US2372567A - Plating rack for optical dies - Google Patents

Description

A. K. GRAHAM ETAL PLATING RACK FOR OPTICAL DIES 1 March 27, 1945.

Filed Dec. 10, 1941 2 Sheets-Sheet 1 EIETE 1-75 A. KENNETH GRAHAM CHARLES V. SMITH By FRANK P. WILLIAMS 3/ 9 Q Jan-mama's PLATING RACK FOR OPTICAL DIES Filed'Deq. 10, 1941 2 Sheets-Sheet 2 INVENTORS A. KENNETH GRAl-IAM CHARLES v SMITH BY F! WILLIAM $59 $04.;

ATTORNEY Patented Mar. 27, 1945 UNITED" s PATENT PLATINGRAGK FOR oer-lonunms Arthur KennethIGraliam, Jenkintown, Pa., and? Charles'V; Smith ahdIFrank R: William's,vD'ay-' ton, Ohio, asslgnorsto TheUnivis Lens c'ompany,,D ayton, Ohio, a corporation'of Ohio Application December 10, 1941; s ri 1.-No.-422-,32o:

This invention relates to plating rack, andmore partiomarlyrteaal plating rachlfor optical dies.

I111 the plating of. optical dies; that is to say,

V dies having accurate'dioptric curves; it is requisite that theaplatebe deposited as a thoroughly unifoi'm.and homogeneous:--1ayer free 'fi'om-flaws and blemishes and'adapted to be ground and polished tola'r high degree of precision; in view of the faot thata surface curvature aberration of asJittleassix 1 millionths of an inch will suffice to produce lenses unsuite'd for ophthalmio purposes:

It isthus n'eoessarythat the 'surface to be plated be in the bestr'iossible oondition toreceive the" plate; and therefore, it should be in an active state:

Plating racks-hitherto usedhave had' thedrawbaok ofibeingcumbersome and requiring 'too"1ong;

a, tirnetd mount the object to beplajted thereon; with the result that passivation of the metal sur= face presents itself as an undesirable feature leadingtoi' improper'plating' and the consequences that suoh a condition brings about:

The platingrack of our invention is eminently well aol'apted" w avoid such undesirable" consequences? 'It'"is' adapted to receive' the object to bejjlatedj such a's'an optical die, with a minimum of delay; and properly to locate 'it'withirespect' tothe anode to insure the. obtainment or a. plate. of"uniform thickness and homogeneous texture substantially corresponding in surf ao'e c'ontou iito, r the mumate surface ds iiedin tl'iel op'ti calvdi.

Thelplating rack offour. invention, because. of

the. easetwith which it is" handled andlthe details of its. construction and arrangement. of parts floringsab'out certain other benefits. Forinstance,

thefstruoture issodesignedthat itis free from and contamination from any intennediatetreat mentv.

Eurthennore, .the anode canbe pre-set tot-any, desired or required position, removed for activa tion; and then quicklyreset, before substantial passivation of the etched .or treated surface has taken placec Theanode isalso prehurrnedlsub stantially tothe; desired':- curvature,-, wherebu, as previously stated, a uniform substantially diop trically curved plate isdeposited gnthe eathocle It l-might. "be added thatt ittis desirable: to.- have the-curvature of the: anodewmatch; that; ofthe cathodez-withini /xtot giof a diopter; Itiis; like-z wisegadesirable 1 but; not requisite; than all parts:

' recesses whiohlinight .aotlfas acid traps, and thus it preventscontamination of the platingibath by inclusion of. etching, mediumv carried over fromv i 401 theletohingbath. Likewise, there is no carryover incontaet Withthe plating;solution shouldbe of stainless steel'orv non-fenous metal in order to;

prevent lironlcontamination; Ferrous-metals may beyused if properlyn protectedwith suitable stopoff. Of course, the; anode is of lead.

Besides theadvantagesof: the platin gjracl;- of ourvinvention which'haverbeen set forth herein v before, thereare-others whichwill appear evident" from the following description; taken in Fig. 5 is a side eievationiof a modifiedformzof cathode mountingihavin'g atwir thief Surround; ing' tlsie cathode; v o i Fig: (i is'a: front elevation of? the Same;

Fig; 'Z isan enlarged oross-seotionalview of'a' die-plated withounusing-the wire thief; and

Fig. this-an enlarged cross-sectional view of adie' plated using thewire thief as shown in Figs.

5 and:

Referring-in detail ticularly toFi'g. 1; l 0 isa plating tank containing pletingsolution H; anode |3(s'ee Fig. 2); l4- is 'the" bu'sbar carry-'- ingthenegativepole to thecathode (clieft'o be' plated? 15; and] His a-souroe of eleotrie'current.

Referring now to Fig; 2, I T'is aninsul'atedstructween-which the anode is mountedbymeans of bolt [8 andn'uts IBa'nd 20, and2l iSaninsUlated structure carrying thecathode (die id be plated") ls ihe'ldfimplace by'spider '22, bo1t123'3and nut 24; Bolt:23"and"nut"2'4?also serve to affix bus bar l4 firrnly, against the. insulated structure 21 and bolt 23"'earriesith negative polirom bus bar. '4 'to the.

cat ode lfiiwhich is the die to be plated.

K rod'25is' threaded atoneendand provided with' nut? 26, and; nut 21 which. serve. to lock Q in place. th insulated" structure 2] at its lower extrern'iti and rod-v2 8. threadedtatoneendi is providedlwith. nut. 2.91 and nut 30 which serve to look inxplace insulatedl structure 2 le at its: upper extremity.

Rod 25 i is "provided a at its unthreaded. end with a shoulder, 3 adapted to. restv against insulated.- structure l1 and a wedge- 32 adaptedjto. cooper ate with shoulder 3|: for; the PUPHOSG'JOfLSBCUIGlY holding insulatedstructure. IT. Likewisetrod 281 is providedia't itszunthreaded 'endr'with :a shoulder to the drawings, and par 33 and a wedge 34 adapted to cooperate with each other for the purpose of securely holding insulated structure ll.

Referring now to Figs. 3 and 4, it will be noted that rod 28 has a counterpart rod 28' provided with a nut 30, a shoulder 33' and a wedge 34'. It will be understood that the elements 28', 30, 33' and 34' are the duplicates of elements 28, 30, 33 and 34 hitherto described.

The modification shown in Figs. 5 and 6 proves advantageous, particularly when heavy plates are being deposited on the surface of the die. A wire thief 36 shaped in the form of a loop is placed in position surrounding the cathode l5. The opposite end of the wire thief is brought into electrical contact with the bus bar M; This contact may be effectedby looping the wire thief, as at 31, over a screw 38 held in place by a nut 39. The shank 40 of the wire theif is insulated.

When the die is plated in the absence ofa wire thief surrounding it, the plate 4| deposited thereon exhibits a heavy shoulder portion 42 (as shown in Fig. 7) which proves highly undesirable since it must be ground off or otherwise removed and the plate may be damaged in so doing. When the wire thief is in position, as shown in Figs. 5 and 6, the plate M deposited on the die 15 exhibits well rounded shoulders 43, as shown in Fig. 8. The use of the wire thief is highly desirable because it effectively prevents a piling of an excessive thickness of metal at the edge of the die, which would require an excessive amount of grinding on finishing the die in order to restore the plated surface to the proper dimensions and curvature.

By way of example, we now describe a typical procedure to be followed in assembling for use the lating rack of our invention.

The die IE to be plated is attached to the spider 22 and bolt 23 with which it forms a unitary structure. Bolt 23 is mounted on insulated structure 2| and tightened thereon through the means of nut 24 after positioning bus bar l4 as shown in Fig. 2. Bus bar l2 carrying the anode I3 is permanently but removably mounted on insulated structure I! by means of bolt l8 (which is permanently attached to anode 13) through the means ofnut I 9 and nut 20. The distance between the cathode l5 and the anode I 3 is determined and regulated by adjusting nut 29 and nut 30 on rod 28. nut 29' and nut 30 on rod 28, and nut 26 and nut 21 on rod 25. The cathode i5 is definitely positioned and centered by movement of insulated structure 2| which is pro vided with loose fitting perforations at the points where rods 25, 28 and 28' pass therethrough.

Having thus mounted the' die to be plated (cathode 15) in the desired position with respect to anode I3, wedge 32, wedge 34 and wedge 34 are removed and insulated structure l1 carrying anode l3 permanently mounted thereon through the means of bolt I8, nut 19 and nut 20 is then withdrawn from the assembly. The remaining parts of the assembly (that is to say, every memher not permanently attached to insulated structure i1, and the wedges 32, 34 and 34') are then introduced into the etching bath and are given any other treatment required prior to plating as a unit. After completion of the etching treatment and any other treatment desired or required to be given the cathode prior to plating, the assembly is again completed by mounting insulated structure I! on rods 25, 28 and 28' and securely looking it in place by means of wedges 32, 34 and 34'. This operation can be carried out in a matter of seconds and the anode will lie with relation to the cathode in the exact pre-set position. The complete assembly is then introduced into the plating bath and the plating operation proceeds according to the usual manner.

It will be noted that there is a space 35 between the spider 22 and the cathode IS. The purpose of this spacing is to provide rapid and complete drainage of the etching solution or any other solution with which the cathode is treated prior to plating. This rapid and complete drainage prevents carryover from one bath to another and thus the plating bath is kept free from contamination.

The anode I3 is integral with bus bar l2 and they are both formed in a single operation by means of a simple pressing step. As has hitherto been pointed out, the curvature of the anode face is made substantially to conform in opposite sense with that of the cathode. This is brought about by forming the anode using a forming die having usbstantially the same curvature as the optical die to be plated.

As has hitherto been noted, the apertures on insulated structure 2| through which rods 25, 28 and 28' pass are provided with a loose fit in order to permit centering of the cathode with relation to the anode. Because of this fact, it is obvious that the anode must retain a fixed position at all times and this is brought about by providing a close fit on the apertures which serve to mount insulated structure I! on rods 25, 28 and 28.

In view of the foregoing, it will be readily appreciated that the plating rack of our invention is eminently well adapted to carry out plating operations of the character hereinbefore described; that is to say, plating operations Where uniformity of plating thickness, homogeneous texture, and freedomfrom surface flaws and blemishes are of paramount importance and where ease of assembly and manipulation is a desirable characteristic in order to insure a plate of the highest quality which may be subsequently ground and polished to close tolerances or to The speed with which the plating rack of our invention may be assembled not only lessens the possibility of passivity being established but also lessens the development of objectionable tarnish on the metal die prior to plating.

Needless to say, it is highly advisable to eliminate dissimilar materials in the construction'of the rack in order to reduce the possibility of metal contamination of the bath. Furthermore, the current carrying members should be of ample size and all parts of the rack should be properly insulated with some stop-off material of suitable characteristics in order to avoid current leakage and the possibility of attack on the materials of construction of the rack.

Those skilled in the art will readily appreciate that one of the features of the rack of our invention is that it affords the opportunity of close inspection of the significant surface of the die during the preparatory cleaning steps, and, furthermore, that it affords the opportunity of swabbing the die surface during treatment prior to plating.

The wire thief hereinbefore described and illustrated in the drawings is a desirable feature inasmuch as it is advantageous in improving the uniform distribution of metal on the significant surface of the die. As will be noted, such a wire asvacc'z rack:

It .willrbe understood that while we. have set";

forth: a particular embodiment off our invention; we do l'lOti intend "to .have our invention: limited to orz'circmnscribedbyuthespecific details of; st'ruceturei and; arrangement" of parts or manipulation". l 1 herein set. forth. since: our inventionmay be" varied. within the spirit'and scope.ofztherappendedr.

claims.

Iclaimrz. i 1*. Ina plating rack of the type describedin combination: an anode having a support substanetie-113 centrally disposedon the back portion thereof: a cathode havinga spider support on the back: thereof insulating: means adaptedtoreceive-the support of saidianode andmaintairr it':

in fixed-: positional relationship: therewith, said insulating: means being provided with a plurality ofapertures-; insulating means adapted to receive the support' oisaid cathode and maint-ain it in fixed positional relationship therewith, said insulatingmeansbeingprovided with a plurality of apertures, means for rigidly supporting each of said 'insulating -me'ans' in spaced predetermined juxtaposition and adapted to permit removal and replacement of said anode and said cathode without altering their predetermined juxtaposition, yet capable of adjustment to vary the distance between said anode and said cathode when desired, said supporting means including a plurality of bars which are adapted to tightly fit the apertures in the cathode insulating means and adapted to loosely fit the apertures inthe anode insulating means, a stop means on said bars adjacent said anode insulating means, and.

wedging means cooperating with said stop means to tightly press said anode insulating means against said stop means.

2. In a plating rack of the type described, in combination: an anode provided with a substantially accurate dioptically curved surface and having a support substantially centrally disposed on the back portion thereof, a cathode having a spider support on the back thereof and provided with a substantially accurate dioptically curved surface, said curved surface being in the opposite sense to the curved surface of said anode; insulating means adapted to receive the support of said anode and maintain it in fixed positional relation therewith, said insulating means being provided with a plurality of apertures; insulating means adapted to receive the support of said cathode and maintain it in fixed positional relationship therewith, said insulating means being provided with a plurality of apertures; means for rigidly supporting each of said insulating means in spaced predetermined juxtaposition and adapted to permit removal and replacement of said anode and said cathode without altering their predetermined juxtaposition and yet capable of adjustment to vvary the distance between said anode and said cathode when desired, said supporting means including a plurality of bars which are adapted to tightly fit the apertures in the cathode insulating means and adapted to loosely fit the apertures in the anode insulating means, stop means on said bars adjacent said anode incombination: an anode: provided with; a; sub:-. stantiallw accurateadioptically. curved. surface of? concave; form and: having; a; support. substan;-. tially centrally disposed: on. the. back; portion thereof; a cathode having: a spider-support; on theiback thereof and provided: with azsubstantial lyaccurate dioptically' curved; surface; of: cone. vex. form; insulating means: adaptedi to: receive; the: supportzof isaidtzanode, in fixed? positional relationtherewith, said insulating means, being-pro1-- videdi withea: plurality of: apertures; insulatin means adapted? to; receive the support: of said cathode in; fixed: positional. relation; therewith, said: insulating, means being' provided: with. a;

; plurality. of. apertures; means for rigidly: sup,

portingeach' ofi'said insulating meanszin" aspaceda. predetermined juxtaposition anda'dapted 'tozpers mit. removal 1. and? replacement of saidianode: and saidi cathode; without altering their predeter mined. juxtaposition: andtyet' capable of, adjust mentftovary tiiezdistancebetween said-anodeiand saichcathodezwherrdesired; saidfsupportingmeanss including a. plurality of' bars which, are adapted? to, tightly fit the aperturess. in the:cathode-:-insu,-'-v lating means and adaptedto loosely fitthewaper turesinthe anodezinsulati-ng means", stop means: on said bars: adjacent; said:- anode; insulting; meanse and: wedgingimeans cooperating. with-said: stop. means. to: tightly presss. said: anodeinsulateing means against said stop means.

4. A plating rack of the type described which comprises, in combination: an electrode having a support substantially centrally disposed on the back portion thereof adapted to receive a positive charge; insulating means adapted removably to mount said electrode in fixed position by means of said support; an electrode having a spider support on the back thereof adapted to receive a negative charge; insulating means adapted removably to mount said electrode in fixed position by means of said spider support; each of said insulating means being provided with a plurality of apertures; means for rigidly supporting each of said insulating means in spaced predetermined juxtaposition adapted to permit removal and replacement of each of said electrodes without altering their predetermined juxtaposition, and yet. capable of adjustment to vary the distance between said electrodes when desired, said supporting means including a plurality of bars which are adapted to tightly fit the apertures in one of said insulating means and adapted to loosely fit the apertures in the other insulating means, stop means on said bars adjacent sulating means, and wedging means cooperating the insulating means which is loosely positioned on said bars, and wedging means cooperating with said stop means to tightly press the insulating means which loosely fits on said bars against said stop means.

5. In a plating rack of the type described, in combination: an anode; a cathode; insulating means adapted to support said anode in fixed positional relation therewith, said insulatin means being provided with a plurality of apertures; insulating means adapted to support said cathode in fixed positional relation therewith, said insulating means being provided with a plurality of apertures; spacing means separating said insulating means and rigidly positioning them with respect to each other, means for rigidly supporting each of said insulating means in a spaced predetermined juxtaposition and adapted to permit removal and replacement of said anode and said cathode without altering their predetermined juxtaposition, and yet capable of adjusts and said cathode when desired, said supporting means including a plurality of bars, said bars having threaded portions adjacent one end and a shoulder adjacent the other end, said bars being adapted to tightly fit the apertures in .the-

first mentioned insulating means and being fur-- inner surface of said first mentioned insulating means, and wedging means being adapted to tightly press said first mentioned insulating means against said shoulder means, whereby said first mentioned insulating means and said anode supported thereon are fixedly positioned on said supporting means. i

6. In a plating rack of the type'described, in combination: an anode; a cathode; insulating means adapted to support said anode in fixed positional relation therewith, said insulating means being provided with a plurality of apertures; insulating means adapted to support said cathode in fixed positional relation therewith, said insulating means being D OVided with a plurality of apertures; means for rigidly supporting each of said insulating means in a spaced predetermined juxtaposition and adapted to permit removal and replacement of said anode and ment to vary the distance between said anode said cathode without altering their predetermined juxtaposition, and yet capable of adjustment to vary the distance between said anode and said cathode when desired, said supporting means including a plurality of bars, said bars being adapted to tightly fit the apertures in the first mentioned insulating means and being further adapted to loosely fit the apertures in the second mentioned insulating means, a shoulder on each f said bars adapted to firmly bear against the inner surface of said first mentioned insulating means, wedging means adapted to slide on said bars for tightly pressing therfirst mentioned insulating means against said shoulders, whereby said first mentioned insulating means and anode supported thereon are fixedly positioned on said bars, locking means movably mounted on said bars and adapted to firmly bear gainst the inner surface of the second mentioned insulating means, and means threadedly engaging said bars for firmly bearing against the outer surface of the second mentioned insulating means, whereby said second mentioned insulating means may be positioned and firmly held in such position.

A. KENNETH GRAHAM.

CHARLES V. SMITH.

FRANK P. WILLIAMS.

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