# US 2019/0169938 A1 · Drilling tool

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- Number: US 2019/0169938 A1
- Document ID: US20190169938A1
- Status: Published application
- Kind: A1
- Application number: 16/323,855
- Filed: 2017-08-09
- Published: 2019-06-06
- Earliest claimed: 2016-08-09
- Assignees: Mitsubishi Materials Corporation
- Applicants: Mitsubishi Materials Corporation
- Inventors: Kazuyoshi Nakamura; Yasutaka Tomita
- Web page: https://patentgrep.com/patent/US20190169938A1

## CPC

- E21B 10/40: with leading portion
- E21B 10/26: Drill bits with leading portion, i.e. drill bits with a pilot cutter; Drill bits for enlarging the borehole, e.g. reamers (percussion drill bits with leading portion E21B10/40)
- E21B 10/36: Percussion drill bits ({with helical conveying portion E21B10/445;} characterised by wear resisting parts E21B10/46)
- E21B 10/43: characterised by the arrangement of teeth or other cutting elements
- E21B 10/62: characterised by parts, e.g. cutting elements, which are detachable or adjustable (E21B10/64 takes precedence; for roller bits E21B10/20; for augers E21B10/44)
- E21B 10/627: with plural detachable cutting elements
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

A drilling tool has: a casing pipe in a circular tubular shape; a cylindrical or annular ring bit rotatably fitted to a tip portion of the casing pipe; and a pilot bit inserted into an inner circumference of the ring bit for a striking force to be exerted to toward a tip end side, wherein the ring bit is engaged with and fitted to the casing pipe, projections are formed on an outer circumferential portion of the pilot bit, a recessed trench, and a housing trench, are formed in the inner circumferential part of the ring bit, a torque transmitting surface is formed in the projection, a torque receiving surface capable of abutting the torque transmitting surface is formed in the housing trench, striking force transmitting surfaces are formed in projections, and striking force receiving surfaces capable of abutting the striking force transmitting surfaces are formed in the ring bit.

## Claims

### Claim 1

A drilling tool comprising:
a casing pipe having a circular tubular shape about an axis;
a cylindrical or annular ring bit which is rotatably fitted to a tip portion of the casing pipe; and
a pilot bit which is inserted into an inner circumferential part of the ring bit and configured for a striking force to be exerted to toward a tip end side of an axial direction while being rotated about the axis,
wherein the ring bit is engaged with and fitted to the casing pipe on the tip end side in the axial direction,
a plurality of projections are formed along the axial direction on an outer circumferential portion of the pilot bit with an interval therebetween,
a recessed trench, which is configured for one of the projections to be inserted from a posterior end side in the axial direction and extends in the axial direction, and a housing trench, which extends from the recessed trench in a rotation direction of the pilot bit in drilling and is configured to house at least one of the projections, are formed in the inner circumferential part of the ring bit,
a torque transmitting surface, which is configured to face the rotation direction, is formed in the at least one of the projections,
a torque receiving surface, which is configured to face an opposite side to the rotation direction and is capable of abutting the torque transmitting surface, is formed in the housing trench,
striking force transmitting surfaces, which are configured to face the tip end side in the axial direction, are formed in two or more of the plurality of projections in the axial direction with an interval therebetween, and
two or more striking force receiving surfaces, which are configured to face the posterior end side in the axial direction and are capable of abutting the striking force transmitting surfaces respectively, are formed in the ring bit with an interval equal to the interval of the striking force transmitting surfaces in the axial direction.

### Claim 2 (depends on 1)

The drilling tool according to claim 1,
wherein the striking force transmitting surfaces and the striking force receiving surfaces are inclined to the posterior end side in the axial direction as being extended toward an outer circumferential side with respect to the axis.

### Claim 3 (depends on 1)

The drilling tool according to claim 1, wherein, in two protrusions adjacent to each other in the axial direction among the protrusions, a length of one protrusion in a circumferential direction is shorter than a length of other protrusion in the circumferential direction, the one protrusion being one of two protrusions on the tip end side in the axial direction and the other protrusion being other of two protrusion on the posterior side in the axial direction.

### Claim 4 (depends on 2)

The drilling tool according to claim 2, wherein, in two protrusions adjacent to each other in the axial direction among the protrusions, a length of one protrusion in a circumferential direction is shorter than a length of other protrusion in the circumferential direction, the one protrusion being one of two protrusions on the tip end side in the axial direction and the other protrusion being other of two protrusion on the posterior side in the axial direction.