Timepiece axis made of an intermetallic material

Abstract

The present invention relates to a watch axis comprising more than 20% by mass of non-magnetic intermetallic material having a hardness greater than 400 HV.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a watch shaft, in particular a balance shaft, based on intermetallic material. PRIOR STATE OF THE ART

[0002] Mechanical watches include a resonator comprising a balance wheel and a balance spring which are generally mounted on the same shaft called the "balance staff" ( figure 1 ).

[0003] Optimizing the performance of the mechanism (precision, durability, etc.) depends heavily on the balance spring and the quality of its pivoting.

[0004] Generally speaking, a watch shaft, in particular a balance shaft, must therefore meet certain constraints, notably in terms of machinability or resistance (i) to corrosion, (ii) to shocks, (iii) to breakage and (iv) to wear.

[0005] Thus, many materials have been used to manufacture watch axes, for example metal alloys such as martensitic steel, or even ceramics such as zirconia oxide stabilized with yttrium oxide... Balance axes covered with a layer of specific material have also been developed.

[0006] In any case, there is still a need for alternative materials that meet established constraints, are easy to machine, and advantageously non-magnetic. Indeed, martensitic steel has adequate strength properties, but remains susceptible to magnetism and corrosion (which is problematic, particularly during manufacturing and storage), while ceramic remains brittle in the event of repeated impacts. In addition, some materials require a multitude of thermal and mechanical treatments to achieve the required strength properties.

[0007] In addition, the increasing presence of electronic devices constantly exposes watches to magnetic fields, which can cause operational problems when the watch movements are made of steel.

[0008] Therefore, there is still a need to develop alternatives that can simultaneously solve all technical problems, namely machinability and resistance to corrosion, impact, fracture and wear and behavior in the presence of magnetic fields, or after exposure to a magnetic field.

[0009] The present invention addresses these issues through the use of a non-magnetic intermetallic material. STATEMENT OF THE INVENTION

[0010] A first aspect of the invention relates to a watch axis comprising more than 20% by mass, relative to the mass of the watch axis, of non-magnetic intermetallic material having a hardness of at least 400 HV, preferably 450 HV.

[0011] In other words, the non-magnetic intermetallic material does not simply constitute a surface layer of the watch axis.

[0012] The watch axis is advantageously a balance wheel axis.

[0013] Advantageously, the watch axis has a length of less than 5 mm, preferably less than 4 mm, even more preferably less than 3 mm. Advantageously, the watch axis comprises two pivots having a diameter advantageously between 0.02 mm and 0.30 mm, preferably between 0.03 mm and 0.20 mm, even more preferably between 0.04 mm and 0.10 mm.

[0014] A balance shaft supports the balance wheel and hairspring of a watch movement.

[0015] A second aspect of the invention relates to a watch oscillator, comprising a balance staff according to the first aspect as well as at least one additional member such as a balance wheel or an elastic return member. Said at least one additional member is advantageously non-magnetic, for example an elastic return member made of non-magnetic material. The elastic return member can thus be provided in the form of a balance spring made of non-magnetic material, such as for example a silicon balance spring or a balance spring made of a non-magnetic metal alloy (NbZr, NbTi, FeMn base, etc.) with its collet, also made of a non-magnetic metal alloy. Even more advantageously, the watch oscillator is made up solely of non-magnetic parts. For example, a balance wheel made of brass, a plate made of brass or nickel silver (alloy of copper, nickel and zinc), a corundum ellipse and a silicon balance spring can be provided.Also, the person skilled in the art may choose to combine the oscillator provided with an axis according to the invention with a non-magnetic escapement. For example, the anchor and / or the escape wheel may be made of non-magnetic NiP alloy or silicon.

[0016] According to one embodiment, the watch oscillator can be tested within a watch movement according to the following sequence: walking test in the 6 usual positions, exposure to an artificial magnetic field of 500 gauss, 1000 gauss or 5000 gauss for a predetermined time, walking test in the 6 usual positions, with a deviation of 20s / day maximum compared to the tests before exposure to magnetic fields, measurement of the stopping value under magnetic field, with at least 100 gauss, preferably at least 500 gauss, preferably at least 1000 gauss.

[0017] The non-magnetic intermetallic material is advantageously a binary material combining (i) two metals or (ii) a metal and a metalloid (B, Si, Ge, As, Sb, Te, At).

[0018] Generally speaking, an intermetallic material has an ordered structure, with a periodic alternation of the different atoms. Intermetallic alloys are distinguished from conventional alloys by the ordered nature of their atoms in the crystal lattice.

[0019] The non-magnetic intermetallic material of the watch axis is advantageously a binary material of formula M 1 < x M 2 < 1-x in which 0 <x<1 ; M 1< étant choisi dans le groupe constitué de :Au, Co, Cu, Fe, Ir, Mo, Ni, Pd, Pt et Zr ; M 2< étant choisi dans le groupe constitué de : Al, Ga, In, Si et Ti ; M 1< et M 2< étant différents l'un de l'autre.

[0020] The non-magnetic intermetallic material is advantageously chosen from the group consisting of: Au x Ti 1-x , Au x Al 1-x , Au x Ga 1-x , Au x In 1-x , Co x Si 1-x , Co x Al 1-x , Co x Ga 1-x , Cu x Ti 1-x , Fe x Al 1-x , Ir x Ti 1-x , Mo x A 1-x , Ni x Al 1-x , Ni x Ga 1-x , Ni x In 1-x , Ni x Si 1-x , Pd x In 1-x , Pd x Al 1-x , Pt x Al 1-x , Pt x Ga 1-x , Pt x In 1-x , Zr x Al 1-x , with 0 <x<1, et leurs mélanges.

[0021] Even more advantageously, the non-magnetic intermetallic material is chosen from the group consisting of: Au x Ti 1-x , Co x Al 1-x , Cu x Ti 1-x , Ir x Ti 1-x , Mo x Al 1-x , Ni x Al 1-x and Zr x Al -1x with 0 <x<1.

[0022] In the general formula M 1< x M 2< 1-x , x is advantageously equal to 0.6, 4 / 7, 2 / 3, 0.8, 0.25, 0.75, 0.5 or 1 / 3.

[0023] More advantageously, the non-magnetic intermetallic material is chosen from the group consisting of: binary intermetallics M 1< x M 2< 1-x with x=0.6 Cu 3 Ti 2 , binary intermetallics M 1< x M 2< 1-x with x= 4 / 7: Cu 4 Ti 3 , binary intermetallics M 1< x M 2< 1-x with x=2 / 3: Cu 2 Ti, binary intermetallics M 1< x M 2< 1-x with x=0.8: Cu 4 Ti, binary intermetallics M 1< x M 2< 1-x with x=0.25: AuTi 3 , IrTi 3 , , ZrAl 3 , binary intermetallics M 1< x M 2< 1-x with x=0.75: Mo 3 Al, Ni 3 Al, Co 3 Al, binary intermetallics M 1< x M 2< 1-x with x=0.5: CuTi, FeAl, CoAl, NiAl, CoGa, NiGa, PdIn, PdAl, NiIn, binary intermetallics M 1< x M 2< 1-x with x=1 / 3: CuTi 2, PtAl 2, AuAl 2, AuGa 2, AuInz, CoSi 2, NiSi 2, PtGa 2 and PtIn 2.

[0024] Preferably, the non-magnetic intermetallic material is chosen from AuTi3, Co 3 Al, Cu 4 Ti, IrTi 3 , Mo 3 Al and Ni 3 Al, ZrAl 3 , and mixtures thereof; more preferably from AuTi 3 , Cu 4 Ti, IrTi 3 , Mo 3 Al, Ni 3 Al, and mixtures thereof; and even more preferably from AuTi 3 , IrTi 3 , Mo 3 Al, and mixtures thereof.

[0025] The hardness of the intermetallic material is greater than 400 HV, preferably greater than 450 HV, more preferably greater than 600 HV.

[0026] The watch axis may be made of a non-magnetic intermetallic material or a mixture of non-magnetic intermetallic materials (advantageously a mixture of two non-magnetic intermetallic materials). In this case, the axis comprises 100% by mass of non-magnetic intermetallic material(s).

[0027] The watch axis may consist of a matrix comprising particles of non-magnetic intermetallic material(s), this matrix being a metal alloy matrix or a matrix of non-magnetic intermetallic material(s).

[0028] The particles of non-magnetic intermetallic material represent more than 20% by mass, advantageously more than 50% by mass compared to the mass of the watch axis.

[0029] The metal alloy matrix is advantageously made of an alloy of a metal chosen from: nickel, copper, aluminum, titanium, gold, platinum. This alloy is advantageously non-magnetic.

[0030] The particles of non-magnetic intermetallic material have a size advantageously between 0.1 µm and 10 µm, more advantageously between 1 µm and 5 µm.

[0031] Particle size is the largest dimension of a particle, for example, the diameter in the case of spherical particles. It can be measured using conventional techniques, for example, laser diffraction.

[0032] The use of at least two distinct materials to prepare the watch axis according to the invention can provide an improvement in hardness by synergy effect, and in the fineness of the microstructures, which reinforces the resistance of the watch axis. As mentioned above, it can be a mixture of two (or more) non-magnetic intermetallic materials (for example AuTi and Au 3 Ti), a mixture of a non-magnetic intermetallic material and a metal alloy matrix.

[0033] The present invention also relates to a method of preparing the watch axis.

[0034] According to a first embodiment, this method comprises the following steps: preparation of a bar by mixing and heating the metals constituting the non-magnetic intermetallic material, machining, advantageously by laser, grinding or electroerosion.

[0035] According to a second embodiment, this method comprises the following steps: preparation of a billet by mixing and heating the metals constituting the non-magnetic intermetallic material, reduction of the billet into powder of non-magnetic intermetallic material, sintering of the powder into bar or pre-form form, machining by laser or by grinding.

[0036] When the watch axis is made of a metal alloy matrix comprising particles of non-magnetic intermetallic material, the method comprises the following steps: preparing a billet by mixing and heating the metals constituting the non-magnetic intermetallic material, reducing the billet into particles of non-magnetic intermetallic material, mixing the particles of non-magnetic intermetallic material with a metal powder, sintering this mixture to form a metal alloy matrix comprising particles of non-magnetic intermetallic material, machining by laser or by grinding.

[0037] The machining is carried out according to the knowledge of the person skilled in the art who may in particular consult document CH715613 for laser machining.

[0038] When the watch axis is made of a metal alloy matrix comprising particles of non-magnetic intermetallic material, the metal powder is advantageously an alloy powder of a metal chosen from: nickel, copper, aluminum, titanium, gold, platinum.

[0039] Advantageously, the clock axis can be used for a non-magnetic oscillator, in combination with other non-magnetic components.

[0040] These non-magnetic components include, in particular, a spiral spring made of silicon, diamond, silicon oxide or the like; a non-magnetic metal spiral spring; a plate made of brass or other non-magnetic material; a balance wheel made of brass or other non-magnetic material. FIGURES

[0041] There figure 1 represents a watch axis, more precisely a balance wheel axis. EXAMPLES

[0042] Several watch axes were prepared from the non-magnetic intermetallic materials in Table 1, using conventional techniques. Table 1: Hardness of non-magnetic intermetallic materials used to prepare watch axes. Example Non-magnetic intermetallic material Hardness (HV) INV-1 AuTi 3 780 INV-2 Co 3 Al 400 INV-3 Cu 4 Ti 550 INV-4 IrTi 3 800 INV-5 Mo 3 Al 600 INV-6 Ni 3 Al 550 INV-7 ZrAl 3 430

Claims

1. Watch shaft comprising more than 20% by mass, relative to the mass of the watch shaft, of non-magnetic intermetallic material having a hardness greater than 400 HV, preferably greater than 450 HV, even more preferably greater than 500 HV.

2. Watch axis according to claim 1, characterized in that non-magnetic intermetallic material is a binary material, or a mixture of binary materials, a binary material combining (i) two metals or (ii) a metal and a metalloid.

3. Watch axis according to one of the preceding claims, characterized in that non-magnetic intermetallic material is a binary material, or a mixture of binary materials, with the formula M 1 x M 2 1-x , in which 0 <x<1, M 1 being selected from the group consisting of Au, Co, Cu, Fe, Ir, Mo, Ni, Pd, Pt and Zr; M 2 being chosen from the group consisting of Al, Ga, In, Si and Ti.

4. Watch axis according to one of the preceding claims, characterized in that non-magnetic intermetallic material is a binary material, or a mixture of binary materials, with the formula M 1 x M 2 1-x , in which x is equal to 0.6, 4 / 7, 2 / 3, 0.8, 0.25, 0.75, 0.5 or 1 / 3; M 1 being selected from the group consisting of Au, Co, Cu, Fe, Ir, Mo, Ni, Pd, Pt and Zr; M 2 being selected from the group consisting of Al, Ga, In, Si and Ti; M 1 and M 2 being different from each other.

5. Watch axis according to one of the preceding claims, characterized in that the non-magnetic intermetallic material is chosen from the group consisting of: Au x You 1-x , At x Al 1-x , At x Ga 1-x , At x In 1-x , Co x If 1-x , Co x Al 1-x , Co x Ga 1-x , Cu x You 1-x , Fe x Al1-x , Ir x You 1-x , Mo x HAS 1-x , Neither x Al 1-x , Neither x Ga 1-x , Neither x In 1-x , Neither x If 1-x , Pd x In 1-x , Pd x Al 1-x , Pt x Al 1-x , Pt x Ga 1-x , Pt x In 1-x , Zr x Al 1-x , and their mixtures, with 0 <x<1.

6. Watch axis according to one of the preceding claims, characterized in that the non-magnetic intermetallic material is chosen from the group consisting of: Au x You 1-x , Co x Al 1-x , Cu x You 1-x , Ir x You 1-x , Mo x Al 1-x , Neither x Al 1-x , Zr x Al -1x and their mixtures, with 0 <x<1.

7. Watch axis according to one of claims 1 to 5, characterized in thatthe non-magnetic intermetallic material is selected from the group consisting of: AuGa2, AuInz, AuAlz, AuTi3, CoAl, Co3Al, CoGa, CoSi2, CuTi, Cu2Ti, CuTi2, Cu3Ti2, Cu4Ti3, Cu4Ti, FeAl, IrTi3, Mo3Al, Ni3Al, NiAl, NiGa, NiIn, NiSi2, PdAl, PdIn, PtAl2, PtGa2, PtInz, ZrAl3 and mixtures thereof.

8. Watch axis according to one of the preceding claims, characterized in that the non-magnetic intermetallic material is selected from the group consisting of: AuTi3, Co3Al, Cu4Ti, IrTi3, Mo3Al, Ni3Al, ZrAl3, and mixtures thereof.

9. Watch axis according to one of the preceding claims, characterized in that the watch axis is made of one non-magnetic intermetallic material or two non-magnetic intermetallic materials.

10. Watch axis according to one of claims 1 to 8, characterized in thatthe watch axis consists of a matrix comprising particles of at least one non-magnetic intermetallic material, the matrix being made of a metal alloy or non-magnetic intermetallic material.

11. Watch axis according to claim 10, characterized in that the metal alloy matrix consists of an alloy of a metal chosen from: nickel, copper, aluminum, titanium, gold, platinum; the particles of non-magnetic intermetallic material having a size between 0.1µm and 10µm.

12. Watch axis according to one of the preceding claims, characterized in that the watch axis is a balance shaft.

13. Method of manufacturing the watch axis according to one of claims 1 to 11, comprising the following steps: - preparation of a bar by mixing and heating the different metals constituting the non-magnetic intermetallic material, - machining by laser or by grinding.

14. Method of manufacturing the watch axis according to claim 13, characterized in that the process comprises, between the preparation of the bar and the machining, the following steps: - reduction of the bar into powder of non-magnetic intermetallic material, - heat treatment of the powder.

15. Method of manufacturing the watch axis according to claim 13, characterized in that the method comprises, between the preparation of the bar and the machining, the following steps: - reduction of the bar into particles of non-magnetic intermetallic material, - mixing the particles of non-magnetic intermetallic material with a metal powder, - heat treatment of this mixture to form a metal alloy matrix comprising particles of non-magnetic intermetallic material.

Images