Method and system for washing a timepiece stone

Abstract

Disclosed is a method for producing a timepiece component (1), in particular a pivot stone (1), having a hole (5), the method involving: - a step of abrasively machining the hole (5) using abrasive particles (21) that are free relative to a machining support (20), in particular diamond particles, which roll between the surface (6) of the hole to be machined and the machining support (20) accommodated in the hole, and / or using abrasive particles that can detach from the machining support, followed by - a step of washing the timepiece component (1) and the machining support (20) while the machining support is accommodated in the hole, and then - a step of removing the machining support from the hole.

Description

[0001] Process and system for washing watch stone.

[0002] The invention relates to a pivoting stone for a watch movement. The invention relates to a method for producing such a pivoting stone and a machine for polishing such a pivoting stone. The invention also relates to a method for determining the roughness of a surface of a pivoting hole of such a pivoting stone. The invention also relates to a watch component comprising such a pivoting stone. The invention also relates to a watch movement, comprising such a pivoting stone or such a watch component. The invention finally relates to a timepiece comprising such a watch movement or such a pivoting stone or such a watch component.

[0003] The invention also generally relates to a method for producing a component comprising a hole. The invention also relates to:

[0004] - such a watch component,

[0005] - a watch movement comprising such a watch component, and

[0006] - a timepiece comprising such a watch movement or such a watch component.

[0007] Watch jewels are crucial elements for the proper functioning of a watch movement. Almost all rotational movements are ensured by axes pivoted in bearings, which are made of drilled ruby ​​elements, also called functional jewels or pivot jewels.

[0008] In a known manner, to produce a pivot stone, a ball of material, in particular a ball of synthetic ruby, more particularly a ball of monocrystalline synthetic ruby, is cut by sawing or wire cutting or laser cutting into plates of a determined thickness. These plates are then cut to form blanks (preparations) of the stones which are brought to a cylindrical external shape, for example by a turning operation.

[0009] The stones are then drilled, for example by laser or by a spindle, in order to obtain the rough shape of a pivot hole. The stones are then subjected to a scaling step which allows to arrive at the final diameter and the desired surface finish of the pivot hole. A turning step then allows to bring the stone to its nominal external diameter. A possible hollowing operation allows to form a hollow on one or two faces of the stone to serve as an oiler for lubrication. Finally, a polishing allows to bring the thickness of the stone to its final dimension and the desired surface finish. A possible final polishing allows to obtain a desired external surface finish. This polishing does not modify the surface finish of the pivot hole.

[0010] The enlarging step is crucial because it determines not only the size but also the surface finish of the pivot hole. To do this, the stones are threaded onto a wire and secured together, which allows them to rotate around the axis of the pivot holes and to perform batch processing. The wire is generally conical, with a diameter that gradually increases until the final target diameter. By adding an abrasive and a back-and-forth movement of the wire, the hole is gradually enlarged to its final size. The rotation speed of the stones is much lower than the translation speed of the wire, and the machining is mainly due to the back-and-forth movement of the wire.Residual machining grooves are therefore necessarily oriented along the axis of the pivot stone or the pivot hole, with a possible inclination of the grooves of a few degrees relative to this axis, given the rotation speeds and movement of the wire relative to the stones. The equipment used and the very principle of the enlarging process do not allow for another orientation of the residual machining grooves. For certain pivot stones, it is desirable to obtain an olived hole, that is to say with a non-cylindrical hole and presenting a convex rounded profile minimizing the diameter of the hole towards its middle. Such an olived hole reduces the friction surface of the pivots of the axes and facilitates lubrication. To obtain an olived hole, the stones are again threaded onto a wire and then are subjected to a particular olived process described below.Stones with a straight or cylindrical hole are not olive-plated and are not subjected to any process other than the magnifying described above.

[0011] The article "The Watchmaking Stone" by Pierhor SA, published in the Swiss Chronometry Society Bulletin No. 69 (06.2012), describes the main steps in the manufacturing processes for different stones, as well as the different types of stones. The glazing process is illustrated in Figure 4 of this article. The operation is carried out on machines by tilting the stones on a roller equipped with a helical groove, using a wire of a precise diameter loaded with a diamond suspension. The stone is pulled by the groove along the roller, and the wire allows the abrasion of the ends of the pivot hole. A good choice of parameters makes it possible to reverse the direction of inclination of the stone in the middle of the roller and thus obtain a glazing that is as regular and symmetrical as possible.

[0012] Documents CH121766 and CH336311 describe machines for making stones, with a wire coated with a mixture of oil and diamond powder, either for boring / enlarging by reciprocating in the axial direction; or for scaling with an inclination of the stone.

[0013] Document CH706268 emphasizes the effect of the olive-plating of the stones, which helps reduce friction.

[0014] Document CH393194 describes a stone manufacturing process that allows for the achievement of very low surface roughness, followed by treatment of the friction zones to obtain a topography / roughness suitable for maintaining the lubricant, by intentionally creating small holes, grooves, roughness or undulations. These inequalities are of the order of magnitude of a few molecules of the lubricant used, i.e. a fraction of a micrometer according to the applicant. However, the document does not cite any value or quantitative element, and does not mention any concrete process for obtaining the surface condition in question.

[0015] Document EP2778801 describes a sintered stone with a laser-formed hole, then finished by lapping, brushing and / or polishing for local modification of the roughness, without further details.

[0016] Documents EP3835881 and EP3835882 also relate to various aspects of a method for manufacturing polycrystalline stones by pressing. These stones have the particularity of comprising a flared hole, the smallest diameter of which may be less than 0.1 1 mm. This method aims here to propose an alternative to methods using a laser which, according to the applicant, would not allow a quality surface finish to be obtained directly. Producing the stone by pressing would allow a good surface finish to be obtained, whereas the stone drilled by femtosecond laser would have an unsatisfactory surface finish.

[0017] The aim of the invention is to provide a high-performance pivot stone that improves the pivot stones known from the prior art. In particular, the invention provides a pivot stone with improved pivot characteristics, in particular improved roughness characteristics, and methods associated with such a stone.

[0018] According to a first aspect, the invention is defined by the following propositions. 1. Pivoting stone (1) for a watch movement (100), the pivoting stone (1) comprising a pivoting hole (5) having a first axis (A1) and capable of pivoting a watch component (98) or capable of pivoting around a watch component (98), such as a watch axis, the pivoting hole comprising a surface (6) having main abrasion machining grooves (61), in particular main polishing grooves, oriented substantially orthoradially relative to the first axis (A1).

[0019] 2. Pivot stone (1) according to proposition 1, characterized in that the main machining grooves (61) have a helix angle of less than 1° or less than 0.5°.

[0020] 3. Pivot stone (1) according to proposition 1 or 2, characterized in that the main machining grooves (61) are parallel or substantially parallel to a plane perpendicular to the first axis (A1) and / or form an angle of less than 1° or less than 0.5° relative to a plane perpendicular to the first axis (A1).

[0021] 4. Pivot stone (1) according to one of proposals 1 to 3, characterized in that the main machining grooves (61) have an orientation dispersion of plus or minus 0, with 0>0.2°, in particular with 0 of the order of 0.5°, around an average orientation.

[0022] 5. Pivot stone (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 grooves (61), is less than 20 nm or less than 10 nm or less than 5 nm.

[0023] 6. Pivot stone (1) according to one of the proposals 1 to 5, characterized 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.

[0024] 7. Pivot stone (1) according to one of proposals 1 to 6, characterized in that the profile of the surface (6) of the pivot hole (5), according to a plane passing through the first axis (A1), is straight or cylindrical.

[0025] 8. Pivot stone (1) according to one of proposals 1 to 6, characterized in that the profile of the surface (6) of the pivot hole (5), according to a plane passing through the first axis (A1), is convex seen from the first axis (A1) with an arrow less than 1 pm or less than 0.5 pm or less than 0.25 pm.

[0026] 9. Pivot stone (1) according to one of proposals 1 to 8, characterized in that it is made of technical ceramic, in particular ruby.

[0027] 10. Pivoting stone (1) according to one of proposals 1 to 9, characterized in that it comprises a rolling surface (7), in particular a rolling surface (7) of first axis (A1), intended to roll on a watch component.

[0028] 1 1. Pivot stone (1) according to one of proposals 1 to 10, characterized in that the geometries and / or positions of the main grooves are not controlled.

[0029] 12. Pivot stone (1) according to one of the proposals 1 to 11, characterized in that the surface (6) has an isotropy:

[0030] - strictly greater than 0, in particular greater than 1%, and

[0031] - less than 10%, in particular less than 3%. 13. Watch component (98), in particular mobile (98), in particular center mobile, comprising at least one pivoting stone according to one of proposals 1 to 12, in particular at least two pivoting stones according to one of proposals 1 to 12.

[0032] 14. Watch movement (100) comprising at least one pivoting stone according to one of propositions 1 to 12, in particular at least two pivoting stones according to one of propositions 1 to 12 and / or comprising a watch component (100) according to proposition 13.

[0033] 15. Watch movement (100) according to proposition 14, characterized in that the at least one stone pivots a watch component, said watch component being:

[0034] - a pendulum, or

[0035] - an anchor, or

[0036] - an escape wheel.

[0037] 16. Watch movement (100) according to proposition 14, characterized in that the at least one stone pivots a watch component being a mobile of a finishing train, such as:

[0038] - a high average, or

[0039] - a small average, or

[0040] - a seconds mobile.

[0041] 17. Watch movement (100) according to proposition 14, characterized in that the at least one stone pivots a watch component being a mobile of an automaton chain.

[0042] 18. Timepiece (200), in particular wristwatch, comprising:

[0043] - at least one pivot stone (1) according to one of propositions 1 to 12, and / or - a watch component (98) according to proposition 13, and / or

[0044] - a clock movement (100) according to one of propositions 14 to 17.

[0045] According to a second aspect, the invention is defined by the following propositions.

[0046] 19. Method for producing a pivot stone (1) for a watch movement (100), the pivot stone (1) comprising a pivot hole (5) having a first axis (A1), in particular a straight or cylindrical pivot hole and having a first axis (A1), and capable of pivoting a watch component (98), such as a watch axis, or capable of pivoting around a watch component (98), the method comprising a first polishing step in which:

[0047] (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 medium (20), such as a wire (20), and / or

[0048] (ii) the pivoting stone (1) is driven in a rotary movement along the first axis (A1) relative to a polishing support (20) returned towards the surface (6) of the pivoting hole (5) to be polished.

[0049] 20. Production method according to proposition 19, characterized in that, during the first polishing step, the pivot stone (1) is held in position relative to the polishing support (20) by contact on the peripheral face (7).

[0050] 21. Production method according to one of proposals 19 and 20, characterized:

[0051] - in that the first axis (A1) is parallel or substantially parallel to a surface of the polishing support (20), and / or - in that the first axis (A1) is parallel or substantially parallel to a second axis (A3) of the polishing support (20), the polishing support consisting in particular of a wire (20).

[0052] 22. Production method according to one of proposals 19 to 21, characterized in that, during the first polishing step, the pivoting stone (1) is driven relative to the polishing support (20) by contact on the peripheral face (7).

[0053] 23. Production method according to one of proposals 19 to 22, characterized in that, during the first polishing step, the pivoting stone (1) is driven in a right rotary or helical movement along the first axis (A1) relative to the polishing support (20).

[0054] 24. Production method according to one of proposals 19 to 23, characterized in that the angle between the first axis (A1) and a second axis (A3) of the polishing support is less than 0.5°.

[0055] 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 an aqueous or oily suspension, covering the polishing support.

[0056] 26. Production method according to one of proposals 19 to 25, characterized in that, during the first polishing step, a clearance of between 5 pm and 20 pm, typically 10 pm, is left between the polishing support (20) and the pivot hole (5).

[0057] 27. Production method according to one of proposals 19 to 26, characterized in that the method comprises, after the first polishing step, a second step of machining a hollow (3) on one or two faces (2, 4) of the pivot stone (1), the face or faces (2, 4) extending perpendicularly or substantially perpendicularly to the first axis (A1).

[0058] 28. Production method according to one of proposals 19 to 27, characterized in that the method comprises, after the first polishing step, a third step of polishing at least one face (2, 4), preferably two faces, of the pivot stone (1), the face or faces (2, 4) extending perpendicularly or substantially perpendicularly to the first axis (A1).

[0059] 29. Production method according to one of proposals 19 to 28, characterized in that the speed of the pivoting stone (1) in the orthoradial direction relative to the first axis (A1) at the level of contact with the polishing support (20) and relative to the polishing support (20) is between 1 m / s and 10 m / s or between 1 m / s and 20 m / s.

[0060] 30. Machine (30) for polishing pivot holes (5) of pivot stones (1) for a watch movement (100), the pivot stones (1) having pivot holes oriented along a first axis (A1), the machine comprising a drum (31) driven in rotation about a second axis (A2) and having a groove (32) for driving the pivot stones forming a helix on the drum (31) and for holding the pivot stones in a position such that the first axis (A1) is perpendicular to the osculating plane of the helix at the level of contact between the pivot stone and the groove.

[0061] 31. Polishing machine according to proposal 30, characterized in that it comprises a polishing support (20) having a second axis (A3) and in that:

[0062] - the second axis (A3) of the polishing support and / or the first axis (A1) of the pivot holes is perpendicular to the tangent to the helix of the groove, and / or

[0063] - the second axis (A3) of the polishing support and / or the first axis (A1) of the pivot holes is perpendicular to the osculating plane of the helix of the groove at the level of the contact between the pivot stone and the groove (32).

[0064] 32. Polishing machine according to proposition 30 or 31, characterized in that the helix on the drum (31) has a helix angle of less than 0.1° or less than 0.05°.

[0065] 33. Polishing machine according to one of the proposals 30 to 32, characterized in that the machine comprises a wire-shaped polishing support (20) intended to hold pivot stones at the bottom of the groove (32) and to polish the pivot holes (5) by abrasion.

[0066] 34. Polishing machine according to one of proposals 30 to 33, characterized in that the machine comprises an element (35) for adjusting the orientation of the polishing support (20) relative to the second axis (A2).

[0067] 35. Polishing machine according to one of the proposals 30 to 34, characterized in that the machine comprises a clamp (33) for distributing the pivoting stones (1), the clamp being arranged to feed the drum (31) by bringing the pivoting stones one by one onto the drum.

[0068] 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 in that the profile of the groove is U-shaped or rectangular, in particular without a chamfer at the bottom of the groove, to facilitate good maintenance of the pivot stones in their vertical position relative to the drum (31). 37. Polishing machine according to one of the proposals 30 to 36, characterized in that it comprises a feed element (38) for depositing, on the polishing support (20), a suspension containing free abrasive particles (21).

[0069] According to a third aspect, the invention is defined by the following propositions.

[0070] 38. Method for producing a watch component (1), in particular a pivot stone (1), comprising a hole (5), the method comprising:

[0071] - a step of machining the hole (5) by abrasion using free abrasive particles (21) relative to a machining support (20), in particular diamond particles, rolling 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 released from the machining support, then

[0072] - a step of washing the watch component (1) and the machining support (20) while the machining support is housed in the hole, then

[0073] - a step of removing the machining support from the hole.

[0074] 39. Production method according to proposition 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.

[0075] 40. Production method according to proposition 39, characterized in that the washing step comprises soaking the watch component (1) and the machining support (20) in the washing solution.

[0076] 41. Production method according to proposition 40, characterized in that the soaking comprises the emission of ultrasound in the washing solution. 42. Production method according to one of propositions 38 to 41, characterized in that the washing step comprises spraying the watch component (1) and the machining support (20) with a washing solution.

[0077] 43. Production method according to one of proposals 38 to 42, characterized in that the washing step comprises blowing a gas or water vapor.

[0078] 44. Production method according to one of proposals 38 to 43, characterized in that the washing step is carried out on a machining machine, in particular on a polishing machine which has made it possible to carry out the step of machining the hole by abrasion.

[0079] 45. Production method according to one of proposals 38 to 43, characterized in that the washing step is carried out after removal of the assembly consisting of:

[0080] - the watch component (1), and

[0081] - the machining support (20) of a machining machine having made it possible to carry out the step of machining the hole by abrasion.

[0082] 46. ​​Production method according to one of proposals 38 to 45, characterized in that the washing step is carried out in a housing (80) crossed right through by the assembly constituted by the watch component (1) and the machining support (20).

[0083] 47. Washing system (84) comprising material means (80, 81, 82, 83) for implementing the step of washing a watch component (1) while a machining support is housed in a hole of a watch component (1) according to the method according to one of proposals 38 to 46, in particular: - a housing (80), for example generally formed by two parts (81, 82) movable relative to each other and / or having a passage for the machining support, and

[0084] - nozzles 83 and / or washing solution projection channels.

[0085] 48. Machining machine (30) comprising material means (20, 31, 34, 35, 36, 37, 38, 39, 40, 84) for implementing the method according to one of proposals 38 to 46, in particular comprising a washing system (84) according to proposal 47.

[0086] 49. Watch component (1), in particular pivot stone (1), obtained by implementing the method according to one of proposals 38 to 46.

[0087] 50. Watch movement (100) comprising a watch component (1) according to proposition 49.

[0088] 51. Timepiece (200) comprising a timepiece component according to proposition 49 and / or a timepiece movement (100) according to proposition 50.

[0089] According to a fourth aspect, the invention is defined by the following propositions.

[0090] 52. Method for determining the roughness of a surface (6) of a pivot hole (5) of a pivot stone (1) for a watch movement (100), the method comprising:

[0091] - a first step of preparing the pivot stone (1) comprising an ablation of a first part of the pivot stone (1) including (i) a part of the surface (6) of the pivot hole (5), (ii) a part of an external surface (7) of the pivot stone (1) and (iii) a part of the volume between the surface (6) of the pivot hole and the external surface (7) in order to obtain a second part of the pivot stone (1), then - a second step of measuring the surface (6) of the pivot hole (5) located on the second part of the pivot stone (1).

[0092] 53. Determination method according to proposition 52, characterized in that the removal of the first part of the pivot stone is carried out along a plane passing through an axis (A1) of the pivot hole (5) or along a plane parallel to the axis (A1) of the pivot hole (5) and / or in that the first preparation step does not modify the surface (6) of the pivot hole (5) located on the second part of the pivot stone (1) but allows access thereto.

[0093] 54. Determination method according to one of proposals 52 and 53, characterized in that the ablation is carried out by abrasion.

[0094] 55. Determination method according to proposition 54, characterized in that a sub-step of assembling several pivot stones (1) is implemented before the ablation.

[0095] 56. Determination method according to one of proposals 52 to 55, characterized in that a sub-step of assembling one or more pivot stones (1) on a support is implemented before the ablation.

[0096] 57. Determination method according to proposition 55 or 56, characterized in that the assembly sub-step comprises threading pivot stones onto a wire.

[0097] 58. Determination method according to one of the propositions 52 to 57, characterized in that a sub-step of coating the pivot stone (1) or the pivot stones (1) is carried out before the ablation. 59. Determination method according to proposition 52 or 53, characterized in that the ablation is carried out by breaking.

[0098] 60. Determination method according to proposition 59, characterized in that a sub-step of making an incision of the pivot stone (1) on a face (2, 4) of the pivot stone (1) is implemented before the breakage.

[0099] 61. Determination method according to proposition 60, characterized in that the breakage is carried out by applying a shock to a part of the pivot stone (1), the other part of the pivot stone being held on a support, the parts being delimited by the incision.

[0100] 62. Determination method according to proposition 52 or 53, characterized in that the ablation is carried out by cutting with a saw or wire.

[0101] 63. Method according to one of proposals 52 to 62, characterized in that the second measurement step is carried out by confocal laser scanning microscopy.

[0102] 64. Method according to one of the proposals 52 to 63, characterized in that the second measuring step comprises a determination of a direction perpendicular to the main machining grooves (61) of the surface (6) of the pivot hole (5) of the pivot stone (1).

[0103] 65. Method according to proposition 64, characterized in that the second measuring step is a linear measurement in the direction perpendicular to the main machining grooves (61) of the surface (6) of the pivot hole (5) of the pivot stone (1). Unless there is a logical or technical incompatibility, all the characteristics of these different aspects can be combined with each other.

[0104] The accompanying drawings show, by way of example, embodiments of pivot stones, polishing machines and associated methods according to the invention.

[0105] Figure 1 is a perspective and longitudinal sectional view of one embodiment of a pivot stone according to the invention.

[0106] Figure 2 is a longitudinal sectional view of several pivot stones according to the invention being polished.

[0107] Figure 3 is a schematic side view of one embodiment of a polishing machine according to the invention.

[0108] Figure 4 is a schematic top view of the embodiment of the polishing machine according to the invention.

[0109] Figure 5 is a schematic representation of a first embodiment of a timepiece according to the invention.

[0110] Figure 6 is a schematic representation of a second embodiment of a timepiece according to the invention.

[0111] Figure 7 is a schematic representation of one embodiment of a washing system according to the invention.

[0112] The applicant's work has highlighted that the surface condition of the pivoting areas is essential to ensure the reliability of the watch movement, in particular to ensure the reliability of the pivoting of the axes in the pivoting jewels. The applicant has noted that it is still possible to improve the wear resistance of the pivots, in particular by removing or delaying the appearance of a black and viscous deposit likely to cause a loss of performance.

[0113] The applicant's developments have made it possible to obtain an excellent surface condition within the pivot hole of a stone, in particular for a stone with a straight or cylindrical hole, i.e. a hole without a conical, truncated or olive-shaped surface. These developments concern the method for measuring roughness, the method for preparing the stones for roughness measurement, the machine (or equipment) and the method for obtaining the optimized surface condition by polishing, the method for washing the stones after polishing, and the stone with the optimized surface condition. In particular, thanks to the solutions that are the subject of the invention, it is possible to obtain a roughness Ra of the pivot hole of less than 10 nm with a preferential orientation of the residual polishing striations in the direction orthoradial to the axis of the pivot hole.The grooves are machining grooves, in particular polishing grooves, their geometries and positioning on the surface of the pivot hole are largely uncontrolled and highly random. According to the invention, only:

[0114] - the depth of the grooves is roughly controlled by choosing an abrasive capable of producing nanometric depths, for example resulting in a roughness Ra of less than 20nm, and

[0115] - the orientation of the streaks is roughly controlled with an orientation dispersion of plus or minus 0, with 0>0.2°, in particular with 0 of the order of 0.5°, around an average orientation.

[0116] As mentioned above, watch jewels are a key element in the reliability of the watch movement. The challenge is to obtain a suitable surface finish with optimal reproducibility on all jewels within a production batch as well as from one batch to another. This is all the more necessary since controlling the surface finish of the pivot hole is very difficult to achieve and destructive.

[0117] Many pivots of watch movements are ensured and achieved by stones with straight or cylindrical holes. This is the case, for example, for large medium, small medium, seconds or calendar wheel pivots. In general, pivots with an axis equipped with a small diameter pivot (balance-spring oscillator, anchor, anchor wheel) are ensured by olive-plated stones (i.e., whose pivot hole has an olive-plated finish), while axes with a larger diameter (above 0.15 mm, for example) are pivoted in straight stones (i.e., with straight holes).

[0118] It was also noted by the applicant that a "cottoning" process, carried out by back and forth on a cotton thread with a suspension of diamond particles, makes it possible to obtain a better surface finish. However, this process is very difficult to implement for diameters less than 0.3 mm, and cannot be applied for mass production for certain critical pivoting movements of the finishing gear. Even for diameters less than 0.6 mm, this process can only be implemented manually, and it turns out that this manual polishing does not have the robustness of an industrial process and does not completely eliminate wear phenomena.

[0119] Furthermore, roughness measurements show that the stones obtained with the standard magnifying process have high roughness with an orientation of the residual polishing striations in the axial direction (i.e. parallel to the axis of the pivot hole, which is logical given the back-and-forth movement imposed on the stones relative to the wire during the process). The manual process mentioned above makes it possible to improve the roughness but does not modify the axial orientation of the striations. To eliminate wear phenomena, the inventors, on the contrary, found that it was necessary to obtain not only the lowest possible roughness, but also an orientation of the residual polishing striations in the orthoradial direction (to the axis of the pivot hole), in order to minimize the abrasion effects of the pivot stone on the axis it is intended to receive.

[0120] An embodiment of a pivot stone 1 for a watch movement 100 is shown in FIG. 1. The pivot stone 1 has a generally cylindrical shape with axis A1 and comprises a pivot hole 5 along the axis A1. This pivot hole 5 comprises a surface 6, in particular a cylindrical surface 6 or substantially cylindrical surface 6, and is intended to pivot a watch component, such as a watch axis, or capable of pivoting around a watch component. Furthermore, the pivot stone 1 is limited by:

[0121] - an upper face 2 and a lower face 4 both preferably extending perpendicularly to the axis A1, and

[0122] - a generally cylindrical external surface 7 of axis A1.

[0123] The pivot stone may also have a hollow 3 made on the upper face 2 and / or a hollow made on the lower face 4. The pivot stone may thus not have a hollow, have a hollow on one of the faces, have a hollow on each of the faces, or even have a curved face or two curved faces.

[0124] 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.

[0125] Surface 6 has main polishing striations 61.

[0126] The pivot stone 1 is preferably made of technical ceramic, in particular corundum or spinel or zirconia or SiC or silica, or possibly other natural or synthetic stones such as diamond. The pivot stone 1 may be made of polycrystalline or monocrystalline corundum, for example ruby, in particular Cr-doped alumina, for example synthetic Cr-doped alumina, or even monocrystalline Cr-doped alumina. The pivot stone 1 may also be made of an alumina-zirconia combination.

[0127] According to the invention, the method for producing a pivot stone 1 for a watch movement 100 makes it possible to obtain a surface condition inside the pivot hole 5 of the stone, in particular at the surface 6, which has the lowest possible roughness and an orientation of the roughness, that is to say an orientation of the main striations, in the direction of the relative movement between the stone and the watch component, in particular the axis, which it is intended to receive. This orientation is therefore in an orthoradial direction relative to the axis A1. It has been found that this orientation in fact makes it possible to minimize the effects of abrasion and therefore of wear at the contact between the pivot stone and the watch component, in particular the axis.

[0128] In one embodiment of the method for producing a pivot stone, the procedure is preferably as explained above, i.e. by carrying out the steps of:

[0129] - flow of material into plates,

[0130] - cutting the plates into blanks,

[0131] - filming,

[0132] - drilling of pivot hole blanks,

[0133] - possible enlargement, and

[0134] - possible digging and polishing.

[0135] However, in addition to or as an alternative to the magnifying step, a specific polishing step of the pivot hole is implemented, which is described in more detail below. This polishing step makes it possible to achieve the previously mentioned surface finish objective. The polishing is a three-body polishing illustrated by Figure 2. This polishing is carried out using a free abrasive 21 (in particular diamond grains of a determined diameter, suspended in an aqueous or oily base) which rolls between the pivot stone and a polishing support 20 of suitable geometry, in particular a wire. The wire may be a metal wire, in particular a metal wire of constant diameter. This three-body polishing makes it possible to obtain a neat surface finish and low roughness, as opposed to a two-body polishing where the abrasive is fixed on the polishing support and scratches the surface.To obtain the desired orientation of the residual polishing striations 61, namely to avoid orientation along the A1 axis, it is necessary:

[0136] - avoid back and forth polishing movements along the A1 axis of the pivot hole as usually implemented in the usual processes for obtaining standard straight holes, and

[0137] - instead, favor the rotational movements of the pivoting stone around the polishing support 20, that is to say around the axis A1.

[0138] Furthermore, to have a regular surface condition over the entire height of the hole and a hole which remains straight and / or cylindrical (as opposed to olive-shaped), the pivot stone must be kept straight relative to the polishing support, i.e. the axis A1 must be kept parallel to the surface of the polishing support 20 and therefore prevent the stone from being placed across and / or the axis of the hole in the stone from having a non-zero angle relative to the polishing support.

[0139] To simultaneously fulfill these different requirements, as illustrated in Figure 2, the stone 1 is threaded onto the polishing support 20, which is covered or loaded evenly with the abrasive 21. The stone is pressed by a force applied to the polishing support 20 against a roller or drum 31, which serves as a support surface and as a means for rotating the stone. During the polishing step, the pivoting stone 1 is therefore driven relative to the polishing support 20 by (rolling) contact on its peripheral face 7. To ensure good drive and rotational movement at high speed, as well as to prevent the stone from being skewed, a groove 32 (or groove 32) is made on the roller with a well-chosen width, depth, shape and groove pitch.

[0140] The width of the groove is chosen to guide the stone well, avoiding it becoming skewed, and is essentially determined by the thickness of the stone, taking into account a certain clearance. Typically, the width La of the groove is at least 50 pm greater than the nominal thickness e of the stone, for example 80 to 100 pm greater. The depth p of the groove must allow good guidance of the stone and good positioning of the wire above the roller, with a certain clearance j1 between the wire and the outer surface of the roller, typically a clearance of at least 200 pm, in particular a clearance between 200 and 400 pm. For example, for a stone with a diameter of 1.2 mm and a hole of 0.2 mm, the depth p of the groove could be 0.12 mm.The profile of the groove preferably has a rectangular shape (U-shaped or rectangular profile in a longitudinal plane passing through the axis A2), in particular a rectangular shape without broken angles or chamfers at the bottom of the groove, to facilitate good maintenance of the stone in its vertical position relative to the roller 31.

[0141] The groove pitch could be zero, meaning that each stone would be placed in an individual groove perfectly perpendicular to the roller axis. However, it is much more favorable from an industrial point of view to make a helical groove, therefore with a non-zero pitch, which allows the stone to be gradually advanced along the roller when it is rotated. The groove pitch can be at least once the width La of the groove, for example typically 1.5 times the width La of the groove, for example 0.6 mm for a groove width of 0.4 mm. The pitch also determines the total distance traveled by the stone on the roller: it is advantageous to choose the smallest possible pitch to maximize the distance and therefore the processing or polishing time.The diameter of the polishing support is chosen according to the diameter of the hole in the stone, in particular so as to leave a clearance j2 between the stone and the polishing support 20 while maintaining good tensile strength and limiting the tendency of the stone to tilt. Typically, the clearance j2 is between 5 pm and 20 pm and is for example 10 pm.

[0142] The axis of the polishing support must be very precisely oriented relative to the groove. In particular, the axis of the polishing support must be perpendicular to the orientation of the groove (or as close as possible to it). It is therefore necessary to precisely compensate for the helix angle of the groove. For this purpose, the required adjustment accuracy is <0.1 °. The polishing machine or equipment used to carry out such polishing therefore has a special construction, with a means for carrying out such precise adjustment. This amounts to tilting an axis A2 of the roller relative to an axis A3 of the polishing support, which axis A3 is parallel to the axis A1 of the pivot holes being polished.

[0143] As illustrated in Figure 4, this compensation angle, referenced a, can be determined precisely: if dr is the diameter of the roller and pa the pitch of the groove 32, a=atan(pa / (iTxdr)). This compensation angle a corresponds to the angle of the helix of the groove 32. In other words, the axis A3 of the polishing support and the axis A1 of the pivot holes must be perpendicular to the tangent to the helix of the groove 32. Alternatively, the axis A3 of the polishing support and the axis A1 of the pivot holes must be perpendicular to the osculating plane of the helix of the groove 32 at the contact between the pivot stone and the groove 32. This makes it possible to obtain a straight or cylindrical hole with a uniform roughness along the hole and with a substantially orthoradial orientation (to the axis A1) of the main machining striations. As an example, for a roller diameter of 250 mm and a groove 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 high precision of adjustment. In practice, an initial adjustment is made on the basis of the theoretical value, then a fine adjustment (of the order of a hundredth of a degree) is made so as to eliminate any trace of olive-likeness (i.e. to keep the hole as cylindrical as possible, i.e. to minimize the difference in diameter between the center and the edges of the hole) on the resulting stone.

[0144] It is important, for the proper implementation of the method according to the invention, that the axis A1 of the hole 5 of the pivoting stone 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 pivoting stone and the axis A3 of the polishing support is as small as possible, in particular less than 0.5°. For this, very good precision of adjustment of the compensation angle between the axis A3 of the polishing support and the axis A2 of the drum 31 is necessary.

[0145] The method described above may at first glance resemble an olive-grinding process. In fact, the polishing method according to the invention is carried out with stones threaded onto a polishing support and with a roller on which a helical groove is machined, which allows each stone to be advanced during polishing. However, the differences are numerous and significant:

[0146] - The purpose of swarfing is to machine the hole locally, and in particular the open ends of the hole, so as to obtain a rounded profile of the hole (the purpose of swarfing is to minimize the contact surface between the axis and the pivot hole). Swarfing is therefore a different machining from polishing. The quantity of material removed during swarfing is significant, the minimum diameter of the hole typically increasing by several micrometers during swarfing. In the case of swarfing, the difference between the minimum diameter of the hole before and after swarfing is typically 2 μm, and is even higher at the ends of the hole (determined according to the axial direction of the stone). Swarfing therefore makes it possible to bring the minimum diameter of the hole to the nominal dimension. On the contrary, in the case of the polishing method according to the invention, the diameter of the pivot hole is at its nominal value before the polishing step implemented in the method for producing a stone.It is estimated that the difference in diameter is less than 0.1 μm between (i) the state before implementing the polishing process and (ii) the state after implementing the process. In other words, the aim of the polishing process according to the invention is to reduce the peak-to-trough height of the striations produced during the drilling and / or enlarging operations by removing as little material as possible, so as to reduce the roughness, flatten the asperities and also to orient the roughness in the direction favorable to the movement of the component guided by the pivot hole during pivoting.

[0147] - The angle between the polishing support and the orientation of the grooves is not compensated but exaggerated when performing a swarfing, with a value typically in the order of 5 to 10°, or even 30°, which allows the stones to be inclined relative to the axis of the polishing support in order to break the edges of the edges of the hole and to achieve the rounded profile inside the hole. Precise control of the angle is not important for swarfing.

[0148] - Thus, in an olive-polishing process, the axis of the hole of the pivot stones is not parallel to the axis of the polishing support, but has a marked inclination, for example an angle of the order of 5 to 10°.

[0149] - Furthermore, in an olive-grinding process, the intersection of the roller cylinder with the vertical plane that includes the polishing support forms an ellipse, which causes the stone to "rise" on the first half of the roller, then "descend" on the second half of the roller, with a tilting of its inclination at the top, which allows to produce a regular and symmetrical profile.

[0150] - In a scouring process, the shape of the groove is preferably V-shaped instead of U-shaped or rectangular, to facilitate the skewing and tilting of the stone. - From the point of view of the sequence of steps, the scouring is carried out after the machining of the hollow, because this makes it possible to obtain a scour that is directly centered relative to the opening ends of the hole, and it is easier to tilt the stone in the groove with a shorter hole. For the polishing process according to the invention, on the contrary, it is easier to keep the stone straight in the groove with a longer hole. The step of polishing the hole is therefore preferably carried out before any machining of the hollow and before any polishing of the upper and lower faces. The hollowing and polishing steps are therefore preferably reversed with the polishing process according to the invention compared to a scouring process.

[0151] As a result of what has been described above, the method for producing a pivot stone 1 for a watch movement 100 comprises a first polishing step in which:

[0152] (i) free abrasive particles 21 are used rolling between the surface 6 of the pivot hole 5 to be polished and the polishing support 20, and / or

[0153] (ii) the pivoting stone 1 is driven in a rotary movement along the axis A1 relative to the polishing support 20 which is returned towards the surface 6 of the pivoting hole 5 to be polished. This return allows a direct or indirect contact action (via the abrasive particles) of the polishing support 20 against the surface 6.

[0154] Neglecting the speed of advance of the stone in translation along the axis A1 relative to the polishing support, we consider the movement of the stone relative to the polishing support as a rotary movement around the axis A1.

[0155] As seen previously, during the first polishing step, the pivoting stone 1 is held in position relative to the polishing support 20 by contact of the peripheral face 7 of the pivoting stone 1 with the bottom of the groove 32. Preferably, the face 7 extends parallel or substantially parallel to the first axis A1.

[0156] Preferably, as a result of the solutions described 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 in the stone is less than 0.5°.

[0157] Preferably again, as a result of the solutions described above, during the first polishing step:

[0158] - the pivoting stone 1 is driven in a right rotary or helical movement along the axis A1 relative to the polishing support 20, and / or

[0159] - a helical movement is produced with a helix angle less than 0.5°, and / or

[0160] - the angle between the axis A1 and the axis of the polishing support A3 is less than 0.5°, and / or

[0161] - the angle between axis A1 (or axis A3) and axis A2 is equal to the helix angle of groove 32.

[0162] An embodiment of a polishing machine for implementing the polishing method according to the invention is described below with reference to Figures 3 and 4. Preferably, the polishing machine allows the polishing method to be implemented industrially on large batches of stones (several thousand, or even tens of thousands of pieces), in a reproducible and repeatable manner. Preferably, the machine allows the simultaneous polishing of several stones.

[0163] The main elements of one embodiment of the polishing machine are shown schematically in Figures 3 and 4. The polishing machine mainly comprises:

[0164] - the roller 31 or drum 31, - the polishing support 20, and

[0165] - a 39 frame.

[0166] The polishing machine further includes:

[0167] - an actuator 40 comprising a motor and enabling the roller to be rotated relative to the frame 39 around the axis A2,

[0168] - a module 38 for supplying or depositing abrasive on the polishing support 20 making it possible to supply the contact between the polishing support 20 and the hole 5 of the stones with polishing product,

[0169] - a distribution module 37 allowing stones to be sequentially brought onto the roller,

[0170] - a module 36 for adjusting the tension F of the polishing support 20, and

[0171] - a module 35 for adjusting the angle a between the axes A2 and A3, and

[0172] - 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.

[0173] Thanks to the tension adjustment module 36, the polishing support can be maintained at the correct tension in order to ensure that the pressing force of the stones on the roller is constant. The tension adjustment module 36 can be achieved simply and effectively by an adjustable weight fixed at the end of the polishing support and therefore exerting a calibrated traction on the polishing support.

[0174] It is also advantageous for the different stones being processed to be distributed equidistantly on the roller, with a given spacing, to ensure a constant and comparable force for each stone. To do this, the distribution module 37 may for example comprise clamps 33 making it possible to ensure such a uniform distribution.

[0175] For example, the dimensions of the roll can be:

[0176] - an external diameter greater than 10 cm or around 25 cm, and - a length of around 28 cm, these dimensions being to be adjusted and / or optimized according to the characteristics of the stones.

[0177] The module 35 for adjusting the angle a between axes A2 and A3 allows very fine adjustment of the angle to ensure perpendicularity between:

[0178] - the axis of the polishing support, and therefore the axis of the holes in the stones, and

[0179] - the orientation of the groove at the location of the stone being treated. In a variant, the adjustment module 35 therefore makes it possible to ensure, through the adjustment of the angle a, the perpendicularity between the axis A3 of the polishing support and the tangent to the helix of the groove. In another variant, the adjustment module 35 makes it possible to ensure, through the adjustment of the angle a, the perpendicularity between the axis A3 of the polishing support and the osculating plane of the helix of the groove at the level of the contact between the pivot stone and the groove 32. Concretely, the adjustment module 35 comprises a plate which carries the roller 31 and the actuator 40 and which is adjustable relative to the frame 39 which carries the polishing support 20. The adjustment module 35 further comprises a rolling coupling which allows an adjustment of the angle a with an accuracy of the order of 1 / 100°, or even <1 / 100°.This adjustment is achieved, for example, using a mechanical sliding system which is also part of the adjustment module 35.

[0180] The setting of the angle a is initially carried out to the theoretical value, namely to the theoretical value of the helix angle, and then setting stones are made. The angle is then adjusted if the pivot hole of the made stones is not cylindrical, and / or if a variation in diameter is detected along the pivot holes of the made stones, and / or if the presence of a deflection is detected (for example a deflection greater than 0.5 pm) along the pivot holes of the made stones, and / or if a significant portion of the surface of the pivot hole of the made stones is not modified (polished) by the process. The aim is to remove the areas and traces of the drilling or enlarging operation along the entire length of the pivot hole.When the axis A1 of the hole of the stone is parallel to the polishing support, the entire surface 6 of the hole, from the lower face 4 to the upper face 2 of the stone, is polished uniformly or substantially polished uniformly.

[0181] When adjusting the polishing backing to the roller, it is important that the polishing backing is in contact with the hole in the stones. Precise adjustment of the position of the polishing backing, especially the angle of the polishing backing axis to the roller surface, is not necessary, as it is guided by the stones and held in position by the tension applied to the polishing backing. The depth of the groove should not be too great to keep the polishing backing away from the roller, but sufficient to ensure good guidance of the stone and avoid vibrations. The important thing is that the stone is held firmly against the bottom of the groove, with the force exerted by the polishing backing also allowing uniform polishing.

[0182] For example, the roller speed is between 800 and 1500 rpm and is typically 1200 rpm. With a roller diameter of around 25 cm and a stone diameter of typically 1 mm, this results in a very high rotation speed of the stone, of around 300,000 rpm or 5,000 rpm (assuming that the stone does not slide on the roller). The rotation speed is therefore much higher than the feed speed of the stone 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 orthoradial direction relative to the A1 axis, compared to 9.2 mm / s in the axial direction relative to the A1 axis, i.e. more than 300 times higher. The angle of the polishing grooves relative to the plane perpendicular to the A1 axis is in this case of the order of 0.2°, which is negligible.The speed of the pivot stone 1 at the contact with the polishing support 20 and in the orthoradial direction relative to the axis A1 relative to the polishing support 20 may be between 1 m / s and 20 m / s, in particular between 1 m / s and 10 m / s.

[0183] Another advantageous element for the repeatability of the polishing process according to the invention is to ensure good separation of the stones on the roller, by preventing the stones from sticking to each other during processing, with constant spacing from one stone to another. This makes it possible to guarantee an equal pressing force from one stone to another and along the roller. One solution for ensuring good distribution is the use, in the distribution module 37, of precision gripping means, in particular clamps, which take and then release exactly one stone at a time and at identical intervals on the polishing support and the roller. The polishing support advances at very low speed along the axis A1 relative to the roller to advance the stones to the distribution module. The advance speed is typically of the order of one stone thickness per distribution period.If the module is set to dispense one stone every 6 seconds onto the roller, and the thickness of the stone is 0.315 mm, the resulting feed rate of the polishing medium is typically of the order of 0.2 m / h. The feed movement is not useful for the structure of the pivot stone obtained by the production method. This movement is only necessary to obtain progression of the pivot stone outside the roller 31 in the described embodiment of the production method.

[0184] A reliable distribution module, which ensures the correct feed of the polishing media and the correct distribution of the stones, is an advantageous element so that each stone has the required surface finish in the pivot hole. The implementation of the process must be robust and repeatable because the control of the surface finish is destructive in its current state and is therefore difficult or impossible to carry out routinely on the stones or on a sample of stones during the stone manufacturing process.

[0185] Of course, to ensure the smooth running of the process, it is possible to add cameras (to control for example the height of the polishing support, the position of the clamps and / or the correct distribution of the stones on the roller), control screens, measurement means and results, parameter monitoring, a human-machine interface, etc.

[0186] When implementing the polishing process for a new stone geometry, adjustment and optimization steps may be carried out. There is generally an interaction and a reciprocal influence to be optimized between the roller speed, the tension of the polishing support (and therefore the applied force), the hole diameter, and the size of the abrasive.

[0187] More generally, a machine 30 for polishing pivot holes 5 of pivot stones 1 for watch movement 100 according to the invention, comprises the drum 31 driven in rotation around the axis A2 and having the groove 32 which forms a helix on the drum 31, the groove 32 ensuring both

[0188] - the drive of the pivot stones, and

[0189] - maintaining the pivot stones in a position such that the axis A1 is perpendicular to the osculating plane of the helix at the pivot stone-groove contact.

[0190] The polishing process, one embodiment of which has been described above, makes it possible on the one hand to orient the polishing lines or grooves of the surface of the pivot hole orthoradially relative to the axis A1 of the pivot hole 5. This orientation is much more favorable because it coincides with the orientation of the movement of the component, in particular of the pivot, guided in the stone, relative to the stone, and thus avoids a "file" effect which causes faster wear of the pivot. On the other hand, the polishing process, one embodiment of which has been described above, makes it possible to obtain low roughnesses in a repeatable manner, with values ​​which can be less than 5 nm for optimized conditions. Since the orientation of the lines is orthoradial relative to the axis A1, a measurement of the roughness in the orthoradial direction is not relevant, and the given values ​​are measured in the axial direction.

[0191] The method described above may also be applied to pivot stones made by other methods or process steps, such as for example stones made by pressing, and / or with hollowing made by laser machining, and / or with other elements such as a clearance zone as described in document WO2021032552A1. The method above may also be applied to other watch components comprising a hole, in particular a cylindrical hole, such as a tube, such as for example a ceramic tube or a metal tube, or a watch component such as a cannon-pinion.

[0192] More generally to what has been described previously, a method for producing a watch component 1 may comprise a step of polishing or machining the hole 5 by abrasion using free abrasive particles 21 relative to the machining support 20 rolling 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 released from the machining support, the component being driven in a rotary movement along the axis of the hole relative to the polishing or machining support.

[0193] As a result of implementing the method described above and / or using the machine described above, it is possible to produce a pivoting stone 1 for a watch movement 100, comprising a pivoting hole 5, in particular a cylindrical pivoting hole, having a first axis A1 and capable of pivoting a watch component or capable of pivoting around a watch component. The pivoting hole comprises a surface 6 having main abrasion machining grooves 61, in particular main polishing grooves, oriented substantially orthoradially relative to the first axis A1.

[0194] The orientation of a groove is the orientation of its length or largest dimension, and can be determined by inspection on an image, or even by using surface texture determination procedures as described below. With the machining process described, neither the number of machining grooves, nor their geometry, nor their location are controlled, but the process results in a preferred orientation which is substantially orthoradial relative to the axis A1 of the hole.

[0195] The main machining and / or polishing grooves 61 advantageously have an average helix angle of less than 1° or less than 0.5° or, more generally, are such that:

[0196] - the osculating plane at any main streak at any point of this main streak, and

[0197] - a plane perpendicular to the axis A1, are parallel or form between them an angle less than 1° or less than 0.5°.

[0198] In other words, preferably, the main machining and / or polishing grooves 61 are parallel or substantially parallel to the plane perpendicular to the axis A1. In other words, the main machining and / or polishing grooves 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.

[0199] 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 striations 61, is less than 20 nm or less than 10 nm.

[0200] As a result of implementing the method described above and / or using the machine described above, the profile of the surface 6 of the pivot hole 5, along a plane passing through the axis A1, can be:

[0201] - right, or

[0202] - convex seen from the A1 axis with an arrow less than 1 pm or less than 0.25 pm.

[0203] According to a first use, as illustrated in figure 5, the pivot stone 1 is intended to:

[0204] - be driven into a frame 99 of a watch movement 100, and

[0205] - receive, in the pivot hole 5, a component 98 such as a watch axis.

[0206] The watch component can be in particular:

[0207] - a pendulum, or

[0208] - an anchor, or

[0209] - an escape wheel, or

[0210] - a wheel of a finishing gear, such as a center wheel or a large average or a small average or a seconds wheel, or

[0211] - a mobile from an automaton chain.

[0212] According to a second use, as illustrated in Figure 6, the pivot stone 1 is intended to:

[0213] - be driven into a watch component 98 such as a watch axis, and

[0214] - receive, in the pivot hole 5, a tenon of a frame 99 of a watch movement 100 or of another watch component. The watch component 98 or the other watch component may in particular be a wheel of a finishing train, such as a center wheel, a large middle wheel or a small middle wheel or a seconds wheel. In the first and second uses, preferably, two pivot stones may be used to guide the watch component relative to the frame 99 or relative to another watch component.

[0215] According to a third use, the pivoting stone 1 is intended to receive, in the pivoting hole 5, a tenon of a watch component 98, such as a rocker. In this use the pivoting stone is used as a roller and its external surface 7 is intended to roll on another watch component. The external surface 7 is in this case intended to come:

[0216] - rolling in a groove of a drum during the manufacture of stone, and

[0217] - rolling on a watch component during its use, after its manufacture. The external surface 7 may not be cylindrical. It may, for example, be generally frustoconical. Furthermore, it may have, in a plane perpendicular to the axis A1, a convex, or concave, or complex profile such as, for example, a cam profile.

[0218] More generally, the invention also relates to a watch component comprising a hole, in particular a cylindrical hole, such as a tube, for example a ceramic tube or a metal tube, or a watch component such as a cannon pinion, the pivot hole comprising a surface having main abrasion machining grooves, in particular main polishing grooves, oriented substantially orthoradially relative to the axis of the hole.

[0219] The invention also relates to a watch movement 100 comprising at least one pivoting stone as mentioned above, in particular at least two pivoting stones as mentioned above and / or comprising a watch component 98 comprising a pivoting stone 1 as mentioned above, and / or comprising a component as mentioned above. The invention also relates to a timepiece 200, in particular a wristwatch, comprising:

[0220] - at least one pivot stone 1 as mentioned above, and / or

[0221] - a watch component as mentioned above, and / or

[0222] - a 100 watch movement as mentioned above.

[0223] Measuring the condition of the internal surface 6 of the pivot hole 5 poses a double challenge:

[0224] - succeed in accessing surface 6, the condition of which must be measured, which is very difficult given the geometry of the hole, and then

[0225] - measure the roughness itself.

[0226] We will see below how, in a first phase, to prepare a stone to then allow, in a second phase, the measurement of the state of the friction surface 6.

[0227] For roughness measurement, confocal laser scanning microscopy appears to be particularly useful. It appears to be suitable for concave surfaces. Confocal laser scanning microscopy allows for precise measurement of surface roughness even at low magnification, in compliance with ISO 25178 (surface roughness) and ISO 4287 (linear roughness) standards.

[0228] In this application, it is preferable to take a linear roughness measurement and not a surface roughness measurement given the preferred orientation of the roughness. Indeed, the surface roughness measurement takes an average over the surface and is relevant when the surface condition is uniform and non-directional, but is less suitable in the present application case where the notion of roughness orientation is present. It is therefore appropriate to consider the linear roughness Ra, i.e. the arithmetic mean deviation of the evaluated profile.

[0229] The preferred orientation of roughness can be quantified by considering the parameters Str and Std. The parameter Str, sometimes referred to as "isotropy", is a measure of the uniformity of the surface texture and takes a value between 0 and 1 without units, depending on the definition of the standard. If the surface has the same characteristics in all directions (isotropic surface), the value of Str will be close to 1, whereas a highly anisotropic or textured surface will have a value of Str close to 0.

[0230] If the surface is anisotropic (Str value close to 0), it is interesting to determine the preferential direction of the texture, expressed by the Std parameter. A useful tool for this purpose is the polar spectrum, i.e. the Fourier spectrum integrated in polar coordinates. The angle corresponding to the most powerful spectrum corresponds to the main texture direction, and the main direction of the spectrum gives the Std parameter, which is the trigonometric angle of this main direction from a reference axis of the image. It is therefore important to always orient the images in the same way relative to this reference axis. In addition, it is preferable to carry out these measurements by excluding the edges of the image or the component, to straighten the surface to remove shape effects and to have, if possible, an adapted acquisition step and a square image size.

[0231] This preferential orientation of the roughness, quantified by the parameters Str and Std, and in particular the preferential direction of the texture expressed by the parameter Std which is the trigonometric angle of this principal direction from a reference axis of the image, corresponds to the orientation of the principal striations which determine the roughness of the surface. In other words, it is considered for example that the principal striations are oriented substantially orthoradially relative to the first axis A1 if the trigonometric angle of the preferential direction of the texture as expressed by the parameter Std is substantially a right angle relative to the first axis A1.

[0232] For roughness measurement, an instrument with a confocal diaphragm optical system, such as the VKX-1 100 instrument from Keyence, can be used as an example. The key parameters are the resolution in the vertical direction and the lateral resolution, and a 50x objective with an aperture of 0.95 used on the aforementioned instrument allows achieving optimal optical resolution with a sufficient working distance to measure the area of ​​interest of stones prepared according to the method described below. The measurement is taken in the central area of ​​the stone. The segment length is chosen according to the ISO 4287 standard, and, for example, 30 different segments are measured successively, each segment being divided into five sub-segments according to the standard to minimize the effect of the profile shape.

[0233] The measuring segments are oriented perpendicular to the residual polishing streaks 61, and / or perpendicular to the preferred direction of the texture expressed by the parameter Std, so as to obtain a characteristic measurement of the roughness. In other words, the measuring segments are oriented in the orthoradial direction when the residual machining or polishing streaks are oriented in the axial direction (such as for example after magnifying), and the measuring segments are oriented in the axial direction when the residual machining or polishing streaks 61 are oriented in the orthoradial direction (such as for example after the polishing method according to the invention described above).

[0234] The roughness values ​​obtained can of course vary depending on the equipment and measurement technique used. The values ​​indicated in this document were all acquired on a confocal laser scanning microscope, at a magnification of 50x, by measuring 30 segments and calculating the roughness Ra. To perform a measurement, for example, half a stone from the preparation described below can be placed in a vice, then focused in the measurement area, for example successively with the different objectives until a sharp image is obtained at 50x magnification. An image resolution of 2048x1536 pixels can be used with a segment pitch of 0.10 pm. The segment length can be 65 pm with 30 lines spaced 2 pm apart. Roughness is measured in the direction perpendicular to the residual machining or polishing striations.According to the standard, the measurement of roughness Ra is valid if and only if the ratio between the standard deviation and the obtained Ra value is strictly less than 0.2.

[0235] According to a test carried out on several batches of large stones obtained with different processes, it was found, with a standard magnifying process, that the residual polishing striations are oriented in the axial direction, and the measuring lines are oriented accordingly in the orthoradial direction. The measured roughness is 25.5 ± 5.0 nm.

[0236] With the polishing method according to the invention, the residual polishing striations are oriented in the orthoradial direction, the measuring lines are oriented in the axial direction and the measured roughness is 4.0 ± 1.6 nm.

[0237] The surface texture is pronounced in both cases, with a comparable Str (isotropy) value close to 0. The isotropy (Str) is however always strictly greater than 0, in particular greater than 1%. It is of the order of 20% for the standard magnifying process, compared to less than 10%, or even less than 3%, for the process according to the invention. In particular, the process according to the invention makes it possible to obtain a roughness Ra of less than 5nm with a preferential orientation of the texture of 90° + / - 0.5° relative to a direction parallel to the hole axis and an isotropy greater than 1% and less than 10%, in particular less than 3%. The difference is especially evident on the polar spectrum and the Std value, with a preferential direction of the texture of Std = 7° and 90.1° for a standard magnifying process and for the polishing process according to the invention, respectively.

[0238] The measurement method described above can be used for any type of stone, and also for olived stones. As mentioned before, the purpose of olived is to obtain a rounded pivot hole profile, not a straight pivot hole profile. The edges of the hole are softened and a deflection (difference in diameter between the center and the edges of the hole) is measurable, of at least 3 pm, more typically at least 5 pm. This deflection value is not specified on the drawings, because no possibility to measure this characteristic was available until now, and the presence of olived is usually noted only by visual inspection, by the oval shape of the reflection in the hole. The deflection value will also depend on the diameter and length of the hole. On the contrary, when performing typical profile measurements for a stone according to the present invention, the edges of the hole are well defined, and the deflection of the hole profile is 0.175 pm. On a measured batch of 40 stones, the measured deflection was between 0.1 and 0.2 pm, over the 150 pm distance from the chimney of the hole. On the finished stone, the deflection may be even less because the length of the hole may be reduced by possible digging.

[0239] The measuring method described above can also be applied to other watch components comprising a hole, such as a tube, for example a ceramic tube or a metal tube, or a watch component such as a cannon pinion.

[0240] The geometry of the stones makes the quantitative measurement of the surface condition 6 of the pivot hole 5 very delicate. This surface is only directly visible by tilting the stone sharply, and a measurement on an inclined and / or confined surface is difficult.

[0241] Accordingly, a method of carrying out a preparation phase of a pivot stone 1 comprises an ablation of a first part of the pivot stone 1 including a part of the surface 6 of the pivot hole 5, as well as a part of the external surface 7 and a part of the volume between the surface 6 of the pivot hole and the external surface 7, in order to obtain a second part of the pivot stone 1. This phase of preparing a stone makes it possible to obtain, in a rapid and reproducible manner, a measurable element with direct and unobstructed access to an area of ​​the surface 6 to be measured. The representation of FIG. 1 can constitute a good image of the second part of stone obtained by the preparation method. Indeed, the ablation of the first part of the pivot stone can be carried out along the plane passing through the axis A1 of the pivot hole 5 or along a plane parallel to the axis A1 of the pivot hole 5.The aim is to allow direct access to the entirety of a profile of the surface of the pivot hole in the axial direction, in particular access with a light or laser beam perpendicular or substantially perpendicular to said profile.

[0242] To gain access to the pivot hole of a stone, one might think that it is sufficient to apply a blow with a tool to the stone to break it and produce chips with a portion of the pivot hole surface intact. However, such a method is very random, is not reproducible and is not suitable for routine inspection.

[0243] One method involves removing material from a portion of the stone, particularly by abrasion. This method is particularly useful when a certain quantity of stones from the same source must be inspected, for example, a sample inspection of 20 pieces from a batch of 1,000 pieces. The quality of the abraded portion is not important because it is not measured. However, it is important to ensure that the cutting process does not alter the samples at the hole. A grinding process is, for example, suitable for quickly preparing the pieces by cutting.To position the stones at the same level and protect the pivot hole, especially to avoid the presence of embedding resin in the hole if such resin is used, it is favorable to thread the stones on a wire with a diameter very slightly smaller (for example 10 μm smaller) than the diameter of the hole, preferably a nylon or other polymer threading wire. It is also possible to use a wire that leaves a clearance greater than 10 μm and to melt the ends to seal the hole of the stones at the ends, which ensures the absence of pollution in the hole. It is also possible to use a metal wire, for example brass, especially for small diameter wires, for example for diameters less than 0.2 mm. With a metal wire, it is important that the wire is well adjusted in relation to the diameter of the hole to prevent the embedding resin from entering the hole and making subsequent measurement impossible.

[0244] Once the coating is completed, it is easy to grind the stones, for example until there is a height difference of the order of the radius of the hole, for example 0.2 mm, between the bottom of the hole and the cutting face or the abraded face to have easy access to the area to be measured for the measuring instrument. The wire can remain in place throughout the grinding step and be removed only just before cleaning and measurement. The stones can be aligned, with surfaces to be measured at comparable heights, in a configuration that lends itself well to automated measurement. Series of several tens, or even a few hundred stones, can thus be measured automatically. Thus, a sub-step of assembling several pivot stones 1 can be implemented before ablation.

[0245] A second method is particularly suitable for the preparation of individual stones, for example unique stones, especially stones dismantled from a movement blank. This second method consists of performing ablation by breaking.

[0246] The procedure allows for simple and repeatable cutting of the stone to access the inner walls of watch jewels, particularly synthetic rubies, for roughness measurement. The principle is to incise the stone on one of the upper or lower faces (for example, on an unhollowed face) with a diamond tool, such as a diamond chisel or a diamond point, in order to create an incipient fracture and then break the stone with a small shock.

[0247] First, the stones are checked for proper cleanliness before cutting, for example by optical microscopy. The stones are dusted and cleaned if necessary, for example by washing in an aqueous phase or solvent. The flat face of the stone is first placed on the operator side and is scored with a diamond tool. The scored stone is then positioned to apply a small shock, for example with a hard metal riveting point placed on a bracket. A light blow, for example applied with a watchmaker's hammer on the stem of the bracket, allows the stone to break according to the initial fracture. For this step, the stones can be held on a stand or a vice or any other support or means suitable for holding them in place.

[0248] The two half-stones are then recovered, possibly cleaned to remove any residue or particles, and then measured. Note that this method of incision and impact breaking produces far fewer particles and debris than traditional wire cutting. This second method is also repeatable and does not depend on the dexterity of the person implementing it.

[0249] Alternatively, the stone or batch of stones could also be cut with a saw or wire. This third method is, however, less favorable given the risk of chips caused by cutting on areas close to the surface to be measured.

[0250] Thus, in general, a method makes it possible to determine the roughness of the surface 6 of the pivot hole 5 of the pivot stone 1. This method comprises:

[0251] - a first step of preparing the pivot stone 1 comprising an ablation of a first part of the pivot stone 1 including a part of the surface 6 of the pivot hole 5 in order to obtain a second part of the pivot stone 1, then

[0252] - a second measuring step on the surface 6 of the pivot hole 5 located on the second part of the pivot stone 1.

[0253] Logically, the preparation of the stone, and in particular the removal of a first part of the pivot stone, does not modify the pivot surface located on the second part of the pivot stone, so that the roughness measurement obtained is indeed representative of the surface condition of the pivot hole obtained following the production, in particular following the machining and polishing, of the watch component.

[0254] The preparation method described above can be used for any type of stone, and also for olive-colored stones. The preparation method can also be applied to other watch components comprising a hole, such as a tube, such as for example a ceramic tube or a metal tube, or a watch component such as a cannon-pinion. The invention also relates to the washing of a watch component. Thus, a method of carrying out a step of washing the watch component 1 and the machining support 20 while the machining support is housed in the hole of the watch component 1 is described below in detail.

[0255] This washing step is advantageously implemented in the method for producing the pivot stone described above and comprising a step of polishing the pivot hole.

[0256] However, more generally, a washing step can be implemented in any method for producing a watch component comprising a hole, the method comprising:

[0257] - a step of machining the hole by abrasion using abrasive particles free relative to a machining support, in particular diamond particles, rolling between the surface of the hole to be machined and the machining support housed in the hole, and / or using abrasive particles capable of being released from the machining support.

[0258] Consequently, the washing step can also be applied to a process for producing an olive-plated stone after the olive-plating machining step.

[0259] In these processes, once the passage of a stone 1 over the roller 31 is complete, abrasive remains on the machining support and on the stone. Investigations carried out using the preparation and measurement process have shown that this presence of residual abrasive frequently poses a problem during unthreading, i.e. when the stones are removed from the machining support.

[0260] Indeed, abrasive particles can get stuck in the pivot hole and cause axial streaks when unthreading or when extracting the component from the machining support. These lines or streaks deteriorate the surface condition of the hole, causing significant roughness oriented in the axial direction and / or possibly breaking the regularity of the rounding of the olive, which is not desired.

[0261] When the washing step is not carried out, the presence of lines in the axial direction is often observed. These lines can be of low density and shallow depth, but can also be very pronounced. The roughness is in all cases degraded and the effect of the olive-polishing on the surface condition is partially, or even totally, eliminated. In this case, it is indeed a degradation that occurred after the olive-polishing, and not a residue of the enlarging process, because the hole has indeed been brought to its final dimension by the olive-polishing with a significant removal of material and much greater than the depth of the residual striations from the enlarging. In addition, the lines observed are superimposed on the characteristic profile of the olive-polishing, with a symmetrical shape and a deflection of typically a few pm or more.

[0262] The addition of the step of washing the machining support and the stones to remove the abrasive before unthreading makes it possible not to damage the polished or machined surface. This washing or cleaning can be carried out in different ways, for example in an aqueous or solvent medium, with or without detergent, with or without ultrasound, or by blowing water vapor, or by cleaning with water or a solvent. This cleaning can be carried out directly on the equipment to clean the stones directly at the outlet of the roller 31, or outside the equipment once the machining support has been dismantled. Preferably, the washing is carried out using a flow of fluid to carry away the abrasive particles used during machining or polishing. The fluid can be a washing solution, in particular an aqueous solution or an alcoholic solution or an oily solution.

[0263] Additionally or alternatively, the washing step may comprise soaking the watch component 1 and the machining support 20 in a washing solution. The soaking may comprise the emission of ultrasound into the washing solution.

[0264] Additionally or alternatively, the washing step may include spraying the watch component 1 and the machining support 20 with a washing solution.

[0265] In addition or as an alternative, the washing step may include the blowing of a gas or water vapor.

[0266] A washing system 84 can be placed just after the roller. Thus, the washing step can be carried out directly on the machining machine, in particular on the polishing machine that made it possible to carry out the step of machining the hole by abrasion. The washing system 84 can be part of the machining machine 30. This washing system makes it possible to wash or clean the stones and the machining support immediately after polishing or olive-polishing or any other machining. The washing system advantageously comprises nozzles 83 and / or channels for projecting a washing fluid, such as a washing solution. Preferably, these nozzles and / or these channels are arranged so as to produce jets directed both in the direction of advance and in the opposite direction to the advance of the stone on the machining support, cleaning the stone first on both sides, then in the direction of advance at the end of the washing system for its exit from the washing system.The washing system is advantageously designed so as to form a housing 80 in two parts 81, 82 so as to be able to be partially opened, for example to place a new machining support or adjust the position of the washing system relative to the machining support and the rest of the machine. Thus, the washing system 84 can take the form of a housing 80 as shown in FIG. 7. This housing 80 can be crossed right through by the assembly constituted by the watch component 1 and the machining support 20. The housing 80 therefore has a passage for the machining support. Alternatively, the washing step can be carried out after removal of the assembly constituted by:.

[0267] - the watch component 1, and

[0268] - the machining support 20 of the machining machine having made it possible to carry out the step of machining the hole by abrasion. In such a hypothesis, the assembly consisting of the watch component 1 and the machining support 20 is dismantled from the machining machine, then the assembly consisting of the watch component 1 and the machining support 20 is washed, then the watch component 1 is dismantled or separated from the machining support 20, in particular the machining support 20 is removed from the hole of the watch component 1.

[0269] More generally than what has been described previously, a method for producing a watch component 1 may comprise:

[0270] - a step of machining the hole 5 by abrasion using free abrasive particles 21 relative to the machining support 20 rolling 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 released from the machining support, then

[0271] - a step of washing the watch component 1 and the machining support 20 while the machining support is housed in the hole, then

[0272] - a step of removing the machining support from the hole.

Claims

Claims Method for producing a watch component (1), in particular a pivot stone (1), comprising a hole (5), the method comprising: - a step of machining the hole (5) by abrasion using free abrasive particles (21) relative to a machining support (20), in particular diamond particles, rolling 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 released from the machining support, then - a step of washing the watch component (1) and the machining support (20) while the machining support is housed in the hole, then - a step of removing the machining support from the hole. Production method according to the preceding claim, characterized in that the washing step comprises using a washing solution, in particular an aqueous solution or an alcoholic solution or an oily solution. Production method according to the preceding claim, characterized in that the washing step comprises soaking the watch component (1) and the machining support (20) in the washing solution. Production method according to the preceding claim, characterized in that the soaking comprises the emission of ultrasound into the washing solution. Production method according to one of the preceding claims, characterized in that the washing step comprises spraying the watch component (1) and the machining support (20) with a washing solution. Production method according to one of the preceding claims, characterized in that the washing step comprises blowing a gas or water vapor. Production method according to one of the preceding claims, characterized in that the washing step is carried out on a machining machine, in particular on a polishing machine which has made it possible to carry out the step of machining the hole by abrasion. Production method according to one of claims 1 to 6, characterized in that the washing step is carried out after removal of the assembly consisting of: - the watch component (1), and - the machining support (20) of a machining machine having made it possible to carry out the step of machining the hole by abrasion. Production method according to one of the preceding claims, characterized in that the washing step is implemented in a housing (80) crossed right through by the assembly constituted by the watch component (1) and the machining support (20). Washing system (84) comprising material means (80, 81, 82, 83) for implementing the step of washing a watch component (1) while a machining support is housed in a hole of a watch component (1) according to the method according to one of the preceding claims, in particular: - a housing (80), for example generally formed by two parts (81, 82) movable relative to each other and / or having a passage for the machining support, and - nozzles 83 and / or washing solution projection channels. 1 1. Machining machine (30) comprising material means (20, 31, 34, 35, 36, 37, 38, 39, 40, 84) for implementing the method according to one of claims 1 to 9, in particular comprising a washing system (84) according to the preceding claim.

12. Watch component (1), in particular pivot stone (1), obtained by implementing the method according to one of claims 1 to 9.

13. Watch movement (100) comprising a watch component (1) according to the preceding claim.

14. Timepiece (200) comprising a watch component according to claim 12 and / or a watch movement (100) according to the preceding claim.

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