Development of Effective Roll-Pass Designs for Production of Longitudinally Welded Pipes of Small and Medium Diameters

The advantages and disadvantages of single-radius roll-pass design for the production of longitudinally welded pipes of small (5–114 mm) and medium (114–480 mm) diameters in an electric-resistance welding pipe mill are discussed. Double-radius (MISiS) roll-pass design and roll-pass designs for forming the workpiece periphery with constant parameters in all the stands of the forming mill are presented. For these roll-pass designs, forming “flowers” are drawn, and the trajectories for fixed fibers of the workpiece and the longitudinal-strain fields are determined for a D_t × S_t ∅ 50 × 1.5 mm tube. The forming patterns are compared, and the effectiveness of the forming process is assessed. It is established that all the forming patterns produce workpieces of high quality; however, to improve the process, it is advisable to apply forming patterns with a descending middle fiber in the open-pass section of TESA 30-50 electric-resistance welding pipe mill.