JP2000326261A - Hydraulic striker device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent damage of a device due to a lost strike, and easily release a low strike preventing condition so that the device can be reset to an ordinary striking condition. SOLUTION: A discharge port 13 communicating with a low-tension circuit 10 and a pilot port 14 communicating with a set up part of a control valve 12 are provided between front/rear part ports 8, 11 formed in a cylinder 3, and a drain port 15 communicating with a drain passage 16 is provided in the forward side of the front part port 8. A communication groove 18 making a front part chamber 4 communicate with the drain port 15 in a condition closing the front part port 8 by a piston 2, when it is advanced from a regular striking position, is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic striker used as a drive source for rock drills and the like.

[0002]

2. Description of the Related Art Conventionally, as shown in Japanese Patent Application Laid-Open No. 10-80878, for example, a piston having a large-diameter portion in the center and a small-diameter portion before and after the center is slidably fitted into a cylinder to separate the front and rear chambers. A front chamber port for communicating the front chamber to the high pressure circuit and a rear chamber port for communicating the rear chamber to the control valve are provided, and the rear chamber is switched to the low pressure circuit and the high pressure circuit by switching the control valve back and forth. In a hydraulic striking device that alternately switches the piston back and forth, it is possible to prevent the striking portion from being damaged by the occurrence of an idle striking in which the striking is performed in a state where the piston is moved forward from a regular striking position. It has been practiced to provide an idling prevention function.

That is, as shown in FIGS. 6 and 7, a valve control port 34 connected to a valve control chamber for switching a control valve 32 by a valve control circuit 33 is provided in the cylinder 31.
Provided at a position communicating with the front chamber 36 when the piston 35 moves backward, a drain port 38 communicating with the low-pressure circuit 37 is provided behind the valve control port 34, and a short stroke port 39 is provided ahead of the valve control port 34. , Piston 35
When the piston advances, the valve control port 34 and the drain port 38 communicate with each other just before the striking position, and when the piston 35 further advances beyond the striking position, the valve control port 34 communicates with the short stroke port 39. Communication groove 4
0 is provided on the outer periphery of the large diameter portion 35a of the piston 35, and the short stroke port 39 is connected to the valve control circuit 33 and the high pressure circuit 42 through the stroke switching valve 41 so as to be able to communicate with each other.

When the piston 35 further advances beyond the normal striking position and reaches the position shown in FIG. 7, the short stroke port 39 and the valve control port 3
4 communicates with each other through the communication groove 40, the pressure in the valve control chamber becomes high, the valve body of the control valve 32 retreats, and the rear chamber 43
Is communicated with the high-pressure circuit 42 again, so that the piston 35 does not retreat and stops in a state where the piston 35 has moved forward, thereby preventing an idling.

[0005]

As described above, when the piston 35 advances further beyond the normal striking position,
If the rear chamber 43 is communicated with the high-pressure circuit 42 to stop the piston 35 in the forward state, there is an advantage that damage to the device due to the idling can be prevented. When returning from the prevention state to the normal striking state, the distal end of the rod 44 driven by the piston 35 is pressed against the object to be crushed, whereby the piston is pressed against the high pressure force acting on the rear chamber 43. Since it is necessary to return the 35 to the normal striking position, there is a problem that this operation is difficult.

In view of such circumstances, the present invention can effectively prevent damage to the apparatus due to an idle hit, and can easily release the idle hit prevention state and return to a normal hitting state. It is intended to provide a hydraulic hitting device which can be operated.

[0007]

The invention according to claim 1 is
A piston that strikes the tool bit, a cylinder that supports the tool bit and the piston so as to be able to move forward and backward, a control valve that is switched according to the forward and backward movement of the piston, and a gas that urges the piston forward are enclosed. A front chamber communicating with the front chamber, a front port communicating with the front chamber, and a rear section communicating with the rear chamber. A port is formed in the cylinder, and at least one of a rear port and a front port is alternately communicated with a high-pressure circuit and a low-pressure circuit in accordance with a switching operation of the control valve, so that the piston is moved forward and backward to make a tool. In a hydraulic striker configured to strike a bit, between the front port and the rear port, a discharge port communicating with a low pressure circuit,
A pilot port communicating with the installation portion of the control valve is provided, and a drain port connected to a drain passage is provided on the front side of the front port, and when the piston moves forward from a normal striking position, In the state where the front port is closed by the piston, a communication groove is provided for communicating the front chamber with the drain port.

According to the above construction, when the piston advances beyond the normal striking position, the front chamber communicates with the drain port through the communication groove in a state where the other of the front ports is closed by the piston. In this state, the piston is held at the forward position by the gas pressure sealed in the gas chamber in a state in which the pressure in the front chamber is low, so that idling is prevented and the rear chamber is in the low pressure state. By doing so, it is possible to easily return the piston to the normal striking position.

According to a second aspect of the present invention, in the hydraulic hitting apparatus according to the first aspect, an outer peripheral portion of the piston has
The communication groove is formed so as to extend in the axial direction.

[0010] According to the above configuration, when the piston advances beyond the normal striking position, the front port is closed via the communication groove formed in the outer peripheral portion of the piston while the front port is closed by the piston. The part port communicates with the drain port, and the working fluid in the front chamber is discharged from the drain port to the drain passage, so that the pressure in the front chamber becomes low.

According to a third aspect of the present invention, in the hydraulic hitting device according to the first or second aspect, an opening and closing means for opening and closing a drain passage connected to the drain port is provided.

According to the above configuration, the opening / closing means is operated to the open position to bring the drain passage into a communicating state,
When the piston moves forward from the normal striking position, the working fluid in the front chamber is discharged to the drain passage in a state where the front port is closed by the piston. The hitting prevention state is set. Also,
By operating the opening / closing means to the closed position to close the drain passage, the working fluid in the front chamber can be discharged to the drain passage when the piston moves forward from the normal striking position. Because of this, the retreat of the biston is allowed, and the idle hit is possible.

[0013]

1 and 2 show an embodiment of a hydraulic hitting apparatus according to the present invention. The impact tool includes a piston 2 for striking a tool bit including a chisel 1 of a rock drill, a cylinder 3 for supporting the chisel 1 and the piston 2 so as to be able to move forward and backward, and a switching operation in accordance with the forward and backward movement of the piston 2. A front chamber 4 and a rear chamber 5 into which a working fluid such as oil is introduced are formed between the piston 2 and the cylinder 3.

The cylinder 3 is provided with a hydraulic pump 6
A front port 8 for communicating the front chamber 4 with a high pressure circuit composed of a hydraulic pressure supply circuit 7 connected to
A rear port 11 for selectively communicating the rear chamber 5 with the low pressure circuit composed of the hydraulic pressure supply circuit 7 and a hydraulic pressure discharge circuit 10 connected to the discharge tank 9 is formed.
The rear chamber 5 is alternately connected to the hydraulic supply circuit 7 and the hydraulic discharge circuit 10 in response to the switching operation of the piston 2, so that the piston 2 moves forward and backward.

That is, at the center of the piston 2,
A pair of front and rear large-diameter portions 2a and 2b are formed, and the diameter of the rear end 2d facing the rear chamber 5 is set smaller than the diameter of the front end 2c facing the front chamber 4. The pressure receiving area on the rear chamber 5 side is configured to be larger than the pressure receiving area on the front chamber 4 side. When both the front chamber 4 and the rear chamber 5 are communicated with the hydraulic pressure supply circuit 7, the piston 2 is urged forward in accordance with the difference in the pressure receiving area to move forward, and the rear chamber 5 is moved. Is communicated to the hydraulic discharge circuit 10, the piston 2 is urged rearward in accordance with the difference between the internal pressure of the front chamber 4 and the internal pressure of the rear chamber 5 to move rearward. .

Between the front port 8 and the rear port 11, a discharge port 13 communicating with the low pressure circuit comprising the hydraulic pressure discharge circuit 10 and a pilot port 14 communicating with the installation portion of the control valve 12 are provided. When the pilot port 14 and the discharge port 13 are changed from the cut-off state to the conductive state, the rear chamber 5 is connected to the hydraulic discharge circuit 10.
The control valve 12 is configured to be switched in a direction to communicate with the control valve 12. A drain port 15 is formed in front of the front port 8, and a working fluid or the like leaked through a gap between the piston 2 and the cylinder 3 is discharged from the drain port 15 through a drain passage 16 through a drain tank 16. 9 is derived.

A communication groove 18 extending in the axial direction is formed on the peripheral surface of the front end 2c of the piston 2. And
As will be described later, when the piston 2 moves forward from the normal striking position, the front chamber 8 is closed via the communication groove 18 in a state where the front port 8 is closed by the large diameter portion 2a of the piston 2. 4 is configured to communicate with the drain port 15. Further, a gas chamber 19 is provided at the rear end of the cylinder 3 in which gas for urging the piston 2 forward is sealed.

In the above configuration, as shown in FIG. 1, when the piston 2 advances to the normal striking position, the pilot port 14 is in communication with the discharge port 13, so that
The pressure for pushing the valve body of the control valve 12 rearward decreases, and the valve body slides forward to displace.
The rear port 11 communicates with the hydraulic discharge circuit 10 and the rear chamber 5
Since the inside is in a low pressure state, the hydraulic pressure supply circuit 7 switches the front chamber 4
The piston 2 is pushed backward by the high-pressure working fluid introduced therein, and starts to retreat.

The piston 2 is moved to the retracted position shown in FIG.
Is retracted, the communication between the pilot port 14 and the discharge port 13 is blocked by the large-diameter portion 2a of the piston 2, and the front port 8 and the pilot port 14 are in communication. For this reason, the high-pressure working fluid is introduced from the hydraulic pressure supply circuit 7 to the front end side of the control valve 12 via the pilot port 14, whereby the valve body of the control valve 12 is pushed rearward. The control valve 12 is switched so as to slide and connect the rear port 10 to the high-pressure circuit including the hydraulic pressure supply circuit 7.

That is, since the diameter of the front end of the valve body of the control valve 12 is set to a value smaller than that of the rear end, the pressure receiving area at the front end is larger than that at the rear end. When the communication between the pilot port 14 and the discharge port 13 is cut off as shown in FIG. 2, the valve body of the control valve 12 slides rearward in accordance with the difference in the pressure receiving area. The rear port 11 communicates with the high-pressure hydraulic control circuit 7.

Then, since the high-pressure working fluid is introduced into the rear chamber 5 in response to the switching of the control valve 12, the piston 2 moves forward again, and this series of operations is repeated. 2 reciprocates back and forth, and the tool bit 1 is continuously hit.

As shown in FIG. 3, when the object to be crushed is crushed by the tool bit 1 and the piston 2 moves forward from the normal hitting position, the large-diameter portion of the piston 2 2a, the front port 8 is closed, and the front chamber 4 is connected to the drain port 15 through the communication groove 18, so that the working fluid in the front chamber 4 is discharged from the drain passage 16 to the discharge tank 9 And the front chamber 4 is also in a low pressure state. Since the rear port 5 is in a state where the pilot port 14 is in communication with the discharge port 13, the rear port 11 is connected to the hydraulic discharge circuit 10 by the control valve 12 and is maintained in a low pressure state.

Thus, the front chamber 4 and the rear chamber 5
Are in a low pressure state, so that the piston 2 is prevented from retreating. Therefore, the piston 2 is moved to the forward position by the pressure of the gas sealed in the gas chamber 19 located at the rear end of the cylinder 3. The idle hit prevention state is maintained. This prevents the piston 2 from continuously striking the tool bit 1 beyond the normal striking position despite the crushed object being crushed, thereby preventing damage to the hydraulic striking device. be able to.

In addition, since the rear chamber 5 is in a low pressure state, the piston 2 can be moved only by pressing the tip end of the tool bit 1 against a crushed object or the like to lightly urge the hydraulic hitting device forward. It can be pushed into the regular hitting position. Therefore, when the crushing operation of the crushed object is restarted, the above-described idling prevention state is extremely reduced as compared with the conventional apparatus in which the piston needs to be pushed in against the pressing force of the high-pressure working fluid introduced into the rear chamber. It can be easily released.

A communication groove 18 for communicating the front chamber 4 with the drain port 15 is formed in the outer peripheral portion of the piston 2 when the piston 2 moves forward from the normal hitting position. Instead of the above embodiment, as shown in FIG. 4, a communication groove 20 extending forward from the installation portion of the drain port 15 can be formed on the cylinder 3 side. At the time of a normal impact, the communication between the front chamber 4 and the drain port 16 by the communication groove 20 is cut off by the flange portion 21 formed on the piston 2, and the piston 2 is moved by the phantom line as shown by an imaginary line. The front chamber 4 and the drain port 16 are communicated via the communication groove 20 by displacing the flange portion 21 to the front side of the drain port 15 in accordance with the movement to the front side from the regular hitting position. You may be comprised so that it may be performed.

However, when the communication groove 20 is formed on the cylinder 3 side as described above, machining is more difficult than when the communication groove 18 is formed on the outer peripheral surface of the piston 2.
Since the manufacturing cost is high and the above configuration cannot be easily applied to the existing hydraulic hitting device, the structure is such that the communication groove 18 is formed on the peripheral surface of the piston 2 so as to extend in the axial direction thereof. It is desirable.

Further, as shown in FIG.
1st drain port 15 which is connected to front room 4 via
And a second drain port 22 for discharging the working fluid leaked through the gap between the piston 2 and the cylinder 3 to the discharge tank 9, and a drain passage connected to the first drain port 15. Opening / closing means 23 comprising a stop valve or plug plug for opening / closing 16
May be provided.

According to the above configuration, when the opening / closing means 23 is opened to allow the first drain port 15 to communicate with the drain passage 16, when the piston 2 moves forward beyond the normal striking position, The working fluid in the front chamber 4 is
By drawing it out to the discharge tank 9 through the drain passage 24 connected to the drain port 22 and setting the inside of the front chamber 4 to a low pressure state, it is possible to set a state in which the piston 2 is held at the above-mentioned advanced position so as to prevent the idling. .

When the opening / closing means 23 is closed to shut off the drain passage 16 connected to the first drain port 15, when the piston 2 moves forward from the normal striking position, By preventing the working fluid in the compartment 4 from being drawn out to the discharge tank 9 through the drain passage 16 and maintaining the high pressure state, the piston 2 can be retracted to be in a state capable of idling.

Even in the idling prevention state in which the opening / closing means 23 is closed, the working fluid leaked from the gap between the piston 2 and the cylinder 3 is transferred from the second drain port 22 to the discharge tank 9 via the drain passage 24. Since it can be led out, it is possible to prevent the sealing material from being deteriorated by the leaked working fluid.

In the above embodiment, the front port 8 is always connected to the high-pressure circuit, and the rear port 11 is alternately connected to the high-pressure circuit and the low-pressure circuit in accordance with the switching operation of the control valve 12. As described above, the rear port 11 is always connected to the high-pressure circuit, and the front port 8 is alternately connected to the high-pressure circuit and the low-pressure circuit in accordance with the switching operation of the control valve 12. The piston 2 may be moved forward and backward by making both the rear port 11 and the high pressure circuit and the low pressure circuit alternately communicate with each other in accordance with the switching operation of the control valve 12.

[0032]

As described above, according to the present invention, there is provided a piston for hitting a tool bit, a cylinder for supporting the tool bit and the piston so as to be able to move forward and backward, and a control for switching operation in accordance with the forward and backward movement of the piston. It has a valve and a gas chamber filled with gas for urging the piston forward, and forms a front chamber and a rear chamber between which the working fluid is introduced between the piston and the cylinder, A front port communicating with the compartment and a rear port communicating with the rear compartment are formed in the cylinder, and at least one of the rear port or the front port is connected to a high-pressure circuit and a low-pressure circuit according to a switching operation of the control valve. By alternately communicating with each other, in a hydraulic hitting device configured to hit the tool bit by moving the piston back and forth, a low pressure is applied between the front port and the rear port. A drain port communicating with the passage and a pilot port communicating with the installation portion of the control valve are provided, and a drain port communicating with the drain passage is provided in front of the front port, so that the piston has a regular impact. When the piston advances beyond the normal striking position, a communication groove for communicating the front chamber with the drain port is provided in a state where the front port is closed by the piston when the piston advances beyond the normal striking position. By setting both the compartment and the rear compartment in a low-pressure state to prevent the piston from retreating, it is possible to prevent an idling.

Therefore, even if the object to be crushed is crushed, it is possible to prevent the piston from exceeding the normal hitting position and repeatedly hitting the tool bit. Damage to the hydraulic striker can be prevented. Moreover, in the above-described idle hit prevention state,
Since the rear chamber is in a low pressure state, the piston can be pushed into the normal striking position only by pressing the tip of the tool bit against a crushed object or the like and lightly urging the hydraulic striking device forward. There is an advantage that the above-described idle hit prevention state can be easily released and the crushing operation of the crushed object can be restarted.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a hydraulic impact tool according to the present invention.

FIG. 2 is a sectional view showing a state in which a piston is retracted.

FIG. 3 is a cross-sectional view showing a state in which a piston has moved forward from a normal striking position.

FIG. 4 is an explanatory view showing another embodiment of the hydraulic impact tool according to the present invention.

FIG. 5 is an explanatory view showing still another embodiment of the hydraulic impact tool according to the present invention.

FIG. 6 is a sectional view showing a conventional example of a hydraulic impact device.

FIG. 7 is an explanatory view showing a conventional example of a hydraulic impact device.

[Explanation of symbols]

 Reference Signs List 1 tool bit 2 piston 3 cylinder 4 front chamber 5 rear chamber 7 hydraulic supply circuit (high pressure circuit) 8 front port 10 hydraulic discharge circuit (low pressure circuit) 11 rear port 12 control valve 13 discharge port 14 pilot port 16 drain port 18 communication groove

Claims (3)

[Claims] 1. A piston for striking a tool bit, a cylinder for supporting the tool bit and the piston so as to be able to move forward and backward, a control valve that is operated to be switched in accordance with the forward and backward movement of the piston, and for urging the piston forward. Having a gas chamber filled with gas, between the piston and the cylinder, forming a front chamber and a rear chamber into which a working fluid is introduced,
A front port communicating with the front chamber and a rear port communicating with the rear chamber are formed in the cylinder, and at least one of the rear port or the front port is connected to a high-pressure circuit and a low-pressure circuit according to a switching operation of the control valve. In the hydraulic striker configured to strike the tool bit by moving the piston back and forth by alternately communicating with the piston, the discharge port communicating with the low-pressure circuit is provided between the front port and the rear port. In addition to providing a port and a pilot port communicating with the installation portion of the control valve, a drain port connected to a drain passage is provided in front of the front port, and the piston has moved forward from a normal striking position. A hydraulic striking device characterized in that a communication groove for communicating the front chamber with the drain port is provided when the front port is closed by a piston. . 2. The hydraulic hitting device according to claim 1, wherein said communication groove is formed in an outer peripheral portion of said piston so as to extend in an axial direction thereof. 3. The hydraulic hitting device according to claim 1, further comprising opening / closing means for opening / closing a drain passage connected to the drain port.