METHOD FOR SCREW ROLLING OUT OF TUBES Russian patent published in 2000 - IPC

FIELD: production of rolled tubes, namely screw rolled tubes. SUBSTANCE: method comprises steps of reducing hollow blank by means of offset rolls on cylindrical mandrel rotating due to friction forces occurring in deformation zone. In period of filling deformation zone by metal mandrel moves freely in rolling direction. Then in stable-rolling period mandrel is moved along rolling direction by distance equal to difference between length values of mandrel and deformation zone. In period of removing metal from deformation zone, direction of mandrel motion is reversed. Invention is especially suitable for rolling out small-diameter tubes (less than 30 mm) due to lowered possibility of forming trihedral flared portions on their ends. EFFECT: enhanced quality, increased yield of process, enhanced wear resistance of mandrel due to its controlled motion. 3 dwg, 1 ex