| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for forming a screw seat capable of preventing swelling of an excess metal at the time of shaping the screw seat and also removing a burr at the time of shaping the screw seat. SOLUTION: The screw seat is formed following a punching process and a shaping process. In the punching process, a solid wall in a punch region and its periphery is pushed in to a die hole 19 by a thickness removing protrusion 14 disposed in a first punch 10. A through hole 2 is formed by shearing the punch region in this state at a shearing part 15. Furthermore, a front stage screw seat 4 is formed by shaping the through hole 2 at a front stage shaping part 16, and a ring part 3 is formed at a receiving hole 20 at the upper end of a die hole 19. The ring part 3 is crushed and pushed back to the through hole 2 side in the shaping process. The front stage screw seat 4 and the ring part 3 plastically deformed are simultaneously shaped and made to the screw seat in the shaping part of a second punch. The swelling of the excess thickness is prevented by minimizing the amount of the solid wall removed by pushing in the shaping part. The burr is absorbed and removed at the time of shaping process. COPYRIGHT: (C)2004,JPO
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