drill

Abstract

The drill is a drill that rotates around an axis and has a cutting edge, a thinning surface, and a receding surface. The cutting edge has a major cutting edge portion and a thinning cutting edge portion. The thinning cutting edge portion is continuous with the major cutting edge portion. The thinning surface is continuous with the thinning cutting edge portion. The receding surface is provided with a coolant supply hole. In a cross section that is parallel to and includes the axis, the receding surface is located axially rearward of the thinning surface, and the opening edge of the coolant supply hole on the receding surface has a first position and a second position. In a cross section that is parallel to and includes the axis, if the angle between the axis and a straight line passing through the first position and the second position and that is 90° or less is defined as the first angle, and the angle between the axis and a tangent to the thinning surface at the boundary between the thinning surface and the recessed surface and that is 90° or less is defined as the second angle, the first angle is smaller than the second angle.

Description

[Technical Field]

[0001] The present disclosure relates to a drill. [Background technology]

[0002] International Publication No. 2022 / 239045 (Patent Document 1) discloses a drill having an oil hole formed in the gash surface of the drill. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 239045 Summary of the Invention

[0004] The drill according to the present disclosure is a drill that rotates around an axis and includes a cutting edge, a thinning surface, and a retraction surface. The cutting edge has a major cutting edge portion and a thinning cutting edge portion. The thinning cutting edge portion is continuous with the major cutting edge portion. The thinning surface is continuous with the thinning cutting edge portion. The retraction surface is provided with a coolant supply hole. In a cross section that is parallel to and includes the axis, the retraction surface is located axially rearward of the thinning surface, and the opening edge of the coolant supply hole on the retraction surface has a first position and a second position. In a cross section that is parallel to and includes the axis, if the angle between the axis and a straight line passing through the first position and the second position and that is 90° or less is defined as the first angle, and the angle between the axis and a tangent to the thinning surface at the boundary between the thinning surface and the recessed surface and that is 90° or less is defined as the second angle, the first angle is smaller than the second angle. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a schematic front view showing the configuration of a drill according to a first embodiment. [Figure 2]FIG. 2 is a schematic side view showing the configuration of the drill according to the first embodiment. [Figure 3] FIG. 3 is a schematic perspective view showing a part of the first body region of the drill according to the first embodiment. [Figure 4] FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 5 is an enlarged schematic view of region V in FIG. [Figure 6] FIG. 6 is a schematic front view showing the configuration of a drill according to the second embodiment. [Figure 7] FIG. 7 is a schematic perspective view showing a part of the first body region of the drill according to the second embodiment. [Figure 8] FIG. 8 is a schematic front view showing the configuration of a drill according to a third embodiment. [Figure 9] FIG. 9 is a schematic perspective view showing a part of the first body region of the drill according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0006] [Description of the embodiments of the present disclosure] First, an embodiment of the present disclosure (also referred to as the present embodiment) will be described. (1) A drill according to the present disclosure is a drill that rotates around an axis and includes a cutting edge, a thinning surface, and a receding surface. The cutting edge has a major cutting edge portion and a thinning cutting edge portion. The thinning cutting edge portion is continuous with the major cutting edge portion. The thinning surface is continuous with the thinning cutting edge portion. The receding surface is provided with a coolant supply hole. In a cross section that is parallel to and includes the axis, the receding surface is located axially rearward of the thinning surface, and the opening edge of the coolant supply hole on the receding surface has a first position and a second position. In a cross section that is parallel to and includes the axis, if the angle between the axis and a straight line passing through the first position and the second position and that is 90° or less is defined as the first angle, and the angle between the axis and a tangent to the thinning surface at the boundary between the thinning surface and the recessed surface and that is 90° or less is defined as the second angle, the first angle is smaller than the second angle. (2) In the drill according to (1) above, the first angle may be equal to or greater than 0° and equal to or less than 45°. (3) In the drill according to (1) or (2) above, if the distance between the front end of the drill and the front end of the coolant supply hole in a direction parallel to the axis is defined as a first distance, the value obtained by dividing the first distance by the diameter of the cutting edge may be 0.1 or more and 0.7 or less. (4) In a drill according to any one of (1) to (3) above, if the distance between the front end of the coolant supply hole and the rear end of the coolant supply hole in a direction parallel to the axis is defined as a second distance, the value obtained by dividing the second distance by the diameter of the cutting edge may be 0.05 or more and 1.08 or less. (5) In the drill according to (1) above, the first angle may be equal to or greater than 0° and equal to or less than 45°. If the distance between the front end of the drill and the front end of the coolant supply hole in a direction parallel to the axis is defined as a first distance, and the distance between the front end of the coolant supply hole and the rear end of the coolant supply hole in a direction parallel to the axis is defined as a second distance, the value obtained by dividing the first distance by the diameter of the cutting edge may be equal to or greater than 0.1 and equal to or less than 0.7, and the value obtained by dividing the second distance by the diameter of the cutting edge may be equal to or greater than 0.05 and equal to or less than 1.08.

[0007] Specific examples of embodiments of the present disclosure will now be described 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.

[0008] (First embodiment) FIG. 1 is a schematic front view showing the configuration of a drill according to the first embodiment. As shown in FIG. 1, the drill 1 according to the first embodiment has a first cutting edge 10, a thinning surface 50, a recessed surface 60, a first flank surface 30, and a first outer peripheral surface 70. The first cutting edge 10 has a major cutting edge portion 11 and a thinning cutting edge portion 12. The major cutting edge portion 11 is continuous with the first outer peripheral surface 70. The thinning cutting edge portion 12 is continuous with the major cutting edge portion 11.

[0009] The drill 1 rotates around an axis A (see FIG. 2). A direction perpendicular to the axis A and radially outward from the axis A is defined as a radial direction. In the radial direction, the main cutting edge portion 11 is located between the thinning cutting edge portion 12 and the first outer peripheral surface 70. When viewed along the axis A, the main cutting edge portion 11 may have a portion recessed rearward in the rotational direction.

[0010] The thinning surface 50 is continuous with the thinning cutting edge portion 12. The receding surface 60 is continuous with the thinning surface 50. The receding surface 60 is continuous with the first outer peripheral surface 70. In the radial direction, the receding surface 60 may be located between the thinning surface 50 and the first outer peripheral surface 70. A coolant supply hole 2 is provided in the receding surface 60. Specifically, an opening edge 3 of the coolant supply hole 2 is located on the receding surface 60. As shown in FIG. 1 , when viewed in the direction along the axis A, the opening edge 3 of the coolant supply hole 2 is surrounded by the outer edge of the receding surface 60.

[0011] The first flank 30 has a first flank portion 31 and a second flank portion 32. The first flank portion 31 is continuous with each of the main cutting edge portion 11 and the thinning cutting edge portion 12. The first flank portion 31 is continuous with the thinning surface 50 at the thinning cutting edge portion 12. The second flank portion 32 is continuous with the first flank portion 31. The second flank portion 32 may be inclined with respect to the first flank portion 31. The second flank portion 32 is located rearward of the first flank portion 31 in the rotational direction.

[0012] The drill 1 according to the first embodiment may further have a second cutting edge 13, a second flank 20, and a second outer peripheral surface 80. In the radial direction, the second cutting edge 13 is located outward from the first cutting edge 10. The second cutting edge 13 is spaced apart from the first cutting edge 10. In the radial direction, the second flank 20 is located outward from the first flank 30. The second flank 20 is spaced apart from the first flank 30. In the radial direction, the second outer peripheral surface 80 is located outward from the first outer peripheral surface 70. The second outer peripheral surface 80 is spaced apart from the first outer peripheral surface 70.

[0013] 1, the drill 1 according to the first embodiment has two first cutting edges 10, two first flanks 30, two thinning surfaces 50, two recessed surfaces 60, two second cutting edges 13, and two second flanks 20. When viewed in the direction along the axis A, the two first cutting edges 10, the two first flanks 30, the two thinning surfaces 50, the two recessed surfaces 60, the two second cutting edges 13, and the two second flanks 20 may have a shape that is two-fold symmetric with the axis A as the center of rotation.

[0014] As shown in FIG. 1 , the first flank surface 30 has a trailing edge 90 located rearward of the first cutting edge 10 in the rotational direction. The trailing edge 90 of the first flank surface 30 is located forward of the thinning surface 50 and the recessed surface 60 in the rotational direction. The trailing edge 90 has a first boundary line portion 53 and a second boundary line portion 63. The first flank surface 30 is continuous with the thinning surface 50 at the first boundary line portion 53. The first flank surface 30 is continuous with the recessed surface 60 at the second boundary line portion 63. When viewed along the axis A, the second boundary line portion 63 may extend along the first boundary line portion 53. The second boundary line portion 63 may be continuous with the first boundary line portion 53.

[0015] FIG. 2 is a schematic side view showing the configuration of the drill 1 according to the first embodiment. As shown in FIG. 2, the drill 1 has a front end 5 and a rear end 6. An axis A extends from the front end 5 along the rear end 6. The drill 1 has a main body 8 and a shank 7. The front end 5 is formed by the main body 8. A chip discharge flute surface 4 is formed in the main body 8. The shank 7 is continuous with the main body 8. The rear end 6 is formed by the shank 7. The shank 7 does not have a chip discharge flute surface 4.

[0016] The direction from the front end 5 to the rear end 6 is defined as the rearward axial direction. The direction from the rear end 6 to the front end 5 is defined as the forward axial direction. The shank portion 7 is located rearward relative to the main body portion 8 in the axial direction.

[0017] The body portion 8 has a first body region 81 and a second body region 82. The second body region 82 is continuous with the first body region 81. In the direction along the axis A, the second body region 82 is located between the first body region 81 and the shank portion 7. The first cutting edge 10, the thinning surface 50, the recessed surface 60, the first flank surface 30, and the first outer peripheral surface 70 are formed by the first body region 81. The second cutting edge 13, the second flank surface 20, and the second outer peripheral surface 80 are formed by the second body region 82.

[0018] As shown in FIG. 1 , the diameter of the first cutting edge 10 is defined as a first diameter D1. When viewed in a direction along the axis A, the first diameter D1 is twice the distance between the outer circumferential end of the first cutting edge 10 and the axis A. The diameter of the second cutting edge 13 is defined as a second diameter D2. When viewed in a direction along the axis A, the second diameter D2 is twice the distance between the outer circumferential end of the second cutting edge 13 and the axis A. The second diameter D2 is larger than the first diameter D1. The second diameter D2 may be 1.3 times or more the first diameter D1, or may be 1.6 times or more the first diameter D1. The second diameter D2 may be 2.2 times or less the first diameter D1, or may be 2 times or less the first diameter D1.

[0019] 3 is a schematic perspective view showing a portion of the first body region 81 of the drill 1 according to the first embodiment. As shown in FIG. 3, the chip flute surface 4 is continuous with the major cutting edge portion 11. The major cutting edge portion 11 is formed by the ridgeline between the chip flute surface 4 and the first flank face 30. A portion of the chip flute surface 4 functions as a rake face.

[0020] The thinning surface 50 is continuous with the chip discharge groove surface 4. The thinning surface 50 has a first thinning surface portion 51 and a second thinning surface portion 52. The first thinning surface portion 51 is continuous with the thinning cutting edge portion 12. The second thinning surface portion 52 is continuous with the first thinning surface portion 51. The second thinning surface portion 52 is spaced apart from the thinning cutting edge portion 12. In the radial direction, the second thinning surface portion 52 may be located outward of the first thinning surface portion 51.

[0021] The receding surface 60 is continuous with the chip discharge groove surface 4. The receding surface 60 has a first receding surface portion 61 and a second receding surface portion 62. The first receding surface portion 61 is continuous with the second thinning surface portion 52. The first receding surface portion 61 may be located outward from the second thinning surface portion 52 in the radial direction. The second receding surface portion 62 is continuous with the first receding surface portion 61. The second receding surface portion 62 may be located outward from the first receding surface portion 61 in the radial direction. The second receding surface portion 62 is spaced apart from the second thinning surface portion 52.

[0022] The first outer peripheral surface 70 has a first margin portion 71, a second margin portion 72, and an outer peripheral end face portion 73. The first margin portion 71 is continuous with each of the first flank surface portion 31, the first cutting edge 10, and the chip discharge groove surface 4. The second margin portion 72 is located rearward of the first margin portion 71 in the rotational direction. The second margin portion 72 is continuous with the second flank surface portion 32. The outer peripheral end face portion 73 is continuous with each of the first margin portion 71 and the second margin portion 72. In the radial direction, each of the first margin portion 71 and the second margin portion 72 is located outward of the outer peripheral end face portion 73.

[0023] As shown in FIG. 3 , the first boundary line portion 53 has a first boundary region 54 and a second boundary region 55. The first boundary region 54 is the boundary between the thinning surface 50 and the first flank portion 31. The second boundary region 55 is the boundary between the thinning surface 50 and the second flank portion 32. Similarly, the second boundary line portion 63 has a third boundary region 64 and a fourth boundary region 65. The third boundary region 64 is the boundary between the first receding surface portion 61 and the second flank portion 32. The fourth boundary region 65 is the boundary between the second receding surface portion 62 and the second flank portion 32. The fourth boundary region 65 is located on an extension of the second boundary region 55.

[0024] FIG. 4 is a schematic cross-sectional view taken along line IV-IV in FIG. 1. The cross section shown in FIG. 4 is parallel to and includes the axis A. The cross section shown in FIG. 4 intersects the thinning surface 50, the recessed surface 60, and the opening edge 3 of the coolant supply hole 2. In the cross section shown in FIG. 4, the recessed surface 60 is located axially rearward of the thinning surface 50. The opening edge 3 of the coolant supply hole 2 on the recessed surface 60 has a first position 41 and a second position 42. In the direction along the axis A, the first position 41 is located axially forward of the second position 42. In the direction along the axis A, the first position 41 is located between the front end 5 of the drill 1 and the second position 42. In the radial direction, the second position 42 is located outward of the first position 41.

[0025] A line passing through the first position 41 and the second position 42 is defined as a first line L1. In the cross section shown in FIG. 4, the angle formed by the axis A and the first line L1, which is 90° or less, is defined as a first angle θ1. In the cross section shown in FIG. 4, the tangent to the thinning surface 50 at the boundary between the thinning surface 50 and the receding surface 60 is defined as a second line L2. In the cross section shown in FIG. 4, the angle formed by the axis A and the second line L2, which is 90° or less, is defined as a second angle θ2. The first angle θ1 is smaller than the second angle θ2.

[0026] The first angle θ1 is, for example, not less than 0° and not more than 45°. The first angle θ1 may be not less than 10°, not less than 15°, not less than 20°, not less than 25°, or not less than 28°. The first angle θ1 may be not more than 40°, or not more than 34°. The first angle θ1 may be not less than 28° and not more than 34°.

[0027] 5 is an enlarged schematic view of region V in FIG. 2. As shown in FIG. 5, the front end of the coolant supply hole 2 in the direction parallel to the axis A is defined as a third position 43. The rear end of the coolant supply hole 2 in the direction parallel to the axis A is defined as a fourth position 44. The distance between the front end 5 of the drill 1 and the third position 43 in the direction parallel to the axis A is defined as a first distance W1. The distance between the third position 43 and the fourth position 44 in the direction parallel to the axis A is defined as a second distance W2.

[0028] The value obtained by dividing the first distance W1 by the first diameter D1 of the first cutting edge 10 is, for example, 0.1 or more and 0.7 or less. The value obtained by dividing the first distance W1 by the first diameter D1 may be 0.2 or more, or 0.3 or more. The value obtained by dividing the first distance W1 by the first diameter D1 may be 0.6 or less, or 0.5 or less. The value obtained by dividing the first distance W1 by the first diameter D1 may be 0.2 or more and 0.7 or less, or 0.1 or more and 0.6 or less.

[0029] The value obtained by dividing the second distance W2 by the first diameter D1 of the first cutting edge 10 is, for example, 0.05 or more and 1.08 or less. The value obtained by dividing the second distance W2 by the first diameter D1 may be 0.1 or more, or 0.2 or more. The value obtained by dividing the second distance W2 by the first diameter D1 may be 1.00 or less, or 0.95 or less. The value obtained by dividing the second distance W2 by the first diameter D1 may be, for example, 0.1 or more and 1.08 or less, or 0.05 or more and 0.1 or less.

[0030] Although the drill 1 according to the first embodiment has the first cutting edge 10 and the second cutting edge 13, the present disclosure is not limited to the above configuration. The drill 1 according to the present disclosure may have the first cutting edge 10 and not have the second cutting edge 13.

[0031] (Second embodiment) Next, the configuration of the drill 1 according to the second embodiment will be described. The drill 1 according to the second embodiment differs from the drill 1 according to the first embodiment mainly in that the fourth boundary region 65 is not located on an extension of the second boundary region 55, but other configurations are substantially the same as those of the drill 1 according to the first embodiment. The following description will focus on the configurations that differ from the drill 1 according to the first embodiment.

[0032] Fig. 6 is a schematic front view showing the configuration of a drill according to the second embodiment. As shown in Fig. 6, when viewed along the axis A, the fourth boundary region 65 does not have to be located on an extension of the second boundary region 55. The fourth boundary region 65 may be located forward of the second boundary region 55 in the rotational direction.

[0033] 7 is a schematic perspective view showing a portion of the first body region 81 of the drill 1 according to the second embodiment. As shown in FIG. 7, the fourth boundary region 65 may be located forward of the third boundary region 64 in the rotational direction. The third boundary region 64 may be located forward of the second boundary region 55 in the rotational direction.

[0034] (Third embodiment) Next, the configuration of the drill 1 according to the third embodiment will be described. The drill 1 according to the third embodiment differs from the drill 1 according to the first embodiment mainly in that the thinning surface 50 is continuous with the first outer peripheral surface 70, but other configurations are substantially the same as those of the drill 1 according to the first embodiment. The following description will focus on the configurations that differ from the drill 1 according to the first embodiment.

[0035] FIG. 8 is a schematic front view showing the configuration of the drill 1 according to the third embodiment. FIG. 9 is a schematic perspective view showing a portion of the first body region 81 of the drill 1 according to the third embodiment. As shown in FIGS. 8 and 9 , the thinning surface 50 is continuous with the first outer peripheral surface 70. The recessed surface 60 is spaced from the first flank surface 30. A portion of the thinning surface 50 is located between the second flank surface portion 32 and the recessed surface 60.

[0036] As shown in Fig. 8 , when viewed in the direction along the axis A, the third boundary line portion 91, which is the boundary between the second receding surface portion 62 and the thinning surface 50, may be located rearward in the rotational direction from the first boundary line portion 53, which is the boundary between the thinning surface 50 and the second flank surface portion 32. As shown in Fig. 9 , the outer peripheral edge of the third boundary line portion 91, which is the boundary between the second receding surface portion 62 and the thinning surface 50, may be located rearward in the axial direction from the outer peripheral edge of the first boundary line portion 53, which is the boundary between the thinning surface 50 and the second flank surface portion 32.

[0037] Next, the effects of the drill 1 according to this embodiment will be described. When drilling with the drill 1, a core hole (pilot hole) having a bottom surface may first be formed, and then drilling may be performed to enlarge the core hole. In the initial stage of drilling, the core hole is enlarged mainly by cutting the side wall surface of the core hole with the outer peripheral edge of the cutting edge.

[0038] When a conventional drill is used to drill the sidewall of a blind core hole, chips removed by the outer circumferential edge of the cutting edge can become trapped between the sidewall of the core hole and the outer circumferential surface of the drill 1. The trapped chips are pressed against the sidewall of the core hole by the outer circumferential surface of the drill 1, and are essentially fixed in place. As the drill 1 continues to rotate, the coolant supply hole 2, located behind the cutting edge in the direction of rotation, approaches the trapped chips. As a result, the trapped chips can become trapped between the nearby coolant supply holes 2.

[0039] As the drill 1 moves further downward in the axial direction, it begins to cut the bottom surface of the core hole. The bottom surface of the core hole is cut mainly by the cutting edges located toward the center of the drill 1 (specifically, the thinning cutting edge portion 12 and the main cutting edge portion 11). The chips cut by the thinning cutting edge portion 12 and the main cutting edge portion 11 pass through the thinning surface 50 and the chip discharge groove surface 4 and approach the coolant supply hole 2 located forward in the direction of rotation. As a result, the chips may become caught in the coolant supply hole 2.

[0040] The drill 1 according to this embodiment has a thinning surface 50 and a recessed surface 60. A coolant supply hole 2 is provided on the recessed surface 60. In a cross section parallel to and including the axis A, the recessed surface 60 is located axially rearward of the thinning surface 50. This prevents chips from becoming trapped in the coolant supply hole 2. In particular, in high-efficiency machining, chips are difficult to break up and tend to become long. Even in such cases, chips can be prevented from becoming trapped in the coolant supply hole 2.

[0041] Furthermore, in the drill 1 according to this embodiment, in a cross section that is parallel to and includes the axis A, the opening edge 3 of the coolant supply hole 2 on the receding surface 60 has a first position 41 and a second position 42. In the cross section that is parallel to and includes the axis A, if the angle between the axis A and a line that passes through the first position 41 and the second position 42 and that is 90° or less is defined as a first angle θ1, and the angle between the axis A and a tangent to the thinning surface 50 at the boundary between the thinning surface 50 and the receding surface 60 and that is 90° or less is defined as a second angle θ2, the first angle θ1 is smaller than the second angle θ2.

[0042] When the first angle θ1 is the same as the second angle θ2, chips that have flowed along the thinning surface 50 flow directly toward the coolant supply hole 2 formed in the receding surface 60, making it easier for the chips to enter the coolant supply hole 2. On the other hand, when the first angle θ1 is smaller than the second angle θ2, the direction in which the chips flow can be changed to a direction different from the direction toward the coolant supply hole 2. This makes it possible to prevent the chips from becoming caught in the coolant supply hole 2.

[0043] According to the drill 1 of this embodiment, the first angle θ1 may be equal to or greater than 0° and equal to or less than 45°. This increases the opening area of ​​the coolant supply hole 2. This further prevents chips from getting caught in the coolant supply hole 2.

[0044] According to the drill 1 of this embodiment, if the distance between the front end 5 of the drill 1 and the front end 5 of the coolant supply hole 2 in the direction parallel to the axis A is defined as a first distance W1, the value obtained by dividing the first distance W1 by the diameter of the drill 1 may be 0.1 or more and 0.7 or less. Setting the value obtained by dividing the first distance W1 by the diameter of the drill 1 to 0.1 or more can prevent chips from becoming caught in the coolant supply hole 2. Setting the value obtained by dividing the first distance W1 by the diameter of the drill 1 to 0.7 or less can allow a sufficient amount of coolant to be supplied to the cutting edge, thereby effectively cooling the cutting edge.

[0045] In the drill 1 according to this embodiment, if the distance between the front end 5 of the coolant supply hole 2 and the rear end 6 of the coolant supply hole 2 in the direction parallel to the axis A is defined as the second distance W2, the value obtained by dividing the second distance W2 by the diameter of the drill 1 may be 0.05 or more and 1.08 or less. By setting the value obtained by dividing the second distance W2 by the diameter of the drill 1 to 0.05 or more, the amount of coolant supplied can be increased. By setting the value obtained by dividing the second distance W2 by the diameter of the drill 1 to 1.08 or less, high strength can be maintained. [Example]

[0046] Drilling was performed using the drill 1 according to the first embodiment. The drill 1 was made of cemented carbide. The workpiece was aluminum. First, a pilot hole was formed in the workpiece. The pilot hole had a depth of 20.7 mm. The peripheral speed (Vc) of the cutting edge during pilot hole drilling was 120 m / min. The coolant pressure was 1 MPa.

[0047] Next, drilling was performed to enlarge the pilot hole. The rotation speed of Drill 1 was 10,000 revolutions per minute. The peripheral speed of the cutting edge (Vc) was 231 m / min. The feed rate per tooth (f) was 0.4 mm / revolution when the hole depth was between 0 mm and 1.8 mm. The feed rate per tooth (f) was 1.2 mm / revolution when the hole depth was between 1.8 mm and 24.1 mm.

[0048] After the drilling was completed, it was confirmed that no chips were trapped in the coolant supply holes 2 of the drill 1. As described above, it was confirmed that the drill 1 according to this embodiment can prevent chips from being trapped in the coolant supply holes 2 during high-efficiency drilling in which the feed rate (f) per tooth is 1 mm / revolution or more.

[0049] 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. [Explanation of symbols]

[0050] 1 drill, 2 coolant supply hole, 3 opening edge, 4 chip discharge groove surface, 5 front end, 6 rear end, 7 shank portion, 8 main body portion, 10 first cutting edge, 11 main cutting edge portion, 12 thinning cutting edge portion, 13 second cutting edge, 20 second flank face, 30 first flank face, 31 first flank face portion, 32 second flank face portion, 41 first position, 42 second position, 43 third position, 44 fourth position, 50 thinning surface, 51 first thinning surface portion, 52 second thinning surface portion, 53 first boundary portion, 54 first boundary area, 55 second boundary area, 60 setback surface, 61 first setback surface portion, 62 second setback surface portion, 63 second boundary portion, 64 third boundary area, 65 fourth boundary area, 70 first outer peripheral surface, 71 first margin portion, 72 second margin portion, 73 Outer peripheral end surface, 80 Second outer peripheral surface, 81 First main body area, 82 Second main body area, 90 Rear edge, 91 Third boundary line, A axis, D1 first diameter, D2 second diameter, L1 first straight line, L2 second straight line, W1 first distance, W2 second distance, θ1 first angle, θ2 second angle.

Claims

1. A drill that rotates around an axis, a cutting edge having a main cutting edge portion and a thinning cutting edge portion connected to the main cutting edge portion; a thinning surface connected to the thinning cutting edge portion; a recessed surface continuous with the thinning surface; a chip discharge groove surface connected to each of the thinning surface and the recessed surface, The retreating surface is provided with a coolant supply hole, In a cross section parallel to and including the axis, the recessed surface is located axially rearward of the thinning surface, an opening edge of the coolant supply hole on the receding surface has a first position and a second position; a first angle is an angle formed by the axis and a line passing through the first position and the second position, the angle being equal to or less than 90°; When a second angle is defined as an angle formed by the axis and a tangent to the thinning surface at the boundary between the thinning surface and the receding surface, and the angle is 90° or less, the first angle is smaller than the second angle, A drill, wherein the first angle is greater than or equal to 0° and less than or equal to 45°.

2. A drill that rotates around an axis, a cutting edge having a main cutting edge portion and a thinning cutting edge portion connected to the main cutting edge portion; a thinning surface connected to the thinning cutting edge portion; a recessed surface continuous with the thinning surface; a chip discharge groove surface connected to each of the thinning surface and the recessed surface, The retreating surface is provided with a coolant supply hole, In a cross section parallel to and including the axis, the recessed surface is located axially rearward of the thinning surface, an opening edge of the coolant supply hole on the receding surface has a first position and a second position; a first angle is an angle formed by the axis and a line passing through the first position and the second position, the angle being equal to or less than 90°; When a second angle is defined as an angle formed by the axis and a tangent to the thinning surface at the boundary between the thinning surface and the receding surface, and the angle is 90° or less, the first angle is smaller than the second angle, A drill, wherein when a distance between a front end of the drill and a front end of the coolant supply hole in a direction parallel to the axis is defined as a first distance, a value obtained by dividing the first distance by a diameter of the cutting edge is 0.1 or more and 0.7 or less.

3. A drill that rotates around an axis, a cutting edge having a main cutting edge portion and a thinning cutting edge portion connected to the main cutting edge portion; a thinning surface connected to the thinning cutting edge portion; a recessed surface continuous with the thinning surface; a chip discharge groove surface connected to each of the thinning surface and the recessed surface, The retreating surface is provided with a coolant supply hole, In a cross section parallel to and including the axis, the recessed surface is located axially rearward of the thinning surface, an opening edge of the coolant supply hole on the receding surface has a first position and a second position; a first angle is an angle formed by the axis and a line passing through the first position and the second position, the angle being equal to or less than 90°; When a second angle is defined as an angle formed by the axis and a tangent to the thinning surface at the boundary between the thinning surface and the receding surface, and the angle is 90° or less, the first angle is smaller than the second angle, a drill, wherein a value obtained by dividing a distance between a front end of the coolant supply hole and a rear end of the coolant supply hole in a direction parallel to the axis and a diameter of the cutting edge is 0.05 or more and 1.08 or less, where the distance is a second distance.

4. A drill that rotates around an axis, a cutting edge having a main cutting edge portion and a thinning cutting edge portion connected to the main cutting edge portion; a thinning surface connected to the thinning cutting edge portion; a recessed surface continuous with the thinning surface; a chip discharge groove surface connected to each of the thinning surface and the recessed surface, The retreating surface is provided with a coolant supply hole, In a cross section parallel to and including the axis, the recessed surface is located axially rearward of the thinning surface, an opening edge of the coolant supply hole on the receding surface has a first position and a second position; a first angle is an angle formed by the axis and a line passing through the first position and the second position, the angle being equal to or less than 90°; When a second angle is defined as an angle formed by the axis and a tangent to the thinning surface at the boundary between the thinning surface and the receding surface, and the angle is 90° or less, the first angle is smaller than the second angle, the first angle is greater than or equal to 0° and less than or equal to 45°, a first distance is a distance between a front end of the drill and a front end of the coolant supply hole in a direction parallel to the axis; When the distance between the front end of the coolant supply hole and the rear end of the coolant supply hole in the direction parallel to the axis is defined as a second distance, A drill, wherein a value obtained by dividing the first distance by the diameter of the cutting edge is equal to or greater than 0.1 and equal to or less than 0.7, and a value obtained by dividing the second distance by the diameter of the cutting edge is equal to or greater than 0.05 and equal to or less than 1.08.