Effect of the Pre-bulging Process on the Quality of Single-point Incremental Forming

Single-point incremental forming of metal sheets is an advanced plastic forming process for manufacturing shell parts with complex geometries. However, issues related to forming quality have consistently limited its widespread application. In this study, a pre-bulging process is introduced into SPIF to modify the initial shape of the sheet and alter the distribution of stress and strain, thereby improving the forming quality. Using a conical shell component as the target component, the influence of different pre-bulging pressure on geometric accuracy and surface quality is investigated through finite element simulations and experimental studies. The results indicate that both axial and radial errors of the formed parts decrease with increasing pre-bulging pressure. In contrast, the surface roughness initially increases and then decreases as the pre-bulging pressure rises, with optimal forming quality achieved at a pre-bulging pressure of 0.8 MPa. The methods and conclusions presented in this paper are expected to provide valuable insights for future research on pre-bulging assisted single-point incremental forming.