JPS5816990B2 - Self-excited hydraulic impact machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic impact machine, and in particular to a self-oscillating hydraulic impact machine that reciprocates a drilling tool impact piston by switching the hydraulic pressure applied to a double-acting cylinder with a spool valve that is activated depending on the piston position. Regarding pressure impact machines.

In conventional self-oscillating type hydraulic impact machines, in order to stably connect the reciprocating motion of the piston, a delicate balance must be satisfied, and the size and shape of the piston and cylinder are subject to considerable restrictions.

Therefore, there is little freedom in design and performance is limited.

Furthermore, since the number of blows and the piston speed are inevitably determined by the weight of the piston and the pressure of the supplied liquid, it is not possible to change the combination of the number of blows and the blow energy depending on the condition of the rock, the hole diameter, etc.

Furthermore, there are reports that the efficiency of energy transmission to the rock is better if the piston is in contact with the drilling tool for a certain amount of time (hereinafter referred to as "pressing time").
This pressing has the disadvantage that it takes almost no time.

An object of the present invention is to provide a self-oscillating hydraulic impact machine that can respond to changes in drilling conditions and has high energy efficiency.

The present invention is a self-oscillating type hydraulic impact machine that reciprocates a drilling tool striking piston by switching the hydraulic pressure applied to a double-acting cylinder using a spool valve that is operated depending on the piston position. A flow path communicating with a hydraulic pressure source through a restriction and a flow path unloaded through a port in the central chamber of a double-acting cylinder opened and closed by the piston position are connected to one side, and a flow path communicating with a hydraulic pressure source through a restriction is connected to the other side through a restriction. A flow path that is unloaded is connected through a flow path that communicates with a hydraulic pressure source and a port in the center chamber of a double-acting cylinder that is alternately opened and closed with the port depending on the piston position, and connected plungers are slidably connected to both ends of the spool. By connecting the moving plunger chamber to the drilling tool side pressure chamber (hereinafter referred to as the cylinder front chamber) and the non-drilling tool side pressure chamber (hereinafter referred to as the cylinder rear chamber) of the double-acting cylinder, two systems are installed on the spool. Apply pilot pressure to ensure spool operation.
It has been stabilized.

EMBODIMENT OF THE INVENTION Hereinafter, one embodiment of the hydraulic impact machine of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the impact machine of this embodiment is composed of an impact machine main body 1, an accumulator 2, a pump 3, and a tank 4, and is adapted to impact a drilling tool 5.

The impact machine main body 1 is composed of a double-acting cylinder 7 having a drilling tool impact piston 6, a spool valve 8, a check valve 9, a starting device 10, and a pipe connecting these.

The cylinder 7, together with the piston 6, has a cylinder front chamber 11.
, a cylinder center chamber 12, and a cylinder rear chamber 13, and the piston 6 is supported by a bearing 14 having an airtight function.

The cylinder 7 is also provided with ports 15 to 24 for liquid inflow and outflow.

Of these, the port 15 is located at the end on the drilling tool side, the port 24 is located at the end on the non-drilling tool side, and the port 23 is located at the end on the non-drilling tool side.
Cylinder rear chamber 1 according to the piston position from the center from 4
It is located in a position that communicates with 3.

The pistons 16, 17, 18 and 20, 21, 22 are located slightly away from the center of the cylinder, and communicate with the cylinder center chamber 12 alternately depending on the piston position.

Further, the port 19 is provided at a position where it always communicates with the cylinder center chamber 12 regardless of the position of the piston in the center of the cylinder.

Plugs 25 are installed in the ports 16, 17, 18 and 20, 21, 22 to open any port and close the other ports.

Note that FIG. 1 shows a state in which the ports 17 and 21 are open.

The spool valve 8 is of a two-position, four-port type, and is housed so that a spool 26 having three land portions can slide therein.

On both sides of this spool 26 are normal pilot pressure chambers 27.
In addition to 28 and 28, there are plunger chambers 3L and 32 via plungers 29 and 30 attached to both ends of the spool.

The pilot pressure chambers 27 and 28 are connected to the port 20, 2L 22 or 16, 17, 18, respectively, and are connected to the throttle 33, 34 and the pilot passage 35, 36.
It is connected to pump 3 via.

Further, the plunger chambers 3L32 and 3L32 are respectively cylinder front chambers 11.
and communicates with the cylinder rear chamber 13.

Therefore, in addition to the normal pilot pressure, the pressures in the front and rear chambers of the cylinder also act on the spool 26 as pilot pressure.

The starting device 10 is connected to the pilot passage 3 of the spool valve 8.
It is set at 6.

This activation device consists of a plunger 3 having a recess 37 in the center.
8, a spring 39, and a plunger chamber 40 that houses them.

The spool valve side pressure chamber 41 of this plunger chamber is connected to the pilot passage 36, the central pressure chamber 42 is connected to the tank 4 via the pilot passage 43, and the non-spool side pressure chamber is connected to the throttle 4.
It is also connected to tank 4 via 4.

The main flow path connecting the components is from the tank 4 to the pump 3.
The cylinder is connected to draw up liquid and alternately supply high-pressure liquid to the cylinder front chamber 11 and cylinder rear chamber 13 via the spool valve 8, or to unload the cylinder front chamber 11 and cylinder rear chamber 13. There is.

That is, a pipe 45 is connected between the pump 3 and the spool valve 8, and a pipe 46 is connected between one port of the spool valve and the port 15 of the cylinder.
The other port of the spool valve and the port 23 of the cylinder are connected by a conduit 47.

A flow path is also formed that branches from the pipe line 47, passes through the check valve 9 and the pipe line 48, and reaches the port 24 of the cylinder, and the accumulator 2 is connected to this pipe line 48.

The check valve 9 is installed in such a direction that high pressure liquid will not flow back from the cylinder to the spool valve.

Meanwhile, the other ports of the spool valve are unloaded by line 49.

Next, the operation will be explained.

FIG. 1 shows a state in which the piston 6 has struck the drilling tool 5 and is about to return.

In this state, since the port [7 is open, a portion of the high pressure liquid from the pump 3 flows through the throttle 34 and the pilot pressure chamber 28.
, the cylinder central chamber 12 and the port 19 and are unloaded.

This flow creates a pressure gradient across the throttle 34, and the pressure in the pilot pressure chamber 28 decreases.

On the other hand, the pressure in the pilot pressure chamber 27 on the opposite side is
1 is equal to the supply pressure because the piston land is closed.

Therefore, the spool 26 is in a state where it is pushed to the right in the figure.

Therefore, the high pressure liquid from the pump 3 acts on the cylinder front chamber 11, while the cylinder rear chamber 13 is unloaded and has only back pressure, so the piston 6 starts moving to the right in the figure.

At this time, the pressures in the plunger chambers 31 and 32 are the same as those in the cylinder front chamber 11 and the cylinder rear chamber 1'3, respectively.

Since this pressure is maintained until the return stroke of the piston is completed, the ports 17.2'f are simultaneously closed or opened during the return stroke, and the pilot pressure chambers 27 and 28
Even if the pressure is the same, the position of the spool 26 is stable and does not change.

When the piston 6 returns further and the port 21 opens, the pump 3
A part of the high pressure liquid from the diaphragm 33 and the pilot pressure chamber 2
7. The air is unrolled through the cylinder central chamber 12 and port 19, and the pressure in the pilot pressure chamber 27 decreases.

On the other hand, the pressure in the pilot pressure chamber 28 on the opposite side is
7 is closed by the land portion of the piston, the pressure becomes equal to the supply pressure, and the spool 26 moves to the left to reach the striking stroke starting position.

(Figure 2). At this time, as described above, high pressure is applied to the plunger chamber 31, and a force acts in a direction to prevent the movement of the first spool 26. However, the ratio of the pressure receiving area of the spool 26 to the pressure receiving area of the plunger 29 must be appropriately selected. This allows the spool to move by overcoming this force.

Even after the spool valve 8 is transferred to the percussion stroke position, the piston 6 continues to retreat for a while due to inertia.

When the piston further retreats and the port 23 is closed,
The liquid in the cylinder rear chamber 13 is discharged from the port 24 and enters the accumulator 2 by the action of the check valve 9.

Then, the brake is applied to the piston by the action of the accumulator, and the piston moves to the striking stroke.

At the beginning of the impact stroke, the port 23 is closed and the check valve 9 is also closed, so the piston is accelerated by the high pressure fluid accumulated in the accumulator 2.

When the piston moves forward and the pressure in the cylinder rear chamber 13 becomes less than the supply pressure, the check valve 9 opens and acceleration by the high pressure liquid from the pump 3 begins.

When the piston 6 moves further forward and the port 23 opens, the high-pressure liquid enters the cylinder rear chamber 13 through the conduit 47, which has little resistance since there is no check valve, etc., and further accelerates the piston.

The accelerated piston moves to the left in the figure and strikes the drilling tool.

Immediately before this impact, the port 17 opens as described above and the pressure in the pilot pressure chamber 28 decreases, so that the spool 26 switches to the state shown in FIG. 1.

By repeating the above steps, the piston 6 continuously strikes the drilling tool 5.

The impact machine of this embodiment is provided with a starting device 10 to ensure starting of the piston.

That is, since the positions of the piston and spool of the impact machine of this embodiment are unstable when stopped, if the impact machine is at the dead center, even if high pressure liquid is supplied, the pressures in the pilot pressure chambers 27 and 28 will be the same and the machine will not start. There is.

Therefore, when stopped, the spring 39 of the starter 10 pushes the plunger 38 to the left in the figure to close the flow path 36 and unload the pilot pressure chamber 28.

Therefore, immediately after startup, the pressure in the pilot chamber 27 becomes higher, and the spool reliably moves to the right.

Therefore, the dead center is removed and startup is ensured.

After activation, the supply liquid pressure is stronger than the force of the spring 39, so the plunger 38 is pushed to the right in the figure and the flow path 36 is opened, so the reciprocating movement of the piston is not hindered.

In the above embodiment, the ports 16, 17, and 18 are provided at three locations at a certain distance in the piston advancing direction, and are set to open into the cylinder central chamber 12 immediately before the piston 6 hits the drilling tool 5. Therefore, by changing the plug 25 and selecting a port, the timing at which the spool 26 is switched can be changed, and the pressing time can be adjusted.

Furthermore, by selecting the ports 20, 21, and 22, the timing at which the spool 26 is switched can be changed, and the stroke of the piston can be changed.

The switching timing of the spool valve can also be changed by changing the diameters of the throttles 33 and 34.

That is, changing the diameter of the throttle changes the amount of pressure drop in the pilot chambers 27, 28, which changes the force applied to the spool 26 and changes the responsiveness of the spool valve.

This has the same effect as changing the switching timing by changing the port position described above.

The third embodiment shows the control mechanism of the present invention applied to an impact machine having a differential cylinder with different effective pressure receiving areas before and after the piston.
As shown in the figure.

In this type of impact machine, the diameter of the piston 6 on the drilling tool side is
This path differs from the above-mentioned implementation path in that it is smaller in diameter than the non-drilling tool side, and there is no port 23 in the rear chamber of the cylinder.

The operation will be briefly explained below.

After the piston 6 hits the drilling tool 5, high-pressure liquid enters the cylinder front chamber 11 by the spool valve as described above, and the piston 6 moves to the right in the figure.

All the liquid in the cylinder rear chamber 13 is then accumulated in the accumulator 2.

At this time, even if the pressure in the cylinder rear chamber 13 exceeds the supply pressure, the piston can return without any problem due to the difference in the piston pressure receiving area.

When the spool valve is switched, the cylinder front chamber 11 is transferred to the tank 4.
The piston moves to the striking stroke because the pressure becomes low.

Repeating the above operations, the piston performs reciprocating motion.

FIG. 4 shows an embodiment in which the accumulator of the embodiment shown in FIG. 1 is replaced with a fluid chamber 60.

With ordinary accumulators such as plug type and diaphragm type, it is sometimes impossible to achieve a high number of blows due to problems in response and durability, but with the fluid chamber of this example, such problems do not occur. do not have.

The hydraulic impact machine of the present invention operates two systems of pilot pressure on the spool valve to ensure reliable switching of the spool valve, so there is no need to strictly maintain a delicate balance like in conventional impact machines. .

Therefore, design and manufacture are facilitated, and the range of combinations of the number of blows and the pressing time of the blow energy is expanded, and an impact machine that can respond to changes in drilling conditions can be realized.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the hydraulic impact machine of the present invention (state at the start of the piston return stroke), and Fig. 2 is a cross-sectional view showing an embodiment of the hydraulic impact machine of the present invention.
FIG. 3 is a cross-sectional view showing the second embodiment of the hydraulic impact machine of the present invention, and FIG. 4 is a cross-sectional view similar to FIG. FIG. 3 is a sectional view showing a third implementation row of the pressure impact machine. 1... Impact machine body, 2... Accumulator, 3...
・Pump, 4...Tank, 5...Drilling tool, 6...
・Drilling tool impact piston, 7...double acting cylinder, 8.
・・Spool valve, 9・・Stop valve, 10 Starting device, 11
...Cylinder front chamber, 12...Cylinder central chamber, 13
...Cylinder rear chamber, 16, 17, 18...Drilling tool side port in the cylinder center chamber, 19...Central port in the cylinder center chamber, 20,21,22...Non-drilling tool in the cylinder center chamber Side port, 25... Plug, 26... Spool, 27° 28... Pilot pressure chamber, 29, 30.
... Plunger, 31.32 ... Plunger chamber, 33
．． 34... Throttle, 35.36... Pilot passage,
38... Plunger of starting device, 39... Spring, 4
0... Plunger chamber of the starting device, 41... Spool side pressure chamber, 42... Central pressure chamber.

Claims (1)

[Scope of Claims] 1. In a self-oscillating type hydraulic impact machine that reciprocates a drilling tool striking piston by switching the hydraulic pressure applied to a double-acting cylinder with a spool valve that is operated depending on the piston position, ordinary pilot pressure chambers on both sides of the spool are used. A flow path that communicates with a hydraulic pressure source through a restriction and a flow path that is unloaded through a port in the center chamber of a double-acting cylinder that is opened and closed depending on the piston position are connected to one side of the cylinder, and the other side is connected to a flow path that communicates with a hydraulic pressure source through a restriction. A flow path that communicates with a hydraulic pressure source through the cylinder and a flow path that is unloaded through a port in the center chamber of the double-acting cylinder that is alternately opened and closed with the port depending on the piston position, and a plunger connected to both ends of the spool. A self-excited hydraulic impact machine characterized in that a sliding plunger chamber is connected to a front chamber and a rear chamber of a double-acting cylinder, respectively. 2. The self-oscillating hydraulic impact machine according to claim 1, wherein a plurality of ports in the central chamber of the double-acting cylinder are installed in the direction of movement of the piston, and any port can be selected using a plug or the like. 3. A plunger with a spring is provided between the hydraulic pressure source and the restriction on one side of the flow path leading from the hydraulic pressure source to the normal pilot pressure chambers on both sides of the spool, and the plunger is connected to the spool-side pressure chamber end port of the plunger, the hydraulic pressure source, and the spool. The port and the throttle are communicated from the center of the side pressure chamber, the center pressure chamber port is unloaded, and the force of the spring in the non-spool side pressure chamber is smaller than the supply liquid pressure. The self-oscillating hydraulic impact machine according to item 1 or 2.