IMPROVED CLOCK COMPONENT

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a component such as a micromechanical part or a decorative part of a timepiece. TECHNICAL BACKGROUND OF THE INVENTION

[0002] Watch movements, particularly mechanical ones, use a lot of parts that rub against each other, which leads to energy losses and even wear, even in the presence of lubricant.

[0003] Therefore, micromechanical parts with the best possible tribological properties are constantly sought.

[0004] Document WO2015 / 039152A1 discloses the manufacture of jewelry pieces comprising coatings made of an alloy of copper (55%), tin (39%) and zinc (6%). SUMMARY OF THE INVENTION

[0005] The aim of the invention is to propose a new type of material for a component, for example a timepiece, allowing improved tribological properties, in particular by offering an improved coefficient of friction and wear resistance.

[0006] For this purpose, the invention relates to a component of a watch movement, this component being defined in claim 1.

[0007] According to the invention, it has been found that such a ternary alloy combines a certain number of advantages. Thus, it has been found that the coefficient of friction and the wear resistance of such an alloy are particularly interesting, in particular compared to nickel-based or nickel-phosphorus materials currently used in watchmaking. In addition, although it may contain a majority of copper, it has a metallic gray appearance offering an advantageous aesthetic, elastic characteristics (such as the modulus of elasticity and the elastic limit) and a surprisingly high hardness for a copper-based alloy. In addition, such an alloy has a very low magnetic susceptibility, that is to say that it is very little sensitive to magnetic fields. Finally, this alloy is stainless. It is therefore understood that the alloy implemented according to the invention has all the qualities for a watchmaking application.

[0008] The alloy is preferably of the galvanic type in order to improve its hardness. In fact, it has been found that this same alloy has a lower hardness when it is manufactured using another process.

[0009] Finally, although it contains a majority of copper, the alloy offers a metallic gray appearance providing advantageous aesthetics.

[0010] The invention may also include one or more of the following optional features, taken alone or in combination.

[0011] The proportion of majority copper is between 50 and 85%, the proportion of intermediate tin is between 10 and 40% and the proportion of minority zinc is between 2 and 15% and, preferably, the proportion of majority copper is between 55 and 65%, the proportion of intermediate tin is between 25 and 40% and the proportion of minority zinc is between 4 and 10%.

[0012] According to a first variant, the proportion of majority copper is substantially equal to 65%, the proportion of intermediate tin is substantially equal to 30% and the proportion of minority zinc is substantially equal to 5%. According to a second variant, the proportion of majority copper is substantially equal to 60%, the proportion of intermediate tin is substantially equal to 30% and the proportion of minority zinc is substantially equal to 10%. According to a third variant, the proportion of majority copper is substantially equal to 57%, the proportion of intermediate tin is substantially equal to 39% and the proportion of minority zinc is substantially equal to 4%.

[0013] Typically, the thickness of the component may, for example, be between 10 µm and 1 mm and, preferably, between 100 µm and 800 µm.

[0014] According to a first embodiment, the component is entirely formed from the aforementioned alloy. It is therefore understood that the component can be obtained for example by electroforming. In fact, the entire outer surface of the component is formed from the alloy.

[0015] According to a second embodiment, the component according to the invention is formed by at least one part at least partially coated with the aforementioned alloy. It is therefore understood that the component can be obtained by an over-thickness deposition of the alloy, for example by electroplating, on all or part of the previously manufactured part. In fact, the part can be only partially or totally coated with the alloy based on copper, tin and zinc.

[0016] According to a third embodiment, the component is mainly formed from the aforementioned alloy, for example by electroforming. The alloy is at least partially coated with a material other than the alloy. It is therefore understood that the component can be obtained by an over-thickness deposition of a material other than the alloy, for example by electroplating or vapor deposition, on all or part of the previously manufactured alloy. In fact, the alloy based on copper, tin and zinc can be only partially or completely coated, with a material other than the alloy based on copper, tin and zinc.

[0017] Furthermore, the invention relates to a timepiece comprising at least one component, characterized in that the component is as described above. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features and advantages of the invention will become clear from the description given below, for information purposes only and in no way limiting, with reference to the appended drawings, in which: There Figure 1 is a schematic view of a timepiece according to the invention; The Figure 2 is a perspective view of a component according to the invention; The Figure 3A is a sectional view of a first embodiment according to plane III-III of the Figure 2 ; There Figure 3B is a sectional view of a first variant of a second embodiment according to plane III-III of the Figure 2 ; There Figure 3C is a sectional view of a second variant of the second embodiment according to plane III-III of the Figure 2 . DETAILED DESCRIPTION OF AT LEAST ONE EMBODIMENT OF THE INVENTION

[0019] By "timepiece" we mean all types of instruments for measuring or counting time such as clocks, pendulum clocks and watches.

[0020] By "watch movement" we mean all types of mechanism capable of counting time, whether powered by mechanical energy (for example a barrel) or electrical energy (for example a battery).

[0021] By "micromechanical part" we mean all types of parts that can be used in a watch, particularly to form its watch movement.

[0022] By "dressing" we mean all types of devices capable of containing, displaying, decorating and / or controlling a watch movement such as, for example, all or part of a case, a bracelet or a display.

[0023] In the following, unless otherwise indicated, all percentages (%) indicated are percentages by total mass or weight.

[0024] The invention relates to a component 1 for a timepiece 11. Such a component 1 can thus be a micromechanical part or a casing part 13. More precisely, the component 1 according to a variant not belonging to the invention can form all or part of a casing such as all or part of a dial, a display such as a hand or a disc, a case, a bracelet, a crystal or a control member such as a crown or a push button. According to the invention, component 1 forms all or part of a watch movement such as all or part of an escapement device such as a Swiss anchor mechanism, a resonator such as a balance-spring mechanism, an energy source such as a barrel, an automatic winding system or a battery, a gear train such as a mobile or a toothed wheel, a spring, a screw, a bridge or a plate.

[0025] Without limitation, component 1 may form an element of a cog (such as a toothed wheel 3 at the Figure 2 ) in particular finishing (replacement in particular of a rhodium-plated part), a plate, a bridge, a winding system, an escapement, a case 15 or a barrel (replacement in particular of a nickel-plated part). For example, component 1 can form a tenon guiding the return wheels or a winding pinion of a manual winding system, a winding wheel or an axis (for example eccentric) of an automatic winding system, an axis (for example of a balance wheel, wheel or wheel), a pull, a sliding pinion or a pinion of a time-setting system or a screw. Finally, component 1 could also form a mechanism part such as a cam, a jumper, a star, a finger, a spring or a screw.

[0026] Preferably, the component 1 is an active part, that is to say a part intended to transmit a movement and, incidentally, intended to undergo friction with another part. Indeed, the invention proposing to improve the tribological properties of the component 1, it preferentially targets a component 1 which is in contact at least temporarily during its movement with another element.

[0027] Advantageously according to the invention, component 1 comprises an alloy 5 based on copper, tin and zinc allowing improved tribological properties.

[0028] Indeed, it has been found that such an alloy 5 combines a certain number of advantages. Thus, it has been found that such an alloy 5 has an improved coefficient of friction and wear resistance, particularly compared to nickel-based or nickel-phosphorus materials currently used in watchmaking. In addition, although it may contain a majority of copper, it has a metallic gray appearance offering an advantageous aesthetic, elastic characteristics (such as the modulus of elasticity and the elastic limit) and a surprisingly high hardness for a copper-based alloy. In addition, such an alloy 5 has a very low magnetic susceptibility, that is to say that it is very little sensitive to magnetic fields. Finally, this alloy 5 is stainless. The alloy 5 according to the invention is therefore particularly advantageous for an application, particularly in watchmaking.

[0029] According to a first embodiment, not forming part of the claimed subject matter, component 1 is entirely formed from alloy 5 as illustrated in the examples of Figures 2 and 3A . It is therefore understood that component 1 can be obtained for example by electroforming (manufacturing a mold followed by filling the mold by electrolytic deposition), by autocatalytic deposition (in English "electroless plating") or vapor deposition (physical or chemical). Such a component 1 can therefore replace solid parts, that is to say, for example, parts having a thickness E 1 of between 10 µm and 1 mm and, preferably, between 100 µm and 800 µm, usually based on steel, nickel or one of its alloys, CuBe or brass while providing all the advantages of alloy 5 explained above.

[0030] According to a second embodiment, the component 1 according to the claimed invention is formed by at least one part 7 at least partially coated with the alloy 5 as illustrated in the examples of Figures 2, 3B and 3C . It is therefore understood that the component 1 can be obtained by an over-thickness deposition of the alloy 5, that is to say for example a thickness E 2 of between 0.1 µm and 10 µm, preferably between 0.3 µm and 5 µm, and, even more preferably, between 0.5 µm and 2 µm, on all or part of the part 7 previously manufactured, for example by electroplating (electrolytic deposition), by autocatalytic deposition or by vapor deposition (physical or chemical). Such a coating of alloy 5 can therefore be deposited on a part 7 not usually coated or as a replacement for a coating usually used, for example based on nickel or one of its alloys such as nickel-phosphorus, gold or rhodium.

[0031] In a first variant of the second embodiment illustrated in the Figure 3B , alloy 5 is present only at the periphery of the toothed wheel 3 in order to improve the tribological properties of the teeth 4. In fact, at least another part of the outer surface of the component 1 is therefore not formed from alloy 5. Of course, alloy 5 could be present on more or less of the face of the component 1. Thus, in a second variant of the second embodiment illustrated in Figure 3C , alloy 5 completely covers part 7 in order to improve the qualities of the entire component 1.

[0032] According to a third embodiment (not claimed and not illustrated because it is substantially the opposite of the second embodiment), the component 1 is mainly formed from the alloy 5 based on copper, tin and zinc, for example by electroforming. The alloy 5 is at least partially coated with a material other than the alloy based on copper, tin and zinc. It is therefore understood that the component 1 can be obtained by an over-thickness deposition of a material other than the alloy 5, for example by electroplating (electrolytic deposition), by autocatalytic deposition or by vapor deposition (physical or chemical), on all or part of a previously manufactured part made of alloy 5. In fact, the part made of alloy 5 based on copper, tin and zinc can be only partially or totally coated with a material other than the alloy 5 based on copper, tin and zinc.

[0033] The coating material may be metallic (e.g. gold or rhodium) or non-metallic (e.g. silicon or carbon such as diamond or DLC) in order to allow, for example, the passage and / or fixing of a shaft, an aesthetic improvement (roughness, color, etc.) or a technical improvement (hardness, tribology, etc.). As for the second embodiment, the coating in the third embodiment has, for example, a thickness E 2 of between 0.1 µm and 10 µm and, preferably, between 0.3 µm and 5 µm and, even more preferably, between 0.5 µm and 2 µm.

[0034] Whatever the embodiment, alloy 5 preferably comprises a majority proportion of copper as a percentage of the total mass of alloy 5, a minority proportion of zinc as a percentage of the total mass of alloy 5 and a proportion of tin, intermediate between the proportion of copper and the proportion of zinc, as a percentage of the total mass of alloy 5. Thus, although it comprises a majority of copper, alloy 5 has a metallic gray appearance offering an advantageous aesthetic, elastic characteristics (such as the modulus of elasticity and the elastic limit) and a surprisingly high hardness for a copper-based alloy.

[0035] Preferably, the proportion of majority copper is between 50 and 85%, the proportion of intermediate tin is between 10 and 40% and the proportion of minority zinc is between 2 and 15% and even more preferably, the proportion of majority copper is between 55 and 65%, the proportion of intermediate tin is between 25 and 40% and the proportion of minority zinc is between 4 and 10%.

[0036] Alloy 5 is preferably of the galvanic type, i.e. obtained from electroplating, in order to improve its hardness. Typically, a hardness of between 400 and 700 HV 0.01, more particularly at least equal to 550 HV 0.01, can be obtained from a galvanic deposit of alloy 5, this hardness being intrinsic, i.e. obtained without any particular hardening treatment. A heat treatment can make it possible to further improve the hardness of the alloy. On the other hand, it has been found that this same alloy 5 has a significantly lower hardness when it is manufactured using a process other than electroplating. However, any method of manufacturing such a ternary alloy 5 can be considered in view of its qualities.

[0037] For comparison, a galvanically obtained nickel-phosphorus alloy has a hardness of around 600 HV 0.01, a modulus of elasticity of around 148 GPa and an elastic limit of around 1900 MPa.

[0038] According to a first variant, the proportion of majority copper is approximately equal to 65%, the proportion of intermediate tin is approximately equal to 30% and the proportion of minority zinc is approximately equal to 5%. This first variant, with the same tests as for the nickel-phosphorus alloy, made it possible to obtain characteristics similar to the nickel-phosphorus alloy.

[0039] According to a second variant, the proportion of majority copper is substantially equal to 60%, the proportion of intermediate tin is substantially equal to 30% and the proportion of minority zinc is substantially equal to 10%. This second variant, with the same tests as for the nickel-phosphorus alloy, made it possible to obtain a hardness of 675 HV 0.01, a modulus of elasticity of 161 GPa and an elastic limit of 2207 MPa. It is understood that this second variant has better characteristics than a nickel-phosphorus alloy.

[0040] According to a third variant, the proportion of majority copper is approximately equal to 57%, the proportion of intermediate tin is approximately equal to 39% and the proportion of minority zinc is approximately equal to 4%. This third variant, with the same tests as for the nickel-phosphorus alloy, made it possible to obtain a hardness of 640 HV 0.01, a modulus of elasticity of 160 GPa and an elastic limit of 2090 MPa. It is understood that this third variant has better characteristics than a nickel-phosphorus alloy.

[0041] The invention is not limited to the embodiments and variants presented and other embodiments and variants will become clear to those skilled in the art. Thus, other compounds may enter into the composition of alloy 5 without departing from the scope of the invention to allow, for example, greater stability or greater hardness such as, for example, carbon, silicon or manganese. In addition, other compounds may enter into the composition as impurities, that is to say in proportions less than or equal to 0.5% of the total mass of alloy 5.

[0042] Optionally, at least one adhesion layer may be deposited between the part 7 and the alloy 5 of the component 1 to facilitate its attachment. Each adhesion layer, for example based on chromium, nickel or gold, may thus act as an attachment element to avoid in particular delamination between the part 7 and the alloy 5 of the component 1. Of course, with or without an adhesion layer, the surface of the part 7 or of the alloy 5 of the component 1 may be cleaned or prepared in another way before any deposition to facilitate its attachment.

[0043] Furthermore, depending on the applications, component 1 can be used with or without lubricant to further improve its tribological qualities.

Claims

1. Component (1) of a timepiece movement for a timepiece (11), formed by at least one part (7), the part (7) being at least partially coated by an alloy (5) of galvanic type or autocatalytic deposition type based on copper, tin and zinc, the alloy (5) comprising a majority proportion of copper as a percentage of the total weight of the alloy (5), a minority proportion of zinc as a percentage of the total weight of the alloy (5) and an intermediate proportion of tin between the proportion of copper and the proportion of zinc as a percentage of the total weight of the alloy (5) providing improved tribological properties.

2. Component (1) according to the preceding claim, wherein the majority proportion of copper is between 50 % and 85 %, the intermediate proportion of tin is between 10 % and 40 % and the minority proportion of zinc is between 2 % and 15 %.

3. Component (1) according to the preceding claim, wherein the majority proportion of copper is between 55 % and 65 %, the intermediate proportion of tin is between 25 % and 40 % and the minority proportion of zinc is between 4 % and 10 %.

4. Component (1) according to the preceding claim, wherein the majority proportion of copper is substantially equal to 65 %, the intermediate proportion of tin is substantially equal to 30 % and the minority proportion of zinc is substantially equal to 5 %.

5. Component (1) according to claim 4, wherein the majority proportion of copper is substantially equal to 60 %, the minority proportion of zinc is substantially equal to 10 % and the intermediate proportion of tin is substantially equal to 30 %.

6. Component (1) according to claim 4, wherein the majority proportion of copper is substantially equal to 57 %, the minority proportion of zinc is substantially equal to 4 % and the intermediate proportion of tin is substantially equal to 39 %.

7. Component (1) according to any one of the preceding claims, whose thickness (E1) is between 10 µm and 1 mm.

8. Component according to one of the preceding claims, wherein the part (7) is completely coated by the alloy (5) based on copper, tin and zinc.

9. Timepiece (11) comprising at least one component (1), characterised in that the component (1) is according to one of the preceding claims.