Technical Field

This invention relates to a device for removing a length of the sleeving surrounding the conducting core of an electrical wire from one end of the wire to leave a bared end for connecting the wire to another conduccing component. Such devices are known and are often referred to as wire strippers.

A device in accordance with this invention can serve as a wire stripper per se but could be incorporated in the housing of an electrical connector (e.g. a 2-pin or 3-pin plug) for use in the wiring-up of the connector. The invention finds particular application in association with connectors of the kind described in GB-B-219859S (the entire disclosure of which is incorporated herein by reference) .

GB-A-2069247 discloses a multi-pin electrical plug in which a separate stationary blade stripper is provided for each pin and GB-A-2086149 discloses a blade fixedly mounted on a plug housing to facilitate wire stripping.

Summary of the Invention

According to the invention a device for removing a length of the sleeving surrounding the conducting core of an electrical wire from one end of the wire to leave a bared end for connecting the wire to another conducting component comprises; a recess to receive the end of the wire, a slot intersecting the recess intermediate its ends, a blade movable along the slot to extend part way only across the recess, and means mounting the blade for such movement.

Desirably the device is usable with wires of different gauge and this can be achieved with two or more adjacent recesses in the form of circular bores of different diam-

eters, or with a tapering elongate recess. The elongate recess can be formed from two or more intersecting circular holes of different diameter or it could be a smooth sided recess which is narrower at one end than the other (i.e. generally "tear-drop" shaped in plan) . In the case of an elongate recess the blade moves through the recess in the direction towards the narrower end. This has the effect of making a tear-drop shaped recess suitable for a range of different gauges of wire (e.g. core diameters and/or sleeve thicknesses) each wire being moved by the blade as far towards the narrower end of the recess as the cross-section of the sleeved wire will allow. In the case of an elongate recess formed from intersecting holes, the restrictions in the cross-section of the recess at the point where two holes intersect may prevent a wire moving beyond the restriction under the influence of the blade. Since the blade extends only part way across the recess or recesses, it cuts the insulation on one side of the core at the level of the slot and can then be used to prevent the length of insulation sleeving below the cut leaving the recess with the core as the wire is pulled out of the recess. If a blind recess closed at its lower end is used (and a blind recess is convenient if wire stripping to a pre-set length of bared end is required) the stripped length of sleeving will be left in the recess but can easily be removed when the blade is drawn back along the slot and the recess inverted.

Where there are two or more recesses for different wire gauges they can share a slot and blade, but a blade for each recess is also possible.

By forming the recess in the outer part or cap of the housing of an electrical plug and mounting the blade on a core part of the plug turnable relative to the outer part, it is possible, in a simple manner, to provide the plug with means to strip just the right length of sleeving off the end of each wire needed for a subsequent wiring-up of

the plug .

Brief Description of the Drawings

The invention will now be described, by way of ex ample, with reference to the accompanying drawings, i which:-

Figure 1 is a plan of a recess containing wires of tw different diameters,

Figure 2 is a scrap section showing a wire in th recess, the blade and the slot along which it travels,

Figure 3 shows a rewirable three-pin electrical plu in side elevation with a two-wire cord being prepared fo wiring into the plug,

Figure 4 shows the underside of the rewirable plug o Figure 3 provided with a wire stripper and with one wir end of the cord inserted in the recess for end stripping,

Figure 5 shows the plug of Figure 4 after the cut has been made and prior to removal of the wire end from the recess, and

Figure 6 shows the cord after stripping of one wire.

Description of Preferred Embodiment

Figures 1 and 2 show the principle behind a wire stripping device according to the invention. A generally tear-drop shaped recess 10, having a narrower end 11 and a wider end 12 is formed in a body part 13A. A slot 14 intersects the recess and provides a passage along which a cutting blade 15 moves. The blade 15 is attached to a second body part 13B movable relative to the part 13A in the direction of the arrow A. The blade 15 protrudes less than half-way across the recess 10 but is long enough to remain embedded in the sleeving of any wire within the

recess 10 when it makes a cutting stroke along the slot 14.

The shape of the recess allows wires of different diameter to be end-stripped, any given wire being carried by the blade 15 as far as possible towards the end 11, before becoming wedged in the recess 10 as the blade makes a cut through the sleeving of the wire. A small diameter wire 20 and a larger diameter wire 21 are shown in Figure 1 to illustrate the automatic compensation for wire size achieved by the device.

Once the blade 15 is in place partially obstructing the recess 10 (see Figure 2), removal of the wire 20 in the direction of the arrow B will strip bare the end of the core below the blade 15, the removed length of sleeve being held in the recess by the blade. Moving the blade back out of the recess in the direction of the arrow C will release the sleeve end so that it can be shaken out of the recess on inverting the parts 13A, 13B.

Figures 3 to 6 show a practical embodiment of the stripping device, the recess 10 being formed in a cap part 13A surrounding a core part 13B of a three-pin plug 30. A cord 31 has the core sleeving removed over a length longer than W + w and each wire 32, 33 is cut to the length W + w prior to stripping. Cutting of the wire end to the correct length (W + w) and stripping the insulation off the correct length (w) may be facilitated by providing some form of gauge on the plug 30. Figure 3 shows a gauge 34 moulded on the plug (as shown, on the side of the cap part of the plug) to indicate these lengths.

Figures 4 and 5 show wire 32 inserted in the recess 10 with the plug 30 in its non-use (or open) state and the core part 13B is turned as shown by the arrow D in Figure 5 to move the blade 15 (not shown in Figures 4 and 5) into the recess 10. Pulling the cord 31 upwardly strips sleev¬ ing of length w from the end of the wire 32, this length

being dictated by the location of the slot 14 above the bottom of the recess 10.

The operation can then be repeated on wire 33, by returning the core part 13B to the open state of the plug, inverting to remove the sleeve length cut from wire 32 and repeating the stripping operation on wire 33.

The plug 30 shown in Figures 3 to 5 is described in greater detail in the aforesaid GB-B-2198598. The core part 13B mounts projecting contact pins 40, 41 and 42 (these being an earth pin, a live pin and a neutral pin), the wires 32 and 33 being destined to make electrical contact with pins 41 and 42 on wiring-up of the plug. Secure electrical contact is achieved by means of wire traps incorporated partly in the core part 13B and partly in the cap part 13A. The wire traps are open in the condition of the plug shown in Figure 4 but closed to make secure electrical connection with bared wire ends inserted therein in the condition shown in Figure 5. It will be appreciated therefore that the same relative turning action between the housing parts 13A and 13B used to strip each wire end is required to wire-up the plug providing a very convenient dual purpose for the turnable mounting of the core part 13B in the cap part 13A.

Although only a two-wire cord 31 has been shown in the drawings, if a three-wire cord is to be used (i.e. with an earth wire for connection to contact pin 40) the stripp¬ ing action described would be repeated a third time to prepare the earth wire for insertion in the concealed wire traps when the wiring-up operation is undertaken.

A carrier 50 (containing a cartridge fuse 51) is also shown in Figures 4 and 5 and this can be used to lock the housing parts in the relative disposition shown in Figure 5 when it is closed down into the recess 52. When so in¬ serted in the recess 52, the fuse 51 is electrically

connected between the wire trap holding the live wire and the live contact pin 41.

The recess 52 forms part of access passages leading to the wire traps in the condition of the housing shown in Figure 4.