Study of metal flow behavior during extruding with inner cone punch

For the defects such as dead zone and shrinkage cavity in conventional extrusion process, an inner cone punch was proposed to improve the metal flow behavior. Numerical simulations on extrusion process with and without the inner cone punch were carried out, and the division of deformation was proposed by employing the characteristic quantity such as Lode parameter and invariant of the deviate (J₂). Numerical simulation results were tested by the 7050 aluminium alloy extrusion experiments, the results showed that, by employing the inner cone punch, velocity field distribution during extrusion process would be improved greatly, the risk in generation of dead zone was reduced remarkably, and shrinkage cavity would be avoided, therefore, the inner cone punch made the metal much easier of extruding.