US1952762A - Process and apparatus for producing sheet metal electrolytically - Google Patents

Description

March 27, 1934.

PROCESS AND APPARATUS s. LEW El AL. 1,952,762 FOR PRODUCING SHEET METAL ELECTROLYTICALLY Filed Jan. 7, 1931 3 Sheets-Sheet 1 March 2?", fi' l 5 m AL 1,952,7fi2

PROCESS AND APPARATUS FOR PRODUCING SHEET METAL ELECTROLYTICALLY Filed Jan. 7, 1931 3 Sheets-Sheet 3 ATTQRNEYS Patented Mar. 27, 134 l v. STATES PATENT oFF cs PROCESS APPARATUS FOR PRODUCING SHEET METAL ,ELECTROLYTICALLY I Solomon Levy, Rutherford, Charles E. Yates, East Rutherford, and William M. Shakespeare, South Orange, N. J., assignors, by mesne assignments;

to Anaconda Copper Mining Company, New

York, N. Y., a corporation of Montana Application January 7, 1931, Serial No. 507,126

24 Claims. (011204-13) This invention relates to the production of thin sheetcopper has been electrolytically prometal in the form of thin sheets by a process of duced in substantial quantities up to the present, electrodeposition and is concerned more particueither for sale as such or for subsequent rolling. larly with a process and apparatus by which a The reasons for the failure of prior 'methods novel sheet metal product maybe produced elecand apparatus for producing sheet copper by trolytically at low cost. The new product is an deposition, at least for commercial purposes, are electrolytic sheet of metal of uniform thickness, manifold. According to these methods, it has free of oxygen, and of uniform quality. .The been the customary procedure to deposit a thin process and apparatus of the invention are -f0il of copper on an endless surface cathode, such adapted to be used in a refinery and in the electroas a drum or a band, and strip the deposit theredeposition, crude metal may be employed to from, and such processes involve an extremely maintain the strength of the electrolyte so that high production cost because the outputnate is in some aspects the invention may be described low and the amount of floor space required per as a continuous refining process characterized in 'ton of metal produced is extremely high.

15 the production of a web of metal of indefinite It has also been proposed to produce a thin 70 length instead of the usual plate cathodes profoil of copperon an endless surface cathode and duced by deposition upon separate starting then build the foil up to final thickness by subsheets. sequently plating the foil while it is in move- The process and apparatus of the invention are ment, the metal being deposited on both faces 9 especially suited for the production of sheet of the foil during the proposed subsequent plating copper and an adaptation of the invention for operation. If such a procedure were followed, that purpose will be described in detail by way of it would be difilcult to produce a smooth'product illustration. It will be apparent, however, that because the foil would normally pass beneath the utility of the invention is not limited to any anodesand slime would fall upon it unless exparticular kind of metal so long as the metal can traordinary precautions involving the use of adbe plated electrolytically with reasonable facility ditional equipment were taken to prevent. Also, to produce a satisfactory deposit. difliculties might be encountered in making the At the present time, sheet copper is produced necessary electrical connections to the moving practically entirely by rolling and the cost of the foil.

finished product increases materially and dis- In most of those methods with which we are proportionately as the thickness decreases. The familiar'in'which an endless band cathode is emcomplete process for the production of such sheet ployed or in which a moving foil is plated to final copper-by rolling involves electrolytic refining in thickness, the plating operations are carried on cells in which crude metal anodes are employed under. such conditions that'crude metal anodes 5 and refined cathodes prdduced, after which the cannot be employed, since the slime which results 90 cathodes are melted and cast into cakes which, from the crude metal going into solution interafter heating, are subjected to a succession of feres with the plating operation and results in rolling operations until sheets of the desired a rough plated surface. 2

thickness result. Because of the rapid and dis- Recognizing the objectionable features and deprbportionate increase in cost of rolled copper as ficiencies of the prior methods and apparatus, the thickness diminishes, sheet copper having the both as used and as proposed, we have devised characteristics of a foil and produced by rolling new equipment for the purpose in which the does not have the wide use commercially that it electrodeposition of the metal is carried on under would have if the cost depended mainly onthe conditions quite different from those heretofore weight of metal. As will be apparent, the cost of prevailing.

rollingoperations necessary in making "metal According to our new method, a thin foil profoils often exceeds the cost of the metal used, duced in any desired manner is built up to final which accounts for the high cost of such foils. thickness by electrodeposition of metal on one Electrolytic production of thin sheets would face thereof. For this purpose, a plating tank appear to offer a method of producing foil at a. is used in which there are mounted a plurality 105 great reduction in cost and many attempts have of anodes in. face to face relation and disposed been made to produce thin sheet copper of coma distance apart to provide spaces between them. mercial quality by such a procedure. So far as The foil is moved through the solution in the we are awaremone of the methods and apparatus tank and is guided so that it forms depending heretofore proposed has been successful and no loops between adjacent anodes without. passing D beneath any anode. Plating current is then withdrawn from the-foil preferably at a plurality of places along its length. With this arrangement of the anodes and foil,,it is possible by placing the first and last anodes in the series'with their faces parallel to obtain a final product of uniform thickness, any variation in the thickness of the plating occurring in one portion of a loop being compensated-for in the other portion of that loop, or in a portion of the next succeeding loop. All portions of the foil are subjected to average current density throughout their travel through the tank, thus insuring uniformity in the weight of the final product. and since the foil does not pass beneath any anode, it is not roughened by the sludge which results from the anode going into solution. Preferably the anodes are so arranged that the foil successively opposes each face of each anode in'the series except the first and last, but if desired, the foil may be so guided as to oppose successively each face of each anode in the series including the first and last. With the latter arrangement, there is a loop of foil in front of the first anode and another loop beyond the last anode in the group and the downwardly moving foil in the first loop and the upwardly moving foil in the last loop do not oppose any anode and thus do not receive any considerable plating.

In one form of the new apparatus. a thin film or foil of metal is plated on an endless cathode surface, stripped therefrom and then led throu h a plating tank along a tortuous path. In such movement, the foil "may be guided by suitable elements which are not affected by the plating solution and may, *if desired, serve as contact means by which the plating current may be withdrawn from the foil. These elements may be so arrangedthat in one construction, the current leaving the solution passes through the foil only substantialln at right angles to the plane thereof, while in another, the current does not travel in the plane of the foil for any substantial distance. In both cases, the current flow through the foil is below the solution level and that arrangement of using this arrangement, sheets are produced,

in which the thickness is of a high degree of uniformity because the plating isnot afiected by stratification in the solution and differences in temperature at different places, nor by variations in spacing between the foil and the anodes. All the anodes are in parallel and similarly all the negative contact elements engaging the foil are in parallel and variations in plating resulting from variable contacts between the anodes or the contact elementsand the bus bars or from a variable space relation between the foil and the various anodes do not affect the final thickness because any reduction in plating which arises from a poor contact at one anode or at one contact element or, from a wider spacing of the foil from one anode than from another is compensated for by increased plating elsewhere. In

order to avoid variation in thickness of the foil because of variation in its spacing fromthe anodes, it is necessary that the end a odes the group lie substantially parallel, and the nearer they are to parallelism, the less variation in the thickness in the final product.

Since the plating is confined to one face only of the sheet, the sheet guided in a loop path between pairs of anodes, thus avoiding the effects of Stratification of electrolyte, and the anodes and cathodes are connected in parallel to ,the bus bars, every point on, the sheet is subjected to average current density during the electro-deposition, provided the end anodes are par allel. This results in uniformity in deposition and in thickness of the final product.

The anodes and the strip being built up have such a relationto one another throughout the equipment that there is a free path unobstructed by the foil from each anode to the bottom of the tank, and, as a consequence, crude metal anodes may be used because the sludge which results from the passage of the crude metal into the solution drops down freely to the bottom of the tank whence it can be removed as in ordinary electrolytic refining and does not come in contact with the surface in which the deposition occurs.

Even if refined metal anodes are used, the results in our apparatus are better than those obtained in others with which we are familiar, in which the foil passes beneath the anodes, because some sludge results even from theme of refined m'etal anodes and when any sludge falls upon the sur-' face receiving the deposit, the latter becomes rough.

The possibility of using crude metal anodes in our process reduces the cost of the final prodthe floor space required per ton of metal output is relatively small. Also, because of the little floor space required, it is not necessary to resort to the high current densities which are required in former drum cathode apparatus to produce a reasonable tonnage and since the output perunit of floor space occupied by. the new equipment is greater than the output with the prior apparatus, the cost per ton of product is proportionately lower.

In the new equipment, it is possible to produce sheets of a thickness well below the limit of ordinary commercial production by rolling, and by using the principles of our invention in a modilied form of apparatus, sheets can be produced of practically any thickness desired. These sheets, regardless of the weight, can be made continuous in any length, although convenience in handling will undoubtedly set some practical limits on the lengths of the sheets produced.-

The sheets produced by thenew method and apparatus are superior in many respects to sheets produced by electrodepbsition in accordance with ordinary prior methods. For som purp ses, where the exact physical properties of rolled metal are required, the new method and apparatus make it possible to obtain sheets of the desired character more cheaply than by ordinary rolling, and for this purpose, sheets may be produced electrolytically by the new process and apparatus which are of greater thickness than is ultimately desired and then rolled to final thickness. Such a rolling operation would change the physical characteristics of the metal, improving its tensile strength and elongation and making'it suitable for special fabrication operations. Bec use of the high degree of uniformity of thickn ss and quality which is obtained in the sheets lee produced by our process, those sheets are especially adapted for subsequent rolling and that is not true of electrolytic shets as heretofore produced because their nonuniformity in thickness results in the production of irregular sheets by rolling.

The invention includes many other features of novelty which will be made apparent in the description to follow, and for a better understanding of the invention, reference may be had: to the accompanying drawings in which Fig. 1 is a view in longitudinal section through apparatus for practicing the processof the invention;

Fig. 2 is a top plan view of the apparatus illustrated in Fig. 1;

Fig. 3 is a vertical sectional view on the line 3-3 of Fig.1;

Fig. 4 is a sectional view on the line 4-4 of Fig. 1;

Fig. 5 is an enlarged end view of a portion of the apparatus shown in Fig. 1;

Fig. 6 is a view in side elevation showing the mounting of a drive roll;

Fig. 7 is an end view of the parts shown in Fig. 6;

Fig. 8 is an end view on an enlarged scale illustrating details of the mechanism;

Fig. 9 is a fragmentary plan view of parts shown in Fig. 8;

Fig. 10 is a sectional view on through a guide element;

Fig. 11 is a sectional view of a portion of amodified form of guide element;

Fig. 12 is a view similar to Fig. 1 showing a modified form of apparatus;

Fig. 13 and 14 are views in front elevation of standard anodes employed in the apparatus;

Fig. 15 is a side view of one of the anodes;

Fig. 16 is a front elevation of a guide and contact element;

Figs. 17 and 19 are vertical sectional views through parts of modified forms of the apparatus;

Fig. 18 is a perspective view of one formof guide element; and

Fig. 19 is a vertical sectional view through another modified form of the apparatus.

Referring now to thedrawings, one form of apparatus for practicing the new process is illustrated in Fig.1 1. This apparatus comprises a standard electrolytic tank 20 into which plating solution is introduced through a pipe 21 and an enlarged scale from which the solution overflows through a drain 22. Extending along the side walls of the tank -at the top thereof on opposite sides are' are connected in the circuit to an elebtrical generator of the type commonly used for refining or plating purposes.

Mounted at one end of the tank is a plating drum generally designated 25. This drum is made up of end discs 26 connected by a cylindrical portion 2'7, the latter being provided with a facing 28 of a metal which permits easy stripping. ,In connection with the deposition of copper, this facing may be of lead, chromium, stainless steel, or the like. The drum 25 is mounted on a shaft 29 supported in bearings 30, 30 mounted on the tank walls and held in .place by bolts 30a. The shaft carries a contact disc 31 which dips into a pool of mercury in the trough 32 electrically connected to the negative bus bar 24. The bearing 30 is insulated from the positive bus bar 23 by a layer of insulation 33. The shaft 29 has a ventilating opening 34 formed in it.

The drum is provided for the purposeof producing a thin foil which is later to be built up in succeeding operations and substantially the entire lower half of the drum extends down into the tank and lies beneath the solution level therein. .iDisposed beneath. the submerged portion of the drum and closely adjacent thereto is an anode assembly. This assembly may be made up of two anodes 35, 36 of the type commonly used in refineries and similar in shape to those illustrated in Figs. 13 and 14. By using such anodes, the formation of special anodes by casting is not necessary.

The anodes 35, 36 to be used beneath the drum are given a curvature so that they conform in shape fairly closely to the outer curvature of the drum and the anodes rest on a support 37 covered with a conducting material such as lead, and disposed within the tank and maintaining the anodes at a close spacing with reference to the drum periphery.- The anodes when placed in the support make contact with the positive bus bar by means oftheir lugs 38, while the lugs 39 which overlie the negative bus bar 424 are insulated therefrom by a strip 40. In the apparatus illustrated in Fig. 1, a pair of anodes 35, 36, are not of suiiicient size to extend around the entire submerged portion of the drum and, in this case, we employ a pair of additional anode plates 38' cut from ordinary refinery anodes and resting on the support to lie between the lower edges of anodes 35, 36. The plates are of such size that they may be slightly spaced apart from each other and from the anodes so that there is a free circulation of the solution between the two plates and between the plates and anodes. Also, this spacing permits the sludge resulting from the anodes going into solution, when soluble anodes are used, to pass down to the bottom of the tank. The plates are in electrical connection with the bus bar through the leadcovered support and the anodes.

Mounted on suitable framework 41 close tothe periphery of the drum and above the top of the tank is a roll 42 and in the operation of the apparatus/the foilor thin sheet 43 deposited on the drum is stripped from the drum surface and led off over the roll 42.

The surface of the drum, from which the metal has been stripped, is cleaned by means such as a driven wire brush 42', which is placed close to the point where the moving surface enters the electrolyte, this brush serving to clean the surface of any foreign matter which adheres thereto and also removing any oxide which may have formed on the surface during its travel beyond the point of stripping. In some instances, as illustrated in Fig. 12, the foil produced on the drum may be stripped -and wound into a roll instead of being passed directly to the subsequent plating tank. and when that procedure is followed, it is preferable to place the stripping roll 42 at apoint close to the brush. Byusing that arrangement. the drum surface is protected from dirt and oxidation by the presence of the foil thereon throughout practically the entire length of the surface which is'outside the electrolyte. Y

The tank wall support a hollow center or skeleton frame 44 of suitable metal construction at a distance from the drum 25, this frame being removable as a unit. On the upper longitudinal members 45 of the frame are mounted a verse axis than elsewhere.

plurality of rolls 46, and each roll has a shaft 46' which carries a sprocket wheel 4'7 on one end. The roll shaft is mounted'\in bearings 48 which are provided with spaced portions 49 which straddle the upright legs 50 of the angle irons which form the longitudinal members of the frame. The mounting for the bearings is such that the rolls can be adjusted lengthwise of the frame and secured in any desired position of adjustment. One of the bearings 51 for each roll shaft is provided with adjustment screws 52 bearing against the top of the lug 50 of the frame member and by means of these screws the bearing can be raised or lowered so as to vary the inclination of the roll to the horizontal.

The sprocket wheels 47 of the several rolls of the series, here shown as six in number, are driven by a chain 53 which passes over a sprocket wheel 54 on the shaft 55 of a roll 56 at the end of the series. The shaft 55 also carries a drive pulley 57 driven by a chain 58 from any suitable source of power and the rotation of the shaft 55 results in rotation of all the rolls 46. The rolls may draw the foil from the drum and cause rotation of the drum as the foil is stripped therefrom or thedrum may be positively driven by suitable means. Each of the sprocket wheels 47 of the rolls 46 has such a number of teeth that the rolls rotate at a slightly higher rate of speed than the roll 56 and this insures that the foil or sheet will be kept taut and not subjected to driving strain concentrated at one point. The rolls 46 serve as a means for controlling the tension of the sheet as it passes around the guide and contact elements and associated with the roll 56 is a roller 59 which contacts with roll 56 and provides a positive drive means for the sheet. By selection of sprocket wheels of proper size for the rolls 46, the tension in'the sheet as it passes around the contact elements may be varied as desired. While the positive drive for the sheet is illustrated as lying at the end of the group of contact elements, it may if desired be placed between the drum and the contact elements, in which event the sheet leaving the elements will be taken up on a take-up roll operated by a friction drive.

Mounted on the frame 45 are elements 60 which may serve both for guidingthe foil and as a contact means for withdrawing plating current from it. In the construction illustrated in Figure 18, each of these elements is a skeleton frame made up of longitudinal members 60a and cross-bars 60b. "There are three cross-bars mounted on the longitudinal members oneach face of the frame, and the-middle cross-bars are .thicker than the outer ones, so that the frame has a greater overall thickness along its trans- The longitudinal frame members are secured at their upper ends to a cross-bar 61, which rests on the lower longitudinal members 62 forming part of the frame 45 and along the outer faces of the two outer members 60a are wooden bars 63. The foil being plated contacts at its edges with these wooden bars and they prevent plating on the inner edges of the foil.

The contact element may be used in the form of the skeleton frame shown in Fig. 18 in which case the moving foil receiving plating makes contact with the several cross-bars and the plating current is withdrawn from the foil through these cross-bars. As there are several cross-bars spaced fairly close together and having a substantial length and width, the plating current is withdrawn from the foil through extended areas thereof and current does not flow through the foil in its plane for substantial distances. Also,

the cross-bars lie beneath the solution level and with this arrangement, danger of injury to the foil by reason of the passage of excessive plating currents through it is reduced, and the power cost is less by reason of the lower voltage required.

For some purposes, it may be desirable to face the skeleton frame with copper sheet 64 (Fig. 10) and a sheet of metal of the proper length is wrapped about the frame from top to bottom and the ends of the metal secured together. To keep the sheet taut, the cross-bar 61 is provided with an adjusting plate 611:. secured to the cross-bar by adjusting screws 61b- These screws pass through openings in the facing sheet and by turning them, the adjusting plate 610, lying with- .in the sheet may be moved away from the crossbar 61 to keep the sheet at the desired tension.

The cross-bar 61of each element is drilled at one end for the reception of an adjusting screw 65 which bears against the frame member, and the frame member is drilled to provide openings for the reception of bolts 66, each of which holds in place an L-shaped clamp 67. -One leg of this clamp bears against the frame member and the other overlies the cross-bar 61 of an element. The latter end of the clamp is slotted as indicated at 68 to straddle the adjusting screw 65.- Secured to the end of the cross-bar 61 through which the adjusting screw 65 passes is a bracket 69 which extends along the frame member and is provided with an adjusting screw.70 bearing on the frame member.

By means of the parts described, a close adjustment of the position of the guiding element may be obtained. The frame member is drilled with a number of closely spaced openings for the reception of the clamping bolts 66 so that the elements 60 may be secured in any desired position along the frame within reasonable limits. After each element is placed, it can be adjusted about a horizontal axis passing through the center of the supporting bar 61 by turning the adjustment screw '70 carried by the bracket 69. Turning the adjustment screw 65 serves to swing the element in ,a plane transverse to the long axis of the tank and the clamp 67 permits the element to be secured and .held rigidly in any desired position of adjustment.

One longitudinal member 62 of the frame is clamped to and in direct electrical contact with the negative bus bar 24, while the other frame member rests on a strip of insulation 71 which lies on top of the positive bus bar 23.

Mounted in depending bearing brackets '72 secured to the upper longitudinal members of the frame are guide rolls 73 and each element 60 is so positioned between a roll 46 and a roll 73, that the rolls are substantially tangent to planes through the opposite faces of-the element. Each element has a rounded lower end 74 and midway between its upper and lower ends the element is thicker than elsewhere, the bulge being indicated at '75. As the foil 43 led from the drum passes over the first of the rolls 46, it is led down one face of the first element, around the lower end, and then upwardly along the other face of the element and over one of the rolls 73' whence it passes over the next roll 46.

By reason of the shape and construction of the elements 60, it will be evident that the foilmakes contact therewith over an extended area and current is withdrawn from the foil beneath the solution level. Since the foil contacts with the element over areas which are fairly closely spaced, the current does not flow through the foil in the plane thereof for substantial distances and-those portions of the foilin which current is flowing in their plane lie beneath the solution so that danger of burning is reduced and a saving in power is effected. Where the element carries a facing sheet, practically one entire surface of each depending loop of the foil extending around a contact element is in electrical contact with the conductive facing of the element below the solution level. The framework of the contact element and also the facing sheet, where one is used, are electrically connected through the bus bar 61 of the element with the negative bus bar.

With either arrangement, the plating current is withdrawn from portions of the foil or sheet which lie beneath the solution and where no-, facing sheetis used, current flowing through the foil in its plane does not travel for any substantial distance whilewhen a facing sheet is employed on the element, the current flows through the foil at right angles to the surface thereof. In

" either case, heavy plating currents may be con-' ducted away with little danger of injury to the sheet. '-Also, only one face of the foil or sheet lies in opposition to the anodes so that all of the deposition occurs on this face.

The anodes employed offer a substantially rectangular exposure to the foil receiving the deposit and may conveniently be of crude metal and of the form used in refineries. These anodes 76 lie between the loops of the foil and have lugs 77 which rest' on the sides of the tank and support the anodes. The lug of each anode which overlies the negative bus bar is separated there-\, from by a strip 78 of insulation whfle the other lug rests directly" on the positive bus bar. The anodes employed may be of a width slightly greater than the width of the sheet, the latter being indicated in broken lines 79 in Fig. 13, or the anodes may be of slightly less width than the sheet, as shown in Fig. 14. If all the anodes were wider than the sheet, the sheet would. build up thicker at the edges than at the middle. If all the anodes were narrower than the sheet, the sheet would be thinner at the edges than elsewhere. In practical operation, anodes of both kinds will be used in proper number to insure uniformity, in thickness of the sheet. These anodes may be of the'two standard sizes normally available in any copper refinery, one size being that used for the production of starting sheets and the other, for regular cathodes.

In the apparatus illustrated, the number of anodes is one greater than the number of elements in the group so that there is an anode adjacent the face of each portion of the sheet in each loop. Since metal is deposited on the sheet in the form of a loop which lies between a pair of anodes, it will be evident that if any element is slightly out of adjustment so that one side of the loop lies nearer an anode than the other side,

, any tendency to produce a heavier plating on the near side will be compensated for by reduced plating on the far side. Thisresults in the sheet .being built up by a definite and uniform amount. in its travel through each loop and results in a sheet iof uniform thickness provided the end anodes are-parallel.

The loop and anode assembly is so arranged as to occupy little spacelengthwise of the tank and the area of the sheet in that portion of each loop which lies beneath the solution level is approximately the same as'the areas of the submerged portion of the drum so that by the use of the depending loop arrangement, deposition at a rapid rate can be accomplished in a relatively small tank occupying little floor space for the amount plated at a much lower current densityyand as a lower voltage is employed, the power cost is proportionately reduced. Accordingly the cost per pound of that part .of the final sheet which is made up of metal deposited in the building-up tank is considerably less than the cost per pound of the metal produced on the drum,,a n d in" the present process, thestarting foil is very thin and the great bulk of the final sheet is metal plated on the'starting foil after it leaves the drum. l

After the sheet has passed around the last element limit is led off around the roller 59 and between that roller and the roller 56, whence it travels around the surface of the roller 56 and is led oif to any suitable take-up device.

It will be observed that in the loop assembly, the sheet passes down into the solutionfrom above so that no openings through the walls of the tank are necessary asin certain apparatus with'which we are familiar. When the sheet is passed into thetank through a side wall, difllcultie's are encountered in making the opening tight against the solution. Also, "by having the sheet pass verti- A further desirableresult obtained by movement of the foil in the manner described is the elimination of variations in plating due to stratification in the electrolyte. In the plating opera tion, the solution at the. top of the tank may contain less metal and more acid than that at the bottom and the temperature 'of the solution may be higher at the top. Accordingly if a sheet is passed throughsuch a tank in a horizontal direction and in a vertical plane, different portions of the sheet will be plated in difierent conditions of concentration and conductivity and this will result in a variation in the amount of metal deposited and in the character of the deposit.

Similarly if a group of sheets were passed horizontally through a tank in different-horizontal planes one above another and at the same rate of speed, there would be a variation in the amount of metal deposited on the different sheets in accordance with their positions relative to the bot-.- tom of the tank. With the present process and apparatus, the foil moves through theelec'trolyte vertically so that the foil passes through the different strata in the electrolyte and the effect of stratification is thus overcome.

In the construction illustrated in Fig. 1, the

drum cathode and the loop assembly are arranged in a single tank and the guide and contactcathods are connected electrically in parallel with the drum cathode. With such a unit, it is possible to supply the tank with plating currents of the order of 6,000 to 8,000 amperes and utilize relatively moderate current densities. In the construction illustrated in Fig. 12 the cathode drum is in one tank 80, while the loop assembly is in the second tank 81. Also the foil produced on the drum is not led directly to the second tank but wound into a roll, and foil is delivered from such a roll to the second tank.

Either arrangement may be used as desired and we contemplate that in'some instances it may be desirable to install a number of tanks containing drum or other types of endless cathodes which will operate to produce thin foils. These foils may then be rolled up and supplied in roll form to the building-up tanks. With this arrangement, the rate of deposition in the buildingup tank is not limited by the speed at whichthe metal can be deposited on the drum.

While the arrangement illustrated in Figs. 1 and 12 is satisfactory for the production of sheets in a relatively wide range of thicknesses, diificulties may be encountered in the production of heavy sheets by the use of that form of apparatus inwhich the sheet passes through a 180 curve around the end of each guide element. To some extent this diificulty may be overcome by mounting a roll 81' at the lower end of the element to facilitate movement of the sheet. For heavier and stiffer sheet, it is preferable to use modified forms of the loop assembly illustrated in Fig. 1.7. In'Fig. 17, a guide and contact element 82 of special form is used, and this element has a narrow opening through the center of it from top to bottom, the opening being of a size sufficient to permit the passage of a-pair of sheets 83 drawn from supply rolls 84. The sheets 83 receive little or no plating while passing down through this opening. At the bottom of the contact ele ment, the sheets are separated and led around 'and up the opposite faces of the element. Each of these faces is provided with a conducting Jacing 85 which is in electrical contact with the neg ative bus bar of the cell. Anodes 86 lie one on each side of the element in close proximity to the opposite faces thereof. 1 1

' With this arrangement, the two thin sheets or foils drawn "from supply rolls 84 pass down through the guide and contact element without receiving any plating and since these sheets are relatively thin and flexible, no difilculty is encountered in leading them through the 180 turns at the bottomof the element. All of the plating on the sheets occurs in their upward travel and thesheets can be built up in this upward passage to the desired final thickness. By this procedure, sheets may be produced having a weight much greater than is possible in that.

form of 'the equipment illustrated in Fig. 1.

For still heaviersheets, the apparatus illustrated in Fig. 17 may be used with a slight modification. Where the foils in their upward travel are to be built up to a-relatively great thickness, it may not be'feasible to bend the resulting sheets in their upward travel and the sheets may be led directly upward from the tank to a place where they can be cut off in desired lengths.

In Fig. lethere is illustrated a modifiedform of the equipment by which a number of foils supplied in the form of rolls 92 may be built up simultaneously. These rolls are mounted in any suitable supports and the foils therefrom are passed downwardly and around guide and contact elements 93 of the construction shown in -Fig. 1. The built-up sheets 94 are then led ofland around guide rolls 95 and a plurality of the sheets may be led away from the tank by means of a group of suitable feed rolls not illustrated. I

It will be observed that in all-of the forms of the equipment shown, the sheet on which deposition occurs never passes between the bottom of the anode and the bottom of the tank.- Thisv makes possible the use of crude metal anodes and results in reducingthe cost of the final product to a great extent. With this equipment, it is possible to produce'sheets in a wide range of thicknesses and in indefinite lengths and the sheets are of a high degree of uniformity of thickness. The equipment has a high capacity per unit of floor space and the power cost is relatively low. Even though unusually heavy plating currents are.,employed, there is no danger of injury to the sheets, since the current is withdrawn therefrom over large areas and contact of the sheet with the parts connected to the negative bus bars occurs beneath the solution level. The limitation of the plating to one side only of the sheet also results in the production of a sheet which has one surface of a high degree of smoothness.

Since'the cost of the sheets produced by the method and apparatus of this invention is approximately proportional to the weight of metal involved, the cost varies directly with the thickness of the final product, whereas, in the case of rolled sheets, the cost increases out of all proportion to a decrease in thickness. In our method, as the weight of the sheet increases, a limit is ultimately reached at which the cost is approximately the same as that of producing such sheets by rolling, but for the production of sheet copper of the foil type, our method and apparatus may be employed much more cheaply than the rolling process. For the class of foils, thecost of production' by rolling is so high that the use of thin rolled foils is comparatively limited and such foils have not gone into wide commercial use for many purposes for which they would be admirably adapted except for cost. Our process, accordingly, permits the economical production of sheet copper in weights which have never been in widecommercial use up to the present time.

The process and apparatus of the invention also make possible the production of foils in wide widths without an increase in cost out of proportion to 'the weight of metal present. Heretofore, ithas not been feasible to produce foils by rolling in widths in excess of approximately 15 inches because of the mechanical diificulties involved in constructing and operating the rolling equipment. Also, the cost of rolled foils of a given weight increases with the width, due to the increase in the amount of scrap produced. Our process may be used for producing foils in any width' desired, although for practical purposes, foils will not be produced by our process in widths exceeding 3-1 inches which is the maximum possible instandard refining tanks. The cost of foil per pound of metal is notsubstantially affected in our process either by gauge 'or width.

The sheets produced in our equipment may be usedin subsequent rolling operations.

For this sired thickness and in suitablelengths, severeduse of lead anodes adds slightly to the power cost from the main web in production and then rolled by the usual equipment. Because the sheets produced by our process have a high degree of uniformity, they are particularly well adapted for rolling and straight sheets can be produced in the rolling operation. Such rolling provides sheets or foils having characteristics quite different from those produced electrolytically and sheets or foils produced by electrodeposition and subsequent rolling can be made at less cost than sheets or foils of the same weight produccd entirely by rolling because of the saving afforded by our process in the elimination of the casting step and the preliminary. rolling operations.

In another aspect, our invention makes pos-- sible continuous refining, the final product being a roll of continuous refined sheet metal of indefinite length produced from crude metal, instead of a plurality -of separate cathode sheets requiring individual handling. This product may e produced in a refinery at the same output rate fas' that at which refined cathodes are produced under similar conditions and in the same tanks. Also, in electrolytic refining as now carried on, the product is a cathode of limited size and is not a final product but an intermediate, which is not useful for any purpose except by being converted into other forms by such operations as casting and rolling. With our invention, crude metal may be transformed into afinal commercial product per content because ,the soluble anodes not only go into solution at a rate proportionate to the rate of deposition but they are also attacked and dissolved by the chemical actionof the free acid i in the electrolyte. Accordingly, a certain number .of'liber'ator tanks'arenecessary in the tank house to keep the copper contentin the electrolytetrom increasing.

Our process is admirably since insoluble anodes may be used to great advantage in the drum tank. which then serves as a liberator tank. As previously pointed out, the cost of the drum equipment, the expense of maintaining the drum surface, the amount of floor space required for the drum equipment etc.,

.raise the cost of the metal in the foil produced 'on the drum above the cost of that deposited in the loop tank. Economic reasons, therefore, dictate that as higha current density as possible be used in the drum tank, and insoluble anodes are best adapted for high current density use because the gassing, which occurs at these anodes during operation, serves to agitate the electrolyte and cause circulation in the space between the anodes and the drum. When crude metal anodes are employed, rapid circulation of the electrolyte is undesirable because this would bring the sludge, resulting from the anodes being dissolved; into contact with the deposit and cause the deposit to be rough.' Accordingly, in carrying on a refining process in accordance with our invention, it is best to employ lead anodes in the drum tank and crude metal anodes in the loop tank. While the adapted for refining per pound of metal produced, this is more than offset by the economies above mentioned.

The product produced by our process is a final commercial product of sufi'icient uniformity so that it-may be converted directly into rolled copper without the necessity of an intermediate casting operation and many rolling operations. The economic advantages of the new process and apparatus will, therefore, be apparent.

What we claim:

1. In a process of producing sheet metal, the steps of leading a foil down into a plating cell and up and out thereof while positively guiding the foil in such movement, and plating metal only on the upwardlytraveling portion of the foil. r

2. In a process of producing sheet metal, the steps of leading a foil down into a plating cell and up and out thereof while positively guiding the foil in such movement, and depositing metal only on the upwardly traveling portion of the foil and on one face only thereof. 3. A process of producng sheet metal which comprises moving a pair of foils in face contact relation downward into a plating cell, separating the foils-and advancingthern upward in spaced relation, and depositing metal on the 'upwardl moving porton only of each foil.

4. Apparatus for electrodeposition which comprises aplating tank, an anode therein, a plateone face of the element and in contact therewith and upwardly along and in contact with the other face of'the element, the upwardly traveling portion of the foil lying adjacent the anode, and said element having an electrocon'ductive surface with which said foil contacts.

6.,"Apparatus for electrodeposition wh-chcomprises a plating tank, an anode therein, a stationary plate-like guide and contact element in the tank, .said' element having an electroconductive surface,nieans for moving a foil 'in contact with the element down and in contact with one face of the element, around the lower end thereof, and upwardly along and in'contact with the other face thereof, and means for withdrawing plating current through the foil in contact with said surface of the element.

7. Apparatus for electrodeposition which comprises a plating tank, a pair of plate-lke anodes disposed in face to face relation therein, a guide and contact element of generally rectangular form between the anodes, this element having electroconductive areas, means for moving a foil contact with the element down and in contact w thone face thereof, around the lower end, and up and in contact with the other face, and means for withdrawing plating current from said foil through said areas. V

8. In apparatusfor electrodeposition, a plating tank having a positive and a negative bus bar on opposite sdes thereof, a frame supported above the tank and having a portion of conductive mabus bar, a plurality of negative contact elements supported on said frame and electrically connected to said portion of the frame, a plurality of .terial in electrical connection with the negative with said elements, said foil having the form of loops lying between said anodes.

9. In apparatus for electrodeposition, a plating tank, a guide element supported above the tank walls tb hang, down into the solution in the tank, and means for adjusting the position of the element about a plurality of axes.

10. In apparatusfor electrodeposition, a plating tank, a guide element supported above the tank walls to hang down into the solution in the tank, means for adjusting the position of the element about an axis and also along the tank, and means for securing the element in adjusted position.

11. In a process for producing sheet metal, the steps of mount'ng a plurality of anodes in spaced relation in an electrolytic tank to lie transverse- 1y thereof, the effective area of said anodes beneath the solution level in said tank being substantially rectangular, and moving a cathode sheet past said anodes successively and in such fashion that each face of each anode except the end anodes is continuously opposed by a portion of the sheet without the sheet moving beneath any an de. I

12. A process for producing sheet metal which comprises mounting a plurality of anodes in spaced relation in an electrolytic tank, said anodes lying in a series along the tankwith each anode having an effective area of generally rectangular shape beneath the solution level in the tank and with the faces of said anodes lying across the tank and advancing a cathode sheet of indefinite length past said anodes successively, said sheet moving edgewise and continuously opposing each face of each anode without pass'ng beneath any anode. 4

13. In a process for continuously refining metal, the steps of mounting a series of crude metal anodes in an electrolytic tank, said anodes extending across the tank connecting said anodes to the positive side of a source of electric energy, and moving a cathode surface past and in opposition to both faces of each anode to receive a deposit without passing between said anodes and the bottom of the tank. I

14. Apparatus for electrodeposition which comprises an electrolytic tank, a pair of anodes in said tank in spaced face-to-face relation, said anodes lying across the tank and having effective areas of generally rectangular shape lying beneath the solution levelin said tank, means for advancing a foil through said tank, means for guiding the foil in opposition to both faces of each anode without said foil passing between said anodes and the bottom of the tank, and 'means ,for

withdrawing plating current from said foil.

15. An apparatusfor electrodeposition which comprises an electrolytic tank, a pair of anodes in said tank in spaced face-to-face relation, said anodes lying across the tank and having an effective area of generally rectangular shape beneath the solution level in the tank, means for I advancing a foil through said tank, meansfor guiding the metallic foil along a tortuous path in which the foil passes successively in opposition and substantially parallel to each face of eachanode without passing between an anode and the bottom of the tank, and means for withdrawing plating current from said foil.

new

combination of a plating tank, a plurality of anodes mounted vertically in said tank in a spaced series extending lengthwise of said tank, means for moving a foil of indefinite length through said tank, means for guiding the moving foil to give it the form of depending loops entering said tank and lying between the anodes, said foil in its movement opposing successively each face of each anode without passing beneath any anode, and receiving a deposit on one face only in its movement, means for supplying current to said anodes, and means for withdrawing plating current from said foil. 1

17. In apparatus for electrodeposition, the

combination of a plating tank, a plurality of an odes mounted vertically in said tank in a spaced series extending lengthwise of said tank; the first and last anodes in said series .being mounted with their 'opposedfaces substantially parallel, means for moving a foil of indefinite length through said tank, means for guiding the moving foil to give it the form of depending loops entering said tank and having substantially parallel sides, said foil in its movement opposing successively each face of each anode without passing beneath any anode, and receiving a deposit on one face only in-its movement, means for supplying current to said anodes, and means for withdrawing plating current from said foil.

18. In apparatus for electrodeposition, the combination of a plating tank, a plurality of plate anodes mounted vertically across said tank in a spaced series extending lengthwise of said tank, means for moving a foil of indefinite length through said tank, means for guiding the moving foil to give it the form of depending loops entering said tank and lying between adjacent anodes, saidfoil in its movement opposing successively each face of each anode without passing beneath any anode, and'receiving a deposit'on one face only in its movement, means for supplying current to said anodes, and means for withdrawing plating current from said foil at a plurality of points along said tank.

19. Apparatus for electrodeposition which comprises a plating tank, a I plurality of anodes mounted vertically in said tank in a spaced series extending lengthwise of said tank, means for moving a foil of indefinite length through said tank, means for guiding the moving foil to give it the form of depending loops entering said tank and lying between adjacent anodes, said foil in its movement opposing successively each face of each anode except the first and last in the series without passing beneath any anode, and receiving a deposit on one face only in its movement, means for supplying current to said anodes, and means series extending lengthwise of said tank, driven.

rolls at one end of said series for drawing afoil through said tank, means for guiding the moving foil to give it the form of depending loops entering said tank and lying between adjacent anodes,

said foil in its movement successively opposing each face of each anode without passing beneath any anode, and receiving a deposit on one face onlyin its movement, a roll at the top of each loop adapted to be driven to assist in the advance of the foil, means for supplying current to said anodes, and meansfor withdrawing current from said foil.

16. In apparatusfor electrodeposition, the 21. A-methodof el'ectrodeposition which com- 3 prises advancing a foil through a plating cell containing a plurality of anodes mounted vertically across the tank in a spaced series, guiding the moving foil to produce downwardly extending loops with the foil successively opposing each face of each anode, without passing beneath any anode, supplying current to the anodes, and withdrawing current from the foil at aplurality of spaced points along its length.

22. Apparatus for electrodepos'ition which comprises a plating tank, a plurality of anodes mounted in said tank in a series, said anodes lying face to face with spacesbetween, means for advancing a foil through the tank, means for guiding the moving foil to give it the form of a plurality of loops lying in the spaces between'the anodes with the foil passing underneath no anode in the series and opposing each faceof each anode in its movement, means for supplying current to said anodes, and means for withdrawing plating current, from the foil.

23. In apparatus for electrodeposition, the combination of a plating tank provided with a positive bus bar and a negative bus bar, a frame supported above the tank and having a portion of conductive material in electrical connection with the negative bus bar, a plurality of guide elements on said frame, a plurality of anodes mounted in the tank and in electrical connection with the positive bus bar, said anodes alternating with said elements, means for withdrawing plating current from said foil, said means being in electrical connection with said negative bus bar, and means for moving a foil through said tank and in contact with said elements, said foil beingguided'by said elements to form loops with each face of each loop opposed by one face of an anode.

24. In apparatus for electrodeposition, the combination of a plating tank provided with a positive bus bar and a negative bus bar, a frame supported above the tank and'having a portion of conductive material in electrical connection with the negative bus bar, a plurality of negative contact elements mounted ,on said frame in electrical connection with said portion thereof, a plurality of anodes mounted in the tank and in electrical connection with the positive bus bar, and means for moving a foil through said tank and in contact with said elements, said foil having the form of loops lying between said anodes with each face of each anode opposed by one side of a loop.

SOLOMON LEVY; CHARLES E. YATES.

WILLIAM M. SHAKESPEARE.

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