EP1383211B1 - Method for crimping a contact to strands of a cable - Google Patents

Abstract

The end of the cable (2) is inserted into the contact (1) via an opening (9) in the end of the contact shank (7) until at least part of the exposed cable wires (10) are located inside a tubular part of the shank (14). A first jaw (12) in a crimping tool (4) is clamped around the shank so that the tubular part of the latter is crimped around the wires, then whilst keeping the first jaw clamped in this position, a second jaw (13) in the tool is moved over the length of the shank in order to crimp the rest onto the wires. The contact comprises a shank with a tubular part and a truncated cone-shaped part (8) forming an extension of the tubular part. The opening for inserting the end of the cable is provided in the truncated cone-shaped part.

Description

The subject of the present invention is a method of crimping a contact on strands of a cable. In particular, it finds its use in the field of electrical connections, in particular those used in aeronautics, where the connection between a cable and a contact must be reliable whatever the external conditions to which it is subject. These electrical connections are generally subject to large variations in temperature and pressure amplitude due to boarding of airplanes capable of flying up to 10,000 meters above sea level. For example on an airplane, the temperature can vary between -50 ° C, when in the air, and + 40 ° C when placed on the ground.

These variations are more rapid and are experienced in the space of a few hours. Cables connect systems electronic them or connect them to a power supply; he is therefore essential to guarantee the security of these connections. For this purpose the invention aims to reduce the consequences of the phenomena of differential expansion induced by these temperature variations. To do this, the invention provides a method for ensuring good crimping of the contact on the cable even when these are made of materials distinct.

Furthermore, the invention proposes a solution to guarantee the crimping of a contact forming a barrel inside which the cable is placed so that the barrel covers both bare strands of the cable and a non-stripped portion of this cable. In general, the core of a cable is made from individual strands which can be made of aluminum in particular for avionics, copper or other applications. These strands are surrounded by an insulating sheath generally made of a material plastic. The constraint when the cable has strands is that these strands can roll on top of each other during a crimping operation. In addition, the retention of contact, even crimped, on these divided wires is difficult. The object of the invention is to remedy the drawbacks of mechanical strength and electrical continuity by proposing to connect the contact to both the soul namely the strands of the cable and both on the cable sheath.

In the state of the art, we know from the teaching of document FR-A-2,710,788, a crimping method for connecting a stripped end of an electrical cable in a contact allowing guarantee the tightness of the connection. To use the process, it is necessary that the contact has a barrel with a tubular portion extending by a portion with an outer periphery frustoconical, this was to receive the cable. This contact is made in a deformable and conductive material. According to a known method, performs crimping by wire drawing. One end of the contact is retained in the crimping tool, while the jaw of the crimping tool is moved along the frusto-conical periphery to fold down the sides along the cable and along the stripped end.

In general, the contact which is intended to receive in the barrel a end of a cable, comprising a portion of stripped strands and a portion of strands surrounded by a sheath, has at a second end a connection termination. The contact has a flange between this connection termination and the area presenting the keg. In the invention it is provided to retain the contact inside the crimping tool at this collar. Indeed, the collar is presented inside a means retention of the crimping tool. Then, after inserting the end of the cable to be crimped inside the barrel, the jaw is moved from the means of retention of the collar towards the opening of the barrel to crush the sections of this barrel on the cable. The displacement of this jaw exerts a radial pressure, and both axial on the strands of the cable to be crimped. With such process, there is a risk of disengaging strands of the barrel, or even breaking them inside the barrel, which causes a connection fault.

The solution proposed by the invention guarantees the connection strands inside the barrel while ensuring their integrity and tightness of the connection thus made. The tightness of a connection is fundamental to prevent corrosion phenomena. In particular, the current connection by the crimping method according to the invention allows provide connections that resist temperature variations and also corrosion by salt spray.

The object of the invention is to crimp a contact in which one inserts a stripped end of a cable inside a barrel of this contact. It is crimped at a first level, at the level of a first zone of the barrel surrounding bare strands of the cable by a radial tightening movement a jaw. And to crimp the barrel along its entire length along this end of cable, the closed position of the tools is maintained ensuring first crimping so as to guarantee the position of the cable strands by compared to the barrel. So when the barrel is crimped over its entire length by wire drawing it is guaranteed that the length of the strands crimped inside the barrel have a length in engagement corresponding well to the dimensions envisaged. Indeed, the cable strands are not pushed back or broken inside the barrel during of the wire drawing operation.

• on enfonce l'extrémité du câble à l'intérieur du fût par l'ouverture du fût jusqu'à ce qu'au moins une partie des brins dénudés soit présentée dans la portion tubulaire du fût 4, puis
• - on serre radialement une première mâchoire d'un moyen des sertissage sur le fût de manière à le sertir à un premier endroit de la portion tubulaire sur la partie de brins dénudés de l'extrémité du câble, et enfin
• on maintient cette première mâchoire en position serrée, tout en déplaçant une deuxième mâchoire du moyen de sertissage le long du fût pour sertir le fût sur toute sa longueur autour de l'extrémité du câble.

The subject of the invention is a method of crimping a contact on one end of a cable, the contact comprising a barrel with a tubular portion extending by a frustoconical portion to open out through an opening and the end of the cable comprising a part of stripped strands and part of strands surrounded by a sheath, characterized in that

• the end of the cable is pushed inside the barrel through the opening of the barrel until at least a portion of the stripped strands is presented in the tubular portion of the barrel 4, then
• - A first jaw is clamped radially with crimping means on the barrel so as to crimp it at a first place in the tubular portion on the part of bare strands at the end of the cable, and finally
• this first jaw is maintained in the clamped position, while moving a second jaw of the crimping means along the barrel to crimp the barrel over its entire length around the end of the cable.

• Figure 1 : Une vue en coupe longitudinale d'un contact retenu dans un outil de sertissage prévue pour recevoir un câble dénudé ;
• Figure 2 : Une vue en coupe longitudinale d'un contact retenu dans un outil de sertissage au cours d'une première étape d'un procédé de sertissage selon l'invention ;
• Figure 3 : Une vue en coupe longitudinale d'un contact retenu dans un outil de sertissage au cours d'une deuxième étape d'un procédé de sertissage selon l'invention ;
• Figure 4 : Une vue en coupe longitudinale d'un contact retenu dans un outil de sertissage au cours d'une troisième étape d'un procédé de sertissage selon l'invention ;
• Figure 5 : Une vue de profil d'un contact serti sur l'extrémité d'un câble selon un procédé selon l'invention.

The invention will be better understood on reading the description which follows and on examining the figures which accompany it. These are presented for information only and in no way limit the invention. The figures show:

• Figure 1: A longitudinal sectional view of a contact retained in a crimping tool intended to receive a stripped cable;
• Figure 2: A longitudinal sectional view of a contact retained in a crimping tool during a first step of a crimping process according to the invention;
• Figure 3: A longitudinal sectional view of a contact retained in a crimping tool during a second step of a crimping process according to the invention;
• Figure 4: A longitudinal sectional view of a contact retained in a crimping tool during a third step of a crimping process according to the invention;
• Figure 5: A side view of a contact crimped on the end of a cable according to a method according to the invention.

The subject of the invention is a crimping process which provides for crimping a contact 1 around one end 2 of a cable 3 by means of a crimping 4.

The contact 1 is preferably made of a deformable material. he has a first front end 5 intended to cooperate with a complementary device. Furthermore it has a second end rear 6 forming a barrel 7 for receiving the end 2 of the cable 3. In the example shown in Figure 1, the first end 5 is a male plug intended to cooperate with a female socket of the complementary device.

Contact 1 has a main elongation axis 8 along which are presented for their respective connections on the one hand the first end of contact 5 and on the other hand the barrel 7. The barrel 7 has a opening 9 perpendicular to the axis 8 and opening inside the barrel 7. The inner cavity of barrel 7 preferably has a frustoconical outer shape so that the diameter of the opening 9 is significantly greater than one cable diameter 3, while an inner diameter at the bottom of the cavity is slightly smaller in diameter than the diameter of the cable 3 surrounded of its sheath 11, while being slightly greater than the diameter of the strands stripped 10 of cable 3

Preferably, the contact 1 is made of copper alloy. Cable 3 has metal strands, in particular made of aluminum, and is surrounded by a sheath 11 preferably insulating and plastic. The invention is particularly interesting for this type of connection.

The crimping tool 4 has a first jaw 12 and a second jaw 13. These two jaws 12 and 13 can be opened from so as to allow the introduction of contact 1 along its axis 8 between parts of the two jaws 12 and 13 respectively. Preferably, jaws open and close orthogonally to axis 8. When the contact 1 is correctly placed in crimping means 4, the first jaw 12 closes around a tubular portion 14 of the barrel 7.

The tubular portion 14 has a tubular outer periphery in the continuity of the frustoconical periphery of the barrel 7, in continuity with the smaller diameter end of this frustoconical portion. This portion more particularly surrounds the bottom of the barrel cavity 7.

The second jaw 13 closes around the portion frustoconical of the barrel 7. For this purpose, the second jaw 13 has chamfered edges of shapes substantially complementary to the shape tapered barrel 7.

The jaws 12 and 13, after introduction of the contact 1 in the tool crimping 4, close in a first retention position, in which they do not exert pressure directly on the contact. The contact is retained in the crimping tool 4, but it is still free to be slightly moved between these two jaws. Contact retention 1 in the first jaw 12 makes it easy to insert the end 2 of the cable 3 inside the barrel 7.

As shown in Figure 2, when in a first step of the crimping process, the end 2 of the cable 3 is inserted inside the barrel 7, this end 2 is pushed in until at least part of the strands stripped 10 is presented at the level of the tubular portion 14. The cable 3 is sufficiently stripped so that in the position inserted in the bole 7, a second part of the stripped strands 10 are also located in the frustoconical portion of the barrel 7. The jaws 12 and 13 are at this stage respectively only half closed.

Contact 1 preferably has a flange 15 to cooperate with flanges 16 of the first jaw 12. Preferably, the first jaw 12 has face-to-face flanges 16 'and 16 "between which the collar 15 is retained. Furthermore cooperation between the edges chamfered and the frustoconical outer wall also limits the mobility of the contact 1 along the axis 8 inside the crimping tool 4.

Mainly a jaw such as 12 or 13 has one or more movable parts respectively to cooperate together. These parts being able to approach and move away from each other to define a variable dimension space between these two parts. On the other hand these two parts can be adjusted in position with respect to each other to be arranged correctly either in an open position for receive a contact either in a retention position to retain the contact, either in a crimping position to compress contact walls on cable 3. Generally these parts are symmetrical one by compared to others. They approach and move away from each other according to an axis preferably perpendicular to the axis 8 of elongation of the contact 1. As regards the second jaw 13, this is furthermore provided with a means of translation to be moved longitudinally along the axis 8.

During a first step, we first crimp the portion tubular 14 disposed between the moving parts of the first jaw 12 in a radial movement of the jaw relative to the axis 8. The parts of jaw 12 move towards each other to constrain the portion 14 around the terminal end 17 of the stripped strands 10. The parts constituting the jaw 12 are brought closer to one another according to radially directed forces. The forces are equivalent. We obtain thus bringing the parts of the first jaw 12 apart and on the other side of portion 14. This reconciliation is on the one hand limited by the presence of the flange 15 against which walls 16 '' 'respectively on each of the parts of the jaw 12 abut. Given that contact 1 is retained in crimping means 4 by cooperation with the walls 16 'and 16 ", the approximation of the parts of the jaw 12 a for simple effect, radial compression, without any axial stress.

For example, when the parts of the jaw 12 are approached, we get a slightly domed shape in the middle and slightly more tightened at both ends of the portion 14 which is retained between the parts of the jaw 12.

As shown in Figure 4, in a second step, the first jaw 12 thus remains pressed into portion 14, while the second jaw 13 is it moved axially along the axis 8 of way to come to rest against the outer edges 18 of the frustoconical portion of the barrel 7. Because of the shape of the parts of the second jaw 13, the axial displacement along the axis 8 of these two parts causes a progressive crushing of the walls 18. These are constrained by the flanges 19 arranged opposite one another, respectively on the parts 20, 21 of the second jaw 13. Preferably, a spacing of the parts 20, 21 is such that a distance between the flanges respectively 19 is slightly greater than the outside diameter of strands stripped 10 and successively from the sheath 11. A crimping is thus obtained by wire drawing, where the rear barrel 7, as shown in FIG. 5, is crimped progressively on the stripped strands 10 and then on the sheath 11. We thus obtains a crimp which still gives a slightly tapered in the barrel 7.

By this method, when the second jaw 13 is moved axially, the strands, on which it gradually crimps the portion tapered 18, are not driven in the same axial movement: they are retained at their most terminal end by the first jaw 12. This ensures the integrity of the cable strands even during the operation crimping.

Preferably, in the crimping tool 4, at the start of the first crimping step, the two jaws 12 and 13 are joined together. Once the first crimping has been carried out at the level of the cylindrical portion 14, then the second jaw 13 gradually deviates from the first jaw 12 to extend along its entire length of the barrel 7. This second jaw 13 is moved to a termination of the barrel 7, namely up to the opening 9 of the barrel 7.

Preferably, the crimping carried out by the first jaw 12 corresponds to a crimping in four or eight points. The parts of the first jaw 12 may for example be two in number and each include four pressure points each to apply against the outer periphery of the portion 14. In a variant, it is possible plan to turn to present only two pressure points on each part of the jaw 12. In this case, to get the eight crimping points, we can plan to impose a rotation of about 45 ° on the contact 1, and to translate it slightly along axis 8. In this variant then we can get a layout of these eight points of staggered crimping on the outer periphery of the cylindrical section 14. This particular position makes it possible to provide better resistance of the crimping with respect to axial tensile forces.

In a preferred embodiment, the crimping means 4 has a trigger which allows the first to be successively engaged jaw 12 around contact 1 and directly chain this insertion of the first jaw 12 in contact 1 by a displacement of the second jaw 13 along this contact 1 for crimping full.

When the crimping by the two jaws 12 and 13 is finished, then the second jaw 13 automatically returns next to the first jaw 12, and the respective parts of each of the jaws 12 and 13 open again to allow the end of the cable to exit with its contact 1 now crimped around. In this open position, the crimping tool can receive a new contact such as 1 to crimp on a new end such as 2.

Claims (6)

1. Method for crimping a contact (1) to an end (2) of a cable (3), the contact comprising a sleeve (7) with a tubular portion (14) that extends by a tapered portion to open out in an aperture (9), and the end of the cable comprising one part of bared strands (10) and one part of strands surrounded by a sheath (11), comprising the following steps :

   the end of the cable is pushed into the sleeve through the aperture of the sleeve until at least one part of the bared strands (10) is presented in the tubular portion of the sleeve, and then,

   a first jaw (12) of a crimping means (4) is radially clamped on the sleeve so as to crimp at a first place of the tubular portion on the bared strands part of the cable end, and finally

   this first jaw is kept in the clamped position, while at the same time a second jaw (13) of the crimping means is shifted along the tapered portion the sleeve along a principal axis of elongation (8) of the contact (1) to crimp the sleeve throughout its length around the end of the cable.
2. Method according to claim 1, characterized in that the second jaw is shifted from the first position up to the aperture (9) of the sleeve.
3. Method according to one of the claims 1 to 2, characterized in that a copper sleeve is crimped on aluminium strands of the cable.
4. Method according to one of the claims 1 to 3, characterized in that the cable is crimped at eight points by means of the first jaw.
5. Method according to one of the claims 1 to 4, characterized in that a trigger of the crimping means is pressed to successively drive the penetration of the first jaw and the shifting of the second jaw.
6. Method according to any of the claims 1 to 5, characterized in that the second jaw is closed about the cable to present an aperture that is slightly greater than the diameter of the cable and slightly smaller than the external diameter of the sleeve.

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