EP2585880A1

EP2585880A1 - Timepiece dial feet

Info

Publication number: EP2585880A1
Application number: EP11726429.1A
Authority: EP
Inventors: Frédéric Jeanrenaud; Yves Winkler
Original assignee: Swatch Group Research and Development SA
Current assignee: Swatch Group Research and Development SA
Priority date: 2010-06-22
Filing date: 2011-06-21
Publication date: 2013-05-01
Also published as: JP2013529777A; US20130148484A1; JP5457608B2; CN103038713A; EP2400354A1; WO2011161080A1

Abstract

The invention relates to a timepiece dial (7). This dial has at least one foot (9). The food is fixed to said dial and used to fix said dial to said timepiece. The foot is produced from an at least partially amorphous metal alloy.

Description

P R O D E R A T IO N D E R A T ION

The present invention relates to a timepiece dial foot, said one foot being fixed on said dial and used to fix said dial to the timepiece.

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

BACKGROUND TECHNOLOGY

It is known that timepieces comprise a movement on which is fixed a dial. This dial includes feet which are used, on the one hand, as a geometrical reference in the cycle of manufacture of the dial and, on the other hand, to fix said dial to the movement.

These feet are made of crystalline metal such as steel, brass or gold. These feet are assembled by spot welding. They very often have a smaller diameter in the area in contact with the base of the dial, this for three main reasons. First, it prevents a weld overflow from properly squeezing the dial against movement. Second, it ensures, in case of impact on the foot, the plastic deformation is located in this narrowed area. The foot can then be straightened while maintaining good accuracy on the large diameter area that will adjust to the movement. Finally, this diameter of the smaller foot in the area in contact with the base of the dial serves to prevent deformation of the base of the dial in case of impact on a foot by a deliberate and controlled weakening of said foot. However, the problems of the current feet are related to the mechanical properties characteristic of crystalline metals that is to say a very limited elastic deformation. Indeed, each material is characterized by its Young's modulus E also called modulus of elasticity (generally expressed in GPa), characterizing its resistance to deformation. Each material is also characterized by its elastic limit σ _θ (generally expressed in GPa) which represents the stress beyond which the material deforms plastically. It is then possible, for given dimensions, to compare the materials by establishing for each the ratio of their elastic limit on their Young's modulus a JE, said ratio being representative of the elastic deformation of each material. Thus, the higher the ratio, the greater the elastic deformation of the material. Typically, for an alloy of the Cu-Be type, the Young's modulus E is equal to 130 GPa and the elasticity limit σ _θ is equal to 1 GPa, which gives an oJE ratio of the order of 0.007 cm. that is to say, weak.

Therefore, when handling errors, if the deformation applied to the feet is too high, the resulting stress may exceed the elastic limit of the alloy and therefore cause permanent plastic deformation. Since they are often used as a geometric reference in the dial manufacturing cycle, it is necessary to unfold the feet to reposition them. A rupture of said foot can then occur if the stress is too high or by fatigue if the constraints are successive.

SUMMARY OF THE INVENTION

The object of the invention is to overcome the drawbacks of the prior art by proposing to provide a metal dial foot which is more resistant to shocks.

For this purpose, the invention relates to a timepiece dial comprising at least one foot. Said at least one foot is attached to said dial and is used to fix said dial to said timepiece, said at least one foot and the dial are made of an at least partially amorphous metal alloy.

A first advantage of the present invention is to allow the dial feet to better withstand shocks. Indeed, amorphous metals have more interesting elastic characteristics. The elastic limit σ _θ is increased, which makes it possible to increase the ratio σ _θ / Ε so that the material sees the stress beyond which it does not return to its initial shape to increase. If the foot deforms plastically more difficult, it is no longer necessary to unfold the foot to return it to its original position. If the foot is more resistant, it is also less weakened by successive folds and unfoldings and thus the foot has a longer life.

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

The present invention also relates to a timepiece dial comprising at least one foot, said dial is fixed on a support on which said at least one foot is fixed to fix said dial to said timepiece. Said at least one foot and the support are made of an at least partially amorphous metal alloy.

Advantageous embodiments of this dial are the subject of the dependent claims.

In a first advantageous embodiment, said at least one foot and the dial are one and the same piece.

In a second advantageous embodiment, said at least one foot and the support are one and the same piece. In a third advantageous embodiment, said at least one foot is attached to the dial.

In a fourth advantageous embodiment, said at least one foot is attached to the support.

In another advantageous embodiment, said material is totally amorphous

In another advantageous embodiment, the dial comprises at least one recess in which said at least one foot is fixed.

In another advantageous embodiment, the support, on which the dial is fixed, comprises at least one recess in which said at least one foot is fixed.

In another advantageous embodiment, the flanks of said at least one recess comprise reliefs in order to improve the fixing of said at least one foot in said at least one recess.

In another advantageous embodiment, the reliefs arranged on the sides of said at least one recess form a tapping.

In another advantageous embodiment, said at least one recess has a constant section.

In another advantageous embodiment, the bottom of said at least one recess has the largest section.

In another advantageous embodiment, the section increases linearly approaching the bottom of said at least one recess.

In another advantageous embodiment, said foot comprises, in its area of contact with the dial or the support, a smaller diameter.

In another advantageous embodiment, said foot comprises, in its zone of contact with the dial or the support, a larger diameter low and in the area contiguous to this contact area, an even smaller diameter.

In another advantageous embodiment, said at least one metallic element is a precious material or an alloy based on such a precious material, said precious material being chosen from the group formed by gold, platinum, palladium, rhenium, ruthenium, rhodium, silver, iridium or osmium.

One of the advantages of these embodiments is to allow the feet to be made directly with the dial in the case where the feet and the dial form a single piece. 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 realize the dial and feet in one piece and accurately.

BRIEF DESCRIPTION OF THE FIGURES

The purposes, advantages and characteristics of the dial foot 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 non-limiting example and illustrated by the accompanying drawings on which : - Figure 1 schematically shows a first embodiment of the invention;

- Figures 2 and 3 schematically show sectional views of dials attached to their movement;

- Figure 4 schematically shows a second embodiment of the invention;

FIGS. 5 to 7 schematically represent alternatives to the second embodiment of the invention, and

- Figure 8 schematically shows a third embodiment of the invention.

- Figure 9 schematically shows a particular variant of the first embodiment of the invention.

DETAILED DESCRIPTION FIG. 1 shows a timepiece 1 comprising a housing 2. In this housing 2 is arranged, as can be seen in FIG. 2, a movement 5 on which is fixed a dial 7. This dial 7 is fixed to movement 5 by means of feet 9 fixed to said dial 7 and engaged in orifices 1 1 of the movement 5. The fixing of the dial 7 to the movement 5 is ensured by fastening means 13. These fastening means 13 consist, for example, of a screw 15 engaged in a threaded hole transverse to the orifice 1 1 and opening therein. This screw then clamps said foot 9 so as to hold it fixed in the orifice 1 January. Of course, it can be understood that, according to a variant shown in Figure 3, the dial 7 is attached to a support 17 on which the feet 9 are fixed as is the case for a dial 7 enamel glued to a support 17 Brass. Advantageously, the feet 9 are 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 the amorphous phase, that is to say that it is capable of losing at least locally all of its crystalline structure.

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 identical, the elastic limit σ _θ is different. An amorphous metal is thus distinguished by an elastic limit σ _θ higher than that of the crystalline metal by a factor of approximately two to three. This allows the amorphous metals to be able to undergo a greater stress before reaching the elastic limit σ _θ . Amorphous metals plastically deform more difficultly and break brittle 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 feet 9 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 foot 9 made 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 is complete. Like this interval of constraints, in which the foot 9 is elastically deformed, is wider for a foot 9 of amorphous metal than for its crystalline metal equivalent, it allows said foot 9 amorphous metal to withstand stresses that plastically deform said foot 9 crystalline metal . As soon as the deformation is elastic, these feet 9 are no longer unfolded to return them to their original position and therefore they become weaker, which improves their longevity.

Moreover, since the elastic limit of an amorphous metal is greater 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 foot. 9. Indeed, as a foot 9 of dial 7 of amorphous metal can withstand a higher stress without deforming plastically, it is then possible, at equivalent stress, to reduce the dimensions of the foot 9 relative to a crystalline metal. As the feet 9 are inserted into the openings 1 1 of the movement 5, the fact of decreasing the dimensions of the feet 9 makes it possible to reduce the dimensions of the orifices 1 1.

However, the fact of decreasing the size of the feet 9 increases the risk of deformation of the dial 7, especially if the foot 9 has a smaller diameter in the area in contact 10, 12 with the base of the dial 7 or the support 17. According to FIG. a particular variant, the foot 9 has an even smaller diameter in the contiguous zone 14 to the contact zone 10, 12 as visible in Figure 9. This allows to separate the functions. The contact zone 10, 12 is used to prevent the overflow of the weld prevents the dial 7 from being correctly pressed onto the movement 5. The zone 14 is used to weaken the foot 9 so that it deforms, elastically or plastically, at this zone 14.

To realize and fix these feet 9 to the dial 7, several methods are possible. In a first embodiment, it may be envisaged to make the feet 9 and then to fix them to the dial 7. The feet 9 may be made by machining, but it is possible to achieve them using the properties of 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 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 (for example for a Zr 41 .2 _4 alloy. Ti 13.77 Cu 12. -7, Ni 10 E3e 22.7, T _q ^y = 350 ° C and T _X = 460 ° C). It is thus ^r p ossible to the shaping at a relatively low and a low temperature constraint allowing then the use of a simplified method 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 negative. 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. s at the temperature Tg.

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 made under a controlled atmosphere with the aim of obtaining as low a contamination of the oxygen alloy as possible. Once these elements are melted, they are cast as a semi-finished product, such as for example a cylinder of dimensions close to those of the dial feet 9, and then rapidly cooled in order to maintain the at least partially amorphous state or phase. . 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 range of temperatures between glass transition temperature T _g of the amorphous material and the crystallization temperature T _{x of} said amorphous material for a predetermined 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 final shaping of the foot 9 of dial 7 are then:

a) Heating the matrices having the negative form of the foot 9 to a chosen temperature,

b) Introduction of the amorphous metal preform between the hot matrices,

c) applying a closing force on the matrices in order to replicate the geometry of the latter on the amorphous metal preform, d) Waiting for a chosen maximum time,

e) Opening of the matrices,

f) Fast cooling of the foot 9 below T _g so that the material keeps its phase at least partially amorphous, and

g) Release of the foot 9 of the matrices.

According to a variant of this first embodiment, a casting process 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 foot 9 of 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 is very low for an amorphous metal, less than 1% relative to that of the crystalline metals which is 5 to 7%. After completion of said feet 9, they are fixed to said dial 7 by welding. Preferably, said feet 9 are arranged as the feet 9 according to the prior art, that is to say having a smaller diameter in the area in contact 12 with the base of the dial 7 to prevent the Overflow of the weld prevents the dial 7 from being pressed correctly on the movement 5. Thus, in the event of impact on the foot 9, the plastic deformation is localized in this narrowed zone in order to preserve the dial 7. Nevertheless, it is also possible to these feet 9, made by hot forming or by casting, to be removed in recesses 19 previously made on the dial 7. Of course, in the case where the dial 7 is attached to a support 17, the feet 9 will be welded to the support or chased in recesses 19 made on the support 17.

According to a second embodiment shown in Figure 4, it is expected to overmould directly feet 9 at the dial 7 during the production of said feet 9. For this, the hot forming technique is used. We begin by making recesses 19 on the dial 7 at the places where it is desired to place said feet 9. These recesses 19 have a depth not exceeding half the thickness of the dial 7, so as not to weaken too much. said dial 7. Then the dial 7 is placed between the matrices and the steps a) to g) previously described are made so that the amorphous metal is overmolded directly into the recesses 19 and that said feet 9 are formed. The feet 9 are held on the dial 7 by the flanks 25 of the recesses 19 when said recesses 19 have a constant section. The friction between these flanks 25 and the amorphous metal then prevent the feet 9 from coming off.

In order to improve the holding of the feet 9 in the recesses 19, holding means 23 are arranged. These holding means 23 can take various forms. In a first alternative visible in Figure 5, these holding means 23 may be the flanks 25 of the recesses 19 which are arranged to have a non-constant section. Preferably, the bottom section 21 of the recess 19 is larger than that at the surface of the dial 7. It can also be expected that the section expands steadily when approaching the bottom 21 of the 19. This arrangement of the section of the recesses 19 in which are fixed the feet 9 allows a natural retention of said feet 9 in said recesses 19 without requiring welding or gluing.

In a second alternative visible in FIG. 6, it may be provided that the flanks 25 of the recesses 19 comprise reliefs 27. These reliefs 27 may be in the form of recesses and / or projections arranged on the flanks 25 of each recess 19. These recesses and / or protrusions can be arranged to form a tapping allowing the screwing and unscrewing of the feet 9. These reliefs 27 exploit the characteristics of the amorphous metal to be able to soften while remaining amorphous in a temperature range [T _g - T _x ] given specific to each alloy thus marrying all the details of the negative. The amorphous metal then inserts into the recesses of the flanks 25 thus ensuring a better hold of the foot 9 in the recess 19. It will be understood that, in the case where the dial 7 is attached to a support 17, the recesses 19, in which are made the feet 9 and whose flanks 25 comprise reliefs 27, are formed on the support 17 as shown in Figure 7.

A third embodiment, visible in FIG. 8, consists in producing the dial 7 and the feet 9 in one and the same piece, that is to say that the dial 7 and the feet 9 are made of amorphous metal simultaneously. . For this purpose, the dies constituting the mold form the complementary impression of the part composed of the dial 7 and the feet 9. It will be understood that, in the case of a dial 7 attached to a support 17, the support 17 and the feet 9 are one and the same room. This part is then cast or hot-formed amorphous metal. The advantage is to have in the first place a perfect reproducibility of the process since the dials 7 associated with their feet 9 are all made in the same mold. In addition, this method has the advantage of being simple and not having a step of fixing the feet 9 with the risk of bending the feet 9 or deforming the dial 7.

It may also be provided that the dial 7 and the feet 9 are made of amorphous metal or metal alloy at least partially amorphous but separately. It is understood that the feet 9 and the dial 7 are separate pieces and that the feet 9 are then reported on the dial 7. This is also valid in the case where the dial 7 is fixed on a support 17 and that the support 17 is amorphous metal. The feet 9 and the support 17 are different pieces of amorphous metal. The feet 9 are attached to said support 17.

The feet 9 are, in the case where they are reported to the dial 7 or the support 17, glued or welded or fixed with any possible method.

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.

Claims

R EV EN DI CATI O NS

1. Timepiece dial comprising at least one foot (9), said at least one foot being fixed on said dial (7) and used to fix said dial to said timepiece, characterized in that said at least one foot (9) and the dial (7) are made of an at least partially amorphous metal alloy.

2. A timepiece dial comprising at least one foot (9), said dial (7) is fixed on a support (17) on which said at least one foot (9) is fixed to fix said dial to said workpiece. watchmaking, characterized in that said at least one foot (9) and the support (17) are made of an at least partially amorphous metal alloy.

3. Timepiece dial according to claim 1, characterized in that said at least one foot (9) and the dial (7) are one and the same piece.

4. Timepiece dial according to claim 2, characterized in that said at least one foot (9) and the support (17) are one and the same piece.

5. Timepiece dial according to claim 1, characterized in that said at least one foot (9) is attached to the dial (7).

6. Timepiece dial according to claim 2, characterized in that said at least one foot (9) is attached to the support (17).

7. Dial according to claims 1 or 2, characterized in that said material is totally amorphous

8. Dial according to claim 1, characterized in that the dial comprises at least one recess (19) wherein said at least one foot is fixed.

9. Dial according to claim 2, characterized in that the support (17), on which the dial (7) is fixed, comprises at least one recess (19) wherein said at least one foot (9) is fixed.

10. Dial according to claims 8 or 9, characterized in that the flanks (25) of said at least one recess (19) comprise reliefs (27) to improve the attachment of said at least one foot in said at least one recess .

1 1. Dial according to claim 10, characterized in that the reliefs arranged on the flanks (25) of said at least one recess form a tapping.

12. Dial according to one of claims 8 to 10, characterized in that said at least one recess (19) has a constant section.

13. Dial according to one of claims 8 to 10, characterized in that the bottom (21) of said at least one recess (19) has the largest section.

14. Dial according to claim 13, characterized in that the section increases linearly approaching the bottom (21) of said at least one recess (19).

15. Dial according to one of the preceding claims, characterized in that said foot (9) comprises, in its contact area (10) with the dial (7) or the support (17), a smaller diameter.

16. Dial according to one of claims 1 to 15, characterized in that said foot (9) comprises, in its contact zone (10) with the dial or the support, a smaller diameter and in the contiguous zone (14). ) at this contact zone, an even smaller diameter.

17. Dial according to one of the preceding claims, characterized in that said metal alloy comprises at least one metal element which is a precious material or an alloy based on such a precious material, said precious material being selected in the group formed by gold, platinum, palladium, rhenium, ruthenium, rhodium, silver, iridium or osmium.