METHOD FOR MANUFACTURING LONGITUDINALLY WELDED PIPES Russian patent published in 1994 - IPC

FIELD: pipes. SUBSTANCE: method involves multipass moulding of a band with variable cross section including flat central section and circular bent peripheral parts in gauges oriented along the moulding axis. The profile forming is made simultaneously with cross displacement of the flat part of the band and tangential displacement of the peripheral section is to provide parallelism of the edge ends of sickle-shaped bands while welding in the intermediate adjacent passes. The compressing force applied to the end surface of the convex edge of the band in m-th pass and to the concave edge - in m+1 pass. The band is moved until its longitudinal axis is aligned with the moulding axis. The bending angle of the band in m-th pass is set. EFFECT: improved quality. 4 dwg