Extrusion of axi-symmetric bi-metallic tubes: some experiments using hollow billets and the application of a generalised slab method of analysis

A generalised slab method of analysis is developed for the extrusion of axi-symmetric bi-metallic tubes through profiled shaped dies and over profile shaped mandrels. It is applied to different combinations of die shapes and mandrels. An experimental investigation into forward extrusion of bi-metallic tubes made of cp aluminium and hc copper was also carried out and the resultant non-dimensionalised extrusion pressures, flow patterns and characteristic deformation modes observed are given and the results commented upon. The theoretical results of extrusion pressures obtained from the analysis are compared with the experimental as well as those of other authors. These show reasonably good agreement.