WO2016146305A1

WO2016146305A1 - Tribological microstructured receptacle

Info

Publication number: WO2016146305A1
Application number: PCT/EP2016/052734
Authority: WO
Inventors: Agnès Marlot Doerr; Yves Burri
Original assignee: The Swatch Group Research And Development Ltd
Priority date: 2015-03-13
Filing date: 2016-02-09
Publication date: 2016-09-22
Also published as: EP3067757A1

Abstract

The invention relates to a micromechanical part, particularly for clockwork mechanisms, locally comprising at least one area which is microstructured by means of a laser, the microstructured area having a three-dimensional surface consisting of microcavities designed to be used as a reservoir for a lubricating substance.

Description

Micro-structured tribological tank

Field of the invention

The invention relates to micromechanical parts, especially those of a mechanical watch, some of which movable parts are made to be lubricated.

Background of the invention

It is known that in watchmaking mechanisms, there are many parts in motion and in frictional contact with each other. This friction must be reduced as much as possible because it can affect the precision and / or the autonomy of the mechanism.

In fact, the friction leads to wear of the parts, an increase in the energy consumption to move the parts and a slowing down of the movement.

To reduce this friction, it is known to use liquid or viscous lubricants. These lubricants are used sparingly on well-defined areas and in suitable quantities. This type of lubricant must be able to slip between two parts to minimize friction or must be removed during assembly. On the other hand, the ability to slip between two rooms can also escape from the space where it has been deposited. It is also very sensitive to the environmental conditions of temperature and relative humidity because its viscosity evolves according to these.

A disadvantage of such a solution is that these liquid or viscous lubricants change in the direction of degradation, for example by loading with dust or becoming more viscous or losing their lubricating capacity by oxidation. Another disadvantage is that this type of lubricant being fluid or viscous, the movement of the parts tends to move the lubricant from the contact area to a non-frictional area.

It is therefore necessary to carry out regular maintenance which consists in cleaning the parts in friction and replacing the used lubricant with a new lubricant at the appropriate places.

The lubrication of a watch mechanism aims to control the friction of moving parts. It obeys complex and precise rules in order to guarantee maximum and lasting reliability. Its action, by a film of oil or grease, prevents the direct contact of the materials in the presence, which results in a reduction of the energy losses and the wear, due to the friction, as well as an increase of the mechanical efficiency. Depending on the parts in contact, different oils or greases are applied with varying viscosities and in specific amounts.

In practice, lubrication losses are observed over time, for example on rotating parts that exert a projection effect and promote leakage. Therefore, regular maintenance (cleaning and / or epilamming and oiling) must be performed on the movements. To reduce the frequency and costs of these interviews, various solutions have been considered and applied in the watch industry.

The first solution is focused on special lubricant formulations. Lubric is an example. It corresponds to a mixture of Moebius 901 0 oil and solid particles of MoS ₂ . In production, this mixture is deposited by spray on the sides of escape wheels, giving a typical black and pasty coloration. The micrograins make it possible to trap, like a sponge, the thixotropic oil 941 applied in a second step on the wheel. The lubricant ensures a more stable and durable operation than standard lubrication. However, it poses great problems aesthetic, especially for high-end brands that have high standards in this area.

Another solution is to structure the basic material constituting the movement part. Such a solution is described in DE 1 02009046647. The base part made of aluminum or aluminum alloy comprises an oxide-based coating formed by anodic oxidation. This coating although hard has a honeycomb structure with pores that can receive an oil, grease or a solid lubricant. However, such a solution does not allow to be applied selectively to precisely defined areas of the room. In addition, it is limited to only one type of base material, namely aluminum-based alloys.

Summary of the invention

The invention particularly aims to overcome the various disadvantages of these known techniques.

More specifically, an object of the invention is to provide localized lubrication for optimizing the role of the lubricant.

The invention also aims, at least in a particular embodiment, to provide lubrication that is reliable and durable.

These objectives, as well as others which will appear more clearly later, are achieved according to the invention with the aid of a micromechanical part, intended in particular for clockwork mechanisms, comprising locally at least one microstructured area by means of laser, the microstructured area having a three-dimensional surface formed of microcavities configured to serve as a reservoir for a lubricating substance.

Thus, the object of the present invention, by its different functional and structural aspects described above, makes it possible to obtain a part whose areas subjected to friction have localized lubrication. to optimize the role of the lubricant and increase its effectiveness by concentrating the lubricant in the areas subject to friction, the laser engraving technique has the advantage of offering a very high accuracy of realization.

According to other advantageous variants of the invention:

the microstructured zone presents a network of microcavities distributed regularly;

the depth P of the microcavities is less than or equal to 100 μιη;

the diameter L of the microcavities is between 0.1 μιη and 100 μιη, and preferably between 1 μιη and 10 μιη;

the depth P and the diameter L of the microcavities may vary within the same microstructured zone;

the depth P of the microcavities is greater than the diameter L of the microcavities;

the microcavities are in the form of holes or canyons;

the microstructured zone is produced by a laser pulse machining method, for example a picosecond or a femtosecond method;

the microstructured zone is made of metal, ceramic, polymer or composite. Examples of metal or metal alloys are steel, aluminum, titanium, brass, nickel or gold;

- The microstructured area can also be ruby, silicon, quartz or diamond.

According to the invention, the microstructured zone may be an inner wall of a barrel, an axis of mobile rotation, exhaust vanes, exhaust wheel teeth, or even pivoting stones. Brief description of the drawings

Other particularities and advantages will emerge clearly from the description which is given hereinafter, by way of indication and in no way limiting, with reference to the appended drawings, in which:

FIGS. 1a and 2a are schematic views from above of a microstructured zone according to two distinct embodiments;

- Figures 1b and 2b are respectively sectional views along the planes 11 and 111 of Figures 1a and 2a;

- Figures 3a and 3b respectively show a perspective view of an exhaust pallet having a microstructured area and a sectional view of the pallet.

Detailed Description of the Preferred Embodiments

A micromechanical part according to a particular embodiment will now be described in the following with reference to Figures 1a, 1b, 2a, 2b, 3a and 3b.

The invention relates to a micromechanical part, intended in particular for clockwork mechanisms, locally comprising at least one microstructured zone 1 by means of a laser, the microstructured zone 1 having a three-dimensional surface formed of microcavities 10 configured to serve as a reservoir for a lubricating substance.

A first embodiment is illustrated in Figure 1a, and schematically shows a microstructured area 1 of a micromechanical part. Microcavities can be observed formed on the surface of the workpiece on a regular basis.

The microstructured zone 1 is formed by a network of microcavities

10 formed by means of a laser whose pulse duration is of the order of the femtosecond, that is to say 10 ^{~ 15} seconds (typically 100 fs). Pulse duration can range from femtosecond to picosecond (10 ^{~ 12} seconds). The laser is used to modify the structure of the piece of micromechanical and locally form a microstructured area 1 having a three-dimensional surface. For this purpose, the laser is set in motion so that it sweeps the surface of the microstructure part to locally cause a change in the structure of the material of the part.

One can also imagine that it is the piece that is set in motion, or a combination of both, so as to modify the structure of the piece.

According to the invention, the microstructured zone 1 has a network of microcavities 10 regularly distributed according to a precise diagram as illustrated in FIG. 1 a. The distribution of microcavities can obviously be performed randomly by programming the movements of the laser and / or the part.

The microcavities forming the three-dimensional surface can be defined according to the following three parameters: the shape, the dimensions, namely the diameter L and the depth P, and the covering surface.

The depth P of the microcavities 10 is advantageously less than or equal to 100 μιη, and the diameter L of the microcavities 10 is between 0.1 μιη and 100 μιη, and preferably between 1 μιη and 10 μιη.

According to a particular embodiment of the invention, the depth

P and the diameter L of the microcavities 10 may vary within the same microstructured zone 1. For example, it is possible to envisage that a first third of the microstructured zone 1 has microcavities 10 having a depth of 1 μιη and a diameter of 10 μιη, whereas a second third of the microstructured zone 1 has microcavities 10 having a depth of 10 μιη and a diameter of 100 μιη, and a third third has microcavities 10 having a depth of 1 μιη and a diameter of 10 μιη. Thus the combinations may vary according to the needs of the skilled person, that is to say, depending on the type of application and the type of room. According to a variant of the invention, the depth P of the microcavities 10 is greater than the diameter L of the microcavities, of the order of three for example.

According to the needs of those skilled in the art, the microcavities 10 may take different forms, and be for example hemispherical, elliptical, parallelepipedal or may be in the form of grooves. Embodiments respectively having microcavities 10 of hemispherical shape and microcavities 10 in the form of grooves are illustrated in FIGS. 1a and 2a.

According to the invention, the microcavities 10 forming the microstructured zone 1 can occupy a variable surface, for example the microcavities can occupy 20% of the surface of the microstructured zone so as not to saturate the microstructured zone 1 with lubricating substance 1.

As can be seen in the cross-sectional view in FIG. 1b, along the line 11-11 of FIG. 1a, the diameter L of the microcavities 10 can vary according to the depth P. It is the same for the width L of the grooves in the sectional view in FIG. 2b, along the line III-III of FIG. 1b.

Depending on the micromechanical part receiving the modification, the zone to be microstructured may be metal, metal alloy, ceramic, polymer or composite. The metals or metal alloys can be for example steel, aluminum, titanium, brass, nickel or gold. The zone to be microstructured can also be in ruby, silicon, quartz or diamond.

The micromechanical parts having at least one microstructured zone 1 may be, for example, an inner wall of a cylinder, an axis of mobile rotation, exhaust vanes, exhaust wheel teeth, or stones pivoting. An exemplary embodiment for a pallet 100 of an anchor is illustrated in Figures 3a and 3b.

Referring to FIGS. 3a and 3b, an anchor pallet 100 is observed. The pallet is a generally ruby piece, all the faces of which are polished, and which is driven and glued into a housing 104 formed in the arm 101 of a Anchor 102. The pallet 100 comprises a pulse plane 100a, a rest plane 100b and a leakage plane 100c, the pulse plane 100a and the leakage plane 100c intersecting according to an output stop or pulse nozzle 100d. The impulse plane 100a and the rest plane 100b cooperate respectively with the teeth 106 of an escape wheel and more particularly with the rest plane 1 06a and the stopper 1 06b of the teeth 106. The wheel of Exhaust turns in a conventional manner step by step in the direction of arrow F. Particularly important lubrication points are therefore the pulse plane 100a and the rest plane 100b so that a presence of lubricant between the teeth of the wheel exhaust and these plans is necessary during the various phases of operation of the exhaust.

To do this, the pallet 1 00 comprises a microstructured zone serving as a reservoir for this lubricant. It will be noted that the dimensions of the microstructured zone are substantially equivalent to or greater than those of the tooth 106 of the escape wheel.

According to the invention, the microstructured zone connects the leakage plane 100c to the pulse plane 100a and to the rest plane 100b so as to establish a lubrication zone on the surface in contact with the teeth 106 of the wheel. 'exhaust.

As can be seen in FIG. 3b, the lubricant 107 which is deposited on the microstructured zone of the pallet 1 00 in the form of a drop is introduced by capillarity into the microcavities and fills the latter until a drop 107a is formed which protrudes slightly from the pulse plane 100a. A drop 1 07b is formed also on the rest plane 100b when the pallet 100 is in contact with the tooth 106.

With these different aspects of the invention, there is an exhaust pallet with localized lubrication to optimize the role of the lubricant and to increase the efficiency by concentrating the lubricant in the areas subject to friction. As the lubricant is trapped in the microstructured zone, the phenomena of leaks and migrations are reduced and the duration of the lubrication is considerably increased. Similarly, the frequency and maintenance costs of the movement of the watch are decreased.

Of course, the present invention is not limited to the illustrated example but is susceptible of various variations and modifications that will occur to those skilled in the art. In particular, any piece forming the movement of a watch and subjected to friction is likely to include a microstructured area as described above.

NOMENCLATURE

1. Microstructured area,

10. Microcavity,

100. Palette,

100a. Pulse plan,

100b. Rest plan,

100c. Flight plan,

100d. Stop output

101. Arms,

102. Anchor,

104. Housing,

106. Tooth,

106a. Rest plan,

106b. Beak of rest,

107a, 107b. Drop of lubricating substance,

P. Depth of microcavity,

L. Diameter or width of the microcavity.

Claims

1. Micromechanical part, intended in particular for clockwork mechanisms, comprising locally at least one microstructured zone (1), the at least one microstructured zone (1) having a three-dimensional surface formed of microcavities (10) on the surface of the part, configured to serve as a reservoir for a lubricating substance, the microcavities (10) having a depth P and a diameter L, the depth P and the diameter L of the microcavities (10) may vary within the same microstructured zone (1).

2. micromechanical part according to claim 1, wherein the at least one microstructured zone (1) has a network of microcavities (10) distributed regularly.

3. micromechanical part according to claim 1 or 2, wherein the depth P microcavities (1 0) is less than or equal to 1 00 μιη.

4. Micromechanical part according to any one of claims 1 to 3, wherein the diameter L of the microcavities (10) is between 0.1 μιη and 100 μιη, and preferably between 1 μιη and 10 μιη.

5. Micromechanical part according to any one of claims 1 to 4, wherein the depth P and the diameter L of the microcavities (10) may vary within the same microstructured zone (1).

6. Micromechanical part according to any one of claims 1 to 5, wherein the depth P of the microcavities (10) is greater than the diameter L of the microcavities (10).

7. micromechanical part according to any one of claims 1 to 6, wherein the microcavities (10) may be hemispherical, elliptical, parallelepiped or in the form of grooves.

8. Micromechanical part according to any one of claims 1 to 7, wherein the microstructured area (1) is performed by a method of machining pulsed picosecond or femtosecond laser.

9. micromechanical part according to any one of claims 1 to 8, wherein the microstructured zone (1) is metal, metal alloy, ceramic, polymer, composite, silicon, ruby, quartz or diamond.

The micromechanical part according to claim 9, wherein the metal or metal alloy is based on steel, aluminum, brass, nickel, titanium or gold.

1 1. Micromechanical part according to claim 9 or 10, wherein the microstructured area (1) can be an inner wall of a cylinder, a rotational axis of the moving parts, exhaust vanes, exhaust wheel teeth, or still some pivoting stones.