EP0320323A1 - Resilient electrical contact members, incorporated in connectors, and their manufacturing process - Google Patents

Abstract

The electrical contact member (1c) is made up of a practically flat piece of metal, obtained by cutting or punching, the outline of the part (11) of this member (1c) which ensures contact with an associated contact member (socket 16, 17, 18, printed circuit board, etc.) being such that it allows this part (11) to be compressed elastically in its plane, possibly after treatment of the metal of this part (copper with beryllium or the like) ensuring it, in a known manner, the necessary elasticity after the cutting or punching operations.

Description

The invention relates to elastically deformable contact members, intended to be incorporated in electrical connectors and to cooperate in particular with contact sockets, as plugs, but also, if necessary, with the conductive tracks of circuit boards. prints. It also relates to the methods of manufacturing such contact members.

Electric contact members are known which are constituted by several oval loops, formed by bending of elastic metal wire, the ends of which are gathered in a sleeve, said loops being arranged parallel to each other so that their assembly constitutes a loop. single oval (French patent n ° 1.426.379 and its certificates of addition filed by the applicant). There are also known electrical contact members formed by cutting a sheet and bending in loop outside the sheet plane (French patent n ° 69.02462 and its certificates of addition also filed by the applicant). In both cases, the elasticity of the contact member is due to the presence of the loop of wire or cut sheet metal, which required at least one folding operation.

Despite their advantages, the known contact members mentioned above have the drawback of requiring, for their manufacture, long and varied series of operations as well as relatively complicated automatic or semi-automatic machines.

The invention aims to provide new electrical contact members and a method of manufacturing such members which eliminate this drawback of known contact members.

According to one of its aspects, the invention relates to an elastically deformable electrical contact member, essentially characterized in that it consists of a practically flat piece of metal, obtained by cutting or punching, the contour of the part of this member which ensures contact with an associated contact member (socket, printed circuit board, etc.) being such that it allows this part to be compressed elastically in its plane, possibly after treatment of the metal of this part (beryllium copper or the like) ensuring it, in a known manner, the necessary elasticity after the cutting or punching operations.

According to another of its aspects, the invention relates to a method of manufacturing an elastically deformable electrical contact member, characterized in that a piece of metal is cut from a practically flat metal strip by giving, to the part of this part which must ensure contact with an associated contact member, a contour such that it allows this part to be compressed elastically in its plane, once the metal of this part has possibly been subjected to a treatment suitable ensuring the necessary elasticity.

It is true that if the metal strip is made of beryllium copper, it is necessary, once the contact is finished after cutting and shaping, to make it undergo a heat treatment. Beryllium copper is supplied in strips, not heat treated; it is "soft" (malleable) and therefore lends itself to folding, bending, shaping. The direction of rolling is of little importance for the configuration of the part, but the contact member can also be produced starting from a metal such as stainless steel or from a phosphorous bronze, the mechanical properties of which are not obtained by a heat treatment but by work hardening during the rolling of the strip (strip in the state: spring, 4/4 hard, 1/2 hard ...).

One of the advantages of the contact member according to the invention is that, not undergoing shaping (that is to say folding, bending, etc.), it can be made of a metal in the state spring. There is no risk of starting mechanical breaks because there is no bending.

It is therefore understood that the electrical contact members in accordance with the invention can be easily manufactured, by means of the process in accordance with the invention, by simple cutting operations, to be carried out successively on the same cutting press, optionally followed by treatment. conventional, without it being necessary to carry out the usual deformation or folding operations outside the plane of the cut piece, unlike the solution described in the above-mentioned French patent n ° 69.02462, which allows the use of presses for this purpose cutting machines, simplified design.

• - la figure 1 montre, en perspective, un organe de con­tact conforme à l'invention et la bande de métal dans laquelle il a été découpé ;
• - les figures 2 à 5 montrent chacune, en perspective, une variante de la figure 1 ;
• - les figures 6 à 10 montrent, un plan, et les figures 11 et 12, en perspective, diverses formes possibles pour les organes de contact :
• - les figures 13 et 14 montrent, en perspective, diverses possibilités d'incorporation, dans des connecteurs, d'organes de contact conformes à l'invention 1 et
• - les figures 15 et 16 illustrent deux procédés de découpage d'organes de contact conformes à l'invention.

The invention will now be described in more detail with the aid of the accompanying drawings, in which:

• - Figure 1 shows, in perspective, a contact member according to the invention and the metal strip from which it was cut;
• FIGS. 2 to 5 each show, in perspective, a variant of Figure 1;
• - Figures 6 to 10 show a plan, and Figures 11 and 12, in perspective, various possible shapes for the contact members:
• FIGS. 13 and 14 show, in perspective, various possibilities of incorporating, into connectors, contact members in accordance with the invention 1 and
• - Figures 15 and 16 illustrate two methods of cutting contact members according to the invention.

As shown schematically in Figure 1, the electrical contact member according to invention 1 consists of a metal part (or metal alloy) practically flat, obtained by cutting or punching (as will be exposed in detail with reference to FIGS. 15 and 16), the outline of part 11 of this member which ensures contact with an associated contact member (as will be explained in detail with regard to FIGS. 13 and 14) being such that it allows this part to be compressed elastically in its plane, as shown diagrammatically by arrows opposite in FIG. 1. The rest of the contact member 1 is constituted by a shank 12 of square or rectangular section intended to be connected by soldering or winding to an electrical conductor.

So that the tools used for cutting are sufficiently solid, it is advisable, as is known, to give the width 1 measured (parallel to the plane of the original metal strip 2) over the major part of the member contact 1 a value at least equal to the thickness e of the latter or of the metal strip 2. To ensure that the elastic deformation of the deformable part 11 of the contact member 1 occurs in its plane, it that is to say practically without bulging or transverse deformation, it is therefore preferable to locally weaken this deformable part 11 so that the deformation occurs preferably in the weakened or reduced thickness and / or width zone.

When this deformable part 11 has, in substance, the form of a closed lozenge in diamond shape (as shown in FIG. 1), such local weakening can be achieved:
- By locally reducing the width 1, during cutting, for example at the four vertices of the inner contour of the loop, as shown in 3 for the contact 1a in FIG. 2, or at three of the vertices of the external contour;
- Or by using a profiled metal strip 2b having, unlike the metal strip 2 in Figures 1 and 2 and as shown in Figure 3, a thickness weakened by a groove 4 or by a recess 5 at the most vertices distant from each other of the lozenge-shaped loop, which gives rise to decreases 6 in the thickness e at these vertices;
- Or, as shown in Figure 4, by combining the solutions illustrated in Figures 2 and 3;
- Or, as shown in Figure 5, adding to the embodiment of Figure 4 a decrease in thickness 7 at the other vertices of the loop, thanks to the presence of a groove 8 suitably placed on the strip of original metal, designated here by 2c.

On reading the above, the tradesmen are able to develop local weakenings which differ more or less from those which have just been described, taking into account the shape and the working conditions of the deformable part. 11 contact bodies.

In the foregoing, it has been assumed that the deformable part 11 of the contact member has the form of a closed loop in the form of a diamond, but other forms are also possible, some of which are illustrated by way of examples in the figures. 6 to 13. In particular, FIGS. 6 to 11 and 13 illustrate deformable parts in the form of closed loops while FIG. 12 illustrates a deformable part having a shape other than that of a loop closed.

FIG. 6 represents a loop in the form of an isosceles triangle with an obtuse apex, which makes it possible to obtain a contact point, plus a contact generator. FIG. 7 represents a loop formed on one side by a straight part and on the other by a wavy part, this loop making it possible to obtain two contact points, plus a contact generator. The embodiment of FIG. 8, which makes it possible to obtain two contact points twice, differs from that of FIG. 7 by the presence of two corrugated parts instead of only one. The embodiment of FIG. 9, which makes it possible to obtain two contact points twice plus continuity by two other internal contact points, differs from that of FIG. 8 by the presence of an appendage extending the tail 11 to inside the loop and which can be used to limit the deformation of the corrugated parts inwards. According to the embodiment of Figure 10 which allows to obtain many points of contact, the loop, as in the embodiments of Figures 1 to 5, has roughly the shape of a diamond but has a series of local weakenings 13 which, unlike the embodiments of FIGS. 2, 4 and 5, are arranged outside the loop. According to the embodiment of Figure 11, the loop externally has an oval shape and it is made more easily deformable by the presence of two inner branches 13 arranged in a U which opens opposite the tail 12. According to the embodiment of FIG. 13, the contact member designated here by 1c comprises an oval loop, with two weakenings similar to those of FIG. 2.

As said above, a shape other than that of a loop can be envisaged but it is in any case preferable that this shape is elongated in the direction of the tail 12, that is to say in a direction perpendicular to that of the deformation undergone during the setting contact. Thus, Figure 12 shows a contact member whose deformable part 11 has, as in Figure 11, an oval outer shape but which is constituted by two branches 14 adjoining the tail 12 and separated by a slot 15 of which the width is sufficient to allow the deformation of the part 11 by bringing these two branches 14 together.

The contact member according to the invention can be incorporated into an electrical connector of the usual type, either alone (as shown on the left of FIG. 13), or stacked with at least one identical or similar contact member (as shown to the right of figure 13).

By way of example, FIG. 13 represents in a simplified manner a plug and socket connector and FIG. 14 a connector for a printed circuit board.

In FIG. 13, in which the usual insulating bodies have been omitted to simplify the drawing, it can be seen that the contact 1c (or the pair of contacts 1c) can, as a plug, cooperate with a socket preferably not split, such as than a circular profile socket 16, an approximately rectangular profile socket 17 or an approximately oval profile socket 18. The only requirement is that the internal dimension of the socket 16, 17 or 18 is less than the corresponding external dimension (at rest) of the deformable part of the contact member.

In Figure 14, there is shown a connector 19, for printed circuit boards 20, consisting of a housing 21 of insulating material. In known manner, this connector comprises guide means (not shown) for the card 20 and cells 22 for contact members such as 1c whose tails 12 pass through the bottom of these cells. The oval (or diamond) shape of the deformable part 11 of each contact member 1c facilitates the introduction of the card 20 and the deformation of this deformable part 11 in its plane which is perpendicular to that of the card.

Unlike almost all contact organs existing electrical, it appears from Figures 13 and 14 that the elastic deformation caused by the contacting is obtained by exerting a pressure on the edge (or thickness of the metal strip to be cut 2) and not on the width of the cut contact, width which is then arched or folded (see the above FR-A-69 02462). This results in less bulk between the axes of neighboring contact members, that is to say a reduction in the distance or "pitch" between neighboring contact members of the same connector such as that of FIG. 14 .

The symmetrical diamond or oval shape of the contact member of FIGS. 1 to 5 makes it possible to obtain the best flexibility for a closed loop. The contact members of FIGS. 11 and 12 are open over a certain length along their axis in order to ensure good flexibility while locating the contact zone not in the middle of the length a of the deformable part 11 but very close to the front face (face located to the left of Figures 1 to 12 and 14 and to the right of Figure 13) the distance b between the front face and the contact area advantageously being between 1/4 and 1/5 of the length a in the case of an open loop (Figures 11 and 12) while, in the case of a more or less symmetrical closed loop, this ratio changes to 1/2. If a ratio of the order of 1/4 to 1/5 was indeed provided for a closed loop, the effort for the same deformation would be much greater. What is known as "head contact" (Figures 11 and 12) is interesting for meeting certain French or United States standards.

FIGS. 15 and 16 illustrate the method of manufacturing the contact members in accordance with the invention which it has been assumed, by way of example, that they were the contact members 1c of FIGS. 13 and 14. Of course, specialists in the subject would be able to adapt this process to the various contact members in accordance with the invention and such, in particular, as those of FIGS. 1 to 12.

FIGS. 15 and 16 represent the essential elements of a cutting press, namely a rectilinear guide 25 for a metal strip 2, means shown diagrammatically by an arrow 27 for advancing the metal strip 2 in the guide 25 (the Figures 15 and 16 showing the strip 2 away from the bottom of the guide 25 only to make the drawing clearer) and punches cooperating with dies formed in the bottom of the guide 25, these punches succeeding each other in the direction of the arrow 27 and being driven in synchronism with a reciprocating movement perpendicular to the plane of the bottom of the guide and / or to the plane of the metal strip 2. In general, the cutting press comprises means (not shown) to cut one of the edges or shore 28 of the strip 2 as rigorously rectilinear as possible and to make pilot holes 29 in this strip 2 at constant distance from the shore 28 and at a constant distance from each other, these holes 29 cooperating with means (not shown) which advance the metal strip 2 intermittently by distance (or "step") equal to the above gap between the holes 29.

According to the embodiment of Figure 15, a first punch 30, which cooperates with a die 31, is arranged so as to form the inner contour 32 of the deformable part 11 of the contact member 1c, by punching a drop 33, while a second punch 34, which cooperates with a matrix 35, is arranged so as to form the entire outer contour 36 of the contact member 1c, so that the contacts 1c fall loose at the rate of outward strokes (shown schematically by arrows 37) of the punches 30 and 34.

According to the embodiment of FIG. 16, a first punch 38, which cooperates with a matrix 39, is arranged so as to form the major part of the external half-contour of two neighboring contact members 1c, by punching a drop 40, so that contact blanks 41 remain adjacent to the strip by their two longitudinal ends. The second punch and the second die are identical to the first punch and die 30 and 33 of FIG. 15 and are designated by the same references. In this way, the contacts 1c come out of the cutting press in the direction of the arrow 27 while remaining temporarily held by their longitudinal ends with what remains of the strip 2, which facilitates the subsequent treatment operations (heat treatment, protection electrolytic and others).

It is easy to understand, on examining FIGS. 15 and 16, that the method of manufacturing the contact members is greatly facilitated by the fact that all of its steps can be carried out on the same cutting press since no folding operation of cambering is required. It is certain that the production of the described contacts requires much less complex tooling than the other known contacts.

Claims (10)

1. Elastically deformable electrical contact member, intended to be incorporated in electrical connectors and to cooperate in particular with contact sockets, as a plug, but also, if necessary, with the conductive tracks of printed circuit boards, characterized in that it consists of a practically flat piece of metal, obtained by cutting or punching, the contour of the part (11) of this member (1) which ensures contact with an associated contact member (socket, card of printed circuits, etc.) being such that it allows this part (11) to be compressed elastically in its plane, possibly after treatment of the metal of this part (beryllium copper or the like) ensuring it, known manner, 1 elasticity necessary after the cutting or punching operations. 2. Contact member according to claim 1, characterized in that it has an elongated shape in the direction perpendicular to that of the deformation undergone during contacting. 3. Contact member according to claim 2, characterized in that it has a diamond or oval shape. 4. Contact member according to any one of claims 1 to 3, characterized in that it has the form of a closed loop. 5. Contact member according to claim 4, characterized in that the thickness and / or the width of the deformable part (11) is locally reduced at the places to be preferably deformed when brought into contact. 6. Contact member according to claim 2, characterized in that, at its end opposite the tail (12), it has an open shape (Figures 11 and 12) and in that the contact zone is located at a distance (b) of this open end which is between 1/4 and 1/5 of the length (a) of the deformable part (11). 7. Method of manufacturing a contact member electrically deformable, intended to be incorporated in electrical connectors and to cooperate in particular with contact sockets, as a plug, but also, if necessary, with the conductive tracks of printed circuit boards, characterized in that cutting a piece of metal from a practically flat metal strip, giving the part (11) of this part which must ensure contact with an associated contact member, a contour such that it allows this part to be compressed elastically in its plane, once the metal of this part has possibly been subjected to an appropriate treatment ensuring it the necessary elasticity. 8. Method according to claim 7 for manufacturing a contact member according to claim 5, characterized in that a profiled metal strip is used whose thickness is locally reduced by the presence of grooves (4, 8) and / or recesses (5). 9. Method according to one of claims 7 and 8 for manufacturing a contact member according to one of claims 4 and 5, characterized in that one successively cuts the inner contour of the loop and the entire outer contour of the contact member, in order to obtain bulk contact members. 10. Method according to one of claims 7 and 8 for manufacturing a contact member according to one of claims 4 and 5, characterized in that one successively cuts the major part of the outer half-contour of two neighboring contact members on the same metal strip (2), then the inner contour of the loop, in order to obtain contact members remaining temporarily maintained by their longitudinal ends to what remains of the metal strip (2).

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