Investigation of Ring Rolling Key Parameters for Decreasing Geometrical Ring Defects by 3D Finite Element and Experiments

The complexity of adjusting ring rolling process parameters is always a great challenge for producing high-quality rings. Inappropriate adjustment of main process parameters, including mandrel feed speed, main roll rotational velocity and guide rolls forces, may lead to geometrical defects such as fishtail, non-circularity and polygon-shaped rings. In this paper, for the first time, the effects of noted main parameters on the above geometrical defects are thoroughly investigated using simulation by Abaqus\Explicit as well as experimental data obtained by radial-axial ring rolling (RARR) setup. Experimental results confirm the final ring geometry, which was obtained by the finite element method. The results show that the individual main process parameters such as mandrel feed speed and main roll rotational velocity have an insignificant effect on a non-circularity defect. However, lower mandrel feed speed-to-rotational speed ratios (F/RT) causes a slight decrease in the value of non-circularity. Furthermore, it was shown that increasing feed speed decreases the fishtail defect due to the diffusion of the plastic zone to the whole ring cross section. This effect can also be obtained by reducing the main roll rotational velocity. Thus, increasing mandrel feed speed improves ring geometrical quality if the process remains in stable condition. In addition to eliminating fishtail defect, the existence of axial rolls would enhance process stability by restricting ring motion and avoiding the ring wobbling and polygon-shaped defect forming in the final ring.