An effective method for predicting the shape of doubly curved sheet metal in continuous roll forming

Continuous roll forming (CRF) is an innovative and powerful process for manufacturing three-dimensional (3D) surfaces using only one pair of bendable rolls. By adjusting the bending shapes of the rolls and the size of the roll gap, doubly curved parts with different types and shapes can be formed. This paper presents an effective method for predicting the shape of doubly curved sheet metal in CRF, that is, the sheet curvatures caused by plastic and elastic deformation are tackled separately, and the effects of the two are superimposed, so as to solve the actual transverse and longitudinal curvatures. The influence of gravity is ignored in the derivation of the basic equation, whose rationality is verified by the finite difference method (FDM). In order to confirm the applicability of the curvature calculation formulas, finite element simulations and forming experiments for two typical doubly curved surfaces are carried out. The simulated results are extremely close to the experimental data, demonstrating the accuracy of the finite element simulation. Under the conditions of different maximum compression ratios, blank widths and radii of the roll gap centerline, the forming surfaces gained by theoretical calculation fit well with those obtained by finite element simulation, thus proving the validity of the derived formulas. The method presented in this study is extended to the process of 3D surface rolling based on rigid variable-section rolls (TSRRAR), and it is found that the method is also applicable in the case of small central reduction.

Automated summary

Continuous roll forming (CRF) is a powerful process for manufacturing 3D surfaces using bendable rolls. This paper presents an effective method for predicting the shape of doubly curved sheet metal in CRF by separately tackling the curvatures caused by plastic and elastic deformation. The method is validated through finite element simulations and forming experiments, showing close agreement between theoretical calculations and experimental results.