| 摘要 |
PURPOSE:To perform spot facing of a flat head screw by pressing by forming a prepd. hole by pressing to the shape by which the other excess metal can be absorbed and spot facing the hole with a press. CONSTITUTION:A prepd. hole 8 is opened by a punch 7 for a star-shaped prepd. hole as a means for spot facing without producing excess metal by absorbing the part where the material is extended by pressing. If the material is then pressed by a punch 6 for forming spot facing for a flat head screw, the excess metal part is absorbed although there is seams 9. The generation of the excess metal part is thus prevented. |
