Method for manufacturing seamless conical rings with defined inclination angles on radial-axial ring rolling mills

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The global objective of this research project is to investigate rolling strategies for manufacturing reproducibly dish shaped rings on conventional radial-axial ring rolling mills without using profiled special tools.In the first funding period, a FEM model was developed, which allows to simulate the ring climbing process realistically. Therefore, additional information about the climbing process, necessary for a deeper process understanding, is available. It could be confirmed that, climbing is associated with a higher tangential stretching of the rings inner part. Furthermore, it was observed in simulation as well as in experiment that for disk shaped rings and a high axial feed the varying contact length over the radius is sufficient in order to support a greater stretching of the rings inner part. Another result of the study is the knowledge that the instability of ring climbing must be initiated in order to manufacture dish shaped rings reproducibly. The local variations of the achieved inclination angle should be reduced by stabilizing the position of the ring after the ring started climbing. For both, the intended initiation of climbing and the stabilization the position of the ring different concepts have been developed. These resulted in a significant improvement with respect to the uniformity of the ring geometry in the FEM-simulation.Based on the global objective and the previous results, the measures for the initiation of ring climbing and stabilizing the position of the ring, which were confirmed to be promising by the FEM, will be examined and tested in reality within the further applied project period.Based on the simulation results concepts for the practical implementation to achieve both objectives have been developed. On the one hand, these concepts require relatively simple modifications of the ring rolling machine, especially of the guide rolls and the main roll. On the other hand, the rolling strategy according to the FEM-simulation has to be implemented in the industrial ring rolling mill by intervention in the control algorithms of the machine. It is expected that as in the simulation the uniformity of the final geometry can be improved considerably by these measures and therefore reproducible dish-shaped rings with small tolerances can be rolled.