EP2458454B1 - Device for positioning a bridge on a bearing plate - Google Patents

Description

Field of the invention

The invention relates to a timepiece comprising a positioning device between a bridge and a plate that includes said timepiece, comprising a centering pin with symmetry of revolution, said plate comprising, for centering said bridge on said plate a centering female implantation, extending in an insertion direction and having facets in a polygonal or star-shaped section orthogonal to said insertion direction, and said female implantation being arranged to receive, resting on at least three said facets, said centering pin fixed on said bridge.

The invention relates to the field of watchmaking.

Background of the invention

The technical problem is that of the precise assembly of a component hereinafter called bridge on a structure, hereinafter called platinum. Precision assembly must be performed with a high positioning accuracy on the one hand, and alignment on the other hand, generally obtained by the use in cooperation of centering pins and reference bores. Unless bridge and platinum simultaneously on the same manufacturing means, it is difficult to obtain a positioning obtained by the cooperation of two centering pins and corresponding bores. If the components are made separately, it is necessary to assign tight tolerances to the manufacture to respect the distances between two centering elements. The different behavior in dilation and, more generally in deformation, components assembled together does not facilitate quality assemblies.

In practice, a male centering means, such as a centering pin, cooperates with a female centering means, such as a centering bore, or vice versa, and the centering thus produced defines a theoretical pivot axis around which the bridge can rotate relative to the corresponding stage. To ensure the accuracy of assembly, it is important to be able to angularly position the bridge relative to the plate perfectly. For this purpose, the plate generally comprises a female alignment means, preferably a linear guide, which cooperates with an alignment means, generally male constituted by a pin, and that comprises, the bridge, or vice versa. Naturally, a radial clearance, compared to pivot, and in the direction of the linear guide, is necessary to compensate for the relative deformations of the bridge relative to the plate, and especially the relocation between the bridge and the plate.

The means of centering the side of the bridge is generally constituted by a milled pivot, a pin or a screw-screw, of cylindrical shape, cooperating with a bore of the plate.

The means for aligning the bridge side is also constituted by a milled pivot, a pin or a foot-screw, of cylindrical shape, cooperating with an elongate slot or slot of the plate.

To ensure assembly and especially disassembly, it is generally provided a clearance between the male centering means and the female centering means. This game compromises the positioning accuracy, as well as the rigidity of maintaining the bridge, on the assembly line.

However, it is known to make a forced adjustment at the alignment means, so as to cooperate for example a groove of the plate with two short segments of the periphery of a pin fixed on the bridge. Thus the bridge remains removable, and high alignment accuracy can be ensured through forced adjustment.

Note that it is still known to perform a centering with an elastic split cylindrical pin, in cooperation with a cylindrical bore, however the concentricity between the free state and the compressed state of the pin is not guaranteed, nor the value of the tightening done.

Triangular pin assemblies cooperating with a smooth bore are still known, as described in the patent document. DE 2,034,993 on behalf of Précision Industries.

The document CH 669 680 A2 in the name of Richemont Int. SA describes a device for fixing a mobile made of a brittle material on a support element, in particular for positioning between a bridge and a plate. This mobile comprises an opening for receiving the support member, and it comprises an elastically deformable intermediate piece fixed in the opening and having a central hole. The intermediate piece redistributes a portion of the stresses exerted by the support member when the latter is driven into the central hole. The opening may comprise facets in a polygonal section cooperating with a cylindrical pin constituting the support element.

The document FR 2,282,554 in the name of ETA SA discloses a positioning of an element on a frame with the aid of three stops with which this element cooperates with three of its surfaces.

The document EP 1 850 193 A1 in the name of PATEK PHILIPPE describes the introduction of a deformable annular intermediate portion, comprising a hole for receiving a pin, in a housing of a spring or a wheel. The intermediate portion is made of a lower yielding material than the material of the spring or the wheel.

The document FR 1 590 572 A in the name of PARRENIN describes the fixing of watch structure parts, each comprising a bore and an alignment window, whose axis is directed towards the axis of the bore, on a plate provided with a pin or similar.

The document JP 2005 291977 A on behalf of CALSONIC KANSEI describes a coupling structure of a measuring instrument for a vehicle to reduce the risk of damage such as cracks, by precise positioning and the matching of two components, by coupling a cylindrical foot with a lip of a non-revolution housing, especially faceted. The documents EP1850193 A1 and JP2005-291977 describe the fastening of horological structure piece.

Summary of the invention

The invention proposes to overcome this problem by proposing means for centering and aligning a bridge on a plate adapted to ensure the required centering and alignment accuracies, while allowing the disassembly and subsequent reassembly of the bridge. . The invention also proposes a mounting method to ensure these accuracies.

The invention consists in producing the centering element with a support on a plurality of points, preferably on three points.

For this purpose, the invention relates to a timepiece comprising a positioning device between a bridge and a plate that includes said timepiece, comprising a centering pin with symmetry of revolution, said plate comprising, for the centering of said bridge on said plate, a female centering implant, according to claim 1.

Brief description of the drawings

• la figure 1 représente, de façon schématisée, partielle et en perspective, un détail d'une pièce d'horlogerie comportant un pont et une platine assemblés avec un dispositif selon l'invention ;
• la figure 2 représente, de façon éclatée, schématisée et en perspective, l'ensemble de la figure 1 ;
• la figure 3 représente, de façon schématisée et en vue de dessus, une implantation femelle de centrage selon l'invention dont est équipée une platine telle celle des figures 1 et 2 ;
• les figures 4 et 5 représentent, de façon schématisée et en coupe brisée dans deux demi-plans passant par l'axe d'un pion de centrage selon la coupe AA de la figure 3, un pont et une platine assemblés selon l'invention, dans deux variantes différentes ;
• les figures 6 et 7 représentent, de façon schématisée et en vue de dessus, deux exemples non limitatifs d'agencements possibles d'une platine pour la mise en oeuvre de l'invention ;
• la figure 8 représente, de façon schématisée et en coupe perpendiculairement à une direction d'insertion, une implantation femelle de centrage selon l'invention, réalisée dans un matériau issu des MEMS, ou en silicium, ou selon le procédé « LIGA » ou similaire.

The invention will be better understood on reading the description which follows, with reference to the appended drawings in which:

• the figure 1 represents, schematically, partially and in perspective, a detail of a timepiece comprising a bridge and a plate assembled with a device according to the invention;
• the figure 2 represents, exploded, schematized and in perspective, the whole of the figure 1 ;
• the figure 3 represents schematically and in plan view, a female centering implantation according to the invention which is equipped with a plate such as that of Figures 1 and 2 ;
• the Figures 4 and 5 are schematically represented in broken section in two half-planes passing through the axis of a centering pin according to section AA of FIG. figure 3 , a bridge and a plate assembled according to the invention, in two different variants;
• the Figures 6 and 7 show schematically and in plan view, two non-limiting examples of possible arrangements of a plate for the implementation of the invention;
• the figure 8 represents, schematically and in section perpendicular to an insertion direction, a female centering implant according to the invention, made of a material derived from MEMS, or silicon, or according to the "LIGA" method or the like.

Detailed Description of the Preferred Embodiments

The problem posed is particularly sensitive in the field of watchmaking, where any positioning defect during assembly is translated, if not by the damage of the components, at least by an altered operation, and the obligation of dismantling and then 'a reassembly, either factory, which is already very expensive, or after-sales, which adds to the costs of labor those related to a deterioration of brand image.

The small size of the components does not allow to move the centering and alignment pins beyond a few millimeters, and any angular fault and / or positioning immediately affects the entire movement.

Very often the alignment adjustment member is subject to a correct sliding fit, or with a very low tightening. The actual fastening of the components to one another is conventionally carried out by screws, if possible remote from the centering and alignment means, which is not always possible in watchmaking where, on the contrary, it may be advantageous to use the 'access available at the level of the centering and alignment pins, to provide the fixing means. A particular constraint is the need for the assemblies to be dismountable. Another constraint is the possibility of adjusting the height of a bridge relative to a plate, and not only in positioning in the plane. The assemblies used must therefore lend themselves to such fine adjustments and dismantling.

The invention relates to a particular arrangement of the bridge and the plate, which can be achieved either by a manufacture in finished dimensions of these components, or by an adaptation or modification of existing components by the attachment of inserts. In particular, it will be described hereinafter a so-called drop insert, comprising a particular housing according to the invention, and which allows its implementation on any type of component, and may allow to modify only a plate, using in the state a already existing bridge. A particular method of assembly guarantees the best quality of assembly, in respect of the components, it guarantees the adjustment ranges, and takes into account the manipulations and in particular the transport between assembly stations which the pre-assembled components undergo, to ensure a good conservation of settings already made and the integrity of the sets.

Thus, the invention relates to a timepiece 100 comprising at least one positioning device 1 between a bridge 2 and a plate 3.

It is understood that device refers to the particular arrangement of the bridge 2 and the plate 3, designed to allow their precise positioning during assembly.

According to the invention, the plate 3 comprises, for the centering of the bridge 2 on the plate 3, a female centering implantation 4. As visible on the Figures 1 to 5 this female implantation 4 extends in an insertion direction Δ1, and has facets 5 in a polygonal or star-shaped section orthogonal to the insertion direction Δ1. This female implantation 4 is arranged to receive, bearing on at least three of the facets 5, a centering pin 6 with symmetry of revolution fixed on the bridge 2.

The essential is to ensure a regular distribution of the contact points between the female implantation 4 and the centering pin 6, so as to compensate for the resulting forces and to ensure a zero resultant to the theoretical positioning axis of the pion of centering.

Thus, preferably, the distribution of the points of contact between the female implantation 4 and the pin 6 is regular with respect to the circumference of the latter, so as to balance, with respect to the axis of revolution of the latter, the reaction forces to which it is subjected from this female implantation 4.

In a particular embodiment, but not limiting, the polygonal section, or star, or the like, is preferably regular around a straight axis, that is to say that it has at least one symmetry with respect to a plane passing through this rectilinear axis, parallel to the introduction direction Δ1.

It is understood that it is not necessary to have a symmetrical alignment, as represented on the Figures 6 and 7 , even if it is a convenient embodiment of the invention, in particular because of the ease of carrying out dimensional control on the machining performed.

Preferably, for manufacturing by stamping or the like, the section of the female implantation 4 is constant, or substantially constant. However, it may be provided a pre-centering, for example in the form of a triangular machining, or homothetic shape to that of the female implantation 4, or other, in the form of a conical inlet, or radiated, to facilitate a pre centering the centering pin 6 during its presentation.

Preferably, the polygonal section is triangular, so the centering support is performed on three points and is perfectly isostatic. Or, in a star design, it comprises three evenly distributed ranges.

The polygonal section is circumscribed to an inscribed circle C1 of diameter D1, which is smaller than the diameter D7 of a cylindrical centering surface 7 that comprises the centering pin 6.

The realization of the female implantation 4 can be carried out in different ways, the most economical being, or a contouring milling with facets tangent to arcs of circle, or preferably a stamping with secant facets with arches of circle.

The difference between diameters D7; D1 is, for application to a timepiece, between 2 and 15 microns, and is preferably maintained in the range of 4 to 6 microns. A centering is thus achieved with a slight tightening, of controlled value, in a clamping zone 27.

In an advantageous embodiment, the centering pin 6 has a stepped profile and comprises, in addition to a cylindrical centering surface 7 of diameter D7, at minus an introduction section 28 of diameter D8 less than or equal to the diameter D1 of the circle inscribed in the polygonal section. The pawn 6 can be evolutionary as visible on the figure 4 , or have several distinct ranges, as visible on the figure 5 .

The female implantation 4 is, as visible on the figure 3 , inscribed in a circumscribed circle C2, and the maximum value of the arrow F between a facet 5, supported on the polygon defining the polygonal section, and the circle C2 circumscribed in the female implantation 4 is such that: $$\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="imgf0001.png"\; state="\{\{state\}\}">D</figure-callout>}1/2<\left(\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="imgf0001.png"\; state="\{\{state\}\}">D</figure-callout>}1/2\right)+\mathrm{F}<\left(\mathrm{<figure-callout\; id="1"\; label="D"\; filenames="imgf0001.png"\; state="\{\{state\}\}">D</figure-callout>}1/2\right)/{\mathrm{sin\; 30}}^{°}.$$

Female polygonal profiles can be produced by different technologies, in particular by stamping in the case of turntables of timepieces, which guarantees precision, repeatability, and controlled cost. It is also possible to use technologies such as sinking or wire EDM, but which are more expensive.

A good solution to reduce production costs, consists of a development of bridges and / or turntables with MEMS type technologies or according to the "LIGA" process, in particular silicon or the like.

In this type of elaboration, accuracy and tightness are perfectly controlled, especially since it is possible to exploit the elasticity of such materials, in particular silicon, as visible in FIG. figure 8 , where the centering female implantation 4 is surrounded by peripheral chambers or recesses 16, having the effect of creating elastic lips or partitions 17. The clamping of the centering pin 6 can be perfectly controlled, and with better repeatability than with machining carried out in metals. In short, the forced-fit clamping recommended by the invention can be perfectly controlled, at an acceptable cost, thanks to the use of these technologies.

As visible on the Figures 1, 2, 6 and 7 , the plate 3 comprises, for the alignment of the bridge 2 relative to the plate 3, a rectilinear female alignment housing 8 with parallel faces 9, 10. This housing 8 is aligned in an alignment direction Δ2 on a plane of symmetry P that comprises the female implantation 4 parallel to the insertion direction Δ1, and the bridge 2 comprises an alignment pin 11, which comprises at least two cylindrical bearing surfaces 12, 13, symmetrical with respect to an axis of revolution Δ3.

The distance 18 between the parallel faces 9, 10 of the alignment housing 8 is preferably smaller than the diameter D11 defined by the two spans. cylindrical 12 and 13, and the difference between the distance 18 and the diameter D11 is between 2 and 15 microns, and preferably between 4 and 6 microns, so as to ensure a slight clamping during assembly.

In a particular variant embodiment, the centering pin 6 may comprise a housing for receiving a screw arranged to cooperate with a tapping that comprises the plate 3, for fixing the bridge 2 on the plate 3.

In the same way, the alignment pin 11 may comprise an oblong slot for receiving a screw arranged to cooperate with a tapping that includes the plate 3, for fixing the bridge 2 on the plate 3.

Naturally, everything that is exposed here can be realized in an inverse configuration, the male components becoming female and vice versa.

Preferably, the bridge 2 comprises, around the centering pin 6, a recess 14, which is arranged to allow a backflow of material from the plate 3, and / or a radius or a shoulder at the foot of the pin, and / or a burr of the plate during assembly with clamping of the centering pin 6 in the female implantation 4 centering.

In a preferred application of the invention, the plate 3 is a timepiece platen and the bridge 2 is a timepiece bridge. Or platinum 3 is a timepiece bridge, and bridge 2 is a timepiece platinum.

The invention also relates to a variant with a drop 15, which is arranged to be fixed on a plate. This drop 15 is an insert which comprises, for centering a pin on the plate, a female centering implantation 4. According to the invention, the female centering implantation 4 extends in an insertion direction Δ1, and comprises facets 5 in a polygonal section orthogonal to the insertion direction Δ1, and the female implantation 4 is arranged to receive, bearing on at least three of the facets 5, a centering pin with symmetry of revolution. It is understood that the use of such a drop 15 makes it easy to transform a classic timepiece. The drop 15 advantageously comprises an outer diameter 19 of narrow tolerance, arranged to cooperate with a bore 20 formed on a plate 3, with a very low clamping of the order of a few micrometers.

The invention has been described here with a centering female implantation at the level of the plate, which represents the most usual case in watchmaking, but understands that of course the reverse configuration is equally feasible, without departing from the invention.

• on usine la platine 3 pour réaliser l'implantation femelle de centrage 4, ou pour recevoir une goutte 15, que l'on fixe ensuite sur cette platine 3;
• on usine la platine 3 pour réaliser le logement d'alignement 8 femelle rectiligne à faces parallèles 9, 10, ou on fixe sur la platine un insert comportant un tel logement d'alignement 8 ;
• on positionne le pion de centrage 6 dans l'implantation femelle de centrage 4, et on l'enfonce librement selon la direction d'introduction Δ1 pour effectuer un pré-centrage, en maintenant le pont 2 à une distance de la platine 3 qui est supérieure à la distance théorique d'assemblage entre le pont 2 et la platine 3. Ce pré-centrage est utile pour permettre l'introduction des pivots des éventuels mobiles dans des paliers du pont ;
• on positionne le pion d'alignement 11 sur le logement d'alignement femelle 8, et on l'enfonce selon la direction d'introduction Δ1, pour effectuer un pré-centrage, en maintenant le pont 2 à une distance de la platine 3 qui est supérieure à la distance théorique d'assemblage entre le pont 2 et la platine 3;
• on chasse le pion de centrage 6 dans l'implantation femelle de centrage 4 de façon à faire coopérer la portée de centrage 7 avec au moins trois des facettes 5, en réglant le pont 2 à une distance de la platine 3 qui est égale à la distance théorique d'assemblage entre le pont 2 et la platine 3;
• on chasse le pion d'alignement 11 dans le logement d'alignement femelle 8, en réglant le pont 2 à une distance de la platine 3 qui est égale à la distance théorique d'assemblage entre le pont 2 et la platine 3 ;
• on immobilise au moins le pion de centrage 6 ou le pion d'alignement 11 sur la platine par pointage, c'est-à-dire en au moins un point, au moyen de colle, d'une fusion ponctuelle laser, ou similaire.

According to a method of mounting the bridge 2 on the plate 3 using the device 1, or the bridge 2 on a plate 3 equipped with a drop 15 as described above, the following operations are carried out in this order :

• the plate 3 is machined to carry out the centering female implantation 4, or to receive a drop 15, which is then fixed on this plate 3;
• platen 3 is machined to form rectilinear female alignment housing 8 with parallel faces 9, 10, or an insert comprising such an alignment housing 8 is fixed on the plate;
• the centering pin 6 is positioned in the centering female implantation 4, and it is freely inserted in the insertion direction Δ1 in order to pre-center, keeping the bridge 2 at a distance from the plate 3 which is greater than the theoretical distance of assembly between the bridge 2 and the plate 3. This pre-centering is useful to allow the introduction of the pivots of the possible mobiles in bearings of the bridge;
• positioning the alignment pin 11 on the female alignment slot 8, and pressing it in the insertion direction Δ1, to perform a pre-centering, maintaining the bridge 2 at a distance from the plate 3 which is greater than the theoretical assembly distance between the bridge 2 and the plate 3;
• the centering pin 6 is driven into the centering female implantation 4 so as to make the centering surface 7 cooperate with at least three of the facets 5, by adjusting the bridge 2 at a distance from the plate 3 which is equal to the theoretical distance of assembly between the bridge 2 and the plate 3;
• the alignment stud 11 is driven into the female alignment housing 8, by adjusting the bridge 2 at a distance from the plate 3 which is equal to the theoretical assembly distance between the bridge 2 and the plate 3;
• at least the centering pin 6 or the alignment pin 11 is immobilized on the plate by pointing, that is to say at least one point, by means of glue, a laser point fusion, or the like.

Optionally, the bridge 2 is fixed to the plate 3 by at least one clamping screw.

In the preferred embodiment of the invention, the female centering is in the form of a triangle, with which cooperates a cylindrical pin. Thus the contact is limited to three short segments, the centering is assured, and the assembly and disassembly are possible due to a forced fit.

Thus centering and alignment between bridge and platinum are performed without play, and without loss of positioning accuracy. On the contrary, it is improved.

Due to the forced adjustment of both the centering member and the alignment member, the holding of the bridge is improved both during its positioning operation and during its screwing operation on the production line.

This arrangement also prevents, during transportation on the assembly line between these two operations, the bridge does not lift, and comes into contact with the wheel pivots and damages by deforming when it is then fixed by screwing or the like. This arrangement still avoids sharing the lubrication in unplanned locations, with a distribution of lubricant other than desired.

These solutions provided by the invention thus deal with a recurring problem in watchmaking, and which has never been satisfactorily solved until now.

Claims (13)

1. Timepiece comprising a positioning device (1) between a bridge (2) and a plate (3) comprised by said timepiece, comprising a removable centring pin (6) with revolution symmetry, said plate (3) arrangement, for the centring of said bridge (2) on said plate (3), a female centring arrangement (4), extending along a direction of insertion (Δ1) and comprising faces (5) along a polygonal cross-section or star orthogonally to said direction of insertion (Δ1), and in that said female arrangement (4) is arranged to receive a centring pin (6) with revolution symmetry fixed on said bridge (2) abutting on at least three of said faces (5) characterized in that said centring pin (6) has a housing for receiving a screw, arranged for cooperating with a tapping in said plate (3), for fixing said bridge (2) to said plate (3).
2. Timepiece according to claim 1, characterized in that said polygonal cross-section is circumscribed to an inscribed circle (C1) having a diameter (D1), which is smaller than the diameter (D7) of a cylindrical centring shoulder (7) comprised in said centring pin (6)
3. Timepiece according to claim 1 or 2, characterized in that the difference between said diameters (D7; D1) is comprised between 2 and 15 µm.
4. Timepiece according to claim 2 or 3, characterized in that said centring pin (6) has a staged profile and, in addition to a cylindrical centring shoulder (7) of diameter (D7), includes at least one insertion section having a diameter (D8) smaller than or equal to said diameter (D1) of said circle inscribed in the polygonal cross-section.
5. Timepiece according to any of preceding claims, characterized in that said female arrangement (4) is inscribed in a circumscribed circle (C2), and the maximum value of the arrow (F) between the polygon defining said polygonal cross-section said circle (C2), circumscribed to said female arrangement (4), is such that: D1/2 < (D1/2) + F < (D1/2)/ sin 30°.
6. Timepiece according to any of preceding claims, characterized in that the distribution of the points of contact between said female arrangement (4) and said pin (6) is regular relative to the circumference of the latter, so as to balance, relative to the axis of revolution of the latter, the reaction forces to which it is subjected by said female arrangement.
7. Timepiece according to any of preceding claims, characterized in that said polygonal cross-section is regular about a rectilinear axis.
8. Timepiece according to any of preceding claims, characterized in that said polygonal cross-section is triangular.
9. Timepiece according to any of preceding claims, characterized in that said plate (3) comprises, for the alignment of said bridge (2) with respect to said plate (3), a female linear alignment housing (8) with parallel faces (9, 10) aligned in an alignment direction (Δ2) on a plane of symmetry (P) comprised by said female arrangement (4) parallel to said insertion direction (Δ1), and said bridge (2) comprises an alignment pin (11) including at least two cylindrical shoulders (12, 13), which are symmetrical relative to an axis of revolution (Δ3).
10. Timepiece according to claim 9, characterized in that the distance between said parallel faces (9, 10) of said alignment housing (8) is smaller than the diameter (D11) defined by said two cylindrical shoulders (12, 13), and the difference between said distance and said diameter (D11) is comprised between 2 and 15 µm.
11. Timepiece according to claim 9 or 10, characterized in that said alignment pin (11) comprises an oblong housing for receiving a screw, arranged for cooperating with a tapping in said plate (3), for fixing said bridge (2) to said plate (3).
12. Timepiece according to any of preceding claims, characterized in that, around said centring pin (6), said bridge (2) includes a recess (14) arranged to allow upsetting of the material of said plate (3) when said centring pin (6) is tight-fit assembled in said female centring arrangement (4).
13. Timepiece according to any of preceding claims, characterized in that said timepiece includes at least one collet (15) arranged to be fixed on said plate and comprising, for the centring of a pin on said plate, a said female centring arrangement (4).

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