Hole saw

Abstract

To provide a hole saw having a simple structure and capable of preventing a cutting piece from being pinched. [Solution] The blade portion 6 of the hole saw 1 is composed of a long blade 7 and a short blade 8, each of which has a different length from the base portion 5, and the first long blade tip portion 11 of the long blade 7, which has the longest length L1 from the groove portion 15, is positioned higher in the tip direction than the first short blade tip portion 13 of the short blade 8, which has the longest length L2 from the groove portion 15.

Description

Technical Field

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

Background Art

[0002] Conventionally, as a hole saw that is detachably attached to an electric drill, for example, there is an invention described in Patent Document 1 below (hereinafter, the invention described in Patent Document 1 is referred to as "the invention of Document Public Knowledge 1"). In the invention of Document Public Knowledge 1, inside a cylindrical blade body having a blade formed at its tip, a piercing body protruding toward the tip and a pressing body pushed toward the tip by a coil spring are arranged. When a hole is made in a cutting target, a cut piece of the cutting target cut into the same shape as the inner diameter of the cylindrical blade body remains inside the cylindrical blade body, and the pressing body pushed by the coil spring pushes out the cut piece.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the disc-shaped cut pieces are not always clogged, and if they are clogged, it is difficult to remove the disc-shaped cut pieces. Moreover, since members such as a pressing body and a coil spring are required in the first place, the structure is complicated.

[0005] The present invention has been proposed in view of such circumstances, and an object thereof is to provide a hole saw having a simple structure that can prevent cut pieces from being pinched.

Means for Solving the Problems

[0006] In order to achieve the above object, the hole saw according to the present invention has an annular base portion, a plurality of blade portions extending from the base portion toward the tip direction, and a groove portion formed in the base portion between the blade portions adjacent to each other in the circumferential direction. The blade portions are composed of a long blade and a short blade having different lengths from the base portion, and the tip portion of the long blade having the longest length from the groove portion in the long blade is at a position higher than the tip portion of the short blade having the longest length from the groove portion in the short blade.

[0007] The hole saw according to the present invention is characterized in that the depth of the groove portion from the long blade is deeper than the depth of the groove portion from the short blade.

[0008] The hole saw according to the present invention is characterized in that at the center of the base portion, it has a tapered protruding blade portion extending in the tip direction more than the blade portion.

Advantages of the Invention

[0009] The hole saw according to the present invention has an annular base portion, a plurality of blade portions extending from the base portion toward the tip direction, and a groove portion formed in the base portion between the blade portions adjacent to each other in the circumferential direction. The blade portions are composed of a long blade and a short blade having different lengths from the base portion, and the tip portion of the long blade having the longest length from the groove portion in the long blade is at a position higher than the tip portion of the short blade having the longest length from the groove portion in the short blade. By providing a difference in length between the blade portions, when a hole is formed in the cutting object, the chip cut off is not pinched inside the blade portions. Therefore, it is possible to prevent the chip from being pinched with a simple structure. Also, since the total length of the blade portion becomes longer by the length corresponding to the long blade, for example, even in the case of a thick wooden concrete panel or the like, a hole can be opened.

[0010] The hole saw according to the present invention is such that the depth of the groove portion from the long blade is deeper than the depth of the groove portion from the short blade. Even if the chip is pinched inside the blade portions, since the groove portion is deeper by the length of the long blade, the groove portion comes at a position deeper than the position where the chip is pinched. Therefore, it is possible to insert a tool such as a driver into the groove portion and scrape out the chip.

[0011] The hole saw according to the present invention has a tapered protruding blade portion that extends in the tip direction rather than the blade portion at the center of the root portion. The chip is supported by the protruding blade portion and separated from the blade portion, and then falls in the tip direction along the tapered shape. Therefore, the chip is not pinched inside the blades.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Mode for Carrying Out the Invention

[0013] Hereinafter, the hole saw according to the embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 show the side surfaces of the hole saw 1 according to this embodiment. In the following, the direction in which the cutting edge is located is defined as the tip direction (Tip), and the direction opposite to the tip direction is defined as the back direction (Back) (see FIG. 1).

[0014] As shown in FIGS. 1 and 2, the hole saw 1 is composed of a shank portion 2 and a blade body portion 3. The blade body portion 3 is generally cylindrical. The blade body portion 3 includes a disk-shaped pedestal portion 4, an annular root portion 5 that extends in the tip direction from the circumferential edge of the pedestal portion 4, a plurality of blade portions 6 that extend in the tip direction from the root portion 5, a protruding blade portion 16 that is disposed at the center of the root portion 5 and extends in the tip direction, and a groove portion 15 that is formed in the root portion 5 between the blade portions 6 adjacent to each other in the circumferential direction. There are four blade portions 6, and each blade portion 6 is curved along the circumferential direction. Note that the number and shape of the blade portions 6 are arbitrary.

[0015] The pedestal portion 4 has a hole formed at its center, and the tip projection (not shown) of the shank portion 2 is inserted into this hole. A protruding blade portion 16 is attached to the tip projection. The protruding blade portion 16 extends in the tip direction beyond the blade portion 6. The protruding blade portion 16 is a tapered triangular pyramid. The base portion 5 has a cylindrical shape, the blade portion 6 is connected to the tip extending in the tip direction, and a groove portion 15 is formed between the blade portions 6.

[0016] The blade portion 6 is composed of a long blade 7 and a short blade 8 with different lengths from the base portion 5. The long blade tip 9 which is the tip of the long blade 7 and the short blade tip 10 which is the tip of the short blade 8 gradually protrude in the tip direction as they go in the forward rotation direction (clockwise) of the hole saw 1. Therefore, for the long blade 7, the first long blade tip portion 11 which is the tip on the forward rotation side protrudes more in the tip direction than the second long blade tip portion 12 which is the tip on the reverse rotation side (counterclockwise), and the shape of the long blade tip 9 is an upward slope from the second long blade tip portion 12 to the first long blade tip portion 11. Similarly, for the short blade 8, the first short blade tip portion 13 which is the tip on the forward rotation side protrudes more in the tip direction than the second short blade tip portion 14 which is the tip on the reverse rotation side (counterclockwise), and the shape of the short blade tip 10 is an upward slope from the second short blade tip portion 14 to the first short blade tip portion 13.

[0017] The first long blade tip portion 11 has the longest length L from the groove portion 15 in the long blade 7 1 and the first short blade tip portion 13 has the longest length L from the groove portion 15 in the short blade 8 2 . Since the long blade 7 is longer than the short blade 8, the first long blade tip portion 11 is at a higher position than the first short blade tip portion 13. Also, the depth of the groove portion 15 from the first long blade tip portion 11 (length L 1 ) is deeper than the depth of the groove portion 15 from the first short blade tip portion 13 (length L 2 ). The groove portion 15 is formed in a U shape across between the first long blade tip portion 11 and the first short blade tip portion 13.

[0018] Next, the operation and effects of the hole saw 1 will be described.

[0019] With the hole saw 1 attached to an electric drill (not shown) and rotating, when the hole saw 1 is pressed against, for example, a concrete panel or a cutting target (not shown) made of metal or resin, a hole is formed in the cutting target. First, the protruding blade portion 16 pierces the cutting target to form a small hole, and then a circular hole is formed by shaving the periphery of the small hole with the blade portion 6. At this time, as cutting chips, a disc-shaped slice corresponding to the shape of the hole is cut out. The slice is sandwiched between the long blade 7 and the short blade 8. Since the protruding blade portion 16 is passed through and supported by the small hole, the slice is separated from the blade portion 6. The slice deviates in the tip direction along the tapered shape of the protruding blade portion 16 and comes off the protruding blade portion 16. (If the hole saw 1 is directed downward, the slice falls.) Therefore, the slice is not sandwiched between the long blade 7 and the short blade 8.

[0020] Also, as the long blade 7 and the short blade 8, since there is a difference in length provided in the blade portion 6, the slice cut from the cutting target is not sandwiched between the long blade 7 and the short blade 8. Therefore, it is possible to prevent the slice from being sandwiched with a simple structure. In addition, since the entire length of the blade portion 6 becomes longer by the amount corresponding to the long blade 7, it is possible to make a hole even in a thick wooden concrete panel in particular.

[0021] Even if it is sandwiched between the long blade 7 and the short blade 8, since the groove portion 15 is deeper by the amount of the long blade 7, the groove portion 15 comes to a position deeper than the position where the slice is sandwiched. Therefore, it is possible to insert a tool (not shown) such as a driver into the groove portion 15 and scrape out the slice.

[0022] As described above, the embodiments of the present invention have been described in detail, but the present invention is not limited to the above embodiments. And the present invention can be variously designed without departing from the matters described in the scope of utility model registration claims.

Explanation of Signs

[0023] 1 Hole saw 2 Shank portion 3 Blade body portion 4 Base part 5 Root part 6 Blade part 7 Long blade 8 Short blade 9 Long blade tip 10 Short blade tip 11 First long blade tip part (long blade tip part) 12 Second long blade tip part 13 First short blade tip part (short blade tip part) 14 Second short blade tip part 15 Groove part 16 Protruding blade part L 1,2 Length

Claims

1. A circular root portion; A plurality of blade portions extending from the base portion toward the tip direction; a groove portion formed in the base portion between the blade portions adjacent in the circumferential direction, The blade portion is composed of a long blade and a short blade each having a different length from the base portion, a tip end portion of the long blade having a maximum length from the groove portion is located higher than a tip end portion of the short blade having a maximum length from the groove portion; A hole saw characterized by:

2. The depth of the groove from the long blade is deeper than the depth of the groove from the short blade.

2. A hole saw according to claim 1.

3. A tapered protruding blade portion is provided at the center of the base portion and extends further toward the tip than the blade portion.

3. A hole saw according to claim 1 or 2.

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