CENTRAL BURSTING AND OPTIMAL DIE PROFILE FOR AXISYMMETRICAL EXTRUSION

A simple criterion for predicting the initiation of central burst in e xtrusion is proposed. The geometric conditions to avoid central bursti ng are predicted by using the proposed criterion under various process conditions and material properties. The optimal die profiles which mi nimize the extrusion power are also obtained for various process condi tions. The mixed (pressure-velocity) formulation is used along with th e Householder method to solve the resulting equations. It is shown tha t the optimal die profiles satisfy the conditions for prevention of ce ntral burst. The predictions based on the proposed criterion are in go od agreement with the experimental observations and are in conformity with the results published earlier.