When the tracking point reaches the i-th stand, the continuous rolling system outputs, to an i-th stand, a roll gap operation value for bringing to zero a difference between a value which is obtained by correcting a strip thickness target value of the i-th stand with a target strip thickness correction value of the i-th stand and a value which is obtained by correcting a strip thickness actual recalculation value of the i-th stand with a gap correction value of the i-th stand. Here, the gap correction value is a correction value that brings to zero a difference between a head end gap error when a head end of the material to be rolled reaches the i-th stand and a non-head end gap error when a part other than the head end of the material to be rolled reaches the i-th stand.

When the tracking point reaches the i-th stand, the continuous rolling system outputs, to an i-th stand, a roll gap operation value for bringing to zero a difference between a value which is obtained by correcting a strip thickness target value of the i-th stand with a target strip thickness correction value of the i-th stand and a value which is obtained by correcting a strip thickness actual recalculation value of the i-th stand with a gap correction value of the i-th stand. Here, the gap correction value is a correction value that brings to zero a difference between a head end gap error when a head end of the material to be rolled reaches the i-th stand and a non-head end gap error when a part other than the head end of the material to be rolled reaches the i-th stand.

The present disclosure provides a strip thickness control device for a hot rolling mill that can reliably pass a leading end of a material-to-be-rolled without raising equipment cost even in a case of rolling the material-to-be-rolled extremely thinly. The strip thickness control device for a hot rolling mill includes a strip thickness meter installed at a delivery side of a last one of rolling stands in a series direction, a gap calculating unit that calculates a gap between rolls in each of the rolling stands, the gap being larger than a product target strip thickness of the material-to-be-rolled and corresponding to a passable strip thickness that enables a leading end of the material-to-be-rolled to be passed stably, a gap setting unit that sets the gap calculated by the gap calculating unit for each of the rolling stands, an automatic strip thickness control unit that executes automatic strip thickness control of minimizing a strip thickness deviation between a strip thickness measured value of the strip thickness meter and the passable strip thickness, and a target strip thickness changing unit that changes the passable strip thickness to the product target strip thickness by adding a strip thickness bias to the strip thickness deviation at a predetermined ramp rate after the leading end of the material-to-be-rolled is passed through the last one of the rolling stands.

The present disclosure provides a strip thickness control device for a hot rolling mill that can reliably pass a leading end of a material-to-be-rolled without raising equipment cost even in a case of rolling the material-to-be-rolled extremely thinly. The strip thickness control device for a hot rolling mill includes a strip thickness meter installed at a delivery side of a last one of rolling stands in a series direction, a gap calculating unit that calculates a gap between rolls in each of the rolling stands, the gap being larger than a product target strip thickness of the material-to-be-rolled and corresponding to a passable strip thickness that enables a leading end of the material-to-be-rolled to be passed stably, a gap setting unit that sets the gap calculated by the gap calculating unit for each of the rolling stands, an automatic strip thickness control unit that executes automatic strip thickness control of minimizing a strip thickness deviation between a strip thickness measured value of the strip thickness meter and the passable strip thickness, and a target strip thickness changing unit that changes the passable strip thickness to the product target strip thickness by adding a strip thickness bias to the strip thickness deviation at a predetermined ramp rate after the leading end of the material-to-be-rolled is passed through the last one of the rolling stands.