US 2684939 A
Description (OCR text may contain errors)
July 27, 1954 C. F. GEESE APPARATUS FOR PLATING CHROMIUM Filed Deo. 17, 1949 INVENTOR. @fs/Aufs iwf/waff 6275i Z5 Patented July 27, ,1954
UNITD STAT S ATENT OFFICE PAPPARTUS FOR PLATING CHROMIUM Application December 17, 1949, Serial No. 133,545
3 Claims. l
The present invention relates to apparatus for plating chromium and like metals, and embodies more specifically an improved. form of plating apparatus by means of Wl'iich merels, such as chromium, may be spot plated, that is, plated upon surfaces that are extremely small in area.
In conventional plating operations, the surface to be plated is immersed in a plating solution and made the positive terminal of electrical circuit while the inetal to be plated upon the surface is ina-de the negative terminal. The plat ing occurs over the entire submerged suriace except such portions as may be staged out .by means of a suitable coating that resists the passage of current. Where a relatively7 small amount only of a surface is to be plated, difliculty is experienced in staging out the surface that not to be plated, and it is an object ci the present invenn tion to provide an apparatus and also a method by means of which metallic plating operations may be carried on in extremely limited areas.
A further object of the invention is to provide an apparatus and method of the above character wherein spot plating oi metals, such as chromium, may be accomplished without disturbing adjacent surfaces or requiring treatment thereof to protect them against injury.
Yet another object of the invention is to provide an apparatus and method of the above character wherein metals, such as chromium, may be plated upon desired surfaces without requiring such surfaces to be immersed in a plating solution.
ll'urther and other objects or" the invention will be apparent as it is described in greater detail in connection with the accompanying drawings, wherein Figure 1 is a schematic View illustrating elements of a plating apparatus constructed in accordance with the present invention;
Figure 2 is a view in longitudinal cross-section, taken on the line 2-2 of Figure 1, showing a spot plating mechanism constructed in accordF ance with the present invention;
Figure 3 is a bottom View of the device shown in Figure 2; and
Fig-ure 4 is a View in longitudinal cross-section, taken on the line 2--2 of Figure l, showing the lower portion of an alternate embodiment of the spot plating mechanism constructed in accordance with the invention.
Referring to the above drawings, l indicates a surface upon which plating is to be eiiected in limited areas, this surface constituting any element such, for example, as a printing plate. The plate is connected to the negative terminal of a (Cl. 20d- 224) battery l l or other suitable source or electric current through a clip l2 and wire I3. The positive terminal of the battery is connected through a wire l l to a plating tool l5 which may be formed at its upper end with a bushing i5 through which the wire I4 extends and with an intermediate wall ll. A cup-shaped terminal it is carried by the wall l? and connected to the wire ill, as illustrated in Figure 2.
The tool l5 is for-med of a casing iS that may comprise nylon or some similar substance that is impervious to the compounds that might be used as plating solutions, as hereinafter mentioned. A head 2li is formed With a shoulder portion 2| within which the end of the casing as nts, the et either being accomplished by a threaded connection or by press t against a circumferential wall 22 that may have a slight taper toward the axis of the head and away from the shoulder 2l. Axially of the head 20, a threaded shaft 23 is secured, the axial position oi the shaft with respect to the head being variable by turning the shaft therein` At the lower eno` ofthe head 20 a conically shaped tip 24 is secured, the'tip being slotted at 25 and terminating in an opening 25 at the small endthereof. An anode 21 in the form of a metallic wire is carried by the shaft 23 and extends to a point adjacent the opening 2li, the size of the opening '2B and the slots 25 being such that a plating solution 28 may be retained within the tip without nov/ing therefrom by gravity. For example, the width of the slots 25 may preferably be in a range of from .006" to .010. Even though slots of this site Willnot permit the free now of the plating'solution 28 by gravity, the slots 25 will tend to feed the plating solution 28 to the opening 26. The space within the tip and above the plating solution 28 may either be vented to the atmosphere by means of a vent 29 of suiiciently small size as shown in Figure 2 or Va duct 38 as shown in Figure 4 may be formed therein communicating with the circumferential portion 22 so that, when the point is dipped in the plating solution, the latter fills the space within the tip, and the air is exhausted through the duct 30, the casing I 9 previously having been removed. When the casing I9 is secured in the position illustrated in Figure 4, the duct 30 is closed, and the plating solution 28 more eiectively maintained Within the tip 24.
Under these conditions, the slots 25 will permit gasesf-ormed by the electrolytioreaction of the plating operation to escape without blocking the opening 26 and interrupting the plating.
In operation, the axial position of the anode 21 is suitably adjust-ed by rotation of the shaft 23 to give the desired spacing of the tip of the anode 2l from the aperture 2B. With the electrical circuit connected as illustrated in Figure 1, the opening 25 of the tip 24 is moved against the surface of the element I9 and over the surface in accordance With the areas upon which plating is to be accomplished. The plating tool thus enables minute areas of the element I9 to be plated without disturbing the areas of the element that are not to be plated.
The invention is particularly useful in connection with the manufacture of lithographic printing plates wherein chromium is applied to the portions of the plates which are to be water receptive and ink repellent. The metal of the plate proper (which carries the int: to be printed) may be copper. It frequently happens that after plates of this character have been manufactured, certain corrections must be performed by plating in chromium on areas that have not been properly plated during the manufacture of the plate. These areas are frequently extremely small, and it is extremely difficult to plate them Without adding additional chromium plating to the previously plated portions, or to other areas in which the base metal (such as copper) is to be preserved. It will be apparent that the apparatus is suitable for plating metals other than chromium simply by selecting the desired plating solution. The anode 2T may be formed of the metals which are to be plated, in Which event, different shafts 23 with the appropriate anodes 2'! are utilized for plating different metals. In operation, the tool l is used somewhat similarly to the Way in which a pen is used. The tip may bedipped into the plating solution in order that a quantity of the solution may enter the tip as illustrated in Figure 2.
The material of which the metallic contact Wire is formed quite naturally depends upon the particular plating operation that is being carried out. For example, if chromium is being plated, the material of the Wire anode might be either platinum or stainless steel. In operations involving the plating of other materials, such as silver, nickel, gold, copper, zinc, etc., the contact could and should be of the correspondingly appropriate material, in accordance with recognized plating opera-tions. It will also be understood that the size or area of the surface that is plated need not -be relatively small. The operating end of the device may be formed with a relatively Wide slot and. an appropriately formed anode in order that more substantial areas may be plated upon one application or operation of the apparatus.
While the invention has been described With specific reference to the accompanying drawings, it is not to be limited save as defined in the appended claims.
1. Plating apparatus for spot electroplating conducting surfaces comprising, a rigid nonconductive tip formed with a hollow portion therein providing a reservoir for plating solution and having a capillary opening at the extremity thereof connecting with the hollow portion for gradually releasing the solution upon movement of the extremity of said tip against a surface to be plated, and an elongated anode Within said tip having an end adjacent the opening, said extremity of said tip having slots intersecting and extending away from said capillary opening to prevent gases formed by electrolysis from blocking the capillary opening.
2. Plating apparatus for spot electroplating con-ducting surfaces comprising a rigid hollow enclosed conically-shaped non-conductive tip adapted to retain a supply of plating solution therein, having a capillary opening at the apex thereof for gradually releasing the solution upon movement of said tip against a surface to be plated, and provided with a pressure equalizing vent, opening into said enclosed conically-shaped tip, and an elongated anode Within said tip having an end extending into the opening, said tip being provided with slots intersecting and extending away from said capillary opening.
3. Plating apparatus according to claim 2 wherein the elongated anode comprises a vvire substantially coaxial with the non-conductive tip.
References Cited in the le of this patent UNITED STATES ?A'IENTS Number Name Date 1,416,929 Bailey May 23, 1922 1,545,941 Coady July 14, 1925 1,621,450 Aramian Mar. 15, 1927 2,336,028 Nichol Dec. 7, 1943 FOREIGN PATENTS Number Country Date 400,510 Great Britain Oct. 26, 1933 673,382 France Oct. 7, 1929 130,909 Switzerland Apr. 16, 1929 373,398 Germany Apr. 12, 1923