Method for manufacturing a watch bearing

Abstract

A method for manufacturing a pivot bearing (1), in particular a pivot jewel, for pivoting a clock part (2) is disclosed, characterized in that it comprises the following steps: drilling (E1) a hole (10a) in a blank (1a) of the bearing (1) along an axis (A1) intended for the pivoting of the clock part (2), the hole (10a) forming a starting point (13a) of a first pivot zone (13) of the bearing (1); subsequently laser engraving (E2) in the blank (1a), in particular using a femtosecond laser, a second clearance zone (14) of the bearing (1) juxtaposed with the starting point (13a) of the first pivot zone (13), the second clearance zone (14) of the bearing (1) opening at a first face (11a) of the blank (1a) of the bearing (1); subsequently removing material by grinding (E3), in particular by olive-shaped cutting, at the starting point (13a) of the first pivot zone (13) of the bearing (1) and at a boundary zone (14a) between the starting point (13a) of the first pivot zone (13) of the bearing (1) and the second clearance zone (14) of the bearing (1), so as to form the first pivot zone (13) and the second clearance zone (14) of the bearing (1) juxtaposed and connected to each other by a circular connection part.

Description

Field of the Invention

[0001] The present invention relates to a method for manufacturing a pivot bearing for pivoting a watch part, in particular a pivot jewel. The invention also relates to a pivot bearing obtained by this method, an assembly including such a bearing, and a movement including such a bearing or such an assembly. The invention finally relates to a timepiece, in particular a watch, including such a movement, such an assembly, or such a bearing. Background Art

[0002] The regularity of the pivoting of an axis, in particular the balance staff in an anti-shock device, is a key factor in the timekeeping performance of a watch. In fact, any change over time (such as wear of the pivot or its damage due to an impact) will cause a change in the performance of the oscillator, which will cause a change in the operation of the watch.

[0003] Various geometries of pierced jewels (also called bearings) sold on the market by jewel suppliers are known. These geometries are specified in particular by the following items: flat jewels with an oval or cylindrical hole, support jewels with an oval or cylindrical hole, semi-flat jewels with an oval or cylindrical hole, flat jewels with an oval or cylindrical hole and two recesses, hemispherical jewels with an oval or cylindrical hole.

[0004] These jewels can be assembled in a combination device and an anti-shock device.

[0005] The jewel includes a hole that may or may not be oval-cut, allowing the pivot of the axis to pivot against a pivoting surface. In the case of jewels particularly considered for assembly in a combination device and an anti-shock device, the hole generally includes a recess on the first face of the jewel, on the side where the pivot is introduced, to facilitate its insertion. These jewels thus include a generally flat first face with a recess, and a flat or hemispherical face opposite the recess. In the jewels of the prior art, it is easy to distinguish between the recess and the pivoting zone or surface, and these two parts are separated by a generally clear edge. This clear edge causes problems during the insertion of the pivot, as the pivot will abut against the edge and be scratched by contact with it.

[0006] As disclosed in documents EP2778801 and EP3483665, it is known to use a pressing technique to obtain sintered jewels based on ceramics.

[0007] The bearing geometries known from document EP2778801 include: a substantially spherical opening which forms a first functional element and has a portion with a maximum diameter greater than 4.5 times the minimum diameter of the hole; and a substantially conical opening which forms a second functional element and has a portion with a maximum diameter substantially twice the minimum diameter of the hole. The purpose of the olive shape at the level of the hole is to minimize the contact of the pivot but also to assist with any lubrication.

[0008] Also found in document EP3483665 is a pierced gemstone geometry which includes a functional element forming a joining cone of the pierced gemstone. The geometry of this functional element meets the need to assist in the installation of a pivot blind hole, especially in seismic devices. However, this sintered gemstone is opaque and does not have the transparent characteristics like a ruby.

[0009] Obviously, the existing methods for manufacturing pivot bearings are not optimal and / or cannot manufacture all shapes and / or cannot manufacture all the materials that can be envisioned for such bearings. Summary of the Invention

[0010] The object of the present invention is to provide a solution that can optimize the manufacture of pivot bearings and can improve the deficiencies of the prior art.

[0011] For this purpose, the present invention is based on a method for manufacturing a pivot bearing, especially a pivot gemstone, for pivoting a clockwork part, which includes the following steps:

[0012] - Drilling a hole in the blank of the bearing along the axis for pivoting the clockwork part, which hole forms the starting point of the first pivot zone of the bearing; subsequently

[0013] - Laser engraving, especially using a femtosecond laser, a second clearance zone of the bearing juxtaposed to the starting point of the first pivot zone in the blank, the second clearance zone of the bearing being open at the first face of the blank of the bearing; subsequently

[0014] - Removing material by grinding, especially by olive-shaped cutting, at the starting point of the first pivot zone of the bearing and at the boundary zone between the starting point of the first pivot zone of the bearing and the second clearance zone of the bearing, so as to form the juxtaposed first pivot zone and second clearance zone of the bearing which are connected to each other by a circular connection.

[0015] The step of drilling the hole may include the sub-step of obtaining a blank disposed between a first face of a plane and a second face of an opposite plane, followed by the sub-step of drilling a through-hole in a direction perpendicular to the first face.

[0016] The step of laser engraving the second clearance zone of the bearing may include a plurality of consecutive sub-steps, each sub-step including engraving the blank of the bearing in at least one plane different from the engraving of the previous sub-step.

[0017] The different planes of the plurality of successive sub - steps can be planes parallel to each other and substantially parallel to the first face of the blank, and they can overlap each other and extend between the first face of the blank and an intermediate plane within the thickness of the blank of the bearing.

[0018] Each sub - step in the laser engraving step can employ engraving circumscribed by a circular profile centered on the axis of the hole in a new different plane, such that the steps included in the laser engraving result in a second clearance zone formed by engraving overlapping discs in different planes, the diameter of the discs decreasing between the upper face and the intermediate plane, and the engraving diameter in the intermediate plane being substantially equal to the diameter of the hole.

[0019] The distance between two successive planes among the different planes can be less than or equal to 2 μm, or less than or equal to 1 μm.

[0020] The step of laser - engraving the second clearance zone of the bearing can employ engraving of a surface having some or all of the following characteristics:

[0021] - The second clearance zone forms a continuous diffused or expanded portion without an edge from the first pivot zone of the bearing to the first face of the bearing;

[0022] - The second clearance zone has a generally frustoconical form of a frustum of a cone, which is flat or has an arcuate surface, especially having an infinite radius of curvature near the first face;

[0023] - The maximum diameter of the second clearance zone is greater than 4 times or 7 times the minimum diameter of the first pivot zone;

[0024] - The maximum cross - sectional area of the second clearance zone is greater than 10 times or 25 times or 30 times or 50 times the minimum cross - sectional area of the first pivot zone;

[0025] - The first volume defined by the first pivot zone and two planes perpendicular to the axis and passing through the edges of the first pivot zone with respect to the axis is less than 0.4 times or 0.35 times or 0.3 times or 0.25 times the second volume defined by the second clearance zone and two planes perpendicular to the axis and passing through the edges of the second clearance zone with respect to the axis, and / or the first volume defined by the first pivot zone and two planes perpendicular to the axis and passing through the edges of the first pivot zone with respect to the axis is greater than 0.1 times or 0.15 times or 0.2 times the second volume defined by the second clearance zone and two planes perpendicular to the axis and passing through the edges of the second clearance zone with respect to the axis;

[0026] - The intersection curve of the plane passing through the axis and perpendicular to the face of the second clearance zone is convex.

[0027] The step of removing material by grinding can use a diamond wire.

[0028] The step of drilling a hole in the blank of the bearing can use a broaching tool or a laser.

[0029] The step of drilling a hole in the blank of the bearing can include extended sub-steps, including imparting a diameter to the hole that is substantially equal to the minimum diameter of the first pivot region of the bearing.

[0030] The method for manufacturing a bearing can include the step of turning the outer diameter of the bearing.

[0031] The method for manufacturing a bearing can include a finishing step of polishing or grinding, in particular reducing the roughness of the second clearance region of the bearing.

[0032] The method for manufacturing a bearing can include the step of rounding the second face of the blank opposite to the first face, thereby forming a hemispherical second face of the bearing, and optionally forming a third clearance region in the extension of the hole in the blank at the level of the second face.

[0033] The method for manufacturing a bearing can include the step of texturing some or all parts of the second clearance region and / or some or all parts of the third clearance region, in particular using a femtosecond laser, such that the first pivot region has a different roughness from the second clearance region and / or such that the first pivot region has an oleophilic surface and the second clearance region has an oleophobic surface as a whole or in part.

[0034] The blank can be made of synthetic ruby or polycrystalline corundum or a ceramic such as zirconia, in particular yttrium-stabilized zirconia, or single-crystal alumina or an alumina-zirconia composition.

[0035] The present invention also relates to a pivot bearing, in particular a pivot jewel, for pivoting a clock part, the bearing including a hole for pivoting the clock part about an axis along the axis and having at least:

[0036] - a first pivot region of the clock part; and

[0037] - a second clearance region extending from the first face of the bearing to the first pivot region, the first face being perpendicular or substantially perpendicular to the axis and adapted to be oriented on the side of the clock part, the first pivot region and the second clearance region being connected to each other by a connecting rounding (circular connecting portion).

[0038] The maximum diameter of the second clearance region can be greater than 4 times or 7 times the minimum diameter of the pivot region.

[0039] The maximum cross-sectional area of the second clearance region can be greater than 10 times or 25 times or 30 times or 50 times the minimum cross-sectional area of the first pivot region.

[0040] The first volume defined by the first pivot region and two planes perpendicular to the axis and passing through the edges of the first pivot region relative to the axis may be less than 0.4 times, or 0.35 times, or 0.3 times, or 0.25 times the second volume defined by the second clearance region and two planes perpendicular to the axis and passing through the edges of the second clearance region relative to the axis, and / or the first volume defined by the first pivot region and two planes perpendicular to the axis and passing through the edges of the first pivot region relative to the axis is greater than 0.1 times, or 0.15 times, or 0.2 times the second volume defined by the second clearance region and two planes perpendicular to the axis and passing through the edges of the second clearance region relative to the axis.

[0041] The second clearance region may have a frustoconical or generally frustoconical shape.

[0042] The second clearance region may be such that the intersection curve of the plane passing through the axis and the second clearance region is convex.

[0043] The first pivot region may be olive-shaped cut.

[0044] The first pivot region may have a different roughness from the second clearance region and / or the first pivot region may have an oleophilic surface and the second clearance region has an oleophobic surface as a whole or in part.

[0045] The present invention also relates to an assembly, in particular a device or a plate or a bridge plate or a seismic isolation device, which comprises the bearing described above.

[0046] The present invention also relates to a watch movement, which comprises the bearing described above.

[0047] The present invention also relates to a watch, in particular a table clock, in particular a wristwatch, which comprises the bearing described above.

[0048] The surface is more particularly defined by the claims. Description of the Drawings

[0049] These objects, features and advantages of the present invention will be disclosed in detail in the following non-limiting description of a specific embodiment with reference to the accompanying drawings, in which:

[0050] Figure 1 is a schematic view of a first embodiment of a watch comprising a bearing according to the present invention.

[0051] Figure 2 is a schematic view of a first watch embodiment further comprising a watch component pivoting in the bearing.

[0052] Figures 3 - 7 represents the steps of a method for manufacturing a pivot bearing according to an embodiment of the present invention.

[0053] Figure 8 Schematic representation of a flowchart of a method for manufacturing a pivot bearing according to an embodiment of the present invention. Detailed implementation

[0054] Hereinafter, reference is made to Figure 1 and 2 Describe an embodiment of the timepiece 300 according to the present invention. The timepiece 300 is, for example, a watch, such as a wristwatch.

[0055] The timepiece includes a timepiece movement 200. The timepiece movement 200 is, for example, a mechanical movement, particularly an automatic movement. Alternatively, the movement may be an electronic movement.

[0056] The timepiece movement 200 includes a component 100, which includes a pivot bearing 1, hereinafter simply referred to as bearing 1. The bearing is capable of guiding the rotation or pivoting of the timepiece component 2. The bearing is thus capable of receiving and guiding the pivot of the timepiece component relative to the axis A1. The component preferably includes an axis that itself includes at least a pivot.

[0057] For a bearing including a hole and a mating recess or cone, the hole may be defined as the part of the jewel that contacts the pivot to allow it to pivot during normal operation. The diameter of the hole thus substantially corresponds to the diameter of the pivot, disregarding tolerances and clearances.

[0058] For example, the timepiece component is the balance wheel assembly of a balance-spring type oscillator. The "balance wheel assembly" refers to an assembly including a balance wheel and an axis, and the balance wheel is mounted on the axis, particularly fixed to the axis by staking.

[0059] For example, the component 100 may include a timepiece shock protection device. Such a shock protection device may include an in-setting, a bearing 1, a cap jewel, and a spring. The bearing is thus a bearing for a pivot jewel or a pivot jewel type bearing. Alternatively, the component 100 may include a bridge plate, such as a plate or a balance wheel bridge plate to which the bearing 1 is fixed by staking.

[0060] The bearing 1 includes a hole 10 along the axis A1 for pivoting the timepiece component 2 relative to the axis A1. The axis A1 is thus the pivot axis of the timepiece component 2.

[0061] The bearing 1, particularly the hole 10, is at least provided with:

[0062] - A first pivot region or surface 13 of the timepiece component 2; and

[0063] - A second clearance region or surface 14 extending from the first face 11 of the bearing to the first pivot region 13.

[0064] The first face 11 is perpendicular or substantially perpendicular to the axis A1 and is oriented on the side of the timepiece component 2.

[0065] The first pivot region 13 and the second clearance region 14 are connected to each other without an edge and are connected by a connecting rounding.

[0066] The bearing is preferably a gemstone or a jewel. The gemstone is preferably made of synthetic ruby, i.e., polycrystalline corundum. Alternatively, the gemstone can be made of any other ceramic, such as zirconia, especially yttrium-stabilized zirconia, or single-crystal alumina, or an alumina-zirconia composition.

[0067] The bearing preferably includes a third clearance region or surface 15 extending from the second face 12 of the bearing to the first pivot region 13.

[0068] The second face 12 of the bearing is the face opposite to the first face 11. The first face and the second face are parallel or substantially parallel. They are each perpendicular or substantially perpendicular to the axis A1. In the illustrated embodiment, the first face is planar and the second face is hemispherical (protrusion). The first face can alternatively be hemispherical. The second face can alternatively be planar.

[0069] The second clearance region is the region in the bearing that engages with the pivot of the timepiece component 2, especially the timepiece component 2.

[0070] The third clearance region is the region opposite to the second clearance region with respect to the first pivot region, and the pivot of the timepiece component 2, especially the timepiece component 2, can project therein after being disposed in the bearing.

[0071] The bearing preferably has a shape that rotates around the axis A1. In particular, the hole preferably has a shape that rotates around the axis A1. Alternatively, only the first pivot region of the hole can have a shape that rotates around the axis A1. As another alternative, only the first pivot region and the second clearance region of the hole can have a shape that rotates around the axis A1 or only the first pivot region and the third clearance region of the hole can have a shape that rotates around the axis A1.

[0072] The first pivot region 13 is advantageously olive-shaped cut.

[0073] As described above, there is no visually perceptible boundary, such as an edge or a ridge, between the first pivot region 13 and the second clearance region 14. In fact, the bearing walls or surfaces defining these regions are connected to each other by connecting rounding portions or are connected to each other without forming an edge. Thus, the direction of the plane tangent to the surface of the hole does not break or suddenly change direction as the plane moves across the first pivot region and the second clearance region in the hole. In particular, the direction of the plane tangent to the surface of the hole does not break or suddenly change direction as the plane moves from any point in the first pivot region to any point in the second clearance region in the hole. In other words, the intersection curve of the plane passing through the axis A1 and perpendicular to the face (11) of the bearing, which defines the walls of the first pivot region and the second clearance region, does not produce any corner points at the junction between the first pivot region and the second clearance region, or does not produce corner points throughout their entire extent. The minimum radius of curvature of the wall or surface of the hole 10 at the junction between the first pivot region and the second clearance region or the minimum radius of curvature of the connecting rounding portion is preferably greater than 0.05 mm. The minimum radius of curvature of the surface of the first pivot region is more preferably greater than 0.05 mm.

[0074] A part of the connecting rounding portion forms a part of the first pivot region, and another part of the connecting rounding portion forms a part of the second clearance region.

[0075] The boundary between the first pivot region and the second clearance region is arbitrarily defined, for example, at a position where the diameter of the hole (measured perpendicular to the axis A1) is equal to 1.1 times the minimum diameter d of the first pivot region or the hole 10 t (measured perpendicular to the axis A1). Alternatively, the boundary between the first pivot region and the second clearance region is defined at a position where the cross-sectional area of the hole (measured perpendicular to the axis A1) is equal to 1.2 times the minimum cross-sectional area of the first pivot region or the hole 10 (measured perpendicular to the axis A1). This boundary is marked as 16 in Figure 1 the figure. As another alternative, the boundary between the first pivot region and the second clearance region is defined at a position where the diameter of the hole is equal to 140% of the nominal diameter at half the height of the pivot (including the axis of the pivot being stationary). Here, the term "pivot" refers to only the part of the shaft that is provided for pivoting the shaft in the bearing.

[0076] The second clearance zone has an expanded geometry. The second clearance zone forms a dilation or diffusion part from the first pivot zone to the first face 11. The second clearance zone 14 preferably has a frustoconical or substantially frustoconical shape. The second clearance zone preferably includes an arcuate surface with a radius of curvature approaching infinity. In a complementary manner, the second clearance zone may equally have a frustoconical or substantially frustoconical cross-section. Alternatively, the second clearance zone may have a frustoconical or substantially frustoconical cross-section. The geometry of the second clearance zone maximizes the distance between the bearing and the watch component outside the first pivot zone and helps to return the pivot to the first pivot zone when the pivot moves away from the first pivot zone in the case of an impact on the wearer.

[0077] The intersection curve of the plane passing through the axis A1 and perpendicular to the face 11 of the bearing of the wall defining the second clearance zone is preferably convex. "Convex" means that any straight line segment connecting any two points of the curve lies within the material forming the bearing.

[0078] The maximum diameter d of the second clearance zone 14 e (measured perpendicular to the axis A1) is preferably greater than 4 times or 7 times the minimum diameter d t (measured perpendicular to the axis A1) of the first pivot zone 13 or the hole 10.

[0079] The maximum cross-sectional area of the second clearance zone 14 (measured perpendicular to the axis A1) is more preferably greater than 10 times or 25 times or 30 times or 50 times the minimum cross-sectional area (measured perpendicular to the axis A1) of the first pivot zone 13 or the hole 10.

[0080] The first volume defined by the first pivot zone 13 and two planes P2, P3 perpendicular to the axis A1 and passing through the edges of the first pivot zone 13 relative to the axis A1 is preferably less than 0.4 times or 0.35 times or 0.3 times or 0.25 times the second volume defined by the second clearance zone 14 and two planes P1, P2 perpendicular to the axis A1 and passing through the edges of the second clearance zone relative to the axis A1. The first volume defined by the first pivot zone 13 and two planes P2, P3 perpendicular to the axis A1 and passing through the edges of the first pivot zone 13 relative to the axis A1 is greater than 0.1 times or 0.15 times or 0.2 times the second volume defined by the second clearance zone 14 and two planes P1, P2 perpendicular to the axis A1 and passing through the edges of the second clearance zone relative to the axis A1.

[0081] The second volume more advantageously constitutes at least 65% or at least 70% or at least 80% of the third volume defined by the surface of the hole and two planes P1, P4 perpendicular to the axis A1 and passing through the edges of the hole relative to the axis A1.

[0082] The first pivot region 13 may advantageously have a different roughness from the second clearance region 14. More particularly, the first pivot region may have an oleophilic surface while the second clearance region may have an oleophobic surface, either wholly or in part. These roughnesses or structures may be obtained by surface texturing or treatment, preferably by surface texturing using a femtosecond laser. These roughnesses or textures may be obtained directly during the machining of the various regions or after complementary finishing steps.

[0083] In one embodiment, the diameter d t is 0.076 mm and the diameter d e is 0.555 mm. The position of the minimum diameter d t that includes the first pivot region or hole 10 may or may not constitute the middle of the pivot region 13. The plane P5 that is perpendicular to the axis A1 and passes through the position that includes the diameter d t may more particularly be set to be equidistant or non - equidistant from the planes P2 and P3.

[0084] If present, the third clearance region 15 may have an expanding geometry. It may form an expansion or diffusion part from the first pivot region to the second face 12. The third clearance region 15 preferably has a frustoconical or substantially frustoconical shape.

[0085] There need not be any visually perceptible boundary, such as an edge or ridge, between the first pivot region 13 and the third clearance region 15. In fact, the bearing surfaces that define these regions may advantageously be connected to each other by connecting rounding portions or connected to each other without forming an edge. Thus, the direction of the plane that is tangent to the surface of the hole does not interrupt or suddenly change direction when the plane moves across the first pivot region and the third clearance region in the hole. In particular, the direction of the plane that is tangent to the surface of the hole does not interrupt or suddenly change direction when the plane moves from any point in the first pivot region to any point in the third clearance region in the hole. In other words, the intersection curve of the plane that passes through the axis A1 and is perpendicular to the face 11 of the bearing 1 and that defines the walls of the first pivot region and the third clearance region does not produce any corner points at the junction between the first pivot region and the third clearance region, or does not produce corner points throughout their entire extension. The minimum radius of curvature of the surface of the hole 10 at the junction between the first pivot region and the third clearance region or the minimum radius of curvature of the connecting rounding portion is preferably greater than 0.05 mm.

[0086] A part of the connecting rounding portion forms a part of the first pivot region, and another part of the connecting rounding portion forms a part of the third clearance region.

[0087] The boundary between the first pivot region and the third clearance region, for example, according to the diameter of the hole (measured perpendicular to the axis A1), is equal to the minimum diameter d of the first pivot region or the hole 10 tis arbitrarily defined at a position 1.02 times (measured perpendicular to axis A1). Alternatively, the boundary between the first pivot region and the third clearance region is defined, for example, according to the position where the cross-sectional area of the hole (measured perpendicular to axis A1) is equal to 1.04 times the minimum cross-sectional area of the first pivot region or hole 10 (measured perpendicular to axis A1). This boundary is marked as 17 in Figure 1 and is labeled 17 in

[0088] As described above, the pivot bearing 1 having the specific geometry referred to above in Figure 1 and 2 is such that it minimizes the risk of damage to the pivot during its insertion into the bearing. Such a bearing can advantageously be made of synthetic ruby, enabling it to have transparent properties, thus assisting the insertion of the pivot.

[0089] The present invention is based on a method for manufacturing a pivot bearing, in particular suitable for manufacturing the bearing described above. Figure 8 A flowchart schematically showing the steps of such a manufacturing method according to an embodiment of the present invention is shown. Of course, the same method remains applicable for manufacturing any other pivot bearing and continues to provide high performance.

[0090] The method includes a first step E1 of drilling a hole 10a in a blank 1a of the bearing 1 along an axis A1 for pivoting a clockwork part 2. This step is carried out by Figure 3 as shown. The hole 10a allows the formation of the starting point 13a of the first pivot region 13 described above.

[0091] The method thus advantageously includes a preliminary sub-step of obtaining the blank 1a of the bearing. The blank 1a can advantageously take the form of synthetic ruby or polycrystalline corundum. Alternatively, it can take the form of any other ceramic, such as zirconia, in particular yttria-stabilized zirconia, or single-crystal alumina, or an alumina-zirconia composition. Furthermore, the blank 1a is advantageously provided between a first planar face 11a and a second planar face 12a opposite and parallel to the first face 11a. These two faces 11a, 12a of the blank 1a form the semi-finished faces 11, 12 of the bearing 1 to be formed later. They are located in planes P1, P2 respectively. The method finally includes a sub-step E11 of drilling the hole 10a. The hole 10a is advantageously a through-hole. It is oriented in a direction perpendicular to the two faces 11a, 12a. It is centered on the axis A1. It advantageously has a cylindrical shape. Drilling can be mechanically achieved by a broaching tool or a laser beam, in particular a femtosecond laser beam.

[0092] The first step optionally includes another extended sub-step E12, including forming the diameter of the hole 10a to be substantially equal to the minimum diameter d of the first pivot region 13 of the bearing 1 to be manufactured later tAlternatively, the same diameter d can be obtained only through the above-mentioned first sub-step. t 。

[0093] The first step may also optionally include another sub-step E13 of turning the outer diameter d of the blank 1a of the bearing 1. ext of the blank 1a of the bearing 1.

[0094] The method then includes a second step E2 of laser-engraving the second clearance zone 14 of the bearing 1 in the blank 1a, in particular using a femtosecond laser, as Figure 4 shown. This engraving is carried out at the level of the holes 10a drilled in the previous step. The second clearance zone 14 to be formed is juxtaposed with the starting point 13a of the first pivot zone 13. In addition, it opens at the level of the first face 11a of the blank 1a of the bearing 1.

[0095] The laser used in this second step is preferably a femtosecond laser. The latter generates ultrashort pulses, thus having no thermal effect on the material, and its wavelength is adjusted so as not to affect the material structure of the blank 1a. The laser beam 400 can be an infrared laser beam, in particular an infrared laser beam having a wavelength between 800 nm and 1100 nm (inclusive), in particular a wavelength of 1030 nm ± 5 nm, or a green laser beam, in particular a green laser beam having a wavelength between 500 nm and 540 nm (inclusive), in particular a wavelength of 515 nm ± 2.55 nm, or an ultraviolet laser beam, in particular an ultraviolet laser beam having a wavelength below 400 nm, in particular a wavelength of 343 nm ± 25 nm, or a blue laser beam, in particular a blue laser beam having a wavelength between 400 nm and 480 nm (inclusive). In addition, the laser beam can have an energy between 0.001 mJ and 2 mJ (inclusive), or between 0.004 mJ and 0.1 mJ (inclusive), or between 0.004 mJ and 0.05 mJ (inclusive). The laser beam can have a diameter between 5 μm and 100 μm (inclusive), preferably between 10 μm and 60 μm (inclusive) or between 15 μm and 30 μm.

[0096] According to this embodiment, step E2 of laser engraving the second clearance zone 14 of the bearing 1 includes a plurality of successive sub-steps, including engraving the blank 1a of the bearing 1 in a plurality of different planes P. In other words, each sub-step can be carried out by engraving in a new plane different from the previously engraved plane. In this sub-step, these previously engraved planes are optionally also subjected to complementary engraving, which therefore does not exclude engraving in a plurality of planes in the same sub-step. The different planes P are advantageously planes parallel to each other. The distance between two successive planes among the different planes P is preferably less than or equal to 2 μm, or less than or equal to 1 μm. They are also advantageously substantially parallel to the first face 11a of the blank 1a and overlap each other, extending between the first face 11a in the first plane P1 of the blank and the intermediate plane P5 within the thickness of the blank 1a of the bearing 1. This laser engraving step is therefore also advantageously carried out at the starting point 13a at the level of the subsequent first pivot zone 13, between the intermediate plane P5 and the above-mentioned plane P2 forming the boundary between the first pivot zone 13 and the second clearance zone 14. It thus forms a part 14a at the level of the boundary region located between the first pivot zone 13 and the second clearance zone 14. It also naturally forms the second clearance zone 14 itself between the two planes P1, P2.

[0097] Each sub-step in the second step E2 of laser engraving advantageously uses an engraving inscribed within a circular profile centered on the axis A1 of the hole 10a, the diameter of this circular profile being able to decrease between the upper face 11a (or plane P1) and the intermediate plane P5; the engraving diameter in the intermediate plane P5 can be substantially equal to the diameter of the hole 10a.

[0098] For greater precision, the second step E2 of laser engraving can include n sub-steps E2i (where 1 ≤ i ≤ n) in which the laser beam 400 passes through n planes P parallel or substantially parallel to the planes P1 and P5 and arranged between the planes P1 and P5. The laser beam more particularly passes through n surfaces circumscribed by circles with diameters d centered on the axis A1 at the level of each plane P arranged between the planes P1 and P5 i These sub-steps can be defined as follows:

[0099] - The first sub-step E21 can include passing the laser beam 400 substantially at the level of the plane P1. This first sub-step E21 more particularly includes moving the laser beam 400 along a predetermined trajectory on a surface circumscribed by a circle with an axis A1 and a diameter d1 = d e ;

[0100] - After the first sub-step E21, there are n - 2 sub-steps, in which the laser beam will move along a predetermined trajectory in n - 2 surfaces (where 1 < i ≤ n) with gradually increasing distances from the plane P1 and respectively set at the levels of n - 2 planes P according to a movement parallel or substantially parallel to the axis A1 until reaching the plane P5. In each plane P, the sub-step E2i may include moving the laser beam 400 along a predetermined trajectory on a surface circumscribing a circle with a diameter d having the axis A1 i where d t ≤d i ≤d e ;

[0101] - In the final sub-step E2n, the laser beam 400 moves along a predetermined trajectory at the level of the plane P5. This final sub-step E2n may more particularly include moving the laser beam 400 along a predetermined trajectory on a surface circumscribing a circle with a diameter d having the axis A1 n =d t .

[0102] It should be noted that the engraving performed in each plane has a smaller thickness, which is why it can be considered surface engraving, but this thickness is sufficient to form the volume of the engraving by superimposing all the engravings on a plurality of the above-mentioned surfaces.

[0103] In the above-described embodiment, each sub-step in the second step E2 of laser engraving advantageously employs an engraving inscribed in a circular trajectory centered on the axis A1 of the hole 10a, and the diameter of this circular trajectory decreases between the upper part 11a (or plane P1) and the intermediate plane P5; the engraving diameter in the plane P1 may be equal to the diameter d e and the engraving diameter in the intermediate plane P5 may be substantially equal to the diameter d t .

[0104] Alternatively, each sub-step in the second step E2 of laser engraving advantageously employs an engraving inscribed in a circular profile centered on the axis A1 of the hole 10a in a new plane P. Such sub-steps can be carried out simultaneously to supplement the engraving of the previously engraved plane. Thus, in each sub-step, the previously engraved plane can be engraved again on a surface inscribed in a circular profile with an increasing radius centered on the axis A1. The engraving diameter in each plane P that has been engraved thus increases in each sub-step. For example, the engraving in the plane P1 can increase in each sub-step, finally changing from the value d during the first sub-step t to the value d in the last sub-step e .

[0105] As another alternative, each sub-step in the second step E2 of laser engraving advantageously employs engraving inscribed in a circular profile centered on the axis A1 of the hole 10a, the diameter of which circular profile can arbitrarily vary between the value d t and d e In this case, as described above, the laser can engrave multiple planes P during one sub-step.

[0106] As described above, the distance between the planes P is adapted to obtain the most continuous finishing surface possible at the level of the walls of the second clearance zone 14.

[0107] Finally, the step E2 of laser engraving the second clearance zone 14 of the bearing 1 employs engraving of a surface having some or all of the following characteristics:

[0108] - The second clearance zone 14 forms a continuous and edge-free expansion or diffusion from the first pivot zone 13 of the bearing 1 (or from the starting point 13a of the first pivot zone 13) to the first face 11a of the bearing;

[0109] - The second clearance zone 14 has a substantially frustoconical shape in the form of a frustum of a cone with a surface including a flat or arcuate surface, particularly having an infinite radius of curvature near the first face 11a;

[0110] - The maximum diameter d of the second clearance zone 14 e is greater than 4 times or 7 times the minimum diameter d of the first pivot zone 13 t ;

[0111] - The maximum cross-sectional area of the second clearance zone 14 is greater than 10 times or 25 times or 30 times or 50 times the minimum cross-sectional area of the first pivot zone 13;

[0112] - The first volume (located between two planes (P2, P3) perpendicular to the axis A1) defined by the first pivot zone 13 is less than 0.4 times or 0.35 times or 0.3 times or 0.25 times the second volume (located between two planes (P1, P2) perpendicular to the axis A1) defined by the second clearance zone 14, and / or the first volume (located between two planes (P2, P3) perpendicular to the axis A1) defined by the first pivot zone 13 is greater than 0.1 times or 0.15 times or 0.2 times the second volume (located between two planes (P1, P2) perpendicular to the axis A1) defined by the second clearance zone 14;

[0113] - The cross-arc of the plane passing through the axis A1 and perpendicular to the face 11a or 11 with the second clearance zone 14 is convex.

[0114] The method then includes a third step E3 of removing material by grinding at the level of the starting point 13a of the first pivot region 13 of the bearing 1 and at the boundary region 14a between the starting point 13a of the first pivot region 13 of the bearing 1 and the second clearance region 14 of the bearing 1, so as to form, in juxtaposition, the first pivot region 13 and the second clearance region 14 of the bearing 1 that are connected to each other by connecting rounding portions. This third step E3 of removing material by grinding can be an olive-shaped cutting step, as Figure 5 and 6 shown.

[0115] For greater precision, the third step can include passing a diamond wire 500 through the hole 10a and moving the bearing blank 1a relative thereto, so as to adjust its cylindrical features by applying the shape of the final first pivot region 13 to the starting point 13a. This shape is sometimes referred to as an "olive" shape. When the second step is completed, the first pivot region 13 does not have any edges. The minimum diameter d is measured by considering a circle in the intermediate plane P5 having a diameter tangent to the closest wall of the first pivot region 13 t .

[0116] In a complementary manner, the diamond wire 500 also acts at least on the boundary portion 14a of the second clearance region 14 adjacent to the starting point 13a or the first pivot region 13. Thus, the first region 13 and the second region 14 are connected to each other without edges and / or are connected to each other by connecting rounding portions. These first region 13 and second region 14 thus form a continuous wall or a continuous surface due to the synergistic effect of two techniques, the first technique being laser engraving and the second technique being removing material by grinding.

[0117] The diamond wire 500 also acts on the connection portion of the hole 10a and the second face 12a of the blank 1a. This transition region located between the second face 12a and the first pivot region 13 forms the above-mentioned third clearance region 15. The first region 13 and the third region 15 are thus connected to each other without any edges and / or are connected to each other by connecting rounding portions due to this third step. The third clearance region 15 is provided in the blank 1a in the extension of the hole 10a and opens at the level of the second face 12a of the blank 1a of the bearing 1.

[0118] The method can then optionally include a fourth finishing step E4 by polishing or buffing, so as to obtain the finished bearing 1. Such a step can include polishing the bearing blank 1a with diamond polishing paste. This step can include different sub-steps aimed at minimizing the roughness of the bearing blank 1a, particularly on the walls and faces 11a, 12a of the second clearance region 14. One sub-step can be particularly provided for imparting a hemispherical appearance to the second face 12 of the bearing 1. Figure 7Shows the finally obtained pivot bearing 1 after the fourth finishing step E4 has been carried out and in particular after the above-mentioned sub-steps have been carried out. It should be noted that the bearing 1 subsequently includes a hole 10 defined by the surfaces of a plurality of regions 13, 14, 15 formed by means of the method according to the invention via an initial hole 10a in the blank, and this initial hole 10a thus itself forms a semi-finished product of the subsequent hole 10.

[0119] In an alternative embodiment of the method, the fourth finishing step E4 can be inserted between the second step E2 and the third step E3, and most importantly the third step E3 acts downstream of the second step E2.

[0120] It is also possible to provide an optional step E5 of texturing some or all parts of the clearance zone 14 and / or some or all parts of the clearance zone 15. This step is preferably carried out by means of a femtosecond laser. This step can act upstream or downstream of the finishing step E4.

[0121] Of course, the above method is particularly suitable for forming Figure 1 and 2 the pivot jewel shown, but is equally suitable for manufacturing any other watch bearing.

Claims

1. A method for manufacturing a pivot bearing (1) that pivots a clock component (2), which includes the following steps: - A hole (10a) is drilled (E1) in the blank (1a) of the bearing (1) along an axis (A1) intended for pivoting of the watch part (2), the hole (10a) forming the starting point (13a) of a first pivoting zone (13) of the bearing (1); subsequently - A second clearance zone (14) of the bearing (1) juxtaposed with the starting point (13a) of the first pivoting zone (13) is laser engraved (E2) in the blank (1a) using a femtosecond laser, the second clearance zone (14) of the bearing (1) opening at a first face (11a) of the blank (1a) of the bearing (1); Subsequently - Material is removed by grinding (E3) at the starting point (13a) of the first pivoting zone (13) of the bearing (1) and at a boundary zone (14a) between the starting point (13a) of the first pivoting zone (13) of the bearing (1) and the second clearance zone (14) of the bearing (1), thereby forming the juxtaposed first pivoting zone (13) and second clearance zone (14) of the bearing (1) connected to each other by a circular connection part.

2. The method for manufacturing a pivot bearing (1) according to claim 1, wherein, The step of drilling (E1) the hole (10a) includes a sub-step of obtaining the blank (1a) disposed between a first face (11a) of a plane and a second face (12a) of an opposite plane, followed by a sub-step of drilling a through-hole (10a) in a direction perpendicular to the first face (11a).

3. The method for manufacturing a pivot bearing (1) according to claim 1, wherein, The step of laser engraving (E2) the second clearance zone (14) of the bearing (1) includes a plurality of consecutive sub-steps, each sub-step including engraving the blank (1a) of the bearing (1) in at least one plane different from the engraving of the previous sub-step.

4. The method for manufacturing a pivot bearing (1) according to claim 3, wherein, The different planes of the plurality of consecutive sub-steps are parallel planes substantially parallel to the first face (11a) of the blank (1a), and they overlap each other and extend between the first face (11a) of the blank and an intermediate plane (P5) located within the thickness of the blank (1a) of the bearing (1).

5. The method for manufacturing a pivot bearing (1) according to claim 4, wherein, Each sub-step in the step of laser engraving (E2) employs engraving with a circular profile circumscribed about the axis (A1) of the hole (10a) in a new different plane, such that the steps included in the laser engraving (E2) result in the second clearance zone (14) formed by engraving overlapping discs in different planes, the diameter of the discs decreasing between the first face (11a) and the intermediate plane (P5), and the engraving diameter in the intermediate plane (P5) being substantially equal to the diameter of the hole (10a).

6. The method for manufacturing a pivot bearing (1) according to any one of claims 3 - 5, wherein, The distance between two consecutive planes among the different planes is less than or equal to 2 μm, or less than or equal to 1 μm.

7. The method for manufacturing a pivot bearing (1) according to any one of claims 1 to 5, wherein, The step of laser engraving (E2) the second clearance zone (14) of the bearing (1) employs engraving of a surface having some or all of the following characteristics: - The second clearance zone (14) forms a continuous diffusion or expansion portion without edges from the first pivot zone (13) of the bearing (1) to the first face (11a) of the bearing (1); - The second clearance zone (14) has a generally frustoconical shape in the form of a frustum of a cone, which is flat or has an arcuate surface; - The maximum diameter (d e ) of the second clearance region (14) is greater than 4 times or 7 times the minimum diameter (d t ) of the first pivot region (13); - The maximum cross-sectional area of the second clearance zone (14) is more than 10 times or 25 times or 30 times or 50 times the minimum cross-sectional area of the first pivot zone (13); - A first volume defined by the first pivot zone (13) and a second plane (P2) and a third plane (P3) perpendicular to the axis (A1) and passing through the edge of the first pivot zone relative to the axis (A1) is less than 0.4 times or 0.35 times or 0.3 times or 0.25 times a second volume defined by the second clearance zone (14) and a first plane (P1) and a second plane (P2) perpendicular to the axis (A1) and passing through the edge of the second clearance zone relative to the axis (A1), and / or the first volume defined by the first pivot zone (13) and the second plane (P2) and the third plane (P3) perpendicular to the axis (A1) and passing through the edge of the first pivot zone relative to the axis (A1) is more than 0.1 times or 0.15 times or 0.2 times the second volume defined by the second clearance zone (14) and the first plane (P1) and the second plane (P2) perpendicular to the axis (A1) and passing through the edge of the second clearance zone relative to the axis (A1); - The intersection curve of a plane passing through the axis (A1) and perpendicular to the first face (11a) with the second clearance zone (14) is convex.

8. The method for manufacturing a pivot bearing (1) according to any one of claims 1 to 5, wherein, The step of removing material by grinding (E3) uses a diamond wire.

9. The method for manufacturing a pivot bearing (1) according to any one of claims 1 to 5, wherein, The step of drilling (E1) the hole (10a) in the blank (1a) of the bearing (1) uses a broaching tool or a laser.

10. The method for manufacturing a pivot bearing (1) according to any one of claims 1 to 5, wherein, The step of drilling (E1) the hole (10a) in the blank (1a) of the bearing (1) includes an extended sub-step (E12) including imparting to the hole (10a) a diameter substantially equal to the minimum diameter (d t ) of the first pivot region (13) of the bearing (1).

11. The method for manufacturing a pivot bearing (1) according to any one of claims 1 to 5, wherein, It includes the step of turning (E13) the outer diameter (d ext ) of the bearing (1).

12. The method for manufacturing a pivot bearing (1) according to any one of claims 1 to 5, wherein, It includes a finishing or polishing step (E4) to reduce the roughness of the second clearance zone (14) of the bearing (1).

13. The method for manufacturing a pivot bearing (1) according to any one of claims 1 to 5, wherein, It includes a step of rounding the second face (12a) of the blank (1a) opposite to the first face (11a) to form the hemispherical second face (12a) of the bearing (1), and optionally forming a third clearance zone (15) in the extension of the hole (10a) in the blank (1a) at the level of the second face (12a).

14. The method for manufacturing a pivot bearing (1) according to claim 13, wherein, It includes a step of texturing (E5) some or all parts of the second clearance zone (14) and / or some or all parts of the third clearance zone (15) using a femtosecond laser, such that the first pivot zone (13) has a different roughness from the second clearance zone (14) and / or such that the first pivot zone (13) has an oleophilic surface and the second clearance zone (14) has an oleophobic surface in whole or in part.

15. The method for manufacturing a pivot bearing (1) according to any one of claims 1 to 5, wherein, The blank (1a) is made of synthetic ruby or polycrystalline corundum or ceramic or single crystal alumina or an alumina-zirconia composition.

16. The method for manufacturing a pivot bearing (1) according to claim 15, wherein, The ceramic is zirconia.

17. The method for manufacturing a pivot bearing (1) according to claim 16, wherein, The ceramic is yttrium-stabilized zirconia.

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