Analysis of extrusion flow behaviors of square pipe deformed with three-porthole and two-core die

In order to reveal the nonuniform flow of aluminium in the two-core die and the effect of die structure on the welding quality,flow behavior of 6005A aluminium alloy square pipe was analyzed with DEFORM-3D. The tetrahedron mesh unit was adopted and the relative interference coefficient was set as 0. 4. The results show that,the weld line is centered in the side of square pipe when the area ratio of the middle porthole to the side porthole is between 0. 93 and 1. 03. When the height of welding chamber is equal to 13-16 mm, the alloy can be welded very well and the forming quality is the best. The extrusion force increases slowly as extruding,but it reaches the peak value abruptly when the billet touches the bottom of the welding chamber. The temperature of alloy increases obviously while the alloy breaks through the die bearing,and the peak value reaches 546-548 ℃. The extrusion experiment was carried out,and the results are in agreement with FEM results.