Part Accuracy of Hollow Profiles Manufactured through Flexible Roll Forming

To further improve the performance of lightweight profiles used in automobile production technologies have been developed to increase the diversity of profile shapes. One of these technologies is flexible roll forming. With this modified roll forming process profiles with non-constant cross section in lengthwise direction can be manufactured. Several typical form deviations are known for roll formed profiles. Because of the increased deformations in the area of changing cross-section the deviations are amplified and additional phenomena arise. In flexible roll forming, in opposition to conventional roll forming, the shaping of the flange leads to considerable non constant lengthwise plastic deformation of the flange. The resulting stresses in the parts lead to typical warping of the profiles which can be regarded as an imprinted spring-back effect for this process. Geometric ratios and material properties of the profile allow an estimation of this phenomenon which needs to be considered during profile design. Other difficulties lie in the forming radius and variation of the flange height. One major challenge for manufacturing is the closing of the flexible roll formed profile due to variations in the flange height.