Selective Plating Machines

Abstract

Electro-plating machines are described, which enable plating to be carried out selectively, but using tanks for electrolytes and other treating liquids which include weirs adjustable in height so as to allow adjustment of the heights of the treating liquids. The objects to be plated are desirably mounted from a trackway, preferably formed by the current busbar, and are moved along the trackway by means of a transport system.

Description

FIELD AND SUMMARY OF THE INVENTION

This invention relates to electro-plating machines of the kind arranged to operate on a continuous basis.

It is sometimes desired to electro-plate only part of an article, leaving the rest uncoated. For example, in the case of the contact springs for electrical connectors or relays, it is only necessary to plate the actual region where contact is made, when the connectors or relays in which the contact springs are included undergo actuation. Since it is frequently the practice for such contact springs to be plated with gold, a considerable saving of precious metal can be effected in this manner, by limiting the gold deposit to the areas of the springs where contact is actually made.

It is an object of the invention to provide an apparatus in which the depth of immersion of an item to be plated in the electrolyte can readily be varied. This apparatus enables gold or other precious metal to be electroplated onto articles with an improved degree of selectivity as regards the parts of the articles on which the deposits are formed.

According to one aspect of the invention, an electro-plating machine is provided, having at least one tank in the form of an elongated trough, articles to be electroplated being passed into the tank at one end and removed from the other end the trough, a weir of being located within the trough adjacent at least one end thereof and at least one of the weirs being adjustable in height, whereby the height of electrolyte in the trough is controllable by adjustment of the weir height, means being provided for supplying electrolyte to the part of the trough between the weirs and means for withdrawing from the trough electrolyte which has flowed over the weir or weirs.

Preferably, two adjustable height weirs are provided and electrolyte drained from the end parts of the trough can be recirculated to the part located between the weirs.

According to another aspect of the invention, arrangements are made for suspending from a track objects which are to be plated. An endless conveyor chain or like member is disposed adjacent to the track and is provided with pusher dogs which are arranged to push the objects along the track, which can also be the cathode supply bus bar.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more readily understood from the following detailed description with reference to the accompanying drawings, in which:

FIG. 1 is a partially broken-away side elevational view of one tank of a plating machine in accordance with the invention, also showing parts of two adjacent tanks;

FIG. 2 is a sectional view taken on the line II--II of FIG. 1; and

FIG. 3 is a sectional view taken on the line III-III of FIG. 1.

Referring to FIG. 1, an elongated plating tank 10 is arranged in line with a preceding plating tank 12 and a following plating tank 14 in a row of tanks. In use, successive tanks in the row contain the treatment liquids necessary for successive stages in the process. The tanks 10, 12 and 14 are generally similar in construction. Thus tank 10 can have a rectangular cross-section, as seen in FIG. 2, and includes a base 10a, opposed side walls 10b, 10c and opposed end walls 10d, 10e. The base 10a includes openings for connection of the tank 10 to supply and drainage pipes, as described in more detail below.

Anode rails 16a and 16b (FIG. 2) mounted on the side walls 10b and 10c of the tank 10 by means of brackets 18 and 22 extend through the tank.

A weir 24 is disposed in the tank 10 adjacent to the end wall 10e thereof. The weir 24 extends between the side walls 10b, 10c of the tank 10 and is sealed thereto in any suitable way permitting its height above the bottom 10a of the tank 10 to be adjusted. A corresponding weir 26 is disposed adjacent to the other end wall 10d of the tank 10. The weirs 24, 26 are provided with notches or recesses 25 (shown for the weirs 26 and 38 in FIGS. 2 and 3, respectively) extending down from their upper edges.

Drainage pipes 28 and 30 lead from the end compartments of the tank 10, i.e. the spaces outside the weirs 24 and 26 respectively and between them and the end walls 10d, 10e. These pipes 28, 30 lead to a reservoir 32 disposed below the tank 10. A pump 34 is arranged to pump liquid from the reservoir 32 via a pipe 36 into the part of the tank 10 between the weirs 24 and 26.

Referring to FIG. 3, the weir 38 consists of a fixed slotted plate 24a having at least one notch or recess 25 therein. The plate 24a is sealed to the base 10a and side wall 10b, 10c of the tank 10. An adjustable slidable plate 24b is mounted on the upstream side of the plate 24a by means of studs 29a and 29b which are located in vertical elongated slots 30a and 30b, respectively, in plate 24b. Plate 24b is less in height than plate 24a, and, when the studs 29a and 29b are located at the top of the slots 30, plate 24b exposes the whole depth of notch or recess 25. When raised, the plate 24b progressively covers more of the notch or recess 25 so that the effective height of the weir can be adjusted to any position throughout the lengths of the notches or recesses 25. The tanks, weirs and other parts contacted by the electrolyte are made of inert material, preferably PVC or polypropylene, screwed unions being used for joints in the pipework.

An alternative method of raising the level is to replace the adjustable plate 24b by one of a series of plates of varying width of notches or recesses, all narrower than the slot 25. When the pump 34 is running, liquid constantly flows through the slots 25 in the weirs 24 and 26 into the end compartments and then by gravity back into the reservoir 32 whence it is pumped again into the tank 10. Consequently, if the adjustable plates 24b of the weirs 24 and 26 are raised or lowered, the liquid level in the part of the tank 10 between the weirs 24 and 26 is altered to a new level. Adjacent tanks 12 and 14 are provided with a similar arrangement, weirs 38 and 40 and the respective drain pipes 42 and 44 being shown in FIG. 1. The liquid levels in the tanks can also be adjusted by means of a control valve in the circuit containing the pump 34, the level being raised if the rate of inflow to the tank exceeds the outflow through the slots 25 and vice versa.

An electrically conductive cathode rail or track 46 (FIGS. 1 and 2) which can be circular, square or rectangular in construction, extends above all the tanks of the machine and is symmetrically disposed with respect thereto. It is connected by means of respective insulators 48 (FIG. 2) to mounting brackets 50 disposed to one side of the various troughs. A conveyor chain 52 (FIG. 1) is disposed above and somewhat to one side of the cathode rail 46. Outwardly extending pusher dogs 54 are disposed at intervals along the chain 52. The pushers could be otherwise arranged for example to extend vertically if necessary because of different conveyor arrangements.

Referring more particularly to FIG. 2, each object 56 which is to be plated is hung from a jig 58 which includes a grooved wheel 60 arranged to engage on the track 46 and a protruding limb 62 which projects into the path of the pusher dogs 54.

In use, anodes 64 are suspended from the anode rails 16a and 16b in those of the tanks such as the tank 10 in which electro-plating (as opposed to washing or degreasing) is to take place. The pusher dogs 54 on the conveyor chain 52 push a jig 58 along the track 46. Objects 56 which are to be plated trail from the jig 58 and are carried thereby through the slots in the weirs and through aligned slots (not shown) in the end walls of the various tanks without contact between the objects and the weirs and walls. The drain pipes 28, 30 allow a rate of flow sufficient to ensure that there is no outflow of liquid through the end wall slots. The level of electrolyte or other treatment liquid in each of the tanks is adjusted so that the required proportion of the object 56 is covered and therefore treated.

A variable drive unit can be provided if required to permit the speed of the conveyor to be varied.

The invention thus provides a convenient apparatus for selectively plating parts of objects. The use of the conveyor chain and pusher dog arrangement enables a jig to be placed on the track 46 or removed therefrom at any point without interfering with the operation of the machine as a whole.

Claims

We claim:

1. An electroplating machine comprising, in combination, at least one tank in the form of an elongated substantially horizontal trough, through which articles to be electroplated are passed; at least one weir within said trough adjacent an end thereof; each weir being adjustable in height so that the height of the electrolyte within the trough inwardly of the weir can be adjusted by adjustment of the weir height; means connected to that part of said trough inwardly of each weir and operable to supply electrolyte to said part of said trough; and means connected to said trough outwardly of each weir and operable to withdraw, from the adjacent end part of the trough, electrolyte flowing over the weir; whereby selected lengths of the lower ends of articles passed horizontally through said trough can be treated by adjustment of the height of the electrolyte within said trough by adjustment of the weir height.

2. An electroplating machine, according to claim 1, including a respective adjustable height weir within said trough adjacent each end of said trough.

3. An electroplating machine according to claim 2, wherein electrolyte drained from the end parts of the trough is recirculated to the part located between the weirs.

4. An electroplating machine, according to claim 1, in which each weir includes a fixed plate, having at least one notch extending downwardly from its upper edge, and further includes an adjustable plate juxtaposed with said fixed plate and adjustable in height to control the effective depth of said notch to adjust the effective overflow height of the weir.

5. An electroplating machine, according to claim 1, in which each weir includes a fixed plate; dies extending downwardly from the upper edge of said fixed plate; and removable plates interchangeably engageable in said guides; said removable plates each having a notch extending downwardly from its upper edge, and said notches having respectively different dimensions to adjust the overflow height of the weir.

6. An electroplating machine, as claimed in claim 1, including a track suspending the articles to be treated; an endless conveyor located above said tank and adjacent said track; and pusher dogs on said endless conveyor operable to push the articles along the track and through said tank.

7. An electroplating machine, according to claim 1, including plural said tanks, substantially identical in construction, components and connections, arranged in succession in longitudinal alignment with each other for passage of the articles successively therethrough; whereby the articles may be passed in a straight line through said electroplating machine, with the respective heights of liquid in each tank being selectively adjustable by the associated adjustable height weirs to control the lengths of the lower ends of the articles to be treated.

8. An electroplating machine, according to claim 7, in which each of said tanks has a different respective treating liquid supplied thereto and withdrawn therefrom.

9. An electroplating machine, according to claim 8, in which at least one of said tanks has a washing liquid supplied thereto and withdrawn therefrom.

10. An electroplating machine, according to claim 8, in which at least one of said tanks has a degreasing liquid supplied thereto and withdrawn therefrom.