Application of a new automatic gauge control system for the tandem cold mill

In July 2000, a new automatic gauge control (AGC) system was successfully installed at the Kakogawa Works, Kobe Steel, Ltd., Hyogo, Japan. The new AGC system consists of two functions: multivariable AGC based on mass flow thickness; and roll eccentricity control. The multivariable AGC is designed using inverse linear quadratic theory, a type of optimal control theory, and controls both thickness and tension. Repetitive control theory is applied to roll eccentricity control as roll eccentricity is a periodic disturbance related to the rotational angle of the rolls. The new AGC system has contributed to improved thickness accuracy and stable rolling. In this paper, details of the new AGC system are described and the application results are shown.