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 is divided by a first recessed part 24B and a second recessed part 24A located between the first recessed part 24B and an axis AX. A dimension SZ2 in the radial direction D2 of the first recessed part 24B is larger than a dimension SZ1 in the radial direction D2 of the second recessed part 24A.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 to 0°. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-069326 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, so that chips can be removed 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 rotates 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 edge being separated by a first recess and a second recess located between the first recess and the axis, and the radial dimension of the first recess being greater than the radial dimension of the second recess. [Effects 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 explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing a cutting tool. [Figure 2] FIG. 2 is a view of the cutting tool cutting edge taken along the axis. [Figure 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. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a diagram showing a case where three recesses are formed in one cutting blade portion. DETAILED DESCRIPTION OF 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 a hole using a drill or the like, they are difficult to remove from the inside of 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 simultaneously with cutting.

[0009] As shown in FIG. 1 , the cutting tool 10 is, for example, a drill, but is not limited to this. The cutting tool 10 is fixed to a spindle of a machine tool, machining center, or the like. In this case, the cutting tool 10 is rotated around an axis AX of the cutting tool 10. Alternatively, the cutting tool 10 may be fixed to a jig, and a workpiece may be rotated 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. An axis AX of the tool body 12 and an axis AX of the cutting tool 10 are positioned 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 this 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 major cutting edge portion 16, a minor cutting edge portion 18, a cutting edge 20, a cutting direction groove 22, and a recessed portion 24.

[0012] The major cutting edge 16 and the minor cutting edge 18 are used to cut the workpiece. The major cutting edge 16 is located outward of 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 major cutting edge 16. Gash is formed in the minor cutting edge 18. The major 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 major cutting edge 16 is made of diamond, and the minor cutting edge 18 is made of an alloy such as cemented carbide. The major cutting edge 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 when the cutting tool 10 and the workpiece rotate relative to each other about the axis AX. The cutting edge 20 includes a partial cutting edge 20A of the major cutting portion 16 and a partial cutting edge 20B of the minor cutting portion 18.

[0014] The cutting edge direction grooves 22 are formed on the rake face 14F of the cutting edge portion 14. The cutting edge 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 cutting edge direction grooves 22 are grooves that mainly control the shape of the chips by curling the chips generated by the cutting edge 20.

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

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

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

[0018] As shown in Fig. 4, the cutting edge directional 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 (major cutting edge portion 16) and the bottom portion 22BT of the cutting edge directional 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 slopes downward 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 slopes upward as it moves away from the bottom portion 22BT. This allows chips generated by the partial cutting edge 20A to be pushed by the inclined surface IP2 and to curl more easily, making it easier to control the shape of the chips. The inclined surface IP2 may be curved.

[0021] 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. An inclined surface IP3 is formed between the first end 22E1 and the bottom 22BT, and the inclined surface IP3 increases in height as it moves away from the bottom 22BT. This allows the flow of chips generated by the partial cutting edge 20A to be changed, making it easier to break the chips.

[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. Because 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. Note that an inclined surface IP3 may be formed between the second end 22E2 and the bottom portion 22BT. The inclined surface IP3 may also be curved.

[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, recess 24A and recess 24B, are formed. Recess 24A and recess 24B are arranged at an interval in the radial direction D2 of the cutting tool 10. Recess 24A is located closest to the axis AX of the cutting tool 10. Recess 24B is located farther from the axis AX of the cutting tool 10 than recess 24A.

[0025] The dimension SZ2 of the recess 24B in the radial direction D2 is larger than the dimension SZ1 of the recess 24A in the radial direction D2. In other words, the length of the opening surface OF of the recess 24B in the extension direction of the partial cutting edge 20A is longer than the length of the opening surface OF of the recess 24A in the extension direction.

[0026] In this embodiment, the recess 24A and the recess 24B divide the partial cutting edge 20A into a portion S1, a portion S2, and a portion S3. One end of the portion S1 and one end of the portion S2 face each other via the recess 24A. The other end of the portion S2 and one end of the portion S3 face each other via the recess 24B. A corner of one end of the portion S2 is chamfered to form a chamfered portion CN1 on the partial cutting edge 20A. A corner of one end of the 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, notch portions CO1 and CO2 may be formed at positions corresponding to the chamfered portion CN1. Similarly, notch 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 edge directional groove 22A and the cutting edge directional groove 22B. The notch portion CO1 is formed at a position 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 a chamfered portion.

[0029] The notch portion CO2 is formed on the rake face 14F between the cutting edge directional groove 22B and the cutting edge directional groove 22C. The notch portion CO2 is formed at a position located along the axis AX relative 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 edge directional groove 22A and the cutting edge directional groove 22B. The notch portion CO3 is formed at a position located along the axis AX relative 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 edge directional groove 22B and the cutting edge directional groove 22C. The notch portion CO4 is formed at a position located along the axis AX relative 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. 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 separates the partial cutting edge 20A that performs the function of separating chips generated by the partial cutting edge 20A. Portions other than this portion do 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 separates the newly formed partial cutting edge performs the above function. Furthermore, when a new partial cutting edge is formed at the location of line Lc2, the portion that separates the newly formed partial cutting edge performs the above function.

[0034] In the above-described cutting tool 10, when the workpiece and cutting tool 10 rotate relative to each other about the axis AX, the movement speed of the recess 24B tends to be faster than the movement speed of the recess 24A. This tendency becomes more pronounced as the diameter of the cutting tool 10 increases. When the difference in the movement speed of the recess 24B relative to the recess 24A increases, chips tend to extend along the axis AX without being broken up in the radial direction D2 of the cutting tool 10 at the recess 24B.

[0035] In this regard, in the present embodiment, the dimension SZ2 of the recess 24B in the radial direction D2 is larger than the dimension SZ1 of the recess 24A in the radial direction D2. Therefore, even if the movement speed of the recess 24B is faster than the movement speed of the recess 24A, the recess 24B can effectively shred the chips in the radial direction D2 of the cutting tool 10. Thus, according to the present embodiment, even if there is a difference in movement speed between the axial side and the outer periphery side of the cutting tool 10, the chips can be effectively shredded.

[0036] As shown in FIG. 6, a recess 24C may be further formed between the recess 24A and the recess 24B. In this case, the radial dimension SZ3 of the recess 24C is smaller than the radial dimension SZ2 of the recess 24B and larger than the radial dimension SZ1 of the recess 24A. This increases the number of chips broken in the radial direction D2 of the cutting tool 10. The number of recesses 24C formed between the recess 24A and the recess 24B is not limited to one. When there are multiple recesses 24C formed between the recess 24A and the recess 24B, the multiple recesses 24C are arranged at intervals in the radial direction D2 of the cutting tool 10. In this case, the radial dimension SZ3 of the recess 24C increases as the recess 24C is positioned farther from the axis AX of the cutting tool 10.

[0037] The following additional notes are further disclosed regarding the above embodiment.

[0038] (Appendix 1) The present disclosure provides a cutting tool (10) that rotates around an axis (AX) and includes a plurality of cutting blade portions (14) spaced apart in a circumferential direction (D1) of the cutting tool, each of the plurality of cutting blade portions having a cutting edge (20) extending along a radial direction (D2) of the cutting tool, the cutting edge (20) being separated by a first recess (24B) and a second recess (24A) located between the first recess and the axis, and the radial dimension (SZ2) of the first recess is larger than the radial dimension (SZ1) of the second recess. This allows for good shredding even when there is a difference in moving speed between the axis and the outer periphery of the cutting tool (10).

[0039] (Appendix 2) In the cutting tool (10) described in Appendix 1, the cutting edge may be further divided by a third recess (24C) located between the first recess and the second recess, and the radial dimension (SZ3) of the third recess may be smaller than the radial dimension of the first recess and larger than the radial dimension of the second recess. This allows the number of chips divided in the radial direction D2 of the cutting tool 10 to be increased.

[0040] (Appendix 3) In the cutting tool (10) described in Supplementary Note 2, the number of the third recessed portions may be plural, and the dimension of the third recessed portion in the radial direction may be larger as the third recessed portion is disposed at a position farther from the axis center. This allows the number of chips broken in the radial direction D2 of the cutting tool 10 to be increased.

[0041] (Appendix 4) In the cutting tool (10) described in Appendix 1, one end of a first portion (S2 (or S3)) of the cutting edge and one end of a second portion (S1 (or S2)) of the cutting edge (20) face each other via the first recess (24B) or the second recess (24A), the second portion (S1 (or S2)) is located between the first portion (S2 (or S3)) and the axis (AX), and a corner of one end of the first portion (S2 (or S3)) is chamfered to form a chamfered portion (CN1 (or CN2)) on the cutting edge. This makes it possible to avoid stress concentration on the cutting edge.

[0042] 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]

[0043] 10...Cutting tool 12...Tool body 14...Cutting blade part 16...Main blade part 18... Sub cutting edge 20... Cutting edge 24, 24A, 24B, 24C...recesses AX…Axis center CN1, CN2…Chamfered portion D1…Circumferential direction D2…Radial direction SZ1, SZ2, SZ3...Dimensions

Claims

1. A cutting tool that is rotated around an axis, a plurality of cutting blade portions arranged at intervals in the 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 is divided by a first recess and a second recess located between the first recess and the axis, a dimension of the first recess in the radial direction is larger than a dimension of the second recess in the radial direction; one end of a first portion of the cutting edge and one end of a second portion of the cutting edge face each other via the first recess or the second 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 at a tip end of the first portion; A cutting tool, wherein the chamfered portion is formed so as to straddle a side surface extending along the axis of the first recess or the second recess and the cutting edge, and to be inclined with respect to the side surface and the cutting edge.

2. 2. The cutting tool according to claim 1, The cutting edge is further divided by a third recess located between the first recess and the second recess, A cutting tool, wherein a dimension of the third recess in the radial direction is smaller than a dimension of the first recess in the radial direction and larger than a dimension of the second recess in the radial direction.

3. 3. The cutting tool according to claim 2, the number of the third recesses is plural, A cutting tool, wherein the radial dimension of the third recess increases as the third recess is disposed farther from the axis center.

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