Deformation mechanism analysis of three-roller continuous and synchronous calibration process of straightness and roundness for LSAW pipes

The continuous and synchronous calibration process for straightness and roundness of LSAW (longitudinally submerged arc welding, LSAW) pipes with three rollers is a bidirectional reciprocating bending process. It includes both axial and circumferential directions. It is particularly important to reveal the deformation mechanism, which provides theoretical support for the calibration process to be applied to actual production. Based on this, through the combination of references, theoretical analysis and numerical simulation, the deformation mechanism is analyzed in this paper. The whole deformation process of pipe is modeled and then numerically simulated with FEM software of ABAQUS. The results show that reciprocating bending can eliminate the difference of initial curvature, so that the axial curvature and circumferential curvature are unified to the same direction and value, respectively. The calibration process of LSAW pipes is realized by the synergy between the axial reciprocating bending straightening process and the circumferential reciprocating bending rounding process. The simulation and experimental results support the theoretical results, and the deformation is mainly caused by axial stress and circumferential stress.