The shape analysis of three-dimensional flexible rolling method

A new forming method, three-dimensional flexible rolling, is proposed for three-dimensional surface parts, which can form the parts effectively with the dieless characteristics. In this study, the shape of bending rolls is circle and the bending radii of upper and lower rolls are different; therefore, the roll gap is non-uniform. Because of the roll gap, an uneven compression appears at the transversal direction, which leads to a non-uniform elongation in feeding direction. The parts bend in two directions at the same time, and the three-dimensional surface shape is obtained. The forming rules of flexible rolling are proposed to analyze the relationship between the pressure ratio and the deformation extent of double-curved surface. The function between the non-uniform roll gap and the bending radius is deduced from the theory of invariable volume. An experimental device is developed to do the forming experiments. The feasibility of the device and the advantage of the method have been validated through numbers of experiments. Typical three-dimensional surface parts such as the convex and saddle parts have been completed for researching and analyzing. Some fine numerical simulation results of flexible rolling have been obtained. Finally, the simulation results are compared with the actual results to analyze the shape and illustrate the forming effect.