Micromechanical component, surface-optimized horological movement and escapement

Abstract

The invention relates to a micromechanical component, in particular a timepiece movement, in particular an escapement wheel, comprising a base material made of a first material comprising at least nickel and phosphorus, which base material is covered on at least one surface of the base material of the movement by a coating of a second material comprising at least nickel and having a lower phosphorus content or no phosphorus than the first material, and said second material constitutes an outer peripheral layer of the movement at the at least one surface of the base material.

Description

TECHNICAL FIELD

[0001] The invention relates to a micromechanical component, in particular a surface-optimized horological movement piece, in particular an escapement wheel.

[0002] The invention also relates to a horological escapement mechanism comprising at least one non-magnetic movement piece constituting an escapement wheel or an escapement lever.

[0003] The invention relates to the field of horological mechanisms, more particularly to an escapement mechanism comprising at least one escapement wheel and at least one escapement lever, at least one of the escapement wheel and the escapement lever being non-magnetic. BACKGROUND

[0004] In Swiss lever escapement mechanisms, Swiss lever escapement wheels have traditionally been made of nickel-plated steel, these escapement wheels being sensitive to magnetic fields.

[0005] Alternatives are known materials such as nickel-phosphorus alloys (NiP12) achieved by the "LIGA" (lithography, electroforming and injection molding) method, such materials having a non-magnetic behavior.

[0006] However, the use of such materials, nickel-phosphorus or similar materials, can become sensitive under certain climatic conditions, which can lead to performance degradation, in particular in terms of amplitude regularity, stop or aging, in particular when the two antagonistic components of the friction torque are produced in similar LIGA materials. SUMMARY

[0007] The invention aims to solve the technical problem of the resistance of a commonly used horological lubricant on a component made of LIGA NiP12 or similar non-ferromagnetic material, in particular a Swiss lever escapement wheel, under common climatic conditions, in particular the technical problem of guaranteeing an oil diffusion-proof effect.

[0008] To this end, the invention relates to a horological movement piece, in particular an escapement wheel, comprising a base made of a first material comprising at least nickel and phosphorus, characterized in that said base is covered on at least one surface of this base of the movement piece by a coating of a second material comprising at least nickel and less phosphorus than said first material, and in that said second material constitutes an outer peripheral layer of said movement piece at said at least one surface of this base of the movement piece, said second material being non-magnetic and comprising between 10% and 15% by weight of phosphorus.

[0009] The invention also relates to a horological escapement mechanism comprising at least one such movement piece constituting an escapement wheel or an escapement lever. DETAILED DESCRIPTION

[0010] The invention relates to the field of micromechanical components, more particularly to horological movement pieces.

[0011] The invention proposes to solve the technical problem of the resistance of usual watch lubricants on a component made of LIGA NiP12 or similar non-ferromagnetic material under usual climatic conditions, especially on a Swiss lever escapement.

[0012] In a Swiss lever watch escapement, the contact between the ruby gathering-pallet of the pallet fork and the teeth of the escape wheel is particularly sensitive, as is the contact between the prongs and the disc pegs or the prongs and the pallet fork stop pin.

[0013] In particular, this concerns ensuring the presence of a lubricant on the contact surface between the escape wheel and the pallet fork, and reducing the ageing of the escape wheel and the pallet fork.

[0014] The main problem is the loss of the oil diffusion barrier effect on the base plate of the escape wheel, which leads to oil diffusion and lubricant loss at the contact between the teeth of the escape wheel and the ruby gathering-pallet.

[0015] The stability of the lubricant at the contact between the gathering-pallet in the pallet fork and the escape wheel must be able to guarantee the amplitude consistency.

[0016] To this end, the addition of a coating in the form of a layer of electroplated nickel (Ni) or chemical nickel (such as NiP6-9) or chemically deposited nickel boron on the escape wheel made of LIGA NiP12 can greatly improve the performance of the movement.

[0017] Indeed, various tests have shown that this significant improvement is linked to better resistance of the oil diffusion barrier under predetermined climatic conditions (for example at 50 degrees Celsius and 90% humidity level). The inventors have observed better adhesion of the oil diffusion barrier on the material when the amount of phosphorus on the surface is reduced, and therefore, the resistance of the lubricant is even better when the amount of phosphorus is low.

[0018] In a variant, the electroplated nickel coating can be an alloy, such as Ni-Fe or Ni-W or other alloys.

[0019] The invention therefore concerns a micromechanical component, in particular a watch movement.

[0020] The component is advantageously producible by a method for manufacturing a watch movement, according to which a base material comprising at least a first material containing nickel and phosphorus is produced, which is shaped into the geometry of the movement, and said base material is coated by electroplating and / or chemically with at least one second material in a low thickness, in particular less than 10 microns, on at least one surface of the base material of the movement, which constitutes an outer peripheral layer of the movement at this at least one surface of the base material of the movement, and which contains at least nickel and a lower content of phosphorus than the first material, or contains nickel but no phosphorus.

[0021] More particularly, the first material is non-magnetic.

[0022] More particularly, the second material is non-magnetic. More particularly, it has non-magnetic properties.

[0023] It should be noted that nickel is not non-magnetic, whereas NiP6-9% is not necessarily so, it is the low thickness of the deposit which confers the non-magnetic properties of the piece.

[0024] In one particular embodiment, the base material is nickel-phosphorus of formula NiPx, with x between 1% and 15% by weight, or more particularly x between 10% and 15% by weight, the latter range making it possible to guarantee the non-magnetic properties of the coating.

[0025] The coating covering the base material has a low phosphorus content, with a thickness of between, but not limited to, 0.2 microns and 10.0 microns, more particularly between 0.2 microns and 2.0 microns.

[0026] Preferably, the thickness of the coating is 0.5 microns.

[0027] According to the invention, the coating treatment with a coating having a low phosphorus content can be performed in an electroplating manner.

[0028] A heat treatment can be applied to the base material, in particular the electroplating, before the deposition operation, or also to the assembly formed by the base material and its coating, after the deposition operation, in particular the electroplating.

[0029] A chemical treatment can also be applied to the base material to modify its surface features, thus facilitating the attachment of the coating, in particular in an electroplating manner.

[0030] Alternatively, according to a method for applying a chemical nickel, which can be pure nickel, or nickel-phosphorus with a low phosphorus content, for example NiP6-9 with 6% to 9% phosphorus by weight, or nickel-boron NiB, the coating treatment using a coating with a low or zero phosphorus content according to the invention can be performed in a chemical manner.

[0031] The addition of a layer of nickel or NiP6-9 or NiB can improve the stability of the anti- spreading agent under all climatic conditions, the attachment of the anti-spreading agent and thus the resistance to any usual watch lubricant.

[0032] More particularly, the anti-spreading agent used is a fluorine-based formulation.

[0033] The lubricant can also be deposited on the escapement wheel and supplemented in the form of a paste based on molybdenum disulfide MoS2 acting as a lubricant and a lubricant sponge.

[0034] Advantageously, the escapement concerned has a geometry that enables the contact surface to be minimized, for example by preferentially using a rounded pallet, the working face of the pallet head of which intended to come into contact with the pin of the disc and the stop pin being rounded, which makes it possible to have points of contact rather than lines of contact.

[0035] One innovative embodiment of the escapement comprises a pallet made from LIGA, or at least a pallet stone of a pallet made from LIGA. In this case, the LIGA-made part of the pallet encounters the same problem and the same solution can be applied.

[0036] The invention makes it possible to guarantee normal aging conditions, consistency of amplitude and elimination of stalling, in particular in the presence of a rounded LIGA nickel-phosphorus pallet, for example, which ensures better shock resistance than a silicon pallet.

[0037] Thus, in a preferred manner, a method for manufacturing such a micromechanical component, in particular a timepiece movement, is implemented according to which:

[0038] - a base material is manufactured from a first material comprising at least nickel and phosphorus, and

[0039] - the base material is coated with at least one second material on at least one surface of the base material of the movement, the second material constituting an outer peripheral layer of the movement at the at least one surface of the base material;

[0040] - the at least one second material comprises at least nickel and a lower amount of phosphorus than the first material, or the at least one second material comprises nickel but no phosphorus.

[0041] More particularly, the base material is coated with the at least one second material on at least one surface that adjoins a friction surface of the movement, the at least one second material constituting an outer peripheral layer of the movement at the at least one surface that adjoins the friction surface. By "adjoins", it is meant that the two surfaces are continuous, or at least tangent, their point of intersection not being empty, even if it is limited to a very small cross section in a narrow portion.

[0042] Such a micromechanical component, in particular a timepiece movement, thus comprises an optimized surface.

[0043] The micromechanical component, more particularly the timepiece movement, comprises a base material made from a first material comprising at least nickel and phosphorus. According to the invention, the base material is covered with a coating of a second material on at least one surface of the base material of the movement, the second material comprising at least nickel and less phosphorus than the first material, or no phosphorus, and the second material constituting an outer peripheral layer of the movement at the at least one surface of the base material.

[0044] More particularly, the coating of the substrate covers the substrate on at least one surface adjoining a friction surface of the moving part.

[0045] More particularly, the substrate is covered by a coating of a second material on at least one surface adjoining a friction surface of the moving part, the second material comprising at least nickel and having less phosphorus than the first material, or no phosphorus, and the second material constituting an outer peripheral layer of the moving part at the at least one surface adjoining the friction surface.

[0046] More particularly, the coating covers the substrate on at least one surface adjoining a friction surface of the moving part other than a guide surface of the moving part for its pivoting or for its guidance according to a single degree of freedom.

[0047] More particularly, the coating of the substrate covers the substrate on all surfaces adjoining a friction surface of the moving part other than a guide surface of the moving part for its pivoting or for its guidance according to a single degree of freedom.

[0048] More particularly, the coating of the substrate covers the substrate on all surfaces adjoining a friction surface of the moving part comprising a guide surface of the moving part for its pivoting or for its guidance according to a single degree of freedom.

[0049] More particularly, the coating of the substrate covers the substrate on all surfaces of the moving part comprising a guide surface of the moving part for its pivoting or for its guidance according to a single degree of freedom.

[0050] More particularly, the first material comprises only nickel and phosphorus.

[0051] More particularly, the first material comprises phosphorus in a weight ratio of between 1% and 15%. More particularly, the first material is non-magnetic and comprises phosphorus in a weight ratio of between 10% and 15%.

[0052] More particularly, the second material is chosen with a weight ratio of phosphorus less than or equal to 15%. More particularly, the second non-magnetic material is chosen with a weight ratio of phosphorus of between 10% and 15%.

[0053] In one alternative, the second material is chosen with a weight ratio of phosphorus of between 6% and 12%. In another alternative, the second material is chosen with a weight ratio of phosphorus of between 1% and 6%. In yet another alternative, the second material is chosen with a weight ratio of phosphorus less than or equal to 1%.

[0054] More particularly, the second material comprises only nickel and phosphorus.

[0055] More particularly, the second material comprises boron. More particularly, the second material comprises only nickel and boron.

[0056] More particularly, the second material is made of pure nickel.

[0057] The thickness of the coating is less than 10 microns. More particularly, the thickness of the coating is less than 5 microns. More particularly, the thickness of the coating is between 0.2 microns and 2.0 microns.

[0058] Preferably, the thickness of the coating is 0.5 microns.

[0059] In yet another variant, a coating having a thickness less than 0.2 microns, in particular around 0.1 microns, is applied.

[0060] The application also relates to a timepiece movement, in particular but not exclusively an escapement. In this advantageous application, the timepiece escapement comprises at least one such moving piece, for example formed by an escape wheel or an escape fork.

[0061] The moving piece comprises a base material made of a first material comprising at least nickel and phosphorus, the base material being covered on all the surfaces adjoining the friction surfaces of the moving piece by a coating made of a second material comprising at least nickel and less phosphorus than the first material or no phosphorus.

[0062] The second material constitutes an outer peripheral layer of the moving piece at the surface adjoining the friction surfaces comprised in the moving piece to cooperate with the escape fork or the escape wheel or the balance.

[0063] The moving piece can advantageously receive on its friction surfaces a lubricating substance, for example an oil or a synthetic grease suitable for precision micro-engineering applications known to the person skilled in the art of horology. This lubricating substance can be combined with a paste based on molybdenum disulfide MoS2.

[0064] The moving piece can also advantageously receive on at least one surface of the coating other than the friction surfaces of the moving piece a layer of an oil diffusion inhibitor in order to give the lubricating substance better resistance.

Claims

1. A timepiece movement comprising a base material made of a first material comprising at least nickel and phosphorus, characterized in that, The substrate is covered on at least one surface of the substrate of the moving piece by a coating of a second material, which contains at least nickel and less phosphorus than the first material, and which constitutes an outer peripheral layer of the moving piece at the at least one surface of the substrate of the moving piece, the second material being non-magnetic and containing phosphorus in a weight percentage between 10% and 15%.

2. The moving element according to claim 1, characterized in that The substrate is covered on at least one surface adjoining a friction surface of the moving piece by a coating of the second material, which coating constitutes an outer peripheral layer of the moving piece at the at least one surface adjoining a friction surface of the moving piece.

3. The moving element according to claim 1, characterized in that The first material is non-magnetic and comprises phosphorus in a weight percentage between 10% and 15%.

4. The moving element according to claim 1, characterized in that The first material contains only nickel and phosphorus.

5. The moving element of claim 1, wherein The thickness of the second material is less than 10 microns.

6. The moving element according to claim 5, characterized in that The thickness of the second material is between 0.2 microns and 2.0 microns.

7. A timepiece movement comprising a base made of a first material comprising at least nickel and phosphorus, said base being covered on at least one surface of the base of the movement by a coating of a second material comprising at least nickel and less phosphorus than the first material, and said second material constituting an outer peripheral layer of the movement at said at least one surface of the base of the movement, characterized in that, The second material contains phosphorus in a weight percentage equal to 1%.

8. A timepiece escapement comprising at least one element according to claim 1, said element constituting an escape wheel or an escape pinion, characterized in that, The moving piece comprises a substrate made of a first material containing at least nickel and phosphorus, and wherein the substrate is covered on all surfaces adjoining a friction surface comprised in the moving piece by a coating of a second material, which contains at least nickel and less phosphorus than the first material, and wherein the second material constitutes an outer peripheral layer of the moving piece at the surfaces adjoining a friction surface comprised in the moving piece, to cooperate with an escape fork or an escape wheel or a balance wheel.

9. The mechanism according to claim 8, comprising a lubricating substance on the friction surface of the moving piece.

10. The mechanism according to claim 9, comprising a layer of an oil-diffusion-preventing agent on at least one surface of the coating other than the friction surface of the moving piece.