To form a crest metallic sheet without developing slipping mark at the time of forming by using a punch having a crest projecting part and one pair of movable dies which are displaced from the horizontal state to the V-shape by pressing with the crest projecting part.
The metallic sheet is laid on a metallic sheet holding part 4B of a die 3. The punch 1 is lowered and the projecting end 2A of the crest projecting part 2 is abutted on the metallic sheet. Further, at the time of lowering the punch 1, the projecting end 2A of the crest projecting part 2 is pushed to the metallic sheet and a push-up table 10 holding the facing part of the movable dies 6A, 6B is displaced downward against the pushing force of a coil spring 8. At the time of progressing the lowering of the punch 1, the inclination of the movable dies 6A, 6B becomes large, and each leg part of the metallic sheet which starts bending as V-shape, starts bending as the reverse V-shape while using the projecting end 2A, the end part (c) of the movable dies 6A, 6B and shoulder part 1B as the supporting point. At the time of lowering the lowermost position of the punch 1, the flattening part (b) of the movable dies 6A, 6B becomes parallel with the flat surface part 1A of the punch 1. In this result, the crest part and the flattened bottom part are formed with a bending part in the metallic sheet.
ONODERA MINORU
HASHIMOTO JIRO
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