Patent ID: 7775080

Claim:
A rolling method for a flat-rolled metal material, for executing rolling by using rolling equipment including a rolling mill ( 1 ) and at least a pair of pinch rolls ( 11 , 12 ) for clamping a rolled material ( 13 ) on the exit side of said rolling mill having a construction in which either one, or both, of upper and lower roll assemblies have a mechanism for supporting a work roll ( 3 , 4 ), by split backup rolls ( 5 , 6 ) split into at least three segments in an axial direction, said split backup roll group having a construction for supporting both a vertical direction load and a rolling direction load acting on said contacting work roll and each of said split backup rolls independently having a load measuring device ( 9 , 10 ), said method comprising the steps of: calculating a difference Fr df between rolling direction force acting on said work rolls ( 3 , 4 ) at a right side (operator side) of said work rolls and rolling direction force acting on said work rolls ( 3 , 4 ) at a left side (driving side) of said work rolls through the rolled material using imaginary rolling direction force F R W and F R D acting between the rolled material and the work roll evaluated at the work roll chock position on the operator side and the driving side based on a measured value of backup roll load measured on each segment of said split backup roll by each independent load measuring device and the formula below: F R W −F R D =(2/ a w )Σ Z i q i cos θ i −( F w −F D ), controlling left-right difference of roll gap of said upper work roll and said lower work roll to result in said calculated difference Fr df of rolling direction force approaching zero; where, F R W and F R D are imaginary rolling direction force when the rolling direction forces acting between the rolled material and the work roll are evaluated at the work roll chock positions on the operator side and the driving side, respectively; q i is the measurement value of the ith split backup roll load; θ i is an angle between each split backup roll load operation line direction and the horizontal line (entry side split backup roll has an acute angle and exit side split backup roll has an obtuse angle); Z i is the barrel length center position of each split backup roll expressed by roll axial direction coordinates with a mill center being an origin; a w is a center distance between an operator side chock and a driving side chock; F W and F D are the actual values of the horizontal direction roll bending force acting on the work rolls on both operator and driving sides, wherein F W and F D may be omitted when the horizontal roll bending force is not provided.