Investigation of crease defect of L-profile in flexible stretch bending of multi-point roller die process using experimental and numerical methods

Springback, fracture, and cross-section distortion are common defects in stretch bending process of profiles. The crease defect of profiles is not obvious in the traditional stretch bending process. However, in the 3D flexible stretch bending of multi-point roller die process, due to the multi-point roller dies instead of the whole die, the forming process is more complex. Therefore, the crease can no longer be ignored. In this paper, the finite element model is established, and the effect of different process parameters on crease defect is discussed, and experiments are carried out with the forming equipment. The validity of numerical simulation is verified by experimental results. The results show that the crease defect becomes more obvious with the increase of the pre-stretching length, the post-stretching length, and the friction coefficient. The number of roller dies has a significant effect on the change of crease defect. However, the change of roller die radius has little effect on the crease defect.