DEVICE FOR CONTINUOUSLY COOLING STEEL SHEET BY GAS JET

PROBLEM TO BE SOLVED: To restrain the flow-in and the flow-out of non-oxidizing gas into the other treating zone or treating device at the front and the rear parts of a cooling device, to reduce the supply of hydrogen and to easily and constantly hold the non-oxidizing gas concn. in the cooling device by arranging at least the outlet side seal part of a steel sheet at the lower part of the vertical type forcedly cooling device using the non-oxidizing gas having high hydrogen concn equal to or higher than a specific value. SOLUTION: In a continuous annealing line process, the heated, soaked and further, slow-cooled steel sheet is passed through the cooling zone from the inlet side seal part A of the steel sheet arranged at the lower part of the cooling zone. This cooling zone is provided with a cooler for cooling the non-oxidizing gas having >=50% hydrogen concn. in the inner part of the device and a blower for blowing the cooled gas to the steel sheet. The steel sheet is cooled to a prescribed temp. in the cooling zone and passed to a treating zone at the latter step from the outlet side seal part B arranged at the lower part of the cooling zone. In such a case, the seal device is constituted of one set of faced seal rolls, but any device for preventing the flow-out/in of the atmospheric gas in the inner part of the cooling zone is allowed to be used.