Roll wear dispersion method for rolling stand and rolling system

A roll wear dispersion method for a rolling stand that rolls a rolling target material, wherein the rolling stand comprises:

• a pair of work rolls including an upper work roll and a lower work roll in which roll diameter distributions thereof in an axial direction are expressed by cubic or higher-order polynomials, wherein the upper work roll and the lower work roll are opposed to each other;
• a work roll shifter configured to shift each of the upper work roll and the lower work roll in the axial direction;
• and
• a roll gap adjuster configured to change a work-side roll gap and a drive-side roll gap of the pair of work rolls by changing a work-side screw down position and a drive-side screw down position, and
• wherein the roll wear dispersion method comprises:
• calculating an opposite direction shift amount for the upper work roll and the lower work roll such that a plate crown and flatness of the rolling target material on an exit side of the rolling stand are within predetermined ranges;
• calculating a same direction shift amount for the upper work roll and the lower work roll that disperses wear of the pair of work rolls;
• based on the same direction shift amount, calculating a screw down position difference of the roll gap adjuster that makes a roll gap difference between both edge portions in a width direction of the rolling target material close to zero;
• and
• causing the work roll shifter to shift each of the upper work roll and the lower work roll based on a total value of the opposite direction shift amount and the same direction shift amount, and causing the roll gap adjuster to change the work-side screw down position and the drive-side screw down position based on the screw down position difference.