Research on Forming Process and Deformation Rule for the Necking of Viscous Medium under Outer Pressures

In this paper, a novel forming method of viscous medium outer pressure necking is presented. Influences of buckling and wrinkling as well as viscous medium properties in necking process on the forming process is analyzed by finite element method. As a result, rules of deformation of the viscous medium and variation of the tube blank shape in the necking process are obtained, and influences of the viscous medium properties on buckling necking amount and appearance variation of wrinkles are concluded. The research results show that viscous medium can alleviate the influence of buckling and wrinkling on the forming process of necking under certain conditions, and increase the necking deformability of tubular blanks. Meanwhile, choosing viscous medium with high rate-sensitivity is helpful to improve the necking limit.