EP0112051B1

EP0112051B1 - Electrical contact for terminating insulated conductors

Info

Publication number: EP0112051B1
Application number: EP83306991A
Authority: EP
Inventors: Weldon L. Brubaker; Arnold A. Case
Original assignee: Molex LLC
Current assignee: Molex LLC
Priority date: 1982-11-22
Filing date: 1983-11-16
Publication date: 1986-10-29
Also published as: GB2130820B; JPS59103285A; JPH059906B2; GB2130820A; GB8330616D0; DE3367304D1; USRE32810E; EP0112051A1

Description

This invention relates generally to electrical contact members for terminating insulated conductors, and specifically, to a contact member having the capability of terminating a conductor without prior removal of the conductor's insulative coating.
A wide variety of methods and devices are available for terminating an insulated electrical conductor such that the conductor may provide a reliable electrical connection between circuitry apparatus of diverse type. Because of its inherent economies, a preferred method involves terminating a conductor to a contact member without prior stripping or removal of the insulative coating covering the conductor. Such a method is particularly well suited for use in the telecommunications or data processing industries, wherein electronic equipment is often field-installed or serviced. By eliminating the step of stripping the insulation from the conductor, significant economics are possible in the wiring of electronic or electrical apparatus.
Two such methods have become widely accepted, namely, insulation piercing and insulation displacement. The former case is illustrated in DE-A-2,525,221 where an electrical connection is established between conductors through the use of a barbed contact member having a pair of barbs which have been forced one through the insulative coating of each of the conductors. A further contact member of the barbed type is disclosed in US-A-4,054,350 illustrating the termination of a multi-conductor cord through the use of blade-like terminals having barbs. In the case of the latter method, the insulative coating of the conductor is severed by the edges of a slot formed in a contact member permitting the insulative coating to be displaced in the region of the connection. This method is disclosed, for example, in GB-A-2,037,493 and US-A-4,217,022. Further, US-A-4,346,955 describes a self-stripping contact member having the latter method in which the slot is formed between a pair of edges of resilient arms such that the arms can deflect to accept a range of conductor diameters in the slot.
In practice, the selection of termination methods as between insulation piercing and insulation displacement, depends primarily upon the construction of the conductor which is to be terminated. Insulated conductors in wide-spread use may fall in three general categories, namely solid core, stranded wire or tinsel wire.
Solid core conductors, which typically comprise a unitary core of conductive material covered with a dielectric coating, are best suited for insulation displacement techniques because of the relative rigidity of the central core. Conversely, piercing methods are generally unreliable for use with a solid core conductor.
Stranded wire usually has a core consisting of a plurality of relatively thin conductive members grouped together. This type of wire may be terminated by either insulation piercing or insulation displacement, if suitable precautions are taken in the design of the contact member to assure a reliable electrical connection to the terminated wire.
Tinsel conductors typically comprise a plurality of tinsel ribbons wrapped helically about a filamentary core with the resulting assembly enclosed in a textile braid or nylon jacket. This type of conductor is known to be unsuitable for termination by insulation displacement, inasmuch as the filamentary core is too soft to provide for appropriate contact forces between the contact member and the tinsel ribbon.
Because all of these conductor types are in widespread use, particularly in the telecommunications field, there is a need to provide a single contact member which has the capability of terminating any one of these conductors as needed.
This invention provides a contact member for forming an electrical connection with an insulated conductor, the contact member including a plate having an open slot therein defining a pair of opposed edges for severing and displacing the insulation of a conductor inserted therebetween, the slot having a mouth open to an edge of the plate and leading to a relatively narrow section for receiving and terminating the conductor to the contact member, and deflectable insulation piercing means spaced laterally from said plate in alignment with the slot of the plate for piercing the insulation of the conductor upon its termination to the contact member whereby said insulation piercing means engages a pierceable conductor to terminate the pierceable conductor to the contact member and is deflected by an unpierceable conductor to allow the unpierceable conductor to be terminated to the contact member in the relatively narrow section of said slot.
Preferably, the contact member includes a second plate having an insulation displacement slot therein spaced apart and generally parallel to the first plate, and means for supporting the plates and the insulation piercing means such that the slots of the plates and the insulation piercing means are aligned along a common axis with the insulation piercing means disposed between the plates.
With this arrangement, the slots provide alignment between the conductor and the intermediate insulation piercing means.
The invention includes a connector assembly including a housing fitted with contact members as defined in the immediately preceding paragraph.
Specific embodiments of the present invention will now be described by way of example, and not by way of limitation, with reference to the accompanying drawings in which:-

FIG. 1 is a perspective view of a connector assembly of this invention fitted with contact members of this invention;
FIG. 2 is a plan view of a blank from which the contact members shown in Fig. 1 may be formed; and
FIG. 3 is an enlarged perspective view of one contact member in its fully formed state.

Referring now to the accompanying drawings, in Fig. 1, the connector assembly is designated generally by the reference numeral 10. The connector assembly 10 is of a type suitable for use in telecommunications applications and comprises a dielectric housing 12 fitted with a plurality of contact members 14 for forming electrical connections with respective insulated conductors 16. The housing 12 includes a plurality of internal partitions 18 which define recesses 20 for receiving and electrically isolating the contact members 14. An opening 22 in the housing 12 allows for exit of the terminated conductors 16, and suitable strain relief formations 24 are provided internally of the housing 12 to aid in the prevention of dissociation of the conductors 16 from the contact members 14.
Extending from sidewalls 26 of the housing 12 by means of a plastics living hinge arrangement 28 are a plurality of termination tabs 30 corresponding in number to the number of contact members 14 housed within the assembly 10. The termination tabs 30 carry ram blocks 32 and 34 which are receivable within the recesses 20, for purposes which will be described in greater detail hereinafter. Ramp-like latching projections 35 extend from the sides of the blocks 34.
In order to seal the housing 12, the connector assembly 10 includes a suitable cover 36 connected to the housing 12 by means of an integrally formed hinge 38. By a number of well-known latching arrangements, the cover 36 may be adapted to snap fit over the housing after tabs 30 and blocks 32 and 34 are received within their respective recesses 20.
Turning now to Fig. 2, the contact member 14 illustrated in Fig. 1 is shown as it would appear in the form of a stamped, sheet metal blank, designated generally by the reference numberal 14'. The blank 14' is preferably a unitary piece of relatively thin, highly conductive material. The contact member 14 includes a central body portion 40 from which an elongated, blade-like terminal portion 42 extends providing an electrical contact member for connection to other circuitry apparatus (not shown). Extending from the opposite side of the body portion 40 is a retention tab 44. Both the terminal portion 42 and tab 44 have a pair of ears 46 extending laterally therefrom for retaining the contact member 14 in a recess 20 between a pair of the partitions 18 formed in the housing 12 with the body portion 40 and the lower edges of a pair of plates 56, yet to be described, seated on an opposite pair of shoulders 18' formed on the two partitions respectively. The body portion 40 also carries a pair of wings 48 connected to the body portion 40 by support members 50. Each wing 48 is the mirror image of the other and is seen to include an insulation displacement portion 52 adapted to be firmly seated with the body portion 40 and an insulation piercing portion 54 adapted to be flexibly supported relative to the body portion 40.
The insulation displacement portion 52 is further adapted to form an electrical connection with an insulated conductor by severing and displacing the insulative coating of the conductor core. To this end, the plates 56 are provided and each includes a slot 58 having a mouth 60 opening to an upper edge of the plate 56.
The insulation piercing portion 54 is intended to establish an electrical connection with an insulated conductor by the method of piercing the insulative coating, and therefore, is formed with an arm 62 having an opening 64 for guiding the insulated conductor. The opening 64 is generally U-shaped and at its bight portion has an upwardly pointing barb 66. The support members 50 are adapted with latching apertures 68, the operation of which will be described in greater detail hereinafter.
In Fig. 3, the contact member 14 is shown as it would appear in a fully formed state. As seen, therein, the wings 48 are bent upwardly on their support members 50 and each plate 56 is bent through an angle of ninety degrees such that plates 56 are substantially parallel one to another. Similarly, each arm 62 of the insulation piercing portions 54 is bent at right angles so as to reside in a plane which is substantially parallel to the planes of the plates 56. Because of this resulting U-shape forming of the wings 48, the insulation piercing barbs 66 and insulation displacement slots 58 are all aligned along a common axis of termination designated generally by the reference numeral 70.
Referring to Figs. 1 and 3, it will be apparent that manual termination of a conductor to the assembly 10 can be readily accomplished by positioning the conductor 16 over the contact member 14 in alignment with the mouths 60 of the insulation displacement slots 58, and correspondingly, in alignment with the U-shape openings 64 of the insulation piercing arms 62. Then, by pivotal movement of the associated tab 30 about its hinge 28, the ram blocks 32 and 34 may be brought in contact with the conductor 16 and further pressed within the contact member 14. The conductor is, thereby, forced into the slots 58 which sever and displace the insulative coating of the conductor 16. Contemporaneously, the insulative coating is pierced by the barbs 66 of the insulation piercing portion 54 of the contact member 14 and the conductor 16 assumes a terminated position along the axis 70. The latching projections 35 thereupon engage the upper edges of the apertures 68 of respective contact members 14, thereby retaining the conductors 16 in seated position against the advent of vibration.
It can be appreciated from the foregoing description that when a tinsel conductor, for example, is terminated to the contact member 14, the barbs 66 provide for effective termination of the tinsel conductor by piercing its insulative coating and establishing contact with the tinsel ribbon. Correspondingly, when it is desired to terminate either a stranded or solid core conductor, the insulation displacement slots 58 provide for the effective termination of those conductor types as well. As best seen in Fig. 3, the insulation piercing portion of the contact member 14 is spaced above the body portion 40 by appropriate dimensioning of the support member 50. Because the arms 62 are, thereby, cantilevered over the body 40, a solid core conductor can cause the arms 62 to deflect downwardly due to natural resilience of the arm material and the inability of the barbs 66 to penetrate the core of the conductor if this proves necessary. Therefore, the barbs 66 cannot interfere with the action of the insulation displacement slots 58 in providing effective electrical contact between a solid conductor core and the contact member 14.

Claims

1. A contact member (14) for forming an electrical connection with an insulated conductor (16), the contact member including a plate (56) having an open slot (58) therein defining a pair of opposed edges for severing and displacing the insulation of a conductor (16) inserted therebetween, the slot having a mouth (60) open to an edge of the plate and leading to a relatively narrow section for receiving and terminating the conductor to the contact member characterised by deflectable insulation piercing means (54) spaced laterally from said plate (56) in alignment with the slot (58) of the plate for piercing the insulation of the conductor upon its termination to the contact member (14) whereby said insulation piercing means (54) engages a pierceable conductor to terminate the pierceable conductor to the contact member (14) and is deflected by an unpierceable conductor to allow the unpierceable conductor to be terminated to the contact member (14) in the relatively narrow section of said slot (58).

2. The contact member of claim 1 wherein the insulation piercing means comprises a barb (66) pointed generally in the same direction as the slot opening.

3. The contact member of claim 1 or 2 wherein the insulation piercing means (54) and plate (56) are formed from a single piece of thin conductive sheet metal (14') which is reversely formed into a generally U-shape, the legs of the U defining a pair of substantially parallel planes, the insulation piercing means (54) and plate (56) being disposed each in a respective one of said planes.

4. The contact member of claim 3 wherein the insulation piercing means (54) comprises an arm member (62) formed integrally with and reversely bent from the plate (56) and the arm (62) is deflectable with respect to the plate (56) upon interaction of the insulation piercing means with a solid core conductor (16) which has been terminated to the contact member.

5. The contact member of claim 4 including a body portion (40) having a support member (50) extending therefrom for supporting the insulation piercing means (54) in suspended disposition over the body portion (40).

6. The contact member of claim 6 including means (42) formed integrally with the body portion (40) for electrical connection of the contact member to a circuit device.

7. The contact member of claim 1 including a second plate (56) having an insulation displacement slot (58) therein spaced apart and generally parallel to the first plate (56), and means (40, 50) for supporting the plates and the insulation piercing means such that the slots (58) of the plates and the insulation piercing means (54) are aligned along a common axis (70) with the insulation piercing means (54) disposed between the plates (56).

8. The contact member of claim 7 including a second deflectable insulation piercing means (54) disposed with its slot (58) aligned along said common axis (70) between said plates (56).

9. The contact member of claim 8 wherein each insulation piercing means (54) comprises an arm member (62) reversely bent from the adjacent one of said plates (56), the arm members (62) extending in opposite directions and being deflectable with respect to the plates (56) upon interaction of the insulation piercing means with a solid core conductor (16) terminated to the contact member.

10. A connector assembly including a housing (12) fitted with contact members (14) as claimed in any preceding claim.