edge 13 and the rear cutting edge 23 is reduced. As a result, the lifespan of the chamfering tool 100 is improved.

[0038] The true rake angle θ1 of the front cutting edge 13 and the true rake angle θ2 of the rear cutting edge 23 are determined by the radial rake angle θr and the axial rake angle θz of the chamfering tool 100.

[0039] As shown in Figure 1, the "radial rake angle θr" in this specification is the angle between the line passing from axis A through the outer peripheral end 40 and the front cutting edge 13 when viewed from a direction along axis A. When viewed from a direction along axis A, the radial rake angle θr is positive when the front end 13a of the front cutting edge 13 is located behind the outer peripheral end 40 (the rear end 13b of the front cutting edge 13) in the rotational direction. In the chamfering tool 100 according to this embodiment 1, the radial rake angle θr is 10°.

[0040] In this specification, the "axial rake angle θz" is the angle between the axis A and the rake face 30. When viewed from a direction along axis A, if the rear cutting edge 23 is in front of the front cutting edge 13 in the rotational direction, the axial rake angle θz is positive. In the chamfering tool 100 according to this embodiment 1, the axial rake angle θz is 0°, and the rake face 30 and axis A are parallel to each other.

[0041] The rake angle θr in the radial direction may be greater than 0°, or may be 1° or more. The rake angle θz in the axial direction may be -10° or more and 10° or less, or may be -5° or more and 5° or less. By doing so, the true rake angles θ1 of the front cutting edge 13 and θ2 of the rear cutting edge 23 both become greater than 0°.

[0042] <Operation> Fig. 6 is a schematic diagram showing a state of chamfering the upper surface of the workpiece 200 using the front cutting edge 13. Fig. 7 is a schematic diagram showing a state of chamfering the lower surface of the workpiece 200 using the rear cutting edge 23.

[0043] When chamfering the end portion 201 of the upper surface of the workpiece 200, first, the front cutting edge 13 is brought into contact with the end portion 201 of the upper surface of the workpiece 200 in a state where the chamfering tool 100 according to the first embodiment is rotated. Next, as shown in Fig. 6, by moving the chamfering tool 100 along the direction of arrow D3, the end portion 201 can be chamfered.

[0044] When chamfering the end portion 202 of the lower surface of the workpiece 200, first, the rear cutting edge 23 is brought into contact with the end portion 202 of the lower surface of the workpiece 200 in a state where the chamfering tool 100 according to the first embodiment is rotated. Next, as shown in Fig. 7, by moving the chamfering tool 100 along the direction of arrow D4, the end portion 202 can be chamfered.

[0045] Next, the operation and effect of the chamfering tool 100 according to the present disclosure will be described. Conventionally, when chamfering the workpiece 200 using the chamfering tool 100, the cutting resistance was large. Also, with the requirement for high finish accuracy of the workpiece 200 after chamfering, suppression of secondary burrs has been demanded.

[0046] The chamfering tool 100 according to this embodiment rotates around the axis A. The chamfering tool 100 includes a rake face 30, a front relief face 10, a rear relief face 20, a front cutting edge 13, and a rear cutting edge 23. The front relief face 10 is continuous with the rake face 30. The rear relief face 20 is located axially rearward with respect to the front relief face 10 and is continuous with the rake face 30 and the front relief face 10. The front cutting edge 13 is formed by the ridge line between the rake face 30 and the front relief face 10. The rear cutting edge 23 is formed by the ridge line between the rake face 30 and the rear relief face 20. In the radial direction of the chamfering tool 100, the front end 13a of the front cutting edge 13 is arranged inside the rear end 13b of the front cutting edge 13. In the radial direction of the chamfering tool 100, the front end 23a of the rear cutting edge 23 is arranged outside the rear end 23b of the rear cutting edge 23. The true rake angle θ1 of the front cutting edge 13 is greater than 0°. The true rake angle θ2 of the rear cutting edge 23 is greater than 0°. Thereby, the cutting resistance during chamfering both on the upper surface and the end portions 201, 202 of the lower surface of the workpiece 200 is reduced. As a result, the occurrence of secondary burrs and the processed altered layer generated during chamfering can be suppressed. Further, by reducing the cutting resistance, the life of the chamfering tool 100 is improved.

[0047] According to the chamfering tool 100 of this embodiment, the number of the front cutting edges 13 is 3 or more and 6 or less. Thereby, the cutting resistance is reduced when chamfering the upper surface of the workpiece 200.

[0048] According to the chamfering tool 100 of this embodiment, the number of the rear cutting edges 23 is 3 or more and 6 or less. Thereby, the cutting resistance is reduced when chamfering the lower surface of the workpiece 200.

[0049] <Example> (Sample Preparation) First, the chamfering tools 100 of Sample 1 to Sample 4 were prepared. In the chamfering tools 100 of Sample 1 to Sample 4, the number of the front cutting edges 13 and the rear cutting edges 23 is 3 in each case. The blade diameter of the chamfering tools 100 of Sample 1 to Sample 4 is 6 mm.

[0050] The chamfering tools 100 of Samples 1 to 4 are made of cemented carbide. A coating film is formed on the surface of the chamfering tools 100 of Samples 1 to 4. The coating film on the chamfering tool 100 of Sample 1 is a TiAlCrN coating containing titanium (Ti), aluminum (Al), chromium (Cr), and nitrogen (N). The coating film on the chamfering tool 100 of Sample 2 is a TiAlN coating containing Ti, Al, and N. The coating film on the chamfering tool 100 of Sample 3 is a CrN coating containing Cr and N.

[0051] Samples 1 to 3 are comparative examples. In the comparative examples, either the true rake angle θ1 or the true rake angle θ2 is less than 0°. Sample 4 is an example. In the example, both the true rake angle θ1 and the true rake angle θ2 are greater than 0°. The radial rake angle θr, axial rake angle θz, true rake angle θ1, and true rake angle θ2 for each sample are as shown in Table 1.

[0052]

[0053] (Processing Condition 1) Next, when the workpiece 200 is a titanium alloy plate, chamfering was performed on the end 201 on the upper surface and the end 202 on the lower surface of the workpiece 200 using the chamfering tools 100 of Sample 1 to Sample 4. The end 201 on the upper surface is chamfered by the front cutting edge 13. The end 202 on the lower surface is chamfered by the rear cutting edge 23. The width of the chamfered workpiece 200 is 220 mm.

[0054] A BT30 vertical machining center was used. The cutting speed Vc was set to 100 m / min. The feed rate f was set to 0.033 mm / revolution. The chamfer amount was set to 0.5 mm so that ends 201 and 202 were chamfered.

[0055] The workpiece material 200 is a titanium (Ti) alloy sheet mainly used in the aerospace industry. The titanium alloy sheet contains 6 mass percent aluminum and 4 mass percent vanadium (V). In processing condition 1, the cemented carbide used in the chamfering tool 100 of sample 4 was a cemented carbide of grade KH26 (manufactured by Sumitomo Electric Industries, Ltd.).

[0056] (Test Result 1) The height of burrs generated at the end 201 on the upper surface and the end 202 on the lower surface, the amount of wear on the front cutting edge 13 and the rear cutting edge 23, and the cutting resistance applied to the chamfering tool 100 were evaluated. Note that the cutting resistance is the resultant force of the cutting resistance in the x and y directions, and the cutting resistance in the axial direction (z direction) is not considered. Table 2 shows the test results under processing condition 1, with the workpiece material 200 being a titanium alloy plate.

[0057]

[0058] As shown in Table 2, when using each of the chamfering tools 100 from Sample 1 to Sample 3, the height of the burrs generated on the upper edge 201 and the lower edge 202 was 5 μm or more. On the other hand, when using the chamfering tool 100 of Sample 4, the height of the burrs generated on the upper edge 201 and the lower edge 202 was 0 μm. Thus, by using a chamfering tool 100 in which both the true rake angle θ1 and the true rake angle θ2 are greater than 0°, the finish of the workpiece 200 after chamfering is improved.

[0059] As shown in Table 2, when using each of the chamfering tools 100 from Sample 1 to Sample 3, the wear of the front cutting edge 13 and the rear cutting edge 23 was 10 μm or more. On the other hand, when using the chamfering tool 100 of Sample 4, the wear of the front cutting edge 13 and the rear cutting edge 23 was 5 μm. Thus, by using a chamfering tool 100 in which both the true rake angle θ1 and the true rake angle θ2 are greater than 0°, the wear of the front cutting edge 13 and the rear cutting edge 23 is reduced.

[0060] As shown in Table 2, when using each of the chamfering tools 100 from Sample 1 to Sample 3, the cutting resistance applied to the front cutting edge 13 when chamfering the upper end 201 and the cutting resistance applied to the rear cutting edge 23 when chamfering the lower end 202 were both 25 N or more. On the other hand, the cutting resistance applied to the front cutting edge 13 when chamfering the upper end 201 and the cutting resistance applied to the rear cutting edge 23 when chamfering the lower end 202 were both less than 25 N. Thus, by using a chamfering tool 100 in which both the true rake angle θ1 and the true rake angle θ2 are greater than 0°, the cutting resistance of the front cutting edge 13 and the rear cutting edge 23 is reduced.

[0061] (Processing Condition 2) Next, when the workpiece 200 is Inconel® 718, chamfering was performed on the end 201 on the upper surface and the end 202 on the lower surface of the workpiece 200 using the chamfering tools 100 of Samples 1 to 4. The end 201 on the upper surface is chamfered by the front cutting edge 13. The end 202 on the lower surface is chamfered by the rear cutting edge 23. The width of the chamfered workpiece 200 is 220 mm.

[0062] A DGM Mori Seiki Co., Ltd. NVX5100 vertical machining center was used. The cutting speed Vc was set to 30 m / min. The feed rate f was set to 0.033 mm / revolution. The chamfer amount was set to 0.5 mm so that ends 201 and 202 were chamfered.

[0063] The workpiece material 200 is Inconel 718. In machining condition 2, the cemented carbide used in the chamfering tool 100 of sample 4 was a cemented carbide of grade AFU (manufactured by Sumitomo Electric Industries, Ltd.).

[0064] (Test Results 2) The height of burrs generated at the end 201 on the upper surface and the end 202 on the lower surface, the amount of wear on the front cutting edge 13 and the rear cutting edge 23, and the cutting resistance applied to the chamfering tool 100 were evaluated. Note that the cutting resistance is the resultant force of the cutting resistance in the x and y directions, and the cutting resistance in the axial direction (z direction) is not considered. Table 3 shows the test results under processing condition 2, where the workpiece material 200 was a titanium alloy plate.

[0065]

[0066] As shown in Table 3, when using each of the chamfering tools 100 from Sample 1 to Sample 3, the height of the burr generated on the upper end 201 was 8 μm or more. On the other hand, when using the chamfering tool 100 of Sample 4, the height of the burr generated on the upper end 201 was 5 μm. The height of the burr generated on the lower end 202 was 30 μm or more. On the other hand, when using the chamfering tool 100 of Sample 4, the height of the burr generated on the lower end 202 was 11 μm. Thus, by using a chamfering tool 100 in which both the true rake angle θ1 and the true rake angle θ2 are greater than 0°, the finish of the workpiece 200 after chamfering is improved.

[0067] As shown in Table 3, when using each of the chamfering tools 100 from Sample 1 to Sample 3, the wear of the front cutting edge 13 and the rear cutting edge 23 was 40 μm or more. On the other hand, when using the chamfering tool 100 of Sample 4, the wear of the front cutting edge 13 and the rear cutting edge 23 was 35 μm or less. Thus, by using a chamfering tool 100 in which both the true rake angle θ1 and the true rake angle θ2 are greater than 0°, the wear of the front cutting edge 13 and the rear cutting edge 23 is reduced.

[0068] As shown in Table 3, when using each of the chamfering tools 100 from Sample 1 to Sample 3, the cutting resistance applied to the front cutting edge 13 when chamfering the upper end 201 and the cutting resistance applied to the rear cutting edge 23 when chamfering the lower end 202 were both 90 N or more. On the other hand, the cutting resistance applied to the front cutting edge 13 when chamfering the upper end 201 and the cutting resistance applied to the rear cutting edge 23 when chamfering the lower end 202 were both less than 80 N. Thus, by using a chamfering tool 100 in which both the true rake angle θ1 and the true rake angle θ2 are greater than 0°, the cutting resistance of the front cutting edge 13 and the rear cutting edge 23 is reduced.

[0069] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The basic scope of this disclosure is indicated by the claims rather than the embodiments described above, and all modifications within the meaning and scope of the claims are intended to be included.

[0070] 1 Cutting section, 2 Main body, 2a Shank area, 2b Narrow area, 4 Front end, 5 Rear end, 10 Front relief face, 11 First front relief face, 12 Second front relief face, 13 Front cutting edge, 13a, 23a Front end, 13b, 23b Rear end, 20 Rear relief face, 21 First rear relief face, 22 Second rear relief face, 23 Rear cutting edge, 30 Rake face, 40 Outer circumference end, 100 Chamfering tool, 200 Workpiece, 201, 202 End, A Axis, D1, D2, D3, D4 Arrows, θ1, θ2 True rake angle, θr Radial rake angle, θz Axial rake angle.

Claims

1. A chamfering tool that rotates around an axis, comprising: a rake face; a front relief face connected to the rake face; a rear relief face located axially rearward with respect to the front relief face and connected to the rake face and the front relief face; a front cutting edge formed by the ridge line of the rake face and the front relief face; and a rear cutting edge formed by the ridge line of the rake face and the rear relief face, wherein in the radial direction of the chamfering tool, the front end of the front cutting edge is positioned inward from the rear end of the front cutting edge; in the radial direction of the chamfering tool, the front end of the rear cutting edge is positioned outward from the rear end of the rear cutting edge; the true rake angle of the front cutting edge is greater than 0°; and the true rake angle of the rear cutting edge is greater than 0°.

2. The chamfering tool according to claim 1, wherein the radial rake angle is greater than 0°.

3. The chamfering tool according to claim 1 or claim 2, wherein the radial rake angle is 1° or more.

4. The chamfering tool according to any one of claims 1 to 3, wherein the rake angle in the axial direction is -10° or more and 10° or less.

5. The chamfering tool according to any one of claims 1 to 4, wherein the rake angle in the axial direction is -5° or more and 5° or less.

6. The chamfering tool according to any one of claims 1 to 5, wherein the number of front cutting edges is 3 or more and 6 or less.

7. The chamfering tool according to any one of claims 1 to 6, wherein the number of rear cutting edges is 3 or more and 6 or less.

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