Drill

Abstract

To provide a drill having good sharpness and excellent durability.SOLUTION: A drill has: a chip discharge groove 6 which is formed on the outer periphery of a drill body 2 rotated around an axis; a first thinning surface 10 which is formed obliquely upward on a tip side across the chip discharge groove from the outer periphery of the drill body; a first flank 11 which forms a first cutting edge 14 as a main cutting edge on a boundary ridge line with the first thinning surface, is brought into contact with the first thinning surface and is formed on a side opposite to a drill rotation direction; a second thinning surface 12 which is on the tip side of the first thinning surface, is brought into contact with the first thinning surface and is formed on a side opposite to the drill rotation direction; and a second cutting edge 15 which is formed on a boundary ridge line between the second thinning surface and the first flank.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] This invention relates generally to drills, and more particularly to drills for medical use. [Background technology]

[0002] Drills used for drilling are used in many industrial fields. The drill is often used to drill holes in bone. The bone is covered with hard cortical bone on the surface and soft cancellous bone on the inside. Cortical bone is very hard, with a Shore hardness of 90 or more. It has a hardness of 820 Hv and a Rockwell hardness of 64.7 HRC.

[0003] The drill shown in FIG. 10 is a surgical drill, which has improved cutting power and is By improving the cutting ability of the cutting edge that is generated around the circumference, it is less likely to wear out and has a high cutting force. The object of the present invention is to provide an excellent medical drill.

[0004] FIG. 10 is a diagram corresponding to FIG. 2 of Patent Document 1, and FIG. 10(a) is a plan view seen from the tip side. FIG. 10(b) is a side view of the tip portion. The thinning cutting edge 101 is formed by the thinning and the rake face 106 formed by the thinning. The main cutting edge 102 is formed at the boundary of the thinning cutting edge 101. The thinning cutting edge 101 is formed on the outer periphery of the main cutting edge. The thinning surface 108 is formed by the chamfer surface 105 and the thinning cutting edge 101. A chisel 104 is formed between the two thinning cutting edges 101. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-108223 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the medical drill described in Patent Document 1, a thinning cutting edge 101 is formed. The surface 108 is axially symmetrical at only two places, and the recesses of the thinning are enlarged to improve sharpness. This will result in a smaller core thickness and a lower rigidity of the drill, making it impossible to avoid damage to the drill. Generally, drills are used repeatedly, so they need to be durable. The drill described in Reference 1 has a problem with durability.

[0007] The present invention has been made in view of the above points, and its object is to provide a cutting tool having excellent sharpness and excellent durability. The object of the present invention is to provide a drill having high durability. [Means for solving the problem]

[0008] The present invention (1) is a drill body that rotates around an axis and has a chip discharge groove formed on the outer periphery of the drill body. and a groove extending from the outer periphery of the drill body diagonally upward toward the tip side across the chip discharge groove. A first cutting edge that becomes a main cutting edge is formed on a boundary ridge between the first thinning surface and the first thinning surface. a second thinning surface formed on the opposite side to the drill rotation direction in contact with the first thinning surface; a flank surface and a tip side of the first thinning surface, the flank surface being in contact with the first thinning surface and having a groove; A second thinning surface formed on the opposite side to the rill rotation direction, and a thinning surface between the second thinning surface and the and a second cutting edge formed at the boundary ridge between the first cutting edge and the flank.

[0009] In the present invention (1), since the first thinning surface and the second thinning surface are provided in the axial direction, The core thickness can be increased, resulting in improved sharpness and durability of the drill. do.

[0010] The present invention (2) is characterized in that the second rake angle of the second cutting edge by the second thinning surface is a regular angle. The drill of the present invention (1) is characterized in that:

[0011] In the present invention (2), the second rake angle of the second cutting edge by the second thinning surface is a regular angle. Since the drill is placed at an angle on the object to be drilled, the drill This can reduce the deviation of the tip, especially when drilling hard materials such as cortical bone. is preferred.

[0012] The present invention (3) is the drill of the present invention (2), wherein the second rake angle is 20° to 60°. If the rake angle is too small, the strength of the cutting edge will be reduced. If the angle is too large, the tip of the drill will slip. After examining various angles, the lowest limit was found to be 20°. Preferably, the angle is 30°, more preferably, and even more preferably, 35°. The upper limit is preferably 60°. Preferably, the angle is 50°, more preferably, and 45° is even more preferably.

[0013] The present invention (4) is the invention (1) to ( 3) The drill has virtually no chisel edge, making it sharp and penetrating the cortical bone. Rotating the drill tip against the cortical bone improves initial bite. It becomes less slippery Effect of the Invention

[0014] According to the present invention, it is possible to provide a drill having excellent sharpness and excellent durability. [Brief description of the drawings]

[0015] [Figure 1] 1 is a side view showing an entire drill according to a first embodiment of the present invention. [Diagram 2] 1 is a perspective view showing an entire drill according to a first embodiment of the present invention. [Diagram 3] FIG. 1 is a perspective view showing a drill tip according to a first embodiment of the present invention. [Figure 4] FIG. 2 is a schematic diagram for explaining positive and negative rake angles of a drill. [Diagram 5] FIG. 4 is a side view showing the entire drill according to the second embodiment of the present invention. [Figure 6] FIG. 11 is a perspective view showing a drill tip according to a second embodiment of the present invention. [Figure 7] 4 is a photograph showing the state of the tip portion after a drilling test was conducted using the drill according to the first embodiment of the present invention. [Figure 8] 1 is a photograph showing the state of the tip portion after a drilling test was conducted using the drill described in Patent Document 1. [Figure 9] FIG. 1 is a diagram showing results of a drilling test of the drill according to the first embodiment of the present invention and the drill described in Patent Document 1. [Figure 10] FIG. 1 is a diagram showing the structure of a drill described in Patent Document 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. These are essentially preferred examples and are not intended to limit the scope of the invention, its applications, or its uses. It is not intended to

[0017] FIG. 1 is a side view showing an entire drill according to a first embodiment of the present invention. The body 2 has a shank 3 formed at one end and a blade 4. The blade 4 has a shank extending from its tip. A chip discharge groove 6 is formed in the recess 3 and is connected to the cutting edge 5.

[0018] FIG. 2 is a perspective view showing the entire drill according to the first embodiment of the present invention. The blade has a shank 3 formed at one end of the body 2 and a cutting edge 4. The feature of the present invention is the cutting edge. The first cutting edge 14 is formed at the boundary between the first thinning surface 10 and the first flank surface 11. A second flank 13 is formed on the side opposite to the first flank 11 in the direction of rotation. The drill bit is located at the tip end of the first thinning surface 10 and is in contact with the first thinning surface 10. A second thinning surface 12 is formed on the opposite side to the rotation direction. A second cutting edge 15 is formed at the boundary ridge with the flank 11 . A chisel edge 16 is formed between the two opposing first flank surfaces 11. The discharge surface 13 is connected to the chip discharge groove 6.

[0019] The first cutting edge 14 is connected to the outer periphery of the drill. However, it is not necessary to be limited to this form, and it is possible to use any other type such as the drill of Patent Document 1. The chip discharge groove 6 is used as the rake face, and a relief surface is formed on the outer peripheral surface of the drill, and the main cutting edge is It may also be provided on the outer periphery of 14.

[0020] FIG. 3 is an enlarged oblique view of the cutting edge 5 at the tip of the drill 1 according to the first embodiment of the present invention shown in FIG. FIG. 1 is a perspective view of a chip discharge groove 6, a first flank surface 10, a first flank surface 11, a second flank surface 12, and a The cutting surface 12, the second flank surface 13, the first cutting edge 14, the second cutting edge 15, and the chisel edge 16 are shown in FIG. This is as shown, and the explanation is omitted.

[0021] FIG. 4 is a schematic diagram for explaining the positive and negative rake angles of a drill. FIG. 4(A) shows a drill with a positive rake angle. Figure 4(B) shows the case where the rake angle is a positive angle, and Figure 4(B) shows the case where the rake angle is a negative angle. In the case of (A), the rake angle is a positive angle, and in the case of (B), the rake angle is a negative angle. If the cutting angle is a right angle, the cutting edge is sharp and cuts into the workpiece sharply, causing the drill bit to slip. It becomes more difficult.

[0022] FIG. 5 is a perspective view showing the entire drill of the second embodiment of the present invention. The drill has almost the same structure as the drill of the first embodiment, but the drill of the first embodiment has a chisel edge at the tip. However, the drill of the second embodiment shown in FIG. 5 has no chisel edge and its tip is at point P It is as follows. The chisel edge increases the thickness of the second thinning surface 12. However, when the chisel edge is removed, the thickness of the tip becomes smaller, but the tip becomes thinner. The other parts are the same as in Figure 2, so the explanation will be omitted.

[0023] FIG. 6 is a perspective view showing a tip portion of a drill according to a second embodiment, in which a chisel edge is formed at the tip P. Other than this, the drill is the same as that of the first embodiment shown in FIG. 3, so a description thereof will be omitted.

[0024] 7(A) and 7(B) are diagrams showing the state after a drilling test was carried out using the drill (example) of the first embodiment. 8(A) and 8(B) are photographs showing the state of the tip of the drill described in Patent Document 1. The photograph shows the state of the tip of the pipe (comparative example) after a puncture test. The puncture test conditions are as follows: Shows. <Drilling test conditions> (1) Drill shape: Both the example and the comparative example have a diameter of 3.2 mm. The core thickness of the example is The core thickness of the comparative example was 1.2 mm, while the core thickness of the comparative example was 0.8 mm. (2) Subject to be drilled: cortical bone sheet (SAW3401-06) in the form of a plate having a thickness of 10 mm. (3) Rotation speed: 760RPM (4) Drill pressure: 30N

[0025] FIG. 7(A) is a photograph of the cutting edge after the drilling test of Example 1, and no damage was observed. Figure 7(B) is a photograph of the blade edge on the opposite side of Figure 7(A), and this photograph also shows no damage. It couldn't be seen. FIG. 8(A) is a photograph of the cutting edge after a drilling test of the comparative example. The circled area shows the cutting edge. Damage from peeling was observed. Figure 8(B) is a photograph of the cutting edge on the opposite side to that of Figure 8(A). The cutting edge had a large dent. The damage was 0.84 mm from the tip and had a long From these observations, the drill of the embodiment of the present invention was larger than that of the comparative example. It appears to be much more durable than

[0026] Fig. 9(A) shows the test results when a drilling test was performed under the above conditions. The drilling time for the drill No. 1 was 11 seconds, while the comparative example described in Patent Document 1 took 20 seconds, which is a significant difference. There was a big difference. 1 shows the results of a drilling test performed when the plate was tilted at an angle of 45°. The drilling time of the drill is 16 seconds, while the comparative example described in Patent Document 1 takes 22 seconds. In addition, the sliding distance of the drill when tilted at 45° was different from that of the drill of the first embodiment of the present invention. The sliding distance of the roller is 4 mm / sec, while that of the comparative example described in Patent Document 1 is 8 mm, which is clearly There was a difference.

[0027] FIG. 9(B) shows the results of the drilling test performed three times under the above conditions. The drilling time of the drill of the first embodiment of the present invention was between 13 and 16 seconds, with little change. However, in the comparative example described in Patent Document 1, the time varies greatly from 17 seconds to 47 seconds. It was found that the durability of the drill was significantly better than that of the comparative example.

[0028] The reason why the durability of the drill of the first embodiment of the present invention is better than that of the comparative example is that the damage to the cutting edge While almost no scratches were observed in the drill of the first embodiment of the present invention shown in FIG. As shown in Fig. 8, this is thought to be due to damage occurring in a single drilling test. do. [Industrial Applicability]

[0029] As described above, the drill of the present invention has a sharp cutting edge, and is useful in, for example, surgery for drilling a bone. The drill bit can be suitably used as a drill having excellent durability. [Explanation of symbols]

[0030] 1; Drill 2; Drill body 3: Shank section 4;Blade part 5: Cutting edge 6; Chip discharge groove 10; First thinning surface 11: First relief face 12; Second thinning surface 13: Second relief face 14; First cutting edge 15; 2nd cutting edge 16;Chisel Edge P; tip point

Claims

1. A chip discharge groove formed on the outer periphery of a drill body that is rotated about an axis; A chip discharge groove is formed from the outer periphery of the drill body across the chip discharge groove toward the tip side obliquely upward. a first thinning surface; A first cutting edge that becomes a main cutting edge is formed on a boundary ridge with the first thinning surface, a first flank surface formed on the opposite side to the drill rotation direction in contact with the running surface; A tip side of the first thinning surface, which is in contact with the first thinning surface and is rotated in the direction of the drill rotation. a second thinning surface formed on the opposite side to the first thinning surface; a second cutting edge formed on a boundary ridge between the second thinning surface and the first flank surface; A drill having a

2. A second rake angle formed by the second thinning surface of the second cutting edge is a regular angle.

2. The drill according to claim 1.

3. The drill according to claim 2, wherein the second rake angle is between 20° and 60°.

4. The method according to any one of claims 1 to 3, wherein the length of the chisel edge formed at the tip is zero. Drill.

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