Ring rolling with flat dies: An analytical method to optimize geometry, time or energy

Ring rolling process is a plastic deformation process used in the production of seamless rings having diameters in a range of meters. During production, rings simultaneously undergo to a width and height reduction and a diameter expansion, however located in different ring cross sections as a function of idle, axial and driving rolls action. Despite roll motion law could be set independently, their combination influences ring accuracy, production time and energy required. Accordingly, based on the results of simulation plan, the authors present an analytical model able to optimize rolls motion laws as a function of required geometrical accuracy and minimizing production time and energy. The analysis of these latter, allowed the definition of their regression models as a function of Idle roll feed rate and ring rotational speed. These models were then expressed as a function of selected geometrical precision parameter and a weighting factor, for balancing time and energy of the process. Afterwards, geometry and energy models were arranged to define an objective function that, once minimized, allowed to assess the optimized values of the process parameters able to achieve the selected ring precision while decreasing process time and energy. The proposed methodology was applied on different combinations of geometrical and weighting factors, and the resulting optimized conditions were tested by finite element simulations. The good comparison between modeled and simulated ring accuracy and energy, demonstrates the model efficacy in the selection of proper motion laws of ring rolling equipment.