Research on reverse multi-step single-point incremental forming and its application for making straight-wall parts

In this study, the strategy of reverse multi-step single-point incremental forming for making straight-wall cups was presented. The simulation was performed using finite element analysis software and validated with experimental data. The forming strategy was to pre-form the unprocessed area outside the target shape so that the material may be compensated for the area of high strain during forming. The distribution and thickness of the metal sheet could be significantly enhanced with adequate reverse pre-forming in this manufacturing approach. The minimum sheet thickness was increased by 7% at an axisymmetric cone of 45° and 17% at an axisymmetric cone of 60°. A cup with vertical side walls was also made using the proposed method. The sheet’s forming angle was extended from 72° to 90° using reverse vertical forming, considerably improving the sheet’s limit of single-point incremental forming. Using a multi-step vertical forming process, the distance and angle of each step were appropriately configured. The resulting vertical side-wall cup had an even distribution of strain without exceeding the material’s forming limit, enhancing the formable angle of the sheet in single-point incremental forming.