Die geometry and frictional condition play an important role in obtaining a desirable flow pattern of deforming metal. The strain-hardening characteristic of metal has also a considerable effect on the deformation pattern.
In this study the effects of various process variables and material characteristics on the deformation pattern are investigated both by theory and experiment. A theoretical model for the deformation field is proposed, which is similar to the actual deforming pattern. Form the proposed kinematically admissible velocity field, the upper bound pressure is computed at the optimal geometrical shape of flow field. Flow patterns are visualized experimentally by visioplasticity using photogridded specimens.
Both from theory and experiment it is shown that the inlet and outlet boundaries move toward the die entrance as friction and strain-hardening coefficient increase. Influence of other process variables are also discussed. The theoretical predictions both in load and flow pattern are in reasonable agreement with experimental observation.
