PITA Fiscal Year 2008 Projects - Product and Process Design and Optimization

Modern Control Technology for Hot Metal Rolling

Principal Investigators: Marwan A. Simaan, John Pittner

A large number of companies dealing with metal processing (Aluminum and Steel) are located in the Commonwealth of Pennsylvania and specifically in the Pittsburgh area. An important component of the overall process of manufacturing and processing of metal is the rolling of hot metal strip. In the case of steel, for example, almost one-half of the finished product made in the world is in the form of steel strips originally produced in a hot strip rolling process. These sheets are eventually used in making automobiles and other consumer products. The investigation proposed herein will focus on the application of modern control technology for improving the performance of a tandem hot metal rolling process in order to a better quality metal. This will be a natural and important extension of our initial work funded by PITA in 2006 on the cold rolling process.

The rolling of hot metal strip is a complex multistage highly nonlinear dynamic process that is performed at temperatures in excess of 850 degrees C. These temperatures, coupled with the presence of coolant water sprays on the metal strip present an environment that is extremely hostile to sensors, which precludes the availability of reliable measurements of significant process variables as is the case in tandem cold rolling. In addition, the metal properties are heavily dependent on temperature and the process includes a large number of interacting components and variables, all of which contribute to making the modeling and control of the hot process a much more difficult and challenging task than the cold process.

Recent work done at the University of Pittsburgh as a part of a project funded by PITA in 2006 has shown that the application of a State-Dependent Riccati Equation (SDRE) technique was quite successful in improving the tolerances in stand exit thicknesses and interstand tensions in both discontinuous and continuous cold rolling processes. This proposal considers the extension of the SDRE technique as a basis for the control of tandem hot metal strip rolling. This technology will be completely new and is expected to considerably improve the hot rolling process especially in reducing the variation in the exit thicknesses of the metal which essentially means producing metal of much higher quality.