US2315272A - Electroplating apparatus - Google Patents

Description

March 30, 1943. K. T. POTTHOFF ELECTROPLATING APPARATUS Filed Oct. 8, 1938 2 Sheets-Sheet l March 1943- K. T. POTTHOFF ELECTROPLATING APPARATUS Filed Oct. 8, 1958 2 Sheets-Sheet 2 M111 ATTORNEY mated n... 30, v

UNITED STATES PATENT OFFICE ELECTBOPLATING APPARATUS Kurt T. l'otthofl, Brooklyn, N. Y.

Application October 8, 1938, Serial No. 233,922

15 Claims.

The present invention relates to rotary electroplating barrel and solution and the protection, by

insulation of certain other metallic bearing parts, which of necessity are also located in the solution, to protect them from wasteful and undesired plating during operation of the device.

Further objects of improvement are accomlished in the structure of the current conducting elements of the device, for making instantaneous contact of the barrel when replacing it back into the plating tank, after recharging the barrel with articles to be plated, after removing a plated charge.

The foregoing and other objects of advantage will be noted as the herein description proceeds and it will be obvious that modifications may be made in the structure herein without departing from the spirit hereof or the scope of the appended claims.

In the drawings:

Fig. 1 is a sectional view, in elevation, of the apparatus, taken on the line l-l, Fig. 2, looking in the direction of the arrows;

Fig. 2 is an end view of the apparatus as viewed from the right hand side of Fig. 1, said tions of a modified barrel end structure;

Fig. 8 is a fragmentary view of one barrel end, taken on the line 8-8, Fig. '1, looking in the direction of the arrows;

Fig. 9 is a view, in side elevation of one of the conductor heads, slightly modified;

Fig. 10 is a sectional view of a barrel head assembly slightly modified over the barrel heads shown in Fig. 3; and

Fig. 11 is a fragmentary plan view of the apparatus as viewed from the left hand side of Fig. 1, with the drum D and its parts removed from the tank I, partially sectioned.

As shown in Fig. l, the apparatus comprises an outer metallic tank I, having a flanged all round, upper edge 3, the underside thereof, the top of the flange and the inner face of the tank may be coated with an insulating, acid proof, dielectric coating 2, in some instances of use.

On two opposit ends of the tank and upon the insulated flange 3, is located opposed and split U-shaped contact terminals 4-4, these being affixed in position at about the mid center of the transverse dimensions of the tank by fastening bolts 5-5, Fig. 1.

One of the terminal members 4, Fig. l, is pro vided with a wire receiving terminal extension 6 .for connection to the minus Side of an electric circuit, the source of which is not shown, but is understood.

A copper buss bar 8, of preferably rectangular section is removably mounted in electrical contact in said split terminals 4-4, said bar being provided with a bolted on bracket piece B, which is held to the bar by bolts b-b, and which is provided with an aperture c, whereby the hook of a hoisting means, not shown, may be introduced to lift the barrel or drum, generally denoted by D, to which the buss bar 8 is attached, from the tank I. As shown, the buss bar 8 and its attached plating barrel, rests in the split contacts 4-4, without fastening means, thus to be freely lifted in-or out of the tank.

The tank i has mounted therein, near its upper end, a U-shaped conductor bar 31, said bar being so mounted that the ends of the U are located above the plating solution level and so as to span, longitudinally, the drum or barrel D, on both of its sides, the connecting portion of the U being located exterior to the tank end, as shown in Figs. 1 and 2. The conductor 31 is provided at its connected end portion with a perforated terminal connection e, whereby the conductor 31 may be connected forplating, to the plus side of an electric current supply. This conductor is utilized to support a plurality of elongate anodes 38, which are suspended in the solution in the tank, by hooks 39. Only one of these anodes is shown in Fig. 1. In practice, the anodes are spaced along the two legs of conductor 31, and are spaced away from said drum on both sides thereof.

Thus, when plating, current flows from the conductor bar 31 and anodes 36, through the plating solution to the drum cathodes and connections, later to be described, and from thence through the buss bar 3 to the'source of current supply.

The manner in which the electrical connection is made from the drum interior will now be described. The drum D is made from a suitable dielectric material which is also acid or alkali proof, such as a phenolic condensation compound, known as Bakelite. It is made up in flat sheets 34 which are rabbeted into a side edge support in a plurality of dielectric staves 33-, as shown dotted in Fig. 2. One of these sheets or side panels 36, Fig. 2, is removably mounted to form a removable cover and is held in Operative closed position by a lock rod 36, shown dotted in Fig. 2. This latter arrangement ailords access to the interior of the drum for charging and discharging the articles being plated. The heads l'i-II of the drums are also of dielectric material and are held to the polygonal drum assembly by headed elongate bolts 43, which pass through the staves 33, Figs. 1 and 3.

One of the heads I'I, asin Fig. 1, is provided with a plurality of bushings 46 which are preferably dielectric, and which being mounted externally of the drum D, are used to support atoothed ring gear 45, which is held to said bushings 46 that impairs their efficiency and they must be replaced from time to time, and owing to the construction and mounting above noted, they are easily removed and replaced. The threaded bushings being easily removed and replaced by the use of a spanner or bar wrench, which may be engaged in the holes 3I and 3|, located in said bushings, as in Fig. 3.

The drum D in its complete assembly as in Fig. 1, has its shaft ends I6I6 -mounted in alined, conductive bearings I3--I3 which in turn are mounted to and suspended, either directly or indirectly from the buss bar 3 as will now be described.

As shown in Fig. 1, the right hand bearing I3 is electrically connected to buss bar 6 by a threaded metallic bolt 3, the head III of which is integral therewith, and underneath which head is a washer II. The bolt is encased or shielded by a dielectric tube I2, which may, as shown in Fig. 6, be an extension of the dielectric covering IQ of the bearing I3, in order to be liquid tight, thereby to shield the bolt 3 and the metallic parts and said head II by inset headed bolts, one of i which, 41, is shown dotted in Fig. 1.

The drum heads I I are each provided with a central, flanged, metallic stub shaft I6, the flange 23 of which is inset into the inside face of the heads IT, as in Fig. 3, and' held therein by screws 23, shown dotted. The shaft ends I 6 thus project from the exterior of the drum heads and act as conductor bearings for the drum.

As shown in Fig. 3, the shafts I6 have interiorly projecting threaded ends 2323,and upon each of these is mounted a metallic cathode disc E, which as shown in Figs. 4 and 5, is circular in form, has a central bore 21 to flt over the threaded stems 29 of the shafts I6; the disc having an indented central portion 26, connected by an outturned portion to an outstanding annulus 24, which is flanged on its perimeter, as at 26, in the direction of the indented center 26. The edge of the flange 23 extends slightly below the plane of the indented center 26 as will be noted in Fig. 5, shown dotted.

. The cathode plates E, as will be noted in Fig. 3,

are mounted upon the threaded stems 29, with the flanges 25 in contact with the inner faces of the heads I1, and as thus loosely mounted, the depressed central portions 26 are assembled in contact with the flanges 23. Then a bored dielectric disc 32 is mounted upon said stem, the

diameter of which disc 32 is such as to allow it to seat in the depressed central portions 26 of the cathode plates. Then a threaded, closed ended, dielectric bushing 30 is screwed upon each threaded stem 29, and the cathode discs E thus are forced into firm, tensional and electrical conalso keeping the plating fluid from contacting with the depressed portion 26.

During the plating process these cathodes be- This latter portion of the sheathing is counterbored at the bearing bore portion, and into this counterbore is fitted one end of a dielectric tube or bushing I8 which surrounds shaft I6, and fits the recess and shaft in a liquid proof manner.

Against the front face of the bearing I3 is fitted a dielectric washer 20, and in the space between the washer 23 and the barrel head I! is located a dielectric bushing 22, the end thereof nearest the washer 23 being tapered, thereby to form a mitred seat into which is fitted a stressed come coated with a metallic depositto an extent 2 resilient rubber ring g of preferably round cross section. When the assembly above is completed as above noted, the rubber ring 9 closes the gap between the washer 20 and the bushing 22 in a liquid tight manner and urges the washer 20 against the flat face of bearing I3, and urges the bushing 22 against the face of the barrel head II. In this shielding construction the metallic parts 3, I5 and I6 are shielded against current loss andundesirable corrosion and plating, while permitting of free rotation of the shafts IS in bearings I3-I3.

The bearing I3 shown at the left hand side of Fig. 1 is identical in construction with bearing I3 already described, but its mode of connection to the buss bar 6 is dissimilar, in that the bolt 43, with its integral head 44 is shorter than bolt 9, said bolt 43 being held by a bracket extension 4I, whichis integral with the gear supporting bearing 46, which in turn is aflixed to the buss bar 6 by fastening means 52-53.

Thus through this construction the buss bar is in electrical connection with cathode plate E on the left side of the structure, as viewed in Fig. 1.

When it is desired .to get at the bearings for any purpose, the rubber closing ring a may be moved back on the bushing 22, as shown dotted, at Fig. 6.

The gear support, being aflixed to the buss bar 6, moves with it when the barrel D is lifted from the tank I.

The gear support carries rotatable gears of suitable size such as gears and 54, these being mounted on shaft 55, Fig. 1. Gear 54 is in constant mesh with the ring gear 45 on head ll', while gear 5| is in removable mesh with drive pinion 56 on shaft 49, which is driven by a power means not shown.

As thus disclosed, when the barrel D is lifted the gears in housing 40 are also lifted therewith, the gear 5| being unmeshed from drive pinion 50. When the barrel is again entered into the tank I, the ends of the buss bar 8 are steered precisely back into operative position, gear 5| meshing readily with pinion 56.

As a means for guiding the barrel or drum D and its appurtenant apparatus into and out of the outer tank I one end of the tank is provided with an interiorly located guideway, generally denoted by 65. Figs. 1 and 11, the entire external surface of which is covered with a dielectric, acid and alkali proof coating 66.

As seen in Fig. 11, which is an enlarged plan view of the left hand upper portion of the tank I, with the flange 3 broken away, to better show the guideway in operative position, the guide 65 is attached to the coated face 2 of the tank wall I.

The guideway proper, indicated by 61, is a metal channel shaped member, and is entirely located within the dielectric coating 66. It comprises two downstanding support legs 6668, which are attached to the wall of the tank I, by two fastening screws 69'69', which are threadedly attached to said legs 68, through the tank wall and both coverings 2 and 66.

The open end of the guide channel is formed by a traversing rear wall 69, which joins the legs 68-68, and from which legs 68 and rear wall 6!! spring two open side guide portions -10. The upper, open ends of the guides 16-10 are inclined towards each other at a slight angle, and at its upper end the guideway has a wide. open, flaring entrant portion, formed by the upper ends AB. Fig. 11, the guide portions 10-10 gradually merging into flat parallel walls, which are open at the bottom forming a substantially parallel guide space 1|, thus from top to bottom the guideways form an open bell mouth construction, into which, when the drum D is being replaced into operative position in the tank, receives the lower end of the bearing l3, on the left side of the drum and guides said gear side of the drum to its operative axis in the tank, and, simultaneously guides the adjacent end of the buss bar 8 into its associated U-shaped contact- 4.

The circuit connections for electric plating are as follows; during rotation of the barrel D. with articles thereon to be plated, current flows on the plus side e, through the anode bar- 31, to the anode 38, from thence it passes through the plating solution, not shown, thence through the metal articles in the barrel through the 4 perforations X partially indicated in the barrel all metallic parts within the tank and below the solution level are protected against contact with the solution, except the exposed portions of the cathode plates, and are thus protected against corrosion and undesired plating, and such parts are accessible, when desired. The anodes 36, of course, are fully exposed to the electrolyte.

In Fig. 7, there is disclosed aview of a modified form of plating barrel structure, the view being somewhat similar to Fig. 3. The differences in this modified form lie in the utilization of a different form of cathode structure. The barrel structure shown in Fig. 7 is the same as described for Figs. 1, 2 and 3, and like parts in Fig. 7 bear like indexes, as described for Figs. 1, 2 and 3.

In detail, the conductive, flanged stub shaft comprises an outer extending short shaft l6, Fig. 9, having a integral central flange 23, and an inner integral threaded shaft end 29. The flange 23 is provided on its extending shaft face with a circular flange extension a, and the opposite face of flange 23 is provided witha narrower circular flange b, which is somewhat larger in diameter than circular flange a. The stub shaft of Fig. 9 is used in the structure shown in Fig. 7, on both head ends.

In Fig. 7, the heads II are each provided on their inner faces with a. two stepped recess 0 and d, into which are fitted the flange 23 and its circular flange a, thus leaving the faces 23' of the flange 23 flush with the inner faces II of the heads II. The flanges 23 are attached to the heads II, by countersunk head screws 26, Fig. 7.

On the outer ends of the shaft extensions |6 I 6 are mounted bushings |8|8, shown in Fig. 7 and also in Fig. 6. These outer extensions |6-|6 are each supported in bearings l3, exactly lik that shown in Fig. 6.

After the flanged stub shafts l6 are affixed to the barrel heads as shown in Fig. 7, the flush flanges 23' are each covered with a bored. non-conductive shielding disc 3232. the inner faces thereof being each provided with a rubber gasket 56, which are compressed into contact with the inner faces ll of the barrel heads II. In this position the discs 32 and gaskets 56 surround the threaded inner end of shaft l6 and the disc 23 with a fluid tight seal, and thus protect tihem from contact with the electrolytic plating uid.

0n the outer faces of each sealing disc 3232 is located a rubber gasket or washer 51-51, Fig. 7, which is compressed into contact with the sealing disc, by conductive, threaded, adjustable collars 58 and 58, which engage the threaded ends 29 of the stub shafts l6. The collars 58 have each affixed thereto a stepped, non-conductive'wrench head 60, which heads have spanner wrench holes 62 therein, Fig. 7, the wrench heads having extensions 6| thereon which fit into the unthreaded interiors of the bushings or collars 58, and to which said extensions 6| are each locked by a rivet 59. The bushings or collars 58 are removed and replaced from their operative, interior, engagement, as shown, by using a spanner wrench on the heads 60, access thereto being had through the access opening 35. Fig. 2, to the interior of the barrel or drum D. These collars 58, as will be seen, compress both gaskets 51 and 51 and the sealing disc 32 in firm operative and liquid tight engagement with the barrel heads I l.

, Before the assembly of the bushings or collars 56 on the threaded shaft ends 29, two dangle cathodes, 63 and 63, are mounted by their eye loops 64, on each of the bushings 58 and 58 and the bushings are then screwed tightlyagainst their respective gaskets 51-81. V

The eye loops of the dangle cathodes are loosely suspended on the bushings 58 so as to freely suspend their lower, gravity controlled ends 63 into the electrolyte or plating bath, while the barrel revolves, during the plating operation. By this construction the loosely suspended cathodes 63-64 are gravitationally held in operative position in the interior of the plating barrel. As above described current passes from th current source, through the conductor rod 31, through the anodes 38 and the plating liquid to the articles being plated, thence through the dangle cathodes 63-63, to the bushing 88, thence through the stub shaft assembly l6, then through the bolts 9 and 43, thence to and through the buss bar and its terminal 6 to the current source.

A further modification in forming a current conducting means to and from the interior of the plating barrel is shown in section, in Fig. 10, and it is very similar to the conducting hub shown and described for Fig. 3. In Fig. 10, like parts to those of Fig. 3 bear like lndices.

The stub shaft assembly, Figs. 9 and 10 comprises, in addition to the previously noted flange 2323, a threaded stem 29 and a hearing or shaft portion l6, both the stem and shaft being integral with the disc 23-23. A hearing bushing 18 is mounted on shaft It for the same purposes as described for Figs. 6 and 7.

The inside face 11', Fig. 10, of head I1, is provided with recess d into which is mounted a bored conductive cathode disc 23, generally denoted by E, the bore of said disc accommodating the threaded stem 29. The disc is flanged inwardly at its rim, as shown at 25, and at its central portion is in conductive contact with the raised circular extension 23' of disc 23. A non-conductive retaining disc 32, of smaller diameter than disc E, contacts with the outer face of disc E and presses it into flrm conductive engagement with the extension 23', under the action of a non-conductive threaded nut 30, which is mounted on the threaded end 29. The nut is provided with spanner wrench holes 3 l v The assembly of Fig. 10, usable on both heads I! of the drum D, is mountable in the same' manner, in the bearing of Fig. 6, as described for Figs. 3, 6 and 7.

In all of the above noted drum shaft assemblies, as shown in Figs. 3, Sand '7, the threads on the threaded ends 29 of each opposed drum bearin unit is of right hand pitch on one bearing and of left hand pitch on the opposite bearing, depending on the direction of rotation of the plating drum, this provision being made to insure that the normal operative direction of rotation of the drum will tend to tighten the nuts 39 and not to unthread them, and thus loosen the assembly.

In the cathode assembly just described for Fig. 10, the plating current is carried from the anodes through the plating fluid to the exposed rim 24 of disc E, and thence through the shaft I, through the bolts 9 and 43 to the bus bar 8. exactly as described for the cathode structures shown in Figs. 1, 3 and 6.

The drum shaft construction shown in Figs. 3, '7, 9 and 10, as will be apprehended, are all constructed to flt the protective bearing shown in Fi 6. The cathode constructions in the above noted figures also have a feature in common, in that they are all axially removable from within the drum interior by the releasing of the threaded, cathode retaining locking means 39 or it, and

thus the cathode members E'or 63 are easily replaced, when required.

Having thus described the invention what claimed is:

1. In an electro-plating apparatus, the combination of a pair of metallic bearings; a barrel including dielectric heads, eachhaving a central opening adjacent to one of the hearingaand an annular recess on the inner face of the head concentric with the opening; a metallic stubshaft received in each opening and having a smooth exterior end engaged in the adjacent bearing; said shaft having a threaded inner stem in the barrel, and an intermediate disk flange sunk in, and secured to the inner face of, the head; a metallic member having a central opening received on said stem; sealing means between said member and the barrel head; a non-conductive wrench-receiving head held against said stem and engaging said member; said member and wrench head constituting an assembly having threaded engagement with said stem for forcing the member toward the head.

2. In an electro-plating apparatus, the combination of a pair of metallic bearings; a barrel including dielectric heads, each having central openings adjacent to the respective bearings, and an annular recess on the inner face concentric with the opening; a metallic stub-shaft received in each opening and having a smooth exterior end engaged in the adjacent bearing;

said shaft having a threaded inner stem in thebarrel and an intermediate disk flange secured to the inner face of the head; a metallic cathode sealing disk having an inwardly off-set central portion lying flat against said disk and head and having central opening received on said stem; said portion being surrounded by an annular flat portion offset from the head and provided with a peripheral flange received in said annular recess; a centrally bored dielectric disk received on said stem and engaging and substantially covering said central portion; and a dielectric bushing screwed on said stem and against said dielectric disk.

3. In an electro-plating apparatus, the combination of a barrel including dielectric heads, each having a central opening; a metallic stubshaft received in each opening and having a smooth exterior end, a threaded inner stem in the barrel, and an intermediate disk flange sunk flush in, and secured to the inner face of, the head; a metallic cathode disk having an intramarginal circular portion having a central bore received on said stem; said portion being surrounded by an annular flat portion oifset from the head and provided with a peripheral flange; the head having an annular recess to receive the flange; a centrally bored dielectric disk received on said stem and engaging and substantially covering said intra-marginal portion; a dielectric bushing having a threaded bore received on said stem and clamping the cathode disk in place against the head and disk flange; the plane of said flange of the cathode disk being inherently inwardly offset from the plane of said intra-marginal portion, whereby when said bushing is screwed home, the peripheral flange is tensioned liquid-tight in said annular recess of the head and the dielectric disk is tensioned liquid-tight against the intra-marginal portion, and the bushing liquid-tight against the dielectric disk.

4. In an electro-plating apparatus, the combination of a barrel including dielectric heads;

a metallic stub-shaft secured in each head and having an exterior end, and a threaded inner stem in the barrel; a metallic bushing having a threaded bore received on the outer end of the stem; a sealing means on said stem between the head and bushing; a non-conductive wrench head of larger diameter than-the bushing secured to the end of the bushing; and dangle cathodes hanging on said bushing.

5. In an electro-plating apparatus, the combination of metallic bearings; a barrel in the tank including dielectric heads having central openings adjacent to the respective bearings; a metallic stub-shaft in each of said openings and having a. smooth exterior end engaged in the adjacent bearing; said shaft having a threaded inner stem in the barrel, and an intermediate disk flange sunk flush in, and secured to the inner face of, the head; a metallic bushing having a threaded bore received on the outer end of the stem; a sealing disk received on said stem, of slightly larger diameter than the disk flange, and disposed between the disk flange and bushing;v rubber gaskets between 'said sealing disk and bushing and between the sealing disk and periphery of the disk flange the adjacent portion of the head, whereby the bushing may clamp the disk, flange, head, gaskets and bushing together in a liquid-tight manner; a non-cona barrel including a dielectric head having a central opening therein; an electrically conductive supporting member comprising a stub-shaft in said opening and having a smooth exterior projecting end engaged in and electrically connected to the bearing, ashort threaded inner stem in the barrel and an intermediate disk flange rigid with the shaft and stem and firmly secured to the inner face of the head; a metallic member received on the stem and electrically connected with the supporting member; cathode metal carried by said metallic member in electrical connection therewith and therefore with the bearing and adapted to contact liquid in the barrel; sealing means between said metallic member and head, in contact with the head beyond the disk flange for sealing the metallic member and head together in a liquidtight manner when the metallic member is pressed toward the head; electrically non-conductive structure engageable liquid-tight with the outer face of said metallic member and including a wrench-receiving part adapted to be rotated by a wrench; said metallic member, said sealing means and said non-conductive structure, including the wrench-receiving part, together forming a continuous liquid-tight protection for said supporting member to prevent plating the latter, and forming a rotatable removable assembly, said assembly having a threaded portion in threaded engagement with the threads of the stem and rigid with the wrench-receiving portion for forcing said metallic member toward the barrel head on rotation of the wrench-receiving portion in one direction to effect said sealing, and for detaching the assembly when the wrench-receiving portion is rotated in the other direction.

7. In an electro-plating apparatus, the combination of an electrically conductive bearing; a

barrel including a dielectric head havingla central opening therein; an electrically conductive supporting member comprising a metallic-stubshaft in said opening and engaged in the bearing in electric contact therewith, an inner stem in the barrel and an intermediate projecting part rigid with the shaft and stem and firmly secured to the head; a metallic cathode disk in electrical contact with said member and having a central opening received on said stem; sealing means between the periphery of said cathode disk and said head and engaging the head beyond said projecting part; and dielectric means on said stem pressing on said dielectric disk and causing the latter to press said sealinnneans into sealing engagement with the head; said cathode disk,

said sealing means and said dielectric means cooperating to shield said supporting member from liquid in the barrel.

8. In an electro-plating apparatus, the combination of an electrically conductive bearing; a barrel including a dielectric head having a central opening therein; an electrically conductive supporting member comprising a metallic-stubshaft in said opening having a smooth exterior and engaged in the bearing in electric contact therewith, a short inner stern in the barrel and an intermediate disk flange rigid with the shaft and stem and firmly secured to the inner face of the head; a metallic cathode sealing disk having a central portion engaging in electrical contact flat against said disk flange and having a central opening received on said stem; said cathode disk being of larger diameter than the disk flange and provided with a peripheral flange turned toward and engaged with said head; a dielectric structure having a portion engaging flat against said central portion and leaving a marginal portion of the disk exposed to liquid in the barrel, and a threaded portion screwed on said stem and adapted to be turned on the stem to cause said structure to press against said dielectric disk and said peripheral flange to press into sealing engagement with the head; said structure, said peripheral flange and said dielectric disk forming a continuous liquid-tight protection for said supporting member.

9. In an electro-plating apparatus, the combination of an electrically conductive bearing; a barrel including a dielectric head having a central opening therein; an electrically conductive supporting member comprising a metallic-stubshaft in said opening having a smooth exterior end engaged in the bearing in electric contact therewith, a short threaded inner stem'in the barrel and an intermediate disk flange rigid with the shaft and stem and firmly secured to the inner face of the head; a metallic cathode sealing disk having a central portion engaging in electrical contact flat against said disk flange and having a central opening received on said stem; said cathode disk being provided with a peripheral flange turned toward and engaged with said head; a centrally bored dielectric disk of smaller diameter than the cathode disk received on said stem and engaging said central portion; and a wrench-receiving dielectric bushing screwed on said stem and pressing liquid tight against said dielectric disk and pressing the latter into sealing engagement with the cathode disk, and said peripheral flange into sealing engagement with the head; said cathode disk, said peripheral flange, said dielectric disk and said bushing forming a continuous liquid-tight protection for said supporting member.

10. An article of manufacture and sale comprising a metallic cathode disk having a flat intra-marginal circular portion having a central bore, said portion being surrounded by an annular flat portion inherently slightly offset in one direction from, and parallel to, the plane of the prising a barrel having a dielectric head having a central opening in which is engaged an electrically conductive member comprising a stubshafthaving a smooth exterior end, a threaded inner stem in the barrel and an intermediate disk flange secured to the inner face of the head; said.

cathode disk having an intra-marginal circular portion adapted to be pressed by means having threaded engagement with the stem into flat electric contact with said flange and having central bore adapted to be received on said inner stern; said circular portion being surrounded by an annular flat portion offset from and parallel to the plane of the circular portionand adapted to be disposed offset from the head when said circular portion is in said contact, said annular portion being provided with a peripheral flange; the plane of the edge of said flange of the cathode disk being parallel to and suiliciently offset from the plane of said intra-marginal portion in a engaging the bushing and the face adjacent thereto in a liquid-tight manner; said material, head, bushing and ring cooperating to shield the bearing portion of said shaft and the interior of the bearing from liquid.

14. In an electroplating apparatus, the combination of an electrically conductive metallic supporting bearing; a barrel disposable in plating liquid and including a dielectric head; an electrically conductive metallic stub-shaft secured fast to said head and having an exterior bearing end engaged in the bearing in electric contact therewith; a cathode in the barrel electrically connected to the shaft; means to shield the hearing portion of the shaft from liquid in the barrel; an insulating material covering said bearing and extending substantially to the shaft and formed said faces and tapered to the other of said faces direction opposite to said flrst named direction to provide sealing engagement with said head when the circular portion is'pressed into said contact.

' 13. In an electroplating apparatus, the combination of an electrically conductive metallic supporting bearing; a barrel disposable in plating liquid and including a dielectric head; an electrically conductive metallic stub-shaft secured fast to said head and having an exterior bearing end engaged in the bearing in electric contact therewith; a cathode in the barrel electrically connected to the shaft; an insulating material covering said bearing and extending substantially to the shaft and formed with an annular face around the shaft facing the adjacent face of the head; a dielectric bushing secured around the shaft and engaging one of said faces and disposed adjacent to the other of said faces to form therewith a seat; and a rubber ring in said seat to form therewith a seat; and a rubber ring in said gear engaging the taper of the bushing liquid-tight and directed by the taper against the face adjacent thereto in a liquid-tight manner; said material head, bushing, ring and means cooperating to shield the bearing portion of said shaft and the interior of the hearing from liquid.

15. In an electro-plating apparatus, the combination of an electrically conductive metallic bearing; a barrel including a dielectric head having a central opening adjacent to the bearing; an electrically conductive metallic stub-shaft in the opening and having a smooth exterior end engaged in the bearing in electriccontact therein; a cathode in the barrel electrically connected to the shaft; said shaft having an intermediate flange secured to the inner face of the head; means to shield the shaft and flange from liquid in the barrel; a liquid-tight insulating sheathing covering said bearing and extending to the shaft, and counterbored around the shaft; a dielectric tube surrounding the shaft and extending to the flange and fitting in the counterbore and said central opening: a dielectric washer on the tube and engaging against the sheathing; a thick dielectricbushing on the tube and tightly engaging the head and tapered to the washer to form therewith a seat; and a rubber ring in said seat of the taper liquid-tight and urged by the taper to engage the washer in a liquid-tight manner;

said sheathing, washer, tube, head, bushing, ring and means cooperating to shield said shaft and the interior of the bearing from liquid.

- KURT T. POTTHOFF.

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