METHOD FOR SETTING ATMOSPHERE IN CONTINUOUS ANNEALING FURNACE

• Main Authors: ISHIZAKI KAZUNARI, UENO TSUTOMU
• Format: Patent
• Language: English
• Published: 13.05.1997
• Edition: 6
• Subjects: CHEMISTRY; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS

PROBLEM TO BE SOLVED: To set a dew point under consideration of out of control range of oxygen additional quantity to the variation of the dew point developed in the case of changing over from the passing of an adjusting sheet to the passing of a proper sheet, at the time of continuously annealing a grain oriented silicon steel sheet. SOLUTION: In the case of changing over from the passing of the adjusting sheet to the passing of proper sheet in a decarburize-annealing furnace for supplying atmosphere summarizely from the rear step of the furnace, a formula showing the dew point distribution in the furnace is made based on the dew point at the inlet side in the furnace and a formula estimating the oxygen additional quantity to the steel sheet is made based on the dew point distribution in the furnace. Further, a model resembled to a dynamic characteristic of the dew point in the furnace in the case of changing over from the adjusting sheet to the proper sheet. The shifting of the oxygen additional quantity in the longitudinal direction of the proper sheet just after changing over from the adjusting sheet, is estimated based on this model and the formula estimating the oxygen additional quantity to the steel sheet. A dew point setting profile of the original gas in the atmospheric gas in the case of changing over from the adjusting sheet to the proper sheet, is decided so that the oxygen additional quantity does not exceed a pre-decided permissible range.