Abstract: Helper rolls in a continuous annealing furnace are divided by a master speed hearth roll serving as the boundary into a plurality of control blocks disposed forwardly and rearwardly of the master speed hearth roll, and the speed of rotation of the master speed hearth roll is used as a reference speed. Tension of a steel strip are continuously controlled on the basis of values detected by a tension meter in the plurality of control blocks towards the inlet of the furnace for the helper rolls disposed forwardly of the master speed hearth roll and towards the outlet of the furnace for the helper rolls disposed rearwardly of the master speed hearth roll.

Abstract: A steel strip continuous annealing furnace comprises a heating zone, a soaking zone and cooling zones, wherein bridle rolls for isolating tension of a steel strip from those in adjacent sections of the steel strip are provided at the inlet and outlet of the furnace and in the furnace so as to define a plurality of tension control blocks and provide tension control mechanisms for controlling the tensions of the steel strip in the respective tension control blocks, so that appropriate tensions can be rendered to the steel strip in the respective zones of the furnace, thereby enabling to secure the safe and satisfactory operating conditions.