JPS59397Y2 - Reverse rotation drill - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a reverse circulation drill used for excavating cast piles such as cast concrete foundation piles.

To excavate a conventional cast-in-place concrete foundation pile, for example, as shown in Figure 4, a drill pipe A, a bit body attached to the lower end of this drill pipe, an enlarged frame C, and this enlarged frame are used. A vertical hole H with the same diameter as the bit body is drilled into the ground G by a reverse circulation drill E consisting of an oil jack d that expands and contracts.
As the excavation progresses and the depth of the shaft H reaches a predetermined depth, as shown in Fig. 5, the oil jack d is extended to gradually widen the enlarged pit (c) while continuing the excavation until it reaches the lower end of the shaft H. An enlarged portion H' is formed, and the excavated earth and sand, together with the water or groundwater injected into the shaft, is sucked up by the drill pipe a and discharged to the outside.

However, when concrete is placed in the shaft H excavated in this way, a concrete foundation pile A with a large bearing capacity and an enlarged part A' at the lower end is constructed in the ground G as shown in Figure 6. It is something that will be done.

However, in the above method, when the enlarged part H of the shaft H is formed using the enlarged bit b of the reverse circulation drill E, a hole wall protective film (mud film) formed by muddy water is formed on the hole wall of the shaft H. There is a risk of collapse due to the rotation of the enlarged frame C.

Furthermore, this enlarged frame C has a disadvantage in that its mechanical strength is extremely weak due to its structure.

Further, as conventional methods of this kind, methods shown in FIGS. 7 to 9 have also been carried out.

In other words, this method uses a drill pipe e as shown in Fig. 7.
and the bit body f attached to the lower end of this drill pipe e.
Then, a reverse circulation drill j consisting of a guide frame g, an expanding tool, and an expanding device i for expanding and closing the expanding tool is rotated to drill into the ground G a piece of the same diameter as the bit body f. When the shaft H is excavated and the depth of the shaft reaches a predetermined depth, as shown in FIGS. 8 and 9, the expansion device i is moved.
The excavation continues while expanding using the guide frame g as a guide to form an enlarged part H' at the lower end of the shaft H, and the excavated earth and sand are sucked up by the drill pipe e and discharged to the outside together with the water or groundwater injected into the shaft H. It is something to do.

However, this method also has various drawbacks as described below.

In other words, as shown in Fig. 8, if you try to secure a desired hole diameter by stopping the descending of the enlarging tool halfway, the bit body f will be in front of the enlarging tool, so when drilling the enlarged part H', B
There is a risk that the earth and sand in the area will collapse and the bit body f will be buried in this earth and sand, making it impossible to suck up the excavated earth and sand.

In addition, when a hydraulic device is used as the spreading device i for the expanding tool f, the expanding tool becomes unable to descend due to an obstacle S such as a boulder in the ground G, as shown in FIG. 11, as shown in FIG. In some cases, the bit body f may float upwards, forming a transverse wave portion H// slightly above the lower end of the shaft H.

Furthermore, when the expanding tool is pushed out (pushed down) with a weight, obstacles such as boulders hit the expanding tool, making it extremely difficult to expand the hole wall of the shaft H.

In addition, there is a risk that stones may get stuck on the contact surface between the guide frame g and the enlarging tool, making it impossible to lower or raise the enlarging tool, making construction impossible.

The object of the present invention is to provide a reverse circulation drill that does not have the above-mentioned drawbacks.

Figure 1 shows the reverse circulation drill of the present invention, in which 1 is a drill pipe, 2□, 22
．． Reference numeral 23 denotes a bit body attached radially to the lower end of the drill pipe 1, and each bit body is provided with an arcuate guide groove 4 and a guide pin 5 at appropriate positions on the blade 3, and a plurality of guide pins 5 on the lower edge. A cutting blade 6 is attached.

Reference numerals 71, 72, and 73 indicate expanding tools, and each of these expanding tools has an arcuate guide groove 9 and a guide pin 1 at appropriate positions on the blade 8.
0.

However, the bit body 2□, 2°, 23 and the enlarger 70
, 7□, and 73 are polymerized to form the bit body 2□,
The guide pins 5 of 2□ and 23 are inserted into the arc-shaped guide grooves 9 of the enlargers 70. They are fitted into the grooves 4, respectively.

111, 112, and 113 are oil jacks attached to the outer peripheral surface of the lower end of the drill pipe 1.
The rods 12 at 1□, 11°, and 113 are enlargers 7, respectively.
A pin 13 is pivotally attached to one corner of the upper edge of □, 7□, and 73.

14 is a central cutting edge attached to the lower end of drill pipe 1; 15
is a water intake port provided at the lower end of the drill pipe 1.

The reverse circulation drill of the present invention includes each bit body 2□, 22, 23 and each expanding tool 7 as shown in Figure 1.
□, 72, 73 are fully overlapped and when this bit body and expander are rotated, the length between the center of the drill pipe 1 and the outer end of the blade 3 of each bit body 2□, 22, 23 A cylindrical shaft H with a radius of is excavated into the ground G.

As the excavation of this shaft progresses in this way and the depth reaches a predetermined depth, the oil jack 1
1□, 11□.

When each rod 12 of 113 is extended, the expanders 7□, 7
2°73 is the guide pin 5, 10 and the arcuate guide groove 4
, 9 and is expanded outward as shown by the arrow P, so that by the rotation of the expanding tools 70, 7□, and 73, an enlarged portion H' having a diameter larger than the diameter of the shaft H is formed at the lower end of the shaft H. It is something that will be done.

As mentioned above, the reversible circulation drill of the present invention has a bit body and an expanding tool that are both plate-shaped, and the expanding tool is removed using the expanding tool and the guide pin and guide groove provided on the bit body as guides. Since it is configured to expand inward or contract inward, its construction is extremely simple and its mechanical strength is also extremely high.

Therefore, this reverse circulation drill can effectively eliminate the various drawbacks of the conventional reverse circulation drill described above.

[Brief explanation of the drawing]

Fig. 1 is a front view of an embodiment of the reverse circulation drill of the present invention, Fig. 2 is a sectional view taken along line I-I in Fig. 1, and Fig. 3 is a front view when the expander is expanded outward. , Fig. 4 is a front view of an example of a conventional reverse circulation drill of this kind, Fig. 5 is a front view of the expanded frame, and Fig. 6 is a front view of an example of a conventional reverse circulation drill of this type. A vertical cross-sectional view of a concrete foundation pile cast in a shaft, Fig. 7 is a front view of another example of a conventional reverse circulation drill of this kind, and Figs. 8 to 11 show the operation of this reverse circulation drill. It is an explanatory diagram. 15...Water inlet, 1...Drill pipe, 2□, 2□. 23... Bit body, 70, 7□, 73...
...Magnifier, 11,. 112゜113... Oil jack, 5, 10... Guide pin, 4゜9... Arc-shaped guide groove.

Claims (1)

[Scope of utility model registration request] A drill pipe with a water intake port at the lower end, a plurality of bit bodies attached radially around the outer periphery of the lower end of the drill pipe, an enlarger superposed on each bit body, and an oil jack attached to the drill pipe. It becomes more,
The rod of the oil jack is expanded and contracted, and the expanding tool is rotated using guide pins and arcuate guide grooves provided on the expanding tool and the bit body as guides, thereby expanding outward or contracting inward. Reverse circulation drill.