Drill

Abstract

To suppress generation of a burr.SOLUTION: A drill includes a chisel edge 11, a first cutting edge 32, a second cutting edge 33, a first outer periphery cutting edge 42, and a second outer periphery cutting edge 43. The first cutting edge 32 extends from the chisel edge 11 to the radially outside of the drill. The second cutting edge 33 extends from the first cutting edge 32 to the radially outside of the drill. The first outer periphery cutting edge 42 extends from the second cutting edge 33 in an axial direction of the drill while being inclined so as to extend from the second cutting edge 33 to the radially outside of the drill. The second outer periphery cutting edge 43 extends from the first outer periphery cutting edge 42 in the axial direction of the drill. An inclination angle θ2 of the second cutting edge 33 with respect to a direction orthogonal to a central axis C1 of the drill is smaller than an inclination angle θ1 of the first cutting edge 32 with respect to the direction orthogonal to the central axis C1 of the drill.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a drill.

Background Art

[0002] As a drill used for drilling a hole in a workpiece to be processed, for example, it is disclosed in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When drilling a hole with a drill, burrs are generated on the workpiece to be processed. The drill is required to suppress the generation of burrs generated on the workpiece to be processed. [[ID=3G]]

Means for Solving the Problems

[0005] The drill for solving the above problems is a drill, including a first cutting edge extending from the tip of the drill toward the outside in the radial direction of the drill, a second cutting edge extending from the first cutting edge toward the outside in the radial direction, a first outer peripheral cutting edge extending from the second cutting edge in the axial direction of the drill while being inclined toward the outside in the radial direction, and a second outer peripheral cutting edge extending from the first outer peripheral cutting edge in the axial direction of the drill. The inclination angle of the second cutting edge with respect to a direction perpendicular to the central axis of the drill is smaller than the inclination angle of the first cutting edge with respect to a direction perpendicular to the central axis of the drill.

[0006] When drilling a hole in a workpiece, the second cutting edge can prevent the hole from being expanded. This can prevent burrs from occurring on the workpiece. Further, as the first outer peripheral cutting edge and the second outer peripheral cutting edge pass through the hole, they cut the peripheral surface of the hole. This can further prevent burrs from occurring on the workpiece.

[0007] Regarding the above drill, the second outer peripheral cutting edge may be curved so that the distance from the central axis increases to a position at a predetermined distance from the first outer peripheral cutting edge.

Advantages of the Invention

[0008] According to the present invention, the occurrence of burrs can be suppressed.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0010] [[ID=’36]]An embodiment of the drill will be described. As shown in FIGS. 1 and 2, the drill 10 includes a chisel edge 11 and two cutting edges 21. The chisel edge 11 is at the tip of the drill 10. The chisel edge 11 is provided at a location including the central axis C1 of the drill 10.

[0011] The two cutting edges 21 are provided at intervals in the circumferential direction of the drill 10. The shapes of the two cutting edges 21 are the same. The drill 10 may include three or more cutting edges 21. The cutting edge 21 includes a tip edge 31, an outer peripheral edge 41, and a margin 51. The tip edge 31 includes a first cutting edge 32 and a second cutting edge 33. The outer peripheral edge 41 includes a first outer peripheral cutting edge 42 and a second outer peripheral cutting edge 43. The margin 51 is provided at a position farther from the chisel edge 11 than the tip edge 31 and the outer peripheral edge 41. The cutting edges are arranged in the order of the first cutting edge 32, the second cutting edge 33, the first outer peripheral cutting edge 42, and the second outer peripheral cutting edge 43 from the chisel edge 11 toward the margin 51.

[0012] <First cutting edge and second cutting edge> As shown in FIG. 3, the first cutting edge 32 is connected to the chisel edge 11. The first cutting edge 32 extends outward in the radial direction of the drill 10 from the chisel edge 11. The first cutting edge 32 linearly inclines at an inclination angle θ1 with respect to the direction orthogonal to the central axis C1 of the drill 10. The first cutting edge 32 inclines from the chisel edge 11 toward the second cutting edge 33.

[0013] The second cutting edge 33 is connected to the first cutting edge 32. The second cutting edge 33 is located outside the first cutting edge 32 in the radial direction of the drill 10. The second cutting edge 33 extends outward in the radial direction of the drill 10 from the first cutting edge 32. The second cutting edge 33 is a portion where the inclination with respect to the direction orthogonal to the central axis C1 of the drill 10 is gentler than that of the first cutting edge 32. In the present embodiment, the second cutting edge 33 extends in the direction orthogonal to the central axis C1 of the drill 10. That is, the inclination angle θ2 of the second cutting edge 33 with respect to the direction orthogonal to the central axis C1 of the drill 10 is 0°. Therefore, the inclination angle θ2 of the second cutting edge 33 with respect to the direction orthogonal to the central axis C1 of the drill 10 is smaller than the inclination angle θ1 of the first cutting edge 32 with respect to the direction orthogonal to the central axis C1 of the drill 10.

[0014] <First outer peripheral cutting edge and second outer peripheral cutting edge> The first outer peripheral cutting edge 42 is connected to the second cutting edge 33. The first outer peripheral cutting edge 42 is located radially outside the drill 10 than the second cutting edge 33. The first outer peripheral cutting edge 42 extends in the axial direction of the drill 10 from the second cutting edge 33. In the present embodiment, the first outer peripheral cutting edge 42 is linearly inclined with respect to the direction orthogonal to the central axis C1 of the drill 10. The first outer peripheral cutting edge 42 is inclined so as to go radially outward of the drill 10 from the second cutting edge 33. The inclination angle θ3 of the first outer peripheral cutting edge 42 with respect to the direction orthogonal to the central axis C1 of the drill 10 is larger than the inclination angle θ2 of the second cutting edge 33 with respect to the direction orthogonal to the central axis C1 of the drill 10. In the present embodiment, the inclination angle θ3 > the inclination angle θ1 > the inclination angle θ2.

[0015] The second outer peripheral cutting edge 43 is connected to the first outer peripheral cutting edge 42. The second outer peripheral cutting edge 43 extends in the axial direction of the drill 10 with a predetermined curvature from the first outer peripheral cutting edge 42. As shown in FIG. 1, the second outer peripheral cutting edge 43 is curved so that the distance from the central axis C1 becomes longer up to the position P1 which is a predetermined distance away from the first outer peripheral cutting edge 42. The second outer peripheral cutting edge 43 is curved so that the distance from the central axis C1 becomes shorter as it goes from the position P1 toward the margin 51. The second outer peripheral cutting edge 43 extends to the margin 51.

[0016] [Operation of the present embodiment] As shown in FIG. 4, the drill 10 is used when drilling a hole in the workpiece W1. The workpiece W1 is, for example, a steel material.

[0017] When drilling a hole with the drill 10, the drill 10 penetrates the workpiece W1. At this time, the hole H1 is expanded by the drill 10. The hole H1 is more easily expanded as the tip angle of the drill 10 is larger. Also, when the hole H1 is expanded, as the drill 10 penetrates, the edge of the hole H1 expands in the radial direction of the hole H1.

[0018] When drilling with the drill 10 of this embodiment, the second cutting edge 33 contacts the portion E1 surrounding the edge of the hole H1. The inclination angle θ2 of the second cutting edge 33 with respect to the direction orthogonal to the central axis C1 of the drill 10 is smaller than the inclination angle θ1 of the first cutting edge 32 with respect to the direction orthogonal to the central axis C1 of the drill 10. That is, by providing the second cutting edge 33, the inclination is made gentler than that of the first cutting edge 32. Thereby, it is possible to suppress the hole H1 from being expanded compared to the case where the tip blade 31 is composed of only the first cutting edge 32.

[0019] After the first cutting edge 32 and the second cutting edge 33 pass through the workpiece W1, the peripheral surface of the hole H1 is cut by the first outer peripheral cutting edge 42 and the second outer peripheral cutting edge 43. The angles of the outer peripheral blade 41 are changed stepwise by the first outer peripheral cutting edge 42 and the second outer peripheral cutting edge 43. By changing the angle of the outer peripheral blade 41 stepwise, corners are prevented from being formed on the outer peripheral blade 41.

[0020] [Effects of this embodiment] (1) The drill 10 includes a first cutting edge 32, a second cutting edge 33, a first outer peripheral cutting edge 42, and a second outer peripheral cutting edge 43. The second cutting edge 33 suppresses the hole H1 from being expanded. Thereby, it is possible to suppress the generation of burrs on the workpiece W1. Further, when the first outer peripheral cutting edge 42 and the second outer peripheral cutting edge 43 pass through the hole H1, the peripheral surface of the hole H1 is cut. Thereby, it is possible to further suppress the generation of burrs on the workpiece W1.

[0021] (2) By suppressing the hole H1 from being expanded, the straight - advancing stability of the drill 10 during drilling is high. Thereby, it is possible to further suppress the generation of burrs on the workpiece W1.

[0022] (3) The second outer peripheral cutting edge 43 curves so that the distance from the central axis C1 becomes longer up to the position P1 which is a predetermined distance away from the first outer peripheral cutting edge 42. Thereby, the peripheral surface of the hole H1 is easily cut. Thereby, it is possible to further suppress the generation of burrs on the workpiece W1.

[0023] (4) The outer peripheral edge 41 includes a first outer peripheral cutting edge 42 and a second outer peripheral cutting edge 43. As a result, the angle of the outer peripheral edge 41 changes stepwise. This prevents a corner from occurring at the boundary between the tip edge 31 and the outer peripheral edge 41. Thereby, stress concentration at the corner is suppressed, and the durability of the drill 10 can be improved.

[0024] [Modified Example] The embodiment can be implemented with the following modifications. The embodiment and the following modified examples can be implemented in combination with each other within a technically non - conflicting range.

[0025] ○ The second cutting edge 33 may be inclined with respect to the direction orthogonal to the central axis C1 of the drill 10. That is, the inclination angle θ2 may be greater than 0°. ○ The second outer peripheral cutting edge 43 may extend linearly in the axial direction of the drill 10.

Explanation of Reference Numerals

[0026] 10…drill, 11…chisel edge at the tip of the drill, 32…first cutting edge, 33…second cutting edge, 42…first outer peripheral cutting edge, 43…second outer peripheral cutting edge.

Claims

1. A drill, comprising: a first cutting edge extending from the tip of the drill toward the outside in the radial direction of the drill; a second cutting edge extending from the first cutting edge toward the outside in the radial direction; a first outer peripheral cutting edge extending from the second cutting edge in the axial direction of the drill while inclining toward the outside in the radial direction from the second cutting edge; a second outer peripheral cutting edge extending from the first outer peripheral cutting edge in the axial direction of the drill; wherein an inclination angle of the second cutting edge with respect to a direction orthogonal to the central axis of the drill is smaller than an inclination angle of the first cutting edge with respect to a direction orthogonal to the central axis of the drill.

2. The drill according to claim 1, wherein the second outer peripheral cutting edge curves such that a distance from the central axis increases to a position at a predetermined distance from the first outer peripheral cutting edge.

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