GB2190546A - Slotted insulation displacement connectors - Google Patents

Abstract

An insulation displacement connector 10 comprises a single metal body 12 from which is formed a connector element comprising at least two longitudinally spaced slotted beams 16, 18 arranged in opposition to one another. On crimping, the wires are held in slots 20, 22 and the beams cut through the insulation and penetrate the conductors to provide the electrical connection. Further, there remains a residual spring load delivered from the connector body to the slots enhancing the electrical connection. A second connector element may be included in the connector adjacent the first connector element such that, on crimping, one beam of the first element lies between the opposite beams of both elements or such that, on crimping, one beam 18 of each element lies between the opposite beams 16 of both elements. Additional connector elements (not shown) spaced from the first connector element may also be included and, by grading the width of the slots, wires of a wide range of diameters can be jointed. Wire entry guide holes can be provided in the metal body. An insulating sheath 26 for the connector may also be provided. <IMAGE>

Description

SPECIFICATION Insulation displacement connectors Description The invention relates to insulation displacement connectors, which are used for the electrical connection of insulated conductors. In particularthe invention relates to insulation displacement connectors of the type in which the insulated wires to be connected are pressed into slots formed from metal beams. The connectors are of particular use in telecommunication installations.

Backgroundofinvention In conventional insulation displacement connectors ofthis type, the insulated wires are pressed into slots in a metal beam by a guide member orfinger usually formed of plastics material. The metal beam requires support of some kind, andthis is usually provided bya plasticsframe.

There is thus a minimum ofthree parts, all of which have to be accurately constructed and mated. The wires emerging from the connector must be gripped in some way, as the electrical connection is sensitive to mechanical disturbance. Some connectors have a second slotted metal beam to grip the wires lightly and/or a port adapted to hold the wires loosely.

These arrangements are seldom fully effective in protecting the electrical connection from mechanical disturbance. The second beam, if present, does not necessarily contribute to the electrical connection, which is usually solely reliant on a single bite on each conductor. This is statistically unsatisfactory, and a failed connector can be extremelyexpensiveto locate and replace. Even if the connector is not subjected to mechanical disturbance, the connection may be adversely affected by the differential thermal expansion ofthe metal and plastics materials.

Inventive features The invention provides an insulation displacement connector for electrically connecting at leasttwo insulated conductor wires, the connector comprising a connector element having first and second slotted metal beams arranged such that, on crimping, each wire is disposed in two slots diametrically opposed but longitudinally offset with respect to the wire, characterised in that the first and second slotted metal beams are upstanding from a single metal body.

The metal body is formed from a single piece of sheet metal, preferably thin sheet metal, such as phosphor bronze. The slotted beams may then be punched from the sheet, and the sheet rolled to the desired configuration. This may be a substantially oval shape for a butt end connector; the edges ofthe sheet are preferably not joined. The desired configuration may alternatively be a U-shape; a special crimping tool will then be necessary to ensure the correct closure ofthe connector element.

A connector according to the invention preferably further comprises a second connector element formed from the metal body. The two connector elements may be arranged such that, on crimping, the first slotted beam ofthe first element lies between the second slotted beam of the first element and the second slotted beam ofthe second element.

Alternativelythetwoconnectorelements maybe arranged such that, on crimping, the first slotted beams ofthe elements both lie between the second slotted beams of the elements.

Aconnector according to the invention may further comprise an additional slotted beam formed from the metal body and arranged such that, on crimping, the first slotted beam of the element lies between the second slotted beam of the element and the additional slotted beam.

One or more additional connector elements may be formed from the metal body. These may, if desired, be longitudinally spaced from the first connector element.

Desirably the widths of the slots decrease along the length ofthe connector. This gradation enables wires of varying thicknesses to be accommodated more easily, with greater reliability ofthe making and permanence ofthe electrical connection.

A connector according to the invention may be provided with a plastics insulating sheath. For a butt end connectorthis may have a closed end and a port end; the portend may be provided with funnel shaped wire entries. These serve both to guide the wires towards the connector elements and, when crimped, will resist mechanical disturbance. For a U-shapedconnector,thesheath may have an index hole, so that many connectors may be strung together and fed to an automatic or hand crimping machine.

The connectors according to the invention provide at least two bites on each wire, one from the upper beam and one from the lower beam. Usually more bites will be provided; there will be one bite for each slotted beam in a connector. No problems arise as a resultof plastics/metal differential thermal expansion. No parts are required to fit precisely together so that the manufacturing tolerances are lower.

Drawings The invention is illustrated by the drawings, of which: Figure lisa partially perspective view of a butt end insulation displacement connector according to the invention, including an insulating sheath for the connector; Figure2 is a sectional elevation taken aboutthe lineA-Ain Figure 1; Figure3 is a sectional elevation taken aboutthe line C-C in Figure 1; Figure4 is a sectional plan taken about the line B-B in Figure 1; Figure5is a sectional elevation similar two Figure 2 but showing the connector in the crimped condition; Figure 6is a sectional elevation showing the port end of the sheath.

Figure 7 is an end elevation of the port end ofthe sheath; Figure 8 is a sectional elevation similarto Figure 2 but illustrating a U-shaped connector according to the invention; Figure 9 is a sectional plan view similar to Figure 4 but illustrating a further embodiment of a connector according to the invention; Figure 70 is a partially perspective view of a further insulation displacement connector according to the invention; Figure 11 is a sectional elevation taken about the line D-D in Figure10and including an insulating sheath forthe connector; Figure 12 is a sectional elevation taken about the line E-E in Figure 10; Figure 13 is a sectional elevation similarto Figure 12 butshowing the connector in the crimped condition;; Figures 14to 17 are views similar to those of Figures lotto 13, butshowavariation ofthe embodiment illustrated in the earlier Figures, the insulated sheath being omitted; Figure 18 is a perspective view of a yet further insulation displacement connector according to the invention; and Figure 19 is a sectional elevation similar two that of Figure 12 but showing the connector of Figure 18, the insulating sheath being omitted.

Description ofparticular embodiments With reference to Figures 1 to 7 of the drawings, a butt end insulation displacement connector 10 comprises a metal body 12. From this metal body 12 is formed two connector elements, each ofwhich comprises a lower metal beam 16 and an upper metal beam 18. The lower metal beams 16 are formed with slots 20 and the upper metal beams with slots 22. The beams 16 and 18 have been formed by punching them from the metal body 12; the latter has then been rolled to the oval shape shown leaving a split 24 which intersects the upper beams 18.

The metal body 12 is enclosed in a plastics sheath 26 formed with a closed end 28 and a portend 30.

The port end 30 has two funnel entries 32 to allowfor insertionofinsulatedwires34,anannulargroove36 to accommodate an end portion ofthe metal body 12 and a split 38 allowing the end 28 to be opened for original insertion ofthe metal body 12.

In use, the two insulated wires 34 to be joined are inserted through the funnel entries 32 in the port end 30 ofthe sheath 26. The funnel entries 32 guidethe wires 34so that they extend through the connector element as shown in Figure 2. Pressure isthen applied to the connector 10 using a crimping tool (not shown), and the slotted beams 16 and 18 close about the wires 34 as shown in Figure 5.

The wires are trapped in the slots 20 and 22 and the beams 16 and 18 cutthrough the insulation 40 of the wire and into the bare conductors 42. Each wire is subjected to four bites. Two derive from the two upper beams and two from the two lower beams. A good electrical connection is therefore assured.

Figure 8 shows an arrangementfora U-shaped connector. In this embodimentthe metal body 12 has been rolled to a U-shape after punching outthe beams 16 and 18. The wires 34 are simply laid on the lower beams 16 as shown and a special crimping tool used to close the connector to a condition similarto that shown in Figure 5. The plastics sheath 26 may be formed with an indexing hole 45 so that a large numberof such connectors can be strung together and fed to a machine for inserting wires and crimping.

The embodiment of Figure 9 is similar to that described with reference to Figures 1 to 7, but has two additional connector elements 44 longitudinally spaced from the connector elements 14. The arrangement of the additional connector elements 44 is the same as that of the connector elements 14.

Metal tongues 46 formed from the metal body 12 stand up at about 45". These help guide the wires 34 towardstheslots and, on crimping, grip the wiresto help prevent breakage ofthe electrical connection by mechanical disturbance. Further wire guides 48 are also formed in the sheath 26.

Referring now to Figures 10 to 13 of the drawings, the illustrated connector 10 again comprises a metal body 12 from which has been formed two conductor elements 14 each comprising a lower metal beam 16 formed with slots 20 and an upper metal beam 18 formed with slots 22. This connector 10 is formed from a single flat strip of metal. An inverted U-shape is formed in the centre of the length of strip, and the slots 20 are punched in it. The slots 22 are punched in the ends of the flat strip and wire entry holes 50 are also punched in the strip, which is then rolled to the form shown.

Avariation of this last embodiment is shown in Figures 14to 17 ofthe drawings. The upper beams 18 are cut back at each end as at 52, and a slot 54 in the inverted U-shaped portion enables the upper beams 18 to pass through the lower beams 16 on crimping, as shown in Figure 17.Thisgives an improved alignment and therefore an improved connection.

In all forms of the connector specifically described thusfar,the act ofcrimping, apartfrom wedging the wires in the slots, causes a further spring load on the wires to be delivered from the metal body of the connector. The initial load from the crimping action causes the upper slots to engage the wires. The load then moves to the sides of the body, sharpening the radius at these points and causing the upper slots to be loaded downwards by cantilever action from the sides ofthe metal body.

On release ofthe crimping load, the relaxation and upward movement ofthe sides ofthe connector are less than the available spring movement of the cantilever portion bearing down on the slots. There is thus a residual spring load on the wires. Because there is a much greater amount of metal in the body ofthe connectorthan in the beams, the stored energy available and therefore the permanence of the electrical connection is considerabiy enhanced.

Another embodiment is shown in Figures 18 and 19. These drawings will be readily understood from the earlier description, without specific description here. This embodiment alone does not have the advantage ofthe cantilever load referred to in the last paragraph, but the force delivered to the slots from the bent outer members on crimping will lockthe body in this position by frictional force and prevent relaxation of the crimping load. However, the wire entry holes 50 are particularly close to the slots 20 and 22, ensuring that positive location of the wires before crimping is easily achieved. The connector also occupies a smaller space in the crimped state.

Claims (13)

1. An insulation displacement connectorfor electrically connecting at least two insulated conductor wires, the connector comprising a connector element having first and second slotted metal beams arranged such that, on crimping, each wire is disposed in two slots diametrically opposed but longitudinally offset with respect to the wire, characterised in that the first and second slotted metal beams are upstanding from a single metal body.

2. A connector according to claim 1 characterised in that the connector further comprises a second connectorelementformed from the metal body, the two connector elements being arranged such that, on crimping, the first slotted beam ofthefirst element lies between the second slotted beam of the first element and the second slotted beam ofthe second element.

3. A connector according to claim 1 characterised in that the connector further comprises a second connector element formed from the metal body, the two connector elements being arranged such that, on crimping, the first slotted beams of the elements both lie between the second slotted beams ofthe elements.

4. A connector according to claim 1 characterised in that the connectorfurther comprises an additional slotted beam formed from the metal body and arranged such that, on crimping, the first slotted beam of the element lies between the second slotted beam ofthe element and the additional slotted beam.

5. A connector according to any preceding claim characterised in that the connectorfurther comprises one or more additional connector elements formed from the metal body.

6. A connector according to claim 5 characterised in thatthe or each additional element is longitudinally spaced from the first connector element.

7. A connector according to any preceding claim characterised in that the widths ofthe slots decrease along the length of the connector.

8. A connector according to any preceding claim characterised in that the connectorfurther comprises a plastics sheath.

9. A butt end connector according to claim 8 characterised in that one end of the sheath is a closed end and the other end of the sheath is a port end having funnel shaped entriesforthewires.

10. A U-shaped connector according to claim 8 characterised in that the sheath is provided with an index holeforfeeding to a crimping machine.

11. Aconnectoraccording to any of claims 1 to8 characterised in that wire entry holes are provided in the metal body.

12. An insulation displacement connector according to claim 1 in which, after crimping, there remains a residual spring load delivered from the connector body to the slots. This load delivered at right angles two the force from the slotted beams stores additional energy which enhances the electrical and mechanical performance ofthejoint and arises as follows. The act of crimping, apart fro wedging the wires in the slots, causes a further spring load on the wires delivered from the metal body. The load from the crimping action passes from the slots to the sides of the body sharpening the radius at these points causing the upper slots to be loaded downwards by cantilever action from the sides of the body. On release the upward movement ofthe sides is less than the available spring movement of the cantilever portion bearing down on the slots giving a final residual spring loading.

13. An insulation displacement connector substantially as described herein with reference to the drawings.