Renewal of Automatic Gage Control System for a Cold Tandem Mill with Electric Screwdowns





This paper describes renewal of automatic gage control (AGC) system for a cold tandem mill with electric screwdowns. Although gage control methods using high responsive actuators were researched, there is few research on the renewal of an old mill with low response actuators. We studied the way of improving gage accuracy without reconstructing actuators, from the viewpoint of saving cost.<br> Gage response to manipulation of the actuators depends on the frequency characteristics of the actuators and the rolling process, and the effect of AGC was restricted by these frequency characteristics. We eliminated the frequency dependency of the gage response by inserting a dynamic compensator with reverse frequency characteristics in the control loop of AGC, and expanded the controllable frequency range of the feedforward AGC to a higher frequency. Moreover, in order to reduce the tension change caused by the gage control and to stabilize rolling force during acceleration and deceleration, we developed new tension control and rolling force control manipulating reduction in thickness. The combination of these controls and the feedforward AGC reduced gage deviation, keeping stable rolling. <br> The application of this AGC system to a cold tandem mill with electric screwdowns resulted in a great improvement in gage accuracy, and the accuracy has almost matched that of a newly constructed mill.


  • ISIJ international

    ISIJ international 38(9), 977-984, 1998-09-15

    The Iron and Steel Institute of Japan

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