METHOD FOR MAKING TUBES WITH HELICAL CORRUGATIONS Russian patent published in 2000 - IPC

FIELD: plastic metal working. SUBSTANCE: method comprises steps of placing tube onto mandrel; forming helical corrugations by means of rollers arranged around tube and inclined relative to its lengthwise axis; applying torque relative to lengthwise axis of tube onto portion of tube approaching to rollers; applying axial effort to portion of mandrel removing from rollers and by means of mandrel - to portion of tube approaching to rollers. Torque may be applied in direction coinciding with rotation sign of tube caused by its engagement with rollers. Additional torque is applied to tube portion removing from rollers. EFFECT: enhanced efficiency. 3 cl, 1 dwg