Hole saw

Abstract

To provide a hole saw in which a cut piece is not caught.SOLUTION: A blade body part 4 of a hole saw 1 includes: a disk-shaped pedestal part 5; an annular root part 6 extending from a circumferential edge of the pedestal part 5 in a distal end direction; a plurality of blade parts 7 extending from the root part 6 in the distal end direction; a tapered projection blade part 11 arranged in the center of the root part 6 and extending in the distal end direction further than the blade parts 7; and a groove part 12 formed in the root part 6 between blade parts 7a, 7b adjacent each other in a circumferential direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hole saw that is detachably attached to an electric drill. [Background technology]

[0002] Conventionally, an example of a hole saw that can be attached to and detached from an electric drill is the invention described in Patent Document 1 below (hereinafter, the invention described in Patent Document 1 will be referred to as the "Publication 1 invention"). The Publication 1 invention has an annular blade and a magnet portion located at the center of the blade. According to the Publication 1 invention, chips generated during cutting are attracted to the magnet portion, thereby reducing the scattering and dropping of chips. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-62021 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if the cutting object is made of resin, for example, the chips and pieces will not be attracted to the magnet, and the pieces will get caught inside the blade, requiring a complicated process to remove them.

[0005] The present invention has been proposed in view of the above circumstances, and has as its object to provide a hole saw that does not trap cutting pieces. [Means for solving the problem]

[0006] In order to achieve the above object, the hole saw of the present invention is characterized by having an annular root portion, a plurality of cutting edges extending from the root portion toward the tip, a tapered protruding cutting edge at the center of the root portion that extends further toward the tip than the cutting edges, and grooves formed in the root portion between adjacent cutting edges in the circumferential direction.

[0007] The hole saw according to the present invention is characterized in that the groove portion is formed with a chamfering blade portion for chamfering the edge of a hole to be formed in the cutting object.

[0008] The hole saw according to the present invention is characterized in that the outer surface of the base portion extends outward beyond the cutting edge, and the chamfered cutting edge protrudes toward the tip and extends from the inside to the outside of the base portion.

[0009] The hole saw according to the present invention is characterized in that the groove portion has a first groove portion curved in the opposite direction to the tip direction, and a second groove portion circumferentially adjacent to the first groove portion and curved in the opposite direction to the tip direction, and the chamfering blade portion is raised in the tip direction between the first groove portion and the second groove portion.

[0010] The hole saw according to the present invention is characterized in that a sloped portion is formed on the outer surface of the base portion, the sloped portion widening outward as it extends in the direction opposite to the tip.

[0011] The hole saw according to the present invention is characterized in that a flange portion is formed on the outer surface of the base portion below the inclined portion, and projects outward beyond the inclined portion. [Effects of the Invention]

[0012] The hole saw according to the present invention has an annular base portion, a plurality of cutting edges extending from the base portion toward the tip, a tapered protruding cutting edge at the center of the base portion extending further toward the tip than the cutting edges, and grooves formed in the base portion between circumferentially adjacent cutting edges. When a hole is cut in a cutting object, a piece of the cutting object would normally be pinched between the cutting edges, but the cutting edge is supported by the protruding cutting edges and separated from the cutting edges, and falls toward the tip along the tapered shape. Therefore, the cutting edge does not become pinched between the cutting edges.

[0013] The hole saw according to the present invention has a chamfering blade formed in the groove for chamfering the edge of a hole to be cut in an object to be cut. Therefore, the edge of the hole in the object to be cut is chamfered. Furthermore, because the chamfering blade is formed in the groove, no complicated processing is required to form the chamfering blade.

[0014] In the hole saw according to the present invention, the outer surface of the base portion extends outward beyond the cutting portion, and the chamfering blade portion projects toward the tip and extends from the inside to the outside of the base portion. Because the chamfering blade portion extends outward beyond the cutting portion, the edge of the hole formed by the cutting portion is chamfered by the chamfering blade portion.

[0015] In the hole saw according to the present invention, the groove portion has a first groove portion curved in the direction opposite to the tip direction and a second groove portion circumferentially adjacent to the first groove portion and curved in the direction opposite to the tip direction, and the chamfering blade portion is protruded in the direction toward the tip between the first groove portion and the second groove portion. Because the chamfering blade portion is formed as the boundary between the first groove portion and the second groove portion, it is easy to manufacture the chamfering blade portion.

[0016] The hole saw according to the present invention has a sloped portion formed on the outer surface of the base portion that widens outward in the direction opposite to the tip. The sloped portion chamfers the edge of the hole to be cut, resulting in a smooth edge of the hole.

[0017] The hole saw according to the present invention has a flange formed on the outer surface of the base portion below the sloped portion, which projects outward beyond the sloped portion. The flange abuts against the edge of the hole to be cut, thereby restricting movement of the hole saw in the insertion direction relative to the hole. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a side view of a hole saw according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a side view of a hole saw according to a second embodiment of the present invention. [Figure 3] FIG. 3 is a top view of a hole saw according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] A hole saw according to a first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 shows a side view of a hole saw 1 according to the first embodiment. In the following, the direction in which the cutting edge is located will be referred to as the tip, and the direction opposite to the tip will be referred to as the back (see Figs. 1 and 2).

[0020] As shown in Figure 1, the hole saw 1 is comprised of a shank portion 2 and a blade body portion 4. The blade body portion 4 has a disk-shaped base portion 5, an annular root portion 6 extending from the circumferential edge of the base portion 5 toward the tip, multiple cutting portions 7 extending from the root portion 6 toward the tip, a protruding cutting portion 11 disposed at the center of the root portion 6 and extending toward the tip, and grooves 12 formed in the root portion 6 between the cutting portions 7a, 7b adjacent in the circumferential direction. The number and shape of the cutting portions 7 are arbitrary.

[0021] The base portion 5 has a hole formed in its center, into which the tip projection 3 of the shank portion 2 is inserted (see FIG. 3). A protruding blade portion 11 is attached to the tip projection 3. The protruding blade portion 11 extends further distally than the blade portion 7. The protruding blade portion 11 is a tapered triangular pyramid. The base portion 6 is cylindrical, and the blade portion 7 is connected to the tip of the protruding blade portion 11, with a groove 12 formed between the blade portions 7a, 7b. The cutting edge 8 of the blade portion 7 gradually protrudes distally in the forward (clockwise) rotation direction of the hole saw 1. Therefore, the forward rotation end 9 of the blade portion 7 protrudes distally more than the reverse rotation end 10 of the reverse rotation end 10, and the shape of the cutting edge 8 slopes upward from the reverse rotation end 10 to the forward rotation end 9. The groove 12 is formed in a U-shape across the area between the forward rotation side end 9 of the cutting portion 7a and the reverse rotation side end 10 of the cutting portion 7b.

[0022] Next, the operation and effect of the hole saw 1 will be described.

[0023] When the hole saw 1 is attached to an electric drill (not shown) and rotates, the hole saw 1 is pressed against a metal or resin cutting target (not shown), forming a hole in the cutting target. First, the protruding blade portion 11 penetrates the cutting target, forming a small hole. Then, the blade portion 9 scrapes around the small hole, forming a circular hole. At this time, a circular piece corresponding to the shape of the hole is cut out as cutting waste. The piece would be sandwiched between the blade portions 7, but since the protruding blade portion 11 is supported by passing through the small hole, the piece is separated from the blade portion 7. The piece shifts toward the tip along the tapered shape of the protruding blade portion 11 and falls off the protruding blade portion 11 (if the hole saw 1 is facing downward, the piece falls). Therefore, the piece does not become sandwiched between the blade portions 7.

[0024] Next, a hole saw according to a second embodiment of the present invention will be described with reference to the drawings. Fig. 2 shows a side view of a hole saw 201 according to the second embodiment, and Fig. 3 shows the tip side of the hole saw 201. Note that the following mainly describes the configuration that differs from the hole saw 1 according to the first embodiment, and a description of the configuration that is the same as that of the hole saw 1 is omitted.

[0025] 2 and 3, the outer surface of the base portion 206 of the hole saw 201 projects outward beyond the cutting edge portion 207. More specifically, the outer surface of the base portion 206 has a sloped surface 220 and a flange portion 221 connected to the lower portion of the sloped surface 220. The sloped surface 220 is an inclined surface that widens outward toward the rear, which is the opposite side from the tip direction, and is annular in shape along the circumferential direction of the base portion 206. The flange portion 221 is annular in shape along the circumferential direction of the base portion 206, projecting outward beyond the sloped surface 220 below the sloped surface 220.

[0026] The groove portion 212 of the base portion 206 has a first groove portion 222 and a second groove portion 223 that curve backward toward the flange portion 221. The first groove portion 222 and the second groove portion 223 are adjacent to each other in the circumferential direction of the base portion 206. The boundary between the first groove portion 222 and the second groove portion 223 is raised toward the tip, forming a chamfered blade portion 224. The chamfered blade portion 224 protrudes toward the tip to an extent that does not reach the height of the blade portion 207. Therefore, the chamfered blade portion 224 is located below the blade portion 207. The chamfered blade portion 224 extends from the inside to the outside of the base portion 206, further outward than the blade portion 207. In other words, the base portion 206 is thicker than the blade portion 207 by the amount of the bevel portion 220, and the chamfered blade portion 224 extends across the thickness of the base portion 206, so that the chamfered blade portion 224 extends further outward than the cutting edge 208.

[0027] Next, the operation and effect of the hole saw 201 will be described.

[0028] The rotating hole saw 201 is pressed against the cutting object, and the blade portion 207 forms a circular hole in the cutting object. The chamfering blade portion 224 then chamfers the edge of the hole. In particular, the chamfering blade portion 224 is formed on the sloped surface 220, which smooths the edge of the hole. Thus, the edge of the hole in the cutting object is chamfered. When the flange portion 221 contacts the edge of the hole, the hole saw 201 is restricted from moving in the insertion direction relative to the hole, preventing further chamfering. The chamfering blade portion 224 is formed as a boundary between the first groove portion 222 and the second groove portion 223 formed in the groove portion 212, making it easy to manufacture.

[0029] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various design modifications can be made to the present invention without departing from the scope of the claims. [Explanation of symbols]

[0030] 1, 201 hole saw 2, 202 Shank 3 Tip protrusion 4, 204 Blade body 5, 205 base 6, 206 Root 7, 7a~b, 207 blade part 8, 208 cutting edge 9 Forward rotation end 10 Reverse rotation end 11, 211 protruding blade 12, 212 Groove 220 Slope 221 Flange 222 First groove 223 Second groove 224 Chamfered blade part

Claims

1. An annular root portion; A plurality of blade portions extending from the base portion toward the tip end; a tapered protruding blade portion extending further toward the tip than the blade portion at the center of the base portion; and a groove formed in the root portion between the blade portions adjacent in the circumferential direction. A hole saw characterized by:

2. The groove portion A chamfering blade portion is formed to chamfer the edge of a hole formed in a cutting object.

2. The hole saw of claim 1.

3. The outer surface of the base portion protrudes outward beyond the blade portion, The chamfered blade portion protrudes toward the tip and extends from the inside to the outside of the base portion.

3. The hole saw according to claim 2.

4. The groove portion is a first groove portion curved in a direction opposite to the tip direction; a second groove portion that is adjacent to the first groove portion in the circumferential direction and curved in the opposite direction to the tip direction, The chamfered blade portion is protruded toward the tip between the first groove portion and the second groove portion.

4. The hole saw of claim 3.

5. A sloped portion that widens outward toward the opposite side to the tip direction is formed on the outer surface of the base portion.

5. A hole saw according to claim 3 or claim 4.

6. A flange portion is formed on the outer surface of the base portion below the inclined portion, and protrudes outward from the inclined portion.

6. A hole saw according to claim 5.

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