Research on the ovality of hollow shafts in cross wedge rolling with mandrel

The trend towards lightweight construction has increased the use of hollow shafts. Cross wedge rolling (CWR) is a competitive near-net-shape forming process that can reduce costs and improve quality in the production of hollow shafts. The ovality of workpiece is the most important issue for making hollow shafts by cross wedge rolling with mandrel, and the process parameters are the main influence factors. The relationships between the process parameters and ovality were investigated by analyzing the influence of the helical and circular contact area between the tool and workpiece on the metal flow using the finite element method. Through the definition of ovality coefficient, a method for predicting the ovality of workpiece and choosing the process parameters was established. The simulation results were verified via rolling experiments and used to develop a process of cross wedge rolling the axle sleeves of truck with good forming quality. This work can provide a theoretical guidance for the tools design and production application of cross wedge rolling hollow shafts with mandrel.