| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a tap capable of improving male screw pulling resistance by reducing failure of a female screw, a method for forming a female screw using the tap, and a female screw. Ž<P>SOLUTION: In this tap including a tool body rotating around an axis and a male screw part 12 provided on an outer periphery of the tool body, a swollen-shaped protrusion 2 is formed at a peak of a thread 20 of the male screw part 12. When the female screw is formed using the tap, a swollen-shaped dent can be formed at a valley part of the female screw. As a result, in the female screw formed by the tap, cracks starting from the valley part can be restrained, so as to improve male screw pulling resistance. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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