CH715419B1 - Bearing for a timepiece and method for manufacturing such a bearing. - Google Patents

Abstract

The invention relates to a bearing for a timepiece, produced in a single block in a substrate transparent to the wavelength of a laser, and comprising a central part (106) delimiting a hole (107) intended to guide a pivot (21), the hole (107) comprising a guide surface (107a). At least a portion of the guide surface (107a) comprises a structured contact surface, intended to come into contact with the pivot (21) that it guides, forming for example protuberances (107b). The bearing may further comprise elastic members making it possible to absorb shocks. The invention also relates to a method of manufacturing the bearing during which the structure of the substrate is modified in a defined area, by means of a femtosecond laser, and the modified structure removed by chemical etching.

Description

Technical area

The present invention relates to a bearing for guiding a component shaft of a timepiece, in particular a balance wheel, characterized by a geometry of the three-dimensional type, which can advantageously be produced in a single step of a microfabrication process, and having advantageous tribological properties during its operation with the shaft with which it is intended to cooperate. The invention also relates to a damping bearing or an anti-shock bearing.

State of the art

[0002] In a mechanical watch movement, the axes of the balance wheel and of the mobiles of the escapement and of the gear train are terminated by pivots guided in bearings. These pivots are generally quite thin, and therefore fragile. Furthermore, because of this relative rotational movement, there is a certain wear of the two surfaces in contact and their relative friction reduces the performance of the system.

[0003] The anti-shock bearings are designed to protect the pivots by authorizing, during an impact, an axial and/or radial movement of the axis of the mobile unit against elastic means until a part of the axis, which is stronger than the pivots, abuts against a fixed support of the bearing, the elastic means bringing the axis back to its initial position after the impact.

[0004] Document JP2011180006 describes a ball bearing damping bearing. In this case, due to the various parts present to form the bearing, and in particular the balls, there are numerous manufacturing and assembly steps. In addition, it is necessary to adapt the dimensions and the manufacturing range of the bearing and of its balls for each bearing of the timepiece.

[0005] The document WO2013092924 describes a watch component, in particular a bearing or an pallet pallet, produced by a selective structuring process and comprising a reservoir intended to contain liquid which cooperates through a channel opening onto the housing of the pivot in order to lubricate it. However, the channels connecting the reservoirs to the hole must be dimensioned so as to ensure the ideal flow rate of the liquid towards the hole, which makes the operations of filling and changing the liquid as well as the cleaning of the bearing very complicated. In addition, the contact surface of the bearing described in this document is not structured so as to limit friction with the shank with which it is associated, contrary to the object of the present invention.

[0006] The document CH702314 describes a one-piece bearing made of a crystalline material and comprising a flared hole to accommodate a shank, this hole comprising flat surfaces resulting directly from the machining process and located in the crystalline planes of the part. This limitation excludes the texture of the walls/surfaces of the hole.

[0007] The document JP2012117842 describes a bearing associated with an axis, as well as a means of lubricating it. The bearing is structured on the surface cooperating with a seat of the shaft, in order to promote lubrication. This document therefore proposes to produce structurings on a plane support surface of the pivot, with a part of these structurings which cooperates with the pivot to dispense the oil, but does not in any case propose or suggest structuring the bore provided to receive the pivot.

[0008] The document EP2226689 describes a bridge made of micromachined material. The bridge has machined holes for receiving an axle. The olivage of the hole makes it possible to maintain a reserve of lubricant in the accesses. However, this geometry is not a structuring, and the manufacturing methods described for making the olives do not make it possible to make complex structures along the wall of the hole.

[0009] Document CH710846 describes a watch component, one surface of which is a surface formed by a network of microcavities, the latter being configured to act as a reservoir for a lubricating substance. However, the processes combined with the materials do not make it possible to obtain complex geometries.

Brief summary of the invention

[0010] An object of the present invention is to provide a solution free from the limitations of known bearings.

Another object of the invention is to provide a bearing that is easy to manufacture, whether for small series or large series.

Another object of the invention is to provide a bearing whose tribological properties are satisfactory during its operation with the pivot with which it must cooperate.

According to the invention, these objects are achieved in particular by means of a bearing for a timepiece, produced in a single block in a substrate transparent to the wavelength of a laser, and comprising a central part defining a hole for guiding a shank, the hole comprising a guiding surface; at least a portion of the guide surface comprising a structured contact surface, intended to come into contact with the shank that it guides. It is understood that the geometry of this bearing makes it possible to have a reduced contact surface between the bearing and the shaft which it receives and which it guides. Indeed, the surface of the hole wall, which can be based on a surface of revolution (such as a cylinder of circular cross-section or a one-sheeted hyperboloid) or on a faceted surface of constant cross-section (such as a polygonal prism) or variable, preferably comprises projecting portions in the direction of the axis of the hole. Thus, it is these protruding portions which are the preferred contact points, lines or surfaces. Another embodiment of the invention consists in carrying out a submicronic structuring on the surface, which also results in privileged contact surfaces. Indeed, in all cases the extent of the surfaces in contact between the shaft and the pivot is reduced.

[0014] This solution notably has the advantage over the prior art of having a bearing having improved tribological properties, whether it is used in combination with a liquid lubricant or not.

Preferably, said geometric structuring comprises at least one of the following geometric objects: spherical ring, sphere cap, portion of any convex surface or any other geometry resulting in points, lines or contact surfaces arranged on at least a circle coaxial with the axis of the hole. These geometric objects form possible surfaces, lines and/or points of contact between the wall of the hole and the pivot. The structured contact surface resulting from the aforementioned intersection may comprise several of these objects, in particular several spherical rings, sphere caps or portions of convex surface, distant from each other.

[0016] In one embodiment, the structured contact surface comprises protrusions of hemispherical shape. Such protrusions provide a geometry which greatly reduces the contact surfaces, and therefore the friction forces between the bearing and the pivot of the shaft, and this in different relative positions between the bearing and the pivot that it receives.

[0017] Advantageously, the structured contact surface comprises at least three protrusions distributed in a plane orthogonal to the axis of the pivot. The presence of three or more contact points between the bearing and the rod, in the same plane orthogonal to the axis of the pivot, provides reduced friction.

[0018] In one embodiment, said bearing further comprises elastic members allowing a translation of the central part delimiting the hole along at least one axis. Such elastic members are preferably arranged between the central part and the edge of the bearing, whereby the bearing is a shock-absorbing bearing. In this way, a bearing is produced which both makes it possible to perform improved tribological functions and also forms a shock absorber. Advantageously, the elastic members are three-dimensional, that is to say that their elastic component is not contained in a single plane, which makes it possible to accommodate very varied geometries and form a more or less flexible or rigid damping, operating in one or more preferred directions. This also has the advantage of being able to reduce the bulk of the bearing without reducing the active length of the elastic arms, by resorting to geometries extending over several planes, such as, for example, geometries of the serpentine type.

Brief description of figures

Examples of implementation of the invention are indicated in the description illustrated by the appended figures in which: FIG. 1 illustrates a first embodiment of a bearing for a timepiece according to the invention; Figure 2 illustrates detail II of Figure 1; FIG. 3 illustrates a second embodiment of a bearing for a timepiece according to the invention; FIGS. 4a and 4b illustrate a third and a fourth embodiment of a bearing for a timepiece according to the invention; FIGS. 5a and 5b illustrate a fifth and a sixth embodiment of a bearing for a timepiece according to the invention; Figures 6a and 6b show the partial sectional view of the bearing according to the fifth embodiment, respectively according to section A-A and B-B of Figure 5a; FIG. 7 shows in partially cutaway perspective, a possible bearing geometry for the variant of the sixth embodiment, from the face of the bearing receiving the pivot, FIG. 8 illustrates the bearing of FIG. 7 in perspective from the other face of the bearing ; FIG. 9 shows in sectioned perspective a possible bearing geometry for a variant partially similar to the first embodiment; Figure 10 illustrates an unsectioned detail of the bearing of Figure 9; FIG. 11 illustrates a seventh embodiment of a bearing for a timepiece according to the invention; and FIG. 12 illustrates one of the phases of the method according to the invention in comparison with a technique of the prior art.

Example(s) of embodiment of the invention

Figure 1 illustrates a first embodiment of a timepiece bearing according to the invention. It is recalled that this bearing is an element serving as a pivot for a shaft of the timepiece.

This bearing 100 alone forms a pivot system comprising, in the lower part, a base 102 with a hole 103 for the passage of the shaft 20 terminated by a pin 21, the base 102 comprising an annular edge 104 forming the radially outer wall of the bearing 100. The bearing 100 comprises in the upper part a central part 106 with a hole 107 of axis P, here a blind hole, to receive the shank 21 of the pivot. Between the central part 106 and the upper end of the annular edge 104 of the base 102 extend arms 108 formed of three-dimensional elastic members. When a bearing is shock-absorbing, that is to say that elastic members allow relative displacements of the pivot, it is important to be able to limit the travel of the radial and axial displacements of the guided mobile to avoid a breakage of the shank 21 during significant shocks. This function is ensured by the base 102 which comprises a hole 103 to limit the radial displacements by retaining the shaft 20 and a bearing surface 111 to limit the axial displacements. In the rest of the text, the term "pivot" is used to describe either the shaft 20 or rod 21, intended to cooperate with one of the holes 103 and/or 107.

According to the invention, the bearing 100 is monobloc, formed from a single piece. Preferably the recess 110 existing between the base 102, the arms and the central part 106 is a continuous volume, opening out towards at least one surface of the part and which is obtained by etching in the mass of a block of material or substrate initially full.

[0023] Preferably, the bearings according to the invention are produced by the "Selective Laser-induced Etching" (SLE) or "In-Volume Selective Laser-induced Etching" (ISLE) technique.

For this purpose, the recess 110 is obtained as follows: a) a substrate of dimensions greater than the dimensions of the bearing is provided; b) a laser is provided with a pulse duration which can range from femtosecond (10<-15>second) to picosecond (10<-12>second); c) the structure of the substrate is modified over at least one volume defining a boundary between the geometry of the desired level and the material to be removed; d) a chemical agent is provided which allows the material of the volume of the substrate whose structure has been modified by the laser in the preceding step, to be dissolved more quickly than the other areas of material whose structure has not been modified; e) the substrate with the volume of modified structure is exposed, for example in a bath, to the chemical agent for a predetermined time so that all of the material of the volume of modified structure is dissolved; and f) the exposure of the part thus formed is stopped, for example by removing it from the bath, and any trace of the chemical agent is removed, for example by washing it and thus stopping the reaction between the chemical agent and the substrate material.

The bearing 100 shown in Figure 1 is then directly obtained.

The modification of the structure of the substrate in step c) is only possible by using a material for the substrate which is transparent for the wavelength of the laser. In practice, one traverses with the focal point of the laser, point to point, at least the contour defined by the border between the volume of the substrate intended to form the recess 110 and the volume of the desired bearing 100. This method has the particular advantage, compared to many chemical etching methods, that only a boundary zone between two volumes of substrate to be separated must be exposed and etched, and not the entire volume to be removed, which greatly accelerates the speed of the process. Obviously, this is only valid for volumes which can be removed entirely, that is to say that their geometry must be extradable from the substrate after separation. Otherwise, the exposure by laser will have to be done on additional zones, by resorting in particular to intermediate cut-outs, or even total exposure in certain cases, in order to remove the unwanted part of the substrate. A modification of the structure of the material is thus carried out by absorption with several photons, which requires a particularly high energy density.

In step d), the local modification of the structure by the laser makes it possible to choose a chemical agent which is more reactive in the volume of modified structure than in the other unmodified zones. By way of example, in the case of a borosilicate glass, the irradiated zone can be dissolved at a rate which can reach 300 times that of the dissolution rate of the unexposed zone.

Thus, preferably, the bearings according to the invention are obtained by a selective etching process, implemented after a preliminary step of modifying the structure of at least part of the three-dimensional zone of the substrate in front of be removed. The modified zone of the substrate can be removed from the modified zone of the substrate by any other means equivalent to chemical etching.

Figure 12 illustrates the advantage of the production method employed in the context of this invention. The laser beam shown in solid lines corresponds to that used in the present method. In this case, it makes it possible to reach points internal to the substrate, at variable depths, or placed on surfaces that are not directly accessible. An example of a conventional method, represented by the dotted line, highlights its limitations. Areas hidden or not directly accessible by a laser beam, in particular the bottoms of grooves or holes, cannot be textured. In addition, the areas potentially reachable by a traditional laser cannot be textured with adequate precision or reproducibility. The incident beam having to be tilted by an angle α to reach the wall of the hole, the sides of the textures cannot be perpendicular to the surface of the hole. Moreover, certain texturing geometries cannot be obtained, in particular circular structurings.

[0030] The cylindrical surface of the wall of the hole can also lead to deformations or complexity in replicating the pattern of the structuring all around the wall. Thus, for a hole diameter of a value D, with an angle α of approximately 10°, the maximum depth of structuring of the wall of the hole that can be obtained by a traditional method cannot reasonably exceed a height e = D tan (α = 10°), i.e. less than 20% of the hole diameter, which is not sufficient for bearings with deeper guides. The present method makes it possible to obtain a bearing comprising a hole of diameter D comprising the structurings having a height e exceeding 20% of the diameter of the hole.

[0031] This method also makes it possible to produce complex geometries that cannot be obtained by a traditional method, in particular thanks to the possibility of focusing the laser on an area internal to the substrate. This also offers great flexibility as to the orientation of the incident laser, which can be directed onto the point to be focused from several points. FIG. 12 illustrates a few examples of complex structurings which can be produced by the method of the invention. Such structurings, by their geometries, their locations and their number, make it possible to control the zones of contact of the bearing with the shaft. In addition, the precisely controlled dimensions and geometries, including in particular edges which limit the spreading of the lubricant, can make it possible to effectively retain the lubricant on the structured surfaces.

The material used to form the substrate making it possible to obtain one or the other of the bearings according to the invention preferably belongs to the group comprising quartz, natural and synthetic ceramics (including in particular sapphire, synthetic ruby , polycrystalline ruby), glasses, glass-ceramics, silica, composites and polymers.

Advantageously, the material used to form the substrate making it possible to obtain one or the other of the bearings according to the invention is a non-metallic material which has a hardness greater than 1200 Hv, this hardness corresponding in particular to requirements described in the ISO 1112-2009 standard or the NIHS 94-10 standard.

As seen more specifically in Figure 2, a guide surface 107a of the wall of the hole 107 has a geometric structure, here protrusions 107b. In this example, the guide surface 107a comprises the entire wall of the hole 107, including the bottom wall of the hole 107. The guide surface 107a advantageously defines a cylinder of revolution intended to receive the pivot, and at the bottom wall of the hole 107 which receives the end of the rod 21a. The guide surface 107a is intended to cooperate with the rod 21 so as to guide it when the latter is received in the hole 107.

In the example of Figures 1 and 2, the geometric structuring comprises hemispherical protuberances arranged in a first group on the bottom wall of the hole 107 (at the top in Figures 1 and 2) and in a second group on the side wall of the hole 107. In the latter case, the protrusions 107b are distributed in a ring, namely in a plane orthogonal to the axis P of the pivot. In this way, there is a series of contact points between these protrusions 107b arranged in a crown and the shank 21, these contact points being distributed over a circle concentric with the hole 107 and with the axis of the pivot. Preferably, these protrusions 107b are distributed equidistantly between them, with the same angular sector measured from the axis P between two neighboring protrusions.

It is understood that these protrusions delimit very small surfaces, most of the time point or linear, for contact with the surface of the shank 21, which greatly limits friction.

Thus, the first group of protrusions 107b (top in Figures 1 and 2) is likely to come into contact with the end of the pin 21 formed in this case of a flat face 21a. In the position shown in Figures 1 and 2, the rod 21 is not sufficiently engaged in the hole 100 for there to be contact between the first group of protrusions 107b and the flat face 21a. Similarly, the second group of protrusions 107b is likely to come into contact with the cylindrical side wall of the pin 21. In practice, this contact occurs on a number of points which may be less than the number of protrusions 107b. In the positions in which the shaft is horizontal and subjected to the action of gravity, the latter will tend to rest on a number of protrusions 107b of the second reduced group, as shown in FIG. 6b. In the positions where the shaft is vertical, contact will be made on the protrusions 107b of the first group, and partially (depending on whether or not the mobile moves on a plane perpendicular to the axis of the pivot) on protuberances 107b of the second group.

In general, the geometric structuring includes protrusions 107b in the form of a sphere portion, an ovoid portion, a paraboloid portion or any convex portion.

In one embodiment, at least a portion of the surface of the hole wall 107 is convex, such as a 2-ply hyperboloid surface. This convexity creates a reduced contact surface with the shaft 20.

[0040] The protrusions 107b can be dimensioned and distributed in such a way that they generate controlled friction torques on the shank 21. Thus, it is for example possible to calculate the friction torques generated by the first and second groups of protrusions on the shank and arranging these first and second groups of protrusions so as to obtain friction couples which compensate for, or even cancel, the variations in the variations of speed (mobile), of amplitude and/or of rate (pendulum) between the positions horizontal and vertical; these calculations can take into account parameters including in particular the respective coefficients of friction of the surfaces in contact, the respective radii of the surfaces of the protrusions and of the shank, the radii of the respective contact zones with respect to the axis of rotation of the pivot and the number of these effective contact areas in each of the positions.

In one embodiment, the protrusions 107b have a capillary effect retaining a film of oil around the point (or line, or surface) of contact with the rod 21.

According to the second embodiment of Figure 3, the difference with the first embodiment which has just been described lies in the fact that only the first group of protrusions 107b located on the bottom wall of the blind hole 107 is present. Here, the shank 21 has a pointed end 21a, in particular in the shape of a cone, so that the rotational guidance essentially takes place via this end 21a. The second group of protuberances 107b of the side wall has been omitted.

In the first and second embodiments which have just been described, the hole 107 of the bearing is blind. In this case, preferably, the bearing 100 comprises protrusions 107b on the bottom wall of the blind hole 107.

According to another embodiment illustrated in Figure 11, the hole 107 is not a blind hole but a through hole.

[0045] Figures 4a and 4b illustrate a third and fourth embodiment, respectively. According to the third embodiment of the bearing 100 illustrated in FIG. 4a, the geometric structuring comprises submicronic ablations 107d which have the effect of reducing the contact surface with the shank 21.

According to the fourth embodiment of the bearing 100 illustrated in Figure 4b, the hole 107 is an olive hole. The wall 107c of this olive hole is convex between the two ends of the hole 107 with a hole diameter which is reduced between each of the two ends of the hole 107 and an intermediate portion, located for example in the middle of the length of the hole 107 This olive shape makes it possible to concentrate the contact zone on a narrow circular band, located approximately in the middle of the length of the hole 107. Another known advantage of this geometry is that it allows relatively stable behavior even if the axis of the rod 21 is not parallel to the axis of the bearing.

[0047] According to a feasible arrangement for all the embodiments and visible at the level of the hole 103 of the base 102 of the third and fourth embodiments of the bearing 100 (FIGS. 4a and 4b), a fillet 112 can be added directly in the bearing in the same operation on all the edges requiring such a geometry, whether it is a question of facilitating the guiding of the shank 21 during its installation, of facilitating the driving of the bearing 100 into its support, of limiting the risks of wear linked to a sharp edge against a surface in mobile contact, or in general, to soften these edges in order to avoid incipient fractures which may occur when using fragile and brittle materials. In this way, the wall of the hole 103 has a rounded end on the side where the shaft 20 engages in the hole, this fillet 112 being favorable to the limitation of friction and the guiding of the shank 21 during its introduction into the hole. 103.

In Figure 4b, the arms 108 are shown in section in a variant in the form of arms 108 'whose thickness (dimension in the direction of the axis P of the central part 106) is not constant as for the arms 108, but is variable in the radial direction, in order to distribute the stresses. This variation in thickness can range from a simple fillet in the corners to a profile of the beam type with variable section.

In Figure 4a, complementary arms 109 are shown in section, in phantom. These complementary arms 109 connect the central part 106 to the annular edge 104, at the bottom of the bearing 100, namely on the side of the hole 107 through which the pin 21 is introduced.

[0050] Figures 5a and 5b show a fifth and a sixth embodiment with a central part 106 similar to that of the first embodiment, with the difference that the shank ends in a rounded profile. It shows the two series of protrusions 107b of the wall of the blind hole 107. Figures 6a and 6b show a partial sectional view of the bearing 100 showing the central part 106 according to the fifth embodiment, respectively according to section A-A and B-B of Figure 5a. Thus, in FIG. 6a, we find the three hemispherical protrusions 107b of the bottom wall of the blind hole 107, in contact with the rounded end of the shank 21. In FIG. 6b, the cut is made in the middle part of the height of hole 107 and there are eight hemispherical protuberances 107b from the side wall of blind hole 107, 2 of which contact shank 21 (indicated by symbol 107b' in Figure 6b).

[0051] In FIG. 5a, exposure by femtosecond laser of a zone of the elastic members results in a modification of the local volume of the material. In this figure, an example of an exposed zone is shown by the shaded portion 1008. This local change in the material can lead to a modification of the local elastic properties. Depending on the orientation and location of the stresses or prestresses in the elastic members 108, it is also possible to modify the linearity of their response to displacements, by favoring for example a different response to small displacements from the response to large ones. displacements.

This structural modification can be carried out in an additional step prior to the etching of the bearing 100, if the exposed areas do not extend to the surface of the bearing, so as not to expose these areas to the chemical agent. etching, the exposure parameters of this modified zone 1008 of the bearing 100 however varying from the exposure parameters of the zone to be removed to obtain the geometry of the bearing. This operation can also take place at any time subsequent to the cutting of the bearing by the method described above.

In Figure 5b, a variant of the first embodiment is proposed, again with elastic members 108 extending over a length greater than the length available between the annular edge 104 and the central part 106, the distribution of this geometry in space being chosen in a form reminiscent of an accordion.

Reference is made to Figures 7 and 8 showing in perspective a possible bearing geometry for the variant of the fifth embodiment. In FIG. 7, this bearing 100 is seen from its face through which rod 21 (not shown in FIGS. 7 and 8) is introduced. We find there the hole 103, the blind hole 107 equipped with protrusions 107b, the annular border 104, the base 102 and the arms 108 forming wavy radial blades between the central part 106 and the border 104.

In Figure 8, this bearing 100 is shown from the other face of the bearing, the hole 107 for introducing the rod 21 then being hidden by its bottom wall.

Figure 9 shows in sectioned perspective a possible geometry of the bearing 100 for a variant partially similar to the first embodiment. Figure 10 shows an unsectioned detail of the bearing in Figure 9.

According to the third embodiment (FIG. 4a), the protrusions 107b, or more generally the zones of the wall of the hole 107 of the central pivot in contact with the shank 21, have a surface with a submicron structuring controlled 107d. By the expression "controlled submicron structuring" is meant a structuring fabricated voluntarily on the surface of the wall of the hole 107, by structuring means, the structuring means being in this case directly those of the initial etching process of the bearing, and these controlled submicron structurings 107d can be produced during the initial cutting of the bearing, or in a subsequent step. Indeed, one of the properties of exposure to a femtosecond laser resides in etchings which can be much smaller than the diameter of the beam which generates them, controlled submicronic structurings 107d are achievable on the surface of the material. Alternatively, the controlled submicron structuring can be machined by a DLIP (Direct Laser Interference Patterning) method. The controlled submicron structuring 107d makes it possible to improve at least locally the tribological properties between the wall of the hole 107 and the rod 21. The controlled submicron structuring 107d also makes it possible to vary the wettability of the surface of the wall of the hole 107. Indeed , some structures can be dimensioned so as to take on an oleophilic function 107d′, to retain the oil, while others can be dimensioned so as to take on an oleophobic function 107d″, to prevent the spreading of the oil. The variation of the contact voltages obtained can advantageously supplement, or even replace, other types of solutions aiming for a similar effect, such as for example an epilame treatment.

Such a structuring of the surface is specifically controlled, unlike the structures corresponding to the intrinsic roughness of a surface in its natural state or after a manufacturing step (for example engraving) for shaping the core of the material. For this, structures are formed on the surface by a step of shaping the surface which allows control of their geometry (height, width, angle of inclination, general shape), of their distribution and of their density. These structures can have different polarities with respect to the surface, i.e. they can be pillar/hill shaped (positive polarity) or hole/valley shaped (negative polarity). For example, the surface of the wall of the hole comprises a coating made of a material different from the material of the substrate, and having more favorable tribological properties than the material of the substrate.

This controlled submicronic structuring is achieved by adapting the surface and depth dimensions of the asperities obtained according to the dynamic and geometric characteristics of the shaft 20 guided by the bearing 100. Without departing from the invention, the different types of structuring proposed 107b, 107c and 107d, 107d' and 107d" can be combined with one another.

According to another embodiment, the surface of the wall of the hole 107 comprises a coating made of a material different from the material of the substrate, and having more favorable tribological properties than the material of the substrate. For example, such a coating is obtained by a growth process, in particular an epitaxial growth process.

In one embodiment which can be combined with any one of the preceding embodiments, one or more surfaces of the bearing 100 are polished by a local reworking operation of the material, known by the term "laser polishing". “. In fact, by exposure to a laser beam having different properties (wavelength, energy level, frequency and duration of the pulses) from the beams used for the previous operations, it is possible to remelt the surface material.

[0062] This polishing operation by recasting the material, makes it possible on the one hand to reduce the roughness very significantly. Indeed, by remelting the material on the surface, the roughness ridges are flattened to fill the roughness, which offers a very smooth surface but also respecting the nominal dimensions as well as possible, since there is no material removal. unlike conventional polishing operations. The polishing operation by overhaul thus makes it possible to improve the tribological properties of the zones in contact with the pivot 21 that it receives. The polishing operation by recasting also makes it possible to reduce or eliminate microcracks or other defects on the surface of the bearing 100, which, in the case of fragile materials such as glass for example, reinforces the resistance of the bearing, in particular of its elastic organs.

[0063] This polishing by remelting can be carried out by exposure to a carbon dioxide laser, a carbon monoxide laser, or any other source making it possible to achieve the same goal.

The bearing 100 of the invention can be integrated into a watch component having at least one additional function.

Reference numbers used in the figures

[0065] P Pivot axis, bearing axis 20 Timepiece shaft 21 Pivot, shank 21a End of the pivot (shank) 100 Bearing 102 Base 103 Hole 104 Edge 106 Central part 107 Hole 107a Guide surface 107b Protrusions 107c Wall 107d submicron structuring 107d' oleophilic submicron structuring 107d'' oleophobic submicron structuring 108 Arm 108' Arm 108'' Arm 108''' Arm 1008 Exposed area of arm 109 Complementary arm 110 Recess 111 Span 112 Fillet

Claims (25)

1. Bearing (100) for a timepiece, produced in a single block in a substrate transparent to the wavelength of a laser, and comprising a central part (106) delimiting a hole (107) intended to guide a rod (21), the hole (107) comprising a guide surface (107a) characterized in that that at least a portion of the guide surface (107a) comprises a structured contact surface (107a-107d), intended to come into contact with the shank (21) that it guides, the structured contact surface offering surfaces preferred contact surfaces, so that the extent of the contact surfaces between the shaft and the pivot is reduced. 2. Bearing (100) according to claim 1, in which the structuring of the structured contact surface has a height exceeding 20% of the diameter of the hole (107). 3. Bearing (100) according to one of claims 1 or 2, wherein the hole (107) is a blind hole terminated by a wall. 4. Bearing (100) according to the preceding claim, in which the geometry of the wall terminating the hole (107) can be a plane, a surface of revolution or a faceted surface. 5. Bearing (100) according to one of the preceding claims, wherein the guide surface (107a) comprises a plurality of protrusions (107b) each forming contact with at least one surface of the pin (21) that it receives. 6. Bearing (100) according to the preceding claim, wherein said contact is a point or linear contact. 7. Bearing (100), according to the preceding claim, wherein said protrusions (107b) have a capillary effect retaining a film of oil around the point of contact with the rod (21). 8. Bearing (100) according to one of claims 5 to 7, wherein the protrusions are distributed over at least one plane orthogonal to the axis (P) of the hole (107). 9. Bearing (100) according to the preceding claim, wherein the protrusions are dimensioned and distributed in such a way that they generate controlled friction torques on the rod (21). 10. Bearing (100) according to one of the preceding claims, wherein said hole (107) is an olive-shaped hole. 11. Bearing (100) according to one of the preceding claims, wherein the wall of the hole of the central pivot in contact with the shank of the bearing (100) has a controlled submicron structuring. 12. Bearing (100) according to claim 11, in which the controlled submicron structuring makes it possible to confer on the surface an adequate wettability, the submicron structuring taking on at least one oleophilic function or one oleophobic function or certain structurings taking on an oleophilic function and others an oleophobic function. 13. Bearing (100) according to one of the preceding claims, wherein the surface of the wall of the hole comprises a coating made of a material different from that of the substrate. 14. Bearing (100) according to one of the preceding claims, further comprising elastic members (108, 108', 108", 108'") allowing translation of the central part (106) along at least one axis (P ). 15. Bearing (100) according to the preceding claim, in which the bearing comprises a rim (104) and the elastic members (108, 108', 108'', 108''') are arranged between the central part (106) and the edge (104) of the bearing (100), so that the bearing (100) has a shock absorbing function. 16. Bearing (100) according to the preceding claim, in which the elastic members (108, 108', 108'', 108'''') are formed beyond a single plane. 17. Bearing (100) according to one of claims 14 to 16, wherein the elastic members (108, 108', 108'', 108'''') locally comprise a modified structure so that the elastic properties and/or or dimensions of the latter are modified. 18. Bearing (100) according to one of the preceding claims, made of a material chosen from quartz, natural or synthetic ceramics, glasses, glass ceramics, silica, composites and polymers. 19. Bearing (100) according to one of the preceding claims, made of a non-metallic material which has a hardness greater than 1200 Hv. 20. Watch component (100) in which the bearing according to one of claims 1 to 19 is integrated. 21. Timepiece comprising a bearing (100) according to one of claims 1 to 19. 22. Process for manufacturing the bearing (100) according to one of claims 1 to 19, comprising the steps of: modifying the structure of at least one zone of the substrate by exposure to a femtosecond laser, said substrate being transparent to said femtosecond laser; And removing the modified zone from the substrate by means of a chemical agent suitable for dissolving the material of the substrate modified by said femtosecond laser more rapidly than the material whose structure is not modified so as to directly obtain said bearing (100). 23. A method according to claim 22, wherein the step of removing the modified area from the substrate comprises chemical etching. 24. Method according to claim 22 or 23, in which at least one surface of the bearing is exposed to a polishing operation by localized remelting of the material. 25. Method according to the preceding claim, in which the polishing by remelting is carried out by exposure to a carbon dioxide or carbon monoxide laser.