Micromechanical component, in particular a watch drive spring, in particular an escapement drive spring, with optimized contact surface

Description

Scope of the invention

[0001] The invention relates to a micromechanical component, in particular a watch movement with an optimized contact surface, in particular an escapement movement.

[0002] The invention further relates to a watch escapement mechanism comprising at least one non-magnetic moving part constituting an escape wheel or an anchor.

[0003] The invention relates to the field of watchmaking mechanisms, and more particularly to escapement mechanisms comprising at least one escape wheel and at least one anchor, of which at least one is non-magnetic. Background of the invention

[0004] In Swiss lever escapement mechanisms, the Swiss lever escape wheels are historically made of nickel-plated steel and are sensitive to magnetic fields. Document CH 514 873 A shows a nickel-plated metallic watch component.

[0005] We know of alternatives with materials such as nickel-phosphorus NiP12 implemented by the "LIGA" process (Lithography and Galvano-Abformung), which have a non-magnetic behavior.

[0006] However, the use of such materials, nickel-phosphorus or similar compounds, can be sensitive under certain climatic conditions, which may lead to performance degradation, particularly in terms of amplitude regularity, stopping, or aging, especially when the two opposing components of the friction couple are made of similar LIGA materials. The deposition of a superficial gold layer, while beneficial for stabilizing amplitude, does not solve the overall problem, may even exacerbate aging, and can affect running stability. Summary of the invention

[0007] The invention aims to solve the technical problem of the holding of the usual watch lubricant, and more particularly to guarantee an epilame effect, under usual climatic conditions, on components made of LIGA NiP12, or similar, non-ferromagnetic, in particular on Swiss lever escapement wheels.

[0008] For this purpose, the invention relates to a micromechanical component with an optimized contact surface, in particular a watch movement, in particular an escapement movement, according to claim 1.

[0009] The invention further relates to a clockwork escapement mechanism comprising at least one such moving part constituting an escape wheel or an anchor. Detailed description of preferred embodiments

[0010] The invention relates to the field of micromechanical components, and more particularly to watch movements.

[0011] The invention aims to solve in particular the technical problem of the holding of the usual watch lubricant, under usual climatic conditions, on components made of LIGA NiP12, or similar, non-ferromagnetic, in particular on wheels of a Swiss lever escapement mechanism.

[0012] The contact between the ruby ​​lever of the anchor and the tooth of the escape wheel is particularly sensitive.

[0013] This is particularly about preventing any contamination of the anchor, especially the anchor fork, and ensuring the presence of lubricant on the contact surfaces of the escape wheel and the anchor, and reducing the aging of the escape wheel and the anchor.

[0014] The main problem is the loss of epilame effect on the exhaust wheel board, which causes oil to spread and loss of lubrication at the contact between the wheel tooth and the ruby ​​lift.

[0015] The stability of the lubrication at the contact between the anchor levers and the escape wheel must ensure the consistency of the amplitude.

[0016] To this end, adding a layer of galvanic nickel (Ni), chemical nickel (e.g., NiP6-9), or chemically deposited nickel-boron to a LIGA NiP12 escape wheel significantly improves movement performance. Various tests have demonstrated that this notable improvement is linked to better resistance of the epilame under climatic conditions, particularly temperature and humidity, better adhesion of the epilame to the material when the amount of phosphorus on the surface is reduced, and improved lubricant performance when the phosphorus content is lower. Specifically, the tribological behavior of a pure nickel surface layer is superior to that of a NiP6-9 layer, which itself is superior to that of a NiP12 or NiP13 layer.

[0017] In one variant, the galvanic nickel coating can be an alloy, for example Ni-Fe, or Ni-W, or other.

[0018] Thus the invention relates to a micromechanical component, in particular a watch movement.

[0019] This component is advantageously produced by a watch movement manufacturing process, according to which a substrate is made with a first material comprising at least nickel and phosphorus, this substrate is shaped to the geometry of the movement, and the substrate is coated, by galvanic and / or chemical means, at the level of at least one surface of the substrate of the movement, with at least a second material of thin thickness, in particular less than 10 micrometers, which constitutes the peripheral layer of the movement at the level of this at least one surface of the substrate of the movement, and which comprises at least nickel and is poorer in phosphorus than the first material, or which comprises nickel and is devoid of phosphorus.

[0020] More specifically, this first material is non-magnetic.

[0021] More specifically, this second material is non-magnetic.

[0022] It is noted that nickel is not non-magnetic, and that NiP6-9% is not necessarily so; it is the thinness of the deposit that preserves the non-magnetic nature of the part.

[0023] According to the invention, the substrate is a nickel-phosphorus of NiPx formulation, with x between 1% and 15% by mass, inclusive of terminals, or more particularly with x between 10% and 15% by mass, inclusive of terminals, the latter range making it possible to guarantee the non-magnetic character of the coating.

[0024] This substrate is covered with a low-phosphorus coating, according to the invention, the thickness of which is more particularly and not limited to between 0.2 micrometers and 5.0 micrometers inclusive, and, more particularly still, between 0.2 micrometers and 2.0 micrometers inclusive.

[0025] The coating treatment with a low-phosphorus coating, according to the invention, can be carried out by galvanic means.

[0026] It is possible to apply a heat treatment to the substrate before the deposition operation, in particular galvanic, or to apply a heat treatment to the assembly formed by the substrate and its coating after the deposition operation, in particular galvanic.

[0027] It is also possible to apply a chemical treatment to the substrate to modify its surface characteristics in order to facilitate the adhesion of the coating, in particular by galvanic means.

[0028] Alternatively, the recoating treatment with a low-phosphorus coating, according to the invention, can be done chemically, according to a chemical nickel application process, which can be pure nickel, or a low-phosphorus nickel-phosphorus, for example NiP6-9, with 6% to 9% by mass of phosphorus, or even a nickel-boron NiB.

[0029] Adding a layer of nickel, or NiP6-9, or NiB, increases the stability of the epilame in climatic conditions, the grip of the epilame and therefore the resistance of any common watch lubricant.

[0030] More specifically, the epilame used is a fluoride-based formulation.

[0031] The lubricant can also be deposited on an exhaust valve with a supplement in the form of a paste based on molybdenum disulfide MoS2, which acts as a lubricant and lubricant sponge.

[0032] Advantageously, the escapement mechanism in question has a geometry that minimizes the contact surfaces; for example, preference is given to using a cradled anchor, which is an anchor whose active faces of the fork, intended to come into contact with the ellipse and the stops, are rounded, which allows for a point of contact instead of a line of contact.

[0033] An innovative design of an escapement mechanism includes an anchor made of LIGA, or an anchor whose pallets are at least made of LIGA. In such a case, the LIGA parts of the anchor are subject to the same problem, and the same solution is applicable.

[0034] The invention makes it possible to guarantee normal aging conditions, a constant amplitude, and the absence of stopping, particularly in the presence of cradled LIGA nickel-phosphorus anchors, which provide better shock resistance than silicon anchors, for example.

[0035] Thus, a preferred method is implemented for manufacturing such a micromechanical component, in particular a clockwork mechanism, according to which: a substrate is manufactured with a first material comprising at least nickel and phosphorus, and a coating is made on this substrate, at the level of at least one surface of the mobile substrate, with at least a second material which constitutes the peripheral layer of the mobile at the level of this at least one surface of the substrate; this at least a second material comprises at least nickel, and is poorer in phosphorus than the first material, or this at least a second material comprises nickel and is devoid of phosphorus.

[0036] More specifically, this coating of the substrate is applied, at least at one surface adjacent to a friction surface of the moving part, with at least one second material, which constitutes the peripheral layer of the moving part at the level of this at least one surface adjacent to a friction surface. By "adjacent" we mean that the two surfaces are contiguous, or at least tangent; their intersection is not empty, even if it is limited to an isthmus of very small cross-section.

[0037] Such a micromechanical component, particularly a watch movement, thus has an optimized contact surface.

[0038] This micromechanical component, and more particularly this clockwork mechanism, comprises a substrate made of a first material containing at least nickel and phosphorus. According to the invention, this substrate is coated, at at least one surface of the clockwork mechanism's substrate, with a coating of a second material containing at least nickel and less phosphorus than the first material, or containing nickel but being phosphorus-free, and the second material constitutes the peripheral layer of the clockwork mechanism at at least one surface of the substrate.

[0039] More specifically, the substrate coating covers the substrate on surfaces of the moving part other than the surfaces that guide the moving part for its pivoting or for its guidance along a single degree of freedom. More specifically still, the substrate coating covers the substrate on all surfaces of the moving part other than the guide surfaces.

[0040] More specifically, the substrate is coated, at at least one surface adjacent to a friction surface of the moving part, with a coating of a second material containing at least nickel and lower in phosphorus than the first material, or containing nickel but being phosphorus-free. This second material constitutes the peripheral layer of the moving part at at least one surface adjacent to a friction surface. More specifically, the substrate coating covers the substrate at surfaces adjacent to friction surfaces of the moving part other than the surfaces used to guide the moving part for pivoting or for guiding it along a single degree of freedom. More specifically still, the substrate coating covers the substrate at all surfaces adjacent to friction surfaces of the moving part other than the surfaces used to guide the moving part for pivoting or for guiding it along a single degree of freedom.Even more specifically, the substrate coating covers the substrate at all surfaces adjacent to the friction surfaces of the mobile, including the mobile's guide surfaces for pivoting or for guiding it according to a single degree of freedom.

[0041] More specifically, the substrate coating covers the substrate at all surfaces of the mobile, including the mobile's guide surfaces for pivoting or for guiding it according to a single degree of freedom.

[0042] More specifically, the first material consists solely of nickel and phosphorus.

[0043] According to the invention, the first material comprises phosphorus with a mass proportion of between 1% and 15%, inclusive. More particularly, the first material is non-magnetic and comprises phosphorus with a mass proportion of phosphorus between 10% and 15%, inclusive.

[0044] More specifically, the second material is chosen with a phosphorus mass proportion less than or equal to 15%. More specifically, the second non-magnetic material is chosen with a phosphorus mass proportion between 10% and 15%, inclusive.

[0045] In one alternative, the second material is chosen with a phosphorus mass content between 6% and 12% inclusive. In another alternative, the second material is chosen with a phosphorus mass content between 1% and 6% inclusive. In yet another alternative, the second material is chosen with a phosphorus mass content between 0% and 1% inclusive.

[0046] More specifically, the second material consists solely of nickel and phosphorus.

[0047] More specifically, the second material contains boron. More specifically still, the second material contains only nickel and boron.

[0048] More specifically, the second material is made of pure nickel.

[0049] More specifically, the second material has a thickness of less than 10 micrometers. More specifically still, the second material has a thickness of less than 5 micrometers. Even more specifically, the second material has a thickness between 0.2 micrometers and 2.0 micrometers inclusive.

[0050] In yet another variant, the second material is applied with a thickness between zero and 0.2 micrometers, excluding limits, particularly in the vicinity of 0.1 micrometers.

[0051] The invention further relates to a clockwork mechanism, in particular but not limited to an escapement mechanism. In this advantageous application, the clockwork escapement mechanism comprises at least one such moving part, constituting an escape wheel or an anchor. This moving part comprises a substrate made of a first material containing at least nickel and phosphorus, and the substrate of which is coated, at all surfaces adjoining the friction surfaces of the moving part, by a coating of a second material containing at least nickel and less phosphorus than the first material, or containing nickel and being devoid of phosphorus. The second material constitutes the peripheral layer of the moving part at the surfaces adjoining the friction surfaces that the moving part has to cooperate with an anchor, an escape wheel, or a balance wheel.

Claims

1. A horology mobile comprising a substrate made of a first material comprising at least nickel and phosphorus, with a proportion by mass of phosphorus comprised between 1% and 15%, limits included, said substrate being covered, on at least one surface, by a plating of a second material comprising at least nickel and lower in phosphorus than said first material, or comprising nickel and being phosphorus-free, and in that said second material constitutes a peripheral layer of said mobile on said at least one surface of the substrate of said mobile.

2. The mobile according to claim 1, characterised in that said substrate is covered, on at least one surface adjoining a friction surface of said mobile, by a plating made of said second material, which constitutes the peripheral layer of said mobile on said at least one surface adjoining a friction surface of said mobile.

3. The mobile according to claim 1, characterised in that said first material is non-magnetic and comprises phosphorus with a proportion by mass of phosphorus comprised between 10% and 15%, limits included.

4. The mobile according to any of claims 1 to 3, characterised in that said first material only comprises nickel and phosphorus.

5. The mobile according to any of claims 1 to 4, characterised in that said second material is non-magnetic and comprises a proportion by mass of phosphorus comprised between 10% and 15%, limits included.

6. The mobile according to any of claims 1 to 4, characterised in that said second material comprises a proportion by mass of phosphorus comprised between 6% and 12%, limits included.

7. The mobile according to any of claims 1 to 4, characterised in that said second material comprises a proportion by mass of phosphorus comprised between 1% and 6%, limits included.

8. The mobile according to any of claims 1 to 4, characterised in that said second material comprises a proportion by mass of phosphorus comprised between 0% and 1%, limits included.

9. The mobile according to claim 8, characterised in that said second material is phosphorus-free.

10. The mobile according to any of claims 1 to 4, characterised in that said second material only comprises nickel and phosphorus.

11. The mobile according to any of claims 1 to 9, characterised in that said second material comprises boron.

12. The mobile according to any of claims 1 to 4, characterised in that said second material only comprises nickel and boron.

13. The mobile according to any of claims 1 to 4, characterised in that said second material is made of pure nickel.

14. The mobile according to any of claims 1 to 13, characterised in that said second material has a thickness of less than 10 micrometres.

15. The mobile according to claim 14, characterised in that said second material has a thickness of less than 5 micrometres.

16. The mobile according to claim 15, characterised in that said second material has a thickness comprised between 0.2 micrometre and 2.0 micrometres, limits included.

17. A horological escapement mechanism comprising at least one mobile according to any of claims 1 to 16, constituting an escapement wheel or a pallet, characterised in that said mobile comprises the substrate with the first material comprising at least nickel and phosphorus, and in which said substrate is covered, on all the surfaces adjoining friction surfaces of said mobile, by the plating of the second material comprising at least nickel and lower in phosphorus than said first material, or comprising nickel and being phosphorus-free, and in that the said second material constitutes the peripheral layer of said mobile on said surfaces adjoining friction surfaces comprised in said mobile for engaging with a pallet or an escapement wheel or a balance.