US2649525A - Contact - Google Patents

Description

C. L. HARVEY Aug. 18, 1953 CONTACT Filed May 16, 1951 LILJLILILILL IE Z Ill! l aivluunu INVENTOR. 6'50/4 Z. Ham E) Patented Aug. 18, 1953 SATES ATNT "FFICE CONTACT tion of Pennsylvania Application May l'fi, 1951, Serial No. 226,693

invention relates are composed of a sintered combination of a highly conductive metal such as copper or silver and a semirefractory or a refractory metal, such as tungsten, tungsten carbide, molybdenum, and molybdenum carbide. The final treatment of the initially porous sintered combination comprises the operation of impregnating the same with a high conductivity metal, such as silver. The electrical contacts referred to herein contain, in most cases, about forty'or more percent of the refractory material.

Electrical contacts which contain refra t y material in an amount of the order of that referred to above are hard and brittle, and hence cannot be subjected to the usual forming operations such as rolling, slitting, cutting, punching, coining and staking. Therefore, they are furnished as individually molded and treated pieces which have not heretofore been available in other than individual form. This is a highly objectionable feature of these contacts when attempting to utilize them in a high production rate set-up. This is particularly true when the individual contacts are very small.

It is presently the practice to either braze or weld the contact to the contact arm. In applying these contacts to the contact carrying arm the operator feeds the contact in position in a jig in the welding machine and then applies the arm to which the contact is to be welded to the contact.

In many instances the contact is of the order of in diameter and in thickness and is accordingly not easily manipulated into its position.

Moreover, there is considerable risk to the operator whose hands must for an instant while placing the contact in place be underneath the electrode which is shortly thereafter to be machine operated with considerable force against the arm and contact while applying current for welding.

In order to overcome these difiicultiesit has been proposed to bond the individual contacts to a paper strip with an adhesive. However, after removal of the contact from the paper strip it is found that the adhesive adheres to the contact 5 Claims. (Cl. 200-166) and adversely affects its characteristic or presents special problems in removal of the adhesive or other foreign matter prior to the securement of the contact on the contact arm.

In accordance with my present invention, I have discovered that I can achieve a binding between adjacent contacts so as to form a l strip comprising a plurality of such contacts. Such a long strip of contacts now makes it relatively easy to handle the operations of feedin individual contacts into the welding jig. he operator, in such a construction, merely holds the contact strip at one end and uses the contact strip to position an end contact into the weldin ig.

Accordingly, an object of my invention is to provide a novel means for connecting a plurality of electrical contacts toegther in series and a novel method for obtaining this result.

A further object of my invention is to provide a bonding material which will have no deleterious effect upon the conductivity or other properties of the electrical contacts.

A further object of my invention is to combine the bonding operation with a previously established operation in the production of electrical contacts.

To carry this out, a further object of my invention is to utilize the contact briquette impregnating metal as the bonding material so that the operation of impregnating the contacts will also result in connecting them.

A further object of my invention is to provide a bonding material between the contacts which may easily be ruptured to allow separation between two adjacent contacts, but which material is sufiiciently strong mechanically to maintain the connection until it is affirmatively broken.

My novel bonding process which satisfies the above objects, the connected series of contacts being produced thereby, may more easily be understood by referring to the following description and drawings in which Figure 1 is a side view of a series of contacts prior to bonding.

Figure 2 is a side view of a series of contacts bonded together.

Figures 3 and 4 show plan and side views of the severed contact.

There are several methods by which it is possible to produce the kind of contacts or parts contemplated in this disclosure; these parts being made from metal powders by what is commonly referred to as the impregnation process. A1-

der consisting of a conductive metal, this metal.

being preferably identical to that which will subsequently be used to impregnate the contact, as for example, silver. This. combination is thoroughly mixed, as for example. by. usilng;. a, tumbling process. The powders thus mixed are then inserted into a die cavity of an appropriate size and shape, and compacted'therein'by'apply ing pressure to the die plungers which-1 compact the powder. Thereafter' the compacted material is. sintered. The compacting pressure is soselected that the briquette which is. obtained will havea predetermined percent porosity after it. is sintered subsequent to the compacting opera.- tion.

Theprocess is thencompleted by placing an appropriate quantity of the impregnating ma.- terial, as for instance, silver, upon theporoussintered. compact, and placing the whole, within a furnace and bringing said whole to a temperature in excess ofthemelting point of the impregnating. material. The. impregnating material when thus. melted will flow into. the sintered compact and fill the voids, creating a dense product.v

In connection with this general description. of the methodused tov produce the electrical contacts. of. the type. to. which this. invention is die rected, I will here describe may. novel bonding operation.

As shownin Figure 1, after the. contacts 1 are pressed. and sintered, they are placed upon a support 2, and so positioned that they are, adjacent to and touching each other, and so arranged that. their centers lie along a predetermined path, in. this case said, path being a straigl'itv line indicated by axis line 33. An appropriate size slug 4 of the impregnating material isthenplaced upon each of the compacts i. It is to, be. noted that. the individual slugs 4 of said impregnatingmaterial maybe replaced. by a bar or; rodof any desirable shape, said bar being of sufiicient length to rest upon thetops of all. the combined contacts.

The above, mentioned assembly is-then placed intoa furnace which is held at a temperature sufficient, to melt the impregnating. material and cause itto now and impregnate the, contacts.

Inaddition to impregnating the contacts 1, as heretofore mentioned, the impregnating metal will form .a fillet 5 between any two adjacent, contacts]. as shown in Figure 2; one contact being bondedby this. fillet 5 between the...t,w,o contacts tadjacent tov it.

Thus, the bonding operation has. been combined with the normally required impregnating process, this process heretofore beingoutlined.

Thebonding fillet l is. thus produced with a relatively soft material, namely theimpregnating. metal, suchas. silver or copper. The fillet,

being soft, may easily be rupturedby-an-operator, or. bymechanical means.- associatedwith a positioning fixture. However, the fillet is sufficiently strong so that a strip of a predetermined length, supported horizontally or vertically by one end, will be capable of supporting its own weight. Since the fillet is composed of the impregnating material, it must necessarily be a good conductor, and hence cannot adversely afiect the propertiesbf.the-contact.

I wi l ow be ppar nt-from the above description that when a strip containing a plurality of such contacts I bonded to each other at their tangential engaging point 5 is applied to a reeeptable or jig in a welding machine, a simple roekingmovement oi; the strip while the contact isheldginplace. in; the jig will release the strip f m-this-cpntact; at the tangential point where the contact is secured to the next adjacent end contact:

appropriate fixture and jig for the positioning of the contacts can be constructed or modified so as to utilize the heretofore described combined form of electrical contacts rather than the individual items. It is obvious thatjthere is greater ease in both mechanical and manual handling of the combined form than there is with the. individual contacts.

A jig and fixture combination is conceivable which may better utilize a combined form of'el ectrical contacts in and annular ring rather than the aforementioned strip form. Hence I'wi'shmy invention to cover any shape into which a; plurality of contacts may be formed by my'novel method.

While I have described my invention in connection with a particular composition of an electrical contact, it will now be'obvious that my invention is applicable to. any contact which, can be joined together atian, appropriate point to form a.v strip of a plurality of contacts; Accordingly, I prefer to be bound not by the specific disclosures herein contained, but only by the appended. claims.

I claim:

1..A strip oi silver impregnated.electrical'con tacts; adjacent, contacts being connected by silver fillets.

2. A strip. of electrical contacts impregnated witha conducting metal; adjacent contacts being connected'byfillet's of said impregnating, metal.

3. A strip. of initially porous electrical; con tacts impregnated with a conducting metal; adjacent contacts being connected by fillets .of'tlie impregnating metal.

4. A strip of initially porous electrical cont ts. impr nated. with a conducting. me al; a jacent. contacts being connected by fillets of the impregnatingmetal, each. fillet, extending in tegrally from within one con act. into. an d'- jacent contact.

5.. A strip of conductin powder imp nat d electrical. contacts; adjacent contacts being connected by said conducting powder fillets.

CECIL L. HARVEY.

References Cited in the file of. this patent UNITED. STATES PATENTS- Number Name Date 2,181,083. Fayette Nov; 21, 19.39 2,433,687 Durst Dec. 30, 19.47 2,458,552 Blattner Jan. 11,. 19.49 2,501,164 Durstvv Mar. 21, .1950

Claims (1)

1. A STRIP OF SILVER IMPREGNATED ELECTRICAL CONTACTS; ADJACENT CONTACTS BEING CONNECTED BY SILVER FILLETS.

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