A study of severe flange wrinkling in first-pass conventional spinning of hemispherical part

Abstract

Flange wrinkling is one of the most common defects in conventional spinning. Slight wrinkles can be eliminated by a reasonable design of the spinning process parameters or assisted process, while severe wrinkles lead to low forming quality or even defective products. A lot of work has been done to find the reason for flange wrinkling and the way to avoid it, while limited research has been done to study the severe flange wrinkling phenomenon in conventional spinning process. In this paper, the severe flange wrinkling phenomenon in first-pass conventional spinning of the hemispherical part has been studied through FE (finite element) simulations and experiments. A double curved surface buckling prediction model based on the energy method is proposed in order to predict severe flange wrinkling. Experiments are designed to verify the theoretical severe flange wrinkling prediction method. It turns out that the wrinkling of the inner compressive stress ring leads to the severe fluctuations of the spinning force, and it can be taken as a sign of severe flange wrinkling in the conventional spinning process. Furthermore, the effects of flange wrinkling on the spinning qualities of the final formed hemispherical parts are researched. It is concluded that slight flange wrinkles in the first-pass have little effects on thickness distribution and geometry accuracy of the final formed part, while severe flange wrinkles lead to failed products. Severe flange wrinkling prediction is significant for the conventional spinning of the hemispherical part.