JPS6243036B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an earth auger for forming an underground hole for a cast-in-place pile.

Conventional earth augers have the disadvantage that when a relatively large rock group or rock bottom is encountered while drilling with an earth screw, the drilling becomes difficult and the drilling efficiency is greatly reduced. Therefore, in order to solve this problem, for example,
As disclosed in Publication No. 78003, a percussion mechanism (impact device) is built into the hollow shaft of the auger screw, and an impact cutter connected to this mechanism is made to protrude downward from the auger head at the tip of the auger screw. A drilling device has been proposed that excavates by using the percution action of an impact cutter as well as the excavation action of an impact cutter, but according to this conventional device, the drive part of the percution device is directly connected to the rotation drive part of the auger screw. As a result, the impact force of the percussion device was directly transmitted to the rotary drive section and the auger screw, causing damage to them in a short period of time. Furthermore, conventional percussion devices rely on the impact force caused by natural falling, which has the disadvantage of being insufficient to crush rock formations. Furthermore, if the auger screw is in direct contact with the borehole wall as in the conventional device described above, the auger screw will be subjected to resistance from the hole wall, especially the rock wall, due to its inertia during operation of the percution device, resulting in damage to the screw. accidents occur. Furthermore, with conventional equipment, a slight clearance is created between the auger head and the excavated soil due to the operation of the percussion device, so the rotation of the auger screw in a fixed direction gradually rotates by this clearance. The excavation proceeded in a twisted manner, making it difficult to form a highly straight excavation hole.

The purpose of the present invention is to eliminate all of the above-mentioned difficulties, and the gist thereof is to include an elevator frame 1 that is suspended from a leader so as to be able to rise and fall freely, a base 6 of the elevator frame, and a base 6 of the elevator frame, and a an upper frame 8 fixed to the upper end of the guide column via the guide column 7; a movable table 10 that is located between the base and the upper frame and moves up and down along the guide column; Lifting spring means 11 interposed between the movable table and the movable base
, a lowering spring means 12 interposed between the movable base and the upper frame, and a crushing vibrating rod having an upper end fixed to the movable base and a cutter member 20 fixed to the lower end thereof. 5, a short pipe 21 fitted on the outside of the vibrating rod and rotatably mounted on the elevator frame, and a first rotational drive section 22 provided at the upper part of the short pipe to rotationally drive the short pipe. a second rotary drive section 23 that is coaxially disposed at the bottom of the short tube and rotates in the opposite direction to the first rotary drive section; and a second rotary drive section 23 that is connected to the lower end of the short tube and into which the vibrating rod 5 is inserted. The casing 2 includes a hollow auger screw 3 and a casing 2 that is fitted on the outside of the auger screw and whose upper end is connected to the second rotation drive section.

An embodiment of the present invention will be described below based on the drawings.

Figure 1 shows the overall view of the earth auger. Reference numeral 1 is an elevator frame that is suspended from a leader (not shown) installed vertically on a crawler crane, etc., so that it can be raised and lowered freely. , a casing 2 and an auger screw 3 fitted into the casing 2 are connected to each other so as to be rotatable, and a vibrating rod 5 for crushing is vertically movable in a hollow shaft 4 of the auger screw 3. The lower end of the vibrating rod 5 is always projected from the lower end of the hollow shaft 4, and the crushing vibrating rod 5 is provided in the elevator frame 1 as a vertical vibration means that vibrates for a predetermined stroke. 5a.

To explain the above structure in more detail, the elevator frame 1 has four pillars 7 at the four corners of the base 6.
...... (see Figure 2), and these pillars 7...
An upper frame 8 is fixed to the upper end, and a support frame 9 is connected to the lower part of the base 6. The vertical vibration means 5 is provided between the base 6 and the upper frame 8 in the machine frame 1.
It is equipped with a. The vertical vibration means 5a is composed of, for example, an air spring device, and a movable base 10 is attached to the supports 7 so as to be vertically slidable. two air spring bodies 11, which serve as rising spring means;
11, an air distribution pipe (not shown) is connected to each air spring main body 11, and an air compressor (not shown) is connected to an air supply port and an exhaust port (not shown) provided in this air distribution pipe. ) air hose etc. (not shown)
are connected via a solenoid valve (not shown), and by switching the solenoid valve, pressurized air from the compressor is alternately pressed into and discharged from each air spring body 11 to expand and contract the air spring body 11. The movable table 10 is configured to vibrate vertically between the base 6 and the upper frame 8 with a predetermined stroke. The upper end of the frame-breaking vibrating rod 5 is fixed to this movable table 10, and the vibrating rod 5 is movable by the vertical movement of the movable table 10 caused by the operation of the vertical vibrating means 5a (air spring device) mentioned above. It will vibrate up and down with the same stroke as the table 10. In addition, in the above air spring device, when the air in the air spring body 11 is released, the movable base 10 is lowered by the weight of the vibrating rod 5, and the air spring body 11 is contracted. In order to increase the speed, a coil spring 12, which is a lowering spring means for urging the movable base 10 downward, is interposed between the upper frame 8 and the movable base 10 in each support column 7. When the air spring main body 11 is expanded by press-fitting air, that is, when the movable base 10 rises, it is compressed, and the air is released and the movable base 1
When the movable base 10 moves to a lowering operation, the restoring force of the spring 12 increases the lowering speed of the movable base 10. Incidentally, instead of providing such a coil spring 12, an air spring body similar to the above-mentioned lifting/lowering spring means 11 is interposed between the upper pedestal 8 and the movable table 10, and the upper and lower air spring bodies are It is also possible to alternately expand and contract.

In addition, the casing 2 and the auger screw 3
To explain the drive method, an electric motor 13 is fixedly installed in the elevator frame 1, and a short pipe 21 is rotatably installed in parallel with its output shaft (not shown), and a short pipe 21 is fixedly installed on the output shaft. The rotational force of the electric motor 13 is transmitted to the short tube 21 by the first rotation drive section 22, which is composed of a small gear (not shown) provided therein and a large gear 14 that is fixedly installed on the short tube 21 and meshes with the small gear. and the auger screw 3 connected to the short pipe 21
drive the rotation. Furthermore, a gear 15 is fixedly installed at the lower part of the short pipe 21, and a plurality of pinions 16 are mounted on the gear case 17 so as to mesh with the gear 15.
The upper end of the casing 2 is integrally connected with a bolt 19 to a second rotation drive section 23 consisting of an inner gear 18 which is also held in the gear case 17 so as to mesh with and rotate with these pinions 16. The casing 2 is rotated by the second rotary drive unit 23.
is configured to rotate in a direction opposite to the rotational direction of the auger screw 3. As described above, the rotational force of the electric motor 13 is applied by the first rotational drive section 22 and the second rotational drive section 23 to cause the auger screw 3 and the casing 2 to rotate in opposite directions while being inseparably related to each other. It's getting old.

The vibrating rod 5 is the hollow shaft 4 of the auger screw 3.
The lower end of the first
At the lowest position indicated by the imaginary line in the figure, it protrudes by at least a length corresponding to the stroke of the movable base 10, and a cutter member 20 is attached to the lower end of the vibrating rod 5.

When operating the earth auger having the above-described configuration, first, the elevator frame 1 is suspended and supported from the top of the leader (not shown) at an appropriate height.
The electric motor 13 is operated to rotate the auger screw 3 and the casing 2, and a lifting operation wire (not shown) is fed out to lower the casing 2 and the auger screw 3 through the machine frame 1 while rotating them. A hole is drilled in the ground G by the operation. If the ground G is a normal soil layer, it would be possible to drill the hole simply by rotating the auger screw 3 and the casing 2, but during drilling, we encountered a layer of rock group R as shown in Figure 1. In this case, the vibration rod 5 for crushing is vibrated vertically by operating the vertical vibration means 5a consisting of the spring means 11 for raising and the spring means 12 for lowering, and the auger screw 3 and the casing are vibrated at the lower end of the vibration rod 5. Prior to the drilling work in step 2, the rock is crushed to facilitate drilling. Although it is possible to crush rocks with the crushing vibrating rod 5 by directly hitting the rock with the lower end of the vibrating rod 5, by attaching a cutter member 20 to the lower end of the vibrating rod 5, the rock can be crushed into fine pieces. be able to. The crushed rock fragments thus crushed or the earth and sand excavated in the ordinary earth and sand layer are discharged to the ground by the auger screw 3 during the drilling operation. After the drilling operation is completed, the operation of the vertical vibration means 5a is stopped, and the crushing vibration rod 5 is held at the highest position, and the auger screw 3 and casing 2 are normally rotated in the opposite direction to the direction of rotation during drilling. The auger screw 3 and casing 2 are extracted to the ground through the elevator frame 1 while rotating in the direction, and then the ready-made pile is inserted into the excavated hole.

In the embodiment described above, the auger screw and the casing are integrally and inseparably rotated in opposite directions by one electric motor, but the present invention is not limited to this, and for example, two electric motors are used. The auger screw and the casing may be appropriately rotated separately and independently using a screwdriver.

Therefore, according to the present invention, the first rotary drive section 22 and the second rotary drive section 23 that rotationally drive the auger screw 3 and the casing 2 and the crushing device that is inserted into the hollow shaft of the auger screw 3 and vibrates up and down. Since the lifting spring means 11 and the lowering spring means 12 are interposed between the vibrating rod 5, the vibrating rod 5 is caused to vibrate up and down by the operation of both spring means 11 and 12, and at the same time, both of these spring means 11 and 12 are operated. The spring means 11 and 12 exhibit a buffering effect, which has the effect of weakening the impact force on the auger screw and the rotational drive section and preventing damage thereto.

Further, according to the present invention, when the crushing vibrating rod 5 is lowered by its own weight, it is further forcibly pushed down by the lowering spring means 12, so that the crushing force against the rock layer etc. becomes even stronger, and therefore the excavation work is improved. Improves efficiency.

Furthermore, according to the present invention, since the casing 2 is fitted on the outside of the auger screw 3, the auger screw 3 is not subjected to resistance from the borehole wall, especially the rock wall, during the excavation process. Therefore, even if the auger screw 3 moves slightly due to inertia caused by the vibration of the crushing vibrating rod 5, the screw will not be damaged.

Furthermore, according to the present invention, the first rotary drive section 22
and the second rotation drive unit 23 to reverse the rotation directions of the auger screw 3 and the casing 2,
Since the rotation reaction force is offset, there is no twisting even if impact vibration is received during excavation, and the straightness of the excavation hole can be increased accordingly.

[Brief explanation of the drawing]

FIG. 1 is a partial vertical sectional view showing one embodiment of the earth auger of the present invention, and FIG. 2 is a sectional view taken along the line -- in FIG. DESCRIPTION OF SYMBOLS 1... Elevator frame, 2... Casing, 3... Auger screw, 5... Vibrating rod for crushing, 6... Base, 7... Guide column, 8... Upper frame, 10...
Movable base, 11... spring means for rising, 12... spring means for descending, 20... cutter member, 21... short tube, 22... first rotation drive section, 23... second rotation drive section.

Claims (1)

[Claims] 1 Elevator frame 1 that is suspended from the leader so that it can be raised and lowered freely
and an upper frame 8 fixed to the upper end of the guide column via a base 6 of the elevator frame and a guide column 7 erected on the base; Movable platform 1 that moves up and down along the guide column
0, a rising spring means 11 interposed between the base and the movable base, a lowering spring means 12 interposed between the movable base and the upper frame, and the movable base. a crushing vibrating rod 5 having an upper end fixed to it and a cutter member 20 fixed to its lower end;
a short pipe 21 fitted on the outside of the vibrating rod and rotatably mounted on the elevator frame; a first rotational drive section 22 provided at the top of the short pipe to rotationally drive the short pipe; A second rotary drive section 23 is provided coaxially at the bottom of the short tube and rotates in the opposite direction to the first rotary drive section; The auger screw 3 is fitted on the outside of the auger screw,
An earth auger comprising: a casing 2 whose upper end is connected to the second rotary drive section;