Method for manufacturing parts based on several precious metals, and parts obtained

Abstract

The present invention relates to a method for manufacturing mechanical parts based on at least two precious metals or noble metals or alloys thereof, the method comprising the steps of atomizing various precious metals, placing the resulting powders in a mold so as to form an assembly of unmixed powders, and sintering at a temperature below the melting temperature of the metals used. The present invention also covers mechanical parts manufactured by such a method, as well as timepieces containing such mechanical parts.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a timepiece component based on a precious metal or noble metal or an alloy thereof, which involves atomizing several precious metals or noble metals or alloys of such metals into separate powders and then jointly subjecting them to a sintering operation, particularly SPS (spark plasma sintering), also known as flash sintering. Various precious metals or noble metals can be distinguished from each other in the resulting timepiece component. This specification also covers timepiece components made of several distinct precious metals, as well as timepieces comprising such components.

Background Art

[0002] The principle of sintering metal powder materials is well-known and is often used to manufacture metal alloys. Document EP3766997 (Patent Document 1), for example, describes the formation of precious metal alloys using such a process. However, such alloys require homogenizing or at least mixing the powders. Such processes cannot produce components with different local compositions from each other.

[0003] Document EP3822712 (Patent Document 2) shows an example of a process for designing components for timepieces using metal powders. The metals involved in said process are not limited to precious metals or noble metals and include, for example, stainless steel or aluminum. Therefore, the sintering conditions are not suitable for manufacturing components made of precious metals that are separately distributed in the final part.

[0004] Document EP2728422 (Patent Document 3) describes the manufacture of a bimetallic component including a base to which a cover plate is welded. This process requires at least partial melting of the metals involved. This process is further restricted by the use of metal plates that limit the variety of effects obtained.

[0005] In document CH715336 (Patent Document 4), the focus is on the production of two-color components with distinct boundaries between colors. To achieve this, sub-assemblies of amorphous materials of different colors must be manufactured separately and then assembled under stress. This process requires meticulous machining operations to assemble the sub-assemblies, as well as joining elements that act as ornaments.

[0006] Sintering technology is an alternative to soldering or welding, which has the advantage of limiting or avoiding the addition of materials at the interface and the mixing of the materials involved. It also enables the production of monolithic parts. However, this process has not yet penetrated precious metals. Therefore, there is room to develop a process specifically adapted to precious materials, which would enable a wider range of applications and assemblies.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0008] One of the objectives of the present invention is to propose a method that is particularly suitable for precious metals and their alloys and enables the production of metal parts, such as watch components, in which the various metals are distinguishable from one another. In particular, the method described herein proposes to assemble different precious metals without mixing them. Furthermore, the method proposes to avoid locally modifying the composition during the production of the parts.

[0009] Another objective of the present invention is to produce monolithic or monoblock mechanical parts, particularly watch components, comprising or consisting of two or more precious metals or precious metal alloys that are distinguishable from one another. In particular, such mechanical parts or watch components preferably do not have a concentration gradient at the interfaces of the various components, or have a minimal concentration gradient, for example, over a thickness of less than 10 micrometers, or less than 5 micrometers, or less than 1 micrometer. The terms "monolithic" or "monobloc" are used to indicate a part composed of a single block, i.e., it is not the result of the assembly of pre-manufactured sub-assemblies.

Means for Solving the Problems

[0010] According to the present invention, these objectives are achieved in particular by the method and components that are the subject of the independent claims, the details of which are the subject of the dependent claims.

[0011] In particular, this solution offers an advantage over the prior art in producing watch components based on precious metals that have specific aesthetic appearances and / or mechanical properties due to the local distribution of the various metals that make them up. In particular, local variations in color and / or hardness can be generated directly in the mass of the component without additional steps. In particular, the parts produced in this way are monoblock, making the parts more resistant and / or easier to manufacture.

Brief Description of the Drawings

[0012] Embodiments of the present invention are shown in the description given by the following drawings: · Figure 1: A method according to an embodiment of the present invention. · Figure 2: A method according to another embodiment of the present invention. · Figure 3: A schematic diagram of a post-release step that may be involved in the method according to the present invention.

[0013] Detailed Description of the Invention The methods described herein are shown in Figures 1 and 2. In a first step S1, one material M1 that constitutes a mechanical part is atomized into a first powder P1. As used herein, the term "atomizing / atomize" refers to any suitable operation for changing the material under consideration into a powder. This can consist of or can include a grinding step. The resulting powder may be composed of particles of various powder degrees. For example, the particles may be micrometer-sized with an average diameter in the range of 1 μm to 500 μm, or 10 to 100 μm. Alternatively, the particles may be sub-micrometer-sized, i.e., having an average diameter of less than 1 micrometer.

[0014] The average particle size of the powder can be adapted according to the material to be obtained and / or the result.

[0015] This process includes step S2 for atomizing a second material M2 to produce a second powder P2. The atomization conditions may be the same as or different from the conditions for atomizing the first material M1. The average particle size forming the second powder P2 may be the same as or similar to the average particle size forming the first powder P1. Alternatively, different particle sizes can be achieved for the first P1 and second P2 powders. It will be understood that the atomization steps of the first M1 material and the second M2 material are carried out separately from each other so as to obtain distinguishable powders P1, P2. In particular, the method according to the invention does not include any mixing step of these first P1 powder and second P2 powder. More specifically, the method according to the invention includes all measures for not mixing the first P1 powder and the second P2 powder. The first M1 material and the second M2 material can also be atomized at different positions so as to avoid or limit contamination from one to the other. Devices for tracing or tracking different materials and powders can also be provided. According to these configurations, the method can include steps for separate packaging, tracing and separate storage of the materials and / or powders.

[0016] The atomization step for the first material M1 can be carried out in parallel with or sequentially to the atomization step for the second material M2.

[0017] According to one embodiment, one or more of the materials used in the method of the invention can be directly selected in powder form, as a result of which the corresponding atomization steps S1, S2, Si described herein are not necessary.

[0018] Both the first M1 material and the second M2 material are selected from precious metals or noble metals, or alloys based on such precious metals or noble metals.

[0019] The precious metals or noble metals according to this specification include gold (Au), silver (Ag), platinum (Pt), palladium (Pd), rhodium (Rh), scandium (Sc), ruthenium (Ru), osmium (Os) and iridium (Ir). In particular, noble metals refer to corrosion-resistant metals. In the context of this specification, the terms "precious" and "noble" are interchangeable and equivalent, so both of these terms refer to the metals listed above.

[0020] In the context of this specification, alloys of these precious metals contain at least 50% by mass, or at least 80% by mass or more, or even at least 95% by mass of one or a combination of these precious metals. The alloys according to this specification can include a mixture of gold and silver and can form at least 50% by mass, or 80% by mass or more of mechanical parts. This does not exclude forming alloys by combining more than two precious metals. In certain embodiments, the alloy can consist only of a combination of two or more of the precious metals listed above.

[0021] According to one embodiment, the alloy according to the present invention contains one or more of the precious metals listed above and one or more other non-precious metals, such as copper, tin, aluminum, zinc, titanium or nickel.

[0022] The different materials M1, M2 can refer to different alloys based on the same precious metal. For example, the first material M1 may represent a first gold alloy and the second material M2 may represent a second gold alloy. One or both of the first M1 material and the second M2 material may be selected, for example, from the following gold alloys: - White gold: 75% gold, 19% copper, 6% silver, - White gold: 75% gold, 25% palladium or 25% nickel, - Red gold: 75% gold, 25% copper, - Pink gold: 75% gold, 20 percent copper, 5 percent silver, - Green gold: 75% gold, 25% silver.

[0023] All 18ct gold alloys from 1N to 5N can be considered as different materials M1, M2 and can be assembled in the same piece. Other gold alloys can be considered as necessary. Furthermore, various alloys based on precious metals other than gold, such as alloys based on platinum or alloys based on palladium, can be considered.

[0024] Precious metals can be used independently of each other in different amounts, for example 9ct, 12ct, 18ct or 24ct, or other amounts.

[0025] The first M1 material and the second M2 material are characterized by their respective melting temperatures T1, T2. For example, the melting temperature of gold at atmospheric pressure is about 1064 °C. The melting temperature of gold alloys is generally higher than this value. The melting temperature of palladium is about 1554 °C, the melting temperature of platinum is about 1768 °C, the melting temperature of rubidium is about 39 °C, the melting temperature of scandium is about 1541 °C, the melting temperature of rhodium is about 1964 °C, the melting temperature of iridium is about 2446 °C, the melting temperature of ruthenium is about 2333 °C, and the melting temperature of osmium is about 3033 °C.

[0026] The method according to this specification includes step S3 of placing the first P1 powder and the second P2 powder in the sintering mold 2. The first P1 powder and the second P2 powder are arranged sequentially so as not to be mixed. They can each form a powder bed, or a powder deposit, or be arranged in different arrangements, for example, in a line, or in a geometric pattern or a random pattern. Depending on the requirements, one or more of the first P1 powder and the second P2 powder, and any additional Pi powder (see below) can be repeatedly used, for example, alternately with other powders, to form several clusters, or several lines, or several layers.

[0027] In one embodiment, the powder can be subjected to vibration or any other operation to make the powder denser or more uniformly distributed, if necessary. Here, if they are performed, it is necessary to ensure that the first P1 powder and the second P2 powder do not mix during these operations.

[0028] The first P1 powder and the second P2 powder can be used in equal amounts in various ratios, for example, so that the final mechanical part contains the same amount of the first material M1 as the second material M2 regardless of their distribution. The M1 / M2 ratio of the first M1 material and the second M2 material can vary, for example, from 10 / 90 to 90 / 10 or from 20 / 80 to 80 / 20. Of course, ratios between 30 / 70 and 70 / 30, or between 40 / 60 and 60 / 40 are also possible.

[0029] The combination of powders forms an assembly A of unmixed powders. The first P1 powder and the second P2 powder are in contact with each other, but each remains localized at a specific point determined when placed in the mold 2.

[0030] The method described herein does not exclude the use of a powder mixture for manufacturing an in-situ alloy. For example, in addition to the first powder P1 and the second powder P2, a third powder consisting of a combination of the first powder P1 and the second powder P2, or other powders, may be added. Under these conditions, the third powder corresponds to a precious metal or noble metal alloy as defined herein.

[0031] Once the assembly A of unmixed powders is produced, it is subjected to sintering in step S4. The sintering conditions include a sintering temperature Tfri. They also include a sintering pressure Pfri, which can be a mechanical pressure.

[0032] The sintering temperature Tfri is determined such that none of the powders in the powder assembly A melt under the sintering conditions. The appropriate sintering temperature Tfri can be evaluated as a function of the sintering pressure Pfri such that it does not reach, or exceed, or remain below the melting temperatures T1 and T2 of the first M1 material and the second M2 material at the sintering pressure Pfri. Preferably, the sintering temperature is determined to remain below the lowest of the melting temperatures T1, T2 of the first M1 material and the second M2 material under the sintering conditions. It is understood that the sintering temperature varies according to the first and second materials used and / or their alloys. In this case, the sintering temperature is defined in relation to the physical properties of the materials involved.

[0033] Preferably, the sintering conditions are those of flash sintering, also known as SPS (spark plasma sintering). The use of electrodes for heating the non-mixed powder assembly A allows for a very short heating time and retains the powder fineness of the particles.

[0034] In one embodiment, the sintering temperature Tfri is less than 2000 °C, or further less than 1500 °C, or further less than 1000 °C. For example, the sintering temperature is between 600 °C and 1600 °C.

[0035] The sintering pressure Pfri is between 20 and 180 N / mm 2 up to, or between 50 and 100 N / mm 2 up to. Depending on the components selected and / or the required quality of the final mechanical parts, other pressure values may also be preferred.

[0036] When sintering is complete, a solid part B is obtained from the assembly of powder A. The solid part B is heterogeneous and thus locally contains different compositions corresponding to the first M1 material and the second M2 material used, respectively. Thus, the local compositions can, independently of each other, correspond to pure precious metals or specific precious metal alloys.

[0037] After the solid component B is obtained, in order to recover the released solid component C, it is released in step S5.

[0038] The released solid component C may correspond to the final component. However, the released component C may require one or more subsequent operations to improve its quality or aesthetic appearance, or to modify the obtained component to obtain the final component 1. The adjustment step S6 can be used, for example, to change the size of the released solid component C. The machining step S7 can be performed to modify the solid component C, resulting in one or more holes, or grooves, or protrusions, or any other ablation of the material. Machining can be performed by any suitable technique, whether mechanical, laser, water jet, or equivalent. One or more finishing steps S8 can also be envisaged. If necessary, other post-sintering transformations can be brought about.

[0039] The method has been described above using two materials, but this in no way precludes the use of more than two, for example three or more, in the same or similar configurations as those already described. Figure 2 shows a method in which additional material Mi is used and atomized into additional powder Pi in an additional atomization step Si. The additional material(s) Mi are different from the first M1 material and the second M2 material. However, they are selected from the precious metals or noble metals described above, or combinations thereof. The obtained additional powder(s) Pi are processed and handled under the conditions already described for the first P1 powder and the second P2 powder. In particular, appropriate measures are taken to ensure that they do not mix with other powders. The additional material(s) can be selected directly in powder form. In this case, the corresponding atomization step(s) may not be necessary.

[0040] The first P1 powder, the second P2 powder, and one or more additional Pi powders, which are separately arranged in a mold so as to form an assembly of at least three non-mixed A' powders, are subjected to a sintering operation under the necessary conditions so as to obtain a solid part B' including a first M1 material, a second M2 material, and one or more additional Mi materials, which are distinguishable from each other but combined. The temperature and pressure conditions for sintering are those already described for the assembly of at least two powders A. In particular, the sintering temperature Tfri is set so that none of the first M1 material, the second M2 material, or the additional Mi materials melts during sintering. The solid part B' can be demolded to obtain a demolded solid part C'. As shown in FIG. 3, one or more of the above-described post-demolding operations S6, S7, S8 can be performed.

[0041] According to one embodiment, other materials, such as pigments, may be added to any of the first P1 powder, the second P2 powder, and the additional Pi powders. Such additives, if present, are preferably in an amount of less than 5% by weight, or even less than 1% by weight.

[0042] Accordingly, the parts obtained from the method described herein are manufactured by a single sintering operation, even though they contain several materials or alloys. This method has the advantage of being simple and easy. In this case, the assembly step of the different subassemblies often required for this type of component is omitted. The boundaries of the colors and geometric patterns also remain distinct and clear. In particular, the concentration gradient at the joints of different materials is limited to zero or less than 10 micrometers or less than 5 micrometers, or even less than 1 micrometer. The patterns generated are implemented directly on the mass of the component. The pattern is understood herein to mean any change in color or shade, any two-dimensional or three-dimensional shape obtained from the mass of the component, or any other visual and / or aesthetic or decorative appearance. The pattern coincides with the interfaces of the various materials of the component. Due to local composition changes, these patterns can be accompanied by local changes in mechanical properties, especially in terms of hardness.

[0043] This document also covers a mechanical part 1 manufactured according to the method described above. In particular, this is a metal part based on at least two precious metals or noble metals or their alloys, or at least three precious metals or noble metals or their alloys. In the context of this document, a part based on a precious metal or noble metal contains one or more precious metals or noble metals for at least half of its mass. According to one embodiment, the mechanical part contains one or more precious metals or noble metals, or their alloys, for 80% or more of its mass, or for 95% or more of its mass. The various precious metals or noble metals of such parts are distinguishable from one another. In this way, the mechanical part 1 can be characterized by the different color characteristics of the different precious metals or noble metals that make it up. Patterns such as a camouflage effect or a geometric pattern can also be produced. Alternatively, or additionally, it can be characterized by different local mechanical properties specific to the different precious metals or noble metals that make it up.

[0044] The distribution of various precious metals or noble metals in mechanical parts is not limited. Different precious metals and noble metals can be distributed in the superposed layers, or in the clusters within the mechanical parts, or in any other configuration determined during their manufacture. One of the precious metals or noble metals can remain completely hidden from view, especially when it forms the core or inner part of the part and is covered by another precious metal or noble metal. Nevertheless, the boundary lines of the different materials within the piece remain distinct and clear. The resulting visual effect is of the highest quality.

[0045] Thus, the mechanical part 1 according to the present specification includes at least a first material M1 and a second material M2 that form an inseparable unity, such as a monolithic body or a monoblock body, where the at least first material M1 and the second material M2 are in a distinguishable state from each other. In addition to the first M1 material and the second M2 material, the mechanical part 1 may include one or more other additional materials Mi that are different from the first M1 material and the second M2 material and are distinguishable from other materials. The first M1 material, the second M2 material, and any additional material Mi are selected from one of the above-mentioned precious metals or noble metals or their alloys.

[0046] The mechanical part 1 can be, for example, a clock component, such as a gear train or any other part of a clock movement. Alternatively, the mechanical part 1 is an ornament component or a decorative component. It can be, for example, a clock case or a dial, or any other element visible to the user. In this regard, the mechanical part 1 fully enjoys the advantages of the above method, which is particularly suitable for combining different precious metals within a single part, and thus produces a wide variety of aesthetic effects.

Example

[0047] Example 1 Stack the first 5N 18ct gold powder and the second 2N 18ct gold powder continuously within the SPS sintering mold. Perform sintering at a temperature of 800 °C and a pressure of 100 MPa, and demold the obtained pellet to form a watch case. Since all materials are 18ct, the resulting case middle is also 18 ct.

[0048] Example 2 Stack the first 18ct 5N gold powder and the second 18ct yellow gold powder continuously within the SPS sintering mold. Place the third 950 / 1000 platinum powder on top of the first two powders. Perform sintering at a temperature of 860 °C and a pressure of 130 MPa, demold the obtained pellet, and machine it into a bezel. The part is then finished by decorating it with a 950 / 1000 platinum surface layer that is softer than the lower layer. The final part is not titrated.

[0049] Example 3 Randomly distribute the first 18ct 5N gold powder, the second 18ct 2N gold powder, and 18ct gray gold powder within the SPS sintering mold to form powder clusters. Perform sintering at a temperature of 790 °C and a pressure of 80 MPa. Demold the obtained pellet to produce a bezel with yellow, pink, and gray camouflage patterns. Since all materials are 18ct, the final piece is also 18ct.

[0050] Reference numbers used in the drawings 1 Mechanical part M1 First material M2 Second material Mi Additional material(s) P1 First powder P2 Second powder Pi Additional powder(s) S1 Atomization step of the first material Si Atomization step of the additional material S2 Atomization step of the second material Step of placing S3 powder in the mold S4 Sintering step S5 Demolding step S6 Adjustment step S7 Machining step S8 Finishing step

Claims

1. A method for manufacturing a watch component (1) based on at least two types of precious metals or alloys of precious metals, which are distinguished from each other, and which contain at least 50% by mass or at least 80% by mass of these metals and / or alloys, - A first material (M1) in the form of a first powder (P1), wherein the first material (M1) has a first melting temperature (T1) at atmospheric pressure. - A second material (M2) in the form of a second powder (P2), wherein the second material (M2) has a second melting temperature (T2) at atmospheric pressure. - and optionally, one or more additional materials (Mi) different from the first material (M1) and the second material (M2), the one or more additional materials (Mi) in the form of an equal number of corresponding additional powders (Pi), - Step S3, placing the material in powder form into a mold (2) to form an assembly (A, A') of at least two types of unmixed powders, wherein the powders are in contact with each other. - Step S4, sintering under conditions that produce solid parts (B, B') from the assembly (A, A') of unmixed powders. - Step S5: Demold the solid parts (B, B') to obtain demolded parts (C, C'). In a manufacturing method that includes selecting, The first material, the second material, and the additional material refer to the precious metal or noble metal, or an alloy of the precious metal or noble metal, contained in the watch component, and the sintering is a flash or SPS type sintering operated at a sintering temperature (Tfri) and a sintering pressure (Pf), wherein the sintering temperature (Tfri) and sintering pressure (Pfri) are determined so that none of the materials melt, and as a result the watch component obtained has no concentration gradient of components at their interfaces or has a concentration gradient at a thickness of less than 10 micrometers, the manufacturing method.

2. The method according to claim 1, wherein the first material, the second material, and additional materials (M1, M2, Mi) are selected from gold (Au), silver, platinum (Pt), palladium (Pd), osmium (Os), and alloys thereof.

3. The method according to claim 1, wherein the alloy comprises at least 50% by mass, or at least 80% by mass or more, or at least 95% by mass or more of a precious metal or noble metal, or a combination of precious metals or noble metals.

4. The method according to claim 1, wherein the powders are arranged in step S4 such that they independently form one or more alternating clusters, rows, or layers.

5. The method according to claim 1, wherein one or more of the first powder, the second powder, and the additional powders (P1, P2, Pi) include one or more additives.

6. The method according to claim 1, wherein the sintering temperature (Tf) is between 600°C and 1600°C.

7. The sintering pressure (Pfri) is 20 N / mm ２ From 180 N / mm ２ The method according to claim 1, wherein the mechanical pressure is between [times].

8. The method according to claim 1, further comprising one or more of the following steps: S1 atomizing the first material (M1) to produce the first powder (P1); S2 atomizing the second material (M2) to produce the second powder (P2); and S2 atomizing the additional material to produce a corresponding powder (Pi) (may be multiple types).

9. To obtain the aforementioned clock component, follow these steps: - Step S6, adjusting the demolded solid parts (C, C') to a desired thickness. - Step S7, machining the molded solid parts (C, C') - Step S8 to finish the demolded solid parts (C, C'), The method according to claim 1, further comprising one or more of the following.

10. A metal watch component comprising at least two materials selected from a first material (M1), a second material (M2), and optionally one or more additional materials (Mi), wherein the at least two materials form a monoblock assembly, in the monoblock assembly, the first material, the second material, and the additional materials (M1, M2, Mi) are distinct from each other, and the interface of the at least two materials has no concentration gradient or has a concentration gradient over a thickness of less than 10 micrometers such that the interface of the at least two materials results in a clear and distinct distinction of the materials, and the first material, the second material, and the additional materials (M1, M2, Mi) form a pattern in the mass of the component, the materials are selected from the group of precious metals or noble metals and their alloys, and the pattern corresponds to the interface of the materials, the metal watch component.

11. The metal clock component according to claim 10, wherein the pattern includes one or more of local color changes, local hue changes, two-dimensional shapes, three-dimensional shapes, and combinations thereof.

12. The metal clock component according to claim 11, wherein the one or more local color or hue changes are three-dimensional.

13. The metal watch component according to claim 10, wherein the concentration gradient of the at least two materials is zero, or reduced to a thickness of less than 10 micrometers, less than 5 micrometers, or less than 1 micrometer.

14. A metal watch component according to claim 10, obtained by the method according to any one of claims 1 to 9.

15. A metal clock component according to claim 10, which is a decorative finish or a movement component.

16. A clock comprising the clock component described in any one of claims 10 to 13.

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