JPS5815272B2 - hydraulic impact machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic impact machine, and in particular controls the number of blows, the blow energy, and the time during which the drilling tool striking piston contacts and presses the drilling tool (hereinafter, pressing is referred to as time). The present invention relates to a hydraulic impact machine that can perform

The hydraulic impact machine that has been put into practical use is an automatic vibration type that uses a spool valve operated by piston displacement to switch the hydraulic pressure applied to a double-acting cylinder and reciprocates the drilling tool impact piston. It has some disadvantages.

First, since the spool switching cycle is determined by the cycle of the piston's reciprocating motion, the number of strikes and the striking energy cannot be changed independently.

That is, if the piston supply fluid pressure is reduced in order to reduce the impact energy, the piston speed will be reduced, and the number of strikes will also be reduced.

Therefore, it is difficult to perform highly efficient drilling in accordance with geological changes.

Particularly with rotary impact drills, in order to maintain an optimal combination of drill rotation speed, impact energy, feed, etc. and achieve high efficiency drilling, the drill rotation speed must be changed in accordance with changes in the number of impacts. And it will not work unless an expensive control method is adopted.

There is also a report that the efficiency of energy transmission to the rock is better if there is a certain amount of time for the pressing when the piston hits the drilling tool, but this pressing takes almost no time.

Therefore, it is of course impossible to change the pressing time according to the drilling conditions.

Furthermore, since it is a self-oscillation type, there is a dead center, and depending on the relative position of the piston and spool when stopped, there are cases where it may not start.

The purpose of the present invention is to provide a hydraulic impact machine that is highly adaptable to mountains with rapid geological changes, has high energy efficiency, and is durable by independently varying the number of impacts, impact energy, and pressing time. There is something to do.

The present invention constantly supplies high pressure to the non-drilling tool side pressure chamber (hereinafter referred to as the cylinder rear chamber) of the differential cylinder, and the drilling tool side pressure chamber (hereinafter referred to as the cylinder rear chamber) of the cylinder, which is a dog having a piston pressure receiving area from the rear chamber.
In a hydraulic impact machine that reciprocates a drilling tool striking piston by switching the hydraulic pressure applied to the front chamber (hereinafter referred to as the cylinder front chamber) with a spool valve, the spool valve is used to control the oscillator and the piston displacement. By operating both, the number of blows, the blow energy, and the pressing time can be independently varied.

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

1 to 4 show an embodiment in which the hydraulic impact machine of the present invention is applied to a rotary impact drill.

This rotary impact drill consists of a drill rotation mechanism section 1, a drill impact mechanism section 2, and a drill 3.

The drill rotation mechanism section 1 is composed of a hydraulic motor 4, gears 5 to 7, a rotating sleeve 8 with gears, a hydraulic source 9, and a tank 10. It is fitted like this.

FIG. 2 shows a partially enlarged view of the drill impact mechanism.

The drill impact mechanism section 2 is composed of a differential cylinder 11, a drill impact piston 12, a spool valve 13, an oscillator 14, an accumulator 15, a check valve 16, a hydraulic pressure source 17, a tank 18, and a flow path that sustains these. be done.

The piston 12 sliding within the cylinder 11 has two stepped portions 19 and 20, which together with the cylinder wall form a cylinder front chamber 21 and a cylinder rear chamber 22, respectively.

The diameter of the piston is smaller on the cylinder front chamber side than on the cylinder rear chamber side, and the pressure receiving area of the piston is smaller on the cylinder front chamber side.

Further, the airtightness of this cylinder is maintained by a piston bearing 23 having an airtight function.

The spool valve 13 is of a two-position, three-port type, and the spool 24 is housed therein so that it can slide.

The spool 24 has pilot pressure chambers 25 on both sides of the spool.
The neutral position is maintained by springs 27 and 28 provided at and 26, respectively.

The oscillator 14 receives an appropriate supply of liquid from a channel 29, supplies alternating hydraulic pressure to the pilot pressure chambers 25 and 26 of the spool valve via channels 30 and 31, and controls the reciprocation of the spool 24. The structure is such that the liquid removed by the vibration is returned to the oscillator through the channels 31 and 30, merged with the liquid consumed in the oscillation, and unloaded from the channel 32.

Note that this oscillator may be of any type, such as electrical, mechanical, or hydraulic, as long as it can reciprocate the spool 24.

The liquid flow paths connecting the component devices are as follows.

That is, the cylinder rear chamber 22 is connected to the hydraulic pressure source 17 via the flow path 33, the check valve 16, and the flow path 34, and is further connected to the check valve 1.
The accumulator 15 is connected between the cylinder rear chamber 220 and the cylinder rear chamber 220 via a flow path 35 .

In addition, ports 36, 37, and 38 for extracting pilot pressure for detecting piston displacement are provided in the center of this cylinder rear chamber 22, and are connected to the pilot pressure chamber 25 of the spool valve through a pipe 39. has been done.

On the other hand, the cylinder front chamber 21 is connected to the spool valve 13 through a conduit 40, communicates with the hydraulic pressure source 17 through the conduit 41 via the spool valve, or is unloaded through the conduit 42.

Next, the operation will be explained.

In FIG. 2, the piston 12 is in contact with the drill 3 and is about to enter the return stroke.

At this time, since high pressure is applied to the cylinder rear chamber 22, the port 36 is also applied to the pilot pressure chamber 25 of the spool valve.
, pilot pressure is applied via the flow path 39, and the spool valve 13 is switched without waiting for pilot pressure from the oscillator 14.

Therefore, the supply pressure P is applied to both the cylinder front chamber 21 and the cylinder rear chamber 22, and due to the difference in the pressure receiving area of the piston, the piston 1
2 enters the return process.

At this time, the cylinder rear chamber 22 is displaced by the piston.
The liquid inside is blocked by a check valve 16 and stored in an accumulator 15.

When the piston returns completely, the signal from the oscillator 14 switches, and the spool valve enters the state shown in FIG. (where Pb is the back pressure applied to the cylinder front chamber 21).

At this time, the force of PxAR is exerted on the pressure receiving surface on the rear chamber side of the cylinder, and since Pb<<P, PbXAF(PxAR) occurs, and the piston enters the striking stroke.

The potential energy stored in the accumulator during the return stroke is converted into kinetic energy of the piston during the percussion stroke.

By repeating the above steps, the piston hits the drill continuously.

On the other hand, the drill is rotated by a hydraulic motor independently of the reciprocating movement of the piston.

In the rotary impact drill of this embodiment, the number of strikes is determined by the frequency of the oscillator, and therefore can be changed by the pressure supplied to the oscillator.

On the other hand, the impact energy is the supply pressure from the hydraulic pressure source to the piston,
Alternatively, it can be changed by the pressure of the gas sealed in the accumulator.

Further, the rotation speed of the drill can be varied by adjusting the supply flow rate to the hydraulic motor.

Furthermore, the pressing time can be changed by changing the operation timing of the signal from the port 36.

Therefore, since the number of blows, the blow energy, and the pressing time of the rotation speed are independently variable, it is possible to drill holes according to the hardness or softness of the rock without using complicated equipment such as variable pumps as in the past.

Further, in this embodiment, in order to continuously perform a good impact, the ratio of the pressure receiving area AF on the cylinder front chamber side of the piston to the pressure receiving area ARO on the cylinder rear chamber side is set to be as follows.

The reason for this is as follows.

In the hydraulic impact machine of the present invention, the spool valve receives an alternating signal from the oscillator unrelated to piston displacement and a signal from the cylinder rear chamber just before the end of the piston impact stroke, and the return stroke receives a signal from the cylinder rear chamber. , the switching to the impact stroke is performed by a signal from the oscillator, but there is a phase difference between the signal from the oscillator and the signal from the piston displacement, and the magnitude of this is indeterminate.

Therefore, for example, if the signal from the oscillator to return the piston lags behind the signal from the piston displacement, the signal to switch the piston to the percussion stroke will also be delayed, causing the piston to be pushed back too far, causing the percussion stroke to be delayed. On the way, before the piston reaches the drilling tool, a signal from the oscillator is received and the piston is returned, resulting in an unfavorable situation in which it reciprocates but does not make a strike.

In order to avoid this situation, the piston speed during the striking stroke may be increased so that the return signal due to the piston displacement is input before the return signal from the oscillator is input.

This requires the following conditions.

That is, in order to satisfy this condition, it is sufficient to make the force acting on the piston during the impact stroke larger than the force acting on the return stroke.

Here, PB is the back pressure applied to the front chamber, so for simplicity, the condition can be obtained by setting PB kiO.

Furthermore, in this embodiment, as shown in FIG. 2, a plurality of pilot pressure extraction ports from the rear chamber of the cylinder that act on the spool valve are installed in the direction of piston movement, and each port has a plug 4.
3, the timing at which the pilot pressure acts on the spool valve, that is, the pressing time can be easily changed.

Furthermore, as shown in FIG. 4, instead of providing multiple ports, a variable throttle 44 is provided in the middle of the flow path, and by changing the amount of curvature, the operation timing of the pilot pressure, that is, the pressing time can be changed. .

Although this embodiment is an example in which the hydraulic impact machine of the present invention is used in a rotary impact drill, it is clear that it can also be used in a normal breaker.

As described above, in the hydraulic impact machine of the present invention, the number of impacts is determined by the frequency of the oscillator and is independent of the supply pressure of liquid to the piston, so the number of impacts and impact energy correspond to changes in the rock condition. A combination of these is possible, allowing for highly efficient drilling.

Further, since the pressing time when the piston strikes the drilling tool is variable, the efficiency of transmitting the kinetic energy of the piston to the rock can be maximized.

Furthermore, since the pressing time can be shortened to the same level as in conventional hydraulic impact machines, normal wear of the bit can be reduced.

Furthermore, since the spool valve is switched by the signal from the oscillator, it has excellent effects such as no dead center and reliable activation of the piston.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a rotary impact drill employing a hydraulic impact machine according to an embodiment of the present invention, FIG. 2 is an enlarged sectional view showing the impact mechanism of the same embodiment (piston return stroke), and FIG. This figure is an enlarged sectional view (piston impact stroke) similar to FIG. 2 showing the operation of the same embodiment, and FIG. 4 is an enlarged sectional view showing the impact mechanism section of another embodiment. 2... Drill impact mechanism section, 3... Drill, 11...
・Differential cylinder, 12...Drill impact piston, 13
... Spool valve, 14... Oscillator, 15... Accumulator, 16... Check valve, 21... Cylinder front chamber, 22... Cylinder rear chamber, 36, 37, 38...
・Pilot pressure extraction port, 44...variable throttle valve.

Claims (1)

[Claims] 1. By constantly supplying high pressure to the rear chamber of the differential cylinder and switching the hydraulic pressure applied to the cylinder front chamber, which has a larger piston pressure receiving area than the rear chamber, with a spool valve, the drilling tool striking piston is activated. There is also a hydraulic impact machine of a reciprocating type, characterized in that the spool valve is actuated by both a signal from an oscillator and a signal from piston displacement. 2. The hydraulic impact machine according to claim 1, wherein the ratio of the piston pressure receiving area AF of the differential cylinder front chamber to the piston pressure receiving area AR of the cylinder rear chamber is . 3. Claim 1 uses pilot pressure as a signal from piston displacement by providing a flow path that opens into the rear chamber of the cylinder just before the end of the impact stroke, and providing a variable throttle or the like in the middle of the flow path to make the operation timing variable. Hydraulic impact machine according to item 2. 4. As a signal from the piston displacement, a plurality of ports are provided in the direction of piston movement that open into the rear chamber of the cylinder just before the end of the impact stroke, and pilot pressure is used to make the operation timing variable by arbitrarily selecting one. Or the hydraulic shock described in item 2.