| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent a drill from being partially lost or broken and to make high accuracy attainable in drilling, by suppressing generation of continuous chips without being affected by machining conditions in a drill. <P>SOLUTION: The drill is configured to form a conically shaped blade part 12 in the tip end of a columnar drill body 11. The blade part 12 includes: a plurality of cutting edges 21a, 21b formed with prescribed spaces apart in the circumferential direction; a plurality of flanks 22a, 22b formed rearward in the rotating direction of the cutting edges 21a, 21b; and a plurality of discharge grooves 23a, 23b formed rearward in the rotating direction of each of the flanks 22a, 22b. In each cutting edges 21a, 21b, the shape in the feeding direction is made different from each other. <P>COPYRIGHT: (C)2012,JPO&INPIT |
