US2073334A - Protected metal article and method of making the same - Google Patents

Description

A. w. COFFMAN March 9, 1937.

PROTECTED METAL ARTICLE AND METHOD OF MAKING THE SAME Filed Aug. 7, 1936 w Ill/V5076;

ing the present Patented 9 1937 I PROTECTED METAL ARTICLE AND METHOD OF MAKING. THE SAME Alden W. Cofi'man,

H. H. Robertson Pittsburgh,- Pa., assi gnor to ompany, Pittsburgh, Pa., a

corporation of Pennsylvania Application August 7, 1936. Serial No. 94,808

This invention relates to a protected metal article and to a method of making the same.

One object of the invention is to provide a novel and superior protected metal article which is particularly useful for building' p poses such as roofing and siding material, which is capable of withstanding mechanical shock in cold weather, which may be formed into various shapes with minimum liability of damage to the protective coatings thereof, and also 'which is extremely durable and possesses superior fire resistance as compared with other protected me articles heretofore manufactured.

Another object of the invention is to provide a is novel and improved method by which the protected metal article may be made at minimum expense and in a rapid and efiicient manner.

With these general objects in view and such others as may hereinafter appear, the invention consists in the protected-metal article, in the method of making the same and also in certain novel steps in the method hereinafter described and particularly pointed out in the claims at the end of this specification.

In the drawing, Fig. 1 illustrates a cross sectional view of a protected metal article embodyinvention; Figs. 2 and 3 are sectional views illustrating the apparatus preferably employed In general, the present invention contemplates an improved protected metal article produced by the process hereinafterto be described and which comprises a metal article In preferably a metal sheet such as an iron or steel sheet. The metal 35 sheet ID has secured to the opposite surfaces thereof layers l2 of fibrous material, preferably asbestos paper or felt, by an interposed metal adhesive M. The metal adhesive completely envelopes the metal sheet l0 and-may comprise zinc, tin, cadmium lead or other alloy and the metal adhesive is alloyed to the metal sheet l0 and keyed or anchored to the fibers comprising the fibrous layers l2. In order to further described, it is preferred to saturate or impregnate the fibrous .layers with saturant or an impregnant preferably comprising a bituminous composition such as asphalt or any of the other commercial impregnants now used for impregnating fibrous layers. The saturated protected metal sheet thus far described is further protected against weather, gas and fume conditions and for the purpose oi. increasing the durability of the protected sheet and, as herein shown, the

protected metal article is provided with an outer in practicing the present process.

atively high protect the article thus far a weather-proofing coating l6 which may comprise any desired compositi'onof bituminous material and preferably a composition comprising cottonseed pitch, and asphalt melted together and which possesses satisfactory weather resistance and durability.

In producing the present protected metal article it is preferred to afllx the fibrous layers [2 to the metal sheet I ll immediately after the metal sheet has passed through a bath of the molten metal adhesive and before the latter has solidified inproducing the preferred protected metal sheet. Zinc is preferably" used as the metal adhesive and as illustrated in the drawing, 20 represents, more'or less diagrammatically, the usual galvanizing bath to which steel sheets l8 are conveyed from the usual. storage tank IT. The steel sheets are conducted throughthe galvanizing bath in the manner usually practiced in producing galvanized steel sheets where they receive thezinc coating. galvanizing practice the temperature of the bath of zinc within the galvanizing pot 20 runs from 830 F. to-8'Z5" F., and the usual fluxes are utilized in the flux box l9 and upon the exit rolls 2i. After the sheets l8 leave the exit rolls 2| and come solidified, provision is made fibrous layers I 8 to one or both surfaces of the sheets. As herein shown, supply rolls of such fibrous material preferably asbestos felt, are mounted within enclosures 25by which they are protected from the fumes, moisture, etc., evolving from the composite sheet by reason of the rel- From the supply rolls the fibrous webs 26 are conducted around heating rolls 24 by which moisture is removed from the fibrous material and the webs are then conducted between combining rolls indicated at 22, 23 and between which the metal sheets l8 with the molten zinc coating thereon are passed. The combining rolls 22, 23 cooperate to firmly impress .the fibrous material into the molten zinc produced is conducted from the rolls on a suitable conveyor indicated generally at 28. When the sheet has-become cooled and the zinc coating solidifies, the fibrous layers are firmly bonded to the metal sheet by the zinc coating which is alloyed to the opposite surfaces of the metal sheet l8 and is also keyed to the fibrous While the composite protected sheet in the condition thus far described may be used with advantage for many purposes, nevertheless for some purposes I prefer to impregnate the fibrous" layers l2.

In accordance with the usual for applying temperautre of the zinc coatings.

coating and the composite sheet thus layer or layers of the sheet with an impregnant or saturant such as asphalt, and it is preferred to impregnate the composite sheet while the'temperature thereof is relatively high. The exact temperature at which it may be found most desirable to impregnate the fibrous layer or layers of the composite sheet will depend, of course, upon the temperature and composition of the impregnating material, and the temperature of the sheet may be controlled by the length of the conveyor 28 or by any convenient cooling or heating methods. The impregnation of the fibrous lay.- ers has been found to take place much more rapidly when the composite sheet is impregnated while hot and the degree of impregnation-produced has been found to be more complete.

As herein shown, after the composite sheet has left the conveyor 28 it is submerged beneath the surface of a bath of impregnating'material within an elongated tank 30, and as herein shown is deposited upon a conveyor 32 by which it is caused to traverse through the bath and to be elevated at the exit end of the bath to pass through a pair of squeeze rolls 34 by which the excess of impregnating material is removed and permitted to return to the bath. Thereafter the impregnated sheet may be conveyed'on a suitable conveyor indicated generally at 35.

From the description thus far it will be observed thatin practicing the present process it is essential to apply the fibrous webs 26 to the zinc or other metal adhesive coating as soon as practicable after the galvanizing or other coating bath, and while the distance from the exit rolls 2| at which this operation may be performed varies within reasonable limits, care should be taken for best results to apply the fibrous layers before the zinc or other coatings have solidified to any extent. In practice, operating upon i2, i4 and I6 gauge steel sheets a distance from the exit rolls of the galvanizing bath to the combining rolls 22, 23, of approximately five to seven feet has been found satisfactory.

The asbestos paper or felt commercially obtainable usually embodies a substantial amount of organic binder, and after such asbestos felt has been applied to the moltenzinc coatings in the manner above described, the heat in the coatings and in the steel sheet operates to burn out a substantial part of the organic matter. This removal of the minor proportion of the organic matter, however, does not destroy the continuity of the asbestos layer and the resulting product has been found to be capable of being impregnated more thoroughly or more completely as a result of this burning of the organic binder.

The extent to which the organic matter is removed depends upon the temperature of the galvanizing pot and the thickness of the metal sheet governs the amount of heat stored in the metal sheet,-so that the thicker the steel sheet the more complete the removal of the organic matter from theTasbestos sheets. When operating upon thin steel sheets supplemental heating means may be utilized if the removal of the organic matter is found to be insufficient-for any particular pur- From the above description, it will be understood that in addition to the above described the application of the fibrous layer or layers at the galvanizing pot, the fibrous layer or layers may be applied to the metal sheet or member immediately following the application of a tame, tin cadmium, or any other suitthe metal sheet l8 has left able alloy coating which may be used as the metal adhesive.

In order to further protect the metal article against weather conditions and particularly against severe fume conditions, it is preferred to envelop the composite sheet or article either before or after saturation or scribed, in a bituminous weather-proofing coating and as' illustrated herein, after leaving the impregnating bath the composite sheet is passed between coating rolls 38,. H. The bituminous composition. in molten condition may be flowed from a supply tank, indicated at 42, to coating tanks 40, 46 in which the coating rolls 38, 44 run. As the composite sheet passes between the coating rolls, the. desired layers 21 of bituminous material,- such as a cotton seed pitch-asphalt composition, are applied to the opposite surfaces of the sheet and in their molten condition fuse together over the sides of the sheet forming the weather proofing envelope shown at i6.

From the foregoing description it will be observed that the present process, involving the application of the fibrous layers upon the metal adhesive before the solidification or cooling of the metal adhesive subsequent to the passage of the metal sheet through the bath of the molten metal adhesive, lends itself to continuity of operation and accompanying economy in the manufacture of the composite sheet, and also of the weatherproofed protected metal sheet. In addition to the economy in the manufacture of the products it has been found that in the products produced by the process described in which the fibrous'layers are applied before the metal adhesive has cooled or solidified, the fibrous layers adhere to the metal in an improved and superior 'manner. The fact that the metal adhesive is not reheated reduces to a minimum the formation of metal oxide on the surface of the metal adhesive coating, thus making it possible for the metal adhesive to inter-penetrate more completely with the fibrous layers, producing a superior and much firmer bond. When zinc is employed as the metal adhesive, the present process also produces a minimum of the zinc iron alloy layer between the pure zinc and the steel comprising the metal member i0, and as a result there is less tendency for flaking off of the zinc coating, so that in the products produced by the process a superior bond and improved durability results. The present process also has the advantage that a minimum amount of the zinc or other metal in the metal adhesive coating is lost by oxidation and by penetration into the steel so that a maximum layer of pure zinc or other metal is available thus contributing to the uniformity with which the fibrous layers may be embedded in the pure zinc or other metal adhesive.

The protected metal article embodying the fibrous layers i2 united to the metal member [0 by the interposed layer of metal adhesive i4, produced in accordance with the present process, and also embodying the envelop iii of weatherproofing bituminous material as described, is less inflammable than other comparable products heretofore produced; it may jected to shock at very low temperatures without removal of the protective coatings, thus contributing to the durability of the protected metal article, particularly when used as a roofing or siding material, and in addition the protected metal sheets may be formed into various shapes and corrugated with-minimum liability of damage to the protective coatings be frozen and sub- In the practical impregnation as despread across the steel sheet l0, and as a result, after corrosion has started and this protective film has been developed, the

film in place.

Another important the structure of the present protected metal sheet resides in the improved ability of the protective coatings to remain in place in the event that the is subjected to under such conditions.

in a continuous manner. I

4. As a new article of manufacture, a protected metal article comprising a metallicsheet, an asbestos sheet and an interposed layer of metal adhesive, whereinthe asbestos sheet is afllxed to the metal sheet by the metal adhesive in its molten condition, as initially applied to the metal sheet, and'wherein the asbestos Sheet is keyed advantage resulting from to the metal adhesive when said metal adhesive has solidified and a protective bituminous coating covering the fibrous material.-

5. As a new article of manufacture, a protected metal article comprising a metallic sheet, an asbrous materi 6. As a new article of manufacture a protected metal article comprising a metallic. sheet,

in a continuous manner and a protective bituminous coating covering the fibrous material.

7. Ajcontinuous method article, the steps comprising applying layers oi. fibrous material to the opposite surfaces 01' a metal sheet provided with a layer of molten base member. 12. A continuous tallic elements which 13. A continuous method for fabricating metallic elements comprising passing a metallic base member through a bath of fiuid metallic adhesive maintained at a temperature sufficient to raise the temperature of the metallic base member, as it is .passed therethrough, to the point where the metallic adhesive alloys with the base member, and thereafter applying fibrous material thereto, before the applied metallic adhesive has solidified, whereby to firmly key and the metal base member.

14. As a new article of manufacture, a protected metal article comprising a metallic sheet, an asbestos sheet and an interposed layer of metal adhesive. wherein the metal adhesive in its molten condition, as initially applied to the metal sheet. alloys with the metal sheet and penetrates into the asbestos sheet to key the asbestos sheet to the metal adhesivewhen the latter has solidified and a weather-proofing and anchor the fibrous material to the metallic sheet members.

bituninous coatinz enveloping the composite sheet thus formed.

15. As a new article of manufacture, 9. protected metal article comprising a metallic sheet, an asbestos sheet and an interposed layer of metal 5 adhesive, wherein the metal adhesive in its molten condition, as initially applied to the metal sheet, alloys with the metal sheet and penetrates into the asbestos sheet to key the asbestos sheet to the metal adhesive when the latter has solidified, said asbestos sheetbeing impregnated with bituminous material.

18. 'As a new article of manufacture, a protected metal article comprising a metallic sheet, an asbestos sheet and an interposed layer of metal adhesive, wherein the metal adhesive in. its molten condition, as initially applied to the metal sheet, alloys with the metal sheet and penetrates into the asbestos sheet to key the asbestos sheet to the metal adhesive when the latter has soliditied and provided with a protective bituminous coating enveloping the composite sheet thus formed.

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