3D-FE modeling for power spinning of large ellipsoidal heads with variable thicknesses

A finite element (FE) model is urgently needed to settle unqualified wall thicknesses, poor fitability and low surface profiles and thereby improve the forming qualities obtained during the power spinning of large ellipsoidal heads with variable thicknesses (LEHVTs). Thus, based on a comprehensive understanding of the characteristics of LEHVT power spinning, an accurate and efficient three-dimensional (3D) FE model was developed and validated by comparing simulation and experimental results. The following technological strategies were addressed: (1) a method for determining the roller trajectory was developed to accurately control the movement of rollers; (2) a similarity theory for reducing the size of the FE model was introduced to save computational time; (3) a constant roller feed ratio and spinning linear speed was implemented by changing the roller feed rate and the mandrel speed, respectively, which improved the stability and efficiency of the FE model; and (4) the different degrees of reduction deformation at different LEHVT zones were considered, and variable mesh densities were adopted to improve computational efficiency. Based on this model, the distributions of stress, strain and wall thickness during this process were obtained. Unfitability and radial runout after unloading were also analyzed.