| 摘要 |
PROBLEM TO BE SOLVED: To provide a drill for reducing push-out of burrs at the time of passing through a hole by guiding cut chips having simple structures into a drill groove, smoothly performing a cutting, and reducing the push-out to the front of a drill at the time of the cutting, and suppressing generation of burrs at the time of drilling, even when a difference in level exists on a machined rear surface and a part of the hole covers the difference in level. SOLUTION: In this drill, a twist angle of a twist drill groove main body is≥15°and≤35°, a cutting edge for suppressing burrs is provided at a distal end of the drill, a twist angle of the cutting edge for suppressing burrs is≥0°and≤10°in front view, and the length of the cutting edge for suppressing burrs is made≥0.1 times and≤0.5 times of the diameter of the drill from a cutting edge ridge toward a base end side. COPYRIGHT: (C)2006,JPO&NCIPI
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