JPH0919817A - Core bit mounting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a washer from easily slipping off from a shank when a core bit is to be removed, by installing the washer capable of being threadedly engaged by the shank between the core bit and shank. SOLUTION: When a core bit 6 is to be removed from a shank 1, tool engaging part 5b of a washer 5 is pinched by a spanner, etc., and turned in the direction the core bit 6 is retreated in screwing. At this time, the core bit 6 rotates in the same direction owing to friction between the washer 5 and core bit 6 in contacting, and engagement with male threads 2 is loosened, and it is possible to remove if the core bit 6 is turned by hand in the retreating direction. Then the washer 5 is engaged by the male threads 2, and rotation in the retreating direction enables removing from the male threads 2, so that replacement can be made easily even when the washer 5 goes invalid due to wear, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a core bit mounting device.

[0002]

2. Description of the Related Art A conventional core bit will be described with reference to FIGS. As shown in FIG. 3, at the tip of the shank 1,
A screw portion for detachably engaging the core bit 6, that is, a male screw 2, is provided in a protruding manner, and a male screw provided on the shank 1 is provided between the contact surface 4 of the shank 1 and the contact surface of the core bit 6. A washer 5 that is inserted through the 2 is provided. On the outer periphery of the washer 5, as shown in FIG. 4, an engaging surface 5b which can be engaged with a tool such as a spanner is formed in a flat shape. When removing the core bit 6 from the shank 1, by rotating the washer 5 with a spanner or the like, the core bit 6 was rotated and removed by frictional contact between the washer 5 and the core bit 6.

[0003]

The shape of the washer 5 used in the conventional core bit mounting device is only inserted into the male screw of the shank, and when the core bit is removed from the shank, the washer can be easily removed. There was a problem that the washer 5 was lost because it was slipped out.

An object of the present invention is to remove a core bit when removing it.
It is to prevent the washer from slipping out of the shank easily.

[0005]

The above object is achieved by providing an internal thread of the washer with an internal thread corresponding to the external thread for mounting the core bit. Further, a groove portion having a width equal to or larger than the plate thickness of the washer and having a diameter smaller than the root diameter of the male screw is provided on the protruding surface side of the male screw, and the washer is inserted into the male screw while being screwed into the groove and loosely fitted therein. It is achieved by

[0006]

The core bit mounting structure configured as described above acts so that the washer is loosely fitted in the groove portion of the male screw unless the washer is intentionally screwed back.

[0007]

Embodiments of the present invention will be described with reference to FIGS. On the tip side of the shank 1, a male screw 2 that can be screwed into a female screw of the core bit 6 is provided so as to project. A groove portion 3 is formed on the male screw projecting surface 4 side of the male screw 2,
The washer 5 is loosely fitted here. The diameter of the groove 3 is smaller than the shape of the valley of the male screw 2, and the width thereof is larger than the plate thickness of the washer 5. The internal diameter of the washer 5 has a male screw 2
A female screw 5a that can be screwed into is formed. Further, the washer 5 has a pair of tool engaging portions 5b formed in a flat shape on the outer peripheral surface at positions opposite to each other by 180 °. 7 is a center pin for aligning the drilling position. When removing the core bit 6 from the shank 1, the tool engaging portion 5b of the washer 5
Is clamped by a spanner or the like, and is rotated in the screw retreating direction of the core bit 6. At this time, due to the friction between the contact surfaces of the washer 5 and the core bit 6, the core bit 6 also rotates in the same direction and the engagement with the male screw 2 is loosened. After that, the core bit 6 can be removed by manually rotating it in the screw retraction direction. Here, the washer 5 remains loosely fitted in the groove portion 3 and does not fall off from the male screw 2. Further, the washer 5 can be removed from the male screw 2 by screwing the washer 5 onto the male screw 2 and rotating in the screw retracting direction. Therefore, even when the washer 5 becomes unusable due to wear or the like, it can be easily replaced.

[0008]

According to the present invention, since the washer can be loosely fitted in the male screw portion of the shank, the washer does not easily fall off when the core bit is replaced, so that the washer can be prevented from being lost.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a core bit mounting device according to the present invention.

FIG. 2 is a perspective view showing a washer according to the present invention.

FIG. 3 is a cross-sectional view showing a conventional core bit mounting device.

FIG. 4 is a perspective view showing a conventional washer.

[Explanation of symbols]

1 is a shank, 2 is a male screw, 3 is a groove portion, 4 is a male screw projecting surface, 5 is a washer, and 5a is a female screw.

Claims (3)

[Claims] 1. A core bit mounting device comprising a shank, a core bit screwed to the shank, and a washer disposed between the core bit and the shank, wherein the shank can be screwed with the shank. A core bit mounting device comprising a washer disposed between the core bit and the shank. 2. The core bit mounting device according to claim 1, wherein a screw groove for screwing with a screw provided on the shank is provided inside the washer. 3. The core bit mounting device according to claim 1, wherein the shank is provided with a groove for accommodating the washer.