Influence of mould structure of continuous extrusion of aluminum tube with double billets on forming property

The continuous extrusion of aluminum tube with double billets is a kind of high efficient aluminum tube manufacturing technology.In order to guarantee the uniformity of metal flow,the continuous extrusion of aluminum tube with double billets needs the confluent die.The confluent die structure is one of the important factors that affect metal forming.According to the characteristics of continuous extrusion forming,based on the HyperXtrude software,the finite element model of the continuous extrusion of aluminum tube with double billet was established.Through numerical simulation of steady continuous extrusion of aluminum tube,the comparative analysis of the metal flow with different confluent die structure schemes was conducted.The experiments for 6063 aluminum alloy tubes were conducted on LLJ350 continuous extrusion machine,and the microstructure and mechanical properties were observed.The results show that outlet diameter of the confluence area in continuous extrusion of aluminum tube with double billets has important influence on the uniformity of the metal flow.When the outlet diameter less than three the periphery diameter of the port hole,the metal flow velocity becomes more consistent,the wall thickness beomes more uniform,and the plasticity has been improved significantly.While,the outlet diameter change has little effect on grain size and tensile strength.