EP0348269A1 - Cable terminal and method for its manufacture - Google Patents

Abstract

The invention relates to a cable terminal of the kind comprising a metal part (11) and an insulating part (15). …<??>According to the invention, the internal end (25) of the metal part (11), initially straight, is overall formed into a tulip shape, the exterior edge (26) of its face (27) forms an anchoring edge through which it engages with the insulating part (15), and it extends opposite a transverse shoulder (21) of this insulating part (15), the interior diameter (D1) of which is less than that (D2) of the circumference along which extends the interior edge (28) of its said face (27). …<??>Application to the cabling of electrical conductors, and in particular those with stranded core. …<IMAGE>…

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.

This is also the case for that which is the subject of the French patent application which, filed on July 9, 1973 under No 73 29221, was published under No 2,277,419.

For its assembly to the insulating part, the metal part has, at its internal end, a development, in a truncated cone, which comes to marry, and on the other, 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.

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 one.

To ensure the assembly between the insulating part and the metal part of a cable end piece, 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 made, the internal end of the part metallic is the object, by swaging, in this one, of a deformation, for its adequacy of shape with the corresponding portion of this insulating part.

However, the corresponding deformation is limited to leading to a plating, against the wall concerned of the insulating part, of the internal end, thus worked, of the metal part.

Most often, and this is the case in French patent application No 85 04572, this, in order to facilitate its deformation, is also fragmented into tongues.

The risks of corking, 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.

This is all the more so as, as experience shows, there occurs, by elasticity, at the end of such crimping, a certain "rebound" of the previously crimped portion of the metal part relative to the insulating part, in particular in the case where, as indicated above, this metal part is, to do this, divided into tongues, the insulating part, more solid, having in fact a relative rigidity compared to such tongues.

This "rebound" of the crimped portion of the metal part leads in practice to the latter to inadvertently protrude into the internal volume of the insulating part, at the risk of plugging to be avoided.

In addition, the crimping force to be applied is relatively large, of the order for example of 35 kg for a cable end whose metallic part has a section of 1.5 mm2, and, in practice, it is necessary to butt outwardly. the insulating part to collect it, which complicates operations, to the detriment of the cost of the assembly, and which further accentuates the relative rigidity of the insulating part with respect to the metal part, for the benefit of the "rebound" to be avoided .

The present invention generally relates to a provision suitable for ensuring in a simple and effective manner, and without resulting in any risk of corking, the assembly, one to the other, insulating and metallic parts of a cable end piece, or, at least, to participate in such an assembly.

More specifically, it relates to a wiring end piece of the kind comprising a metallic part, generally tubular, 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 collar, is engaged, by a front section, with the metal part, and 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, the internal end of the metal part, initially straight, is generally deformed in the shape of a tulip, the outer edge of its edge forms an anchoring edge by which it is engaged with the insulating part, and it extends opposite a transverse shoulder of this insulating part whose internal diameter is less than that of the circumference nce along which extends the inner edge of its said edge.

In practice, this anchoring edge penetrates like a wedge into the insulating part.

Thus, according to the invention, a simple anchoring of the metal part is carried out in the insulating part.

This anchoring is distinguished from an overmolding, on the one hand because, the insulating part being carried out beforehand, it is practiced after the engagement of the metallic part in this insulating part, and on the other hand because, at its term , the material of this insulating part extends only on one side of this metal part, and not on either side of it.

It is also distinguished from a crimping, because it is not limited to leading to a simple plating of the metal part against the insulating part, but to a real penetration of this metal part into this insulating part.

Like crimping, the anchoring used according to the invention can advantageously be carried out by swaging, using a simple conical punch.

However, the effort to be developed is significantly reduced compared to that required for crimping.

The conditions being equal moreover, this effort proves to be reduced by at least two thirds, passing for example from 35 kg to 10 kg for a cable end fitting whose metal part has a section of 1.5 mm2.

As a result, in particular, it is advantageously not necessary to buttress the insulating part externally during such an anchoring.

But, and above all, it also follows that the "rebound" of the metal part after anchoring is zero or almost zero.

In practice, this "rebound", if it occurs, is accompanied by the insulating part.

Indeed, this one not being buttressed externally during the anchoring, it too returns, by elasticity, to its initial configuration, and its own elasticity being in practice intrinsically superior to that of the metallic part, it then same tendency to exceed the latter.

It is then both the insulating part which encloses the metal part around its anchoring edge as this metal part which penetrates through the latter into this insulating part.

The risk of seeing the metal part protrude into the interior volume of the insulating part, and therefore the risk of a possible subsequent plugging, is advantageously minimized, if not canceled.

Certainly, it has already been proposed, in the French patent application which, filed on September 5, 1974 under No. 74 30217, was published under No. 2,243,534, to carry out a deformation, in the form of a tulip, of the internal end of the metal part of the terminal concerned.

But, initially, this internal end must be pointed by a double chamfer, both external and internal, which cannot fail to increase the cost of the whole.

In addition, the internal end, thus blunted, of the metal part attacks a straight portion, devoid of any shoulder, of the internal surface of the insulating part.

A substantial part of the edge of this internal end thus projecting from the internal surface of the insulating part, there may remain a risk of jamming when the end, previously stripped, of the conductive core d 'an electrical conductor, even if this projecting portion of this section extends obliquely.

It is not the same in the wiring end piece according to the invention, in which, on the contrary, the deformed internal end of the metal part extends opposite an internal transverse shoulder of the insulating part, the internal diameter is less than that of the circumference along which its own internal edge extends.

Thus, at the junction of the metal part with the insulating part, and taking account of a return of the latter to its initial configuration after anchoring of the metal part, this metal part is set back relative to this insulating part.

Any risk of subsequent corking is therefore eliminated.

Besides that the anchoring according to the invention thus advantageously requires no undercut shape on the insulating part, while being satisfied on the contrary with a particularly simple shape for the latter, the punch put implemented for its execution also has the advantage of ensuring a certain deburring of the insulating part during its introduction into it and of aligning perfectly with it the metal part, which makes it even easier the subsequent introduction of an electrical conductor overall.

For the assembly of the metal part of a cable end to its insulating part, the anchoring according to the invention can, if desired, be sufficient in itself.

But it can also advantageously be associated with bonding, when, as has already been proposed elsewhere, a film of adhesive intervenes between this metal part and this insulating part.

It then has the main effect of reinforcing in notable proportions, greater in practice than 20%, the tensile strength of the assembly, and advantageously ensuring in any event the permanence of a certain tensile strength even in the case of a possible subsequent deterioration of the adhesive as it can for example occur by aging.

Things being equal, the anchoring according to the invention can also advantageously allow, if desired, a reduction in the thickness of the adhesive film used.

In all cases, it can be carried out before or after bonding, but, then, before the polymerization of the corresponding adhesive.

In the case where it is carried out before bonding, it advantageously makes it possible to confine the film of adhesive used, by ensuring a seal at the internal end of the metal part, and therefore opposing any penetration of the glue in the insulating part beyond it.

Any internal burr of glue which may subsequently cause corking is thus advantageously avoided.

• la figure 1 est une vue en perspective d'un embout de câblage suivant l'invention et de l'extrémité du conducteur électrique 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 reprend, à échelle encore supérieure, le détail de la figure 2 repéré par un encart III sur cette figure 2 ;
• les figures 4A, 4B sont des vues partielles en coupe axiale, qui, reprenant pour partie celle de la figure 2, illustrent, chacune respectivement, deux phases successives de la réalisation de l'embout de câblage suivant l'invention.

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 electrical conductor which 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 shows, on a still larger scale, the detail of Figure 2 identified by an insert III in this Figure 2;
• FIGS. 4A, 4B are partial views in axial section, which, partly taking up that of FIG. 2, each illustrate two successive phases of the production of the cable end piece according to the invention.

As illustrated in these figures, the wiring end piece 10 according to the invention comprises, on the one hand, a metallic part 11, generally tubular, which is intended to be engaged on the end 12, previously 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 collar, is engaged, by a front section 16, with the metal part 11 above, and 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.

In the embodiment shown, the metal part 11 forms a barrel which is circularly closed on itself, without any discontinuity, and it is generally cylindrical.

But it goes without saying that this metal part could as well result from the rolling of an initially flat blank, and therefore present, longitudinally, a slot, straight or oblique, rectilinear or corrugated, and open or closed, for example by welding, and / or that it can be more or less frustoconical, while then converging in the direction opposite to the insulating part 15.

As a corollary, the front section 16 of the insulating part 15 is, itself, generally cylindrical in the embodiment shown, by forming, internally, a housing 20, which, bounded by a transverse shoulder 21, is clean, according to modalities which, not falling within the scope of the present invention, will not be described in detail here, at a fitting, with clearance, but with centering, of the metal part 11, and being connected, externally, to the associated rear section 17, by fins 23, which, regularly distributed circularly, extend generally radially, and which, level with the external contour of this rear section 17 at its connection to the latter, are tapered towards the outlet of the front section 16.

According to the invention, the internal end 25 of the metal part 11, initially straight, is generally deformed in the shape of a tulip, going in blooming radially in the direction opposite to the axis of the assembly, the external edge 26 of its edge 27 forms an anchoring edge by which it is engaged with the insulating part 15.

By internal end 25 of the metal part 11 is meant here the portion of this metal part immediately adjacent to its edge 27, and the outer edge 26 of this edge 27 forms the periphery of larger diameter.

In practice, the anchoring edge formed by this outer edge 26 penetrates in the manner of a wedge into the insulating part 15, and, more precisely, into the corresponding internal wall of the front section 16 of this insulating part 15.

Preferably, and as shown, the amplitude d of the radial offset of this outer edge 26, measured by relative to the external surface of the current portion 29 of the metal part 11, is of the same order of magnitude as the thickness e of its wall.

In practice, this amplitude d of the radial offset of the outer edge 26 forming the anchoring edge is at most equal to the thickness e of the wall of the metal part 11.

It is therefore relatively low.

In practice, too, only the outer edge 26 of the edge 27 of the metal part 11 is thus engaged in the form of a wedge in the insulating part 15, to the exclusion of the inner edge 28 of this edge 27.

On the contrary, and according to the invention, when the deformed internal end 25 of the metal part 11 extends, as in the present case, opposite an internal transverse shoulder 21 of the insulating part 15, the internal diameter D1 of this transverse shoulder 21 is less than that D2 of the circumference along which extends the internal edge 28 of the edge 27 of this deformed internal end 25.

Finally, in the embodiment shown, and according to the provisions proposed elsewhere, there is involved, in the housing 20, between the metal part 11 and the insulating part 15, an adhesive film 30.

According to the invention, this adhesive film 30 is confined by the deformed internal end 25 of the metal part 11.

It therefore extends only on the side thereof opposite the transverse shoulder 21 of the insulating part 15.

Initially, and as already emphasized above, the metal part 11, whose wall thickness e is in practice uniform over its entire length, is generally straight, FIG. 4A.

It is then engaged in the housing 20 formed by the section 16 of the insulating part 15, until it comes into abutment, by its edge 27, against the internal transverse shoulder 21 bounding this housing 20.

According to the provisions proposed elsewhere, the metal part 11 is then suitably centered in the insulating part 15, and, by its internal surface, it extends in continuity with the internal surface of the latter.

According to the invention, and as shown in FIG. 4A, it is then introduced, in the rear section 17 of the insulating part 15, on the side of the latter opposite the metal part 11, a punch 32 whose active part 33 is generally frustoconical.

The insertion of the punch 32 is continued until, making contact, through its active part 33, with the internal end 25 of the metal part 11, and until, the corresponding axial force F being made sufficient for this purpose, it causes, as shown diagrammatically in FIG. 48, the tulip deformation sought for this internal end 25, with, jointly, and as also diagrammatically shown in FIG. 48, an elastic deformation of the insulating part 15 .

To facilitate its action, the punch 32 can be turned on itself around its axis.

Anyway, it results from the deformation that it applies to the internal end 25 of the metal part 11 the anchoring of the latter in the insulating part 15.

After the punch 32 has been withdrawn, the insulating part 15 resumes its initial configuration elastically, while the deformed internal end 25 of the metal part 11 is possibly only subject to a more moderate elastic "rebound".

The anchoring thus produced can be carried out before the adhesive film 30 is put in place.

As pointed out above, this advantageously results in confinement of the latter on the side of the deformed internal end 25 of the metal part 11 opposite the transverse shoulder 21 of the insulating part 15.

However, as a variant, the anchoring according to the invention can be carried out after the glue film 30 has been put in place, being then performed before the polymerization of the corresponding glue.

Of course, the present invention is not limited in any case to the embodiment described and shown, but encompasses any variant.

Claims (8)

1. A cable end of the kind comprising a metallic part (11), generally tubular, which is intended to be engaged on the end (12), previously stripped, of the conductive core (13) of an electrical conductor (14 ), for the wiring thereof, and an insulating part (15), which, forming a collar, is engaged, by a front section (16), with the metal part (11), and 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), characterized in that the internal end ( 25) of the initially straight metal part (11) is generally deformed in the shape of a tulip, the outer edge (26) of its edge (27) forms an anchoring edge by which it engages the insulating part (15), and it extends opposite a transverse shoulder (21) of this insulating part (15) whose internal diameter (D1) is less than that (D2) of the circumference along which extends the internal edge (28) of its said edge (27). 2. cable end piece according to claim 1, characterized in that the outer edge (26) of the edge (27) of the deformed internal end (25) of the metal part (11) penetrates in the manner of a corner in the insulating part (15). 3. cable end according to any one of claims 1, 2, characterized in that the amplitude ( d ) of the radial offset of the outer edge (26) of the edge (27) of the deformed internal end ( 25) of the metal part (11) vis-à-vis the external surface of the current portion (29) thereof is of the same order of magnitude as the thickness ( e ) of the wall of this metal part ( 11). 4. A cable end according to claim 3, characterized in that the amplitude of the radial offset of the outer edge (26) of the edge (27) of the deformed internal end (25) of the metal part (11) is at more equal to the thickness ( e ) of the wall of this metal part (11). 5. cable end according to any one of claims 1 to 4, characterized in that only the outer edge (26) of the edge (27) of the deformed internal end (25) of the metal part (11) is engaged with the insulating part (15), excluding the internal edge (28) of this section (27). 6. cable end according to any one of claims 1 to 5, characterized in that, between the metal part (11) and the insulating part (15), there is an adhesive film (30). 7. cable end according to claim 6, characterized in that said adhesive film (30) is confined by the deformed internal end (25) of the metal part (11). 8. cable end according to any one of claims 1 to 7, characterized in that the thickness ( e ) of the wall of the metal part (11) is uniform over the entire length thereof.

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