WORKING MEDIUM FOR TRAMSMITTING EFFORTS AT EXPANDING TUBE Russian patent published in 2003 - IPC

FIELD: plastic metal working, namely expansion of tubes with use of rigid lower die. SUBSTANCE: working medium for transmitting efforts at expanding tube on rigid die is in the form of elastic envelope with valve for filling envelope with elastic pellets. Space between pellets is filled with lubricant. EFFECT: enlarged manufacturing possibilities due to using in working medium lubricant of any viscosity, enhanced quality of inner surface of tube due to uniform transmitting of effort. 2 cl, 2 dwg