Abstract: During the process of finite element simulation of precision warm forging,the selec-tion of friction models has a direct effect on the precision accuracy of finite element simulation results.Among all the factors which inftuence the selection of friction models,hte distribution rule of mormal stress at the tool-workpiece interface is a keyone.To find out the distribution rule of normal stress at the tool-workpiece inter-face,this paper has made a systematic research on three typical plastic deformation processes:forward extrusion,backward extrusion,and lateral extrusion by a method of finite element simulation.Then on the base of synthesizing and correcting tradi-tional friction models,a new general friction model which is fit for warm extrusion is developed at last.

Key words: friction model, warm extrusion, finite element simulation,