PAINTING LINE FOR STEEL SHEET COIL

摘要

PURPOSE:To produce inexpensively and efficiently a precoated steel sheet having excellent quality by disposing an Zn electroplating installation in common use as an anodic electrolytic treatment installation before a chemical conversion treatment part of a painting line. CONSTITUTION:The strip is passed through the Zn electroplating installation 9 in common use as the anodic electrolytic treatment installation prior to the passage thereof through the chemical conversion treatment installation 10 after the strip is subjected to the pretreatment of the chemical conversion treatment in a painting line for a steel sheet coil. The Zn electroplating installation is used to execute thin plating to about 2-15g/m<2> by which troubles such as burnt deposit, uneven plating and nonuniform alloy compsn. are prevented. The chemical conversion treatability of the steel sheet is positively improved by an electrode polarity change-over device in the case of using the cold rolled steel sheet as a blank material without regarding important the corrosion resistance thereof according to the applications of the precoated steel sheet. The strip treated by the installation 9 in the above-mentioned manner is fed to the chemical conversion treatment installation 10.