DIE SET FOR FORMING TUBULAR BLANKS Russian patent published in 2001 - IPC

FIELD: plastic metal working, particularly forming parts of tubular blanks. SUBSTANCE: die set includes punch and lower die arranged in rigid casing and designed for placing in it tubular blank. Sleeve with loose working medium is arranged inside blank. Elastic piston is placed between punch and loose working medium. Sleeve has opening in zone for deforming tubular blank. Arrangement of sleeve with loose working medium inside tubular blank with minimum gap between their lateral walls eliminates friction between said walls and prevents pressure of working medium upon walls of blank in non-deformed zone. EFFECT: improved design. 2 dwg _