Gas wiping apparatus
In a gas wiping apparatus which blows gas through a wiping nozzle onto front and rear surfaces of a steel plate going out from a molten metal coating pot and running upward and which thereby controls a deposit mass, the wiping nozzle is separated into upper and lower lips, blocking faces partially closing a gas supply channel are formed in the upper and lower lips at vertically different positions on the opposite sides from each other in a gas outlet width direction, and the upper and lower lips are provided in such a manner as to be movable in a width direction of the steel plate.
1. A gas wiping apparatus configured to blow gas through a wiping nozzle onto front and rear surfaces of a steel plate going out from a molten metal coating pot and running upward and which thereby controls a deposit mass, the apparatus comprising:
the wiping nozzle, separated into an upper lip and a lower lip, wherein
blocking faces partially closing a gas supply channel are formed in the upper and lower lips at vertically different positions on opposite sides from each other in a gas outlet width direction, and
the upper and lower lips are configured to be independently movable with respect to each other in a width direction of the steel plate by a plurality of drive means in such a manner as to close a nozzle slit at a position coinciding with the plate width of the steel plate.
2. The gas wiping apparatus according to claim 1 , wherein recess portions are respectively formed, at such positions as to be always located near ends of the steel plate, in facing surfaces which form the nozzle slit of the upper and lower lips, so that a gap of the nozzle slit is made larger near the ends of the steel plate than near a center of the steel plate.
3. The gas wiping apparatus according to claim 1 , comprising:
plate end detection sensors respectively attached to the upper and lower lips so as to detect end portions of the steel plate; and
control means for controlling the drive means on a basis of detection signals from the plate end detection sensors so as to adapt the upper and lower lips to changes in position of the end portions of the steel plate.