Study on the Guiding Chamber Effect on Welding Pressure in Hollow Extrusion Die Design

In order to increase the welding pressure of the hollow Al7075 tube in extrusion process, a special die feature has been created. Several different proportions of chamber structure in outlet of extrusion die have been designed. The finite element analysis software DEFORM 3D to analyze various design parameters on the load–displacement and the welding pressure have been studied. Comparing to 6000 series, 7000 series aluminum alloy have good material properties, including excellent strength and toughness especially for hollow aluminum extrusion products in terms of Al7075. However, in extruded hollow aluminum alloy products, the industry’s common use is 6000 series material, except for indirectly extruded seamless pipe, Al7075 can be found. This is because of less welding pressure can be provided by using the traditional die structures in Al7075 hollow products. Therefore, to use the directly extruded seam tube of Al7075 in high-yield and high-quality, to increase the welding pressure and improve the quality of welding products becomes a very important issue. In this study, a different high proportion in material guiding chamber has been defined. The same angle both on the exit of female die and the bearing of male die which can be integrated into a material guiding chamber has been designed. Therefore, the welding pressure can be increased due to the change of metal flow behavior that is after a complete fill in material guiding chamber, and then metal can flow out of die bearing surface. The results showed that welding pressure can be increased rapidly if a suitable material guiding chamber has been built. Among them, the ratio of chamber height and length is 2:1; the increased welding pressure is most significant.