APPARATUS FOR EXPANDING TUBE END PORTIONS Russian patent published in 2001 - IPC

FIELD: forming parts of tubular blanks, possibly tube end expanding. SUBSTANCE: apparatus includes fixed rod on which crosspiece, tube blank and punch are mounted successively. Two sleeves are arranged on tube blank coaxially one after another without gap between their inner surface and outer surface of blank. At applying effort to crosspiece it begins to move along rod together with tube blank and sleeves. At motion tube blank and sleeve nearest to punch are deformed and simultaneously pressure applied from sleeve to blank increases in direction normal relative to its outer surface. It prevents stability loss of tube wall at expansion. EFFECT: improved design. 2 dwg