FACILITY AND METHOD FOR CONTINUOUSLY MANUFACTURING HOT-DIP GALVANIZED STEEL SHEET

摘要

A facility for continuously manufacturing a galvanized steel sheet includes a continuous annealing furnace, a snout, and a galvanization bath. The furnace is divided into a heating zone, a soaking zone, and a cooling zone. The bath is directly connected to the furnace through the snout. The facility has a dewpoint meter and a draft port and a suction port for a furnace gas that are provided in at least one of the zones, gas cyclic paths which connect the draft port and the suction port to a refiner, and a dewpoint meter and a humidification device that are provided in the snout. The gas cyclic paths are separately formed for the respective connected zones. The refiner functions so that a measured value of the dewpoint meter is equal to a target dewpoint, and the humidification device functions so that a measured value of the dewpoint meter in the snout is equal to a target dewpoint for the snout.

主权项

1. A facility for continuously manufacturing a galvanized steel sheet, comprising:
a continuous annealing furnace divided into three zones including a heating zone that heats a steel strip which is a strip-shaped steel sheet to be passed through the furnace, a soaking zone that soaks the heated steel strip, and a cooling zone that cools the soaked steel strip, which are arranged in this order from an upstream side of a transport path; a galvanization bath; a snout that directly connects the furnace to the galvanization bath therethrough, the snout being a closed space through which the steel strip is directly fed into the galvanization bath from the furnace; a first dewpoint meter and a suction port and a spray port for a gas within the furnace that are provided in at least one of the three zones of the furnace; a gas cyclic path that connects the suction port and the spray port to a refiner, which is a moisture removing device provided outside the furnace, separately formed for each of the connected zones; and a second dewpoint meter and a humidification device, which humidifies an inside of the snout, that are provided in the snout, wherein: the refiner functions so that, for each of the gas cyclic paths, a first measured value of the first dewpoint meter in the connected zone is equal to a first target dewpoint; and the humidification device functions so that a second measured value of the second dewpoint meter in the snout is equal to a second target dewpoint for the snout.