| 摘要 |
PROBLEM TO BE SOLVED: To develop a sufficient curved driving performance without impairing a straight driving performance. SOLUTION: This drilling device comprises a plurality of bits 3 arranged parallel with each other at the tip of a hole drilling shaft 1 and a means for rotating driving these bits 3. A part of the plurality of bits 3 is formed so as to be movable relative to the other bits 3 so that a force received by the tip of the hole drilling shaft 1 can be varied and the direction of drilling can be changed by the movement of the part of the bits 3. COPYRIGHT: (C)2006,JPO&NCIPI
|
