JPS6431512A - Automatic controlling method for plate thickness in rolling mill - Google Patents

Abstract

PURPOSE:To prevent plate thickness from variation based on the eccentricity of a roll in a high speed rolling by setting the central frequency of a band-pass filter to the rotary frequency of the roll by a low frequency worthy of a phase lag based on a hydraulic depressing controller. CONSTITUTION:In order to compensate for the phase lag of a hydraulic rolling rediction controller 36, the central frequency of the band-pass filter 40 is set at a value lower than the frequency corresponding to the eccentricity of the roll. This central frequency works out the roll eccentricity frequency from a signal showing the number of rotations of a motor detected by a rotation detector 34 through a circuit 46 for working out the frequency. To compensate for the phase lag of the hydraulic rolling reduction controller 36, setting of a phase lead is required from the roll eccentricity frequency through a circuit 48 for setting the phase lead. The eccentricity frequency is sent to an arithmetic circuit 50 for the quantity of compensation and since the circuit 50 sets the central frequency of a band-pass filter 40 at a low value, it works to compensate for the reduction of a gain and the gain makes a function of the eccentricity frequency.