| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a drill in which burrs can be prevented from being generated on an outlet peripheral edge part of a through-hole which is formed in drilling and from which a drill blade comes out. Ž<P>SOLUTION: The drill 1 includes a shank, a drill body 10 continuing to the shank, a preceding blade 14 formed on a tip end of the drill body 10, and a finishing blade 17 formed in a shank side of the preceding blade 14 in the drill body 10 and in an outer peripheral side of the preceding blade 14. A workpiece is cut by the preceding blade 14 and the finishing blade 17. In cutting the workpiece, feed speed of the drill body 10 when the preceding blade 14 penetrates through the workpiece is set faster than that of the drill body 10 when the finishing blade 17 penetrates through the workpiece and set to the speed to arrow chipping to be generated on the workpiece. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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