Forming Behavior of Thin-Walled Tubular Components in Hydro-pressing with Floating Die

To solve the problems of traditional closed-die hydro-pressing, such as side-biting, stress concentration, and difficulty in removing the components, hydro-pressing with a floating die was proposed. The upper and the lower die frames are first clamped to form a closed space so that the tube blank can be pressed by the upper and lower die cores from opposite directions, significantly improving the cross-sectional accuracy of tubular components and the stability of the process. Therefore, it is suitable for the mass production of tubular components with irregular cross sections. The influence of internal supporting pressure, circumferential compression ratios, and material properties on the cross-sectional accuracy of rectangular tubular components was investigated by numerical simulation and hydro-pressing experiment. The results show that tubular components with optimal cross-section accuracy can be obtained with a relative internal supporting pressure of 0.6 p_s, and the corner radius non-uniformity r_u is only 2.13%. Using high-strength tube materials will reduce the cross-sectional accuracy and increase the risk of side wall wrinkling for tubular components with variable-section perimeters. Moreover, the distributions of circumferential stress and wall thickness were also discussed. These results provide the theoretical basis and the technical support for high-efficiency and low-loading formation of thin-walled tubular components.