CH720499A2 - One-piece dial in precious metal based on at least two gold alloys for a timepiece - Google Patents

Abstract

The invention relates to a single-piece dial made of precious metal (10) based on at least two gold alloys, characterized in that it comprises a first part (11), called structural, made of a first gold alloy having at least 350‰ by weight of gold and a second part (12), called aesthetic, partially or completely covering the first part (11), the second part (12) being made of a second gold alloy having at least 350‰ by weight of gold of a composition different from the first gold alloy; the two parts (11, 12) being inseparable. The invention also relates to a method for manufacturing such a single-piece dial made of precious metal based on at least two gold alloys.

Description

Technical field

[0001] The present invention relates to a single-piece dial made of titratable precious metal based on at least two gold alloys for a timepiece, in particular for a wristwatch.

[0002] The invention also relates to a method of manufacturing such a single-piece dial made of precious metal based on at least two gold alloys.

State of the art

[0003] Conventionally, dials for timepieces are solid, single-piece parts generally manufactured by machining in the base material of the dial, such as stone, precious or non-precious metal, or ceramic, to obtain the desired three-dimensional shape, and finished with a decoration operation to obtain the desired aesthetic effects.

[0004] In the particular case of metal dials, the manufacture of the dials usually requires steps of machining, deformation and/or cutting of the metal base material.

[0005] The base material once shaped is then decorated during a decoration or finishing operation which may include engraving, guilloche, and/or enameling operations. This is why the metallic base material of the dial is generally in the annealed state before carrying out these decoration and finishing operations, in order to minimize the hardness of the metallic alloy of the base material of the dial and thus facilitate the carrying out of these finishing and decoration steps.

[0006] However, these annealing states of certain alloys, and in particular precious metal alloys, give rise to problems of shock resistance.

[0007] In the particular case of solid gold dials (in particular for dials that can be titrated or titrated at 18K or more), their significant mass and the poor mechanical properties of the gold alloys used accentuate this problem of shock resistance, because these solid gold dials can easily deform during shocks. The poor mechanical properties of gold alloys can also be problematic during dial assembly operations.

[0008] This is accentuated when using solid gold dials having a specific color with little or no copper whose mechanical properties can be very low (hardness less than 100Hv in the annealed state).

Summary of the invention

[0009] In this context, the invention aims to propose a single-block dial made of titratable precious metal based on at least two gold alloys making it possible to remedy at least one of the drawbacks described above.

[0010] The dial according to the invention makes it possible to have a titratable gold dial comprising both the required aesthetic properties (specific color) while preserving sufficiently high mechanical characteristics to withstand shocks (hardness greater than 100Hv in the annealed state).

[0011] For this purpose, the invention proposes a single-piece dial made of precious metal based on at least two gold alloys, characterized in that it comprises a first part, called the structural part, made of a first gold alloy having at least 350‰ by weight of gold and a second part, called the aesthetic part, partially or completely covering the first part, the second part being made of a second gold alloy having at least 350‰ by weight of gold and having a composition different from the first gold alloy; the two parts being inseparable.

[0012] Preferably, the second part completely covers the first part.

[0013] Thus, thanks to the invention, it is possible to obtain a solid dial in titratable gold (having a title at least equal to 9K) having a visible face in “soft” gold alloy, such as for example in green gold alloy while having a dial having improved mechanical characteristics and greater than the hardness of the green gold alloy (in the annealed state) by the use of a structural part in “hard” gold alloy having a hardness greater than or equal to 100 Hv, configured to withstand the various constraints linked to the use of a timepiece.

[0014] Thus, each part constituting the final solid dial is titled or titrable with a minimum title of 9K.

[0015] Preferably, the invention proposes a single-piece dial made of precious metal based on at least two gold alloys, characterized in that it comprises a first part, called the structural part, made of a first gold alloy having at least 750‰ by weight of gold and a second part, called the aesthetic part, partially or completely covering the first part, the second part being made of a second gold alloy having at least 750‰ by weight of gold and having a composition different from the first gold alloy; the two parts being inseparable.

[0016] Thanks to the invention, it is possible to obtain a solid dial in titrable gold having a visible face in “soft” gold alloy, such as for example in green gold alloy, with a title greater than or equal to 18K.

[0017] In addition to the characteristics mentioned in the preceding paragraphs, the single-piece dial made of precious metal based on at least two gold alloys according to the invention may have one or more complementary characteristics among the following, considered individually or according to all technically possible combinations: – the first gold alloy forming the first part has a hardness greater than the hardness of the second gold alloy forming the second part; – the first gold alloy forming the first part has a hardness greater than or equal to 100Hv, preferably greater than or equal to 120Hv; for example, the first gold alloy has a hardness of the order of 135Hv; – the second part covering the first part is made of a second gold alloy having a hardness of less than 100Hv; – the first gold alloy comprises, expressed by weight, the following elements: o gold: in a percentage equal to or greater than 750‰; o copper: balance at 1000‰; o optionally in a percentage between 0 and 50 ‰, limits included, at least one of the following elements: silver, indium, palladium, gallium, zinc; o optionally, at least one grain refiner, in a percentage between 0 and 0.5 ‰, limits included; the respective percentages of all the constituent elements of the gold alloy adding up to 1000 ‰; – the first gold alloy comprises, expressed by weight, the following elements: o gold: 750 ‰; o silver: 50 ‰; o copper: balance at 1000 ‰; o optionally, at least one grain refiner, such as iridium, in a percentage between 0 and 0.5 ‰, limits included; the respective percentages of all the constituent elements of the gold alloy adding up to 1000 ‰; – the second gold alloy is a green, purple, blue, pink, white, grey or yellow gold; – the second gold alloy is a green gold alloy comprising, expressed by weight, the following elements: o gold: in a percentage equal to or greater than 750 ‰; o silver: balance at 1000 ‰; o optionally at least one grain refiner in a percentage between 0 and 0.5 ‰, limits included; o optionally copper in a percentage between 0 and 100 ‰, limits included; o optionally zinc in a percentage between 0 and 100 ‰, limits included; o optionally indium in a percentage between 0 and 50 ‰, limits included; o optionally palladium in a percentage between 0 and 50‰, limits included; the respective percentages of all the constituent elements of the gold alloy adding up to 1000‰; – the dial comprises a filler element ensuring the continuity of material between the first part and the second part; the filler element being made of a third gold alloy comprising, expressed by weight, at least 350‰ of gold; preferably at least 750‰ of gold; – the first part, the second part and the filler element are made of respective gold alloys comprising the same percentage by weight of gold; – the filler element is a solder or a filler metal in gold alloy; – the filler element comprises, expressed by weight, at least 350‰ of gold and in balance for example at least one of the following elements: silver, copper, zinc, gallium; – the filler element comprises, expressed by weight, at least 750‰ of gold and in balance for example at least one of the following elements: silver, copper, zinc, gallium; – the filler element has a melting point lower than 450°C; – the filler element has a melting point higher than 450°C.

[0018] The invention also relates to a timepiece comprising such a single-piece dial made of precious metal according to the invention.

[0019] The invention also relates to a method for manufacturing a single-piece dial made of precious metal according to the invention, characterized in that the manufacturing method comprises the following steps: a) manufacturing a first disk in the first gold alloy; b) manufacturing a second disk in the second gold alloy; preferably, the diameter of the second disk being less than the diameter of the first disk; c) welding the second disk to the first disk by a welding method without filler metal to form a single-piece assembly.

[0020] Preferably, the manufacturing method further comprises a step d) of cutting the single-piece assembly obtained in step c) according to a determined geometric contour to obtain the final dimensions of the single-piece dial in precious metal.

[0021] According to an alternative embodiment, the method for manufacturing a single-piece dial made of precious metal according to the invention comprises the following steps: a) manufacturing a first disk in the first gold alloy; b) manufacturing a second disk in the second gold alloy; preferably, the diameter of the second disk being less than the diameter of the first disk; c) assembling the two disks, the second disk covering the first disk; the two disks being assembled by manually or automatically depositing a gold alloy solder comprising, expressed by weight, at least 350‰ of gold, preferably at least 750‰, in the form of a paste, on the first disk and in contact with the second disk, the solder being able to be deposited on a part of the perimeter or on the entire perimeter of the second disk; d) maintaining the assembly of the two disks obtained in step c); e) heating the assembly obtained in step d) to fuse the brazing to the two disks and obtain a single-piece assembly, the brazing migrating by capillarity into the joint plane of the two disks held together; preferably, the heating step is carried out at a temperature between 550°C and 750°C.

[0022] Preferably, the manufacturing method further comprises a step f) of cutting the single-piece assembly obtained in step e) according to a contour of determined geometry to obtain the final dimensions of the single-piece dial in precious metal.

[0023] According to an alternative embodiment, the method for manufacturing a single-piece dial made of precious metal according to the invention comprises the following steps: a) manufacturing a first disk in the first gold alloy; b) manufacturing a second disk in the second gold alloy; preferably, the diameter of the second disk being less than the diameter of the first disk; c) depositing, manually or automatically, a solder paste, made of a gold alloy comprising, expressed by weight, at least 350‰ of gold, preferably at least 750‰ of gold, on at least one surface of one of the two disks, the solder being deposited in part or on all of said at least one surface; d) assembling the two disks, the second disk covering the first disk; e) maintaining the assembly of the two disks obtained in step d); f) heating the assembly obtained in step e) to fuse the solder to the two disks and obtain a single-piece assembly; preferably, the temperature setting step is carried out at a temperature between 550°C and 750°C.

[0024] Preferably, the manufacturing method further comprises a step g) of cutting the single-piece assembly obtained in step f) according to a determined geometric contour to obtain the final dimensions of the single-piece dial in precious metal.

[0025] According to an alternative embodiment, the method for manufacturing a single-piece dial made of precious metal according to the invention comprises the following steps: a. manufacturing a first disk in the first gold alloy; b. manufacturing a second disk in the second gold alloy; preferably, the diameter of the second disk being less than the diameter of the first disk; step a) or b) comprising the following sub-steps: – a step of depositing, manually or automatically, a gold alloy solder as a filler element, in the form of a strip on the first alloy, or the second alloy; – a step of heating, for example in a pass-through furnace, to fuse the solder to the first alloy, or to the second alloy, in order to obtain a first single-piece assembly; preferably, the heating step is carried out at a temperature of between 550°C and 750°C, – optionally a step of rolling the first single-piece assembly to obtain a desired thickness; – a step of cutting the first single-piece assembly obtained previously to obtain the desired dimensions of the first disk, or of the second disk; c. assembling the two disks obtained in steps a) and b), by depositing the second disk on the first disk on the brazing side; d. maintaining the assembly of the two disks obtained in step c); e. heating the assembly obtained in step d) to fuse the brazing to the other disk and obtain a second single-piece assembly; preferably, the heating step is carried out at a temperature between 550°C and 750°C.

[0026] Preferably, the manufacturing method further comprises a step f) of cutting the second single-piece assembly according to a determined geometric contour to obtain the final dimensions of the single-piece dial in precious metal.

[0027] Preferably, the manufacturing method further comprises a heat treatment step and/or a finishing step.

[0028] Other features and advantages of the present invention will become apparent from the following description of preferred embodiments, presented by way of non-limiting example with reference to the accompanying drawings.

Brief description of the figures

[0029] The aims, advantages and characteristics of the present invention will become apparent upon reading the detailed description below with reference to the following figures. Figure 1 shows a first example of an embodiment of a single-piece dial made of titratable precious metal based on at least two gold alloys according to the invention. Figure 2 shows a second example of an embodiment of a single-piece dial made of titratable precious metal based on at least two gold alloys according to the invention. Figure 3 shows the constituent parts of a single-piece dial made of titratable precious metal based on at least two gold alloys manufactured according to the manufacturing method of the invention, according to a first variant embodiment. Figure 4 shows the constituent parts of a single-piece dial made of titratable precious metal based on at least two gold alloys manufactured according to the manufacturing method of the invention, according to a second variant embodiment. Figure 5 shows the constituent parts of a single-piece dial made of titratable precious metal based on at least two gold alloys manufactured using the manufacturing method of the invention, according to a third variant embodiment.

Detailed description of the invention

[0030] Generally, in the present application the hardness values of the gold alloys are indicated in the annealed state, unless otherwise specified.

[0031] Figure 1 schematically illustrates a first example of embodiment of a single-piece dial 10 made of precious metal based on at least two gold alloys. Such a dial 10 is a solid piece composed of at least 350‰ in weight of gold, as well as each alloy composing it. Thus such a dial is a dial having in its entirety at least 9K of gold.

[0032] Preferably, dial 10 is a solid piece composed of at least 750‰ in weight of gold.

[0033] Dial 10 according to the invention is a solid gold dial with a minimum fineness of 18 carats.

[0034] The dial 10 is made up of an inseparable assembly of a first structural part 11, lower part of the dial 10, made of a first gold alloy, chosen for its structural properties, and of a second aesthetic part 12, upper part of the dial 10, partially or completely covering the first structural part 11, the second aesthetic part 12 being made of a second gold alloy chosen mainly for its aesthetic properties, and in particular for its color, without concern for its mechanical characteristics, and in particular the hardness of the alloy in question in the annealed state.

[0035] The upper face 14 of the second aesthetic part 12 forms the upper surface of the dial 10 intended to be the visible part of the dial. The lower face 15 of the first structural part 11 forms the lower surface of the dial 10 intended to be opposite the clockwork movement.

[0036] Preferably, the upper surface 14 of the second aesthetic part 12 comprises decorations applied or made in the mass by any techniques known in the state of the art. For example, the decorations can be engraved, guilloched directly in the mass of the second aesthetic part 12.

[0037] The upper face 14 of the second aesthetic part 12 may also have enameled, lacquered, varnished parts, etc.

[0038] Conventionally, and as required, the dial 10 may also be covered, at least in part at the level of the upper surface 14 of the second aesthetic part 12, with a protective coating, for example against tarnishing of the gold alloy used for the production of this second aesthetic part 12.

[0039] The first structural part 11 is made from a part, for example a disk, made from a first gold alloy comprising, expressed by weight, at least 350‰ of gold, preferably at least 750‰ of gold. The first structural part 11 forms the structural base of the dial 10 configured to provide the mechanical strength of the dial 10.

[0040] Preferably, the first structural part 11 is made of a “hard” gold alloy having a hardness greater than or equal to 100 Hv, preferably greater than or equal to 120 Hv. For example, the first structural part 11 has a hardness of 135 Hv.

[0041] For example, the first structural part 11 is made from a first gold alloy comprising, expressed by weight, at least 350‰ of gold, and in balance copper, so as to obtain a titrated gold alloy with the best possible mechanical properties by the addition of copper.

[0042] For example, the first structural part 11 is made from a first gold alloy comprising, expressed by weight, at least 750‰ of gold, and in balance copper, so as to obtain a titrated gold alloy with the best possible mechanical properties by the addition of copper.

[0043] For example, the second gold alloy may be 9 karat, 10 karat, 14 karat, 15 karat, 18 karat, 20 karat, 21.6 karat or 22 karat gold.

[0044] Optionally, the first gold alloy of the first structural part 11 may also comprise, in a percentage of between 0 and 50 ‰ (limits included), expressed by weight of the alloy, at least one of the following elements: silver, indium, palladium, gallium, zinc. The respective percentages of all the constituent elements of the alloy add up to 1000 ‰.

[0045] Optionally, the first gold alloy of the first structural part 11 may also comprise, in a percentage of between 0 and 0.5‰ (limits included), expressed by weight of the alloy, a grain refiner, such as for example iridium. The respective percentages of all the constituent elements of the alloy are completed up to 1000‰.

[0046] The first structural part 11 is for example made from a 5N18 gold alloy, which is an 18-carat 5N red gold.

[0047] The first structural part 11 is for example made of a first gold alloy comprising, expressed by weight, the following elements: – gold: in a percentage of 750‰; – silver: in a percentage of 50‰; – copper: balance at 1000‰; – optionally, at least one grain refiner, such as iridium, in a percentage between 0 and 0.5‰; the respective percentages of all the elements of the gold alloy adding up to 1000‰. Such a gold alloy has a hardness of 135Hv.

[0048] The second aesthetic part 12 is made from a part, for example a disc, made from a second gold alloy comprising, expressed by weight, at least 350‰ of gold.

[0049] Preferably, the second aesthetic part 12 is made from a second gold alloy comprising, expressed by weight, at least 750‰ of gold.

[0050] The second gold alloy has a different composition and color from the first gold alloy.

[0051] For example, the second gold alloy may be 9 carat, 10 carat, 14 carat, 15 carat, 18 carat, 20 carat, 21.6 carat, 22 carat, 23 carat, or 24 carat gold.

[0052] Preferably, the second aesthetic part 12 is made from a second “soft” gold alloy having a hardness of less than 100 Hv.

[0053] Thanks to the dial 10 according to the invention, the second aesthetic part 12 can be made of a gold alloy having a hardness of less than 60 Hv without reducing the capacity of the gold dial 10 to resist shocks, thanks to the use of the first structural part 11.

[0054] Preferably, the second aesthetic part 12 is made from a second gold alloy whose composition has a copper proportion of less than 150‰ by weight, preferably less than 50‰ by weight.

[0055] The second gold alloy of this second aesthetic part 12 can be a green, purple, blue, pink, white, gray or yellow gold.

[0056] For example, the second aesthetic part 12 is made from a second green gold alloy comprising, expressed by weight, at least 750‰ of gold and silver in balance at 1000‰.

[0057] For example, the second aesthetic part 12 is made from an alloy of 18 carat green gold, called electrum gold, comprising, expressed by weight, 750‰ of gold and 250‰ of silver.

[0058] For example, the second aesthetic part 12 is made of a green gold alloy comprising, expressed by weight, the following elements: – gold: in a percentage at least equal to 750‰; – silver: balance at 1000‰; – optionally at least one grain refiner, such as iridium, in a percentage between 0 and 0.5‰, inclusive; – optionally copper in a percentage between 0 and 100‰; copper can be used to improve the hardness if necessary; – optionally zinc in a percentage between 0 and 100‰, inclusive; zinc can be used to nuance the green color of the gold alloy according to the needs; – optionally indium in a percentage between 0 and 50‰, inclusive; indium can be used to nuance the color of the gold alloy according to requirements; – optionally palladium in a percentage between 0 and 50‰, limits included; palladium can be used to improve the resistance to oxidation and tarnishing of the green gold alloy; the respective percentages of all the constituent elements of the gold alloy adding up to 1000‰.

[0059] It will be noted that the addition of zinc to the gold alloy, in particular in a proportion greater than 100‰, complicates the casting of the gold alloy and therefore the manufacture of the disk forming the second aesthetic part 12 of the dial 10. Consequently, the proportion of zinc in the second gold alloy will preferably be chosen to be less than 100‰ by weight of the alloy.

[0060] According to the first exemplary embodiment illustrated in FIG. 1, the second aesthetic part 12 is secured to the first structural part 11 without the addition of a filler element, a brazing metal, a filler metal or a fusion part to form the fusion of the two parts 11, 12.

[0061] This first exemplary embodiment can be carried out by a welding process without filler metal, for example by a spot welding process, a laser welding process or an electron beam welding process.

[0062] Thus, a first method for manufacturing a single-piece dial 10 made of precious metal based on at least two gold alloys according to the invention consists of: – manufacturing a first disk in the first gold alloy; – manufacturing a second disk in the second gold alloy; preferably, the diameter of the second disk being less than the diameter of the first disk; – welding the second disk to the first disk by a welding method without filler metal to form a single-piece assembly; – optionally, cutting the single-piece assembly according to a contour of determined geometry to obtain the final dimensions of the single-piece dial 10 made of precious metal.

[0063] Figure 2 illustrates a second exemplary embodiment of a single-piece dial 20 made of precious metal based on at least two gold alloys according to the invention. Dial 20 is identical to dial 10 described with reference to Figure 1 except for the characteristics which will be described below.

[0064] In this second exemplary embodiment, the second aesthetic part 12 is secured to the first structural part 11 by the use of a filler element 13 made from a third gold alloy comprising, expressed by weight, at least 350‰ of gold, preferably at least 750‰ of gold.

[0065] Preferably, the filler element 13 is a filler metal made from the third gold alloy added during a brazing or welding process. The filler element 13 ensures the continuity of material between the first structural part 11 and the second aesthetic part 12. The filler element 13 is for example a braze.

[0066] For example, the first gold alloy, the second gold alloy and the third gold alloy of the filler element 13 have different titles.

[0067] For example, the first gold alloy, the second gold alloy and the third gold alloy of the filler element 13 each have, expressed by weight, at least 750‰ of gold.

[0068] For example, the first gold alloy, the second gold alloy and the third gold alloy of the filler element 13 have the same title, that is to say the same proportion of gold by weight in the respective alloy, for example 750‰ by weight.

[0069] Preferably, the contribution element 13 comprises at least 750‰ of gold and in balance at least one of the following compounds: silver, copper, zinc, gallium.

[0070] For example, the filler element 13 has a melting point below 450°C.

[0071] For example, the filler element 13 has a melting point greater than 450°C.

[0072] The melting point of the filler element 13 is determined and modifiable according to the percentage of silver, zinc and gallium used in the third gold alloy.

[0073] The first structural part 11 and the second aesthetic part 12 of the dial 10, 20 are formed from initial disc-shaped parts. However, the first structural part 11 and the second aesthetic part 12 of the gold dial 10, 20 can be formed from initial parts of various shapes (round, square, etc.) and with variable dimensions depending on the needs.

[0074] Preferably, the first structural part 11 and the second aesthetic part 12 of the dial 10, 20 are formed from discs having a thickness of between 0.1 mm and 1.5 mm, preferably between 0.2 mm and 0.5 mm.

[0075] Preferably, the first structural part 11 has a thickness greater than the second aesthetic part 12.

[0076] The disks used to produce the first structural part 11 and the second aesthetic part 12 have a diameter of between 10mm and 60mm. The dimensions are adapted according to the needs and the final dimensions of the dial 10, 20.

[0077] The disks used to produce the first structural part 11 and the second aesthetic part 12 have a flatness of less than 0.1 mm, preferably less than 0.05 mm, in particular to ensure the capillary flow of the filler element 13.

[0078] Figure 3 illustrates a first method of manufacturing the dial 20 illustrated in Figure 2. This first method of manufacturing comprises the following steps: – manufacturing a first disk 11a in a first structural gold alloy as described above; – manufacturing a second disk 12a in a second aesthetic gold alloy as described above; preferably, the diameter of the second disk 12a is less than the diameter of the first disk 11a; – assembly of the two disks 11a and 12a, the second disk 12a, made in the second aesthetic gold alloy, forms the second aesthetic part 12 of the dial 20 and covers the first disk 11a forming the first structural part 11 of the dial 20; the two disks 11a and 12a being assembled by manually or automatically depositing a gold alloy solder 13 as a filler element, in the form of a paste, on the first disk 11a and in contact with the second disk 12a, the gold alloy solder 13 being able to be deposited on part of the perimeter or on the entire perimeter of the second disk 12a; – maintaining the assembly of the two disks 11a and 12a, for example by adding a weight made of neutral material on the upper surface 14a of the second disk 12a, for example made of graphite or sapphire because they do not react with gold alloys and have sufficient temperature resistance; – heating the assembly, for example in a pass-through furnace, allowing the solder 13 to be fused to the two disks 11a, 12a and a single-piece assembly to be obtained, the solder 13 migrating by capillarity into the joint plane of the two disks 11a, 12a; preferably, the heating step is carried out at a temperature between 550°C and 750°C; – optionally, cutting the single-piece assembly according to a contour of determined geometry to obtain the final dimensions of the single-piece dial made of precious metal.

[0079] Figure 4 illustrates a second method of manufacturing the dial 20 illustrated in Figure 2. This second method of manufacturing comprises the following steps: – manufacturing a first disk 11a in a first structural gold alloy as described above; – manufacturing a second disk 12a in a second aesthetic gold alloy as described above; preferably, the diameter of the second disk 12a is less than the diameter of the first disk 11a; – depositing, manually or automatically, a solder 13' in gold alloy as a filler element, in the form of a paste, on the upper surface 16 of the first disk 11a; the solder 13' can be deposited in part or on the entire upper surface 16 of the first disk 11a; – assembling the two disks 11a and 12a, by depositing the second disk 12a, made of the second aesthetic gold alloy forming the second aesthetic part 12 of the dial 20, on the gold alloy brazing 13' deposited on the first disk 11a forming the first structural part 11 of the dial 20; – maintaining the assembly of the two disks 11a and 12a, for example by adding a weight on the upper surface 14a of the second disk 12a, for example made of graphite or sapphire for temperature resistance; – heating the assembly, for example in a pass-through furnace, to fuse the brazing 13' to the two disks 11a, 12a and obtain a single-piece assembly; preferably, the heating step is carried out at a temperature between 550°C and 750°C; – optionally, cutting of the single-piece assembly according to a specific geometric contour to obtain the final dimensions of the single-piece precious metal dial.

[0080] Figure 5 illustrates a third method of manufacturing the dial 20 illustrated in Figure 2.

[0081] This third manufacturing method comprises the following steps: – manufacturing a first disk 11a in a first structural gold alloy as described above; – manufacturing a second disk 12a in a second aesthetic gold alloy as described above; preferably, the diameter of the second disk 12a is less than the diameter of the first disk 11a; – In this third method, the step of manufacturing the first disk 11a or the step of manufacturing the second disk 12a, comprises: – a step of depositing manually or automatically, a 13" solder in gold alloy as a filler element, in the form of a strip on the first alloy, or the second alloy; – a step of heating for example in a passage furnace, to fuse the 13" solder to the first alloy, or to the second alloy, in order to obtain a first single-piece assembly; preferably, the temperature-setting step is carried out at a temperature between 550°C and 750°C, – optionally a rolling step of the first single-piece assembly to obtain a desired thickness; – a cutting step to obtain the desired dimensions of the first disc 11a, or of the second disc 12a.

[0082] The third manufacturing method further comprises the following steps: – assembling the two disks 11a and 12a obtained previously, by depositing the second disk 12a, made of the second aesthetic gold alloy forming the second aesthetic part 12 of the dial 20, on the first disk 11a forming the first structural part 11 of the dial 20 on the brazing strip 13" side; – maintaining the assembly of the two disks 11a and 12a, for example by adding a weight on the upper surface 14a of the second disk 12a, for example made of graphite or sapphire for temperature resistance; – heating the assembly, for example in a pass-through furnace, to fuse the brazing 13" to the other disk, i.e. to the second disk 12a, or to the first disk 11a, and obtain a second single-piece assembly; preferably, the temperature-setting step is carried out at a temperature between 550°C and 750°C; – optionally, cutting the second single-piece assembly according to a determined geometric contour to obtain the final dimensions of the single-piece precious metal dial.

[0083] Optionally, the manufacturing methods described above may include at least one heat treatment step (annealing, stress relief, etc.), and/or at least one finishing step (polishing, decoration, etc.).

Claims (22)

1. One-piece dial made of precious metal (10, 20) based on at least two gold alloys, characterized in that it comprises a first part (11), called the structural part, made of a first gold alloy having at least 350‰ by weight of gold and a second part (12), called the aesthetic part, partially or completely covering the first part (11), the second part (12) being made of a second gold alloy having at least 350‰ by weight of gold and having a composition different from the first gold alloy; the two parts (11, 12) being inseparable. 2. One-piece precious metal dial (10, 20) according to the preceding claim, characterized in that the first gold alloy forming the first part (11) has a hardness greater than the hardness of the second gold alloy forming the second part (12). 3. One-piece precious metal dial (10, 20) according to the preceding claim, characterized in that the first gold alloy forming the first part (11) has a hardness greater than or equal to 100Hv, preferably greater than or equal to 120Hv. 4. One-piece precious metal dial (10, 20) according to one of the preceding claims, characterized in that the second part (12) covering the first part (11) is made of a second gold alloy having a hardness of less than 100Hv. 5. One-piece precious metal dial (10, 20) according to one of the preceding claims, characterized in that it comprises a first part (11), called the structural part, made of a first gold alloy having at least 750 ‰ by weight of gold and a second part (12), called the aesthetic part, partially or completely covering the first part (11), the second part (12) being made of a second gold alloy having at least 750 ‰ by weight of gold and having a composition different from the first gold alloy; the two parts (11, 12) being inseparable. 6. One-piece precious metal dial (10, 20) according to one of the preceding claims, characterized in that the first gold alloy comprises, expressed by weight, the following elements: – gold: in a percentage equal to or greater than 750‰; – copper: balance at 1000‰; – optionally in a percentage between 0 and 50‰, limits included, at least one of the following elements: silver, indium, palladium, gallium, zinc; – optionally, at least one grain refiner, in a percentage between 0 and 0.5‰, limits included; the respective percentages of all the constituent elements of the gold alloy adding up to 1000‰. 7. One-piece precious metal dial (10, 20) according to one of the preceding claims, characterized in that the first gold alloy comprises, expressed by weight, the following elements: – gold: 750‰; – silver: 50‰; – copper: balance at 1000‰; – optionally, at least one grain refiner, such as iridium, in a percentage between 0 and 0.5‰, limits included; the respective percentages of all the constituent elements of the gold alloy adding up to 1000‰. 8. One-piece precious metal dial (10, 20) according to one of the preceding claims, characterized in that the second gold alloy is a green, purple, blue, pink, white, gray or yellow gold. 9. One-piece precious metal dial (10, 20) according to one of the preceding claims, characterized in that the second gold alloy is a green gold alloy comprising, expressed by weight, the following elements: – gold: in a percentage equal to or greater than 750 ‰; – silver: balance at 1000 ‰; – optionally at least one grain refiner in a percentage between 0 and 0.5 ‰, limits included; – optionally copper in a percentage between 0 and 100 ‰, limits included; – optionally zinc in a percentage between 0 and 100 ‰, limits included; – optionally indium in a percentage between 0 and 50 ‰, limits included; – optionally palladium in a percentage between 0 and 50 ‰, limits included; the respective percentages of all the constituent elements of the gold alloy adding up to 1000‰. 10. One-piece precious metal dial (20) according to one of the preceding claims, characterized in that it comprises a filler element (13) ensuring the continuity of material between the first part (11) and the second part (12); the filler element (13) being made of a third gold alloy comprising, expressed by weight, at least 350‰ of gold. 11. One-piece precious metal dial (20) according to the preceding claim, characterized in that the filler element (13) is made from a third gold alloy comprising, expressed by weight, at least 750‰ of gold. 12. One-piece precious metal dial (20) according to one of claims 10 to 11, characterized in that the first part (11), the second part (12) and the filler element (13) are made from respective gold alloys comprising the same percentage by weight of gold. 13. One-piece precious metal dial (20) according to one of claims 10 to 12, characterized in that the filler element (13) is a solder or a filler metal. 14. One-piece precious metal dial (20) according to one of claims 10 to 13, characterized in that the filler element (13) comprises, expressed by weight, at least 350‰ of gold, preferably at least 750‰ of gold, and in balance at least one of the following elements: silver, copper, zinc, gallium. 15. One-piece precious metal dial (20) according to one of claims 10 to 14, characterized in that the filler element (13) has a melting point below 450°C. 16. One-piece precious metal dial (20) according to one of claims 10 to 14, characterized in that the filler element (13) has a melting point greater than 450°C. 17. Timepiece comprising a single-piece precious metal dial (10, 20) according to one of the preceding claims. 18. A method of manufacturing a single-piece precious metal dial (10) according to one of claims 1 to 17, characterized in that the manufacturing method comprises the following steps: a. manufacturing a first disk in the first gold alloy; b. manufacturing a second disk in the second gold alloy; preferably, the diameter of the second disk being less than the diameter of the first disk; c. welding the second disk to the first disk by a welding process without filler metal to form a single-piece assembly; d. optionally, cutting the single-piece assembly obtained in step c) according to a determined geometric contour to obtain the final dimensions of the single-piece precious metal dial (10). 19. A method of manufacturing a single-piece precious metal dial (20) according to one of claims 1 to 17, characterized in that the manufacturing method comprises the following steps: a. manufacturing a first disk (11a) in the first gold alloy; b. manufacturing a second disk (12a) in the second gold alloy; preferably, the diameter of the second disk (12a) being less than the diameter of the first disk (11a); c. assembling the two disks (11a, 12a), the second disk (12a) covering the first disk (11a); the two disks (11a, 12a) being assembled by manually or automatically depositing a solder (13) made of a gold alloy comprising, expressed by weight, at least 350‰ of gold, preferably at least 750‰ of gold, in the form of a paste, on the first disk (11a) and in contact with the second disk (12a), the solder (13) being able to be deposited on part of the perimeter or on the entire perimeter of the second disk (12a); d. maintaining the assembly of the two disks (11a, 12a) obtained in step c); e. heating the assembly obtained in step d) to fuse the solder (13) to the two disks (11a, 12a) and obtain a single-piece assembly, the solder (13) migrating by capillarity into the joint plane of the two disks (11a, 12a) maintained assembled; preferably, the temperature-setting step is carried out at a temperature between 550°C and 750°C; f. optionally, cutting the single-piece assembly obtained in step e) according to a determined geometric contour to obtain the final dimensions of the single-piece precious metal dial (20). 20. A method of manufacturing a single-piece precious metal dial (20) according to one of claims 1 to 17, characterized in that the manufacturing method comprises the following steps: a. manufacturing a first disk (11a) in the first gold alloy; b. manufacturing a second disk (12a) in the second gold alloy; preferably, the diameter of the second disk (12a) being less than the diameter of the first disk (11a); c. depositing, manually or automatically, a solder (13') in paste, in gold alloy comprising, expressed by weight, at least 350‰ of gold, preferably at least 750‰ of gold, on at least one surface of one of the two disks (11a, 12a), the solder (13') being deposited in part or on the whole of said at least one surface; d. assembling the two disks (11a, 12a), the second disk (12a) covering the first disk (11a); e. maintaining the assembly of the two disks (11a, 12a) obtained in step d); f. heating the assembly obtained in step e) to fuse the solder (13') to the two disks (11a, 12a) and obtain a single-piece assembly; preferably, the heating step is carried out at a temperature between 550°C and 750°C; g. optionally, cutting the single-piece assembly obtained in step f) according to a contour of determined geometry to obtain the final dimensions of the single-piece precious metal dial (20). 21. A method of manufacturing a single-piece precious metal dial (20) according to one of claims 1 to 17, characterized in that the manufacturing method comprises the following steps: a. manufacturing a first disk (11a) in the first gold alloy; b. manufacturing a second disk (12a) in the second gold alloy; preferably, the diameter of the second disk (12a) being less than the diameter of the first disk (11a); step a) or b) comprising the following sub-steps: – a step of manually or automatically depositing a gold alloy solder (13") as a filler element, in the form of a strip on the first alloy, or the second alloy; – a step of heating, for example in a pass-through furnace, to fuse the solder (13") to the first alloy, or to the second alloy, in order to obtain a first single-piece assembly; preferably, the temperature-setting step is carried out at a temperature between 550°C and 750°C, – optionally a step of rolling the first single-piece assembly to obtain a desired thickness; – a step of cutting the first single-piece assembly obtained previously to obtain the desired dimensions of the first disk (11a), or of the second disk (12a); c. assembling the two disks (11a, 12a) obtained in steps a) and b), by depositing the second disk (12a) on the first disk (11a) on the solder side (13"); d. maintaining the assembly of the two disks (11a, 12a) obtained in step c); e. heating the assembly obtained in step d) to fuse the solder (13") to the other disk (11a, 12a) and obtain a second single-piece assembly; preferably, the heating step is carried out at a temperature between 550°C and 750°C; f. optionally, cutting the second single-piece assembly according to a contour of determined geometry to obtain the final dimensions of the single-piece dial made of precious metal. 22. Method for manufacturing a single-piece precious metal dial (20) according to one of claims 17 to 21, characterized in that the manufacturing method comprises a heat treatment step and/or a finishing step.