Cutting tools

Abstract

To provide a cutting tool capable of controlling the shape and size of chips generated during cutting.SOLUTION: A cutting tool 10 includes a plurality of cutting blade parts 14 which are disposed at intervals in a circumferential direction D1 of the cutting tool 10. Each of the cutting blade parts 14 has a cutting blade 20 extending along a radial direction D2 of the cutting tool 10. The cutting blade 20 has: a first portion cutting blade 20A; and a second portion cutting blade 20B located between the first portion cutting blade 20A and an axis AX. A rake angle θ1 of the first portion cutting blade 20A differs from a rake angle θ2 of the second portion cutting blade 20B.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a cutting tool.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2007-069326 discloses a drill having a rake angle of 0° formed at the tip of a cutting edge.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to remove chips generated during cutting from the workpiece without affecting the machining operation, a cutting tool capable of controlling the shape of the chips during machining is eagerly awaited.

Means for Solving the Problems

[0005] One aspect of the present invention is a cutting tool that rotates relative to a workpiece about an axis, the cutting tool including a plurality of cutting edge portions spaced apart in the circumferential direction of the cutting tool, each of the plurality of cutting edge portions having a cutting edge extending along the radial direction of the cutting tool, the cutting edge having a first partial cutting edge and a second partial cutting edge located between the first partial cutting edge and the axis, and the rake angle of the first partial cutting edge being different from the rake angle of the second partial cutting edge.

Effects of the Invention

[0006] According to one aspect of the present invention, a cutting tool capable of controlling the shape and size of chips generated during cutting is provided.

Brief Description of the Drawings

[0007] [Figure 1] Figure 1 shows a cutting tool. [Figure 2] Figure 2 shows the cutting edge of the cutting tool along its axis. [Figure 3] Figure 3 shows a view focusing on a single cutting edge. [Figure 4] Figure 4 is a cross-sectional view along the line IV-IV in Figure 3. [Figure 5] Figure 5 is a cross-sectional view along the VV line in Figure 3. [Figure 6] Figure 6 shows the state of the cutting edge of the main cutting tool when cutting a workpiece. [Figure 7] Figure 7 shows the state of the partial cutting edge of the secondary cutting edge when cutting a workpiece. [Modes for carrying out the invention]

[0008] When chips generated by cutting a workpiece are relatively large or long, they are difficult to remove from the workpiece. In particular, when drilling holes, chips are difficult to remove from inside the hole. In this case, chips tend to get entangled in the workpiece or cutting tool, leading to malfunctions. The technology of this disclosure aims to provide a cutting tool that can control the shape of chips simultaneously with machining.

[0009] As shown in Figure 1, the cutting tool 10 is, for example, a drill, but is not limited to this. The cutting tool 10 is fixed to the spindle of a machine tool, machining center, etc. In this case, the cutting tool 10 rotates around its axis AX. Alternatively, the cutting tool 10 may be fixed to a jig, and the workpiece W (see Figure 6) may rotate around the axis AX of the cutting tool 10. The cutting tool 10 has a tool body 12 and a plurality of cutting blades 14.

[0010] The tool body 12 is rod-shaped. The axis AX of the tool body 12 and the axis AX of the cutting tool 10 are located on the same line. Multiple cutting edges 14 are formed on the tool body 12. As shown in Figure 2, the multiple cutting edges 14 are spaced apart in the circumferential direction D1 of the cutting tool 10. In Figure 2, there are four cutting edges 14, but the number is not limited to this. The configuration of each of the multiple cutting edges 14 is similar.

[0011] As shown in Figure 3, the cutting blade portion 14 has a main blade portion 16, a secondary blade portion 18, a cutting edge 20, a blade direction groove 22, and a recess 24.

[0012] The main cutting edge portion 16 and the secondary cutting edge portion 18 are used for cutting the workpiece. The main cutting edge portion 16 is located outside the secondary cutting edge portion 18 in the radial direction D2 (see Figure 2) of the cutting tool 10. The secondary cutting edge portion 18 is located between the axis AX of the cutting tool 10 and the main cutting edge portion 16. A gash is formed on the secondary cutting edge portion 18. The hardness of the main cutting edge portion 16 may be the same as that of the secondary cutting edge portion 18, or it may be harder than the secondary cutting edge portion 18. For example, the main cutting edge portion 16 is made of diamond, and the secondary cutting edge portion 18 is made of an alloy such as cemented carbide. The main cutting edge portion 16 may be brazed to the tool body 12.

[0013] The cutting edge 20 extends along the radial direction D2 of the cutting tool 10. The cutting edge 20 cuts the workpiece due to the relative rotation of the cutting tool 10 and the workpiece W around the axis AX. The cutting edge 20 includes a partial cutting edge 20A of the main cutting edge portion 16 and a partial cutting edge 20B of the secondary cutting edge portion 18.

[0014] The blade direction groove 22 is formed on the rake face 14F of the cutting edge portion 14. The blade direction groove 22 extends along the partial cutting edge 20A. The rake face 14F is the surface through which the chips generated by cutting by the cutting edge 20 pass. The blade direction groove 22 is a groove that primarily controls the shape of the chips by curling the chips generated by the cutting edge 20.

[0015] In this embodiment, the cutting edge direction grooves 22A, 22B, and 22C are formed as cutting edge direction grooves 22, but the embodiment is not limited to this. In other words, there may be one cutting edge direction groove 22 or multiple cutting edge direction grooves 22. When there are multiple cutting edge direction grooves 22, the multiple cutting edge direction grooves 22 are spaced apart in the direction along the axis AX of the cutting tool 10. In this embodiment, the cutting edge direction groove 22A is located closest to the cutting edge 20. The cutting edge direction groove 22B is located further from the cutting edge 20 than the cutting edge direction groove 22A. The cutting edge direction groove 22C is located further from the cutting edge 20 than the cutting edge direction groove 22B.

[0016] Furthermore, when there are multiple blade direction grooves 22, it is the blade direction groove 22A that performs the function of controlling the shape of the chips generated by the partial cutting edge 20A. In this case, of the multiple blade direction grooves 22, the blade direction grooves 22B and 22C other than blade direction groove 22A do not substantially perform the above function.

[0017] When the partial cutting edge 20A wears down, the main blade portion 16 is ground from the partial cutting edge 20A to the line Lc1, thereby forming a new partial cutting edge at the line Lc1. In this case, the blade direction groove 22B functions to control the shape of the chips generated by the partial cutting edge formed at the line Lc1. Furthermore, when the partial cutting edge formed at the line Lc1 wears down, the main blade portion 16 is ground from the line Lc1 to the line Lc2, thereby forming a new partial cutting edge at the line Lc2. In this case, the blade direction groove 22C functions to control the shape of the chips generated by the partial cutting edge formed at the line Lc2. In other words, if there are multiple blade direction grooves 22, the blade direction grooves 22B and 22C, other than the blade direction groove 22A closest to the partial cutting edge 20A, are formed in advance in preparation for the formation of new partial cutting edges.

[0018] As shown in FIG. 4, the blade direction groove 22 is surrounded by a first inner portion 22F1, a second inner portion 22F2, and a bottom portion 22BT. The first inner portion 22F1 and the second inner portion 22F2 are located between the rake face 14F of the cutting edge portion 14 (main cutting edge portion 16) and the bottom portion 22BT of the blade direction groove 22. The first inner portion 22F1 and the second inner portion 22F2 face each other and extend along the partial cutting edge 20A. The bottom portion 22BT is located between the first inner portion 22F1 and the second inner portion 22F2.

[0019] The first inner portion 22F1 is arranged closer to the partial cutting edge 20A than the second inner portion 22F2. The first inner portion 22F1 has an inclined surface IP1 that slopes so as to become lower as it approaches the bottom portion 22BT. Thereby, the first inner portion 22F1 can favorably guide the chips generated by the partial cutting edge 20A to the bottom portion 22BT. Note that the inclined surface IP1 may be curved.

[0020] The second inner portion 22F2 is arranged farther from the partial cutting edge 20A than the first inner portion 22F1. The second inner portion 22F2 has an inclined surface IP2 that slopes so as to become higher as it moves away from the bottom portion 22BT. Thereby, the chips generated by the partial cutting edge 20A are pushed by the inclined surface IP2 and are likely to curl, and as a result, the shape of the chips is easily controlled. Note that the inclined surface IP2 may be curved.

[0021] As shown in FIG. 5, the blade direction groove 22 has a first end portion 22E1 and a second end portion 22E2. The first end portion 22E1 is arranged closer to the axis AX of the cutting tool 10 than the second end portion 22E2. An inclined surface IP3 that slopes so as to become higher as it moves away from the bottom portion 22BT is formed between the first end portion 22E1 and the bottom portion 22BT. Thereby, the flow of the chips generated by the partial cutting edge 20A can be changed, and as a result, the chips are easily segmented.

[0022] The second end portion 22E2 reaches the outer circumferential surface of the main cutting edge portion 16. The outer circumferential surface of the main cutting edge portion 16 is flush with the surface of the tool body 12, but is not limited to this. Because the second end portion 22E2 reaches the outer circumferential surface of the main cutting edge portion 16, an inclined surface IP3 is not formed between the second end portion 22E2 and the bottom portion 22BT. However, an inclined surface IP3 may be formed between the second end portion 22E2 and the bottom portion 22BT. Also, the inclined surface IP3 may be curved. Furthermore, the second end portion 22E2 does not have to reach the outer circumferential surface of the main cutting edge portion 16. In this case, an inclined surface IP3 may be formed on the second end portion 22E2.

[0023] As shown in Figure 3, the recess 24 is formed on the rake face 14F of the main blade portion 16. The recess 24 divides the partial cutting edge 20A of the main blade portion 16. As a result, the recess 24 can cut the chips generated by the partial cutting edge 20A in a direction along the axis AX of the cutting tool 10. Consequently, the chips are divided in the radial direction D2 of the cutting tool 10.

[0024] In this embodiment, two recesses 24, recess 24A and recess 24B, are formed, but the embodiment is not limited to this. That is, there may be one or more recesses 24. When there are multiple recesses 24, the multiple recesses 24 are spaced apart in the radial direction D2 of the cutting tool 10. In this case, the number of chips that are divided in the radial direction D2 of the cutting tool 10 can be increased. Alternatively, the recesses 24 of each of the multiple cutting edge portions 14 spaced apart in the circumferential direction D1 of the cutting tool 10 may be provided at positions that are phase-shifted from each other. In this case, it is possible to prevent cutting marks from remaining in the machined hole, which is more desirable.

[0025] In this embodiment, recess 24A is located closest to the axis AX of the cutting tool 10. Recess 24B is located further from the axis AX of the cutting tool 10 than recess 24A. Recesses 24A and 24B divide the partial cutting edge 20A into portion S1, portion S2, and portion S3.

[0026] One end of part S1 and one end of part S2 face each other via a recess 24A. The other end of part S2 and one end of part S3 face each other via a recess 24B. The corner of one end of part S2 is chamfered to form a chamfered portion CN1 on the partial cutting edge 20A. Similarly, the corner of one end of part S3 is chamfered to form a chamfered portion CN2 on the partial cutting edge 20A. By forming chamfered portions CN1 and CN2, stress concentration on the partial cutting edge 20A can be avoided.

[0027] If multiple blade direction grooves 22 are formed, notches CO1 and CO2 may be formed in the area corresponding to the chamfered portion CN1. Similarly, notches CO3 and CO4 may be formed in the area corresponding to the chamfered portion CN2.

[0028] The notch CO1 is formed on the rake face 14F between the cutting direction groove 22A and the cutting direction groove 22B. The notch CO1 is formed in a location aligned with the axis AX relative to the chamfer CN1. When a new partial cutting edge is formed at the location of line Lc1, the notch CO1 becomes a chamfer.

[0029] The notch CO2 is formed on the rake face 14F between the cutting direction groove 22B and the cutting direction groove 22C. The notch CO2 is formed in a location aligned with the axis AX relative to the chamfer CN1. When a new partial cutting edge is formed at the location of line Lc2, the notch CO2 becomes a chamfer.

[0030] The notch CO3 is formed on the rake face 14F between the cutting direction groove 22A and the cutting direction groove 22B. The notch CO3 is formed in a location aligned with the axis AX relative to the chamfer CN2. When a new partial cutting edge is formed at the location of line Lc1, the notch CO3 becomes a chamfer.

[0031] The notch CO4 is formed on the rake face 14F between the cutting direction groove 22B and the cutting direction groove 22C. The notch CO4 is formed in a location aligned with the axis AX relative to the chamfer CN2. When a new partial cutting edge is formed at the location of line Lc2, the notch CO4 becomes a chamfer.

[0032] The recess 24 may be formed as an axial groove extending along the axis AX of the cutting tool 10. The axial groove intersects with the cutting edge groove 22. Also, one end of the axial groove reaches the tip of the partial cutting edge 20A.

[0033] Furthermore, when the recess 24 is formed as an axial groove, the portion of the axial groove that divides the partial cutting edge 20A is responsible for dividing the chips generated by the partial cutting edge 20A. The portion other than this part does not substantially perform the above function. As described above, when a new partial cutting edge is formed at the location of line Lc1, the portion that divides the newly formed partial cutting edge performs the above function. Similarly, when a new partial cutting edge is formed at the location of line Lc2, the portion that divides the newly formed partial cutting edge performs the above function.

[0034] Figure 6 shows the state of the partial cutting edge 20A of the main cutting edge 16 when cutting the workpiece W. Figure 7 shows the state of the partial cutting edge 20B of the secondary cutting edge 18 when cutting the workpiece W.

[0035] The rake angle θ1 of the partial cutting edge 20A (Figure 6) and the rake angle θ2 of the partial cutting edge 20B (Figure 7) are different. As a result, the direction in which the chips flow differs between the partial cutting edge 20A and the partial cutting edge 20B. Consequently, the chips are more easily broken up compared to the case where the direction in which the chips flow is the same for both the partial cutting edge 20A and the partial cutting edge 20B.

[0036] The rake angle θ1 is the angle between a virtual line L extending vertically from the surface WF of the workpiece formed by cutting and the rake face F2 of the partial cutting edge 20A. The rake angle θ2 is the angle between the virtual line L and the rake face F4 of the partial cutting edge 20B. The rake face F2 of the partial cutting edge 20A and the rake face F4 of the partial cutting edge 20B are included in the rake face 14F of the cutting edge portion 14.

[0037] In this embodiment, the angle θ3 between the rake face F2 and the relief face F3 of the partial cutting edge 20A is acute. In contrast, the angle θ4 between the rake face F4 and the relief face F5 of the partial cutting edge 20B is obtuse. This increases the relative angle difference between the cutting edges of the partial cutting edge 20A and the partial cutting edge 20B. As a result, the chips are more easily broken up.

[0038] Furthermore, this is not limited to the case where the angle θ3 of the partial cutting edge 20A is acute and the angle θ4 of the partial cutting edge 20B is obtuse. For example, if the rake angle θ1 of the partial cutting edge 20A and the rake angle θ2 of the partial cutting edge 20B are different, then both the angle θ3 of the partial cutting edge 20A and the angle θ4 of the partial cutting edge 20B may be acute.

[0039] With regard to the above embodiments, the following additional information is disclosed.

[0040] (Note 1) This disclosure relates to a cutting tool (10) that rotates relative to a workpiece (W) about an axis (AX), and comprises a plurality of cutting edges (14) arranged at intervals in the circumferential direction (D1) of the cutting tool, each of which has a cutting edge (20) extending along the radial direction (D2) of the cutting tool, and the cutting edge has a first partial cutting edge (20A) and a second partial cutting edge (20B) located between the first partial cutting edge and the axis (AX), and the rake angle (θ1) of the first partial cutting edge and the rake angle (θ2) of the second partial cutting edge are different. As a result, the direction in which the chip flows differs between the first partial cutting edge and the second partial cutting edge. Consequently, the chip is more easily broken up compared to the case where the direction in which the chip flows is the same between the first partial cutting edge and the second partial cutting edge.

[0041] (Note 2) The cutting tool (10) described in Appendix 1 may have an acute angle (θ3) between the rake face (F2) and the relief face (F3) of the first partial cutting edge, and an obtuse angle (θ4) between the rake face (F4) and the relief face (F5) of the second partial cutting edge. This increases the relative angle difference between the cutting edges of the first and second partial cutting edges. As a result, chips are more easily broken up.

[0042] (Note 3) The cutting tool (10) described in Appendix 1 or 2 has a cutting-edge groove (22) formed on the rake face (14F) of the cutting edge portion, which extends along the first partial cutting edge, and an inclined surface (IP1) may be formed between the rake face of the first partial cutting edge and the bottom (22BT) of the cutting-edge groove. This makes it easier to guide the chips generated by the first partial cutting edge into the cutting-edge groove. As a result, the chips are more easily broken up in the cutting-edge groove.

[0043] (Note 4) The cutting tool (10) described in Appendix 3 may have an inclined surface (IP3) formed between the end (22E1) of the cutting edge groove and the bottom of the cutting edge groove. This allows the flow of chips generated by the first partial cutting edge to be altered, and as a result, the chips become easier to break apart.

[0044] (Note 5) The cutting tool (10) described in Appendix 1 has a recess (24) formed on the rake face of the cutting edge portion that divides the first partial cutting edge, and one end of the first portion (S2) of the first partial cutting edge and one end of the second portion (S1) of the first partial cutting edge face each other via the recess, the second portion is located between the first portion and the axis, and the corner of one end of the first portion may be chamfered to form a chamfered portion (CN1) on the first partial cutting edge. This makes it possible to avoid stress concentration on the first partial cutting edge.

[0045] Furthermore, the present invention is not limited to the disclosure described above, and various configurations can be adopted without departing from the spirit of the invention. [Explanation of symbols]

[0046] 10...Cutting tool 12...Tool body 14...Cutting edge portion 14F...Rake face of the cutting edge portion 16...Main blade section 18...Secondary blade section 20...Cutting edge; 20A, 20B...Partial cutting edge 22, 22A, 22B, 22C…Blade direction groove 22BT...Bottom of the groove in the direction of the blade 22E1...End of the groove in the direction of the blade 24…Concave portion AX…Axis center CN1... Chamfered section D1... Circumferential direction D2...Radial direction F2, F4...Rake face of partial cutting edge F3, F5... Relief surface of the partial cutting edge θ1, θ2... Rake angle θ3, θ4...Angles between the rake face and the relief face.

Claims

[Claim 1] A cutting tool that rotates relative to the workpiece around its axis, The cutting tool comprises a plurality of cutting blades arranged at intervals in the circumferential direction, Each of the plurality of cutting edges has a cutting edge that extends along the radial direction of the cutting tool. The cutting edge has a first partial cutting edge and a second partial cutting edge located between the first partial cutting edge and the axis. Unlike the rake angle of the first partial cutting edge and the rake angle of the second partial cutting edge, A recess is formed in the rake face of the cutting edge portion that divides the first partial cutting edge. One end of the first portion of the first cutting edge and one end of the second portion of the first cutting edge face each other via the recess. The second portion is located between the first portion and the axis, A cutting tool in which one end corner of the first part is chamfered, and a chamfered portion is formed on the first partial cutting edge.

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