| 摘要 |
PROBLEM TO BE SOLVED: To provide a precision forging technology for precisely punching a hole in a forging having a thin-walled part in a circumferential wall part of the hole by the hot forging. SOLUTION: In a punching step after a closed die forging step, outer circumferential edge parts corresponding to at least thin-walled parts b of the circumferential wall part of the hole are punched by auxiliary outer circumference punches 2 synchronously with the punching of a predetermined hole a' by a hole punch 1 in a closed die forging C. A hole a' is punched by the hole punch 1 while the outer circumferential edge parts corresponding to the thin-walled parts b of the circumferential wall part of the hole a' is supported and restricted by the auxiliary outer circumferential punches 2. Distortion when punching the hole a' can be effectively prevented. COPYRIGHT: (C)2003,JPO
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