Timepiece shaft

Abstract

The invention relates to a timepiece shaft (1), in particular a shaft of a balance wheel (2) or of an escape wheel or of an anchor, comprising:-a first axis of rotation (A1); and at least one pivot (12), the timepiece shaft (1) having a curved surface of revolution around the first axis of rotation (A1), the generatrix (G) of which is curved in a plane (P) passing through the first axis of rotation (A1), the curved surface of revolution extending at least at the pivot, the pivot being defined as a region of the timepiece shaft (1) intended to come into contact with a pivot bearing (50), in particular a pivot gem (50).

Description

Technical Field

[0001] The present invention relates to a clock shaft. The present invention also relates to an element intended to be mounted on a clock shaft. The present invention also relates to an assembly comprising such a shaft and / or such an element. The present invention also relates to a combination comprising such a shaft or such an element or such an assembly. The present invention also relates to a clock movement comprising such a shaft or such an element or such an assembly or such a combination. The present invention finally relates to a clock comprising such a shaft or such an element or such an assembly or such a combination or such a clock movement. Background Art

[0002] A great deal of work and many patent applications have aimed to determine the material and / or geometry of the shafts of movements, these shafts being both paramagnetic and resistant to mechanical loads during wear. This research particularly concerns the balance staffs subjected to particularly heavy loads. Historically, clock shafts have been made of ferromagnetic carbon steel. From a mechanical point of view, the paramagnetic alloys tested so far have clearly provided poorer performance. Thus, the mechanical strength of clock shafts remains a problem.

[0003] Document WO2021032552A1 describes a specific hole geometry of a pivot jewel. The pivot is Figure 2 schematically shown as having a frustoconical geometry, but without further elaboration.

[0004] Document CH702314 describes a specific pivot geometry having a tapered pivot that mates with a counter-pivot jewel surface in the form of a chamfered cone.

[0005] Document CH704770 describes different geometries of the end of a pivot that mates with a counter-pivot jewel. In the vertical position of the movement, a portion of the cylindrical surface of the pivot contacts the inner surface of the bearing. In the horizontal position of the movement, the end of the pivot bears against the counter-pivot jewel. Document CH704770 pays particular attention to the geometry of the end, proposing to offset the support point of the clock shaft on the counter-pivot jewel from the pivot axis.

[0006] Document EP3258325 discloses a ceramic balance staff. The pivot rod and the pivot can be the same or not delimited by a clear boundary such as a bearing surface. The pivot rod and the pivot can be separated, for example, by a frustoconical surface or a surface with a curved generatrix. The shaft has a standard geometry at the level of its middle part, which has a receiving part (cylindrical part) for the plate, a receiving part for the balance with a receiving seat and a cylindrical part forming a stop, and a receiving part for a collet (not shown).

[0007] Standard NIHS - 34 - 01 describes the standard balance staff geometry. The staff includes a plurality of parts, in particular a cylindrical part, a bearing surface forming a stop perpendicular to the axis of symmetry, and a frustoconical part. However, these frustoconical parts are not bearing or stop surfaces, but rather entry chamfer surfaces that facilitate the assembly and / or machining of components mounted on the staff. In particular, the plate and the balance are driven so as to press against a flat or substantially flat surface of the seat. The pivot is described as having a cylindrical shape with a diameter p and extending through a cone or through a surface of revolution evolving into an arc of radius r.

[0008] A. Haag described in "Theoretische und experimentelle Untersuchungen zum Verhalten der Unruhzapfen bei Stoessen auf die Uhr" (Actes du Conrès International de Chronomtrie 1964, p. 1125) the general plane of a balance staff having a flat bearing or stop surface and a conical receiving part forming a drive cone. The use of this type of cone is because it ensures very good centering and facilitates assembly. The drive cone (sometimes called a Morse cone) rests on nested convex and concave elements, and the conical walls of the convex and concave elements usually have a cone angle of a few degrees and are used to hold parts together in fields such as the machine tool industry and dental applications.

[0009] Document CH327357 describes a geometry of a staff designed to facilitate the disassembly of various elements. The staff includes a cylindrical receiving part, optionally having a conical part and / or a shoulder with a small cone angle. Various elements are driven onto the cylindrical part using corresponding holes.

[0010] Document CH715867 describes a geometry of a staff including a plurality of straight frustoconical sections. The purpose of these parts is to facilitate the driving and / or machining of various elements (the inner stud of the hairspring, the balance, the plate) mounted on the staff, but they do not constitute bearing or stop surfaces for the mounted elements. Instead, the inner stud and the plate press against a flat surface forming a shoulder, that is, a flat bearing surface perpendicular to the axis of rotation of the staff.

[0011] Document FR2268291 describes an optimized balance staff geometry for producing a staff by drawing, which has no holding or bearing or stop surfaces for the balance or the plate.

[0012] The clockmaking dictionary (G.-A. Berner) shown indicates that a type of pivot is wrongly called "conical". It would be better called a pivot without a bearing surface. It is formed by a cylindrical part connected to the pivot rod by a rounded corner. It is part of the clock axis whose end presses against the face of the counter-pivot jewel. The bearing surface is eliminated and friction is reduced.

[0013] C. Schlater and H.-A. Lehmann measured the bending resistance of various pivot geometries in "Mesures de la fragilité des pivots d’axes de balancier" (Proceedings of the 46th Congress of the Swiss Horological Society, p. 157, 1971 (actes du 46 e congrès de la Société Suisse de Chronométrie, p. 157, 1971)). A continuous connection between the cylindrical part (pivot) and the conical part is recommended. In addition, for connecting the cylindrical pivot part to the pivot rod, a test using the "circular cone" (rounded corner) geometry is more advantageous than a cone geometry like this. SUMMARY OF THE INVENTION

[0014] The object of the present invention is to provide a clock axis that solves the above problems and can improve the clock axis known in the prior art. In particular, the present invention proposes a clock axis with improved mechanical strength.

[0015] According to a first aspect of the present invention, the object is defined by the following proposal.

[0016] 1. A clock axis 1, in particular the axis of a balance wheel 2 or the axis of an escape wheel or the axis of an escapement fork:

[0017] - having a first axis of rotation A1, and

[0018] - including at least one pivot 12,

[0019] The clock axis 1 has a surface of revolution about the first axis of rotation A1, the generatrix G of which is curved in a plane P passing through the first axis of rotation A1, and the surface of revolution extends at least at the level of the pivot, which is defined as the area of the clock axis 1 intended to come into contact with a pivot bearing 50, in particular a pivot jewel 50.

[0020] 2. The clock axis 1 according to proposal 1, wherein:

[0021] - the radius of curvature of the generatrix G at all points is less than 2 mm, in particular less than 1.8 mm, and / or

[0022] - The diameter of the cross-section of the rotary surface continuously increases in the direction away from the proximal end portion 13 of the timepiece axis 1, and / or

[0023] - The radius of curvature of the generatrix G decreases in the direction away from the proximal end portion 13 of the timepiece axis 1.

[0024] 3. The timepiece axis 1 according to any one of Proposals 1 or 2, wherein the generatrix G has a first portion 121 that is convex when viewed from the first rotation axis A1 at the level of the pivot.

[0025] 4. The timepiece axis 1 according to any one of Proposals 1 or 2, wherein the generatrix G has a first portion 121 that is concave when viewed from the first rotation axis A1 at the level of the pivot.

[0026] 5. The timepiece axis 1 according to Proposal 4, wherein the distance R from the first portion to the first rotation axis A1 increases as a function of the distance d to the proximal end portion 13 of the timepiece axis 1 according to the following law: R = A × (d + B) 1 / 3 , where A and B are constants.

[0027] 6. The timepiece axis 1 according to Proposal 3 or 4, wherein the first portion 121 is a part of a circle having a first radius of curvature R1.

[0028] 7. The timepiece axis 1 according to any one of Proposals 3 to 6, wherein the generatrix G has a second portion 122 that is convex when viewed from the first rotation axis A1, and the first portion and the second portion are continuously connected, in particular continuously connected in tangency and / or continuously connected in curvature.

[0029] 8. The timepiece axis 1 according to Proposal 7, wherein the second portion 122 is a part of a circle having a second radius of curvature R2.

[0030] 9. The timepiece axis 1 according to any one of Proposals 1 to 8, wherein the generatrix G is composed of spline curves or parts of spline curves that are continuously connected, in particular continuously connected in tangency and / or continuously connected in curvature.

[0031] 10. The timepiece axis 1 according to any one of Proposals 1 to 9, wherein the timepiece axis includes a plurality of rotary surfaces, and each of the plurality of rotary surfaces of the timepiece axis 1 around the first rotation axis A1 has a generatrix that has a radius of curvature greater than 40 μm or 50 μm at all points on the generatrix in the plane P passing through the first rotation axis A1.

[0032] 11. The timepiece axis 1 according to any one of Proposals 1 to 10, wherein the timepiece axis 1 is made of the following materials:

[0033] - Technical ceramics, in particular zirconia or alumina, or

[0034] - Glass, especially metallic glass, or

[0035] - Steel, especially carbon steel, or

[0036] - Paramagnetic austenitic steel, or

[0037] - Metallic alloy, or

[0038] - High-entropy alloy, or

[0039] - Composite material, especially a composite material including ceramic fillers in a metallic matrix.

[0040] 12. A component 150, especially an assembled balance wheel 150, which includes a timepiece shaft 1 according to any one of Proposals 1 to 11.

[0041] 13. An assembly 100, which includes:

[0042] - A timepiece shaft 1 according to any one of Proposals 1 to 11 or a component 150 according to Proposal 12, and

[0043] - A pivot bearing 50, especially a pivot jewel 50.

[0044] 14. The assembly 100 according to Scheme 13, wherein the pivot bearing 50 includes a pivot jewel 50, and the pivot jewel 50 includes a hole 51 for pivoting the timepiece shaft 1 along a second rotation axis A2, and the hole includes:

[0045] - A first pivot region 52 in which the timepiece shaft 1 pivots, and

[0046] - A second clearance region 53 extending from a first face 54 of the bearing to the first pivot region 52,

[0047] The face 54 is perpendicular or substantially perpendicular to the second rotation axis A2 and is designed to be oriented on the body side of the timepiece shaft 1, and the first pivot region 52 and the second clearance region 53 are connected to each other by a connecting fillet 55.

[0048] 15. The assembly 100 according to Scheme 14, wherein the maximum diameter of the second clearance region 53 is greater than twice or four times or six times the minimum diameter of the first pivot region 52.

[0049] 16. A timepiece movement 200, which includes a timepiece shaft 1 according to any one of Proposals 1 to 11 and / or a component according to Proposal 12 and / or an assembly according to any one of Proposals 13 to 15.

[0050] 17. A timepiece 300, in particular a wristwatch, comprising a timepiece movement 200 according to Proposal 16 and / or a timepiece shaft 1 according to any one of Proposals 1 to 11 and / or a component according to Proposal 12 and / or an assembly according to any one of Proposals 13 to 15.

[0051] According to a second aspect of the invention, the object is defined by the following proposals.

[0052] 18. A timepiece shaft 1, comprising a first part 24 for driving elements 2; 3; 4 along a drive axis A1, the timepiece shaft 1 having a geometry such that:

[0053] The geometry has a first frustoconical stop portion 21, the first stop portion 21 being adapted to stop elements 2; 3; 4 during their driving onto the timepiece shaft 1, the first stop portion 21 having a half-angle at the apex between 30° and 60° (including the end points), and such that the distance L measured along the drive axis A1 separating the first drive part 24 from the first stop part 21 is at least 0.05 mm, even at least 0.1 mm.

[0054] 19. The timepiece shaft 1 according to Proposal 18, wherein the timepiece shaft is the shaft of the balance wheel 2.

[0055] 20. The timepiece shaft 1 according to any one of Proposals 18 and 19, wherein the first drive part 24 and the first stop part 21 are separated by a separating part 25, the diameter of the separating part 25 being smaller than the diameter of the first drive part 24.

[0056] 21. The timepiece shaft 1 according to Proposal 20, wherein the first drive part 24 and the separating part 25 are connected by one or more rounded corners, and / or the first stop part 21 and the separating part 25 are connected by one or more rounded corners.

[0057] 22. The timepiece shaft 1 according to any one of Proposals 18 to 21, wherein the timepiece shaft 1 is made of the following materials:

[0058] - Technical ceramics, in particular zirconia or alumina, or

[0059] - Glass, in particular metallic glass, or

[0060] - Steel, in particular carbon steel, or

[0061] - Paramagnetic austenitic steel, or

[0062] - Metal alloy, or

[0063] - High-entropy alloy, or

[0064] - Composite material, in particular a composite material comprising ceramic fillers in a metal matrix.

[0065] 23. The clockwork shaft 1 according to any one of Proposals 18 to 22, wherein the clockwork shaft 1 has a geometry that rotates about a drive axis A1.

[0066] 24. The clockwork shaft 1 according to any one of Proposals 18 to 23, wherein the clockwork shaft 1 has a plurality of revolution surfaces about the drive axis A1, and each of the plurality of revolution surfaces has a generatrix that has a radius of curvature greater than 40 μm or 50 μm at all points on the generatrix in a plane P passing through the drive axis A1.

[0067] 25. The clockwork shaft 1 according to any one of Proposals 18 to 24, wherein the clockwork shaft 1 includes at least one pivot 12, preferably two pivots.

[0068] 26. An element 2; 3; 4 which is intended to be driven onto the clockwork shaft 1 along the drive axis A1, the element 2; 3; 4 comprising:

[0069] - A second part 34 adapted to be driven onto the clockwork shaft 1, and

[0070] - A frustoconical second stop part 31 which is adapted to stop the element 2; 3; 4 during the driving of the element 2; 3; 4 onto the clockwork shaft 1, the second stop part having a half-angle between 30° and 60° (including the endpoints) at the apex, and the distance L between the second drive part 34 and the second stop part 31 measured along the drive axis A1 being at least 0.05 mm, even at least 0.1 mm.

[0071] 27. The element 2; 3; 4 according to Proposal 26, wherein the element 2; 3; 4 is a balance wheel 2 or a plate or a double plate 3 or an inner stud 4.

[0072] 28. The element 2; 3; 4 according to Proposal 26 or 27, wherein the element 2; 3; 4 includes a recess 35 between the second drive part 34 and the second stop part 31.

[0073] 29. An assembly 150, in particular an assembled balance wheel 150, which comprises:

[0074] - A clockwork shaft 1, in particular the clockwork shaft 1 according to any one of Proposals 18 to 25, and

[0075] - An element 2; 3; 4 driven onto the clockwork shaft 1, in particular the element 2; 3; 4 according to any one of Proposals 26 to 28.

[0076] 30. A watch movement 200, which comprises:

[0077] - A clockwork shaft 1 according to any one of Proposals 18 to 25, and / or

[0078] - Element 2; 3; 4 according to any one of proposals 26 to 28, and / or

[0079] - Assembly according to proposal 29.

[0080] 31. A timepiece 300, in particular a wristwatch, comprising:

[0081] - A timepiece movement 200 according to proposal 30, and / or

[0082] - A timepiece shaft 1 according to any one of proposals 18 to 25, and / or

[0083] - Element 2; 3; 4 according to any one of proposals 26 to 28, and / or

[0084] - Assembly 150 according to proposal 29.

[0085] According to the third aspect of the present invention, the object is defined by the following proposals.

[0086] 32. An assembly 150, in particular an assembled balance wheel 150, comprising:

[0087] - A timepiece shaft 1, and

[0088] - Elements 2; 3; 4 driven onto the timepiece shaft 1,

[0089] The timepiece shaft 1 has a first drive portion 24 and a first stop portion 21 arranged to stop elements 2; 3; 4 during the driving of elements 2; 3; 4 onto the timepiece shaft 1. Elements 2; 3; 4 have a second drive portion 34 on the timepiece shaft 1 and a second stop portion 31 arranged to stop elements 2; 3; 4 during the driving of elements 2; 3; 4 onto the timepiece shaft 1.

[0090] The first drive portion 24 and the first stop portion 21 are separated by a separating portion 25, the diameter of the separating portion 25 being smaller than the diameter of the first drive portion 24, and / or

[0091] Elements 2; 3; 4 include a recess 35 between the second drive portion 34 and the second stop portion 31.

[0092] 33. The assembly 150 according to proposal 32, characterized in that the first stop portion 21 is frustoconical and has a half-angle, for example, between 30° and 60° (including the endpoints) at the apex, and / or, characterized in that the distance L separating the first drive portion 24 from the first stop portion 21, measured along the drive axis A1, is at least 0.05 mm, or even at least 0.1 mm.

[0093] 34. Assembly 150 according to proposal 32 or 33, characterized in that the clockwork axle is the axle of balance wheel 2.

[0094] 35. Assembly 150 according to any one of proposals 32 to 34, characterized in that the first drive portion 24 and the separation portion 25 are connected by one or more rounded corners, and / or the first stop portion 21 and the separation portion 25 are connected by one or more rounded corners.

[0095] 36. The assembly 150 according to any one of the proposals 32 to 35, characterized in that the clockwork shaft 1 is made of the following material:

[0096] - technical ceramics, in particular zirconium oxide or aluminium oxide, or

[0097] - glass, especially metallic glass, or

[0098] - steel, especially carbon steel, or

[0099] - paramagnetic austenitic steel, or

[0100] - metal alloys, or

[0101] - High entropy alloys, or

[0102] - Composite materials, in particular composite materials comprising ceramic fillers in a metal matrix.

[0103] 37. Assembly 150 according to any one of proposals 32 to 36, characterised in that clockwork axle 1 has a geometry which allows rotation about drive axis A1.

[0104] 38. A component 150 according to any one of Proposals 32 to 37, characterized in that the clock shaft 1 has a plurality of revolution surfaces around the drive axis A1, and each of the plurality of revolution surfaces has a generatrix having a radius of curvature greater than 40 μm or 50 μm at all points on the generatrix in a plane P passing through the drive axis A1.

[0105] 39. Assembly 150 according to any one of proposals 32 to 38, characterised in that timepiece axle 1 comprises at least one pivot 12, preferably two pivots.

[0106] 40. An assembly 150 according to any one of proposals 32 to 39, characterized in that the second stop portion is frustoconical and has a half angle at the vertex between 30° and 60° (inclusive), and / or characterized in that the distance L between the second drive portion 34 and the second stop portion 31 measured along the drive axis A1 is at least 0.05 mm, or even at least 0.1 mm.

[0107] 41. The component 150 according to any one of proposals 32 to 40, characterized in that the elements 2; 3; 4 are the balance wheel 2 or the plate or double plate 3 or the inner stud 4.

[0108] 42. A timepiece movement 200, comprising a component according to any one of proposals 32 to 41.

[0109] 43. A timepiece 300, in particular a watch, comprising:

[0110] - a timepiece movement 200 according to proposal 42, and / or

[0111] - a component 150 according to any one of proposals 32 to 41.

[0112] Any combination of the features of the first, second and third aspects can be envisaged if there is no logical or technical incompatibility. Description of the Drawings

[0113] The drawings represent, by way of example, two embodiments of a timepiece according to the invention.

[0114] Figure 1 is a schematic view of a first embodiment of a timepiece according to the invention.

[0115] Figure 2 is a detailed partial cross-sectional view at the level of the pivot of the first embodiment.

[0116] Figure 3 is a detailed partial cross-sectional view at the level of the assembly of the double plate to the timepiece shaft of the first embodiment.

[0117] Figure 4 is a detailed partial cross-sectional view at the level of the assembly of the double plate to the timepiece shaft of a second embodiment of a timepiece according to the invention. Detailed Description

[0118] The following will refer to Figures 1 to 3 The first embodiment of the timepiece 300 will be described in detail.

[0119] The timepiece 300 is, for example, a watch, in particular a wristwatch. The timepiece 300 includes a timepiece movement 200, which is intended to be installed in a timepiece case in order to protect the timepiece movement 300 from the external environment.

[0120] The timepiece movement 200 can be a mechanical movement, in particular an automatic movement, or a hybrid movement. Alternatively, the movement can be an electronic movement.

[0121] The timepiece movement 200 includes a component 150, which includes:

[0122] - a timepiece shaft 1, and

[0123] - Elements 2; 3; 4 mounted on the clockwork shaft 1, in particular driven onto the clockwork shaft 1.

[0124] The clockwork movement 200 includes an assembly 100, which assembly 100 includes:

[0125] - The clockwork shaft 1 or the assembly 150, and

[0126] - The pivot bearing 50, in particular the pivot jewel 50.

[0127] The pivot bearing 50 may include a pivot jewel 50 and a counter pivot jewel 59. The pivot jewel 50 and the counter pivot jewel 59 may form part of a shock absorber system.

[0128] The pivot jewel 50 preferably includes a hole 51 for the pivoting of the clockwork shaft 1 around a second axis of rotation A2. The hole 51 advantageously includes:

[0129] - A first region 52 for pivoting the clockwork shaft 1, and

[0130] - A second clearance region 53, which extends from the first face 54 of the bearing, in particular of the pivot jewel 50, to the first pivoting region 52,

[0131] The face 54 is perpendicular or substantially perpendicular to the second axis of rotation A2 and is designed to be oriented on the side of the body 15 of the clockwork shaft 1. The first pivoting region 52 and the second clearance region 53 are connected to each other by a connecting fillet 55.

[0132] Preferably, the first pivoting region 52 is configured to have a minimum diameter, which is located at a position remote from the two ends of the hole, in particular remote from the face 54 and the other face of the jewel bearing 50 opposite the face 54. In other words, the bearing region of the clockwork shaft 1 on the pivot jewel 50 is not located at the edge of the hole 51. Preferably, the counter pivot jewel 59 includes a planar contact surface designed to cooperate with the end 13 of the clockwork shaft 1.

[0133] Using such a pivot jewel with such a clearance region 53 can improve performance by minimizing the pivot play and minimizing the risk of the clockwork shaft 1 getting stuck in the pivot jewel 50 when using a clockwork shaft 1 with the optimized pivot geometry described hereinafter. In fact, surprisingly, the clearance region 53 can minimize the risk of the clockwork shaft 1 getting stuck, the diameter of which (along its geometric axis A1) is more significantly increased than that of a clockwork shaft with a standard geometry.

[0134] The maximum diameter of the second clearance region 53 is advantageously greater than twice or four times or six times the minimum diameter of the first pivoting region 52.

[0135] The assembly may be:

[0136] - An assembled balance wheel including a balance staff, or

[0137] - An assembled escape wheel including an escape wheel staff, or

[0138] - An assembled escapement moving device including an escapement moving device shaft, or

[0139] - An assembled escapement fork assembly including an escapement fork staff, or

[0140] - An assembled escapement fork moving device including an escapement fork moving device shaft.

[0141] For an assembled balance wheel, one or more of the elements may be:

[0142] - The balance wheel 2, and / or

[0143] - The plate 3, in particular a double plate, and / or

[0144] - The inner stud 4, in particular for a hairspring.

[0145] According to a first aspect of the invention, the timepiece shaft 1:

[0146] - Preferably has a first axis of rotation A1, and

[0147] - Preferably includes at least one pivot 12,

[0148] The timepiece shaft 1 has a revolution surface about the first axis of rotation A1, the generatrix G of which is curved in a plane P passing through the first axis of rotation A1. The revolution surface extends at least at the level of the pivot, which is defined as the region of the timepiece shaft 1 intended to come into contact with the pivot jewel 50.

[0149] Alternatively or additionally, according to a second aspect of the invention, the timepiece shaft 1 includes a first portion 24 for driving the elements 2; 3; 4 along the drive axis A1, and the timepiece shaft 1 has the following geometry:

[0150] The geometry includes a frustoconical first stop portion 21, which is adapted to stop the elements 2; 3; 4 during their driving onto the timepiece shaft 1. The first stop portion 21 has a half-angle between 30° and 60° (including the end points) at the apex (the apex of the cone extending the frustoconical surface), and the distance L between the first drive portion 24 and the first stop portion 21 (that is, separating the first drive portion 24 from the first stop portion 21) measured along the drive axis A1 is at least 0.05 mm, or even at least 0.1 mm.

[0151] Figures 1 to 3The first embodiment shown combines these two aspects of the invention.

[0152] The first rotation axis A1 and the drive axis A1 preferably coincide. For this reason, the two axes are shown as coinciding and have the same reference numeral A1. Furthermore, neglecting functional clearances, the first rotation axis A1 and the second rotation axis A2 also coincide.

[0153] The shaft 1 advantageously includes pivots 12 at each of its ends. Each pivot 12 is preferably connected to the body 15 by a pivot rod 14.

[0154] In the case of a balance wheel, the shaft has different functions. On the one hand, the pivots 12 located at the ends of the shaft enable the balance wheel / hairspring assembly to pivot in cooperation with the bearings. To ensure good performance over time, this function requires:

[0155] - high mechanical strength,

[0156] - a very polished surface condition in terms of its roughness, and

[0157] - a very small diameter.

[0158] Furthermore, the shaft 1 carries the components of the balance wheel / hairspring, such as:

[0159] - a balance wheel forming a wheel with a given inertia,

[0160] - a hairspring that exerts a restoring torque on the oscillating assembly,

[0161] - an inner stud that is driven or assembled onto the shaft 1 and secures the hairspring, or

[0162] - a single plate or a double plate that interacts with the pallet fork assembly of the escapement, for example, by means of pins, on the one hand to unlock the escapement and on the other hand to receive impulses to maintain the oscillation of the balance wheel / hairspring. When, in addition to the plate carrying the pins, the plate includes an additional stage that generally has a smaller diameter, the plate is a double plate, and the additional stage is provided with a notch that interacts with the barbs of the pallet fork assembly to form an anti-flip system that prevents untimely unlocking of the escapement.

[0163] For example, each end 13 of the clock shaft 1 that is particularly designed to contact the reverse pivot jewel 59 is not part of the pivot 12. This reverse pivot jewel 59 is provided to define the longitudinal movement of the clock shaft 1 and cannot pivot the clock shaft 1. Therefore, the reverse pivot jewel 59 does not constitute a pivot jewel.

[0164] Each end 13 of the clock shaft 1 can be:

[0165] - protruding and rounded, or

[0166] - planar, or

[0167] - recessed,

[0168] so as to come into contact with the reverse pivot jewel 59.

[0169] For example, from the point on the surface of the timepiece axis having the most extreme abscissa with respect to the axis A1, i.e., from the most extreme point of the timepiece axis 1, the range between the end 13 and the pivot 12 lies in those positions where the plane tangent to the surface of the timepiece axis 1 forms an angle of less than 10° with the axis A1.

[0170] For example, the range between the connection area and the pivot 12 is formed by a plane at a distance of 50 μm or 210 μm or 250 μm from the end of the axis.

[0171] When moving on the surface of the timepiece axis from one end point (one end) of the timepiece axis 1 to the other end point (the other end) of the timepiece axis, the following are encountered in sequence:

[0172] - the end 13,

[0173] - the pivot 12,

[0174] - the connection area connecting the pivot to the pivot rod, and

[0175] - the pivot rod 14.

[0176] The connection area includes a surface of revolution portion obtained by the rotation of a part 122 of the generatrix curve G.

[0177] The work of the inventors has surprisingly shown that due to the nature of the materials used, the shape of the pivot must be reimagined. Rules based on experience and empirical modifications regarding high-hardness metal alloys do not necessarily apply to shafts made of high-performance technical ceramics, such as yttrium zirconia shafts of the 2YZ or 3YZ type in particular. This approach applies to the shape of the pivot but also to the geometry of the central part 15 (or body 15) of the shaft 1 to which various elements mounted on the balance wheel are assembled.

[0178] Thus, it has been found that when using ceramic-type materials, the traditional geometry of the pivot is not favorable for their mechanical strength. On the one hand, an evolution of the profile as continuous as possible is required, thus avoiding any sudden change in edges or dimensions. In fact, the simulations carried out have shown that each corner and / or edge and / or suddenly changing dimension causes a stress concentration that must be prevented.

[0179] The fact of redefining the transitions between the various parts or zones of the shaft (in particular avoiding the bearing surfaces and edges perpendicular to the axis of rotation A1) makes it possible to improve the shock resistance and limit breakage. This breaks with the traditional shapes seen in the clockmaking dictionaries shown (G.-A. Berner), and even in application EP3594757, which relates to a shaft made of an injectable material such as ceramic. From a dimensional point of view, the work of the inventors has shown that it is necessary to adjust the radius of curvature in the connection zone to minimize stress, in particular to make the radius greater than 40 μm, ideally greater than 50 μm. This first adjustment of the connection radius makes it possible to significantly reduce the stress level in the ceramic material: in batches produced under the same conditions (processing conditions and parameters, product range), when bending loaded at three points (the points where the force presses on the receiving zone of the balance wheel), an increase in the breaking force and a decrease in the number of shafts broken by a standardized shock have been measured:

[0180] - During a first series of tests on ten parts, the radius of curvature in the connection zone was increased from 35 μm to 55 μm, resulting in an increase in the breaking force from 12 N to 16 N and a very significant decrease in the percentage of broken shafts from 50% to 0%;

[0181] - During a second series of tests on ten parts, the radius of curvature in the connection zone was increased from 10 μm to 55 μm, resulting in an increase in the breaking force from 7 - 10 N to 15 N and a decrease in the percentage of broken shafts from 70% to 0%.

[0182] Thus, increasing the radius to 40 μm or even to greater than 50 μm enables a 50% improvement in terms of the breaking force and prevents the shaft from breaking when colliding with the assembled balance wheel during movement.

[0183] The pivot that bears the forces applied to the balance wheel / hairspring is the most critical functional part. As mentioned above, the pivot mates with the bearing to ensure the most regular and efficient possible oscillation of the balance wheel / hairspring by minimizing frictional losses (this also applies to the rotation of the escape wheel or the reciprocation of the escapement fork assembly). If the diameter at the pivot level is smaller, the frictional losses and thus the accuracy of the watch are better. On the other hand, a small diameter results in low mechanical strength and thus high sensitivity to shock. For most metal alloys used for shafts, especially non-magnetic alloys, the deformation behavior exhibits a certain range of plastic deformation: shock can produce irreversible deformation, which leads to defective concentricity of the shaft and deterioration of the timekeeping performance. Ceramic shafts do not plastically deform (or plastically deform very little), and excessive deformation leads to shaft breakage and the watch stopping. Therefore, there is a compromise between the accuracy of the watch (the smallest possible diameter) and the mechanical strength of the shaft (the largest possible diameter). Thus, obtaining a functional ceramic shaft that resists the loads on the watch under demanding conditions is a real challenge.

[0184] As described above, the first part 13 (the end of the clockwork shaft 1) contacts the reverse pivot jewel 59. Such contact occurs, for example, in the horizontal position of the movement (the axis of rotation of the shaft is parallel to the earth's gravity).

[0185] As described above, the second part 12 (the pivot 12) provides contact between the shaft 1 and the pivot jewel 50, with the surface of the pivot pressing against the pivot jewel 50, especially in the vertical and inclined positions of the movement.

[0186] Each pivot includes a first toroidal surface portion (obtained by the rotation of the first part 121 of the generatrix curve G), which, as described above, is intended to contact the pivot jewel 50.

[0187] The shaft 1 also includes at least one connection region, which includes a second toroidal surface portion (obtained by the rotation of the second part 122 of the generatrix curve G). Each connection region enables the pivot to be connected to the pivot rod 14 or, in the absence of a pivot rod, directly to the body 15 of the shaft 1. Studies have shown that these connection regions are important for mechanical strength.

[0188] According to the prior art, the axial section (relative to the axis A1) of the first surface portion is straight: the first surface portion is cylindrical or frustoconical. This geometry is mainly due to the machining process used to produce the pivot, especially the rolling process, which does not allow freedom to produce a varying shape. According to the present invention, the use of laser machining enables the production of a first surface portion whose axial section (relative to the axis A1) is not straight.

[0189] In the first variant, the radius of curvature of the generatrix G at each point is less than 2 mm, especially less than 1.8 mm.

[0190] In a second variant, which may be combined with the first variant, the cross-sectional diameter of the toroidal surface continuously increases in the direction away from the proximal end 13 of the clockwork shaft 1 and towards the distal end of the clockwork shaft 1. The proximal end of the clockwork shaft 1 is the end 13 of the shaft that is (along the axis A1) closest to the toroidal surface. The distal end of the clockwork shaft 1 is the end 13 of the shaft that is (along the axis A1) at the greatest distance from the toroidal surface.

[0191] According to a third variant, which may be combined with the first and / or second variants, the radius of curvature of the generatrix G (along the axis A1) decreases in the direction away from the proximal end 13 of the clockwork shaft 1 and towards the distal end of the clockwork shaft 1.

[0192] In a particular embodiment, the generatrix G may include, at the level of the pivot, a first portion 121 that is convex when viewed from the first axis of rotation A1. The tangent to the first portion lies between the first portion and the axis A1. The second derivative of the first portion 121 with respect to the axis A1 is strictly positive in the direction away from the proximal end of the clock axis 1 and towards the distal end of the clock axis 1.

[0193] In an alternative embodiment, the generatrix G may have, at the level of the pivot, a first portion 121 that is concave when viewed from the first axis of rotation A1. The first portion lies between the tangent to the first portion and the axis A1. The second derivative of the first portion 121 with respect to the axis A1 is strictly negative in the direction away from the proximal end of the clock axis 1 or towards the distal end of the clock axis 1.

[0194] In this alternative embodiment, the distance R from the first portion 121 to the first axis of rotation A1 preferably increases as a function of the distance d to the proximal end 13 of the clock axis 1 according to the following law: R = A × (d + B) 1 / 3 , where A and B are constants. Thus, the distance R is the radius of the cross-section (perpendicular to the axis A1) at the distance d from the proximal end 13 of the clock axis 1. It is interesting to note that with such dimensions, the pivot can be longer without increasing the maximum stress. This will allow the pivot to bend more and will be able to limit the axial movement.

[0195] Regardless of which of the two embodiments just mentioned is chosen, the first portion 121 may be part of a circle or an arc having a first radius of curvature R1.

[0196] Furthermore, regardless of the embodiment, the generatrix G advantageously has a second portion 122 that is convex when viewed from the first axis of rotation A1. The tangent to the second portion lies between the second portion and the axis A1. The second derivative of the second portion 122 with respect to the axis A1 is strictly positive in the direction away from the proximal end of the clock axis 1 and towards the distal end of the clock axis 1. The first portion and the second portion are advantageously connected continuously, (the radius R at the connection level of the first portion and the second portion is the same), in particular continuously in tangency (the tangents at the connection level of the first portion and the second portion are the same) and / or continuously in curvature (the curvatures at the connection level of the first portion and the second portion are the same).

[0197] The second portion 122 may be part of a circle or an arc having a second radius of curvature R2.

[0198] As a variant of the first and second portions in the form of arcs, the generatrix G may consist of spline curves or portions of spline curves that are connected continuously, in particular continuously in tangency and / or continuously in curvature.

[0199] Compared with the traditional geometry formed by a frustoconical pivot connected to a pivot rod through an arc fillet, the geometry of the above-mentioned type of test conducted by the inventors shows very obvious improvements. In the case of having a considerable axial clearance of the clock shaft 1 in the pivot jewel, through simulation, the reduction of stress is estimated to be 10%.

[0200] The stress can also be reduced by reducing the axial clearance.

[0201] Tests have been conducted to compare the optimized pivot as described above and the standard frustoconical pivot of a clock shaft made of ZrO2. Obviously, compared with the clock shaft having a standard pivot, the optimized pivot can reduce the stress in the clock shaft 1 by 24%. In addition, obviously, compared with the clock shaft having a standard pivot, the optimized pivot can increase the breaking force by 30%.

[0202] The inventors have noticed that the central part (or body 15) of the clock shaft 1, that is, the part 11 including in particular the rod and the hub receiving the balance wheel, the inner stud of the hairspring and / or the seat or seating part of the single plate or double plate, also includes potential weak areas, especially in the case where the shaft is made of a ceramic material. It has been proven that when the shaft is made of a ceramic material, the traditional elements (such as the bearing surface) or sudden changes in dimensions of the structure of the balance wheel shaft weaken the strength of the shaft. Some characteristics that do not cause any problems to high-performance metal alloys are revealed as the key weak points of technical ceramics.

[0203] For the pivot, the inventors have noticed that corners and edges that are conducive to stress concentration should generally be avoided. The geometry must be optimized, especially the geometry of the various elements received and assembled onto the shaft, to reduce the stress level. Generally speaking, in order to minimize stress, a radius of curvature of at least 20 μm, preferably at least 50 μm, needs to be used.

[0204] The first solution to limit stress and increase the strength of the shaft between the pivots is to use a tapered bearing surface for some of the elements assembled onto the shaft, as described below in a non-limiting manner for the example of the double plate.

[0205] In the case of a traditional assembly with a double plate, the double plate includes holes with inlet chamfers on either side, and these inlet chamfers facilitate the machining of the double plate and the assembly by driving the double plate onto the shaft. The double plate is driven while pressing on the bearing surface of the clock shaft 1, and the chamfers do not fit with the shaft: there is a space left between:

[0206] - the chamfers of the double plate, and

[0207] - the fillet of the connection on the shaft between the receiving part and the bearing surface.

[0208] In the case of an optimized geometry, the double plate 3 includes a frustoconical bearing surface 31 which is wider than a simple chamfer or a simple chamfer edge. This surface 31 bears directly on a corresponding frustoconical surface 21 on the watch axis 1. In order to obtain a controlled positioning of the components assembled on the watch axis 1, the angles of the corresponding two surfaces are ideally the same or comparable. This arrangement makes it possible to control the position of the double plate using a clearly defined stop, while avoiding a sudden change in the cross-section of the balance wheel axis and thus minimizing the stress in the axis. Bearing on a cone (for example a 45° cone) also enables the double plate to have better shock resistance, shocks tending to cause a relative movement of the watch axis 1 and the double plate 3 with respect to the drive axis A1, in particular a relative movement about the drive axis A1.

[0209] Tests have been carried out with a nominal height and a nominal width of 0.07 mm (on the assembled component side) for the frustoconical bearing surface 31, and the results have been entirely satisfactory, with no problems detected. The dimensions of the frustoconical bearing surface 31 must be adapted to the strength of the material of the double plate, since a reduction in the width of the frustoconical bearing surface 31 increases the risk of flanging of the inner edge of the material of the double plate in the event of a shock. The dimensions of the frustoconical bearing surface 31 are estimated as follows:

[0210] - For a heavy balance wheel (typical inertia and dimensions of a movement with a large diameter ≥ 25 mm), a width (measured along the axis A1) and / or a height (measured perpendicular to the axis A1) of 0.05 mm, and

[0211] - For a light balance wheel (movement with a small diameter < 25 mm), a width (measured along the axis A1) and / or a height (measured perpendicular to the axis A1) of 0.04 mm.

[0212] In all cases, it seems advisable that the frustoconical bearing surface 31 on the double plate be no less than the bearing surface which ensures that the assembled components (such as the double plate) have no flanging of the inner edge or only slight flanging of the inner edge in the event of an axial shock.

[0213] In terms of the angle of the frustoconical support surface 31, the selected value is the result of a compromise between two opposing requirements. In order to increase the strength of the shaft as gradually as possible, a transition in shape or diameter is required, and thus the angle between the axis of rotation and the frustoconical surface needs to be as small as possible. Generally speaking, an angle ≤ 45° between the axis of symmetry and the frustoconical surface can greatly reduce the stress in the shaft in the case of a radial impact. On the contrary, for the assembled components, a larger angle is required as much as possible to ensure good positioning on the shaft after driving. The compromise adopted is an angle of 45° (half-angle at the vertex of the cone formed by the frustoconical section). In this case, a minimum angle of 30° (half-angle at the vertex of the cone) enables good positioning while avoiding too obvious a transition in the diameter on the shaft, which would weaken the strengthening of the shaft and the reduction of stress, and reduce the improvement compared to the standard geometry. Another requirement is less critical and will depend on the elastic strength of the material of the assembled components and the accuracy of the relative positioning of the various elements (e.g., precise chamfers on the assembled components). Obviously, an angle of 60° may be suitable. In summary, the ideal angle appears to be 45° (half-angle at the vertex of the cone), and the allowable range is 30° to 60° (half-angle at the vertex of the cone).

[0214] This support on the cone will be different from the "Morse cone" (or drive cone) or "ISO cone" type couplings or clamps used in other fields. In this case, the cone angle of the shaft is smaller, about 3° or less for the "Morse cone".

[0215] A second solution for limiting stress, which can be highly advantageously combined with the first solution, is to move the receiving or driving part 24 of the element (e.g., a double plate) away from the support or stop part 21. When the element 3 is mounted on the clock shaft 1, the element is driven along the axis A1 on the clock shaft 1, especially on the driving part 24, and when the element 3 is pressed against the support or stop part 21 of the clock shaft 1, the element 3 stops axially relative to the clock shaft 1. Therefore, the element 3 includes:

[0216] - a driving part 34 that cooperates with the receiving or driving part 24, and

[0217] - a stop or support part 31 that cooperates with the stop or support part 21.

[0218] In the case of the standard geometry, the driving area is located as close as possible to the support surface to facilitate the machining and assembly of the components and to increase the mechanical strength of the shaft.

[0219] The inventors have noted that this arrangement is disadvantageous in the case of a ceramic shaft or mandrel: the optimized geometry actually aims to move the receiving part 24 away from the support part 21 by providing a region 25 with a smaller cross-section between the part 24 of the receiving member and the support part 21, which prevents any contact and clamping with the clock shaft 1 near the support part 21. This makes it possible to prevent the accumulation of stresses associated with the drive element and with the change in cross-section caused by the presence of the support region 21. This solution is counterintuitive a priori: in fact, measurements show that, as Figure 3 shown, using this optimized geometry, only the strength of the clock shaft 1 is reduced. However, once the element is assembled onto the shaft, the element-shaft assembly is significantly less fragile and more robust than the element-shaft assemblies known in the prior art, particularly in terms of shock resistance.

[0220] The influence of the central geometry of the shaft (shaft body 15) has been characterized using batches of five components at the bearing level of the double plate. A version with an optimized geometry according to the second aspect of the invention has been compared with a standard or conventional version (the support surface is perpendicular to the axis A1 and adjacent to the drive part of the double plate). This characterization is achieved by performing a three-point bending test on the assembled balance wheel / hairspring, with reaction forces at the level of each pivot and the force applied at the level of the receiving part of the balance wheel. The breaking force of the standard version is 17.3 ± 1.2 N, and the breaking force of the optimized version is 18.9 ± 0.6 N, i.e., a statistically significant difference of 10%. This improvement is comparable to the improvement expected after numerical simulation and enables additional operating safety and improved shock resistance for the ceramic balance wheel shaft. The same order of improvement was also found for the average drop height that causes the balance wheel shaft to break at the level of its central part (severe ram impact test). It is very likely that system optimization will be able to further increase the improvement obtained.

[0221] The purpose of the separation part between the receiving part 24 and the support part 21 is to separate the stress regions generated on the one hand by the drive and on the other hand by the cross-section change, particularly when the watch shaft 1 is subjected to bending deformation.

[0222] Simulations have been carried out to estimate the minimum size L of the separation region. For a distance L of 0.02 mm between the receiving part 24 and the support part 21, the stress fields coincide. For a distance of 0.05 mm, separation occurs and the stress is reduced by 5%. The separation at a distance of 0.1 mm is clearly marked, and the stress is reduced by 10% compared to a distance of 0.02 mm.

[0223] Therefore, the presence of a groove 25 or a separating part 25 having a diameter smaller than that of the first driving part 24 and capable of separating the first driving part 24 and the first stopping part 21 is very beneficial, and a distance of 50 μm, more specifically 100 μm, has been presented in the simulation. This separation is produced by the groove on the shaft. The depth does not seem to be a parameter affecting the simulation performed. The groove depth is, for example, 7 μm (the radius difference between the groove 25 and the part 24 is 7 μm). Additionally and / or alternatively, the radius difference between the hole 34 of the driven element 3 and the bottom of the groove can be approximately 4 μm.

[0224] The driving part 24 and the separating part 25 are advantageously connected by one or more rounded corners, and / or the first stopping part 21 and the separating part 25 are advantageously connected by one or more rounded corners.

[0225] The following refers to Figure 4 Describe a second embodiment of the clock according to the present invention.

[0226] The second embodiment preferably differs from the first embodiment in that the geometries of the clock shaft 1 and the element 3 can separate the parts that generate stress on the clock shaft 1.

[0227] The element 3 includes:

[0228] - A second driving part 34 on the clock shaft 1, and

[0229] - A frustoconical second stopping part 31 for stopping the element 3 when the element 3 is driven onto the clock shaft 1.

[0230] The second stopping part has a half-angle between 30° and 60° (including the endpoints) at the vertex, and the distance L separating the second driving part 34 and the second stopping part 31 measured along the driving axis A1 is at least 0.05 mm, even at least 0.1 mm.

[0231] To achieve this distance, the element 3 preferably includes a recess 35 between the second driving part 34 and the second stopping part 31, as Figure 4 shown. As an alternative to the recess 35, a tapered hole part can be made to connect the parts 31 and 34.

[0232] Note that for this type of embodiment, it is not necessary to provide a groove on the clock shaft 1 between the parts 24 and 21.

[0233] Regardless of the embodiment or variant, the clock shaft 1 is advantageously made of the following materials:

[0234] - Technical ceramics, especially zirconia or alumina, or

[0235] - Glass, especially metallic glass, or

[0236] - Steel, especially carbon steel, or

[0237] - Paramagnetic austenitic steel, or

[0238] - Metallic alloy, or

[0239] - High-entropy alloy, or

[0240] - Composite material, especially a composite material including ceramic fillers in a metallic matrix.

[0241] Technical ceramic materials such as zirconia or alumina have mechanical characteristics and properties that are of interest for many applications. On the other hand, their use in watch movement components is difficult, especially due to the challenge of obtaining small components with very small tolerances and due to the fragility of the materials. These two obstacles particularly limit the use of ceramics at the level of the shafts of the movement (especially the balance staff), although their high hardness and their paramagnetic properties make them materials of choice.

[0242] However, the geometry of the shafts of the above solutions has proven to be particularly suitable for ceramic materials, optimized at the level of the pivots and the bodies of the shafts, and these optimizations can significantly increase the strength and the breaking force of the shafts. These new geometries facilitate the use of ceramic shafts by ensuring that the strict technical requirements regarding the shock resistance of the watch movement are met.

[0243] Regardless of the implementation or variant, the watch shaft can have a plurality of revolution surfaces and the plurality of revolution surfaces of the watch shaft 1 about a first rotation axis A1 can each have a generatrix that has a radius of curvature greater than 40 μm or 50 μm at any position on the generatrix in a plane P passing through the first rotation or drive axis A1.

[0244] Regardless of the implementation or variant, the watch shaft 1 advantageously has a revolution geometry about the drive or rotation axis A1.

[0245] Regardless of the implementation or variant, the stop portion and / or the drive portion do not need to be circular.

[0246] Regardless of the implementation or variant, the transverse dimension of the drive portion, especially the diameter, can be between 0.2 mm and 1 mm, or even between 0.2 mm and the maximum diameter of the watch shaft minus the width of the bearing surface 21. Preferably, the drive portion and / or the receiving portion have a cylindrical geometry, especially with a constant or substantially constant diameter.

[0247] Preferably, regardless of the implementation or variant, the axial dimension (measured parallel to the geometric axis A2) is:

[0248] - The axial dimension of the drive part 24 is greater than 0.1 mm, or 0.1 times the drive diameter or even 0.25 times the drive diameter, and / or

[0249] - The axial dimension of the drive part 34 is greater than 0.1 mm, or 0.1 times the drive diameter or even 0.25 times the drive diameter.

[0250] Even more preferably, regardless of the embodiment or variant, the contact between the following two is not linear (circular):

[0251] - The drive part 24, and

[0252] - The drive part 34.

[0253] This contact is not in the form of a curve, but in the form of a surface. This also applies to the shapes of the drive parts 24 and 34.

[0254] In the illustrated embodiment, the stop parts 21, 31 are conical or frustoconical. Alternatively, regardless of the embodiment or variant, the stop parts 21, 31 can be planar.

[0255] Embodiments or variants applied to driving a double plate onto a balance wheel shaft have been described. However, the described solutions are applicable to mounting any type of element on any type of watchmaking shaft, such as mounting a hairspring collet on a balance wheel shaft, mounting a balance wheel on a balance wheel shaft, mounting an escapement fork plate on an escapement fork lever, mounting an escapement wheel plate on an escapement wheel, or mounting a moving device plate on a moving device shaft or pinion.

[0256] Document EP3258325A1 describes a watchmaking shaft made of a natural paramagnetic ceramic material, in particular a balance wheel shaft. The advantage of ceramics is that, unlike pivot shafts made of plastically deformable metal alloys, such pivot shafts do not leave marks in the case of severe impacts. In addition, the work of the applicant of application EP3258325A1 has shown that ceramic shafts may not wear during operation due to their high hardness, which enables performance to be maintained over time compared to most paramagnetic metal alloys.

[0257] Due to these above-mentioned solutions, by using ceramic materials, performance equivalent to that of alloys conventionally used for producing watchmaking shafts can be obtained. In fact, for the same shaft geometry, the brittle behavior of ceramics essentially results in a strength lower than that of the best ferromagnetic alloys (such as 20AP alloy).

[0258] The development work carried out has particularly made it possible to:

[0259] - By optimizing the shape of the pivot, achieve a 25% improvement in the maximum yield stress,

[0260] - By changing the design of the shaft, in particular by using a gradual variation of the cross-section, large connection radii, introducing conical bearing surfaces for some of the elements mounted on the shaft, and spacing the receiving / driving part and the bearing part apart, the breaking force is increased by 10%.

[0261] The described solution is also capable of improving the mechanical properties of clock shafts made of materials other than ceramics.

[0262] Throughout this text, a "fillet" means a rounded part that joins two surfaces (e.g., two cylindrical surfaces with different diameters) in a part of any shape. The cone of what watchmakers call a conical pivot is actually usually a fillet that joins the pivot to the rest of the clock shaft.

[0263] Throughout this text, a "bearing surface" means any surface of a clock shaft that is not parallel to the longitudinal direction of the clock shaft and on which an element mounted on the clock shaft can rest. Unless a specific geometry is specified, a "bearing surface" means a plane perpendicular to the longitudinal direction of the clock shaft.

Claims

1. A component (150), in particular an assembled balance wheel (150), comprising: - a clockwork shaft (1), and - an element (2; 3； 4)， The clockwork shaft (1) has a first drive portion (24) and a first stop portion (21) arranged to stop the element (2; 3; 4) during the driving of the element (2; 3; 4) onto the clockwork shaft (1). The element (2; 3; 4) has a second drive portion (34) on the clockwork shaft (1) and a second stop portion (31) arranged to stop the element (2; 3; 4) during the driving of the element (2; 3; 4) onto the clockwork shaft (1). The first drive portion (24) and the first stop portion (21) are separated by a separating portion (25) having a diameter smaller than that of the first drive portion (24), and / or The element (2; 3; 4) includes a recess (35) between the second drive portion (34) and the second stop portion (31).

2. The component (150) according to claim 1, characterized in that, The first stop portion (21) is frustoconical and has a half-angle, for example, between 30° and 60° at the apex, and / or, the distance (L) separating the first drive portion (24) from the first stop portion (21) measured along the drive axis (A1) is at least 0.05 mm, or even at least 0.1 mm.

3. The component (150) according to claim 1 or 2, characterized in that, The clockwork shaft is the shaft of the balance wheel (2).

4. The component (150) according to any one of the preceding claims, characterized in that The first drive portion (24) and the separating portion (25) are connected by one or more rounded corners, and / or, the first stop portion (21) and the separating portion (25) are connected by one or more rounded corners.

5. The component (150) according to any one of the preceding claims, characterized in that, The clockwork shaft (1) is made of the following materials: - technical ceramics, in particular zirconia or alumina, or - glass, in particular metallic glass, or - steel, in particular carbon steel, or - paramagnetic austenitic steel, or - metal alloy, or - high-entropy alloy, or - composite material, in particular a composite material including ceramic fillers in a metal matrix.

6. The component (150) according to any one of the preceding claims, characterized in that The clockwork shaft (1) has a geometry that rotates about the drive axis (A1).

7. The component (150) according to any one of the preceding claims, characterized in that, The clockwork shaft (1) has a plurality of rotating surfaces about the drive axis (A1), and each of the plurality of rotating surfaces has a generatrix, and the generatrix has a radius of curvature greater than 40 μm or 50 μm at all points on the generatrix in a plane (P) passing through the drive axis (A1).

8. The component (150) according to any one of the preceding claims, characterized in that, The clockwork shaft (1) includes at least one pivot (12), preferably two pivots.

9. The component (150) according to any one of the preceding claims, characterized in that, The second stop portion is frustoconical and has a half-angle between 30° and 60° at the apex, and / or, the distance (L) between the second drive portion (34) and the second stop portion (31) measured along the drive axis (A1) is at least 0.05 mm, or even at least 0.1 mm.

10. The component (150) according to any one of the preceding claims, characterized in that, The element (2; 3; 4) is a balance wheel (2) or a plate or a double plate (3) or an inner stud (4).

11. A clock movement (200), comprising the components according to any one of claims 1 to 10.

12. A clock (300), in particular a watch, comprising: - the clock movement (200) according to the preceding claims, and / or - the components (150) according to any one of claims 1 to 10.

13. A clock shaft (1), comprising a first drive portion (24) for driving an element (2; 3; 4) along a drive axis (A1), the clock shaft (1) having the following geometry: The geometry has a frustoconical first stop portion (21), the first stop portion (21) being arranged to stop the element (2; 3; 4) during the driving of the element onto the clock shaft (1), the first stop portion (21) having a half-angle between 30° and 60° at the apex, and such that the distance (L) measured along the drive axis (A1) separating the first drive portion (24) from the first stop portion (21) is at least 0.05 mm, or even at least 0.1 mm.

14. The clock shaft (1) according to claim 13, characterized in that, The clock shaft is the shaft of the balance wheel (2).

15. The clock shaft (1) according to claim 13 or 14, characterized in that, The first drive portion (24) and the first stop portion (21) are separated by a separating portion (25), the diameter of the separating portion (25) being smaller than the diameter of the first drive portion (24).

16. The clock shaft (1) according to the preceding claim, characterized in that, The first drive portion (24) and the separating portion (25) are connected by one or more rounded corners, and / or the first stop portion (21) and the separating portion (25) are connected by one or more rounded corners.

17. The clock shaft (1) according to any one of claims 13 to 16, characterized in that, The shaft is made of the following materials: - technical ceramics, in particular zirconia or alumina, or - glass, in particular metallic glass, or - steel, in particular carbon steel, or - paramagnetic austenitic steel, or - metal alloy, or - high entropy alloy, or - composite material, in particular a composite material comprising ceramic fillers in a metal matrix.

18. The clock shaft (1) according to any one of claims 13 to 17, characterized in that, The clock shaft (1) has a geometry that rotates about the drive axis (A1).

19. The clock shaft (1) according to any one of claims 13 to 18, characterized in that, The clock shaft (1) has a plurality of rotating surfaces about the drive axis (A1), and each of the plurality of rotating surfaces has a generatrix, the generatrix having a radius of curvature greater than 40 μm or 50 μm at all points on the generatrix in a plane (P) passing through the drive axis (A1).

20. The clock shaft (1) according to any one of claims 13 to 19, characterized in that, The clock shaft (1) includes at least one pivot (12), preferably two pivots.

21. A component (2; 3; 4), which is intended to be driven onto the clock shaft (1) along the drive axis (A1), the element (2; 3; 4) comprising: - a second drive portion (34) on the clock shaft (1), and - a frustoconical second stop portion (31), the second stop portion (31) being arranged to be in the element (2; 3; 4) During the process of driving onto the clockwork shaft (1), the element (2; 3; 4) is stopped, the second stop portion has a half-angle between 30° and 60° at the vertex, and the distance (L) between the second driving portion (34) and the second stop portion (31) measured along the driving axis (A1) is at least 0.05 mm, or even at least 0.1 mm.

22. The element (2; 3; 4) according to the preceding claim, characterized in that The element (2; 3; 4) is a balance wheel (2) or a plate or a double plate (3) or an inner stud (4).

23. The element (2; 3; 4) according to claim 21 or 22, characterized in that, The element (2; 3; 4) includes a recess (35) between the second driving portion (34) and the second stop portion (31).

24. A component (150), in particular an assembled balance wheel (150), comprising: - a clockwork shaft (1), in particular the clockwork shaft (1) according to any one of claims 13 to 20, and - an element (2; 3; 4) driven onto the clockwork shaft (1), in particular the element (2; 3; 4) according to any one of claims 21 to 23.

25. A clockwork movement (200), comprising: - the clockwork shaft (1) according to any one of claims 13 to 20, and / or - the element (2; 3; 4) according to any one of claims 21 to 23, and / or - the component according to claim 24.

26. A clock (300), in particular a watch, comprising: - the clockwork movement (200) according to the foregoing claims, and / or - the clockwork shaft (1) according to any one of claims 13 to 20, and / or - the element (2; 3; 4) according to any one of claims 21 to 23, and / or - the component (150) according to claim 24.

27. A clockwork shaft (1), in particular the shaft of a balance wheel (2) or the shaft of an escape wheel or the shaft of an escapement fork: - having a first axis of rotation (A1), and - including at least one pivot (12), The clockwork shaft (1) has a surface of revolution about the first axis of rotation (A1), the generatrix (G) of the surface of revolution is curved in a plane (P) passing through the first axis of rotation (A1), and the surface of revolution extends at least at the level of the pivot, and the pivot is defined as the area of the clockwork shaft (1) intended to contact a pivot bearing (50), in particular a pivot jewel (50).

28. The clockwork shaft (1) according to claim 27, wherein: - the radius of curvature of the generatrix (G) at all points is less than 2 mm, in particular less than 1.8 mm, and / or - the diameter of the cross-section of the surface of revolution continuously increases in the direction away from the proximal end (13) of the clockwork shaft (1), and / or - the radius of curvature of the generatrix (G) decreases in the direction away from the proximal end (13) of the clockwork shaft (1).

29. The clockwork shaft (1) according to any one of claims 27 or 28, wherein the generatrix (G) has a first portion (121) that is convex when viewed from the first axis of rotation (A1) at the level of the pivot.

30. The timepiece shaft (1) according to any one of claims 27 or 28, wherein the generatrix (G) has a first portion (121) that is concave as seen from the first axis of rotation (A1) at the level of the pivot.

31. The clockwork shaft (1) according to claim 30, wherein the distance R from the first part to the first axis of rotation (A1) increases as a function of the distance d to the proximal end (13) of the clockwork shaft (1) according to the following law: R = A × (d + B) 1 / 3 , where A and B are constants.

32. The timepiece shaft (1) according to claim 29 or 30, wherein the first portion (121) is part of a circle having a first radius of curvature (R1).

33. The timepiece shaft (1) according to any one of claims 29 to 32, wherein the generatrix (G) has a second portion (122) that is convex as seen from the first axis of rotation (A1), and the first portion and the second portion are continuously connected, in particular continuously connected in tangency and / or continuously connected in curvature.

34. The timepiece shaft (1) according to claim 33, wherein the second portion (122) is part of a circle having a second radius of curvature (R2).

35. The timepiece shaft (1) according to any one of claims 27 to 34, wherein the generatrix (G) consists of a spline curve or a portion of a spline curve that is continuously connected, in particular continuously connected in tangency and / or continuously connected in curvature.

36. The timepiece shaft (1) according to any one of claims 27 to 35, wherein the timepiece shaft includes a plurality of revolution surfaces, and each of the plurality of revolution surfaces of the timepiece shaft (1) about the first axis of rotation (A1) has a generatrix that has a radius of curvature greater than 40 μm or 50 μm at all points on the generatrix in a plane (P) passing through the first axis of rotation (A1).

37. The timepiece shaft (1) according to any one of claims 27 to 36, wherein the timepiece shaft (1) is made of the following materials: - Technical ceramics, in particular zirconia or alumina, or - Glass, in particular metallic glass, or - Steel, in particular carbon steel, or - Paramagnetic austenitic steel, or - Metal alloy, or - High-entropy alloy, or - Composite material, in particular a composite material including ceramic fillers in a metal matrix.

38. An assembly (150), in particular an assembled balance wheel (150), comprising the timepiece shaft (1) according to any one of claims 27 to 37.

39. An assembly (100) comprising: - The timepiece shaft (1) according to any one of claims 27 to 37 or the assembly (150) according to claim 38, and - A pivot bearing (50), in particular a pivot jewel (50).

40. The assembly (100) according to the preceding claims, wherein the pivot bearing (50) includes a pivot jewel (50), and the pivot jewel (50) includes a hole (51) along a second axis of rotation (A2) for pivoting the timepiece shaft (1), and the hole includes: - A first pivoting region (52) in which the timepiece shaft (1) pivots, and - A second clearance region (53) extending from a first face (54) of the bearing to the first pivoting region (52). The face (54) is perpendicular or substantially perpendicular to the second axis of rotation (A2) and is designed to be oriented on the body side of the timepiece axis (1), and the first pivot region (52) and the second clearance region (53) are connected to each other by a connecting fillet (55).

41. The assembly (100) according to the preceding claim, wherein the maximum diameter of the second clearance region (53) is greater than twice or four times or six times the minimum diameter of the first pivot region (52).

42. A timepiece movement (200) comprising the timepiece axis (1) according to any one of claims 27 to 37 and / or the assembly according to claim 38 and / or the assembly according to any one of claims 39 to 41.

43. A timepiece (300), in particular a wristwatch, comprising the timepiece movement (200) according to the preceding claim and / or the timepiece axis (1) according to any one of claims 27 to 37 and / or the assembly according to claim 38 and / or the assembly according to any one of claims 39 to 41.

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