Defect control for the stretch-bending forming of tube profile

Stretch-bending of tube profiles results in defects such as springback, wall thickness reduction, and cross-section distortion, making it more challenging to regulate the forming quality. Most existing research focuses only on a certain defect without comprehensively considering the influence of various factors, making it difficult to control the forming quality of the stretch-bending workpiece as a whole. In this study, the stress and strain of the cross-section of the tube profile were analyzed under the stretch-bending loading path, and expressions for the strain neutral layer and bending moment under stretch-bending loading were derived. An analytical method for the stretch-bending of tube profiles with an inner core tube was established. ABAQUS was used to simulate and analyze the variation in springback, wall thickness reduction, and cross-section distortion after the unloading of tube profiles. The experimental results show that the theoretical analysis of tube profile stretch-bending has high precision, and the inner core polyurethane significantly improves the tube profile stretch-bending formability. Increasing the tension or reducing the bending radius makes wall thickness reduction and cross-section distortion more pronounced but effectively reduces springback. This work provides guidance for improving the quality of stretch-bending of tube profiles.