JPS58800B2 - Hammer excavator with ground pressure adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a hammer excavator that excavates hard ground by continuous impact of a bit.

BACKGROUND ART Conventionally, an air hammer excavator is known in which an air hammer excavator head having a striking bit at the lower end that is driven up and down by compressed air is connected to the lower end of a rod, and the rod is suspended from a boom so as to be movable up and down.

By the way, in general, in an air hammer excavator, if the ground pressure between the bit and the ground exceeds a certain value, it becomes difficult to drive the bit up and down depending on the pressure of normal compressed air.

Therefore, in conventional air hammer excavators, in order to keep the ground pressure below a certain value, the air hammer excavating head and rod are designed to be small and lightweight, or the length of the rod is shortened to reduce weight. As a result, it had the disadvantage that it could not be used for excavating large diameter or long shafts.

An object of the present invention is to provide a hammer excavator that can eliminate the drawbacks of the conventional hammer excavator, and its main features are that a hammer excavator head is connected to a ram of a hydraulic cylinder that is suspended so as to be able to rise and fall; A circuit for sending pressure oil to the hydraulic cylinder is connected, and a high pressure relief valve, a low pressure relief valve, and a valve for opening and closing the circuit to the low pressure relief valve are connected to the circuit, and both relief valves are connected. The setting pressure is determined appropriately.

The present invention will be described in detail below with reference to the drawings.

In FIG. 1, one end of a hydraulic cylinder 6.6 constituting a ground pressure adjustment device 5 is connected by a wire 4 hanging down from a top sheave block 3 of a vertical leader mast 2 mounted on the front part of a base machine 1. A rotary drive device 10 including a motor 8 and a speed reducer 9 is connected to the lower end of the ram 7.7 of the cylinder 6.6, and a helical screw blade 13 is connected to an output shaft 11 protruding from the lower surface of the drive device 10. The upper end of a screw rod 12 provided on the outer peripheral surface is connected to the lower end of the screw rod 12, and a cylindrical air hammer excavation head 14 having approximately the same diameter as the hollow shaft of the screw rod is connected with its axis aligned.

Reference numeral 15 denotes a guide rail provided on the front surface of the mast 2, to which the drive device 10 is engaged by a slide fitting 16 so as to be vertically slidable.

The hydraulic cylinder 6.6 has one end connected to the lower surface of the upper plate 17 suspended by the wire 4 by means of a pin engagement.

The ground pressure adjusting device 5 is comprised of the hydraulic cylinder 6.degree. 6 and a hydraulic circuit 18 connected to the hydraulic cylinder, and the configuration of the hydraulic circuit 18 is as follows.

In FIG. 2, the pipe 20 connected to the discharge port of the hydraulic pump 19 is connected to each lower chamber 6a of the hydraulic cylinder 6.6.
6a, and drain pipes 21.21 are connected to the upper chambers 6b, 6b of the hydraulic cylinders, respectively, while a branch pipe 22 is branched from the middle part of the pipe 20 between the pump 19 and the hydraulic cylinder 6.6, A high pressure relief valve 23 and a low pressure relief valve 25 are connected to the branch pipe 22 via a switching valve 24, respectively.

26 is an oil tank, 27 is a motor, 28 is a check valve, 2
9 is a flow control valve.

As shown in the third figure, the air hammer drilling head 14 is connected to the lower end of the screw rod 12 by a joint with a pin 30° 31, and a stem 34 of a disk-shaped striking bit 33 is connected to the lower end of the cylinder 32. The upper cylinder 32 is fitted and connected so as to be slidable up and down, and a hammer drive mechanism for continuously driving the bit 33 up and down with compressed air is installed inside the upper cylinder 32.

Reference numeral 35 denotes a guide tube that runs vertically inside the screw rod 12 to guide compressed air to the hammer drive mechanism, and its upper end communicates with a flexible tube 37 connected to the near compressor via a swivel 36 (see Figure 1). .

38 is a screw blade provided on the outer peripheral surface of the excavation head 14.

Next, the operation of this device will be explained.

First, for convenience of explanation, conditions are established as follows.

First, the switching valve 24 of the hydraulic circuit 18 is operated to close the circuit to the low pressure relief valve 25, and then the hydraulic pump 19 is started, and oil is sent into the cylinder 6.6 and the cylinder ram 7.7. Accordingly, the drive device 10, screw rod 12, and excavation head 14 (hereinafter abbreviated as the excavation head, etc.) are raised, and the impact bit 33 at the lower end thereof is separated from the ground.

In this state, a total weight of 5 tons including the excavation head 14, etc. is applied to the cylinder ram 7.7, and the pressure inside the cylinder 6.6 is 5 tons.
becomes.

After the cylinder ram rises to the upper limit, oil is subsequently sent and the pressure in the circuit increases to 10 or more, the high pressure relief valve 23 opens and the oil flows to the drain, reducing the pressure in the circuit to 10 or more.
Keep it at t.

Next, the wire 4 is loosened to lower the drilling head 14 etc. to a height where the bit 33 does not come off the ground, and in this state, the switching valve 24 is switched to open the circuit to the low pressure relief valve 25. opens immediately and drains the oil,
When the pressure in the cylinder 6.6 is rapidly reduced to below 5, the cylinder ram 7.7, the drilling head 14, etc. begin to descend, and the bit 33 at the lower end thereof is grounded.

After touching the ground, the ground pressure applied to the bit 33 gradually increases.

However, when the pressure inside the cylinder 6.6 drops below 3, the low pressure relief valve 25 closes and the ground pressure stops increasing.

At this stage, the ground pressure that the bit 33 receives is 2 t between the total weight of the excavation head 14, etc., 5 t, and the pressure inside the cylinder 6.6, 3 t (the maximum ground pressure that allows the bit to move up and down is 3 t).
(lower than t).

Impact excavation is performed using the bit 33 under this ground pressure of 2t.

Due to the above-mentioned excavation, a hole is formed or softened in the part hit by the bit 33, so the ground pressure of the bit 33 decreases to 2 or less, and the pressure in the cylinder 66 accordingly increases to 3 or more. When the pressure increases, the low pressure relief valve 25 opens to reduce the pressure inside the cylinder 6.6, and accordingly, the cylinder ram 7.7, the drilling head 14, etc. descend to ground the bit 33.

When the pressure in the cylinder 6.6 drops below 3, the low pressure relief valve 25 closes to stop the lowering of the cylinder ram 7.7, drilling head 14, etc.

The ground pressure at this stage is a strong difference of 2 between the total weight of the excavation head 14, etc., which is 5 tons, the weight of the attached earth and sand, which is less than 1, and the pressure inside the hydraulic cylinder 6, which is 3 tons. Resume excavation.

The above action is repeated.

When the cylinder ram 7.7 is fully extended, the low pressure relief valve 25 is closed by switching the switching valve 24, thereby sending oil to the cylinders 6, 6 and raising the cylinder ram 7.7, the drilling head 14, etc. The excavation head 14 and the like are pulled up to the ground by the wire 4.

In this case, the cylinder drum 7.7 is loaded with a total weight of 6 t, which is the total weight of 5 t of the excavation head 14, etc., and 1 t of earth and sand adhering to the screw blades.

After the cylinder ram 7.7 rises to the upper limit, oil is continuously sent and the pressure in the circuit increases to 10 or more.
J IJ-F valve 23 is opened to maintain the pressure in the circuit at 10t.

Next, the earth and sand attached to the screw blades are removed, and then the wire 4 is loosened and the drilling head 14 is lowered to a height where the bit 33 is barely above the bottom of the previously drilled hole, and the same operations as described above are repeated. Then, intermittent excavation will be carried out.

As another embodiment, instead of the screw rod 12, a hollow rod without a screw blade is provided, and in place of the air hammer drilling head 14, an air hammer drilling head without the screw blade 38 is provided, and the other structures are substantially the same as the upper side. An example in which they are identical is also obtained.

In this case, in the operation of this device, the weight of soil adhering to the rod member and the air hammer excavation head can be almost ignored, so under the above conditions, the low pressure IJ IJ
- The set pressure of the valve may be 2t.

Further, in the present invention, not only the upper air hammer mechanism but also a hammer mechanism in which the striking bit is driven up and down by hydraulic pressure or the like and other various hammer mechanisms can be used as appropriate.

According to the present invention, it is possible to adjust the ground pressure applied to the striking bit to a ground pressure that allows the bit to move up and down, thereby making it possible to design a larger hammer drilling head or a longer rod member. This makes it possible to obtain a hammer excavator that can excavate large-diameter or long vertical holes.Furthermore, the ground pressure adjustment mechanism of the striking bit is equipped with a high- and low-pressure IJ-F valve. It has an extremely simple configuration consisting of a hydraulic circuit mainly consisting of a switching valve and a switching valve.To drive the hydraulic cylinder backward, simply close the circuit to the low pressure +J IJ- valve by operating the switching valve, so its operation is extremely simple. It is simple, and since the hydraulic cylinder is suspended from the mast so that it can move up and down, the hydraulic cylinder itself can be short and has great effects.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which FIG. 1 is a partially omitted side view, FIG. 2 is a hydraulic circuit diagram, and FIG. 3 is an enlarged vertical sectional view of the air hammer excavation head portion. 2... Leader mast, 6.6a... Hydraulic cylinder,
7.7a... Cylinder ram, 10... Rotation drive device, 12... Screw rod, 14... Air hammer drilling head, 23... High pressure relief valve, 24...
Switching valve, 25...Low pressure relief valve.

Claims (1)

[Scope of Claims] 1. A hydraulic cylinder is suspended from a mast so as to be able to rise and fall freely, and a hammer drilling head having a striking bit that is driven vertically at the lower end is connected to the ram of the hydraulic cylinder via a rod member and is suspended therefrom. , A circuit for sending pressure oil to the hydraulic cylinder is connected, and a high-pressure relief valve, a low-pressure relief valve, and a valve for opening and closing the circuit to the low-pressure relief valve are connected to the circuit, and the high-pressure The set pressure of the low-pressure relief valve is appropriately higher than the total weight of the hammer drilling head and rod members, etc., and the set pressure of the low-pressure relief valve is based on the total weight of the hammer drilling head and rod members, etc., and the striking bit. A hammer excavator with a ground pressure adjustment device that has a pressure equivalent to the difference between the ground pressure and the ground pressure that can be driven up and down.