Method, computer program and rolling mill train for rolling a metal strip

Method of cold rolling a metal strip (200) in a tandem rolling mill train with 1≦n≦N wherein N corresponds to the total number of active rolling stands arranged one after the other in a rolling direction with N being two or more as desired, comprising the following steps:

• a) setting a roll gap of an n-th active rolling stand (300) to a predetermined first initial pass thickness Dk,n where k=1 so that the first initial pass thickness D of the roll gap is smaller than a thickness of a metal strip head (210) defining a beginning end of the metal strip;
• thereafter
• b) transporting the metal strip in the rolling direction toward the n-th active rolling stand with the strip head (210) facing the n-th rolling stand (300);
• thereafter
• c) continuously passing the metal strip including the metal strip head through the roll gap of the n-th active rolling stand to reduce the thickness of the metal strip and the metal strip head to the first initial pass thickness Dk=1,n of the roll gap of the n-th active rolling stand;
• d) setting a roll gap of the n+1-th active rolling stand (300) to a predetermined initial pass thickness Dk=1,n+1, which is smaller than the first initial pass thickness Dk=1,n of the n-th active rolling stand;
• e) transporting the metal strip in the rolling direction to the n+1-th active rolling stand with the strip head facing the n+1-th rolling stand;
• thereafter
• f) continuously passing the metal strip including the metal strip head through the roll gap of the n+1-th active rolling stand to reduce the thickness of the metal strip and the metal strip head to the initial pass thickness Dk=1,n+1 of the roll gap of the n+1-th active rolling stand;
• g) building up a tensile stress in the metal strip between the n-th and the n+1-th active rolling stands after the strip head reaches the n+1-th rolling stand and before the strip head reaches a winder located downstream in the rolling direction of the N-th rolling stand;
• characterized by:
• h) reducing the initial pass thickness of the roll gap of the n-th active rolling stand in accordance with the built-up tensile stress between the n-th and the n+1-th active rolling stands, to a second predetermined initial pass thickness D2,n which is smaller than the first initial pass thickness Dk=1,n of the n-th active rolling stand.