Dynamic analysis and performance of hot rolling mills

Abstract

The development and testing of a mathematical model suitable for the simulation of the dynamic performance of hot rolling mills are described. The model which has been developed includes a detailed representation of the mill motor and supply transformer together with a simplified, but nevertheless adequate, representation of the torsional elements of the mill, including important non-linear elements such as torsional detuners. Considerable attention is paid to an accurate determination of the magnitude of the rolling load and a picture of how this might change as a function of time is given since this directly affects the accuracy with which mill responses can be predicted. A method for improving the accuracy with which the rolling load can be predicted for low roll radius/stock height ratios is given and a simplified guide for itsapplication is developed. New information on the lateral spread of less common steels when rolled in open passes is given and the accuracy of some of the more popular spread formulae is examined. Confirmation of the ease with which reasonably accurate rolling temperatures can be predicted using only simple methods is also given. Solution of the differential equations governing the mill performance is obtained numerically on a digital computer. Comparison between test and computed results show close correlation and the model has been used to assist with a number of important changes in plant design and rolling practice. It is expected that the method will prove a useful addition to existing design-analysis methods, particularly where a high degree of electromechanical interaction may be an important feature of the design.