JPS57193216A - Plate thickness controlling method of rolling mill - Google Patents

Abstract

PURPOSE:To always make the plate thickness in the delivery side of a rolling mill coincide with a target value, by controlling front and rear tensions in accordance with actual mean deformation resistance of a material to be rolled, which has been measured in the course of rolling, in a feed forward plate thickness controlling system. CONSTITUTION:When a plate thickness deviation measuring point has reached right under a roll by the expressionI(P: rolling load, H and (h) : plate thickness of the entry and delivery sides, respectively, tb : rear tension) in accordance with a plate thickness deviation signal DELTAH of a thickness gauge 3, and a forecasting value Km of mean deformation resistance, a plate thickness controller 4 provides the rear tension change quantity DELTAtb to a rear tension controller 5. Subsequently, a deformation resistance compensator 8 inputs the plate thickness H+DELTAH and a load P when DELTAH has been detected, and stores both the values. Also, the compensator 8 inputs a load P' and DELTAtb in case when the thickness deviation measuring point has reached right under the roll and has changed the rear tension, calculates the delivery-side plate thickness (h)+DELTAh' of the expression II (M : a constant of a mill, S : a space of a roll), mean deformation resistance Km' of the expression III, and rear tension change quantity DELTAtb' of the expression IV, and provides them to the controller 5. The controller 5 controls a motor 6 by a value which had added DELTAtb' to DELTAtb.