| 摘要 |
PURPOSE:To prevent the generation of galling at the press processing of plated steel sheet, by applying specifically prepared solution of chromic acid solution and silica sol on the surface of the plated steel sheet and moreover, applying an aqueous solution of polyvinyl alcohol and drying it. CONSTITUTION:Plated steel sheet is continuously passed through and immersed in the bath filled up with a solution consisting of silica sol and 2-4% chromic acid solution at 1/15-1/30 volume ratio and the sticking quantity to the steel sheet is suitably controlled by roll squeeze or air blow. Next, said sheet is immersed in the aqueous solution of 3-25g/l polyvinyl alcohol and is squeezed by a rubber roll and then, is dried by hot air. Thus, the galling during press processing is effectively prevented by the coating formed on the plated steel sheet. |
