An optimum-curved die profile for the hot forward rod extrusion process

An incremental slab method is implemented to obtain the extrusion pressure of the hot forward rod extrusion process for arbitrarily-curved dies. Two different algorithms utilizing that incremental slab method are developed to obtain the optimum curved die profile that minimizes the extrusion load and stresses at the tool-workpiece interface for the hot forward rod extrusion process. Both techniques are based on the optimization of the effects of friction at the tool-workpiece interface, strain rate, and redundant deformation. The optimum curved die profiles generated by the two different algorithms are found to be very similar. For the material used in the present study which is carbon steel, the shape of the optimum curved die profile is found to depend on the extrusion ratio and Coulomb friction coefficient and not to be affected by the extrusion velocity. The finite element method revealed that the optimum curved die profile developed in the present work produces lower stress levels than those produced using the optimum conical die profile found in the literature. (C) 1998 Elsevier Science S.A.