JPH0119004B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diameter-expanding excavation method for continuous wall piles or cast-in-place piles, and a diameter-expanding excavator used to carry out the method.

A machine that excavates a hole with the same diameter as the outside diameter of the foundation pile and a hole with a larger diameter than this hole for tip hardening has been known as a two-stage expansion bit, for example, as disclosed in Utility Model Publication No. 53-22404. This method has been proposed in the official gazette, Utility Model Publication No. 54-44962, etc. The excavators described in these publications are able to drill holes with different diameters in two stages without changing equipment, and although the construction time can be shortened, the disadvantage is that the machine structure is complex and costs are high. However, there is also the disadvantage that the cross-sectional area of the blade to which the tip is attached must be increased. The reason for this is that no special consideration is given to the mounting position of the tips, and therefore all the tips of the blade come into contact with the excavation wall surface at the same time, and a large excavation rotational twisting force acts on the blade.
Furthermore, in conventional excavators of this type, the excavation work and the slime cleaning work, which are completely different, were performed using the same mechanism (bit), resulting in poor work efficiency.

The present invention aims to provide an excavation method and an excavator that eliminate the conventional drawbacks as described above. According to the present invention, the bit is composed of both an inner and outer bit, which share the roles of excavation and slime cleaning, and the blade of the outer bit is made of a flexible material, and the bit shaft is made of an elastic material. If large drilling resistance occurs, install it through the hole to avoid this resistance, and drill with the outer bit expanded in diameter, and when the diameter is reduced and rotated in the opposite direction, the slime will fall into the center of the hole. It's becoming like that.

When carrying out the present invention, it is preferable to provide a steady rest and water flow guide plate between the bit shafts.

Therefore, the bit rotating shaft is rotated to the convex side of the outer bit, the bit shaft is rotated to the concave side, and the outer bit is inserted into the cylindrical hole in a reduced diameter state. Next, the bit rotating shaft is rotated in the opposite direction to the above-mentioned direction, and the outer bit is rotated to expand its diameter to excavate. When a predetermined amount of excavation is completed, the excavator is slightly raised, the outer bit is rotated to reduce its diameter, the slime is collected in the center of the hole, and the slime is guided to the reverse hole by the inner bit and discharged to the outside.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of an excavator according to the present invention will be explained below with reference to the accompanying drawings, and then an excavation method using the excavator will be explained.

Now, referring to FIGS. 1 and 2, the excavator according to the present invention includes one bit rotation shaft 1, three bit shafts 10, an outer bit 20 and an inner bit attached to the bit shaft. It is equipped with 40 bits.

The bit rotation shaft 1 is rotated left and right by a prime mover (not shown), and due to this left and right rotation,
The bevel gear 2 attached to the tip rotates the gear 11 of the bit shaft 10 from side to side. The three bit shafts 10 are located at the enlarged vertices of a triangle, and the bit rotation shaft 1 is installed at the center thereof.
Therefore, when the bit rotation shaft 1 is rotated left and right, the bit axis is simultaneously rotated in the right and left directions.

The outer bit 20 is composed of a blade 21, which is attached to the bit shaft 10 via an elastic body.For example, the head 12 of the bit shaft and the bit shaft 10 are connected to a coil spring housed within the bit shaft. They are connected via 13. Therefore, when excessive digging resistance acts on the blade 21, the coil spring 13 provides relief. Note that if the blade is made of flexible material, it can be used to avoid hitting large gravel or the like with the bit. An inner bit 40 that excavates the bottom of the hole and guides slime to the reverse hole, which will be described later.
is provided at the lower end of the bit shaft 10, as shown in FIG.

The inner and outer bits 40, 20 are attached to the bit shaft as described above, and their shapes will be explained below. The blade 21 of the outer bit 20 is flared downward and has a convex surface. The chip 22 is implanted on the convex side. These chips 22 are preferably provided along the edge of the window 23 or the flange 24. The inner bit 40 has a plurality of chips 42, 42, . . . planted on the concave side. Then, these internal and external bits are paired and
As shown in the figure and FIG. 3, they are arranged at an angle of about 90 degrees when viewed from above. As shown in FIG. 4, the outer bit 20 can also be made wider on the bit shaft 10' side and narrower at the tip. It is clear that if the blade is configured in this way, the shape of the expanding hole will only be approximately spindle-shaped.

A reverse pipe 50 is provided approximately at the center of the excavator configured as described above. A reverse suction port 51 is provided at the lower end of this tube, and the upper end is connected to a reverse pump (not shown) or the like. Further, a steady rest and water flow guide plate 52 is inserted near the lower end of the reverse pipe.
This plate 52 is connected to the bit shafts 10, 10, 10.
It is also inserted or locked. Therefore, the bit shaft 10 is bundled by the plate 52 and the box 60. Further, through holes 53, 53, . . . having a substantially trapezoidal shape are formed in this plate 52 to increase the flow velocity of the water flow.

Next, a diameter-expanding excavation method will be described using the excavator configured as described above. First, a cylindrical hole B as shown in FIG. 2 is drilled using, for example, a clam shell. Next, the bit rotating shaft 1 is rotated to the left (as shown in FIG. 2). Then, the gear 12 meshing with the bevel gear 2 rotates in the opposite direction. That is, the bit shafts 10, 10, 10 rotate to the right. Therefore, the outer bit 20 also rotates and the first
The diameter is reduced as shown by 20' in the figure. In this reduced diameter state, the bit is inserted into the cylindrical hole 60, and then the bit rotating shaft 1 is rotated to the right. Then, the diameter of the outer bit is expanded and excavation becomes possible. The drive shaft 61 (and box 60) is then rotated counterclockwise as indicated by arrow A in FIG.
Then, the chips 22, 22, . . . of the outer bit excavate so as to peel off the excavation wall. During this excavation, the blade 21 is curved so that the outer tip gradually works as the excavation progresses, and the blade 21 is provided with windows 23, 23, etc., so that excessive excavation resistance is prevented. Doesn't work. Also, since the blade is made of flexible material,
The impact of excavation is also buffered, and if rotation becomes difficult due to hitting large gravel, the diameter of the bit is reduced by a coil spring built into the bit shaft 10 to avoid this.

When the prescribed excavation is completed as described above, it is necessary to clean the slime before concrete is poured, and this cleaning is carried out as follows. That is, pull the excavator upwards slightly and rotate the excavator clockwise. Next, the rotary shaft 1 is gradually rotated to the left to gradually reduce the diameter of the outer bit 20. At this time, the inner bit 40 is
It is clear that the position indicated at 40' in FIG. 1 is taken. By reducing the diameter of the outer bit 20 in this manner, the excavator is rotated in the clockwise direction indicated by arrow C in FIG. In this case, no large stress is applied to the blade 21 of the outer bit, and the outer bit pulls the slime down to the center of the hole, while the inner bit 40 guides it to the reverse hole 51.
The slime thus collected is discharged to the outside through the reverse pipe 50.

As detailed above, according to the present invention, the blade of the bit is flexible and at the same time the bit is attached to the bit shaft via an elastic body, which has the advantage that excessive stress is not applied to the excavator during excavation. You can obtain the desired effects and effects.
In addition, two types of bits are provided on one bit shaft, an outer bit for digging and an inner bit mainly for slime cleaning, so the work roles are separated and the digging and slime cleaning effects are further enhanced. It will be done. In addition, a guide plate is provided to increase the flow velocity at the reverse suction port, but this guide plate also acts as a steady rest for the bit shaft, so there is no need to provide a separate steady rest, making the entire structure compact and lightweight. be able to.

[Brief explanation of drawings]

Fig. 1 is a plan view of the diameter expanding excavator according to the present invention, Fig. 2 is a partially sectional front view showing the state of use, Fig. 3 is a detailed sectional view of the inner and outer bits, and Fig. 4 is another example of the outer bit. It is a front view showing an example. 1... Bit rotation axis, 10... Bit shaft, 13... Elastic body (coil spring), 20... Outer bit, 21... Blade, 22... Chip, 23... Window, 40... Inner bit, 50... Reverse tube, 52... Steady rest Water flow guide board.

Claims (1)

[Claims] 1. A method for expanding the diameter of a pre-drilled cylindrical hole at any position, which includes a plurality of external bits each having a tip on the convex side of the blade when viewed in plan; Using an excavator equipped with an inner bit having a tip on the concave side, the excavator is inserted into the hole with the blade of the outer bit reduced in diameter, and the outer blade is expanded in diameter. When the outer bit encounters large digging resistance in such a state that the tip of the outer bit peels off the excavation wall surface, the outer bit is rotated and excavated to avoid this resistance, and then the diameter of the blade of the outer bit is reduced. The slime is collected in the central part of the hole by rotating the outer bit in the opposite direction to the excavation direction, the slime is guided to the reverse hole by the inner bit, and is discharged to the outside from the reverse pipe. Diameter expansion drilling method for piles. 2. A bit rotation shaft, and a plurality of bit shafts that rotate in opposite directions in conjunction with the left and right rotation of the shaft;
The outer bit is attached to the shaft of these bits and expands the diameter of the excavation wall while being enlarged, and when the diameter is reduced and rotated in the opposite direction, the slime is collected in the center of the hole, and the outer bit is attached to the bottom of the outer bit. is installed in
Equipped with an inner bit that excavates the bottom of the hole and guides slime to the reverse hole when rotated in the opposite direction,
The blades of the inner and outer bits can be changed into an enlarged diameter state and a reduced diameter state by the left and right rotation of the bit rotating shaft, and the blades of the outer bit have a convex side when viewed from above, and the blades of the inner bit have a convex side when viewed from above. A diameter expanding excavator characterized in that a tip is attached to the concave side of the bit, and the outer bit is made of a flexible blade and is attached to the bit shaft via an elastic body. 3. The second claim in which the blade of the outer bit is provided with a plurality of windows at appropriate intervals.
Diameter expansion excavator described in section.