US2607724A - Apparatus for the manufacture of tapered conductors - Google Patents

Description

G. F. LAING Aug. 19, 1952 APPARATUS FOR THE MANUFACTURE OF TAPERED CONDUCTORS Filed March 29, 1945 4 2 SHEETS-SHEET 1 R m m w.

GORDON F. LAING Y w A G. F. LAING Aug. 19, 1952 2 SHEETSSHEET 2 Filed March 29, 1945 Y. m WW 2 A L mF M m N Q O D D. O 3 s w Y/ B B O\ \NRwQ m Q on Patented Aug. 19, 1952 APPARATUS FIOR THE .MANUF-ACTURE OF 'TAPERED 'CONDUCTORS Gordon F. Laing, Delavan, Wis., assignor to The George W. Borg Corporation, Chicago, 111., a corporation of Delaware Application March 29, 194.5,SerialNo. 585,475

3 Claims. (01. 204-206) The present invention relates in general to methods and apparatus for the manufacture of .tapered conductors, such as are suitable for use in .the manufacture .of none-linear rheostats and .potentiometers, an the object of the invention isto provide new. and improved methods .andapparatus of this character.

The invention maybe considered as an improvement-on the invention disclosed in the pending application of Thomas B. Gibbs et 8.1., Serial No. 525,764 filed March 9, 1944 .(now Patent 2,605,218) which discloses a method and apparatus for making tapered conductors from conductors or wires of nm'iorm .cross section by drawing such wirespthrough .an electrolytic bath, in .w-hichthey are subjected to anodicreduction. The taper. isproduced by progressively decreasing the speed at which the wires are drawn through the bath, thereby progressively increasing the time in .the bath and the amount of metal removed from the wires.

A -feature of thepresentinvention is the use of alternating current in .the electrolytic bath rather than direct current, whichmakes possible a more compact and efficient arrangement of the electrolytic cell system.

,A furtherfeature of the invention is the use of alternating .current of relatively high frequency,.onthe order of 10.00cycles per. second, or higher, which reduces the evolution .of.gas in the 'electrolyticcells and increases the rate of anodic reduction.

The foregoing and other features will .be ,de-

.scribed more injdetail hereinafter with reference e t r l ind ca spart of .atebla benc v-or..[ot r support on which the apparatus is mounted.

The supportlO' has a rectangularjopenins.therematerial .or .sh0uld1have. a lining of acid-proof material.

"The; tank is. dividedinto. two sections; I and II,

Fig. e. .by eniimpervious :and mwmnducfilng .partition. t9. v I

Twobars 1'4 and t5 are provided for supporting the;electrolyt ic c ells abovethe tank. he; one

'end'the 'barsrest on" the "flange 13 of (the tank a d at t e ther end. t e rest on th ros ba l5 which is secured to the sides of the tank, as jindicated in Fig. 1. These bars may be made of suitableacid-proof material such as polystyrene.

There must be at least two'electrolytic cells, and forefiicient operation there should be a considerable number of them. The drawings v*sl rowfourteen cells, indicated by reference char- .acte'r zl to 34, inclusive. These cells and the two. headers ll. and [8 are preferably made'from strips. of polystyrene secured together by means of a cement made by dissolving polystyrene in a "suitable organic solvent.

.Theelectrolytic cell 22 comprises'a bottom strip' 3l, which rests on the bars l4 and 1 I5, the side strips '35 and .36, and. the short end strip '38. These strips are cemented'together as 'previously .mentioned and form a relatively long I and narrow cell which is open at one end and is closed at the other end by the end strip-3'8. The sidewalls 35 "and 36 have slots as indicated at '44, "Fig. .3, and there is a partition 39 near the closed end o f'the cell. This partition is lower 'than the cell walls but is somewhat higher than the bottoms of the slots 44. Between the partition andflthe end wall 3 8 there is an opening AI leading to the pipe-or tube 42. which is cement ed to the bottom strip 31. The reference characters!) indicates an electrode which is-preferably a stripof platinum resting on'the bottom of the cell. At the left hand end the electrode is held down-by the partition"39 as shown in Fig. 3, and-at the right hand end it isbent down aroundtheend of the bottom stripj-l.

'The'cells 23t 33, inclusive, are-the same as the cell'22 "which has beendescribed. The'two end cells-2| and 34 are the same also, except that the' side -walls =-"4-5 and 48 are made-somewhat "longer so as to form the-end walls of theheaders l1 and 1.1

The cells are'arranged on the bars l4 and [5 as shown in Fig. 1, with the odd numbered cells 22', 2. .e h vin their op nds a ne si of the assembly while the even numberedcells :22 .24. s t h thei open dsv on h oth side. The cells arespaced apart by the end walls such as "38, whichshould becemented to the side walls of the'adiacent cells afterthey have been properly lined up. Inthis way the cells are firmlysecured together.

Thehea'der' IT- has the bottom strip 41 and the sidewall strip 4'6 and-the ends are closed bythe extended sidewalls 45- and'48 of the cells 34-and -21. l -b tt strip s shallow notches at [the points where the electrodes suchnas v4|] leave the associated cells,- to avoid leaving a space between the'edge of the strip and the .'ends.0f the I cells. The parts being well cementedtpgether i easie is viQ l l lw ich spans the .row .of .cells and opens intotheeven numbered cells.

wall 49 of the header.

The header It includes the bottom strip 49 and the side strip or wall 50 and is similar to header IT. The header 18, however, opens into the odd numbered cells.

After the cells and headers are assembled as described the joints may be painted with the.-

polystyrene cement to insure that no leaks are present.

The electrodes such as 40 which are associated? with the even numbered cells are all connected to the bus bar 52, while the electrodes associated with the odd numbered cells are connected to' .known construction and need not be described in detail. The pump 53 is located in the well [2, section II, and. delivers electrolyte from section II of the tank to the vertical pipe 55, whence it flows to the header l8 by way of the horizontal pipe 55, the hose '1, theelbow 58, and the channeled block 60, which is cemented to the bottom Ifhe other circulating system includes the motor 56 and a pump similar to pump 53. The pump associated with motor 54'. is located in the Well l2, sectio'nI, and delivers electrolyte fromsection .I of the tank to the verticalpipe 6 I, whence it flows to the header H through horizontal pipe 52, hose 83, elbow 58', and the channeled block 60'.

The volume of electrolyte delivered to the headers is controlled by means of the valves 64 and 67. The stem of valve 54 is threaded into 7 a rectangular plate 66 which is supported on the or the other by meansof a screw driver to raise or lower the V-shaped valve head and thus regulate the effective area of the opening in the bottom l! of the header through Whichthe electrolyte flows from the channel in the block 60. A locknut 65 is provided by means of which the valve can be secured in adjusted position. The valve 61 is similar to valve 64 and regulates th flow of electrolyte into the header [8. 1

The composition of the electrolyte may vary somewhat depending on the kind of wire to be processed. For the manufacture of tapered conductors from Nichrome or similar resistance wire a mixture of ortho-phosphoric acid and sulphuric acid has been found to give good results.

composition, for example, may be as follows:

Parts .In the above formula, the proportions given are by volume. The sulphuric acid is concen- .maintained constant at a fairly high value, 50

degrees C., for example. Although not shown in the drawings, it will be understood that suitable heating and temperature control apparatus will be provided. Apparatus such as disclosed in the Gibbs et al. application previously referred to may be used.

The cell 69 is a washing cell and is supplied with water through a suitable hose connection 68. The water fills the cell 69 to the level of 13 and I l. circuit. The primary winding of the transformer T8 is connected to the single phase A. C. genera- 4 the end wall llover which it. overflows into the outer cell 18 which is drained by the hose 19. The walls of the cells 'EQand '18 are slotted like the walls of the electrolytic cells 2 I, 22, etc.

The first four electrolytic cells 2| to 24 are shown diagrammatically in Fig. 4, with the bus bars 5| and 52. These-bus bars are connected to the secondary winding of the constant current transformer Ill by means of the conductors An animeter H is included in the tor 15 by way of the auto-transformer 12. The generator E5 is driven by the motor it which is supplied with commercial current through the switch Si.

The motor generator set itis employed in order to convert the commercial alternating current having a frequency of 60 cycles per second into alternating current of .higherfrequency, 3000 cycles per second, for example. Otherarrangements for supplying high frequency alter- I nating current could be used.

The wires 8|, 82, 83 and 84 from which tapered conductors are to' be made are carried on the spools B5, 86, $7 and 88, respectively, which are supported for rotation in any suitable manner. Braking devices (not shown) may be provided to prevent free rotation of the spools.

The wires 8i-84 are drawn through the electrolytic cells by winding them on the four take-up spools 855-92. 7 These spools are clamped against thefiange 93 on shaft 94 by means of the wing nut 95.

Two notched guide rods are indicated at 96 and 97. It will be understood that in practice the spools $5'88 are located at least several feet away from the guide rod 99, so that there will be no danger of the wires slipping out of the notches in the guide rod as they unwind from the spools. The same is true as regards the relation between the spools 89-92 and the guide rod 91, although the spacing here is desirable mainly in order to afford the necessary room for a suitable devicelnot shown) for causing each wire to be wound up on its asociated spool in a single evenly applied layer.

The shaft 94 is driven by the motor 98 through the medium of a variable speed mechanism 99. A variable speed mechanism such as is disclosed in the Gibbs et a1. application previously referred to may be used. Another variable speed mechanism which is suitable for the purpose is disclosed in the application of Gordon F. Laing, Serial No. 547,041, filed July 28, 1944 (now Patent 2,422,306). v The operation of the apparatus in the manufacture of tapered conductors may now be explained, it being assumed for this purpose that the apparatus is installed and connected up as shown diagrammatically in Fig. 4.

The Well I2 of the tank having been filled with electrolyte, the switch S3 may be closed to start the motors 54 and 54' which drive the pump 53 and the corresponding pump in the other section of the tank. The operation of the pumps transfers electrolyte from the Well to the headers l1 and 18 from which it flows into the electrolytic cells, header I! supplying electrolyte to the even numbered cells 22, 24, etc. and header I8 supplying electrolyte to the odd numbered cells 2|,

, 23, etc.

anon-24 5, tio'rr 39.1.v As the: electrolyte. continues. to. enter. thecell it. begins; to..overfiow= over; the partition and' iszreturned to'the tank by way of; the drainage :opening ('41. and the tube; 42..- Thus a definite current. of: electrolyte is. established, flowing,

lengthwise of thecell...

The action at:the othercells=is thesame'as described, the: electrolyte. entering; each cell: at its open: end. overflowing the partition at--,the opvpositeuend, .andd'raim'ng. backrto-thetank byway:

offthe: associated drainagegopening. The valves. 64' and? 61' shouldcbe adjusted; to supply an -adequatevolumexotelectrolytetdthe headers l1 and I8, suflicientto maintain a vigorous flow-through the; cells. In: this: connectionit will be understood; that the pumps have some excess capacity andzthat the :valves: are adjusted to limit the volume: of electrolyte delivered to theheaders to the desiredvalue.

It will. be. notedthat the-drainagdtuberlz for. celL 2 2:. andthe tubes rwhich. drain the: other; even numbered cells all. empty into section I, of the tank; fromxwhichelectrolyte is. pumped to the header IT to supply. these even numbered cells. The drainage tubes irom'the-oddznumberedcells, onthe other handempty into section II ofthe tank, from whichelectrolyte is. pumped toheader l8- for the odd numberedcells. .Theodd and even numbered: cells-are thus suppliedby separate cinculating systems which are electrically, insulated from each other by thepartition. IS in theLtank'.

The'wash water may now beturnedon and enters-the" washing cell 59 by way of the. hose connection 68, filling the cell and overfiowingover the end wall 1'! of the washing cell into the outer cell-"I8 whence it isdrained off. through the hose connection I9.

Dueto the slbts-Minthewalls of the electrolytic cells, a certain amount of leakage occurs. The electrolyte which leaks through the slots runs down the outside of thecell walls, which are spacedapart far enough-for this action to take place, and drips intothe tank. There is alsoa leakage of water throughthe slots in the walls of the-washing cell 69; The leaka'ge water collects in the 'outer cell 'l8-in which the-water level is lowerthan the bottoms of the slots due to the location of the drainage opening near the bottom; Accordingly, there no leakage through the slots inthe walls of cell 18: I v

It-may'be assumed now that the four spools of wire 85-88 have been placed on theirsupports as indicated-and that the four take-up spools 89-92 have. been assembled on shaft 94. The wires 817-434 are pulled' off from their respective spools one at a; time and" are" passed under the guide rod 96, over-the'electrolytic cell system, under the guiderodfll; and arefinally attached'to the-takeup spools; notchesbeing provided in the flanges ofithe takeup spools for this purpose. The wires are then adjustedin'the notches of the guide rods and in the slots of the electrolytic cells and washer cells and the spools 85-88 are rotated'backwards if necessary until the wires become taut. It will be understood that the lower sides of the guide rods 96 and 91 shouldbe at the same level or slightly lower" than thebottoms of the slots in the cell walls: so that; as the -wires are drawn through there will be no tendencyv for. them to rise in the. cells.

The operator may now close the switch SI to start the motor generator set l6 l5. The'generator-IS'; having-attainedits running speed, delivers alternating current to the primary winding of the transformer 10, the'secondary winding of which delivers alternating :current to theqelectrolytic cellsystem. The amount of currentflowingin .the.;secondary, circuit is indicated by the. am--. meter H: and-Jit may beassumed that thepauto -a transformer-12' has been adjusted so that the currentrhasthe proper value. The-current should be as high aspossible'consistent with. the. carrying capacity of the wires. In the manufacture of ta.- pered. conductors. having a. largerv diameter of about 5'to;8 mils and'a smaller diameter. of about l mil .orimore; with the apparatus: described about 32amperes per wire may be used. Thehighzcurrrent valueis desirable in order. to-givethe: tapered wiresasmoothsurface.

The anodic reduction of the wires takes place in the odd and even numbered. cellsalternatel'ya Duringthe half cycles in which the bus bar5l is positive. current-flows over a circuit which may be traced from'bus bar 52, platinum electrodes in the even numbered cells, electrolyte in the even numbered cells,- wires- 8.|'--8, electrolytein the odd numbered cells, platinum electrodes in the odd numbered cells, and the bus bar 51, and anodic reduction takes place in the even num bered cells, where the wires are positive with respect tothe electrodes; During the intervening'halr cycles the circuit isthesame-but the-direction of current flow is reversed-and anodic' reduction of the wires takesplace in the odd numbered cells.

The evolution of gas is lessthan in an apparatus using direct current. The gases'produced in each type of apparatus are' hydrogen and oxygen. Both hydrogen and oxygen are produced by electrolysis ofthe water inthe electrolyte. The gases are liberated asatomic hydrogen H and'atomic oxygen 0 and can combine' toform water H2O if given an opportunity to do; so, being otherwise separately converted to molecular hydrogen I-Ia'and molecular oxygen Ozwhich are given ofi as bubbles-of gas.

The reduction in gassing in thepresent ap paratus, using alternating current isbelieved'to be'due to the fact thatwiththis type of apparatusithe gases have a greater opportunity to combine to form water. In the direct current apparatus the hydrogen and oxygen produced by electrolysis are liberatedat difierent' electrodes, hydrogen being liberated at the cathode and oxygen at the anode (the wires), and have no chanceat all torecombine; The hydrogen pro-- duced by anodicreductionof the wires is also liberated at the cathode. In the alternating current apparatus, on' the other hand; the hydrogen and oxygen produced-by electrolysis and the hydrogen produced-by anodic reduction are liberated at the same electrodes, since in each cell the wires function alternately as cathode and anode, and the gases have an opportunity to recombine. The. formation of water in this Way results in some reduction in gassing even if low frequency 60 cycle alternating current is used; The efiect is increased with an increase in the frequency and itis advantageous, there fore; to use a fairly high frequency. Frequencies on-the orderof 1000 to 5000 cycles-per second maybe-used with good results.

The reduction-in the amount ofgassin has the special advantage. that the tendency. to polarizationof the wires is reduced and the ree duction of the wires is correspondingly Haccelerated.

At the same time that the switch SI is closed tostart the anodic reduction process the switch S2 maybe close.d'also,.to start the motor 98.

or conductors having the length and taper .re-

quired. vThese instructions may, for example, specify a wire having a definite number of sec-, tions, the length and pulling speed of which are designated. The length of the sections maybe given in terms of rotations of shaft 94qwhile the pulling speeds may be given as different settings of the variable speed mechanism. These settings are calculated in advance in accordance with the taper required.

Before starting the operation, therefore, the operator will adjust the'knob I of the variable speed mechanism to the correct setting for the first section. Then, as the wires are pulled through, the operator counts the rotations of shaft to keep track of the sections and as each section emerges from the electrolytic cell system she will adjust the knob Hill to the setting which is specified for the next section. A rotation counter may be used in connection with shaft 94, if desired, and will be of assistance to the operator.

When the end sections have been pulled through, and a few feet of wire in addition, the operator will stop the operation by opening the switches SI and S2. The switch S3 may be left closed assuming that more tapered wires are to be made. The wires on the take-up spools are nowcut off one at a time where they emerge from the electrolytic cell system, the winding of these wires on the spools is completed by hand, and the spools are removed from the shaft 94. Four. tapered wires have now been completed.

To make four more tapered wires, the operator will place four empty take-up spools on shaft 94, and reset the variable speed mechanism. The wires 3|-84 are then cut ofi just to the left of the point where they enter the electrolytic cell system and the sections of wire in' the electrolytic cell system are lifted out and'discarded. The ends of the wires on the spools 85-438 are then passed beneath the guide rods and are attached to the take-up spools as before. These matters having been attended to and the wires having been adjusted in the grooves of the guide rods and in the slots of the cell walls, the switches SI and S2 may be closed again, whereupon the described tapering operations are repeated. 7

The apparatus may also be used for manufacturing very fine wire of uniform diameter, starting with a wire having a diameter of 4 or 5 mils such as can conveniently be produced by drawing and reducing it to the desired smaller diameter by pulling it through the electrolytic cell system. The pulling speed is determined in accordance with the reduction required and is maintained constant throughout the operation.

The invention having been described, that which is believed to be new and for which the protection of Letters Patent is desired will be pointed out in the appended claims.

Iclairm:

1. Apparatus for processing wire by anodic reduction, comprising two groups of electrolytic 8 cells, said cells being arranged in a row. with the cellsof one group alternating withthe cells ofthe other group, means for drawing aiwire through said cellsptwo independent circulating. systems for circulating electrolyte through said two groups of cells, respectively, saidisystems including parts made of insulating material for insulating the electrolyte in one system from the electrolyte in the othersystem, an electrode ineach cell, a source of alternating current, and conductors connecting one terminal ofsaid source to the electrodes in one group of cells and the other terminal of said sourceto the electrodes in the other groupv of cells.

-2. An electrolytic cell "system for the anodic reduction of wires, comprising a plurality of electrolytic cells spaced apart in a row, a header extending parallel to said rowon one side thereof and communicating with the odd numbered cells, a header extending parallel .to said row on the oppositeside thereof and communicating with the even numbered cells, two electrolyte storage reservoirs, discharge outlets for the odd numbered cells emptying into the first of said reservoirs, discharge outlets for the even numbered cells emptying into the second of said reservoirs, two pumps for transferring electrolyte from .the first and second reservoirs to the first and second headers, respectively, means for drawing wires through said cells, a source of al-, ternating current, electrodes in the odd numbered cells connected in parallel to one terminal of said source, and electrodes in the even numbered cells connected in parallel to the other terminal of said source.

3. An electrolytic cell system for the anodic reduction of wires, comprising a plurality of electrolytic cells spaced apart in a row, a header extending parallel to said row on one side thereof andcommunicating with the odd numbered cells, a header extending parallel to said row onthe opposite side thereof and communicating with the evennumbered' cells, discharge outlets for the 'odd numberedcells, discharge outlets for the even numbered cells, the discharge outlet for, each cellbeing located at the end op: posite the header with which the cell communi cates, a circulating system for collecting electrolyte from the discharge outlets for the odd numbered cells and transferring it to said first header, a circulating system for collecting electrolyte from the discharge outlets for the even numbered cells and transferring it to said second header, means for drawing wires. through said cells a source of alternating current, cathodes in the odd-numbered cells connected in parallel to one terminal of saidsource, cathodes in the even-numbered cells connectedin parallel to the other terminal of said source, and parts in said circulating systems made of insulating material to prevent current fiow from one group of cathodes to the other group by way of the electrolyte in said headers. 7 V

GORDON F. LAING.

REFERENCES CITED The following references are 'of record in the file of this patent:

(Other references on following page) 9 10 UNITED STATES PATENTS FOREIGN PATENTS Number Country Date Number Name Date 4,120 Great Britain of 1897 1,607,582 Walker Nov. 16, 1926 428,488 Great Brltam May 14, 1935 1,614,562 Lalse Jan. 18, 1927 5 467,024 Great Brltam June 9, 1937 1,721,414 Robe July 16, 1929 683 169 Ge 0 t 31 1939 1,959,531 Hickman et a1 May 22, 1934 many 2,093,238 Domm Sept. 14, 1937 OTHER REFERENCES 2,374,449 Mulcahy Apr. 24, 1945 Journal of the Electrodepositors Technical 10 Society, vol. 4 (1928-1929), pages 137 thru 139.

Claims (1)

1. APPARATUS FOR PROCESSING WIRE BY ANODIC REDUCTION, COMPRISING TWO GROUPS OF ELECTROLYTIC CELLS, SAID CELLS BEING ARRANGED IN A ROW WITH THE CELLS OF ONE GROUP ALTERNATING WITH THE CELLS OF THE OTHER GROUP, MEANS FOR DRAWING A WIRE THROUGH SAID CELLS, TWO INDEPENDENT CIRCULATING SYSTEMS FOR CIRCULATING ELECTROLYTE THROUGH SAID TWO GROUPS OF CELLS, RESPECTIVELY, SAID SYSTEMS INCLUDING PARTS MADE OF INSULATING MATERIAL FOR INSULATING THE ELECTROLYTE IN ONE SYSTEM FROM THE ELECTROLYTE IN THE OTHER SYSTEM, AN ELECTRODE IN EACH CELL, A SOURCE OF ALTERNATING CURRENT, AND CONDUCTORS CONNECTING ONE TERMINAL OF SAID SOURCE TO THE ELECTRODES IN ONE GROUP OF CELLS AND THE OTHER TERMINAL OF SAID SOURCE TO THE ELECTRODES IN THE OTHER GROUP OF CELLS.

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