Method of controlling operation of tandem rolling mill and method of manufacturing hot-rolled steel sheet using the same

A method of controlling operation of a tandem rolling mill which comprises N stands (N being an integer of 2 or more) and in which a tightening load is pre-applied to each of the (N−m+1)-th stand (m being an integer of one or more and N or less) to the N-th stand before a material to be rolled is fed thereinto,

• the method comprising an exit side sheet thickness determination step of determining a sheet thickness on an exit side of each of the first stand to the N-th stand,
• wherein the exit side sheet thickness determination step comprises:
• a first exit side sheet thickness determination step of determining sheet thicknesses on the exit sides of the first stand to the N-th stand in rolling a constant portion of the material to be rolled;
• and a second exit side sheet thickness determination step of determining sheet thicknesses on the exit sides of the first stand to the N-th stand in rolling a front end portion of the material to be rolled, such that the tightening load to be pre-applied to the stands becomes a preset tightening load or less;
• the material to be rolled is rolled to have the exit side sheet thickness determined in the second exit side sheet thickness determination step, until at least the front end portion of the material to be rolled is fed into each of the stands;
• the constant portion of the material to be rolled is rolled by the (N−m+1)-th stand to the N-th stand to have the exit side sheet thickness determined in the first exit side sheet thickness determination step;
• and
• the sheet thicknesses on the exit sides of the (N−m+1)-th stand to the N-th stand determined in the second exit side sheet thickness determination step are larger than the sheet thicknesses on the exit sides of the same stands determined in the first exit side sheet thickness determination step.