US-20260126758-A1 - TIMEPIECE STAFF

Abstract

The timepiece shaft ( 1 ), in particular a shaft for a balance ( 2 ) or a shaft for an escapement wheel or a pallet shaft, includes at least one pivot ( 12 ). The timepiece shaft ( 1 ) has a surface of revolution about a first rotation axis (A 1 ) the generatrix (G) of which in a plane (P) passing through the first rotation axis (A 1 ) is curved, this surface of revolution extending at least at the level of the pivot, the pivot being defined as the zone of the timepiece shaft ( 1 ) intended to come into contact with a pivot bearing ( 50 ), in particular with a pivot jewel ( 50 ).

Inventors

• Daniel Moille
• Blaise Fracheboud

Assignees

• ROLEX SA

Dates

Publication Date

20260507

Application Date

20231003

Priority Date

20221003

Claims (20)

1. 1 . An assembly for an assembled balance, the assembly comprising: a timepiece shaft, and an element driven onto the timepiece shaft, the timepiece shaft having a first driving portion and a first abutment portion arranged to halt the element during its driving onto the timepiece shaft, the element having a second driving portion on the timepiece shaft and a second abutment portion arranged to halt the element during driving of the element onto the timepiece shaft, wherein the first driving portion and the first abutment portion are separated by a separation portion having a diameter less than a diameter of the first driving portion, and/or the element comprises a recess between the second driving portion and the second abutment portion.
2. 2 . The assembly according to claim 1 , wherein the first abutment portion is frustoconical, and/or a distance measured along the driving axis and separating the first driving portion from the first abutment portion is at least 0.05 mm.
3. 3 . The assembly according to claim 1 , wherein the timepiece shaft is a shaft for a balance.
4. 4 . The assembly according to claim 1 , wherein the first driving portion and the separation portion are connected by one or more radii, and/or the first abutment portion and the separation portion are connected by one or more radii.
5. 5 . The assembly according to claim 1 , wherein the timepiece shaft is made of: a technical ceramic, or a glass, or a steel, or a paramagnetic austenitic steel, or a metal alloy, or a high-entropy alloy, or a composite material.
6. 6 . The assembly according to claim 1 , wherein the timepiece shaft has a geometry of revolution about the driving axis.
7. 7 . The assembly according to claim 1 , wherein the timepiece shaft has surfaces of revolution about the driving axis and the surfaces of revolution each have a generatrix which, in a plane passing through the driving axis, has a radius of curvature greater than 40 m at all points on the generatrix.
8. 8 . The assembly according to claim 1 , wherein the timepiece shaft includes at least one pivot.
9. 9 . The assembly according to claim 1 , wherein the second abutment portion is frustoconical and has a half-angle at the apex in a range of from 30° and to 60°, and/or a distance measured along the driving axis between the second driving portion and the second abutment portion is at least 0.05 mm.
10. 10 . The assembly according to claim 1 , wherein the element is a balance or a plate or a double plate or a collet.
11. 11 . A timepiece movement, comprising the assembly according to claim 1 .
12. 12 . A timepiece, comprising a timepiece movement according to claim 11 .
13. 13 . A timepiece shaft comprising a first driving portion for driving an element along a driving axis, the timepiece shaft having a geometry comprising a frustoconical first abutment portion arranged to halt an element during driving of the element onto the timepiece shaft, the first abutment portion having a half-angle at the apex in a range of from 30° to 60°, so that a distance measured along the driving axis and separating the first driving portion from the first abutment portion is at least 0.05 mm.
14. 14 . The timepiece shaft according to claim 13 , wherein the timepiece shaft is a shaft for a balance.
15. 15 . The timepiece shaft according to claim 13 , wherein the first driving portion and the first abutment portion are separated by a separation portion having a diameter less than a diameter of the first driving portion.
16. 16 . The timepiece shaft according to claim 15 , wherein the first driving portion and the separation portion are connected by one or more radii, and/or the first abutment portion and the separation portion are connected by one or more radii.
17. 17 . The timepiece shaft according to claim 13 , wherein the shaft is made of: a technical ceramic, in particular zirconia or alumina, or a glass, or a steel, or a paramagnetic austenitic steel, or a metal alloy, or a high-entropy alloy, or a composite material.
18. 18 . The timepiece shaft according to claim 13 , wherein the timepiece shaft has a geometry of revolution about the driving axis.
19. 19 - 43 . (canceled)
20. 44 . The assembly according to claim 5 , wherein the timepiece shaft is made of a composite material including a ceramic charge in a metal matrix.

Description

The invention concerns a timepiece shaft. The invention also concerns an element intended to be mounted on a timepiece shaft. The invention also concerns an assembly comprising a shaft of this kind and/or an element of this kind. The invention further concerns an assembly comprising a shaft of this kind or an element of this kind or an assembly of this kind. The invention further concerns a timepiece movement comprising a shaft of this kind or an element of this kind or an assembly of this kind or a combination of this kind. The invention finally concerns a timepiece comprising a shaft of this kind or an element of this kind or an assembly of this kind or a combination of this kind or a timepiece movement of this kind. A great deal of work and numerous patent applications are aimed at identifying a material and/or a geometry for the shafts of the movement that are both paramagnetic and resistant to mechanical loads when worn. This research relates in particular to the balance shafts, which are particularly heavily loaded. Historically, timepiece shafts are made of carbon steel, which is ferromagnetic. Paramagnetic alloys tested until now clearly offer poorer performance from a mechanical point of view. The mechanical strength of timepiece shafts therefore continues to be a problem. The document WO2021032552A1 describes a particular hole geometry for a pivot jewel. A pivot is schematically represented in FIG. 2 with a frustoconical geometry, but not specified further. The document CH702314 describes a specific pivot geometry with a conical pivot that cooperates with a counter-pivot jewel surface in the form of an inverted pyramid. The document CH704770 describes different geometries of the end of a pivot that cooperates with a counter-pivot jewel. In the vertical position of the movement a portion of the cylindrical surface of the pivot is in contact with the internal surface of the bearing. In a horizontal position of the movement the end of the pivot bears against the counter-pivot jewel. The document CH704770 is particularly concerned with the geometry of the end, proposing to misalign from the pivot axis the bearing point of the timepiece shaft on the counter-pivot jewel. The document EP3258325 discloses a ceramic balance shaft. The pivot-shank and the pivot may be one and the same or not be delimited by a clear boundary such as a bearing surface. The pivot-shank and the pivot can for example be separated by a frustoconical surface or a surface with a curved generatrix. The shaft has a standard geometry at the level of its median part with receiving portions for a plate (cylindrical portion), a balance with a receiving seat forming an abutment and a cylindrical portion and a collet that is not represented. The standard NIHS-34-01 describes standard balance shaft geometries. The shaft comprises a plurality of portions, in particular cylindrical portions, bearing surfaces perpendicular to the axis of symmetry forming abutments, and frustoconical portions. These frustoconical portions are not bearing or abutment surfaces, however, but entry chamfer surfaces to facilitate assembly of the components mounted on the shaft and/or machining. In particular, the plate and the balance are driven so as to bear on the plane or substantially plane surfaces of the seating. The pivots are described as being of cylindrical shape with diameter p, extended by a cone or by a surface of revolution evolving into a circular arc of radius r. A. Haag, in “Theoretische und experimentelle Untersuchungen zum Verhalten der Unruhzapfen bei Stoessen auf die Uhr” (Actes du Congrès International de Chronométrie 1964, p. 1125), describes a general plane of a balance shaft with plane bearing or abutment surfaces and conical receiving portions that form a driving cone. This type of cone is used because it ensures very good centering and facilitates assembly. The driving cone (sometimes termed a Morse cone) rests on nested male and female elements the conical walls of which typically have cone angles of a few degrees and is used to fix parts together in fields such as the machine tools industry and dental applications. The document CH327357 describes a shaft geometry designed to facilitate demounting of the various elements. The shaft includes a cylindrical receiving portion, optionally with a conical portion with a small cone angle and/or a shoulder. The various elements are driven with corresponding bores onto the cylindrical portions. The document CH715867 describes a shaft geometry including a plurality of straight frustoconical sections. The object of these parts is to facilitate the driving of the various elements mounted on the shaft (collet of the balance-spring, balance, plate) and/or machining of the shaft, but they do not constitute bearing or abutment surfaces for the mounted elements. To the contrary, the collet and the plate come to bear on plane surfaces forming shoulders, i.e. forming plane bearing surfaces perpendicular to t