PIVOT ARBOR OF A REGULATING MEMBER

Abstract

A timepiece component for a timepiece movement and notably a pivot arbor of a regulating member of a mechanical timepiece movement, made of an alloy containing by weight: between 25% and 55% of palladium, between 25% and 55% of silver, between 10% and 30% of copper, between 0.5% and 5% of zinc, gold and platinum with a total percentage of these two elements comprised between 15% and 25%, between 0% and 1% of one or more elements chosen from among boron and nickel, between 0% and 3% of one or more elements chosen from among rhenium and ruthenium, no more than 0.1% of one or more elements chosen from among iridium, osmium and rhodium, and no more than 0.2% of other impurities, the respective quantities of the components being such that, added together, they do not exceed 100%.

Claims

1. A timepiece component for a timepiece movement, and notably a pivot arbor of a regulating member of a mechanical timepiece movement, made of an alloy comprising by weight: between 25% and 55% of palladium, between 25% and 55% of silver, between 10% and 30% of copper, between 0.5% and 5% of zinc, gold and platinum with a total percentage of these two elements comprised between 5% and 25%, between 0% and 1% of one or more elements chosen from among boron and nickel, between 0% and 3% of one or more elements chosen from among rhenium and ruthenium, no more than 0.1% of one or more elements chosen from among iridium, osmium and rhodium, and no more than 0.2% of other impurities, the respective quantities of the components being such that, together, they add up to 100%.

2. The timepiece component according to claim 1, wherein the alloy contains by weight between 30% and 40% of palladium.

3. The timepiece component according to claim 1, wherein the alloy contains by weight between 25% and 35% of silver.

4. The timepiece component according to claim 1, wherein the alloy contains by weight between 10% and 18% of copper.

5. The timepiece component according to claim 1, wherein the alloy contains by weight between 0.5% and 1.5% of zinc.

6. The timepiece component according to claim 1, wherein the alloy contains gold and platinum with a total percentage by weight of said two elements comprised between 16% and 24%.

7. The timepiece component according to claim 1, wherein the alloy contains by weight between 8 and 12% of gold and 8 and 12% of platinum with a total proportion of rhenium and ruthenium comprised between 0 and 6% by weight.

8. The timepiece component according to claim 1, made of an alloy containing by weight: between 34% and 36% of palladium, between 29% and 31% of silver, between 13.5% and 14.5% of copper, between 0.8% and 1.2% of zinc, between 9.5% and 10.5% of gold between 9.5% and 10.5% of platinum, no more than 0.1% of one or more elements chosen from among iridium, osmium, rhodium and ruthenium and no more than 0.2% of other impurities, the respective quantities of the components being such that, together, they add up to 100%.

9. The timepiece component according to claim 1, wherein the component comprises at least one part (3) machined by chip removal, said part (3) comprising a hardening layer (5) on the external surface thereof.

10. The timepiece component according to claim 9, wherein the hardening layer (5) is made of a material chosen from the group including Ni and NiP.

11. The timepiece component according to claim 1, wherein said arbor is a balance staff (1), a pallet staff or an escape wheel arbor.

12. The timepiece component according to claim 1, wherein the alloy has a Vickers hardness of 350 HV to 550 HV.

13. A mechanical movement for a timepiece, wherein the movement includes a timepiece component for a timepiece movement, and notably a pivot arbor of a regulating member of a mechanical timepiece movement, made of an alloy comprising by weight: between 25% and 55% of palladium, between 25% and 55% of silver, between 10% and 30% of copper, between 0.5% and 5% of zinc, gold and platinum with a total percentage of these two elements comprised between 5% and 25%, between 0% and 1% of one or more elements chosen from among boron and nickel, between 0% and 3% of one or more elements chosen from among rhenium and ruthenium, no more than 0.1% of one or more elements chosen from among iridium, osmium and rhodium, and no more than 0.2% of other impurities, the respective quantities of the components being such that, together, they add up to 100%.

14. A method for manufacturing a timepiece component for a timepiece movement, and notably a pivot arbor of a regulating member of a mechanical timepiece movement, comprising at least one part machined by chip removal, the method comprising the following steps: a) taking an element machinable by chip removal, said element being made of a non-magnetic alloy containing by weight: between 25% and 55% of palladium, between 25% and 55% of silver, between 10% and 30% of copper, between 0.5% and 5% of zinc, gold and platinum with a total percentage of these two elements comprised between 15% and 25%, between 0% and 1% of one or more elements chosen from among boron and nickel, between 0% and 3% of one or more elements chosen from among rhenium and ruthenium, at most 0.1% of one or more elements chosen from among iridium, osmium and rhodium, and at most 0.2% of other impurities, the respective quantities of the components being such that, together, they add up to 100% b) chip removal machining said timepiece component to form at least the part of said timepiece component that is machined by chip removal and made of said non-magnetic alloy.

15. The manufacturing method according to claim 14, wherein the method further includes a heat hardening step d).

16. The manufacturing method according to claim 15, wherein heat hardening step d) is performed at a temperature comprised between 350° C. and 450° C. for a time comprised between 30 minutes and 3 hours, more particularly between 30 minutes and 1 hour 30 minutes.

17. A method according claim 15, wherein the method further includes a step e) of depositing a hardening layer (5) at least on an outer surface (5) of said part (3) machined by chip removal.

18. The method according to claim 17, wherein hardening layer (5) is made of a material chosen from the group including Ni and NiP.

19. The method according to claim 14, wherein the method includes a rolling and/or polishing step c) performed on said part (3) machined by chip removal after step b), after step d) or after step e).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Other features and advantages will appear clearly from the following description, given by way of non-limiting illustration, with reference to the annexed drawings, in which:

[0039] FIG. 1 is a representation of a timepiece component, and more precisely of a balance staff, according to the invention; and

[0040] FIG. 2 is a partial sectional view of a part machined by chip removal of the timepiece component according to a variant of the invention, after an operation of depositing a hardening layer and after a rolling or polishing operation. More precisely, FIG. 2 is a partial sectional view of one of the pivots of the arbor of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0041] In the present description, the term “non-magnetic” alloy means a paramagnetic or diamagnetic or antiferromagnetic alloy, whose magnetic permeability is less than or equal to 1.01.

[0042] The term “chip removal machining” means any shaping operation by a material removal process intended to give a component dimensions and a surface finish within a given tolerance range. Such operations are, for example, profile turning, milling or any other technique known to those skilled in the art.

[0043] The invention relates to a component for a timepiece movement and particularly to a non-magnetic timepiece component , such as a pivot arbor, for a mechanical timepiece movement.

[0044] The invention will be described below in the context of application to a non-magnetic balance staff 1 as represented in FIG. 1. Of course, other types of timepiece pivot arbors can be envisaged, such as, for example, timepiece wheel arbors, typically escape pinions, or pallet staffs. Components of this type have a body with a diameter preferably less than 2 mm, and pivots with a diameter preferably less than 0.2 mm, with a precision of several microns. Other timepiece components that can be envisaged are screws, winding stems, balance spring studs, etc., and may have similar dimensions to those mentioned above for the arbors.

[0045] Referring to FIG. 1, there is shown a balance staff 1 according to the invention, which includes a plurality of sections 2 of different diameters, preferably formed by profile turning or any other chip removal machining technique, and defining, in a conventional manner, bearing surfaces 2a and shoulders 2b arranged between two end portions defining two pivots 3. These pivots are each intended to pivot in a bearing, typically in an orifice in a jewel or ruby.

[0046] According to the invention, at least one part of the timepiece component, and, in the example illustrated at least one pivot 3, is made of a non-magnetic metal alloy 4 in order to limit its sensitivity to magnetic fields. This alloy contains or includes by weight: [0047] between 25% and 55% of palladium, [0048] between 25% and 55% of silver, [0049] between 10% and 30% of copper, [0050] between 0.5% and 5% of zinc, [0051] gold and platinum with a total percentage of these two elements comprised between 15% and 25%, [0052] between 0% and 1% of one or more elements chosen from among boron and nickel, [0053] between 0% and 3% of one or more elements chosen from among rhenium and ruthenium, [0054] no more than 0.1% of one or more elements chosen from among iridium, osmium and rhodium, and [0055] no more than 0.2% of other impurities, the respective quantities of the components being such that, added together, they do not exceed 100%.

[0056] Advantageously, the alloy contains or includes by weight: [0057] between 30% and 40% of palladium, [0058] between 25% and 35% of silver, [0059] between 10% and 18% of copper, [0060] between 0.5% and 1.5% of zinc, [0061] between 8 and 12% of gold and 8 and 12% of platinum, with a proportion of rhenium and ruthenium comprised between 0 and 6% by weight.

[0062] According to a still more preferred embodiment, the alloy of the invention contains by weight: [0063] between 34% and 36% of palladium, [0064] between 29% and 31% of silver, [0065] between 13.5% and 14.5% of copper, [0066] between 0.8% and 1.2% of zinc, [0067] between 9.5% and 10.5% of gold [0068] between 9.5% and 10.5% of platinum, [0069] no more than 0.1% of one or more elements chosen from among iridium, osmium, rhodium and ruthenium and [0070] no more than 0.2% of other impurities, the respective quantities of the components being such that, together, they add up to 100%.

[0071] According to a still more preferred embodiment, the alloy of the invention contains by weight 35% of palladium, 30% of silver, 14% of copper, 10% of gold, 10% of platinum and 1% of zinc. The present invention also relates to the method for manufacturing the timepiece component for a timepiece movement and, in particular, the pivot arbor of a regulating member of a mechanical timepiece movement comprising the following steps:

[0072] a) taking an element machinable by chip removal, said element being made of a non-magnetic alloy containing by weight: between 25% and 55% of palladium, between 25% and 55% of silver, between 10% and 30% of copper, between 0.5% and5% of zinc, gold and platinum with a total percentage of these two elements comprised between 15% and 25%, between 0% and 1% of one or more elements chosen from among boron and nickel, between 0% and 3% of one or more elements chosen from among rhenium and ruthenium, at most 0.1% of one or more elements chosen from among iridium, osmium and rhodium, and at most 0.2% of other impurities, the respective quantities of the components being such that, together, they add up to 100%

[0073] b) chip removal machining said timepiece component to form at least one part of said timepiece component that is machined by chip removal and made of said non-magnetic alloy.

[0074] The method may also include, after the machining step b), a surface finish treatment step c) such as rolling and/or polishing.

[0075] The method can also include a heat treatment step d) typically a structural hardening treatment, intended to increase the hardness of the alloy to a hardness comprised between 350 and 550 HV1. This heat treatment is performed at a temperature comprised between 350 and 450° C. for a time comprised between 30 minutes and 3 hours, more particularly between 30 minutes and 1 hour 30 minutes.

[0076] The structural hardening heat treatment of step d) can be performed before step b) (directly on the chip removal machinable element made of the non-magnetic alloy of the invention, typically in the form of a bar) if the machining process requires high hardness. However, it is preferably performed after the machining of step b) and before step c).

[0077] The heat treatment of step d) can be preceded by a mechanical cold working treatment of the chip removal machinable element made of the non-magnetic alloy of the invention, typically in the form of a bar.

[0078] Referring to FIG. 2, the method can also include a step e) of depositing a hardening layer 5 at least on an outer surface of said part 3 machined by chip removal in step b) before or after step c) and after step d) where appropriate. Preferably, the hardening layer is made of a material chosen from among the group including Ni and NiP.

[0079] The phosphorus content can be comprised between 0 (thus pure Ni) and 15% by weight. Preferably, the phosphorus content is either medium and comprised between 6 and 9% by weight, or high and comprised between 9 and 12% by weight. Deposition of the hardening layer can be performed by PVD, CVD, ALD, electroplating and chemical deposition, and preferably by chemical deposition. Preferably, layer 5 has a thickness comprised between 0.5 and 10 μm, preferably between 1 and 5 μm and more preferably between 1 and 2 μm. This hardening layer makes it possible to obtain excellent shock resistance in the main stress areas.