Method for polishing timepiece stone and device for carrying out said method

Abstract

Disclosed is a method for producing a pivot stone (1) for a timepiece movement (100), said pivot stone (1) comprising a pivot hole (5) having a first axis (A1) and capable of pivoting a timepiece component (98), such as a timepiece shaft, or about the timepiece component (98), said method comprising a first polishing step, in the first polishing step, (i) free abrasive particles (21), in particular diamond particles, rolling between the surface (6) of the pivot bore (5) to be polished and a polishing support (20) such as a wire (20) are used, and / or (ii) the pivot stone (1) is rotated about a first axis (A1) relative to the polishing support (20) held against the surface of the pivot bore (5) to be polished.

Description

Technical Field

[0001] The present invention relates to a pivot jewel for a timepiece movement. It also relates to a method for producing such a pivot jewel and a machine for polishing such a pivot jewel. It also relates to a method for determining the roughness of the surface of a pivot hole of such a pivot jewel. It also relates to a timepiece component including such a pivot jewel. It also relates to a timepiece movement including such a pivot jewel or such a timepiece component. Finally, it relates to a timepiece including such a timepiece movement, such a pivot jewel, or such a timepiece component.

[0002] The present invention also relates generally to a method for producing a component comprising a hole. The present invention also relates to:

[0003] - This kind of watch parts,

[0004] - a watch movement comprising such a watch component, and

[0005] - a timepiece comprising such a timepiece movement or such a timepiece component. Background Art

[0006] Watch jewels are crucial for the smooth functioning of a watch movement. Almost all rotational movement is performed by axles pivoting in bearings made of drilled ruby elements (also called functional jewels or pivot jewels).

[0007] To produce pivot stones, it is known to determine the size of the boule of material, in particular of synthetic ruby, more particularly of single-crystal synthetic ruby, by sawing, wire cutting or laser cutting into plates of a given thickness. These plates are then cut, for example by turning, to form blanks (preforms) of the stone that are given a cylindrical outer shape.

[0008] The gemstone is then drilled, for example, by laser or spindle, to obtain a rough pivot hole. The gemstone then undergoes an enlargement step, which achieves the final diameter and desired surface finish of the pivot hole. A subsequent turning step brings the gemstone to its nominal outer diameter. An optional grooving operation can create recesses on one or both faces of the gemstone to serve as lubrication channels. Finally, polishing brings the gemstone to its final thickness and desired surface finish. A possible final polishing achieves the desired outer surface finish. This polishing does not alter the surface finish of the pivot hole.

[0009] The enlargement step is crucial, as it determines not only the size of the pivot hole but also its surface finish. To achieve this, the gemstone is threaded onto a wire and secured together, allowing it to rotate about the axis of the pivot hole and process them in batches. The wire is typically conical in shape, its diameter gradually increasing to the target final diameter. The addition of abrasive and the reciprocating movement of the wire cause the hole to gradually enlarge until it reaches its final size. The rotational speed of the gemstone is significantly lower than the translational speed of the wire, and machining is primarily accomplished by the reciprocating movement of the wire. Therefore, any remaining machining marks are inevitably oriented along the axis of the pivot stone or pivot hole, and may be tilted several degrees relative to this axis, given the rotational speed and movement rate of the wire relative to the gemstone. The equipment used and the exact principle of the enlargement process preclude the possibility of obtaining different orientations of the remaining machining marks.

[0010] For some pivot stones, it's desirable to obtain an oval-cut hole—a non-cylindrical hole with a convex, rounded profile that decreases in diameter toward its center. This oval-cut hole reduces the surface area on which the shaft rubs against the pivot and facilitates lubrication. To obtain an oval-cut hole, the stone is again threaded onto the wire and then subjected to the specific oval-cut process described below. Stones with straight or cylindrical holes are not oval-cut and are not subjected to any processes other than the enlargement described above.

[0011] The article "The Horological Gemstone" published by Pierhor SA in the Bulletin of the Swiss Chronometer Association (Société Suisse de Chronométrie) No. 69 (June 2012) describes the main steps in the process used to manufacture the various gemstones and the various types of gemstones. Figure 4 The marquise cutting process is illustrated in Figure 1. This operation is performed on a machine by tilting the gemstone over a roller with spiral grooves using a wire of precise diameter coated with a diamond suspension. The gemstone is driven along the roller via the grooves, while the wire abrades the end of the pivot hole. Careful selection of parameters allows the gemstone's tilt to be reversed midway through the roller, resulting in a marquise cut that is as uniform and symmetrical as possible.

[0012] Documents CH121766 and CH336311 describe machines for producing gemstones having a wire coated with a mixture of oil and diamond powder for reaming / enlarging by a reciprocating motion in the axial direction or for marquise cutting with the inclination of the gemstone.

[0013] Document CH706268 emphasizes the effect of the marquis cut of the gemstone, which can reduce friction.

[0014] Document CH393194 describes a process for producing gemstones that achieves very low surface roughness, followed by treating the friction zone by intentionally creating small pores, grooves, roughness, or undulations to obtain a topography / roughness suitable for retaining lubricants. These inhomogeneities are on the order of a few molecules of the lubricant used, i.e., according to the applicant, a fraction of a micron. However, the document does not cite any values or quantitative elements, and does not mention the specific method used to achieve the surface finish in question.

[0015] Document EP 2 778 801 describes a sintered gemstone having a hole formed by a laser and then finished by grinding, brushing and / or polishing to locally modify the roughness, without providing further details.

[0016] Documents EP3835881 and EP3835882 also address various aspects of a method for producing polycrystalline gemstones by pressing. These gemstones have a specific characteristic, including an enlarged hole, the minimum diameter of which may be less than 0.11 mm. In this context, the method aims to provide an alternative to laser methods, which, according to the applicant, do not directly achieve a high-quality surface finish. While producing gemstones by pressing allows for a good surface finish, drilling them using a femtosecond laser results in an unsatisfactory surface finish. Summary of the Invention

[0017] The object of the present invention is to provide a pivot jewel having good properties and capable of improving upon the pivot jewels known in the prior art. In particular, the present invention proposes a pivot jewel having improved pivoting properties, in particular improved roughness properties, and a method relating to such a jewel.

[0018] According to a first aspect, the invention is defined by the following propositions.

[0019] 1. A pivot jewel (1) for a watch movement (100), the pivot jewel (1) comprising a pivot hole (5), the pivot hole (5) having a first axis (A1) and capable of pivoting a watch component (98) or pivoting about the watch component (98), the watch component being, for example, a watch axle, the pivot hole comprising a surface (6), the surface (6) having main abrasive working stripes (61), in particular main polishing stripes, oriented substantially orthogonally radially with respect to the first axis (A1).

[0020] 2. The pivot jewel (1) according to proposal 1, characterized in that the main processing stripes (61) have a spiral angle of less than 1° or less than 0.5°.

[0021] 3. A pivot jewel (1) according to proposal 1 or 2, characterized in that the main processing stripe (61) is parallel or substantially parallel to a plane perpendicular to the first axis (A1) and / or forms an angle of less than 1° or less than 0.5° relative to a plane perpendicular to the first axis (A1).

[0022] 4. A pivot jewel (1) according to one of the proposals 1 to 3, characterized in that the main processing stripes (61) have an orientation dispersion around a mean orientation of positive or negative θ, where θ>0.2°, in particular where θ is about 0.5°.

[0023] 5. A pivot jewel (1) according to one of proposals 1 to 4, characterized in that the roughness Ra of the surface, in particular the roughness Ra of the surface (6) measured parallel to the first axis (A1) or perpendicular to the main stripe (61), is less than 20 nm or less than 10 nm or less than 5 nm.

[0024] 6. A pivot jewel (1) according to any one of proposals 1 to 5, characterised in that the diameter of the pivot hole (5) is less than 2.5 mm or less than 2 mm or less than 1.6 mm or less than 0.6 mm or less than 0.3 mm.

[0025] 7. A pivot jewel (1) according to one of proposals 1 to 6, characterised in that the profile of the surface (6) of the pivot hole (5) passing through a plane passing through the first axis (A1) is straight or cylindrical.

[0026] 8. A pivot jewel (1) according to one of proposals 1 to 6, characterised in that the profile of the surface (6) of the pivot hole (5) passing through a plane passing through the first axis (A1) is convex, as seen from the first axis (A1), wherein the deflection is less than 1 μm or less than 0.5 μm or less than 0.25 μm.

[0027] 9. The pivot jewel (1) according to one of the proposals 1 to 8, characterized in that it is made of technical ceramic, in particular of ruby.

[0028] 10. Pivot jewel (1) according to one of the proposals 1 to 9, characterized in that it comprises a rolling surface (7) intended to roll on a timepiece component, in particular a rolling surface (7) having a first axis (A1).

[0029] 11. Pivot jewel (1) according to one of the proposals 1 to 10, characterized in that the geometry and / or positioning of the main stripes are not controlled.

[0030] 12. A pivot jewel (1) according to any one of proposals 1 to 11, characterised in that said surface (6) exhibits isotropy:

[0031] - is strictly greater than 0, in particular greater than 1%, and

[0032] - less than 10%, in particular less than 3%.

[0033] 13. A timepiece component (98), in particular a wheel (98), in particular a center wheel, comprising at least one pivot jewel according to one of the proposals 1 to 12, in particular at least two pivot jewels according to one of the proposals 1 to 12.

[0034] 14. A timepiece movement (100) comprising at least one pivot jewel according to one of proposals 1 to 12, in particular at least two pivot jewels according to one of proposals 1 to 12, and / or comprising a timepiece component (100) according to proposal 13.

[0035] 15. A timepiece movement (100) according to proposal 14, characterised in that said at least one jewel causes a timepiece component to pivot, said timepiece component being:

[0036] - a balance wheel, or

[0037] - Pallet fork assembly, or

[0038] -Escape wheel.

[0039] 16. Timepiece movement (100) according to proposal 14, characterized in that said at least one jewel causes a timepiece component to pivot, said timepiece component being a wheel of a finely finished gear, such as:

[0040] - minute wheel, or

[0041] - Over the wheel, or

[0042] -Seconds wheel.

[0043] 17. Timepiece movement (100) according to proposal 14, characterized in that said at least one jewel pivots a timepiece component that is a wheel of an automatic winding train.

[0044] 18. A timepiece (200), in particular a watch, comprising:

[0045] - at least one pivot jewel (1) according to one of the proposals 1 to 12, and / or

[0046] - a watch component (98) according to proposal 13, and / or

[0047] - A timepiece movement (100) according to one of the proposals 14 to 17.

[0048] According to a second aspect, the invention is defined by the following proposals.

[0049] 19. A method for producing a pivot jewel (1) for a watch movement (100), said pivot jewel (1) comprising a pivot hole (5), in particular a straight or cylindrical pivot hole, having a first axis (A1), said pivot hole enabling a watch component (98), such as a watch axle, to pivot or to pivot about the watch component (98), said method comprising a first polishing step, in which:

[0050] (i) using free abrasive particles (21), in particular diamond particles, rolling between the surface (6) of the pivot hole (5) to be polished and a polishing support (20), such as a wire (20), and / or

[0051] (ii) driving the pivot jewel (1) in rotational motion about the first axis (A1) relative to the polishing support (20), the polishing support (20) being pulled back towards the surface (6) of the pivot hole (5) to be polished.

[0052] 20. Production method according to proposal 19, characterized in that, during the first polishing step, the pivot jewel (1) is held in position relative to the polishing support (20) by contact with its peripheral face (7).

[0053] 21. The production method according to claim 19 or 20, characterized in that:

[0054] - the first axis (A1) is parallel or substantially parallel to the surface of the polishing support (20), and / or

[0055] The first axis (A1) is parallel or substantially parallel to the second axis (A3) of the polishing support (20), so that the polishing support is in particular constituted by a wire (20).

[0056] 22. Production method according to one of the proposals 19 to 21, characterized in that during the first polishing step, the pivot jewel (1) is driven relative to the polishing support (20) by contact with its peripheral face (7).

[0057] 23. Production method according to one of the proposals 19 to 22, characterized in that, during the first polishing step, the pivot jewel (1) is driven in a straight helical or rotational movement about the first axis (A1) relative to the polishing support (20).

[0058] 24. Production method according to one of the proposals 19 to 23, characterized in that the angle between the first axis (A1) and the second axis (A3) of the polishing support is less than 0.5°.

[0059] 25. Production method according to one of proposals 19 to 24, characterized in that the free abrasive particles (21) are contained in a suspension, in particular a water-based or oil-based suspension, covering the polishing support.

[0060] 26. Production method according to one of the proposals 19 to 25, characterized in that during the first polishing step, a gap of between 5 μm and 20 μm, typically 10 μm, is formed between the polishing support (20) and the pivot hole (5).

[0061] 27. Production method according to one of proposals 19 to 26, characterized in that, after the first polishing step, the method comprises a second machining step of machining a recess (3) on one or two faces (2, 4) of the pivot jewel (1), the faces (2, 4) extending perpendicularly or substantially perpendicularly to the first axis (A1).

[0062] 28. Production method according to one of proposals 19 to 27, characterized in that, after the first polishing step, the method comprises a third polishing step of polishing at least one face (2, 4), preferably two faces, of the pivot jewel (1), said faces (2, 4) extending perpendicularly or substantially perpendicularly to the first axis (A1).

[0063] 29. A production method according to one of proposals 19 to 28, characterized in that the speed of the pivot jewel (1) relative to the polishing support (20) in the orthogonal radial direction relative to the first axis (A1) at the point of contact with the polishing support (20) is in the range between 1 m / s and 10 m / s or between 1 m / s and 20 m / s.

[0064] 30. A machine (30) for polishing the pivot hole (5) of a pivot jewel (1) of a watch movement (100), the pivot jewel (1) having a pivot hole oriented along a first axis (A1), the machine comprising a roller (31) which is driven in rotation about a second axis (A2) and has a slot (32) forming a spiral around the roller (31), the slot (32) being used to drive the pivot jewel and to hold the pivot jewel in a position such that the first axis (A1) is perpendicular to the osculating plane of the spiral at the contact between the pivot jewel and the slot.

[0065] 31. The polishing machine according to proposal 30, characterized in that it comprises a polishing support (20) having a second axis (A3), and:

[0066] - the second axis (A3) of the polishing support and / or the first axis (A1) of the pivot hole are perpendicular to a tangent to the spiral of the slot, and / or

[0067] - the second axis (A3) of the polishing support and / or the first axis (A1) of the pivot hole are perpendicular to the osculating plane of the spiral of the slot at the contact between the pivot jewel and the slot (32).

[0068] 32. Polishing machine according to proposal 30 or 31, characterized in that the helix angle of the helix around the drum (31) is less than 0.1° or less than 0.05°.

[0069] 33. Polishing machine according to one of the proposals 30 to 32, characterized in that it comprises a polishing support (20) in the form of a wire, which is intended to hold the pivot jewel at the bottom of the slot (32) and to polish the pivot hole (5) by abrasion.

[0070] 34. Polishing machine according to one of the proposals 30 to 33, characterized in that it comprises an element (35) for setting the orientation of the polishing support (20) relative to the second axis (A2).

[0071] 35. Polishing machine according to one of the proposals 30 to 34, characterized in that the machine comprises a fixture (33) for distributing the pivot stones (1), the fixture being arranged to feed the drum (31) by bringing the pivot stones one at a time to the drum.

[0072] 36. Polishing machine according to one of the proposals 30 to 35, characterized in that the diameter of the drum (31) is greater than 10 cm and / or the profile of the slot is U-shaped or rectangular, in particular without chamfers at the bottom of the slot, so as to make it easier to correctly maintain the pivot jewel in its vertical position relative to the drum (31).

[0073] 37. Polishing machine according to one of the proposals 30 to 36, characterized in that it comprises a feed element (38) for depositing a suspension containing free abrasive particles (21) onto the polishing support (20).

[0074] According to a third aspect, the invention is defined by the following propositions.

[0075] 38. A method for producing a timepiece component (1), in particular a pivot jewel (1), comprising a hole (5), said method comprising:

[0076] - a step of machining the hole (5) by abrasion using abrasive particles (21), in particular diamond particles, which are free relative to the machining support (20) and roll between the surface (6) of the hole to be machined and the machining support (20) housed in the hole, and / or using abrasive particles capable of being detached from the machining support, and then

[0077] - a step of washing the timepiece component (1) and the machining support (20) while the machining support is housed in the hole, and then

[0078] - A step of removing said machining support from said hole.

[0079] 39. The production method according to proposal 38, characterized in that the washing step comprises the use of a washing solution, in particular an aqueous solution or an alcoholic solution or an oily solution.

[0080] 40. The production method according to proposal 39, characterized in that the washing step comprises immersing the timepiece component (1) and the machining support (20) in the washing solution.

[0081] 41. The production method according to proposal 40, characterized in that the immersion includes emitting ultrasonic waves into the washing solution.

[0082] 42. Production method according to one of proposals 38 to 41, characterized in that the washing step consists in spraying a washing solution onto said timepiece component (1) and said machining support (20).

[0083] 43. The production method according to any one of proposals 38 to 42, characterized in that the washing step comprises blowing gas or steam.

[0084] 44. Production method according to one of the proposals 38 to 43, characterized in that the washing step is carried out on a processing machine, in particular a polishing machine that carries out the step of processing the holes by abrasion.

[0085] 45. The production method according to any one of proposals 38 to 43, characterized in that the washing step is carried out after removing the assembly consisting of the following components from the processing machine that carries out the step of processing the hole by abrasion:

[0086] - said timepiece component (1), and

[0087] - said machining support (20).

[0088] 46. Production method according to one of proposals 38 to 45, characterized in that the washing step is carried out in a casing (80), said assembly consisting of said timepiece component (1) and said machining support (20) passing through said casing.

[0089] 47. A washing system (84) comprising hardware means (80, 81, 82, 83) for implementing the steps of washing a timepiece component (1) by a method according to one of proposals 38 to 46, when a machining support is housed in a hole of the timepiece component (1), in particular:

[0090] a housing (80) formed, for example, entirely of two parts (81, 82) movable relative to one another and / or having access for the machining support, and

[0091] - Nozzles 83 and / or channels for spraying said washing solution.

[0092] 48. A processing system (30) comprising hardware means (20, 31, 34, 35, 36, 37, 38, 39, 40, 84) for carrying out the method according to one of proposals 38 to 46, in particular comprising a washing system (84) according to proposal 47.

[0093] 49. A timepiece component (1), in particular a pivot jewel (1), obtained by implementing a method according to one of proposals 38 to 46.

[0094] 50. A timepiece movement (100) comprising a timepiece component (1) according to proposal 49.

[0095] 51. A timepiece (200) comprising a timepiece component according to proposal 49 and / or a timepiece movement (100) according to proposal 50.

[0096] According to a fourth aspect, the invention is defined by the following propositions.

[0097] 52. A method for determining the roughness of a surface (6) of a pivot hole (5) of a pivot jewel (1) of a timepiece movement (100), the method comprising:

[0098] - a first preparation step for preparing the pivot jewel (1), the first preparation step comprising ablating a first portion of the pivot jewel (1) so as to obtain a second portion of the pivot jewel (1), the first portion comprising (i) a portion of the surface (6) of the pivot hole (5), (ii) a portion of the outer surface (7) of the pivot jewel (1) and (iii) a portion of the volume between the surface (6) of the pivot hole and the outer surface (7), and then

[0099] - A second measuring step of measuring said surface (6) of said pivot hole (5) situated on said second portion of said pivot jewel (1).

[0100] 53. A determination method according to Proposal 52, characterized in that the ablation of the first part of the pivot jewel is performed through a plane passing through the axis (A1) of the pivot hole (5) or through a plane parallel to the axis (A1) of the pivot hole (5), and / or the first preparation step does not change the surface (6) of the pivot hole (5) located on the second part of the pivot jewel (1), but allows access to the surface (6) of the pivot hole (5) on the second part of the pivot jewel (1).

[0101] 54. The determination method according to one of proposals 52 and 53, characterized in that the ablation is performed by abrasion.

[0102] 55. Determination method according to proposal 54, characterized in that an assembly sub-step of assembling a plurality of pivot stones (1) is carried out before said ablation.

[0103] 56. Determination method according to one of the proposals 52 to 55, characterized in that, before said ablation, an assembly sub-step of assembling one or more pivot stones (1) on a support is carried out.

[0104] 57. The determination method according to proposal 55 or 56, characterized in that the assembling sub-step includes threading the pivot jewel onto the wire.

[0105] 58. Determination method according to one of the proposals 52 to 57, characterized in that a coating sub-step of coating one or more of said pivot stones (1) is carried out before said ablation.

[0106] 59. The determination method according to proposal 52 or 53, characterized in that the ablation is performed by fragmentation.

[0107] 60. Determination method according to proposal 59, characterized in that, before said fragmentation, a sub-step of making a cut in said pivot jewel (1) on one of its faces (2, 4) is carried out.

[0108] 61. Determination method according to proposal 60, characterized in that said fragmentation is carried out by applying an impact to a portion of said pivot jewel (1), the other portions of said pivot jewel being retained on a support, these portions being delimited by said cutout.

[0109] 62. The determination method according to proposal 52 or 53, characterized in that the ablation is performed by saw cutting or wire cutting.

[0110] 63. Method according to one of the proposals 52 to 62, characterized in that the second measurement step is performed by means of a laser scanning confocal microscope.

[0111] 64. Method according to one of the proposals 52 to 63, characterized in that the second measuring step comprises determining the direction perpendicular to the main machining striations (61) on the surface (6) of the pivot hole (5) of the pivot jewel (1).

[0112] 65. A method according to proposal 64, characterized in that the second measuring step is a linear measurement along the direction perpendicular to the main processing stripe (61) on the surface (6) of the pivot hole (5) of the pivot jewel (1).

[0113] All features of these different aspects can be combined with each other unless they are logically or technically incompatible. BRIEF DESCRIPTION OF THE DRAWINGS

[0114] The accompanying drawings illustrate, by way of example, embodiments of the pivot jewel, the polishing machine and the associated method according to the invention.

[0115] Figure 1 is a perspective view in longitudinal section of one embodiment of a pivot jewel according to the present invention.

[0116] Figure 2 is a longitudinal cross-sectional view of a plurality of pivot stones according to the present invention during polishing.

[0117] Figure 3 is a schematic side view of one embodiment of a polishing machine according to the present invention.

[0118] Figure 4 is a schematic top view of an embodiment of a polishing machine according to the present invention.

[0119] Figure 5 is a schematic diagram of a first embodiment of a timepiece according to the present invention.

[0120] Figure 6 is a schematic diagram of a second embodiment of a timepiece according to the present invention.

[0121] Figure 7 is a schematic side view of one embodiment of a washing system according to the present invention. DETAILED DESCRIPTION

[0122] Work carried out by the applicant has demonstrated that surface finish in the pivoting area is crucial for ensuring the reliability of a timepiece movement, and in particular for ensuring that the axle pivots reliably in the pivot jewel. The applicant has observed that it is also possible to improve the wear resistance of the pivot, in particular by eliminating or delaying the appearance of sticky black deposits that could degrade performance.

[0123] Developments made by the applicant make it possible to obtain an excellent surface finish in the pivot hole of a gemstone, in particular for gemstones having a straight or cylindrical hole (i.e. a hole without conical, frustoconical or olive-shaped cut surfaces). These developments relate to a method for measuring roughness, a method for preparing a gemstone for measuring roughness, a machine (or apparatus) and a method for obtaining an optimized surface finish by polishing, a method for washing a gemstone after it has been polished, and a gemstone having an optimized surface finish. In particular, the solution provided by the invention makes it possible to obtain a roughness Ra of less than 10 nm for the pivot hole, wherein the preferential orientation of the remaining polishing streaks is in an orthogonal radial direction relative to the axis of the pivot hole. Striae are machining streaks, in particular polishing streaks, whose geometry and positioning on the surface of the pivot hole are largely uncontrolled and extremely random. According to the invention, all that is done is:

[0124] - roughly controlling the depth of the striations by selecting an abrasive capable of producing a depth in nanometers (e.g. resulting in a roughness Ra of less than 20 nm), and

[0125] The orientation of the stripes is generally controlled to have a dispersion of orientations around a mean orientation of positive or negative θ, where θ>0.2°, in particular where θ is about 0.5°.

[0126] As mentioned above, watch jewels are a key element in the reliability of a watch movement. The challenge is to achieve the right surface finish on all jewels within a manufacturing batch, and with optimal reproducibility from one batch to the next. This is all the more necessary because checking the surface finish of pivot holes is extremely difficult and destructive.

[0127] Many pivoting movements in a watch movement are ensured and implemented by jewels with straight or cylindrical holes. This is the case, for example, with the pivoting movements of the minute wheel, the second wheel, the second wheel, or the calendar wheel. Typically, the pivoting movements performed by shafts with small-diameter pivots (sprung balance oscillators, pallet forks, pallet wheel) are provided by marquise-cut jewels (i.e., jewels whose pivot holes have an marquise-shaped cut), while shafts with larger diameters (e.g., greater than 0.15 mm) pivot in straight jewels (i.e., jewels with straight holes).

[0128] The applicant also noted that a "cotton weaving" operation, performed by moving a cotton thread carrying a suspension of diamond particles back and forth, could achieve a better surface finish. However, this process is extremely difficult to implement for diameters less than 0.3 mm and cannot be applied to series production of certain critical pivot bearings for finishing gears. Even for diameters less than 0.6 mm, the process can only be performed manually, which has proven to be less robust than an industrial process and incapable of completely eliminating wear.

[0129] Furthermore, roughness measurements show that the gemstones obtained by the standard enlargement process have a high roughness, with the remaining polishing streaks oriented in the axial direction (i.e., parallel to the axis of the pivot hole; this is logical given the back-and-forth movement exerted on the gemstone relative to the wire during this process). The aforementioned manual process increases the roughness without changing the axial orientation of the streaks. Conversely, in order to eliminate wear phenomena, the inventors have noted that it is necessary not only to obtain the lowest possible roughness, but also to obtain an orientation of the remaining polishing streaks in an orthogonal radial direction (relative to the axis of the pivot hole) in order to minimize the impact of the pivot gemstone on the abrasive effect on the shaft it is intended to receive.

[0130] Figure 1 1 shows an embodiment of a pivot jewel 1 of a timepiece movement 100. Pivot jewel 1 has a cylindrical overall shape with axis A1 and includes a pivot hole 5 along axis A1. This pivot hole 5 includes a surface 6, in particular a cylindrical surface 6 or a substantially cylindrical surface 6, and is intended to enable a timepiece component, such as a timepiece axle, to pivot or to be able to pivot about a timepiece component. Furthermore, pivot jewel 1 is defined by:

[0131] - an upper face 2 and a lower face 4 , preferably both extending perpendicularly to the axis A1 , and

[0132] - a cylindrical overall outer surface 7 having an axis A1 .

[0133] The pivot jewel may also have a recess 3 formed on the upper face 2 and / or a recess formed on the lower face 4. However, the pivot jewel may have no recess, a recess on one face, a recess on each face, or one or two curved faces.

[0134] Advantageously, the diameter of the pivot hole 5 is less than 2.5 mm or less than 2 mm or less than 1.6 mm or less than 0.6 mm or less than 0.3 mm.

[0135] The surface 6 has main polishing striations 61 .

[0136] The pivot jewel 1 is preferably made of technical ceramics, in particular corundum or spinel or zirconium oxide or SiC or silicon dioxide, or possibly other natural or synthetic stones such as diamond. The pivot jewel 1 can be made of polycrystalline or single-crystalline corundum, for example ruby, in particular Cr-doped alumina, for example synthetic Cr-doped alumina, or even single-crystalline Cr-doped alumina. The pivot jewel 1 can also be made of a combination of alumina and zirconium oxide.

[0137] According to the invention, the method for producing a pivot jewel 1 for a timepiece movement 100 makes it possible to obtain, inside the pivot hole 5 of the jewel, and in particular on its surface 6, a surface finish having the lowest possible roughness and an orientation of the roughness in the direction of relative movement between the jewel and the timepiece component it is intended to receive (in particular, a shaft), that is, a main striation orientation. This orientation is therefore in an orthogonal radial direction relative to the axis A1. It has been noted that this orientation makes it possible, in particular, to minimize the effects of abrasion and, therefore, wear at the points of contact between the pivot jewel and the timepiece component (in particular, the shaft).

[0138] In one embodiment of the method for producing a pivot jewel, the process is preferably as described above, i.e. the following steps are performed:

[0139] - Processing the material into boards,

[0140] - cutting the sheets into blanks,

[0141] - Turn,

[0142] -Drill the rough pivot hole,

[0143] - possible expansion, and

[0144] - Possibly one or more grooving and polishing operations.

[0145] However, in addition to or as an alternative to the enlarging step, a specific step of polishing the pivot hole is performed, which will be described in more detail below. This polishing step can achieve the surface finish goals mentioned above.

[0146] Polishing is like Figure 2 The three-body polishing operation shown is a three-body polishing operation. This polishing is performed using a free abrasive 21 (in particular, diamond particles of a given diameter suspended in an aqueous or oily matrix), which rolls between the pivot jewel and a polishing support 20 of suitable geometry (in particular, a wire). The wire can be a metal wire, in particular a metal wire of constant diameter. Compared to two-body polishing, in which the abrasive is fixed to the polishing support and wears the surface, this three-body polishing can achieve a precise surface finish and low roughness. In order to obtain the desired orientation of the residual polishing stripes 61, i.e., to avoid orientation along the axis A1, it is necessary to:

[0147] - avoidance of the back and forth polishing movement along the axis A1 of the pivot hole conventionally performed in standard and conventional processes for obtaining straight holes, and

[0148] On the contrary, a rotational movement of the pivoting jewel about the polishing support 20 , ie about the axis A1 , is preferred.

[0149] Furthermore, in order to obtain a uniform surface finish over the entire height of the hole and to obtain a hole that remains straight and / or cylindrical (unlike an olive-cut hole), the pivot jewel must remain straight relative to the polishing support, i.e. the axis A1 must remain parallel to the surface of the polishing support 20, and the jewel must therefore be prevented from tilting and / or the axis of the jewel's hole must not have a non-zero angle relative to the polishing support.

[0150] In order to meet these different requirements at the same time, Figure 2 As shown, a gemstone 1 is threaded onto a polishing support 20 that is uniformly covered or filled with abrasive 21. The force applied to the polishing support 20 presses the gemstone against a roller or drum 31, which serves as a contact surface for the gemstone and a means for rotating the gemstone. Thus, during the polishing step, the pivoting gemstone 1 is driven relative to the polishing support 20 by (rolling) contact on its outer peripheral surface 7. To ensure proper drive and high-speed rotational motion, and also to prevent the gemstone from tilting, grooves 32 (or slots 32) are formed in the roller, the width, depth, shape, and spacing of the grooves being carefully selected.

[0151] The width of the groove is selected to ensure good guidance of the gemstone by preventing it from tilting, and is essentially determined by the thickness of the gemstone, allowing for a certain clearance. Typically, the groove width La is at least 50 μm greater than the nominal thickness e of the gemstone, for example 80 to 100 μm greater. The groove depth p should allow for good guidance of the gemstone and for good positioning of the wire over the roller, with a certain clearance j1 between the wire and the outer surface of the roller, typically at least 200 μm, and in particular between 200 and 400 μm. For example, for a gemstone with a diameter of 1.2 mm and a hole of 0.2 mm, the groove depth p can be 0.12 mm. The groove profile preferably has a rectangular shape (a U-shaped or rectangular profile in a longitudinal plane passing through the axis A2), in particular a rectangular shape without softened edges or chamfers at the groove bottom, to make it easier to correctly hold the gemstone in its vertical position relative to the roller 31.

[0152] The spacing of the grooves can be zero, meaning each gemstone will be placed in a separate groove that is completely perpendicular to the roller's axis. However, it is more industrially advantageous to create spiral grooves (i.e., with a non-zero spacing), as this allows the gemstone to be gradually moved forward along the roller as the roller rotates. The spacing of the grooves can be at least the same as the groove width La, typically 1.5 times the groove width La, e.g., for a groove width of 0.4 mm, the spacing is 0.6 mm. The spacing also determines the total distance covered by the gemstone on the roller: it is advantageous to choose the smallest possible spacing to maximize the distance and time over which treatment or polishing can occur. As for the diameter of the polishing support, it is selected based on the diameter of the gemstone's bore, particularly to leave a gap j2 between the gemstone and the polishing support 20 while still maintaining good traction resistance and limiting the gemstone's tendency to tilt. Typically, the gap j2 is in the range between 5 μm and 20 μm, e.g., 10 μm.

[0153] The axis of the polishing support must be oriented very precisely relative to the grooves. In particular, the axis of the polishing support must be oriented perpendicular to the grooves (or as close to perpendicular as possible). Therefore, the helical angle of the slots needs to be precisely compensated. This requires a setting accuracy of <0.1°. Therefore, the polishing machine or equipment used to perform this polishing has a specific construction that includes a device that allows this precise setting. This is equivalent to tilting the axis A2 of the roller relative to the axis A3 of the polishing support, which is parallel to the axis A1 of the pivot hole during polishing.

[0154] like Figure 4 As shown, this compensation angle (denoted by α) can be precisely determined: if dr is the diameter of the roller and pa is the pitch of the slots 32, then α=atan(pa / (π×dr)). This compensation angle α corresponds to the helical angle of the slots 32. In other words, the axis A3 of the polishing support and the axis A1 of the pivot hole must be perpendicular to the tangent to the helix of the slots 32. Alternatively, the axis A3 of the polishing support and the axis A1 of the pivot hole must be perpendicular to the osculating plane of the helix of the slots 32 at the point of contact between the pivot stone and the slots 32. This makes it possible to obtain a straight or cylindrical hole with a uniform roughness along the hole and with the main machining stripes having a substantially orthogonal radial orientation (relative to the axis A1).

[0155] For example, for a roller diameter of 250 mm and a slot pitch of 0.6 mm, the compensation angle is 0.044°. More generally, the helix preferably has a helix angle of less than 0.1° or less than 0.05°. This requires considerable setting precision. In practice, a first setting is performed based on theoretical values, followed by a fine setting (to approximately one hundredth of a degree) in order to eliminate any traces of a marquise cut in the resulting gemstone (i.e., to keep the hole as cylindrical as possible, that is, to minimize the diameter difference between the center and the edge of the hole).

[0156] In order to correctly implement the method according to the invention, it is important that the axis A1 of the hole 5 of the pivot jewel 1 is parallel to the axis A3 of the polishing support and / or that the angle between the axis A1 of the hole of the pivot jewel and the axis A3 of the polishing support is as small as possible, in particular less than 0.5°. For this reason, great precision is required when setting the compensation angle between the axis A3 of the polishing support and the axis A2 of the roller 31.

[0157] The method described above may initially appear similar to the marquise cutting method. This is because the polishing method according to the invention is carried out with gemstones threaded onto a polishing support and with rollers machined with spiral grooves to allow each gemstone to move forward during polishing. However, there are a number of significant differences:

[0158] The purpose of the maritimum cut is to locally machine the hole, particularly the exposed ends, in order to achieve a circular profile (the purpose of the maritimum cut is to minimize the contact surface area between the shaft and the pivot hole). Maritimum cuts are therefore a different type of machining than polishing. The amount of material removed during maritimum cuts is significant, with the minimum diameter of the hole typically increasing by several microns during maritimum cuts. With maritimum cuts, the difference in the minimum diameter of the hole before and after maritimum cuts is typically 2 μm, and even higher at the ends of the hole (defined along the axial direction of the gemstone). Thus, maritimum cuts can bring the minimum diameter of the hole to the nominal size. In contrast, with the polishing process according to the present invention, during the process used to produce the gemstone, the diameter of the pivot hole is at its nominal value before the polishing step is performed. It is estimated that the diameter difference between (i) the surface finish before the polishing process and (ii) the surface finish after the process is less than 0.1 μm. In other words, the purpose of the polishing process according to the invention is to reduce the peak-to-valley height of the striations produced during the drilling and / or enlarging operations by removing as much material as possible so as to reduce the roughness, eliminate unevenness, and also orient the roughness in a direction that is favorable to the movement of the component when it pivots under the guidance of the pivot hole.

[0159] When making a marquise cut, the angle between the polishing support and the orientation of the groove is not compensated but rather amplified, typically to a value of about 5° to 10° or even 30°, which can tilt the stone relative to the axis of the polishing support, thus softening the edge corners of the hole and creating a rounded profile inside the hole. Precise control of this angle is not crucial for a marquise cut.

[0160] Thus, in a marquise-cut process, the axis of the hole of the pivot stone is not parallel to the axis of the polished support, but has a pronounced inclination, for example an angle of about 5° to 10°.

[0161] - In addition, in the marquis-cut process, the intersection of the cylindrical body of the roller with the vertical plane containing the polishing support forms an ellipse, which means that the stone "ascends" on the first half of the roller and then "descends" on the second half of the roller, whose inclination is switched at the top, making it possible to produce a uniform and symmetrical profile.

[0162] - In the marquise cut, the grooves are preferably V-shaped rather than U-shaped or rectangular to make it easier to bevel and tilt the stone.

[0163] Regarding the order of the steps, the marquise cut is performed after the recess has been machined, as this allows for a marquise cut that is perfectly centered relative to the exposed end of the hole, making it easier to tilt the gemstone in the groove of a hole with a shorter length. In contrast, with the polishing process according to the present invention, it is easier to keep the gemstone straight in the groove of a hole with a longer length. Therefore, the step of polishing the hole is preferably performed before any machining of the recess and before any polishing of the upper and lower faces. Therefore, compared to the marquise cut process, the polishing process according to the present invention preferably reverses the grooving and polishing steps.

[0164] As a result of what has been described above, the method for producing pivot jewels 1 of timepiece movement 100 comprises a first polishing step during which:

[0165] (i) using free abrasive particles 21 rolling between the surface 6 of the pivot hole 5 to be polished and the polishing support 20, and / or

[0166] (ii) driving the pivot jewel 1 in rotational motion about the axis A1 relative to the polishing support 20, which is pulled back towards the surface 6 of the pivot hole 5 to be polished. This pullback allows contact between the polishing support 20 and the surface 6, either directly or indirectly (via the abrasive particles).

[0167] Ignoring the rate of forward movement of the gemstone in translation relative to the polishing support along the axis A1 , the movement of the gemstone relative to the polishing support is considered to be a rotational movement about the axis A1 .

[0168] As seen above, during the first polishing step, pivot jewel 1 is held in position relative to polishing support 20 by contact between peripheral face 7 of pivot jewel 1 and the bottom of slot 32. Preferably, face 7 extends parallel or substantially parallel to first axis A1.

[0169] Preferably, as a result of the above, during the first polishing step, the polishing support is a wire whose axis A3 is substantially parallel to the axis A1 and the angle between the axis of the polishing support A3 and the axis A1 of the hole of the gemstone is less than 0.5°.

[0170] Further preferably, due to the above solution, during the first polishing step:

[0171] - driving the pivot jewel 1 in a straight helical or rotational motion about the axis A1 relative to the polishing support 20 , and / or

[0172] - produces a helical motion with a helical angle of less than 0.5°, and / or

[0173] - the angle between the axis A1 and the axis of the polishing support A3 is less than 0.5°, and / or

[0174] The angle between the axis A1 (or the axis A3 ) and the axis A2 is equal to the helix angle of the slot 32 .

[0175] Reference below Figure 3 and Figure 4 One embodiment of a polishing machine for performing the polishing process according to the present invention is described. Preferably, the polishing machine can perform the polishing process on large quantities of gemstones (thousands or even tens of thousands of gemstones) in an industrially reproducible and repeatable manner. Preferably, the machine can polish multiple gemstones simultaneously.

[0176] exist Figure 3 and Figure 4 The main elements of one embodiment of a polishing machine are schematically shown in FIG. The polishing machine mainly comprises:

[0177] - roller 31 or drum 31,

[0178] - polishing support 20, and

[0179] -Frame 39.

[0180] Polishing machines also include:

[0181] an actuator 40 for rotating the roller relative to the frame 39 about the axis A2, the actuator 40 comprising a motor,

[0182] a module 38 for feeding or depositing abrasive onto the polishing support 20 , making it possible to feed polishing agent to the point of contact between the polishing support 20 and the hole 5 of the stone,

[0183] - a distribution module 37 for bringing the gemstones one by one onto rollers,

[0184] a module 36 for setting the tension F of the polishing support 20 , and

[0185] - a module 35 for setting the angle α between the axes A2 and A3, and

[0186] A module 34 for adjusting the position of the polishing support relative to the roller in order to maintain a constant distance between the polishing support and the roller over the entire length of the roller.

[0187] The tension setting module 36 makes it possible to keep the polishing support under the correct tension in order to ensure that the contact force exerted by the gemstone on the roller is constant. The tension setting module 36 can be simply and effectively implemented by means of adjustable weights fixed at the ends of the polishing support and thus exerting a calibrated tension on the polishing support.

[0188] It is also advantageous that the various gemstones to be treated are distributed equidistantly on the rollers at given intervals to ensure a constant and comparable force for each gemstone. To this end, the distribution module 37 may for example comprise a clamp 33 for ensuring such an even distribution.

[0189] For example, the dimensions of the rollers may be:

[0190] - an outer diameter greater than 10 cm or approximately 25 cm, and

[0191] - is about 28 cm in length;

[0192] These dimensions will need to be adjusted and / or optimized based on the characteristics of the gemstone.

[0193] The module 35 for setting the angle α between the axes A2 and A3 allows a very fine adjustment of this angle to ensure perpendicularity between:

[0194] - The axis of the polished support, and therefore the axis of the hole of the gemstone,

[0195] - The orientation of the groove where the treated stone is located.

[0196] Thus, in one variant, the setting module 35 can ensure perpendicularity between the axis A3 of the polishing support and the tangent of the spiral of the groove by setting the angle α. In another variant, the setting module 35 can ensure perpendicularity between the axis A3 of the polishing support and the osculating plane of the spiral of the slot at the contact between the pivot jewel and the groove 32 by setting the angle α. Specifically, the setting module 35 includes a plate that carries the roller 31 and the actuator 40 and can be set relative to the frame 39 that carries the polishing support 20. The setting module 35 also includes a rolling coupling that allows the angle α to be adjusted with an accuracy of approximately 1 / 100° or even less than 1 / 100°. This adjustment is performed, for example, by a mechanical sliding system that is also part of the setting module 35.

[0197] The angle α is initially set to a theoretical value, in particular to a theoretical value of the helix angle, and then the set gemstone is produced. This angle is then adjusted if the pivot hole of the produced gemstone is not cylindrical, and / or if diameter variations are detected along the pivot hole of the produced gemstone, and / or if deflection is detected along the pivot hole of the produced gemstone (e.g., a deflection greater than 0.5 μm), and / or if a substantial portion of the surface of the pivot hole of the produced gemstone has not been modified (polished) by the process. The goal is to eliminate areas and traces of drilling or enlarging operations along the entire length of the pivot hole. When the axis A1 of the gemstone's hole is parallel to the polishing support, all surfaces 6 of the hole, from the lower face 4 to the upper face 2 of the gemstone, are polished uniformly or substantially uniformly.

[0198] To adjust the polishing support relative to the roller, it is important that the polishing support is in contact with the hole of the gemstone. Since the polishing support is guided by the gemstone and held in position by the tension applied to it, the position of the polishing support, and in particular the angle of its axis relative to the surface of the roller, does not necessarily need to be precisely set. The depth of the groove does not need to be large enough to keep the polishing support away from the roller, but rather needs to be sufficient to ensure proper guidance of the gemstone and avoid vibrations. It is important that the gemstone is correctly held against the bottom of the groove by the force applied by the polishing support, thereby ensuring uniform polishing.

[0199] For example, the speed of the rollers ranges between 800 and 1500 rpm, typically 1200 rpm. For a roller diameter of about 25 cm and a gemstone diameter of typically 1 mm, this results in a very high rotational speed of the gemstone of about 300,000 rpm or 5,000 rps (assuming the gemstone does not slip on the rollers). The rotational speed is therefore much higher than the rate of forward movement of the gemstone on the polishing support: at the hole, for a hole diameter of 0.2 mm, for example, the speed at the point of contact between the polishing support and the hole is 3.15 m / s in the orthogonal radial direction relative to the axis A1, and 9.2 mm / s in the axial direction relative to the axis A1, i.e. more than 300 times higher. In this case, the angle of the polishing streak relative to the plane perpendicular to the axis A1 is about 0.2°, which is negligible.

[0200] The speed of pivot jewel 1 in contact with polishing support 20 and relative to polishing support 20 in an orthogonal radial direction relative to axis A1 may range between 1 and 20 m / s, in particular between 1 and 10 m / s.

[0201] Another advantageous factor in the repeatability of the polishing process according to the present invention is the excellent separation of the gemstones on the rollers, which is ensured by preventing them from abutting against each other during processing, with a constant spacing from one gemstone to the next. This ensures that the contact force is constant from one gemstone to the next and along the rollers. One approach to ensuring good distribution is to use precision clamping devices, particularly jigs, in the distribution module 37. These clamps pick up exactly one gemstone at a time at consistent intervals and then release them onto the polishing support and rollers in the same manner. The polishing support moves forward relative to the rollers along axis A1 at a very low rate to advance the gemstones to the distribution module. The forward movement rate is typically approximately the thickness of the gemstone per distribution cycle. If the module is set to dispense one gemstone onto the rollers every 6 seconds, and if the gemstone is 0.315 mm thick, the resulting forward movement rate of the polishing support is typically approximately 0.2 m / h. The forward movement rate is independent of the structure of the pivot jewels obtained using this production process. In the described embodiment of the production process, this movement is only necessary to ensure the pivot jewels travel outside the rollers 31.

[0202] A reliable dispensing module is an advantageous element that ensures the correct forward movement of the polishing support and the correct dispensing of the gemstones so that each gemstone has the desired surface finish in the pivot hole. The implementation of this process must be robust and repeatable, as checking the surface finish is conventionally destructive and therefore difficult or impossible to perform on the gemstones or on gemstone samples during the process for producing the gemstones.

[0203] It goes without saying that in order to ensure the correct execution of the process, cameras can be added (to check, for example, the height of the polishing support, the position of the clamps and / or the correct distribution of the stones on the rollers), display monitors, measuring devices and results, parameter tracking devices, human / machine interfaces, etc.

[0204] When implementing a polishing process for a new gemstone geometry, a setup step and an optimization step may be performed. Generally speaking, there are reversible interactions and influences to be optimized between the speed of the rollers, the tension of the polishing support (and therefore the force applied), the diameter of the hole, and the size of the abrasive.

[0205] More generally, a polishing machine 30 according to the invention for polishing a pivot hole 5 of a pivot jewel 1 of a timepiece movement 100 comprises a drum 31 driven in rotation about an axis A2 and having slots 32 forming a spiral around the drum 31, the slots 32

[0206] - drives the pivot jewel, and

[0207] - Holding the pivot jewel in a position such that the axis A1 is perpendicular to the osculating plane of the helix at the contact between the pivot jewel and the slot.

[0208] The polishing process (one embodiment of which has been described above) makes it possible, on the one hand, to orient the polishing scratches or striations on the surface of the pivot hole orthogonally and radially relative to the axis A1 of the pivot hole 5. This orientation is more advantageous because it matches the orientation of the movement of the component guided in the jewel (in particular the pivot) relative to the jewel, thus avoiding a "file" effect that causes more rapid wear of the pivot. On the other hand, the polishing process (one embodiment of which has been described above) makes it possible to reproducibly obtain a low roughness, which, in optimized cases, can have values of less than 5 nm. Since the orientation of the scratches is orthogonal and radial relative to the axis A1, the measurement of the roughness in the orthogonal radial direction is irrelevant, and the given values are measured in the axial direction.

[0209] The above-described process can also be applied to pivot jewels produced by other processes or process steps, for example, jewels produced by pressing and / or having recesses produced by laser machining, and / or jewels having other elements such as the clearance zones described in document WO2021032552A1. The above-described process can also be applied to other timepiece components comprising a hole, in particular a cylindrical hole, such as a tube, for example a ceramic tube or a metal tube, or a timepiece component such as a cannon pinion.

[0210] More generally, compared to what has been described above, the method for producing a timepiece component 1 may comprise a step of polishing or machining a hole 5 by abrasion using abrasive particles 21 that are free relative to a machining support 20 and roll between the surface 6 of the hole to be machined and the machining support 20 housed in the hole, and / or using abrasive particles capable of being detached from the machining support, the component being driven in a rotational motion about the axis of the hole relative to the polishing or machining support.

[0211] As a result of the implementation of the above-described process and / or the use of the above-described machine, it is possible to produce a pivot jewel 1 for a timepiece movement 100, comprising a pivot hole 5, in particular a cylindrical pivot hole, having a first axis A1 and enabling the pivoting of a timepiece component or pivoting about a timepiece component. The pivot hole 5 comprises a surface 6 having main abrasive working striations 61, in particular main polishing striations, oriented substantially orthogonally and radially with respect to the first axis A1.

[0212] The orientation of the striae is the orientation of their length or their largest dimension and can be determined by examining the image or even by using the process for determining the surface texture as described above. With the machining process described, the number, geometry and position of the machining striae are not controlled, but the process results in a preferred orientation that is substantially orthogonal radially relative to the axis A1 of the hole.

[0213] The main machining and / or polishing stripes 61 advantageously have an average helix angle of less than 1° or less than 0.5°, or more generally such that the following portions are parallel or form an angle between them of less than 1° or less than 0.5°:

[0214] - the osculating plane relative to any main fringe at any point on that main fringe, and

[0215] - a plane perpendicular to said axis A1.

[0216] In other words, the main machining and / or polishing stripes 61 are preferably parallel or substantially parallel to a plane perpendicular to the axis A1. In other words again, the main machining and / or polishing stripes 61 (or their tangents) form an angle of less than 1° or less than 0.5° relative to the plane perpendicular to the axis A1.

[0217] Advantageously, the roughness Ra of the surface 6 , in particular the roughness Ra of the surface 6 measured parallel to the first axis A1 or perpendicular to the main stripes 61 , is less than 20 nm or less than 10 nm.

[0218] As a result of the implementation of the above-described process and / or the use of the above-described machine, the profile of the surface 6 of the pivot hole 5 passing through the plane passing through the axis A1 may be:

[0219] - straight, or

[0220] - Convex, seen from the axis A1 , with a deflection of less than 1 μm or less than 0.25 μm.

[0221] According to the first use, such as Figure 5 As shown, the Pivot Jewel 1 is designed to:

[0222] - driven into the frame 99 of the watch movement 100, and

[0223] - To receive a component 98 , for example a clock arbour, in the pivot hole 5 .

[0224] The watch component may in particular be:

[0225] - a balance wheel, or

[0226] - Pallet fork assembly, or

[0227] - escape wheel, or

[0228] - a finely finished gear wheel, such as a center wheel or minute wheel or second wheel, or

[0229] -The wheel of the automatic winding train.

[0230] According to the second use, such as Figure 6 As shown, the Pivot Jewel 1 is designed to:

[0231] - driven into a clock component 98 such as a clock axle, and

[0232] - a tenon receiving in pivot hole 5 another timepiece component or frame 99 of timepiece movement 100. Timepiece component 98 or another timepiece component may in particular be a wheel of a finishing gear, such as a centre wheel, a minute wheel or a second wheel.

[0233] In both the first and second uses, preferably two pivot jewels can be used to guide the timepiece component relative to frame 99 or relative to another timepiece component.

[0234] According to a third use, the pivot jewel 1 is intended to receive a support of a timepiece component 98 (e.g. a lever) in the pivot hole 5. In this use, the pivot jewel acts as a runner, its outer surface 7 being intended to roll on another timepiece component. In this case, the outer surface 7 is intended to:

[0235] - rolling in the grooves of the drum while the gemstone is being made, and

[0236] After the watch component is manufactured, it is rolled on the watch component during use. The outer surface 7 may not be cylindrical. It may, for example, be generally frustoconical. Furthermore, it may have a convex or concave profile or a complex profile, such as a cam profile, in a plane perpendicular to the axis A1.

[0237] More generally, the invention also relates to a timepiece component such as a tube, for example a ceramic or metal tube, or a timepiece component such as a cannon-pinion, comprising a hole, in particular a cylindrical hole, the pivot hole comprising a surface having main abrasive working striations, in particular main polishing striations, oriented substantially orthogonally radially with respect to the axis of the hole.

[0238] The invention also relates to a timepiece movement 100 comprising at least one pivot jewel as described above, in particular at least two pivot jewels as described above, and / or comprising a timepiece component 98 comprising a pivot jewel 1 as described above, and / or comprising a component as described above.

[0239] The invention also relates to a timepiece 200, in particular a wristwatch, comprising:

[0240] - at least one pivot jewel 1 as described above, and / or

[0241] - a timepiece component as described above, and / or

[0242] - A timepiece movement 100 as described above.

[0243] Measuring the finish of the inner surface 6 of the pivot hole 5 presents a twofold challenge:

[0244] - Successfully approach the surface 6 where the finish needs to be measured, which is very difficult given the hole geometry, and then

[0245] -Measure the roughness itself.

[0246] It will be seen below how the gemstone is prepared in a first stage so that the finish of the friction surface 6 can then be measured in a second stage.

[0247] For measuring roughness, laser scanning confocal microscopy appears to be particularly advantageous. This is because it appears to be well-suited for concave surfaces. Laser scanning confocal microscopy allows for precise measurement of surface roughness even at very low magnifications, in accordance with ISO 25178 (areal roughness) and ISO 4287 (linear roughness).

[0248] In the context of this application, it is preferable to measure linear roughness rather than areal roughness, given the preferred orientation of the roughness. This is because measuring areal roughness involves taking an average over the surface area, which is relevant when the surface finish is uniform and non-directional, but is less appropriate in the current use case involving the concept of orientation of roughness. Therefore, it is more appropriate to consider linear roughness Ra, which is the arithmetic mean difference in the evaluated profiles.

[0249] The preferred orientation of the roughness can be quantified by considering the parameters Str and Std. According to the definition in the standard, the parameter Str (sometimes called "isotropy") is a measure of the uniformity of the surface texture and takes a unitless value between 0 and 1. If the surface has the same properties in all directions (isotropic surface), the Str value will be close to 1, while the Str value of a strongly anisotropic or textured surface will be close to 0.

[0250] If the surface is anisotropic (Str value close to 0), it is advantageous to determine the preferred direction of the texture, represented by the parameter Std. A useful tool for this is the polar spectrum, i.e. the integrated Fourier spectrum in polar coordinates. The angle corresponding to the strongest spectrum corresponds to the main texture direction, and the main direction of the spectrum gives the parameter Std, which is the counterclockwise angle of this main direction with the reference axis of the image. Therefore, for this it is important to always orient the image in the same way with respect to this reference axis. Furthermore, it is preferable to perform these measurements excluding the edges of the image or component, to align the surface to eliminate the influence of the shape, and, if possible, to provide a suitable acquisition spacing and square image size.

[0251] This preferential orientation of the roughness, quantified by the parameters Str and Std, and in particular the preferential direction of the texture, represented by the parameter Std (this parameter Std being the counterclockwise angle of this principal direction with respect to the reference axis of the image), corresponds to the orientation of the main fringes that determine the surface roughness. In other words, for example, if the counterclockwise angle of the preferential direction of the texture, represented by the parameter Std, is substantially a right angle with respect to the first axis A1, then the main fringes are considered to be oriented substantially orthogonally radially with respect to the first axis A1.

[0252] For roughness measurement, for example, a tool equipped with a pinhole confocal optical system, such as the VKX-1100 from Keyence, can be used. Key parameters are vertical and lateral resolution, and the optimal optical resolution is achieved using a 50x lens with an aperture of 0.95 on such a tool, with sufficient working distance to measure the region of interest of a gemstone prepared according to the procedure described below. Measurements are performed in the center of the gemstone. The segment length is selected according to ISO 4287; for example, 30 different segments are measured consecutively, each segment being cut into five sub-segments according to the standard to minimize the influence of the profile shape.

[0253] The measured segments are oriented perpendicularly to the residual polishing streaks 61 and / or perpendicularly to the preferential direction of the texture, represented by the parameter Std, in order to obtain a measurement value characterizing the roughness. In other words, when the residual machining or polishing scratches are oriented in the axial direction (e.g., after enlargement), the measured segments are oriented in the orthogonal radial direction, whereas when the residual machining or polishing scratches 61 are oriented in the orthogonal radial direction (e.g., after the polishing process according to the invention described above), the measured segments are oriented in the axial direction.

[0254] The roughness values obtained may of course vary with the measuring equipment and technique used. The values shown in this article were obtained on a laser scanning confocal microscope at a magnification of 50 times by measuring 30 segments and calculating the roughness Ra.

[0255] To perform the measurement, for example, a half-gemstone from the preparation described below can be placed in a vise and then focused on the measurement area, for example using successive lenses, until a sharp image is obtained at 50x magnification. An image resolution of 2048 x 1536 pixels can be used, with a spacing of 0.10 μm between segments. The segment length can be 65 μm, with 30 lines spaced 2 μm apart. The roughness is measured perpendicular to the remaining machining or polishing streaks. According to this standard, the roughness Ra measurement is applicable if, and only if, the ratio between the standard deviation and the obtained value Ra is strictly less than 0.2.

[0256] Based on tests conducted on several batches of minute wheel gemstones obtained using various processes, it was noted that, for the standard enlargement process, the remaining polishing striations are oriented in the axial direction, and therefore the measurement lines are oriented in the orthogonal radial direction. The measured roughness is 25.5 ± 5.0 nm.

[0257] Using the polishing process according to the present invention, the remaining polishing stripes are oriented in the orthogonal radial direction, the measuring line is oriented in the axial direction, and the measured roughness is 4.0±1.6 nm.

[0258] The surface texture is evident in both cases, with comparable Str (isotropy) values close to 0. However, the isotropy (Str) remains strictly greater than 0, in particular greater than 1%. It is about 20% for the standard amplification method, while it is less than 10%, or even less than 3%, for the method according to the invention. In particular, the method according to the invention makes it possible to obtain a roughness Ra of less than 5 nm, with a preferential orientation of the texture with respect to the direction parallel to the axis of the pore of 90°+ / -0.5° and an isotropy greater than 1% and less than 10%, in particular less than 3%. This difference is particularly evident in the polarographic and Std values, with the Std texture having a preferential direction of 7° and 90.1° for the standard amplification method and the method according to the invention, respectively.

[0259] The above measurement process can be used for any type of gemstone, including those with a marquise cut. As mentioned above, the goal of a marquise cut is to achieve a rounded, rather than a straight, pivot hole profile. The edge corners of the hole are softened, and the deflection (the diameter difference between the center and edge of the hole) is measurable and is at least 3 μm, more typically at least 5 μm. This deflection value is not specified in the design because, until now, there has been no possible way to measure this characteristic; the presence of a marquise cut is typically only observed through visual inspection, based on the reflected elliptical shape in the hole. The deflection value also depends on the hole diameter and length. In contrast, when measuring a typical profile of a gemstone according to the present invention, the edge corners of the hole are well-defined, and the deflection of the hole profile is 0.175 μm. In a measurement batch of 40 gemstones, the measured deflection ranged from 0.1 to 0.2 μm within a 150 μm range around the hole opening. In finished gemstones, the deflection can be even smaller, as the hole length can be reduced through possible slotting operations.

[0260] The above-described measuring method can also be applied to other timepiece components comprising a hole, such as a tube, for example a ceramic tube or a metal tube, or a timepiece component such as a cannon pinion.

[0261] The geometry of the gemstone makes it very difficult to quantitatively measure the finish of the surface 6 of the pivot hole 5. This surface can only be viewed directly by tilting the gemstone to a considerable degree, and measurements on tilted and / or confined surfaces are difficult to perform.

[0262] Thus, one embodiment of the stage of preparing pivot jewel 1 comprises ablating a first portion of pivot jewel 1, so as to obtain a second portion of pivot jewel 1, this first portion comprising a portion of surface 6 of pivot hole 5, as well as a portion of outer surface 7 and a portion of the volume between surface 6 of the pivot hole and outer surface 7. This stage of preparing the jewel makes it possible to quickly and reproducibly obtain an element that allows direct and unobstructed access to the area of surface 6 to be measured for measurement. Figure 1 The illustration in FIG. 1 provides a good representation of the second jewel portion obtained through the preparation process. Specifically, the first portion of the pivot jewel can be ablated through a plane passing through or parallel to the axis A1 of the pivot hole 5 . The goal is to allow direct axial access to all contours of the surface of the pivot hole, in particular, access by a light beam or laser beam perpendicular or substantially perpendicular to said contours.

[0263] To access the pivot hole of a gemstone, it would seem that all that is necessary is to strike the gemstone with a tool so as to fracture it and produce a fragment while leaving the surface of the pivot hole partially intact. However, this method is highly random, non-reproducible, and unsuitable for routine inspection.

[0264] The first method requires the removal of material from a portion of the gemstone, in particular by ablation.This method is particularly advantageous when a certain number of gemstones of the same kind must be examined, for example by randomly examining 20 gemstones from a batch of 1000.

[0265] The quality of the ablated portion is unimportant, as it is not measured. However, it is necessary to ensure that the cutting process does not alter the sample at the hole. A fine grinding process, for example, is suitable for enabling the portion to be prepared quickly by cutting. To position the gemstones at the same level and protect the pivot hole, and in particular to avoid the presence of coating resin in the hole when using such a material, it is advantageous to thread the gemstones onto a wire (preferably made of nylon or another polymer) with a diameter slightly smaller than the hole diameter (for example, 10 μm smaller). It is also possible to use a wire with a gap greater than 10 μm and melt the end so as to block the hole of the gemstone at the end, thereby ensuring that there is no contamination in the hole. It is also possible to use a wire made of metal, such as brass, particularly a small diameter wire, for example less than 0.2 mm. When using a metal wire, it is important to adjust the wire well relative to the hole diameter to prevent the coating resin from entering the hole and making subsequent measurements impossible.

[0266] Once coated, the gemstones can be easily polished, for example, until they have a height difference between the bottom of the hole and the cutting or ablation surface that is approximately the hole radius, for example 0.2 mm, allowing easy access to the area to be measured by the measuring instrument. The wire can remain in place throughout the polishing step and is removed only before cleaning and measuring the gemstone. The gemstone can be aligned at a comparable height to the surface to be measured in a configuration well suited for automated measurement. Batches of dozens or even hundreds of gemstones can be measured automatically in this way.

[0267] Thus, the sub-step of assembling a plurality of pivot stones 1 may be performed before ablation.

[0268] The second method is particularly suitable for preparing individual gemstones, such as unique gemstones, and in particular gemstones removed from a blank for a movement. This second method consists in ablation by fragmentation.

[0269] This process allows for simple and reproducible cutting of gemstones to access the inner walls of watch gemstones (in particular synthetic rubies) in order to measure roughness. The principle is to cut the gemstone using a diamond tool (such as a diamond chisel or a diamond-tipped tool) on one of the upper or lower faces (for example, on a non-recessed surface) in order to induce a fracture so that the gemstone can then be broken by subjecting it to a small impact.

[0270] Before cutting, ensure that the gemstone is in good condition, for example, by examining it under an optical microscope. Dust is removed from the gemstone as needed, for example, by washing it in water or a solvent. The gemstone is first placed with its flat side facing the operator and cut with a diamond tool. The cut gemstone is then positioned so that a small impact can be applied, such as with a hard metal staking punch placed on a staking tool. A gentle blow, such as that applied by a watchmaker's hammer to the shank of the staking tool, can fracture the gemstone at the onset of fracture. For this step, the gemstone can be held in a fitting, a vise, or any other support or device suitable for holding it in place.

[0271] The two semi-precious stones are then recovered, possibly cleaned to remove any residue or particles, and then measured. It should be noted that this method of cutting and fracturing by impact produces significantly less particles and debris than traditional wire sawing. This second method is also repeatable and does not rely on the dexterity of the person performing it.

[0272] Alternatively, the gemstone or batch of gemstones can also be cut with a saw or wire. However, this third method is less advantageous in view of the risk of chips generated by the cutting in the area near the surface to be measured.

[0273] Thus, in summary, a method can determine the roughness of the surface 6 of the pivot hole 5 of the pivot jewel 1. The method comprises:

[0274] - a first preparation step for preparing pivot jewel 1, which comprises ablating a first portion of pivot jewel 1, comprising a portion of surface 6 of pivot jewel 1, comprising pivot hole 5, so as to obtain a second portion of pivot jewel 1, and then

[0275] A second measurement step, performed on surface 6 of pivot hole 5 situated on the second part of pivot jewel 1 .

[0276] Logically, the preparation of the jewel, in particular the ablation of the first portion of the pivot jewel, does not modify the pivot surface situated on the second portion of the pivot jewel, so that the roughness measurement obtained actually represents the surface finish of the pivot hole obtained after the production of the timepiece component, in particular after machining and polishing the timepiece component.

[0277] The above-described preparation method can be used for any type of gemstone, including gemstones for marquise cuts. The preparation method can also be applied to other watch components comprising holes, such as tubes, for example ceramic tubes or metal tubes, or watch components such as cannon pinions.

[0278] The invention also relates to the washing of a timepiece component. Therefore, one embodiment of the steps for washing the timepiece component 1 and the machining support 20 while the machining support 20 is housed in the hole of the timepiece component 1 is described in detail below.

[0279] This washing step is advantageously implemented in the process for producing pivot jewels as described above and includes the step of polishing the pivot hole.

[0280] However, more generally, the washing step may be implemented in any method for producing a timepiece component comprising a hole, the method comprising:

[0281] a step of machining the hole by abrasion using abrasive particles, in particular diamond particles, which are free relative to the machining support and roll between the surface of the hole to be machined and the machining support housed in the hole, and / or using abrasive particles capable of detaching from the machining support.

[0282] As a result, a washing step may also be applied in the method of producing a marquise-cut gemstone after the step of machining the marquise-cut.

[0283] In these methods, some abrasive remains on the work support and the gemstone once the gemstone 1 has passed the rollers 31. Studies conducted through preparation and measurement processes have shown that this presence of residual abrasive often causes problems when the gemstone is removed from the wire, that is, when it is removed from the work support.

[0284] This is because when the gemstone is removed from the wire or when the part is removed from the machining support, abrasive particles can become lodged in the pivot hole and create streaks in the axial direction. These scratches or streaks can adversely affect the surface finish of the hole by causing considerable roughness oriented in the axial direction and / or by potentially disrupting the uniformity of the rounding of the olive cut, which is undesirable.

[0285] Without the washing step, scratches in the axial direction are typically observed. These scratches can be low in density and depth, but can also be quite pronounced. In all cases, roughness is reduced, and the effects of the olive cut on surface finish are partially or even completely eliminated. In this case, this reduction is undoubtedly due to the olive cut itself, rather than a residual effect of the expansion process, as the olive cut does indeed bring the hole to its final dimensions, removing a significant amount of material far greater than the depth of the remaining expansion streaks. Furthermore, the observed scratches superimpose the characteristic contours of the olive cut, with a symmetrical shape and deflections typically several μm or more.

[0286] The addition of a step of washing the machining support and the gemstone to remove the abrasive before removing the gemstone from the wire makes it possible to avoid damaging the polished or machined surface. This washing or cleaning can be carried out in various ways, for example in an aqueous medium or solvent, with or without detergent, with or without ultrasound, or by blowing steam, or by cleaning with water or a solvent. This cleaning can be performed directly on the device to clean the gemstone directly at the runoff of the roller 31, or outside the device after removing the machining support. Preferably, the washing is performed using a fluid stream that is used to carry away the abrasive particles used during machining or polishing. The fluid can be a washing solution, in particular an aqueous solution, an alcoholic solution, or an oily solution.

[0287] Additionally or alternatively, the washing step may comprise immersing the timepiece component 1 and the machining support 20 in a washing liquid. The immersion may comprise emitting ultrasonic waves into the washing solution.

[0288] Additionally or alternatively, the washing step may comprise spraying a washing solution onto the timepiece component 1 and the machining support 20 .

[0289] Additionally or alternatively, the washing step may comprise blowing gas or steam.

[0290] A washing system 84 can be placed just after the rollers. Thus, the washing step can be carried out directly on the processing machine, in particular on a polishing machine that carries out the step of processing the holes by abrasion. The washing system 84 can be part of the processing machine 30. This washing system makes it possible to wash or clean the gemstones and the processing support immediately after polishing or marquise cutting or any other processing. The washing system advantageously comprises nozzles 83 and / or channels for spraying a washing fluid, such as a washing solution. Preferably, these nozzles and / or these channels are arranged so as to generate both jets directed in the direction of forward movement and jets directed in a direction opposite to the forward movement of the gemstone on the processing support, which first cleans the gemstone on both sides and then cleans the gemstone in the direction of forward movement at the end of the washing system as the gemstone leaves the washing system. The washing system is advantageously designed to form a housing 80 in two parts 81, 82 so that it can be partially opened, for example to fit a new processing support or to set the position of the washing system relative to the processing support and the rest of the machine. As a result, the washing system 84 can take the form of Figure 7 The form of the case 80 shown. The assembly consisting of the timepiece component 1 and the machining support 20 can pass through this case 80. The case 80 thus has access for the machining support.

[0291] In an alternative, the washing step may be performed after removing the assembly consisting of:

[0292] - a watch component 1, and

[0293] - machining support 20. In this case, the assembly consisting of timepiece component 1 and machining support 20 is removed from the machining machine, then washed, and then the timepiece component 1 is removed or separated from the machining support 20, in particular by removing the machining support 20 from the hole in the timepiece component 1.

[0294] More generally than described above, a method for producing a timepiece component 1 may comprise:

[0295] - a step of machining the hole 5 by abrasion using abrasive particles 21 that are free relative to the machining support 20 and that roll between the surface 6 of the hole to be machined and the machining support 20 housed in the hole, and / or using abrasive particles that can break away from the machining support, and then

[0296] - a step of washing the timepiece component 1 and the machining support 20 while the machining support is housed in the hole, and then

[0297] - A step of removing said machining support from said hole.

Claims

1. A method for producing a pivot jewel (1) for a watch movement (100), the pivot jewel (1) comprising a pivot hole (5), in particular a straight or cylindrical pivot hole, having a first axis (A1), capable of pivoting a watch component (98), such as a watch axle, or capable of pivoting about the watch component (98), the method comprising a first polishing step, in which: (i) using free abrasive particles (21), in particular diamond particles, rolling between the surface (6) of the pivot hole (5) to be polished and a polishing support (20), such as a wire (20), and / or (ii) driving the pivot jewel (1) in rotational motion about the first axis (A1) relative to the polishing support (20), the polishing support (20) being pulled back towards the surface (6) of the pivot hole (5) to be polished.

2. The production method according to claim 1, characterized in that During the first polishing step, the pivot jewel (1) is held in position relative to the polishing support (20) by contact with its peripheral surface (7).

3. The production method according to claim 1 or 2, characterized in that: - the first axis (A1) is parallel or substantially parallel to the surface of the polishing support (20), and / or The first axis (A1) is parallel or substantially parallel to the second axis (A3) of the polishing support (20), so that the polishing support is in particular constituted by a wire (20).

4. The production method according to any one of claims 1 to 3, characterized in that During the first polishing step, the pivot jewel (1) is driven relative to the polishing support (20) by contact with its peripheral surface (7).

5. The production method according to any one of claims 1 to 4, characterized in that During the first polishing step, the pivot jewel (1) is driven in a straight helical or rotational motion about the first axis (A1) relative to the polishing support (20).

6. The production method according to any one of claims 1 to 5, characterized in that The angle between the first axis (A1) and the second axis (A3) of the polishing support is less than 0.5°.

7. The production method according to any one of claims 1 to 6, characterized in that The free abrasive particles (21) are contained in a suspension, in particular a water-based or oil-based suspension, covering the polishing support.

8. The production method according to any one of claims 1 to 7, characterized in that During the first polishing step, a gap of between 5 μm and 20 μm, typically 10 μm, is formed between the polishing support (20) and the pivot hole (5).

9. The production method according to any one of claims 1 to 8, characterized in that The method comprises, after the first polishing step, a second machining step of machining a recess (3) on one or two faces (2, 4) of the pivot jewel (1), the faces (2, 4) extending perpendicularly or substantially perpendicularly to the first axis (A1).

10. The production method according to any one of claims 1 to 9, characterized in that The method comprises, after the first polishing step, a third polishing step of polishing at least one face (2, 4), preferably two faces, of the pivot jewel (1), said faces (2, 4) extending perpendicular or substantially perpendicular to the first axis (A1).

11. The production method according to any one of claims 1 to 10, characterized in that The speed of the pivot jewel (1) relative to the polishing support (20) at the point of contact with the polishing support (20) is in the range between 1 m / s and 10 m / s or between 1 m / s and 20 m / s in an orthogonal radial direction relative to the first axis (A1) .

12. A machine (30) for polishing the pivot hole (5) of a pivot jewel (1) of a watch movement (100), the pivot jewel (1) having a pivot hole oriented along a first axis (A1), the machine comprising a roller (31) driven in rotation about a second axis (A2) and having a slot (32) forming a spiral around the roller (31), the slot (32) being used to drive the pivot jewel and to hold the pivot jewel in a position such that the first axis (A1) is perpendicular to the osculating plane of the spiral at the contact between the pivot jewel and the slot.

13. The polishing machine according to claim 12, characterized in that The polishing machine comprises a polishing support (20) having a second axis (A3), and: - the second axis (A3) of the polishing support and / or the first axis (A1) of the pivot hole are perpendicular to a tangent to the spiral of the slot, and / or - the second axis (A3) of the polishing support and / or the first axis (A1) of the pivot hole are perpendicular to the osculating plane of the spiral of the slot at the contact between the pivot jewel and the slot (32).

14. The polishing machine according to claim 12 or 13, characterized in that: The helix angle of the helix around the roller (31) is less than 0.1° or less than 0.05°.

15. The polishing machine according to any one of claims 12 to 14, characterized in that The machine comprises a polishing support (20) in the form of a wire intended to hold the pivot jewel at the bottom of the slot (32) and to polish the pivot hole (5) by abrasion.

16. The polishing machine according to any one of claims 12 to 15, characterized in that The machine comprises an element (35) for setting the orientation of the polishing support (20) relative to the second axis (A2).

17. The polishing machine according to any one of claims 12 to 16, characterized in that The machine comprises a jig (33) for distributing the pivot stones (1), the jig being arranged to feed the drum (31) by bringing the pivot stones one at a time to the drum.

18. The polishing machine according to any one of claims 12 to 17, characterized in that The diameter of the drum (31) is greater than 10 cm and / or the profile of the slot is U-shaped or rectangular, in particular without chamfers at the bottom of the slot, to make it easier to correctly maintain the pivot jewel in its vertical position relative to the drum (31).

19. The polishing machine according to any one of claims 12 to 18, characterized in that The polishing machine comprises a feeding element (38) for depositing a suspension containing free abrasive particles (21) onto the polishing support (20).

Images