| 摘要 |
PROBLEM TO BE SOLVED: To provide a ground drilling device capable of two functions of a percussion function and a vibration function without making device large and automatically switching over in accordance with the ground condition for drilling objects. SOLUTION: The bedrock drilling device is formed to be freely movable in the axial direction in a case 2 and provided with a hammer sub 3 having a large diameter part 12 at the middle, a hammering mechanism 8 hammering the rear end of the hammer sub, an elastic member 19 provided at the outer periphery of the hammer sub 3 at the forwarder side than the large diameter part 12, and an urging member 21 provided at the periphery of the hammer sub 3 protruding from the case 2 and brought at a position where the elastic member 19 can be compression-deformed by the large diameter part 12 by urging the hammer sub forward. COPYRIGHT: (C)2005,JPO&NCIPI
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