| 摘要 |
PROBLEM TO BE SOLVED: To provide double-pipe type excavating equipment which prevents a ring bit from being accidentally disconnected from an inner bit, even if a percussion force does not act, and which enables the inner bit to be surely disconnected from the ring bit, when the inner bit is recovered. SOLUTION: This double-pipe type excavating equipment comprises: an almost U-shaped force imparting part 90 which is installed so as to protrude to an outer peripheral side in a range except a notched groove 14 of the inner bit 10; an almost annular dead-end part 21 which is installed on the inner peripheral surface of the ring bit 20; a force receiving part 25 which is installed on the rear surface side of the dead-end part 21 and which is protruded to an inner peripheral side; and a rotation restraining part 13 which is installed in the imparting part 90 of the inner bit 10, and into or on which a part of the receiving part 25 of the ring bit 20 intrudes or abuts. Additionally, an almost U-shaped recessed part is integrally formed on the rear surface of a butt part 12 of the restraining part 13. COPYRIGHT: (C)2005,JPO&NCIPI
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