EP2952971B1 - Pallet for escapement mechanism of a watch movement - Google Patents

Description

The present invention relates to an anchor for an escapement mechanism of a watch movement, in particular an escapement of Swiss anchor type.

An anchor for a clock escapement mechanism is described in the application for EP2320280 . In order to optimize the respective functions of the fork and the rod, the fork of the anchor is an insert, offset from the plane of the rod and the stinger. The fork is fixed to the rod by means of a tenon driven into respective holes made in the fork and the rod, the tenon also realizing the spacing between the plane of the rod and the fork. This spacing along an axis perpendicular to the general plane of the anchor must be perfectly mastered during the manufacture of the anchor and in particular during the assembly of the dart on the rod to obtain optimum operation of the mechanism in which the anchor is integrated. As an indication, the manufacturing tolerance for achieving this spacing is typically of the order of ± 20 microns. In conventional practice, the tenons are metal parts of very small diameters made by bar turning. Typically these tenons are made by bar turning from a steel bar, brass or nickel silver. These tenons conventionally have a diameter of about 0.24 mm.

A current problem with the tenons turned is that they have on their front faces "nipples" resulting from the cutting operation during their manufacture. Indeed, when the chisel separates the tenon of the material bar at the end of the bar turning operation, the tenon is detaches from the bar and a small cone of material remains on the end surfaces. This small cone of material called "nipple" is not desired because it does not allow to form a clean end face and perpendicular to the cylinder that can be used as a reference to perform an assembly operation of the dart on the rod with a spacing specific. These tenons can not be hunted "flush" with the rod. In addition, the assembly of these tenons is difficult to achieve because they tend, given their small size to deform during assembly resulting in a loss of final position of the range relative to the sting which has a negative impact on the performance of the exhaust system.

We also know the patent CH703794 which describes a pallet anchor in which the body of the anchor and the stinger are each formed by electroforming. The stinger includes a portion forming a main body of the stinger and a fastening portion on the body of the anchor. The assembly of the dart on the body of the anchor is ensured by driving the attachment portion of the dart in an opening of the body of the dart provided for this purpose.

An object of the invention is to provide an anchor for a precise and reliable watch exhaust mechanism over a long period of use.

Another object of the invention is to provide a robust anchor that is economical to manufacture.

An object of the invention is also to provide an anchor for a clock escapement mechanism for optimizing the functions of the fork, the rod and the pallets of the anchor.

Yet another object of the invention is to provide an anchor for a clockwork escapement mechanism in which the spacing between the plane of the rod and the stinger along an axis perpendicular to the general plane of the anchor is perfectly controlled.

Objects of the invention are provided by an anchor for a watch exhaust mechanism according to claim 1. The dependent claims describe advantageous aspects of the invention.

In the present invention, an anchor for an escape mechanism for a watch movement includes a fork portion, a pallet support portion, pallets mounted on the pallet support portion, and a batten interconnecting the pallet portion. support pallets at the fork portion. The fork portion includes a fork, a dart and a tenon. The batten and the pallet support portion are integral and form a monolithic main body of the anchor, and the fork is an insert attached to the main body by means of the peeled stud and / or assembled in a fixing hole in the body main and a fixing hole in the fork. The reported fork is spaced from the main body. The post is made of a material that does not have a plastic field under stress.

The surfaces of the tenon engaging the fixing holes comprise a surface finish obtained by grinding and / or polishing.

According to one embodiment the tenon has a hardness greater than or equal to 850HV. The material of the tenon may be a metal matrix composite material, a ceramic, a crystalline or amorphous metal, treated or not to achieve a hardness greater than or equal to 850HV.

The tenon is preferably made from a material selected from the group consisting of sapphire, ruby, aluminum oxide, zirconium oxide, tungsten carbide, monocrystalline corundum, or polycrystalline, silicon nitride, silicon carbide, hardened steel, tungsten carbide in a cobalt matrix and amorphous metal alloys. As amorphous alloys, iron-nickel-based amorphous alloys and cobalt-nickel-based amorphous alloys, typically the Fe52Ni22Nb6VB15 alloy or the Co50Ni22Nb8V5B15 alloy, will be chosen in particular.

Advantageously, the tenon has a generally cylindrical shape having at each of its ends a front face extending perpendicularly to the longitudinal axis of the tenon. The end faces have a perpendicularity defect with respect to the axis less than 1 °, and preferably the surfaces of the post engaging the fixing holes and the end faces comprise a surface finish obtained by grinding.

In one embodiment, the fork is made of a material selected from the group of materials including silicon, silicon nitride, silicon carbide, nickel, nickel-phosphorus alloys (especially alloy NiP12), and amorphous alloys, especially iron-nickel based alloys and amorphous cobalt-nickel alloys, typically the Fe52Ni22Nb6VB15 alloy or the Co50Ni22Nb8V5B15 alloy.

In one embodiment, the main body is made of a material selected from the group of materials including steel, nickel silver, silicon, silicon nitride, silicon carbide, nickel, nickel alloys -Phosphorus, (in particular NiP12), and amorphous alloys, in particular alloys based on iron-nickel, amorphous alloys based on cobalt-nickel, and amorphous alloys based on zirconium typically a Fe52Ni22Nb6VB15 alloy or an alloy Co50Ni22Nb8V5B15 or an alloy Zr65.7Cu15.6Ni11.7Al3.7Ti3.3.

In one embodiment, the main body includes a spacer tube formed around the attachment hole and configured to define the spacing between the fork and the main body.

In another embodiment, the fork includes a spacer tube formed around the attachment hole and configured to define the spacing between the fork and the main body.

The invention also relates to a watch exhaust mechanism comprising an anchor as described, and a watch movement comprising an escape mechanism.

• La Fig. 1a est une vue en perspective schématique d'une ancre pour un mécanisme d'échappement de type suisse, selon une forme d'exécution de l'invention ;
• La Fig. 1b est une vue plane de la forme d'exécution de la figure 1a ;
• La Fig. 1c est une vue éclatée en perspective de la forme d'exécution de la figure 1a ;
• La Fig. 2a est une vue en perspective schématique d'une ancre pour un mécanisme d'échappement de type suisse, selon une deuxième forme d'exécution de l'invention ;
• La Fig. 2b est une vue en perspective d'un corps de l'ancre en cours de fabrication de la figure 2a ;
• La Fig. 2c est une vue éclatée en perspective de la forme d'exécution de la figure 2a ;
• La Fig. 3 est une vue schématique en coupe d'une ancre pour un mécanisme d'échappement de type suisse, selon une troisième forme d'exécution de l'invention.

Other objects and advantageous aspects of the invention will appear on reading the claims, as well as on the following detailed description of the embodiments and the accompanying drawings, in which:

• The Fig. 1a is a schematic perspective view of an anchor for a Swiss type escapement mechanism, according to one embodiment of the invention;
• The Fig. 1b is a plan view of the embodiment of the figure 1a ;
• The Fig. 1 C is an exploded view in perspective of the form of execution of the figure 1a ;
• The Fig. 2a is a schematic perspective view of an anchor for a Swiss type escapement mechanism, according to a second embodiment of the invention;
• The Fig. 2b is a perspective view of a body of the anchor being manufactured from the figure 2a ;
• The Fig. 2c is an exploded view in perspective of the form of execution of the figure 2a ;
• The Fig. 3 is a schematic sectional view of an anchor for a Swiss type escapement mechanism, according to a third embodiment of the invention.

Referring to the figures, an anchor 2 for a Swiss type escapement mechanism for a watch movement comprises a fork portion 4, a support portion of the pallets 7, pallets 6, and a rod 8 interconnecting the support portion. pallets at the fork part. The anchor is rotatably mounted in the movement (not shown) by means of a pivot 10.

The vanes 6 cooperate with the teeth of an escape wheel (not shown) of an exhaust mechanism which is connected to a power source providing a rotational torque to the escape wheel. One of the pallets constitutes the entry pallet and the other constitutes the exit pallet, that according to the alternation of rotation of the anchor.

The fork portion 4 comprises a fork 12, a stinger 14 and a post 16. The fork 12 comprises a first horn 22a and a second horn 22b. The fork conventionally engages a peg secured to an oscillating wheel of a pendulum.

In a direction of rotation of the balance, the first horn 22a functions as input horn and the second horn 22b as output horn. In the other direction of rotation, the functions of the first and second horns are reversed. The stinger prevents the anchor from pivoting so that the fork passes the wrong side of the ankle during a shock. The illustrated mechanism corresponds to a classic Swiss-anchor escapement as described in more detail on pages 99 to 128 of the book entitled "Theory of Watchmaking" ISBN 2-940025-10-X .
As this principle is well known, the conventional elements and their operation will not be described in more detail in the present application.

The rod and support arms of the pallets are integral and form a main body 3 of the anchor 2.

The fork 12 is an insert attached to the main body 3 by means of the post 16 driven into a fixing hole 18 formed in the main body. The spacing of the fork of the main body of the anchor makes it possible to optimize the function of the fork, in particular in order to reduce the losses due to the friction between the fork and the ankle, without limiting the choice of the material and the process of manufacture for the realization of the rest of the anchor - stick, dart and support of the pallets. The reported fork also allows to shift the plane of the fork relative to the pallets, which allows for a compact exhaust device.

The fork can be made of different materials including silicon, silicon nitride, and silicon carbide, silicon coated with a layer of silicon oxide, silicon coated with a diamond layer, by various methods of fabrication including photolithography, and DRIE (Deep Reactive-Ion Etching) type etching a wafer of one of these materials. The fork can also be made of nickel or phosphorus nickel (NiP, NiP12), for example by a LIGA type electroforming process (Roentgenlithographie, Galvanoformung, Abformung). This fork can also be made of metal or a metal alloy in crystalline or amorphous form by mechanical shaping. The amorphous alloys, based on iron-nickel, for example the alloy Fe52Ni22Nb6VB15, amorphous alloys based on cobalt-nickel, for example the alloy Co50Ni22Nb8V5B15 as well as the amorphous alloys based on zirconium, for example the alloy Zr65 .7Cu15.6Ni11.7Al3.7Ti3.3 are particularly suitable. The fork could also be made of an alloy of copper and beryllium, an alloy of austenitic cobalt, austenitic stainless steel or steel type HIS (High Interstitial Steels).

The main body 3 of the anchor 2 can also be made of different materials including silicon, silicon nitride, and silicon carbide, silicon coated with a layer of silicon oxide, silicon coated with a layer of diamond by various manufacturing processes including photolithography processes, and DRIE (Deep Reactive-Ion Etching) etching. The main body 3 may also be made of titanium, aluminum, magnesium, steel, typically austenitic stainless steel or steel type HIS (High Interstitials Steels), copper alloy (typically nickel silver or beryllium copper ), an austenitic cobalt alloy or an austenitic nickel alloy or an amorphous alloy. The amorphous alloys, based on iron-nickel, for example the alloy Fe52Ni22Nb6VB15, amorphous alloys based on cobalt-nickel, for example the alloy Co50Ni22Nb8V5B15 as well as the amorphous alloys based on zirconium, for example the alloy Zr65 .7Cu15.6Ni11.7Al3.7Ti3.3 are particularly suitable.

In a first preferred embodiment, the main body 3 and the fork 12 are made by a phosphor nickel LIGA type electroforming process, typically made of NiP12.

In a second preferred embodiment, the main body 3 is made by a LIGA process typically in nickel phosphorus or nickel and the range 12 is made by etching typically from a silicon wafer.

The tenon 16 is made of a material having no or substantially no plastic field under stress and the tenon preferably has a hardness greater than or equal to 850HV. Typically the tenon is made from a material selected from the group consisting of sapphire, ruby, aluminum oxide, zirconium oxide, tungsten carbide monocrystalline corundum, or polycrystalline, the nitride of silicon, silicon carbide, hardened steel, tungsten carbide in a cobalt matrix, amorphous alloys, especially iron-nickel based alloys and amorphous cobalt-nickel alloys.

As an amorphous alloy, a Fe52Ni22Nb6VB15 alloy or a Co50Ni22Nb8V5B15 alloy may be used.

In an advantageous embodiment, the post has a generally cylindrical shape having at each of its ends a front face extending perpendicularly to its longitudinal axis and is made of ruby, comprising a finish by grinding to obtain precise dimensions with tolerances less than circularity ± 1 μm, diameter ± 1.5 μm, length ± 7 μm. In particular, the front faces of the tenon have a perpendicularity defect of less than 1 °.

The hardness of the tenon material greater than or equal to 850HV makes it possible to produce the tenon with a very precise diameter and perfectly perpendicular front faces between them and thus to carry out a driving operation of the tenon in the orifice of the fork and the body 3 by decreasing the risk of breakage of these components. The stability of the fixation and the Positioning accuracy between the post and these components is also improved over conventional assemblies.

In the form of execution according to Figures 1a to 1c , the main body 3 and the fork 10 are manufactured by a LIGA electroforming process, this is a very economical manufacturing process for small parts, while being very precise in the direction of the thickness of the electroformed layer as well as in the general plane of the main body.

• Les géométries sont réalisées avec la précision des procédés photolithographiques utilisés classiquement pour la réalisation des moules pour l'opération d'électroformage.
• La fabrication du tenon en rubis est maîtrisée : les tolérances sur le diamètre sont très fines typiquement de l'ordre de (± 1.5 µm).
• Le tenon en rubis n'a pas de téton de coupe sur ses faces d'extrémités qui sont parfaitement planes et parallèles entre elles contrairement aux tenons décolletés.
• Selon la géométrie du tenon (avec un plat ou non) et la forme des orifices 18, 20, l'indexage des cornes de la fourchette rapportée relative au dard est garanti par l'assemblage.
• L'assemblage ne nécessite pas de colle.
• La précision en hauteur garantie par ce concept garanti des tolérances deux à trois fois plus serrées qu'un procédé conventionnel d'assemblage de la fourchette sur le corps principal.
• L'utilisation de la fourchette réalisée par un procédé d'électroformage du type LIGA permet un assemblage par chassage, ce qui permet de régler les hauteurs indépendamment des tolérances de composants, ce qui évite la production d'un tenon avec une collerette qui assure la distance entre la fourchette et le dard.

The advantages of this first variant are the following:

• The geometries are made with the precision of the photolithographic processes conventionally used for producing the molds for the electroforming operation.
• The manufacture of the ruby tenon is controlled: the tolerances on the diameter are very fine typically of the order of (± 1.5 μm).
• The ruby tenon has no cutting nipple on its end faces which are perfectly flat and parallel to each other unlike the tenons décolletés.
• Depending on the geometry of the tenon (with a flat or not) and the shape of the orifices 18, 20, the indexing of the horns of the fork relative to the dart is guaranteed by the assembly.
• The assembly does not require glue.
• The height accuracy guaranteed by this concept guarantees tolerances two to three times tighter than a conventional method of assembly of the fork on the main body.
• The use of the fork made by a LIGA-type electroforming process allows for assembly by driving, which makes it possible to adjust the heights independently of the tolerances of components, which avoids the production of a tenon with a collar that ensures the distance between the fork and the stinger.

In the second embodiment, according to Figures 2a to 2c , the main body 3 is manufactured by a LIGA type electroforming process. then machined by mechanical recovery to achieve the different levels and chamfers. Around the orifice 18 in the main body 3, a spacer tube 19a is configured, in particular in length, to define the spacing between the fork 12 and the stinger 14. The fork 10 is made by etching typically from a silicon wafer. A ruby pin 16 is driven into the hole of the board and the silicon fork is assembled with play on the pin which protrudes then is glued, the fork being pressed against the end surface of the spacer tube 19a.

• Les géométries sont réalisées avec la précision des procédés photolithographiques utilisés classiquement pour la réalisation des moules pour l'opération d'électroformage du corps ainsi que pour la définition de la forme de la fourchette dans une couche de masquage avant le gravage du silicium.
• La fabrication du tenon en rubis est maîtrisée : les tolérances sur le diamètre sont très fines typiquement de l'ordre de ± 1.5 µm.
• Le tenon en rubis n'a pas de téton de coupe et les faces sont parfaitement planes et parallèles entre elles contrairement aux tenons décolletés.
• Le positionnement vertical des composants est très précis.
• Les coûts de fabrications et d'assemblages sont réduits

The advantages of this second embodiment are:

• The geometries are made with the precision of the photolithographic processes conventionally used for producing the molds for the electroforming operation of the body as well as for defining the shape of the fork in a masking layer before the etching of the silicon.
• The manufacture of the ruby tenon is controlled: the tolerances on the diameter are very fine typically of the order of ± 1.5 microns.
• The ruby tenon has no cutting nipple and the faces are perfectly flat and parallel to each other unlike the low-cut tenons.
• The vertical positioning of the components is very precise.
• Manufacturing and assembly costs are reduced

In the third embodiment according to figure 3 , the main body 3 is manufactured by a LIGA type electroforming process to form a layer of constant thickness. The fork 10 is made by etching typically from a silicon wafer on at least two levels to form a spacer tube 19b extending around the orifice 20 of the fork 14. The spacer tube 19b is configured, in particular in length, to define the spacing between the fork 12 and the plank of the main body 3. A tenon ruby 16 is driven into the hole of the board and the silicon fork is assembled with clearance on the post that exceeds and is glued. the end of the spacer tube 19 of the fork being abutted against the surface of the main body 3.

It will generally be noted that the connection between the tenon and the fork and / or the main body will be different in nature depending on whether the fork and / or the post is made of a material with a plastic domain (for example metal) or a material fragile, that is to say having virtually no plastic field (eg silicon, silicon carbide, silicon nitride, etc.). When the fork and / or the main body is of a material with a plastic field, the post is driven into the body and / or the fork. When the fork and / or the main body is in a material without a plastic field the tenon is stuck in the body and / or the fork.

The invention makes it possible to reduce manufacturing costs and increase production yields. It is indeed problematic to remove the current tenons in these dimensions and to control the assembly of the post, plank and dart / horns. An important advantage of the use of a tenon made of a material having no plastic domain under stress for the assembly of the fork to the main body of the anchor is that it holds the deformation during assembly , it allows to be cut and ground with front faces forming perfectly flat reference faces parallel to each other and precise dimensions. This results in particular excellent control of the spacing between the fork and the main body during the assembly operation between these two parts.

List of references

• an escape mechanism
• an anchor 2
• main body 3
• baguette 8
• pallet support part 7
• spacing tube 19a
• hole / hole 18
• pivot 10
• part of fork 4
• fork 12
• first horn 22a second horn 22b
• hole / hole 20
• spacing tube 19b
• dard 14
• tenon 16
• dish 24
• pallets 6
• entry pallet
• output pallet

Claims (11)

1. Pallet lever (2) for an escapement mechanism of a watch movement, including a fork portion (4), a pallet-stone holder portion (7), pallet-stones (6) mounted on the pallet-stone holder portion, and a lever (8) interconnecting the pallet-stone holder portion to the fork portion, the fork portion including a fork (12), a guard pin (14) and a stud (16), the lever and the pallet-stone holder portion being integral and forming a one-piece main body (3) of the pallet lever, and the fork is an added part secured to the main body by means of the stud which has a generally cylindrical shape including at each end thereof a front face extending perpendicularly to its longitudinal axis, said stud being driven into a securing hole (18) in the main body and a securing hole (20) in the fork, the added fork being at a distance from the main body, the pallet lever (2) being characterized in that the stud is manufactured from a material having virtually no plastic range under stress, and in that the front faces of the stud (16) are less than 1° out of square with respect to said longitudinal axis.
2. Pallet lever according to claim 1, characterized in that the stud has a hardness greater than or equal to 850 HV.
3. Pallet lever according to claim 1 or 2, characterized in that at least the surfaces of the stud engaging with the securing holes include a surface finish obtained by grinding.
4. Pallet lever according to any of the preceding claims, characterized in that the stud is made from a material selected from the group including sapphire, ruby, aluminium oxide, zirconium oxide, tungsten carbide, single crystal or polycrystalline corundum, silicon nitride, silicon carbide, hardened steel, tungsten carbide in a cobalt matrix and amorphous metal alloys.
5. Pallet lever according to any of the preceding claims, characterized in that the fork is manufactured from a material selected from the group of materials including silicon, silicon nitride, silicon carbide, nickel, nickel-phosphorus, steel, amorphous alloys and copper alloys.
6. Pallet lever according to any of the preceding claims, characterized in that the main body is manufactured from a material selected from the group of materials including silicon, silicon nitride, silicon carbide, titanium, aluminium, steel, nickel, nickel-phosphorus, and amorphous alloys.
7. Pallet lever according to any of the preceding claims, characterized in that the fork includes a spacer tube (19b) around the securing hole (20), said tube being configured to define the distance between the fork and the main body.
8. Pallet lever according to any of the preceding claims 1 to 7, characterized in that the main body includes a spacer tube (19a) around the securing hole (18), said tube being configured to define the distance between the fork and the main body.
9. Pallet lever according to any of the preceding claims, characterized in that the main body includes different levels obtained by machining.
10. Timepiece escapement mechanism including at least one pallet lever according to any of the preceding claims.
11. Watch movement including an escapement mechanism according to the preceding claim.

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