Application of Simulation Technology to Hollow Die Extrusion

In recent years, the application of various simulations in hot extrusion of aluminum alloys has proven useful. However, the most of them are generally applied in the field of steady metal flow conditions with solid die extrusion. In this paper, the simulation technology is applied to hollow die extrusion. Especially, the effects of the taper port-hole shapes on the extrusion pressure-stroke diagrams and the metal flows are investigated experimentally and theoretically. Taper port-hole shapes are useful for the reduction of the extrusion pressure in comparison with straight port-hole shape, because the extrusion pressure in the port-hole filling process is decreased by the reduction of the sliding friction, and the extrusion pressure in the welding chamber filling process is decreased by the reduction of equivalent strain rate in the port-hole and the welding chamber. FEM results by FEM analysis code added with special know-how show a close match with the experimental results. Therefore, we are able to predict the extrusion pressure and the metal flow through the port-hole and the welding chamber by this simulation technology.