Continuous Shaping of Welded Straight-Seam Pipe in the Open Stands of a Pipe-Welding System

Physical and computer modeling of continuous shaping is described. In the experiments, strip workpieces undergo continuous shaping on a TESA 10-50 pipe-electrowelding system for pipe of diameter 50 mm with wall thickness 1 mm. The pipe blanks are shaped in horizontal and vertical shaping stands, with estimation of the geometric parameters. Single-radius grooves are used on the rollers. The forces affecting the geometry of the pipe blank are determined. Analysis of the workpiece geometry reveals defects of corrugation type on its right edge between the second edging stand and the third shaping stand. A similar defect appears on the left edge in the section between the third shaping stand and third edging stand. To eliminate defects in the shaping section, the horizontal stands are adjusted so that the forces at the drives are the same. Then the relevant forces are again determined: the tractional forces of the drives; the resistance to strip motion in the stands; and the vertical shaping forces. In calculating the forces, the basic parameters are determined by two methods. In the first, the geometric parameters of the pipe blank and the parameters in the bending section are taken into account, with allowance for deformation outside of the contact zone. In the second, the contact interaction of the pipe blank and the shaping tool over the deformation cross section is taken into account. The discrepancy between the calculation results and the experimental data is 8–12%. After correcting the shaping parameters and adjusting the roller grooving, defect-free pipe blanks are shaped. According to comparison of the calculated and experimental trajectories of the edges of the workpiece over the height and width in the stands, the discrepancy is 6–9%. In investigating the geometric parameters of the deformation region, the bending zones with and without contact are taken into account, as well as the springback section. The shaping parameters of the pipe blank are calculated in uniform and roller shaping zones. Analysis of the results shows that shaping of the workpiece corresponds to the assumptions regarding the change in its geometry in roller grooves.