Factors of Affecting Large Diameter Double-sided Submerged Arc Welding Steel Pipe Mechanical Expandi

There are many factors that affect the quality of large diameter double-sided submerged arc welding steel pipe(dsaw steel pipe). The key factors that directly relate to the quality of diameter forming are the expansion ratio, the amount of axial overlap, the number of segments and the rounded corners, The friction and lubrication between the block and the inner wall of the steel pipe, the shape error of the steel pipe, the expanding speed and the straightening setting of the expanding machine.
(1) When the enlarging rate is small, the roundness error of the steel pipe decreases with the enlarging rate, but when the enlarging rate increases to a certain value, with the enlargement rate increasing, The roundness error of the steel pipe will increase greatly. In the actual production, the expansion ratio 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 diameter-enlarging efficiency of the full-length expansion of the steel tube. The zero overlap amount and the small positive overlap amount are beneficial to alleviate the "bamboo" Improve the diameter expansion efficiency.
(3) Increasing the number of segments, increasing the speed of expansion, increasing friction and lubrication between the segments and the inner wall of the steel pipe, and reducing the friction coefficient of the contact zone are all conducive to the uniform distribution of the wall stress.
(4) The diameter of the pipe to improve the roundness effect is obvious. After the expansion, the roundness error of steel pipe becomes very small.