Simulation of multi-hole die extrusion

Abstract

When extruding shaped sections which would normally require pressures in excess of the press capacity, and where it is more productive to extrude shorter lengths or when extruding forge stock it is common to use multi-hole dies. The literature describing or analysing this process is sparse although the industrial application is quite common. The majority of experimental extrusion reported has been concerned with plane or axi-symmetric extrusion of sheet or rod. There are few studies reported concerning the pressure requirements or the temperature variations and material flow when considering complex shapes or multi-hole dies although these are important considerations to the press designer and to the operator. This paper reports the use of a commercial FEM code FORGE3 ® to study the influence of the number and the distribution of die holes on extrusion parameters. The flow pattern, pressure requirements, and temperature histories developed are established and it is clearly shown by the FEM simulations that agreement with experimental results is obtained. The metallurgical behaviour (the substructure, recrystallised grain size and the fraction recrystallised) is obtained from these simulations and is used as a criterion for the optimal distribution of the multi-hole configuration. Finally the structures are compared with extrusion through a single-hole die.