| 摘要 |
PURPOSE:To form better and stronger and to improve a durability by inserting a plied sheet between a drawing punch and a dies hole, forming a projected caulking part by a downward pressure of the punch and crushing around the drawing by a caulking punch. CONSTITUTION:The plied sheets 4, 5 are inserted between the drawing punch 1 and the bottomed dies hole 2. The projected caulking parts 4a, 4b are formed by the downward pressure of descending punch 1. On that occasion, buildup parts 4b, 5b are generated around the punch 1, but these buildup parts 4b, 5b are pressed down by descending the punch 1 to flatten. The side wall of the caulking part bites into the outer side (a) to strengthen the caulking. Further, as a vertical groove is provided on a peripheral wall 3a of the dies hole 2 to be bitten in by the plied sheets 4, 5, a rotation of the plied part is checked to prevent a phase shift and if small projection parts are provided around the dies hole 2, the caulking part becomes better and stronger.
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