JPS5842349B2 - Gravel crushing multi-blade bit for reverse construction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multi-blade bit for crushing gravel that is applied to the reverse construction method.

The reverse construction method fills the excavation hole with water and
Using a standpipe to increase water pressure and stabilize the borehole wall, earth and sand are excavated by rotating the drilling drill multi-blade bit inserted into the borehole, and this earth and sand is transferred to the drill rod or multi-blade. This method uses a soil removal pipe connected to the bit to suck water up to the ground and separate soil and sand.It is suitable for driving piles and sheet pile steel pipes because it has low noise, low vibration, and has a wide range of applications. It has been widely used as a tool.

By the way, in this reverse construction method, the drilling drill multi-winged bit rotates in accordance with the diameter of the excavation hole, and the above-mentioned earth removal pipe sucks up earth and sand with a diameter smaller than its inner diameter, so large gravel is generated. Even if the inner diameter of the soil removal pipe is
It is also necessary to crush the soil into small grains.

However, once gravel larger than the inner diameter of the earth removal pipe is generated due to the rotation of the multi-blade bit, the rotation of the multi-blade bit is controlled due to the resistance of the gravel, making it difficult to crush the gravel. In the case of a three-winged bit, if you repeat operations such as rotating it forcibly, the device itself may be damaged, making it impossible to excavate.Also, even if you increase the number of blades and increase the driving force, it will not be possible to excavate. There was a problem in that workability did not improve as much as expected.

This invention was made in view of the above circumstances, and it eliminates the normally provided center leading bit, installs a gravel crushing cup in this position, and inserts the gravel crushed by the multi-winged bit into the hole drilled by this cup. By dropping and pulverizing it finely, the purpose is to ensure that excavation work can be carried out even when large gravel is encountered, and to expand the scope of application of the reverse method to large gravel layers.

Hereinafter, this invention will be explained in detail based on an embodiment shown in the drawings.

The reference numeral 1 in the figure is an earth removal pipe that is rotated by appropriate driving force and moved up and down intermittently. A multi-blade drilling bit 3 is provided at the lower end of the soil removal pipe 1 to sequentially drill holes A of a predetermined size. .

In the present invention, a medium-diameter pre-drilling hole B is set in the lower part of the multi-blade excavation bit 3, which is smaller than the excavation hole A and larger than the expected gravel in the soil. A crushing cup 10 is installed concentrically with the multi-blade bit 3, that is, concentrically with the soil removal pipe 1.
A cup 12 having a predetermined diameter smaller than the rotational diameter and larger than the inner diameter of the soil removal pipe 1 and having an inclined surface 11 narrowed at the top inside, and the cup 12 being concentrically and integrally formed with the soil removal pipe 1. an auxiliary cylinder 13 connected to the auxiliary cylinder 13; a plurality of mounting members 14 for integrally attaching the outer periphery of the auxiliary cylinder 13, the multi-blade excavation bit 3, the cup 1, etc.; 2, and a plurality of large-sized gravel crushing bits 16 with cemented carbide, which are attached to the lower end or outer circumference of the cup 12 and mainly crush large-diameter gravel. and a plurality of cemented carbide-equipped gravel crushing bits 17 that are installed facing downward into the cup 12 and crush the gravel in the cup 12 into smaller pieces.

Here, the material of the tip of each of the bits 16 and 17 is not particularly limited to cemented carbide, and various design changes can be made by changing the shape, mounting position, mounting angle, etc.

Hereinafter, this invention configured as described above will be described in detail.

In FIG. 1, if the earth removal pipe 1 is rotated and moved up and down by the drive device in the illustrated path, the earth and sand button and large gravel C excavated by the excavating multi-blade bit 3 due to the rotational movement are It is forcibly rotated by the wing bit 3, and then when the drilling multi-wing bit 3 moves upward as shown in Fig. 3, it falls from the gap of the bit 3 to the bottom of the drilling hole A, and is further used for crushing gravel. It falls to the bottom of the pre-drill hole B formed by the cup 10 and is collected.

Next, as the gravel crushing cup 10 moves downward, the earth and sand and large gravel C collected in the pre-excavation hole B come into contact with the large gravel crushing bit 16 button and the small gravel crushing bit 17. It is rotated and gradually crushed into small gravel by both crushing bottles (16.17) or by the biting action of large acid C.

These earth and sand and small gravel are pushed out to the vicinity of the communication hole 15 communicating with the earth discharge pipe 1 by the pressure force generated when the gravel crushing cup 10 descends and the water pressure mentioned above, and are pushed out from the communication hole 15. Small-diameter earth and sand and small gravel pass through the communication hole 15 and are sucked up into the earth discharge pipe 1 through the opening 2 and treated.

Further, when the gravel crushing cup 10 moves downward, the inclined surface 11 of the cup 12 comes into contact with earth, sand, and small gravel, thereby collecting them in the center, that is, near the communication hole 15 of the cup 12. It works like this.

Furthermore, the communication hole 1 of the cup 12 is connected to the opening 2 of the earth removal pipe 1.
By making 5 a slightly smaller inner diameter, small gravel that has passed through the communication hole 15 will reliably pass through the opening 2 and be sucked up and discharged by the earth discharge pipe 1.

On the other hand, large gravel C that cannot pass through the communication hole 15 is gradually crushed into smaller pieces by the action of the gravel crushing bit 17 in the cup 12 as the gravel crushing cup 10 moves up and down and rotates. 15, even if the soil layer easily generates large gravel C, the large gravel C will fall into the pre-excavation hole B every time the gravel crushing cup 10 moves up and down, and Ryogra crushing bit 1
6.17 will be broken into small pieces when it descends or rotates.

Among the embodiments shown in FIGS. 1 to 3, an earth removal pipe 1 and an excavating multi-blade bit 3 are integrally attached, and a gravel crushing cup 10 is integrally attached to the multi-blade bit 3. However, the drive shaft that operates the multi-blade excavation bit and the soil removal pipe are separate bodies, so the multi-blade excavation bit has almost no relation to its structure or the number of blades. It is possible to install the gravel crushing cup 10, and it is also easy to apply the present invention to existing multi-wing excavation bits currently in use.

As is clear from the above description, this invention has a gravel crushing cup that crushes gravel into small pieces and excavates a pre-excavation hole at the bottom of the excavation multi-blade bit, and has a diameter larger than the inner diameter of the lower opening of the earth removal pipe. Even if gravel is generated, the large gravel is dropped into the pre-excavation hole, and the gravel crushing bit of the gravel crushing cup gradually crushes it into smaller pieces and sends it through the communication hole to the earth removal pipe. Therefore, the gravel is reliably crushed, the generation of large gravel hardly interferes with excavation work, the reverse method can be applied even to strata that generate large gravel, and the structure of the equipment is simple. This invention has excellent effects such as being able to be applied to existing equipment.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; FIG. 1 is a partially cutaway front view, FIG. 2 is a bottom view of the main part, and FIG. 3 is an explanatory diagram of the excavated state. DESCRIPTION OF SYMBOLS 1...Earth removal pipe, 2...Opening, 3...Drilling multi-blade bit, 10...Gravel crushing cup, 12...Cup, 15...Communication hole, 16...Large Gravel crushing bit for splitting,
17... Gravel crushing bit for small pieces.

Claims (1)

[Claims] 1. Regarding an excavation bit for reverse construction method, which has a leading bit at the lower end of an earth removal pipe having an opening facing downward, and a multi-wing excavation bit arranged near the lower end of the earth earth removal pipe, the preceding bit is A downward bowl-shaped cup formed to a predetermined diameter smaller than the rotational diameter of the multi-blade bit and larger than the inner diameter of the earth removal pipe is attached to the lower end of the earth removal pipe concentrically with the earth removal pipe. A plurality of gravel crushing bits are provided in the cup so as to protrude downward on the outer periphery and inner surface of the cup, respectively, and the cup is further provided with an opening in the earth removal pipe that communicates the inside of the cup with the inside of the earth removal pipe. A gravel crushing multi-blade bit for reverse construction method, characterized in that it is formed into a gravel crushing cup by providing a communication port through which excavated soil and crushed gravel can be fed.