| 摘要 |
PROBLEM TO BE SOLVED: To provide a drilling apparatus which carries out excavation of sediment by arranging bits on a front end of a hollow cylindrical casing, and rotating the bits together with the casing, and facilitates assembly thereof. SOLUTION: The drilling apparatus is formed of: the cylindrical casing 2; an outer bit 3 which is connected to one end of the casing 2, formed like a cylinder, functions to excavate the sediment via the tip thereof, and has a diameter-contracted portion 15 on the rear thereof; an inner bit 4 loosely fitted in the outer bit 3 and formed like a closed end cylinder; through holes 16, 17 radially penetrated into the diameter-contacted portion 15 and the inner bit 4; a connection block 10 inserted into the through holes 16, 17 to fix the bits to each other; a block retaining member 12 arranged in the inner bit 4 in a manner longitudinally slidable in a predetermined range, for inhibiting inward movement of the connection block 10 when located on the front and canceling the inhibition of the movement when located on the rear; a spring 18 arranged on the connection block 10 in a manner protruding in a radially outward direction; a block retaining collar 19 arranged on the periphery of the diameter-contracted portion 15, for pressing the spring 18 in a contracting direction; and a recovering member 6 for pulling the block retaining member 12 rearward to cancel fixture between the bits, and recovering the inner bit 4. COPYRIGHT: (C)2008,JPO&INPIT
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