Manufacture of galvanized steel sheet and device therefor

PURPOSE:To manufacture a galvanized steel sheet free from surface defects caused by dross or the like. CONSTITUTION:A plating soln. is pumped out from a plating tank 1 into an auxiliary tank 2 by using a metallic pump 6. Al is added thereto to float and separate dross as top dross, and its components are regulated into a clean soln. Then, it is circulated in the plating tank 1 by using a metallic pump 7 and is sprayed from a spraying nozzle 5 on the surface of a steel sheet 3 in a plating bath. In this way, the surface defects of the galvanized steel sheet can remarkably be reduced.