EP2400355A1 - Shockproof system for a timepiece - Google Patents

Abstract

The bearing has a support (1) equipped with a housing designed to receive a pivot system into which a rod is inserted. A base of the support comprising a hole is provided for passage of a staff by a rod. Resilient units i.e. springs (10), exert axial force on the pivot system. The resilient units are made from partially amorphous metal alloy including a metal element selected in a list comprising gold, platinum, palladium, rhenium, ruthenium, rhodium, silver, iridium or osmium. The resilient units are in the shape of a loop.

Description

The present invention relates to an anti-shock system for a mobile axis of a timepiece. The shaft comprises a beam, having a support, said support being provided with a housing adapted to receive a pivot system in which the tigeron is inserted. The shockproof system further comprises elastic means arranged to exert on said pivot system at least one axial force

The technical field of the invention is the technical field of fine mechanics.

BACKGROUND TECHNOLOGY

The present invention relates to bearings for timepieces, more particularly of the type for damping shocks. The mechanical watch manufacturers have long since designed numerous devices allowing an axis to absorb the energy resulting from an impact, in particular a side impact, by abutment against a wall of the hole of the base block that it crosses. while allowing a momentary movement of the tigeron before it is brought back to its rest position under the action of a spring.

The Figures 1 and 2 illustrate an inverted double-cone device that is currently used in timepieces on the market.

A support 1, whose base comprises a hole 2 for the passage of the balance shaft 3 terminated by a tigeron 3a, allows positioning a kitten 20 in which are immobilized a pierced stone 4 traversed by the shank 3a and a counter pivot stone 5. The kitten 20 is held in a housing 6 of the support 1 by a spring 10 which comprises in this example radial extensions 9 compressing the The housing 6 comprises two bearing surfaces 7, 7a in the form of inverted cones on which support complementary bearing surfaces 8, 8a of the kitten 20, said bearing surfaces to be executed with very high precision. In the event of an axial impact, the pierced stone 4, the counter pivot stone 5 and the axis of the balance arm move and the spring 10 acts alone to bring the balance shaft 3 back to its initial position. The spring 10 is dimensioned to have a limit of displacement so that beyond this limit, the balance shaft 3 comes into contact with abutments 14 allowing said axis 3 to absorb the shock, which the tigers 3a of Axis 3 can not do without breaking. In case of lateral impact, that is to say when the end of the tigeron imbalances the kitten 20 out of its resting plane, the spring 10 cooperates with the complementary inclined planes 7, 7a; 8, 8a to refocus the kitten 20. Such bearings have for example been sold under the trademark Incabloc®. These springs can be made of phynox or brass and are manufactured by traditional means of cutting.

However, the use of crystalline metals for these springs can cause some problems. Indeed, the crystalline metals are characterized by a low elasticity that can lead to plastic deformation if the shocks are too high. This problem is amplified by the fact that the current springs can not be designed with complex shapes and, therefore, the elastic deformation of the current springs is very close to the elastic limit.

Thus, if an excessive shock is applied to the timepiece, the movement of the stones and the balance can be of great amplitude and, therefore, a plastic deformation that is to say permanent spring can occur. The spring becomes less efficient for damping shocks and refocus the axis of the balance in its rest position because it does not resume its original form and therefore loses elasticity.

This permanent deformation can also occur during handling of said springs during their installation, when they are removed for lubrication operations or during retouching or after-sales operations.

SUMMARY OF THE INVENTION

The object of the invention is to overcome the drawbacks of the prior art by proposing to provide a shock-proof timepiece system that is more efficient and more shock-resistant.

For this purpose, the invention relates to the shockproof timepiece system cited above which is characterized in that the spring is made of at least partially amorphous material.

A first advantage of the present invention is to allow shock systems to better withstand shocks. Indeed, amorphous materials have more interesting elastic characteristics. The elastic limit σ _e is increased, which makes it possible to increase the ratio σ _e / E so that the material sees the stress beyond which it does not return to its initial shape to increase. The spring can then undergo a higher stress before plastically deforming and the workpiece can thus suffer greater shocks without the anti-shock system losing efficiency.

Another advantage of the present invention is to make it possible to produce smaller springs. Indeed, as the amorphous materials are able to withstand higher stresses before deforming plastically, it is possible to make smaller springs without losing resistance.

Advantageous embodiments of this anti-shock system are the subject of dependent claims 2 to 9.

One of the advantages of these embodiments is to make it possible to produce springs of more complex shapes. Indeed, the amorphous metal is very easy to shape and allows the manufacture of complicated shapes with greater precision. This is due to the particular characteristics of the amorphous metal which can soften while remaining amorphous for a certain time in a given temperature range [T _g - T _x ] specific to each alloy. It is thus possible to shape it under a relatively low stress and at a low temperature then allowing the use of a simplified process such as hot forming, while reproducing very precisely fine geometries because the viscosity of the alloy decreases significantly as a function of temperature in said temperature range [T _g - T _x ]. Therefore, it becomes possible to achieve complex and precise springs but simply.

BRIEF DESCRIPTION OF THE FIGURES

• les figures 1 et 2, déjà citées, permettent de représenter de manière schématique un système antichoc de pièce d'horlogerie selon un premier mode de réalisation de l'invention;
• les figures 3 à 5 représentent de manière schématique un système antichoc de pièce d'horlogerie selon un second mode de réalisation de l'invention;

The objects, advantages and characteristics of the anti-shock system according to the present invention will appear more clearly in the following detailed description of at least one embodiment of the invention given solely by way of nonlimiting example and illustrated by the appended drawings in which: :

• the Figures 1 and 2 , already mentioned, allow to schematically represent a shockproof timepiece system according to a first embodiment of the invention;
• the Figures 3 to 5 show schematically a shockproof timepiece system according to a second embodiment of the invention;

DETAILED DESCRIPTION

The present invention proceeds from the general inventive idea of providing a shock absorbing system having greater reliability by using an at least partially amorphous material having at least one metal element. The present invention can take different forms.

The Figures 1 and 2 already mentioned allow to illustrate an anti-shock system according to a first embodiment. This system comprises a support 1, whose base comprises a hole 2 for the passage of the balance shaft 3 terminated by a tigeron 3a, which allows to position a kitten 20 in which are immobilized a pierced stone 4 crossed by the tigeron 3a and a counter pivot stone 5. The support 1 is a part of revolution comprising a circular flange 11. This flange 11 is interrupted in two diametrically opposite locations by an opening 12 so as to create two semi-circular flanges 11a, 11b. The opening 12 is formed partly in the two semi-circular flanges 11a, 11b so as to materialize two returns 13. The kitten 20 is held in a housing 6 of the support 1 by elastic means such as a spring 10 which comprises in this example radial extensions 9 compressing the counter pivot stone 5. The spring 10 is of the axial type and has a form of lyre arranged to bear under the return semicircular rims 11a, 11b. The housing 6 comprises two bearing surfaces 7, 7a in the form of inverted cones on which support complementary bearing surfaces 8, 8a of the kitten 20, said bearing surfaces to be executed with very high accuracy. In the event of an axial impact, the spring 10 acts alone to bring the balance shaft 3 back to its initial position. In case of lateral impact, that is to say when the end of the tigeron imbalances the kitten 20 out of its resting plane, the spring 10 cooperates with the complementary inclined planes 7, 7a; 8, 8a to refocus the kitten 20.

The Figures 3 and 4 illustrate an anti-shock system according to a second embodiment. The bearing comprises a support 101 of circular shape delimiting a housing 106 whose center is pierced with a hole 102 to allow the passage of a balance shaft 103 terminated by a rod 103a.

The support 101 can be either an independent part driven or fixed by any other means in the frame of the watch movement, or be part of another part of the movement, such as a bridge or a plate.

As can be seen, the kitten 120 which supports the pierced stone 104 traversed by the tigeron 103a and the counter-pivot stone 105 is suspended in the housing 106 by a spring 110. The spring 110, shown in perspective at the figure 5 , is of the radial type and is composed of three parts. A first part is constituted by a scalloped peripheral rigid ring 111 which is mounted in force against the wall 106a of the housing 106 by resting on a bead 106b located at the bottom of the housing 106 so as to provide a space allowing a certain axial movement of the spring 110. The second part consists of a central rigid support 113 of generally annular shape. As we see on the figure 5 , the pierced stone 104 is driven into the opening of the support 113 whose inner wall 113a has a number of recesses 117 whose main purpose is to provide a certain elasticity for non-destructive hunting of the pierced stone 104. The third part the spring 110 is constituted by elastic means 112 joining the peripheral ring 111 and the central support 113, said elastic means 112 being chosen to have a reaction force both along the axis of the beam and perpendicularly thereto. The kitten 120 is made of two parts. A first part integrated in the spring 110, is constituted by the central support 113 supporting the pierced stone 104, as described above. A second part is constituted by a cover 123 which is fitted on the central support 113 to immobilize the counter pivot stone 105 on the upper surface 113b. In the example shown, the casing of the cover 123 is obtained by means of tabs 125 extending along the outer wall 113c of the central support 113, through recesses 115 provided in said wall 113c between the attachment points of the arm 114, 116, 118. The areas where the cover 123 does not have tabs 125, bear on the upper bearing surface 113b of the central support 113. To secure the casing of the cover 123 on the central support 113 can for example perform a bonding, welding or riveting.

Of course, the pierced stone 104 and the counter-pivot stone 105 can both be crimped or driven inside the wall 113a of the rigid central support 113, provided of course to give said wall a sufficient height, which will be generally greater than the height of the remainder of the spring 110.

In an example of the figure 5 , the elastic means are formed by three curved arms 114, 116, 118 whose attachment points, respectively to the peripheral ring 111 and the central support 113, are angularly offset by 120 degrees. It is obvious that the elastic function could be ensured with a different number of arms, or with other forms.

Advantageously, the spring 10, 110 is made of an amorphous material or at least partially amorphous. In particular, a material comprising at least one metal element is used. Preferably, the material will be an amorphous metal alloy. It will be understood by at least partially amorphous material that the material is capable of solidifying at least partially in amorphous phase, that is to say that it is able to locally avoid that its atoms do not arrange in crystalline form by means of a sufficient cooling rate.

Indeed, the advantage of these amorphous metal alloys comes from the fact that, during their manufacture, the atoms of these amorphous materials do not arrange according to a particular structure as is the case for crystalline materials. Thus, even if the Young's modulus E of a crystalline metal and an amorphous metal is substantially identical, the elastic limit σ _e is different. An amorphous metal is thus differentiated by an elastic limit σ _e higher than that of the crystalline metal by a factor of about two to three. This allows the amorphous metals to be able to undergo a greater stress before reaching the elastic limit σ _e . Amorphous metals deform plastically more difficultly and break fragile way when the applied stress exceeds the elastic limit. Surprisingly, precious amorphous metals have good mechanical properties. The metal element of said material may then comprise gold, platinum, palladium, rhenium, ruthenium, rhodium, silver, iridium or osmium.

Such springs 10, 110 have the advantage of having higher strength and longevity compared to their crystalline metal counterparts.

Indeed, since the amorphous metal has a higher elastic limit, it is necessary to apply a higher stress to deform plastically. As a result, a spring 10, 110 of amorphous metal has a better resistance to the stresses applied to it during an impact because it will deform elastically over a wider stress interval and return to its initial position once the shock completed. As this stress interval, in which the spring 10, 110 is elastically deformed, is wider for a spring 10, 110 of amorphous metal than for its crystalline metal equivalent, it allows said spring 10, 110 of amorphous metal to withstand constraints that would plastically deform a similar spring of crystalline metal. As soon as the deformation is elastic, these springs 10, 110 are no longer unfolded to return them to their original position and therefore they get tired less which improves their longevity.

Moreover, since the elastic limit of an amorphous metal is higher than that of a crystalline metal by a factor of approximately two to three, making it possible to withstand higher stresses, it is conceivable to reduce the dimensions of said spring 10, 110. Indeed, as a spring 10, 110 shockproof system of amorphous metal can withstand a higher stress without plastically deforming, it is then possible, with equivalent stress, to reduce the dimensions of the spring 10, 110 relative to a similar spring made of a crystalline metal.

To achieve these springs 10, 110, several methods are possible.

First, it is possible to achieve them as in the prior art, that is to say by cutting by wire or water jet or by machining or stamping.

Nevertheless, it can be envisaged to make the spring 10, 110 using the properties of the amorphous metals. Indeed, the amorphous metal has a great ease in shaping allowing the manufacture of parts with complicated shapes with greater precision. This is due to the special characteristics of the amorphous metal which can soften while remaining amorphous for a certain time in a given temperature range [T _g - T _x ] specific to each alloy (for example for an alloy Zr _41.24 Ti _13.77 Cu _12.7 Ni ₁₀ Be _22.7 , T _g = 350 ° C and T _x = 460 ° C). It is thus possible to shape them under a relatively low stress and at a low temperature then allowing the use of a simplified process such as hot forming. The use of such a material also makes it possible to reproduce very precisely fine geometries because the viscosity of the alloy decreases strongly as a function of the temperature in the temperature range [T _g - T _x ] and the alloy marries so all the details of the mold. For example, for a platinum-based material, the shaping is done around 300 ° C for a viscosity up to 10 ³ Pa.s for a stress of 1 MPa, instead of a viscosity of 10 ¹² Pa. at the temperature T _g .

1. a) Chauffage des pinces ou matrices formant le moule ayant la forme négative du ressort 10, 110 jusqu'à une température choisie,
2. b) Introduction de la préforme en métal amorphe entre les matrices chaudes,
3. c) Application d'une force de fermeture sur les matrices afin de répliquer la géométrie de ces dernières sur la préforme en métal amorphe,
4. d) Attente durant un temps maximal choisi,
5. e) Ouverture des matrices,
6. f) Refroidissement rapide du ressort en dessous de T_g de sorte que le matériau garde sa phase au moins partiellement amorphe, et
7. g) Sortie du ressort 10, 110 des matrices.

One method used is the hot forming of an amorphous preform. This preform is obtained by melting in a furnace the metallic elements constituting the amorphous alloy. This fusion is done under a controlled atmosphere with the aim of obtaining contamination of the alloy with impurities as low as possible. Once these elements are melted, they are cast as a semi-finished product, then cooled rapidly to maintain the at least partially amorphous state. Once the preform obtained, the hot forming is performed in order to obtain a final piece. This hot forming is carried out by pressing in a temperature range between the glass transition temperature T _g of the amorphous material and the crystallization temperature T _{x of} said material. amorphous for a determined time to maintain a totally or partially amorphous structure. The goal is then to retain the characteristic elastic properties of amorphous metals. The different stages of definitive shaping of the spring 10, 110 are then:

1. a) heating the pliers or dies forming the mold having the negative shape of the spring 10, 110 to a chosen temperature,
2. b) Introduction of the amorphous metal preform between the hot matrices,
3. c) applying a closing force on the matrices in order to replicate the geometry of the latter on the amorphous metal preform,
4. d) Waiting for a chosen maximum time,
5. e) Opening of the matrices,
6. f) rapid cooling of the spring below T _g so that the material keeps its phase at least partially amorphous, and
7. g) Spring output 10, 110 of the dies.

The hot forming of the metal or amorphous alloy thus makes it possible to produce complex and precise parts but also a good reproducibility of the part which is a consequent advantage for the mass production such as that of the damping system springs.

According to a variant of this method, the casting is used. This process involves casting the alloy obtained by melting the metal elements in a mold having the shape of the final piece. Once the mold filled, it is cooled rapidly to a temperature below T _g to prevent crystallization of the alloy and thus obtain a spring amorphous or partially amorphous metal. The advantage of casting an amorphous metal with respect to the casting of a crystalline metal is to be more precise. The solidification shrinkage, for an amorphous metal, is very low, less than 1% relative to that of the crystalline metals which is 5 to 7%.

It will be understood that various modifications and / or improvements and / or combinations obvious to those skilled in the art can be made to the various embodiments of the invention set out above without departing from the scope of the invention defined by the appended claims.

It can also be understood that the pivot-facing stone 5, 105 comprises a conical recess so that the end of the taper 3a, 103a can be inserted therein to have a difference in amplitude between the different positions of the watch minimized. .

Claims (9)

Shock absorber bearing for an axis (3, 103) of a mobile of a timepiece, said axis comprising a tigeron (3a, 103a), said bearing comprising a support (1, 101) provided with a housing (6, 106) adapted to receive a pivot system in which the beam (3a, 103a) is inserted, said bearing further comprising elastic means (10, 110) arranged to exert on said pivot system at least one axial force, characterized in that the elastic means are made of at least partially amorphous material. Shock absorber bearing according to claim 1, characterized in that said elastic means (10, 110) are made of totally amorphous material. Shock absorber bearing according to claims 1 or 2, characterized in that the amorphous material comprises at least one metal element. Shock absorbing bearing according to claim 3, characterized in that said at least one metallic element is of the precious type or an alloy comprising such a precious metal element. A shock absorbing bearing according to claim 4, characterized in that said precious metal element comprises gold, platinum, palladium, rhenium, ruthenium, rhodium, silver, iridium or aluminum. 'osmium. Shock absorber bearing according to one of the preceding claims, characterized in that the pivot system comprises a kitten (20) arranged in the housing (6) and supporting a pierced stone (4) traversed by the tigeron (3a) and a stone against the pivot (5) and in that the support (1) is a piece of revolution comprising a circular flange interrupted in two diametrically opposite locations by an opening (12) so as to create two semi-circular flanges (11a, 11b) , said opening being formed partly in the two semi-circular flanges so as to materialize two returns (13) under which the elastic means (10) support to maintain the kitten in the housing (6) of the support (1). Shock absorber bearing according to claim 6, characterized in that the elastic means (10) are a spring (1) having a lyre shape. Shock absorbing bearing according to one of claims 1 to 5, characterized in that the housing (106) is arranged to receive a spring (110) with axial and radial deformation and a kitten (120) supporting a pierced stone (104) traversed by the tigeron (103a) and a counter-pivoting stone (105), said elastic means (110) being formed by a rigid peripheral ring (111) driven into the housing (6) and connected by elastic means (112) to a rigid central support (113) substantially annular and in that the kitten (120) holding the two stones (104, 105) is suspended in the center of the spring (110). Shock absorbing bearing according to claim 8, characterized in that the kitten (120) is formed of two parts (113, 123), one being constituted by the central rigid support (113) whose inner wall (113a) maintains the pierced stone (104), the other being formed by a cap (123) which is secured to the rigid central support (13) to block the counter-pivot stone (15) on the upper bearing surface (113b) of the central support (113); ).

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