| 摘要 |
PROBLEM TO BE SOLVED: To stably form a narrow groove in a metallic plate by forming a rough approximately U-sectioned groove having wider width than desired groove width and then forming a groove having the desired width by reducing the width of the rough groove, on the metallic plate. SOLUTION: As a raw material, a metallic plate 2 whose end portion is in advance pressed into an L-shaped section is used. With a rough die and a rough punch, rough groove 5 is formed at the end portion of the metallic plate 2. The rough groove 5 has groove width V and is a U-shaped groove having a high side wall 51 and a low side wall 52. A main body 21 is clamped with a cushion 71 and a die 72, and a corner 711 of the cushion 72 is brought into contact with the corner, at which at rough groove 5 and the main body 21 are connected. A control surface 721 of the die 72 is faced, at desired groove width W, to the inner surface of the high side wall 51. While the spacing between the punch 73 and the cushion 71 is maintained at the desired outer surface width of the groove 1, the punch 73 is moved in parallel from the base portion of the high side wall 51 toward the top end to form the groove 1 having the desired groove width W.
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