US1933401A - Coated metal article and manufacture thereof - Google Patents

Description

D. R. WARD Oct. 31, 1933.

' COATED METAL ARTICLE AND MANUFACTURE THEREOF Filed Oct. 1, 1929 Patented Oct. 31, 1933 1,933,401

UNITED STATES PATENT OFFICE COATED METAL ARTICLE AND MANU- FACTURE THEREOF David R. Ward, Struthers, Ohio, assignor to The Youngstown Sheet and Tube Company, Youngstown, Ohio, a corporation of Ohio Application October 1, 1929. Serial No. 396,444 16 Claims. (Cl. Ell-70.2)

This invention relates to a coated metallic arand surrounded by a non-oxidizing or reducing ticle and a method and apparatus for making the atmosphere. This prevents oxidation of the coatsame, and is herein particularly described as aping material and removes the necessity of having plied to the lead coating of steel strips. a fluxing agent present to dissolve the oxides Any attempts to apply a lead coating direct to which would form in the presence of air.

steel by processes heretofore known have resulted If desired, the fixation rolls may be preceded by in coatings having pin holes therein and some of sizing rolls which determine the amount of coatthe fluxing agents have been retained on the ing material which is applied per unit of area metal. The pin holes and retained flux both inof the base.

duce corrosion efiects. These pin holes are at- The use of my process and apparatus results 65 tributed to the combined action of escaping hyin a new product substantially free from pin holes drogen absorbed by the base metal in the pickand having improved corrosion-resistant propling operation, and to the surface tension of the erties. lead. The surface tension of the lead is suf- The accompanying figure of drawing illustrates ficiently high that it tends to produce globules on in longitudinal vertical section a present pre- 70 the surface of the base material during the procferred embodiment of the invention as applied to ess of solidification, because lead does not wet the lead coating of a continuous strip. steel. In the apparatus shown in the drawing, strip I provide for applying the metallic coating and material S is fed continuously through a pickling substantially simultaneously cooling the same and tank 2 under a guide roll 3, and upwardly through 75 acting on the surface, as by compression rollers, a dry flux box 4. The flux box 4 is filled with t pr v nt f rmat f pin holes or to se any a suitable flux such as zinc chloride, ammonium pin holes which may be formed and produce subchloride, or both. The material is still wet from stantial continuity of the coating material. Prefthe pickling tank when it passes through the a y t e base iS fed through a bath of the flux box 4. Hydrochloric acid is preferably em- 80 coating metal and is engaged almost immediately ployed for pickling. The flux box is closed off at after'it leaves the bath, a by a P of rolls, Which the bottom by rolls 5 between which the wet strip are maintained at such temperature as to freeze i mi The use of rolls 5 prevents choking of the adherent atin ma ia While at the same the box at the bottom and at the same time closes time, by compression, overcoming the surface tenit ofi against leakage of th dry flux, 85 SiOn fi ll, and tendency to fl P 110165, The material passes upwardly from the flux box Closing y p 110165 which y be formed- 4 over a guide roll 6 and then downwardly through The material is preferably fluxed before enterflux b '7 containing a it bl lt flux ing the bath and is wiped scrubbed 80 as 170 such as those now in use. The material passes g remove any es api s s or flux adhering to t e through the flux box 7 directly into a bath 8 of 90 u a ra ly th wip s effected while molten lead contained in a lead pot 9, which is the material is moving in a substantially vertical maintained at proper temperature by any suitdirection, whereby neither surface of the material m means (not shown) The material travels lies above the gas bubbles which are wiped off. downwardly and passes around a guide r011 10 If the wiped off bubbles in their natural upward submerged in the lead. 95 travel through the bath were to be stopped in A wiper 11 is placed above the guide r011 10 such travel by a surface of the base material, they so as to engage both surfaces of the Strip in would tertd to adhere to the its vertical travel from the guide roll 6 to the 53:22:33; figzgg alloymg o 8 base guide roll 10. The rate of travel of the strip The base preferably passes through a dry flux material is g g absorbed on its way to the coating bath, and then through hydrogen produce tiring e pic ng operaa flux box adjacent the u f of the coating tlon escapes before the wlper ll is reached. The

material. This insures adequate fluxing of the Wlper may be made I any sulteble mammal, such t i and d in t production of a as woven asbestos reinforced with wlre and car- 105 tinuous uninterrupted coating. ried in suitable rigid frame members, as shown. The rolls employed for the fixation of the coat- The w p is effective for mechanically mo ing material on the base, that is to say, the rolls ing gas bubbles adhering to the surface of the which compress and cool the coating, are prefbase material, and since the strip extends ver- 55 erably arranged in a chamber lying over the bath tically upwardly fr m th w p the gases ar 110 free to travel to the top of the lead bath and pass off to the atmosphere.

By the time the base reaches the guide roll 10 it is highly heated, and the lead in the bath becomes alloyed therewith as the strip travels from the guide roll 10 to a pair of rolls 12, similar to the so-called wiping rolls used in galvanizing practice. These rolls run partly in and partly out of the lead bath so that when the material leaves the same, it is above the bath. The spacing of the rolls is adjusted in any desired manner so as to determine the amount of lead which passes upwardly with the base.

The rolls 12 are enclosed in a chamber 13 in which a neutral or reducing atmosphere is maintained. This prevents oxidation of the hot lead after it leaves the bath. v

As the coated material travels upwardly from the rolls 12, the surface tension of the lead tends to collect the coating into globules, thus causing a discontinuous coating. This condition, if not corrected, results in pin holes in the final product.

A pair of fixation rolls 14 is arranged in the chamber 13 a short distance above the sizing rolls 12. These rolls are hollow and are watercooled. They are efiective for mechanically acting on the still molten coating so as to squeeze down any globules, thus rendering the coating again continuous, and for freezing or setting the lead so that any tendency of the same to again collect into globules and produce a discontinuous coating is immediately eliminated. The material, therefore, when it leaves the fixation rolls 14, is a ferrous base having a coating of lead applied directly thereto, the coating being substantially free from pin holes; This material travels upwardly over a guide roll 15 and thence out of the apparatus. The force necessary to pull the strip through the apparatus may be supplied by a coiler or by pinch rolls 16, as desired. All rolls may or may not be driven as desired.

While the rolls 14 serve to chill the fiuid lead under pressure, the solidified lead still has a high degree of plasticity and because there are no oxides present, it will be rolled into a uniform and continuous surface. As a matter of fact, the operations of rolling and chilling occur simultaneously and by proper regulation of the amount of cooling fluid supplied, the continuity of surface is probably obtained approximately when the solidification point of the lead is reached.

My process is of value not only in the coating of lead on steel, but also for the coating of other materials such as lead on brass or copper, or aluminum on iron, which do not readily alloy with the base. In this connection see Protective Metallic Coatings by Henry S. Rawdon of the U. S. Bureau of Standards, page 136, where pin holes intin coatings are discussed.

It will be noted from the drawing that a coating 17 is provided over the bath to prevent oxidation of lead. This coating may be the flux material, powdered charcoal, or other suitable substance. It will be further noted that this protective coating is not applied to that portion of the bath lying within the chamber 13, and that the walls of the chamber are extended below the lead line so as to prevent any of the coating material from entering. There is no need to protect the surface of the lead from oxidation by a coating such as 17 in the chamber 13 because of the reducing or non-oxidizing atmosphere therein. Because of this provision the rolls 12 do not pick up dross, but maintain their shape and cleanness of surface indefinitelyl While the invention has been described as particularly applied to the coating of strips, it will be understood that it is not to be limited but may be also used for the coating of other articles such as wire, rods, sheets, or pipes. It will be understood, therefore, that while I have illustrated and described the preferred form of the invention as applied to the lead coating of strips, it is not to be limited to the form shown but may be otherwise embodied or practiced within the scope of the following claims.

I claim:-

1. In the method of applying a metallic coating to a metallic base, the steps consisting in feeding the base through a molten bath of the coating metal, engaging the issuing material while the coating is still at a high temperature, and substantially simultaneously mechanically confining, compressing and cooling the same in a non-oxidizing atmosphere.

2. In the method of applying a metallic coating to a metallic base, the steps consisting in feeding the base through a molten bath of the coating metal, engaging the issuing material while the coating is still at a high temperature, and substantially simultaneously mechanically confining, compressing and cooling the same in a reducing atmosphere.

3. In the method of applying a metallic coating to a metallic base, the steps consisting in feeding the base through a molten bath of the coating metal, passing the material direct from the bath into a non-oxidizing atmosphere, and before the coating has set there substantially simultaneously mechanically confining, compressing and cooling the same.

4. In the method of applying a metallic coating to a metallic base, the steps consisting in passing a base through a molten bath, wiping the surface of the base while the same is submerged and is in such position as to insure uniform release of gases from both sides thereof, and continuously moving the base away from the wiping point while it is maintained in the same'relative position to permit uniform release of gases from both sides thereof.

5. In the method of applying a metallic coating to a metallic base, the steps consisting in supplying a wet pickled base, applying a flux thereto while still wet, heating the fiuxed base, wiping the same while the portion being wiped is vertically disposed within a coating bath, and applying a coating.

6. In the method of applying a metallic coating to a metallic base, the steps consisting in heating a base, wiping the same and. applying a coating, and thereafter compacting the coating before it has set so as to close pin holes and simultaneously solidify the coating.

7. In the method of applying a metallic coating to a metallic base, the steps consisting in heating a base, wiping the same and applying 140 a coating, and thereafter compacting the coating material in a non-oxidizing atmosphere and before it has set so as to close pin holes and simultaneously solidify the coating.

8. In the method of applying a metallic coating to a metallic base, the steps consisting in fluxing a base and heating the same, wiping the heated base, applying a coating material thereto, and thereafter compacting the coating ma terial before it has set so as to close any pin 150 to a metallic base, comprising a holes therein and simultaneously solidify the same.

9. Apparatus for applying a metallic coating to a metallic base, comprising means whereby a coating material is applied to the base, and means effective on the pressure in a non-oxidizing atmosphere.

10. Apparatus for applying a metallic coating to a metallic base, comprising a container for a bath of molten coating material, means whereby the base is guided through the container, means for engaging the issuing material before the coating has set and substantially simultaneously mechanically confining, compressing and cooling the same, and means for maintaining the issuing material in a non-oxidizing condition until the last-mentioned means has acted thereon.

11. Apparatus for applying a metallic coating to a metallic base, comprising a container for a bath of coating material, achamber extending upwardly from the bath, means for guiding base material through the bath and the chamber, the chamber being adapted for maintaining a nonoxidizing atmosphere around the base as it travels therethrough, and means in the chamber for cooling the coated base under pressure. I

12. Apparatus for applying a metallic co ting containei' for a bath of molten coating material, means for guiding the base therethrough, means whereby the base is heated, means for wiping the base while at elevated temperature, sizing means for coating before it has set for chilling the applied coating under rolling determining the amount of coating material on the base as it leaves the bath, and means for setting and cooling the coated base under pressure.

13. Apparatusfor applying a metallic coating to a metallic base, comprising a container for a bath of molten coating material, guide means whereby the base is directed upwardly and then downwardly into the bath, and means for applying a flux during its upward travel.

14. Apparatus for applying a metallic coating to a metallic base, comprising a pickler, means for applying a dry fluxing material to the wet base as it leaves the pickler, and a container for a bath of molten coating material adapted to coat the fluxed base.

-15. In the method of applying a metallic coating to a metallic base, the steps consisting in feeding the base'through a molten bath of the coating metal, withdrawing the coated base, applying pressure to the coated base before the coating has set, and chilling the base and coating I coating metal, withdrawing the coated base, ap-

plying pressure to the coated base before l5h coating has set, and chilling the base and coating at the point of pressure application while maintaining said point under a non-oxidizing atmosphere.

DAVID R. WARD.

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