JP2001032661A - Drilling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To pull out a drilling bit, keeping the wall surface of a drilled hole as much as possible from crumbling when the drilling bit is in a jamming state in a drilling device for drilling a rock-bed or the like with the drilling bit mounted through a rod to the tip of a shank rod accommodated in a drifter, by striking the shank rod forward while rotating it. SOLUTION: A reverse striking piston 8 is mounted in a longitudinally slidabld manner on the front side of a collar part 3a on a shank rod 3. Advance side and retreat side working chambers 24, 25 are provided for advancing or retreating the reverse striking piston 8. Only the retreat side working chamber 25 is put in a high pressure state by a hydraulic supply circuit C, and the shank rod 3 is retreated by the reverse striking piston 8 into a position where it can be struck by a normal striking piston 9. The retreat side working chamber 25 is alternately changed into the high pressure state and low pressure state to directly apply backward impact to the shank rod 3 by the reverse driving piston 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rock drilling machine used in the fields of civil engineering, crushed stone, etc.
The present invention relates to a drilling device such as a tap hole opening machine of a refuse treatment facility, and particularly to a technical field of a so-called jamming countermeasure when a drill bit is stuck in a drilling hole and cannot be removed.

[0002]

2. Description of the Related Art Conventionally, a drilling device of this type generally has a shank rod having a drill bit attached to a tip end thereof, extending in the drilling direction, and a rear end of a punching piston (mainly). The piston is hit forward by a piston to drill rock or the like.

Further, as disclosed in Japanese Patent Publication No. 8-9943, for example, a cylindrical sub-piston is slidably mounted on the shank rod, and the sub-piston partitions a buffer chamber on the front side in a casing. There is something. In this device, when the drill bit is clogged in the drilling hole and cannot be removed, first, the buffer chamber is filled with pressure oil to retract the sub piston, and the sub piston moves the shank rod to a normal striking position. After retreating, the rear end is hit with a regular piston. This allows
An impact force in both the front and rear directions can be applied to the drill bit clogged in the drill hole, and jamming is eliminated by repeatedly performing this.

Further, for example, Japanese Patent Publication No. 2613538 proposes that a rock drilling machine be provided with a reverse piston in addition to a normal regular piston. In this device, a cylindrical reverse striking piston is attached to a shank rod in the same manner as in the conventional example (Japanese Patent Publication No. 8-9943).
A dedicated hydraulic cylinder is provided to advance or retreat the reverse striking piston along the shank rod, and when jamming occurs, the reverse striking piston directly applies a rearward blow to the shank rod to form a drill bit. By applying a sufficiently large rearward impact force to the hole, it can be reliably pulled out of the borehole.

[0005]

By the way, in the case of blasting tunnels, for example, soft portions and viscous layers are present intricately and intricately on the face of the cutting face to be drilled. However, the biting state of the drill bit at that time varies. For example, in the case where the drill bit is bitten tightly in extremely hard rocky material, the rearward impact force cannot be increased so much by using the former conventional example (Japanese Patent Publication No. 8-9943). ,
It is inevitable that a great deal of time and effort will be expended in extracting the drill bit, and moreover, the drill bit may not eventually be pulled out.

On the other hand, for example, when the latter conventional example (Patent No. 2613538) is used in a place where the rock is relatively soft, when the drill bit is pulled out, the rearward impact force is too large and the inner wall of the drill hole is too large. May collapse significantly. In such a case, the blasting of the excavation hole cannot achieve the calculated effect, and the efficiency of the construction is greatly reduced. In addition, for example, in a taphole drilling machine of an ironworks, if the inner wall of the taphole collapses when the drilling bit is pulled out as described above, the amount of pig iron to be taken out of the hole will be out of order, resulting in an extremely large defect. Occurs.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to pay attention to the fact that the biting state of a drill bit in a jamming state is not uniform.
In response to this, it is desirable to ensure that the drill bit is pulled out while keeping the wall surface of the drill hole as small as possible.

[0008]

In order to achieve the above object, according to the present invention, there is provided a drilling apparatus, wherein a sub piston is mounted on a shank rod of a drilling device, and the shank rod is retracted to a predetermined position. It is possible to switch between hitting with the piston and directly hitting the shank rod backward with the auxiliary piston.

More specifically, according to the first aspect of the present invention, the shank rod is held at a predetermined striking position in the casing, and a main piston operated by fluid pressure is disposed behind the shank rod. It is premised on a drilling device in which a rear end portion of a rod is hit forward and drilling is performed by the hitting force. Then, a flange portion is formed on the shank rod, and a cylindrical sub-piston engageable with the flange portion is slidably mounted on the shank rod on the front side of the flange portion. In the casing, a forward working chamber for applying a forward fluid pressure to the auxiliary piston and a retreating working chamber for applying a backward fluid pressure to the sub-piston are provided, respectively. A first adjusting operation for adjusting the fluid pressure of both working chambers so that the fluid pressure acts on the sub-piston backward, and a fluid pressure of both working chambers such that the sub-piston reciprocates back and forth. A configuration is provided that includes a fluid pressure adjustment circuit that can be switched to a second adjustment operation for changing and adjusting.

With the above configuration, when jamming occurs, first, the fluid pressure adjusting circuit is switched to the first adjusting operation to apply a backward fluid pressure to the auxiliary piston. As a result, the sub-piston retreats and presses the shank rod to the rear side via the flange portion, and retreats the shank rod to a position where it can be hit by the main piston. And
If the rear end of the shank rod is struck forward by the main piston at this position, an impact force can be applied to the drill bit attached to the tip of the shank rod. If the condition is not too strong, the drill bit can be pulled out without breaking the wall surface of the drill hole, and jamming can be eliminated.

On the other hand, if the biting of the drill bit is tight, jamming cannot be eliminated even if the above operation is repeated. At this time, the fluid pressure adjusting circuit is switched to the second adjusting operation to reciprocate the sub-piston back and forth, and the sub-piston collides against the flange of the shank rod to directly apply a rearward impact. As a result, a sufficiently large rearward impact force acts on the drill bit, so that the drill bit can be reliably pulled out of the borehole. In other words, the impact force acting on the drill bit can be switched very easily according to the biting condition.
When the wall surface of the drill hole is soft, the drill bit can be pulled out while the wall surface is not broken as much as possible, and when the wall surface of the drill hole is hard, the drill bit can be reliably pulled out with a strong impact force.

According to the second aspect of the present invention, the fluid pressure adjusting circuit comprises:
During the first adjustment operation, only the fluid pressure in the retreat-side working chamber is increased, while in the second adjustment operation, the fluid pressure in the retreat-side working chamber is increased, and the fluid pressure in the forward-side working chamber is alternately increased or decreased. Configuration.

As a result, only the fluid pressure in the retreating-side working chamber is increased by the first adjusting operation, and the fluid pressure acts on the sub-piston in a backward direction, so that the shank rod is moved rearward by the sub-piston. be able to. On the other hand, in the second adjusting operation, the fluid pressure of the forward working chamber is alternately increased or decreased while the fluid pressure of the backward working chamber is increased, so that the auxiliary piston increases the forward working chamber. It can move forward and away from the flange at the time of pressurization, and retreat at the next pressure reduction and collide with the flange, and can directly strike the shank rod backward.

According to a third aspect of the present invention, the fluid pressure adjusting circuit according to the second aspect is provided with an electromagnetic switching valve for switching the forward working chamber to a supply or discharge side of the working fluid. In this case, the fluid pressure in the forward working chamber can be easily switched to increased or reduced pressure by the electromagnetic switching valve. Also,
For example, if the electromagnetic switching valve is duty-controlled to linearly change the fluid pressure of the forward working chamber, the rearward impact force applied to the shank rod can be finely adjusted. The operation and effect of the first invention can be further enhanced.

According to a fourth aspect of the present invention, the fluid pressure adjusting circuit according to the second aspect includes a switching valve for switching the forward working chamber to a supply side or a discharge side of the working fluid, wherein the switching valve is a pilot valve from an electromagnetic valve. It shall be of a fluid pressure pilot type that operates under pressure. With this configuration, the same effect as that of the third aspect of the invention can be obtained, and the solenoid valve can be disposed away from the main body of the drilling device, so that the reliability is improved.

According to the fifth aspect of the present invention, a stopper is provided in the casing for engaging with the auxiliary piston to prevent retreat, and this stopper is provided when the shank rod is at a predetermined position in front of the striking position. It is arranged to be engaged with the auxiliary piston.

Thus, when the fluid pressure adjusting circuit is switched to the first adjusting operation and the shank rod is retracted by the auxiliary piston, when the shank rod reaches a predetermined position ahead of the striking position, the auxiliary piston and the stopper are stopped. The part engages and no longer retracts, and the shank rod is positioned forward of the normal striking position. When the rear end of the shank rod is struck forward by the main piston in this state, the striking force is weaker than the striking force at the time of normal drilling. By making it smaller than at the time, it is possible to reliably prevent the wall from collapsing.

[0018]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show the structure of a drilling apparatus A according to an embodiment of the present invention. The drilling apparatus A is applied to, for example, a tap opening machine of a refuse melting furnace in a refuse treatment facility. Things. As shown in FIG. 2, the drilling device A includes a guide cell 1 supported by a bogie or the like so as to extend in the drilling direction, and a drifter 2 that advances or retreats along the guide cell 1. A rod 5 is attached to the tip of a shank rod 3 (see FIG. 1) of the drifter 2 by a sleeve 4, and a drill bit 6 is attached to the tip of the rod 5. Then, the drill 5 is moved forward by a chain (not shown) while applying a striking force to the rod 5 and the drill bit 6 by the drill 2 and rotating the drill 5 to form a drilling hole.

(Structure of Drifter) As shown in FIG. 1, the drifter 2 has a casing 7 formed by combining a plurality of cylindrical bodies. The shank rod 3 is accommodated in a front portion of the casing 7. , The shank rod 3
A cylindrical back-hitting piston 8 (sub-piston) is mounted on the upper side so as to be slidable back and forth, while a forward-hitting piston 9 (main piston) is disposed substantially coaxially behind the shank rod 3. ing. The front end of the casing 7 is formed by a front cap member 10 that tapers forward.
The four cylindrical bodies 11, 12, 13, and 14 are joined in order, and the rear end is closed by an end cap 15.

The shank rod 3 is supported at its front end by a front cap member 10 while its rear end extends halfway through a third cylindrical body 13, and is extended in the front-rear direction by a cylindrical transmission member 16. While being slidably supported, the rotational force of a hydraulic motor 17 disposed outside the third cylindrical body 13 is transmitted via the transmission member 16. That is, the transmission member 16 is a pair of front and rear tapered roller bearings 1.
8 and 19, and the rear end of the shank rod 3 is inserted halfway so that the spline 2
0 to rotate integrally with the shank rod 3. A driven gear 21 that receives rotation input from the hydraulic motor 17 is formed on the outer periphery of the transmission member 16.

Further, a flange 3a is provided at a portion of the shank rod 3 on the front side of the spline 20 to regulate the forward and backward movement of the shank rod 3. That is, the shank rod 3 has the rear surface of the flange 3a
By contacting the front end of the piston 6, further retreat is restricted, and this position corresponds to a striking position where the striking piston 9 strikes during normal drilling. On the other hand, when the front surface of the flange portion 3a contacts the rear surface of the intermediate member 26 described later, further advance of the shank rod 3 is restricted.

The reverse striking piston 8 is provided on the shank rod 3.
It is slidably mounted on the top, and is housed movably back and forth in a cylinder composed of the first tubular body 11 and a sleeve 23 at the front end thereof. A large diameter portion 8a is provided at the center in the front-rear direction of the reverse striking piston 8, and a plurality of circumferential shallow grooves having an oil sump function are formed on the outer peripheral surface thereof. On the other hand, on the inner peripheral surface of the first cylindrical body 11 that accommodates the reverse strike piston 8, the reverse strike piston 8 is provided.
An annular groove is formed over the entire circumference in two places on the front side and the rear side with respect to the large-diameter portion 8a of the large-diameter portion 8a. Annular forward and backward working chambers 24 and 25 for applying forward or backward hydraulic pressure are formed.

Here, the outer diameter of the reverse striking piston 8 is slightly larger on the front side with respect to the large diameter portion 8a than on the rear side. Since the pressure receiving area of the facing reverse piston 8 is larger than the pressure receiving area of the retreating side working chamber 25, if the hydraulic pressures of the two working chambers 24 and 25 are the same, the reverse hitting piston 8 moves forward. Also,
An annular intermediate member 26 having a stopper protruding inwardly is fitted between the first cylindrical body 11 and the second cylindrical body 12, and the reverse striking piston 8 is connected to the stopper part. By contacting (engaging) with the, further retreat is prevented.

The positive hitting piston 9 is accommodated in a cylinder liner 27 fitted on the inner peripheral side of the fourth cylindrical body 14 so as to be movable back and forth. In the vicinity of the center in the front-rear direction of the regular hitting piston 8, two large-diameter portions 9a, 9 are sequentially arranged from the front side.
b are provided at an interval from each other, and a portion behind the large-diameter portion 9b on the rear side is a small-diameter portion 9c. A plurality of circumferential shallow grooves each having an oil reservoir function are formed on the outer peripheral surfaces of the two large-diameter portions 9a and 9b. On the other hand, the cylinder liner 27
A plurality of annular grooves are formed on the inner peripheral surface of the piston so as to surround the outer periphery of the hitting piston 9, and the hydraulic working chambers 28, 29, 30, 31 are formed between the grooves and the outer peripheral surface of the hitting piston 9. Is partitioned.

A cylindrical switching valve 32 for switching the operation of the front-hitting piston 9 between forward and backward is disposed on the outer peripheral surface on the rear side of the front-hitting piston 9. Similarly, a plurality of annular grooves are formed on the inner peripheral surface of the cylinder liner 27 surrounding the outer periphery of the valve body of the valve 32, and between the groove and the valve retreat, hydraulic working chambers 33, 34, 35 (FIG. 3
See section). Further, on the inner peripheral side of the valve body of the switching valve 32, a working chamber 36 for applying a forward hydraulic pressure to the right-handing piston 9 is defined between the valve body and the small-diameter portion 9c of the right-handing piston 9.

The forward hitting piston 9 and the reverse hitting piston 8
Operates upon receiving a supply of hydraulic oil from a hydraulic pressure supply circuit C (fluid pressure adjustment circuit) shown in FIG. This hydraulic supply circuit C
Is provided with a hydraulic pump 40 driven by an engine or the like (not shown).
An electromagnetic first switching valve 41 that supplies or shuts off the operating oil pressure to or from the right-hitting piston 9 and a second electromagnetic switching valve 42 that similarly feeds or shuts off the hydraulic pressure to the reverse-stroke piston 8 are connected in parallel. It is arranged. The high pressure line 43 on the downstream side of the first switching valve 41 is branched into three,
It communicates with the working chambers 28, 29, 34 via an oil passage in the cylindrical body 14 and the cylinder liner 27. The high-pressure line 43 is connected to an accumulator 44 for absorbing fluctuations in hydraulic pressure. On the other hand, the working chambers 31 and 35 in the cylinder liner 27 communicate with the low-pressure line 45 through the same oil passages, and communicate with the oil tank 47 through the check valve 46 through the low-pressure line 45. An accumulator 48 is also connected to the low-pressure line 45.

On the other hand, the downstream side of the second switching valve 42 is branched into two supply / discharge passages 51, 52.
Numerals 2 communicate with the forward-side and reverse-side working chambers 24 and 25 of the reverse stroke piston 8 via oil passages in the first cylindrical body 11, respectively. 1
A third switching valve 53 is provided in the supply / discharge passage 51. The third switching valve 53 is a hydraulic pilot type that operates by receiving a pilot pressure supplied from an electromagnetic valve 54.
In the initial state, it is positioned at the discharge position (the left position shown in FIG. 1) by the urging force of the spring, and connects the forward working chamber 24 to the low pressure line 55 on the hydraulic oil discharge side while the solenoid valve 54 is in the on state. When the operating hydraulic pressure of the second supply / discharge passage 52 is transmitted and switched to the supply position (the right side position in the figure), the operating hydraulic pressure is supplied to the forward working chamber 24.

Reference numeral 57 in FIG. 1 denotes a check valve. Further, a relief valve 58 is provided on the discharge side of the hydraulic pump 40 so as to maintain the operating oil pressure on the discharge side at a predetermined pressure or less. The hydraulic pump 40, the second switching valve 42, the supply / discharge passages 51 and 52,
The third switching valve 53, the solenoid valve 54, the low pressure line 55, and the like correspond to a fluid pressure adjusting circuit.

(Operation of Drifter) Next, the drifter 2
Will be described in detail.

First, the case where a normal drilling operation is performed by hitting the shank rod with the forward-acting piston 9 will be described with reference to FIGS. In this case, the second
While the switching valve 42 is in the off state (the state shown in FIG. 1), a signal is input to the solenoid of the first switching valve 41,
Is switched to the ON state as shown in FIG. As a result, the high-pressure hydraulic oil discharged from the hydraulic pump 40 is supplied to the high-pressure line 43.
Are supplied to the working chambers 28, 29, and 34, respectively. The working chambers are brought into a high pressure state, and the working chambers 3
The working oil that has flowed through 4 flows into the working chamber 36 through a through passage 32a that penetrates the valve body of the switching valve 32, so that the working chamber 36 is also in a high pressure state.

On the other hand, the working chambers 31 and 35 communicating with the low-pressure line 45 are each maintained at a low pressure, and the working chamber 30 communicating with the low-pressure working chamber 31 is also at a low pressure. In this state, the working chamber 33 that is in communication with the working chamber 30 via the communication path 38 is also in a low pressure state. Then, the action chambers 28 and 29 in the high pressure state are
, A forward hydraulic pressure acts on the positive-stroke piston 9 from the working chamber 36, and a forward hydraulic pressure acts on the positive-stroke piston 9 from the working chamber 36 in the high-pressure state. Since the area is larger than the pressure receiving area facing the working chambers 28 and 29, the hit piston 9 moves forward as indicated by the arrow in FIG.

As shown in FIG. 4, the front end of the forward striking piston 9 which has been advanced by the hydraulic pressure strikes the rear end of the shank rod 3 at the striking position. It is transmitted to the drill bit 6 via the rod 5 and excavation is performed. In this state, the working chamber 30 is cut off from the high-pressure working chamber 29 and communicates with the low-pressure working chamber 31 on the opposite side. Therefore, the working chamber 33 connected to the working chamber 30 is also in the low-pressure state. Is switched to Here, a step portion is provided on the outer peripheral surface of the switching valve 32 over the entire periphery thereof so as to face the working chambers 33 and 34, respectively, and a step of the step portion facing the working chamber 33 acts. Since the working chamber 33 is switched to the high pressure state as described above and becomes the same high pressure state as the working chamber 34 as described above, the oil pressure acts on the valve body of the switching valve 32 backward. Become like

As a result, the valve body of the switching valve 32 moves rearward as shown in FIG.
By 2a, the low-pressure operation chamber 35 communicates with the operation chamber 36, and the operation chamber 36 is switched to the low-pressure state. Accordingly, the forward stroke piston 9 receives backward hydraulic pressure from the high-pressure working chambers 28 and 29, moves backward as shown by the arrow in the figure, and retreats to the initial position shown in FIG. When this happens, the working chamber 30 is again shut off from the high-pressure working chamber 29 and communicates with the low-pressure working chamber 31, so that the working chamber 33 is switched to the low-pressure state and the valve body of the switching valve 32 moves forward. Then, returning to the state shown in FIG. 3, the normal stroke piston 9 moves forward again. As described above, the reciprocating operation of the hitting piston 9 and the switching valve 32 is repeated, so that the hitting piston 9 can apply a regular impact to the rear end portion of the shank rod 3, and thus the shank rod 3 can be hit. A drilling hole having a required depth can be formed by advancing the drifter 2 while applying an impact to the hole 3. And
While the drifter 2 is stopped, the first switching valve 41 is switched to the off state to stop the operation of the hitting piston 9, and then the drill bit 2 is withdrawn and the drill bit 6 is extracted from the drilling hole. At this time, the drill bit and the drill bit 6 in the drill hole may bite and become clogged, and a so-called jamming state may occur in which the drill bit 6 cannot be extracted. In this embodiment, in the case of such a jamming state, the drill bit 6 is first pulled out while applying a relatively weak impact to the drill bit 6, and a strong impact force is given only when the drill bit 6 is still not pulled out. Bit 6 is reliably pulled out.

First, a method of pulling out the drill bit 6 while applying a relatively weak impact to the drill bit 6 will be specifically described. In this case, first, the drifter 2 is retracted on the guide cell 1 and the hydraulic pressure of the working chambers 25 and 24 before and after the reverse strike piston 8 is adjusted to retract the reverse strike piston 8, thereby setting the shank. The rod 3 is retracted so as to be positioned slightly forward from the normal striking position (first adjusting operation of the hydraulic adjusting circuit).

That is, as shown in FIG. 6, a signal is input to the second switching valve 42 to switch the second switching valve 42 to the ON state while the solenoid valve 5
No signal is input to 4, and the third switching valve 53 is kept at the discharge position. As a result, the high-pressure hydraulic oil discharged from the hydraulic pump 40 flows through the second supply / discharge passage 52 and is supplied to the retreating-side working chamber 25, and the retreating-side working chamber 25 is in a high-pressure state, while the forward-side working chamber 25 is in a high pressure state. Since the chamber 24 is maintained in a low pressure state, the hydraulic pressure acts on the reverse striking piston 8 in a backward direction, and the reverse striking piston 8 is connected to the flange of the shank rod 3 as shown by an arrow in FIG. 3a is pressed backward to retreat. Since the drill bit 6 is actually bitten into the borehole and the shank rod 3 hardly retreats, the entire drifter 2 is moved forward by an amount corresponding to the retraction of the shank rod 3 with respect to the casing 7. Will move.

As shown in FIG. 7, when the reverse stroke piston 8 comes into contact with the stopper of the intermediate member 26 and stops,
The rear surface of the shank rod 3 has a transmission member 16
Is held at a position away from the front end, that is, at a position slightly forward of the normal hitting position (see FIG. 1). In this state,
By hitting the shank rod 3 with the right-stroke piston 9 in the same manner as in the case of the normal drilling described above, a relatively weak impact force can be applied to the drill bit 6 bitten in the drilling hole. If the biting condition is not too tight, the drill bit 6 can be pulled out without breaking the wall surface of the drill hole. In other words, shank rod 3
Is located forward of the normal striking position, the striking force on the shank rod 3 is appropriately weakened, and the wall surface of the excavation hole can be reliably prevented from collapsing.

On the other hand, when the drill bit 6 is bitten into the borehole and cannot be extracted by the above-described method, the reverse stroke piston 8 moves forward and backward so as to reciprocate back and forth. (The second adjusting operation of the hydraulic pressure adjusting circuit) so that the reverse striking piston 8 collides with the flange 3a of the shank rod 3 to directly apply a rearward impact. I do. That is, first, in the state shown in FIG.
Is advanced until the flange 3a of the shank rod 3 comes into contact with the intermediate member 26 (actually, the drifter 2 retreats on the guide cell 1).

In this state, as shown in FIG. 8, a signal is input to the second switching valve 42 to switch to the ON state, and a signal is also input to the solenoid valve 54 to switch to the ON state. Switch to the hydraulic oil supply position (right side position in the figure). As a result, the high-pressure hydraulic oil is supplied to the forward-side and backward-side working chambers 24, 25, and both working chambers 24, 25 are similarly brought into a high-pressure state, and the reverse stroke piston 8 moves forward as shown by the arrow in FIG. Then, it separates from the flange 3a of the shank rod 3. Subsequently, in this state, as shown in FIG.
Is switched to the off state, and the third switching valve 53 is switched to the hydraulic oil discharge position (the left position in the figure).
4 is communicated with the low-pressure line 55, the reverse stroke piston 8 quickly retreats as shown by the arrow in the same figure, and its rear end collides with the flange 3a of the shank rod 3 and directly faces backward. Can be hit.

That is, the retreating side working chamber 2 of the reverse stroke piston 8
By alternately increasing or decreasing the hydraulic pressure of the forward working chamber 24 while maintaining the high pressure state of 5, the reverse stroke piston 8 is reciprocated to directly strike the shank rod 3 backward. By applying a sufficient rearward impact force to the drill bit 6, the drill bit 6 can be reliably pulled out even if the bite is tight.

Therefore, the drilling machine A of this embodiment
According to the above, as described above, the impact force acting on the drill bit 6 can be very easily switched between two levels, so that when the wall surface of the excavation hole is soft, the impact force is relatively small so as to minimize the collapse of the wall surface. While the drill bit 6 can be pulled out, while the drill bit 6 can be reliably pulled out even when the wall of the drill hole is tight and the drill bit 6 is biting tightly. it can.

In particular, when the shank rod 6 is retracted by the reverse striking piston 8 and a relatively weak impact is applied by the normal striking piston 9, the shank rod 6 is positioned forward of the normal striking position. In addition, the striking force of the front hitting piston 9 is reduced, and the collapse of the wall surface can be reliably prevented.

Also, the third switching valve 53 connected to the forward working chamber 24 of the reverse stroke piston 8 is of a hydraulic pilot type, and is switched by a pilot pressure guided from an electromagnetic valve 54 provided separately. Forward working chamber 24
Can be switched to an increased or reduced pressure state with one touch. In addition, the third switching valve 5 is used to improve responsiveness.
3 is arranged close to the forward working chamber 24 while the solenoid valve 54
Can be arranged apart from the drifter 2 main body, so that the reliability is improved.

In the above embodiment, the third switching valve 5
Instead of being of the hydraulic pilot type, 3 may be of an electromagnetic type. Also, by controlling the electromagnetic third switching valve 53 in this case or the electromagnetic valve 54 in the above-described embodiment, the hydraulic pressure of the forward working chamber 24 can be changed linearly. 8, the rearward impact force applied to the shank rod 6 can be finely adjusted, so that the operation and effect of the present invention can be further enhanced.

[0045]

As described above, according to the drilling device of the first aspect of the present invention, the shank rod is retracted by the first adjusting operation of the fluid pressure adjusting circuit, and the shank rod is hit forward by the main piston. If the bit of the drill bit is not tight, the drill bit can be pulled out without breaking the wall surface of the drilling hole, while if the bit of the drill bit is tight, the fluid pressure adjusting circuit is set to the second position.
By switching to the adjustment operation, the rear piston can directly apply a rearward impact to the shank rod, thereby applying a sufficiently large rearward impact force to the drill bit and ensuring that the drill bit can be moved from inside the drill hole. Can be pulled out.
That is, since the impact force applied to the drill bit can be switched very easily according to the biting condition, the drill bit can be reliably pulled out while the wall surface of the drill hole is not broken as much as possible.

According to the second aspect of the present invention, the auxiliary piston can be moved backward by the first adjusting operation of the hydraulic adjusting circuit to move the shank rod to the rear side, while the auxiliary piston can be alternately operated by the second adjusting operation. It can be advanced or retracted to apply a direct rearward impact to the shank rod.

According to the third aspect of the present invention, the fluid pressure in the forward working chamber can be easily switched between increasing and decreasing by the electromagnetic switching valve. Further, the fluid pressure can be changed linearly.

According to the fourth aspect of the invention, the same effects as those of the third aspect of the invention are obtained, and the reliability is improved.

According to the fifth aspect of the present invention, by positioning the shank rod forward of the normal striking position, the forward striking force of the main piston can be reduced, and the wall surface of the borehole can be reliably prevented from collapsing.

[Brief description of the drawings]

FIG. 1 is a sectional view of a drifter according to an embodiment of the present invention.

FIG. 2 is a diagram showing an overall configuration of a drilling device.

FIG. 3 is an explanatory diagram of a forward movement of a forward hit piston.

FIG. 4 is an explanatory diagram of a striking operation of a forward striking piston.

FIG. 5 is an explanatory diagram of a retreating operation of a front-hitting piston.

FIG. 6 is an explanatory diagram of an operation of retracting a shank rod by a reverse striking piston.

FIG. 7 is an explanatory diagram showing a state in which a reverse striking piston has contacted a stopper portion.

FIG. 8 is an explanatory diagram of an operation of separating a reverse striking piston from a shank rod.

FIG. 9 is an explanatory diagram of an operation of causing a reverse striking piston to collide with a shank rod.

[Explanation of symbols]

 Reference Signs List A Drilling device C Hydraulic supply circuit (fluid pressure adjusting circuit) 2 Drifter 3 Shank rod 3a Collar 7 Casing 8 Reverse piston (sub piston) 9 Regular piston (main piston) 24 Forward working chamber 25 Retreat working chamber 26 Intermediate member (stopper part) 53 Third switching valve (fluid pressure pilot switching valve)

Claims (5)

[Claims] 1. A shank rod is held at a predetermined striking position in a casing, and a main piston operated by fluid pressure is disposed behind the shank rod. The main piston strikes a rear end of the shank rod forward. In the drilling device configured to perform the drilling by the impact force, a flange portion is formed on the shank rod, and a cylinder engageable with the flange portion is provided on the shank rod in front of the flange portion. A sub-piston is mounted so as to be slidable back and forth, and a forward-side working chamber for applying a forward fluid pressure to the sub-piston and a backward-side working chamber for applying a backward fluid pressure to the sub-piston are respectively provided in the casing. A first adjusting operation that is connected to the forward-side and backward-side working chambers, and adjusts the fluid pressure of both working chambers so that the fluid pressure acts backward on the sub piston. A drilling device comprising a fluid pressure adjusting circuit capable of switching to a second adjusting operation for changing and adjusting the fluid pressures of both working chambers so that the auxiliary piston reciprocates back and forth. 2. The fluid pressure adjusting circuit according to claim 1, wherein the fluid pressure adjusting circuit increases only the fluid pressure of the retreating side working chamber during the first adjusting operation, while increasing the fluid pressure of the retreating side working chamber during the second adjusting operation. In addition, a drilling device is configured to alternately increase or decrease the fluid pressure of the forward working chamber. 3. The drilling device according to claim 2, wherein the fluid pressure adjusting circuit includes an electromagnetic switching valve that switches the forward working chamber to a supply side or a discharge side of the working fluid. 4. The fluid pressure adjusting circuit according to claim 2, further comprising a switching valve for switching the forward working chamber to a supply or discharge side of the working fluid, wherein the switching valve is operated by receiving pilot pressure from an electromagnetic valve. A drilling device characterized in that it is a fluid pressure pilot type. 5. The casing according to claim 1, wherein a stopper is provided in the casing to engage with the auxiliary piston to prevent retreat, and the stopper is located at a predetermined position where the shank rod is located forward of the hitting position. A drilling device, sometimes arranged to engage the sub-piston.