Effect of Material Properties on Cross-Section Deformation during Bending an Aluminum Extruded Section

The cross-section shape change was investigated to determine the effects of proof stress, r value, wall thickness, and cross section in push-through bending of a square extruded pipe. Extruded A6063 aluminium alloy (40 x 40 x 2.0 mm) was used in the experiment. The push-through bending machine used has a six-axis NC controller. In this study, a two-dimensional single curvature shape was adopted in order to investigate the fundamental bending properties. A high-proof-stress material with severe bending workability was examined in this experiment to clarify the effect of bending workability on the material properties. Workability was evaluated by examining wrinkles and shape change of the cross section; the change in thickness was also evaluated, as were n and r values. The results are as follows. The high-proof-stress material was bent, resulting in significant cross-section deformation. The size of wrinkles caused by bending increased due to the large bending radius, and the wrinkles produced were deep. The effect of the r value on the cross-section deformation after bending could not be determined. In the present experiment range, the bending limit was determined by the size of wrinkles in internal bending. In A6063-T1, the wall thickness had a significant effect, and the forming limit of the thin-walled material was low. The bending limit was low for A6063-T5, and the effect of the wall thickness was slight. The bending limit of a 60 x 60mm cross-section piece was considerably lower than that of a 40 x 40 mm cross-section piece, for the same wall thickness; it was particularly significant in A6063-T5.