A UBET analysis of the non-axisymmetric combined extrusion process

In this paper, the upper bound element technique (UBET) method was used to analyze non-axisymmetric combined extrusion processes. New kinematically admissible velocity fields (KAVFs) were proposed to determine the forming load, the extruded length and the velocity distribution according to the stroke in the combined extrusion process of a socket wrench from solid cylindrical billets. Experiments were carried out with antimony–lead billets at room temperature without lubricants. In order to observe the flow pattern of a billet at each stroke, square grids were inscribed on the surface formed by cutting the billet longitudinally. The forming load and the extruded length were compared between theory and experiment. It was found that the theoretical predictions of forming load and extruded length were in good agreement with the experimental results.