Spiral seam welded pipe made from metal strip - using continuous adjustment of bending rolls to avoid internal stress in pipe

摘要

Process for controlling bending roll adjustment on spiral seam welding machines used to mfr. welded pipe, where several bending rolls are radially adjusted w.r.t. the pipe axis, each roll being supported by a girder and used in a triangular layout above and below the metal strip, the rolls being followed by an internal or external pipe guide. The novelty is (a) continuous conventional measurement of the load on the first and/or second and/or third bending roll in the three-roll system; (b) continuous measurement of strip thickness and roll adjustment using d = (where d is the bending dia. of the strip; D = final pipe dia.; K2 is a constant; P the measured load; and s is the measured strip thickness). The "spring" in the welded pipe is zero, i.e. when a short ring is cut from the pipe and slit longitudinally the dia. of the ring does not change.