There have been numerous studies of corrugation in welded-pipe production, and corresponding calculation methods have been developed [1-3]. Existing methods assume that, when a blank with a rectilinear central fiber is shaped by loading, the peripheral sections of the edges extend longitudinally in the plastic zone and then, after removal of the external forces, the blank is unloaded, which may lead to compression of the plastically deformed fibers and corrugation. The extent of the corrugated sections is determined by the parameters of the deformation source, the curvature of the blank over the length of the deformation source, and the trajectory of the fibers in the peripheral sections of the blank. We know that corrugations are formed both in continuous shaping of small- and moderate-diameter pipe and in discontinuous manufacture of large-diameter pipe (Fig. 1).
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