A novel application of sideways extrusion to produce curved aluminium profiles: Feasibility study

Conventional curved aluminium alloy profile forming methods which depend on apparatus, additional to extrusion tooling, to bend extruded, straight sections inevitably decrease manufacturing efficiency and have to deal with springback and cross-sectional distortion. In this article, a novel energy-efficient forming method based on internal differential material flow, differential velocity sideways extrusion (DVSE), is proposed, which can directly form billets into curved profiles/sections by extrusion alone, using two opposing punches. A detailed study has been conducted and cold extrusion/bending of round bars and tubes was examined. It was found that curved profiles/sections with no distortion are formed, and adjustable profile curvature can be achieved by changing the velocity ratio of a slower lower punch to a faster upper punch and also extrusion ratio. Lower velocity ratio and larger extrusion ratio tend to increase the material flow velocity gradient at the die exit and lead to greater curvature. Effect of velocity ratio is greater than that of extrusion ratio, especially when velocity ratio is less than 1/3. Effect of the extrusion ratio is small when velocity ratio is greater than 0.5, after which the effect of extrusion ratio becomes more significant as velocity ratio decreases.