Influences of conditions at tube-blank end on viscous medium outer pressure necking of thin-wall parts

Influences of the conditions at tube-blank end on viscous medium outer necking of thin-wall parts were analyzed by theoretical method and finite element method.Then the buckling pressure as well as the shape change of the tube-blank and the rule of its wall thickness distribution after wrinkling,under the condition of the end fixed and free were obtained.Results show that the end condition of tube-blank makes an impact on the forming quality of the viscous medium outer pressure necking of thin-wall parts.Restraining the end of the tube-blank and limiting the material flow can not only give rise to the buckling pressure,but also help to eliminate the wrinkles and increase the necking limit.