US1741388A - Metal coating metal sheets - Google Patents

Description

E. R. WEHR ET AL METAL COATING METAL SHEETS Filed Sept. 13, 1926 Dec. 31, I929.

211mm 0 W BY l C.W

A TTORNEYS Patented Dec. 31, 192 9 Y UNIT-ED STATES PATENT. oFfleE .EARL a warm AND can. 0. mun, or mrnnnnrown, onro, ASSIGHOBS ro' THE AMERICAN ROLLING MILL COMPANY, or mnmn'rown, 01110, A coaronmrron or onro 1 METAL COATING METAL SHEETS Application filed September 13!, 1926. Serial No. 185,275..

, Our invention relates specifically to the itsufliciently to render the fluxing problem formation of a coating on steel and iron sheets difiicult. 1

which consists on the surface at least of an With alloys high in aluminum as a coatalloyof zinc and aluminum, but inasmuch ing, we are fairly closely confined to the use as certain of the steps would also be apof commercially pure zinc, as themain body plicable to the formation of alloy coatings of the floating coating material. of different metals on metallic bodies ca- .By our -princess we can produce a continupable of being fed through a bath, the in- (ms succession of iron or steel sheets coated .ventionhas more general aspects as will subwith an alloy of zinc and aluminum, quite 1o sequently appear. high in aluminum, say up to twenty percent 60, In the coating of sheet metal by the methaluminum. Above twenty percent aluminum, od of feeding it through molten metal baths, the melting point of the alloy gets hi her and particularly with iron and steel, when than the meltin point of pure zinc, which subjected to surface treatments with metals introduces another problem that we avoid 16 which coat the iron, the problem of securvloy keepin below twenty percentaluminum. 6

ing a. proper coating is rendered difiicult be- Normally it will be of little value to vuse cause of the largearea which must be covthree percent or less of aluminum, as the? ered and because -of the distinctness with product produced does not vary sufliciently 'which any defect appears on the large flat to give the very decided novel product that 2 area. is produced by us. For example, a coating The process is also rendered diflicult due containin commercially pure zinc, and eight to'the fact that the ordinary fluxes can not percent 0 aluminum by weight to the zinc, be used on a bath consisting of zinc and as proven to be a radical departure and imaluminum because of the formation of alurovement over past roducts, and produci- 25 minum chloride (AlGl which volatilizes tile by our process wit out excessive expense,

readily at the temperature of the bath. with avoidance of any hand dipping, or flux- We employ as the main portion of the bath, ing previous. to introduction into the mamolten lead, with a flux box at the entrance chine. end, and an exit box at the exit end, in which We accomplish our objects by that certain 3 exit box is maintained afloatingmolten body process to be hereinafter more specifically of zinc aluminum alloy. pointed out and claimed.

' Our process has considerable by. Way of In the drawing, the figure is a diagram of advantage, due to the' fact that we preferequipment found by us to be satisfactory ably employ commercially pure zinc in formwith our process.

35 ing the zinc-aluminum alloy, Pure zinc will We have shown coating equipment having dissolve to a small extent in, the lead bath, a pot 1, with guides 2, exit rolls 4, and flux but the. lead, will be insufficiently changed box 5. The exitrolls have located alongside to'enable it to take u the aluminum. In of them stirring or skimming rolls 6.

machine processes, wit which we are dealpartition 7 extends downinto the pot divid- 40 ing, the continued assage of material 'ing the upper portion of the bath. The althrough the' bath, wit "continued additions loys we use deteriorate the pot rapidly, so

' of the floating alloyf in theexitcompartment that care must be taken in the metals used on the lead bathiswill soon deteriorate the in -aVQiding'a product soluble in the alloy.

bath, if this is possible: But lead will take In this -process,pure lead is melted in the i 45 up only so much zinc,fand this will noten: pot to the desired level. Zinc-aluminum al able it to dissolve "the aluminum to any aploy. is melted on top of the lead at the exit preciable extent, with the result that high end, and a small amount of pure zinc is aluminum alloys can be kept'atthe exit endymelted in the flux boxon top of the lead. of the machine, floating onrthe lead,'withou-t Anv" of the usual galvanizing fluxes can'be aluminum getting into the lead and defiling used on the zinc, such aai'saI-ammOmaC. The

use of pure Zinc at these points is desirable as against impure zinc spelters, Where the finish of the sheet is to be of the highest value and free from the typical spangle, and to avoid contamination of the zinc aluminum alloy at the exit end of the mechanism, and also for the reasons heretofore noted.

The level of the lead at the exit end is indicated at 8 upon which is the zinc-aluminum alloy 9. The level of the lead in the flux box is indicated at 10 and the zinc in the flux box at 11.

The cleaned metal sheet is passed through the flux 12 into the zinc where it becomes zinc coated and then down through the lead, which partially replaces the zinc coating, and up through the zinc-aluminum alloy, which replaces the lead, the final product being coated with zinc-aluminum alloy.

The advantage of using a molten zinc on which the flux is supported lies in the fact that where the metal to be passed down through a flux supported on the lead, the flux often adheres in spots which are subsequently coated over.

The percentage of aluminum in the zincaluminum alloy is maintained at any desired percentage. In one of our practices, we keep the alloy at around six per-cent aluminum, and in another we use eight per-cent.

We do not wish, however, to be excluded from covering the use of a flux directly on the lead even though the product is not so readily produced in uniform excellence, nor do we wish to be limited to pure zinc alone in some phases of our process. By reference to alloys of zinc and aluminum in the claims thatfollow, we do not wish to exclude the presence of small quantities of other metals, so long as the aluminum is the important alloying element with the zinc.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent, is

1. A process of coating metal sheets which consists of passing them through a flux into a molten body of zinc floating on a molten metallic bath of a heavier metal, down through said molten metallic bath of a heavier metal, and up through a molten metallic body containing zinc and alloying material and floating on the molten bath of a heavier metal said heavier metal being such as will not substantially absorb said zinc alloy.

2. A process of coating metal sheets which consists of passing them through a flux and into a molten body of purezinc floating on molten lead, and down into the molten lead bath of lead and up through a molten body of zinc-aluminum alloy floating on the molten lead bath, the zinc-aluminum alloy being kept from access to the flux.

4. A process of coating metal bodies having a plane surface which comprises passing them through a flux, through a bath of molten lead, and out through a molten alloy floating on the surface of the lead, in a continuous manner, said alloy composed of commercially pure zinc and aluminum.

5. A process of coating metal bodies having a plane surface which'comprise's passing them through a flux, through a bath of molten lead, and out through a molten alloy floating on the surface of the lead, in a continuous manner, said alloy composed of commercially pure zinc and aluminum, said aluminum being resent in quantities less than twenty Ipercent by weight of the zinc, and more than ve per cent.

6. A process of coating metal bodies having a plane surface which comprises passing them through a flux, through a bath of molten lead, and out through'a molten alloy floating on the surface of the lead, in a continuous manner, said alloy composed of commercially pure zinc and aluminum, said aluminum being present in quantities less than twenty percent by weight of the zinc, and over three percent by weight of the zinc.

EARL R. WEHR. CARL C. MAHLIE.

bathandthrough the lead bath up through a molten metal body containing zinc and aluminum floating on the lead.

3. A process of coating ferreous sheets which consists of passing them through a flux, into a molten body of pure zinc floating on a molten bath of lead, and through the molten

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