Upper bound analysis of bimetallic rod extrusion process through rotating conical dies

In this paper, an upper bound approach is used to analyze the bimetallic rod extrusion process through rotating conical dies. By extending the kinematically admissible velocity field for mono-metal rod extrusion to the bimetallic rod extrusion process, the internal power and the power dissipated on frictional and velocity discontinuity surfaces are evaluated. Then, by equating the total power with the external power produced by axial movement of the punch and the power induced by rotation of the die, the relative extrusion pressure is determined. The extrusion process of bimetallic rods composed of a copper sleeve layer and an aluminium core layer through a conical rotating die is also simulated by using the finite element code ABAQUS. The analytical results are compared with the results given by the finite element method. These comparisons show a good agreement.