Method for operating an annealing furnace

A method for operating an annealing furnace (200) for annealing a metal strip, comprising the following steps:

• selecting a desired target material property (MPTarget), to be assumed by a point or section of the metal strip (100) after passing through the annealing furnace (200), the target material property (MPTarget) being one of a yield strength, a tensile strength, an elongation at break and a uniform elongation;
• providing information (E) relating to the metal strip in front of or in the annealing furnace (200);
• calculating a target temperature distribution (TTarget) and/or a target speed (VTarget) of the metal strip (100) in the annealing furnace (200) by a computer-aided model (220) as a function of the desired target material property (MPTarget) and the information (E) relating to the metal strip;
• setting the target temperature distribution (TTarget) and/or the target speed (VTarget) of the metal strip (100) in the annealing furnace (200) by a furnace control system (230) as a control element;
• measuring an actual material property (MPActual) of the metal strip (100) after passing through the annealing furnace (200);
• calculating a comparative temperature distribution (TComp) and/or a comparative speed (VComp) of the metal strip (100) in the annealing furnace (200) with by the computer-aided model (220) as a function of the measured actual material property (MPActual) of the metal strip (100) after passing through the annealing furnace (200) and the information (E) relating to the metal strip in front of or in the annealing furnace (200);
• and
• adjusting the temperature distribution and/or the speed of the metal strip (100) in the annealing furnace (200) to the comparative temperature distribution (TComp) and/or the comparative speed (VComp) through adapting of the computer-aided model;
• wherein the adapting of the computer-aided model takes place only after the passing of at least the entire metal strip through the annealing furnace (200), and
• wherein the adapting of the computer-aided model comprises the sub-steps of
• measuring an actual temperature distribution (TActual) and/or an actual speed (VActual) of the metal strip (100) in the annealing furnace (200),
• comparing the actual temperature distribution (TActual) with the calculated comparative temperature distribution (TComp) and determining a temperature deviation (ΔT);
• and/or
• comparing the actual speed (VActual) of the metal strip (100) in the annealing furnace (200) with the comparative speed (VComp) and determining a speed deviation (ΔV);
• calculating at least one adaptation value (a) for adjustment of the computer-aided model (220) based on the temperature deviation (ΔT) and/or the speed deviation (ΔV);
• adapting the computer-aided model (220) based on the adaptation value (a);
• and
• recalculating the target temperature distribution (TTarget) and/or the target speed (VTarget) of a new metal strip (100) by the adapted computer-aided model (220), and
• wherein the information (E) relating to the metal strip (100) before or in the annealing furnace (200) is selected from the group consisting of
• a tensile strength and/or a yield strength before a continuous galvanizing line (CGL), before a continuous annealing line (CAL), in a pickling line, or before a reel,
• a reel temperature,
• a final rolling temperature of the metal strip upon exiting a finishing roll train,
• an input temperature of a slab from which the metal strip is produced, at the input of the finishing roll train,
• a strip speed of the metal strip upon exiting a last stand of the finishing roll train,
• a rolling force in a skin pass mill,
• rolling forces during cold rolling,
• rolling forces during hot rolling,
• an input temperature of the slab into a roughing stand in front of the finishing roll train,
• a cold rolling grade,
• a composition of a material of the metal strip,
• a carbon content of the metal strip;
• and
• a straightening force at a flattener in front of the CGL/CAL.