Patent ID: 6658908
Filing Date: 2003-12-09
Classification: B21D,Y10T

Abstract:
A punch for forming a hole in a hydroformed part in a hydroforming process wherein a hydroforming pressure used to form the part is maintained in the part for the formation of a hole in the part with said punch, said punch comprising a piercing end portion adapted to pierce an opening in the part, a roll-forming portion adapted to enter said opening following said piercing end portion, a hole-finishing portion adapted to fully enter said opening following said roll-forming portion to complete the finishing of a hole required in the part, and said roll-forming portion extending only partially about said punch and having a roll-forming surface adapted on entering said opening to form a rolled edge portion in said part extending only partially about said punch whereby said rolled edge portion forces sealing contact between the part and said punch sufficient to maintain the hydroforming pressure in the part and thereby prevent collapse of the part as said roll-forming portion enters said opening and then when said hole-finishing portion enters said opening to complete the formation of the hole.