Theoretical prediction of flange wrinkling in first-pass conventional spinning of hemispherical part

Flange wrinkling is one of the most common defects in conventional spinning. A lot of work has been done to find the reason for the flange wrinkling and the way to avoid it. However, the theoretical prediction of flange wrinkling is limited for the non-uniformly distributed stresses and complicated boundary conditions of the flange. In this paper, a FE (Finite element) model is established to study the deformation characteristic of the material in conventional spinning, two stable compressive stress rings distributed at the middle surface of the formed part are found, and the outer stress ring distributed at the flange is considered to be the key factor of flange wrinkling. A theoretical flange wrinkling prediction method is proposed based on the plastic buckling theory and the energy method with the boundary conditions extracted from the FE simulation results. Experiments are designed to research the flange wrinkling phenomenon and verify the proposed theoretical flange wrinkling prediction method. At last, effects of feed ratio on flange wrinkling are analyzed by this method, it is concluded that the decrease of the circumferential compressive stresses distributed in the flange caused by low feed ratio reduces the risk of flange wrinkling.