US2697690A

US2697690A - Electroplating rack

Info

Publication number: US2697690A
Application number: US66611A
Authority: US
Inventors: Jr Austin H Beebe
Original assignee: Federal Mogul LLC
Current assignee: Federal Mogul LLC
Priority date: 1948-12-22
Filing date: 1948-12-22
Publication date: 1954-12-21
Anticipated expiration: 1971-12-21

Description

Dec? 1954 A. H. BEEBE, JR

ELECTROPLATING RACK 2 Sheets-Sheet 1 Filed Dec. 22. 1948 a F M R. J m W m w w 9 5 k m @w J -il 1 ll q Q 1954 A. H. BEEBE, JR

ELECTROPLATING RACK 2 Sheets-Sheet 2 Filed Dec. 22. 1948 INVENTOR. flasZZ/I /7( 5 6 a, -77.

United States Patent ELEcTnorLA'riNG RACK Austin H. Beebe, .lr., Ann Arbor, Mich., assignor to Federal-Mogul Corporation, Detroit, Mich., a corporation of Michigan Application December 22, 1948, Serial No. 66,611

4 Claims. (Cl. 204-297) This invention relates generally to the art of plating and more particularly to an improved method and apparatus for the plating of precision sleeve bearings and other similar objects and is particularly adapted, among other uses, to the plating of a lining on semi-cylindrical bearings which may be used individually or in pairs.

In the plating of precision bearings it is desirable that the plated layer be of uniform thickness and composition over the entire lining surface of the bearing and that there be no metal plated onto the back surface of the bearings. It has been the usual practice in the previous plating of such bearings to use internal anodes in the plating rack. The use of such internal anodes has numerous disadvantages. For example, the possible range of anode current densities which may be used is strictly limited because of the size of the bearings and the necessity for a rigid anode structure. Because the distance between the anode and bearings is small a slight out-of-roundness of the anode can cause considerable variation in thickness and composition of the electroplated layer at different areas on the same bearing. Similarly, if the anode is located slightly eccentric with respect to the bearings considerable variation in the thickness and composition of the layer may result. In many cases the anode contributes solid particles to the plating bath which particles can easily migrate to the bearings and cause a rough electroplate. This feature frequently necessitates the use of much lower cathode current densities than might otherwise be desired. Bagging of internal anodes is somewhat difficult and in some cases impossible. The cost of manufacture, installation and replacement of internal anodes is considerable. Many racks containing internal anodes cause difficulty because of frequently developed short circuits within the racks. Electrolytic cleaning of the hearings in racks containing permanent internal plating anodes frequently is not feasible.

Therefore it is an object of the present invention to provide a new rack for plating the lining surfaces of bearings for which the anode is entirely external and separate from the rack thereby eliminating the aforementioned difliculties.

A further object is to provide a rack for electroplating bearing linings in which the anode current densities may be widely varied from less than to greater than the cathode current density.

A still further object is to provide a rack in which the bearings may be electroplated in successively different baths without having to change the anode or anodes in the rack.

A further object is to provide a rack for electrodepositing alloy bearing linings with which a plurality of anodes having independently controlled anode current densities can be used.

A further object is to provide a rack for electroplating of bearing linings in which the anodes may be easily and conveniently bagged.

Still another object is to provide a rack for the electroplating of bearing linings in which process the bearings can be separated from the anodes in the plating tank by means of a porous diaphragm.

A further object is to provide a rack in which bearings can be electroplated with a smooth deposit of uniform thickness at high cathode current densities.

A further object is to provide a rack in which bearings can be electroplated with a deposit which does not require any subsequent machining.

A still further object is to provide a rack for electr0- depositing alloy bearing linings in which the chemical composition of the electrodeposit is uniform.

An additional object is to provide a rack for the electroplating of bearing linings in which process no significant thickness of metal is plated onto the back or parting surfaces of the bearings.

Other objects will be apparent from the specification, the appended claims and the drawings in which drawm s:

Figure 1 is a plan view with certain parts broken away of an electroplating rack embodying the invention;

Fig. 2 is a view in central vertical section of the rack shown in Fig. 1;

Fig. 3 is a view taken substantially along the line 3-4: of Fig. 1;

Fig. 4 is a view similar to Fig. 2 showing a modified form of the invention;

Fig. 5 is a view similar to Figs. 2 and 4 but showing a still modified form of the invention;

Fig. 6 is a view taken substantially along the line 66 of Fig. 5; and

Fig. 7 is a broken view similar to that of Fig. 1 showing the form of the invention shown in Fig. 5.

Referring to the drawings by characters of reference, the numeral 1 indicates generally an electroplating rack which, as illustrated, is a substantially rectangular box having longitudinally extending

side walls

2 and 4, upper and lower end walls 6 and 8, a hinged cover 10, and a side wall 12. The end walls 6 and 8 are provided with extending

portions

14 and 16 respectively which are apertured to receive hinge pins 18 carried by downwardly extending tabs 19 of the cover 10 whereby the cover 10 may be swung about the pins 18 to obtain access to the interior of the rack 1 for loading of the bearing halves 20 which are arranged in edge-to-edge relation longitudinally of the rack 1 with their concave surfaces tacing a longitudinally extending slot 21 opening through the wall 12. The upper edge surfaces of the

walls

2, 4, 6 and 8 are provided with a groove 22 in which is positioned a gasket 23 so that when the cover 10 is held in place by the retaining nuts 24, the rack will be fluid tight except for the slot 21 and the aperture through which the cathode hook, to be described below, extends. The

walls

2, 4, 6, 8, 10 and 12 are preferably made of plastic or other material which is impervious to liquid which might be encountered in the plating tank (not shown) with which the rack is adapted to cooperate and a nonconductor of electricity. The wall 12 may be suitably permanently secured to the

walls

2, 4, 6 and 8 in a fluid tight manner since it is unnecessary to remove this wall from the side and end walls.

The central longitudinally extending slot 21, as shown in Fig. 3, is provided with a throat 26 adjacent the inner surface of the wall 12. The slot 21 is further provided with outwardly flaring side walls 28 which flare outwardly from the throat 26 toward the outer surface of the wall 12. As shown in dot-dash lines the bearing halves 20 are arranged in edge-to-edge relation centrally of the throat 26 by means of work guides 32 and 34 which may be suitably held on the inner surface of the wall 12 as by means of pins 36. A movable wall 38 closely fits the adjacent bearing 20 and is slidable longitudinally within the rack 1. The wall 38 closely fits against the wall 12 and is held in closely fitting relation by the wall 6. The wall 38 also holds the bearings 20 in closely stacked relation and against the end wall 8 whereby the plating current is substantially confined to the concave surface of the bearings 20. The wall 38 permits the rack to be used with bearings of varying width.

Springs

40 and 42 extend between the walls 8 and 38 and exert sufficient pressure on the wall 38 so that it will hold the bearings 20 tightly in edge-to-cdge relation to prevent the flow of plating current there'oetween. The

springs

40 and 42 are so spaced that they gvill lie along or beyond the outer surface of the bearings The guides 32 and 34 are provided with tapered end portions 43 which are engaged by the outer surface of slot 21. The work guides 32 and 34 are preferably so spaced that the bearings 20 must be slightly flexed when they are inserted therebetween whereby the guides will hold the end surfaces of the bearings 20 against the bottom wall 12 and plating current is substantially prevented from flowing to the convex surface of the bearings 20.

In each of the forms of the invention, this fit between the bearings 20 and the guides 32 and 34 holds the bearing halves in place during the plating process; however in some of the forms as, for example, in the arrangement shown in Fig. 1, the bearings are-additionally urged toward engagement with the inner surface of the bottom wall 12 by means of current conducting springs 44 which are arranged at spaced positions along the underside of the cover and in such relation relative to the bearings that each bearing is engaged by at least a portion of one of the current conducting springs 44.

The rack 1 is provided with a cathode bar 46 which extends longitudinally of the rack substantially fully throughout its length and substantially centrally between the

side walls

2 and 4 and extends outwardly above the end wall 6 through an aperture therein whereby a hook portion 48 of the bar 46 may be hooked upon the usual cathode bus which is located above the plating tank. Aseries of cap screws 50 extend through the bus 46 with their head portions in engagement therewith and their inner end portions threadedly engaged in blind screwthreaded holes in the cover 10 whereby the current springs 44 are securely clamped between the cathode bus 46 and the inner surface of the cover 10 for mechanical support with the rack 1 and electrical connection with hook 48.

In use the rack 1 is suspended in the plating tank on the usual cathode bus by means of the hook'48, and the level of the solution is adjusted so that the solution completely immerses the uppermost one of the bearings 20. Preferably the liquid level approaches the mid-point of the movable wall 38.

The rack 1 may have any-desired position with respect to the anode 52 with which it is to be associated and the anode 52 may be of any desired shape or configuration as desired for the particular plating result desired. Preferably the anode 52 is of sufficient length so that .it extends within the solution for the entire depth of the opening-of the elongated longitudinally extending slot 26 although under some instances this may not be desired. If desired a plurality of anodes 52 may be used either of the same or different materials. When anodes of different materials are used, an alloy depending upon the anodes used may be plated on the bearings 20.

In operation current flows from the anode or anodes 52 through the-elongated throat 26 which is at substantially the center of curvature of the bearings 20 whereby the distance from the throat 26 to any point on the inner surface of the bearings 20 is substantially the same so that there is an equal tendency for the plating material to deposit out evenly on the inner surface of the bearings 20. It will be obvious from the foregoing that this rack may be used with any desired anode configuration having any desired area whereby the relative current densities of the anode or anodes 52 and of the interior surface of the bearing being plated may be maintained at any desired ratio from an anode which has a surface less than to an anode which has a surface greater than the surface to be plated and also it likewise follows that the current density of the anode may be made less than, equal to, or greater than the currentdensity of the work being plated.

In the form of the invention shown in Fig. 4, the springs 44 are replaced by a single longitudinally extending spring60 carried by the cover 10a and which is connected to the cathode bus by means-of a conductor 72 attached to the bolt 74 which secures the spring 60 to the cover 10a. In this form it will be apparent that the bearings 20 are held against the wall 12a by the clamping etfect of the guides and any force exerted by the longitudinal spring extending between the walls 8a and 32a. Preferably insulation 62 covers the bolt 64 to prevent plating thereof. The rack 1a may be held in the plating tank by any suitable means such as the hook 66. In this modification the cathode current flows end-to-end along the stack of bearing halves 20 and then outwardly through the contact spring 60 and conductor 68 to the cathode. In some instances the end-to-end flow may be more desirable than a return directly to the cathode by means of current conducting springs :arranged in contact with each of the bearing halves. In the racks 1a of Fig. 4 like that of rack 1, the bottom wall 12a is provided with the longitudinally extending slot similar to slot 21 having the throat 26 and the tapered side walls 28 whereby the plating current is equally distributed to the inside on the bearing halves contained Within each of the racks. The operation of the rack 1a will be evident from the description of operation given with respect to the rack 1.

In the modification shown in Figs. 5, -6 and 7, the rack 1b is in the form of a substantially rectangular box .having longitudinally extending side walls 2b and 4b, upper and lower end walls 6b and 8b and a hinged cover 10b. In this form a hinged pin 18b which preferably is of a material having a relatively low resistance to the conductivity of electricity extends across the rack 1b between the side walls 2b and 4b and is secured at either end to a U-shaped cathode bus strap 70 which telescopes over the upper end of the rack 1b and which is provided at its midpoint with a hook-shaped current-conducting cathode member 72 adapted to "be hooked onto-a cathode bus 73 which may extend substantially horizontally over the plating tank (not shown). A cathode bus 46b is carried on the inner surface of the cover and is secured thereto by means of screws 74 extending into blind screw-threaded holes in the cover 10b. The upper end of the cathode bus 46b is connected to the hinge pin 18b by means of spring current-conducting members 76 rigidly secured -to the bus 46b and having sliding contact with the pin 18b.

In this form of the invention, there is shown another form of current-conducting spring 78 which is received within an aperture 79 in the cathode bus 46b and which is held therein by transversely extending pins 82. It will be apparent however that if desired the same type of springs 44, as shown in Figs. 1 and 2, could be utilized. The springs 78 not only provide a direct current-conducting path from each bearing 20 to the bus 46b but also serve as do the springs 44 for resiliently urging the bearings against the inner surface of the wall 12b to prevent current flow from the anode to the back surface of the bearings.

The cover member 10b is provided with transversely extendingfins or protuberances 80 which when the cover 10b is in closed position may engage the upper surface of the guides 34b and 32b if desired and which may closely fit within the adjacent side walls '2b and 4b if desired. The fins 80 are apertured adjacent the upper end of the cover 1012 to receive the hinge pins 18b whereby the cover is journaled for opening and closing movement. The end wall 6b is provided with an aperture 83 through which a pin or thrust rod 84 threadedly secured :to the movable wall 38b extends. The-outer end of the pin 84 extends through an aperture in a lever 86 and a nut '88 is threaded thereon to limit relative movement of the lever 86 and rod 84 in one direction. A spring 89 'arranged concentrically of the rod 84 seats at one and against the wall 38b and atits-other end against-the wall 6b. The lever 86 is pivotally connected 'to a pin -90 threadedly carried by'the wall 6b and extends outwardly of the edge of the end wall 6b oppositetothe edge thereof adjacent the wall 12b. Upon opening of the cover "1012,

the outer surface thereof engages a block 92 carried by the lever 86 and rotates'the lever in 'a clockwise direction from the position shown in Fig. 5 whereby the'lever engages the nut 88 and moves the rod 84 outwardly of the rack 1b thereon movingthe movable 'wall 38b away from its engaging position with the bearings 20 against the force of the spring 89.

In this form the cover 101) is held closed by means of a suitable cam '94 operated by cam handle 96. The cam 94 engages the upper surface of a locking member '98 carr ed on the upper surfaceof the cover 10b. The cam 15 plvotally carried by spaced links which in turn are p1votally secured on either side of a pin 102 threadedly secured in a blind hole to the end'wall 8b.

In order that the plating liquid will drain from the rack, the end wall 8b thereof is provided with a pair 'of apertures 104 therethrough opening into the space in the rack along the back surface of the bearings 20. Pieces of tubular conduit, such as rubber hose 106, are 'wedgedly carried in the apertures 104 and extend outwardly therefrom. The length of the hose with :respect to-the internal diameter thereof should be sufficient so that the reslstance to current flow through the column of liquid contained in the hose is sufficiently great so that substantially no current flows from the anode through the column of liquid in the hoses 104 to cause plating on the rear surfaces of the bearings 20. Test results show that hoses about one foot long or longer and of one-quarter inch internal diameter are satisfactory for the purpose. Since most bearings 20 are provided with oil holes and which oil holes are already in the bearings at the time they are plated, a great deal of liquid will accumulate back of the bearings 20 during the plating operation and the hoses permit rapid draining of this liquid when the rack is removed from the tank. It will be apparent that such hoses 104 are equally applicable to any of the shown forms of racks even though they are specifically shown only on the form shown in Figs. 5, 6, and 7. The operation of the rack 117 will be evident from the description of operation given with respect to the rack 1.

What is claimed and is desired to be secured by United States Letters Patent is as follows:

1. An electroplating rack for concave surfaces of workpieces comprising a substantially imperforate but not necessarily fluid-tight casing having a longitudinal aperture extending through one wall thereof against which such workpieces are held with their concave surfaces facing said aperture, means providing a throat for said aperture adjacent the inner surface of said one wall substantially at the center of curvature of such surfaces, the remainder of the walls of said aperture being outwardly tapering to provide an opening in the outer surface of said one wall which is several times the dimension of said throat whereby the rate of plating through said aperture is substantially increased.

2. An electroplating rack comprising a boxlike member having an open side, a cover for said side, said member having a wall opposite to said side, said wall having a longitudinally extending aperture extending completely therethrough, guide means in said member for locating work to be plated with respect to said aperture, a current-conducting means carried on said cover, a series of current-conducting resilient members carried by said cover and adapted to engage said Work upon closure of said cover, means for hingedly securing said cover to said boxlike member and including a current-conducting hinge pin, a resilient current-conducting member carried by said cover member in electrical contact with said conducting means, said conducting member having a sliding contact with said pin, and cathode hook means rigidly secured to said boxlike member in rigid electrical contact with said pin, said hook means being adapted to support said boxlike member in a plating tank.

3. An electroplating rack comprising, a bottom wall, spaced side walls, an end wall, a cover adapted to cooperate with said walls to provide a boxlike member, means hingedly securing said cover to one of said walls, a movable abutment wall movable toward and away from said end wall within said member adapted to engage a concave workpiece therein, means normally urging said abutment against such workpiece, said bottom wall having an elongated opening therethrough extending from a point adjacent said abutment substantially to said end wall, a lever fulcrumed on said member and having a portion engaged by said cover upon opening movement thereof for rotating said lever about said fulcrum in one direction, and means operatively connecting said lever and said abutment wall whereby rotation of said lever moves said wall in one direction against said normally urging means to release such workpieces.

4. In an electroplating rack for plating a stack of bearing sleeve halves stacked in edge-to-edge relation, a substantially imperforate but not necessarily fluid-tight housing for such sleeve halves having a wall against which such sleeves are to be placed, said wall being provided with an elongated aperture extending longitudinally thereof and at a distance equal to the length of said wall against which such sleeves are to be placed, the width of said aperture being a minor fraction of the diameter of such halves, means carried by said housing and holding such stack with the end portions of such halves firmly against said housing with such end portions equally spaced on opposite sides of said aperture whereby the distances from said aperture to all points on such concave surfaces are substantially equal, the side walls of said aperture through the external surface of said housing wall being ilared outwardly, such flare being of such a magnitude as to provide an aperture width at the outer surface of said housing wall which is several times the width at said inner surface whereby to secure a substantially increased rate of plating of such concave surfaces.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 718,249 Haas Jan. 13, 1903 1,181,613 Rich May 2, 1916 1,519,572 Wolf Dec. 16, 1924 1,594,509 Rosenqvist Aug. 3, 1926 1,861,446 Maag June 7, 1932 2,073,679 Brown et a1 Mar. 16, 1937 2,316,609 Miner Apr. 13, 1943 2,362,228 Wright Nov. 7, 1944 2,401,415 Duggan June 4, 1946 2,500,205 Schaefer Mar. 14, 1950 2,500,206 Schaefer et al Mar. 14, 1950 FOREIGN PATENTS Number Country Date 712,505 France July 21, 1931