US2115616A

US2115616A - Method of and apparatus for plating

Info

Publication number: US2115616A
Application number: US683968A
Authority: US
Inventors: Robert N Brown
Original assignee: Packard Motor Car Co
Current assignee: Packard Motor Car Co
Priority date: 1933-08-07
Filing date: 1933-08-07
Publication date: 1938-04-26
Anticipated expiration: 1955-04-26

Description

April ,1938. R. N. BROWN. 15,6 6

METHOD OF AND APPARATUS FOR PLATING Filed Aug. 7,. 1933 ;;II;;;IIIIIIIIIIIIIIIII'IIIIIIIIIIIIII'III'IIIIIIIIIIIIIIIIIIIIIIIIII i R1751??? M atenterl Apr. 26, 1938 2,115,616 METHOD OF AND APPARATUS FOR PLATING Robert N. Brown, Detroit, Mich, assignor to Packard Motor Car Company, Detroit, Mich, a corporation of Michigan Application August 7 v1933, Serial No. 683,968

Claims. (Cl.,204-5) This imention relates to a process of and apparatus for plating articles.

It is sometimes desirable to plate articles so that the coating is of varying thicknesses. In order to obtain different thicknesses of coating, it has previously been necessary to subject the article to more than one plating operation. This has been necessary because the article must be adjusted in its carrier to place the portion having a desired thickness of coating in a relation where it will not again be submerged in the bath, or portions of the article must be covered with .paramn or similar material in order to prevent further coatingthereof if complete submersion in the bath is resorted to. The multiple plating operations or multiple handling of an article during plating is expensive and requires time,

and it is an object of this invention to provide apparatus for carrying an. article during a single plating process so that different portions will have coatings of different thicknesses.

Another object of the invention is to provide apparatus for holding bolts submerged in a bath during a plating process so that the coating deposited on the head portion will be thicker than the coating deposited on the shank portion.

A further object of the invention is to provide an apparatus for holding articles during a plating process so that a portion of the article is shielded. in a manner such that it will receive a thinner coatingthan the unshielded portion.

Still another object of the inventionis to provide a novel and improved plating" process wherein the coating deposited on a submerged article is thinner on one portion than on another portion. 1

Other objects or the invention will appear from the following description taken in connection with the drawing, which forms a part of this specification, and in which:

Fig. l is a sectional view of plating apparatus incorporating my invention;

Fig 2 is a sectional view taken on line 2-4 of Fig. 1 with parts of the apparatus broken away.

Referring now to the drawing by, characters of reierence, -l0 represents an open top tank ior containing an electrolyte II which in this ina stance is a chromic acid solution H2Cr04. Ex-

nects with a source of electricity, such as a battery l'l.

Extending across the .tank and resting on the top edges thereof is a supporting member having a copper core i8 surrounded by a layer of insulating material l9. Wiring 20 leads from the battery and. is connected with the end of the supporting bar core by a connector 2! fastened by a set screw 22. Suspended from the bar and extending into the electrolyte is a holder for an article to be plated, which in this instance is a bolt 23. The holder consists of a pair of partly insulated wire members 24 having the upper ends extending through an opening in the bar and fixed in contact with the core by a set screw 25. The wires are of a length to extend into the acid bath when the bar is resting on the tank and the lower end portions are bent to form resiliently contacting fingers providing an opening 28 therebetween through which the shank of a bolt can be readily axially inserted or removed. Current passes from the bar core through the holder to the bolt so that it forms the cathode.

When the above described apparatus is associated and the switch It is closed, then the electrolyte is decomposed by the electric current and chrome adheres to the bolt. This plating will be of substantially uniform thickness on the entire bolts surface unless some provision is made to lessen the deposit in certain areas.

In many instances, difierent thicknesses of plating on articles are necessary or desirable. A thick heavy plating on a bolt head is desirable because of repeated applications of a wrench thereto and, at the same time, a considerably thinner plating on the bolt shank is desirable ii retapping oi the threadsis to be avoided. Two thicknesses of plating have heretofore required multiple plating operations or adjustment of the article support after being submerged in the bath.

In order to obtain two thicknesses of plating on different surfaces of an article without re moval from the bath or adjustment of the apparatus or the article during the process, I provide means'ior limiting the electrolytic action in the bath adjacent the portions of thearticle to receive the thinner coating. In the present instance, a shield is provided around the shank of the bolt so that the electrolytic action will be less adjacent the shank than adjacent the head. The shieldv consists of a cylindrical casing 21 formed of insulation material having one end adjacent the wires 24 removable and formed with an opening 28 aligned with the opening 28 so that the bolt shank can project therethrough. An arm 29 extends upwardly from this end of the cylinder, and'one endoi' a hanger in the form of a wire 30, is fixed in the arm. The other end of the hanger is fixed to the supporting bar and an insulation sleeve 3| covers the portion of the hanger intermediate the arm and the bar.

Openings 32 are provided in'the cylinder shield which with the opening 28 allow the electrolyte to flll the casing when submerged. The casing 2! acts as a shield around the bolt shank which reduces the chemical action produced by the electric current as compared with that in the surrounding bath. The degree to which such chemical action causes deposition of chromium on the bolt shank is regulated by the size or number of openings, and thus the thickness of plating on the bolt shank relative to the thickness of the plating on the bolt' head can be regulated as desired.

It will be seen that the apparatus herein described can .be submerged in a plating bathand that portions of an article carried thereby will be coated diflerent thicknesses without any further adjustment or repeated process operation.

Although the invention has been described in connection with a specific embodiment, the principles involved aresusceptible of numerous other applications which will readily occur to persons skilled in the art. The invention is therefore to be limited only as indicated appended claims.

What I claim is:

1. Proceastor chrome plating bolts, comprising submerging a bolt as a cathode in a chrome acid solutIomeneasin'g the bolt shank in a member provided with means permitting limited electrolytic action around the bolt shank, suspending an anode-in the zone of the bolt, and passing current through the solution by means of said 40 bolt and anode to form diflerent thicknesses of plating on the shank and head of the bolt.

2. An electrolytic apparatus comprising a reby the scope of theceptacle, an electrically conducting support adv ,iacent the top of said receptacle, an article enclosing member of non-conducting material depending from said support, said article enclosing member having a horizontally extending chamber open at one end, and a pair of resilient fingers of conducting material electrically connected to said support and disposed adjacent the open end of said chamber.

3. An electrolytic apparatus comprising a receptacle, an electrically conducting support adliacent the top of said receptacle, an article enclosing member oi! non-conducting material depending from' said support, said article enclosing member having a horizontally extending chamber open at one end, the walls of said chamber being perforated.

4. An electrolytic apparatus comprising a receptacle, an electrically conducting support adjacent the top of said receptacle, an article enclosing member of non-conducting material depending from said support, said article enclosing member having a horizontally extending chamber open at one end; and a pair of resilient fingers of conducting material electrically connected to said support and disposed adjacent the open end of said chamber, said fingers being adapted to grip an article therebetween and support said article partially within said chamber.

5. An electrolytic apparatus comprising a receptacle, an electrically conducting support adjacent-the'top of said receptacle, an article enclosing member of non-conducting material depending from said support, said article enclosing member having a horizontally extending chamber'open at one end, a member having a central aperture and adapted to partially close said open end of ,said chamber,- and article supporting means electrically connected to said support and disposed outside of said chamber and adjacent said aperture.

" V ROBERT N. BROWN.