Drill head, tip-interchangeable drill, and drill
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2025-02-05
- Publication Date
- 2026-08-13
Smart Images
Figure JP2025003737_13082026_PF_FP_ABST
Abstract
Description
Drill head, tip-exchangeable drill, and drill
[0001] The present disclosure relates to a drill head, a tip-exchangeable drill, and a drill.
[0002] WO 2022 / 201298 (Patent Document 1) describes a drill. The drill described in Patent Document 1 has a main cutting edge and a thinning cutting edge. The thinning cutting edge extends linearly.
[0003] WO 2022 / 201298
[0004] The drill according to the present disclosure is a drill that rotates around a central axis, and includes a tip and a rear end that are ends in a direction along the central axis, a tip surface at the tip, an outer peripheral surface continuous with the tip surface, a cutting edge extending from the outer peripheral surface toward the central axis on the tip surface, a flute surface formed on the outer peripheral surface and extending around the central axis from the tip surface toward the rear end, and a thinning surface continuous with the tip surface and the flute surface. The tip surface has a first relief surface continuous with the cutting edge and a second relief surface on the opposite side of the first relief surface across the flute surface. The thinning surface has a thinning rake surface continuous with the first relief surface and a thinning heel surface continuous with the second relief surface. The thinning rake surface has a first thinning rake surface portion continuous with the thinning heel surface, a second thinning rake surface portion continuous with the flute surface, and a third thinning rake surface portion connecting the first thinning rake surface portion and the second thinning rake surface portion. The cutting edge has a main cutting edge portion, a first thinning cutting edge portion, a second thinning cutting edge portion, and a third thinning cutting edge portion. The main cutting edge portion is continuous with the outer peripheral surface and is formed by a ridge line between the first relief surface and the flute surface. The first thinning cutting edge portion is linear and is formed by a ridge line between the first thinning rake surface portion and the first relief surface. The second thinning cutting edge portion is linear and is formed by a ridge line between the second thinning rake surface portion and the first relief surface. The third thinning cutting edge portion is curved, is located between the first thinning cutting edge portion and the second thinning cutting edge portion, and is formed by a ridge line between the third thinning rake surface portion and the first relief surface.
[0005] Figure 1 is a schematic perspective view showing the configuration of a drill according to the first embodiment. Figure 2 is a schematic perspective view showing the configuration of a drill head. Figure 3 is a schematic front view showing the configuration of a drill head. Figure 4 is a schematic rear view showing the configuration of a drill head. Figure 5 is a schematic front view showing an example of the configuration of a cutting edge. Figure 6 is a schematic front view showing another example of the configuration of a cutting edge. Figure 7 is a schematic cross-sectional view showing the axial rake angle of the first thinning rake face. Figure 8 is a schematic cross-sectional view showing the axial rake angle of the second thinning rake face. Figure 9 is a schematic cross-sectional view showing the axial rake angle of the flute face. Figure 10 is a schematic perspective view showing the configuration of a holder. Figure 11 is a schematic perspective view showing the overall configuration of a drill according to the second embodiment. Figure 12 is an enlarged schematic perspective view showing a part of the configuration of a drill according to the second embodiment.
[0006] [Description of Embodiments of the Disclosure] First, embodiments of the disclosure will be listed and described.
[0007] (1) The drill according to the present disclosure is a drill that rotates around a central axis and comprises a tip and a rear end which are ends in a direction along the central axis, a tip surface at the tip, an outer circumferential surface connected to the tip surface, a cutting edge extending from the outer circumferential surface toward the central axis at the tip surface, a flute surface formed on the outer circumferential surface and extending around the central axis toward the rear end from the tip surface, and a thinning surface connected to the tip surface and the flute surface. The tip surface has a first relief surface portion connected to the cutting edge and a second relief surface portion on the opposite side of the first relief surface portion with the flute surface in between. The thinning surface has a thinning rake surface connected to the first relief surface portion and a thinning heel surface connected to the second relief surface portion. The thinning rake face has a first thinning rake face portion connected to the thinning heel surface, a second thinning rake face portion connected to the flute surface, and a third thinning rake face portion connecting the first thinning rake face portion and the second thinning rake face portion. The cutting edge has a main cutting edge portion, a first thinning cutting edge portion, a second thinning cutting edge portion, and a third thinning cutting edge portion. The main cutting edge portion is connected to the outer circumferential surface and is formed by the ridge line between the first relief surface portion and the flute surface. The first thinning cutting edge portion is linear and is formed by the ridge line between the first thinning rake face portion and the first relief surface portion. The second thinning cutting edge portion is linear and is formed by the ridge line between the second thinning rake face portion and the first relief surface portion. The third thinning cutting edge is curved, located between the first thinning cutting edge and the second thinning cutting edge, and is formed by the ridge line between the third thinning rake face and the first relief face.
[0008] (2) In the case of the drill according to (1) above, the axial rake angle of the first thinning rake face and the second thinning rake face may be -7° or more and 7° or less.
[0009] (3) In the case of the drill according to (1) or (2) above, when the tip surface is viewed along the central axis, the amount of recess of the main cutting edge with respect to the imaginary straight line connecting the connection point between the main cutting edge and the outer surface and the connection point between the second thinning cutting edge and the main cutting edge may be -0.01 times or more and 0.02 times or less of the diameter of the cutting edge.
[0010] (4) In the case of the drill according to (1) or (2) above, when the tip surface is viewed along the central axis, the distance between the imaginary straight line extending the second thinning cutting edge toward the outer surface and the outer endpoint of the main cutting edge may be 0.01 times or less the diameter of the cutting edge.
[0011] (5) In the drill according to (1) or (2) above, the main cutting edge portion may have a first main cutting edge region and a second main cutting edge region located on the opposite side of the first main cutting edge region with respect to the central axis. The first thinning cutting edge portion may have a first thinning cutting edge region located between the first main cutting edge region and the central axis and a second thinning cutting edge region located between the second main cutting edge region and the central axis. When the tip surface is viewed along the central axis, the angle between the direction extending outward along the first thinning cutting edge region and the direction from the central axis toward the outer endpoint of the second main cutting edge region may be 141° or more and 155° or less.
[0012] (6) In the case of the drill according to (1) or (2) above, the value obtained by dividing the length of the first thinning cutting edge by the sum of the length of the main cutting edge and the length of the second thinning cutting edge may be 0.19 or more and 0.25 or less.
[0013] (7) The drill head according to the present disclosure is a drill head that rotates around a central axis and comprises a mounting surface which is an end face in the direction along the central axis, a tip surface which is the opposite surface of the mounting surface in the direction along the central axis, an outer circumferential surface connected to the mounting surface and the tip surface, a cutting edge which extends from the outer circumferential surface toward the central axis on the tip surface, a flute surface which is formed on the outer circumferential surface and extends around the central axis toward the mounting surface from the tip surface, and a thinning surface which is connected to the tip surface and the flute surface. The tip surface has a first relief surface which is connected to the cutting edge, and a second relief surface which is on the opposite side of the first relief surface which is separated by the flute surface. The thinning surface has a thinning rake surface which is connected to the first relief surface which is connected to the second relief surface which is connected to the second relief surface. The thinning rake face has a first thinning rake face portion connected to the thinning heel surface, a second thinning rake face portion connected to the flute surface, and a third thinning rake face portion connecting the first thinning rake face portion and the second thinning rake face portion. The cutting edge has a main cutting edge portion, a first thinning cutting edge portion, a second thinning cutting edge portion, and a third thinning cutting edge portion. The main cutting edge portion is connected to the outer circumferential surface and is formed by the ridge line between the first relief surface portion and the flute surface. The first thinning cutting edge portion is linear and is formed by the ridge line between the first thinning rake face portion and the first relief surface portion. The second thinning cutting edge portion is linear and is formed by the ridge line between the second thinning rake face portion and the first relief surface portion. The third thinning cutting edge is curved, located between the first thinning cutting edge and the second thinning cutting edge, and is formed by the ridge line between the third thinning rake face and the first relief face.
[0014] (8) The interchangeable tip drill according to the present disclosure comprises the drill head described in (7) above and a holder attached to a mounting surface.
[0015] [Details of Embodiments of the Disclosure] Details of embodiments of the disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals, and redundant descriptions will not be repeated.
[0016] (First Embodiment) First, the configuration of the drill according to the first embodiment will be described. The drill according to the first embodiment is a drill with a replaceable tip.
[0017] Figure 1 is a schematic perspective view showing the configuration of a drill according to the first embodiment. As shown in Figure 1, the drill 100 according to the first embodiment rotates around a central axis A. The drill 100 has a tip 101 and a rear end 102. The tip 101 and the rear end 102 are the ends of the drill 100 in the direction of the central axis A. The rear end 102 is on the opposite side of the tip 101 in the direction of the central axis A.
[0018] The drill 100 includes a drill head 10, a holder 20, and a fixing member 30. The drill head 10 forms the tip 101 of the drill 100. The holder 20 forms the rear end 102 of the drill 100. The drill head 10 is attached to the holder 20 using the fixing member 30.
[0019] <Drill Head Structure> Figure 2 is a schematic perspective view showing the structure of the drill head 10. The drill head 10 is made of, for example, cemented carbide. The drill head 10 rotates around a central axis A. As shown in Figure 2, the drill head 10 has a cutting edge 1, a mounting surface 12, a tip surface 11, an outer peripheral surface 5, a flute surface 4, and a thinning surface 40.
[0020] The mounting surface 12 is the surface facing the holder 20. The mounting surface 12 is the end face in the direction along the central axis A of the drill head 10. The tip surface 11 is the opposite surface of the mounting surface 12 in the direction along the central axis A. The outer peripheral surface 5 is connected to the mounting surface 12 and the tip surface 11. The flute surface 4 is formed on the outer peripheral surface 5. The flute surface 4 extends spirally around the central axis A from the tip surface 11 toward the mounting surface 12. The thinning surface 40 is connected to the tip surface 11 and the flute surface 4.
[0021] The tip surface 11 has a first relief surface 51 and a second relief surface 52. The first relief surface 51 is connected to the cutting edge 1. The second relief surface 52 is on the opposite side of the flute surface 4 from the first relief surface 51. In the rotational direction of the drill 100, the flute surface 4 is located between the first relief surface 51 and the second relief surface 52. The first relief surface 51 and the second relief surface 52 may be composed of a single conical surface. A step may be provided between the first relief surface 51 and the second relief surface 52.
[0022] The thinning surface 40 has a thinning rake surface 44 and a thinning heel surface 45. The thinning rake surface 44 is connected to the first relief surface 51. The thinning heel surface 45 is connected to the second relief surface 52. The thinning rake surface 44 and the thinning heel surface 45 are connected to the flute surface 4.
[0023] The thinning rake face 44 has a first thinning rake face portion 41, a second thinning rake face portion 42, and a third thinning rake face portion 43. The first thinning rake face portion 41 is connected to the thinning heel surface 45 and the third thinning rake face portion 43. The first thinning rake face portion 41 is located between the thinning heel surface 45 and the third thinning rake face portion 43. The first thinning rake face portion 41 is spaced apart from the flute surface 4. The first thinning rake face portion 41 is spaced apart from the second thinning rake face portion 42.
[0024] The second thinning rake face portion 42 is connected to the flute surface 4 and the third thinning rake face portion 43. The second thinning rake face portion 42 is located between the flute surface 4 and the third thinning rake face portion 43. The second thinning rake face portion 42 is spaced apart from the thinning heel surface 45.
[0025] The third thinning rake face portion 43 is connected to the first thinning rake face portion 41, the second thinning rake face portion 42, the flute surface 4, and the thinning heel surface 45. The third thinning rake face portion 43 connects the first thinning rake face portion 41 and the second thinning rake face portion 42. The third thinning rake face portion 43 connects the second thinning rake face portion 42 and the thinning heel surface 45.
[0026] Figure 3 is a schematic front view showing the configuration of the drill head 10. The schematic front view shown in Figure 3 is a view of the tip surface 11 of the drill head 10 along the central axis A. As shown in Figure 3, the cutting edge 1 extends from the outer circumferential surface 5 toward the central axis A on the tip surface 11. The cutting edge 1 has a main cutting edge portion 65, a thinning cutting edge portion 64, and a chisel edge 66. The main cutting edge portion 65 is connected to the outer circumferential surface 5.
[0027] As shown in Figure 3, the thinning cutting edge portion 64 has a first thinning cutting edge portion 61, a second thinning cutting edge portion 62, and a third thinning cutting edge portion 63. The first thinning cutting edge portion 61 is straight. The first thinning cutting edge portion 61 is connected to the chisel edge 66. The second thinning cutting edge portion 62 is straight. The second thinning cutting edge portion 62 is connected to the main cutting edge portion 65.
[0028] As shown in Figure 3, the third thinning cutting edge portion 63 is curved. The third thinning cutting edge portion 63 has a convex shape outward. The third thinning cutting edge portion 63 is connected to the first thinning cutting edge portion 61 and the second thinning cutting edge portion 62. The third thinning cutting edge portion 63 is located between the first thinning cutting edge portion 61 and the second thinning cutting edge portion 62.
[0029] As shown in Figure 2, the main cutting edge portion 65 is formed by the ridge line between the first relief surface portion 51 and the flute surface 4. The first thinning cutting edge portion 61 is formed by the ridge line between the first thinning rake surface portion 41 and the first relief surface portion 51. The second thinning cutting edge portion 62 is formed by the ridge line between the second thinning rake surface portion 42 and the first relief surface portion 51. The third thinning cutting edge portion 63 is formed by the ridge line between the third thinning rake surface portion 43 and the first relief surface portion 51.
[0030] As shown in Figure 2, the point where the first thinning rake face portion 41, the third thinning rake face portion 43, and the thinning heel surface 45 meet is defined as the first triple point T1. The point where the second thinning rake face portion 42, the third thinning rake face portion 43, and the flute surface 4 meet is defined as the second triple point T2. The point where the third thinning rake face portion 43, the flute surface 4, and the thinning heel surface 45 meet is defined as the third triple point T3. In the direction along the central axis A, the second triple point T2 may be located between the first triple point T1 and the third triple point T3.
[0031] As shown in Figure 3, the main cutting edge portion 65 has a first main cutting edge region 65a and a second main cutting edge region 65b. The second main cutting edge region 65b is on the opposite side of the first main cutting edge region 65a with respect to the central axis A. The central axis A is located between the first main cutting edge region 65a and the second main cutting edge region 65b. The first main cutting edge region 65a and the second main cutting edge region 65b are positioned symmetrically twice with respect to the central axis A as the center of rotation. The distance between the outer endpoint of the first main cutting edge region 65a and the outer endpoint of the second main cutting edge region 65b is the diameter D of the cutting edge 1.
[0032] The first thinning cutting edge portion 61 has a first thinning cutting edge region 61a and a second thinning cutting edge region 61b. The first thinning cutting edge region 61a is located between the first main cutting edge region 65a and the central axis A. The second thinning cutting edge region 61b is located between the second main cutting edge region 65b and the central axis. The first thinning cutting edge region 61a and the second thinning cutting edge region 61b are located in positions that are symmetrical twice with respect to the central axis A as the center of rotation.
[0033] As shown in Figure 3, when the tip surface 11 is viewed along the central axis A, the direction extending outward along the first thinning cutting edge region 61a is defined as the first direction L1. When the tip surface 11 is viewed along the central axis A, the direction from the central axis A toward the outer endpoint of the second main cutting edge region 65b is defined as the second direction L2. The angle between the first direction L1 and the second direction L2 is defined as the thinning angle θ3. The thinning angle θ3 is, for example, 141° or more and 155° or less. The thinning angle θ3 may also be 143° or more and 153° or less, or 145° or more and 151° or less.
[0034] As shown in Figure 3, the drill head 10 is provided with a mounting hole 3. The mounting hole 3 is located at the boundary between the second relief surface 52 and the thinning heel surface 45. The mounting hole 3 opens into both the second relief surface 52 and the thinning heel surface 45.
[0035] Figure 4 is a schematic rear view showing the configuration of the drill head 10. As shown in Figure 4, the mounting surface 12 of the drill head 10 is provided with a plurality of grooves 15. Each of the plurality of grooves 15 extends from the outer peripheral surface 5 toward the central axis A. The mounting hole 3 penetrates from the tip surface 11 of the drill head 10 to the mounting surface 12. The mounting hole 3 opens into the mounting surface 12.
[0036] Figure 5 is a schematic front view showing an example of the configuration of the cutting edge 1. In Figure 5, the direction approximately perpendicular to the main cutting edge portion 65 is shown in a larger view than the direction approximately parallel to the main cutting edge portion 65.
[0037] As shown in Figure 5, when the tip surface 11 is viewed along the central axis A, the imaginary straight line extending the second thinning cutting edge portion 62 toward the outer circumferential surface 5 is defined as the first imaginary straight line B1. When the tip surface 11 is viewed along the central axis A, the first imaginary straight line B1 may be located forward in the rotational direction from the outer endpoint 71 of the main cutting edge portion 65. The outer endpoint 71 of the main cutting edge portion 65 is the connection point between the main cutting edge portion 65 and the outer circumferential surface 5.
[0038] When the tip surface 11 is viewed along the central axis A, the distance between the first virtual line B1 and the outer endpoint 71 of the main cutting edge portion 65 is defined as the first distance E. The first distance E may be 0.01 times or less the diameter D of the cutting edge 1. The first distance E may be 0.008 times or less the diameter D of the cutting edge 1, or 0.006 times or less. The first distance E is not particularly limited, but may be 0.001 times or more the diameter D of the cutting edge 1.
[0039] As shown in Figure 5, the cutting edge 1 has a second connection point 72, a third connection point 73, a fourth connection point 74, and a fifth connection point 75. The second connection point 72 is the connection point between the main cutting edge portion 65 and the second thinning cutting edge portion 62. The third connection point 73 is the connection point between the second thinning cutting edge portion 62 and the third thinning cutting edge portion 63. The fourth connection point 74 is the connection point between the third thinning cutting edge portion 63 and the first thinning cutting edge portion 61. The fifth connection point 75 is the connection point between the first thinning cutting edge portion 61 and the chisel edge 66.
[0040] The length of the first thinning cutting edge portion 61 is defined as the first length C1. The first length C1 is the distance between the fourth connection point 74 and the fifth connection point 75. The length of the second thinning cutting edge portion 62 is defined as the second length C2. The second length C2 is the distance between the second connection point 72 and the third connection point 73. The length of the main cutting edge portion 65 is defined as the third length C3. The third length C3 is the distance between the outer endpoint 71 of the main cutting edge portion 65 and the second connection point 72 in the direction along the first virtual straight line B1.
[0041] The value obtained by dividing the first length C1 by the sum of the third length C3 and the second length C2 may be between 0.19 and 0.25. The value obtained by dividing the first length C1 by the sum of the third length C3 and the second length C2 may be between 0.195 and 0.245, or between 0.20 and 0.24.
[0042] As shown in FIG. 5, the third thinning cutting edge portion 63 has, for example, an arc shape. The radius of curvature R of the third thinning cutting edge portion 63 is, for example, 0.15 times the diameter D of the cutting edge 1. The radius of curvature R of the third thinning cutting edge portion 63 may be, for example, 0.08 times or more and 0.20 times or less the diameter D of the cutting edge 1, or may be 0.12 times or more and 0.18 times or less the diameter D of the cutting edge 1.
[0043] FIG. 6 is a front schematic view showing another example of the configuration of the cutting edge 1. In FIG. 6, the direction substantially perpendicular to the main cutting edge portion 65 is shown enlarged compared to the direction substantially parallel to the main cutting edge portion 65.
[0044] As shown in FIG. 6, when the tip surface 11 is viewed along the central axis A, the virtual straight line connecting the connection point (outer end point 71) between the main cutting edge portion 65 and the outer peripheral surface 5 and the connection point (second connection point 72) between the second thinning cutting edge portion 62 and the main cutting edge portion 65 is the second virtual straight line B2. When the tip surface 11 is viewed along the central axis A, the recess amount F of the main cutting edge portion 65 with respect to the second virtual straight line B2 may be -0.01 times or more and 0.02 times or less the diameter of the cutting edge 1.
[0045] Note that, as shown by the solid line in FIG. 6, when the main cutting edge portion 65 is curved toward the rear in the rotation direction, the recess amount F is taken as positive. On the contrary, as shown by the dashed-dotted line in FIG. 6, when the main cutting edge portion 65 is curved toward the front in the rotation direction, the recess amount F is taken as negative.
[0046] FIG. 7 is a cross-sectional schematic view showing the axial rake angle of the first thinning rake face 41. The cross-sectional schematic view shown in FIG. 7 is a cross-section perpendicular to the first thinning cutting edge portion 61 and parallel to the central axis A. As shown in FIG. 7, the axial rake angle of the first thinning rake face 41 may be, for example, positive. The axial rake angle of the first thinning rake face 41 is the first rake angle θ1. The first rake angle θ1 is the angle formed by the straight line A1 parallel to the central axis A and the first thinning rake face 41. The first rake angle θ1 may be, for example, -7° or more and 7° or less, or -5° or more and 5° or less, or -3° or more and 3° or less.
[0047] FIG. 8 is a schematic cross-sectional view showing the axial rake angle of the second thinning scooping surface 42. The schematic cross-sectional view shown in FIG. 8 is a cross-section perpendicular to the second thinning cutting edge portion 62 and parallel to the central axis A. As shown in FIG. 8, the axial rake angle of the second thinning scooping surface 42 may be positive, for example. The axial rake angle of the second thinning scooping surface 42 is defined as the second rake angle θ2. The second rake angle θ2 is the angle formed by a straight line A1 parallel to the central axis A and the second thinning scooping surface 42. The second rake angle θ2 may be, for example, not less than -7° and not more than 7°, or not less than -5° and not more than 5°, or not less than -3° and not more than 3°.
[0048] FIG. 9 is a schematic cross-sectional view showing the axial rake angle of the flute surface 4. The schematic cross-sectional view shown in FIG. 9 is a cross-section perpendicular to the tangent line of the main cutting edge portion 65 and parallel to the central axis A. As shown in FIG. 9, the axial rake angle of the flute surface 4 may be positive, for example. The axial rake angle of the flute surface 4 is defined as the fourth rake angle θ4. The fourth rake angle θ4 is the angle formed by a straight line A1 parallel to the central axis A and the flute surface 4. The fourth rake angle θ4 may be larger than the first rake angle θ1. The fourth rake angle θ4 may be larger than the second rake angle θ2.
[0049] <Configuration of Holder>FIG. 10 is a perspective schematic view showing the configuration of the holder 20. As shown in FIG. 10, the holder 20 has a front end surface 21, a rear end surface 22, a holder outer peripheral surface 23, and a holder flute surface 24. The holder 20 extends along the central axis A2. In the direction in which the central axis A2 extends, the front end surface 21 is located opposite to the rear end surface 22. The holder outer peripheral surface 23 is continuous with the front end surface 21. The holder flute surface 24 is provided spirally around the central axis A2. The central axis A2 of the holder 20 coincides with the central axis A of the drill head 10.
[0050] Multiple protrusions 25 are formed on the front end surface 21, extending from the center of the front end surface 21 to the outer circumferential surface 5. The front end surface 21 of the holder 20 is positioned to face the mounting surface 12 of the drill head 10. Multiple grooves 15 formed on the mounting surface 12 of the drill head 10 are fitted into the multiple protrusions 25 formed on the front end surface 21 of the holder 20. As described above, the holder 20 is attached to the mounting surface 12 of the drill head 10.
[0051] (Second Embodiment) Next, the configuration of the drill 100 according to the second embodiment will be described. The drill 100 according to the second embodiment is a solid type drill 100. The drill 100 according to the second embodiment differs from the drill 100 according to the first embodiment in that it is not a replaceable tip type, but the other configurations are substantially the same as those of the drill 100 according to the first embodiment.
[0052] Figure 11 is a schematic perspective view showing the overall configuration of the drill 100 according to the second embodiment. Figure 12 is an enlarged schematic perspective view showing a part of the configuration of the drill 100 according to the second embodiment.
[0053] As shown in Figures 11 and 12, the drill 100 according to the second embodiment is rotated around a central axis A. The drill 100 has a tip surface 11, an outer circumferential surface 5, a flute surface 4, and a thinning surface 40. The tip surface 11 is located at the tip 101 of the drill 100. The outer circumferential surface 5 is connected to the tip surface 11. The flute surface 4 is formed on the outer circumferential surface 5. The flute surface 4 extends from the tip surface 11 toward the rear end 102 around the central axis A. The thinning surface 40 is connected to the tip surface 11 and the flute surface 4.
[0054] The drill 100 has a cutting edge 1. The cutting edge 1 extends from the outer circumferential surface 5 toward the central axis A on the tip surface 11. The tip surface 11 has a first relief surface 51 connected to the cutting edge 1 and a second relief surface 52 on the opposite side of the first relief surface 51, with the flute surface 4 in between. The thinning surface 40 has a thinning rake surface 44 connected to the first relief surface 51 and a thinning heel surface 45 connected to the second relief surface 52. The configuration of the tip surface 11, outer circumferential surface 5, flute surface 4, thinning surface 40, and cutting edge 1 is substantially the same as that of the drill 100 according to the first embodiment.
[0055] The effects of the drill 100 and drill head 10 according to this embodiment will be described below.
[0056] According to the drill 100 and drill head 10 of this embodiment, the thinning cutting edge portion 64 has a straight first thinning cutting edge portion 61, a straight second thinning cutting edge portion 62, and a curved third thinning cutting edge portion 63. This allows the length of the main cutting edge portion 65 to be longer than the length of the first thinning cutting edge portion 61, compared to the case where the thinning cutting edge portion 64 is a single straight cutting edge. Therefore, when the chips cut by the first thinning cutting edge portion 61 are discharged to the outer circumference, the chips are discharged linearly along the main cutting edge portion 65 by centrifugal force. As a result, the chips are more easily broken up by centrifugal force. Consequently, the ability to break up chips can be improved.
[0057] According to the drill 100 and drill head 10 of this embodiment, when the tip surface 11 is viewed along the central axis A, the amount of recess F of the main cutting edge portion 65 with respect to a virtual straight line connecting the connection point between the main cutting edge portion 65 and the outer peripheral surface 5 and the connection point between the second thinning cutting edge portion 62 and the main cutting edge portion 65 may be -0.01 times or more and 0.02 times or less of the diameter of the cutting edge 1. As a result, the main cutting edge portion 65 becomes substantially straight. Consequently, chips are less likely to get caught in the main cutting edge portion 65. Therefore, since chips are discharged linearly outward, the chip breaking ability can be further improved.
[0058] According to the drill 100 and drill head 10 of this embodiment, when the tip surface 11 is viewed along the central axis A, the distance between the imaginary straight line extending the second thinning cutting edge portion 62 toward the outer peripheral surface 5 and the outer endpoint 71 of the main cutting edge portion 65 may be 0.01 times or less the diameter of the cutting edge 1. As a result, the step difference between the main cutting edge portion 65 and the second thinning cutting edge portion 62 is reduced, and the chips are discharged outward in a more linear fashion. Consequently, the chip breaking performance can be further improved.
[0059] According to the drill 100 and drill head 10 of this embodiment, when the tip surface 11 is viewed along the central axis A, the angle between the direction extending outward along the first thinning cutting edge region 61a and the direction toward the outer endpoint 71 of the second main cutting edge region 65b from the central axis A may be 141° or more and 155° or less. This makes it possible to make the length of the main cutting edge portion 65 even longer than the length of the first thinning cutting edge portion 61. As a result, the chip breaking performance can be further improved.
[0060] According to the drill 100 and drill head 10 of this embodiment, the value obtained by dividing the length of the first thinning cutting edge portion 61 by the sum of the lengths of the main cutting edge portion 65 and the second thinning cutting edge portion 62 may be 0.19 or more and 0.25 or less. This makes it possible to relatively increase the length of the main cutting edge portion 65 and the length of the second thinning cutting edge portion 62. As a result, the chip breaking performance can be further improved.
[0061] <Sample Preparation> First, drills 100 for Sample 1 to Sample 3 were prepared. The diameter D of the cutting edge 1 is 18 mm. Drill 100 for Sample 1 is the drill 100 described in Patent Document 1. Specifically, in drill 100 for Sample 1, the thinning cutting edge portion 64 is a single straight cutting edge. The thinning angle θ3 in drill 100 for Sample 1 was 160°. Drill 100 for Sample 2 applies the X-thinning shape to drill 100 for Sample 1. Specifically, when viewed in the direction along the central axis A, the ridge line between the thinning heel surface 45 and the second relief surface portion 52 is straight.
[0062] The drill 100 of Sample 3 is the drill 100 according to the first embodiment. As shown in Figure 2, in the drill 100 of Sample 3, the thinning cutting edge portion 64 had a straight first thinning cutting edge portion 61, a straight second thinning cutting edge portion 62, and a curved third thinning cutting edge portion 63. The length of the first thinning cutting edge portion 61 was 1.487 mm. The length of the second thinning cutting edge portion 62 was 1.607 mm. The length of the main cutting edge portion 65 was 5.178 mm. The value obtained by dividing the length of the first thinning cutting edge portion 61 by the sum of the lengths of the main cutting edge portion 65 and the second thinning cutting edge portion 62 was approximately 0.22. The radius of curvature of the third thinning cutting edge portion 63 was 0.15 times the diameter of the cutting edge 1. The thinning angle θ3 in the drill 100 of Sample 1 was 149.5°.
[0063] <Cutting Test Method> Drilling was performed on the workpiece using drills 100 from Sample 1 to Sample 3. The equipment used was a machining center (model number HSK-A63) manufactured by DGM Mori Seiki Co., Ltd. The workpiece was rolled steel (JIS SS400). The cutting speed (Vc) was set to 80 m / min. The feed rate (f) was set to 0.20 mm / revolution. The length of the through hole (H) was set to 100 mm. A water-soluble internal lubrication system was used. The chips generated when machining the three holes were collected, and the chip fragmentation rate was determined.
[0064] Of the recovered chips, three types with different generation mechanisms were excluded. Specifically, inlet chips, disc-shaped chips, and exit chips were excluded. Inlet chips are characterized by having more than five helices in a series. Exit chips are characterized by a looser and thinner helical twist at the trailing end of the chip, with the length of this section being more than five times the length of the curled section. The chip fragmentation rate was defined as the mass of the fragmented chips divided by the total mass of the fragmented and unfragmented chips.
[0065] <Cutting test results>
[0066]
[0067] As shown in Table 1, the chip fragmentation rates of drill 100 for samples 1, 2, and 3 were 63%, 70%, and 96%, respectively. It was experimentally confirmed that the chip fragmentation rate is improved in the drill 100 of this embodiment.
[0068] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the embodiments described above, and all modifications within the meaning and scope of the claims are intended to be included.
[0069] 1 Cutting edge, 3 Mounting hole, 4 Flute surface, 5 Outer circumference surface, 10 Drill head, 11 Tip surface, 12 Mounting surface, 15 Groove, 20 Holder, 21 Front end surface, 22 Rear end surface, 23 Holder outer circumference surface, 24 Holder flute surface, 25 Protruding ridge, 30 Fixing member, 40 Thinning surface, 41 First thinning rake surface, 42 Second thinning rake surface, 43 Third thinning rake surface, 44 Thinning rake surface, 45 Thinning heel surface, 51 First relief surface, 52 Second relief surface, 61 First thinning cutting edge, 61a First thinning cutting edge region, 61b Second thinning cutting edge region, 62 Second thinning cutting edge, 63 Third thinning cutting edge, 64 Thinning cutting edge, 65 Main cutting edge, 65a First main cutting edge area, 65b Second main cutting edge area, 66 Chisel edge, 71 Outer endpoint, 72 Second connection point, 73 Third connection point, 74 Fourth connection point, 75 Fifth connection point, 100 Drill, 101 Tip, 102 Rear end, A, A2 Central axis, A1 Straight line, B1 First virtual straight line, B2 Second virtual straight line, C1 First length, C2 Second length, C3 Third length, D Diameter, E First distance, F Amount of recess, L1 First direction, L2 Second direction, R Radius of curvature, T1 First triple point, T2 Second triple point, T3 Third triple point.
Claims
1. A drill that rotates around a central axis, comprising: a tip and a rear end which are ends in a direction along the central axis; a tip surface at the tip; an outer circumferential surface connected to the tip surface; a cutting edge extending from the outer circumferential surface toward the central axis on the tip surface; a flute surface formed on the outer circumferential surface and extending around the central axis toward the rear end from the tip surface; and a thinning surface connected to the tip surface and the flute surface, wherein the tip surface has a first relief surface portion connected to the cutting edge and a second relief surface portion on the opposite side of the first relief surface portion with the flute surface in between; and the thinning surface has a thinning rake surface connected to the first relief surface portion and a thinning heel surface connected to the second relief surface portion. The thinning rake face has a first thinning rake face portion connected to the thinning heel surface, a second thinning rake face portion connected to the flute surface, and a third thinning rake face portion connecting the first thinning rake face portion and the second thinning rake face portion. The cutting edge has a main cutting edge portion connected to the outer circumferential surface and formed by the ridge line between the first relief surface and the flute surface, a straight first thinning cutting edge portion formed by the ridge line between the first thinning rake face portion and the first relief surface, a straight second thinning cutting edge portion formed by the ridge line between the second thinning rake face portion and the first relief surface, and a curved third thinning cutting edge portion located between the first thinning cutting edge portion and the second thinning cutting edge portion and formed by the ridge line between the third thinning rake face portion and the first relief surface.
2. The drill according to claim 1, wherein the axial rake angle of the first thinning rake face and the second thinning rake face are -7° or more and 7° or less.
3. When the tip surface is viewed along the central axis, the amount of recess of the main cutting edge with respect to a virtual straight line connecting the connection point between the main cutting edge and the outer peripheral surface and the connection point between the second thinning cutting edge and the main cutting edge is -0.01 times or more and 0.02 times or less the diameter of the cutting edge, as described in claim 1 or claim 2.
4. The drill according to any one of claims 1 to 3, wherein, when the tip surface is viewed along the central axis, the distance between the imaginary straight line extending the second thinning cutting edge portion toward the outer peripheral surface and the outer endpoint of the main cutting edge portion is 0.01 times or less the diameter of the cutting edge.
5. The drill according to any one of claims 1 to 4, wherein the main cutting edge portion has a first main cutting edge region and a second main cutting edge region located on the opposite side of the first main cutting edge region with respect to the central axis, the first thinning cutting edge portion has a first thinning cutting edge region located between the first main cutting edge region and the central axis, and a second thinning cutting edge region located between the second main cutting edge region and the central axis, and when the tip surface is viewed along the central axis, the angle between the direction extending outward along the first thinning cutting edge region and the direction from the central axis toward the outer endpoint of the second main cutting edge region is 141° or more and 155° or less.
6. The drill according to any one of claims 1 to 5, wherein the value obtained by dividing the length of the first thinning cutting edge by the sum of the length of the main cutting edge and the length of the second thinning cutting edge is 0.19 or more and 0.25 or less.
7. A drill head that rotates around a central axis, comprising: a mounting surface which is an end face in a direction along the central axis; a tip surface which is the opposite surface of the mounting surface in a direction along the central axis; an outer circumferential surface connected to the mounting surface and the tip surface; a cutting edge extending from the outer circumferential surface toward the central axis on the tip surface; a flute surface formed on the outer circumferential surface and extending around the central axis toward the mounting surface from the tip surface; and a thinning surface connected to the tip surface and the flute surface, wherein the tip surface has a first relief surface portion connected to the cutting edge and a second relief surface portion located opposite the first relief surface portion across the flute surface; and the thinning surface has a thinning rake surface connected to the first relief surface portion and a thinning heel surface connected to the second relief surface portion. The drill head has a thinning rake face having a first thinning rake face portion connected to the thinning heel surface, a second thinning rake face portion connected to the flute surface, and a third thinning rake face portion connecting the first thinning rake face portion and the second thinning rake face portion, and the cutting edge having a main cutting edge portion connected to the outer circumferential surface and formed by the ridge line between the first relief surface portion and the flute surface, a straight first thinning cutting edge portion formed by the ridge line between the first thinning rake face portion and the first relief surface portion, a straight second thinning cutting edge portion formed by the ridge line between the second thinning rake face portion and the first relief surface portion, and a curved third thinning cutting edge portion located between the first thinning cutting edge portion and the second thinning cutting edge portion and formed by the ridge line between the third thinning rake face portion and the first relief surface portion.
8. A drill with an interchangeable tip, comprising the drill head described in claim 7 and a holder attached to the mounting surface.