GB2173053A

GB2173053A - An electrical conductor socket terminal and method of producing the same

Info

Publication number: GB2173053A
Application number: GB08606872A
Authority: GB
Inventors: Andre Benani; Jean-Marie Millet
Original assignee: Telemecanique Electrique SA
Current assignee: Telemecanique SA
Priority date: 1985-03-27
Filing date: 1986-03-20
Publication date: 1986-10-01
Also published as: GB8606872D0; IT8647819A0; FR2579836A1; JPS61263071A; DE3610086A1; FR2579836B1; IT1191871B; GB2173053B; KR860007761A; HK96391A

Abstract

A terminal is formed from metal sheet into a tube (1) having contiguous edges (5) and also includes a moulded insulated skirt (3). A tube may be formed from a long flat blank and then cut to form tubular contacts. The stripped end of a multi-strand wire (not shown) is introduced into the tube and crimped therein. <IMAGE>

Description

SPECIFICATION Electrical conductor terminal and method of producing the same This invention relates to a terminal for an electrical conductor having an insulating sheath, of the type comprising a conductive metal tube adapted to receive the stripped end of the conductor and connected to a coaxial tubular insulating skirt adapted to cover the conductor sheath, and a method of producing this terminal.

This type of terminal used for connecting a multi-strand conductor to a clamp-type terminal, more particularly one using a screw, is already known from French patent 1 468 859, and has the advantage of allowing the stripped end of the conductor to be crimped in the terminal when connected to the receiving terminal.

However, a cable terminal of this kind has the disadvantage of requiring a relatively thick conductive tube which is expensive because it is produced by a known drawing process. The thickness of the tube imposed by the drawing operation therefore makes it necessary to apply a fairly large clamping force to the terminal clamping means in order to obtain effective crimping of the conductor and reliable electrical and mechanical connection qualities.

The object of the invention is to obviate these disadvantages nd provide a conductor terminal which is cheap to manufacture and which facilitates and improves clamping of the conductor in the connecting terminal.

Another object of the invention is to form the metal tubular part of the terminal not from a drawn tube as in the prior art but from a metal strip which may be very thin.

The invention therefore relates to a terminal for an electrical conductor having an insualting sheath and stripped at one of its ends, the terminal being adapted to crimp the stripped end of the conductor, and comprising a conductive metal tube adapted to receive the stripped end of the conductor, and a tubular insulating skirt connected to one end of the tube and adapted to cover the conductor sheath, characterised in that the tube has contiguous edges which are brought into contact with one another along a direction parallel to the longitudinal axis of the tube.

It will be apparent that in this way the tube has a weakened zone at the joint of its longitudinal edges, thus improving crimping of the conductor in the terminal when it is clamped to the receiving terminal.

According to another feature of the invention, the edges of the tube are brought into close contact without welding.

The invention also relates to a method of producing a terminal of this kind, characterised in that it comprises the following operations starting with a flat metal strip: the strip is brought into a tubular shape in which two of its opposite parallel edges meet together so as to form a tube having contiguous edges; and a tubular skirt of insulating material is fixed on one of the tube ends.

Other features and advantages of the invention will be more readily apparent from the following detailed description with reference to the accompanying drawings, which are given solely by way of example and wherein: Fig. 1 is a longitudinal section of a first embodiment of the terminal according to the invention.

Fig. 2 shows the step of forming the metal tubular part of the terminal according to the first embodiment.

Fig. 3 shows the terminal provided with notching.

Fig. 4 is a longitudinal section of a second embodiment of the terminal according to the invention.

Figs. 5 and 6 show some of the steps in the formation of the metal tubular portion of the terminal according to the second embodiment, and Fig. 7 shows the metal tubular part of the terminal, in which the edge joint is of notched shape.

In the various Figures, like elements which perform the same functions for the same results have been given like references.

According to a first embodiment shown in Fig. 1, a cable terminal according to the invention denoted by the general reference 1 consists mainly of a tube or a length of conductive metal tubing 2, for example of circular cross-section and of longitudinal axis XX', one of the ends of which is connected to a funnelshaped insulating collar or skirt 3 coaxial with the tube.

It will be seen that the metal tube 2 may also be of polygonal cross-section, e.g.

square, or of any other shape without departing from the scope of the invention.

According to one feature of the invention, the conductive tube 2 has contiguous longitu dinal edges contacting one another along a direction parallel to its longitudinal axis and it is produced from a thin flat metal band or strip of given length, as will be explained hereinafter.

Thus the contiguous-edge tube 2 shown in Fig. 1, having a circular cross-section and formed from a very thin strip, therefore has a very thin thickness e of the order of one-tenth of a millimetre, thus advantageously providing an improved clamping of the electrical conductor in the connecting terminal, and hence improved electrical and mechanical qualities for the connection.

Reference 5 in Fig. 1 denotes the rectilinear joint line of the edges of the cylindrical tube 2 along one of its generatrices.

The contiguous-edge cylindrical tube 2 may also be of small diameter thus advantageously allowing the terminal to be fitted to electrical conductors of small section.

The shaping of the metal strip into the tubular form so as to obtain the contiguous-edge length of cylindrical tubing will now be described with reference to Fig. 2.

The initial metal strip 7, made of copper for example and of thickness e, is moved in the longitudinal direction (arrow A) by any conventional means and is converted into a cylindrical tube 8 of thickness e by means of a mechanical element, for example a conventional die illustrated diagrammatically at 10. As they pass through this die, the two parallel longitudinal edges 7a and 7b of the strip meet closely together, i.e. without any clearance, and without any overlap, in the longitudinal direction and thus form the contiguous-edge cylindrical tube 8 in which the edges are in contact with one another without any need for welding along a generatrix of the tube.

The initial strip 7 may optionally be pretreated on its surface by metallization of its top and bottom surfaces, by means of a deposit of tin, silver or gold for example, thus advantageously giving at the die outlet a tube which is metallized both on the outside and the inside, thus providing anti-corrosion protection and improved electrical contact quality.

Once the tube 8 has been formed, it is cut, e.g. by means of a cutting wheel known per se, in the direction of the arrows B in Fig. 2, to given lengths, thus giving a plurality of contiguousedge tube lengths, one of which corresponds to the one illustrated at 2 in Fig. 1.

It will be apparent that the fact that a very long strip is formed into a tube and then the tube is cut advantageously enables these two operations to be performed continuously. It is however possible to carry out the cutting operation on the actual strip and then put each strip length into the tubular shape individually, without departing from the scope of the invention.

As will be apparent in Fig. 1, the end of the conductive tube on which the insulating tubular skirt 3 is fixed is slightly widened or flared, e.g. mechanically by means of a tool such as a broach, so that the metal part of the terminal may be anchored in the plastics of the skirt.

Reference 2a in Fig. 1 shows this part of the tube flared to an angle Al of the order of 30 , for example, with the longitudinal axis XX' of the tube. During the opening out of this tube end its contiguous edges move apart slightly forming a V-shaped notch as shown in Fig. 1. During this operation it is also possible to cut a plurality of other notches on the tube periphery.

The insulating skirt 3 coaxial with the tube is formed and fixed on its flared part by moulding on the tube with a plastic material of the polyamide type, e.g. of the kind known by the trade mark Rilsan. The skirt 3 is funnelshaped with a conical part 3a of angle A2 of the order of, for example, 40 with the axis XX' and in which the flared part 2a of the tube is rigidly embedded, and with a cylindrical part 3b having internal projections or ribs 12, e.g. three such projections, this cylindrical part being adapted to cover the sheathing of the electrical conductor.

Optionally, a tongue 14 may be provided on the skirt (Fig. 1) to receive indicia. A tongue of this kind is well known to the skilled addressee and is described in French patent 1 468 859.

Once the terminal 1 has been formed, the multistrand electrical conductor is introduced axially into the insulating skirt 3 after one of the conductor ends has been stripped, until the conductor sheathing abuts the end of the skirt. The conductor strands are then received in the conductive tubular portion 2 of the terminal, being parallel to its axis XX'.

When used for connecting a multi-strand conductor to a connector or screw terminal, the cable terminal provided with the conductor is crimped by the screw, which crushes the tube to clamp the conductor strands together.

The contiguous nature of the longitudinal edges of the tube enables the rigidity of the tube cross-section to be reduced, thus facilitating clamping and improving electrical contact.

When applied to a resiliently clamping terminal, the conductor terminal can be precrimped, e.g. by means of pliers, to compact the end of the conductive tubular part of the cable terminal to a polygonal, e.g. square, shape, thus providing optimum utilization of the terminal space, obviating the strands being cut by the clamping means, and giving good electrical contact and good mechanical stability between the terminal and the electrical conductor. Also, as shown in Fig. 3, the polygonal cross-section metal tubular part 2 of the terminal may have longitudinal edges provided with notches 15, thus advantageously improving the resistance to longitudinal stress on the conductor terminal.

A preferred alternative of the cable terminal according to the invention will now be described, which differs from the previous version only in that teeth are provided at the contiguous-edge conductor tube end on which the plastics skirt is moulded. These teeth are provided to give good anchoring of the metal part of the terminal in the plastics moulded thereon.

Fig. 4 is a longitudinal section of this alternative terminal 1 with a part of the tube 2 toothed at 18, and with the insulating skirt 3 moulded on this tube and having an identical construction to that described with reference to Fig. 1.

The teeth for each tube are formed by cutting notches in one of the longitudinal edges of the initial metal strip, which may have undergone surfacetreatment as previously, and then cutting the strip in the transverse direction with respect to its cut edge so that each strip length has a set of identical teeth 18 uniformly spaced apart, for example three such teeth being provided.

Referring to Fig. 5, reference 18 denotes the various teeth of the same depth produced after cutting of the strip 7 of thin thickness e.

These teeth are in groups of three, which are then separated from one another by cutting as shown by the arrows C.

Each toothed strip length is put into the tubular shape as before in a longitudinal direction XX' (Fig. 5) by bringing together its two opposite edges parallel to said direction so as to form a contiguous-edge tube terminating at one end, according to this alternative embodiment, in three teeth distributed uniformly over its periphery, i.e. disposed at 1200 in relation to one another.

Fig. 6 shows the contiguous-edge metal tube 2 after a length of metal strip has been put into the tubular shape and terminating in the three teeth 18.

This toothed end of the tube is also flared as before and acts as an anchoring for the moulded plastics forming the tubular skirt coaxial with the tube.

Fig. 7 shows the metal tube 2 of Fig. 1 with an edge joint line 5 in the form of notches. These notches are made by cutting each of the two longitudinal edges of the very long metal strip as shown in Fig. 2, and provide improved tube resistance to torsion during its cutting to given lengths. Of course it is possible for the tube joint line to have other suitable shapes without departing from the scope of the invention.

Claims

1. A terminal for an electrical conductor having an insulating sheath and stripped at one of its ends, the terminal being adapted to crimp the stripped end of the conductor, and comprising a conductive metal tube (2) adapted to receive the stripped end of the conductor, and a tubular insulating skirt (3) connected to one end of the tube and adapted to cover the conductor sheath, characterised in that the tube (2) has contiguous edges (7a, 7b) which are brought into contact with one another along a direction parallel to the longitudinal axis of the tube.

2. A terminal according to claim 1, characterised in that the edges of the tube (2) are brought into close contact without welding.

3. A terminal according to claim 1 or 2, characterised in that the joint of the edges of the tube (2) is rectilinear.

4. A terminal according to claim 1 or 2, characterised in that the joint of the edges of the tube (2) is of notched shape.

5. A terminal according to any one of the previous claims, characterised in that the tube (2) is metallized on its inner and outer surfaces.

6. A terminal according to any one of the preceding claims, characterised in that the skirt (3) is coaxially aligned with the tube (2) and is funnel-shaped made by moulding on the tube with a plastic material, and in that the tube (2) has, at its end connected to the skirt, a flared part (2a) for fixing the skirt.

7. A terminal according to claim 6, characterised in that the tube (2) has means (18) for anchoring the moulded plastics.

8. A terminal according to any one of the preceding claims, characterised in that the tube (2) is of circular cross-section.

9. A terminal according to any one of claims 1 to 7, characterised in that the tube (2) is of polygonal cross-section.

10. A terminal according to claim 9, characterised in that the tube (2) is longitudinally notched.

11. A method of producing a terminal as claimed in any one of the preceding claims, characterised in that it comprises the following operations starting with a flat metal strip (7): the strip is brought into a tubular shape in which two of its opposite parallel edges meet together so as to form a tube having contiguous edges (7a, 7b); and a tubular skirt (3) of insulating material is fixed on one of the tube ends.

12. A method according to claim 11, characterised in that the skirt is fixed coaxially to the tube and in that the skirt fixing comprises moulding on the tube (2) by means of a plastic.

13. A method according to claim 11 or 12, characterised in that it comprises metallizing the surfaces of the strip (7) before the same is brought into the tubular shape.

14. A method according to any one of claims 11 to 13, characterised in that it comprises flaring the tube after it has been formed, the flaring being made at the end where the skirt is fixed.

15. A method according to any one of claims 11 to 14, characterised in that before the strip is brought into the tubular shape it comprises a notching operation on said strip (7) on one of its sides so that the strip when brought into the tubular shape forms the said tube terminating at one end in a set of teeth (18) on which the skirt (3) is fixed.

16. A method according to any one of claims 11 to 14, in order to produce a plurality of terminals (1), characterised in that it comprises cutting the flat metal strip (7) to given lengths, each terminal then being made from a length of metal strip.

17. A method according to claims 15 and 16, characterised in that the flat metal strip cutting operation is carried out after the said strip has been notched.

18. A method according to any one of claims 11 to 14, for the production of a plurality of terminals (1), characterised in that it comprises, after the strip has been brought into the tubular shape, cutting the tube (2) to given lengths, each tube length then being completed by the skirt to form a terminal.

19. A terminal for an electrical conductor, in accordance with Claim 1 and substantially as hereinbefore described with reference to, and as shown in, Figures 1 to 3, 4 or 7 of the accompanying drawings.

20. A method of producing a terminal, in accordance with Claim 11 and substantially as hereinbefore described with reference to Figures 5 and 6 of the accompanying drawings.

21. Any novel feature or combination of features described herein.