JPH0913860A - Down-the-hall drill - Google Patents

Abstract

PURPOSE: To break and overhaul a spacer for the easy replacement of a bit by connecting a joint between a bit section and a casing, and a joint between the casing and a drill rod joint member via an annular spacer. CONSTITUTION: The high-pressure compressed air is continuously supplied from the ground surface to repeat the reciprocating motion of a hammer 15, and a down-the-hall drill is rotated and advanced on the operation of a boring machine on the ground surface, thereby proceeding with an excavation work. At the time of replacing a bit section for the wear of the leading end of a bit 11 due to the continuity of a long-time excavation process in that way, or due to the abrasion of the end for any other reason, an annular spacer 17a is first fused. Then, the mounting member 12 of the bit 11 is rotated for loosening the screwed engagement thereof with a casing 10, and demounted therefrom. Also, when the bit section including the casing 10 and a percussion device 14 is replaced, an annular spacer 17b is similarly heated and fused. Then, screwed engagement between the easing 10 and a drill rod connecting member 13 is loosened, and the casing 10 including the bit section is demounted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a down-the-hole drill mounted on the tip of a drill rod for ground boring and driven by air pressure for feeding, and more particularly to a down-the-hole drill in which a drill body can be easily disassembled.

[0002]

2. Description of the Related Art A conventional down-the-hole drill is, as shown in FIG.
A casing 2 connected to the casing 2, a connecting member 3 connected to the rear end of the casing 2, and a striking device 4 provided in the casing 2 between the bit portion 1 and the connecting member 3. There is. This down-the-hole drill is connected to the tip of the drill rod 5 via the threaded portion 3a of the connecting member 3, and is drilled with one bit 1a at the tip. That is, air is introduced from the drill rod 5 through the hollow center portion 3b of the connecting member 3, passes through the check valve 6 and drives the hammer 7 back and forth to strike the bit 2, and the air then blows the bit 1a. Connect to the outside of the casing 2 and the inner wall of the excavation hole (chain line) 9 and to the ground through the exhaust holes 8a and 8b provided in the shaft center and out to the tip of the bit 1a, along with the excavated earth and sand or rock granules. It is designed to be discharged to the ground through the gap between the outside of the extended drill rod 5 and the inner wall of the drill hole (not shown). The compressed air that drives this down-the-hole drill is the drill rod 5
It is supplied by an air compressor from an air hose connected to a ground air space (not shown) connected to the upper end of the, and the drill rod 5 is rotated and fed by an excavator installed on the ground. There is.

[0003]

In the down-the-hole drill of this type, since the tip of the bit 1a is gradually worn away by continuing excavation for a long time, or due to the relation with the excavation geology, or other reasons, only the bit part 1 is formed. Or, it becomes necessary to replace the casing 2 and the striking device 4 together. However, in the conventional down-the-hole drill, the connection screw portion between the casing 2 and the mounting member 1b (head sub) of the bit portion 1 and between the casing 2 and the connecting member 3 is excavated for a long time, There is a problem that it is so tight that it cannot be easily disassembled and removed, and therefore it is extremely difficult to replace the bit at the work site. The present invention was devised in view of the above circumstances, and it is possible to easily remove only the bit portion 1 or the casing 2 and the striking device 4, and therefore it is possible to easily perform the replacement work or the like. To provide down-the-hole drills that can.

[0004]

In order to achieve the above object, in the present invention, a bit portion, a casing having a tip portion connected to the bit portion, and a drill rod connected to a rear end portion of the casing are provided. A down-the-hole drill comprising a connecting member and a striking device provided in a casing between the bit portion and a drill rod connecting member, the connecting portion between the bit portion and the casing, and the casing and the drill. A technical measure is taken to connect at least one of the connecting portions with the rod connecting member via an annular spacer.

[0005]

[Operation] When disassembling the bit or drill rod of the down the hole drill for exchanging the bit, etc., the torsional stress or strain applied to the screw of the connecting portion is caused by fusing or breaking the annular spacer by mechanical means. Removed and thus these connections can be easily separated.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the down-the-hole drill of the present invention will be described below with reference to the drawings. 1 is a sectional view showing the down-the-hole drill in a state where the hammer of the striking device is in contact with the bit, and FIG. 2 is a sectional view showing the down-the-hole drill in a state where the hammer of the striking device is retracted from the bit.

In the figure, 10 is a casing made of a cylindrical body, and a bit 11 is screwed to the tip of the casing via a mounting member (head sub) 12. It should be noted that the exhaust hole 11a penetrates through the axial center of the bit 11 substantially along the axial direction,
It communicates with the exhaust hole 11b which is open at the tip end away from the axis. Further, the rear end of the casing 10 has a hollow center 13
It is screwed with the tip of the drill rod connecting member 13 having a. The base end of the drill rod connecting member 13 is connected to the drill rod 18.

Further, a striking device 14 is arranged at the axial center of the casing 10 between the bit 11 and the drill rod connecting member 13. The striking device 14 includes a hammer 15 and a check valve mechanism 16. The hammer 15 reciprocally slides along the axial direction of the casing 10 as will be described later, and the bit 11
Is hit intermittently.

The rear end portion of the mounting member (head sub) 12 is a step portion which is lowered by one step, and this portion is the screw portion 1
2a, and the casing 10 is attached to the screw portion 12a.
End portion (having the same thickness as the step portion of the mounting member 12)
The screw portion 10a formed on the inner surface of the is screwed. Here, the stepped wall surface of the mounting member 12 and the casing 1
An annular spacer 17a is provided between the end of the annular spacer 17 and the end of the casing 0 so as to be flush with the outer peripheral surfaces of the mounting member 12 and the casing 10.
The bit portion and the casing 10 are fastened with the interposing 7.

Similarly, the tip of the drill rod connecting member 13 is also a screw portion 13b formed to be further lowered, and the screw portion 10b formed on the inner surface of the rear end portion of the casing 10 is screwed into the screw portion 13b. Further, an annular spacer 17b is interposed between the abutment wall surface of the drill rod connecting member 13 and the rear end of the casing 10 so as to be flush with the outer peripheral surfaces of the drill rod connecting member 13 and the casing 10. And the annular spacer 17b
The drill rod connecting member 13 and the casing 10 are tightened with the intervening.

Here, the annular spacers 17a and 17b are
A metal material that has sufficient mechanical strength to withstand the environment of use and that can be broken by heat such as a burner or other physical means without damaging the body of the down the hole drill is used. If it is a synthetic resin material, it may be used.

Next, the operation of the down-the-hole drill having this structure will be described. The operation itself of the down the hole drill is not particularly different from that of the conventional one, and first, air is introduced from a drill rod (not shown) through the hollow center portion 13a of the connecting member 13, passes through the check valve mechanism 16, and at that time. The hammer 15 is driven to the left in the drawing by the compressed air to strike the bit 11 (FIG. 1), and the tip of the bit 11 applies an impact force to the excavation surface.

Then, the air is sent between the rear end surface of the bit 11 and the front end surface of the hammer 15 through the inner surface of the casing 10 to retract the hammer 15 rearward in the drawing, and further the shaft of the bit 11. Exhaust hole 11 in the heart
Out of the casing 10 and the inner wall 19 of the excavation hole (chain line) and the outer side of the drill rod connected to this and extending to the ground through the a and 11b to the tip of the bit 11 along with the excavated earth and sand or rock granules. It is designed to be discharged to the ground through a gap between the inner wall of an excavation hole (not shown). When the hammer 15 retracts as shown in FIG. 2, air is introduced through the inner surface of the casing 10 between the rear end surface of the hammer 15 and the front end surface of the check valve mechanism 16, and as shown in FIG. To move forward.

The compressed air for driving the down-the-hole drill is supplied by an air compressor from an air hose connected to the upper end of the drill rod, and the drill rod is rotated and fed by an excavator installed on the ground. ing. In this way, by continuing the supply of highly compressed air from the surface of the earth, the hammer 15 repeats the reciprocating motion as described above, and the down-the-hole drill is rotated and fed or excavated by the boring machine on the surface of the earth to complete the excavation work. Can be advanced.

When the tip of the bit 11 is gradually worn away by continuing excavation for a long time in this way, or when the bit portion is replaced for other reasons, first, the annular spacer 17a is melted by a burner, or otherwise. It is broken by the physical means of. Then, the mounting member (head sub) 12 of the bit 11 is rotated to rotate the casing 1
It can be removed from the casing 10 by loosening the screwing with 0.

When the bit part including the casing 10 and the striking device 14 is replaced, the annular spacer 17b is also heated and melted, or broken by other physical means. Then, the casing 10 is rotated to loosen the screw engagement with the drill rod connecting member 13, and the casing 10 including the bit portion is moved to the drill rod connecting member 13.
Can be removed from.

FIG. 3 shows a case where the present invention is applied to a down-the-hole drill having a larger diameter. Also in this case, by disposing the annular spacer, the disassembly can be facilitated similarly to the above-mentioned embodiment.

The same components as those in the above embodiment are designated by the same reference numerals and the description thereof will be omitted. In the above embodiment, the driving air is discharged from the tip of the bit through the internal through passage of the down the hole drill, and is discharged to the ground along with the earth and sand particles excavated from the gap between the outer periphery of the down the hole drill and the inner wall of the drill hole. Although the present invention is not limited to this, the present invention is naturally not limited to this, and the inside of the down-the-hole drill is connected to the double-pipe drill rod and the driving air is excavated together with the particles of the earth and sand or rock mass. It can be applied to all types and types of down-the-hole drills such as those that are discharged to the ground via the road.

[0019]

As described above, according to the present invention, when disassembling the down-the-hole drill for exchanging the bit, the annular spacer is broken by mechanical means such as fusing, so that the twist of the screw at the connecting portion is twisted. The stresses or strains are relieved so that these connections can be easily separated even at the work site, thus allowing easy and quick bit replacement.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a down-the-hole drill of an embodiment of the present invention.

FIG. 2 is a cross-sectional view explaining the operation of the down the hole drill.

FIG. 3 is a cross-sectional view showing an example of a down-the-hole drill having different shapes.

FIG. 4 is a sectional view showing an example of a conventional down the hole drill.

[Description of sign]

 DESCRIPTION OF SYMBOLS 1 ... Bit 2 ... Casing 3 ... Connection member 4 ... Hitting device 5 ... Drill rod 6 ... Check valve 7 ... Hammer 10 ... Casing 11 ... Bit 11a ... Exhaust hole 12 ... Attachment member (head sub) 13 ... Drill rod connection member 14 ... Impact device 15 ... Hammer 16 ... Check valve mechanism 17a, 17b ... Annular spacer

Claims (2)

[Claims] 1. A bit portion, a casing having a tip end portion connected to the bit portion, a drill rod connecting member connected to a rear end portion of the casing, and a portion between the bit portion and the drill rod connecting member. In a down-the-hole drill including a striking device provided in a casing, at least one of a connecting portion between the bit portion and the casing and a connecting portion between the casing and the drill rod connecting member is annular. Down the hole drill characterized by having a spacer interposed. 2. A connecting portion between the bit portion and the casing,
The down-the-hole drill according to claim 1, wherein an annular spacer is interposed between the casing and the connecting portion between the casing and the drill rod connecting member.