PRESS FORMING METHOD

摘要

PURPOSE:To obtain a big drawing depth by increasing the wrinkle pressing force at the initial forming time and by reducing the wrinkle pressing force according to the progress of the punching stroke. CONSTITUTION:A blank 14 is pressed by a wrinkle pressing plate 16 to the die 12 forming the cavity 10 for forming and this blank 14 is subjected to a drawing by pushing it into the cavity 10 with a punch 18. In this case the blank pressing force of the wrinkle pressing plate 16 at the forming start time is made higher than the pressing force corresponding to the intersection of the crack generation limit line at the blank pressing force constant time with the wrinkle generation limit line. While the forming this pressing force is reduced in the state of not intersecting with the crack generation limit line according to the increase in the punch pushing quantity. And it is reduced than the pressing force corresponding to the intersection at the forming completion time.