Use of Advanced Control Techniques With Virtual Rolling to Improve Threading of the Tandem Cold Mill

The threading of the tandem cold metal rolling mill is a significant function in the control of this process. During the threading process it is important to reduce the excursions in the strip thicknesses and tensions. Additionally, in most cases it is desired by the operational personnel to control the individual mill stand speeds such that, as the head of the strip moves between two adjacent stands, its speed between the two stands is held at the strip speed at the exit of the last stand just before acceleration to run speed. Moreover, it is desired that disturbances in the thickness and the resistance to deformation in the incoming strip are successfully handled by the controller. In this article, we propose a method of improved control for this process that considers all of these requirements. The effectiveness of this method is shown by simulation using data from operating mills.