BUILTUP PUNCH FOR STRETCHING ELONGATED ENVELOPE Russian patent published in 1998 - IPC

FIELD: plastic metal working, namely forming elongated large-size complex-shape envelopes of sheet blanks, possibly in aerospace, ship building and other industry branches. SUBSTANCE: punch is made of sections with inner rigidity rib mutually joined along their cross and longitudinal butts passing on inner rigidity rib and it has respectively dent and recess mutually joined by fastening members. Mutually spaced cross butts are arranged at both sides of longitudinal butt. EFFECT: elimination of high-rigidity supporting frame, lowered labor consumption, reduced metal consumption of punch and its separate sections, simplified design, possibility of reassembling builtup punch of unitized set of sections for making different shape parts. 3 dwg