Stretch bending defects control of L-section aluminum components with variable curvatures

Abstract

To achieve high-precision bent components for rail vehicles, the stretch bending properties of the common L-section aluminum extrusions with variable contour curvatures were investigated by simulation. The causes of the defects, such as bad die fittingness, cross-section distortion of horizontal plate sagging and low contour accuracy, were analyzed, and the corresponding control methods were proposed. The simulation results demonstrate that die fittingness could be significantly improved by increasing the die elongation. The horizontal plate sagging distortion of L-section aluminum components could be eliminated by modifying the die supporting surface curve, i.e., to reduce the depth from the die’s outer surface according to the shrinkage of the profile’s vertical wall. By applying suitable springback compensation to the bending die geometry, the contour accuracy could be enhanced exponentially. Using the optimal process parameters and defect controlling methods, the stretch bending tests were then carried out, and results indicate that the proposed controlling methods were quite effective and the scale production of high-precision bent parts has been achieved.