| 摘要 |
PROBLEM TO BE SOLVED: To perform working of drilling a prepared hole in a work and forming a female thread in the prepared hole at one step. SOLUTION: A tap portion 2 is provided between a drill body 1 with a cutting edge 1a formed at an end and a grip portion 3 for holding by a drilling device. The tap portion is arranged to be coaxial with an axis C of the drill body 1, and an outside diameter of the drill body 1 is a prepared-hole diameter for the tap portion. The prepared hole H is drilled in the work W by the drill body 1, and a chamfer 2a of the tap portion 2 directly bites the prepared hole. COPYRIGHT: (C)2003,JPO
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