JPS5633111A - Controlling method for sheet shape in rolling mill - Google Patents

Abstract

PURPOSE: To improve the control performance for the sheet shape, by correcting the roll bending force depending on the factor affecting the sheet shape varying during the rolling work and the error of the roll bending force obtained from the specified relationship.

CONSTITUTION: At controlling the sheet shape in the rolling mill, the variation of the deformation- resistance in the direction of the roll axis, the variation of the friction factor between the roll and the rolled material, the variation of the thickness of the oil film of the bearing to support the roll, and the variation of the rolling load as the influence of the automatic control, are detected as ones of factors affecting the sheet shape during the rolling work. At the same time, other factors like as the thermal expansion and the roll's defacement are presumed as the variation of the roll crown, by measuring the initial crown just after the exchange of the rolls, and by taking this value as the initial value for establishing the forecasting formula for forecasting the thermal expansion and the roll's defacement as the function of the rolling load, the draft percentage, the sheet thickness, the number of revolutions of the roll, the open air temperature, the coolant temperature, and the time, and then, by calculating this formula. As a result, the optimum roll bending force is obtained from the variation of the rolling load and the roll crown. The roll bending force is corrected according to the error of the roll bending force and the error signal for the undetectable and unpresumable factors given by the sheet shape detector.

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