METHOD OF SHAPING TUBULAR BLANK Russian patent published in 1994 - IPC

FIELD: production of welded tubes. SUBSTANCE: in order to enhance quality of tubes by elimination of corrugations on edges of metallic belts at bending a tube blank in roll passes of tube forming mill method comprises steps of bending the belt with smooth increase of a curvature of the blank of the tube in each subsequent roll pass; setting a value of the tube blank curvature in each roll pass according to a shaping angle, being determined in dependance upon a number of the roll pass in accordance with a given law. Formation of the welded straight-seam tube in roll passes with above mentioned formation radius values allows to produce the welded tube without depressions and other defects of the welded seam. EFFECT: enhanced quality of welded formed tubes. 1 cl, 2 dwg