METHOD FOR FORMING PIPE BILLET Russian patent published in 1994 - IPC

FIELD: plastic metal working. SUBSTANCE: to improve the quality of pipes by eliminating corrugations on strip edges when pipe billet is bent in passes of pipe mill, the strips are bent with a gradual increase of billet curvature in each next pass and the pipe curvature in each pass is set in accordance with design formula depending on strip width, stand-to-stand distance and radiuses on bottom of upper and lower rolls in compliance with a preset law. EFFECT: preventing formation of corrugations on edges of metal strip used to make pipe billet. 2 dwg, 2 tbl