K Abrinia - Engineering Department, College of Engineering, University of Tehran
M Makaremi - Engineering Department, College of Engineering, University of Tehran

A simulation based on the upper bound solution for the forward extrusion of elliptical sections with the major diameter greater then the initial billet diameter is presented in this paper. A generalized velocity field is presented which is derived from the geometry of the deformation region and is automatically kinematically admissible. For the extrusion of such shapes the material flow in the die has both diverging and converging nature. The theory presented predicts the material flow and predicts the effects of different process parameters such as friction, reduction of area, shape complexity on the extrusion pressure. The same theory was used for simulating the extrusion process for bilinear dies. Numerical finite element analysis was also carried out for the same die designs and comparison with the analytical results showed good agreement. Experiments were also carried out and the theoretical results were verified.

extrusion, elliptical sections, simulation, upper bound