PURPOSE:To bright-anneal a band steel wider and thinner than before with excellent flatness by holding a wide thin band steel in a first annealing zone at a specified temp. at the of brightannealing the steel band, etc., in a horizontal continuous annealing furnace having the heating zone, first annealing zone and a second annealing zone. CONSTITUTION:The horizontal continuous annealing furnace consisting of a heating zone 2 having a heater 7, the first annealing zone 3, a connection zone 4, and the second annealing zone 5 is used, when a wide thin band steel or a wide band foil 1 is bright-annealed. A support roll 10 having 200-600mm outer diameter identical to the outer diameter of a hearth roll 12 in the second annealing zone 5 is arranged at the outlet from the heating zone 2 and at the inlet to the first annealing zone 3, the first annealing zone 3 has the same structure as that of the heating zone 2, a furnace temp. controller 6 is provided in both zones 2 and 3 to prevent the supercooling of the band steel 1 leaving the heating zone 2 in the first annealing zone 3, and the thermal compressive stress exerted on the band steel 1 is controlled. The band steel 1 is then annealed with an atmospheric gas in the second annealing zone 5, and the deformation of the band steel in the cooling process is prevented.
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