| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a center hole drill capable of carrying out hole cutting processing using the center hole drill under the same hole cutting processing condition as that of a conventional center hole drill, and reducing grinding time and manufacturing the center hole drill at a lower cost by reducing the grinding amount of the flank of a drill part and a counter bore part when manufacturing the center hole drill by reducing the runout amount of the flank arranged at the drill part and the counter bore part. Ž<P>SOLUTION: The runout amount of the flank arranged at the drill part and counter bore part of the center hole drill is determined to an extent that the flank does not interfere with a material to be cut during hole cutting processing using the center hole drill. The runout amount of the flank arranged at the drill part and the counter bore part is not continued to increase from a cutting blade till a heel. The increase of the runout amount of the flank arranged at the drill part and the counter bore part is stopped on a half way between the cutting blade and the heel to generate a fixed value. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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