EP0335772B1 - Cable end piece - Google Patents

Description

The present invention relates generally to the wiring accessories to be attached to the previously stripped end of the conductive core of an electrical conductor in order to make it easier and safer to connect to any terminal, in particular when this conductive core is formed of a plurality of strands suitably stranded.

It is more specifically aimed at those of these wiring accessories which, commonly known as cable ends, comprise, on the one hand, a metallic part, generally tubular, which is that intended to be engaged on the stripped end of the conductive core of the electrical conductor to be fitted, for the wiring thereof, and, on the other hand, an insulating part, which, forming a collar, is engaged, by a front section, with the metal part, and which is intended for its part, to cover, by a rear section, wider than the front section, the corresponding end of the insulating sheath of this electrical conductor.

One of the problems to be solved, in the production of wiring end pieces of this type, relates to the assembly to be provided between the metal part and the insulating part for a suitable relative joining of the latter.

Most often, to date, it is done by overmolding.

This is the case, for example, for the cable end fitting which is the subject of the French patent which, filed on October 20, 1965 under No 35.521, was published under No 1.468.859.

For its anchoring in the insulating part, the metal part has, at its internal end, a development, in a truncated cone, which comes to marry, on both sides, the synthetic material constituting this insulating part.

Although this arrangement has given and may still give satisfaction, it has drawbacks, which are as follows.

First of all, and above all, the removal of the metal part in the mold necessary for the overmolding of the insulating part proves difficult, to the detriment of productivity, and, therefore, of costs.

This difficulty is increased if, for obtaining a plurality of cable ends arranged in a chain one after the other, and as described for example in the French patent filed on October 15, 1980 under No. 80 22422 and published under No. 2,468,224, a plurality of metal parts arranged side by side in a single mold are simultaneously molded.

This is why, in practice, it is most often carried out as a unit.

In addition, if, in a cable end fitting with insulating part thus overmolded on the metal part, the overmolding joint between insulating part and metallic part is not suitably checked, and this check is not necessarily easy, this joint of overmolding can constitute an obstacle for one or the other of the strands of the conductive core to be engaged in the metallic part, and thus lead this or these strands to plug, which, on the one hand, constitutes a discomfort to the with regard to the installation of the cable end fitting during installation, which may lead to the scrapping thereof, and which, on the other hand, in the event that this installation is nevertheless finally carried out, and independently of the impact of such a plugging on the electrical quality of the connection then ensured, may subsequently give rise to incidents, if, for example, the plugged strand (s) protrude outside the cable end piece, or, broken, escape this here.

Finally, in any event, the mechanical characteristics of the cable end obtained do not only depend on the unique characteristics of the parts, metallic and insulating, which constitute it, but also on the quality, less easy to control, of the overmolding occurring between they.

To ensure the assembly between the insulating part and the metal part of a cable end, it has also already been proposed to proceed by crimping.

This is the case, for example, in the French patent application which, filed on March 27, 1985 under No 85 04572, was published under No 2,579,836, and specifically concerns a cable end, and it is the case, also, in the American patent No. 2,964,171, which itself relates more precisely to a terminal.

After its engagement in the insulating part previously carried out, the internal end of the metallic part is the object, by swelling, in this one, of a development, for its adequacy of shape with the corresponding portion of this insulating part.

However, the risks of plugging and the drawbacks of mechanical characteristics depending on the method of assembly selected, succinctly explained above for an assembly by overmolding, are found in a similar manner, and even in a substantially increased manner, with such an assembly by crimping. Document US-A-2 715 764 discloses a wiring accessory, in this case a terminal, in which the metal part is strictly fitted in the insulating part.

According to the invention, and having regard to the quality of the adhesives now available and to the possibility of micro-dosages for these, it is proposed to proceed by bonding to the desired assembly, with arrangements suitable for allowing such bonding. .

The present invention according to claim 1 thus relates to a wiring end of the kind comprising a generally tubular metal part over its entire length which is intended to be engaged on the end, previously stripped, of the conductive core of an electrical conductor, for the wiring thereof, and an insulating part which, forming a flange, is engaged, by a front section, with the metal part, and which is intended to cover, by a rear section, wider than the front section, the corresponding end of the insulating sheath of such an electrical conductor, this cable end being generally characterized in that, jointly, the metal part has its internal end, at least, which is entirely right, it is in support, by the edge of this internal end, against an internal transverse shoulder of said insulating part, there is, at least locally, between this metal part and this insulating part, for their relative fastening, a film of glue, and, at least at least said internal transverse shoulder of the insulating part, the internal surface thereof has a diameter at most equal to that of the internal surface of the metal part, and internally the front section of the insulating part has, at its outlet, a portion enlarged.

Any risk of plugging is eliminated, and the overall mechanical characteristics obtained depend on the sole characteristics of the metallic and insulating parts used, without being dependent on their method of assembly.

In addition, an embodiment in a chain is advantageously possible, either by section or in continuous strip, the metal parts being deposited individually in insulating parts previously produced in a chain.

The result is, overall, higher production rates, and lower implementation and maintenance costs.

In addition to the enlarged portion facilitating the operation of introducing the metal part during assembly of the assembly, it constitutes, for the adhesive used for this assembly, an expansion vessel capable of absorbing variations in volume due to the inevitable manufacturing tolerances on the insulating part and on the metal part, thus avoiding, or minimizing, possible burrs for this adhesive.

Preferably, also, the surface of the front section of the insulating part of the wiring end piece according to the invention has, projecting, in the vicinity of the internal transverse shoulder thereof, at least one centering facet, and , in practice, a plurality of such centering facets suitably distributed circularly, which, oblique to the axis of the assembly, extend in the direction of this internal transverse shoulder.

This results, advantageously, for sure, a suitable centering of the metal part in the insulating part, and therefore, on the one hand, the guarantee that, thus properly centered, this metal part cannot be at the origin of '' any plugging during the engagement of the assembly on the electrical conductor to be fitted, and, on the other hand, the certainty that, for the adhesive joint used, good thickness uniformity can be obtained while around the metal part, for the benefit of the quality of its assembly with the insulating part.

If desired, the assembly thus provided by gluing can be combined one or more expansion of the metal part on the insulating part.

However, according to the invention, this or these swaging operations take place at a distance from the internal transverse shoulder of the insulating part.

The internal end of the metal part, that which abuts against the internal transverse shoulder of the insulating part, thus remains straight, without being affected by any crimping deformation, and the advantages of eliminating any risk of plugging. are not compromised.

Preferably, finally, the front section of the insulating part of the cable end according to the invention is generally cylindrical, in the manner of its rear section, and it therefore has a relatively reduced thickness.

Thanks to the thickness limitation which is thus its own, this front section can advantageously best accompany the deformations of which the metal part is subjected during its crimping on the stripped end of the conductive core of the electrical conductor to be fitted. , which, in limiting the corresponding constraints, minimizes the risk of peeling for the film of adhesive intervening between this insulating part and this metallic part.

It further results from this thickness limitation an advantageous saving of material.

To avoid, however, that, when the assembly is engaged in any connection terminal, the front section, thus thinned, of the insulating part of the cable end according to the invention does not inadvertently come into it too in this connection terminal, at the risk of disturbing the electrical connection then to be ensured, provision is made, according to a development of the invention, to provide, externally, projecting, this front section, with at least one fin, which, forming a guard, is capable of limiting, if not preventing, penetration into such a connection terminal.

Thus an advantageous compromise is found between the deformation capacity sought for this front section and the need to oppose its engagement in a connection terminal.

• la figure 1 est une vue en perspective d'un embout de câblage suivant l'invention et de l'extrémité du conducteur qu'il est destiné à équiper ;
• la figure 2 est, à échelle supérieure, une vue en coupe axiale de cet embout de câblage, suivant la ligne II-II de la figure 1 ;
• la figure 3 est, à l'échelle de la figure 2, une vue en coupe axiale de la seule partie isolante de cet embout de câblage ;
• la figure 4 reprend, à échelle supérieure, le détail de la figure 3 repéré par un encart IV sur cette figure 3 ;
• la figure 5 est une vue en élévation, de bout, de cette partie isolante, suivant la flèche V de la figure 3 ;
• la figure 6 en est une vue en coupe transversale, suivant la ligne VI-VI de la figure 3 ;
• la figure 7 est une vue partielle en coupe axiale qui, analogue à celle de la figure 4, se rapporte à une variante de réalisation.

The characteristics and advantages of the invention will become apparent from the description which follows, by way of example, with reference to the appended schematic drawings in which:

• Figure 1 is a perspective view of a wiring end according to the invention and the end of the conductor it is intended to equip;
• Figure 2 is, on a larger scale, an axial sectional view of this cable end, along the line II-II of Figure 1;
• Figure 3 is, on the scale of Figure 2, an axial sectional view of the single insulating part of this cable end;
• Figure 4 shows, on a larger scale, the detail of Figure 3 identified by an insert IV in this Figure 3;
• Figure 5 is an elevational end view of this insulating part, according to arrow V in Figure 3;
• Figure 6 is a cross-sectional view along the line VI-VI of Figure 3;
• Figure 7 is a partial view in axial section which, similar to that of Figure 4, relates to an alternative embodiment.

As illustrated in these figures, the wiring end piece 10 according to the invention comprises, on the one hand, a metal part 11 which, generally tubular over its entire length, is intended to be engaged on the end 12 beforehand stripped of the conductive core 13 of an electrical conductor 14, for the wiring thereof, and, on the other hand, an insulating part 15, which, forming a flange, is engaged, by a front section 16, with the preceding metal part 11, which is intended to cover, by a rear section 17, wider than the front section 16, the corresponding end 18 of the insulating sheath 19 of such an electrical conductor 14.

According to the invention, and jointly, the metal part 11 has its internal end 20, at least, which is entirely straight, it is in abutment, by the edge 21 of this internal end 20, against an internal transverse shoulder 22 of the part insulating 15, there is, at least locally, between this metal part 11 and this insulating part 15, for their relative fastening, an adhesive film 24, and, at least in line with said internal transverse shoulder 22 of the insulating part 15, the internal surface 25 of the latter has a diameter D1 at most equal to that D2 of the internal surface 26 of the metal part 11, and internally the front section 16 has, at its outlet, an enlarged portion 29.

By internal end 20 of the metal part 11 is meant here the portion of this metal part, which, fitted into the insulating part 15, is immediately adjacent to its corresponding edge 21.

According to one aspect of the invention, and as indicated above, this internal end 20, at least, is entirely straight.

This means that it is devoid of any frustoconical deformation of the type used when the assembly with the insulating part 15 must be make by overmolding or by crimping.

In other words, and according to this aspect of the invention, the internal end 20 of the metal part 11 is, continuously, in alignment with its current part.

In the embodiment shown in Figures 1 to 6, it is over its entire length that the metal part 11 is thus entirely straight.

In other words, it is completely devoid of any deformation.

This does not necessarily imply that it is cylindrical.

On the contrary, if, in the embodiment shown by way of example, this metal part 11 is thus generally cylindrical, it could just as easily be more or less frustoconical, while then converging in the direction opposite to the insulating part 15.

Similarly, if, in this embodiment, this metal part 11 forms a barrel which is circularly closed on itself, without any discontinuity, in the manner of a tube obtained by stamping or drawing, this metal part 11 could just as easily well result from rolling an initially flat blank, and therefore have, longitudinally, a slot, straight or oblique, straight or wavy, and open or closed, for example by welding.

In the embodiment shown, and according to another aspect of the invention, the front section 16 of the insulating part 15 is generally cylindrical, and it is connected to the rear section 17, itself generally cylindrical, by a median section 27 generally frustoconical.

In practice, the internal surface of this front section 16 of the insulating part 15 has, successively, from its internal transverse shoulder 22, two portions, namely, a first portion 30, of diameter means D3 slightly greater than the mean outside diameter D4 of the internal end of the metal part 11, and a second, enlarged portion, the portion 29 mentioned previously, of mean diameter D5 greater than that D3 of the first.

In the embodiment shown, the internal surface of the enlarged portion 29 of the front section 16 of the insulating part 15 comprises a median section 31, generally cylindrical, framed by two generally frustoconical sections, one, 32, for its connection to the first portion 30, itself generally cylindrical, the other, 33, to form an engagement chamfer at the outlet of the assembly.

Axially, the length L1 of this internally enlarged portion 29 of the front section 16 of the insulating part 15 is only a fraction, for example less than a third, of the total length L2 of this front section 16 from the shoulder internal transverse 22.

Preferably, this total length L2 of the front section 16 of the insulating part 15, that along which the metal part 11 is fitted into this insulating part 15, is at least equal to the mean outside diameter D4 of this metal part 11.

Furthermore, although generally cylindrical, as indicated above, the internal surface of this front section 16 of the insulating part 15 advantageously has, in particular for reasons of ease of molding, a certain draft, of the order for example a few degrees.

It is to take account of this draft, and of a possible taper of the metal part 11, that mention was made above of "average" diameters.

Preferably also, and as shown, the internal surface of the front section 16 of the insulating part 15 has, projecting, in the vicinity of the internal transverse shoulder 22 from which it extends, at least one centering facet 35, which, oblique on the axis of the assembly extends in the direction of this internal transverse shoulder 22.

In practice, this centering facet 35 thus extends to the internal transverse shoulder 22, thus biting thereon, it is a planar facet, and there are thus, suitably distributed circularly around from the axis of the assembly, several centering facets 35.

In the embodiment shown, these centering facets 35 are three in number, being arranged at 120 ° two by two.

In the vicinity of the internal transverse shoulder 22, upstream of the latter relative to its front section 16, the internal surface 25 of the insulating part 15 preferably extends, and as shown, substantially tangentially to a surface cylindrical perpendicular to said internal transverse shoulder 22.

Advantageously, there can thus be, on either side of the internal transverse shoulder 22, a surface continuity between the internal surface of the insulating part 15 and that of the metal part 11, if the corresponding diameters D1, D2 are equal.

However, in any event, the diameter D1 being at most equal to the diameter D2, there can be, at this level, no obstacle to the engagement of the electrical conductor 14 if the metal part 11 is suitably centered in the insulating part 15 .

It is, moreover, very precisely, the role of the centering facets 35 of ensuring proper centering of this metallic part 11.

Preferably, and as shown, the front 16 and rear 17 sections of the insulating part 15 have substantially the same thickness E.

It is substantially the same, moreover, for the middle section 27, apart from a thickening thereof upstream of the internal transverse shoulder 22.

As a corollary, the front section 16 carries, externally, projecting, at least one fin 37, forming a guard.

In the embodiment shown, this fin 37 extends generally parallel to the axis of the assembly, it extends from the outlet, or nose, of the front section 16 to the rear section 17, covering in passing the median section 27, and, at first fleeing obliquely in the direction of the rear section 17, its elevation profile is then level with the external contour of this rear section 17; alternatively, and as shown diagrammatically in broken lines in FIG. 2, this profile may be rectilinear.

In practice, there are thus several fins 37, suitably distributed circularly.

In the embodiment shown, these fins are eight in number, and they are regularly distributed circularly.

The metal part 11, produced according to the usual techniques in the matter, as succinctly mentioned above, is preferably made of copper.

Preferably, it is applied to it any treatment capable of imparting a certain frosting to its external surface, or at least to the portion thereof affected by the adhesive film 24, with a view to better adhesion of this film of adhesive. glue 24.

For example, it is subjected for this purpose to a matt electrolytic tinning, without subsequent reflow.

But any other chemical or mechanical means suitable for obtaining a comparable frosted finish can also be envisaged.

As a corollary, the insulating part 15 is produced by molding a suitable synthetic material such as for example polyamide.

This molding can be done in isolation, or, preferably, in strings.

In FIGS. 2, 3 and 5, 6 have been shown diagrammatically in broken lines, the tongues 38 connecting two by two two insulating parts 15 in such a chain.

• dépose d'un chapelet de parties isolantes 15 à un poste d'assemblage,
• après dégraissage, dépose d'une partie métallique 11 dans chacune de ces parties isolantes 15, avec, soit un enfoncement complet d'une telle partie métallique 11 dans une telle partie isolante 15, jusqu'à butée de la tranche 21 de l'extrémité interne 20 de cette partie métallique 11 dans l'épaulement transversal interne 22 de cette partie isolante 15, soit, seulement, un enfoncement partiel de cette partie métallique 11,
• dépose, en au moins un point de l'intervalle annulaire entre la partie métallique 11 et la partie isolante 15, d'une dose convenable de colle appropriée, et par exemple d'une colle du type cyanoacrylate, étant entendu que si la partie métallique 11 a été préalablement complètement enfoncée dans la partie isolante 15, une lègère pression est alors exercée sur elle pour éviter toute bavure de colle à l'intérieur de cette partie isolante 15, et que si son enfoncement préalable n'a été que partiel, elle est alors complètement enfoncée dans cette dernière, jusqu'à butée de la tranche 21 de l'extrémité interne 20 contre l'épaulement transversal interne 22 de celle-ci.
• et, éventuellement, vaporisation d'un activateur pour accélérer la polymérisation en surface de la colle mise en oeuvre et éviter ainsi le phénomène de "blooming" susceptible d'entraîner l'apparition de taches blanches à la surface des pièces concernées.

However, for the assembly, by gluing, according to the invention, of a metal part 11 with a part insulator 15, it can therefore be carried out as follows:

• depositing a chain of insulating parts 15 at an assembly station,
• after degreasing, deposit of a metal part 11 in each of these insulating parts 15, with either a full insertion of such a metal part 11 in such an insulating part 15, until the edge 21 of the end stop internal 20 of this metal part 11 in the internal transverse shoulder 22 of this insulating part 15, or, only, a partial depression of this metal part 11,
• deposit, at at least one point in the annular gap between the metal part 11 and the insulating part 15, of a suitable dose of suitable glue, and for example a glue of the cyanoacrylate type, it being understood that if the metal part 11 has been previously completely inserted into the insulating part 15, a slight pressure is then exerted on it to avoid any glue burr inside this insulating part 15, and that if its prior insertion was only partial, it is then fully inserted into the latter, until the edge 21 of the internal end 20 abuts against the internal transverse shoulder 22 thereof.
• and, optionally, vaporization of an activator to accelerate the surface polymerization of the adhesive used and thus avoid the "blooming" phenomenon capable of causing the appearance of white spots on the surface of the parts concerned.

As a variant of the previous process, the dose of adhesive can be deposited on the metal part 11, before it is inserted into the insulating part 15.

Anyway, the cable end 10 thus produced according to the invention can then be manipulated, while the deep polymerization of the adhesive ensuring its assembly continues to take place naturally, to be completed after a few hours .

Of course, and in the usual way, it is then preferably carry out a systematic check of this cable end 10.

As it is easy to understand, it is by simple capillarity that the dose of adhesive used is best distributed between the metal part 11 and the insulating part 15, thereby forming a homogeneous manner between them. glue film 24 sought.

For this dose of adhesive, the enlarged portion 29 of the front section 16 of the insulating part 15 advantageously forms, around the metal part 11, an expansion vessel capable of absorbing any variations in volume between the various constituents in question.

In the alternative embodiment illustrated in FIG. 7, the internal surface of the front section 16 of the insulating part 15 has, annularly, recessed, at a distance from the internal transverse shoulder 22, at least one groove 40, and, by a padding bead, not shown, the corresponding metal part 11 is engaged with this groove 40.

Notwithstanding this bulging bead, this metal part 11 still remains entirely straight.

In the embodiment shown, there is thus only one groove 40, and, the latter has in cross section, a semi-circular profile.

But, of course, several grooves 40, duly staggered, can be provided, and / or a section other than semi-circular is adopted for one or the other of them.

According to another variant, not shown, the insulating part 15 does indeed have, thus, internally, one or more grooves 40, but no expansion of the metal part 11 takes place, which thus remains still entirely straight over the whole of its length.

A bead of glue is simply formed in favor of such a groove 40, and this glue therefore performs an additional mechanical function.

The present invention is moreover not limited to the embodiments described and shown, but encompasses any variant within the limits of the claims.

Claims (23)

1. An electric terminal connector of the type comprising a metal part (11) which, generally tubular over its entire length, is intended to fit onto the previously bared end of the conductive core of an electric conductor for the wiring of this latter, and an insulating part (15) which, forming a collar, has a front portion (16) engaging the metal part (11) and which is intended to have a rear portion (17) which is wider than the front portion (16) fit over the corresponding end of the insulating sheath of such an electric conductor, characterised in that jointly the metal part (11) has its inner end (20) at least, which is entirely straight, bearing via the portion (21) of this inner end (20), against the inner transverse shoulder (22) of the said insulating part (15) and in that there is at least locally between this metal part (11) and this insulating part (15), for their relative fitment to one another, a film of adhesive (24) at right-angles at least to the said inner transverse shoulder (22) of the insulating part (15), the inner surface (25) of this latter having a diameter (D1) which is at most equal to that (D2) of the inner surface (26) of the metal part (11) and on the inside the front portion (16) of the insulating part (15) has at its outlet a widened portion (29).
2. A terminal connector according to claim 1, characterised in that the inner surface of the front portion (16) of the insulating part (15) has in succession, from its inner transverse shoulder (22), two portions, a first portion (30) of an average diameter (D3) which is slightly greater than the average outside diameter (D4) of the inner end (20) of the metal part (11) and a second widened portion (29) having an average diameter (D5) which is greater than that (D4) of the former.
3. A terminal connector according to claim 2, characterised in that the inner surface of the widened portion (29) of the front part (16) of the insulating part (15) comprises a middle portion (31) which is generally cylindrical and which is framed by two generally frustoconical portions, one (32) for its connection to the first portion (30), the other (33) to form a chamfer for engagement on the outlet of the assembly.
4. A terminal connector according to any one of claims 2 to 3, characterised in that axially the length (L1) of the widened inner portion (29) of the front portion (16) of the insulating part (15) is only a fraction, for example less than one-third, of the total length (L2) of this front portion (16), with effect from its inner transverse shoulder (22).
5. A terminal connector according to any one of claims 1 to 4, characterised in that all in all the inner surface of the front portion (16) of the insulating part (15) has a clearance taper.
6. A terminal connector according to any one of claims 1 to 5, characterised in that in the vicinity of its inner transverse shoulder (22) the inner surface of the front portion (16) of the insulating part (15) has projecting at least one centring facet (35) which, oblique to the axis of the whole, extends in the direction of the said inner transverse shoulder (22).
7. A terminal connector according to claim 6, charac-terised in that the centring facet (35) extends as far as the inner transverse shoulder (22) and therefore inter-sects it.
8. A terminal connector according to claim 7, characterised in that there are a plurality of circularly suitably distributed centring facets (35).
9. A terminal connector according to any one of claims 1 to 8, characterised in that at a distance from its inner transverse shoulder (22), the inner surface of the front portion (16) of the insulating part (15) has annularly an recessed at least one groove (40).
10. A terminal connector according to claim 9, charac-terised in that by a bead produced by expansion, the metal part (11) engages a groove (40) in the insulating part (15).
11. A terminal connector according to any one of claims 1 to 10, characterised in that the metal part (11) is entirely straight over its entire length.
12. A terminal connector according to any one of claims 1 to 11, characterised in that in the vicinity of its inner transverse shoulder (22) and upstream thereof in relation to its front portion (16), the inner surface (25) of the insulating part (15) extends substantially tangentially of a cylindrical surface perpendicular to the said inner transverse shoulder (22).
13. A terminal connector according to any one of claims 1 to 12, characterised in that the front portion (16) of the insulating part (15) is generally cylindrical and is connected at its rear portion (17), itself generally cylindrical, via a middle and generally frustoconical portion (27).
14. A terminal connector according to claim 13, characterised in that the front portion (16) and rear portion (17) of the insulating part (15) are of substantially the same thickness (E).
15. A cable connector according to any one of claims 1 to 14, characterised in that externally the front portion (16) of the insulating part (15) carries at least one projecting fin (37) which forms a guard.
16. A terminal connector according to claim 15, characterised in that the said fin (37) extends generally parallel with the axis of the assembly.
17. A terminal connector according to claim 16, characterised in that the said fin (37) extends from the opening or nose of the front portion (16) as far as the rear portion (17).
18. A terminal connector according to either of claims 16 or 17, characterised in that firstly diminishing obliquely in the direction of the rear portion (17), the elevation profile of the fin (37) is then level with the outer contour of this rear portion (17).
19. A terminal connector according to either of claims 17 or 18, characterised in that the elevation profile of the fin (37) is rectilinear.
20. A terminal connector according to any one of claims 16 to 19, characterised in that there are a plurality of circularly distributed fins (37).
21. A terminal connector according to any one of claims 1 to 20, characterised in that the length (L2) along which the metal part (11) is fitted into the insulating part (15) is at least equal to the mean outside diameter (D4) of this metal part (11).
22. A terminal connector according to any one of claims 1 to 21, characterised in that the outer surface of its metal part (11) or at least the portion thereof which is affected by the film of adhesive (24) has a certain roughness.
23. A terminal connector according to any one of claims 1 to 22, characterised in that the metal part (11) is made from tinned copper.

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