JPS6147271B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is fixed to the cutting edge of drilling equipment for oil wells, geothermal extraction wells, etc. or tunnel drilling equipment, especially the tip of a drill pipe, and is inserted into the ground to make a hole. This invention relates to a drill bit used in a drilling rig with a structure that allows it to be pulled up.

BACKGROUND OF THE INVENTION Most common drilling equipment uses a bit that can be fixed to the tip of a drill pipe to rotate the drill pipe from above the ground surface and push it into the ground to drill holes. The bit of this drilling equipment cuts the entire bottom of the hole in one continuous plane, that is, it drills while cutting the bottom of the hole into a flat surface.

In the present invention, since the bit is rotated around the center line of the drill pipe, the circumferential speed of the cutter at the center of the hole is smaller than the circumferential speed at the periphery, so when cutting the hole bottom flat, the drilling speed is Focusing on the point that the drilling speed at the center of the hole is restricted, if the peripheral part where the circumferential speed is high is excavated in a circular manner first, the central part that remains in the shape of a core will be easily fractured because it protrudes toward the center. It was discovered that the excavation speed could be improved.

The present invention applies this technical concept to a bit that performs excavation using high-pressure water jetted from a nozzle.

The basic structure of the bit of the present invention will be explained with reference to the drawings. A cylindrical base 1 with a hollow interior 2 and an open end is provided with a screw 1' on the outer periphery of one end. It is designed so that it can be connected to the inside 2, and the pressurized water sent through the inside of the drill pipe is communicated with the inside 2. The other end surface of the base 1 is closed, and the closed other end surface 3 has a plurality of central nozzle holes 4.
is provided so as to communicate from the inside 2 of the base 1 to the outside.

A plurality of branch portions 5 are provided on the side surface of the base 1 so as to extend forward from the other end surface 3 of the base 1 integrally with the base 1 . The branch part 5 has a hollow interior 6 and communicates with the interior 2 of the base 1, and a closed end surface 7 of the branch part 5 has a plurality of outer peripheral nozzle holes 8 communicating from the interior 6 to the outside. It is provided.

Two or three of these branch-shaped parts 5 are provided symmetrically as a set with respect to the center line O connecting one end of the base and the center of the other end surface 3, and are perpendicular to the center line O in front of the other end surface 3. The end face 7 of the branch-like part 5 is located on the same plane as the above.

This bit is connected to the tip of the drill pipe with a screw provided with the outer periphery of one end of the base 1, and the drill pipe is rotated and pushed toward the ground. At the same time, high-pressure water such as 1500 kg/cm ² Drilling is performed by supplying the liquid into the bit and injecting it from the central nozzle hole 4 and the outer peripheral nozzle hole 8. High-pressure water injected from the central nozzle hole 4 and the outer nozzle hole 8 penetrates into minute cracks in the rock, crushing the rock, and drilling is performed. At this time, as the branch part 5 is rotated around the center line O, the high-pressure water injected from the outer nozzle hole 8 of the branch part 5 uniformly spreads over the outer periphery of the hole bottom 9 shown by the chain line to other parts. An annular groove is excavated in advance of the excavation. The part close to the center line O remains in the form of a core, but since it is an independent protrusion, it is easy to break and is easily crushed by the high-pressure water jetted from the central nozzle hole 4. The excavation speed can be improved compared to when excavating the same surface on both the outer periphery and the center.

In the above description, the basic form is explained in which a set of two or three branches 5 of the same length is provided. Both the distance between the intersection of the perpendicular line and the center line and the other end surface 3 of the base 1 and the distance from the center line O to the end of the branch portion 5 having the closed end surface 7 were gradually increased. If a plurality of sets of branch-like parts 5 are provided, and the two sets are arranged from the set with the largest distance to the set with the smallest distance as they move toward the other end surface 3 of the base 1, the bottom of the excavated hole by this bit will have a central part. Since it has a core-like or mountain-like protruding shape with stepped sides and is sequentially cut from the periphery to the center, the excavation speed can be higher than before, similar to the basic shape.

In the present invention, the reason why each set of branch parts is provided centrally symmetrically is to obtain a balance to prevent vibration during rotation, and even if the nozzle holes are uniformly provided in each branch part, it will not be asymmetrical. If this is done, a side with a large injection reaction force will be generated in a part of the circumference, and this side will come into pressure contact with the hole wall and not only act as a brake against the rotational force applied from the ground, but also prevent one-sided wear on the bit and drill pipe. This is because it occurs and is not desirable.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view of the basic form of an underground drilling drill bit according to the present invention. DESCRIPTION OF SYMBOLS 1... Base, 1'... Threaded part, 2... Inside, 3... Other end surface, 4... Central nozzle hole, 5... Branch-like part, 6... Inside,
7...Closed end face, 8...Outer nozzle hole, 9...Bottom of the hole.

Claims (1)

[Claims] 1. A base having one end formed to be attachable to the drill pipe and having a hollow interior, and a closed end face of the base so as to communicate from the inside of the base to the outside. a central nozzle hole, a plurality of hollow branch-like parts extending from the side of the base to the front from the other end face of the base, integrally formed with the base and communicating with the inside of the base, and branches formed on the closed end face of the branch-like part. and a peripheral nozzle hole formed to communicate from the inside of the shaped part to the outside, and the branched part is arranged symmetrically with respect to a center line passing through the centers of one end and the other end of the base and on the same plane orthogonal to the center line. An underground drilling drill bit comprising at least one set of a plurality of bits each formed with a closed end face. 2. Distance between the point where the perpendicular drawn from the closed end surface of the branch to the center line intersects with the center line and the other end surface of the base, and the end with the closed end surface of the branch from the center line. The base includes a plurality of sets of branch parts whose distances from each other are sequentially increased, and the branch parts of each set are arranged in order from the one with the smallest distance to the one with the largest distance from the other end of the base. An underground drilling drill bit according to claim 1.