US2105426A - Method of processing metal - Google Patents

Description

Jan. 11, 1938. c. E. MCMANUS METHOD OF PROCESSING METAL Filed May 8, 1934 3 Sheets-Sheet l (22/1/68 2: Fif 1W Jan. 11, 1938. c. E. MOMANUS 2,105,426

v METHOD OF PROCESSING METAL Filed May 8, 1954 3 Sheets-Sheet 2 Jan. 11, 1938. c. E. McMANUS 2,105,425 I METHOD OF PROCESSING METAL Filed May 8, 1934 5 Sheets-Sheet 3 v 7IIIIIIIIIIIIIIIIIIIII/III/II.

Patented Jan. 11, 1938 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to the processing of electrolytic iron and the production of satisfactory commercial sheets or plates therefrom.

Particularly, the invention resides in the processing of virgin iron produced electrolytically. By virgin iron, I mean iron formed by a suitable electro-deposition process; this iron without preliminary treatment, is subjected to my method of processing.

Thus, the electrolytic deposit is removed from the cathode as a continuous strip, in plates orin sheets, and may have a gauge or, thickness substantially that desired in the final product. Briefly, the plates, sheets, or strip, are subjected to continuous steps of heat treatment, cooling, in conjunction with heat treatment, and rolling. The plates, sheets or strip so produced may be subjected to suitable formingiand/or coating operations as desired.

The method of processing is (1) preferablycarried out as a continuous operation, and (2) the usual commercial operations employed for the manufacture of so-called tin bar and the subsequent reduction of the bar to sheet forin are com pletely avoided.

Hence, the necessity for numerous and precise conditions and the expense and time incident to conventional practice are eliminated. The present invention enables a very, satisfactory sheet or plate to be produced, having qualities distinctly better. than those to be found with the present commercial iron or steel plate and sheets; moreover, the operation is accomplished in a shorter time period and at greatly reduced expense.

The importance of the reduction in time'period and costs will be appreciated when it is understood that the method of the present invention can be practiced to produce complete sheets, for example, in tin mill gauges #40 to #15 (0.005%6875" to 0.0703125". thickness) within a maximum time cycle of thirty minutes, and at an expense which is but a fraction of that necessary at the present time for manufacturing commercial plate and sheets.- Since millions of tons of commercial plates and sheets-are used yearly in numerous industries, the saving which the present invention affords is very substantial and also greatly enlarges the field of application of the product.

I have referred above to aheat' treatment. This heat treatment is controlled and consists in passing the plates, sheets or continuous strips on a suitable conveyor continuously at a predechamber, preferably an electric furnace in the presence of a reducing atmosphere.

In conjunction with the heat treatment and as a continuation-of the same, the sheets or strip are given'a cooling. That is, they pass continu- 5 ously from the furnace or heating chamber into a cooling chamber in the presence of a reducing atmosphere and are cooled to a temperature at which they exhibit substantially no affinity for oxygen. The travel of the sheets or strip through 10 the cooling chamber is accomplished. at a predetermined speed equal to the rate of travel in the heating chamber, so that a controlled cooling is likewise effected.

As a result of the controlled, continuous heat- 15 ing and cooling treatments, I find that the sheets or plates of virgin electrolytic iron possess a tionable gases, oxides, as well as metalloids. I

also observe that the crystals do not lose their elongation in the direction of the thickness of the sheet, and that, in fact, this very desirable arrangement of the crystals is permanently stabilized. Furthermore, I observe that any conditions of oxidation existing in the sheet'or plate before it is heat treated are effectively removed, and the pure iron resulting from the reducing operations becomes an integral part of the sur- 0 face of the sheet strip or plate. The plates, sheets or strip exhibit a marked resistance to oxidation and corrosion, and have enhanced qualtities of ductility, tensile strength, elasticity, malleabi-lity, as well as elastic limit and yield point, not attainable with present commercial'plate or sheet.

Following the heat treatmentand cooling, the plates, sheets or strip are given a cold rolling.

This rolling will impart to the plates, sheets or This resistance to drawing and forming strains is due to the enhanced ductility of the metal.

The plates, sheets or strips in suitable gauges may be readily coated, for example, tinned, and produce a highly satisfactory tin plate.

As is well known, tin plate is employed in largeresistance heating elements It. A cooling chamquantities for the manufacture of containers and closures therefor; the tin plate of the present invention is particularly useful for these purposes.

In the drawings:

Figure 1 is a diagrammatic view illustrating a preferred form of the invention.

Figure 2 isa similar diagrammatic view illustrating another preferred form of the invention.-

Figure 3 is a diagrammaticview illustrating the manner in which the process may be carried out by utilizing a tin bar stock .of the electrolytic metal initially and following conventional procedure to reduce the bar to sheet form.

Figure 4 is a sectional View of a laminated article Showing by representation a base consisting of aplate, sheet or strip of the metal processed in accordance with this invention and having a coating upon each surface thereof.

Figure 5 is a similar sectional view showing by representation a coating or film on one side of the base.

Flgurefiis a similar sectional view showing by representation the base having two or more layers 0r films on one surface thereof.

Figure 7 is a similar sectional view showing by representation a base of the metal of this invention having a multiplicity of coatings upon opposite sides. I

Figure 8 is a front elevation of a crown or crimped cap.

' Figure 9 is a front elevation of a screw cap.

Figure 10 is a front elevation of a cap made from base material of the present invention in accordance with the patents to George W. Booth, Nos. 1,956,208, 1,956,209, 1,956,217 and 1,956,218.

Figure 11 is a top plan view of the disc from which the cap of Figure 10 is formed, in accordance with the said patents of George W. Booth.

Figure 12 is a front elevation of a lug cap.

Figure 13 is a plan view of cap spotting material'comprising a base of the metal processed in accordance with thisinvention, and preferably of a gauge equal to or thinner than the usual tin or aluminum foil, having a layer of a thermoplastic or other heat sensitive or heat coagulable' adhesive on one surface thereof. 4

Figure 14 is a side elevation showing by representation a container made of metal processed in accordance with this application.

I Figure 15 is a view in section showing a gasket made inaccordance with the patents to George T. Balfe, Nos. 1,776,140, 1,843,438, 1,927,450 and 1,927,791.

Figure 16 is a view partly broken away of an electron discharge tube.

Figure 17 is a side elevation of plate material useful for auto body manufacture, and

Figure 18 is a sectional view of the plate of Figure 17.

The primednumerals and letters in Figures 2 and 3 of theaccompanying drawings indicate corresponding parts as numbered and lettered. in Figure 1.

The method of processing is shown diagrammatically in Figure 1 of the drawings which represents the preferred form of the invention;

I have shown at A a suitable apparatus for producing electrolytically a deposit of iron. 'The numeral 10 indicates a scrubbing means and II a conventional drier both customarily associated f with electro-deposition apparatus.

At B is indicated an electric furnace having a' plates therethrough, and, of course, a single travelling conveyor or a plurality of cooperating associated conveyors will be utilized where the ill electrolytic deposit is removed from the electrodeposition apparatus and moved without interruption through the entire series of operations, i. e., continuously.

The sheet X of electro-deposited metal is continuously removed from the cathode of the apparatus A, and is continuously passed through the several devices described as a continuous strip. If desired, strips of predetermined length may be passed continuously through the processing apparatus.

Also, the strips of predetermined length may be rolledup at the end of each operation, as shown at 20, and then subsequently continuously fed to each processing instrumentality from the roll.

, The same sequence of precedure and continuous treatment is carried out in connection with separate sheets Y formed in the electro-deposition apparatus A, as shown in Figure 2.

In Figure 3, I have illustrated a fourth method of procedure, which is not preferred, and in fact is set forth to indicate the substantial advantages accruing from a method of processing, as shown in Figure 1 or Figure 2.

In Figure 3, a so-called tin bar Z is formed electrolytically in the apparatus A". Thereafter, in accordance with conventional procedure this bar must be heated a furnace 22 and transferred over suitable tables 23, 24 to a three high-mill 25, where it is rolled one or more times to proper gauge. The sheet X is then doubled upon itself in a roll type doubler 26 and heated in a suitable double type furnace 2?. The sheets are then rolled to their final gauge in rolling mill 28, doubled and sheared at 29, cut to size at 30, and the pack opened at 3 l'. Thereafter, the operation continues as described in connection with Figure 2.

In the conventional method of making tin bar, for example, the metal is formed into an ingot of iron or steel weighing several tons, placed in a soaking pit, passed through a blooming mill, a universal plate mill, reheated in a furnace, and reduced to tin bar size in a bar mill or strip plate mill. All of these preliminary operations and those described in referringto Figure 3 for initially processing the tin bar so formed, are eliminated by practicing the invention in accordance with Figures 1 and 2.

The reduction in time period and elimination of costly operations incident to following conventional procedurewill, it is believed, be readily discernible by this comparison, and the resultant savings as will be appreciated are substantial.

Referring to Figure 1, the strip X is removed from the cathode and may have a predetermined gauge or weight, substantially that required in the final product. However, the thickness of the strip may be varied, as desired.

' The deposit is removed as a. continuous strip four days.

large quantities of tin plate, the present method or in the form of sheets or plates (Fig. 2), and thereafter, if necessary, cleaned or. scrubbed and dried in the usual manner. The strip as removed from the cathode may be carried continuouslyon the conveyors and submitted to the several processing operations. On the other hand, the strip material may be formed into rolls 20 and coiled after the drying step or after the heating and cooling step, or after the rolling step. The strip material will be fed from the rolls of predetermined lengths continuously through the respective processing instrumentalities.

Referring to Figure 2, the sheets or plates may be carried on the continuous conveyor from the electro-deposition apparatus through the several processing instrumentalities. On the other hand,

. sheets or plates may be collected after each of the operations in the same manner'as the coils 20 of predetermined length, and the sheets then fed to the succeeding processing device. In any event, it will be observed that the process is continuous, this ,term being used to include (1) travel onthe continuous conveyor from the electro-deposition apparatus through each of the processing instrumentalities, and (2) the-collection of the material after each operation into a roll or pile and its continuous feeding from such a state into the succeeding instrumentalities.

I prefer a continuous feed in one of the ways described in connection with Figures 1 and 2, because the cost of production and the time period of operation are very favorable. For example, the. entire operation, as shown in Figuresc 1 and 2, including the application of a tin coating, can be consummated in a fraction of the time now required to manufacture sheet plate from tin bar. A sheet of virgin electrolytic iron of tin mill gauge, for example, can be processed and tinned within a time cycle of approximately thirty minutes. .Smaller gauges require less time, and heavier gauges a proportionally greater time cycle.

If desired, of course, an intermittent presentation of the strip, sheets or plates to the processing instrumentalities may be resorted to, but I prefer' a continuous method, because of the substantial reduction in operating costs, and particularly the excellent results obtained. In other words, the continuous treatment when compared to intermittent feeding, and particularly present commercial methods of making metal plate or sheets, discloses very marked advantages as regards operating costs, speed of production, and quality of the final product obtained.

Conventional commercial methods of producing tin plate from tin bar or sheet break downs require approximately a time cycle of three to Consequently, for the production of the virgin strip, plate or sheet is subjected to a temperature which will -(1) remove alldccluded gases, such as hydrogen, oxides of iron, as well During travel through the heating chamber,

as metalloids; (2) reduce any oxides on the surface of the plates, sheets or strip; (3) not only reduce surface oxides, but the pure iron which remains combines with the surface of the sheet without producing scales, 1. e;, a dense and substantially continuous surface is formed, and (4 the heating step does not change the elongation of the crystals in the direction of the thickness of the sheet or plate. On the contrary, the heat treatment preserves this desirable crystal structure and makes it permanent and stable.

' The heating temperatures preferably employed are sufiicient to heat the plate, strip or sheets to 9. temperature of substantially 1700 to 2285 F., i

and I maintain a reducing atmosphere in the furnace during the heating operation. This atmosphere may be pure hydrogen, dissociated ammonia, or be neutral. In some cases, illuminating gas "or natural gas may be employed, al-

though the latter are not preferred where a carbon pick-up would'be objectionable, i. e., where similar to that present in the heating chamber and is.cooled to a temperature below substantially 212 F.

The temperature of the cooling chamber and the speed of travel of the sheets, plates or strip will be such that in its travel through the cooling chamber in the reducing atmosphere at the same rate of travel through the heating chamber, the sheets or strip will emerge from the cooling "chamber exhibiting no substantial affinity for oxygen and will have a temperature below substantially 212 F. a

In both the heating chamber and the cooling chamber, the speed of travel of the sheets or strip and the temperature .are controlled, according to the specification of sheet for the articles to be manufactured therefrom. In this manner, the relative heating and cooling of sheets or.

strip will be regulable.

For sheets or strip of tin mill gauges, the period of heating and cooling averages two and one-half minutes to fifteen minutes for the combined operation. For narrower gauges, a lesser time is required, and for heavier gauges a greater time cycle is necessary. In all cases, however, the time is relatively brief as compared to present commercial operations.

It will be understood that the time period to which the plates, sheets or strip are subjected to the heating and cooling operation will determine the relative size of the grain or crystals. This will be varied in accordance with the specifications of the commercial articles desired.

The plate, sheets or strip as it is received from the cooling chamber exhibits a silvery white color characteristic of pure iron, has a dense and con tinuous surface, and the elongation of the crystals is in the direction of the thickness of the sheet.

The sheets, plate or strip when subjected to drawing strains exhibit no directional weakness, longitudinally or transversely, the test consisting in straining the metal beyond its elastic limit and yield point, and resulting in a uniform circular break in the surface of the metal. This is directly traceable to the elongation of the crystals in'the direction of the thickness of the sheet, whereby the transverse and longitudinal strength of the sheet are shown to be equal.

The present sheet and plate, as compared with ordinary commercial steel or iron plate, sheet or strip, exhibits marked advantages as regards ductility, malleability, elasticity, elastic limit and yield point.

Tests which have been made with sheets or strip of tin mill gauge, by way of example, disclose that the Erichsen ductility value is from 8 to 33 better than ordinary grades of commercial steel sheets of similar gauge. For'example, the best cold rolled deep drawing steel sheets have an average Erichsen ductility value of about 8.10, whereas the processed sheet of this invention and of similar gauge, has an average Erichsen ductility value of 8.9 plus.

The continuous heating and cooling operation is in the nature-of an annealing, and is sometimes referred to as a normalizing treatment.

The plate, sheet or strip after having been given a heat treating and cooling operation is cold rolled, preferably under a tempering pressure. In this connection, it will be noted that previous practice required that the plates or sheets be given a large number of passes on hot rolling mills preliminary to any processing treatment. With the present invention, however, no preliminary or subsequent hot rolling or hot working of the metal is necessary.

The rolling operation is preferably what is termed cold rolling, or a skin pass treatment. The rolling apparatus comprises a pair of two high rolling mills in tandem, but, in many cases, the metal need-only be submitted to one of the rolling mills.

The purpose of the rolling operation is to temper and stifien the sheet, roll out any surface irregularities, polish the plate or sheet, and, in some cases, to reduce it slightly when necessary to the desired gauge. In this connection, the sheet by cold rolling may be reduced to a'thickness 75%,of its original thickness without impairing its desirable characteristics appreciably or work hardening the sheet or plate. ample, sheets of the thickness of tin foil or aluminum foil may be produced by cold rolling the metal. The pressure employed in the rolling mill, of course, may be varied in accordance with requirements.

Microscopically, the sheet discloses after the rolling an irregular rhombic shaped crystal with a tendency toward elongation across the plate thickness, instead of the typical elongation of the crystals in the direction of rolling, characteristic of commercial packed rolled plate. This microscopic examination illustrates that the initial elongation of the crystals in the direction of the thickness is not changed by the previous processing, and that it likewise remains unaf fected'by the rolling.

The sheets or'strip are flexible, resilient, and may be cut, formed, drawn, or folded without cracking or producing fissures. This is due to the superior ductility as demonstrated by the bend test which comprises (1) folding a sheet on itself, hammering down the fold, opening the sheet, and straightehingit out fiat. The sheet discloses no cracks, fissures, or strains. The superior ductility of the sheet and its ability to withstand the severe bend test is attributable to For exaioaaae the elongation of the crystalsin the direction of the sheet thickness.

While I have described sheets or strips of tin mill gauge, the same favorable qualities are observable in the heavier gauge material, known as plate. The term plate is used in this specification to identify an accepted product of the iron .and steel industry and defined in "I'iedman's Encyclopedia of Steel and Iron.

. Following either the heating and cooling operation, or the rolling operation, the plates, sheets or strip may be formed or coated in any suitable manner.

Preferably, however, the sheets are rolled and trimmed, or cut to size as at it. Thereafter, the sheets will be formed into the desired articles or given a coating of any suitable character.

In connection with the coating operation, a light wash pickle is normally required, but, in many cases, pickling is not necessary.

I have illustrated a tinning bath at it, as representative of any desired coating apparatus. In the manufacture of tin plate, the sheets or strip are passed through a tinning bath in the usual manner. Under test, using metal processed in accordance with this invention, less tin is required than with conventional commercial plate. This is due to the purity of the sheet, processed in accordance with this invention, and which forms a very complete amalgam with the tin. For example, present commercial tin plate requires an average coating of one and one-half pounds of tin per base box. The sheet of this invention takes an average coating of 1.17 pounds of tin per base box, effecting a very substantial saving in the cost of tinning.

Furthermore, the formation of pin holes and blisters usually encountered with tin plate are practically eliminated by using metal processed in accordance with this invention as proven by the gelatin test.

Referring to Figure 4, I have illustrated by representation a sheet of tin plate in which the numeral 35 indicates a base of virgin electrolytic iron made in accordance with this invention and having upon its opposite surfaces a layer, or film of tin 36.

In lieu of a coating on each side of the base, a coating 36 may be applied to one side only, as shown in Figure 5.

While I have referred to tin, I also coat the base 35 on one or both sides with a layer or film 36 of lacquer, paint, zinc, enamel, a porcelain finish, and, in fact, any desired coating or another layer of the metal base. The layer 36 also represents a decorative or lithographed surface on one or both sides of the base 35.

- The coatings 36 described may be temperature, water, and moisture resistant, as well as heat sensitive; For example, in the manufacture of closures and containers, the base 35 will have on one surface a layer of-heat sensitive adhesive lacquer 36, and on the opposite side, a layer of a decorative lacquer 36.

In Figure 6, I have illustrated the base 35 as provided with a layer 36 of tin or other suitable coating, as above described, and superposed upon the coating 36 a second coating 31. This material will comprise, for example, a lacquered tin plate in which the lacquered surface 31 may be either decorative or temperature and moisture resistant, or a heat plastic adhesive.

In Figure 7, a structure similar to that described in Figure 6 is illustrated in which the superposed coatings upon the base 35, as decap, while the cap shown. in Figures 10 and 11 is made in accordance with the patents to George W. Booth, above referred to.

The cap shown in Figure 12 is a conventional lug cap, and is likewise made from the material processed in accordance with this invention.

In Figure 13, I have shown strip spotting material for closures, wherein the base 35 will be initially formed or reduced to foil thickness, i. e.,

substantially .002", and have applied to one surface thereof a layer of a suitable adhesive, such as thermo-plastic adhesive, or a heat coagulable adhesive 36. As understood, these strips are fed to a suitable punch and applying apparatus and the spots are punched from the strip and positioned upon the cushion liners, for example, cork or composition cork, of closures, such as crown caps, the spots being illustrated at 38 and usually being of less diameter than the diameter of the cushion liner.

In Figure 14, I have illustrated by representation, any suitable type of container formed from material processed in accordance with this invention, for instance, a tin can.

InFigure 15, I have illustrated a gasket of the type having a metal insert 39 of the base material 35 provided with a multiplicity of upstruck projections 40 throughout the area of the sheet insert, and asbestos layers or other insulating layers or layers of cushion material 4| superposed on the metal layer and in which the projections 40 are embedded by pressure. Such gaskets are illustrated and described in the patents to George T. Balfe, above referred to. The layer 4| may be positioned on one side of the insert only and the insert formed with projections only on that side; again the layer 4| may be sandwiched between layers of the insert material,

the projections being formed on one side-of the metal layers and compressed into opposite sides of the cushion material, forming facing'layers of metal.

In Figure 16. I have shown an electron discharge tube, wherein the metal supporting parts H for the electrodes are constructed of metal made in accordance with this invention.

In Figures 17 and 18, I have shown auto-body plate material 42 having a suitable resistant finish and/or lacquer 43 thereon constructed from plate processed in accordance with this-invention.

This plate is usually & in thickness.

In connection with the several uses of the material described and particularly gaskets and electron tubes, the heat resistance of the metal, and its resistance to corrosive moisture and oxidative influences, make it highly valuable and efficient.

In the manufacture of caps and containers, the ability of the metal to withstand severe bending and drawing operations, as well as its above mentioned characteristics, gives it a particular utility. Moreover, the compatability of the metal with a tin coating and other coatings or lacquers disposed on the tin coating, as described herein, renders it peculiarly useful for the manufacture of caps and containers, as well as numerous other articles. For example, the metal for making caps or closures will comprise the base 35, a tin coating 36 on each side (Figure 4) and a lacquer (decorative and resistant) coating 31 on one side of the tin, and a thermo-plastic lacquer film 38 on the opposite side (Figure '7).

I prefer an electric furnace or heating chamber of the type having an associated continuous con veyor with electrodes exposed to the material being treated. While other heating apparatus may contrary, the sheets or plates may be of any depredetermined length, strips coiled upon rolls as n at 20, or a continuous strip taken from the electro-deposition'apparatus and passed continuously through the several processing instrumentalities. Also, I prefer a continuous treatment, either utilizing the material as it comes from the electro-deposition apparatus and passing it through the several operations as a continuous strip, or rolling it at one or more points and continuously passing it from the roll to the several succeeding instrumentalities continuously from such points. With respect to the gauge or thickness of the metal, I have found that the invention is operative in connection with extremely thin gauges and likewise ually satisfactory in connection with metal of considerable thickness.

As heretofore stated, the speed of travel of the conveyors and the time of heating and cooling are controllable in accordance with the size and thickness of the sheet. Moreover, the heating chamber and the cooling chamber may be of 'a length so as to prolong the heating or prolong the cooling, as desired. In this connection, separate conveyors for the heating chamber and the cooling chamber may be employed, and these may be so controlled as to speed as to give a prolongation of the heating and cooling effect.

I claim:

The method of processing electrolytic iron consisting of annealing virgin electrolytic iron to 1700 to 2285" F. in a reducing atmosphere, cooling it in a reducing atmosphere and then cold rolling it.

CHARLES E. McMANUS.

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