US2319624A - Current distributing means for electrolytic processes - Google Patents

Description

May 18, 1943 R. C. OLSEN CURRENT DISTRIBUTING MEANS FOR ELECTROLYTIC PROCESSES Filed Dec. 24; 1940 Snnentor 0135723 6 @Zwzz/ Patented May 18, 1943 UNITED STATES PATENT OFFICE CURRENT DISTRIBUTING MEANS FOR ELECTROLYTIC PROCESSES Robert C. Olsen, Detroit,- Mich., assignor to Ternstedt Manufacturing Company, Detroit, Mich., a corporation of Michigan Application December 24, 1940, Serial No. 371,486

1 Claim. (01. 204-228) g r electrolyte but may-include, particularly in the Considerable diificulty is encountered in electrolytic processes in obtaining the desired distribution of current over the surfaces of the electrodes. This is particularly true in processes which require relatively narrow limits of the current densities at the electrode surfaces in order to effect the desired results. In chromium plating, for example, .or in bright nickel plating, fairly accurate control of current densities is necessary to maintain satisfactory brightness of the deposits. at the surfaces, as, for example, the quantity or thickness of electrodeposits, is also dependent upon the current density over the areas involved and uniformity of actions is obtainable .only b accurate control of current distribution.

It is recognized that the difiiculty in question is due to varying resistances offered to the flow of The extent of electrolytic action current. discharging or redistributing portion, materials adapted to supply coatings for the cathode or work. In electroplating operations, for example, the current distributing part may be of the metal being deposited such as nickel, or.

example, to modify the form of the anode to make it conform more closely to the contour of the cathode or work. Cathodic appendages, commonly termed robbers, are also frequently employed to shield portions of the cathode that are nearer the anode. The latter devices are of only limited utility since they merely divert current entirely unconnected electrically except through.

the electrolyte with either ofthe electrodes. This means may however, as a matter of convenience,

particularly where oneelectrode, as the cathode or work, travels through the electrolyte, be supported upon the electrode by suitable insulating means, Its mechanical features may be widely varied but comprise essentially a current collecting part positioned in the electrolyte in the path of current flow and a current distributing part,

.said parts so proportioned and positioned with reference to the anode and cathode as to collect,

direct, and/or redistribute the current in accordance with the desired apportioning of current densities.

the process. It should ordinarily be inert in the The material of the device will vary, of course, with the nature of the electrolyte and I Where the metal being deposited is supplied by the electrolyte, as in the usual chromic acid chromium plating baths, such part may be of .any

suitably inert metal, as lead, lead-coated copper,

or soft steel.

It will be understood that, if plating metal is being supplied in part by the current distributing means, such metal must be replenished at intervals. It is therefore convenient, in such cases, to provide means for removal or replacing of the current distributing portion. The current collecting portion, however, is of indefinite life since electrolytic action at its surface tends to deposit metal rather than remove it.

In the accompanying drawing Figure 1 is a diagrammatic view illustrating the application of the invention.

, Figure 2 is a view more in detail, showing the form of the current distribution modifying device as designed for a particular use.

Figure 3 is a cross section on line 3-3 of Figure l. v

, In the drawing, 5indicates a suitable receptacle, hereinafter referred to as a tank, shown in cross-section and which may be of any size and length depending upon the character and extent of the electrolyticprocess.

The electrolyte is marked 1. Over the tank are positive and negative bus bars 9 and II and currentis supplied by a generator G. The anode I3 is supported as at IS on the positive bus bar and th cathode li-the work-is supported on the negative bus bar by means such as a hook 19. In the embodiment shown the work is a part of a motor vehicle grille. .It is irregular in shape and as explained above the work would receive a coating of unequal thickness were no provision made to correct such a defect. r

The difllculty is overcome by the use of a redistributing means in the form of an intermediate anode markedll shaped to conformto the outline of the work as shown by Figure 1.

- In practice the work travels through the electrolyte and it is desirable to support the anode 2| "from the work itself so that it moves with the work and the space relation between the intermediate anode and the work remains unchanged. The anode 2i may. be of nickel wire in the process ofplating a surface with nickel.

marked 21 and 29.

In order to gather more current ther is assoiciated with the intermediate anode a collector plate marked 23. The ends of the nickel wire 2| are secured to the collector plate as shown at To support the assembly of parts 2land 23 there are used insulating members of Bakelite Member 21 carries a hook 3| which engages in an opening in the lower end of the work. Member 29 carries an undercut attaching element 33 for engaging an upper part the work travels through the electrolyte.

While the invention has been described herein as applied specifically to the electroplating art for which it was more particularly designed, it will be understood that, in its broader aspect, it is applicable to other fields in which it becomes desirable to modify the distribution of electric current over the surfaces of electrodes employed in electrolytic processes. v

I claim:

The combination with 'a tank, an electroplating electrolyte therein. anodes fixedly supported in said electrolyte, work-supporting means arranged to travel through said electrolyte past said anodes and to support irregularly shaped work, and means to cause electric current to flow through said electrolyte between said anodes and said work, of a current-collecting and distributing device spaced from said anodes and unconnected therewith but positioned in the pathof said current, said device having a current-collecting part composed of metal other than the plating metal positioned nearer the anodes than the work and a rcurrent-distributing part composed of plating metal positioned nearer the work and conforming in contour to the contour of irregularities of the work throughout substantially the entire area of the irregularities, and means for insulatingly supporting said device fixedly upon the work so as to travel therewith.

ROBERT C. OLSEN.

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