US2643225A - Electroplating rack - Google Patents

Description

June 23, 1953 H. F. JONES ErAL ELECTROPLATING RACK Filed Jan. 19. 1949 2 Sheets-Sheet l www? m W ff F w. F m @d Takt H. F. JONES ETAL ELECTROPLATING RACK June 23, 1953 2 Sheets-Sheet 2 Filed Jan. 19, 1949 5.3. R m .wa F m. m

Patented June 23, 1953 ELECTROPLATING RACK Hugh F. Jones and Hedley R. Colby, Greenville,

Mich., assignors to Federal Mogul Corporation, Detroit, Mich., a corporation of Michigan Application January 19, 1949, seriaiNo. 71,714

2 Claims.

This invention relates to the art of electroplating and, in particular, refers to an improved rack for use in the plating of hollow objects such as cylinders, bearing elements and the like.

In the electroplating of hollow members such as cylinder liners, bearings, and the like it is often desired to deposit the plating material on only one surface of the member. Inasmuch as the entire member is submerged in the electrolyte, it has been necessary heretofore to employ stop-01T coatings or other means for preventing contact with the electrolyte when selective plating of this nature was attempted. Depending upon the means employed, these expedients have either required additional steps in the processing of the member or inflexible and sensitive plating apparatus both of which contribute to the expense of plating without producing reliably satisfactory results.

It is thus an object of the present invention to provide a relatively simple and inexpensive rack for selectively plating hollow members which is economical of manufacture and easy to use but, nevertheless, produces dependable results.

Another object is to provide a rack of the type described which is capable of adjustment to accommodate various size hollow members.

A particular object is to provide a rack which will plate the inner and not the outer surface of hollow members.

The means whereby these and other objects of the invention are accomplished will be described in conjunction with the accompanying drawings wherein:

Figure 1 is a view in central vertical section through the improved plating apparatus;

'y Fig. 2 is a view in partial side elevation taken from the right of Fig. l;

Fig. 3 is a View taken substantially along the line 3-3 of Fig. 1;

Fig. 4 is a View taken substantially along the line 4-4 of Fig. l and Fig. 5 is a View taken substantially along the line 5-5 of Fig. l.

As best shown in Fig. 1, the improved plating fixture has a frame, designated generally by the reference numeral I, which is preferably formed by laterally spaced, longitudinal hanger straps 3 and 5 which are xedly joined at their upper ends by the transverse beam 'I. A longitudinal hanger hook 9 is alixed by welding or other suitable means to the beam 'I and has its upper end II formed into a hook or other suitable shape whereby the frame I may be suspended on the current carrying cathode bus bar C. The members comprising the frame I are composed of current conducting material, such as stainless steel, so that the hanger straps 3 and 5 function additionally as electrodes.

Preferably, an anode I3 is insulatingly carried by the beam 'I of frame I by means of through bolt or rod I4 extending through a central longitudinally extending aperture I5 of the anode I3. A tapered bushing I6 which also serves as a nut is threaded to the lower end of the rod I4 and positions the anode I3 relative to the rod I4. The rod I4 extends upwardly through a central aperture in an insulating bushing II held within an aperture I3 in the beam l. The upper end of the rod I4 extends upwardly of the bushing I'I and receives a nut I9 which acts to clamp the rod I4 and electrode I3 to the bushing Il. An anode conductor strap 2| is clamped between the bushing II and the nut I9 in electrical contact with the rod I4.

The means required to adapt the strap 2I for connection to the anode bus A depends upon the location of said bus relative to the cathode bus C. When it is spaced below the bus C, as shown, this means may include a block 25 of electrical insulating material, such as Micarta, having a central slot 21 of greater depth than the thickness of the hanger hook or cathode bar 9 in the bottom of which said hook is seated. Screws 29 may be used to fasten the block 25 to the hook 9. A spring type clip 3| adapted forl quick connection to the bus A is mounted on the face of the block 25 by means of screws 33 which serve as conductors and pass through the block and engage the strap 2 I. Y The frame I which has been described thus includes side members 3 and 5 which are also electrodes connected to bus C. It also carries an anode I3 which is adapted for connection to a separate bus A and thus comprises an electrode for coaction with the electrodes 3 and 5. In accordance with this invention, hollow objects to be plated, which may be a stack of bearing elements, are mounted on the frame I so that the electrode I3 is within the bore thereof and the electrodes 3 and 5 are located outside of the object. l

The support means, designated generally by the reference numeral 35, for mounting the objects in this manner includes longitudinally spaced, lateral platelike members or heads 3l and 39 which are adapted to each engage opposite ends of the objects to be plated so that said objects are longitudinally disposed between the members. This assembly of members 3l and 39 and the object to be plated ls removable from the frame I and is adapted for rapid and simple mounting thereon. For this purpose the outer ends of the lower member 31 have lateral grooves 4I on the underside thereof which rest upon the upper surfaces of inturned flanges or shoulders 45 formed on the lower ends of the straps 3 and 5. By this means, in .conjunction with-theforce of gravity, the support lmeans 35 and object are attached to the frame I. They may be disconnected and removed therefrom by lifting them until the edges of the groove 4I clear .the fianges 45, rotating the assembly relative to the frame I, and then lowering the assemblyof support-.means and object from the frame.

Suitable means are provided to properly Aguide the movements of the support means 35 4in assembly and disassembly with the frame I. The electrode I3 may be conveniently employed `as a guide or locating bar for this purpose. In order Atoreceive it, the .heads 31 and r39 .are provided with guide bushings 41 and 4.9, respectively. rhese bushings are mounted in larger bushings 5I and 53, respectively, which are formed of suitable insulating material, suchas Micarta, and are secured in suitable apertures inthe members 31and 39. It `will `thus `be ,recognized that Ythe electrode I3 has no -electrical connection with the support means 35 and yet serves to guide longitudinal and rotary motion thereof relative -to -the yframe I, the tapered end I6 Aacting to facilitate initial alignment upon assembly. YIt is desirable upon Vsubmersion of the :fixture `to have :electrolyte lrcontact the .in-

terior surface of the hollow obiectmounted between the members :31 Aand -V39, :as well as the-exterior, hence the bushings 5I and .53 are pro vided with a plurality of longitudinal passages 55 topermit flow olf-electrolyte through the 0bject and support means 35 and .to permit ciryculation `thereof during the plating operation. Also the apertures 5.5 of the bushing 53 permit the escape of any gases formed during plating.

The support means .35 .may .be yespecially adapted to hold generally lcylindrically-shaped y hollow articles which may be sleeves or bearing elements D illustrated in the drawings. For this purpose, longitudinal, diametrically opposed, inwardly opening sangle bars 51 vand 59 are affixed to the underside'of the plate v39. In Order to make this connection laterally .adjustable .to accommodate sleeves D of various diameters, the jbars .and y59 have laterally extending ybase portions :6I -which may be integral `therewith or preferably they may be blocks secured thereto by `welding or .other suitable means ythereby permitting the use of standard angle iron for the bars-.51 and E9. Thebase portions 6I .are provided with `slots `53. yScrews 65 extend upwardly through the slots B3 .and engage suitable ythreaded `apertures 61 in the member 39 whereby the bars 51 vand 59 are adjustable .to provide the desired lateral spacing therebetween for reception of different sized objects. Preferably the ibars 51 `and 59 are adjusted .s0 that they are equidistant from the longitudinal axis of the apertured bushings 5I and 53 whereby the bars 5'! and 59 will center the cylindrical objects and in thecase of the split sleeves D will clamp them togetherto form, in effect, -a hollow article.

A pair of additional angle bars .6,9 similar n construction to the bars I51 .and 59 but much shorter in length are adapted for laterally adjustable attachment to the lower member 31 vby Cil lthe headers 31 and 39 whereby the means 35 will accommodate varying heights of stacked ar- Iticles to be plated will to a large extent be controlled .by .the length of the bars 69. Preferably vthe bars G9 are relatively positioned to pro- -vide a frictional 'telescopic fit with the bars 51 :and 159. If :.des'ired, detent means may also be Vprovided 4to yincrease thel friction of the telescopic connection,

The upper end surfaces of the bars 59 are beveled :as at 14 to provide for an easy assembly of the support means 35 since any outward aringl of the .lower endportions .of the Ybars 5:1 -and 55 will be corrected-,by engagement thereof with Athe beveled surfaces .14 which will .cam .these end portions into alignment. The supporting means l35.50 assembled separate and -apart from the :frame I may be easily handledasa unit-and inserted into the frame YI by merely sliding the unit on the anode .I.3 which .is .received within the .apertured bushings .5I .and 53. The means 35 is slid over the anode .I3 until vthe lower head clears the flanges 45 after which Vthe means .35 is rotated Yand slid outwardly .until .the recesses 4I engage the flanges 45. The frame I and means 3 5 so assembled ,may .then be placed -in the ,plating bath. When vso assembled .the .restricted .area .contact -vbetween .the iianges t5 and the head 31 provides .a vvoltage .drop therebetween by which .the` straps :i .and `5 are maintained at a more negative potential than the articles to be lplated wherebyany .ions will tend to deposit on the straps 3 and5 rather than on the backs ofthe articles .to beplated.

A plating rack so constructed may :be used in many Vdifferent .electrolytic solutions as well `as .with .workpieces or.articles .to be plated of lmany different metals, it `merely .being necessary to provide enough `voltage drop between the articles and the .straps so that the 4ions `will tend to deposit on the straps rather vthan the articles. It has also been found that under-certain circumstances the Vcathode .connection may vbe made Y directly from the articles Yor vany of the metal `portions kof the removable article sup'- porting portion of the rack and undesirable plating will not occur on .the outside of the articles and Yunder .certain circumstances the straps 3 and .5 may ieven be entirely electrically isolated from the electrical `plating circuit. As an illustration yof these just-.named circumstances, if the straps 3 and 5 are of stainless steel, .the backor outersurfacesof thearticles Ibeing plated are of carbon steel and the electrolytic acid is an acid .iiuoroborata Yfor example, HBM, then the cathode return conductor may be connected at -any point Yto .the movable rack portion or to the vrear or outer surfaces of the articles and the stainless steel straps 3 and 5 may be electrically 4isolated vfrcmthe direct plating circuit. This operation `as far as we have been ,able to explain it stems from the inherent .action of the stainless steel with the electrolyte which renders thestraps 3 and 5 negative with respect tothe electrolyte.

We have ,found that when a rack such as the one illustrated is used to plate an alloy of an proximately 90% lead and 10% tin on bearings from an electrolyte comprising Pb BF4 2 and Sn(BF4)2 in the ratio 0f about 9 to 1 in an acid fluoroborate solution onto bearings having a three and one-eighth inch outside diameter of carbon steel that straps of stainless steel having a section dimension of one-quarter inch by one inch when positioned relative to each other as shown, and whether electrically connected directly in the plating current circuit or not, will prevent any substantial amount of plating on the outside of the bearings. If the plating current flows across the restricted area contacts and through the straps 3 and 5 better results are obtained and the rack is usable in a wider variety of electrolytes and for plating parts formed of a wider variety of metalsfihe relative areas of the straps and of the bearing backs is apparently not critical providing that the areas of the straps 3 and 5 are suflicient. If desired, a casing 'I5 of stainless steel having its inner surface uninsulated and its outer surface covu ered with an insulating material 17 such as rubber or the like may be used. This casing 75 may be held in place by bolts 8l. This increases the negatively charged area and further tends to draw the metal ions thereto away from the out= side surface of the bearings.

If desired, a casing 15 having an outer surface covered with insulating material 11 such as rubber or the like, may be used to surround the frame.

The manner in which objects are assembled and disassembled on the fixture has been explained above. After assembly the entire structure is submerged in the electrolyte to just beneath the hanger beam 1. The electrolyte is therefore in contact with the inner and Outer surfaces of the object and with the electrodes 3, 5, and I3.

Current from the anode bus A flows through the clip 3|, bolts 33, anode strap 2|, rod I4 and anode I3 to the electrolyte. Current ows through the electrolyte to the articles D, then to the rods 51, 59, 69 and therethrough to the head 37. Current ows from the head 31 to the flanges 45 of the straps 3 and 5 from. whence it flows through the beam 'I and hook 9 to the cathode bus C.

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

0'1945, pp. 17o to 172.

1. In a rack for electroplating hollow articles, a frame comprising an upper end element having a pair of spaced downwardly depending legs which are provided with inwardly projecting anges at their lower end portions, an upper and a lower end member positionable between said legs,`a first pair of angle bars carried by one of said end members and extending toward the other of said end members, and a pair of abutments carried by said other end member and clampingly engaging the extending end portions of said bars, said end members having a first dimension in a plane extending transversely of said legs and of a magnitude less than the distance between said flanges whereby said end members may be inserted longitudinally of the legs between said flanges into the space between said legs, said lower end member having a second dimension in said plane of a magnitude greater than the distance between said anges but less than the distance between said legs, said second dimension being aligned with said flanges whereby said lower end member seats on and is supported by said flanges.

2. The combination of claim l in which said frame comprises one electrode, a second electrode is carried by but electrically insulated from said frame and extends downwardly between said legs and in which said upper end member is apertured to receive said second electrode.

HUGH F. JONES. HEDLEY R. COLBY.

References Cited in the ille of this patent UNITED STATES PATENTS June 8, 1943.

Belke Plating Rack Manual, Belke Mfg. Co., Chicago 51, Ill., p. 20.

Transactions of the Electrochemical Society, vol. 86, 1944, pi. 433.

Metal Industry (New York). September 14,

Claims (1)

1. IN A RACK FOR ELECTROPLATING HOLLOW ARTICLES, A FRAME COMPRISING AN UPPER END ELEMENT HAVING A PAIR OF SPACED DOWNWARDLY DEPENDING LEGS WHICH ARE PROVIDED WITH INWARDLY PROJECTING FLANGES AT THEIR LOWER END PORTIONS, AND UPPER AND LOWER END MEMBER POSITIONABLE BETWEEN SAID LEGS, A FIRST PAIR OF ANGLE BARS CARRIED BY ONE OF SAID END MEMBERS AND EXTENDING TOWARD THE OTHER OF SAID END MEMBERS, AND A PAIR OF ABUTMENTS CARRIED BY SAID OTHER END MEMBER AND CLAMPINGLY ENGAGING THE EXTENDING END PORTIONS OF SAID BARS, SAID END MEMBERS HAVING A FIRST DIMENSION IN A PLANE EXTENDING TRANSVERSELY

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