METHOD FOR CONTROLLING TEMPERATURE OF PLATE IN CONTINUOUS ANNEALING INSTALLATION

PURPOSE:To decrease the absolute value in deviation by half by changing beforehand a target temp. according to the deviation in a plate thickness that arises owing to a change in the plate thickness when the part of a plate where the thickness changes passes a cooling roll group, returning the target temp. to the original target temp. and distributing uniformly the same to a high temp. side and a low temp. side after the part of the plate where the thickness changes passes the cooling roll group. CONSTITUTION:The target temp. of a steel plate X is beforehand changed to a high temp. side in the case of the conversion of a thick steel plate to a thin plate and to a low temp. side in the case of the conversion of a thin plate to a thick plate before the part of the plate X where the thickness changes enters the inlet side of a cooling roll 1. Vertically movable rolls 2 are moved upward and downward by the change in the target temp. and the contact length with the plate X begins to change. In the case of the conversion of a thick steel plate to a thin plate, that is, when the target temp. is changed to the high temp. side, the rolls 2 change in the direction where the temp. of the plate X is increased, or in the direction where the contact length is decreased. As a result, the temp. of the thick plate X is increased, and when the thickness is changed in this state and the thin plate arrives at the roll group 1, the contact length begins to decrease so as to increase the temp. of the plate X. The cooling of the thin plate is thus decreased as compared to the cooling in the prior art; therefore, the deviation to the low temp. side is suppressed.