Square Tube Manufacturing by forward Extrusion of AA7075 with Porthole Die

Abstract

The proposed paper aims at the development of extruding seam square tube of AA7075 high strength aluminum alloy by simulation and experiment. There are several factors related to extrusion load such as billet temperature, billet dimension, flow stress, die cavity and product geometry. The extrusion loads and die stresses for hot extruding square tube with respect to different product have been investigated. Since AA7075 behaves high forming resistance comparing to AA6063 and AA6061, the product design and die design should be modified in order to meet with the limitation of extrusion machinery. Moreover, AA7075 has high thermal welding crack behavior by comparing to AA7003. Therefore, In order to provide high contact pressure enough to conduct solid welding for the split AA7075 materials in welding chamber, the specific die cavity design has been finished. Then, the solid welding pressure can be increased. The research results show that under the same forming conditions such as fixed ram speed and billet temperature, the extrusion force for the product with thick thickness is small than the one with thin thickness. The same result was obtained for die stress. A square tube extrusion experiment has been conducted by installing die set into forward extrusion machinery. The experiment and simulation results have been compared and discussed.