Study on cross-sectional distortion laws of 3D multipoint stretch bending based on internal filling support

In the process of multipoint stretch bending, the hollow rectangular profile is easy to produce serious cross-sectional distortion, which affects the forming quality of parts. In this paper, adding internal fillers to the hollow rectangular profile significantly reduces the cross-sectional distortion of the hollow rectangular profile during the multipoint stretch bending process, and the forming quality of parts has been improved. In order to study the influence of different process parameters on cross-sectional distortion and to obtain the minimum bending radius of the parts with qualified cross-sectional shapes, it is very important to study the formability of the profile and guide the actual production. The Abaqus finite element simulation platform is used to study the effects of pre-stretching and post-stretching on the cross-sectional distortion of the profile. Based on a large number of simulation analyses, the minimum bending radius of the parts with qualified cross-sectional shapes is obtained. The research shows that the addition of internal fillers can effectively reduce the stress and strain of the hollow rectangular profile, expand the safe forming area, and form parts with qualified cross-sectional shapes under a smaller bending radius.