Drill

Abstract

To provide a drill that can suppress burr from occurring around a machined hole.SOLUTION: A drill 10 comprises two or more cutting blades 2, 3 and 4 arranged outward from a center shaft O. The cutting blades 2, 3 and 4 are formed of first cutting blades 2A and 2B having straight portions extending from chisel edges 1A and 1B to the outside of the drill 10, second cutting blades 3A and 3B extending from end parts of the first cutting blades 2A and 2B to the outside of the drill 10 and to a rear side of the drill, in a circumferential direction, and third cutting blades 4A and 4B in a straight shape extended from end parts of the second cutting blades 3A and 3B to the rear side of the drill 10 and connected to a leading edge 5.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drill that can suppress burrs that occur on the surface of a workpiece after drilling. [Background technology]

[0002] In drilling using a drill, burrs are generated around the hole after drilling, so a deburring process is added after the drilling to remove the burrs. For this reason, Patent Documents 1 to 3 disclose drills that can reduce the burrs generated after drilling.

[0003] However, these drills have a problem in that burrs remain after drilling depending on the type of work material. Therefore, Patent Document 4 discloses a plurality of drills with different shapes classified according to the work material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Utility Model Registration No. 3199122 [Patent Document 2] Patent Publication No. 2021-65967 [Patent Document 3] JP 2005-279848 A [Patent Document 4] JP 2021-151681 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the drill disclosed in Patent Document 4 has an inflection point at the connection between the cutting edge at the tip of the drill and the margin at the rear of the drill, which means that burrs or burrs can form on the surface of the workpiece depending on the hole-cutting conditions, such as high speed rotation and high feed rate.

[0006] Therefore, an object of the present invention is to provide a drill that suppresses the generation of burrs around a drilled hole, regardless of hole drilling conditions such as high speed rotation and high feed. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, a step portion as in conventional drills is eliminated by providing a portion that smoothly connects the cutting edge provided on the tip side of the drill with the margin provided on the rear end side (shank side). That is, the drill of the present invention has at least two or more cutting edges extending outward from the central axis, and these cutting edges are formed of a first cutting edge having a straight portion extending from the chisel edge to the outside of the drill, a second cutting edge that is a curved cutting edge extending from the end of the first cutting edge to the outside, circumferential direction and rearward of the drill, and a straight third cutting edge that extends from the end of the second cutting edge to the rear side of the drill and connects to the leading edge.

[0008] Alternatively, in a drill having two or more cutting edges extending outward from a central axis, these cutting edges are formed of a first cutting edge having a straight portion extending from the chisel edge to the outside of the drill, a second cutting edge extending from an end of the first cutting edge to the outside, circumferential direction and rearward of the drill, and a curved third cutting edge extending from an end of the second cutting edge to the rearward side of the drill and connecting to the leading edge. The second cutting edge may be a curved cutting edge, and the radius of curvature of the third cutting edge may be larger than the radius of curvature of the second cutting edge.

[0009] Also, the third cutting edge may be connected to the leading edge of the drill, and the flank adjacent to the third cutting edge may be formed continuously with the margin of the drill, and the angle (θ1, θ2) between the ridgeline that is the boundary between the flank adjacent to the third cutting edge and the margin and the leading edge may be set to a range of 4° to 25°. The clearance angles of the second and third cutting edges of the drill may be set to a range of 5° to 11°. Effect of the Invention

[0010] The drill of the present invention has the effect of suppressing the generation of burrs around a drilled hole, regardless of the type of work material or the hole drilling conditions such as high speed rotation and high feed. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a front view of a drill 10 of the present invention. [Diagram 2] FIG. 2 is a right side view of the drill 10 shown in FIG. [Diagram 3] 2 is a view of the drill 10 shown in FIG. 1 taken along an arrow A. [Figure 4] 1 is a schematic longitudinal projection view of a drill 10 according to the present invention. [Diagram 5] 1 is a schematic enlarged view of the vicinity of a second cutting edge 3 and a third cutting edge 4 of a drill 10 of the present invention (first embodiment). [Figure 6] 2 is a schematic enlarged view of the vicinity of a second cutting edge 3 and a third cutting edge 4 of a drill 10 of the present invention (second embodiment). FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] An embodiment of the drill of the present invention will be described with reference to the drawings. An embodiment of the drill of the present invention will be described with reference to the drawings. FIG. 1 shows a front view of a drill 10 according to an embodiment of the present invention, FIG. 2 shows a right side view, and FIG. 3 shows a view of the drill 10 shown in FIG. 1 as viewed from the arrow A. The drill 10 of the present invention has first to third cutting edges 2, 3, 4 extending radially (outwardly) from a chisel edge 1 (1A, 1B) located at the tip portion of the drill 10 as shown in FIG. 1 and FIG. 2, and each of the flanks 6 (6A, 6B), 11 (11A, 11B), 51 (51A, 51B) formed adjacent to the first to third cutting edges 2, 3, 4.

[0013] In particular, the flank (first flank) 51 (51A, 51B) adjacent to the first cutting edge 2 (2A, 2B) and the flank (second flank) 11 (11A, 11B) adjacent to the second cutting edge 3 (3A, 3B) are formed as flanks separate and independent of each other as shown in Figures 1 to 3. In addition, the flank (first flank) 51 (51A, 51B) adjacent to the first cutting edge 2 (2A, 2B) is further provided with a separate flank (third flank) 6 (6A, 6B) on the rear side in the rotation direction of the drill.

[0014] The first cutting edge 2 (2A, 2B) having a straight portion extending outward of the drill 10 is generally called the "main cutting edge," and the first cutting edge 2 (2A, 2B) shown in Figures 1 to 3 is in the form of a cutting edge extending outward in a straight line, but the first cutting edge 2 (2A, 2B) is not limited to this form. For example, when the workpiece is a light metal such as an aluminum alloy or a difficult-to-cut material such as stainless steel, the first cutting edge 2 (2A, 2B) may be in a form that partially includes a straight portion or in a form that combines a straight portion and a curved portion.

[0015] As shown in FIG. 2 and FIG. 3, the first cutting edge 2 (2A, 2B) has a rake face 7 (7A, 7B) and a groove (twisted groove) 8 (8A, 8B) formed continuously thereto. Since the first cutting edge 2 (2A, 2B) has a straight portion, it plays a role of breaking up and discharging chips generated during hole drilling by the drill of the present invention to the outside without continuously generating them. In addition, by setting the point angle α of the first cutting edge 2 (2A, 2B) shown in FIG. 2 in the range of 90° to 140°, it is possible to improve the centripetal property (prevention of drill runout) and biting property (initial workability for flat work material) of the drill 10 at the start of hole drilling. Furthermore, by setting the point angle α in the range of 170° to 200°, the drill is not affected by the inclined surface at the start of hole drilling, and the drill can be drilled without bending.

[0016] Here, the "point angle" is defined as "the angle when the cutting edges are projected parallel to a plane parallel to the axis of the drill" as specified in the Japanese Industrial Standards (JIS) B0171. In other words, the point angle α formed by the first cutting edges 2A, 2B is the angle when the two first cutting edges 2A, 2B are projected parallel to a plane parallel to the axis (center axis O) of the drill 10 as shown in Figure 2.

[0017] Next, a schematic projection view of the drill 10 of this embodiment in the longitudinal direction (axial direction) is shown in FIG. 4, and a schematic enlarged view of the vicinity of the second cutting edge 3 and the third cutting edge 4 of the drill 10 of the first and second embodiments is shown in FIG. 5 and FIG. 6, respectively. In the drill 10 of this embodiment, as shown in FIG. 2 and FIG. 3, the second cutting edge 3 (3A, 3B) extends from the end of the first cutting edge 2 (2A, 2B) to the outside of the drill 10, in the circumferential direction, and toward the rear side of the drill 10, and the third cutting edge 4 (4A, 4B) extends from the end of the second cutting edge 3 (3A, 3B) to the rear side of the drill 10 and is connected to the leading edge 5. The formation of the second cutting edge 3 (3A, 3B) and the third cutting edge 4 (4A, 4B) suppresses the generation of burrs around the through hole when machining a through hole (through hole).

[0018] The second cutting edge 3 (3A, 3B) can be curved as shown in Fig. 1 to Fig. 4, so that, for example, two or more cutting edges having different radii of curvature can be combined. In this case, the radius of curvature of the cutting edge connected to the end of the first cutting edge 2 (2A, 2B) can be smaller than the radius of curvature of the cutting edge connected to the end of the third cutting edge 4 (4A, 4B). In other words, when the second cutting edge 3 (3A, 3B) is a curved cutting edge, the radius of curvature can be gradually increased from the tip side to the rear end side of the drill 10.

[0019] The third cutting edge 4 is either curved or straight, and is connected to the leading edge 5 via an outer circumferential corner toward the rear side of the drill 10 as shown in Fig. 5. That is, the connection portion between the third cutting edge 4 and the leading edge 5 corresponds to the outer circumferential corner of the drill 10 of this embodiment, and is the outermost position of the drill 10. In addition, when the second cutting edge 3 and the third cutting edge 4 are both formed in a curved shape as shown in Fig. 4, the radius of curvature r4 of the third cutting edge 4 may be made larger than the radius of curvature r3 of the second cutting edge 3.

[0020] 5, the flank 11 adjacent to the third cutting edge 4 is formed continuously with the margin 12 of the drill 10 of this embodiment, and the connection from the flank 11 of the third cutting edge 4 to the margin 12 gradually changes in an inclined manner from the front end side to the rear end side of the drill 10. The linear ridge 20 (first embodiment) which is the boundary between the flank 11 adjacent to the third cutting edge 4 and the margin 12 can have an angle θ (θ1) with the leading edge 5 in the range of 4° to 25°.

[0021] Furthermore, as a different embodiment regarding the boundary between the flank 11 and the margin 12, a ridge line 21 (second embodiment) which is the boundary between the flank 11 and the margin 12 may be configured with a straight portion and a curved portion as shown in Fig. 6. In this case as well, it is preferable that the angle θ (θ2) between the ridge line 21 and the leading edge 5 is in the range of 4° to 25°.

[0022] In addition, the angle θ (θ1, θ2) can be optimized according to various parameters such as the diameter (drill diameter) φD0 of the drill 10, the angle (rake angle) of the cutting face 7 (7A, 7B), the angle (twist angle) of the groove (twist groove) 8 (8A, 8B), the axial length L1 of the second cutting edge 3 (3A, 3B) and the third cutting edge 4 (4A, 4B), and the magnitudes of the radii of curvature r3, r4.

[0023] In the drill 10 of the present invention, the axial length L1 of the second cutting edges 3 (3A, 3B) and the third cutting edges 4 (4A, 4B) is preferably in the range of 0.10 to 0.40×D0 when the diameter D0 of the drill 10 is used as the reference as shown in Fig. 4. In the drill 10 of the present invention, the radial distance (shortest distance) E1 from the end of the first cutting edge 2 (2A, 2B) to the outermost periphery of the drill 10 (a virtual straight line that is parallel to the central axis O of the drill 10 and passes through the outer periphery corner) is preferably in the range of 0.01 to 0.20×D0 when the diameter D0 of the drill 10 is used as the reference as shown in Fig. 4. [Explanation of symbols]

[0024] 1 Chisel Edge 2 First cutting edge 3 Second cutting edge 4 3rd cutting edge 5 Leading Edge 6 Flank (third flank) 7. Scooping surface 8 Groove (Twisted Groove) 10 Drill 11 Flank (second flank) 12 Margin 20,21 The ridge that is the boundary between the flank and the margin 51 Flank (first flank) D0 Drill diameter (drill diameter) O center axis r3 Radius of curvature of second cutting edge r4 Radius of curvature of third cutting edge α Tip angle θ(θ1,θ2) Angle between the ridge and the leading edge

Claims

1. A drill having at least two or more cutting edges extending outward from a central axis, the cutting edges being formed from a first cutting edge having a straight portion extending from a chisel edge outward from the drill, a second cutting edge extending outward, circumferentially and rearward from an end of the first cutting edge, and a straight third cutting edge extending from the end of the second cutting edge to the rear side of the drill and connected to a leading edge.

2. A drill having at least two or more cutting edges extending outward from a central axis, the cutting edges being formed from a first cutting edge having a straight portion extending from a chisel edge outward from the drill, a second cutting edge extending outward, circumferentially and rearward from an end of the first cutting edge, and a curved third cutting edge extending from the end of the second cutting edge to the rear side of the drill and connected to a leading edge.

3. The drill of claim 1 , wherein the second cutting edge is a curved cutting edge.

4. The drill of claim 2 , wherein the second cutting edge is a curved cutting edge, and the radius of curvature of the third cutting edge is greater than the radius of curvature of the second cutting edge.

5. The drill according to any one of claims 1 to 4, characterized in that the third cutting edge is connected to the leading edge via an outer corner, and a flank adjacent to the third cutting edge is formed continuously with a margin of the drill, and a ridge line that is a boundary between the flank adjacent to the third cutting edge and the margin forms an angle with the leading edge in the range of 4° to 25°.

6. The drill according to claim 5 , wherein the clearance angles of the second cutting edge and the third cutting edge are in the range of 5° to 11°.

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