Influences of forming parameters on wrinkling in NC thin-walled tube bending

The NC thin-walled tube bending process is multiple-factor-coupling action, and wrinkling often occurs in the process. A numerical method is put forward to predict the wrinkling onset based on the energy method and FEM. At the same time, the influences of forming parameters, such as bending radius, relative tube radius, material properties, forming speed and so on, on the wrinkling initiation are also researched. The results indicate that the bending radius, the relative tube diameter, the extension of mandrel, the hardening factor of material and friction are the main factors determining the wrinkling onset in the process, while the strength coefficient of material and the forming speed only have a little effect. These results provide the guidance for the optimization of the forming parameters in tube bending.