US406365A - Process of galvanizing metals - Google Patents

Description

(SpecimensJ T. 'MIDGLEY &-,'W. '13. NYE. PROCESS OF GALVANIZING METALS.

No. 406,365. Patented July 2, I889.

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' UNITED STATES PATENT OFFICE.

THOMAS MIDGLEY AND WALTER I). NYE, OF BEAVER. FALLS, PENNSYLVANIA.

PROCESS OF GALVANIZING METALS.

SPECIFICATION forming part of Letters Patent No. 406,365, dated July 2, 1889.

Application filed September 2, 1886.

To all whom it may concern.-

Be it kn own that we, THOMAS MIDGLEY and \VALTER B. NYE, citizens of the United States, residing; at Beaver Falls, in the county of Beaver and State of Pennsylvania, have invented certain new and useful Improvements in the Process of GalvanizingMetals ,and wedo hereby declare the following to beafull, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in galvanizing metals in different formssuch as wire, rods, strips,sheets, pipe, &c. There are various disadvantages attending the use or process of galvanizing heretofore practiced, either or allof which result in large loss, not only on account of injury caused to the material itself, but also because of the necessity of frequently repairing or replacing the pan which contains the bath. In. the first place the quality of the material is lessened when the zinc is deposited directlyupon it, it being a well-known fact that the efiect of zinc upon iron is to harden and give it a certain amount of temper, which is a disadvantage where flexibility is required, as in the case of galvanized wire. It is also well known that zinc in a melted state is extremely susceptible to oxidation, and as the bath ordinarily used has a large surface exposed to the air the loss on this account is considerable. There is also a certain percent age of loss occasioned by the chemical action of the acids generally used upon the zinc bath. Especial loss and disadvantage result in these old processes from the formation of what are known as dross and stodge, which in large establishments reaches very large proportions, not only from the expense of renewing the pans, but on account of the frequent stoppage of operations for that purpose.

The object of our invention is to overcome all these disadvantages, and thus produce a better quality of galvanized material by a much more economical process of manufacture.

Our process consists, first, in immersing the material after it has been treated with acid in the usual manner in a bath of molten lead and then passing it through a small body of $e1'ial No. 212,504. lSpecimens.)

melted zinc, which floats upon the surface of the lead, (by reason of its inferior specific gravity,) being suitably confined to prevent it from spreading over the surface of the lead bath. By thus confining the zinc Within a small space upon the surface of the lead any material to be treated passes first into and through the lead, and thence directly through and out of the zinc, from which it receives the coating. By this arrangement of the apparatus the surface of zinc exposed to the air is very small and the amount of oxidation correspondingly reduced. The injurious effect of the acid upon zinc'is also entirely obviated, since they are not brought in contact. Another important advantage arising from the use of this process is that the wire or other material in its passage through the lead is heated to a temperature nearly, if not quite, up to that of the zinc, and thus the hardening effect of zinc in a molten state upon metal at a normal temperature is entirely prevented. This heating of the material also tends to prevent the formation of dross, ordinarily caused by the great difference in temperature between the bath and the material exposed to it. By using the small body of zinc and restraining it in place by movable partitions the loss resulting from the affinity of zinc with the iron of the pan itself is also completely prevented, this action being restricted to the partitions themselves, which are easily removed and replaced at any time and at a small cost.

\Ve have devised an apparatus for carrying out our process, which is illustrated in the accompanying drawings, in which Figure 1 is a longitudinal section on theline 00 0c of Fig. 2. Fig. 2 is a plan view, and Fig. 3 is a cross-section on the line y y of Fig. 2.

A represents the large iron-lined pan, which contains a bath of molten lead kept in that condition by the application of heat in any suitable manner, or as hereinafter described.

B represents the zinc bath, which is formed by means of walls D D. This bath has an 7 open bottom which permits the lead to enter it to a certain height, as shown. It will be understood that the walls composing the zinc bath may be located at any point relatively to the pan A, their position being governed IOO by the nature and shape of the material under treatment. We have shown them in the drawings as supported at the exit end of the lead bath when used for galvanizing wire. \Vithin these retaining-walls is confined a body of melted zinc, which, by reason of its smaller specific gravity, floats upon the surface of the lead in the pan A.

E represents the acid bath, and a a designate rollers, by means of which the strands b of wire are fed and guided, passing from the acid bath directly into and through the molten lead, and being carried thence directly through the body of zinc, as shown.

F represents a cover over the zinc bath, and G a chamber, into whichthe products of combustion pass from a fire-box H, through cover F, out of pipe shown in drawings. Passages K extend along the sides of the pan A and are provided with ash-pits L beneath them. Both pans are thus heated and theirtemperature maintained at the same point.

Having thus described our invention, what we claim, and Wish to secure by Letters Patent, is as follows:

The above-described process of galvanizing metal, which consists in passing the metal into and through a large body of lead, and through and out of a smaller body of zinc floating upon the lead, as herein described, and for the purposes set forth.

In testimony whereof we aflix our signatures in presence of two witnesses.

THOMAS MIDGLEY. WALTER B. NYE. Vitnesses:

JOHN L. GREENHOVV, A. \VoLF.

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