Patent ID: 6280596
Filing Date: 2001-08-28
Classification: B03C,B08B,B21B,C23C,C23G,C25D,Y02P,Y10T

Abstract:
Process for eliminating surface dissolution of iron during electrolytic tinplating of continuous-strip flat-rolled steel substrate in a horizontally-oriented plating line, comprisingA. providing continuous-strip flat-rolled steel substrate of preselected width presenting opposed substantially-planar surfaces;B. preparing such planar surfaces for electrolytic tinplating;C. providing a horizontally-oriented electrolytic tinplating line with a plurality of plating cells sequentially located in-line, includingan entry cell which provides sole access, for plating purposes, of such steel substrate into such tinplating line;D. providing acidic stannous-ion electrolytic plating solution in such plurality of plating cells;E. directing such continuous-strip for horizontally-oriented travel in which such opposed planar surfaces present a bottom surface and a top surface during such travel;F. submerging soluble tin anode bar means in such plating solution in such plurality of plating cells including such entry cell, withsuch submerged anode bar means confronting such bottom surface of such steel substrate, in substantially-uniformly spaced relationship therefrom, across such preselected width of such continuous-strip flat-rolled steel substrate;G. providing electrical power supply means for establishing plating current in such anode means in such plurality of plating cells;H. locating roll means externally of such plurality of plating cells, for:(i) polarizing such strip cathodically in relation to such submerged anode means, and(ii) directing travel of such continuous-strip flat-rolled steel substrate horizontally, through such plurality of plating cells, with such bottom surface of such steel substrate confronting such submerged anode means;I. controlling plating current established in such submerged anode means, forelectrolytically tinplating such bottom surface of such steel substrate, confronting such submerged anode means, andJ. substantially eliminating dissolution of iron from such top surface, into such acidic stannous-ion electrolytic plating solution in such plurality of plating cells, by carrying out the following steps:(i) modifying such entry cell for access into such horizontally-oriented plating line, by:(a) raising plating solution surface level in such entry cell, so as to enable(b) submersing a second soluble-tin anode means, confronting such remaining top surface of such steel substrate,(c) dissolving stannous ions, from such second anode means, into such plating solution for plating such top surface,(d) establishing plating current in such second-anode means, independently of establishing plating current in such submerged anode means,(e) electrolytically tinplating such top surface simultaneously with such bottom surface upon entry into such plating line, and(f) substantially preventing dissolution of strip surface iron into such plating solution.