DEVICE FOR CONTROLLING SHEET THICKNESS OF ROLLING MILL

PROBLEM TO BE SOLVED: To provide a device for controlling a sheet thickness of a rolling mill capable of decreasing a deviation of the sheet thickness of outlet side owing to eccentricity of a back up roll even in the case of rolling mills hardly allowing easy kiss-roll. SOLUTION: This controlling device is equipped with a thickness meter 8 mounted at an outlet side of a rolling mill to detect a deviation of the sheet thickness from a set value, a rotational angle detection means 9 to detect n pieces of rotational angles equally divided into n equal parts out of the rotational angle by one turn of a back up roll 2, a calculating means to calculate the length of a rolled material on the outlet side of a rolling mill corresponding to the length by one turn of the back up roll at a timing of output of a rotational angle detecting signal, a delay means 11 to delay a sheet thickness deviation signal by a material shifting time corresponding to a difference between the calculated length of a rolled material on the outlet side and a distance from the rolling mill to the thickness meter, and further a calculating means 12 to calculate a roll opening degree operating amount of the rolling mill which integrates the delayed sheet thickness deviation signals by every same rotational angle of the back up roll 2 detected by the rotational angle detecting means 9 and calculates respectively the roll opening degree operating amount of the rolling mill corresponding to the rotational angle of the back up roll 2, and thus operates the roll opening degree of the rolling mill according to the calculated roll opening degree operating amount.