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1. (WO2018030464) EXCAVATING TOOL

Pub. No.:    WO/2018/030464    International Application No.:    PCT/JP2017/028924
Publication Date: Fri Feb 16 00:59:59 CET 2018 International Filing Date: Thu Aug 10 01:59:59 CEST 2017
IPC: E21B 10/36
E21B 10/627
Applicants: MITSUBISHI MATERIALS CORPORATION
三菱マテリアル株式会社
Inventors: NAKAMURA Kazuyoshi
中村 和由
TOMITA Yasutaka
富田 泰隆
Title: EXCAVATING TOOL
Abstract:
This excavating tool has: a casing pipe (1) centered around an axial line (O); a ring bit (2) rotatably engaged with and attached to the tip portion of the casing pipe; and a pilot bit (3) inserted into the inner circumferential portion of the ring bit (2) and receiving torque around the axial line (O) and a striking force toward the tip side. A plurality of protrusion sections (7A-7C) are formed at intervals on the outer circumferential portion of the pilot bit (3). In addition, in the inner circumferential portion of the ring bit (2), recessed grooves (5), through which the protrusion sections (7A, 7B) can be inserted from the rear end side thereof, and receiving grooves (6), which extend from the recessed grooves (5) in the rotating direction during boring, are formed. On the protrusion section (7A), a torque transmitting face (7a) is formed, and in a receiving groove (6A), a torque transmitted face (6a), which can be brought into contact with the torque transmitting face (7a), is formed. On the two or more protrusion sections (7B, 7C), striking force transmitting faces (7b) are respectively formed, and the striking force transmitting faces (7b) are spaced apart from each other in the direction of the axial line (O). In the ring bit (2), two or more striking force transmitted faces (6b), which can be brought into contact with the striking force transmitting faces (7b), are formed at equal intervals with the striking force transmitting faces (7b).