Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
2000-01-04
2001-07-24
Arbes, Carl J. (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S874000, C029S882000
Reexamination Certificate
active
06263567
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of electrical connectors, and, more particularly, to an electrical connector and associated manufacturing method.
BACKGROUND OF THE INVENTION
Underground and submersible junction bus connectors are widely used in electrical power distribution systems. One type of such connector is offered under the designation SWEETHEART® by Homac Mfg. Company of Ormond Beach, Florida, the assignee of the present invention. The SWEETHEART® connector is a cast or welded aluminum connector including a bus, or bar, portion and a series of tubular posts extending outwardly from the bus portion. The posts have an open upper end to receive one or more electrical conductors. A threaded bore is provided in the sidewall of the post, and which receives a fastener to secure the electrical conductor within the upper end of the post. An insulating coating is provided on the lower portion of the posts and bus of the connector. In addition, EPDM insulating sleeves may be used to provide waterproof seals for the posts.
Unfortunately, the casting method for making such a connector may result in small trapped bubbles which leave internal voids in the casting. The internal voids may reduce the strength of the connector. The surface texture of the cast parts may be relatively rough, thereby requiring additional grinding or finishing steps. In addition, different molds are typically required for the different connector sizes and configurations. Accordingly, casting may be relatively expensive. In addition, a cast part may have a lower electrical conductivity.
U.S. Pat. Nos. 5,766,044; 5,555,620 and 5,608,965 each discloses an alternate approach to casting of the bus and post connector. A hollow-end milling cutter is used to form the entire extent of the upstanding posts from generally rectangular extruded stock material, and while also leaving the bus or bar portion at the base of the connector. In other words, an integrally formed monolithic connector is produced without casting and starting from extruded aluminum stock.
While the hollow-end milling approach offers a number of potential advantages, there are also shortcomings. In particular, a relatively large amount of the starting aluminum stock material must be removed and is therefore wasted. Also, the cost of the aluminum stock may also be relatively high because the stock must have a height dimension that is at least as great as the bus portion and the full height of the posts.
SUMMARY OF THE INVENTION
In view of the foregoing background, it is therefore an object of the present invention to provide a method for making a bus and post connector without casting, and while reducing the waste and other drawbacks of the hollow-milling cutter based approaches of the prior art.
These and other objects, features and advantages in accordance with the present invention are provided by a method preferably including the steps of: selectively removing material from metal stock to form a monolithic body comprising a bus portion and a plurality of spaced apart stubs extending outwardly therefrom; providing a plurality of metal posts, each metal post having a lower open end; and engaging the lower open end of each metal post and a respective stub of the monolithic body together.
The step of selectively removing material may, for example, comprise using a milling cutter. The metal stock may have a generally rectangular shape, or may have a rectangular base with rectangular fingers extending outwardly from the base. The metal stock may also preferably comprise extruded aluminum and may have a relatively compact height dimension substantially equal to a combined height of the bus portion and stub. The starting stock need not be the full height of the posts and bus portion. Accordingly, the advantages of using extruded material versus casting may be obtained without, for example, the shortcomings in terms of excess material waste and associated expense.
The step of selectively removing material preferably comprises selectively removing material so that each stub is frustoconically-shaped. In addition, the step of providing the metal posts preferably comprises providing each with a correspondingly-shaped lower open end for engaging the respective frustoconically-shaped stub. The frustoconical shape may have a taper angle in a range of about 1-5 degrees, for example. Each stub may also have a generally circular cross-sectional shape.
In one embodiment, each metal post may have a bore extending therethrough defining the lower open end and also defining an open upper end for receiving at least one electrical conductor. In this embodiment, the metal post may also have at least one threaded passageway therein and extending transversely into the bore, such as to receive a fastener for securing the electrical conductor in the bore. Also, the metal post may have an increased thickness wall portion through which the threaded passageway extends.
In another embodiment of the invention, the metal post has a different configuration. More particularly, in this embodiment, the metal post comprises an uppermost tab with at least one opening therein for receiving a fastener to secure an electrical conductor.
The method may also include the step of forming an insulating coating on at least the bus portion and lower portions of the metal posts. The step of selectively removing material may comprise selectively removing material so that all of the stubs have a common height. In addition, the step of providing the metal posts may comprise providing at least some of the metal posts with different shapes, such as to accommodate different sized conductors.
Another aspect of the invention relates to the electrical connector. The connector preferably comprises a monolithic metal body comprising a bus portion and a plurality of spaced apart stubs extending outwardly therefrom, and a plurality of metal posts connected to the stubs. Each metal post preferably has a lower open end engaged on a respective stub and an upper end to be connected to at least one electrical conductor. Each stub may be frustoconically-shaped, and each metal post may have a correspondingly-shaped lower open end for engaging the respective frustoconically-shaped stub.
In one embodiment, each metal post may have a first bore extending therethrough defining the lower open end and also defining an open upper end for receiving at least one electrical conductor therein. In another embodiment, each metal post comprises an uppermost tab with at least one opening therein for receiving a fastener to secure an electrical conductor.
The connector also preferably includes an insulating coating on at least the bus portion and lower portions of the metal posts. In addition, the monolithic metal body and the metal posts may each comprise aluminum, although other metals may be suitable as well. In some configurations, at least one of the metal posts may have a shape different than at least one other metal post, such as to accommodate a different sized electrical conductor.
REFERENCES:
patent: 5555620 (1996-09-01), Kies
patent: 5608965 (1997-03-01), Kies
patent: 5611142 (1997-03-01), Kies
patent: 5690516 (1997-11-01), Fillinger
patent: 5766044 (1998-06-01), Norden
Catalog—“Quality Electrical Connectors and Accessories”, The Homac Companies—Industries Division, pp. 30-33.
Allen Dyer Doppelt Milbrath & Gilchrist, P.A.
Arbes Carl J.
Homac Manufacturing Company
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