Mec Company Ltd.

Sang-Ho Kim

The present invention relates to an apparatus and a method of manufacturing a hot dipped galvanized steel sheet that is excellent in corrosion resistance and has no linear defects, thereby being available for automobile bodies, household appliances, construction materials, and the like which need aesthetic surfaces. The apparatus for manufacturing a hot dipped galvanized steel sheet includes: a plating pot filled with a galvanizing bath for coating of a steel sheet; a sink roll; a wiping device adjusting the thickness of the coating on the steel sheet; a top roll; an oxidation process chamber; and an air cooling device. According to the present invention, after an excess molten coating solution attached to the steel sheet is evenly removed, an oxide film is made to be 0.1 &#x3bc;m to 0.3 &#x3bc;m thick before a coating layer starts to solidify. Thus, linear defects can be prevented.

Mg-comprising hot-dip galvanized steel sheet manufacturing method and manufacturing apparatus

The present invention relates to a molten metal plated steel sheet manufacturing method for cooling a molten galvanized layer with high efficiency when manufacturing a molten galvanized steel sheet, and the purpose of the present invention is to provide a method for manufacturing a molten galvanized plating, wherein a molten galvanized steel sheet having an aesthetically pleasing surface without fitting defects, drop mark defects, and linear comb-pattern defects can be stably obtained by cooling a galvanized layer with high efficiency during a molten metal plated steel sheet manufacturing process. This method for manufacturing a molten galvanized steel sheet having excellent surface properties is characterized by comprising the steps in which a molten galvanized layer is formed on the surface of a steel sheet while the steel sheet passes through a galvanizing pot, the thickness of the galvanized layer formed on the surface of the steel sheet is adjusted while the steel sheet passes through a gas wiping device, the steel sheet that has had the thickness of the galvanized layer adjusted undergoes a primary cooling while passing through a bottom cooler, and the galvanized steel sheet that has undergone the primary cooling undergoes a secondary cooling while passing through a cooling chamber, wherein: the primary cooling is performed with cooling air blown from the bottom cooler until right before a galvanizing solution of the galvanized layer attached to the surface of the steel sheet becomes solidified, the amount of air blown being adjusted according to the temperature of the galvanized layer attached to the surface of the steel sheet; and the secondary cooling is performed with ionic air generated from an ionic air generator provided in the cooling chamber and a spray solution sprayed from a solution atomization part, the secondary cooling being performed from the start of the solidification of the galvanizing solution until the end of the solidification, and the cooling chamber cooling the galvanized steel sheet while moving up and down according to the temperature of the galvanized layer attached to the surface of the galvanized steel sheet.

Growing community of inventors

Gwangyang-si, South Korea

Sang-Ho Kim