| 摘要 |
PROBLEM TO BE SOLVED: To provide a boring drill capable of machining a twisting groove with a fixed twisting angle to a drill body even if the drill body is a stepped drill having a small diameter portion and a large diameter portion, and efficiently boring a stepped hole; and a method of machining the boring drill. SOLUTION: In the stepped boring drill having the small diameter portion 12 at a distal end portion of the drill body 1 and the large diameter portion 13 at a proximal end portion, the spiral twisting grooves 12a, 13a having the same twisting angles are continuously formed on the large diameter portion 13 and the small diameter portion 12 of the drill body 11. COPYRIGHT: (C)2010,JPO&INPIT |
