drill

Abstract

To provide a drill capable of suppressing occurrence of a burr on a periphery of a processing hole.SOLUTION: There is provided a drill 10 comprising: two or more first cutting edges 3A, 3B extending from a chisel edge 1 being a center of the drill 10, to a radial direction of the drill 10; second curved cutting edges 4A, 4B which extend further to a radial direction and to a circumferential direction from the ends of the first cutting edges 3A, 3B; connection parts 5A, 5B comprising cutting edges extending spirally to an axial direction from ends of the second cutting edges 4A, 4B; and guide parts 6A, 6B which are continuous to the connection parts 5A, 5B and where a relief angle of the cutting blade is 1° or smaller. In addition, relief angles θ1 and θ2 of the cutting edges on the connection parts 5A, 5B are set to 12° or smaller, so that the relief angles decrease gradually as going to the shank side.SELECTED DRAWING: Figure 1

Description

Technical Field

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[0001] The present invention relates to a drill that can suppress burrs (swarf) generated on the surface of a workpiece after drilling.

Background Art

[0002] In drilling using a drill, burrs (swarf) occur around the hole after processing, so a deburring process is added after drilling to remove the burrs. Therefore, drills that can reduce burrs generated after drilling are disclosed in Patent Documents 1 to 3.

[0003] However, these drills have a problem that burrs still remain after drilling depending on the type of workpiece. Therefore, Patent Document 4 discloses a plurality of types of drills classified for each workpiece and having different forms.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the drill disclosed in Patent Document 4, a bending point occurs at the connection portion between the cutting edge at the tip of the drill and the margin on the rear side of the drill. Therefore, depending on drilling conditions such as high-speed rotation and high feed, burrs and swarf may occur on the surface of the workpiece.

[0006] <00000Therefore, the object of the present invention is to provide a drill that suppresses the generation of burrs around the machined hole, regardless of hole machining conditions such as high rotation speed or high feed rate. [Means for solving the problem]

[0007] To solve the aforementioned problems, the step portion found in conventional drills is eliminated by providing a section 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). In other words, the drill of the present invention has at least a first cutting edge extending radially from the chisel edge, a curved second cutting edge extending radially and circumferentially from the end of the first cutting edge, a connecting section having a cutting edge that extends helically in the axial direction from the outer peripheral corner which is the end of the second cutting edge, and a guide section formed continuously with the connecting section and having a cutting edge with a relief angle of 1° or less, wherein the relief angle of the cutting edge of the connecting section is 12° or less, and the relief angle gradually decreases as it approaches the shank side.

[0008] Furthermore, the drill may be provided with a back taper (a taper that causes the outer diameter of the drill to decrease from the tip to the rear end of the drill), and the relief angle of the cutting edge of the guide section may be set to be less than or equal to the relief angle of the cutting edge of the connecting section. In addition, by applying a thinning surface to the drill, the central cutting edge adjacent to the thinning surface may be formed to be continuous with the first cutting edge, or the relief angle of the second cutting edge may be made larger than the relief angle of the first cutting edge.

[0009] Furthermore, the axial length of the connection point when projected along the longitudinal direction of the drill may be set to at least 30% of the drill's diameter. [Effects of the Invention]

[0010] The drill of the present invention has the effect of suppressing the generation of burrs around the machined hole, regardless of the type of workpiece or the hole machining conditions such as high rotation speed or high feed rate. [Brief explanation of the drawing]

[0011] [Figure 1] Front view of the drill 10 according to an embodiment of the present invention. [Figure 2] Left side view of the drill 10 according to an embodiment of the present invention. [Figure 3] Schematic projection view of the drill 10 of the present invention in the axial direction. [Figure 4] Cross-sectional view taken along the line X-X of the drill 10 shown in FIG. 1. <00000...66> [Figure 5] Cross-sectional view taken along the line Y-Y of the drill 10 shown in FIG. 1.

Mode for Carrying Out the Invention

[0012] An embodiment of the drill of the present invention will be described with reference to the drawings. The front view of the drill 10 (drill diameter: φD0), which is an embodiment of the present invention, is shown in FIG. 1, the right side view is shown in FIG. 2, and the schematic projection view of the drill 10 in the axial direction is shown in FIG. 3. As shown in FIGS. 1 and 2, the drill 10 of the present invention extends from the chisel edge 1 including the central axis O located at the tip of the drill 10 in the radial direction (outward) of the drill 10 straight line Two 1 cutting edges 2 (2A, 2B) Having are provided.

[0013] These 2 pieces of the first cutting edge 2 ( 2 A, <000008...3>B) extend in the radial direction (outward) and circumferential direction (rotation direction side) from each end of the 3 ( 3 A, 3 B) have two curved second cutting edges 3 ( 3 A, 3 B) which, as shown in FIG. 3, have an arc shape with a predetermined radius of curvature R3.

[0014] Also, as shown in FIGS. 1 and 3, the two second cutting edges 3 ( 3 A, 3 B) are provided with a connecting portion having cutting edges that extend helically in the axial direction from each end of the 4 ( 4A, 4 B) is formed, and a guide portion with a cutting edge is located on the shank side of the drill 10. 5 ( 5 A, 5 It is continuously connected to B). The second cutting edge. 3 ( 3 A, 3 B) and the connecting part 4 ( 4 A, 4 B) is connected via an outer corner of the drill 10 (not shown). In other words, the second cutting edge 3 ( 3 A, 3 B) and the connecting part 4 ( 4 A, 4 The contact point (connection point) at B) becomes the maximum diameter of the drill 10.

[0015] Also, the second cutting edge 3 ( 3 A, 3 B) Axial length d3, connection part 4 ( 4 A, 4 The axial length d4 of B) has a predetermined length in the axial direction of the drill 10, as shown in Figure 3, and the second cutting edge 3 ( 3 A, 3 The axial length d3 of B) is the connection part 4 ( 4 A, 4 It is longer than the axial length d4 of B). 3 ( 3 A, 3 B) Axial length d3, connection part 4 ( 4 A, 4 The axial length d4 of B) is preferably at least 30% of the diameter D0 of the drill 10. Furthermore, the connection part 4 ( 4 A, 4 B) has a back taper with a slope of angle θ10 toward the shank side of the drill 10 (not shown), as shown in Figure 3 (the straight line L10 shown in Figure 3 is an imaginary line parallel to the central axis O of the drill 10).

[0016] The connection part of the drill 10 of the present invention shown in Figure 1 4 ( 4 A, 4 Figure 4 shows the cross-sectional view along line XX in B), and Figure 5 shows the cross-sectional view along line YY, respectively. The connecting parts constituting the drill 10 of the present invention shown in Figures 4 and 5. 4 ( 4 A, 4 The relief angles θ1 and θ2 of the cutting edge in B) gradually decrease towards the shank side of the drill 10 (not shown), and the second cutting edge 3 ( 3 A, 3 The closer it is to B), the larger it becomes (θ1 > θ2). For example, the connection part of the drill 10 shown in Figure 4. 4 ( 4 A, 4 When the relief angle θ1 of the cutting edge in B) is 10°, the connection part of the drill 10 shown in Figure 5 4 ( 4 A, 4 In B), the relief angle θ2 of the cutting edge is less than 10°.

[0017] The first cutting edge that forms the cutting edge of the drill 10 shown in Figure 1, etc. 2 ( 2 A, 2 B) is a straight line, but it can also be a curved shape or a composite shape combining straight and curved lines. [Explanation of Symbols]

[0018] 1 (1A, 1B) Chisel Edge 2 ( 2 A, 2 B) First cutting edge 3 ( 3 A, 3 B) Second cutting edge 4 ( 4 A, 4 B) Connection part 5 (5A, 5B) Guide Department 10 Drills d3 Axial length of the second cutting edge of the drill d4 Axial length of the drill at the connection point D0 Drill Diameter L10 Imaginary line parallel to the central axis of the drill O Drill's central axis R3 Radius of curvature of the second cutting edge θ1, θ2 Relief angle of the cutting edge at the connection point θ10 Back taper gradient (angle)

Claims

[Claim 1] A drill having at least a first cutting edge extending radially from a chisel edge, a curved second cutting edge extending radially and circumferentially from the end of the first cutting edge, a connecting portion having a cutting edge extending helically axially from the outer peripheral corner which is the end of the second cutting edge, and a guide portion formed continuously with the connecting portion and having a cutting edge with a relief angle of 1° or less. The contact point between the second cutting edge and the connecting portion constitutes the maximum diameter of the drill. The cutting edge of the aforementioned connection part has a relief formed therein. The relief of the cutting edge at the aforementioned connection point has a relief angle of 12° or less, and gradually decreases towards the shank side. A drill characterized by the following features.

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