| 摘要 |
<p>1,221,349. Coating by hot-dipping. ARMCO STEEL CORP. May 1, 1968 [May 10, 1967], No. 20599/ 68. Heading C7F. Ferrous metal strip is coated with molten metal by (a) cleaning the surface of the strip and bringing its temperature to that of the molten coating metal (b) passing the strip through a bath of molten coating metal and withdrawing it in a generally vertical path of travel (c) impinging a substantially laminar flow jet of gaseous fluid on the surface of the strip as it emerges from the bath at a height where the thickness of the coating metal is in excess of the desired final coating thickness, the impinging jet returning a continuous flow of the molten metal to the bath while a desired quantity of molten coating metal adheres to the strip and (d) contouring the narrow dimension of the gaseous jet across a portion thereof so as to proportion the wiping effect and leave a uniform coating thickness across the entire width of the strip. For instance, bowing of the strip is compensated for by widening the nozzle across part of its length, this being achieved by using a nozzle of the kind described in U. S.A. Specification 3, 314,163. The maximum velocity of the jet should be at the point of exit from the nozzle, and there should be a sharp velocity gradient across the narrow dimension of the jet, to avoid turbulence and consequent distortion of the coating, which may be of Zn, Al, or terne.</p> |
