Method And Means For Connecting Cable Shielding

Abstract

A metal strip connector with a convex pronged surface is inserted under the shielding of a cable, pulled forward to cause the prongs to pierce the shielding and the free end folded back over the jacket and bound down, thus locking the prongs in their piercing position. The extreme free end of the connector is formed into a loop that is pressed onto the flexible conductor of a harness.

Description

BACKGROUND OF THE INVENTION

In the telephone industry there has been recent widespread use of cables, such as that described in U.S. Pat. No. 3,459,877, assigned to the present assignee, in which the shielding bonds firmly to the jacket. This has the result that the outer surface of the shielding is not available for making electrical connections, and conventional means for assuring shielding continuity when cables are joined cannot be employed. It remains essential, however, that electrical connection to the cable shielding should be made, that it should have high electrical conductivity, be easy, inexpensive, and fast to install, and have long life and positive reliability during this life. It is highly desirable that connections should be made without special tools, other than those carried normally by telephone installation crews.

SUMMARY

In my method for making an electrical connection to a cable shielding, I take the steps of preparing a metal strip connector that is curved across its short dimension for a substantial portion of its length from one end and has a plurality of prongs projecting outwardly of the curved portion with points directed toward the opposite end. Then I connect the end, facing the points of the prongs, of the strip connector to a conducting strand and, subsequently, insert the curved portion of the connector into the cable directly under the shielding. Thereafter I urge the connector longitudinally of the cable so that the prongs pierce the shielding, and thereafter I fold the connector strip back over the jacket, locking the prongs in their piercing position. Finally I fasten the folded portion down, most simply, with wrappings of adhesive tape. By my method two cables are joined by forming a splice between the cable conductors, fastening one of my strip connectors to each end of a conducting strand, inserting the curved, pronged ends of the connectors, one under the shielding of each cable, urging the connectors longitudinally so that the prongs pierce the shieldings, and folding the strips back and taping them down so as to lock the prongs in their piercing position.

My connector comprises a metal strip with a substantial curved portion extending from one end of the strip. This portion is curved across its short dimension and a flat portion of the strip extends from the curved portion. A plurality of prongs project outwardly and are pointed toward the flat portion which comprises a closed conductor-receiving loop at the end remote from the curved portion. A bonding harness of my invention comprises a length of insulated conductor with bared portions at each end and one of the strip connectors of my invention compressed onto each of the ends of the conductor.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a perspective view of a strip connector of my invention.

FIG. 2 shows a view, from the curved end, of the connector of FIG. 1.

FIG. 3 shows a perspective view of a harness of my invention.

FIGS. 4a--4f show the steps of a method of my invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

Referring first to FIGS. 1 and 2 of the drawing, a strip connector, indicated generally by the numeral 10, has a short dimension 11 and a long dimension 12 which is divided into a curved portion 13 and a flat portion 14. The curvature of the portion 13 which is curved across the dimension 11 can best be seen in FIG. 2. A double row of sharp pointed prongs 16 have been stamped into the portion 13 to project outwardly, i.e., away from the center of radius of the curvature, in the portion 13. The flat portion 14 constitutes a substantial fraction of the total dimension 12 extending from line 17 which marks the end of the curvature and a slight upward bend in the strip. The portion 14 terminates in a closed loop 18 large enough to receive a conducting strand. Importantly, an end 19 of the loop 18 is folded around under an underface 21 of the connector 10, I have found that when a full loop 18 is formed no soldered seam to close the loop 18 is required although the loop can be soldered or brazed, at extra cost within the scope of my invention.

Each of the prongs 16 terminates in a sharp point 23 directed outwardly and generally in the direction of the flat portion 14.

In the practice of the method of my invention a supply of the connectors 10 are prepared, and a harness, indicated generally by the numeral 25 (FIG. 3), is formed by pressing one of the connectors 10 to each end of an insulated stranded conductor 24 from which insulation 26 has been stripped from each end to expose bared conductor lengths 27, 28. The size of the metal strands forming the lengths 27, 28 is such that they fit easily into the loops 18 of the connectors but substantially fill these loops so that good and permanent electrical connections can be made by pressing the loops down upon the strands. This can be done with conventional tools. The metal used for connectors 10 must take a permanent deformation without cracking or becoming brittle and I have found that brass, which may be cadmium plated, is particularly suitable. Solder is not needed for the compressed connection since the compression of the closed loop 18 assures a good compression fit.

The cable for which my connection is particularly adapted can be seen in FIG. 4d to be comprised of a plurality of insulated conductors 29 within an overall jacket 31 to which is internally bonded a shielding layer 32 of aluminum, copper or other suitable metal or combination. Because of the bonding of the shielding 32 to the jacket 31 to the outer surface of the shielding is not readily available for electrical contact. To make a connection between two cables 33, 34 (FIG. 4a), in the method of my invention, the jackets 31 and attached shielding 32 are stripped back to expose lengths 36, 37 of the conductors 29 (FIG. 4b). Thence the conductors 29 of the two cables are spliced in a known manner (FIG. 4c), and (FIG. 4d) the curved ends of the connectors 10 which have been pressed onto the conductor 24 are inserted under the shieldings 32 of the cables 33, 34 with the curve of the connector more or less matching the curvature of the cable jacket. As shown in FIGS. 4d and 4e the conductors 29 are surrounded by an inner sheath 38, and when the connectors 10 are inserted they are easily inserted by hand between this sheath and the shielding 32, up to the line 17. The connectors are then pulled by hand (FIG. 4e) toward each other to force the prongs 16 to pierce the shielding 32 which they do because of the outward and backward direction of the points 23. The flat portion 14 of the connectors is then folded back (as shown in FIG. 4f) over the jackets 31 of both the cables 33 and 34 and pressed firmly down upon the jacket surfaces. This folding has the effect of locking the prongs 16 in their piercing position with their points 23 in the stock of the jacket 31. In order to bite firmly into the shielding the prongs 16 must not only be sufficiently long but must be undercut to provide an area 22 under the points 23 for the accommodation of shielding material and jacket stock when the connector is pulled forward to cause the piercing action. The insertion of the connector under the shielding should be far enough so that, after the shielding has been pierced, a cut edge 35 (FIG. 4d) of the shielding 32 and jacket 31 is in contact with the flat portion 14 of the connector with the result that the connector will bend easily and firmly against the edge 35 to effect the locking action.

The portions 14 are then bound down over the cables by means of a plurality of turns 39 of adhesive tape as shown in FIG. 4f. In open locations a conventional splice enclosure can be applied over the entire splice or the whole connection can be taped in a conventional manner, not shown.

Although, my method, connector and harness have particular advantages as described, where the cable shielding is bonded to the jacket, their use is not limited to such cables but has been successfully applied to cables where the shielding is not bonded to the jacket, and although I have shown the application of my invention to a cable with an inner sheath 38, the presence of such a sheath is by no means necessary for the successful attachment of my connector so long as it can be inserted between the core and the shielding.

Claims

I claim:

1. The method of making an electrical connection to the shielding of a cable comprising the steps of:

A. preparing a metal strip connector curved across its short dimension for a substantial portion of its length from one end thereof, and having a plurality of prongs projecting outwardly of the curved portion with points directed toward the opposite end,

B. mechanically and electrically connecting the end, facing said prongs, of said strip connector, to a conducting strand,

C. inserting said curved portion of said connector into said cable directly under said shielding,

D. urging said connector lengthwise of said cable so as to force said prongs to pierce said shielding,

E. folding a substantial portion of said connector back over said jacket so as to sandwich said shielding and said jacket between said curved and folded portions of said strip connector, and lock said prongs in their piercing positions, and

F. fastening said folded portion down upon said cable.

2. The method of claim 1 wherein said fastening step comprises wrapping adhesive tape around said cable and said folded portion of said connector.

3. The method of joining the shielding of two cables, comprising the steps of:

A. preparing two metal strip connectors, said connectors each being curved across its short dimension for a substantial portion of its length from one end thereof and having a plurality of prongs projecting outwardly of said curved portion, said prongs having points directed toward the opposite end,

B. mechanically and electrically connecting the ends of said strip connectors facing said prongs to two ends of a conducting strand,

C. splicing the conductors of said cables,

D. inserting the curved portions of each of said connectors into a different one of said cables directly under said shielding,

E. urging said connectors lengthwise of said cables so as to force said prongs to pierce said shieldings,

F. folding a substantial portion of each of said connectors back over the jacket of the cable attached thereto, so as to sandwich said shielding and said jacket between the curved and folded portions of said strip connectors and lock said prongs in their piercing positions, and

G. fastening said folded portions down against said cables.

4. The method of claim 3 wherein said fastening step comprises wrapping adhesive tape around said cables and the folded portions of said connectors.

5. A connection between two cables, each comprising a plurality of insulated conductors, an overall jacket, and a metallic shielding layer bonded to said jacket, comprising:

A. means splicing the conductors of one of said cables to the respective conductors of the other of said cables,

B. at least two connectors comprising metal strips, each comprising a plurality of prongs distributed over at least a substantial portion of said strip, said portion, comprising said prongs of one of said strips, being inserted directly under said shielding layer of one of said cables, and said portion, comprising said prongs of another of strips, being inserted directly under said shielding layer of the other of said cables, said prongs piercing said shielding layers and making electrical contact therewith, portions of said strips being folded back over said jackets so as to grip the combined shielding layer and jacket of each of said cables between the folded portions of said strips,

C. a plurality of turns of tape wrapped around each of said folded back portions of said strips and its attached cable, binding said portions back against said jacket, and locking said connectors to said cables, and

D. a metallic conductor electrically connecting together the ends of said folded back portions, thereby electrically connecting said shielding layers.

6. The connection of claim 5 wherein said metallic conductor is insulated and stranded.