US1371445A - Lead-coating process - Google Patents

Description

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To all whom it may concern Be it known that I, ROBERT J. SHOEMAKER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Lead-Coating Processes, of which the following is a specification.

y iron or steel articles, and its object is to provide a method b which this operation scribed, may, however,

ing the billets output with a "quired or ma be accomplishe more conveniently, expe itiousl and economically than with methods eretofore used. A more specific object of the invention is to improve upon the process of manufacturing cold drawn steel tubes by coating the billets from which the tubes are drawn with lead in the novel manner, to be hereinafter described, for

the urpose, in the first place, of lubricatin the illets for the drawin operation an in the second place, giving t e finished tubes a highly polished rustproof surface. By utilizing the coatin' process in this connection the necessit or lubricating or dopefore drawin 'ls obviated (where the billets are not su 'ected to a large number of passes at least the peroentage of breakers is greatly decreased; the number of asses to obtain a given reduction of the billet may be diminished; the danger of scratching the tubes is minimized; wear and tear on the dies and mandrels lessened, thereby increasing the life of thes parts; and the possible speed of the billets through the draw bench is considerably 1ncreased; al-l of which results in increased 'ven equipment and in a.

"van time and ecrease in the manufacturmgLcost of the tubes. In addition the surfaces of the tubes are made highly polished and rustproof.

- The coating method, to be hereinafter debe used inoth'er connections, for example, coating blanks or bodies to be employed in stamping o rations or, in fact, the method may be uti ized in the manufacture of any iron or steel articles where the coating of the articles with a thin, even dense covering of lead is redesirable. With this understanding, the improved method will, be described as .utilizedfor treatment of billets for cold drawin steel tubes, and is as follows:

The hillets are first cleaned in the usual Specification of Letters Patent.

invention relates to the lead coating of way by means of a suitable acid, it being of partlcular importance to remove all traces of grease. They are then immersed in a concentrated water solution of lead acetate and acetic acid. The solution should contain at least thirty-five per cent, by weight, of lead acetate, although to get the best results'the lead acetate content should be from forty to fifty per cent. The acetic acid should not be less than five per cent. A somewhat larger quantity may be used. The solution 18 heated, otherwise the action will be extremely slow. Preferably it is maintained at a temperature from 160 to 180 Fahrenheit, which is sufficient to disassociate the ace- 'tate without producing excessive volatilization of the acetic acid. If the billets be allowed to remain for approximately fifteen minutes 1n the solution at this temperature they will be covered with an extremely thin but smooth and very dense coating of lead which adheres to the steel with great tenac-f ltg. Apparently the chemical action is one 0 substitution, the lead acetate disassociating and the lead being deposited on the bil let and iron from the billet combining with the radical (OJ-1,0,) to form iron acetate. In time this iron acetate will decompose into 1I'0I1 hydrate and acetic acid andthe iron hydrate settling to,the bottom of the tank,

may be drawn ofi at suitable intervals. The solution will become impoverished during the process and may be built u acetic aci iron and has a cleansin effect 0 th billets. g up n e .After-the process has been carried on for a time,:the solution will necessarily contain a eertam amount of iron acetate and while this does not interfere with the contemlated chemical action the adherence of this iron acetate to the billets will result in the formation of rust on the plated surface,

through oxidation, so thatit is desirable that the billets, when taken from the solution, be washed to remove the iron acetate, or otherwise treated to prevent the rusting from; 1 5

taking place. Ordinarily it will be sufli- 0161;: to wash the billets t ordughly in clean wa r.

The billets thus treated may be drawn m the usual manner through dies and over Patented Mar. 15, 1921. Application filed December 11', mo. 8erial1io.429,889.

by adding mandrels. The lead coating makes it unnecessa to cover the billets with any of the usua lubricants or dope elther before the pass or. between lpasses unless the billet 1s given, a consider-a le number of passes, say .fouro'r more. The usual annealin and pickling between passes is consequent y obviated.

Commercial operation of the process has shown that the billets when treated as above described may be drawn with less breakage than when dope according to methods heretofore used. 'I have found that the number of breakers is ordinarily reduced from the usual ten per cent. to about three per cent. In some operations it is ssible to accomplish the desired reduction y a fewer number of passes than heretofore. The speed of the billets through the draw bench may be increased, thereby making possible an enlarged production with a given e uipment and in a given time. Fewer o the tubes are scratched. Year and tear on the mandrels and dies is diminished, increasing the life of these parts several fold. The billets are more conveniently handled than those coveredwith the greasy dope ordinarily used. Finally, the finished tubes are given, within and without, highly polished surfaces which will not rust. If the tubes are annealed it will be found that they can be flanged, flattened or similarly manipulated just as well as the seamless tubes made by the old processes.

This application is a continuation in part of my co-pending application Serial No. 374,089, filed April 15, 1920, for lead coating process.

I claim:

1. Method of lead coating an iron or steel article which consists in bringing the same into contact with asolution of lead acetate I tate therefrom.

3. Method of lead coating iron or steel articles which consists in immersing the same in a solution of lead acetate of sufficient concentration to cover the surfaces thereof with a dense, thin, smooth, permanently adherent film of lead which is substantially non-oxidizable when exposed to the atmosphere.

4. Method of lead coating iron or steel articles which consists in lmmersing the same in a solution containin not less than thirty-five per cent. by weig t of lead acetate.

5. Method' f lead coating iron or steel articles which consists in immersing the same in a solution containin not less than thirty-five per cent, by Weig t, of lead acctate and thereafter washing the articles to remove traces of iron acetate.

6. Method of lead coating iron or steel articles which consists in immersing the same in a water solution containin approximately forty to fifty per cent, y weight, of lead acetate, and five per cent. or more of acetic acid maintained at a temperature of between 160 and 180 Fahrenheit.

ROBERT JAY SHOEMAKER.

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