Cemented carbide drill

Abstract

To provide a cemented carbide drill capable of improving a flow of chips generated by cutting a workpiece by suppressing wear of a flank face of a cutting edge so as to enhance cutting edge performance with respect to the workpiece, as well as, by suppressing inflow of the workpiece to the flank face side.SOLUTION: In a cemented carbide drill 10 having two or more cutting edges 1: the cutting edges 1 include at least a linear cutting edge 1; the linear cutting edge 1 is provided with a chamfer surface 5 having been subjected to chamfer honing; and an angle of the chamfer surface 5 is gradually reduced as proceeding toward an outer peripheral corner 4 from a center axis of the cemented carbide drill 10. Therein the angle of the chamfered surface 5 may be - 3° to 28° inclusive.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a cemented carbide drill having a chamfered cutting edge. [Background technology]

[0002] Conventionally, the cutting edge of a cemented carbide drill is chamfered (or chamfer honed) to prevent chipping of the cutting edge, as in the drills disclosed in Patent Documents 1 to 4. The angle of the machined cutting edge is in the range of 10° to 30° in cross-sectional view, and is formed at a constant angle from the central axis to the outer peripheral corner. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 2508539 [Patent Document 2] Japanese Utility Model Application Publication No. 60-175513 [Patent Document 3] Patent Publication No. 2022-23828 [Patent Document 4] Patent Publication No. 2022-129078 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the drills disclosed in Patent Documents 1 to 4, due to the negative chamfer angle, part of the work material flows into the flank face at the outer corner where the cutting amount is large during cutting, and is pressed down, causing the work material and the drill to rub strongly against each other, which tends to cause the flank face to wear more rapidly.

[0005] In addition, since the cutting speed is faster on the outer corner side than on the central axis side, the performance (sharpness) of the cutting edge on the outer corner side is important. With the conventional chamfer shape, the shear angle becomes small, which has a significant effect on the breakability of the chips.

[0006] Therefore, an objective of the present invention is to provide a cemented carbide drill that can improve cutting edge performance against the workpiece by suppressing wear on the flank of the cutting edge, while at the same time suppressing the flow of workpiece material onto the flank side and improving the flow of chips generated during cutting processing. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems, the cemented carbide drill of the present invention has two or more cutting edges, and the cutting edges have at least straight cutting edges, and the straight cutting edges are provided with chamfered surfaces that have been subjected to chamfer honing, and the angle of the chamfered surfaces decreases from the central axis of the cemented carbide drill toward the outer circumferential corner. The angle of the chamfered surfaces may be between -3° and 28°. Effect of the Invention

[0008] The cemented carbide drill of the present invention reduces the angle of the chamfered surface of the cutting edge from the central axis to the outer corner, thereby suppressing wear on the flank of the cutting edge and improving the cutting performance for the work material. At the same time, it has the effect of suppressing the flow of the work material onto the flank side and improving the flow of chips generated by cutting. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a partial plan view of a cemented carbide drill 10 according to the present invention. [Diagram 2] 2 is a view taken along the arrow A of the cemented carbide drill 10 shown in FIG. [Diagram 3] 2 is a cross-sectional view taken along line XX of the cemented carbide drill 10 shown in FIG. [Figure 4] 2 is a cross-sectional view of the cemented carbide drill 10 shown in FIG. 1 along line YY. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] An embodiment of the cemented carbide drill 10 of the present invention will be described with reference to the drawings. Fig. 1 shows a partial plan view of the cemented carbide drill 10 of the present invention, Fig. 2 shows a view of the cemented carbide drill 10 shown in Fig. 1 from the arrow A, Fig. 3 shows a cross section of the cemented carbide drill 10 shown in Fig. 1 along line XX, and Fig. 4 shows a cross section of the cemented carbide drill 10 shown in Fig. 1 along line YY.

[0011] As shown in Figures 1 and 2, a cemented carbide drill 10 according to one embodiment of the present invention has two or more cutting edges 1, a flank face 2 and a rake face 3 adjacent thereto, and as shown in Figure 1, the cutting edges 1 have at least a straight cutting edge portion. The cemented carbide drill 10 also has a thinning surface 6 on the central axis side (not shown) as shown in Figure 2. The cutting edges of the drill according to the present invention need only have at least a straight cutting edge. For example, the cutting edges may be straight from one end to the other end, or may be a combination of straight and curved cutting edges.

[0012] The cutting edge 1 is provided with a chamfered surface 5 that has been subjected to honing as shown in Figures 1 and 2, and the angles θ1, θ2 of the chamfered surface 5 become smaller from the central axis (not shown) of the cemented carbide drill 10 toward the outer circumferential corner 4 as shown in Figures 3 and 4. The angles θ1, θ2 of the chamfered surface 5 are preferably set to be between -3° and 28°.

[0013] In particular, by setting the angle θ2 of the chamfer surface 5 in the range of +3° to -3° near the outer corner 4 where the cutting amount is large, the chips generated by the cutting process can flow more easily to the rake face 3 side, reducing the cutting resistance, and improving the sharpness of the cutting edge, which has the effect of improving the breakability of the chips. As a result, it also leads to an improvement in the life of the drill.

[0014] In the present invention, the "angle of the chamfered surface" refers to the angle formed by two imaginary straight lines L0, L1, i.e., an imaginary straight line L0 perpendicular to the cutting edge of the cemented carbide drill and an imaginary straight line L1 parallel to the chamfered surface. In addition, regarding the distinction between "+ (positive)" and "- (negative)" of the chamfered surface angles θ1, θ2, in the form shown in Fig. 3, when the imaginary straight line L1 parallel to the chamfered surface is positioned counterclockwise from the imaginary straight line L0 perpendicular to the cutting edge, it is distinguished as a + (positive) angle, and when the imaginary straight line L1 parallel to the chamfered surface is positioned clockwise, it is distinguished as a - (negative) angle. [Explanation of symbols]

[0015] 1 Cutting edge 2 Flank 3. Scooping surface 4 Outer corners 5 Chamfered surface 6 Thinning surface 10 Carbide drill L0, L1 Virtual straight line related to the cutting edge θ1,θ2 Chamfer angle

Claims

1. A cemented carbide drill having two or more cutting edges, characterized in that the cutting edges have at least straight cutting edges, the straight cutting edges have chamfered surfaces that have been subjected to chamfer honing, and the angle of the chamfered surfaces becomes smaller from the central axis of the cemented carbide drill toward the outer corner.

2. 2. The cemented carbide drill according to claim 1, wherein the angle of the chamfered surface is between -3° and 28°.

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