Analysis and fi nite element simulation of bimetallic backward rod extrusion.

In this paper, the process of bimetallic backward rod extrusion through a conical punch, by means of upper bound method and fi nite element method is investigated. An admissible velocity fi eld is developed and then by calculating the internal, shear and frictional powers, the extrusion force is estimated. The extrusion process is also simulated by using the fi nite element code, ABAQUS. Analysis and simulations are done for two types of bimetallic rods: aluminium as core, copper as sleeve (Al-Cu) and copper as core, aluminium as sleeve (Cu-Al). The extrusion force from the upper bound method is compared with the fi nite element results. This comparison shows that the upper bound predictions are in good agreement with the fi nite element results. The results also show that, the extrusion force in the case of Cu-Al rod is smaller than Al-Cu rod and in both types of bimetallic rods, the aluminium leaves the deformation zone sooner than the copper. Finally the effects of various extrusion parameters, such as the friction factor, reduction in area and semi-punch angle upon the extrusion force are investigated and the optimum semi-punch angle is determined. [ABSTRACT FROM AUTHOR]