Controlled Compensation of Defects in the Rings Geometry in Radial-Axial Ring-Rolling by Using Image Processing Methods

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The process of radial-axial ring-rolling has established itself as the main process for producing hot rolled seamless rings within a diameter range of 200 mm up to 13 m. Even though the field of radial-axial ring-rolling has been intensively explored and developed in the past, there are still errors and defects appearing in the rings geometry during the process. Reject will be produced if a rings geometry is still defective after its manufacturing process has been finished. To avoid this reject by exceeding the manufacturing tolerances, material allowance is necessary as defects may occur in the rings geometry. Especially for producing rings with large dimensions, this material allowance may be substantial. Today there is a high number of methods which have been designed to avoid many of these errors. However, most of these methods must be controlled manually by the operator or are activated as a preventative measure. There has not yet been the possibility to detect errors in the rings geometry automatically during the process in order to initiate adequate countermeasures. This possibility has been developed in a DFG-funded research project named Grundlagen zur Steuerung des Radial-Axial Ringwalzens durch den Einsatz von Bildverarbeitungssystemen. This project has introduced the integration of an image processing system which is able to detect errors in the rings geometry within the process of radial-axial ring-rolling. Based on these results, this research project aims at the development of control strategies to automatically avoid the errors of the rings geometry. Input quantities of these control strategies are the information about the rings geometry gathered by the image processing system and the data of the conventional ring measuring system of the radial-axial ring-rolling machine. To realize this approach, the errors of circularity and climbing are exemplarily chosen as the application field. A sub-goal is to catalogue the methods described in literature and to quantify the control variables of these methods to avoid unwanted errors of the rings geometry. Control strategies, based on these methods, can subsequently be developed and put into practice. The implementation as a standalone software and the integration into the control of the ring-rolling machine is also a sub-goal of this project. Along with the development of the strategies and finally to evaluate the results, rolling experiments will be executed. First, the influence of the control variables on the appearance of the particular errors in the rings geometry is in the focus of these experiments. By varying these control variables, the influence can be observed and documented. In further experiments, a parameterization of the control and a verification of the functional capability of the developed approach can be achieved. The possibility of an extension of the developed approach on other defects of the rings geometry shall always be considered.