Modelling and prediction of twist springback for UHSS thin-walled component with asymmetric complex section in roll forming process

To solve the problem that twist springback of thin-walled component with asymmetric complex section cannot meet the high-precision quality requirement, FEA (finite element analysis) model of multi-pass roll forming (RF) process is established. Different material constitutive models are verified with RF tests, and the developed FEA model with variable elastic modulus and Yld2000 yield criterion is carried out to predict twist springback accurately. The mechanism of twist springback is studied by numerical simulations that twist springback results from the torque produced with the uneven residual longitudinal stress distribution due to the asymmetric forming for asymmetric section. The effect of different forming strategies on twist springback is discussed that developed UDT-type (USTB-Durable T) method with constant-arc-length method can effectively control twist springback. Orthogonal test is designed to study the effect of process parameters on twist springback. Results indicate that forming stands has the greatest impact on twist angle, followed by roll diameter and inter-distance, and roll gap has the smallest impact. The developed design and forming parameters are applied to control twist springback of asymmetric complex-section product. The actual product is deformed in industrial production line with the twist angle of less than 2 ^∘ /m to meet high-precise quality requirement.