| 摘要 |
PROBLEM TO BE SOLVED: To provide a drilling tool used in tunnel excavation work, foundation construction work, and reinforcement construction work and capable of withstanding the use sufficiently even if a casing pipe for preventing collapse of a drilled wall is made of synthetic resin and drilling a hole in even a hard rock-bed. SOLUTION: This hole drilling tool 11 has a rod 21 for transmitting power for drilling a hole and a hole drilling bit member 31 provided at a tip of the rod 21 to drill the hole. A cylindrical tip sleeve 41 attached to a tip of the casing pipe 51 surrounding an outer peripheral side of the rod 21 is connected with a rear part of the hole drilling bit member 31. Recessed grooves 42, 67 are provided on respective opposing faces of the hole drilling bit member 31 and the tip sleeve 41, respectively. A plurality of spherical bodies 68 are stored in these grooves 42, 67 to roll. The drilling bit member 31 and the tip sleeve 41 are mutually connected to rotate relatively and buffer in order to reduce the load working on the casing pipe 51 when drilling the hole. COPYRIGHT: (C)2008,JPO&INPIT
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