JP2001098874A - Drill bit structure for rock drill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drill bit structure which allows for a separate retractive bit to be installed therein, and can exchange only a bit when the retractive bit is not worn, to thereby cut wastes. SOLUTION: In the drill bit structure, a cylindrical retractive bit 8 having teeth 11 formed at the rear end thereof, has an enlarged-diameter portion 13 into which a stopper 14 is fitted, and the enlarged-diameter portion 13 is covered cover the region of a rod 1 from a taper portion 3 to a male screw 2. A bit 4, having a teeth (buttons) 5 formed only at the front end thereof, has a female screw 3 thereof screwed and clamped, whereby the retractive bit 8 is pressed and fixed to the taper portion 3 by the thrust of the screw. Cutting torque due to the retractive bit 8 is transmitted by the engagement of an engaging depression 7 formed in the bit 4 with an engaging projection 12 formed on the retractable bit 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drill bit structure for use in a drilling device such as a rock mass, and more particularly to a drill bit structure in which a female screw of a bit is screwed to a male screw at a tip of a rod. It is suitable for.

[0002]

2. Description of the Related Art In general, a drill bit used in a drilling device is mounted by screwing a female screw of a bit into a male screw at a tip of a rod so that only a bit portion can be replaced. This bit structure has teeth (buttons) only at the tip of the bit, that is, the side to be drilled,
As shown in FIG. 3, there is a type in which a tooth T is provided at the rear end of the bit B. Of the latter, the latter is also called a retract bit, and when the rod R is collected, the dust that has fallen into the drilled hole is separated by the teeth T at the rear end of the bit B, thereby easily removing the bit portion. It was done.

[0003]

Incidentally, the retract bit is expensive because teeth are formed at the front and rear ends of one drill bit. Further, the tooth at the rear end of the bit may or may not be worn depending on the properties of the rock. In other words, depending on the bedrock, the powder may not fall into the drilled hole.
The teeth at the rear end of the bit do not wear. However, the bit tip teeth are definitely worn by the drilling operation, and in some cases, the expensive retracting bit must be replaced entirely, even though the bit tail teeth are not completely worn. There is a problem that there is much waste.

[0004] The present invention has been developed in view of these problems, and the drill at the rear end of the bit, that is, the retract bit, can be separated and easily detached to reduce waste. It is an object to provide a drill bit structure for use.

[0005]

In order to achieve the above object, a drill bit structure for a drill according to claim 1 of the present invention is provided by screwing a female screw of a bit into a male screw at the tip of a rod. It is a drill bit structure for drilling to be attached, wherein a separate retract bit is interposed between the bit and the rod, and the retract bit is pushed by the thrust of a screw at the time of screwing the rod and the bit. It is characterized in that the rod is pressed against and fixed to a tapered portion provided behind the male screw at the tip of the rod.

According to a second aspect of the present invention, there is provided a drill bit structure for a drill according to the first aspect of the present invention, wherein a joint between the bit and the retract bit is capable of transmitting torque to each other. A joint is formed.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of a drill bit structure for drilling according to the present invention. The rod 1 used in this drill bit structure is a conventional one and does not require any particular change. Therefore, a tapered portion 3 for cutting the male screw 2 is provided behind the male screw 2 at the tip of the rod 1.

The bit 4 used in this embodiment is provided with teeth (buttons) 5 only at the distal end portion. In particular, in this embodiment, since a guide portion is provided on a later-described retract bit, Not required for bit 4 side. From the rear end of the bit 4, a female screw 6 to be screwed with the male screw 2 of the rod 1 is formed. At the rear end of the bit 4, an engagement recess 7 into which an engagement projection of a retract bit described later is fitted is formed. The engagement concave portion 7 of the present embodiment has a vertical surface on the side opposite to the rotation direction of the rod 1 and a tapered surface on the opposite side.

On the other hand, the retract bit 8 is a cylindrical member having an inner diameter approximately equal to the outer diameter of the male screw 2 at the distal end of the rod 1, and a guide 9 and a groove 10 are formed on the outer periphery. At the rear end of the retract bit 8, a rod 1
The teeth 11 are formed to separate the powdered powder during storage. At the tip of the retract bit 8, an engaging projection 12 that fits into the engaging recess 7 of the bit 4 is formed. Also,
At the rear end portion of the inner diameter portion of the retract bit 8, an enlarged diameter portion 13 for accommodating a stopper described later is formed.

As shown in FIG. 2, the stopper 14 has a tapered inner surface 1 which is in close contact with the tapered portion 3 of the rod 1.
The outer diameter of the ring member has a diameter that fits into the enlarged diameter portion 13 of the retract bit 8. The inner diameter of the stopper 14 is made slightly smaller than the actual outer diameter of the male screw 2 at the distal end of the rod 1 in order to increase the joint area between the tapered inner surface 15 and the tapered portion 3 of the rod 1. The stopper 14 is screwed in from the tip of the rod 1 while rotating in accordance with the lead of the male screw 2. The inner diameter of the stopper 14 is smaller than the maximum diameter of the tapered portion 3.

Therefore, when assembling the drill bit 4 structure, the tapered inner surface 15 of the stopper 14 is brought into close contact with the tapered portion 3 of the rod 1 as shown in FIG. When the retract bit 8 is covered from the tapered portion 3 to the male screw 2 and finally the female screw 6 of the bit 4 is screwed into the male screw 2 of the rod 1, the thrust of the screw The retract bit 8 is pressed and fixed to the tapered portion 3 of the rod 1 via the tapered inner surface 15 of the stopper 14. In actual use, particularly when the rod 1 is collected, the rotational torque of the rod 1 is applied to the retract bit 8 from the bit 4 screwed to the rod 1 via the engaging concave portions 7 and the engaging convex portions 12. Since the powder is transmitted, the powder that has fallen into the hole can be reliably separated by the teeth 11.

When the bit 4 and the retract bit 8 are exchanged, simply loosening the screw of the bit 4
Since the bit 4, the retract bit 8, and the stopper 14 can be disassembled, it is sufficient to replace only the worn member as needed. Therefore, according to the drill bit 4 structure of the present embodiment, for example, when the retract bit 8 has not been completely worn, only the bit 4 can be replaced at the same time when the retract bit 8 has also been worn. And waste can be reduced.

[0013]

As is apparent from the above description, according to the drill bit structure for drilling according to the first aspect of the present invention, an individual retract bit is interposed between the bit and the rod. When the female screw of the bit is screwed into the male screw at the tip of the rod, the retracting bit is pressed and fixed to the tapered portion behind the male screw by the thrust of the screw. The bit can be easily attached to and detached from an existing rod, and a separate retract bit can be used until it is worn, thereby reducing waste.

Further, according to the drill bit structure for drilling according to the second aspect of the present invention, an engagement portion capable of transmitting torque to each other is formed at a joint portion between the bit and the retract bit, so that the retract bit is formed. The torque to the bit is reliably transmitted from the rod via the bit, so that the powder can be reliably separated when the rod is stored.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a drill bit structure for drilling according to the present invention, wherein (a) is a front view and (b) is a longitudinal sectional view.

FIG. 2 shows details of the stopper of FIG. 1;
(A) is a side view, (b) is a front view.

3A and 3B show an example of a conventional drill bit structure for drilling, wherein FIG. 3A is a front view and FIG. 3B is a longitudinal sectional view.

[Explanation of symbols]

 1 is a rod 2 is a male screw 3 is a tapered portion 4 is a bit 5 is a tooth (button) 6 is a female screw 7 is an engagement recess (engagement portion) 8 is a retract bit 9 is a guide 10 is a groove 11 is a tooth 12 Mating part (engaging part) 13 is enlarged diameter part 14 is stopper 15 is tapered inner surface

Claims (2)

[Claims] 1. A drill bit structure for drilling, wherein a female screw of a bit is screwed into a male screw at the tip of a rod, and a separate retract bit is interposed between the bit and the rod. The retracting bit is pressed and fixed to a tapered portion provided behind a male screw at the tip of the rod with a thrust of a screw when the rod and the bit are screwed together. Drill bit structure. 2. The drill bit structure for drilling according to claim 1, wherein an engagement portion capable of transmitting torque to each other is formed at a joint between the bit and the retract bit.