US 2675348 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
April 13, 1954 GREENSPAN APPARATUS PoR METAL PLATIN@ 3 Sheets-Sheet l Filed Sept. 16, 1950 April 13, 1954 GREENSPAN 2,575,348
APPARATUS FOR METAL PLATING Filed Sept. 16, 1950 3 Sheets-Sheet 2 ATTORNEY April 13, 1954 L.. GREENSPAN APPARATUS FOR .METAL PLATING 5 Sheets-Sheet 5 Filed Sept. 16, 1950 FIGB FIG.6
span HT'TORNEY Patented Apr. 13, M1954 UNITED STATES PATENT oEFlcE APPARATUS Foa METAL PLATTNG Lawrence Greenspan, Bronx, N. Y; Y
Application `September 16, 1950, Serial No. 185,205
This invention relates to improved devices for rapidly and uniformly plating objects, and novel methods of plating the objects. More particularly the invention relates to devices for electroforming stampers or dies used in the manufacture of phonograph records and electrical transcriptions and methods of making said stampers or dies.
It is the general object of the present invention to provide novel and improved devices and methods for producing stampers rapidly and with a minimum variation in thickness of the electroformed shell or stamper from the center to the periphery.
Another object of this invention `is toprovide in a plating apparatus of the character described, baie means to direct plating current inwardly of the periphery of the cathode surface being plated, in order to prevent an excessive build-up of electrodeposited metal at the periphery and thereby produce a plating of substantially uniform thickness.
A further important objectof this invention is to provide in plating apparatus of the character to be described, means to direct a stream of gas bubbles through the plating solution and adjacent the cathode surface being plated, in order to produce vigorous agitation of the plating solution and thereby permit the use of high current densities to obtain rapid plating.
:Still another object of this invention is to provide in a plating apparatus of the character to be described, baiiie'means to direct the plating current uniformly over a metallized cathode surface, and means to vigorously agitato' the plating solution by passing a flow of air bubbles through the plating solution and adjacent the surface being plated, whereby high current densities may be employed to decrease the plating time.
Another object of this invention isto provide a device for electroforming stampers comprising a backplate made of electrically insulating ma- 'terial chemically inert to the electrolyte, a cathode holder attached at one end'to the back o f said backplate, said cathode holder having its other end adapted to electrically Contact a negative bus bar, and means at the attached end to make electrical contact through said back-` jacent to the surface of the object 'to be plated during the plating process in order to produce vigorous agitation of the electrolyte over the Whole exposed face of said object and sheet, whereby a high current density may be used to obtain rapid plating.
A further object of this invention is to provide in a device of the character to be described, in clined baffle plates forwardly and inwardly and` scribed, a metal sheet Vinterposed between a chemically and electrically inert backplate and the object to be plated, said sheet extending beu yond the edges of said object whereby the plating current is caused to distribute itself uniformly over the object to be plated, and to elecn trodeposit a shell of substantially uniform thickness without the formation of nodules, trees and roughness which in prior methods had a tendency to form around the periphery of the object being plated.
Still another object of this invention is to provide a device for electroforming stampers comprising a backplate made of electrically insulating material, chemically inert to the electrolyte, a cathode holder attached at one end to the back of said backplate, said cathode holder having its other end adapted to electrically contact a negative bus bar, and means at the attached end to hold and make electrical contact through said backplate with a metallized cathode surface of a record to be plated, means attached to said backplate to provide a stream of air bubbles through the plating solution and adjacent the surface of the record to be plated, and a balespaced from said backplate and parallel thereto, and in front of the record `surface `being plated, said baffle being formed with a hole of smaller diameter than the diameter of the record being plated, whereby the electrodeposited metal is caused to distribute itself uniformly on the metallized cathode surface, and permit appreciabie saving in copper.
Yet another object of this invention is to provide an economical method of manufacture of stampers in which a minimum of equipment,
space and labor lis required. I
Other objects of this invention will in part be obvious and in part hereinafter pointed out.
The invention accordingly consists in the features of construction, combination of elements, arrangement of parts, and method steps which will be exemplified in the construction hereinafter described, and of which the scope of invention will be indicated in the following claims.
In the accompanying drawings in which are shown illustrative. embodiments of this invention,
Fig. 1 is a front elevation vieW of a preferred embodiment of the invention;
Fig. 2 is a cross-sectional view taken along the line 2-2 of Fig. l; j
Fig. 3 is a top plan view of the embodiment shown in Fig. 1;
4 sarir to turn the shells down to a uniform thickness on a lathe, an excessive number of cuts are required toV make the stamper of uniform thickness and this makes the process expensive'both from the standpoint of labor and loss due to copper scrap. Furthermore, there is a tendency for the outer edges to be cold worked excessively in the cutting operation on the lathe, resulting in a hardening and embrittling action on the outer surfaces and causing distortion and even cracking of the stamper when removed from the cutting lathe.
' present invention for producing stampers overcome vallucf .these disadvantages.
Referring now to the drawings, particularly Figs.v l', ZandS, for a more complete understand- Fig. 4 is a top plan viewofltwor-unitSrQi the'.
embodiment shown in Fig. 1, in a plating tank;
Fig. 5 is a cross-sectional view taken along the line 5 5 of Fig. 4;,
Fig. Gris-a view similar to Fig.' 1 showing another embodiment of the invention;
Fig. '7` isav top` plan view-'of the embodiment shown in Fig. 6;. l
Fig. 8 is a crossesectional View taken along line 8-8 of Fig. 6; v
Fig. 9 is an enlarged.cross-sectional view of a portion ofa phonograph-record whose surface has been metallized; l
Fig. 10- is Aa view similar to tion of the electroormed stamper deposited on the metallized surfaceand y Fig. 11 is--an-enl'arged cross-sectional view of a portion of they electroformedstamper deposited on the metallized surface of the record and -removed from the record.
In themanufacture ofphonograph records electricaltranscriptions there has been a great needv for producing an electro-formed shell or stamper which has a smooth'- surface without treesor nodules, is hard and` springy- `without being brittle, and has-a well controlled and constant thickness from the periphery tothe center. Also, itV is desirable to produce these stampers as rapidi-vas possible. l y
In the usual `methode-ofA producing electroformed'shells or stampers, the original recording disc which is made` of' Waxor aluminum' coated with a lm of cellulose acetate, on which lthe recording grooves are cut,- is first; metallized to i make the surface' electrically conductive. The conventional methods used are' either to rappl-y a gold nlm-by sputtering or to form a silver mirror by spraying or immersion tank methods. This filmer mirror isnext strengthened byV applying a preplate at low current density to buiid upa shell having a thickness of approximately 0.0005.V to 0.001". The recordV disc is then plated at a higher current vdensity tobuild up athiokness of approximatelyV 0.050V of metal, usually copper. Obviously, it is desirableA to produce these stamp-. ers as rapidlyV as `possible and with aminimum outlay of equipment and space. Most of the methods in common use take vfrom 16- -to 48 hours to electroformthe shell or stamper. Faster plating methods have been devised by rotating, the cathode, providing-a systeml of baffles and. circulating the plating solution. These methodsA are comparatively expensivefrom the. standpoint of initial equipment cost, excessive space and maintenance required. Also, in most of the methods in common use` the. electroformed shellsV show` a variation in thickness ofcopper, or other metal, of as much as- 0.050" from the center to thev outside edge. In view of.' theV factk that itis neces- Fig. 9 showinga pori and me of the invention.. i0 designates the plating device embodying the invention for electroform- 'ing' stampe'rs or dies used in the manufacture of phonograph records and electrical transcriptions. The plating devicel lil. comprises a rectangular support or backplate il which may be made of a plate of chemically and electrically resistant material such as Bakelite niicarta, or similar non-conducto-rof electricity. Said backplate il comprises a frontV wall I2, a rear wall I3, a top edge. I4 and a bottom edge l5. Backplate Il, is further formed with substantially 45 beveled edges l5 extending forwardly and. inwardly fromV the rear wall i3 to the front Wall i2. At substantially the. center of backplate i l is a shallow discshaped recess il in WallV i2. Extending rearwardly from recess ll is a smaller disc-shaped recess i8, concentric with recess i7.. Extending rearwardly from recess [Si is aA round hole Isav communicating with the rear wall i3 of backplate ll for the purpose hereinafter described.
To help prevent an excessive build-up of depositedmetal around the periphery of the stamper to be formed and to prevent; treeing of deposited metal along the edges of the aluminum sheet to be described, there is attached toeach beveled edge l0 of backplate I l, by any suitable means such as, screws i9, a rectangular sheet or baille 23.. The baliies 20 aremade of the same composition as .baokplate Il are coextensive with edges- IE andextend forwardly and inwardly of said backplate VI l.
`Flush withthe lower edge l5 and on theV front wall i2 of backplate H is a rectangular spacer bar 2l of rectangular cross-section and of chemically and electrically inert material similar Vto said backplate l l. Said spacer bar 2l is attached to backplate ll by means of screws 23 or any other `suitable means. The triangular shaped holes 2 la formed between the ends of the spacer bar and cailles 20 are for the purpose of permitting drainage-of electrolyte When device iii is removed from the platingy bath.
In order to permit faster plating of the record by use of high. current densities with this invention, strong agitation of the plating solution is provided byv a steady; stream of air bubbles through the solution and over the surface of the record to-be plated. To this end, there is provideda member 2li.; Member 2S. may be made of the same composition as backplate i! and comprises a rear wall 25 contacting the front wall of spacer bar 2i and extending beyond the side edges thereof, a lower horizontal edge Z ilush with the lower llorizontal edge of spacer bar 2l, a front wall 21 parallely to rear wall 25, and an upper Wall 28 sloping downwardly and rearwardly at an' angle of substantially 45 from front' Wall Z'itoireargwall 2,5.l Walls 28. and 25 The devices and methods of theV meet in a straight line which is substantially at the level of the upper horizontal edge of spacer bar 2I, or slightly above this level. Member 24 may be secured to spacer bar 2I by the screws 23 or any other suitable means. The side edges 29 of member 24 are beveled in the same manner as side edges I6 of backplate II, and form plane surfaces therewith which contact the inner surfaces of baiiies 20 and terminate short of the forward edges of said baffles 2li. Member 24 is further formed with a plurality of vertical through openings 30 parallel to front wall 21 and communicating with the upper wall 28 and the lower edge 26.
Satisfactory results have been obtained in plating large record surfaces when the through openings 30 were ile in diameter and spaced about from each other.
In contact with the lower horizontal edge 26 of member 24, is the upper surface of a rectangular bar 3|, of rectangular cross-section and of the saine thickness and composition as member 24. Bar 3I which protrudes slightly from both sides 29 of member 24 is secured to member 24 by screws 32 or any other suitable means. Bar 3| is further formed in its upper surface with a vertical groove 33, which communicates with the through openings 36 of member 24, and which terminates short of the ends of said bar 3I. A round through passage 34 communicates with groove 33 and one end surface of bar 3l. Inserted into the through passage 34 and extending beyond the end surface of bar 2I is a chemically and electrically inert tube 35 for the purpose hereinafter described.
Electrical contact must be made between the negative terminal of a source of direct current, and the cathode or surface to be plated. To this end there is provided a heavy contact holder 36. Contact holder 36 comprises a bar of metal, preferably copper, of rectangular cross-section, having a vertical portion 31 extending upwardly along rear wall I3 from a point just below the center of backplate II to a point above the upper edge I4 of backplate II. Extending from the upper end of vertical portion 31 and making an angle of about 135 therewith is a smaller rearwardly and upwardly inclined portion 38. Portion 38 is formed with a through opening 39 at its center for the purpose to be hereinafter described. Extending from the upper end of portion 38 in a downwardly and rearwardly direction, making an angle of 90 therewith is a portion 40. It will now be seen that portions 3S and 40 form a hook-like structure adapted to engage a cathode bar of square cross-section for an electrical connection. Vertical portion 31 is further formed with a round hole 4I spaced from its lower extremity, and in register with hole I8a in backplate II.
By means of wing nut 61 the whole assembly is held rigid so that the vertical stream of air bubbles rises parallel to the surface of the record, agitating the solution in contact therewith but not actually making contact with the record surface.
To connect contact holder 36 with the record surface to be plated there is provided a rod 42, externally threaded at both ends, snugly inserted into holes 4I and I8a. The forward flat end of rod 42 is flush with front wall I2 of backplate` I I. The rear flat end of rod 42 projects beyond vertical portion 31 of contact holder 36 and is se. Cured thereto by-nut 4,3 in threaded engagement with rod 42. An internally threaded disc-like metal insert 44, having a iiat front surface flush with front wall I2 of backplate I I and adapted to snugly t into recesses I1 and I8 of backplate I I, is threadedly engaged with the front external threads of rod 42. Rod 42 is further formed with an axially threaded opening 45 in its front end to receive a headed screw 46 for the purpose hereinafter described.
To prevent the formation of nodules, trees and roughness around the edges of the record to be plated, particularly when high current densities are used, there is provided a rectangular metallic sheet 41, preferably of aluminum, which lies at against front wall I2 of backplate I I, and in contact with the front flat surface of insert 44. Aluminum sheets of between .005" to 11s have been found to produce satisfactory results. The bottom edge of sheet 41 rests on the upper edge of the spacer bar 2| and covers substantially the entire front Avvall I2 of backplate II, terminating just short of the sides and top thereof. Sheet 41 is formed with an opening 48 at its center to register with opening 45 in rod 42 and through which screw 46 passes. A metal washer 49 may be placed against the head of screw 46. The record 5t to be plated is interposed between the washer 43 and sheet 41 with the screw 46 passing through the hole 5I in the record 56. The icord surface to be plated is the front surface All of the metal parts through which the plating current will flow are preferably made of copper, with the exception of sheet 41 which may be of aluminum, to provide a good conductor for the electric current. All the metal parts, with the exceptions of the surface to be plated and sheet 41 which come in contact with the plating solution or electrolyte in the plating tank should be painted or coated with a chemically and electrically inert material in order to prevent chemi cal and electrical reactions with the electrolyte.
It will now be understood that an electrical connection is made between the metallized cathode surface 52 of record 50 and contact bar 36 through washer 49, screw 46, sheet 41, insert 44, rod 42, nut 43 and vertical portion 31 of contact bar 36. Portions of the cellulose acetate film on record 5i?, near the center hole 5I may be scraped away to expose a metal base to insure a good electrical contact between washer 49 and sheet 41 when screw 46 is tightened.
For a better understanding of the plating process, reference is made particularly to Figs. 4 and 5 in which 53 designates a plating tank or container. Tank 53 is filled to capacity with the usual plating solution or electrolyte 54 which may be a solution of copper sulphate and sulfuric acid if, for instance, the stamper is to be made of copper. While stampers may be made of other metals, as for example nickel, the process of making copper stampers by this invention will be described for purposes of illustration. Two plating devices IE) are shown within tank 53 to illustrate the compactness and simplicity possible in this method of plating.
The anodes 62 may be placed as closely to the cathode surface as is practicable which by virtue of the construction is about 2". There are several advantages accruing to this close spacing. One important advantage is the low solution IR drop with its resultant saving in electrical power. .Another advantage is to be seen in the eifect of the air stream in agitating the solution in proximity to the anode surface thus reducing anode 7. polarization andA any tendency toward sludge-forillatifh TanlcSS comprises asubstantially square bottom: wall 55, parallel side walls 55, a iront-.iwan lV and a rear wall 5t. Extending outwardly from the upper liorizc'ntalledees of side walls 58; front wall 51 and rearwall B'lis `a squarenorizom tal flange 59. Resting on electrioallinsulatn blocks 59a on. flange :itV andparallel to side walls 5S are two metal anode bars 6c each. equally spaced from 'side wallV 5c' or tank 53. Anous barsA till-` may be: offromdf or square cross-'section and are preferably madeloiccpper. touact asr socal conductors of electricity'. `suspencllecl from each anodebar 60 by means of hooks 61| aretwo ieee tangular copper bars 62 which are the sources of metal-used'oif plating' thestalil'pr'. .Ailde bls 60 arel'ctlicall-y connected ta Gommoni al'l terminal 633s' at 64'f0`1 the' ulD'oSevof Slliaplyillg source of direct current 'to the plating solution 54j.
Midway between. anode bars Eil andi parallel thereto are two adjacent cathode bars E5 which act assupportsfor the plating! devices E9. Cathode bars r55 maybe of square cross-section so that they may rest on their edgesl on flange 59| Extending upwardly and outwardly from each cathode barde at its midpoint is a threaded shank 66. Platingrdev'lce- Hi! is hung on cathode bar E5 so that shanki` protrudes through open* ing 39 of cathode holder 35. Wing nut iii is thenv screwedvcn shankt to make good electrical contact between the cathode holder 35 and the cathode bar 85. Cathode bars 65 are connected to a common cathoderterminal SS as at GQ for 'connection toj the negative terminal of a direct currentsupply.
A chemically inert flexible rubber tube ill is connected to tube 35 in member 3i for the purposeV of supplying air under pressure from an air compressor blower' through groove $3, openings te and over'the metallized cathode surface 52 of theA record 5o during the plating process.
To make a copperstamper of the metallized VcathodeV surface vili of the record tii, a sourceV of direct current is' applied across anode terminal E3- and cathode terminal 681. A copper pre-spiate atv alow current density oi' about 25 amps/su. it. is formed on the metallizcd cathode surface until the thickness of the copper plate is oi approximately 039005" to 0.001. noted that during the entire plating process copper will also be deposited on the aluminum sheet 4f? which-.extends beyond the periphery of record 59, and which is electrically connected to the negative source of direct current.
Air under pressure is next introduced through tube 752 and flows through passage 34, groove 33, openings Sil and over the metallized surface 52 being plated. The air uniformly,T agita/tes the plating solution along the whole plating surface. By varying the air pressure in tube 'lll any degree of agitation of .the plating solution, from mildto extremely violent, may be produced. By using strong agitation comparatively high current densities can be used and thus permit rapid elec-'- trodeposition to take place. Because of this uniform agitation overthe face of the nletallized cathode surface YE52 the metal electrodeposited is srhooth, uniform and of excellent physical characteristics for record stampers.
The aluminum sheet lll' serves the functionv of preventing excessive` current density around the periphery of record 50. This is accomplished by extending the metalliz'ed cathode surface 52 on to plate 4l andV causing thecopper to plate onto Itl will be bothfaluininum sheet IH and metallized cathode surface 52. The het euect come assembly of the plating device iii is to provide. very uniform current distribution over the whole metallised cathode surface 521er the record 50 with.there suit-.that the thickness'- oi 'the electro'ionned shell Ol* .stall f'h'l the' c'iltel" to. the plphlfy vis suistltialiy' 'llllffilL dlth'drmre', the' tllde ency for nodules trees and roughness to'` occur over the surface beingplated andparticularly amandine periphery of the record sil, prac tically eliminated. Thisy smoothness and uni.- oimity isv a decided advantage sincaas pre-vlously pointed out, a single trimming out a lathe of a' fewthousandths is all that is required to produce a satisfactory iinished stariiper ready forv use. .in electroforming the Vcoincer shell or stamper current densities asf highas 2G() ampsl/ sql. ft. 'may be employed with an -air pressure of about 3 lbsuntil a stamper shell of 0.050 is formed. Exceilent results have been achieved ln building up the requisite thickness of a stamper in from 6to l() hoursoy this method.
The barde-s 2li and inclined wall 28 of mem--i ber" 2d of plating device Il] serve the function of preventing the current from concentrating' along the edges of the nietalli'zed cathode surface 52 and the edges of sheet 41 thus eliminating any tendency toward the formation of treesl and nodules which, as is well known inthe art, are wasteful of metal and electrical energy, partieularly when heavy electroplates are built up'.
In Figs. 6, 7 and 8 is shown ar'lotherv embodiment of a plating device" lill similar to thel platf ing device if! shown in Figs'. l, 2 and 3', except for the arrangement of the baffles and the' elimination of theV metal sheet 571' behind the metal-e lined cathode surface 5'2 of the record 5G to be plated. v'il'ie plating device Hf] comprises a rec*- tangular p1ismaticsha`ped support or backplate iii of the samey plate material as backpla'te il'. Said back-platelll further comprises a front wall H2, a' rear Wall H3; a top edge IM, a bote tom edge H5 and side edges Ht; At substantially the center oi backplate iii are the same concentric disceshaped recesses il' and lii'ancl hole ma, as are formed in nackplate A system of baffles is attached to backplate for the purpose of directing theA electrodeposited metal uniformly o n the stamper to be'formcd and thereby prevent the formation of trees and nodules which usually form around the periphery of the stamper. To this 'end there are provided a pair of rectangular spacer plates H9, par'- allel to each other, and each adjacent and coextensive with side edges H6 of backplate lll'. Plates H9 are of the same material as backplate ill, are perpendicular to front wall H2 o1" said backplate Hl and attached thereto by any suitable means. Attached to the front edges of plates H9 by any suitable means is a rectangular Vbaille 20 parallel .to baclzplateA Ill, of the same chemically` and electrically inert material, and coextensve therewith. Balile |26 is formed with a large round hole 12M concentric with disc'- shaped recesses Ii and i3, and hole 18a. Hole Ia is of slightly smaller diameter than the metallized cathode surface 52 of the record to be plated'. f
Flush with the Ylower edgev IIE and on the front wall ||2 of packplate |.|'1f is a rectaneailar` spacer bar |21. Spacer bar |2| isv attached to backplatc by meansof screws |23 or any other suitable means. Tneparallelside edges of'spacer par :2| terminate shortfof the innersurfaces' of 9, plates I l 9 thereby forming a rectangular `through opening |2|a for the purpose of permitting drainage of electrolyte when device |111 is 4removed from theplating bath. Spacer bar |2.| is made of the 'same material `as backpla-te To provide strong agitation of the plating solution by supplying a steady stream of air bubbles through the plating solution and adjacent the cathode surface to be plated, there is provided a prismatic-shaped member |24 similar in function to member 24 of plating device .10. Member |24 is made of the same materialas backplate and comprises a rear wall |25 contacting the front wall of spacer bar |2| and extending beyond the side edges thereof, a lower horizontal wall 25 flush with the lower horizontal edge of spacer bar |2|, a front wall |21 parallel to rear wall |25,
vand an upper wall |28 parallel to lower wall |26 and flush with the upper horizontal edge of spacer bar |21. The parallel side edges of member |24 contact the inner surfaces of plates H9. Member |22 is further formed with a plurality of vertical through openings |30 parallel to front wall |21 and communicating with upper walll|28 and lower wall |25, similar to openings 3in `member 24 of plating device lil. Member |24 may be secured to spacer bar |2| by screws |23 or any othe suitable means.
In contact with and suitably attached to fthe lower horizontal wall |26 of member |24 and the lower edges of plates I9 is the upper surface-of a rectangular prismatic bar `3|. Bar 3| has the same construction and function in relation to member IZLlof plating device Il@ as it has in relation to member 24 of plating device I0. Interposed between and suitably attached to baille |2 and the upper portion of front wall I 21 is a spacer bar |3|.
It will now be understood that 'a continuous stream of air under pressure from an air compressor can be introduced through tube 35, pas-v lsage 34, groove 33, openings |39 and over the metallized cathode surface 52 of record 59 during the plating process. i
In plating device the rear surface of record U is placed flush against front wall H2 ofbackplate Il and secured thereto in the same manner as record 5t is secured to plating device EL It will be noted, however, that in plating device IIB there is no metal plate interposed between the back of the record 50 and the front wall ||2 of the backplatelii. l
It will now be understood that an electrical connection is made between the metallized cathode surface of record 5!) and contact bar 36 through washer 49, screw 5.6, insert 44, rod 42 and nut 43.
Plating device lli! can now be suspended into tank 53 in the same manner as plating device l0 and metallized cathode surface 52 of record 5i) can now be plated to electroform a stamper as previously described. It will be noted however that in plating device Ill the entire cathode surface plated is the metallized cathode surface 52 of record 55. In plating device l, the entire cathode surface plated is the metallized cathode surface 52 of record 5B and the .portions of metal sheet 31 that extend beyond .the periphery of record. 55.
Baiie |23@ functions to prevent an excess of metal from depositing around the periphery of the stamper. This is accomplished by diverting the metal ions in the plating solutionfrom the periphery of the record because in travelling from the anode bars 52 to the metallized cathode surface "52, said ions must pass through hole |2|la which has asmaller diameter thansaid metallized cathode surface.
Referringnow particularly to Figs. 9, 10 and 11, therecordor electrical transcription to be plated is` represented by numeral 50. Record 50 comprises a metal base 5|a, usually of aluminum, a bottom side 5 lb, usually of a plastic material such ascellulose acetate, and a top side 5to also of a similar plastic material. Sound recordings are cut into the top side 5|c, for instance, by a recording machine well known in the art. These recordings are in the form of grooves 5|d. In order to make a stamper of these grooves 5|d the entire surface 5| c is metallized by a very thin coating of metal, usually in the form of a silver mirror or metallized cathode surface 52.
In the plating process the stamper 52a usually of copper,` is deposited on the metallized cathode surface 52. When stamper 52a is of the required thickness it is pried loose from the record surface 5Ic. Stamper 52a, with the thin metallized surface 52 adhered to itnow contains an impression of the sound recording made on the record and is capable of functioning as a die to stamp out similar recordings. By using the above plating devices and methods a stamper of substantially uniform thickness, an excellent stamping characteristic, is produced.
If desired a metallic sheet like sheet 41 may be employed in the apparatus shown in Figures 6, 7 and 8, interposed between the record 50 and the front wall 2 of backplate While the above specication has described the invention with relation to a metallized matrix surface of a plastic or non-metallic record or matrix, it is understood that the inventive method may be applied to a metal matrix surface also.
It will thus be seen that there are provided devices and processes in which the several ob jects of this invention are achieved and which are well adapted to meet the conditions of practical use. l Y
As various possible embodiments might be made of the above invention, and as various changes might be made in the above embodiment set forth, it is understood that all matter herein set forth or shownV in the accompanying drawings is to be interpretedv as illustrative and not in a limiting sense.
l. A device for plating the front metallized surface of a'phonograph record comprising a backplate, a cathode holder attached to the back of said backplate, said cathode holder having means on one end to electrically contact a negative bus bar of a source of direct current, and means at the other end to make electrical contact through said backplate with said metallized .surface of said` phonograph record, means in the front of said backplate to hold the rear surface of said phonograph 'record in contact with the front surface of said backplate, and means near the bote tom of. said backplate to direct a stream of air bubbles adjacent to said metallized surface, and a baliie supported by 'said holder and disposed in front of and spaced from said record and having aholeopposed to said record, saidbackplate and haliiebeing made of electrical insulating material resistantto plating solution.
2. A device for plating the front metallized surface of a phonograph record comprising a backplate, a cathode holder attached to the back of said backplate, said cathode holder having means on one end to electrically contact a negative bus bar of a source of direct current, and means at scrapes 111 the other end to vmake'electrical contactthrough said backplate with said metallized surface of said phonograph record, means in the front of said backplate to hold .the rear'surface'of said phonograph record lin contact with the front surface of vsaid backplate, means near-the bottom of said backplate to direct a stream of air bubbles adjacent to said metallized surface, said last means comprising a member `attached tothe bach'-Y plate and having a plurality of vertical through openings parallel to each other, anda bar attached to .the underside of said member, formed with a longitudinal groove in its upper surface and communicating with said through openings and with a through ,passage at one Vend of .said bar to receive air from an air compressor, a bale attached to said member and disposedin front of and spaced from said backplate and having an opening opposed to said record, sa'idfbackplate member, bar and baille being made of electrical insulatingr material :resistant Vto platingsolutions.
3. A device Afor plating 'the frontfmetallized'surface oi a lphonograph record comprising :a hackplate, a cathode holder attached "to the back of said backplate, isaid cathode holder Ehaving means on one end to electrically contact a'negative'bus bar-of a source of direct current, and ,means .aat the other end to make electrical vContact through said backplate with said :metallized surface of said phonograph record, means in the vfront Yof said backplate to hold the Vrear surface of said phonograph record ineen-tact with the front surface of said backplate, means near the Ebcl'oln of said backplate to direct a Vstream 'of air bubbles adjacent to said metallized surface, and ay baille attached to said backplate and located in frontof and spaced from `said metallized surface. said baile being formed with a circular holeof smaller diameter than the diameter of saidimetallized surface, said backplate and baille being madeof electric insulating materialresistant to plating solution.
4. A plating device for electroformingstampers forphonograph records comprising a backplatefa cathode holder attachedto the back of said-backplate, said `cathode holder having means "on'one end to make velectrical conta-ct with a negative'bus bar, and means .onthe other end to .malte-zelectri cal contact through said backplate with a metalliaed cathode surface of phonograph record, means in "thefront of said back-plate to hold said phonograph record against said backplatefandla baie attached to `said front of said backplate, said baille being spaced from said backplate `and metallized `cathode surface, and formed with 4a circular hole having a smaller diameter than said metall-ized cathode surface of said phonograph record andl concentric therewith, whereby lthe plating current is prevented from concentrating around the periphery and the forma-tionlof noda ules, trees and roughness prevented around the periphery of said .metallized-cath'ode surface, said backplate and baffle A'being :m'ad'efof electric inV sulating material resistant to plating solutions. and means to supply airunderjpressure :between the metallized surface and baille.
5. A vdevice for plating the front metall-izedsur face lof a phonographic record in a plating tank provided with a negative bus bar 'of a vsource of I2 directlcurre'nt, saiddevioe comprising aunit which may be .-'hungon the @bus bar to project down into plating vsolution in thev tank, said unit comprising a cathodeholder having means at its upperend for removable attachment to said negative bus bar, means on sai-dholder to support a phonograph 4vrecord having a front metallized surface and to-make electrical contact with the metallized surface of said phonograph record, a bale plate of electric resistant material supported by said holder bar in spaced relation in front of the phonograph record, said Vbaille being formed with an'openingin opposed relation to the record, and means supported by said holder to direct spaced streamsof .air bubbles adjacent said metallized surface and .between the record and baile, said unit being removable as a whole from the bus bar.
6. 'The device of claim 5 in combination with a backing `plate of electrical resisting material, supported on the holder and against which the back of the recordcontacts.
7. A `portable unitary device -for plating the front `rr'i'et'al-lized surface of a phonograph record, comprising a cathode .holder having a hook at its upper end `from which it may be hung on the nega'tive busibar `of a plating tank, a record having a front Ymetallized surface, means on the holder bar toysupport said record on a horizontal axis and ltomake electrical contact with the front metallized surface .of said record, a bale of electrical Tesistantmaterial supported by said holder bar and disposed in front of the record in spaced relation thereto-and -being formed with an opening substantially coextensi-ve with the metallized surface of .said record whereby current in the plating tankis directed 4through the opening to saidmetallizedfsurface, means supported by said holder bar and located between the lower end of the baffle and the record to direct upwardly, streams'of nir bubbles to agitate the plating solution in the r'tank, said device 'being removable from the tank as. a unit by unhooking the holder bar from t-hebns bar.
8. The device of claim 'l' in combination with a. backing plate of electrical resistant `material contacting the back of the record and supported on said holder.
References cited in the me of uns patent :UNITED STATES PATENTS OTHER V'REFERENCES A Principles of .Electroplating and ElectroforminggbyWilliam'Blum and George B. Hogaboom, 3rd edition, 1949, pages 270 and 271.