Method for calculating plate thickness schedule for tandem rolling machine and rolling plant

A rolling plant comprising:

• a plurality of rolling stands;
• roll gap control devices each provided in each rolling stand of the plurality of rolling stands;
• electric motors each rotating rolls in each rolling stand;
• and
• a process computer configured to calculate a plate thickness schedule of each rolling stand based a first value, the first value being one of a roll force ratio of the roll gap control device and a motor power ratio of the electric motor, wherein
• the process computer is configured to
• acquire a rolling model formula including a first value which is one of a roll force ratio and a motor power ratio in each of a plurality of rolling stands,
• determine whether or not a second value is restricted by parameter restriction, the second value is at least one value of roll force, motor power, and a reduction rate in each of the rolling stands,
• select one derived function from a first derived function and a second derived function to use the one derived function as a derived function of an evaluation function, the evaluation function evaluate an error based on the first value, the first derived function is a function configured to satisfy a ratio of the first value, the second derived function is defined in advance so that the second value is set in accordance with the parameter restriction, each derived function for each rolling stand is selected in accordance with a result of the determination so that the first derived function is selected when the parameter restriction does not occur and the second derived function is selected when the parameter restriction occurs, and
• modify each delivery side plate thickness in each rolling stand using a matrix including the one derived function selected from the first derived function and the second derived function in accordance with the result of the determination.