JPS5626612A - Controlling method for thickness of rolled sheet - Google Patents

Abstract

PURPOSE:To reduce the fluctuation of sheet thickness due to the eccentricity of the backup roll, and to make a leap in the accuracy of thickness control, by computing the representative waveform of the sheet thickness fluctuation owing to above stated reason according to the linear forecasting method depending on the time series data for the sheet thickness on the run-out side, and by controlling the hydraulic screw down mechanism depending on above computed waveform. CONSTITUTION:The thickness of the rolled material 3 on the run-out side of the rolling stand, comprising couples 1, 2, of work rolls and backup rolls, is measured for a specified period of time by the thickness measuring device 6 utilizing X-rays, etc., installed at a specified position; the result of this measurement is sent out as the signal x(t). At the sampling time T, the converter 7 carries out the A/D conversion, and sends out the discrete time series signal xn. The computer 8 processes this signal statistically and computes the representative waveform of the periodical sheet thickness fluctuation owing to the eccentricity of the roll couple 1, and sends out the signal x'n. This signal is the control signal for removing above stated sheet thickness fluctuation of the present rolling pass. On the other hand, a pulse corresponding to the measured rotational speed of the roll 1a and the eccentricity period, is produced from the generator 11 and is inputted to the computer 8. With the signal x'(t), the circuit 10 sends the corrected signal to the hydraulic screw down device 4; hereby, the device 4 is controlled.