JP7206573B1 - Drill - Google Patents

Abstract

The drill has a cutting edge, a helical flute surface, a first peripheral margin surface, and an approach surface. The helical flute surface is continuous with the cutting edge. The first outer peripheral margin surface is positioned behind the outermost peripheral end of the cutting edge in the rotational direction and has a diameter larger than the diameter of the cutting edge. The approach surface is located between the first outer peripheral margin surface and the twist groove surface, continues to the outermost periphery, and is formed along the leading edge of the twist groove surface. When viewed along the axis, the approach surface is inclined with respect to the first outer peripheral margin surface. The length of the approach surface in the direction parallel to the axis is at least 0.5 times the diameter of the first peripheral margin surface.

Description

The present disclosure relates to drills.

Japanese Patent Laying-Open No. 6-15512 (Patent Document 1) describes a drill having a margin portion.

JP-A-6-15512

A drill according to the present disclosure is a drill that rotates about an axis and includes a cutting edge, a helical flute surface, a first peripheral margin surface, and an approach surface. The helical flute surface is continuous with the cutting edge. The first outer peripheral margin surface is positioned behind the outermost peripheral end of the cutting edge in the rotational direction and has a diameter larger than the diameter of the cutting edge. The approach surface is located between the first outer peripheral margin surface and the twist groove surface, continues to the outermost periphery, and is formed along the leading edge of the twist groove surface. When viewed along the axis, the approach surface is inclined with respect to the first outer peripheral margin surface. The length of the approach surface in the direction parallel to the axis is at least 0.5 times the diameter of the first peripheral margin surface.

FIG. 1 is a schematic plan view showing the configuration of a drill according to the first embodiment. FIG. 2 is a schematic front view showing the configuration of the drill according to the first embodiment. 3 is an enlarged front view of region III of FIG. 2; FIG. FIG. 4 is a schematic perspective view showing the front end portion of the drill according to the first embodiment. FIG. 5 is an enlarged schematic diagram of region V in FIG. FIG. 6 is a schematic diagram showing a state in which the cutting edge is rotationally projected onto a rotational projection plane including the axis when the drill is rotated about the axis. FIG. 7 is a schematic cross-sectional view taken along line VII-VII in FIG. FIG. 8 is a schematic front view showing the configuration of a drill according to the second embodiment. FIG. 9 is a schematic plan view showing the configuration of a drill according to the second embodiment. FIG. 10 shows the diameter of the hole formed using the drill according to sample 1. FIG. FIG. 11 shows the diameter of the hole formed using the drill according to sample 2. As shown in FIG.

[Problems to be Solved by the Present Disclosure]
An object of the present disclosure is to provide a drill capable of highly accurate hole drilling.

[Effect of the present disclosure]
According to the present disclosure, it is possible to provide a drill capable of highly accurate drilling.

[Outline of Embodiment of Present Disclosure]
First, an outline of an embodiment of the present disclosure will be described.

(1) A drill 100 according to the present disclosure is a drill 100 that rotates around an axis X and includes a cutting edge 3, a helical groove surface 5, a first peripheral margin surface 10, and an approach surface 8. ing. The helical groove surface 5 continues to the cutting edge 3 . The first outer peripheral margin surface 10 is positioned behind the outermost peripheral end of the cutting edge 3 in the rotational direction and has a diameter larger than the diameter of the cutting edge 3 . The approach surface 8 is located between the first outer peripheral margin surface 10 and the twist groove surface 5 , continues to the outermost peripheral end, and is formed along the leading edge 7 of the twist groove surface 5 . When viewed along the axis X, the approach surface 8 is inclined with respect to the first outer peripheral margin surface 10 . The length of the approach surface 8 in the direction parallel to the axis X is 0.5 times or more the diameter of the first outer peripheral margin surface 10 .

(2) According to the drill 100 according to (1) above, the value obtained by subtracting the diameter of the cutting edge 3 from the diameter of the first outer peripheral margin surface 10 may be 0.01 mm or more and 0.08 mm or less. When viewed in the direction along the axis X, the width of the approach surface 8 may be 0.1 mm or more and 0.4 mm or less.

(3) According to the drill 100 according to (1) or (2) above, the angle of inclination of the approach surface 8 with respect to the first outer peripheral margin surface 10 when viewed in the direction along the axis X is 3° or more and 15° or less. may be

(4) According to the drill 100 according to any one of (1) to (3) above, the core thickness of the drill 100 may be 28% or more and 40% or less of the diameter of the first outer peripheral margin surface 10 . In a cross section perpendicular to the axis X, the central angle of the twisted groove surface 5 may be 0.5 times or more and 1 time or less than the central angle of the portion other than the twisted groove surface 5 .

(5) According to the drill 100 according to (4) above, the second outer peripheral margin surface 20 is further provided, which is spaced apart from the first outer peripheral margin surface 10 and positioned behind the first outer peripheral margin surface 10 in the rotational direction. may When viewed in the direction along the axis X, the width of each of the first outer peripheral margin surface 10 and the second outer peripheral margin surface 20 may be 5% or more and 20% or less of the diameter of the first outer peripheral margin surface 10 . In the direction parallel to the axis X, the front end of the second outer peripheral margin surface 20 may be positioned axially rearward of the front end of the first outer peripheral margin surface 10 . The recession amount of the second outer peripheral margin surface 20 with respect to the first outer peripheral margin surface 10 may be 2% or more and 10% or less of the diameter of the first outer peripheral margin surface 10 .

(6) According to the drill 100 according to (5) above, the flank 40 connected to the cutting edge 3 and the outer peripheral intermediate surface 4 between the first outer peripheral margin surface 10 and the second outer peripheral margin surface 20 are provided. You may have more. The flank 40 includes a first flank portion 43 and a first chamfered surface portion 41 that is located on the outer peripheral side of the first flank portion 43, is inclined with respect to the first flank portion 43, and continues to the first flank portion 43. and The first chamfer surface portion 41 may continue to the outer peripheral intermediate surface 4 .

(7) According to the drill 100 according to (6) above, the flank 40 includes the second flank 44 located behind the first flank 43 in the rotational direction and continuous with the first flank 43, It may have a second chamfer surface portion 42 located rearward in the rotational direction from the second flank portion 44 and continuing to the second outer peripheral margin surface 20 .

(8) The drill 100 according to any one of (1) to (5) above may further include a flank 40 that continues to the cutting edge 3 . The flank 40 includes a first flank portion 43 and a first chamfered surface portion 41 that is located on the outer peripheral side of the first flank portion 43, is inclined with respect to the first flank portion 43, and continues to the first flank portion 43. and The cutting edge 3 may have a main cutting edge portion 32 connected to the first flank portion 43 and a chamfered cutting edge portion 33 connected to the first chamfered surface portion 41 . When the drill 100 is rotated around the axis X, the rotational trajectory of the axis X and the rotational trajectory of the chamfered cutting edge portion 33 form a rotation projection plane in which the cutting edge 3 is projected onto a plane containing the axis X. The angle may be greater than or equal to 15° and less than or equal to 45°.

(9) According to the drill 100 according to (8) above, the length of the chamfer cutting edge portion 33 in the direction parallel to the axis X is 3% or more and 10% or less of the diameter of the first outer peripheral margin surface 10. may

(10) The drill 100 according to any one of (1) to (5) above may further include a flank 40 that continues to the cutting edge 3 . A coolant supply hole 30 may be provided in the flank 40 .

(11) The drill 100 according to (1) above further includes the second outer peripheral margin surface 20 that is spaced apart from the first outer peripheral margin surface 10 and positioned behind the first outer peripheral margin surface 10 in the rotational direction. may A value obtained by subtracting the diameter of the cutting edge 3 from the diameter of the first outer peripheral margin surface 10 may be 0.01 mm or more and 0.08 mm or less. When viewed in the direction along the axis X, the width of the approach surface 8 may be 0.1 mm or more and 0.4 mm or less. When viewed in the direction along the axis X, the inclination angle of the approach surface 8 with respect to the first outer peripheral margin surface 10 may be 3° or more and 15° or less. When viewed in the direction along the axis X, the width of each of the first outer peripheral margin surface 10 and the second outer peripheral margin surface 20 may be 5% or more and 20% or less of the diameter of the first outer peripheral margin surface 10 . In the direction parallel to the axis X, the front end of the second outer peripheral margin surface 20 is located axially rearward than the front end of the first outer peripheral margin surface 10, and the second outer peripheral margin surface is positioned relative to the first outer peripheral margin surface 10. The recession amount of 20 may be 2% or more and 10% or less of the diameter of the first outer peripheral margin surface 10 .

[Details of the embodiment of the present disclosure]
Hereinafter, details of an embodiment of the present disclosure (hereinafter also referred to as the present embodiment) will be described based on the drawings. In the drawings below, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

(First embodiment)
First, the configuration of the drill 100 according to the first embodiment will be described. FIG. 1 is a schematic plan view showing the configuration of a drill 100 according to the first embodiment. As shown in FIG. 1, the drill 100 according to the first embodiment includes a front end 1, a rear end 2, a flank 40, a thinning surface 6, an outer peripheral surface 9, a twist groove surface 5, and a shank 17. It mainly has A drill 100 according to the first embodiment is a drill 100 for metal working. As shown in FIG. 1, the outer peripheral surface 9 is spirally provided around the axis X. As shown in FIG. The outer peripheral surface 9 continues to the twisted groove surface 5 . The twisted groove surface 5 constitutes a flute. The twisted groove surface 5 is spirally provided around the axis X. As shown in FIG. The cutting edge 3 is provided near the front end 1 of the drill 100 .

A front end 1 of the drill 100 is a portion facing the work material. A rear end 2 of the drill 100 is a portion facing a tool spindle that rotates the drill 100 . The shank 17 is the part attached to the tool spindle. An axis X passes through the front end 1 and the rear end 2 . Drill 100 rotates about axis X. The direction along the axis X is the axial direction. The direction perpendicular to the axial direction is the radial direction. The direction from the front end 1 to the rear end 2 is referred to herein as axially rearward. Conversely, the direction from the rear end 2 to the front end 1 is referred to as axially forward. A direction parallel to the radial direction and away from the axis X is called an outer peripheral side.

FIG. 2 is a schematic front view showing the configuration of the drill 100 according to the first embodiment. As shown in FIG. 2 , the flank 40 continues to the cutting edge 3 . A ridge line between the flank surface 40 and the helical groove surface 5 constitutes the cutting edge 3 . The helical groove surface 5 close to the cutting edge 3 functions as a rake surface. The flank 40 has a first flank portion 43 , a first chamfered surface portion 41 , a second flank portion 44 and a second chamfered surface portion 42 .

The first flank portion 43 continues to the cutting edge 3 . The first chamfer surface portion 41 continues to the first flank portion 43 . The first chamfer surface portion 41 is located on the outer peripheral side of the first flank surface portion 43 . The first chamfer surface portion 41 is inclined with respect to the first flank portion 43 . The second flank portion 44 is positioned behind the first flank portion 43 in the rotational direction. The second flank portion 44 continues to the first flank portion 43 . The second flank portion 44 is inclined with respect to the first flank portion 43 . The second chamfer surface portion 42 is located rearward in the rotational direction of the second flank surface portion 44 . The second chamfer surface portion 42 continues to the second flank portion 44 . The second chamfer surface portion 42 is inclined with respect to the second flank portion 44 .

The outer peripheral surface 9 of the drill 100 has a first peripheral margin surface 10 , a second peripheral margin surface 20 , an intermediate peripheral surface 4 , a first side surface 11 and a second side surface 12 . The second outer peripheral margin surface 20 is separated from the first outer peripheral margin surface 10 . The second outer peripheral margin surface 20 is positioned behind the first outer peripheral margin surface 10 in the rotational direction. In the direction of rotation, the outer peripheral intermediate surface 4 is located between the first outer peripheral margin surface 10 and the second outer peripheral margin surface 20 . The first side surface 11 continues to each of the first outer peripheral margin surface 10 and the outer peripheral intermediate surface 4 . The first side surface 11 is located between the first outer peripheral margin surface 10 and the outer peripheral intermediate surface 4 in the radial direction. The second side surface 12 continues to each of the second outer peripheral margin surface 20 and the outer peripheral intermediate surface 4 . In the radial direction, the second side surface 12 is positioned between the second outer peripheral margin surface 20 and the outer peripheral intermediate surface 4 .

As shown in FIG. 2, the width of the first outer peripheral margin surface 10 when viewed in the direction along the axis X is a first width W1. The first width W1 is, for example, 5% or more and 20% or less of the diameter of the first outer peripheral margin surface 10 . When viewed in the direction along the axis X, the shape of the first outer peripheral margin surface 10 is arcuate. The width of the first outer peripheral margin surface 10 is the length of a line segment connecting both ends of the arc-shaped first outer peripheral margin surface 10 . The lower limit of the first width W1 is not particularly limited, but may be, for example, 7% or more of the diameter of the first outer peripheral margin surface 10, or may be 9% or more. The upper limit of the first width W1 is not particularly limited, but may be, for example, 18% or less of the diameter of the first outer peripheral margin surface 10, or 16% or less.

As shown in FIG. 2, when viewed in the direction along the axis X, the width of the second outer peripheral margin surface 20 is a second width W2. The second width W2 is, for example, 5% or more and 20% or less of the diameter of the first outer peripheral margin surface 10 . When viewed in the direction along the axis X, the shape of the second outer peripheral margin surface 20 is arcuate. The width of the second outer peripheral margin surface 20 is the length of a line segment connecting both ends of the arc-shaped second outer peripheral margin surface 20 . The lower limit of the second width W2 is not particularly limited, but may be, for example, 7% or more of the diameter of the first outer peripheral margin surface 10, or may be 9% or more. The upper limit of the second width W2 is not particularly limited, but may be, for example, 18% or less of the diameter of the first outer peripheral margin surface 10, or 16% or less.

The first outer peripheral margin surface 10 continues to the first chamfer surface portion 41 . The first chamfer surface portion 41 continues to each of the first flank portion 43 and the second flank portion 44 . The first chamfer surface portion 41 may continue to the outer peripheral intermediate surface 4 . The second outer peripheral margin surface 20 continues to the second chamfer surface portion 42 . The second chamfer surface portion 42 may continue to the outer peripheral intermediate surface 4 . A coolant supply hole 30 may be provided in the flank 40 . The coolant supply hole 30 may be open at the second flank portion 44 .

As shown in FIG. 2 , the cutting edge 3 continues to the helical groove surface 5 . The cutting edge 3 has a thinning cutting edge portion 31 , a main cutting edge portion 32 and a chamfered cutting edge portion 33 . The main cutting edge portion 32 continues to the thinning cutting edge portion 31 . The main cutting edge portion 32 is positioned on the outer peripheral side of the thinning cutting edge portion 31 . The chamfered cutting edge portion 33 continues to the main cutting edge portion 32 . The chamfer cutting edge portion 33 is positioned on the outer peripheral side of the main cutting edge portion 32 . The main cutting edge portion 32 continues to the first flank portion 43 . The chamfered cutting edge portion 33 continues to the first chamfered surface portion 41 .

3 is an enlarged front view of region III of FIG. 2; FIG. A drill 100 according to the first embodiment has an approach surface 8 . The approach surface 8 continues to the chamfer cutting edge portion 33 at the outermost peripheral end of the cutting edge 3 . As shown in FIG. 3 , the approach surface 8 is inclined with respect to the chamfer cutting edge portion 33 when viewed in the direction along the axis X. As shown in FIG. The approach surface 8 is located behind the chamfer cutting edge portion 33 in the rotational direction. The first outer peripheral margin surface 10 continues to the approach surface 8 . The first outer peripheral margin surface 10 is positioned behind the approach surface 8 in the rotational direction. The first outer peripheral margin surface 10 is positioned behind the outermost peripheral end of the cutting edge 3 in the rotational direction. The approach surface 8 is positioned between the outermost peripheral edge of the cutting edge 3 and the first peripheral margin surface 10 .

As shown in FIG. 3, the diameter of the cutting edge 3 when viewed along the axis X is a second diameter D2. The diameter of the first outer peripheral margin surface 10 is defined as a first diameter D1. The first diameter D1 is greater than the second diameter D2. Seen in the direction along the axis X, the second diameter D2 is twice the distance between the outermost peripheral edge of the cutting edge 3 and the axis X. When viewed along the axis X, the first diameter D1 is twice the distance between the first outer peripheral margin surface 10 and the axis X. As shown in FIG.

A value obtained by subtracting the second diameter D2 from the first diameter D1 is, for example, 0.01 mm or more and 0.08 mm or less. Although the lower limit of the value obtained by subtracting the second diameter D2 from the first diameter D1 is not particularly limited, it may be, for example, 0.02 mm or more, or 0.03 mm or more. Although the lower limit of the value obtained by subtracting the second diameter D2 from the first diameter D1 is not particularly limited, it may be, for example, 0.06 mm or less or 0.05 mm or less.

A boundary portion between the chamfer cutting edge portion 33 and the approach surface 8 when viewed in the direction along the axis X is defined as a first boundary portion 51 . In the direction of rotation, the first boundary 51 is the front end of the approach surface 8 . The first boundary portion 51 corresponds to the outermost peripheral edge of the cutting edge 3 . A boundary portion between the approach surface 8 and the first outer peripheral margin surface 10 when viewed in the direction along the axis X is defined as a second boundary portion 52 . In the direction of rotation, the second boundary 52 is the rear end of the approach surface 8 and the front end of the first outer peripheral margin surface 10 . A boundary portion between the first outer peripheral margin surface 10 and the first side surface 11 when viewed in the direction along the axis X is a third boundary portion 53 . In the rotational direction, the third boundary portion 53 is the rear end portion of the first outer peripheral margin surface 10 .

As shown in FIG. 3 , when viewed in the direction along the axis X, the approach surface 8 is inclined with respect to the first outer peripheral margin surface 10 . In other words, when viewed in the direction along the axis X, the straight line passing through the first boundary portion 51 and the second boundary portion 52 is inclined with respect to the tangent to the first outer peripheral margin surface 10 at the second boundary portion 52 . ing. When viewed along the axis X, the distance between the axis X and the second boundary portion 52 is greater than the distance between the axis X and the first boundary portion 51 .

The inclination angle of the approach surface 8 with respect to the first outer peripheral margin surface 10 when viewed in the direction along the axis X is a first angle θ1. Specifically, the first angle θ1 is the inclination angle of a straight line passing through the first boundary portion 51 and the second boundary portion 52 with respect to the tangent line of the first outer peripheral margin surface 10 at the second boundary portion 52 . The first angle θ1 is, for example, 3° or more and 15° or less. The lower limit of the first angle θ1 is not particularly limited, but may be, for example, 5° or more, or may be 7° or more. Although the upper limit of the first angle θ1 is not particularly limited, it may be, for example, 12° or less or 8° or less.

When viewed in a direction parallel to the axis X, the first width W1 is the length of a line segment connecting the second boundary portion 52 and the third boundary portion 53 . The width of the approach surface 8 when viewed in a direction parallel to the axis X is a fourth width W4. The fourth width W4 is the length of the line segment connecting the first boundary portion 51 and the second boundary portion 52 . When viewed in the direction along the axis X, the fourth width W4 is, for example, 0.1 mm or more and 0.4 mm or less. Although the lower limit of the fourth width W4 is not particularly limited, it may be, for example, 0.15 mm or more, or 0.20 mm or more. The upper limit of the fourth width W4 is not particularly limited, but may be, for example, 0.35 mm or less or 0.30 mm or less.

FIG. 4 is a schematic perspective view showing the front end portion of the drill 100 according to the first embodiment. As shown in FIG. 4 , the approach surface 8 is positioned between the first outer peripheral margin surface 10 and the twist groove surface 5 . The approach surface 8 continues to the outermost peripheral edge of the cutting edge 3 . An approach surface 8 is formed along the leading edge 7 of the torsion groove surface 5 . From another point of view, the leading edge 7 is formed by the ridgeline between the approach surface 8 and the twist groove surface 5 . The approach surface 8 extends from the first chamfer surface portion 41 toward the rear end 2 along the first outer peripheral margin surface 10 .

As shown in FIG. 1, the length of the approach surface 8 in the direction parallel to the axis X is a third length L3. The third length L3 is at least 0.5 times the first diameter D1. Although the lower limit of the third length L3 is not particularly limited, it may be, for example, one or more times the first diameter D1 or two or more times the first diameter D1. Although the upper limit of the third length L3 is not particularly limited, it may be, for example, 20 times or less the first diameter D1, or may be 10 times or less.

FIG. 5 is an enlarged schematic diagram of region V in FIG. As shown in FIG. 5 , in the direction parallel to the axis X, the front end of the second outer peripheral margin surface 20 is positioned axially rearward of the front end of the first outer peripheral margin surface 10 . In other words, the second peripheral margin surface 20 is located between the front end of the first peripheral margin surface 10 and the rear end 2 of the drill 100 . In the direction parallel to the axis X, the distance between the front end of the first outer peripheral margin surface 10 and the front end of the second outer peripheral margin surface 20 is set to the receding amount L1 of the second outer peripheral margin surface 20 with respect to the first outer peripheral margin surface 10 . The retreat amount L1 is, for example, 2% or more and 10% or less of the first diameter D1. The lower limit of the retreat amount L1 is not particularly limited, but may be, for example, 3% or more of the first diameter D1, or may be 4% or more. The upper limit of the retreat amount L1 is not particularly limited, but may be, for example, 9% or less of the first diameter D1, or may be 8% or less.

As shown in FIG. 5, the length of the chamfer cutting edge portion 33 in the direction parallel to the axis X is the second length L2. The second length L2 is, for example, 3% or more and 10% or less of the first diameter D1. The lower limit of the second length L2 is not particularly limited, but may be, for example, 4% or more of the first diameter D1 or 5% or more of the first diameter D1. The upper limit of the second length L2 is not particularly limited, but may be, for example, 9% or less of the first diameter D1 or 8% or less of the first diameter D1.

As shown in FIG. 5 , the thinning surface 6 is continuous with the twisted groove surface 5 . The thinning cutting edge portion 31 continues to the thinning surface 6 . As shown in FIGS. 4 and 5 , the ridge line between the thinning surface 6 and the first flank surface portion 43 constitutes the thinning cutting edge portion 31 . The helical groove surface 5 continues to each of the main cutting edge portion 32 and the chamfer cutting edge portion 33 . A ridge line between the helical groove surface 5 and the first flank surface portion 43 constitutes the main cutting edge portion 32 . A ridgeline between the twisted groove surface 5 and the first chamfered surface portion 41 constitutes a chamfered cutting edge portion 33 .

FIG. 6 is a schematic diagram showing a state in which the cutting edge 3 is rotationally projected onto a rotation projection plane including the axis X when the drill 100 is rotated around the axis X. As shown in FIG. As shown in FIG. 6 , the rotational projected trajectory 130 of the cutting edge 3 has a first projected trajectory 131 , a second projected trajectory 132 and a third projected trajectory 133 . The first projection trajectory 131 is a trajectory obtained by projecting the thinning cutting edge portion 31 onto the rotational projection plane. The second projection trajectory 132 is a trajectory obtained by projecting the main cutting edge portion 32 onto the rotational projection plane. A third projection trajectory 133 is a trajectory obtained by projecting the chamfered cutting edge portion 33 onto the rotational projection plane.

The angle formed by the projection trajectory 134 of the axis X and the third projection trajectory 133 of the chamfer cutting edge portion 33 on the rotational projection plane is a second angle θ2. The second angle θ2 is, for example, 15° or more and 45° or less. Although the lower limit of the second angle θ2 is not particularly limited, it may be, for example, 17° or more, or 19° or more. The upper limit of the second angle θ2 is not particularly limited, but may be, for example, 43° or less or 41° or less.

FIG. 7 is a schematic cross-sectional view taken along line VII-VII in FIG. The cross-section shown in FIG. 7 is perpendicular to axis X. FIG. The distance between the cross section shown in FIG. 7 and the front end 1 of the drill 100 in the direction along the axis X is the same as the first diameter D1.

As shown in FIG. 7, the drill 100 has a core thickness of a third diameter D3. The third diameter D3 is, for example, 28% or more and 40% or less of the first diameter D1. The lower limit of the third diameter D3 is not particularly limited, but may be, for example, 30% or more, or 32% or more of the first diameter D1. The upper limit of the third diameter D3 is not particularly limited, but may be, for example, 38% or less, or 36% or less. The core thickness of the drill 100 is twice the shortest distance between the axis X and the helical groove surface 5 in a cross section perpendicular to the axis X.

As shown in FIG. 7, in a cross section perpendicular to the axis X, the central angle of the twisted groove surface 5 is the first central angle θ3, and the central angle of the portion other than the twisted groove surface 5 is the second central angle θ4. The first central angle θ3 is formed by a line segment connecting the front end of the twist groove surface 5 in the rotational direction and the axis X, and a line segment connecting the rear end of the twist groove surface 5 in the rotation direction and the axis X. is the angle. The front end of the twist groove surface 5 in the rotational direction is the boundary between the second outer peripheral margin surface 20 and the twist groove surface 5 . The end of the twisted groove surface 5 in the rearward direction of rotation is the boundary between the approach surface 8 and the twisted groove surface 5 . When the number of cutting edges 3 is N, the second central angle θ4 is a value obtained by subtracting the first central angle θ3 from the value obtained by dividing 360° by N. When the number of cutting edges 3 is two, the second central angle θ4 is a value obtained by subtracting the first central angle θ3 from 180°.

In a cross section perpendicular to the axis X, the first central angle θ3 is, for example, 0.5 times or more and 1 time or less as large as the second central angle θ4. In the cross section perpendicular to the axis X, the lower limit of the first central angle θ3 is not particularly limited, but may be, for example, 0.55 times or more the second central angle θ4, or 0.60 times the second central angle θ4. It may be double or more. In the cross section perpendicular to the axis X, the upper limit of the first central angle θ3 is not particularly limited. It may be twice or less.

In the drill 100 according to the first embodiment, one cutting edge 3 is provided with a margin portion forming a first outer peripheral margin surface 10 and a margin portion forming a second outer peripheral margin surface 20 . Specifically, the drill 100 according to the first embodiment has two cutting edges 3, two approach surfaces 8, four margin portions, two helical groove surfaces 5, and two flank surfaces 40. have. Viewed in a direction along axis X, the shape of drill 100 is substantially rotationally symmetrical with respect to axis X. As shown in FIG. If the number of cutting edges of the drill 100 is N, the shape of the drill 100 is substantially N-fold symmetrical with respect to the axis X. When the number of cutting edges 3 of the drill 100 is two, the shape of the drill 100 is two-fold symmetrical with respect to the axis X.

(Second embodiment)
Next, the configuration of the drill 100 according to the second embodiment will be described. The drill 100 according to the second embodiment differs from the drill 100 according to the first embodiment in that it has a third outer peripheral margin surface 60, and in other respects it is substantially the same as the drill 100 according to the first embodiment. essentially the same. Hereinafter, the points different from the drill 100 according to the first embodiment will be mainly described.

FIG. 8 is a schematic front view showing the configuration of the drill 100 according to the second embodiment. The schematic front view shown in FIG. 8 corresponds to the schematic front view shown in FIG. As shown in FIG. 8, the drill 100 according to the second embodiment has a third peripheral margin surface 60. As shown in FIG. The third peripheral margin surface 60 is located between the first peripheral margin surface 10 and the second peripheral margin surface 20 in the rotational direction of the drill 100 . The third outer peripheral margin surface 60 is separated from each of the first outer peripheral margin surface 10 and the second outer peripheral margin surface 20 .

As shown in FIG. 8, when viewed in the direction along the axis X, the width of the third outer peripheral margin surface 60 is a third width W3. The third width W3 is, for example, 5% or more and 20% or less of the diameter of the first outer peripheral margin surface 10 . When viewed in the direction along the axis X, the shape of the third outer peripheral margin surface 60 is arcuate. The width of the third outer peripheral margin surface 60 is the length of a line segment connecting both ends of the arc-shaped third outer peripheral margin surface 60 .

FIG. 9 is a schematic plan view showing the configuration of a drill 100 according to the second embodiment. The schematic plan view shown in FIG. 9 corresponds to the schematic plan view shown in FIG. As shown in FIG. 9 , the outer peripheral surface 9 of the drill 100 according to the second embodiment has a third side surface 63 and a fourth side surface 64 . The third side surface 63 continues to the third outer peripheral margin surface 60 . The third side surface 63 is positioned forward in the rotational direction with respect to the third outer peripheral margin surface 60 . The fourth side surface 64 continues to the third outer peripheral margin surface 60 . The fourth side surface 64 is positioned rearward in the rotational direction with respect to the third outer peripheral margin surface 60 .

The outer peripheral intermediate surface 4 has a first intermediate area 61 and a second intermediate area 62 . The first intermediate region 61 continues to each of the first side surface 11 and the third side surface 63 . The first intermediate region 61 is positioned rearward in the rotational direction with respect to the first side surface 11 and is positioned forward in the rotational direction with respect to the third side surface 63 . The second intermediate region 62 continues to each of the second side surface 12 and the fourth side surface 64 . The second intermediate region 62 is positioned rearward in the rotational direction with respect to the fourth side surface 64 and is positioned forward in the rotational direction with respect to the second side surface 12 .

In the drill 100 according to the second embodiment, for one cutting edge 3, a margin portion forming the first outer peripheral margin surface 10, a margin portion forming the second outer peripheral margin surface 20, and a third outer peripheral margin surface 60 There is provided a margin portion that forms a Specifically, the drill 100 according to the second embodiment has two cutting edges 3, two approach surfaces 8, six margin portions, two helical groove surfaces 5, and two flank surfaces 40. have.

In addition, although the case where the drill 100 has two cutting edges 3 has been described above, the number of cutting edges 3 is not limited to two. The number of cutting edges 3 may be three, or may be four or more. The work material is metal such as stainless steel (SUS). The work material may be carbon steel, alloy steel, or a difficult-to-cut material.

Next, functions and effects of the drill 100 according to this embodiment will be described.
According to the drill 100 according to this embodiment, the first outer peripheral margin surface 10 is positioned rearward in the rotational direction from the outermost peripheral end of the cutting edge 3 and has a diameter larger than that of the cutting edge 3. . By varnishing the inner surface of the hole with the margin portion having the first outer peripheral margin surface 10, the hole diameter can be widened and the inner surface (hole surface) of the hole can be finished. Therefore, the roughness of the hole surface can be reduced. Further, according to the drill 100 according to this embodiment, it has the approach surface 8 that is inclined with respect to the first outer peripheral margin surface 10 when viewed in the direction along the axis X. As shown in FIG. The approach surface 8 is located between the first outer peripheral margin surface 10 and the twist groove surface 5 , continues to the outermost peripheral end, and is formed along the leading edge 7 of the twist groove surface 5 . As a result, the diameter gradually changes from the leading edge 7 to the first outer peripheral margin surface 10 compared to the case where the approach surface 8 is not provided. Therefore, it is possible to suppress welding of the work material to the outer peripheral margin surface due to frictional heat generated by the burnishing. The length of the approach surface 8 in the direction parallel to the axis X is 0.5 times or more the diameter of the first outer peripheral margin surface 10 . As a result, even when the cutting edge 3 is reground, the approach surface 8 can remain. Therefore, the life of the drill 100 can be extended.

Further, according to the drill 100 according to the present embodiment, the value obtained by subtracting the diameter of the cutting edge 3 from the diameter of the first outer peripheral margin surface 10 may be 0.01 mm or more and 0.08 mm or less. By setting the value obtained by subtracting the diameter of the cutting edge 3 from the diameter of the first outer peripheral margin surface 10 to 0.01 mm or more, the vanishing effect can be enhanced. Therefore, the roughness of the hole surface can be further reduced. By setting the value obtained by subtracting the diameter of the cutting edge 3 from the diameter of the first outer peripheral margin surface 10 to 0.08 mm or less, it is possible to suppress abrasion of the drill 100 due to a significant increase in frictional resistance due to varnishing. .

Furthermore, according to the drill 100 according to the present embodiment, the width of the approach surface 8 as viewed in the direction along the axis X may be 0.1 mm or more and 0.4 mm or less. By setting the width of the approach surface 8 to 0.1 mm or more, welding of chips can be further suppressed. By setting the width of the approach surface 8 to 0.4 mm or less, the peripheral margin surface can be provided at a position close to the cutting edge 3 . As a result, it is possible to suppress the deterioration of the precision of the hole diameter.

Furthermore, according to the drill 100 according to the present embodiment, the inclination angle of the approach surface 8 with respect to the first outer peripheral margin surface 10 when viewed in the direction along the axis X may be 3° or more and 15° or less. By setting the inclination angle of the approach surface 8 with respect to the first peripheral margin surface 10 to 3° or more, the difference between the diameter of the first peripheral margin surface 10 and the diameter of the cutting edge 3 can be increased. By setting the inclination angle of the approach surface 8 with respect to the first outer peripheral margin surface 10 to be 15° or less, the angle of the approach surface 8 with respect to the first outer peripheral margin surface 10 becomes excessively large, and welding of the work material occurs. can be suppressed.

Furthermore, according to the drill 100 according to this embodiment, the core thickness of the drill 100 may be 28% or more and 40% or less of the diameter of the cutting edge 3 . In a cross section perpendicular to the axis X, the central angle of the twisted groove surface 5 may be 0.5 times or more and 1 time or less than the central angle of the portion other than the twisted groove surface 5 . By increasing the core thickness of the drill 100, the rigidity of the drill 100 can be increased. By enlarging the center angle of the twisted groove surface 5, the chip discharging property can be improved. The core thickness of the drill 100 is 28% or more and 40% or less of the diameter of the first outer peripheral margin surface 10, and the central angle of the twisted groove surface 5 is 0.5 times or more than the central angle of the portion other than the twisted groove surface 51. By making it twice or less, it is possible to increase the rigidity of the drill 100 and improve the chip discharging performance.

Furthermore, according to the drill 100 according to this embodiment, when viewed in the direction along the axis X, the width of each of the first outer peripheral margin surface 10 and the second outer peripheral margin surface 20 is equal to the diameter of the first outer peripheral margin surface 10. It may be 5% or more and 20% or less. By setting the width of each of the first outer peripheral margin surface 10 and the second outer peripheral margin surface 20 to 5% or more of the diameter of the first outer peripheral margin surface 10, the vanishing effect can be enhanced. By setting the width of each of the first outer peripheral margin surface 10 and the second outer peripheral margin surface 20 to 20% or less, it is possible to suppress wear of the drill 100 due to excessive burnishing.

Furthermore, according to the drill 100 according to this embodiment, the second outer peripheral margin surface 20 is positioned between the front end of the first outer peripheral margin surface 10 and the rear end 2 of the drill 100 in the direction parallel to the axis X. may The recession amount of the second outer peripheral margin surface 20 with respect to the first outer peripheral margin surface 10 may be 2% or more and 10% or less of the diameter of the first outer peripheral margin surface 10 .

Furthermore, according to the drill 100 according to the present embodiment, the cutting edge 3 has the main cutting edge portion 32 that continues to the first flank portion 43 and the chamfered cutting edge portion 33 that continues to the first chamfered surface portion 41 . may As a result, burrs formed in the holes can be removed. Therefore, finishing reaming becomes unnecessary.

Furthermore, according to the drill 100 according to this embodiment, the flank 40 may be provided with the coolant supply hole 30 . As a result, even if the drill 100 becomes hot due to burnishing, the drill 100 can be cooled by supplying the coolant from the coolant supply hole 30 . As a result, the roughness of the hole surface can be further reduced.

(Sample preparation)
First, drills 100 of samples 1 and 2 were prepared. Drill 100 of Sample 1 is a comparative example. Drill 100 of Sample 2 is an example. The sample 2 drill 100 has an approach surface 8 . The inclination angle (first angle θ1) of the approach surface 8 with respect to the first outer peripheral margin surface 10 was set to 7°. The width of the approach surface 8 (fourth width W4) was set to 0.3 mm. Drill 100 of Sample 1 does not have approach surface 8 . The first diameter D1 of the drill 100 of sample 1 was 7.993 mm. The first diameter D1 of the drill 100 of sample 2 was set to 8.003 mm.

(Evaluation method)
Next, using the drills 100 of Samples 1 and 2, the enlargement margin of the hole diameter was evaluated. Drills 100 of Samples 1 and 2 were used to form holes in the work material. The work material was S50C. The depth of the hole was 24 mm. The number of holes was five. The hole diameter was measured at each hole entrance and hole depth. The minimum, maximum and average values of five hole diameters were obtained. Hole formation was performed using four different cutting conditions. The cutting speed Vc was 80 m/min or 120 m/min. The feed amount f was 0.15 mm/rotation or 0.25 mm/rotation.

(Evaluation results)
FIG. 10 shows the diameter of the hole formed using the drill 100 according to sample 1. As shown in FIG. FIG. 11 shows the diameter of the hole formed using the drill 100 according to sample 2. As shown in FIG. Table 1 shows the diameter of the holes formed using the drill 100 according to samples 1 and 2. 10 and 11, the position indicated by the dashed line corresponds to the first diameter D1 of the drill 100. As shown in FIG. As shown in FIGS. 10 and 11, when comparing under the same cutting conditions, the hole diameter expansion margin when a hole is formed using the drill 100 according to sample 2 is It was smaller than the expansion margin of the hole diameter when the hole was formed. From the above results, it was demonstrated that the drill 100 of the example can reduce the enlargement margin of the hole diameter compared to the drill 100 of the comparative example.

(Evaluation method)
Next, the drills 100 of Samples 1 and 2 were used to evaluate the thrust component force of the cutting resistance. The work material was S50C. The depth of the hole was 24 mm. Hole formation was performed using four different cutting conditions. The cutting speed Vc was 80 m/min or 120 m/min. The feed amount f was 0.15 mm/rotation or 0.25 mm/rotation. Using the drills 100 of samples 1 and 2, the thrust component force of the cutting resistance was measured while forming a hole in the work material.

(Evaluation results)

Table 2 shows the thrust components of the cutting resistance of the drills 100 according to samples 1 and 2. As shown in Table 2, when compared under the same cutting conditions, the thrust component force of the cutting resistance of the drill 100 according to sample 2 is approximately the same as the thrust component force of the cutting force of the drill 100 according to sample 1. was confirmed.

(Evaluation method)
Next, the drills 100 of samples 1 and 2 were used to evaluate the roughness of the hole surface. The work material was S50C. The depth of the hole was 24 mm. Hole formation was performed using four different cutting conditions. The cutting speed Vc was 80 m/min or 120 m/min. The feed amount f was 0.15 mm/rotation or 0.25 mm/rotation. Arithmetic mean roughness (Ra) was measured on the surfaces of the holes formed in the work material using the drills 100 of Samples 1 and 2.

(Evaluation results)

Table 3 shows the surface Ra of the holes formed using the drill 100 according to samples 1 and 2. As shown in Table 3, when compared under the same cutting conditions, the Ra of the surface of the hole formed using the drill 100 according to Sample 2 is higher than that of the surface of the hole formed using the drill 100 according to Sample 1. was smaller than Ra. From the above results, it was demonstrated that the drill 100 of the example can reduce the roughness of the hole surface compared to the drill 100 of the comparative example.

(Evaluation method)
Next, the drills 100 of samples 1 and 2 were used to evaluate the roughness of the hole surface. The work material was S50C. The depth of the hole was 24 mm. The cutting speed Vc was set to 80 m/min. The feed amount f was 0.25 mm/rotation. Arithmetic mean roughness (Ra) and maximum height roughness (Rz) were measured on the surface of the hole formed after the cutting length of 23.6 m.

(Evaluation results)

Table 4 shows Ra and Rz of the surface of a hole formed after a cutting length of 23.6 m. As shown in Table 4, the Ra and Rz of the surface of the hole formed using the drill 100 of Sample 2 were smaller than the Ra and Rz of the surface of the hole formed using the drill 100 of Sample 1. rice field. From the above results, it was demonstrated that the drill 100 of Example can reduce the roughness of the hole surface compared to the drill 100 of Comparative Example even after the cutting length of 23.6 m.

The embodiments and examples disclosed this time are illustrative in all respects and should not be considered restrictive. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope.

REFERENCE SIGNS LIST 1 front end 2 rear end 3 cutting edge 4 outer peripheral intermediate surface 5 twist groove surface 6 thinning surface 7 leading edge 8 approach surface 9 outer peripheral surface 10 first outer peripheral margin surface 11 first side surface 12 second side surface 17 shank 20 second outer peripheral margin surface 30 coolant supply hole 31 thinning cutting edge portion 32 main cutting edge portion 33 chamfer cutting edge portion 40 flank surface 41 first chamfer surface portion 42 second chamfer surface portion 43 first flank portion 44 second flank surface portion 51 first boundary portion 52 second boundary portion 53 third boundary portion 60 third outer peripheral margin surface 61 first intermediate region 62 second intermediate region, 63 third side surface, 64 fourth side surface, 100 drill, 130 rotational projection trajectory, 131 first projection trajectory, 132 second projection trajectory, 133 third projection trajectory, 134 projection trajectory, D1 first diameter, D2 second diameter, D3 third diameter, L1 retraction amount, L2 second length, L3 third length, W1 first width, W2 second width, W3 third width, W4 fourth width, X axis, θ1 First angle, θ2 Second angle, θ3 First central angle, θ4 Second central angle.

Claims (10)

A drill that rotates about an axis,
a cutting edge;
a twisted groove surface connected to the cutting edge;
a first outer peripheral margin surface located behind the outermost peripheral end of the cutting edge in the rotational direction and having a diameter larger than the diameter of the cutting edge;
an approach surface located between the first outer peripheral margin surface and the torsion groove surface, connected to the outermost peripheral edge, and formed along the leading edge of the torsion groove surface;
When viewed in the direction along the axis, the approach surface is inclined with respect to the first outer peripheral margin surface,
the length of the approach surface in the direction parallel to the axis is 0.5 times or more the diameter of the first outer peripheral margin surface ;
The value obtained by subtracting the diameter of the cutting edge from the diameter of the first outer peripheral margin surface is 0.01 mm or more and 0.08 mm or less,
The drill , wherein the approach surface has a width of 0.1 mm or more and 0.4 mm or less when viewed in a direction along the axis . 2. The drill according to claim 1, wherein an inclination angle of said approach surface with respect to said first peripheral margin surface when viewed along said axis is 3[deg.] or more and 15[deg.] or less. The core thickness of the drill is 28% or more and 40% or less of the diameter of the first outer peripheral margin surface,
3. The drill according to claim 1 or 2 , wherein in a cross section perpendicular to the axis, the central angle of the helical groove surface is 0.5 times or more and 1 time or less than the central angle of the portion other than the helical groove surface. . further comprising a second outer peripheral margin surface spaced apart from the first outer peripheral margin surface and positioned rearward in the rotational direction relative to the first outer peripheral margin surface;
When viewed in the direction along the axis, the width of each of the first outer margin surface and the second outer margin surface is 5% or more and 20% or less of the diameter of the first outer margin surface,
In a direction parallel to the axis, the front end of the second outer peripheral margin surface is positioned axially rearward of the front end of the first outer peripheral margin surface, and the second outer peripheral margin is positioned relative to the first outer peripheral margin surface. 3. The drill according to claim 1, wherein the recession amount of the surface is 2% or more and 10% or less of the diameter of the first peripheral margin surface. a flank surface connected to the cutting edge;
a peripheral intermediate surface between the first peripheral margin surface and the second peripheral margin surface;
The flank includes a first flank portion and a first chamfered surface portion that is located on the outer peripheral side of the first flank portion, is inclined with respect to the first flank portion, and continues to the first flank portion. have
The drill according to claim 4 , wherein said first chamfer surface portion is continuous with said outer peripheral intermediate surface. The flank includes a second flank portion located rearward in the rotational direction of the first flank portion and continuous with the first flank portion, and a second flank portion located rearward in the rotational direction of the second flank portion and the second flank portion. 6. A drill according to claim 5 , having a second chamfer surface portion which is contiguous with the two peripheral margin surfaces. Further comprising a flank that continues to the cutting edge,
The flank includes a first flank portion and a first chamfered surface portion that is located on the outer peripheral side of the first flank portion, is inclined with respect to the first flank portion, and continues to the first flank portion. have
The cutting edge has a main cutting edge portion continuous with the first flank portion and a chamfered cutting edge portion continuous with the first chamfered surface portion,
When the drill is rotated about the axis, the rotational trajectory of the axis and the rotational trajectory of the chamfer cutting edge form a rotation projection plane in which the cutting edge is projected onto a plane containing the axis. 3. The drill according to claim 1 or 2 , wherein the angle is between 15[deg.] and 45[deg.]. 8. The drill according to claim 7 , wherein the length of said chamfered cutting edge in the direction parallel to said axis is 3% or more and 10% or less of the diameter of said first peripheral margin surface. Further comprising a flank that continues to the cutting edge,
3. A drill according to claim 1 or 2 , wherein the flank is provided with a coolant supply hole. further comprising a second outer peripheral margin surface spaced apart from the first outer peripheral margin surface and positioned rearward in the rotational direction relative to the first outer peripheral margin surface;
When viewed in the direction along the axis, the inclination angle of the approach surface with respect to the first outer peripheral margin surface is 3° or more and 15° or less,
When viewed in the direction along the axis, the width of each of the first outer margin surface and the second outer margin surface is 5% or more and 20% or less of the diameter of the first outer margin surface,
In a direction parallel to the axis, the front end of the second outer peripheral margin surface is positioned axially rearward of the front end of the first outer peripheral margin surface, and the second outer peripheral margin is positioned relative to the first outer peripheral margin surface. 2. The drill according to claim 1, wherein the retreat amount of the surface is 2% or more and 10% or less of the diameter of the first peripheral margin surface.

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