PLATE THICKNESS CONTROL DEVICE FOR MULTISTAGE ROLLING MILL

PURPOSE:To improve the accuracy of a plate thickness by correcting exactly a roller opening set value, when a rolling roller has been moved in the axial direction in the course of rolling. CONSTITUTION:When rollers 2A, 2B execute a change of a moving extent in the axial direction, a gate 10 is closed for a while and a storage device 11 stores it as a rolling load P* before a start of said change based on load detectors 8A, 8B, also inputs it to an arithmetic unit 13, and a plate width B of a rolling material 1, which has been set in advance by a setting device 12 is also inputted to the unit 13. The unit 13 calculates a mill elastic deformation quantity Sm1 from input signals P*, B at the time of inputting a pulsative signal from a control device 5 for moving extent in rollers 2A, 2B axial direction, and an effective barrel length Le by an arithmetic unit 7 for effective barrel length Le, based on detectors 6A, 6B for moving extent in rollers 2A, 2B axial direction. Thereafter, in the same way, a deformation quantity Sm2 is calculated, a difference S of both of them is outputted to a rollers 2A, 2B opening control device 14, and the device 14 drives rolling reduction driving devices 15A, 15B in accordance with the signal S, and corrects and controls the opening between the work rollers 2A, 2B.