US3384704A - Connector for composite cables - Google Patents

Description

May 21, 1968 w. J. VOCKROTH CONNECTOR FOR COMPOSITE CABLES Filed July 26. 1965 III III/

United States Patent 3,384,704 CONNECTOR FOR COMPOSITE CABLES William Joseph Vockroth, Harrisburg, Pa., assignor to AMP Incorporated, Harrisburg, Pa. Filed July 26, 1965, Ser. No. 474,619 3 Claims. (Cl. 174-90) ABSTRACT OF THE DISCLOSURE A high tensile electrical connector for joining stranded c. bles and having an outer ferrule with a pair of tapered gripping jaw means disposed therein in spaced relationship to the ends of the ferrule. The jaw means grip the core strands of cables for a mechanical connection, and the ferrule is crirnped at both ends onto the conductor strands of the cables for an electrical connection. During crimping, the conductor strands and the ferrule extrude longitudinally and pull the core strands and jaw means into tighter engagement.

This invention relates to a high tensile electrical connector for ACSR cables and a method of applying same.

ACSR cable comprises a steel core strand and a number of aluminum strands surrounding the same in a helical lay. The steel core provides tensile strength for the cable nad the aluminum strands provide electrical current-carrying means.

Heretofore, one type of connector provided for the above composite cables included ferrules with a series of frangible inserts therein which break upon crimping and grip the steel core (note US. Patent No. 3,052,750). The ferrules have duplicate ends and are crirnped along their entire length beginning at their ends and crimping towards the center. The application of this type of connector has the dis-advantage of requiring a large number of crimps.

Some other connectors provide means to grip the steel core strand by crimping through a ferrule and through the outer aluminum strands. This type of connector does not usually provide sufiicient tensile strength for a connection, as the aluminum strands can break or pull out due to excessive tension and vibrations on the cable.

It is therefore an object of the present invention to provide a new and improved connector means for ACSR cable wherein the cable core is gripped separately from the outer aluminum strands.

Another object is that of providing a connector wherein a residual stress is effected between a connector ferrule and the steel core strand so that any axial strain on the cable will tighten the connection.

Another object is to provide an in-line connector which requires less crimping than conventional connectors, thereby reducing bending in the ferrule.

These and other objects and advantages will become apparent when the description of a preferred form of the invention is read in conjunction with the accompanying drawings wherein:

FIGURE 1 is a perspective section view of a connector in accordance with the present invention showing the parts thereof exploded along a centerline;

FIGURE 2 is a longitudinal section view taken through a connector of the present invention prior to cable insertion;

FIGURE 3 is a view similar to FIGURE 2 during cable insertion;

FIGURE 4 is a view similar to those of FIGURES 2 and 3 after crimping;

FIGURE 5 is a transverse section view taken through the lines AA of FIGURE 3;

3,384.74 Patented May 21, 1968 FIGURE 6 is a transverse section view taken through the lines B-B of FIGURE 4; and

FIGURE 7 is a transverse section view taken through the lines C-C of FIGURE 4.

Referring now to the drawings, and particularly to FIGURES 1 and 2, the connector assembly comprises a ferrule member 2, which may be extruded from aluminum, a tapered insert 4, gripping jaws 6 and a spring 8. The insert 4 and gripping jaws 6 are duplicated at each end of ferrule 2 so that two cable ends may be connected to constitute an in-line splice. Spring 8 is centrally disposed in ferrule 2 and adapted to be biased against both pairs of gripping jaws 6. Annular grooves 10 on each end of ferrule 2 retain the parts within the ferrule. Each end of ferrule 2 has a wire lead-in means defined by tapered Opening 12.

Insert 4, which is generally cylindrical in shape, may be formed from aluminum. One end of insert 4 has a wire lead-in means defined by a bell-mouthed opening 14. Directly behind opening 14 is a reverse tapered passageway 16 which continues through the other end 5 of insert 4. Passageway 16 insertably receives tapered gripping jaws 6 through end 5.

laws 6 which are conical shaped and segmented by a longitudinal cut along their centerline have an outside taper 6' to match taper 16 on insert 4. Buttress or threadlike serrations 18 are formed in passageway 16 of insert 4, which serrations 18 serve to grip core S of cables C when the connector is in use. Jaws 6 are biased in passageway 16 by spring 8 when the connector is assembled. Jaws 6 are limited to move longitudinally in passageway 16 by virtue of coacting tapered surfaces 6 and 16 against each other.

In the assembly of the present connector, one end of ferrule 2 is provided with an annular groove 10. A tapered insert 4 with a pair of gripping jaws 6 thereinside is positioned inside ferrule 2 against groove 10. Spring 8 is then placed into ferrule 2 so that its inner end abuts large end 7 of jaws 6.

Another sub-assembly including an insert 4' and pair of jaws 6' is positioned against the other end of spring 8, FIGURE 1, whereafter insert 4' is pushed into the ferrule by an assembly mandrel (not shown) against the bias of spring 8. Another annular groove 10 is formed around the other end of ferrule 2, and the assembly mandrel is withdrawn.

The resulting assembled connector comprises a ferrule 2 having duplicate sets of inserts i and 4' and jaws 6 and 6' biased against two grooves 10 and 10" by a central spring 8.

In operation, the ends of ACSR cables C are prepared by cutting outer aluminum strands and exposing short lengths of steel cores S. A pre-stripped cable C is inserted into one end of ferrule 2 (FIGURE 2) so that core S engages serrated section 18 of jaws 6. During insertion, the jaws 6 are urged longitudinally in passageway 16 against the bias of spring 8 which causes the jaws to spread radially to receive the core S. After the cable is inserted, the spring 8 urges jaws 6 toward the annular groove 10. The tapers 6' and 16 between insert 4 and jaws 6 urge the jaws into gripping engagement with core S. Tension applied to the cable C tightens the gripping action between the jaws 6 and the strands S.

A series of radial crimps 26 is applied to ferrule 2 over the strands of cable C. The first crimp is made at end 3 of ferrule 2, with additional crimps 20 being longitudinally spaced along the connector body, Crimps 20 provide an intimate aluminum-to-aluminum connection between the connector 2 and the conductor C which results in good electrical conductivity. The first crimp causes slight metal extrusion in the ferrule 2 and aluminum strands, and each subsequent crimp thereafter causes additional extrusion. Steel strand S does not extrude during the crimping operation.

During the extrusion caused by crimping, jaws 6 are pulled into tight engagement with steel core S, aided by the bias of spring 8.

The other end of ferrule 2 is connected to another cable in the same manner as described above to constitute a high tensile in-line splice wherein residual stresses from a spring 8 along with tapered inserts and jaws assure a tight connection especially during tension on the cables.

It should be noted that the gripping means shown and described herein may be included in connectors other than in-line splices, e.g. dead end connectors for steel core cables.

It will therefore be appreciated that the aforementioned and other desirable objectives have been achieved; however, it should be emphasized that the particular embodiment of the invention which is shown and described herein, is intended as merely illustrative and not as restrictive of the invention.

I claim:

1. A connector adapted to be secured to aluminum cables having steel core wires comprising an outer ferrule of soft electrically conductive metal, said ferrule having a substantially constant outer diameter, gripping means within said ferrule to grip said core wires and spring means, means within said ferrule to retain said gripping means, said gripping means including segmented tapered jaws with serrated gripping edges on the inner surface thereof, said jaws disposed in cylindrical inserts having rearwardly directed tapered inner surfaces to match a forwardly directed taper onsaid tapered jaws, said gripping means closeable onto said core Wires causing said gripping edges to bite into said core wires, end sections on said ferrule adapted to be secured onto said aluminum cables by a series of crimps, said crimps causing longitudinal metal extrusion of said end sections and said aluminum cable, said extrusion causing said gripping means to tighten onto said core wires, said spring means biased against said gripping means and serving to further tighten the connection, whereby a mechanical connection is made to said core wires and an electrical connection is effected between said connector and said cable.

2. A connector according to claim 1 wherein said cylindrical inserts have bell-mouthed openings in said end sections to receive said core wires.

3. A mechanical and electrical connection between two stranded cables each having a core strand, said connector comprising a connector member including an electrically conductive soft metal ferrule crimped onto aluminum strands of said cables defining said electrical connection, tapered inserts disposed in said ferrule, tapered gripping jaws with serrated inner gripping edges within said tapered inserts, said gripping edges biting into each of the core strands of said cables defining said mechnical connection, spring means, within said ferrule between said tapered inserts biased against said gripping jaws to further tighten said mechanical connection.

References Cited UNITED STATES PATENTS 2,144,050 1/1939 Fotsch 24-126 X 2,859,424 11/1958 Berndt 339-273 DARRELL L. CLAY, Primary Examiner.

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