A novel combined process of flaring-upsetting for forming end flanges on thin-walled tubes

Tube components with end flanges are widely used in piping systems of industrial fields. Generally, folding defects are prone to generate in the upsetting of the end flange tubes, for which the size of the end flanges is limited. In this paper, a novel process combining the flaring and upsetting deformation is proposed for forming the end flanges on thin-walled tubes. First, the flaring-upsetting combined process of thin-walled rings was studied to clarify the influence of the flaring pre-deformation on the subsequent upsetting deformation behavior. It is concluded that the position and size of defects depend on the flaring angle, the ratio of height to thickness and the upsetting reduction. Furthermore, the novel process is applied for forming the tube end flanges. Under proper parameters, the folds with little increase in size were transferred to the upper surface, which can be removed by machining without any harm to the flange quality. Therefore, the process is conducive to fabricating thin-walled tubes with wider flanges.