US 3043767 A
Description (OCR text may contain errors)
July 10, 1962 A. E. TOBEY 3,043,767
ELECTROPLATING APPARATUS Filed May 12, 1959 .27 v FLEA jwqrm www United Sitates Patent O 3,043,767 ELECTROPLATING APPARATUS Alton E. Tobey, 2203 Mission, Santa Cruz, Calif. Filed May l2, 1959, Ser. No. 812,647 2 Claims. (Cl. 204-297) My invention relates, in general, to methods and apparatus for selectively plating pointed articles, and, more particularly, to methods and apparatus for applying metal plating to the pointed portions of nails, tacks, pins, spikes, etc., as well as to facilitate manufacture of rasping elements therefrom.
Ordinarily, small articles of the character described are electroplated by being disposed in a rotating drum cathode immersed in a plating bath. This method applies a more or less uniform platingover the entire surface of the plated article to improve the appearance or serve as a protection against corrosion. For certain purposes, however, pointed articles plated as described are not completely satisfactory or it is desirable 'that only the pointed portion-s be provided with a plating or a plating of a different metal than that of the head portions, especially when abrasive wear is to be minimized.
For example, tack-like elements are utilized as described in U.S. Patent No. 2,583,615, issued January 29, 1952, to myself, for producing rasp webs. The tacks are driven through metal strips so as to protrude through the opposite side and become aixed in this relation by the displaced metal bearing on the shank portion. Polished surfaces in the said bearing region promote early loosening of the tack Shanks. Moreover, I have found that hard chrome plating of the tip portions of the tacks or spikes greatly increases life of the rasps in abrasive service.
In accordance with my present invention, I provide an electroplating cathode assembly by means of which pointed articles of the character described may be suspended in an electroplating bath wherein a metal plating is seloc-tively applied to tip and adjacent shank portions thereof. Such cathode includes a fixture member adapted for rapid loading and is constructed to provide the selective plating action so as to provide economical operation and conservation of the plating metal bath.
Accordingly, it is an object of my invention to provide articles of the character described having end and tip portions selectively electroplated.
Another object of my invention is to provide methods and `apparatus for selectively electroplating metal upon tip and end portions of pointed articles such as nails, spikes, tacks, pins and the like.
Still another object of my invention is to provide methods and apparatus yfor selectively applying hard chrome plating to tip and end portions of pointed articles.
A further object of my invention is to provide an electroplating cathode assembly especially adapted to selectively apply hard chrome plating to tip and end portions of pointed articles in an electroplating bath.
The inventionv possesses 'other objects and features ofv advantage, some of which, with the foregoing, will be set yforth in the following description of the preferred form of the invention which is illustrated in the drawing accompanying and forming part of the specification. It is to be understood, however, that lvariations in the showing -made by the said drawing may be adopted within the scope of the invention as set forth in the claims.
With reference to said drawing:
FIGURE l is a plan view of the electroplating cathode assembly of the invention with the cover plate partially broken away to better illustrate the positioning xture element with some positioning perforations shown with tacks in place.
FAice FIGURE 2 is a cross-sectional view of the cathode assembly along the plane 2-2 of FIGURE l with the cat-hode structure` illustrated in operating position Within an 'electroplating bath.
FIGURE 3 is an enlarged view of a portion of YFIG- URE 2 better illustrating details of construction.
FIGURE 4 is a side view illustrating details of the latching mechanism of the assembly.
Basically, as illustrated in FIGURES 1 and 2 of the drawing the electroplating cathode assembly 10 of the inventionincludes a fixture plate 11 perforated to receive the pointed articles to be plated, a cover plate 12 removably affixed with a resilient spacer pad 13 'disposed therebetween.V This arrangement permits convenient insertion and retention of the articles in plate l1. The assembly 10 is constructed and arranged to shield selected areas of the articles'from the plating solutionas well as to preferentially direct deposition of the metal to the desired tip locations as described hereinafter.
As noted above, the invention may be utilized for selectively applying metal electroplating to tip portions of various elongated pointed metallic articles. The general type of article is exemplified by a particular type of tack 14 best seen in FIGURE 3 of the drawing as disposed in proper lposition in cathode 10 and corresponding to the tack or spike elements utilized in fabricating rasp webs as disclosed in my aforesaid patent. Such a tack 14 generally includes an elongated shank 16 usually round, a flat head 17 and a pointed tip 18 either conical or pyramidal in shape. Typical tacks 14 utilized in said rasp have a head of about 0.187 inch in diameter, a shank length equivalent to about 14 to 8 American gauge, e.g., 0.335 inch and a tip of about 0.110 inch long; however, it will be appreciated that the composition, physical properties, dimensions and proportions indicated can be varied to suit other purposes. The tacks 14 as utilized in manufacturing rasp webs are generally`of carbon or alloy steel, heat treated to produce about 30 to 40 degree Brinell hardness suitable for the indicated use.
Fixture member 11, of the cathode yassembly 10, here shown, is provided in the form of a rectangular plate of an electrical conductor metal such as copper or iron perforated with a plurality of receptacle perforations 19 arranged in rows. Perforations 19 are provided with a shoulder 21 creating a recessed area 2.2 in the upper face 23 of member 11 into which the heads17 of tacks 14 fit loosely to bear upon said shoulder 21. The lower portion of said perforations is counterbored or countersunk to be of ya larger diameter than the tack shank-s 16 which project downwardly therethrough. VThe areas 22 'are recessed toV a depth about equivalent to one half head 17 thickness (about 0.020 inch) so that the pad 13 bears effectively to retain heads 17 against shoulders 21 to establish positive electrical contact and alignment. The fixture member plate 11 is about i inch thickness for the specific tack length given above so that about one half of the tack projects beneath the lower face 24 thereof. The lower plate face 24 -adjacent to holes 19 is preferably countersunk with about a 45 bevel to a depth of about 1/2 the fixture plate thickness to expose additional shank portions when short length tacks 14 are to be proces-sed. Any undue tendency of undesired deposits to form near the juncture of tack shanks 16 and fixture plate 11 is largely eliminated by such counter-sunk areas or the counterbored equivalent noted above. The resilient pad 13 can be about 1% inch thickness of 40-60 durometer hardness rubber preferably chemically resistant synthetic.
The cover plate 12 is attached to the fixture plate 11 in a clamped detachable fashion as by the means best seen in FIGURES 2 and 4. As illustrated therein projecting lugs 26 with downwardly depending lips 27 are provided at one end and at each side of plate 11. The cover plate 12 is preferably made of metal such as copper, iron, etc., in a size suicient to cover iixture plate 11 with lug portions 23 extended outwardly over lugs 26. Snap latches 29 -are positioned so that a downwardly depending loop portion 31 thereof engages lug 26 whereupon handle 32 of latch 29' bearing upon lug 28 is depressed downwardly to a stable position. With such an arrangement the cover plate 12 causes pad 13 to be brought into effective bearing engagement with tack heads 17 firmly positioning the tacks in plate 11 and assuring good electrical contact between the tacks and the plate 1'1. An insulated electrical conductor 33 is attached to any convenient portion of fixture member 11 to supply electroplating current as described below.
It is desirable that appropriate surface portions of any of the cathode assembly components be treated to provide corrosion resistance and good electrical contact with the tacks. Portions of the assembly not exposed to the direct electroplating action such yas recesses 22, the upper face 23 of plate 11, lower face 34 of cover plate 12, peripheral walls of the holes 19, etc., may he so treated merely by electroplating a layer 36, the same metal to be employed with the tacks or another suitable metal may be so employed. For simplicity, all surfaces of the cathode assembly may be provided initially with such an elcctroplating layer 36.
As a feature which is essential to obtain the most advantageous results all outwardly disposed surfaces of the assembly which are exposed to direct and elfective electroplating potentials are provided with a tightly adherent insulating coating 37. lThe more critical areas which must be coated include the lower face 24, end, side and lugs 26 surfaces of fixture plate 111 and end, side, upper face, lugs 2S and latch 29 surfaces. Other areas which are not required to establish anelectrical contact may also be treated; however, in the less exposed areas lovervoltage generally provides ample lprotection to the plated areas. Vitreous enamels or adherent chemically resistant plastics or hard rubber may be applied by conventional techniques to provide such an insulating coating 37. Tygon, chemically resistant resin paints, epoxy or other types of plastic compositions, neoprene or chlorsulfonated polyethylene (Hypalon) rubbers and the like normally employed `in the 4art should be found satisfactory for the purpose. With the cathode assembly provided as described above, deposition of the electroplating is preferentiallydirected to tip portions of the tacks as discussed more fully hereinafter.
The lixture plate 11 may be loaded with tacks 14 either by hand or the plate 11 may be loaded mechanically, for example, by being utilized as the transfer plate as describedk lin my aforesaid patent. Moreover, if the holes are arranged in diagonal rows in plate 11, plate 11 may be employed as the transfer plate is employed in said patent in the -fabrication of rasp webs subsequent to the plating operation whereby a rasp web with hard chrome tipped spike-s is produced.
Following loading of the plate 11 with tacks, pad 13 is positioned and the cover plate |12 is attached with snap rlatches 29. The cathode assembly 10 is then arranged as the cathode in an electroplating bath 38. Such bath -generally comprises a container 39 of conventional design Jhaving an anode 41 selected as required for plating a selected metal and supported, preferably, in a horizontal tity to assure immersion of the anode 41 and at least the fixture plate 11. Conductor 33 is connected with the negative terminal of an electroplating power supply (not shown) and conductor 45 to the positive terminal to supply the electroplating current. Preferably, the power supply is `of a conventional type kwhich is adapted to provide cyclic current reversal so as to produce a smoother plating without an undue number of projecting irregularities.
With the orientation of the anode and cathode assembly indicated more uniform circumferential distribution of plating 46 is obtained on the tips and end shank portions of the tacks. Moreover, due to the orientation, the insulated covering and shape of the cathode `assembly causes the normal tendency for concentration of plating current at the tack tips to be enhanced so that the plating becomes progressively heavier from the shank to the tip portions. This distribution is mos-t advantageous for abrasive purposes. Also, the tack tips tend to become sharper as a result of the plating process.
It is contemplated that the apparatus of the invention can be employed to plate decorative metals such yas gold, silver, etc., as well as utilitarian metals such as zinc, nickel, copper, chromium and the like using conventional compositions for both the electroplating electrolyte 44 and the anode 41. With the tacks intended for use in constructing rasp webs of the character described tin-lead or antimony-lead alloys are suitable for the anodes The electrolyte may be provided as in conventional practice with about 33,-55 oz./gal. of C1O3 and about 0.33-0.55 oz./ gal. of H2504, ratios of :0 to 80:1, CrO3 to H2804 being satisfactory. For hard chrome plating current densities of `about 300 amp/sq. ft. at about F. deposits about 0.0009 in./hr. of chromium giving a hardness of about 55-60 Rockwell C. Good adherence is assured by making the cathode assembly anodic for a few second at about 100 amp/sq. ft. and then establishing the normal electroplating cycle. Cyclic reversal of the current for yabout 1 second in each l5 seconds eliminates irregularities and yields a polished finish.
What is claimed is:
1. An electroplating system for use in the application of a variable thickness hard chrome plating selectively to shank and tip protions of flat headed steel spikes utilized as in fabricating rasp webs and comprising an electrolytic cell container, a horizontally extending anode adapted to be immersed with an upwardly facing surface in electroly'te in said cell, a cathode assembly including a horizontal xture plate member of substantial Ithickness with an upper and lower horizontal surface having a plurality of spaced passages extending completely therethrough between said upper and lower surfaces for receiving said steel spikes therethrough, said passages having an annular shoulder therein adjacent said upper surface for-ming a shallow recess for receiving the flat head of said steel spikes, said passages having a reduced cylindrical crosssectional area adjacent to and below said shallow recess extending downwardly therefrom for forming a constriction closely about the portion of the steel shank received therethrough to prevent plating of the shank in this region, said passage having an enlarged cylindrical cross-sectional area adajcent to and below said reduced cylindrical area, `and terminating in a diverging conical section with respect to the longitudinal axis of said passage for surrounding the remaining portion of Ia steel shank received there* through and extending below the lower surface of the fixture plate member, said conical section being substantially one half the depth of said fixture plate member, the lower surface of said fixture plate being disposed parallel to and in spaced relationship with the upper facing surface of said horizontally extending anode so the spike tips of steel spikes received in said passages will point substantially vertically downwardly to said 4anode surface, a resilient pad disposed over the upper surface of said tixture plate member, a cover plate, means for attaching and locking said cover plate for compressing said pad over the area occupied by the Hat heads `disposed in said shallow recesses, an insulated conductor attached to said fixture plate, a meta-1 plating adherent to the surfaces of said xture plate, cover plate and vattachment means, and an insulating coating applied to exposed surfaces of said 5 plated fixture plate, cover plate and attachment means surfaces, and an electroplating power supply connected -tO said anode and cathode assembly.
2. The cathode assembly of claim 1 wherein the diverging conical section has an angle of 45 with respect to 10 4the longitudinal axis of said passage.
References Cited in the le of this patent UNITED STATES PATENTS FOREIGN PATENTS Great Britain of 1897