ELECTROPLATING METHOD FOR HOT GALVANIZED STEEL SHEET AND CONTINUOUS GALVANIZING PRODUCING LINE

摘要

PURPOSE:To make the above line continuous and to efficiently produce a plated steel sheet having an electroplated composite layer excellent in coating property by arranging a hot galvanizing post-treating device in the interval until an electroplating device after performing hot galvanizing in the continuous plating producing line. CONSTITUTION:A steel sheet wherein washing and annealing have been performed is regulated at the temp. proper for plating in a cooling furnace 6. Thereafter both sides or single side of the steel sheet is galvanized in a hot galvanizing bath tank 7. Furthermore at least one or more hot galvanizing post-treating devices 9 are arranged and the surface of the hot galvanized steel sheet is treated by strong alkali. Successively it is washed with water dewatered and thereafter refining and rolling are performed to smoothen the surface of the galvanized steel sheet. This steel sheet treated by various hot galvanizing post-treatment is successively led to an electroplating device 14 and electroplating is performed on the upper layer thereof. Successively in accordance with necessity, surface treatment due to chromate treatment, zinc phosphate treatment or resin coating by a roll coater, etc., is performed to obtain a final product.