JPS60180616A - Control method of sheet thickness - Google Patents

Abstract

PURPOSE:To improve the control of sheet thickness by removing the hysteresis of a rolling reduction device in controlling a sheet thickness control device wherein a hysteresis exists between the actual roll opening of a rolling mill and the detecting signal of a roll opening position. CONSTITUTION:A rolling material 1 is rolled between the rolls of a rolling mill 2, and a roll opening is adjusted by a rolling reduction device 3, and the rolling load of device 3 is detected by a load meter 4. The roll opening is detected by a roll position detector 5 and is inputted to a sheet thickness control device 6 together with a load signal outputted from the meter 4; a roll opening reference is inputted to a draft-position-decision driving device 7 which adjusts the roll opening by its output. Here, said roll-opening-position detecting signal is corrected by a bias value DELTAS<e> equivalent to the hysteresis portion of device 3, and a roll-opening-position reference signal is also corrected by adding or subtracting the value DELTAS<e> to/from the reference signal, depending on whether the rolling-reduction correcting direction is the same as that of the last time or not.