US3564116A

US3564116A - Splice for laminated tapes

Info

Publication number: US3564116A
Application number: US822370A
Authority: US
Inventors: Joseph B Masterson; John D Lawler
Original assignee: General Cable Corp
Current assignee: General Cable Corp
Priority date: 1969-05-07
Filing date: 1969-05-07
Publication date: 1971-02-16
Anticipated expiration: 1988-02-16
Also published as: JPS4936754B1; GB1295624A; CH524874A; ES377460A1; FR2042956A5; DE2021397A1

Abstract

Shielding tapes around the cores of electrical cables are connected together by an electrically conductive strip placed between overlapping ends of the shielding tapes and with tangs projecting from both sides of the strip for piercing the corrosion-preventing coating on the tapes and establishing metalto-metal contact with the overlapping ends of the tapes to provide the tapes with electrical continuity and to mechanically lock the tapes from axial movement relative to one another.

Description

United States Patent inventors Joseph B. Masterson Carteret, NJ John D. Lawler, Bayonne, NJ. Appl. No. 822,370 Filed May 7, 1969 Patented Feb. 16, 1971 Assignee General Cable Corporation New York, N.Y. a corporation of New Jersey SPLICE FOR LAMINATED TAPES 14 Claims, 6 Drawing Figs.

US. Cl 174/88; 29/628: 174/84; 339/95; 339/97 Int. Cl .H01r 9/06; 1-102g 15/08 Field ofSearch 174/84, 88,

[56] References Cited UNITED STATES PATENTS 3,205,299 9/1965 Dickie 174/84 3,377,422 4/1968 Trimble et al. 174/88 3,435,126 3/1969 Hamilton 174/78 Primary Examiner- Darrell Clay Attorney- Sandoe, Hopgood & Calimafde PATENIEuFEBismn 131564.116

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1 SPLICE FOR LAMINATED TAPES BACKGROUND AND SUMMARY or THE INVENTION This invention relates to the providing of an electrical connection between two composite electrical tapes used as a shield, or a moisture barrier in electrical cables. The problem of providing electrical connection to the tape without damaging 'other properties of the tape, is significant. Conventional means for removing the insulation from the metal of the tape, spot-welding the metal, and then recoating the denuded area with an insulation, is time consuming and can not completely restore the integrity of the tape. Inthe cases where thin metal such as foil is employed in the tape fabrication, the removal of insulation is virtually impossible for production methods.

This invention connects the overlapping ends of shielding tapes together by placing between their overlapping ends a strip connector of a metal having good electrical conductivity and having tangs punched substantially perpendicular to each face of the metal strip. The tang length is regulated by the diameter of the punched hole and'the metal thickness. It can, therefore, be designed to penetratethrough various depths of insulation to make contact with the metal of the insulated shielding tapes but not necessarily piercing or breaking the metal.

The overlapping ends of the shielding tapes, with the strip connector between them, are held together under heat and pressure which causes the plastic coatings on the tapes to melt andflow around the connector strip, completely encapsulating the connector in the splice overlap and making a hermetically sealed electrical and mechanical connection between the tapes. The connector strip itself can be punched from either polyethylene-coated metal or bare metal. In cases where the shielding tapes have a minimum thickness of plastic coating, it is preferable to use a connector strip made from coated metal so as to insure a hermetic seal. Connectors of this invention inserted in overlapped tape splices, have shown a contact resistance of approximately l-, ohms. The connector strips of this invention, when used with an 8 milaluminum tape having a 2 mil coating, will withstand high-current application which causes the aluminum tape itself to fuse with no change in the contact resistance of the splice. Heat-sealed overlapped splices with the connectors of this invention, when subjected to tensile strength, do not fail at the splice area. The tape itself fractures at an area remote from the splice.

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

DESCRIPTION OF THE DRAWING In the drawing, forming a part hereof, in which like reference characters indicate corresponding parts in all the views:

FIG. 1 is a diagrammatic view of an. electrical cable having shielding tapes spliced together withla connector element made in accordance with this invention;

FIG. 2 is an enlarged diagrammatic sectional view taken on the line 2-2 of FIG. 1;

, FIG. 4.

DESCRIPTION OF PREFERRED EMBODIMENT FIG. 1 shows a cable having a shielding tape 12 along oneportion of the cable, spliced to'another shielding tape 14 which extends along another portion of the cable. Each of the dinally folded around a cable core 16 and has a longitudinal lap seam 18.

The end of the tape 12 is indicated by the reference character 22 and the end of thetape 14 is indicated by the reference character 24. Within the area of overlap of the

tapes

12 and 14, i.e., between the

ends

22 and 24, there is a strip or tape connector, hereinafter referred to as a connector element 30.

The connector element 30 eittends circumferentially around the outside of the tape 12 and under the overlapping portion of the tape 14. For purposes of clearer illustration, the thicknesses of parts are greatly exaggerated in the drawing and in actual practice the thickness of the

shielding tapes

12 and 14, including the plastic coating on the tapes, is between 6 and 16 mils.

The connector element 30 is made from sheet metal having a thickness somewhat greater than the thickness of the metal foil of the shielding tapes l2 and 14 in order to obtain tangs of sufficient strength for its intended purpose. In the preferred construction the connector element 30 is made from material having a thickness between 1 and 10 mils.

FIG. 4 shows the way in which'the connector element 30 is formed with

openings

32 and 34 having metal displaced from the openings bent substantially perpendicular to the rest of the connector element 30 to form tangs 36. Some of the tangs 36 extend upwardly from the body of the connector element 30, as shown around the opening 32; and others of the tangs 36 are bent downwardly, as shown around the opening 34. There are preferably an equal number of openings having tangs bent inwardly as compared to those having tangs bent outwardly so that the connector element will cooperate equally with the shielding tapes above and below it.

The length of each of the tapes 36 is substantially equal to the radius of the: opening from which the tangs are displaced. FIG. 5 shows a connector element 304 with an opening 32b having upwardly extending tangs 36a and shows another opening 34a with downwardly extendingtangs 36b. The tangs 360 are long enough to penetrate the coating on the shielding tape which will contact with the upper end of the connector element 30a of FIG. 5 and the tangs 36b are long enough to penetrate a coating which will contact with the lower side of the connector element 30a.

FIG. 3 shows the connector element 30 assembled with the shielding tapes l2 and 14. The shielding tape 14 is shown with a thin outer coating of plastic 41, a metal foil strip 42, preferably aluminum, and a lower plastic coating 43 of greater thickness than the outer coating 41. The shielding tape 12 has a thin inner coating 47, a metal foil strip 48 and a thicker inner coating 49.

Both of the coatings 43 and 47 which confront the connector 30 are of different thickness and, therefore, the connector 30 has the

tangs

36 and 36, which project from its opposite surfaces, of difierent lengths as shown in FIG. 4. 1

Referring again to FIG. 1, the connector element is shown 7 with angularly spaced rows 54 of

openings

32 and 34. Rows of openings 32, with upwardly extending tangs 36, alternate with rows of openings 34 having downwardly extending tangs 36'.

For greater convenience in manufacturing, all of the openings of each alternate row have their tangs extending in the same direction, but other arrangements can be used and staggered relations of the opening can be substituted for the rows shown in the preferred embodiment.

In FIG. 3, the left-hand opening 32 is shown with the tangs 36 piercing the plastic coating 43 to contact with the bare metal of the foil 42. The drawing shows the tangs 36 indenting the foil 42 and displacing some of the foil at the indents as indicated by the humps '56 on the side of the foil opposite the tangs. This prevents relative movement of the shielding tape 14 axially with respect to the connector element 30 and also with respect to the other shielding tape 12 which is similarly locked to the connector element 30 by tangs which extend downwardly from the opening 34.

This left-hand opening 32 in FIG. 3 has the plastic 43 'of the tape 14 substantially filling the space between the tangs, and this is the condition that exists after the tangs have pierced through the plastic. For clearer illustration, however, showing the tangs 36 other than those in the plane of section, the plastic that is actually between the tangs 36 of the right-hand opening 32 and the tangs 36' of the opening 34 is broken away to expose the tangs on the far sides of these openings; and to show the way in which those tangs also dent the

metal foils

42 and 48, respectively, to increase the area of contact for the electrical connection and to anchor the connector element 30 to the

tapes

12 and 14, and thereby splice the tape together.

The degree to which the tangs 36 indent the

metal foils

42 and 48 is a matter of choice. It depends largely upon the length of the tangs 36 with respect to the thickness of the coatings 43 and 47, and to some extent upon the pressure with which the outer tape 12 is pressed against the connector element 30, and the resulting pressure of the connector element 30 against the tape 14. The tangs must touch the

metal foils

42 and 48. In order to have a splice which is as strong or stronger than the

tapes

12 and 14 in axial tension, the tangs should dent the

foils

42 and 48 for a depth at least equal to approximately the thickness of the foil. In the preferred embodiment, construction, the foil thickness is about .7 mils. It is desirable to have it within the range of from 0.5 and 8.0 mils.

The tangs 36 can be made to pierce openings through the

foils

42 and 48, but this is not necessary, and it requires longer tangs and larger holes from which the tangs are displaced. The projections provided by the tangs 36 can be formed in other ways than by displacing them from the body portion of the connector element around theedges of holes punched through the connector element.

The

coatings

41, 43, 47 and 49 each have a thickness of about 2-9 mils. With aluminum foil, the plastic coatings are a copolymer of polyethylene with reactive carboxyl groups for providing strong adhesion for the corrosion-preventing coating, and when the coatings are thin, they are homogenous throughout their thickness. When the plastic coating on the aluminum foil is thicker than about 4 mils, it is more economical to use the copolymer for a thickness of from 2-4 mils adjacent to the foil and to have the remaining thickness of the plastic coating a polyethylene homopolymer.

When the assembly of the connector element 30 with the

tapes

12 and 14, as shown'in FlG. 3, is subjected to heat and pressure, the plastic in contact with the connector element 30 fuses to the connector element to form a hermetically sealed splice in which all of the metal is coated with plastic to protect it from corrosion.

As previously explained, the connector element 30 need not be made from coated metal when it is to be used with shielding

tapes

12 and 14 that have coatings of substantial thickness which can fuse to cover and protect the surfaces of the connector element. When the tapes have minimum coating of from 2-4 mils, however, then it is desirable that the connector 30 be made of metal which is itself coated with plastic to protect it from corrosion. With the connector illustrated in the drawing, the coating is preferably applied before the tangs are struck from the body portion of the connector element so that the points of the tang are uncoated.

For clearer illustration, the connector 30 is shown without coating, but FIG. 6 is on a substantially enlarged scale so that the coating can be illustrated. A metal body portion 60 of the connector element 30 is sandwiched between

plastic coatings

61 and 62 which may be of the same material asused to coat the shielding

tapes

12 and 14, or some other plastic-that will bond to the coatings of the shielding tapes.

The preferred embodiments of the invention have been illustrated and described, and the invention is described in the appended claims.

We claim:

1. A splice construction for providing electrical conductivimetal strip for protecting the metal strip from corrosion. said splice construction comprising end portions of the tapes overlapping one another and having confronting faces at the overlap, a metal connector element located between the overlapping end portions of the tape, said connector element having a body portion and sharp projections extending in opposite directions from the body portion and penetrating through the plastic coating of the strips and into contact with the metal strip of each of the tapes of the splice construction to provide a continuous electric circuit between the strips of the tapes.

2. The splice construction described in claim 1 characterized by the inside face of one tape overlapping the confronting outside face of the other tape and the thickness of the plastic coating on the face of one of the tapes being substantially greater than the thickness of the plastic coating on the confronting face of the other tape, the projections on the op posite sides of the connector element being of different lengths that compensate at least a part of the greater thickness of coating that they have to penetrate.

3. The splice construction described in claim 2 characterized by the connector being a metal sheet sandwiched between the overlapping end portions of the tapes, said metal sheet having a plurality of openings extending through it with the metal that is displaced from the openings forming tangs that extend upward from some of the openings around the edges thereof and that extend downward from others of the openings around the edges thereof to provide projections that penetrate the plastic coatings of the tapes, said splice construction being within an electrical cable containing a core including a conductor surrounded by electrical and having one of the tapes wrapped around the insulated conductor as a shield along a part of the length of the cable, and having the other tape wrapped around the length of the conductor as a shield along a different but contiguous part of the length of the cable, the overlapping ends of the tapes making the metal strips in the tapes a continuous circuit along the different parts of the cable, and said tapes being applied to the core as a shield and moisture barrier, the tangs having points on their ends that contact with the strips of the tapes, said points extending into the strips and displacing metal from the faces of the strips to increase the area of contact of the tangs with the strips and to lock the connector element and the strips against relative movement in the direction of the extent of the strips and thereby prevent longitudinal rupture of the splice construction, the coatings on the confronting faces of the overlapping end portions of the tapes being fusion-bonded to one another to hold them in contact with said connector element.

4. The splice construction described in claim 1 characterized by the coatings on the overlapping end portions of the tapes being held together by fusion bonding of the protective plastic coatings to one another, and the connector element having plastic coating of the tapes protecting it from corrosion by covering all surfaces of the connector element that are not in contact with the metal strips of said tapes, and the ends of the metal strips being protected by plastic coating material that has been exuded from faces of the overlapping ends of the tapes.

5. The splice construction described in claim 1 characterized by the connector being a different piece of metal from terized by the connector element being a metal sheet having a plurality of openings extending through it with the metal that is displaced from the openings forming tangs that extend upward from some of the openings around the edges thereof and that extend downward from others of the openings around the edges thereof to provide the projections that penetrate the plastic coatings on the tapes that are spliced together.

7. The splice construction described in claim 6 characterized by an electrical cable containing a core including a conductor surrounded by electrical insulation an having one of the tapes wrapped around the insulated conductor as a shield along a part of the length of the cable, and having another tape wrapped around a length of the conductor as a shield along a different but contiguous part of the electrical cable, the overlapping ends of the tapes making the metal strips in the tapes a continuous electric circuit along the different parts of the cable, and said tapes being applied to the core as a shield and moisture barrier therefor.

8. The splice construction described in claim 7 characterized by each tape being longitudinally wrapped around the core and the longitudinal edges of the tapes being secured together along seams extending lengthwise of the cable, said connector element extending circumferentially around the cable for substantially the full width of the tapes and having an axial length substantially less than its circumferential extent.

9. The splice construction described in claim 7 characterized by the connector element having the openings in it disposed in a plurality of axially extending rows and a plurality of longitudinally extending rows, alternate openings of each of the rows having their tangs extending in opposite directions from the body of the connector element for contact with a different one of the tapes.

10. The splice construction described in claim 1 characterized by the metal strips and the projections being made of metal of good electrical conductivity, said strips having a thickness of between approximately 4 and .8 mils and the coatings on the strips being of a thickness between approximately 2 and 5 mils.

11. The splice construction described in claim 10 characterized by the metal strips being aluminum, the projections being aluminum, and the coatings on the strips being a copolymer of polyethylene with reactive carboxyl groups that produce a chemical bond of the coating to the aluminum.

12. The splice construction described in claim ll characterized by at least one of the confronting faces of the tapes having a high-density polyethylene portion of the coating that merges with the copolymer at a location spaced from the metal strip that the copolymer coats.

13. The splice construction described in claim 1 characterized by the projections having points on the ends thereof that extend into contact withthe confronting faces of the metal strips and that displace metal of said confronting faces to increase the area of contact of the points with the strips, and to lock the strip and projections against relative movement parallel to the planes of said confronting faces of the strips, the coatings on the confronting faces of the tapes being bonded together to hold the tapes in contact with one another.

14. The splice construction described in claim 1 characterized by the projections being tangs displaced from and bent substantially normal to the face of the connector element from which they extend, the tangs remaining connected to the connector at an edge of an opening produced by the displacement of the tangs from said connector element.

Claims

1. A splice construction for providing electrical conductivity continuity from one tape to the next where each tape includes a metal strip and plastic coating on both sides of the metal strip for protecting the metal strip from corrosion, said splice construction comprising end portions of the tapes overlapping one another and having confronting faces at the overlap, a metal connector element located between the overlapping end portions of the tape, said connector element having a body portion and sharp projections extending in opposite directions from the body portion and penetrating through the plastic coating of the strips and into contact with the metal strip of each of the tapes of the splice construction to provide a continuous electric circuit between the strips of the tapes.

2. The splice construction described in claim 1 characterized by the inside face of one tape overlapping the confronting outside face of the other tape and the thickness of the plastic coating on the face of one of the tapes being substantially greater than the thickness of the plastic coating on the confronting face of the other tape, the projections on the opposite sides of the connector element being of different lengths that compensate at least a part of the greater thickness of coating that they have to penetrate.

5. The splice construction described in claim 1 characterized by the connector being a different piece of metal from the metal strips of either of the tapes.

6. The splice construction described in claim 5 characterized by the connector element being a metal sheet having a plurality of openings extending through it with the metal that is displaced from the openings forming tangs that extend upward from some of the openings around the edges thereof and that extend downward from others of the openings around the edges thereof to provide the projections that penetrate the plastic coatings on the tapes that are spliced together.

10. The splice construction described in claim 1 characterized by the metal strips and the projections being made of metal of good electrical conductivity, said strips having a thickness of between approximately .4 and .8 mils and the coatings on the strips being of a thickness between approximately 2 and 5 mils.

12. The splice construction described in claim 11 characterized by at least one of the confronting faces of the tapes having a high-density polyethylene portion of the coating that merges with the copolymer at a location spaced from the metal strip that the copolymer coats.

13. The splice construction described in claim 1 characterized by the projections having points on the ends thereof that extend into contact wIth the confronting faces of the metal strips and that displace metal of said confronting faces to increase the area of contact of the points with the strips, and to lock the strip and projections against relative movement parallel to the planes of said confronting faces of the strips, the coatings on the confronting faces of the tapes being bonded together to hold the tapes in contact with one another.