| 摘要 |
PURPOSE:To prevent leads from being undesirably deformed and shifted by a method wherein a die which can descend together with a punch is used, and a lead frame is formed holding its leads with a regulator which controls the pressure of an air cylinder that applies a force to the die. CONSTITUTION:A die used for down-set forming is composed of a vertically movable die 12 and an air cylinder 11 which gives a force to hold the leads of a lead frame. After the periphery of the lead frame is fixed by a stripper, a punch 5 is made to descend further to hold a lead 9 together with the movable die 12. The punch 5 is made to descend furthermore, but the holding force is kept constant by controlling the air cylinder 11 in pressure with a regulator. After the forming is finished, the punch 5 is made to ascend, and if the movable die 12 ascends together with the punch 5, the lead frame is deformed, so that the air cylinder 11 is so controlled as to be zero in pressure at the bottom dead center. |
