| 摘要 |
A pressing apparatus 30 performs plastic working by pressing a punch 36 into a metal plate 31. The pressing apparatus 30 includes a rough surface part 47 that is formed at a front-end-side area of an outer surface of the punch 36, the level of surface roughness of the rough surface part 47 being greater than that of other area part, and a smooth surface part 48 that is formed at a base-end-side area that is located at a relatively base-end side in comparison with the area of the rough surface part 47, the smooth surface part 48 being smoother than the rough surface part 47. The punch is inserted up to a point where the rough part goes beyond one surface of the metal plate that is opposite to the other surface thereof that is provided at a side at which the insertion of the punch into the metal plate is started. By this means, the formation of a bump on the punched-side surface is prevented.
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