A method for rolling a metal strip in a finishing train, wherein the metal strip is comprised of a plurality of sections along the metal strip and wherein the finishing train has multiple rolling stands through which the metal strip passes in succession, the method comprises:
- detecting the actual width (b0) and the actual temperature (T0) of each of the sections of the metal strip before each section enters the finishing train;
- deriving a respective actual width (b) from the detected actual width (b0), a respective initial target width (b0*), a respective actual temperature (T) derived from the detected actual temperature (T0), and a respective target temperature (T*) which are respectively associated with each of the sections of the metal strip;
- path-tracking the sections of the metal strip during the passage of the metal strip through the finishing train;
- associating a width control unit at least with each of the rolling stands, except the last rolling stand in succession of the plurality of rolling stands;
- the respective width control unit for the section of the metal strip which is rolled in the associated rolling stand;
- on the basis of all of said initial target width (b*) before the rolling in the associated rolling stand, a target tension (Z1*) desired in the metal strip before a rolling in the associated rolling stand, a target tension (Z2*) desired in the metal strip after the associated rolling stand, the target temperature (T*) associated with the respective section of the rolling strip and parameters (P) of the rolling procedure performed in the associated rolling stand, the respective width control unit ascertains a target width (b*) after the rolling in the associated rolling stand and associates it with the respective section of the metal strip;
- on the basis of all of the actual width (b) of the metal strip before the rolling in the associated rolling stand, the target tension (Z1*) of the metal strip, which is corrected by an upstream additional target value (δZ1*), which is desired in the metal strip before the associated rolling stand, correcting the target tension (Z2*) by a downstream additional target value (δZ2*), which is desired in the metal strip after the associated rolling stand, the actual temperature (T) associated with the respective section of the metal strip, and the parameters (P) of the rolling procedure performed in the associated rolling stand, the respective width control unit ascertains an actual width after the rolling of the metal strip in the associated rolling stand and associates it with the respective section of the metal strip;
- using the respective width control unit to ascertain the downstream additional target value (δZ2*) on the basis of the target tension (Z2*) desired in the metal strip after the associated rolling stand, the target temperature (T*) and the actual temperature (T) of the section of the metal strip rolled in the associated rolling stand, the difference (δb) of a target width (b*) and the actual width (b) of a section of the metal strip which is located at a predetermined point after the associated rolling stand, and the parameters (P) of the rolling procedure;
- using the respective width control unit to ascertain the downstream additional target value (δZ2*) such that the actual width (b) of the rolled section of the metal strip rolled in the associated rolling stand approximates the target width (b*) of the rolled section;
- and
- using the respective width control unit to supply the downstream additional target value (δZ2*) to a respective tension regulator, which sets an actual tension prevailing in the metal strip after the associated rolling stand and the actual tension corresponds to the target tension (Z2*) corrected by the downstream additional target value (δZ2*).