Drilling tool

Abstract

This drilling tool has a body part, a first cutting insert, and a second cutting insert. A first pocket has: a first lateral face connected with a front end face; a second lateral face that is connected to the front end face, is located more radially outward than the first lateral face, and faces the first lateral face; a third lateral face between a rear end face and each of the first and second lateral faces in a direction along an axis; and a seat surface where a bottom face contacts. A first raised part to be inserted into a recessed part is formed on the first lateral face, and a second raised part to be inserted into a recessed part is formed on the second lateral face. Provided that a first direction is the direction running from the center of the first raised part to the center of the second raised part and a second direction is the direction parallel to the axis and running from the rear end face to the front end face as seen along a line perpendicular to the seat surface, the angle between the first and second directions is greater than 45° and less than 135°.

Description

Drilling tools

[0001] The present disclosure relates to drilling tools.

[0002] Japanese Patent Application Laid-Open No. 2008-080483 (Patent Document 1) discloses a cutting tool having two replaceable cutting inserts.

[0003] JP 2008-080483 A

[0004] The drilling tool according to the present disclosure comprises a body portion, a first cutting insert, and a second cutting insert. The body portion extends along an axis. The first cutting insert is replaceable and has a central cutting edge. The second cutting insert is replaceable and has a peripheral cutting edge. The body portion has a front end surface and a rear end surface opposite the front end surface. The body portion is provided with a first pocket and a second pocket. The first pocket is continuous with the front end surface. The first cutting insert is disposed in the first pocket. The second pocket is continuous with the front end surface. The second cutting insert is disposed in the second pocket. The diameter of the inscribed circle of the central cutting edge is larger than the diameter of the inscribed circle of the peripheral cutting edge. The first cutting insert has a rake face, a flank face continuous with the rake face, and a bottom surface continuous with the flank face. The flank face has four flank portions. A recess is formed at the boundary between each of the four flank portions and the bottom surface. The first pocket has a first side surface connected to the front end surface, a second side surface connected to the front end surface, located radially outward from the first side surface and facing the first side surface, a third side surface located between each of the first and second side surfaces and the rear end surface in the direction along the axis, and a seating surface with a bottom surface in contact. A first protrusion to be inserted into the recess is formed on the first side surface, and a second protrusion to be inserted into the recess is formed on the second side surface. When viewed along a line perpendicular to the seating surface, a first direction is defined as a direction from the center of the first protrusion to the center of the second protrusion, and a second direction is defined as a direction parallel to the axis and from the rear end surface to the front end surface, the angle between the first direction and the second direction is greater than 45° and less than 135°.

[0005] FIG. 1 is a schematic perspective view showing the configuration of a drilling tool according to a first embodiment. FIG. 2 is a schematic plan view showing the configuration of a drilling tool according to the first embodiment. FIG. 3 is a schematic plan view showing the configuration of a first cutting insert. FIG. 4 is a schematic perspective view showing the configuration of a first cutting insert. FIG. 5 is a schematic plan view showing the configuration of a second cutting insert. FIG. 6 is a schematic perspective view showing the configuration of a second cutting insert. FIG. 7 is a first schematic perspective view showing the configuration of a main body portion. FIG. 8 is a schematic plan view showing the configuration of a first pocket. FIG. 9 is a schematic cross-sectional view taken along line IX-IX in FIG. 8. FIG. 10 is a second schematic perspective view showing the configuration of a main body portion. FIG. 11 is a schematic view showing the configuration of the rotational projection plane of the central cutting edge and the peripheral cutting edge when the drilling tool is rotated around the axis. FIG. 12 is a schematic plan view showing the configuration of a main body portion of a drilling tool according to a second embodiment. FIG. 13 is a schematic view showing the pocket shape of a sample and the state when fastened. Fig. 14 is a schematic plan view showing a state in which the second cutting insert is placed in the first pocket and pressed against the main body portion in the direction of arrow B. Fig. 15 is a schematic side view showing a state in which a force is applied to the front of the second cutting insert when the second cutting insert is placed in the first pocket. Fig. 16 is a schematic side view showing a state in which a force is applied to the rear of the second cutting insert when the second cutting insert is placed in the first pocket.

[0006] [Description of an embodiment of the present disclosure] First, an embodiment of the present disclosure (also referred to as the present embodiment) will be described.

[0007] (1) A drilling tool according to the present disclosure includes a body portion, a first cutting insert, and a second cutting insert. The body portion extends along an axis. The first cutting insert is replaceable and has a central cutting edge. The second cutting insert is replaceable and has a peripheral cutting edge. The body portion has a front end surface and a rear end surface opposite the front end surface. The body portion is provided with a first pocket and a second pocket. The first pocket is continuous with the front end surface. The first cutting insert is disposed in the first pocket. The second pocket is continuous with the front end surface. The second cutting insert is disposed in the second pocket. The diameter of the inscribed circle of the central cutting edge is larger than the diameter of the inscribed circle of the peripheral cutting edge. The first cutting insert has a rake face, a flank face continuous with the rake face, and a bottom surface continuous with the flank face. The flank face has four flank portions. A recess is formed at the boundary between each of the four flank portions and the bottom surface. The first pocket has a first side surface connected to the front end surface, a second side surface connected to the front end surface, located radially outward from the first side surface and facing the first side surface, a third side surface located between each of the first and second side surfaces and the rear end surface in the direction along the axis, and a seating surface with a bottom surface in contact. A first convex portion to be inserted into the recess is formed on the first side surface, and a second convex portion to be inserted into the recess is formed on the second side surface. When viewed along a line perpendicular to the seating surface, a first direction is defined as a direction from the center of the first convex portion to the center of the second convex portion, and a second direction is defined as a direction parallel to the axis and from the rear end surface to the front end surface, the angle between the first direction and the second direction is greater than 45° and less than 135°. This prevents incorrect installation of the cutting insert.

[0008] (2) According to the drilling tool according to (1) above, the third side surface may be continuous with the seat surface.

[0009] (3) According to the drilling tool according to (1) above, a third protrusion to be inserted into the recess may be formed on the third side surface.

[0010] (4) In the drilling tool according to any one of (1) to (3) above, when the height of the first convex portion relative to the seating surface is defined as the first height, the diameter of the inscribed circle of the central cutting edge is defined as the first diameter, and the diameter of the inscribed circle of the peripheral cutting edge is defined as the second diameter, the value obtained by dividing the first height by the first diameter may be 0.05 or more and 0.15 or less, and the value obtained by dividing the first height by the second diameter may be 0.054 or more and 0.185 or less.

[0011] (5) According to the drilling tool according to any one of (1) to (4) above, when the diameter of the inscribed circle of the central cutting edge is the first diameter and the diameter of the inscribed circle of the peripheral cutting edge is the second diameter, the value obtained by dividing the first diameter by the second diameter may be 1.08 or more and 1.23 or less.

[0012] (6) According to the drilling tool according to any one of (1) to (5) above, the bottom surface of the second cutting insert may have a planar shape.

[0013] (7) According to the drilling tool of (1), the third side surface may be continuous with the bottom surface. When the height of the first convex portion relative to the bearing surface is defined as the first height, the diameter of the inscribed circle of the central cutting edge is defined as the first diameter, and the diameter of the inscribed circle of the peripheral cutting edge is defined as the second diameter, the value obtained by dividing the first height by the first diameter may be 0.05 or more and 0.15 or less, and the value obtained by dividing the first height by the second diameter may be 0.054 or more and 0.185 or less. The value obtained by dividing the first diameter by the second diameter may be 1.08 or more and 1.23 or less.

[0014] Specific examples of drilling tools according to embodiments of the present disclosure will be described below with reference to the drawings, in which the same or corresponding parts are designated by the same reference numerals and descriptions thereof will not be repeated.

[0015] First Embodiment Fig. 1 is a schematic perspective view showing the configuration of a drilling tool according to a first embodiment. Fig. 2 is a schematic plan view showing the configuration of the drilling tool according to the first embodiment.

[0016] 1 and 2 , the drilling tool 5 according to the first embodiment has a body portion 100, a first cutting insert 10, a second cutting insert 20, a first fastening screw 3, and a second fastening screw 4. The first cutting insert 10 is attached to the body portion 100 using the first fastening screw 3. The second cutting insert 20 is attached to the body portion 100 using the second fastening screw 4. The first cutting insert 10 is replaceable. The second cutting insert 20 is replaceable. In other words, the drilling tool 5 according to the first embodiment is an indexable drilling tool 5.

[0017] As shown in Fig. 2, the main body 100 extends along an axis A. The drilling tool 5 is rotatable, for example, around the axis A. The main body 100 has a front end surface 113, a rear end surface 114, a first outer peripheral surface 111, a second outer peripheral surface 112, a first groove surface 115, and a second groove surface 116. The front end surface 113 faces the workpiece. The rear end surface 114 is located opposite the front end surface 113. The rear end surface 114 is attached to a rotating spindle (not shown) of a machine tool.

[0018] The axis A is parallel to the direction from the rear end surface 114 to the front end surface 113. The direction from the rear end surface 114 to the front end surface 113 is defined as the forward direction. The direction from the front end surface 113 to the rear end surface 114 is defined as the rearward direction.

[0019] Each of the first outer peripheral surface 111 and the second outer peripheral surface 112 is continuous with the front end surface 113. In the direction from the rear end surface 114 toward the front end surface 113, each of the first outer peripheral surface 111 and the second outer peripheral surface 112 is located between the front end surface 113 and the rear end surface 114.

[0020] In the direction from the rear end face 114 toward the front end face 113, the first groove surface 115 is provided between the first cutting insert 10 and the rear end face 114. The first groove surface 115 discharges chips cut by the first cutting insert 10. A portion of the first cutting insert 10 is located forward of the front end face 113.

[0021] The second groove surface 116 is provided between the second cutting insert 20 and the rear end surface 114 in a direction from the rear end surface 114 toward the front end surface 113. The second groove surface 116 discharges chips cut by the second cutting insert 20. A portion of the second cutting insert 20 is located forward of the front end surface 113.

[0022] Fig. 3 is a schematic plan view showing the configuration of the first cutting insert 10. Fig. 4 is a schematic perspective view showing the configuration of the first cutting insert 10.

[0023] 3 and 4 , the first cutting insert 10 has a center cutting edge 17, a first rake face 16, a first flank face 19, and a first bottom surface 15. The first rake face 16 is continuous with the first flank face 19. The ridgeline between the first rake face 16 and the first flank face 19 forms the center cutting edge 17.

[0024] The first bottom surface 15 is opposite the first cutting face 16. The first bottom surface 15 is continuous with a first flank surface 19. The first cutting insert 10 is provided with a first through hole 18. The first through hole 18 passes through between the first cutting face 16 and the first bottom surface 15. The first fastening screw 3 is disposed in the first through hole 18.

[0025] 3 , when viewed in the direction in which the first through-hole 18 penetrates, the first inscribed circle E1 is inscribed in the central cutting edge 17. The diameter of the first inscribed circle E1 is defined as a first diameter D1. The first diameter D1 is, for example, 6.9 mm. The first diameter D1 may be 5.9 mm or greater and 7.9 mm or less.

[0026] As shown in Fig. 4, the first flank 19 has four flank portions. Specifically, the first flank 19 has a first flank portion 11, a second flank portion 12, a third flank portion 13, and a fourth flank portion 14. The first flank portion 11 is opposite the second flank portion 12. The third flank portion 13 is opposite the fourth flank portion 14. The first through hole 18 is between the first flank portion 11 and the second flank portion 12, and between the third flank portion 13 and the fourth flank portion 14.

[0027] A recess is formed at the boundary between each of the four flank portions and the first bottom surface 15. Specifically, the first recess 31 is formed at the boundary between the first flank portion 11 and the first bottom surface 15. The second recess 32 is formed at the boundary between the second flank portion 12 and the first bottom surface 15. The third recess 33 is formed at the boundary between the third flank portion 13 and the first bottom surface 15. The fourth recess 34 is formed at the boundary between the fourth flank portion 14 and the first bottom surface 15. Each of the first recess 31, the second recess 32, the third recess 33, and the fourth recess 34 is spaced apart from the first through hole 18.

[0028] Fig. 5 is a schematic plan view showing the configuration of the second cutting insert 20. Fig. 6 is a schematic perspective view showing the configuration of the second cutting insert 20.

[0029] 5 and 6 , the second cutting insert 20 has a peripheral cutting edge 27, a second rake face 26, a second flank face 29, and a second bottom surface 25. The second rake face 26 is continuous with the second flank face 29. The ridge between the second rake face 26 and the second flank face 29 forms the peripheral cutting edge 27.

[0030] The second bottom surface 25 is located opposite the second rake face 26. The second bottom surface 25 is continuous with the second flank face 29. The second cutting insert 20 is provided with a second through hole 28. The second through hole 28 passes between the second rake face 26 and the second bottom surface 25. A second fastening screw 4 is disposed in the second through hole 28. When viewed in the direction in which the second through hole 28 passes through, the second bottom surface 25 has, for example, a rectangular shape. In the second cutting insert 20, no recess recessed toward the second through hole 28 is provided at the boundary between the second bottom surface 25 and the second flank face 29.

[0031] As shown in Figure 5, when viewed in the direction in which the second through-hole 28 penetrates, the second inscribed circle E2 is inscribed in the peripheral cutting edge 27. The diameter of the second inscribed circle E2 is set to a second diameter D2. The second diameter D2 is, for example, 6.3 mm. The second diameter D2 may be 5.3 mm or greater and 7.3 mm or less.

[0032] The first diameter D1 is larger than the second diameter D2. The value obtained by dividing the first diameter D1 by the second diameter D2 is, for example, 1.08 or greater and 1.23 or less. The value obtained by dividing the first diameter D1 by the second diameter D2 may be 1.10 or greater, or 1.12 or greater. The value obtained by dividing the first diameter D1 by the second diameter D2 may be 1.21 or less, or 1.19 or less.

[0033] As shown in Fig. 6, the second flank 29 has four flank portions. Specifically, the second flank 29 has a fifth flank portion 21, a sixth flank portion 22, a seventh flank portion 23, and an eighth flank portion 24. The fifth flank portion 21 is opposite the seventh flank portion 23. The sixth flank portion 22 is opposite the eighth flank portion 24. The second through hole 28 is located between the fifth flank portion 21 and the seventh flank portion 23, and between the sixth flank portion 22 and the eighth flank portion 24.

[0034] The second bottom surface 25 has a first bottom surface portion 71, a second bottom surface portion 72, and a third bottom surface portion 73. The first bottom surface portion 71 is continuous with the second relief surface 29. The second bottom surface portion 72 is inclined with respect to the first bottom surface portion 71. The second bottom surface portion 72 is continuous with the first bottom surface portion 71. The third bottom surface portion 73 is inclined with respect to the second bottom surface portion 72. The third bottom surface portion 73 is continuous with the second bottom surface portion 72. The second bottom surface portion 72 is located between the first bottom surface portion 71 and the third bottom surface portion 73. The third bottom surface portion 73 may be parallel to the first bottom surface portion 71. When viewed in the direction in which the second through hole 28 penetrates, the first bottom surface portion 71 surrounds the third bottom surface portion 73. The third bottom surface portion 73 of the second bottom surface 25 has, for example, a planar shape.

[0035] Fig. 7 is a first perspective schematic view showing the configuration of the main body portion 100. As shown in Fig. 7, a first pocket 1 is provided in the main body portion 100. A first cutting insert 10 is disposed in the first pocket 1. The first pocket 1 is continuous with a front end surface 113. From another perspective, the first pocket 1 is provided so as to open to the front end surface 113.

[0036] The first pocket 1 has a first side surface 41, a second side surface 42, a third side surface 43, a first curved surface 45, a second curved surface 46, and a first seating surface 44. The first side surface 41 and the second side surface 42 are each continuous with the front end surface 113. The second side surface 42 faces the first side surface 41. The second side surface 42 is located radially outward from the first side surface 41. Note that in this specification, the radially outward direction is defined as a direction extending radially from the axis A in a plane perpendicular to the axis A.

[0037] The third side surface 43 faces forward. In the direction along the axis A, the third side surface 43 is located between each of the first side surface 41 and the second side surface 42 and the rear end surface 114. From another perspective, in the direction along the axis A, the third side surface 43 is located between the front end surface 113 and the first groove surface 115. The first curved surface 45 connects the first side surface 41 and the third side surface 43. The second curved surface 46 connects the second side surface 42 and the third side surface 43.

[0038] The first bearing surface 44 is a surface that comes into contact with the first bottom surface 15 of the first cutting insert 10. A first screw hole 47 is provided in the first bearing surface 44. The first fastening screw 3 is inserted into the first screw hole 47.

[0039] The main body 100 has a first flat surface 117. The first pocket 1 is provided at the boundary between the first flat surface 117 and the front end surface 113. The first flat surface 117 is continuous with the first groove surface 115. In the direction along the axis A, the first flat surface 117 is located between the front end surface 113 and the first groove surface 115. The first flat surface 117 may be substantially parallel to the first bearing surface 44.

[0040] A first convex portion 51 is formed on the first side surface 41. The first convex portion 51 is inserted into a recess provided in the first cutting insert 10. A second convex portion 52 is formed on the second side surface 42. The second convex portion 52 is inserted into a recess provided in the first cutting insert 10. The third side surface 43 does not have a convex portion that fits into the recess provided in the first cutting insert 10. From another perspective, the third side surface 43 is continuous with the first seating surface 44. The third side surface 43 may be flat.

[0041] FIG. 8 is a schematic plan view showing the configuration of the first pocket 1. The plane shown in FIG. 8 is parallel to the first bearing surface 44 of the first pocket 1. As shown in FIG. 8 , when viewed along a line perpendicular to the first bearing surface 44, the direction from the center of the first convex portion 51 (first center C1) to the center of the second convex portion 52 (second center C2) is defined as a first direction 91. Note that, in this specification, the center of a convex portion is defined as the center of the tip of the convex portion. The direction parallel to the axis A and from the rear end surface 114 to the front end surface 113 is defined as a second direction 92. The angle formed by the first direction 91 and the second direction 92 is defined as a first angle θ1. The first angle θ1 is greater than 45° and less than 135°.

[0042] The first angle θ1 is, for example, 82°. The first angle θ1 may be greater than or equal to 70° and less than or equal to 95°. The first angle θ1 may be greater than or equal to 75°, or may be greater than or equal to 80°. The first angle θ1 may be less than or equal to 90°, or may be less than or equal to 85°.

[0043] FIG. 9 is a schematic cross-sectional view taken along line IX-IX in FIG. 8 . The cross section shown in FIG. 9 is along a first direction 91 and perpendicular to the first seating surface 44 of the first pocket 1. As shown in FIG. 9 , the first convex portion 51 is provided at the boundary between the first side surface 41 and the first seating surface 44. The height of the first convex portion 51 relative to the first seating surface 44 is defined as a first height H1. The second convex portion 52 is provided at the boundary between the second side surface 42 and the first seating surface 44. The height of the second convex portion 52 relative to the first seating surface 44 is defined as a second height H2. The width of the upper surface of the first convex portion 51 along the first direction 91 is defined as a first width W1. The width of the upper surface of the second convex portion 52 along the first direction 91 is defined as a second width W2.

[0044] The first height H1 is substantially the same as the second height H2. The first width W1 may be greater than the first height H1 or less than the first height H1. The second width W2 may be greater than the second height H2 or less than the second height H2. The first height H1 may be different from the second height H2. The first width W1 may be different from the second width W2.

[0045] The value obtained by dividing the first height H1 by the first diameter D1 is, for example, 0.05 or more and 0.15 or less. The value obtained by dividing the first height H1 by the first diameter D1 may be 0.07 or more, or 0.09 or more. The value obtained by dividing the first height H1 by the first diameter D1 may be 0.13 or less, or 0.11 or less.

[0046] The value obtained by dividing the second height H2 by the first diameter D1 is, for example, 0.05 or more and 0.15 or less. The value obtained by dividing the second height H2 by the first diameter D1 may be 0.07 or more, or 0.09 or more. The value obtained by dividing the second height H2 by the first diameter D1 may be 0.13 or less, or 0.11 or less.

[0047] The value obtained by dividing the first height H1 by the second diameter D2 is, for example, 0.054 or more and 0.185 or less. The value obtained by dividing the first height H1 by the second diameter D2 may be, for example, 0.074 or more, or 0.094 or more. The value obtained by dividing the first height H1 by the second diameter D2 may be, for example, 0.165 or less, or 0.145 or less.

[0048] The value obtained by dividing the second height H2 by the second diameter D2 is, for example, 0.054 or more and 0.185 or less. The value obtained by dividing the second height H2 by the second diameter D2 may be, for example, 0.074 or more, or 0.094 or more. The value obtained by dividing the second height H2 by the second diameter D2 may be, for example, 0.165 or less, or 0.145 or less.

[0049] 10 is a second perspective schematic view showing the configuration of the main body 100. The main body 100 is provided with a second pocket 2. A second cutting insert 20 is disposed in the second pocket 2. The second pocket 2 is continuous with both the front end surface 113 and the second outer peripheral surface 112. From another perspective, the second pocket 2 is provided so as to open to both the front end surface 113 and the second outer peripheral surface 112.

[0050] As shown in FIG. 10 , the second pocket 2 has a fourth side surface 61, a fifth side surface 62, a third curved surface 64, and a second seating surface 63. The fourth side surface 61 is continuous with the front end surface 113. The fifth side surface 62 faces forward. In the direction along the axis A, the fifth side surface 62 is located between the fourth side surface 61 and the rear end surface 114. From another perspective, in the direction along the axis A, the fifth side surface 62 is located between the front end surface 113 and the second groove surface 116. The third curved surface 64 connects the fourth side surface 61 and the fifth side surface 62.

[0051] The second bearing surface 63 is a surface with which the second bottom surface 25 of the second cutting insert 20 comes into contact. A second screw hole 67 is provided in the second bearing surface 63. The second fastening screw 4 is inserted into the second screw hole 67. The fourth side surface 61 does not have a protrusion that fits into a recess that is provided in the first cutting insert 10. The fourth side surface 61 may be continuous with the second bearing surface 63. The fifth side surface 62 does not have a protrusion that fits into a recess that is provided in the first cutting insert 10. The fifth side surface 62 may be continuous with the second bearing surface 63.

[0052] The main body 100 has a second flat surface 118. The second pocket 2 is provided at the boundary between the second flat surface 118 and the front end surface 113. The second flat surface 118 is continuous with the second groove surface 116. In the direction along the axis A, the second flat surface 118 is located between the fifth side surface 62 and the second groove surface 116. The second flat surface 118 may be substantially parallel to the second bearing surface 63.

[0053] Figure 11 is a schematic diagram showing the configuration of the rotational projection plane of the central cutting edge 17 and the peripheral cutting edge 27 when the drilling tool 5 is rotated around the axis A. As shown in Figure 11, the central cutting edge 17 in the rotational projection plane intersects with the axis A. The peripheral cutting edge 27 in the rotational projection plane does not intersect with the axis A. In the rotational projection plane, the central cutting edge 17 intersects with the peripheral cutting edge 27. When drilling a workpiece using the drilling tool 5, the central cutting edge 17 cuts the radially inner side of the hole, and the peripheral cutting edge 27 cuts the radially outer side of the hole.

[0054] Second Embodiment Next, the configuration of the drilling tool 5 according to the second embodiment will be described. The drilling tool 5 according to the second embodiment differs from the drilling tool 5 according to the first embodiment mainly in that a third convex portion 53 is formed on the third side surface 43, but other configurations are substantially the same as those of the drilling tool 5 according to the first embodiment. Below, the configurations that differ from the drilling tool 5 according to the first embodiment will be mainly described.

[0055] FIG. 12 is a schematic plan view showing the configuration of the main body 100 of the drilling tool 5 according to the second embodiment. As shown in FIG. 12 , a third convex portion 53 is formed on the third side surface 43. The third convex portion 53 is inserted into the recess of the first cutting insert 10. In the radial direction, the third convex portion 53 is disposed between the first convex portion 51 and the second convex portion 52. The shape of the third convex portion 53 is substantially the same as the shapes of the first convex portion 51 and the second convex portion 52. Specifically, the height of the third convex portion 53 is substantially the same as the first height H1 and the second height H2. Note that the height of the third convex portion 53 may be different from the first height H1 and the second height H2.

[0056] Next, the effects of the drilling tool 5 according to this embodiment will be described. According to the drilling tool 5 according to this embodiment, a first cutting insert 10 is disposed in the first pocket 1. A second cutting insert 20 is disposed in the second pocket 2. The diameter of the inscribed circle of the central cutting edge 17 of the first cutting insert 10 is larger than the diameter of the inscribed circle of the peripheral cutting edge 27 of the second cutting insert 20. By making the diameter of the inscribed circle of the central cutting edge 17, which has a low peripheral speed, larger than the diameter of the inscribed circle of the peripheral cutting edge 27, which has a high peripheral speed, the forces applied to the cutting edges can be balanced. As a result, the accuracy of the hole formed by the drilling tool 5 can be improved.

[0057] In the drilling tool 5 according to this embodiment, the first cutting insert 10 has a first rake face 16, a first flank face 19, and a first bottom face 15. The first flank face 19 has four flank portions. A recess is formed at the boundary between each of the four flank portions and the first bottom face 15. The first pocket 1 has a first side face 41, a second side face 42, a third side face 43, and a seat surface. A first protrusion 51 to be inserted into the recess is formed on the first side face 41, and a second protrusion 52 to be inserted into the recess is formed on the second side face 42.

[0058] When the first cutting insert 10 is placed in the first pocket 1, one of the four recesses formed in the first cutting insert 10 is inserted into the first protrusion 51, and one of the remaining three recesses is inserted into the second protrusion 52. Therefore, the first bottom surface 15 of the first cutting insert 10 contacts the first seating surface 44 of the first pocket 1. On the other hand, when the second cutting insert 20 is erroneously placed in the first pocket 1, the second cutting insert 20 is placed on both the first protrusion 51 and the second protrusion 52. Therefore, a gap is formed between the second bottom surface 25 of the second cutting insert 20 and the first seating surface 44 of the first pocket 1. Therefore, if the second cutting insert 20 is erroneously placed in the first pocket 1, an operator can easily notice the mistake. As a result, incorrect installation of cutting inserts is reduced.

[0059] In the drilling tool 5 according to the present embodiment, when viewed along a straight line perpendicular to the first bearing surface 44, the direction from the center of the first convex portion 51 toward the center of the second convex portion 52 is defined as the first direction 91, and the direction parallel to the axis A and from the rear end surface 114 toward the front end surface 113 is defined as the second direction 92. If the angle formed by the first direction 91 and the second direction 92 is 45° or less or 135° or more, the second cutting insert 20 may get in between the first convex portion 51 and the second convex portion 52, and the second bottom surface 25 of the second cutting insert 20 may come into contact with the first bearing surface 44 of the first pocket 1. By setting the angle between the first direction 91 and the second direction 92 to be greater than 45° and smaller than 135°, it is possible to prevent the second bottom surface 25 of the second cutting insert 20 from coming into contact with the first seating surface 44 of the first pocket 1. Therefore, the second cutting insert 20 is disposed on each of the first convex portion 51 and the second convex portion 52. As a result, a large gap is formed between the second bottom surface 25 of the second cutting insert 20 and the first seating surface 44 of the first pocket 1.

[0060] According to the drilling tool 5 of this embodiment, the third side surface 43 may be continuous with the seat surface. When a force is applied to the rear of the second cutting insert 20 while the second cutting insert 20 is placed in the first pocket 1, the second cutting insert 20 tilts rearward. In this case, the operator is likely to feel uncomfortable, and is therefore more likely to notice that the second cutting insert 20 has been placed incorrectly in the first pocket 1. As a result, incorrect installation of the cutting insert is further suppressed.

[0061] If the height of the convex portion is excessively small, the gap between the bottom surface of the second cutting insert 20 and the seat surface of the first pocket 1 becomes small. Conversely, if the height of the convex portion is excessively large, the depth of the recess formed in the second cutting insert 20 needs to be increased. If the depth of the recess is large, the area of ​​the flank surface of the second cutting insert 20 becomes small, and the contact area between the second cutting insert 20 and the main body portion 100 becomes small. In this case, the second cutting insert 20 is not firmly attached to the main body portion 100.

[0062] In the drilling tool 5 according to this embodiment, the value obtained by dividing the first height H1 by the first diameter D1 may be 0.05 or more and 0.15 or less, and the value obtained by dividing the first height H1 by the second diameter D2 may be 0.054 or more and 0.185 or less. This allows the second cutting insert 20 to be firmly attached to the main body 100 while ensuring a large gap between the second bottom surface 25 of the second cutting insert 20 and the first seating surface 44 of the first pocket 1.

[0063] In the drilling tool 5 according to this embodiment, when the diameter of the inscribed circle of the central cutting edge 17 is the first diameter D1 and the diameter of the inscribed circle of the peripheral cutting edge 27 is the second diameter D2, the value obtained by dividing the first diameter D1 by the second diameter D2 may be 1.08 or greater and 1.23 or less. This makes the first cutting insert 10 sufficiently larger than the second cutting insert 20. As a result, even if an operator mistakenly attempts to place the first cutting insert 10 in the second pocket 2, the first cutting insert 10 will not be placed in the second pocket 2. This further reduces incorrect installation of the cutting inserts.

[0064] According to the drilling tool 5 of this embodiment, the third bottom surface portion 73 of the second bottom surface 25 of the second cutting insert 20 may have a planar shape. This makes the bottom surface shape of the first cutting insert 10 clearly different from the bottom surface shape of the second cutting insert 20. As a result, it is possible to prevent an operator from misidentifying the cutting inserts.

[0065] Example 1 (Sample Preparation) The main body 100 of the drilling tool 5 according to Samples 1, 2, and 3 was prepared. The main body 100 of the drilling tool 5 according to Sample 1 is a comparative example. The main body 100 of the drilling tool 5 according to Samples 2 and 3 are examples.

[0066] 13 is a schematic diagram showing the pocket shape of the samples and the state when fastened. As shown in FIG. 13, in sample 1, a first convex portion 51 is formed on the first side surface 41, and a third convex portion 53 is formed on the third side surface 43. No convex portion is formed on the second side surface 42. In sample 1, the midpoint between the first convex portion 51 and the third convex portion 53 does not coincide with the center of the first screw hole 47.

[0067] In sample 2, a first convex portion 51 is formed on the first side surface 41, and a second convex portion 52 is formed on the second side surface 42. No convex portion is formed on the third side surface 43. Sample 2 corresponds to the drilling tool 5 according to the first embodiment. In sample 2, the midpoint between the first convex portion 51 and the second convex portion 52 coincides with the center of the first screw hole 47.

[0068] In sample 3, a first convex portion 51 is formed on the first side surface 41, a second convex portion 52 is formed on the second side surface 42, and a third convex portion 53 is formed on the third side surface 43. Sample 3 corresponds to the drilling tool 5 according to the second embodiment. In sample 3, the midpoint between the first convex portion 51 and the second convex portion 52 coincides with the center of the first screw hole 47.

[0069] (Verification method) When the second cutting insert 20 was attached to the main body portion 100 in the first pocket 1, a gap between the first seating surface 44 and the second bottom surface 25 of the second cutting insert 20 was visually observed. Specifically, the second cutting insert 20 was disposed in the first pocket 1 by inserting the first fastening screw 3 into the second through hole 28 and the first screw hole 47 of the second cutting insert 20 while aligning the position of the first screw hole 47 of the first pocket 1 with the position of the second through hole 28 of the second cutting insert 20.

[0070] 13 , when the second cutting insert 20 is placed in the first pocket 1 of the main body 100 of the sample 1, the second bottom surface 25 of the second cutting insert 20 is inclined with respect to the first seating surface 44. A part of the second bottom surface 25 of the second cutting insert 20 contacts the first seating surface 44, and therefore the gap between the second bottom surface 25 of the second cutting insert 20 and the first seating surface 44 becomes small.

[0071] On the other hand, when the second cutting insert 20 is placed in the first pocket 1 of the main body 100 of Samples 2 and 3, the second bottom surface 25 of the second cutting insert 20 is substantially parallel to the first seating surface 44. The gap between the bottom surface of the second cutting insert 20 and the first seating surface 44 is relatively large. This makes it easy for an operator to visually observe the gap.

[0072] Example 2 (Sample Preparation) The main body 100 of the drilling tool 5 according to Samples 1, 2, and 3 was prepared. The main body 100 of the drilling tool 5 according to Samples 1, 2, and 3 of Example 2 was the same as the main body 100 of the drilling tool 5 according to Samples 1, 2, and 3 of Example 1.

[0073] (Verification method) Fig. 14 is a schematic plan view showing a state in which the second cutting insert 20 is placed in the first pocket 1 and pressed against the main body portion 100 in the direction of arrow B. As shown in Fig. 14, the second flank surface 29 of the second cutting insert 20 is pressed against each of the first side surface 41 and the third side surface 43 of the first pocket 1. In this state, the center position of the second through hole 28 of the second cutting insert 20 does not coincide with the center position of the first screw hole 47 provided in the first seating surface 44 of the first pocket 1.

[0074] (Verification Results) In the first pocket 1 of the main body portion 100 of Sample 2, the first convex portion 51 is formed on the first side surface 41, but no convex portion is formed on the third side surface 43. Therefore, when the second cutting insert 20 is pressed against the main body portion 100 in the direction of arrow B, the bottom surface of the second cutting insert 20 is inclined with respect to the first seating surface 44. Therefore, when the second cutting insert 20 is mistakenly placed in the first pocket 1, the worker is likely to feel uncomfortable. As a result, the worker is likely to notice that the second cutting insert 20 has been mistakenly attached to the first pocket 1.

[0075] On the other hand, in the first pocket 1 of the main body portion 100 of Samples 1 and 3, a first convex portion 51 is formed on the first side surface 41, and a third convex portion 53 is formed on the third side surface 43. Therefore, when the second cutting insert 20 is pressed against the main body portion 100 in the direction of arrow B, the second bottom surface 25 of the second cutting insert 20 contacts each of the first convex portion 51 and the third convex portion 53. Therefore, even if the second cutting insert 20 is erroneously placed in the first pocket 1, the second cutting insert 20 is stably placed in the first pocket 1. As a result, it is difficult for an operator to notice that the second cutting insert 20 has been erroneously attached to the first pocket 1.

[0076] From the above, compared to the drilling tools 5 of samples 1 and 3, the drilling tool 5 of sample 2 makes it easier for an operator to notice that the second cutting insert 20 has been mistakenly installed in the first pocket 1.

[0077] <Example 3> (Sample Preparation) The main body 100 of the drilling tool 5 according to Samples 2 and 3 was prepared. The main body 100 of the drilling tool 5 according to Samples 2 and 3 of Example 3 was the same as the main body 100 of the drilling tool 5 according to Samples 2 and 3 of Example 1.

[0078] (Verification method) Fig. 15 is a side schematic view showing a state in which a force is applied to the front of the second cutting insert 20 with the second cutting insert 20 disposed in the first pocket 1. The force is applied in a direction toward the first seating surface 44 along a normal to the first seating surface 44. As shown in Fig. 15, when a force is applied to the front of the second cutting insert 20, the second cutting insert 20 tilts forward. When a force is applied to the front of the second cutting insert 20, the inclination angle of the normal to the second bottom surface 25 of the second cutting insert 20 with respect to the normal to the first seating surface 44 of the first pocket 1 is set to a second angle θ2.

[0079] Fig. 16 is a schematic side view showing a state in which a force is applied to the rear of the second cutting insert 20 with the second cutting insert 20 disposed in the first pocket 1. The force is applied in a direction toward the first seating surface 44 along a normal to the first seating surface 44. As shown in Fig. 16, when a force is applied to the rear of the second cutting insert 20, the second cutting insert 20 inclines rearward. When a force is applied to the rear of the second cutting insert 20, the inclination angle of the normal to the second bottom surface 25 of the second cutting insert 20 with respect to the normal to the first seating surface 44 of the first pocket 1 is set to a third angle θ3.

[0080] In the main body 100 of the drilling tool 5 according to Sample 2, the height of the first convex portion 51 is the same as the height of the second convex portion 52. In the main body 100 of the drilling tool 5 according to Sample 3, the height of the first convex portion 51 is the same as the height of the second convex portion 52 and the height of the third convex portion 53. The height of the convex portion was changed in the range from 0.2 mm to 2.4 mm, and the second angle θ2 and the third angle θ3 were calculated.

[0081] (Verification results)

[0082]

[0083] Table 1 shows the relationship between the height of the convex portion and the second angle θ2 and the third angle θ3. As shown in Table 1, in the drilling tool 5 of Sample 2, as the height of the convex portion increased, the second angle θ2 and the third angle θ3 each increased. In the first pocket 1 of the main body 100 of Sample 2, no convex portion was formed on the third side surface 43. Therefore, when a force is applied to the rear of the second cutting insert 20, the second cutting insert 20 tilts rearward. Therefore, when the second cutting insert 20 is erroneously placed in the first pocket 1, the operator is likely to feel uncomfortable. As a result, the operator is likely to notice that the second cutting insert 20 has been erroneously installed in the first pocket 1.

[0084] On the other hand, in the drilling tool 5 of Sample 3, as the height of the convex portion increased, the second angle θ2 increased, but the third angle θ3 remained unchanged at 0°. In the first pocket 1 of the main body portion 100 of Sample 3, a third convex portion 53 is formed on the third side surface 43. Therefore, when a force is applied to the rear of the second cutting insert 20, the second cutting insert 20 does not tilt rearward.

[0085] That is, the sum of the second angle θ2 and the third angle θ3 in the drilling tool 5 of Sample 2 is greater than the sum of the second angle θ2 and the third angle θ3 in the drilling tool 5 of Sample 3. Therefore, compared to the drilling tool 5 of Sample 3, the drilling tool 5 of Sample 2 makes it easier for an operator to notice that the second cutting insert 20 has been erroneously attached to the first pocket 1.

[0086] The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof.

[0087] 1 First pocket, 2 Second pocket, 3 First fastening screw, 4 Second fastening screw, 5 Drilling tool, 10 First cutting insert, 11 First flank portion, 12 Second flank portion, 13 Third flank portion, 14 Fourth flank portion, 15 First bottom surface, 16 First rake face, 17 Central cutting edge, 18 First through hole, 19 First flank surface, 20 Second cutting insert, 21 Fifth flank portion, 22 Sixth flank portion, 23 Seventh flank portion, 24 Eighth flank portion, 25 Second bottom surface, 26 Second rake face, 27 Peripheral cutting edge, 28 Second through hole, 29 Second flank surface, 31 First recess, 32 Second recess, 33 Third recess, 34 Fourth recess, 41 First side surface, 42 Second side surface, 43 Third side surface, 44 First bearing surface, 45 First curved surface, 46 Second curved surface, 47 First screw hole, 51 First convex portion, 52 Second convex portion, 53 Third convex portion, 61 Fourth side surface, 62 Fifth side surface, 63 Second bearing surface, 64 Third curved surface, 67 Second screw hole, 71 First bottom surface portion, 72 Second bottom surface portion, 73 Third bottom surface portion, 91 First direction, 92 Second direction, 100 Main body portion, 111 First outer peripheral surface, 112 Second outer peripheral surface, 113 Front end surface, 114 Rear end surface, 115 First groove surface, 116 Second groove surface, 117 First flat surface portion, 118 Second flat surface portion, A Axis, B Arrow, C1 First center, C2 Second center, D1 First diameter, D2 Second diameter, E1 First inscribed circle, E2 Second inscribed circle, H1 First height, H2 Second height, W1 First width, W2 Second width.

Claims

1. A cutting tool comprising: a main body extending along an axis; a first cutting insert which is replaceable and has a central cutting edge; and a second cutting insert which is replaceable and has a peripheral cutting edge, wherein the main body has a front end surface and a rear end surface opposite the front end surface, the main body is provided with: a first pocket which is continuous with the front end surface and in which the first cutting insert is disposed; and a second pocket which is continuous with the front end surface and in which the second cutting insert is disposed, the diameter of the inscribed circle of the central cutting edge is larger than the diameter of the inscribed circle of the peripheral cutting edge, the first cutting insert has a rake face, a flank which is continuous with the rake face, and a bottom surface which is continuous with the flank, the flank has four flank portions, and a recess is formed at the boundary between each of the four flank portions and the bottom surface, the first pocket has a first side surface continuous with the front end surface, a second side surface continuous with the front end surface, located radially outward of the first side surface and facing the first side surface, a third side surface located between each of the first side surface and the rear end surface in a direction along the axis, and a seat surface with which the bottom surface is in contact, wherein a first convex portion to be inserted into the recess is formed on the first side surface, and a second convex portion to be inserted into the recess is formed on the second side surface, and when viewed along a straight line perpendicular to the seat surface, a first direction is a direction from the center of the first convex portion to the center of the second convex portion, and a second direction is a direction parallel to the axis and from the rear end surface to the front end surface, the angle between the first direction and the second direction is greater than 45° and less than 135°.

2. The drilling tool according to claim 1, wherein the third side surface is continuous with the seat surface.

3. A drilling tool according to claim 1, wherein the third side surface is formed with a third protrusion that is inserted into the recess.

4. A drilling tool as described in any one of claims 1 to 3, wherein, when the height of the first convex portion relative to the seating surface is defined as a first height, the diameter of the inscribed circle of the central cutting edge is defined as a first diameter, and the diameter of the inscribed circle of the peripheral cutting edge is defined as a second diameter, the value obtained by dividing the first height by the first diameter is 0.05 or more and 0.15 or less, and the value obtained by dividing the first height by the second diameter is 0.054 or more and 0.185 or less.

5. A drilling tool according to any one of claims 1 to 4, wherein when the diameter of the inscribed circle of the central cutting edge is the first diameter and the diameter of the inscribed circle of the peripheral cutting edge is the second diameter, the value obtained by dividing the first diameter by the second diameter is 1.08 or more and 1.23 or less.

6. A drilling tool according to any one of claims 1 to 5, wherein the bottom surface of the second cutting insert has a planar shape.

7. A drilling tool as described in claim 1, wherein the third side surface is continuous with the seating surface, and when the height of the first convex portion relative to the seating surface is defined as a first height, the diameter of the inscribed circle of the central cutting edge is defined as a first diameter, and the diameter of the inscribed circle of the peripheral cutting edge is defined as a second diameter, the value obtained by dividing the first height by the first diameter is 0.05 or more and 0.15 or less, and the value obtained by dividing the first height by the second diameter is 0.054 or more and 0.185 or less, and the value obtained by dividing the first diameter by the second diameter is 1.08 or more and 1.23 or less.

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