| 摘要 |
PROBLEM TO BE SOLVED: To perform a processing having no flashes or an underfill without damaging a die by restraining a solid column, which is a processing material, with a fixed die, a knockout pin, an outer punch and a center punch, and making the outer punch face pressure larger than that of the center punch for performing a pressurization. SOLUTION: A processing material 1 is inserted into a hole die being constituted with a fixed die 2 and a knockout pin 4 and, mounted on the knockout pin 4. Then, an outer punch 5 and a center punch 6 are lowered so as to restrain the processing material 1. Thereafter, the processing material 1 is pressurized with the outer punch 5 and the center punch 6. In this case, a face pressure of the outer punch 5 is made larger than that of the center punch 6. When a swaging part of the processing material 1 is completely formed, an excessive volume or a short volume of the processing material 1 is absorbed by a backward or a forward movement of the center punch 6. In a case where ratio between a length and a diameter of the processing material 1 exceeds 2.25, it is preferable that a portion equivalent to the swaging part is preliminary formed. |
