A simple analysis for bend-stretch forming of aluminum extrusions

Bend-stretch forming is a cold-forming operation used to bend initially straight aluminum extrusions. The process consists of bending the parts over a curved die in the presence of axial tension. Higher tensions reduce the springback of the part but can induce relatively large, permanent cross-sectional distortions. This work presents an efficient formulation to predict the cross-sectional distortion of extrusions with relatively arbitrary, thin-walled cross-section. The results show good agreement with calculations for simple tubular sections and experimental results in the literature. The numerical implementation has short computer run times and should be useful in the design of extrusion cross-sections and in the optimization of the process variables.