Cutting tool

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 technology]

[0002] Japanese Patent Application Laid-Open No. 2007-069326 discloses a drill in which the rake angle at the tip of the cutting edge is formed at 0°. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-069326 A Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for a cutting tool that can control the shape of chips generated during cutting processing, in order to remove the chips from a workpiece without affecting the processing operation. [Means for solving the problem]

[0005] One aspect of the present invention is a cutting tool that is rotated relative to a workpiece around an axis, and includes a plurality of cutting blade portions spaced apart circumferentially of the cutting tool, each of the plurality of cutting blade portions having a cutting edge extending radially of the cutting tool, the cutting edges 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 is different from the rake angle of the second partial cutting edge. Effect of the Invention

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

[0007] [Figure 1] FIG. 1 is a diagram showing a cutting tool. [Diagram 2] FIG. 2 is a view of the cutting edge of the cutting tool viewed along the axis. [Diagram 3] FIG. 3 is a diagram focusing on one cutting blade portion. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. [Diagram 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a diagram showing the state of the partial cutting edge of the main cutting edge when cutting a workpiece. [Figure 7] FIG. 7 is a diagram showing the state of the partial cutting edge of the minor cutting edge when cutting a workpiece. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] When chips generated by cutting a workpiece are relatively large or long, the chips are difficult to remove from the workpiece. In particular, when a hole is drilled using a drill or the like, the chips are difficult to remove from inside the hole. In this case, the chips tend to become entangled in the workpiece or the cutting tool, resulting in malfunction. The technology disclosed herein aims to provide a cutting tool that can control the shape of the chips while processing.

[0009] As shown in Fig. 1, the cutting tool 10 is, for example, a drill, but is not limited thereto. The cutting tool 10 is fixed to a spindle of a machine tool, a machining center, or the like. In this case, the cutting tool 10 is rotated about an axis AX of the cutting tool 10. Alternatively, the cutting tool 10 may be fixed to a jig, and a workpiece W (see Fig. 6) may be rotated about an axis AX of the cutting tool 10. The cutting tool 10 has a tool body 12 and a plurality of cutting blade portions 14.

[0010] The tool body 12 is rod-shaped. An axis AX of the tool body 12 and an axis AX of the cutting tool 10 are located on the same line. A plurality of cutting blade portions 14 are formed on the tool body 12. As shown in FIG. 2, the plurality of cutting blade portions 14 are arranged at intervals in the circumferential direction D1 of the cutting tool 10. In FIG. 2, the number of cutting blade portions 14 is four, but is not limited to this. Each of the plurality of cutting blade portions 14 has the same configuration.

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

[0012] The main cutting edge 16 and the minor cutting edge 18 are used to cut the workpiece. The main cutting edge 16 is located outside the minor cutting edge 18 in the radial direction D2 (see FIG. 2 ) of the cutting tool 10. The minor cutting edge 18 is located between the axis AX of the cutting tool 10 and the main cutting edge 16. Gash is formed in the minor cutting edge 18. The main cutting edge 16 may have the same hardness as the minor cutting edge 18, or may be harder than the minor cutting edge 18. For example, the main cutting edge 16 is made of diamond, and the minor cutting edge 18 is made of an alloy such as cemented carbide. The main cutting edge 16 may be brazed to the tool body 12.

[0013] The cutting edge 20 extends along a radial direction D2 of the cutting tool 10. The cutting edge 20 cuts the workpiece by relative rotation between the cutting tool 10 and the workpiece W about the axis AX. The cutting edge 20 includes a partial cutting edge 20A of the main cutting edge 16 and a partial cutting edge 20B of the sub cutting edge 18.

[0014] The blade direction grooves 22 are formed on the rake face 14F of the cutting blade portion 14. The blade direction grooves 22 extend along the partial cutting edge 20A. The rake face 14F is a surface through which chips generated by cutting with the cutting edge 20 pass. The blade direction grooves 22 are grooves for mainly controlling the shape of the chips by curling the chips generated by the cutting edge 20.

[0015] In this embodiment, the blade direction groove 22 includes the blade direction groove 22A, the blade direction groove 22B, and the blade direction groove 22C, but is not limited thereto. That is, the blade direction groove 22 may be a single groove or a plurality of grooves. When the blade direction groove 22 includes a plurality of grooves, the plurality of grooves 22 are arranged at intervals in a direction along the axis AX of the cutting tool 10. In this embodiment, the blade direction groove 22A is located closest to the cutting edge 20. The blade direction groove 22B is located farther from the cutting edge 20 than the blade direction groove 22A. The blade direction groove 22C is located farther from the cutting edge 20 than the blade direction groove 22B.

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

[0017] When the partial cutting edge 20A is worn, the main cutting edge 16 is ground from the partial cutting edge 20A to the line Lc1, so that a new partial cutting edge is formed at the location of the line Lc1. In this case, the blade direction groove 22B exerts a function of controlling the shape of the chips generated by the partial cutting edge formed at the location of the line Lc1. Also, when the partial cutting edge formed at the location of the line Lc1 is worn, the main cutting edge 16 is ground from the line Lc1 to the line Lc2, so that a new partial cutting edge is formed at the location of the line Lc2. In this case, the blade direction groove 22C exerts a function of controlling the shape of the chips generated by the partial cutting edge formed at the location of the line Lc2. In other words, when there are a plurality of 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 case of forming a new partial cutting edge.

[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 blade portion 14 (main cutting 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 disposed closer to the partial cutting edge 20A than the second inner portion 22F2. The first inner portion 22F1 has an inclined surface IP1 that is inclined so as to become lower as it approaches the bottom portion 22BT. This allows the first inner portion 22F1 to effectively guide chips generated by the partial cutting edge 20A to the bottom portion 22BT. The inclined surface IP1 may be curved.

[0020] The second inner portion 22F2 is disposed farther from the partial cutting edge 20A than the first inner portion 22F1. The second inner portion 22F2 has an inclined surface IP2 that is inclined so as to become higher as it moves away from the bottom portion 22BT. This makes it easier for the chips generated by the partial cutting edge 20A to curl as they are pushed by the inclined surface IP2, and as a result, it becomes easier to control the shape of the chips. The inclined surface IP2 may be curved.

[0021] As shown in Fig. 5, the cutting direction groove 22 has a first end 22E1 and a second end 22E2. The first end 22E1 is disposed closer to the axis AX of the cutting tool 10 than the second end 22E2. Between the first end 22E1 and the bottom 22BT, an inclined surface IP3 is formed, which is inclined so as to become higher as it moves away from the bottom 22BT. This makes it possible to change the flow of chips generated by the partial cutting edge 20A, and as a result, the chips are easily broken up.

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

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

[0024] In this embodiment, two recesses 24, namely, recesses 24A and recesses 24B, are formed, but the present invention is not limited thereto. That is, the recesses 24 may be singular or plural. When the recesses 24 are plural, the plural recesses 24 are arranged at intervals in the radial direction D2 of the cutting tool 10. In this case, the number of chips cut in the radial direction D2 of the cutting tool 10 can be increased. In addition, the recesses 24 of the plural cutting blades 14 arranged at intervals in the circumferential direction D1 of the cutting tool 10 may be provided at positions shifted in phase with each other. In this case, it is possible to prevent cutting marks from remaining in the processed hole, which is more preferable.

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

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

[0027] When a plurality of cutting direction grooves 22 are formed, cutout portions CO1 and CO2 may be formed at positions corresponding to the chamfered portion CN1. Similarly, cutout portions CO3 and CO4 may be formed at positions corresponding to the chamfered portion CN2.

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

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

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

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

[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 direction groove 22. In addition, one end of the axial groove reaches the tip of the partial cutting edge 20A.

[0033] When the recess 24 is formed as an axial groove, it is the portion of the axial groove that divides the partial cutting edge 20A that performs the function of dividing chips generated by the partial cutting edge 20A. The other portions do not substantially perform the above function. As described above, when a new partial cutting edge is formed at the location of the line Lc1, the portion that divides the newly formed partial cutting edge performs the above function. Also, when a new partial cutting edge is formed at the location of the line Lc2, the portion that divides the newly formed partial cutting edge performs the above function.

[0034] Fig. 6 is a diagram showing a state of the partial cutting edge 20A of the main cutting edge 16 when cutting the workpiece W. Fig. 7 is a diagram showing a state of the partial cutting edge 20B of the auxiliary cutting edge 18 when cutting the workpiece W.

[0035] The rake angle θ1 of the partial cutting edge 20A (FIG. 6) is different from the rake angle θ2 of the partial cutting edge 20B (FIG. 7). This causes the direction in which the chips flow to differ between the partial cutting edge 20A and the partial cutting edge 20B. As a result, the chips are more easily broken up than when the flow directions of the chips are the same between the partial cutting edge 20A and the partial cutting edge 20B.

[0036] The rake angle θ1 is the angle between an imaginary 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 imaginary 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 blade portion 14.

[0037] In this embodiment, the angle θ3 between the rake face F2 of the partial cutting edge 20A and the relief face F3 of the partial cutting edge 20A is an acute angle. In contrast, the angle θ4 between the rake face F4 of the partial cutting edge 20B and the relief face F5 of the partial cutting edge 20B is an obtuse angle. 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, chips are easily broken.

[0038] In addition, the present invention is not limited to the case where the angle θ3 of the partial cutting edge 20A is an acute angle and the angle θ4 of the partial cutting edge 20B is an obtuse angle. For example, as long as the rake angle θ1 of the partial cutting edge 20A and the rake angle θ2 of the partial cutting edge 20B are different, both the angle θ3 of the partial cutting edge 20A and the angle θ4 of the partial cutting edge 20B may be acute angles.

[0039] Regarding the above embodiment, the following supplementary notes are further disclosed.

[0040] (Appendix 1) The present disclosure relates to a cutting tool (10) that rotates relative to a workpiece (W) around an axis (AX), and includes a plurality of cutting blade portions (14) that are spaced apart in a circumferential direction (D1) of the cutting tool, each of which has a cutting edge (20) that extends along a radial direction (D2) of the cutting tool, the cutting edge having 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 is different from the rake angle (θ2) of the second partial cutting edge. This causes the direction in which the chips flow to differ between the first partial cutting edge and the second partial cutting edge. As a result, the chips are more easily broken up than when the direction in which the chips flow is the same between the first partial cutting edge and the second partial cutting edge.

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

[0042] (Appendix 3) In the cutting tool (10) described in Supplementary Note 1 or 2, a cutting edge direction groove (22) extending along the first partial cutting edge is formed on the rake face (14F) of the cutting edge portion, 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 direction groove. This makes it easier to guide chips generated by the first partial cutting edge to the cutting edge direction groove. As a result, the chips are easier to break up in the cutting edge direction groove.

[0043] (Appendix 4) In the cutting tool (10) described in Appendix 3, an inclined surface (IP3) may be formed between the end (22E1) of the cutting direction groove and the bottom of the cutting direction groove. This makes it possible to change the flow of chips generated by the first partial cutting edge, and as a result, the chips are easily broken up.

[0044] (Appendix 5) In the cutting tool (10) described in Appendix 1, a recess (24) is formed on the rake face of the cutting blade portion to divide the first partial cutting edge, one end of a first portion (S2) of the first partial cutting edge and one end of a 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 a corner of one end of the first portion is 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] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

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

Claims

1. A cutting tool that is rotated relative to a workpiece around an axis, A cutting tool includes a plurality of cutting blades arranged at intervals in a circumferential direction of the cutting tool, Each of the plurality of cutting blade portions has a cutting edge extending along a 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, A cutting tool, wherein a rake angle of the first partial cutting edge is different from a rake angle of the second partial cutting edge.

2. 2. The cutting tool according to claim 1, an angle between a rake face of the first partial cutting edge and a relief face of the first partial cutting edge is an acute angle; a cutting tool, wherein an angle between the rake face of the second partial cutting edge and the relief face of the second partial cutting edge is an obtuse angle.

3. 3. The cutting tool according to claim 1 or 2, A cutting edge direction groove extending along the first partial cutting edge is formed on a rake face of the cutting edge portion, A cutting tool, wherein an inclined surface is formed between a rake face of the first partial cutting edge and a bottom of the cutting edge direction groove.

4. 4. The cutting tool according to claim 3, A cutting tool, wherein an inclined surface is formed between an end portion of the cutting direction groove and the bottom portion of the cutting direction groove.

5. 2. The cutting tool according to claim 1, A recess is formed on a rake face of the cutting blade portion to divide the first partial cutting edge, one end of a first portion of the first partial cutting edge and one end of a second portion of the first partial cutting edge face each other via the recess, the second portion is located between the first portion and the axis; A cutting tool, wherein a corner at one end of the first portion is chamfered to form a chamfer on the first partial cutting edge.

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