JPS6338501B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of operating a hydraulic vibratory pile driver.

FIG. 1 is a diagram showing a device for driving steel sheet piles into the soil using a vibrating pile driver. In the figure, 1 is the crane body, 2 is the crane boom attached to the crane body 1, 3 is the crane hook suspended from the upper end of the crane boom 2, and 4 is suspended from the crane hook 3 via the shock absorber 5. A vibrating pile driver 6 is connected to the vibrating pile driver 4 via a chuck device 7.
A pile 8 attached to is a power source for driving the vibratory pile driver 4.

FIG. 2 is a diagram showing a vibratory pile driver. In the figure, 9 is an electric motor, 10 is a box fixed to the lower part of the electric motor 9, 11 is an eccentric shaft provided in the box 10, 1
2 is a belt for transmitting the rotation of the electric motor 9 to the eccentric shaft 11.

In this vibrating pile driver, when the electric motor 9 is operated and the eccentric shaft 11 is rotated, the vibrating pile driver 4
vibrates vertically, and this vibration is transmitted to the pile 6. Therefore, the frictional force, adhesive force, etc. of the soil acting on the pile 6 is reduced, and the pile 6 sinks into the soil due to its own weight.

By the way, when the vibratory pile driver 4 is started, the vibration frequency of the vibratory pile driver 4 gradually increases, and when the vibratory pile driver 4 is stopped, the vibration frequency of the vibratory pile driver 4 gradually decreases. , the vibration frequency of the vibratory pile driver 4 changes as shown in FIG. The natural frequency f _a of the crane boom 2 is 1 to 5 Hz, and the natural frequency f _a of the crane boom 2 is smaller than the frequency f _b of the vibratory pile driver 4 in a steady state. Therefore, when the vibration frequency of the vibration pile driver 4 reaches the natural frequency f _a of the crane boom 2 when the vibration pile driver 4 starts or stops, the crane boom 2 resonates and the crane boom 2 vibrates violently. Therefore, the life span of the crane boom 2 will be shortened, the damage to the wire rope will be low, and the wire rope and the crane boom 2 will be damaged.
This may cause problems such as collision between the two and the generation of noise.

For this reason, in some cases, efforts have been made to shorten the stopping time by braking the eccentric shaft 11 with a strong braking force when the crane boom 2 is stopped, and the time during which the crane boom 2 resonates. However, it resonates.

This invention was made to solve the above-mentioned problems, and an object thereof is to provide a method of operating a hydraulic vibratory pile driver in which the crane boom does not resonate.

In order to achieve this object, the present invention includes a hydraulic vibrator which is composed of a cylinder and a piston fitted in the cylinder and which is attached to a crane boom, and an oil path leading from a hydraulic source to the hydraulic vibrator. a vibrating valve that generates vibration by continuously switching; a neutral position that is provided between the hydraulic pressure source and the vibrating valve and in which pressure oil is not supplied from the hydraulic source to the vibrating valve; and a neutral position from which pressure oil is supplied from the hydraulic source to the vibrating valve A method for operating a hydraulic vibratory pile driver having a main switching valve having an operating position for supplying pressure oil to the crane boom, wherein at startup, the switching frequency of the vibration valve exceeds the natural frequency of the crane boom. The main switching valve is set to the operating position, and when stopped, the main switching valve is set to the neutral position, and then the vibration valve is stopped.

FIG. 4 is a diagram showing a hydraulic vibratory pile driver.
In the figure, 13 is the hydraulic vibrator of the hydraulic vibratory pile driver, 14 is the cylinder of the hydraulic vibrator 13, 15 is the piston of the hydraulic vibrator 13, 16 is the hydraulic power source, and 18 is the hydraulic source 16 and the hydraulic vibrator. The vibration valve 18 is a vibration valve installed between the machine 13 and the machine 13.
The vibration valve 18 continuously switches the oil path from the hydraulic power source 16 to the hydraulic vibrator 13 to generate vibration. 17 is a main switching valve provided between the hydraulic source 16 and the vibration valve 18; the main switching valve 17 is in a neutral position where no pressure oil is supplied from the hydraulic source 16 to the vibration valve 18; It has an operating position that supplies oil.

In this hydraulic vibratory pile driver, when the main switching valve 17 is set to the operating position and the vibration valve 18 is switched to the A and B positions at a predetermined period, that is, when the vibration valve 18 is activated, the cylinder chambers 14a and 14b are alternately activated. Since pressure oil is supplied to the hydraulic vibrator 13, the hydraulic vibrator 13 vibrates at the switching frequency of the vibration valve 18.

In this invention, the vibration valve 18 is first activated at startup, and when the switching frequency of the vibration valve 18 exceeds the natural frequency _fa of the crane boom 2,
The main switching valve 17 is switched to the operating position, and when stopped, the main switching valve 17 is first returned to the neutral position, and then the vibration valve 18 is stopped. If you do this,
Since the hydraulic vibrator 13 starts at a frequency that exceeds the natural frequency f _a and stops at a steady frequency, the hydraulic vibrator 13 starts at a frequency that exceeds the natural frequency _f a of the crane boom 2.
Since the crane boom 2 does not vibrate, the crane boom 2 does not resonate.

In the above embodiment, when the switching frequency of the vibration valve 18 exceeds the natural frequency f _a of the crane boom 2 at startup, the main switching valve 17 is switched to the operating position, but the vibration valve 18 is not activated. The main switching valve 17 may be switched to the operating position after a predetermined period of time has elapsed since the switch was turned on. In this case, it is necessary to set the predetermined time so that the switching frequency of the vibration valve 18 becomes sufficiently large. Also, when starting up, the vibration valve 18
After the main switching valve 17 is activated, the main switching valve 17 may be automatically set to the operating position, and the vibration valve 18 may be automatically stopped after the main switching valve 17 is returned to the neutral position when the main switching valve 17 is stopped.

As explained above, in the operating method of the hydraulic vibratory pile driver according to the present invention, since the hydraulic vibrator does not vibrate at the natural frequency of the crane boom, the crane boom resonates and vibrates violently. Never. Therefore, the life of the crane boom is extended, damage to the wire rope is reduced, and since there is no collision between the wire rope and the crane boom 2, no noise is generated and the operation is quiet. Can be done. As described above, the effects of this invention are remarkable.

[Brief explanation of the drawing]

Figure 1 is a diagram showing a device for driving piles into the soil using a vibrating pile driver, Figure 2 is a diagram showing a vibrating pile driver,
FIG. 3 is a graph showing changes in the vibration frequency of the vibratory pile driver shown in FIG. 2, and FIG. 4 is a diagram showing a hydraulic vibratory pile driver. 2... Crane boom, 6... Pile, 13... Hydraulic vibrator, 16... Hydraulic source, 17... Main switching valve, 18... Vibration valve.

Claims (1)

[Claims] 1. A hydraulic vibrator consisting of a cylinder and a piston fitted in the cylinder and attached to the crane boom, and a vibration valve that generates vibration by continuously switching an oil path from a hydraulic source to the hydraulic vibrator. and a main body that is provided between the hydraulic power source and the vibrating valve and has a neutral position in which pressure oil is not supplied from the hydraulic power source to the vibrating valve, and an operating position in which pressure oil is supplied from the hydraulic power source to the vibrating valve. In a method of operating a hydraulic vibratory pile driver having a switching valve,
When starting, the main switching valve is set to the operating position after the switching frequency of the vibration valve exceeds the natural frequency of the crane boom, and when stopping, the main switching valve is set to the neutral position, and then the vibration valve is set to the operating position. A method of operating a hydraulic vibratory pile driver characterized by stopping.