Research on tube hydro-forging process of trapezoid-sectional parts

The tube hydro-forging as a new tube forming technology has many differences in principle and mechanism; it is based on the principle of compression deformation instead of the common tensile deformation. This gives great advantages to form parts with variable cross-section perimeters and small sharp corner. The trapezoid-sectional parts are the usual quadrangular structure and widely used in many areas, but it has poor shape accuracy when formed by expansion. In this paper, the tube hydro-forging process of trapezoid-sectional parts was studied. The effects of corner angle and radius on the thickness distribution were analyzed theoretically, and the design principle of die parting for asymmetric trapezoid-section was pointed out. Finite element analysis and the experimental results show a good agreement with the theoretical conclusions. The present study provides a guideline for the rational design of process parameter and die parting, and it will be helpful to wide application of the tube hydro-forging process.