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 clockwork mechanism with an optimized surface, in particular an escapement mechanism.

[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 escapement wheels are historically made of nickel-plated steel, and are sensitive to magnetic fields.

[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, can prove sensitive in certain climatic conditions, which are likely to lead to a degradation of performance, particularly in terms of amplitude regularity, stops, or even aging, especially when the two antagonistic components of the friction couple are made of similar LIGA materials.

[0007] Document WO 2008 / 052 378 A2 discloses the example of a watch part made of a material containing nickel and phosphorus, and coated on the surface with another material. Summary of the invention

[0008] 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.

[0009] For this purpose, the invention relates to a micromechanical component whose surface is optimized, in particular a watch movement, in particular an escapement movement, according to claim 1.

[0010] 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

[0011] The invention relates to the field of micromechanical components, and more particularly to watch movements.

[0012] 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.

[0013] In Swiss lever escapement mechanisms, the contact between the ruby ​​lever of the anchor and the tooth of the escape wheel is particularly sensitive, as is the contact between the fork and the pallet fork pin or between the fork and the anchor stops.

[0014] This is particularly important to ensure the presence of lubricant on the contact surfaces between the escape wheel and the anchor, and to reduce the aging of the escape wheel and the anchor.

[0015] 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.

[0016] The stability of the lubrication at the contact between the anchor levers and the escape wheel must ensure the consistency of the amplitude.

[0017] To this end, the addition of a coating in the form of a layer of galvanic nickel (Ni) preferably, or of chemical nickel (for example NiP6-9), or even of nickel-boron deposited by chemical means, on a LIGA NiP12 escape wheel greatly improves the performance of the movements.

[0018] Indeed, various tests have demonstrated that this significant improvement is linked to better adhesion of the epilame under predetermined climatic conditions, for example at 50° Celsius and a humidity level of 90%. The inventors observed better adhesion of the epilame to the material when the amount of phosphorus on the surface is reduced; consequently, the lubricant's performance is all the better as the amount of phosphorus decreases.

[0019] In one variant, the galvanic nickel coating can be an alloy, for example Ni-Fe, or Ni-W, or other.

[0020] Thus the invention relates to a micromechanical component, in particular a watch movement.

[0021] 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 a peripheral layer of the movement at the level of this at least one surface of the substrate of the movement, and which comprises only nickel and boron.

[0022] More specifically, this first material is non-magnetic.

[0023] More specifically, this second material is non-magnetic. More precisely, it exhibits a non-magnetic character.

[0024] 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 gives the part its non-magnetic character.

[0025] In a particular embodiment, the substrate is a nickel-phosphorus of NiPx formulation, with x between 1% and 15% by mass, or more particularly with x between 10% and 15% by mass, the latter range making it possible to guarantee the non-magnetic character of the coating.

[0026] In an unclaimed manner, the coating covering the substrate is low in phosphorus and its thickness is not limited to between 0.2 micrometers and 10.0 micrometers, and, more particularly, between 0.2 micrometers and 2.0 micrometers.

[0027] Preferably, the coating has a thickness of 0.5 micrometers.

[0028] The coating treatment with a low-phosphorus coating, according to the invention, can be carried out by galvanic means.

[0029] 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.

[0030] 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.

[0031] In an unclaimed alternative, the recoating treatment with a low or zero 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.

[0032] Adding a layer of nickel, or NiP6-9, or NiB, increases the stability of the epilame in all climatic conditions, the grip of the epilame and therefore the resistance of any common watch lubricant.

[0033] More specifically, the epilame used is a fluoride-based formulation.

[0034] 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.

[0035] 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 pallet fork pin and the stops, are rounded, which allows for a point of contact instead of a line of contact.

[0036] 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.

[0037] 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.

[0038] 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 a peripheral layer of the mobile at the level of this at least one surface of the substrate; this at least a second material comprises only nickel and boron.

[0039] 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 a second material, which constitutes a 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.

[0040] Such a micromechanical component, particularly a watch movement, thus has an optimized surface area.

[0041] 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 only nickel and boron, and the second material constitutes the peripheral layer of the clockwork mechanism at at least one surface of the substrate.

[0042] 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.

[0043] More specifically, the substrate is covered, at the level of at least one surface adjoining a rubbing surface of the mobile, by a coating of a second material comprising only nickel and boron, and the second material constitutes the peripheral layer of the mobile at the level of at least one surface adjoining a rubbing surface.

[0044] More specifically, the coating covers the substrate at the level of at least one surface adjoining friction surfaces of the mobile other than the guiding surfaces of the mobile for its pivoting or for its guidance along a single degree of freedom.

[0045] More specifically, the substrate coating covers the substrate at all surfaces adjacent to the friction surfaces of the mobile other than the surfaces guiding the mobile for its pivoting or for its guidance according to a single degree of freedom.

[0046] 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.

[0047] 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.

[0048] More specifically, the first material consists solely of nickel and phosphorus.

[0049] More specifically, the first material contains phosphorus with a mass proportion between 1% and 15%. More specifically still, the first material is non-magnetic and contains phosphorus with a mass proportion between 10% and 15%.

[0050] More specifically, and in a manner not claimed, 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%.

[0051] In an unclaimed alternative, the second material is chosen with a phosphorus mass content between 6% and 12%. In another unclaimed alternative, the second material is chosen with a phosphorus mass content between 1% and 6%. In yet another unclaimed alternative, the second material is chosen with a phosphorus mass content less than or equal to 1%.

[0052] More specifically, and in an unclaimed manner, the second material consists solely of nickel and phosphorus.

[0053] More specifically, the second material contains boron. According to the invention, the second material contains only nickel and boron.

[0054] More specifically, and in an unclaimed manner, the second material consists of pure nickel.

[0055] The coating has a thickness of less than 10 micrometers. More specifically, the coating has a thickness of less than 5 micrometers. Even more specifically, the coating has a thickness between 0.2 micrometers and 2.0 micrometers.

[0056] Preferably, the coating thickness is 0.5 micrometers.

[0057] In yet another variant, the coating is applied with a thickness of less than 0.2 micrometers, specifically in the vicinity of 0.1 micrometers.

[0058] The invention also 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, for example, formed by an escape wheel or an anchor.

[0059] This mobile comprises a substrate made of a first material comprising at least nickel and phosphorus, the substrate being covered, at the level of all surfaces adjoining the rubbing surfaces of the mobile, by a coating made of a second material comprising only nickel and boron.

[0060] The second material constitutes the peripheral layer of the mobile at the level of the surfaces adjoining the friction surfaces that the mobile has to cooperate with an anchor or an escape wheel or a balance wheel.

[0061] The moving part can advantageously receive a lubricating substance on its friction surfaces, for example, a synthetic oil or grease suitable for precision microtechnical applications, familiar to watchmakers. Such a lubricating substance can be combined with a paste based on molybdenum disulfide (MoS2).

[0062] The mobile can also advantageously receive a layer of epilame on at least one surface of the coating other than its friction surfaces in order to allow better adhesion of the lubricating substance.

Claims

1. A horology mobile comprising a substrate made of a first material comprising at least nickel and phosphorus, characterised in that said substrate is covered, on at least one of its surfaces, by a plating made of a second material comprising only nickel and boron, 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 or 2, characterised in that said first material comprises phosphorus with a proportion by weight comprised between 1% and 15%.

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

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

6. The mobile according to any of claims 1 to 5, characterised in that said second material has a thickness of less than 10 micrometres.

7. The mobile according to claim 6, characterised in that said second material has a thickness comprised between 0.2 micrometres and 2.0 micrometres.

8. A horological escapement mechanism comprising at least one mobile according to any of claims 1 to 7, constituting an escapement wheel or a pallet.

9. The mechanism according to claim 8, comprising a lubricating substance on the friction surfaces of the mobile.

10. The mechanism according to claim 9, comprising an epilame layer on at least one surface of the plating other than its friction surfaces.