There are many factors affecting large-diameter high-quality double-sided submerged arc welded steel pipes (
LSAW steel pipe). The key factors directly related to the formation of the mass diameter are: expansion rate, axial overlap, number of segments and fillets, friction and lubrication between the block and the inner wall of the steel pipe, shape error of the steel pipe, expansion speed and setting of the expander leveler .
(1) When the magnification is small, the roundness error of the steel tube decreases with the decrease of the amplification rate, but when the amplification rate increases to a certain value, the roundness error of the steel tube increases as the expansion rate of the steel tube increases. Big. In actual production, the expansion rate is controlled between 0.8% and 1.5%.
(2) The amount of axial overlap has a certain influence on the uniformity of the longitudinal deformation and the efficiency of the expansion of the overall length of the steel pipe. The zero overlap amount and the small positive overlap amount help to reduce the "bamboo" to increase the diameter expansion efficiency.
(3) Increasing the number of segments, increasing the expansion speed, increasing the friction and lubrication between the segment and the inner wall of the steel pipe, and reducing the friction coefficient in the contact zone are all conducive to the uniform distribution of the wall stress.
(4) Circular tube diameter has obvious effect on improving roundness. After the expansion of the steel pipe, the roundness error becomes smaller
