US1970459A - Plating rack - Google Patents

Description

J. N; KELLY PLATING RACK Filed May 26, 1932 9 gm 97. 7! 2 @62 Aalzw' Patented Aug. 14, 1934 PLATING RACK John N. Kelly,

Cleveland, Ohio Application May 26, 1932, Serial No. 613,682

2 Claims.

This invention relates to a method of and apparatus for plating articles, and more particularly to a method and apparatus for economically plating certain portions of small articles, for example the heads of bolts.

In ordinary plating methods, the same thickness of metal is deposited upon substantially all of the unprotected surface of the article to be plated. For example, in the nickel plating of bolt heads it has been found that by the time a thousandth of aninch of plating is deposited on the head of a bolt, the same thickness of plating has been built up on the top of the threads. The plating action takes place unevenly on V threads, and distorts them to such an extent that when a thousandth of an inch has been deposited on the bolt heads, the threads would no longer fit the gauge specified for the particular bolts. Also, plating the entire bolt in order to obtain a coating on the head results in an expensive waste of power and material.

Accordingly, a general object of my invention is -to provide an economical method and apparatus for plating desired portions of small articles. A specific object of my invention is to provide an inexpensive, efficient method and apparatus for plating the heads of bolts without depositing an objectionable amount of plate on the threads of the bolts.

My prior application, Serial No. 532,110, filed April 22nd, 1931, shows an efficient plating rack which is well adapted for plating small articles, such as bolts, on a production basis. The apparatus comprising a part of the present invention is an improvement on the plating rack shown in my copending application in that means are provided to shield the threaded portions of the bolts from the plating action, so that only the heads thereof will receive a deposit of material thickness.

In the drawing, Fig. 1 is a section through a plating bath showing my apparatus positioned therein, with a portion of the apparatus broken away; Fig. 2 is an elevation of the apparatus removed from the bath; Fig. 3 is a section along the line 33 of Fig.2; Fig. 4 is a sectional detail taken along the line 44 of Fig. 2, and Fig. 5 is a crosssectional detail on an enlarged scale taken along the line 5-5 of Fig. 2.

I have shown my invention in connection with the plating of bolts, but it is to be understood that my method and apparatus may be adapted for use in connection with the plating of any small articles on a production basis, particularly when it is desired to plate certain portions of the article and leave the remaining portions without any substantial deposit of plate.

A preferred arrangement of my invention includes a holder 10, which is adapted to be suspended within a plating bath 11, and which is provided with means for enabling the articles to be quickly engaged and released, and for shielding the portions of the articles which are not to be plated from the plating action.

The holding mechanism is quite similar to that illustrated in my copending application, Serial No.-532,010, and a preferable arrangement may comprise current-carrying bars 12, that are provided with spacedopenings 13, into which the bolts 15 or other articles to be plated may be inserted. In the drawing, bolts are shown in only a few of the openings 13, but it is to be understood that in ordinary practice a bolt will be placed in each of the openings in the rack. The members 12 may be held in the form of a frame by cross-bars 16 secured to the respective members at spaced intervals, sufiicient cross-bars being employed to give the rack the required strength and rigidity.

To hold the bolts or other members in place,

I may employ a clamp which is adapted to clamp or release all the bolts simultaneously. Such a clamp may comprise a plurality of yieldable wires '20, which are attached rigidly to a bar 21 which is in turn mounted for longitudinal movement on the cross-member 16, as by pin and slot connections 22. The longitudinal bar may be actuated by a lever 23 which may be pivotally mounted on a bracket 24, and which may be held in clamping position by a keeper 25.

As shown clearly in Fig. 5, the resilient wires preferably engage the bolts immediately below the heads thereof and lie between the bolt heads and the conducting bars 12. The openings 13 are slightly larger than the shank of the bolts, so that the bolts may be readily inserted therein. When the bolts areclamped in place, they will be tilted slightly, thus making contact on opposite sides of the openings, as at 27 and 28.

In order to prevent the rack from being plated during use, the entire rack is preferably provided with an insulating coating, of rubber or other material, as indicated at 26. After' the coating has been applied, the holes 13 are reamed out to prcvidea contacting surface for conducting electricity to the bolts.

' It is well known that the rate at which metal is deposited in electro-plating operations, is largely dependent on the current density employed. I have found that by shielding the electrolyte which is in contact with, for example, the threads h of the bolts, while allowing the heads to remain in the main body of electrolyte, it is possible to locally reduce the current density to such an extent that the required thickness of metal may be 5 deposited on the heads without depositing a material amount on the threaded portion. By this means, any distortion of the thread is prevented, and as only a comparatively small area of the bolt is plated, the power required is much less and the amount of plating material used is greatly reduced.

In order to shield the threaded portions of the bolts from the plating action, I have provided hollow shielding members 30, which may be made of any suitable insulating material, such as hard rubber, and as shown in Fig. 4, may have a substantially semi-cylindrical cross-section. Bolts 31 fasten the shields to the bars 12 and press them against the insulating material 26 with sufficient firmness to provide substantially fluid-tight joints between the bars and the shields. In order to facilitate rinsing of the shields, small openings as at 32 may be formed in the bottom thereof. The shields therefore comprise backing strips which cooperate with the openings 13 to provide pockets for receiving the bolts or other articles to be plated.

As indicated in Fig. 1, the shields extend abovethe level of the electrolyte, so that the only means by which the'electrolyte within the shields can communicate with the main body of electrolyte in the plating bath is through the restricted path around each bolt and through the small slots 32. The total cross-sectional area of such paths is quite small, and therefore there will be considerable resistance to the passage of current from the main body of electrolyte to the portion within the shields. Thus, the current density on the shanks and threaded portions of the bolts will be much less than the current density on the heads of the bolts which are exposed to the main body of the electrolyte and as a result of this difference a layer of metal of the required thickness may be deposited on the heads before any substantial deposit will be made on the threaded portions of the bolts.

It will be seen that I have provided a convenient method and apparatus for plating certain desired portions of small articles; that my method may be carried out with a minimum amount of trouble; that it will result in substantial savings in power and material cost and will prevent any undesired and troublesome deposits of plating material.

I claim:

1. In a device of the character described, the combination with a holder having spaced article receiving pockets therein adapted to shield one end portion of the article from the plating current, and a flexible clamp carried by the holder and movable with relation thereto, said clamp when moved in one direction being adapted to engage all of the articles substantially simultaneously and to hold them in current conducting contact with the holder, and when moved in the opposite direction being adapted to release all of the articles substantially simultaneously whereby they may drop by gravity from the holder.

2. In a device of the character described, the combination with a relatively stationary bar having spaced article receiving openings therein, a hollow shield carried by the bar on one side thereof for shielding one end portion of the articles from the plating current, a clamp movably mounted on the bar on the side opposite the shield and having yieldable portions thereon for engaging each of the articles, Whenever the clamp is moved in one direction, so as to lock all of them substantially simultaneously in current conducting contact with the bar, and to release all of them substantially simultaneously, whereby they may drop by gravity from the bar whenever the clamp is moved in the opposite direction with reference to the bar, said bar having a hook adjacent the top thereof for suspending it in a plating bath.

JOHN N. KELLY.

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