Patent ID: 9598756
Date: 2017-03-21
CPC Classifications: C23C

Claim:
1. A method for producing a hot dip plated steel sheet, the method comprising: continuously immersing a steel sheet in a plating bath; pulling up the steel sheet having a plating metal adhered on a surface of the steel sheet from the plating bath; controlling a coating weight of the plating metal on the surface of the steel sheet with a wiping gas injected through a gas wiping nozzle toward two surfaces of the steel sheet from when the steel sheet is pulled up from the plating bath to when the plating metal adhered on the surface of the steel sheet is solidified; and shielding two edges of the steel sheet at a position where the wiping gas collides with the steel sheet pulled up from the plating bath, by using a seal box, wherein a surface of the plating bath is exposed to an air atmosphere so that the surface of the plating bath is covered with an oxide film, wherein the seal box includes wherein the seal gas forms a gas curtain which acts as a barrier blocking ambient atmosphere so that the seal box and the gas curtain define a space which is insulated from the ambient atmosphere and in which an oxygen concentration is controlled by the inert gas to at least 0.05 vol % to no more than 3 vol % when the wiping as is injected toward the two surfaces of the steel sheet, wherein the space includes a region, which is from the edges of the two surfaces of the steel sheet to 50 mm or more in the sheet width direction towards a center of the steel sheet and at which the gas collides with the steel sheet, and excludes the surface of the plating bath, wherein the seal box is disposed on the gas wiping nozzle, and wherein the gas wiping nozzle is configured to move so that a distance between the periphery of the opening of the seal box and the two surfaces of the steel sheet is controlled within a range of 3 to 200 mm.