Solderless Connector Assembly For Cable Shielding Jackets And Method Of Installing The Same

Abstract

A connector assembly and method of making a strong mechanical, solderless, electrical connection to the thin shielding jacket underlying a cable sheath. When employed in combination with a tension strip the connector assembly provides both a grounding connection for the shield and a load transmitting member for the major load forces acting lengthwise of the cable. The connector assembly includes a threaded fastener inserted through aligned holes in the shield and sheath and is employed to clamp the shield and sheath between a pair of wide area shoes with the inner one pressed into firm contact with the shield. Similar connector assemblies anchored to the cable shield and sheath to either side of a splice zone are interconnected by an insulated conductive tension strip to interconnect the two shields and to transfer load forces across the splice zone.

Parent Case Text

This application is a continuation of our application for U.S. Letters Patent Ser. No. 12,820, filed Feb. 2, 1970 entitled Solderless Connector Assembly for Cable Shielding Jackets and Method of Installing the Same.

Description

The present invention embodies improvements in a universal sheath bond and connector assembly disclosed in our copending application for U.S. Letters Patent Ser. No. 765,158, filed Oct. 4, 1968 now abandoned.

The connector and bonding assembly there disclosed possesses many advantages over prior constructions and techniques for making a solderless connection to the thin, highly ductile metal shield jacket customarily employed to shield the conductors of communication and the like cables from foreign flux fields. However, the improved connector assembly provided by this invention is more versatile and provides a far stronger, simpler mechanical connection to the cable sheath than does our earlier construction. More specifically, installation of the improved connector requires but a single or at most, a pair of slits formed lengthwise of the shield and sheath and utilizes aligned openings formed through the shield and sheath through which the connector shank is inserted. The shield and sheath are rigidly clamped between the inner and outer connector shoes to provide an excellent solderless connection to the shield and a positive mechanical connection to the cable sheath. This connection is further strengthened if desired by the use of tangs on one or both shoes which may extend through another pair of aligned openings or abut the end of the sheath or be clamped against the body of the cable to further strengthen the mechanical connection and to prevent rotation of the connector parts about the connector shank. In this manner there is provided an exceptionally high strength mechanical connection to the cable sheath capable of developing substantially the full tensile strength of the sheath. In consequence, a heavy duty grounding connector secured to the connector assembly can be utilized to transmit the tensile load forces in the cable to a suitable anchorage for the cable or to a companion cable sheath on the other side of an associated splice assembly.

From the foregoing it will be appreciated that a particularly advantageous application of the invention connector assembly comprises its utilization to provide a load transfer connection across a splice between two or more different cables or across a splice zone intermediate the ends of a single cable. The completion of a splice between cable conductors necessitates the removal of a portion of the cable sheath and the underlying shield jacket thereby destroying the effectiveness of the sheath in carrying the tension forces acting lengthwise of the cable. If satisfactory means cannot be utilized to bridge the gap between the two cable sheaths then the cable load forces must of necessity be carried by the cable conductors some or all of which may include spliced joints. This is highly unsatisfactory for obvious reasons. The present invention with its high strength positive mechanical connection to the ends of each of the cable sheaths and including a common interconnecting bridging bar serves to transfer all load strains without assistance from the cable conductors and without risk of imposing any strain on the splice connections per se.

If the ends of two different cables are being spliced together, then it is feasible to provide an exceptionally high strength installation of the connector assembly utilizing a single slit in the end of the cable sheath and spaced remotely from the opening in which the assembly stud is mounted. If the splice is being made in a zone intermediate the ends of a previously installed cable, then it may be necessary to form a tongue from the cable sheath by making a pair of slits lengthwise of the sheath. The connector assembly is then assembled in a hole formed through this tongue while the latter is flexed outwardly away from the taut conductors.

It is therefore a primary object of the present invention to provide an improved solderless bonding connector assembly and method for completing a bonding connection to an electrically shielded cable.

Another object of the invention is the provision of a unique, solderless connector for positive high pressure assembly to the shield and sheath jackets of an electrical cable and an improved method of installing the same.

Another object of the invention is the provision of an improved method of providing a high strength foolproof bonding connection to the thin shield jacket of a cable.

Another object of the invention is the provision of an improved cable splice utilizing a high strength electrically conductive bridging connection extending across the splice proper and positively anchored to the severed ends of the shield and sheath jackets to either side of the splice proper.

These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated:

FIG. 1 is an exploded perspective view showing one of the invention connector assemblies and indicating the mode and order of assembling its components astride the end of a cable shield and sheath;

FIG. 2 is a longitudinal sectional view through the end of the cable showing the connector shank and inner shoe in an initial assembly position;

FIG. 3 is an enlarged cross sectional view taken along line 3--3 on FIG. 2;

FIG. 4 is a longitudinal sectional view similar to FIG. 2 but showing the sheath compressed against the cable conductors by servings of high strength tape;

FIG. 5 is a longitudinal sectional view showing the connector assembly fully installed;

FIG. 6 is a cross sectional view on an enlarged scale taken along line 6--6 on FIG. 5;

FIG. 7 is a side elevational view showing a pair of the invention connector assemblies installed and interconnected across a completed cable splice;

FIG. 8 is a cross sectional view similar to FIG. 5 but showing a modified outer connector shoe and the means for clamping the same about the cable;

FIG. 9 is a perspective view of a third embodiment of the outer clamping shoe;

FIG. 10 is a cross sectional view similar to FIG. 8 but showing the modified connector assembly fully installed;

FIG. 11 is a perspective view of the inner shoe of the FIG. 10 assembly; and

FIG. 12 is a perspective view showing the cable sheath and shield formed with a pair of parallel slits and a mounting hole for the connector assembly spaced centrally between the opposite ends of the two slits.

Referring initially and more particularly to FIGS. 1-4, there is shown one illustrative embodiment of the invention connector assembly designated generally 10. This assembly comprises a threaded shank 11 having a thin wide area head 12 staked or otherwise rigidly secured thereto. Desirably, head 12 is generally triangular in shape and arched crosswise along a radius conforming generally to the curvature of the cable for which it is designed. Usually the assembly includes a thin resilient shim plate 13 having the same size and configuration as head 12 and formed with a hole 14 fitting loosely over shank 11. Shim 13 is formed with dimple-like openings 15 having sharp burrs 16 projecting outwardly from their outer rim edges. These burrs serve to cut through any insulative film often present on the cable shielding jacket.

The cable shielding jacket 18 is usually formed of a thin aluminum or the like ductile electrically conductive material. It is seldom more than a few mils thick and has low mechanical strength but is highly effective as an electrostatic flux shield. This shield is normally enclosed and protected by a thick high-strength cable sheath 20 of tough abrasion resistant non-conductive elastomeric material such as a tough thermoplastic material.

Connector assembly 10 includes an outer pressure or clamping shoe 22 of generally triangular configuration and arched crosswise similarly to inner shoe 12. A central hole 23 fits loosely over shank 11 and the pointed apex end of the shoe is preferably formed with an out turned threaded tang 24 supporting a lock nut 25. Clamping plate 22 may be formed with quite short down-turned tangs 26 (FIG. 5) which bite into the cable sheath as the connector assembly is being tightened during installation. The remaining parts of the connector assembly include an inner clamping nut 27, a lock washer 28 and an outer clamping nut 29.

The described connector assembly may be installed in several different ways, a first mode being illustrated in FIGS. 1-5. The first step is to slit both sheath 20 and the shielding jacket 18 longitudinally of the cable for a distance of several inches as is indicated at 30. The opposite edges of this slit are spread apart as indicated in FIGS. 1 and 2 thereby permitting the cable conductors 32 to be flexed outwardly between the expanded edges of the slit. While the conductors are held in this position aligned holes 33 are formed through the sheath and shield either by a hand punch or a drill of a size to have a snug fit with connector shank 11. This shank along with the attached inner shoe 12 and shim 13 are inserted outwardly through aligned openings 33. Desirably shim 13 is preferably arched to a greater degree than shoe 12 in order that the shim will be flattened as the parts are tightened together. This flattening of the shim causes burrs 16 to scratch through any protective film on the shielding jacket and to form numerous excellent electrical contacts with the shield. Thereafter, the conductors 32 are pulled back into alignment with the main body of the cable in order that the expanded edges of slit 30 can be compressed together. While so held compressed, the cable sheath is served with multiple convolutions of high strength friction tape 35 beginning in an area to the left of slit 30 as viewed in FIGS. 2 and 4. This tape is highly effective in holding the sheath restored to its former position snugly against the underlying cable conductors 32.

The next step in the assembly operation is to place the outer clamping shoe 22 over shank 11 and clamp it rigidly in place against the cable by tightening nut 27. When this has been accomplished both the shielding layer 18 and cable sheath 20 are held firmly clamped under high pressure between the inner shoe assembly 12, 13 and the outer clamping shoe 22. This high clamping pressure together with the large surface areas of the two clamping shoes provides an extremely strong mechanical connection of assembly 10 to the cable sheath and a foolproof solderless electrical connection to shielding jacket 18.

Assembly 10 may be used to transmit the normal load forces acting lengthwise of a cable to a suitable anchorage by assembling a conductive tension strip 40 to shank 11. Strip 40 is provided with a series of closely spaced holes 41 seating freely over the end of the shank and so spaced that one of them registers with threaded tang 25 of shoe 22. Lock washer 28 is then assembled to the shank along with the clamping nut 29 and the latter is firmly tightened. But 25 is also assembled to tang 24 to provide an additional load carrying connection to strip 40.

Desirably connector assembly 10 as well as major body portions of strip 40 are enclosed in an insulative jacket 43 and its ends are enclosed by appropriately contoured boots 44,44 of suitable flexible plastic material. Booth 44 includes a flattened tubular projection 45 having a snug fit about insulation 43 and its open side facing toward the cable sheath fits snugly about the edges of clamping shoe 22.

FIG. 7 illustrates a pair of connector assemblies 10 concealed beneath the insulative boots 44,44 to either end of a completed cable splice zone 50. It will be understood that each of the boots 44 encloses a connector assembly installed in the manner described in detail above and illustrated in FIGS. 1-6. After completion of the splice connections the latter are wrapped with a protective covering and thereafter the ends of strip 40 are assembled over a respective connector shank 11,11 as boots 44,44 are held flexed outwardly away from the cable. After the strip has been clamped in assembled position the two boots are released and allowed to resume their normal positions seated about the edges of the clamping shoes 22.

Referring now to the modification shown in FIGS. 8 and 9, it will be understood that the same or similar components to those just described are designated by the same reference characters distinguished by a prime. The principal change involves a modified outer clamping shoe 22' having a long anchor tang 55 projecting from its wider end and terminating in an upturned tang 56. Any suitable clamping band 57 is assembled over tang 55 and about the cable and secured firmly in place by an adjustable tensioning screw 58.

As will be readily evident from a consideration of FIG. 8, the presence of tank 55 and clamp 57 aids very materially in strengthening the connector assembly and its anchorage to the cable. Additionally, it prevents any tendency of the inner or the outer shoe to rotate about shank 11' and provides a strut resisting tilting of the connector shank under load. Although tang 55 and clamp 57 are shown as located beyond the end of the cable sheath, it will be understood that the stabilizing anchorage so provided may be located at the opposite end of clamping shoe 22' with the clamp encircling the cable sheath.

FIGS. 10 and 11 show still another variant of the connector assembly designated generally 10", wherein the inner clamping shoe or head of the connector 12" includes a pair of out turned tangs 60,61 at its opposite ends. Tang 60 projects outwardly across the wider heel end of clamping plate 22" whereas tang 61 projects through an opening 63 in clamping shoe 22" and through aligned openings 64 in shield 18" and cable sheath 20".

From the foregoing it will be appreciated that connector assembly 10" is a particularly strong one because both the connector shank 11" and tang 61 of inner shoe 12" project through aligned openings in the cable sheath and shield. Also the double tangs 60,61 carried by the inner shoe interlock mechanically with the outer clamping shoe.

Referring now to FIG. 12, still another mode of assembling connector assembly 10 to a cable sheath and shield is illustrated. The principal difference here resides in the provision of a pair of parallel slits 30a,30b extending lengthwise of shield layer 18a and cable sheath 20a. The two sets of slits provide a flexible tongue 67 from the shield and sheath in the central portion of which aligned openings 33a are formed to receive the connector shank 11. The provision of the two sets of slits 30a,30b permits tongue 67 to be lifted away from the cable conductors so that the shank can be inserted from the underside of the tongue. This mode of assembly is expedient in instances where the cable has already been installed and is under tension. Under these conditions it is generally not possible to flex the conductors away from the shield in the manner illustrated in FIGS. 1 and 2. However, by forming a pair of slits and a tongue, the latter can be lifted away from the tensioned conductors for insertion of the connector shank. Once the latter has been installed the tongue is pressed back against the conductors and secured in place by servings of tape 35 in the same manner described above.

While the particular solderless connector assembly for cable shielding jackets and method of installing the same herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, it is to be understood that it is merely illustrative of the presently preferred embodiment of the invention, and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.

Claims

We claim:

1. That method of forming a positive electrical and a high strength mechanical connection to a cable metal shield jacket and a surrounding cable sheath which comprises: forming juxtaposed slits in said sheath and shield lengthwise of their respective ends, forming aligned holes through said sheath and shield in an area spaced to one side of said slits and between the opposite ends thereof, inserting the shank of a headed fastener through said holes from the inner ends thereof, placing a clamping shoe and fastener means over the outer end of said fastener shank and tightening said fastener means thereagainst to clamp said sheath and shield rigidly together with the fastener head electrically connected with said thin metal shield and said clamping shoe applying high pressure to the exterior side of said sheath.

2. That method defined in claim 1 characterized in the steps of forming two sets of juxtaposed slits in said sheath and shield generally parallel to one another lengthwise of the cable and spaced to either side of said aligned holes for said fastener shank, said sets of slits forming coextensive elongated tongues from said cable sheath and shield respectively extending lengthwise of said cable.

3. That method defined in claim 1 characterized in the steps of utilizing a fastener shank having an elongated attached head arched crosswise of its longer dimension in general conforming with the curvature of the cable shield so as to have wide area bearing contact therewith when clamped against the interior side of the shield.

4. That method defined in claim 3 characterized in the steps of forming said elongated fastener head with a short tang projecting in the same direction and parallel to said shank, and forming a set of aligned holes through said sheath and shield positioned to seat said tang when said shank is inserted into said first mentioned aligned holes.

5. That method defined in claim 3 characterized in the steps of forming said elongated fastener head with a short tang normal to the inner side thereof and positioned to project outwardly across the end edges of said sheath and shield when said shank is assembled into said aligned holes, and said tang cooperating with the end edges of said sheath to prevent rotary movement of said fastener head during tightening of said clamping nut.

6. That method defined in claim 4 characterized in the steps of forming said elongated fastener head with a second short tang diametrically opposite said first mentioned tang and positioned to extend outwardly and closely parallel to the adjacent end edges of said sheath and shield.

7. That method defined in claim 1 characterized in the steps of forming said clamping shoe with a short threaded tang projecting outwardly away from the cable sheath, and providing said tang with a nut for use in clamping an electrical conductor thereto.

8. That method defined in claim 7 characterized in the step of utilizing a metal strip for said electrical conductor and formed with a multiplicity of holes spaced for simultaneous assembly over said shank and said threaded tang.

9. That method defined in claim 1 characterized in the step of providing said shank with annular groove means, having interlocking engagement with cooperating means on said fastener means and effective to hold said sheath and shield compressed under pressure between said shoe and said fastener head.

10. That method defined in claim 1 characterized in the step of providing said shank with a thread and utilizing fastener means having a thread mating with the thread on said shank.

11. That method defined in claim 1 characterized in the step of utilizing fastener means of said shank which can be loosened and retightened at the user's option.

12. That method defined in claim 1 characterized in the step of utilizing a plurality of sharp metallic burrs between the surface of said headed fastener and said shield and effective to penetrate into said shield as said fastener means is tightened to assure electrical contact between said shield and shank and to strengthen the mechanical connection of said shield to said headed fastener.

13. That method of making a solderless electrical connection to a cable shield jacket sandwiched between the cable conductors and an insulative sheath therefor, which method comprises: slitting the sheath and the shield jacket lengthwise of the cable to permit expanding a length of each away from the conductors, forming an opening through the sheath and the shield inwardly from the end of the slit portion thereof, inserting metal fastener means having a large area head through said openings from the inner ends thereof with said head lying against the inner face of said shield jacket, clamping the slit portion of said shield and sheath snugly closed against said conductors, and applying a wide area clamping member over said metal fastener means exteriorly of said sheath and securing the same to said fastener means in a manner to provide a strong mechanical anchor between said fastener means and the cable sheath with the head of the fastener means firmly pressed in electrical contact with the cable shield jacket.

14. That method defined in claim 13 characterized in the step of forming a pair of slits lengthwise of said shield jacket and cable sheath to form a tongue, and locating said opening for said fastener means between said pair of slits and intermediate the opposite ends of said tongue.

15. That method defined in claim 13 characterized in the steps of forming a single slit lengthwise of said sheath and of said shield jacket, and locating said opening for said fastener means in an area spaced inwardly from the adjacent end of the sheath and laterally from said slit.

16. That method of mechanically and electrically interconnecting the shield jackets of cabling on the opposite sides of intervening splice connections to the cable conductors which comprises: removing a length of the cable sheath and the underlying shield jacket to expose the cable conductors for making splice connections, forming at least one set of slits lengthwise of the sheath and shield at either end of the exposed length of conductors, inserting the shank of a large headed fastener outwardly through aligned holes through the sheath and shield and spaced laterally from and intermediate the opposite ends of each of said sets of slits, clamping a pressure shoe over the outer end of each of said shanks to compress the associated sheath and shield between the head and pressure shoe of one of said fasteners, and clamping the opposite ends of a conductive tension strip between the outer ends of said two shanks to form an electrical connection between the respective cable shields and a load-transmitting mechanical connection between the cable sheaths to either end of the exposed cable conductors.

17. That method defined in claim 16 characterized in the steps of enclosing the portion of said tension strip between said shanks with insulation, and providing the outer ends of said shanks and the adjacent end of said tension strip with a resilient boot having an open lower side normally seating against and closed by the underlying surface of the cable sheath.

18. That method defined in claim 16 characterized in the steps of providing said pressure shoe with an extension shaped to bear against the cable in an area spaced lengthwise of the cable from said shank, and clamping said extension to the underlying portion of the cable to strengthen the mechanical connection of said shank to said sheath and to reduce the strain of the connection to said shield jacket.

19. In combination with a cable having a metal shield jacket enclosed with a non-conductive high strength sheath, a solderless connector assembly providing a high strength mechanical and electrical connection to said sheath and to said shield jacket, said connector assembly having a shank secured to a large area head bearing against the inner side of said shield with said shank projecting outwardly through aligned openings spaced inwardly from the end of said shield and sheath, and outer clamping shoe means assembled over the outer end of said shank and effective to hold said sheath and shield jacket tightly clamped together with the outer end of the shank available for connection to a load transmitting member and to electrically conductive means.

20. The combination defined in claim 19 characterized in that said sheath and said shield have at least one set of juxtaposed slits extending lengthwise of said cable to one side of said shank to facilitate temporary separation of the sheath and shield from the conductors while assembling said shank in said aligned openings.

21. The combination defined in claim 20 characterized in the provision of high strength servings about said cabling to either side of said shank to hold the sheath snugly contracted against the cable conductors and the edges of said slits closed together.

22. The combination defined in claim 19 characterized in the provision of a short tang on the head of said shank projecting radially outwardly through aligned openings in said shield and sheath and cooperating with said shank in holding the shank and its head against rotation.

23. The combination defined in claim 19 characterized in the provision of short tang means on the head of said shank projecting radially outwardly and in close abutment with the end of said sheath and cooperating therewith to prevent rotation of said shank about its axis.

24. The combination defined in claim 19 characterized in that said shank is threaded and provided on its outer end with threaded nut means wrenchable to compress a large area of said sheath and shield jacket compressed between the large area head of said threaded shank and said outer clamping shoe means.

25. The combination defined in claim 19 characterized in the provision of a plurality of small sharp metallic burrs between said shield jacket and the large area head of said shank and effective to penetrate the surface and make a strong mechanical and electrical connection to said shield jacket as said clamping shoe means is tightened.

26. The combination defined in claim 19 characterized in the provision of arched metallic shim means generally coextensive in size with said fastener head and having a multiplicity of sharp burrs protruding therefrom and positioned to scratch the surface of said shield jacket as said arched shim means is flattened as said clamping shoe means is being clamped into its fully assembled position.

27. The combination defined in claim 19 characterized in that said clamping shoe means is elongated and formed with threaded tang means positioned to engage an edge of a cable clamping band encircling the cable and embracing said clamping shoe means in an area thereof located between said shank and said tang means, said tang means and said clamping band reinforcing the anchorage of said connector assembly to said cable and preventing the latter from rotating about the axis of said aligned openings.

28. The combination defined in claim 27 characterized in that said clamping shoe means is elongated with one end thereof projecting beyond the end of the cable sheath and lying closely against the underlying exposed cable conductors, and clamping band means encircling said exposed conductors and embracing the adjacent end of said clamping shoe means.

29. The combination defined in claim 28 characterized in that said clamping band and said clamping shoe means include means engageable with one another to hold said clamping band against movement lengthwise of said clamping shoe means when properly assembled to one another.

30. The combination defined in claim 19 characterized in that said outer clamping shoe means has tang means projecting outwardly therefrom and spaced from said shank, and strip-like conductor means having separate holes spaced for registry over said shank and over said tang means respectively, and nut means mounted on said threaded tang means for holding said conductor means against disassembly therefrom.

31. That improvement in a cable splice assembly having a short length of its metallic shield jacket and of its outer protective non-conductive sheath removed to expose a length of the cable conductors, said improvement comprising a high strength mechanical and electrical connection bridging the exposed conductors and connected with the severed ends of the shield and sheath to relieve the exposed conductors and splice connections of strain while providing an electric path between the two shields, said improved connection including a strong conductive tension strip bridging the exposed conductors and spaced closely beside the latter, similar metallic clamping means secured to either end of said strip, said clamping means including a threaded shank extending through aligned openings spaced inwardly from the end of said sheath and shield at either end of said exposed conductors and cooperating with clamping inner and outer shoe means to clamp said sheath and shield therebetween, and means clamping the opposite ends of said tension strip to the adjacent one of said threaded shanks and effective to interconnect the same electrically and mechanically and effective to transmit tension forces between the cable ends being spliced together independently of the individual spliced conductors.