| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a punching method and a punching device capable of enhancing the fatigue strength by preventing unevenness or cutouts from being formed in a punched end face after the punching. Ž<P>SOLUTION: A punch 11 is used, which has a cutting blade 12 having a side face substantially parallel to the punching direction, a tapered part 13 continuously expanded upwardly from an upper portion of the cutting blade 12, and a sliding part 18 having a side face substantially parallel to the punching direction continuously from an upper portion of the tapered part 13. The punching clearance defined by the formula (1)' is adjusted in advance so that the punching clearance is ≤18%, where h1 denotes the space formed between the side face of the sliding part 18 and the side face of an opening 21, and t denotes the thickness of a metal plate. Punching clearance (%)=h1/t×100 (1)'. Further, when the punch 11 is forcibly passed into the opening in a die 14, a punched end face of an opened hole by the cutting blade is expanded via the tapered part 13, and allowed to slide by the sliding part 18. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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