| 摘要 |
<p>A gun drill with a single cutting edge exhibiting high cutting efficiency in which strict positional precision is not required when a cutting edge chip is brazed as a cutting edge, the cutting head can be manufactured easily and the cutting edge itself has an easy-to-machine profile. The cutting edge (5) is arranged such that the inner end (51a) of the edge (51) is spaced apart from the central axis (O) of a head to form a non-cutting zone (Z) in the vicinity of the central axis (O), the side face (52) of the cutting edge on the inner end (51a) side is a surface inclining from the inner end (51a) to the central axis (O) side of the head, and the non-cutting core (C) of a material (W) to be cut occurring in the non-cutting zone (Z) during cutting work is pushed by the inclining side face (52) of the cutting edge and broken off.</p> |
