JPH0525826Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a hydraulic impact tool used for drilling rock or drilling holes.

(Prior Art) In general, hydraulic impact tools used for drilling rocks or drilling holes have a striking piston that is moved back and forth by switching the supply of pressure oil to the front chamber or the rear chamber of the piston before and after the striking piston in the cylinder. The impact force is transmitted to the chisel via a shunt rod placed in front of the impact piston and rotated by a drive means such as a hydraulic motor, and the impact force of the chisel crushes the rock and excavates the hole. However, since it is possible to excavate more efficiently by changing the operating stroke of the striking piston depending on the hardness or softness of the rock to be crushed, various ideas have been made in the past. For example, as described in Japanese Patent Application Laid-Open No. 58-90476, a detection element detects a reflected shock wave generated by the impact between a striking piston and a shunt rod, and a detection element detects a reflected shock wave caused by a strike between a striking piston and a shunt rod, and a signal is sent to the front and rear chambers of the striking piston in response to the reflected shock wave. A system has already been proposed in which a control rod is actuated to switch the pressure oil supply/discharge path.

(Problem to be solved by the invention) In the hydraulic impact tool of the above-mentioned known example, multiple pressure oil supply and discharge passages are provided on the cylinder side for switching the supply and discharge of pressure oil to the front and rear chambers of the impact piston. , which has a structural problem in that the structure around the cylinder has to become complicated.

This invention was made in view of the above points,
The purpose of this invention is to enable switching of pressure oil supply and discharge via a passage formed on the striking piston side, thereby simplifying the structure.

(Means for solving the problem) In the present invention, as a means for solving the above problem, a cylinder formed in the impact tool body,
A striking piston that is slidably inserted into the cylinder, a piston front chamber and a piston rear chamber formed by the cylinder and the piston, and a piston that is supplied to either the piston front chamber or the piston rear chamber. A hydraulic impact tool having a switching valve that switches the pressure oil used to move the impact piston back and forth, the hydraulic impact tool comprising: a first oil passage bored in the axial direction of the impact piston; a plurality of second oil passages, which are bored approximately perpendicularly to the axis at intervals, communicate with the first oil passage, and configured to discharge pilot pressure for performing the switching operation of the switching valve; A shielding member is provided in the first oil passage and allows the second oil passage to be selectively opened and closed.

(Function) In the present invention, the following effects can be obtained by the above means.

In other words, the switching valve switches the supply of oil to either the piston front chamber or the piston rear chamber by selectively opening and closing the second oil passage using a shielding member depending on the rock quality of the rock or the rock to be drilled. Since the operating timing of the striking piston can be changed, the operating stroke of the striking piston can be made variable.

(Embodiments) Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

As shown in FIG. 1, the hydraulic impact tool of this embodiment includes a cylinder 2 formed in an impact tool body 1;
A striking piston 3 is slidably inserted into the cylinder 2, and a front piston chamber 5 and a rear piston chamber 6 are formed by the cylinder 2 and the striking piston 3.
, a shank rod 4 which is slidably inserted in the front side of the striking piston 3 in the cylinder 2 and is rotatable by the action of a drive means (not shown), and a pressurized oil supplied to the piston rear chamber 6. and a switching valve 7 that enables the striking piston 3 to move back and forth.

The piston front chamber 5 and the piston rear chamber 6 are partitioned by a first boss portion 3a formed on the striking piston 3.

The piston front chamber 5 is composed of three chambers 5a, 5b, and 5c that are arranged continuously in the axial direction, and a second boss portion formed on the striking piston 3 as the striking piston 3 reciprocates. Only the two adjacent chambers 5a, 5b or 5b, 5c are in communication with each other through the opening 3b. The piston front chamber 5 is always communicated with the pressure oil supply path 8 and is connected to a switching valve 7 provided in the piston rear chamber 6.
Rear valve rear chamber 10 and pilot pressure supply path 11
It is communicated via. The switching valve 7 is moved forward by pilot pressure supplied through the pilot pressure supply path 11. A valve front chamber 9 of this switching valve 7 is communicated with a pressure oil supply path 10, and a return communication chamber 12 formed in an intermediate portion of the switching valve 7 is connected to a pressure oil discharge path 13.
It is communicated with. The switching valve 7 moves forward when the same pressure is applied to the valve front chamber 9 and the valve rear chamber 10 because the pressure receiving area on the valve rear chamber 10 side is larger than the pressure receiving area on the valve front chamber 9 side. It's becoming like that. Further, the valve front chamber 9 is brought into communication with the piston rear chamber 6 when the switching valve 7 moves backward, and the return communication chamber 12 is brought into communication with the piston rear chamber 6 when the switching valve 7 moves forward. There is.

The ring 2 also includes the striking piston 3.
A return communication chamber 14 is formed at a portion where the first boss portion 3a slides into contact with the return communication chamber 14.
is communicated with the pressure oil discharge path 13.

On the other hand, the striking piston 3 has a first oil passage 15 that is bored in the axial direction and whose front part is blocked, and that has a predetermined interval in the axial direction of the striking piston 3 and is perpendicular to the axis of the striking piston 3. A plurality of second oil passages 16a and 16b are provided which are bored in the direction and communicate with the first oil passage 15. In the case of this embodiment, the first oil passage 15 is communicated with the piston front chamber 5 via a communication passage 17. In other words, the second oil passages 16a and 16b are the same as the first oil passage 1.
5, the valve rear chamber 1 of the switching valve 7 via the communication passage 17, the piston front chamber 5 and the pilot pressure supply passage 11.
0, and is configured to discharge pilot pressure for performing the switching operation of the switching valve 7 to the pressure oil discharge path 13 by communicating with the return communication chamber 14 as the striking piston reciprocates. It is.

In the first oil passage 15, the second oil passage 16 is provided.
A shielding member 1 that allows selective opening and closing of a and 16b
8 is provided so that it can move forward and backward. The shielding member 18
is the first oil passage 15 of the second oil passages 16a, 16b.
A valve part 18a that selectively opens and closes the side opening; and a threaded part 18 that extends rearward from the valve part 18a and is screwed into a threaded hole 19 formed at the rear of the first oil passage 15.
It consists of b. The threaded portion 18b can be threadedly rotated from outside the impact tool main body 1.

In the drawings, reference numeral 20 indicates a sealing member provided at the front and rear ends of the valve portion 18a, and 21 indicates a valve retainer for holding the switching valve 7.

Next, the operation of the illustrated hydraulic impact tool will be explained.

(I) At maximum stroke This is the case when chiseling is performed on hard rock.

In this case, as shown in FIG. 1, the hydraulic impact tool is operated with the shielding member 18 moved forward to close the second oil passages 16a, 16b.

At the forward limit of the impact piston 3, the switching valve 7
High pilot pressure is introduced into the valve rear chamber 10 via the pressure oil supply path 8, the piston front chamber 5, and the pilot pressure supply path 11, the switching valve 7 is moved forward, and the piston rear chamber 6 is returned. Communication room 1
2 and communicates with the pressure oil discharge path 13.

When the striking piston 3 retreats from this state and the rear end of the piston front chamber 5 is brought into communication with the return communication chamber 14 as shown in FIG. Road 11,
It is communicated with the pressure oil discharge passage 13 via the piston front chamber 5 and the return communication chamber 14, and the switching valve 7 is moved backward by the high pressure introduced into the valve front chamber 9, so that the piston rear chamber 6 is It communicates with the pressure oil supply path 8 via the valve front chamber 9 . Therefore, the striking piston 3 starts moving forward due to the high pressure introduced into the piston rear chamber 6.
At the forward limit, the state returns to the state shown in FIG. In other words, by repeating the above operation, the striking piston 3 reaches the maximum operating stroke L ₁
This applies the impact force to the hammer rod 4, resulting in an operation suitable for chiseling hard rock.

At this time, since both the second oil passages 16a and 16b are closed by the shielding member 18, the first
The pressure oil introduced into the oil passage 15 does not act.

() At minimum stroke This is the case when drilling is performed on soft rock.

In this case, as shown in FIG. 3, the hydraulic impact tool is operated with the shielding member 18 retracted to its retraction limit and the second oil passages 16a, 16b opened.

At the forward limit of the impact piston 3, the switching valve 7
High pilot pressure is introduced into the valve rear chamber 10 via the pressure oil supply path 8, the piston front chamber 5, and the pilot pressure supply path 11, the switching valve 7 is moved forward, and the piston rear chamber 6 is returned. Communication room 1
2 and communicates with the pressure oil discharge path 13.

When the striking piston 3 retreats from this state and the second oil passage 16b on the rear side is brought into communication with the return communication chamber 14 as shown in FIG. 4, the valve rear chamber 10 of the switching valve 7 supplies pilot pressure. Road 11,
Piston front chamber 5, first oil passage 15, second oil passage 16b
and the pressure oil discharge path 1 via the return communication path 14.
3, and the switching valve 7 is
The high pressure introduced into the valve front chamber 9 causes the piston rear chamber 6 to be retracted, and the piston rear chamber 6 is communicated with the pressure oil supply path 8 via the valve front chamber 9 . Therefore, the impact piston 3 starts moving forward due to the high pressure introduced into the piston rear chamber 6, and returns to the state shown in FIG. 3 at its forward movement limit. In other words, by repeating the above operation, the striking piston 3 applies a striking force at the minimum operating stroke _L2 to the shunt rod 4, and performs an operation suitable for drilling soft rock.

In addition, when drilling rock between hard and soft rocks, as shown in Fig. 5, the shielding member 1
8, when the hydraulic impact tool is operated with only the second oil passage 16b on the rear side closed, the changeover valve 7 is actuated when the second oil passage 16a on the front side communicates with the return communication chamber 14. The pilot pressure is then discharged, allowing rock to be drilled with an operating stroke intermediate between the maximum and minimum working strokes.

As described above, according to this embodiment, the shielding member 1
By selectively opening and closing the second oil passages 16a and 16b by 8, the operating stroke of the striking piston 3 can be changed as appropriate, and the striking force can be reliably changed according to the quality of the rock mass.

In the above embodiment, a switching valve is used to supply and discharge pressurized oil to the rear chamber side of the piston to switch the forward and backward movement of the impact piston. Of course, the present invention can also be applied to systems in which pressure oil is supplied and discharged using a switching valve.

Further, the present invention is not limited to the configuration of the above-described embodiment, and it goes without saying that the design can be changed as appropriate without departing from the gist of the invention.

(Effects of the Invention) As described above, according to the present invention, a cylinder formed in a striking tool body, a striking piston slidably inserted into the cylinder, and a tool formed by the cylinder and the striking piston. A hydraulic impact tool having a piston front chamber and a piston rear chamber, and a switching valve that switches the pressure oil supplied to either the piston front chamber or the piston rear chamber to enable the percussion piston to move back and forth. , a first oil passage bored in the axial direction of the striking piston, and a plurality of oil passages bored in the axial direction of the striking piston at predetermined intervals and substantially perpendicular to the axis and communicating with the first oil passage,
Moreover, a second oil passage configured to discharge pilot pressure for performing a switching operation of the switching valve, and a shield provided in the first oil passage and capable of selectively opening and closing the second oil passage. Since a member is attached, the shielding member provided on the striking piston side can be operated depending on the rock quality of the rock or the rock to be drilled.
The operating stroke of the striking piston can be made variable by selectively opening and closing the second oil passage and switching the operating timing of a switching valve that switches the supply of oil to either the piston front chamber or the piston rear chamber. This has the practical effect of greatly simplifying the structure compared to the conventional stroke variable operation on the cylinder side.

[Brief explanation of the drawing]

1 and 2 are longitudinal sectional views showing the operating state of a hydraulic impact tool according to an embodiment of the present invention at the maximum operating stroke, and FIGS. 3 and 4 are hydraulic impact tools according to an embodiment of the present invention. FIG. 5 is a longitudinal cross-sectional view showing the operating state at the minimum operating stroke, and FIG. 1...Impact tool body, 2...Cylinder, 3...
Impact piston, 5...Piston front chamber, 6...Piston rear chamber, 7...Switching valve, 15...First oil passage, 1
6a, 16b...second oil passage, 18...shielding member.

Claims (1)

[Scope of utility model registration request] a cylinder formed in a striking tool body; a striking piston slidably inserted into the cylinder;
A piston front chamber and a piston rear chamber formed by the cylinder and the striking piston, and switching that enables the striking piston to move back and forth by switching the pressure oil supplied to either the piston front chamber or the piston rear chamber. a hydraulic impact tool having a first oil passage bored in the axial direction of the striking piston; and a plurality of oil passages bored substantially perpendicularly to the axis at predetermined intervals in the axial direction of the striking piston. and the first
a second oil passage that communicates with the oil passage and is configured to discharge pilot pressure for switching the switching valve; and a second oil passage that is provided within the first oil passage and selectively controls the second oil passage A hydraulic impact tool, characterized in that a shielding member that allows opening and closing is attached to the tool.