METHOD FOR CONTROLLING TENSION OF LOOPER

PURPOSE:To prevent a running trouble such as meandering by providing a tension to a strip at the small crosssectional-area side in correspondence with the tension of a strip at the large crosssectional-area side at the time when the tension of a metallic strip is changed due to the change of the crosssectional area of strip. CONSTITUTION:Moving-side looper rolls 15, 16 connected to each other by a carriage 14 are installed oppositely to the fixed-side looper rolls 12, 13 of a looper 4. The rolls 15, 16 are advanced and retreated by the carriage 14 which is moved through a wire 17 by rotating a drum 18, to control the tension of a strip ST. When a succeeding strip ST having a large crosssectional area arrives and a detection signal of crosssectional area is outputted from a changing-point detector 28, the rotational torque of a looper motor 19 increases and the tension of wire 17 is increased by the movement of drum 18. Accordingly, the slack of a preceding strip ST is eliminated and a running trouble such as meandering is prevented.