JP3204002B2 - Lock bit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lock bit for drilling a hole for blasting in rock or the like, and more particularly to a lock bit in which a large number of button chips are implanted in a body.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a rock bit 1 for drilling a hole 6 for blasting a rock 5 is provided.
Is used. Some of these lock bits include
As shown in FIG. 7, there is a steel body 2 in which a number of button chips 4 made of cemented carbide are implanted on a head 3 of the body. (See Japanese Patent Publication No. 45-10401) The lock bit 1 configured as described above includes:
The button chip 4 crushes the bedrock 5 by applying an axial striking force and a rotational force around the axis, so that a hole 6 for blasting can be formed.

[0003]

By the way, in the above-mentioned conventional lock bit 1, debris generated when the hole 6 is drilled enters between the inner wall surface 6a of the hole 6 and the body 2, and
Acting as if grinding the body 2, the body 2 is gradually worn. On the other hand, since the button tip 4 made of cemented carbide does not easily wear, the button tip 4 falls off the body 2 as the body 2 gradually wears, and the function of the lock bit 1 gradually decreases. I will. In particular, the plurality of button chips 7 implanted in the outermost portion in the radial direction of the head 3 of the body 2 are most important in finishing the hole 6 to a predetermined inner diameter,
The conventional lock bit 1 has a problem that if some of these button chips 7 fall off, the inner diameter of the hole 6 can no longer be finished to a predetermined size.

Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide some of the plurality of button chips for drilling the inner wall surface of the hole to be drilled. An object of the present invention is to provide a lock bit capable of finishing an inner diameter of a hole to be drilled to a predetermined size even if the lock bit is dropped.

[0005]

An object of the present invention is to provide a lock bit in which a number of button chips are implanted in a body, according to the present invention. A second button tip, which cuts the inner wall surface when the first button tip falls off the body, is inclined to the axial rear side of the button tip with respect to the axis of the body.
This can be achieved by a lock bit characterized in that the lock bit is caused to be implanted in the body .

[0006]

In the lock bit of the present invention, when the first button chip falls off, the second button chip replaces the first button chip and cuts the inner wall surface of the hole to be drilled, so that the body is worn. Thus, even if the first button chip falls off the body, the inner diameter of the hole to be drilled can be finished to a predetermined size.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a lock bit according to the present invention will be described below in detail with reference to the drawings. Here, FIG. 1 is a half sectional side view of a lock bit according to the present invention, FIG. 2 is an enlarged sectional view showing a main part of the lock bit shown in FIG. 1, and FIG. 3 is a state in which a first button chip is dropped. FIG. 4 is an enlarged cross-sectional view of an essential part for explaining the operation of the second button chip. FIG. 4 illustrates the positional relationship in the radial direction between the first button chip and the second button chip of the lock bit according to the second embodiment of the present invention. It is a principal part expanded sectional view.

First Embodiment As shown in FIG. 1, a lock bit 110 according to a first embodiment has a substantially disk-shaped large-diameter head 10A and a substantially cylindrical small-diameter shaft 1.
0B.

An axially front surface 10C of the head 10A
, A number of button chips 11 made of cemented carbide for crushing the rock are implanted. Also, the button chip 11 is provided on the outermost peripheral surface 10D of the head 10A on the outermost side in the radial direction.
A discharge groove 12 for discharging crushed debris is formed at regular intervals in the circumferential direction, and
C has a concave groove 13 extending radially outward from the center of the head 10A and communicating with the groove 12.

The lock bit 1 is attached to the shaft 10B.
A spline 16 to which the rotational force about the axis C is transmitted
Are formed. The shaft 10B and the head 1
0A, a flat surface 10E extending perpendicular to the axis C is formed.
The striking force is applied in the axial direction with respect to 0.

A high-pressure air supply hole 14 extending in the axial direction is formed in the shaft portion 10B, and a through-hole 15 for communicating a tip end of the high-pressure air supply hole 14 with the concave groove 13 is formed in the shaft portion 10B. It penetrates the head 10A. Thereby, the high-pressure air supply hole 1 is connected through a pipe (not shown).
When high-pressure air is supplied into the through-hole 1, the high-pressure air
5, the debris crushed by the button chip 11 is put on the flow of high-pressure air, and discharged through the discharge groove 12 to the axially rear side of the head 10A. You.

Next, the characteristic portion of the lock bit 110 of the present embodiment will be described with reference to FIGS. FIG.
As shown in an enlarged view of the main part, the axial line with respect to the first button chip 21 planted on the outermost side in the radial direction among the many button chips 11 planted on the head 10A. A second button chip 22 is implanted behind C. The distance between the first button chip 21 and the second button chip 22 in the radial direction with respect to the axis C is L. In this embodiment, as shown in FIG. 2, the first button chip 21 and the second button chip 22 each have an inclination angle θ with respect to the axis C in the range of 30 ° to 60 °. As shown in FIG. 1 as a side view, a first button chip 21 and a second button chip 22 are attached to the head 10A.
Is implanted so that the position in the circumferential direction is shifted. Further, the second button chip 22 is embedded so as to fit inside a hole 23 formed in the outer peripheral surface 10D of the head 10A.

As a result, the lock bit 11 of this embodiment is
When a hole is drilled in the rock using 0, the head 10A eventually wears out and the first button chip 21 falls off as shown in FIG.
Is gradually exposed, and the rock is drilled in place of the first button chip 21. At this time, as described above, since the distance between the first button chip 21 and the second button chip 22 with respect to the axis C is both L, the hole 6 drilled by the first button chip 21 The inside diameter is equal to the inside diameter of the hole 6 drilled by the second button tip 22.

That is, the lock bit 110 of the present embodiment
According to this, even if the head 10A gradually wears out and the first button chip 21 falls off, the second button chip 22
Since the inner wall surface 6a of the hole 6 is drilled in place of the button chip 21, the inner diameter of the hole 6 does not change, and the inner diameter of the hole 6 to be drilled can be finished to a predetermined size. Further, until the first button chip 21 comes off, the second button chip 22 reinforces the head 10A, so that the wear of the head 10A is delayed and the first button chip 21 comes off. You can extend the time until.

Second Embodiment The lock bit of the second embodiment is the same as that of the first button chip 21 and the second button chip of the lock bit 110 of the first embodiment.
The radial positional relationship of the button chip 22 is changed. That is, as shown in FIG. 4, in the lock bit 120 of the second embodiment, the second button chip 2
2 is implanted radially inward from the first button chip 21 in a range of 0 to 1.8 mm. Accordingly, even when a hole is formed in a hard rock, not only the wear of the second button chip 22 can be prevented, but also the inside diameter of the hole to be formed can be secured. On the other hand, when the second button chip 22 is implanted radially inward beyond the first button chip 21 by more than 1.8 mm, the inner diameter of the hole to be drilled can be secured. Can not. When the second button chip 22 is implanted radially outward with respect to the first button chip 21, the second button chip 22 is undesirably worn.

The lock bit of the present invention is not limited to the above-described embodiment. For example, the tilt angle θ of the second button chip 22 with respect to the axis of the body 10 is set.
Is different from that of the first button chip, etc.
It goes without saying that various modifications are possible based on the gist of the present invention.

[0017]

That is, the lock bit of the present invention is a lock bit in which a number of button chips are implanted in a body, and the axis of the first button chip for drilling the inner wall surface of the hole to be drilled. A second button chip, which drills the inner wall surface when the first button chip falls off the body , is tilted with respect to the axis of the body, and
When the first button chip falls off, the second button chip replaces the first button chip and cuts the inner wall surface of the hole to be drilled, so that the body is worn. Thus, even if the first button chip falls off the body, the inner diameter of the hole to be drilled can be finished to a predetermined size. This not only eliminates the need to periodically replace the lock bit due to the fear of the first button chip falling off, but also allows the hole with a small inner diameter formed by the falling off of the first button chip to have a predetermined diameter. Since the operation of re-drilling the hole to finish the inner diameter of the hole can be omitted, there is an excellent effect that the operation of drilling the hole in the rock can be efficiently performed.

[Brief description of the drawings]

FIG. 1 is a half sectional side view of a lock bit according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a main part of the lock bit shown in FIG.

FIG. 3 is an enlarged cross-sectional view of a main part for explaining an operation of a second button chip in a state where the first button chip is dropped.

FIG. 4 is an enlarged sectional view of a main part for explaining a radial positional relationship between a first button chip and a second button chip of a lock bit according to a second embodiment of the present invention.

FIG. 5 is a partial cross-sectional side view for explaining the operation of a conventional lock bit.

FIG. 6 is an enlarged side view showing the head of a conventional lock bit.

[Explanation of symbols]

 C Body axis L Radial distance θ Inclination angle of button tip 1 Conventional lock bit 2 Body 3 Head 4 Button tip 5 Rock 6 Hole 10 Body 10A Head 10B Shaft 10C Front face 10D Outer face 10E Flat face 11 Button tip 12 Exhaust groove 13 Concave groove 14 High-pressure air supply hole 15 Through hole 16 Spline 21 First button chip 22 Second button chip 23 Button chip burying hole 110 Lock bit of Example 1 according to the present invention 120 Example according to the present invention 2 lock bits

Continuation of front page (56) References JP-A-50-13201 (JP, A) JP-A-6-167181 (JP, A) JP-A-2-116586 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) E21B 10/36 E21B 10/58

Claims (4)

(57) [Claims] 1. A lock bit having a plurality of button chips implanted in a body, wherein the first button chip which drills an inner wall surface of a hole to be drilled is axially rearward of the body with respect to the first button chip. A second button tip for drilling the inner wall surface when the first button tip falls off the body ;
A lock bit which is implanted in said body so as to be inclined with respect to the axis of the body . 2. The lock bit according to claim 1, wherein the first button chip and the second button chip are implanted in the body with their positions shifted in a circumferential direction. . 3. The lock according to claim 1, wherein a diameter of the second button tip is set in a range of 85% to 105% of a diameter of the first button tip. bit. 4. A radial distance between the axis of the body and the second button tip is 0 to -1.8 mm with respect to a radial distance between the axis and the first button tip. 4. The method according to claim 1, wherein:
Lock bit according to any of the above.