Electroplating apparatus

Aug. 22, 1950 κ. a. w. twele etal 2,519,945

ELECTROPLATING APPARATUS

Filed Jan. 25, 1946 2 Sheets-Sheet 1

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Aug. 22, 1950 κ. a. w. twele etal 2,519,945

ELECTROPLATING APPARATUS '

Filed Jan. 25, 1946 2 Sheets-Sheet 2

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Patented Aug. 22, 1950

UNITED STATES PATENT OFFICE

2,519,945

ELECTROPLATING APPARATUS

Karl A. W. Twele, Philadelphia, and Albert D. Canner, Upper Darby, Fa., assignors to General Electric Company, a corporation Of New York

Application January 25, 1346, Serial No. 643,326

Claims.

Our invention relates to improvements in electroplating apparatus and more particularly to improvements in apparatus for rapidly plating a portion of a work piece.

It is becoming more and more the practice to have silver contact surfaces on electric current conductors such as bus bars, switch blades and studs, and the like. In order not to waste silver, it is customary to mask the piece to be plated by some suitable coating, leaving bare only the portion on which the silver surface is desired. The piece, or at least the part thereof containing the portion which is to be plated, is then immersed in a tank containing a suitable plating bath for a time sufficient to produce the desired thickness of plating. The plating time, of course, depends on the thickness of the metal deposit desired for the contact portion. The piece is then taken from the bath, drained and rinsed, and the masking removed. This process is slow because of the time required to apply, dry and remove the masking coating and the slowness of metal deposit due to the relatively low velocity of electrolyte circulation. Moreover, the masking feature, principally a manual operation, is costly.

An object of our invention is to provide improved apparatus for electroplating continuously with a minimum waste of electrolyte and without masking coatings. Another object of our invention is to provide improved electroplating apparatus utilizing the advantages of high velocity of electrolyte flow and high plating current densities. Still another object of our invention is to provide improved electroplating apparatus which functions substantially automatically to control the plating, draining and rinsing operations and which is practically foolproof. A further object of our invention is to provide improved electroplating apparatus embodying the maximum of safety to the operator as well as to the apparatus. A still further object of our invention is to provide improved apparatus for electroplating without using pumps which are subject to corrosion and other damage by the electrolyte. These and other objects of our invention will appear in more detail hereinafter.

In accordance with our invention, we provide improved electroplating apparatus wherein a plating head is used to mask only the portion of the work piece to be plated and wherein electrolyte is supplied to the plating head at high velocities under pneumatic pressure and plating current at high densities is used. Also in accordance with our invention, the plating hea.d is (Cl. 204—229) supplied with a rinsing liquid after a time sufficient to drain the electrolyte, and the steps of plating, draining and rinsing automatically proceed in the correct cyclic order with the preset 3 times necessary for each. Again in accordance with our invention, we provide an arrangement for so automatically and continuously circulating electrolyte from a reservoir to two tanks and from either tank pneumatically to the plating 10 head and return to the reservoir that one tank is being filled from the reservoir while the other tank is supplying electrolyte under air pressure to the work piece. Further in accordance with our invention, the plating head comprises rela15 tively movable members suitably arranged to engage the work piece and to mask the portion thereof to be plated and pneumatically operated to the masking position from which the members cannot inadvertently be released as long as there 20 is air pressure tending to cause flow of electrolyte and also while rinsing liquid is flowing to the work piece. Still further in accordance with our invention, we provide an arrangement for quickly running through the plating, draining and rinsing 25 cycle or whatever portion thereof is left in case of an emergency requiring, for example, the release of the plating head. Also in accordance with our invention, we provide improved plating heads for plating areas or one or simultaneously on both sides of a flat piece and for plating curved surfaces either internally or externally.

Our invention will be better understood from the following description when considered in connection with the accompanying two sheets of drawings, and its scope will be pointed out in ³⁵ the appended claims.

In the accompanying two sheets of drawings, Fig. 1 illustrates schematically, partly in diagram and partly in perspective, electroplating apparatus embodying our invention; Fig. 2 is an enlarged perspective view of the plating head shown in Fig. 1 with parts broken away to illustrate the internal structure; Fig. 3 is a part sectional illustration of the plating head shown in Fig. 2, ₄5 the section being taken substantially at right angles to the longitudinal axis of the work piece looking from right to left as viewed in Fig. 2; Fig. 4 is a part sectional elevation of a modification of the plating head shown in Figs. 1, 2 5Q and 3; and Fig. 5 is a vertical sectional elevation of a plating head for use in plating the convex contact portions of contact studs.

In the embodiment of our invention shown in Fig. 1, we have illustrated an arrangement for 55 plating, on one side or or both sides simultane-,

2,519.945 ously of a work piece I and around a hole 2 therein, a flat annulus 3 of silver. As shown, the work piece is a flat conductor which may be a copper bus bar, for example. For convenience in operating, the work piece i is so movably supported on a table comprising rollers 4 as to lie between the relatively movable members 5 and 6 of a plating head, shown in more detail in Figs.

and 3. In accordance with our invention, the members 5 and 6 are so constructed and arranged as to be actuated to engage the work piece i and mask the portion thereof to be plated. Thus, in this embodiment of the plating head, the lower member 5 is rigidly mounted on a suitable support, not shown, and the upper member 6 is arranged to be actuated by suitable pneumatic means comprising a cylinder 7 supported by brackets 8, shown in part in Fig. 2. Within the cylinder 7 is a piston 9 which is rigidly connected to the upper plating head member 6 by a piston rod 10. Through suitable means such as a fourway air control valve ACV and lower and upper pipes li and 12, respectively, air under pressure from a suitable source, not shown, is admitted to the bottom of the cylinder 7 to raise the upper plating head member 6 and to exhaust the air above the piston 9, and to the top of the cylinder 7 to lower the upper plating head member 6 and maintain it in the plating position and to exhaust the air below the piston 9. For safety features, hereinafter described, the air pipe 12 to the top of the cylinder 7 is provided with an air pressure switch APS whose contacts are closed only when the air pressure in the pipe 12 is above a predetermined value.

Referring now more particularly to Figs. 2 and which illustrate the plating head members 5 and 6 in the plating position against the work piece f, it will be observed that the body of the lower plating head member 5 is suitably ported for admission of liquids such as electrolyte and water through an inlet pipe 13 and discharge through a downwardly extending outlet pipe 14. In order to insure better circulation of electrolyte and rinsing liquid against the work piece, the inlet pipe 13 is so arranged as to discharge liquids tangentially to the exterior surface of a suitably shaped diverter and discharge element 15. As shown, this element, which is seated in a recess in the body portion of the member 5, has a generally conical exterior surface. With this arrangement, a. swirling action of the electrolyte and rinsing liquid is effected, as indicated by the arrows 16. Likewise, the plating head 6 is suitably ported for admission of liquids through an inlet pipe 17, discharge being by way of the hole in the work piece and the opening in the discharge element 15. As in the case of the lower plating head member 5, a- swirling action of introduced liquids is effected, as indicated by the arrows 18, by a tangential discharge against a diverter element 19 seated in a recess in the body portion of the upper plating head member 6 axially in line with the diverter element 15 in the lower plating head member 5. As shown, the shape of the diverter element 19 is substantially conical with a generally spherical end.

For masking the portion of the work piece I to be plated and also preventing escape of electrolyte and rinsing liquid, each of the plating head members 5 and 6 is provided with a recessed portion in which are seated a cushioning gasket 20, a sealing gasket 2 i and, between these, a supporting plate 22, the function of which is to support the sealing gasket 21 when it is neces sary to change the sealing gasket for masking a smaller area on the work piece. The gaskets 20 and 21 are of suitable resilient material such as rubber, and the supporting plate is metallic and 5 may be steel. For better sealing and locking action between the supporting plate 22 and the gaskets 20 and 21, the plate may be provided with annular raised ridges 23. For holding the gaskets 20 and 21 and the supporting plate 22 in place in 10 the respective plating head member, we provide a flanged retainer collar 24 secured to the respective member by suitable means such as screws 25. In case it is desired to plate only one side of the work piece I, then as shown in Fig. 4 the upper : 5 sealing gasket 21 is replaced by a sealing plug 21' having no central opening. With this arrangement, the electrolyte is prevented from touching the upper face of the work piece. In order quickly to drain the plating heads 5 and 6 after 20 the flow of electrolyte and rinsing liquid has been stopped, suitable means such as vent valves 26 are provided.

Plating current is supplied to the plating head members 5 and 6 from a suitable source of direct 25 current, indicated simply by plus and minus signs, and controlled through an electromagnetically actuated plating current switch PCS. From the upper plating head member 6, plating current is conducted to the work piece I by way of elec30 trodes 27 which are so resiliently supported on the member 6 as firmly to engage the work piece i when the members 5 and 6 are in the masking position. Thus, as shown, the electrodes 27 are mounted in housings 28 of suitable insulating 35 material carried on arms 29 of the upper plating head member 6 and are biased downward by springs 30. It will be observed that in order to avoid a short circuit of the plating current circuit when the plating heads are in the masking ⁴⁰ position, the sealing gaskets 21 and the sealing plug 21' should be of insulating material.

For aligning the work piece 1 relatively to the plating head members 5 and 6, we provide a locator 31 which is automatically swung into posi⁴⁵ tion over the work piece during the final portion of the upward movement of the upper plating head member 6 and is quickly swung out of the way of this member early in the downward movement thereof. For this purpose, the locator 31 is ⁵⁰ mounted on an arm 32 which is resiliently coupled to a shaft 33, pivotally supported on a bracket 34, and is arranged to be turned approximately 90° into position over the work piece I near the end of the upward movement of the ⁵⁵ plating head member 6 and vice versa. For this purpose, the shaft 33, as shown in Fig. 2, is square with an approximate 90° twist at its upper end and an actuator 35, provided with a square hole to register the shaft 33, is arranged to partake of ^G0 the movement of the plating head member 6. In order to permit overtravel of the shaft 33, the arm 32 is provided with a sleeve 36 which is positioned between the lower shaft bearing 37 and a . collar 38 secured to the shaft, and this sleeve is resiliently coupled to the shaft by a torsion spring 39 having one end secured to the collar 38 and the other end positioned in a slot in the sleeve 36. For definitely positioning the locator 70 31 relatively to the vertical axis or center line of the plating head members 5 and 6, a stop 40 on the bracket 34 is arranged to be engaged by an adjustably positioned lug 41 on the arm 32. In order to compensate for different thicknesses 75 of work piece, the locator 31 is yieldingly sus5 pended from the arm 32 by suitable resilient means such as springs 42. For smooth engagement with the work piece, the ends of the locator 3 f are bent upwardly as shown. For definitely locating the work piece, the locator 31 is provided wfth a hole 43 with which the hole in the work piece is to be registered.

Longitudinally the work piece is centered by moving the piece on its table rollers 4. To prevent scuffing the lower sealing gasket 21 during this process, we provide a resiliently supported roller 44 which is mounted on the base of the lower plating head member 5. This roller keeps the work piece clear of the lower sealing gasket 2f and yet allows the necessary downward movement of the work piece when the upper plating head member 6 is brought into the masking position. For laterally aligning the work piece, we provide suitable means such as a parallel motion mechanism which, as shown in Fig. 1, is arranged to move the work piece from the back of the machine to the front. Thus, as shown, this parallel motion mechanism comprises a plurality of rollers 45 against which the edge of the work piece f abuts. These rollers are supported on angles 46 whieh are arranged to be moved transversely of the work supporting table without change in direction. For this purpose, we provide a plurality of actuating shafts 47, only two of which are shown in Fig. 1. These shafts are supported in stationary bearings 48 and are connected to the angles 46 by cranks 49 which are rigid on the shafts and pivotally connected to the angles. For turning the shafts ti simultaneously, we provide an actuator bar 50 which is connected to all of the shafts by cranks 5! and 52 which are rigid on the shafts and pivotally connected to the actuator bar. For moving the actuator bar, one of the cranks 52 is a bell crank, the arm 52' of which carries a swivel nut 53 for engagement by a threaded operating shaft 54. This shaft is supported at its outer end against longitudinal movement in a swivel bearing 55 and is provided: with an operating crank. 56.

For supplying electrolyte to the plating head continuously during the plating operation, we provide a reservoir ER for electrolyte and two suitable, preferably metallic, tanks ETI and- ET2 Which are adapted to be supplied with electrolyte from the reservoir ER and with air under pressure thereby avoiding the use of pumps which would be subject to corrosion and other difficulties. Flow of electrolyte from the reservoir ER is by way of a manually controlled electrolyte valve EVI, a pipe 57 and an inlet check valve ICI to the tank ETI and by way of a manually controlled electrolyte valve EV2, a pipe 58 and an inlet check valve IC2 to the tank ET2. The check valves ICI and IC2 are to prevent flow of electrolyte from their respective tanks to the reser- ₍voir when the tanks are under air pressure. For effecting a flow of electrolye from either of the tanks ETI or ET2 to the plating head and thence to the reservoir ER, we provide valve means operative in dependence on the levels of the elec- ₍trolyte in the tanks for substantially simultaneously stopping the flow of air to one tank when the electrolyte therein falls to a predetermined level and starting a flow of air to the other tank when the surface of the electrolyte therein is · above a predetermined level. As shown, this means includes solenoid operated three-way air valves AVI and AV2 which are arranged to control the flow of air- to and from the tanks ETI and ET2, respectively, by way of their respec- ;

2,519,845

5ΙΪ5 ζα ively associated pipes 59 and 60 and surge Compartments 61 and 62 for keeping electrolyte out of the air lines. Flow of electrolyte from the tanks. ETI and ET2 to the plating head is by way of pipes S3 and 64, respectively, through outlet check valves OCI and OC2 to a common pipe 55. The outlet check valves OCI and OC2 are. arranged to prevent flow of electrolyte from the tank which is under, air pressure to the tank H's which is not. While for convenience in illustration we have shown, the electrolyte tanks ETI and ET2. at different elevations relatively to the electrolyte reservoir ER, it is to be understood that both tanks may be at the same elevation and preferably are below the reservoir so as to have gravity flow from the reservoir to the tanks, thereby eliminating the need for circulating pumps and the controls necessary thereto. It will also be understood that the supply of electrolyte, may be replenished from time to time as required and suitable metallic salts or metal added to the electrolyte in a manner well known to the art.

For automatically controlling the flow of air into and out of the tanks ETI and ET2 in response to tho level of the electrolyte therein, we provide a plurality of electrically interlocked rer lays R2, R3 and R4 which are arranged to be energized from a suitable preferably low voltage souree indicated as a potential transformer T which has its high voltage winding connnected across busses 63, 67, the energization of which is arranged to be controlled in a manner hereinafter described. The interlocking arrangement of the relays R2, R3 and Ri is such that 35 when the level of the electrolyte in the tank ETI is above the bottom of the electrode El and the transformer T is energized, the relay R2 is energized to effect through the closing of its upper contacts 68 the energization of the winding 63 of the air valve AVI whereby to open this valve and admit air to the tank. Also, with the closing of the middle contacts 70 of the relay R2, the relay R4 is energized to close its sealing-in contacts 71 and its lower contacts 72 in circuit with the winding of the relay R3. The relay R3, however, which through its upper contacts 73 controls the circuit of the winding 74 of the air valve AV2, cannot, be energized as long as the lower contacts 7 5 of the relay R2 are open. When, however, the relay R2 drops out because the level of. the electrolyte in the tank ETI falls below the bottom of the electrode El, the winding 69 of the air valve AVI is deenergized and the relay R3 is energized through the lower closed contacts 75 of the relay R2 and the lower closed contacts 72 of the relay R4 if the level of the electrolyte in the tank ΞΤ2 is above the bottom of the electrode E2 whereby to pick up and interrupt at its contacts 76 the circuit of the relay R2 and complete at its contacts 73 the circuit of the winding 74 of the air valve AV2. While the electrolyte in the tank ET2 is flowing to the plating head, the tank ETI is being refilled from the reservoir ER. When the level of the electrolyte in the tank ET2 falls below the bottom of the electrode E2, the relay R3 is deenergized to drop out the solenoid operated valve A VS and reenergize the relay R2 if the level of the electrolyte in the tank ΞΤt is above the bottom of the electrode El. The relay R4 when once energized and sealed in remains in this condition as long as the transformer T is energized. In order to avoid arcing between the solution and the electrodes El and E2, suitable resistances- 77 and 78 are respectively connected betweeii the electrodes Ei and E2 and the solutions in the tanks ETI and ET2.

For controlling the flow of electrolyte and rinsing liquid to and from the plating head in the sequence of electrolyte to the plating head, draining electrolyte therefrom, water to the plating head and draining water therefrom, we provide a multiple valve means MV which, as schematically shown, comprises suitably ported body portions Bi and B2. The body portion Bi is provided with valves VI, V3 and V5 and the body portion B2 with valves V2, V4 and V6, all spring biased to close. These valves are arranged to be actuated in a predetermined sequence by suitably shaped and angularly disposed valve cams Cl through C6 which are rigidly mounted on a common shaft indicated by the dash-dot line SVS. This shaft is arranged to be actuated by suitable motive means such as a control motor CM working through a reducing drive 79. For the purpose of the drawing, the rotation of the shaft and the cams is clockwise as indicated by the arrow A. The common electrolyte flow pipe 65 from the tanks ETI and ET2 enters the valve body portion Bl above the valve VI. When the valves VI and V3 are open and the other valves are closed, that is the cams CI through C6 have been turned clockwise about 90° from the positions shown, electrolyte can flow through a pipe 80 to the lower plating head member 5 by way of the pipe 13 and to the upper plating head member 6 by way of a pipe 81 which is flexible in order to accommodate itself to the movement of this upper plating head member. Electrolyte flow from the plating head is by way of the pipe 14 to the chamber above the valve V3, thence through this valve and a pipe 82 to the chamber above the valve V4 and return to the reservoir ER by way of a pipe 83. In order to reduce splashing and wave action in the reservoir ER, a baffle wall 84 adjacent the pipe 83 is provided.

When the cams have been turned about 180°, the valve VI is closed, the valve V4 is opened, the valve V3 remains open and the other valves remain closed. Electrolyte can now drain from each of the plating head members 5 and 6 through the pipes 14, 80 and 82 and a pipe 85 to the reservoir ER by way of the return pipe 83. When the cams have been turned through about 270°, the valves V2 and V5 are opened, the valves V3 and V4 are closed and the other valves remain closed. A rinsing liquid such as water can now flow from a source of water under pressure through a solenoid operated water valve WV, assumed open, to the chamber below the open valve V2 and thence by way of the pipes 85 and 80 to the plating head members 5 and 6 and return through pipe 14 to the chamber above the closed valve V3. The discharge of the water is then through the open valve V5 to a pipe 86 leading to a sewer or other suitable drain. When the cams have been turned about 360°, the valves VI through V4 are closed and V5 and V6 are open, as shown. During this last 90° of movement, the valve V2 is quickly closed to stop the flow of water so that water can drain from both plating head members 5 and 6 by way of the pipes 14 and 8! and also by way of the pipes 89, 85 and a pipe 87 discharging to the sewer through the open valve V6.

For controlling the durations of flow of electrolyte to the plating head, the draining of electrolyte from the plating head and the flow of rinsing liquid to the plating head, we provide timing means comprising a plating timer PT, a

2,619,846 draining timer DT and a rinsing timer RT. As shown, each of the timers comprises a motor 88 which is arranged to drive through a solenoid operated clutch 89 a rotatably mounted contact g controlling member 90 against the bias of a spring 91. The member 90 is arranged to engage and close after a predetermined time a pair of normally open relatively movable contacts 92 which are adjustably positioned on a support 10 93 so that the time can be varied according to requirements. In accordance with our invention, these timers are arranged to effect the energization of the control motor CM at the end of the respective plating, draining and rinsing If periods. For this purpose, the contacts 92 of the three timers are connected in parallel with each other and in series with the winding of a relay R7 across the busses 66 and 67. This relay, through its contacts 94, upon energization conM nects the control motor CM across the busses 66 and 67.

For controlling the sequence of operation of the timing means and the flow of plating current to the plating head, we provide cyclic switchM ing means S2, S3 and S4 which are arranged to be actuated by the control motor CM. As shown, each of the switching means is double throw and is arranged to be biased to one circuit controlling position by suitable resilient means such M as a spring 95. For movement to the other circuit controlling position, the switch and valve shaft SVS is provided with suitably shaped and angularly disposed cams C8, C9 and CIO rigidly secured to the shaft and respectively arranged U to actuate the switches S2, S3 and S4.

For controlling the energization of the plating current switch PCS and the plating timer PT, the winding 96 of the switch and the clutch winding of the timer are arranged to be connected in 40 parallel across the busses 66 and 67 through conductors 111 and 97, the upper contacts of the switch S2 and the conductors 98 and 99. Similarly, the clutch winding of the draining timer DT is arranged to be connected across the busses 45 θθ and 67 through conductors III and 100, the lower contacts of the switch S3 and the conductors 98 and 99. Also, the clutch winding of the rinsing timer RT is arranged to be connected across the busses 66 and 67 through conductors 50 HI and 101, the upper contacts of the switch S4 and the conductors 98 and 99. For indicating purposes so that the operator may know the progress of the plating operation, we provide lamps L2, L3 and L4 connected in parallel with ¢5 the clutch windings of the timers PT, DT and RT, respectively.

For the safety of the operator so that the plating head members cannot be released from the masking position while there is air pressure 60 above a predetermined value in the top of the cylinder 7 and while the plating, draining and rinsing operations are under way, we provide an air control lock ACL having an energizing winding 102. This lock comprises a biased pivotally 65 supported member 103 which is arranged upon energization of the winding 102 to engage an extension 104 on the handle H of the air control valve when it is turned clockwise about 90° from the position shown whereby to prevent move70 ment of the handle and any change in the position of the air control valve. The operating shaft of the air control valve is indicated by the dashdot line 105. The circuit of the winding 102 of the air control lock ACL is arranged to be con75 troliecj by the lower contacts of a double throw

8,519,945 switch SI which is arranged to be actuated by a cam C7 on the shaft SVS. When the electroplating apparatus is in the off position shown, the lower contacts of the switch SI are open and the upper contacts closed, but the cam C7 is so . arranged that quickly upon the starting of the motor CM the switch SI is operated to open its upper contacts and close its lower contacts and maintain this condition throughout nearly one revolution of the shaft SVS. The circuit of the i air control lock winding 102 is across the busses and 67 on the deenergized side of the air pres- sure switch APS so that no locking can occur unless the plating head members 5 and 6 are in the masking position. i

When it is desired to plate, a supply switch SS is closed on a suitable source of electric current and the work piece I is aligned transversely by the parallel motion mechanism and by longitudinal movement until the hole in the work piece is centered under the hole 43 in the locator 31. The air control valve handle H is then turned clockwise about 90° to admit air to the top of the cylinder 7 above the piston 9 and simultaneously the air below the piston is exhausted, y Assuming the air pressure is above the desired value, the upper plating head member 6 is actuated to the masking position, the locator 31 being quickly swung to the off position as the plating head starts its downward movement, and ;&lt; the air pressure switch APS closes its contacts. A relay R5 connected across the busses 66 and then picks up. As long as the upper -contacts of Si are closed, the relay R5 will remain energized even though the air pressure switch APS 3 drops out because the relay R5 seals itself in through its own contacts in a circuit including a conductor 106, the upper contacts of the switch SI and a conductor 107 to the supply side of the air pressure switch APS. ΐ

To start the apparatus in operation, a manually operated switch such as a starting push button SPB is closed. This switch completes the energizing circuit of the transformer T and the circuit of the winding of a relay R1 which picks 4 up and through its upper contacts seals in around the switch SPB. The energizing of the transformer T starts the sequence of operation of the relays R2, R3 and R4, heretofore described, so that electrolyte may flow from one of the S tanks ETI or ΞΤ2 to the multiple valve mechanism MV and from the reservoir ER to the other tank. The closing of the lower contacts of the relay Rl completes the circuit of the winding

108 of the water valve WV through a conductor ;&gt;

109 and the conductor 106 to the upper contacts of the relay R5. The circuit of the winding 108 of the water valve WV is also momentarily completed independently of the air pressure switch APS by way of the upper contacts of the switch c SI and the conductor ¢07. Everything is now in readiness for the plating operation.

To start this operation, a switch such as a plating push button PPB is closed. This connects the winding of a plating control relay R6 and ti an indicating lamp Li in parallel therewith across the busses 66 and 67 through a conductor 110, the lower contacts of the switch S2, the upper contacts of the switch S3 and the lower contacts of the switch S4, all in series, and the conductor 7 99. The relay R6 then seals in through its upper contacts. Through its lower contacts, the relay R6 effects the energization of a motor control relay R7 by connecting its winding to the conductor 110 which returns to the bus 67 by way of the 7 closed contacts of the switches S2, S3 and S4 as described for the circuit of the relay R6. With the closing of its contacts 94, the relay R7 connects the control motor CM across the busses 5 66 and 67, and the switch and valve shaft SVS is started turning.

After a slight turning of the shaft SVS, the cam Cl opens the upper contacts of the switch SI and closes its lower contacts. The winding ο 198 of the solenoid operated water valve WV, however, remains energized through the lower contacts of the relay Rl and the contacts of the relay R5 as heretofore described. With the closing of the lower contacts of the switch Si, the _β circuit of the winding 102 of the air control lock ACL is completed from the bus 66 through the conductor III, a conductor 112, the lower contacts of the switch SI and a conductor 113 to the bus 67. As long as the air control lock is energized 0 to engage the extension 194 on the handle H, the plating head members 5 and 6 must remain in the masking position, that is, as long as there is air pressure in the pipe 12 above a predetermined value.

_;6 Also, after the shaft SVS is turned clockwise a slight amount, the valves V5 and V6 close.

After the shaft SVS is turned about 90°, the lower contacts of the switch S2 are opened and its upper contacts closed. The opening of the lower con0 tacts of the switch S2 deenergizes the relays R6 and R7 and thereby effects the stopping of the motor CM. Also, the valves VI and V3 are opened. Electrolyte is now free to flow from whichever one of the tanks ETI or ET2 is in :-, service to both of the plating head members 5 and 6 through the valve VI and return by way of the valve V3 and the pipes 82 and 83 to the reservoir ER. With the closing of the upper contacts of the switch S2 by the movement of the ,0 cam C8, the circuit of the winding of the clutch of the plating timer PT is energized from the bus 66 through the conductor 111 to the winding of the clutch, the conductor 97, the upper contacts of the switch S2 and the conductors 98 and 5 99 to the bus 67. At the end of a predetermined time requisite for the desired thickness of plating, the contacts 92 of the plating timer PT are closed to effect the energization of the relay R7 from the bus 66 through the winding of the relay R7, i) a conductor 114, the contacts 92 of the plating timer PT and a conductor 115 to the bus 67.

Upon reenergization of the relay R7, the circuit of the control motor CM is again energized and the shaft SVS started turning. After the r&gt; shaft has again turned through approximately 90°, the switch S2 is released by its cam C8 for its spring 95 to open its upper contacts and close its lower contacts. The opening of the upper contacts deenergizes the clutch of the stalled Ο motor plating timer PT which then opens its contacts 92 to deenergize the relay R7. This relay drops out to deenergize the control motor CM. Also, after a small movement of the shaft SVS from the 98° position, the valve VI is closed to stop the flow of electrolyte to the plating head members 5 and 6. By the time the shaft SVS is turned shout 180°, the valve V4 is opened. Electrolyte is now free to flow from both of the plating head members through the valves V3 and V4 0 to the reservoir ER by way of the pipe 83. The time for this draining operation is controlled by the draining timer DT which is started into operation by the energization of the winding of its clutch 89 when the cam C9 at the end of about y 180° of movement opens the upper contacts of

2,619,946 the switch S3 and closes its lower contacts. The circuit of the clutch winding is then from the bus 63 through conductor 111 to the winding of the clutch, the conductor 100, the lower contacts of the switch S3 and the conductors 98 and 99 to the bus 67. At the end of a predetermined time requisite for draining the plating solution from the plating head members 5 and 6, the contacts 92 of the draining timer DT are closed to reenergize the motor control relay R7 through a circuit comprising a conductor 116 and the conductor i! 4, and the control motor CM is again energized to continue the clockwise rotation of the shaft SVS. After another approximately 90° of rotation of the shaft SVS, the switch S3 is actuated by its cam C9 to open its upper contacts and deenergize the clutch of the stalled motor draining timer DT and to close its lower contacts. Also, the valves V3 and V4 are quickly closed. Also at the end of about 270° of rotation of the shaft Sirs, the valves V2 and V5 are opened, but the other valves VI and VS remain closed. Water is now free to circulate by way of the valve V2 to the plating head members 5 and 6 and return by way of the pipe 14 and thence through valve VS to the sewer. The switch S4 has also been actuated by its cam C10 to open its lower contacts and to close its upper contacts. Upon closing its upper contacts, the circuit of the winding of the clutch 89 of the rinsing timer· RT is energized from the bus 66 through the conductor Hi, the winding of the clutch, the conductor 101, the upper contacts of the switch S4 and the conductors 98 and 99 to the bus 67. At the end of the desired time for the rinsing operation, the contacts 92 of the rinsing timer RT are closed, and the circuit of the winding of the motor control relay R7 is again completed from the bus 67 through a conductor 117 and the conductor It 4 to the bus 66.

With the reenergization of the relay R7, the control motor CM is again started into operation to turn the shaft SVS. After another approximately 90° rotation, the switch S4 is released by its cam C10 to open its upper contacts and thereby deenergize the clutch of the stalled motor rinsing timer and to close its lower contacts. The valve V2 is quickly closed to stop the flow of water to the plating head members 5 and 6. Also after about 360° of rotation, the valve V6 is opened. Water in the plating head then is free to drain through the pipes 89 and ' 4 back into the valve body and thence to the sewer by way of the pipes 86 and 87. Also, at the end of the 360° of rotation of the shaft SVS, the lower contacts of the switch SI are opened to effect the deenergization of the air control lock ACL and the upper contacts are closed. The operator is novz free to turn the handle H of the air control valve ACV counterclockwise and. move the plating head member 6 upwardly from the masking position. When this is done, the relay RS and everything energized through the air pressure switch APS drop out and the parts are positioned as shown in Fig. 1 except for the relay R! which remains energized through the upper contacts of the switch SI to maintain solution and water pressures on the valve MV. The work piece I may then be moved along the supporting table on its rollers 4 for plating another spot or another work piece may be substituted as the occasion requires.

If at any time during the operation it is desired to stop the flow of air and water to the multiple valve MV, a normally closed switch such as a release push button RPB may be actuated to the.

open position whereby to deenergize the relay Rl and the transformer T. This effects the closing of the water valve WV and whichever one of the air valves AV I or AV2 was open at the time.

For emergency operation after starting, we provide a normally open switch such as an emergency push button EPB. When this switch is closed, it energizes a supplementary motor control relay R8 through a circuit including a conductor 118, the lower closed contacts of the switch SI and the conductor 113. When the relay R8 picks up, it seals in through its lower contacts, and through its upper contacts it completes the energization of the motor control relay R7 in a circuit including this relay, a conductor 119, the upper contacts of the relay R8, the conductor 118, the lower contacts of the switch SI and the conductor 113. The motor control relay R7 completes the circuit of the control motor CM which then runs continuously to finish one revolution of the shaft SVS independently of the timers. When SI opens its lower contacts, relays R7 and R8 are deenergized and the control motor CM stops. In connection with this emergency operation, it is, of course, assumed that the air pressure switch APS has its contacts closed.

For plating the outer surface 120 of the end of a contact stud 121, we provide a plating head such as shown in Fig. 5, for example. As illustrated, this plating head comprises a suitably ported base 122 which is provided with an inlet pipe 123 for plating and rinsing liquids and a suitably secured sealing cap 124 tapped for an outlet pipe, as shown. Seated in a recess in the base 122 is a nozzle 125 having a plurality of discharge openings or ports 126 in liquid flow connection with the inlet pipe 123 through a port in the pipe 122. For centering, supporting and insulating the stud 121, the nozzle 125 is provided with a central portion 127 which is recessed for mounting an insulating shell 128. Within this shell is slidably and resiliently supported a centering element 129 movable in a sleeve 130. For further insulating and also for masking purposes, we provide a sealing gasket 131 which is centered by the sleeve 130. For directing the flow of electrolyte and rinsing liquid over the rounded surface 120 to be plated, we provide a shell 132 which, as shown, is in the form of a hollow frustrum of a cone with a generally spherical inner surface at its upper end, this surface being shaped to conform to the surface 120 to be plated. Also, as shown, the shell 132 is secured to the base of the nozzle 125. For confining the flow of liquids after passage through the nozzle 125 and between the shell 132 and the contact surface 120, we provide an outer housing 133 which is suitably secured to a flange on the base 122. For sealing the contact stud 121 against escape of liquids, we provide a sealing tube 134 of suitable material such as rubber. This also serves to insulate the stud from the remainder of the plating head structure so as to avoid a short circuit of the plating current circuit. As shown, the tube 134 is housed in a suitably shaped cover 135 suitably secured to the housing 133. In accordance with our invention, this sealing tube 134 is arranged to be supplied with air in a manner similar to the arrangement shown for the cylinder 7 in Figs. 1 and 2. Also, the stud 121 may be arranged to be held in the plating position by pneumatic means analogous to the arrangement shown in Figs. 1 and 2 for the plating head 6. For venting the liqu’d chamber, a vent valve 136 js provided. With the arrangement shown in

2,618,945

Fig. 5, plating current connections are-made to the base (22 and to the stud 121 as will be apparent to those skilled in the art. Apart from the differences described in the structure shown in Fig. 5, the operation is essentially the same as for the arrangement shown in Fig. 1 embodying the plating head arrangement shown in Figs. 2 and 3. In other words, there is no essential difference in the automatic controls and operation.

While we have shown and described our invention in considerable detail, we do not desire to be limited to the exact arrangements shown, but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of our invention.