| 摘要 |
PURPOSE:To provide the device which prevents overcooling and permits the exact control of a treatment temp. for overaging by disposing gas cooling and roll cooling in this order to the titled device for constituting a continuous annealing installation for a steel strip and providing a preheater for temp. control therebetween. CONSTITUTION:Steel strip preheating parts 14 are respectively provided between a gas jet cooling part 11 and roll cooling part 12 of the cooling device 10 provided in the primary cooling zone of a continuous annealing furnace and between the cooling part 12 and an outlet 13 of the cooling device. The steel strip is first cooled down to the optimum cooling stop temp. at an optimum cooling rate from the prescribed strip temp. in the cooling part 11 right after the emergence from the holding zone in the case of a general steel strip as a drawing material. The steel strip is then conveyed to the overaging zone at the optimum start temp. for the aging treatment while the strip is preheated in the preheating part 14. The cooling part 12 is stopped during this time. On the other hand, the steel strip is preheated so as to permit the maintenance of the optimum temp. for starting the aging in the preheating part 14 from the holding zone up to the inlet of the cooling part 12 and is cooled down to the optimum cooling stop temp. at the optimum cooling rate in the cooling part 12 in the case of a high tensile steel strip. The optimum aging treatment is thus executed at the optimum aging temp.
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