JPS6220550Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a pile driver equipped with a front jack that supports a leader installed at the front of the main body.

One method for driving foundation piles for buildings is to attach an auger excavator to a pile driver, use the auger excavator to dig a hole in the ground, and drive ready-made piles or sheet piles into the hole. With this construction method,
When the casing attached to an auger or excavator is pulled out of the ground, the pullout load exceeds the allowable load of structural parts such as the leader and frame, which can cause deformation and cracks in the structural parts, which can be dangerous. To prevent this, the rope winding force T of the hoisting drum that operates the hoisting rope with the auger and casing attached, or the number of ropes N
It is necessary to reduce the load so that it does not exceed the allowable load, but this is actually impossible in terms of work efficiency and the strength of the hoisting rope.

Therefore, as a means to prevent overload on structural parts such as the leader, conventionally, a means has been taken to detect the pull-out load using a load meter provided at the end of the hoisting rope with the number N of hoisting ropes. That is, a load detector is provided on the upper part of the leader, and the pulling force of the hoisting rope during pulling is converted into an electric signal, which is displayed on an instrument in the driver's seat, thereby detecting the pulling load.

However, this method is unreliable, as the load detector is prone to malfunction due to vibrations, water, moisture, etc. that it receives during operation. Also, the operator must operate the machine while watching the pull-out load displayed on the instrument so as not to exceed the allowable load, and if the load exceeds the allowable load, another device or a crane is used to pull out the load.

On the other hand, when excavating with an auger, you may encounter strata with gravel, and in such cases, the gravel may get stuck in the spiral groove of the auger, causing the auger to suddenly descend deeper than the digging depth at the normal digging speed. There may be a phenomenon where you are drawn into. For this reason, an unexpected overload is applied and there is a problem in that the overload cannot be prevented as in the case of withdrawal.

The purpose of this invention is to reliably prevent overload from being applied to structural parts such as the leader and frame of the pile driver.

The embodiments of this invention will be described below in Figures 1 to 3.
This will be explained using figures.

First, the pile driver shown in FIG. 1 will be described.

A hoisting drum 5 is installed on the upper part of the main body 1, and a leader 2 is attached to the front part with a pin.
The leader 2 is supported by a pair of left and right backstays 3 whose upper end is connected to the upper part of the leader 2 and whose lower end is received by the main body 1. A front jack 4 is provided to receive the entire load. The hoisting rope 6 extends from the hoisting drum 5 and passes through a sheave attached to the upper end of the leader 2.
An auger 7 that is rotated to dig a hole in the ground and a cylindrical casing 8 attached to the auger 7 are suspended.

The reaction force R acting on the front jack 4 is expressed by the following equation.

R=F+W _p +T+P+W _lWhere , F: Pulling force of the auger or casing 8 W _p : Self weight of attached equipment such as the auger 7 T: Tension of the hoisting rope 6 P: Vertical component of the tensile force of the backstay 3 applied to the leader 2 Force W _l : is the dead weight of the leader 2. The load applied to the leader 2 is determined by subtracting the dead weight _Wl of the leader 2, which is known in advance, from the reaction force R of the front jack 4.

This invention detects the reaction force R of the front jack 4 using the internal pressure of the front jack cylinder or a load detector installed between the front jack 4 and the leader 2, and detects the load exceeding the allowable load of the leader 2. When this occurs, an alarm is activated to notify the operator, and the rotation of the hoisting drum 5 is automatically stopped.

Next, one embodiment of this invention will be explained with reference to FIG.

A main hydraulic pump 17 and a sub-hydraulic pump 18 are connected to the engine 16.
On the discharge side, there is a direction switching valve 19, main circuits 20A, 20
It is connected to a hydraulic motor 9 for driving the hoisting drum 5 via B. The main circuit 20B has a solenoid switching valve 1
2 has been inserted. The discharge side of the auxiliary hydraulic pump 18 is connected to the head chamber 4a of the cylinder of the front jack 4 and the rod side chamber 4b through a circuit provided with a direction switching valve 21 and a pilot check valve 22. A pressure switch 10 is connected to the head chamber 4a, which closes an electric circuit (represented by a broken line) when the internal pressure exceeds a set value.The electric circuit is connected to an alarm 11 and an electromagnetic switching valve 12. ing.

Since the reaction force R of the front jack 4 and the pressure A in the head chamber 4a are proportional, the internal pressure A when the dead weight W _l of the leader 2 and the allowable load are added can be calculated in advance, and the front jack 4 The pressure switch 10 attached to the machine is set to operate at the pressure at the allowable load.

When the hoisting drum 5 is pulling out the auger 7 or casing 8, if a pulling force F exceeding the allowable load of the leader 2 is generated, the contact of the pressure switch 10 is switched by the internal pressure A of the head chamber 4a and the electric circuit is closed. The alarm 11 is activated, the electromagnetic switching valve 12 is switched, and the rotation of the hydraulic motor 9 and the hoisting drum 5 is stopped. This prevents overload.

FIG. 3 shows another embodiment of this invention, in which a load detector 13 for detecting the reaction force R is installed between the leader 2 and the front jack 4, and the reaction force is transmitted through the load detector 13. R is displayed on the load cell 14, and the relay unit 15 is configured to operate the alarm 11 and the electromagnetic switching valve 12. Although the hydraulic circuit is omitted, the electromagnetic switching valve 12 is inserted into the main circuit 20B of the hydraulic motor 9.

According to this embodiment, the operator can detect the pull-out load using the load cell 14, and also detect the load during excavation by the auger 7, thereby preventing overload from being applied to the leader 2 during excavation. can.

According to this invention explained above, the following effects can be obtained.

(1) Compared to the upper part of the reader, the load detection device receives less vibration and is not directly exposed to rainwater, so failures can be reduced and equipment reliability can be improved.

(2) It is possible to detect not only the pull-out force but also all loads applied to the leader, making it easy to compare with the allowable load of the leader, and detecting overloads applied to the leader due to alarm activation or stoppage of the hoisting drum. can be reliably prevented.

(3) According to the embodiment in which the load detector 13 is provided,
This prevents overload from being applied to the leader not only when the auger or casing is pulled out, but also when the auger excavates.

[Brief explanation of drawings]

FIG. 1 is a side view showing a pile driver according to this invention, and FIGS. 2 and 3 are system diagrams showing different embodiments of this invention. 1...Main body, 2...Leader, 3...Back stay, 4...Front jack, 5...Hoisting drum, 6...Hoisting rope, 7...Auger, 8...Casing, 9...Hydraulic pressure Motor, 10...Pressure switch, 11...Alarm, 12...Solenoid switching valve, 1
3...Load detector, 14...Load cell, 17...Main hydraulic pump, 18...Sub-hydraulic pump, 19...Direction switching valve, 21...Direction switching valve, 22...Pilot type check valve.

Claims (1)

[Scope of utility model registration request] The pile driver is equipped with a front jack that supports the leader installed at the front of the main body.
A detection device is provided to detect the reaction force of the front jack, and an alarm activated by a signal from the detection device and a solenoid valve that stops the hydraulic motor of the hoisting drum are electrically connected to the detection device. A pile driver overload prevention device featuring: