JPH0668235B2 - Bit for drilling soft rock - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention is based on a rock drilling machine, a powder charging hole, a rock bolt hole,
The present invention relates to a bit for drilling soft rock, which is attached to a rock drilling machine when drilling anchor bolt holes and the like in soft rock.

[Prior art]

Conventionally, as shown in FIG. 5, a bit of a rock drill has a head 1 that is relatively long with respect to the entire length in the axial direction, and a body portion 2 and a joint portion 3 that follow the head portion 1 are gradually reduced in diameter. However, the correspondence to the type of rock usually depends on the shape of the chip. That is, looking at the soft rock drilling bit used for drilling this into soft rock, the wedge angle of the tip of the tip is made smaller and the radius of curvature of the bending wheel is made larger than that used for hard rock. is there.

[Problems to be Solved by the Invention]

However, even if only the shape of the tip as described above is applied to soft rock, the head 1 is relatively long, and due to this, the boring powder adheres to the outer periphery of the head 1 during drilling, In addition, there is a problem in that the so-called jamming phenomenon, in which the rotation resistance of the bit is increased to prevent perforation, cannot be prevented, and the hole wall after perforation cannot be collapsed. An object of the present invention is to solve the above-mentioned problems that often occur particularly in soft rock drilling by devising the overall shape of the bit.

[Means for solving the problem]

The bit of the present invention comprises a bit head portion a, a body portion b, and a joint portion c, and its axial length is the same as that of a conventionally known bit. The bit head a has a relatively short length from the front end face to the vicinity of the embedded bottom portion of the chip 4, and has a relatively deep and wide head recess 5 on the outer periphery thereof. The outer peripheral surface of the body portion b has a diameter smaller than that of the bit head portion a. The joint portion c has an axial length shorter than that of the bit head a, and an outer diameter smaller than the outer diameter of the bit head a but larger than the outer diameter of the body portion b, and its outer circumference. On the surface, relatively shallow and wide joint recesses 9 and lands 10 are alternately formed.

[Work]

The mixed fluid of boring powder generated by drilling and the pressure fluid for discharging it to the outside of the hole is easily taken into the recess of the head and does not wrap around to the outer peripheral surface of the bit head. There is no risk of contacting the surface and increasing the rotational resistance. There is little resistance to the flow of the mixed fluid in the body portion toward the joint portion, and therefore the flow is smoothly performed. Furthermore, the mixed fluid can be applied to the hole wall by the action of the land portion accompanying the rotation of the bit itself. The joint recess allows the excess mixed fluid that could not be applied to the wall of the hole to flow backward smoothly.

【Example】

The illustrated embodiment will be described in detail below. The bit A of the present invention comprises a bit head a in which the tip 4 is embedded in the front end surface in a front cross shape, a body part b and a joint part c, and the overall length in the axial direction thereof is shown in FIG. It is the same as the total length of the bit. The outer diameter of the bit head a is the above-described known head 1 of the bit.
The outer diameter of the bit is the same as the outer diameter of the bit, but the length in the axial direction is shorter up to the vicinity of the embedded bottom portion of the tip 4 as compared with the known head 1 of the bit. In addition, the bit head a has deeper and wider head recesses 5 between the chips 4 arranged in a front cross shape as compared with the head recess 1'of the known bit head 1. Is forming. That is, the bit head portion a has the head recessed portion 5 formed as deep and wide as possible with the tip brazing portion having a minimum wall thickness necessary for maintaining the required strength. The body b is formed on the inner surface thereof, and the thread 6 threadedly engaged with the outer periphery of the tip of the rod d of the rock drill (not shown) leaves the minimum wall thickness necessary to maintain the required strength. The outer peripheral surface is made smaller in diameter than the bit head a and is continuous with the bit head a by a boundary portion 7 having a required curvature. The joint portion c has an outer diameter slightly smaller than the outer diameter of the bit head portion a, but slightly larger than the outer diameter of the body portion b, and a boundary portion with the body portion b having a required curvature. 8 are continuous with each other, and relatively shallow but wide joint recesses 9 are formed alternately with lands 10 on the outer peripheral surface thereof. The axial length of the joint portion c is set to be slightly shorter than the length of the bit head portion a. The bit A having the above structure is screwed and fixed to the tip of a rod d of a rock drilling machine (not shown) by a thread 6, and is mixed with a predetermined pressure fluid (water, air, foaming agent, etc.) according to a conventional method. A liquid, or a mixture of two or more of these, is spouted from the through hole 11 of the bit head a and rotated to be used for perforation. In this bit A, the bit head a is shorter in the axial direction and the head recess 5 is deeper and wider than the conventional one. Therefore, the chipping generated by the perforation is mixed in the pressure fluid. As a result, the mixed fluid is easily taken into the head recess portion 5 and does not go around the outer peripheral surface of the bit head a, so that it may adhere to the outer peripheral surface and increase the rotation resistance. There is no. Further, since the body portion b has a small diameter, there is little resistance to the flow of the mixed fluid in the direction of the joint portion c, and therefore the flow is smoothly performed. Further, since the diameter of the joint portion c is made slightly larger than the outer diameter of the body portion b, the flow velocity of the mixed fluid slows down at this portion. Due to the action of the land portion 10, the mixed fluid is applied to the hole wall 12, whereby the hole wall 12 is protected and stabilized, and the hole wall is prevented from collapsing. The outer diameter of the joint portion c is smaller than that of the bit head portion a even though it is larger than that of the body portion b, and the axial length thereof is shorter than that of the bit head portion a, and the outer peripheral surface thereof is relatively shallow. By forming a wide joint recess 9,
It is possible to avoid an increase in rotation resistance caused by coating the mixed fluid on the hole wall 12. Further, the joint recess 9 allows the excess mixed fluid that could not be applied to the hole wall 12 to smoothly flow rearward.

【The invention's effect】

As is clear from the above description, the bit of the present invention is screwed and fixed to the tip of the rod of a rock drill, and is rotated and pierced while ejecting a predetermined pressure fluid according to a conventional method. Yes, it has the following effects. Since the bit head is shorter in the axial direction and the head recess is deeper and wider than the conventional one, the mixed fluid formed by mixing the dust powder generated with perforation into the pressure fluid is: There is no possibility that it is easily taken into the recess of the head portion and wraps around the outer peripheral surface of the bit head portion, so there is no fear that it will stick to the outer peripheral surface of the bit head portion and increase the rotational resistance. Since the body is thin, there is little resistance to the flow of the mixed fluid in the joint direction, and therefore,
The flow is smooth. Since the outer diameter of the joint portion is larger than that of the body portion, the mixed fluid slows down its flow velocity at this portion, and this and the action of the land portion due to the rotation of the bit itself. The mixed fluid is applied to the pore walls, thereby protecting and stabilizing the pore walls and contributing to preventing collapse of the perforations. The outer diameter of the joint is larger than the outer diameter of the body but smaller than the outer diameter of the bit head, the axial length is also shorter than the bit head, and the outer peripheral surface of the joint is relatively shallow but wide. By forming the process, it is possible to surely avoid an increase in rotation resistance due to coating the mixed fluid on the hole wall. The joint recess allows the excess mixed fluid that could not be applied to the hole wall to be smoothly discharged backward.

[Brief description of drawings]

The drawings show an embodiment of the present invention. FIG. 1 is a partially longitudinal side view, FIG. 2 is a front view, FIG. 3 is a rear view, FIG. 4 is a side view in use, and FIG. It is a side view of a conventionally known bit. a ... bit head, b ... body, c ... joint, 4 ...
Tip, 9 ... Recessed part of joint, 10 ... Land part.

Claims (1)

[Claims] 1. A bit head portion, a body portion and a joint portion,
The bit head is relatively short from the front end surface to the vicinity of the embedded bottom of the chip, and has a relatively deep and wide head recess on the outer periphery. The joint part has a smaller axial length than that of the bit head part, and an outer diameter smaller than that of the bit head part but larger than that of the body part. The bit for soft rock drilling is characterized in that a relatively shallow and wide joint recess and land are alternately formed.