AN UPPER BOUND SOLUTION OF BACKWARD TUBE EXTRUSION PROCESS THROUGH CURVED PUNCHES

Abstract

In this paper, an upper bound approach is used to analyze the process of backward tube extrusion through arbitrarily curved punches. Based on the assumptions of proportional angles and proportional distances from the mandrel surface in the deformation zone, two kinematically admissible velocity fields are proposed and those are used in upper bound solution. By using the developed upper bound solution, optimum punch lengths which minimize the extrusion forces are determined for a streamlined punch shape and also for a conical punch. The corresponding results are also determined by using a finite element code, ABAQUS, and by doing some experiments and compared with the analytical results. This comparisons show a good agreement.