Abstract
Aluminum space-frame is one of the candidates to be applied to a structure of car bodies in future because of its light weight as well as high strength. To omit the secondary forming process in the production of aluminum space-frame, variable shape extrusion apparatus employing a taper mandrel and four movable dies has been developed and the characteristics of hot extrusion were investigated. As a result, the step mandrel provides good dimensional accuracy due to its bearings which is parallel to the extruding direction. On the other hand, severe pick-up occurred easily on the surface of extrusions by using the step-mandrel. DLC coated dies has a remarkable effect to suppress generation of pick-up even under extrusion temperature of 673K.
