Improving the Availability of Tandem Cold Metal Rolling by the Use of Fault-Tolerant Techniques with Virtual Rolling

It is important in the control of the tandem rolling of cold metal strip to achieve a degree of robustness to faults in certain measurements to avoid degradation of the availability of the process. Examples of such faults are those that would preclude valid measurements of strip speed and tension stress. These types of faults could degrade the process availability and seriously reduce the quality and yield of the output, along with a major loss of production and with possible equipment damage. In this paper we propose a method of control for this process that permits continuity of operation during possible major faults in the strip speed and tension measurements due to initiating events that result in several of these measurements being faulty. The faults are handled without major disruptions in process operation or a significant reduction in the quality of the output. The effectiveness of this method is shown by simulations using data from operating mills.