EP0142444A2 - Method of manufacturing a stator element for a rotary switch, and element made by this method - Google Patents

Abstract

1. Method of manufacturing a stator element for a rotary electrical switch, according to which a conductive lamellar annulus (10) is enclosed by over-moulding in a substantially annular body (20) consisting of insulating plastic material, the said annulus (10) comprising, projecting externally of the said body, connecting terminals (13) and, projecting internally of the said body, a plurality of radial tabs (11) intended for being bent over axially to form contact studs, characterised in that, prior to the aforesaid moulding, at least one zone (14) of small width is arranged in the portion of annulus (10) embedded in the plastic material (20), in that the aforesaid moulding comprises opposite and at each side of the said zone (14) two recesses (23, 24) the bottom of which is flush with the said switch and whereof at least the radially measured dimension is larger than the said width, and in that the continuity of the said annulus (10) is interrupted in the said zone (14) by cutting out the latter by means of a punch and of a die formed by one (24) of the aforesaid recesses.

Description

Many rotary electrical switches include at least one rotor element carrying two conductive pads capable of making electrical contact between two diametrically opposite pads of a stator element, or two pads aligned in an axial direction of two adjacent stator elements.

A stator element is generally constituted by a conductive element which, in a single piece, is molded by a plastic ring from which the studs (in the form of axially foldable legs) protrude internally and electrical connection terminals as well as the parts of connection project externally. To then constitute groups of pads electrically isolated from each other or individual pads, it is necessary to cut all or part of the annular portions of electrical and mechanical connection of the above-mentioned tabs (and terminals) which are located outside of the overmolding. This manufacturing method requires the installation of one or more cutting tools to make the necessary sections after overmolding, comprising a punch and a die. This cutting also constitutes a drawback because it generates relatively large drops of material by the very fact of the external location of the annular necessarily long connecting elements. However, the material used is often a precious metal (in which gold and / or silver enter for a large part) therefore expensive.

The invention intends to remedy the drawbacks of the prior art on the one hand, by simplifying the tools necessary for the production of a stator element and on the other hand by allowing a significant saving of material.

To this end, it therefore relates to a method of manufacturing a stator element for a rotary electrical switch according to which a conductive lamellar crown is trapped in a substantially annular body of insulating plastic material by overmolding, said crown comprising, projecting from the outside said body connection terminals and, projecting inside said body a plurality of radial tabs intended to be folded axially to form contact pads; prior to the above overmolding, at least one zone of small width is housed in the crown part embedded in the plastic, the above overmolding then being provided on either side of said zone, with two recesses whose bottom is flush with said conductor and of which at least the dimension measured radially is greater than said width, and the continuity of said crown is interrupted in said zone by cutting it by means of a punch and a die formed by one of the abovementioned recesses .

The invention also relates to a stator element resulting from the method which, in a first alternative embodiment comprises twelve studs, twelve terminals and twelve recesses through each of which the conductive ring is cut.

In a second variant, the stator element has twelve studs, six terminals and eight punching recesses through at least two of which the conductive ring is cut.

The invention will be better understood during the description given below by way of purely indicative and non-limiting example which will make it possible to identify the advantages and the secondary characteristics thereof.

• - la figure 1 est une vue de dessus d'un élément de stator selon l'invention,
• - la figure 2 est une coupe selon la ligne II-II de la figure 1,
• - la figure 3 est un schéma illustrant d'autres modes de réalisation possible de l'invention

Reference will be made to the appended drawings in which:

• FIG. 1 is a top view of a stator element according to the invention,
• FIG. 2 is a section along line II-II of FIG. 1,
• - Figure 3 is a diagram illustrating other possible embodiments of the invention

Referring first to Figures 1 and 2, we see a lamellar crown 10, conductive (for example from a cut silver strip) having a plurality of radial tabs 11 separated from each other others by slots 12 and a plurality of connection terminals 13. This ring 10 is trapped in an insulating plastic body 20 molded onto the ring 10, of substantially annular shape so that the tabs 11 are disposed inside the body 20 internally limited by a cylindrical surface 21 and that the terminals 13 are located outside of the external surface 22 of the body (here delimiting a square seen in plan). Each of the radial slots 12 is of length such that it defines with the outer edge 10a of the crown 10 a zone of small width 14 to the right of which the body 20 is provided with upper 23 and lower 24 recesses axially aligned. The bottom of these recesses is flush with each of the faces of the crown 10 and their dimension measured radially (for example along the axis of a slot) is greater than the width of the above-mentioned zone 14. These recesses 23 24, as well as the orifices 25 which comprise at least two angles of the body 20, are produced at the time of overmolding by the installation of suitable cores or pins.

Thus, after the overmolding operation which leads to the part of FIG. 1, the method of the invention consists in punching the part 14 of the crown 10 between a punch (not shown) guided by the recess 23 and a die constituted by the recess 24. It has been noted that the plastic material could very well play the role of a matrix if it has sufficient hardness characteristics, which is the case of plastics loaded with glass powder used in this technique. Depending on whether one wants to obtain electrically independent studs or groups of independent studs, all the parts 14 or a part of them will be punched. We see that the falls of noble material (silver) are at this stage reduced to the minimum (lower than the section of the recesses) and that the required tools for finishing the stator element is extremely simplified. Finally, conventionally, the flaps 11 above are folded down (as indicated at 11 ′ in FIG. 2) so as to form axial stud surfaces.

• -deux groupes de 6 plots en poinçonnant la couronne 10 dans les évidements 33 et 37,
• -trois groupes de 4 plots en poinçonnant la couronne 10 dans les évidements 31, 34 et 36,
• -quatre groupes de 3 plots en poinçonnant la couronne 10 dans les évidements 31, 33, 35 et 37,
• -six groupes de 2 plots en poinçonnant la couronne 10 dans les évidements 31, 32, 34, 35, 36 et 38.

The arrangements shown schematically in Figure 3 are identical to those of Figure 1 in principle. The differences lie, on the one hand in the number of connection terminals (6 instead of 12) which protrude outside the body 20 at determined locations compatible with, for example, a connection pitch imposed by a circuit printed on which the switch must be mounted, and on the other hand, in the number (eight) of recesses such as those 23, 24, of the preceding figures (here referenced 31 to 38) located in line with the defined narrow width zones by eight radial slots 12 longer than the other four slots 15 intended simply to constitute the legs 11. Thus, in this variant embodiment, it is possible to constitute:

• -two groups of 6 studs by punching the crown 10 in the recesses 33 and 37,
• - three groups of 4 studs by punching the crown 10 in the recesses 31, 34 and 36,
• -four groups of 3 studs by punching the crown 10 in the recesses 31, 33, 35 and 37,
• -six groups of 2 studs by punching the crown 10 in the recesses 31, 32, 34, 35, 36 and 38.

This alternative embodiment makes it possible to manufacture a stator comprising a stacking of different stator elements by their punching, finding in particular an application in a switching device controlled by a lock with several keys giving selective access to two, three, four or six circuits .

The invention finds an iterative application in the field of electrical components. It is not limited to the description which has just been given. In particular, the number of pads and terminals of the stator can be varied.

Claims (3)

1. A method of manufacturing a stator element for a rotary electrical switch according to which a conductive lamellar crown (10) is trapped in a body (20) substantially annular of insulating plastic material by overmolding, said crown (10) comprising, projecting from the outside of said body of the connection terminals (13) and, projecting inside said body, a plurality of radial lugs (11) intended to be folded down axially to form contact pads, characterized in that prior to the above overmolding, at least one zone (14) of small width is spared in the crown part (10) embedded in the plastic material (20), in that the above-mentioned overmolding comprises on the right and on either side of said zone (14 ) two recesses (23, 24) whose bottom is flush with said switch (10) and of which at least the dimension measured radially is greater than said width and in that the continuity of said crown (10) is interrupted in said zone (14) p ar cutting thereof by means of a punch and a die formed by one (24) of the above recesses. 2. stator element resulting from the method according to claim 1, characterized in that it comprises twelve studs (11), twelve terminals (13), and twelve recesses (23, 24) through each of which the conductive crown (10 ) is severed. 3. stator element resulting from the method according to claim 1, characterized in that it comprises twelve studs (11), six terminals (13) and eight recesses (31 to 38) for punching through at least two of which the conductive ring (10) is severed.

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