Forming of ellipse heads of large-scale austenitic stainless steel pressure vessel

Aiming at reducing the drawbacks of traditional forming process of large-scale austenitic stainless steel ellipse heads, the draw-bead was introduced to the forming process in this article. Three types draw-bead were considered in this paper: the round draw-bead, the rectangular draw-bead and edge-bead. Accordingly, a finite element model was built to simulate the forming process of ellipse heads. Meanwhile, the geometrical parameters were optimized in terms of the forming quality, the maximum thinning ratio and the maximum punch force by using the finite element analysis and design of experiment. The single-factor experiment was adopted to find out the possible significant factors and the reasonable range of these factors. The influencing factors, such as the type of draw-bead, the distance between the center of the draw-bead and inside of die, the height of the draw-bead, and the roundness radius of die, were researched. By means of orthogonal test and multi-objective experiment, the optimum parameter combination of draw-bead was found. (C) 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).