| 摘要 |
PROBLEM TO BE SOLVED: To provide a bending hole correction drilling method for detecting bending hole in real time to improve work efficiency. SOLUTION: A second excavation shaft 62 has an upper fixed shaft part 62F, a rotary shaft part 62R connected with a part below the fixed shaft part 62F rotatably, and a detector 40 provided in the fixed shaft part 62F. A first excavation shaft 61 is constituted in such a way that substantially the whole excavation shaft 61 including all the parts from its upper part to its lower part rotates. The first excavation shaft 61 is provided with a rotary driving mechanism 7 for giving rotary driving force to transmit rotation of the first excavation shaft 61 to a rotary shaft part 62R of the second excavation shaft 62. A transmission mechanism for rotating the rotary shaft part 62R is provided. COPYRIGHT: (C)2008,JPO&INPIT
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