US3784731A

US3784731A - Connector for insulated conductors

Info

Publication number: US3784731A
Application number: US00312008A
Authority: US
Inventors: T Newbold
Original assignee: TRW Inc
Current assignee: Northrop Grumman Space and Mission Systems Corp
Priority date: 1972-12-04
Filing date: 1972-12-04
Publication date: 1974-01-08
Anticipated expiration: 1991-01-08
Also published as: GB1442644A; DE2360360A1; BR7309463D0; CA995321A; AR201208A1; JPS4986891A

Abstract

An electrical connector of the composite sleeve type having an inner sleeve carrying a plurality of tangs for piercing insulation and engaging the metal wires of a plurality of electrical conductors inserted into the inner bore in the sleeve to interconnect the conductors responsive to a crimping of the connector includes a liner of thin, filmlike material disposed within the bore in the inner sleeve opposite the distal ends of the tangs. The liner is retained in assembly with the connector by a reversely bent extension thereof which is sandwiched between the outer surface of the outermost metallic sleeve of the connector and the inner surface of the outer insulative jacket of the composite sleeve forming the connector.

Description

United States Patent [191 Nev/hold Jan, 0, 1974 i 1 CDNNECTOR FOR INSULATED CONDUCTORS [75] inventor: Thomas Newbold, Lincoln, Mass.

[73] Assignee: TRW Inc., Cleveland, Ohio [22] Filed: Dec. 4, 1972 211 Appi. No; 312,008

Primary Examiner-Darrell L. Clay W Attorney-James R. OConnor, Hall & l-loughton [57} ABSTRACT An electrical connector of the composite sleeve type having an inner sleeve carrying a plurality of tangs for piercing insulation and engaging the metal wires of a plurality of electrical conductors inserted into the inner bore in the sleeve to interconnect the conductors responsive to a crimping of the connector includes a liner of thin, filmlike material disposed within the bore in the inner sleeve opposite the distal ends of the tangs. The liner is retained in assembly with the connector by a reversely bent extension thereof which is sandwiched between the outer surface of the outermost metallic sleeve of the connector and the inner surface of the outer insulative jacket of the composite sleeve forming the connector.

PMNTEUM slam 3354 73 3 SHEET 1n? 2 CONNECTOR FOR INSULATED CDNDUCTORS BACKGROUND OF THE lNVENTlON 1. Field of the Invention The invention relates generally to electrical connectors and more specifically to crimp-type connectors frequently classified in U.S. Art Class 174, Subclass 87, entitled, Conduits, Cables and Conductors With Joints Angular.

2. Description of the Prior Art One of the early connectors of the type contemplated by the present invention is disclosed in U.S. Pat. No. 2,828,353 (W. E. Adams et al.), which connector embodies a single inner metallic sleeve of relatively hard springlike material. The Adams et al., connector thus presented a smooth internal bore for easy telescopic insertion of a plurality of conductors to be connected into the sleeve through its open end. Thereafter during crimping of the connector by a special tool, insulation piercing and wire engaging prongs were formed in the metallic sleeve simultaneously with the crimping operation. The art under consideration was subsequently improved through modifications of the Adams et al. connector, with said modifications being best exemplified by the disclosure of U.S. Pat. No. 3,064,072 (H. .l. Graff et al.). The major contribution to the art of Graff and his coinventors was to provide the inner metallic sleeve of the connector with a plurality of preformed, spaced apart perforations defining inwardly extending insulation piercing and wire engaging prongs which eliminated the need for the special crimping dies required for utilization of the Adams et al. connector. in addition, Graft et al provided an outer sleeve of relatively soft, malleable material which surrounded the inner sleeve and was crushed during the crimping operation to insure that the harder springlike inner sleeve would remain compressed whereby the prongs thereof were held in good wire engaging and retaining contact with the spliced conductors. U.S. Pat. Nos. 3,265,807 (D. T. Smith); 3,283,061 (P. O. Bolling); 3,507,977 (B. B. Pusey); and 3,372,227 (K. C. Allison) disclose variations of connectors embodying the basic teachings of Graff et al. The Graffet al. connector and certain of the above mentioned variations thereof have enjoyed tremendous commercial success, with literally billions of said connectors having been used by the telephone industry for the splicing of communication cables. A number of crimping tools including rather sophisticated automatic devices and rather simple hand crimpers have been developed for attaching wire member interconnectors of the Graff et al. type.

A salient deficiency in the Graff et al. type connector, which has been recognized for some years, is that the performing of the insulation piercing and wire engaging prongs presents a restriction in the bore of the inner sleeve of the connector which often interferes with or renders rather difficult the full depth telescopic insertion of the wire members to be connected through the open end of the bore in the connector. Moreover, as the Graff et a]. and Smith patents most clearly illustrate, the faces of the crimping dies which come togetherto effect the connection are often disposed at an acute angle to one another with the most proximate portions of the dies being opposite the rearward end of the connector. Thus, the crushing action exerted on the metallic sleeves is more extensive at the rear of the connector. Ergo, if the conductors are not fully longitudinally seated in the connector by reason of same having become snagged on prongs disposed toward the open end of the connector, defective splices or connections frequently result.

With a view to overcoming the above mentioned problem with the Graft et al type connectors, designers have developed so-calledopen sided connectors which retain the basic composite sleeve construction and preformed prongs taught by Graff et al., but permit transverse insertion of a plurality of conductors into the inner sleeve whereby one can properly position the conductors to insure maximum prong and conductor engagement responsive to crimping. Connectors of the aforementioned type are illustrated in U.S. Pat. Nos. 3,242,256 (L. L. .lugle) and 3,514,528 (J. C. Ray). The latter connectors, however, require more sophisticated crimping tools than the Graff et al. type and they are rather difficult for an installer, i.e., a lineman, to handle since they tend to become entangled with one another when shipped in bulk and have thus not enjoyed particularly significant acceptance by the communications industry. Over the years it has been found convenient to preassemble connectors of the Graff et al. type in distinctly defined pairs on flexible tapes, whereby said connectors can be reeled and easily fed to automatic crimping tools. The taping of connectors in defined pairs and a typical automatic crimping machine for taking advantage of the taped arrangement is disclosed in U.S. Pat. No. 3,625,350 (J. C. Ray). The Ray patent, however, does not disclose what has actually become the practice in the art, to wit, to provide a second, upper layer of continuous tape which overlies the connectors and is heat sealed or adhesively attached to the lower reach of tape adjacent the outboard sides of each pair of connectors. This arrangement insures that the connectors do not become detached from the tape and has been generally accepted by the telephone industry, particularly the Bell System and its manufacturing divisions. Obviously open top or open side connectors of are not conducive to use in the aforementioned double layer taped arrangement in that the upper layer or reach of tape would overlie the opening in the connector and inhibit transverse insertion of a plurality of conductors into same. Thus, the problem of providing a connector of the Graff et al. type having some means for providing a smooth bore to facilitate telescopic insertion of insulated conductors, which connector could be secured between double layers of flexible tapes, has been one for which the industry has long been seeking a solution.

l am aware of one proposed solution which has not yet appeared in the patented prior art, but which is somewhat similar to the teaching of the present disclosure. That solution proposes the insertion into the central bore in a connector of the Graff et al, type, after the shrinking of the outer jacket on the metallic sleeves, of a tube of thin, filmlike material (usually a transparent Mylar), and securing the tube to the con nector by curling an extension thereof back around the open end of the insulative jacket and applying an elastic band to the connector to hold the said extension in assembly therewith. We are of the opinion that there are several drawbacks to this proposed solution. One drawback is that the use of the elastic bands adds another component to the connector and necessitates an additional manufacturing operation. Another drawback is that the retaining bands are subject to becoming detached from the connectors during shipment or during feeding to a taping machine through vibratory hoppers, etc. Still another drawback is that the bands do not retain the filmlike material in a taut condition so that it tends to wrinkle and in effect provide an obstruction at the entrance to the connectors which to some extent recreates the problem which the solution under discussion purports to eliminate. Still further, the use of the elastic band tends to eliminate the necked-in profile of the insulative jacket of the open ends of the connectors. This profile is characteristic of many commercial connectors and has been found to be extremely useful as a keying means for feeding loose connectors through hoppers to transport tracks of automatic machinery for taping the connectors in distinctly defined pairs.

The present invention is seen to provide a unique solution to the problem outlined above in that the connector disclosed herein retains the basic structural composition of the Graff et al type connector, but additionally includes a tautly retained internal liner in the assembly which greatly facilitates full depth insertion of conductors into the bore in the connector, and thereby renders the connector substantially more efficient by greatly reducing the possibility of a defective electrical connection. The aforementioned advantages are achieved in a connector which remains conducive to accurate feeding to automatic taping equipment wherein connectors may be taped in distinctly defined pairs between double layers of tape for subsequent reeling and convenient feeding to commercial crimping devices in accordance with the present actual practice in the art. The aforementioned advantages as well as other contributions to the art will become readily apparent to one who proceeds to a consideration of the detailed description of the connector which follows hereinafter.

SUMMARY OF THE INVENTION A connector for splicing insulated conductors. The connector is of the composite sleeve type and includes telescopically disposed inner and outer metallic sleeves, and an outer jacket of insulating material. The inner metallic sleeve carries a plurality of insulation piercing and wire engaging tangs extending into the central, axial bore in the connector. The major improvement in connectors of this type disclosed herein is the provision of a liner of thin, filmlike material disposed within the central bore in the connector and overlying the distal ends of the tangs on the inner metallic sleeve. The liner is permanently tautly secured to the connector by a reversely bent extension thereof which extends around the end wall of the outer metallic sleeve at its open end and is sandwiched between said sleeve and the outer insulating jacket. The liner greatly facilitates full depth longitudinal insertion of a plurality of conductors into the central bore in the connector through its open end, whereby effective electrical connections are made responsive tovpressure exerted on said jacket to crush said inner sleeve and cause the tangs to pierce the liner and the insulation on the conductors and securely engage the wire members of the conductors.

BRIEF DESCRIPTION OFTHE DRAWING FIG. 1 is an enlarged, exploded, perspective view of the four major component parts of a connector according to the invention;

FIG. 2 is a greatly enlarged, partially broken away, transverse cross-sectional view of a connector according to the invention;

FIG. 3 is an enlarged, elevational perspective view of a connector according to the invention;

FIG. 4 is a cross-sectional view of the connector taken on line 4-4 of FIG. 3 with the inboard leg forming the liner partially broken away;

FIG. 5 is a cross-sectional view of the connector taken on line 55 of FIG. 3 and depicting the connector crimped to a pair of insulated electrical conductors disposed therein;

FIG. 6 is a cross section taken on line 6-6 of FIG.

DESCRIPTION OF A PREFERRED EMBODIMENT With reference, in particular, to FIGS. 1 through 6 of the drawing, one will observe that a connector according to the invention comprises a composite sleeve structure including four major component parts, three of which are well known in the art, to wit: afirst or inner metallic sleeve 2; a second or outer metallic sleeve 4; an outer jacket 6; and an inner liner 8.

The inner sleeve 2 is formed from a hard, springlike material, e.g., a spring tempered phosphor bronze and is relatively thinner and shorter than the outer metallic sleeve 4. The inner sleeve is open at both ends 10 and 12 thereof and is slightly necked inwardly at 14 and 16 adjacent said open ends. The body of said inner sleeve is provided with a plurality of randomly spaced perforations 18 defining a plurality of tangs or protuberances 20 sheared from the sleeve incident to the blanking out of said perforations and directed into the central bore 22 in said sleeve. The inboard edge of each of said perforations is thus defined by a plurality of said protuberances 20 and each protuberance is sharply pointed and provided with leading knife-like edges for piercing the insulation on a conductor and engaging the metal wire of a conductor as will be described further hereinafter.

The outer metallic sleeve 4 is formed from a soft, relatively malleable material, e.g., annealed brass, and is open at one end 24 and closed at its opposite end 26.

Both of the metallic sleeves are of generally elliptical or oval transverse cross-section configuration (see FIG. 6 in particular) and the inner sleeve is diametrically somewhat smaller than the outer sleeve to permit telescopic assembly of the former within the latter. The relative dimensions of the sleeves are selected so that the inner sleeve is press fitted within the outer sleeve to inhibit any longitudinal shifting of one sleeve with respect to the other. If desired, the inner sleeve may be provided with external bosses to enhance the tightness of the press fit assembly or some other interlocking fastener means, e.g., that depicted in the patent to P. O. Bolling above mentioned, may be employed.

The major contribution to the art of this disclosure resides in the liner 8 which is formed from a strip of thin, filmlike tape, ideally polyester tape marketed by du Pont under the trade name Mylar," and includes a first or inboard section 28 disposed within the central bore 22 in the inner metallic sleeve, said first section being defined by opposed legs 30 gradually converging from the open end of the outer metallic liner to an integral connecting web 32 disposed adjacent the closed end 26 of said outer liner, and a second or outboard section 34 formed as an integral extension of said inboard section and defined by a pair of reversely bent wings 3b which are curled over the end wall of the sleeve d at the open end 24 thereof and extend back along the outer wall of said sleeve toward the closed end thereof and terminate in free ends 38 disposed relatively proximate said closed end. The inboard section 28, or more specifically legs 30 of the liner are pinched slightly inwardly toward the axis of the central bore and lightly bitingly gripped by the ends of some of the protuberances as is best seen in FIG. 2, and the liner is stretched or held tautly in assembly with the connector by the fourth major component, to wit, the jacket 6 which is heat shrunk about the outer sleeve 4 and thus sandwiches the extension or wings 36 between the outer wall of said sleeve and its, i.e., the jackets, inner wall.

The outer jacket 6 is formed from a heat shrinkable, synthectic plastic material, e.g,., a polyolefin resin, and generally assumes the contour of the outer sleeve 4 but protrudes endwise beyond said sleeve and is severely pinched inwardly at 40 adjacent the closed end 26 of said sleeve. Further, the jacket is necked slightly inwardly at 42 and then flares outwardly to its open end 44 to provide a funnel-like entry portion 46 which facilitates insertion of conductors to be spliced into the central bore in the connector.

A connector of the type disclosed herein is typically utilized as depicted in H6. 5 to splice together and electrically interconnect a pair or more of insulated electrical conductors 48 which are axially inserted into the connector through the open end 44 of the composite sleeve. The previously described funnel-like extension 4b of the outer jacket 6 provides a convenient lead-in to the central bore in the connector and the inboard section, i.e., the inwardly converging legs 30 of the liner 8 which overlie the distal ends of the tangs or protuberances 20, facilitate unimpeded full depth insertion of the conductors into the connector, as is again best depicted in FIG. 5. Once the conductors are fully seated, the connector is crimped by applying a force on the outer jacket under the pressure of the dies of a suitable crimping tool to crush the metallic liners thereby causing the protuberances 20 to perforate the liner 3 and pierce the insulation 50 on the conductors 48 and engage the metal wire 52 of the conductors with a slid ing, biting action to thereby securely grip the conductors and effect the requisite electrical connection.

Referring once again to FIG. 5, the reader will appreciate that even if the opposed faces of the crimping dies are tapered angularly toward the rear of the connector, so that maximum crushing action is achieved adjacent the connectors closed end 26, the liner 8 by greatly facilitating full depth conductor insertion substantially reduces the possibility of a defective connection which would otherwise occur if the conductors, in the absence of the liner, become snagged or hung up on protuberances adjacent the open end of the connector and were thus not inserted to the full depth of the sleeves. Frequently, in a typical communications installation, a splice is made by a lineman first cutting two parallel conductors to form four conductor ends and then inserting said ends in matched pairs into a pair of connectors and crimping the latter to complete the splicing operation. To facilitate the linemans chore, it has been found convenient to the industry to tape connectors in distinctly defined pairs, e.g., as is shown in l iay Patent fllfitl i ii fit lisllsdr li w l; rm new @l as well as the lower reach Ray depicts securing the connectors in said distinctly spaced pairs. The disclosed connector is fully conducive to being double layer taped as aforesaid. Further, the taped connectors are fed from reels to automatic crimping devices so that the lineman is often working blind so to spealr and he must rely on feel rather than sight to determine if the matching conductor ends to be spliced are fully seated in the pair of adjacent connectors. Obviously, the incorporation of the disclosed liner 8 which is held in a taut condition, greatly reduces the margin for lineman error in effecting splices in the manner aforesaid. it should also be observed that the incorporation of the liner 8 into the connector does not in any way alter the basic external configuration of the connector. Thus the connector may be fed to automatic taping machinery utilizing existing apparatus as conveniently as the presently used commercial connectors.

Having considered the foregoing detailed description the reader should now clearly recognize a significant contribution to the art. One should also appreciate that the description is to be considered in an illustrative rather than a limiting sense. Modifications within the scope of the disclosure are contemplated. For example, it is clearly envisioned that the thin, filmlike liner and its extension could be in a circumferentially continuous form as well as in the preferred form depicted and described. Therefore, for a more precise definition of the scope of the invention protected by these Letters Patent, one should rel'er to the claims which follow.

I claim:

l. in a connector for connecting insulated electrical conductors, said connector being of the type comprising a composite sleeve having an outer jacket of insulating material and a pair of coaxially, telescopically disposed metallic sleeves including an inner sleeve of relatively hard springlike material and an outer sleeve of relatively soft material, both of said metallic sleeves being positioned within said jacket, said inner metallic sleeve having on its inner surface spaced apart perforations defining inwardly extending insulation piercing and wire engaging protuberances, said connector being thereby adapted to confine and embrace a plurality of insulated electrical conductors positioned in the central bore of said inner sleeve responsive to the deformation of said outer sleeve, by pressure applied to said insulating jacket, to exert a crushing action on said inner sleeve to cause the protuberances to pierce the insulation on the conductors and engage the metallic portions of the conductors, thereby establishing electrical contact with the metallic portions of the electrical conductors; the improvement comprising a liner of electrically nonconductive, thin, filmlilre material disposed within the central bore of said inner sleeve opposite the distal ends of said protuberances, said material being perforable by said protuberances responsive to the crushing action exerted on said inner sleeve to effect the electrical connection, said liner being retained in assembly with said connector by a reversely bent extension of the material thereof which extends over the end wall of said outer sleeve at the open end thereof and back toward the opposite end of said sleeve and is sandwiched between the outer of said outer sleeve metallic sleeve and integrally connected by a reversely bent web disposed proximate the closed end of said sleeve.

3. A connector according to claim 2 wherein said extension of said liner includes a pair of wings joined to the most divergent ends of said legs by reversely bent webs disposed at the open end of said outer sleeve.

Claims

1. In a connector for connecting insulated electrical conductors, said connector being of the type comprising a composite sleeve having an outer jacket of insulating material and a pair of coaxially, telescopically disposed metallic sleeves including an inner sleeve of relatively hard springlike material and an outer sleeve of relatively soft material, both of said metallic sleeves being positioned within said jacket, said inner metallic sleeve having on its inner surface spaced apart perforations defining inwardly extending insulation piercing and wire engaging protuberances, said connector being thereby adapted to confine and embrace a plurality of insulated electrical conductors positioned in the central bore of said inner sleeve responsive to the deformation of said outer sleeve, by pressure applied to said insulating jacket, to exert a crushing action on said inner sleeve to cause the protuberances to pierce the insulation on the conductors and engage the metallic portions of the conductors, thereby establishing electrical contact with the metallic portions of the electrical conductors; the improvement comprising a liner of electrically nonconductive, thin, filmlike material disposed within the central bore of said inner sleeve opposite the distal ends of said protuberances, said material being perforable by said protuberances responsive to the crushing action exerted on said inner sleeve to effect the electrical connection, said liner being retained in assembly with said connector by a reversely bent extension of the material thereof which extends over the end wall of said outer sleeve at the open end thereof and back toward the opposite end of said sleeve and is sandwiched between the outer surface of said outer sleeve and the inner surface of said outer jacket of insulating material, said liner being particularly adapted to facilitate the telescopic insertion of the electrical conductors into the central bore in said inner sleeve through the open end thereof.

2. A connector according to claim 1 wherein said liner includes a pair of opposed legs gradually converging toward one another from the open end of said outer metallic sleeve and integrally connected by a reversely bent web disposed proximate the closed end of said sleeve.