| 摘要 |
PROBLEM TO BE SOLVED: To prevent the occurrence of flow marks with relatively low plating weight and to efficiently execute hot dip galvanizing small in dispersion and good in surface properties by executing wiping treatment in which the injection pressure of a nozzle and the interval between the nozzle and the steel sheet to be passed are controlled in accordance with sheet thickness and the plating weight. SOLUTION: A steel sheet passed through a hot dip balvanizing bath is taken up from the plating bath face, and a wiping gas is injected onto the surface to regulate the plating weight, by which a hot dip galvanized steel sheet is obtd. In the case the plating weight per one side of the hot dip galvanized steel sheet is 30 to 100 g/m<2> , the injection pressure of a nozzle and the interval between the nozzle and the steel sheet to be passed are controlled in accordance with the sheet thickness and the plating weight, and wiping treatment is executed. In the case the plating weight is defined as W g/m<2> , the injection pressure of the nozzle as P kg/cm<2> , and the interval between the tip of the nozzle and the steel sheet to be passed as d mm, the control is executed so as to satisfy the inequality: d<=αW<1/2> and the expression: P=β+γ(α,βandγare constants decided in accordance with the line speed, the sheet thickness and the condition of the bath).
|
