The present study is concerned with an analysis of hydrostatic extrusion through conical dies.
For the analysis of hydrostatic extrusion the upper-bound theory for metal is used in combination with a hydrodynamic lubrication theory for lubrication film.
A kinematically admissible velocity field in spherical coordinate is proposed in order to predict metal deformation energy rate which relates to some variables such as reduction of area, die cone angle and film thickness.
For the analysis of the phenomenon of viscous fluid a lubrication equation is formulated from Reynolds equation in consideration of thermal effect on the fluid film.
According to the concept of energy minimization the total energy rate composed of metal deformation energy rate and fluid viscous shear energy dissipation rate is minimized with respect to the chosen parameters.
Strain-hardening effect and variation of viscosity due to pressure and temperature change are taken into account.
Experiments are carried out with aluminum and copper at room temperature. The experimental results are good agreement with the theoretical predictions.
