Conductor In-slot Electrical Connectors

Abstract

Electrical connecting device has a channel-shaped cross-section and tongues struck up from the web of the channel. Wire receiving slots extend downwardly from the free ends of the tongues. A plurality of fingers extend from the sidewalls and are adapted to be curled inwardly and downwardly to stuff a wire positioned between the sidewalls into the slots in the tongues.

Description

BACKGROUND OF THE INVENTION

This invention relates to connecting devices for forming electrical connections with conductors. The herein disclosed embodiment is particularly intended for forming a butt splice between two wires which extend axially towards each other. However, the principles of the invention can be used in connecting devices for making many other types of connections and for making connections under many other circumstances as will be apparent to those skilled in the art.

The U.S. Patent to Marley et al U.S. Pat. No. 3,320,354 discloses a crimpable channel-shaped connecting device having tongues between its sidewalls which are adapted, upon crimping, to receive the end portions of wires extending axially towards each other. The Marley et al connecting device is capable of forming a common connection among as many as four wires and is widely used in the telephone industry for forming butt splices (a connecting between two wires extending axially towards each other) and for making tap connections (a connection of a branch wire to a through wire). Connecting devices of the type shown in Marley et al U.S. Pat. No. 3,320,354 are adapted to be crimped by crimping tools of the types shown in U.S. Pat. Nos. 3,328,871 and 3,431,621 which perform a wire trimming operation at the time of crimping. The principle embodiment of the present invention disclosed below is also adapted to be crimped by tools in accordance with U.S. Pat. Nos. 3,431,621 and 3,328,871.

Connecting devices of the type shown in U.S. Pat. No. 3,320,354 have received an enthusiastic acceptance in the telephone industry and are in widespread use. However, most electrical connections involving telephone cables are made when the ends of two multi-conductor cables are spliced to each other, a procedure which requires only a butt splice for two wires which extend axially towards each other. The high degree of versatility of the connector shown in U.S. Pat. No. 3,320,354 is therefore, not required for these cable splicing operations and there exists a need for a connecting device which is particularly intended for such operations.

The instant invention is then specifically directed to the achievement of a connecting device which can be produced in a relatively small size, which can be crimped with relatively low crimping forces, and which will have a high degree of reliability as regards both application to the wires and performance of the finished electrical connection.

It is an object of the invention to provide an improved connecting device for forming an electrical connection with a conductor, particularly an insulated wire. A further object is to provide a connecting device for forming a butt splice between two wires. A further object is to provide a connecting device which can be produced in relatively small sizes with a minimum of material. A further object is to provide a preinsulated crimpable connecting device which will have good dielectric properties after crimping. A still further object is to provide a low resistance and highly reliable crimped electrical connection to a conductor.

These and other objects of the invention are achieved in a preferred embodiment which is briefly described in the foregoing abstract, which is described in detail below, and which is shown in the accompanying drawings in which:

FIG. 1 is a perspective view of a section of a strip of preinsulated connecting devices in accordance with the invention.

FIG. 2 is a perspective view of an individual connecting device in accordance with the invention.

FIG. 3, is a perspective view of the connecting device of FIG. 2 crimped onto two wires extending towards each other.

FIG. 4 is a end view of a connecting device in accordance with the invention positioned on an anvil of a crimping tool and showing the position of the crimping die and a wire at an early stage of the crimping operation.

FIGS. 5-8 are views similar to FIG. 4 but showing the positions of the parts at successive stages of the crimping operation, FIG. 8 showing the positions of the parts at the completion of the crimping operation.

FIGS. 9 and 10 are views taken along the lines 9--9 and 10--10 of FIGS. 3 and 11 (the connector being uncrimped in FIG. 11).

FIG. 11 is a top plan view of an uncrimped connecting device in accordance with the invention.

FIGS. 12-15 are perspective views of alternative embodiments of the invention.

A PREFERRED EMBODIMENT

Referring first to FIGS. 2, 4, and 11, a butt splice connecting device 2 in accordance with the invention comprises a generally channel-shaped stamped and formed metallic member 4 having a web 12 and sidewalls 14, 14a. A film of 6 insulating material, preferably Mylar (polyethyleneterephthalate), is bonded to the external surface of the connecting device and extends axially beyond the ends thereof as shown at 5 and upwardly beyond the sides as shown at 7. The connecting device 2 is intended for forming a butt connection between two wires 8, 10 which extend axially toward each other. As is apparent from FIG. 2, the righthand end of the connecting device 2 is a mirror image of the lefthand end and the device is symmetrical about its vertical center line. Each end of the connecting device 2 can, therefore, be regarded as a single connecting means and only one of these connecting means is described in detail below.

A pair of tongues 16, 18 are struck up from the web 4, the inner tongue 18 has a slot 20 that extends downwardly from the upper free end 22 of the tongue and the outer tongue 16 has a similar slot 23. The inner ends of these slots are above the surface of the web 12 but are below the upper edges of the sidewalls 14, 14a. The edges of the slots flare outwardly at the upper ends of the tongues as shown at 24 to provide guidance for the wire at the time of crimping. It should also be mentioned that the slot 23 in the tongue 16 which is adjacent to one end of the connector is relatively wider than the slot 20 in the inner tongue 18. Specifically, the width of the slot 20 in the tongue 18 is less than the diameter of the conducting core 70 of the wire so that when the wire is forced into this slot, the edges of the slot will penetrate the wire insulation and substantially deform the conducting core and good electrical contact will be established. When the wire is forced into the relatively wider slot 23 in the tongue 16, the edges of this slot penetrate the insulation 68 and may engage the conducting core but they do not penetrate the core to the extent that it is weakened. These outer tongues 16 thus function as strain relief devices to protect the electrical connections between the wires and the inner tongues 18.

The wire is stuffed into the slots during crimping by means of fingers 26, 28, 30, 26a, 28a, 30a which extend from the sidewalls 14, 14a. These fingers are identical to each other so that a description of one will suffice for all. Each finger thus has a proximate section 34 which is integral with, and extends in the same general direction as, its respective sidewall 14 or 14a. Each finger further has an end section 36 which is joined to the proximate section by a reverse bend 38. These end sections of the fingers are directed generally inwardly and downwardly with reference to longitudinal axis of the connecting device.

The fingers 28, 28a are located between the planes defined by the tongues 16, 18 and have a width which is less than the spacing between these tongues so that they can be curled downwardly until they lie between the tongues. The fingers 26, 26a, and 30, 30a are located on each side of the fingers 28, 28a and are spaced from the surfaces of the tongues so that they can be curled downwardly during crimping and will be beside the tongues after crimping.

The embodiment of FIGS. 1-3 has additional fingers 32, 32a which are integral with the sidewalls adjacent to the ends of the connecting device. These fingers also have proximate end sections 42, 42a respectively and serve as guide fingers as will be described below. These fingers are somewhat lower than the previously described fingers in order to adapt them to their guiding function.

Turning now to FIG. 4, a connecting device 2 is adapted to be crimped by a suitable crimping tool as generally disclosed in either one of U.S. Pat. Nos. 3,431,621 or 3,328,871. In crimping tools of these types, the connecting device is supported on the surface 58 of an anvil 56 and is crimped by a crimping die 54 having forming surfaces 60, 62, 64. The die is symmetrical about the vertical center line of FIG. 4 and has steeply convergent surfaces 60 which function to center the connector before curling thereof commences. The forming surfaces 60 merge with convergent surfaces 62 which slope gently towards each other and these surfaces in turn follow reverse curves 64 which merge at a cusp 66.

During crimping, the wire 8 will be located as generally shown in FIG. 4 above a connector supported on the surface 58 of the anvil. The wire is centrally located in FIG. 4 although as a practical matter, the wire may be located anywhere in the space above the connector when the die and anvil are positioned relative to each other as shown in FIG. 4.

As the die and anvil move towards each other to the position of FIG. 5, the wire is relocated, regardless of its initial position, until it is between the ends of the fingers 26, 28, 30, 26a, 28a, 30a and above the ends 42, 42a of the guide fingers 32. It will be noted in FIG. 5 that at this stage of the crimping operation, the edge portions 7 of the insulating film 6 have been curled by the die surfaces 64 and the fingers have been bent slightly inwardly from their original divergent orientations.

Upon further movement of the die and anvil towards each other, proximate sections 34 of the fingers 26, 28, 30, 26a, 28a, 30a are curled so that the end portions 36 of the fingers engage the upper surface of the wire on opposite sides of the vertical center line of the connector. Upon still further movement of the die towards the anvil, FIGS. 7 and 8, these stuffing fingers are further curled and push the wire into the slots of the tongues.

Returning to FIG. 6, it will be noted that at this intermediate stage, the end portions 42, 42a of the guide fingers extend parallel to the vertical center line of the connector and the opposed surfaces 43, 43a of these guide finger ends function to precisely center the wire at the end of the connector. Subsequently, the guide fingers are further curled (FIG. 7) but this occurs after the wire has entered the slots in the tongues.

The marginal edge portions 7 of the insulation are similarly curled until they are against each other and the insulating film moves with the fingers so that in the finished connection, the opposed surfaces of this film are against each other and locked between the opposed surfaces of the deformed fingers.

Depending upon the size of the wire and the width of the slots 20, the tongues may be substantially deformed by outward flexure of each side of each tongue with respect to the inner ends of the slots 20. In the drawing, the tongues are shown as being substantially deformed in FIGS. 7 and 8, a condition which will result where a relatively large wire is inserted into the slots. Connectors in accordance with the invention are designed to accept a range of wire sizes and the largest wire of the range may cause noticeable deformation of the tongues while the smallest wire may not.

In the finished crimped connection, the fingers 28, 28a will be between the tongues and will have curled surfaces disposed against the insulation of the wire as shown in FIG. 9. The fingers 26, 26a and 30, 30a will be similarly disposed with respect to the wire but outwardly of the tongues. The guide fingers 32, 32a have curved surface portions against the upper side of the wire and function as a strain relief. In addition, these guide fingers maintain the wire centered with reference to the connector so that the emergent wires extend centrally and axially from the connection device as shown in FIG. 3.

Connecting devices in accordance with the invention are advantageously manufactured by stamping and forming continuous sheet metal strip. It is desirable to produce these connecting devices in the form of a continuous ladder strip, FIG. 1, and this can be done by blanking the metal strip and bonding the flat blanks to a continuous strip of plastic film. Thereafter, the plastic strip is severed between adjacent metal blanks and the connecting devices are formed up or "U-ed" so that the completed strip comprises side by side connecting devices which are integral at their ends 52 with side carrier strips 50. Strip of the type shown in FIG. 1 can be used in the crimping apparatus shown in U.S. Pat. No. 3,431,621. The individual connecting devices can be severed from the strip of FIG. 1 and crimped by means of the tool shown in U.S. Pat. No. 3,328,871. The connecting devices can be manufactured from any suitable strip metal, 3/4 hard brass (70Cu-30Zn) of a suitable Phosphor bronze. As previously mentioned, the connector in accordance with the embodiment of FIGS. 1-3 is relatively compact having an overall length of about 0.96 inch, a width of about 0.18 inch, and a height of about 0.13 inch. Where connecting devices are produced from brass, metal stock having a thickness of 0.016 inch can be used and the connecting devices will be suitable for wires in the size range of AWG 26 to 17.

A salient advantage of connectors in accordance with the invention is that during crimping, the wire is accurately guided into the slots of the tongues 16, 18 and the manner in which the fingers are curled ensures stuffing of the wires to the inner ends of the slots so that electrical contact with the conducting core of the wires is assured. The manner of centering the wires is shown in FIG. 4-7; as the die 54 moves relatively towards the anvil 56, the wire must move to the position shown in FIG. 5 and further movement of the die has the effect of curling the fingers and guiding the wire in a manner such that it moves precisely and accurately laterally of its axis until it reaches the inner ends of the slots. By virtue of precise guiding and placement of the wire, it is not necessary that the technician have a high degree of operator skill and good results will consistently be obtained.

Other advantages are achieved and contribute materially to high quality electrical connections. For example, in the finished crimped connection, the internal surface of insulating film 6 is engaged only by flat surfaces or smooth rounded surfaces as at the lower corners of the connecting device and curved surfaces of the formed fingers as shown in FIG. 10. The fact that the insulating film is supported by smooth curved surfaces results in the achievement of a crimped connection having relatively high dielectric strength since the metallic connecting device does not have sharp edges disposed against the inner surface of the film at any location.

The finished crimped connection between the wire and the connecting means is rugged and durable and is not easily damaged for several reasons. For example, the tongues, which are the site of the connection, are protected on each of their sides by curled fingers and these curled fingers are strong by virtue of their cylindrical shapes. The tongues are thus protected against their being bent downwardly towards the web of the connecting device by an external force. It can be noted also that the fingers are partially curled and are located on each side of the tongues while the wire is being forced into the slots in the tongues, see FIGS. 7 and 8. During such movement of the wire into the slots, the tongues are subjected to downwardly directed forces which may tend to bend the tongues downwardly. The partially curled fingers function to prevent such bending of the tongues by virtue of their locations adjacent to the tongues. Finally, the web and sidewalls form a channel member which is an extremely strong and rigid structural shape.

In the finished crimped connection, there will be little relaxation for the reason that the fingers are curled through a full 360.degree. and the end portions of the fingers, if they tend to relax at all, will be urged against the wire rather than away from the wire. In this manner, the effects of spring back (the residual elasticity which remains in a metal part after it has been stressed beyond its elastic limit) are nullified or eliminated.

Connecting devices in accordance with the invention require only a relatively low crimping force because of the fact that the crimping operation requires only that the fingers be curled downwardly as illustrated in FIGS. 5-8. It will be appreciated that the force required to carry out the curling operation on these fingers will be less, other things being equal, than the force required for bending a flat section of sheet metal. The fact that the wire is symmetrically loaded during the crimping operation also probably contributes to the low crimping forces realized.

The disclosed embodiment of the invention has flat insulating film on its external surface. If desired, a corrugated film, having corrugations running axially along the length of the connecting device, may be used as shown in U.S. Pat. No. 3,621,117. The use of a corrugated insulated film may be preferred for the reason that the corrugations will interlock with each other between the opposed surfaces of the fingers so that the film will be more securely held on the crimped connecting device. Additionally, a corrugated insulated film has a tendency to accomodate itself to the curling operation since it can be elongated in the direction of the circumference of the connecting device.

Applications of the principles of the invention to connecting devices other than the butt connector shown in FIGS. 1-3 will be apparent to those skilled in the art and FIGS. 12-15 show some of the possible alternative embodiments. FIG. 12 shows a conventional ring-tongue terminal having a contact ring-tongue 76 which is integral with a web of a connection means 74. This connecting means is adapted to form an electrical connection with a single wire and has the same structural features as each of the two connecting means of the embodiments of FIGS. 1-3.

FIG. 13 shows a butt splice connector 78 which differs from the previous embodiment in that it does not have auxillary strain relief and guide fingers corresponding to the fingers 32, 32a. The end pairs of fingers in this embodiment 82, are relatively smaller than the fingers 84, 86 so that the wires will be guided at the ends of the connectors as briefly explained.

FIG. 14 shows an embodiment of a butt splice connector having a single tongue 88 at each end and having two fingers on each sidewall associated with each tongue. Connecting devices of this type will be relatively shorter than the previously described embodiments and can be used under circumstances where two tongues and slots for each wire are not deemed to be essential.

The embodiments of the invention described thus far all have sidewalls 14, 14a extending from the web 12 and the presence of these sidewalls is highly advantageous for the reason that a channel is an extremely strong and rigid structural shape. These sidewalls thus strengthen the connecting device in its uncrimped condition and in its crimped condition. Under some circumstances, however, it may prove feasible to eliminate the sidewalls and to have the fingers 90 extending directly from a flat web 92 from which a tongue 94 has been struck. A connecting device as shown in FIG. 15 can be crimped unto a wire as previously described and can be provided with an insulating film.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only.

Claims

What is claimed is:

1. A stamped and formed metallic connecting means for forming an electrical connection with a wire comprising:

a substantially flat web having two parallel sides,

a tongue struck up from said web, said tongue defining a plane extending transversely of said web and transversely of said sides,

said tongue having a free upper end, a wire-receiving slot extending partially downwardly into said tongue from said free end, and

two wire stuffing fingers extending from each of said parallel sides, the said fingers on each side being spaced-apart and being on each side of said tongue, each of said fingers having a proximate section with respect to said web and having an end section which is remote from said web, said proximate section of each finger extending divergently with respect to its respective side and said end section of each finger being joined to said proximate section by a reverse bend, each of said end sections extending generally downwardly towards said web, whereby,

upon location of a wire with its axis extending parallel to said sides and between said fingers, and upon curling said proximate sections of said fingers inwardly and downwardly, the external surfaces of said fingers will engage said wire on each side of said tongue and push said wire into said slot.

2. Connecting means as set forth in claim 1 said web having sidewalls extending from said sides, said fingers extending from said sidewalls.

3. Connecting means for forming an electrical and mechanical connection with an elongated conductor comprising:

a generally U-shaped member having a web and sidewalls extending from the sides of said web,

a tongue struck from said web, said tongue extending from said web in the same direction as said sidewalls and defining a plane which extends transversely of said web and transversely of said sidewalls, said tongue having a free end, a wire receiving slot extending centrally into said tongue from said free end towards said web,

each of said sidewalls having first and second integral fingers extending therefrom, corresponding fingers on said sidewalls being aligned with each other, said plane defined by said tongue being between said first and second fingers,

each of said fingers having a first section which is integral with, and extends in the same general direction as, its respective sidewall, and each finger having a second section which is connected to said first section by a reverse bend and which extends inwardly and generally downwardly whereby,

upon locating said conductor between said fingers and curling said fingers downwardly, said wire will be engaged by external surface portions of said fingers and pushed into said slot.

4. Connecting means as set forth in claim 3 including a film of insulating material bonded to the external surface of said connecting means.

5. Connecting means as set forth in claim 4 including a second tongue struck from said web, said second tongue being spaced from said first tongue and extending generally parallel to said first tongue, and each of said sidewalls having a third finger extending therefrom, said first fingers being between said tongue and said second tongue, and said third fingers being on the opposite side of said second tongue from said first fingers.

6. Connecting means as set forth in claim 5, and contact means integral with and extending from said connecting means for making contact with a further conductor.

7. Connecting means as set forth in claim 5, said additional tongue having a slot therein which is relatively more narrow than the said slot in said tongue, said slot in said additional tongue having a width which is significantly less than the diameter of the conducting core of said wire.

8. Connecting means as set forth in claim 4 and a second connecting means which is substantially identical to said connecting means, said connecting means and said second connecting means being in axial alignment and said web of said connecting means being integral with the web of said second connecting means.

9. Connecting means for forming an electrical connection with a wire, said connecting means comprising a stamped and formed member having:

a generally U-shaped cross-section comprising a web and sidewalls,

a pair of spaced-apart tongues struck up from said web, said tongues defining planes which extend transversely of said web and said sidewalls, each of said tongues having a wire-receiving slot extending inwardly from its free end,

first, second, and third fingers extending from each of said sidewalls, said first fingers being between said tongues, said second and third extensions being on the opposite sides of said first fingers,

said fingers each comprising a proximate section which is integral with, and which extends in the same general direction as, its respective sidewall and each finger further comprising an end section extending obliquely towards the opposite one of said sidewalls, said end section being connected to said proximate section by a reverse bend,

said tongues having a height, relative to said web which is greater than the height of said sidewalls and the upper edges of said sidewalls being above the inner ends of said notches whereby,

upon locating a wire between said end sections of said fingers and upon curling said fingers inwardly and downwardly towards said web, said wire will be centered by said fingers and forced into said slots.

10. An electrical connecting device for making a butt connection between two wires, at least the end portions of said wires extending axially towards each other, said connecting device comprising:

a generally channel-shaped cross-section having a web and having sidewalls extending from the longitudinal sides of said web,

a connecting means proximate to each end of said connecting device, each connecting means comprising a pair of tongues struck up from said web, said tongues being spaced apart along the length of said connecting device and defining planes which extend transversely of said web and transversely of said sidewalls, each of said tongues having a free end and having a wire-receiving slot extending inwardly from said free end, said slots being centrally located in said tongues and lying on the longitudinal axis of said connecting device, said tongues having a height relative to said web which is greater than the height of said sidwallls and the upper edges of said sidewalls being above the inner ends of said notches,

each connecting means further comprising first, second, and third finger-like extensions on each of said sidewalls, the first finger-like extension of each sidewall being between said tongues and having a width which is less than the spacing between said tongues, each said first finger-like extensions comprising a proximate section which is integral with, and extends in the same direction as, its respective sidewall, and an end section having a reverse bend and extending generally obliquely towards said web,

said second finger-like extension of each sidewall being on one side of said first extension and being proximate to the one of said tongues which is adjacent to an end of said connecting device, said third finger-like extension being on the other side of said first extension and being proximate to the one of said tongues which is remote from said one end of said connecting device,

said second and third finger on each sidewall having proximate and end sections which are at least similar to said proximate and end sections of said first extension whereby,

each of said wires can be connected to said connecting device by means of one of said connecting means by locating said wire with its axis extending between said fingers and curling said fingers inwardly towards each other and towards said web, whereby said fingers will engage said wires and push said wires into said slots.

11. An electrical connecting device as set forth in claim 10, each of said connecting means having fourth finger-like extensions which are spaced from said second finger-like extensions and adjacent to an end of said connecting device, said fourth finger-like extensions serving to center said wires at the ends of said connecting device.

12. An electrical connecting device as set forth in claim 10, each of said connecting means having fourth finger-like extensions which are spaced from said third finger-like extensions and adjacent to an end of said connecting device, said fourth finger-like extensions having proximate and end sections, said proximate sections of said fourth finger-like extensions being relatively shorter than said proximate sections of said first, second, and third finger-like extensions.