| 摘要 |
PURPOSE:To maintain the diameter of the mating hole of a press die to a correct size and to prevent the surface shear droop around the hole by heating the part of the press die around the mating hole to harden said part while a pin is held inserted into the mating hole then removing the pin from the mating hole. CONSTITUTION:A pin 8 is inserted into a press die 7 having a mating hole and the part around a mating hole 5 is hardened in this state. The pin is made to the diameter 8 at which a required diameter is maintained in the hole 5 after the part around the hole 5 is hardened and to the diameter at which a suitable clearance is formed between the inside wall of the hole 5 and the pin while the pin is held inserted into the hole. The clearance refers to the clearance of the extent to suppress excessive shrinkage of the hole 5 in the hardening process and to permit removal of the pin 8 after hardening. More specifically, the clearance is determined by the degree of the shrinkage in the hardening process of the mating hole 7 of the die 7 to be used. In the figure, 6 denotes the surface shear droop around the hole 5. |
