US2341158A - Electroplating apparatus - Google Patents

Description

Feb. 8, 1944. J. 5. NACHTMAN I 2,341,158

ELECTROPLATING APPARATUS Original Filed Jan. 16, 1939 3 Sheets-Sheet 1 Jolm/ JYNac/zimarz x w www Fe. 8, 1944. .1. s. NACHTMAN 2,341,158

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ELECTROPLATING APPARATUS Original Filed Jan. 16, 1939 3 Sheets-Sheet 3 Jblmfmiman Patented Feb. 8, 1944 mthltt all ELECTROPLATING APPARATUS John S. Nachtman, Youngstown, Ohio Original application January 16, 1939, Serial No.

251,065. Divided and this application March 17, 1942, Serial No. 435,030

4 Claims. (or. 204-206) This invention relates to electro-baths, and particularly, to the handling of strip material while subjecting it to an electro-treating process, such as electroplating. I have particular reference to suitable apparatus for continuously electroplating or treating meta1 strip and the like. This application is. a division of my copending application Serial No. 251,065, filed January 16, 1939.

I have found that there are many difficulties encountered in providing a suitable arrangement for the purposes enumerated. In electro-treatment, the strip will constitute one of the electrodes (in plating, the cathode) and other means will constitute the other electrode (in plating, the anode).

Some of the difficulties with prior methods and apparatus for continuously treating metal. strip occur because the strip is not perfectly straight (i. e., possesses camber), as a result of which it undergoes a lateral sliding motion as it passes over the various rolls and contacts the Walls of the plating tank and other parts of the apparatus, resulting in damage thereto. Since the anodes are located in a predetermined central position in the plating tank, this sidewise shifting of the strip results in the deposition of a non-uniform electro-deposit on the strip.

It is accordingly a general object of my invention to provide a commercially practical solution of these difficulties.

More specifically, it is an object of my invention to provide electroplating apparatus for strip material that will automatically center the strip in its passage through the bath and prevent it from contacting the sides of the electro-tank.

These and other objects of my invention will appear to those skilled in the art from the drawings, the description, and the appended claims.

Although for the purpose of illustration, I particularly refer to electroplating operations, it should be understood that many of the novel features of this invention are equally applicable to electro-pickling and other types of electrobath treating operations.

In the drawings:

Figure 1 is a side elevational view of an electroplating apparatus embodying my invention.

Figure 2 is a vertical sectional view taken along the line 2-2, of Figure 1, looking in the direction of the arrows in ,this figure; the relativ location of the contact roll assemblies, the submerged roll assembly, the anodes, the bus bar assembly and electrolyte conduits are shown.

Figure 3 is a vertical longitudinal sectional View taken substantially along the line 3-3 of Figure 2, looking in the direction of the arrows.

Figure 4 is a side elevational view, with parts broken away of a combined squeegee roll and strip centering roll assembly.

Figure 5 is a top plan view of the structure shown in Figure 4.

Figure, 6 is a view in elevation, with parts broken away, looking at the left hand end of the structure shown in Figure 4, with the end plate removed.

Figure 7 is a cross sectional view taken substantially on the line 1---! of Figure 6.

Figure 8 is a diagrammatic view of the electric circuitand the electric units employed in the structure of Figures 4-7, inclusive.

With continued reference to the drawings, wherein like reference characters have been used to designate like parts throughout the several views thereof, the apparatus comprises a tank or container T through which the strip material S is fed in a sinuous path. The strip material is reeved over and under respectively, a series 7 of upper rolls and 26 and lower rolls R. The

rolls R are submerged in the solution, but the rolls 25 and 26 are above the surface of the solution. Abov the strip where it passes over each roll 26, is a contact roll 25, by means of which electrical contact for the plating current is made with the strip, instead of through roll 26, as in the practice usually followed hitherto. The rolls 25 are preferably driven at the same peripheral speed so as to propel the strip smoothly through the bath.

As the strip emerges from the bath for the last time, it passes through a squeegee assembly Q for removing the adhering electrolyte therefrom. An anode electroplating current is applied to a plurality of anodes A which are suspended in the bath between the vertical reaches of strip 5. The electrolyte is continuously circulatedpreferably, by removing a portion of it from tank T, filtering it, passing it through a heat exchanger (for imparting heat thereto or dissipating heat therefrom, as the case may be, for securing the requisite electroplating temperature), and returning it to tank T ata point remote from the removal point. The electrolyte is returned to the electroplating tank in such manner as to continuously agitate the body of electrolyte in the tank adjacentAthe anodes and also to flush strip S above the level of the electrolyte for dis lodging adhering extraneous matter, both as it is entering and emerging from the electrolyte.

' Tank' and support constru tion Tank T is generally rectangular in form and comprises side walls ID, a bottom wall I I, and end walls 52. For the purpose of simplifying the illustration of the invention, I have shown the strip as making only two complete passes through the electrolyte. but it is to be understood that in actual practice the tank and other parts will be so designed as to cause the strip to make any suitable number of passes through the electrolyte; in some instances several hundred feet of strip material may be immersed in the tank at one time.

Communicating with the bottom of the tank is a circulation pipe I3, through which the electrolyte is fed to an electrolyte reconditioning and heat-exchanging apparatus of any suitable charactor, for purifying the electrolyte, restoring it to proper strength and bringin it to the requisite electroplating temperature.

The electrolyte is returned to the tank by way of a pair of spray pipes I4 and a pair of recirculation pipes I5. Spray pipes I4 may extend longitudinally of the apparatus and they are joined by a plurality of pairs of perforated pipes 66. The pipes of each pair are disposed at either side of the path of travel of the strip S and the perforations are directed downwardly at an angle to the horizontal for flushing the strip and cleansing it of any adhering material.

Pipes 85 are each joined to a horizontal pipe I8 and as seen in Figure 2, each pipe I8 extends longitudinally on either side of the path of travel of the strip S. Joined to pipes I8 at spaced interare vertical pipes 19 each having perforations 26 therein that are directed toward the middle of the tank. The electrolyte issuing from openings 25 supplies fresh electrolyte adjacent the anodes and also keeps the body of the electrolyte in the tank in a state of constant agitation.

The contact roll assemblies and other parts of the mechanism are carried upon a pair of horizontally extending angle members 22, which extend longitudinally of the apparatus and rest on a plurality of vertical supports 23. The mechanism preferably is supported upon the independent framework just described in order that the tank may not be subjected to stresses. The tank may, accordingly, be constructed of wood, concrete, brick, steel, hard rubber, or any other material or combination of material appropriate for use with the particular electrolyte employed, without special regard for supporting the assemblies and parts. To this end, the bus bars and anodes are also supported upon an independent structure.

Contact roll assembly The contact roll assembly as shown in Figures 1-3, inclusive, are similar in construction and therefore one of them will be described.

Each assembly comprises a contact roll 25 proper hich is mounted for movement to and from an associated strip carrying roll 28.

Referring to Figures 1, 2, and 3, each contact roll 25 is journaled on a shaft 21 which is carried, at each end thereof, in an arm 28, which in turn is pivoted at 29 on a support 3|, carried by members 22. Shaft 21 is insulated from members 28 by means of insulating backings 32; and an electrical conductor 33, preferably of flexible design, is connected to each end of shaft 21 for applying a cathode current to shaft 21 and to contact roll 25.

Each strip carrying roll 26 is preferably made of steel and rubber (flexible) covered in order that it may effect intimate surface engagement between the strip S and the contact roll 25. However, the surfacing of the carrying roll may be constructed of any other material found suitable for the purpose, such as micarta, asbestos, or other materials or combinations of materials. Each carrying roll is supported on a shaft 35, which latter is journaled at each end in a bearing 36 carried by the support 3I. A slinger 31 is positioned on shaft 35 adjacent each side of the carrying roll; it, functions to keep the electrolyte (with which the carrying roll is coated in normal operation by reason of the strip carrying it out of the tank) from creeping along the shaft and into the bearings.

Each contact roll 25 is resiliently urged toward a carrying roll, preferably by means of compression springs 39 that act upon extensions H of the arms 28. Each extension 4| is apertured, and a stud 42, through the aperture and through spring 39 and has a nut 43 threaded thereon, against which the spring 39 abuts.

By adjusting nuts 43 of each contact roll assembly, the strip can be gripped between surface portions of the contact roll 25 and the strip carrying roll 26 in contact with the strip with variout degrees of compression. A second compression spring 44 is shown on each stud 42 between extension M and support 3| for opposing the action of spring 39. and smoothing out the gripping action of the contact roll assemblies.

Each contact roll 25 is preferably hollow and provided with novel means for conducting the cathode current from the stationary shaft 21 to the roll. The contact roll construction, together with roll driving means, the submerged roll construction, and the anode and bus bar construction, are all fully disclosed in my copending application Serial No. 251,065, of which this application is a division.

Combined squeegee and centering roll assembly In feeding strip material continuously, there is a possibility of camber or misalignment in the strip after the component parts thereof have been welded or otherwise joined together. Where such a strip is propelled through a plating tank, it will have a sidewise motion and will be damaged if its edges 'come into contact with the stationary parts of the plating machine; anuneven electrodeposition will occur and the tank, itself, undergo damage. Accordingly, there is provided in the apparatus of the invention a novel strip guiding or centering device which is fully automatic in operation and insures against the disadvantages just discussed.

Referring more particularly to Figures 3 to 8 inclusive, a pair of squeegee rolls III and H2 are journaled on a rocking base support H2; the latter is mounted for rocking movement in a trunnion H4 on a stationary support H5. The other end of the rocking support H3 is guided in a frame-like, stationary member I I6, which engages opposite edges H1 and H8 of support H3, see Figure 6; roll H2 is journaled in the left hand portion of base H3 at I20.

Roll III is journaled at H9 in a pair of arms I2I, which are pivoted at I22 to base H3. A

screw I23 actuated by a hand wheel I24, is threaded into each end of base H3 and acts upon a compression spring I25 to apply pressure to pivot arms I2 I, for gripping the strip between secured to the support 3|, extends the squeegees under selectively variable degrees of pressure.

Squeegeerolls III and H2 are disposed in a side-by-side relationship in housing H (see Figure 1), above the tank T, in order that electrolyte squeezed from the surface of the strip will freely gravitate back into the tank. In order to Switch I42 is mounted for movement as a unit prevent electrolyte from working along the shafts supporting the rolls and finding its way to the bearings, each shaft is provided with a pair of slingers I21. The shafts for rolls III and H2 are provided with intermeshing gears I28 and I29, respectively, that are actuated by a chain driven sprocket I3I carried by the shaft of roll II2. Sprocket I3I may be driven to give rolls III and H2 a peripheral speed equal to that of the other rolls by a synchronously driven motor.

I also preferably associate the novel centering means or strip guiding means of my invention with the squeegee rolls, but it is to be understood that, if desired, it may be associated with one of the contact roll assemblies or may be duplicated and be applied to two or more of the contact roll assemblies.

Means, actuated by the lateral movement of the strip material are provided for causing base I I3 to be rotated about its axis I I4 in the proper direction to cause the moving strip to be restored to the proper direction of travel. To this end, a unitary electric motor and gear box assembly I33 is mounted on stationary frame member H6 and provides a driving connection between the motor and a pair of guide screws I34 which are journaled in frame IIB. Screws I34 are threaded into spaced frame portions I35 and I36 of base II3, see Figure 6; the arrangement being such that the rotation of the motor (which is reversible) will effect synchronous rotation of screws I34 and thereby cause the left hand endof base II3 (Figures 4 and 5) to be raised or lowered depending upon the direction of rotation, effecting rocking movement of the entire assembly about pivot I I4 as an axis.

As shown in Figs. 6 and 7, in order to prevent binding between the screws I34 and frame portions I35 and I36 when the frame rocks about pivot II4, the screws are threaded through a plate I35a having a concave bottom surface fitting on a convex surface in frame portion I35, and are likewise threaded through a plate I360 having a convex top surface fitting a concave surface in frame portion I36. A clearance is provided between the screws I34 and the frame portions I35 and I36. Accordingly, when the support II3 rocks about pivot II4, the misalignment on screws I34 is taken care of by slipping of the plates I35a and I36a on the convex and concave surfaces of frame portions I35 and I36 respectively.

The circuit for motor I33 is automaticaly controlled by a rod I38 that carries a lefthand finger in the form of a plate I39 and a right hand finger in the form of a plate I40. Rod I38 is mounted for reciprocating movement parallel to the axes of the rolls in base I I3 and fingers I39 and I40 are adapted to be contacted by the side edges of the strip material in its passage through the rolls. Contact of the strip with fingers I39 will effect a movement of rod I38 to the left, whereas contact of the strip with finger I40 will eifect a right hand movement of the rod. The movements of the rod just described are employed to close the circuits in a limit switch assembly designated at I42, see Figures 4 and 6, into whose housing the rod I38 projects.

rod I38 and its housing is provided with a pin I43. A bell crank lever I44 is pivoted on base H3 at I45;and is provided witha bifurcated end I46 which embraces this pin I43 and a bifurcated end I41 which embraces a pin I48 carried by stationary frame member H6. The arrangement of the parts is such that downward movement of the rocking base I I3 will effect clockwise rocking movement of the lever I44 and move switch I42 to the right (Figure 4). Upward movement of base II3 within frame 6 will effect counter clockwise movement of lever I44 and movement of switch I42 to the left.

Summarizing the operation of the centering mechanism and assuming that the strip is being fed through the apparatus and is traveling too far to the right, its edge contacts finger I40 and moves rod I38 to the right, which in turn causes switch unit I42 to energize motor I33 in a direction to cause screws I34 to effect a downward movement of base II3. This movement of base II3 rotates lever I44 in a clockwise direction, causing switch unit I42 to be moved to the right until it reaches a point where it will break the circuit and shut down the motor. The purpose of movably mounting the limit switch I42 or other detecting device is to prevent overcorrection of the roll position, which would result in an oscillating motion being imparted to the straight portion of the strip after the cambered part had passed.

With more particular reference to Figure 8, a suitable circuit is shown embodying the reversible motor I33 and its controlling unit or limit switch indicated within rectangle I42; the armature and field of the motor are connected independently, as illustrated, across a line which carries direct current under proper voltage. The armature has reversible connections which determine its direction of rotation, depending upon the positions of a plurality of automatic switches R82, R83, Lsz and LS3. When the R switches are closed and the L switches are open, the armature turns in one direction; and upon closure of the L switches and opening of the "RP switches the direction of rotation is reversed. The R switches are operably connected for closure simultaneously with a switch RS1 when a coil Re is energized; and the L switches likewise are operably connected with a switch Lsi and are actuated by a coil Lc. Normally, that is, when the strip is running true, all of the switches and the limit switch I42 occupy the positions illustrated in Fig. 8.

The switch assembly I42 embodies a pair of double contact switches R and L comprising spaced pairs of contacts cooperating, respectively, with contact disks Rd and Ld which are carried within the switch assembly by, and shiftable axially with, the strip-actuated rod I38. The disks, however, are movable slightly in both directions along the rod against any suitable yielding means. such as compression springs I4I that are designed to normally urge the disks to definite positions relative to the rod, such positions being illustrated in Fig. 8.

The contact elements of the switches R and L are associated with the respective coils, Re and Lo, in such a manner that, in the position illustrated in Fig. 8, both coils are short-circuited and hence de-energized and the motor I33 is stationary; that in one direction of movement of the rod I38 (righthand), th coil Rc is ener base H3.

gized while the coil Lc remains shorted; and that in the other direction of movement of rod I38 (lefthand), the coil Rc becomes short-circulted and the coil Lc energized. Suitable current adjusting resistors RT and LT are interposed in the respective branches of the circuit.

Assuming that the rod I38 has been moved to the right through contact of the strip with finger I40, this will open the normally closed contacts and close the normally open contacts of switch R, thus energizing the motor in such a way as to drive the lefthand end (Figures 4 and 5) of base H3 downwardly on screws I34. Downward movement of the left portion of base H3 causes the limit switch unit I42 to be shifted to the right through the action of lever I and this will reopen the normally open contacts and reclose the normally closed contacts of the switch R. Reclosing the normally closed contacts will short-circuit the coil RC, thus de-energizing the coil and stopping the motor. Should the strip continue to shift to the right after the cycle of operations just described has been completed, the entire sequence of action will be repeated until the roll assembly has been lowered sufliciently to counteract the misaligning tendency of the camber of the strip.

When the cambered part of the strip has passed the squeegee roll assembly, the strip will feed to the left because the left hand end of the roll assembly is lowered as the result of the operation previously described. The strip will then engage finger I39 and carry rod I38 to the left. This will energize the motor by means of the limit switch unit L in a manner similar to that previously described except that the direction of the rotation of the motor will be reversed so as to effect upward movement of the lefthand end of base H3. This in turn will cause the limit switch unit I42 to be shifted to the left to stop the motor and arrest upward movement of the Should the strip continue to feed to the left, the sequence of operations will be repeated until the sidewise motion of the strip has been corrected. The manner of correction for movement of the strip to the left of its true center position is thought to be obvious in view of the above, and hence is not explained in detail. It is therefore apparent that the feed of the strip is automatically and accurately controlled at all times without overcorrection and without feeding the strip past a center position.

The invention may be carried out by other suitrhle and/or modified apparatus. For examle, the squeegee roll support has been illustrated Lild described as being mounted for rocking movement about a horizontal axis, but, if desired, it may be mounted for rocking movement about a vertical axis and the actuating means and control mechanism therefor modified to effect proper centering of the strip. Also, rod

iiiii and fingers I39 and M0 have been illustrated as being carried by the squeegee roll support H3, but, if desired they may be so disposed as to cooperate with the strip in a region other than ad- Jacent the squeegee roll assembly. For instance, they may be located adiacent one of the contact rolls if desired, without departing from the spirit of my invention so long as movements of the squeegee roll support are suitably correlated therewith to effect a control similar to that effected by the'mechanism of Figures 4 to 8, inclusive.

I claim:

1. In a combined squeegee and guide roll assembly for propelling strip material through an electrotreating tank, a support, a pair of parallel rolls mounted for rotation on said support, means mounting said support for rocking movement, power means for actuating said support, finger means mounted adjacent the path of travel of the strip material and adapted to be contacted by a side edge thereof for causing said power means to actuate said support in one direction, and a second finger means cooperating with the other side edge of the strip material for effecting opposite movement of said support, and mechanism actuated in accordance with movement of said support for causing said power means to brin said support to rest after the latter has been moved a predetermined distance by said power means in response to actuation by either of said fingers.

2. In an apparatus as defined in claim 1, electromagnetic means controlled by said finger means and actuating said power means.

3. In an apparatus for electrotreating strip material, a plurality of rolls for guiding the strip through the apparatus, at least one of said rolls being journaled in a rockable frame mounted on a stationary support, means for rocking said frame about an axis perpendicular to the axis of said one roll, control means automatically actuated by lateral movement of the strip for operating said rocking means to rock said frame and maintain said strip properly centered relative to said one roll as said strip passes thereover, and means actuated by said rocking movement of the frame for stopping said rocking means when said rocking frame has moved a; predetermined amount.

4. In an apparatus for electrotreating strip material having an electrolytic tank within which the strip is adapted to be electrotreated, a plurality of rolls for guiding the strip through the tank, at least one of said rolls being journaled in a rockable frame mounted on a stationary support, means for rocking said frame about an axis perpendicular to the axis of said one roll, actuating means on opposite sides of the path of said strip and adapted to be contacted by the side edges of said strip for operating the rocking means to rock said frame for raising the end of the roll at the side of the strip being contacted, and control means actuated by a predetermined amount of rocking movement of the frame in either direction for stopping operation of said rocking means.

JOHN S. NACHTMAN.

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