Item with plique-a-jour enamel decoration and method for manufacturing the same

Abstract

To provide a method for making it possible to manufacture components with a plique-a-jour enamel decoration in large series at a low cost and with increased enamel strength.SOLUTION: A method for manufacturing an item comprising a through-decoration filled with an enamel to form a plique-a-jour enamel, includes the steps of: obtaining a blank 5 defined with an upper face 5a and a lower face 5b on the opposite side of the upper face 5a; removing a part of the blank 5 from the upper face 5a to produce a decoration 2a that does not pass through to the lower face 5b or, alternatively, in the previous step, directly obtaining the blank 5 with the non-through decoration 2a; depositing one or more layers of enamel 3 within the non-through decoration 2a and firing the enamel 3 after each layer has been deposited; and machining, preferably by grinding, the lower face 5b to reveal the enamel 3 and thus produce the item with the through-decoration filled with enamel 3.SELECTED DRAWING: Figure 1c

Description

[Technical Field]

[0001] The present invention relates to a method for producing articles decorated with plique-à-jour enamel. The method according to the invention allows for the production of large series at low cost. The invention further relates to articles produced by this method. [Background technology]

[0002] Plique-à-jour is a technique for applying enamel to a substrate that has no base at the level of the enamel. This allows light to stream through the transparent or translucent enamel, resulting in a miniature stained-glass effect.

[0003] The traditional plique-à-jour technique involves creating metal welded partitions that remain stable during the enamel firing. Due to their nature, metal partitions, mainly made of yellow or white gold, can deform or detach from the base material during the successive firing of layers deposited one by one, severely limiting the number of kiln passes and the designs that can be produced.

[0004] A substrate is also required during deposition and firing to prevent the enamel from flowing beyond the partitions. This is extremely difficult to achieve on non-planar shapes because the substrate is made of quartz. Traditionally, enamel is deposited by hand using a brush or oiler. The layers deposited using these methods are very thin, typically requiring the deposition of several dozen layers to achieve a total thickness of less than 0.5 mm. Due to their thinness, the resulting enamel is very fragile.

[0005] Because the technique is laborious and unreproducible, watches with plique-à-jour dials are either one-offs or produced in extremely limited series at prohibitive cost. To this day, the lack of reproducibility of this technique prevents watchmakers from mass-producing the watches. Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is to overcome the above-mentioned drawbacks by proposing a manufacturing method that makes it possible to produce plique-à-jour enamel decorated parts in large series at low cost and with increased enamel strength. [Means for solving the problem]

[0007] For this purpose, the invention relates to a method for manufacturing an article with a through-decoration filled with enamel to form a so-called plicajour enamel, the method comprising the steps of: obtaining a blank defined by an upper surface and a lower surface opposite the upper surface; removing a portion of the blank from the upper surface to form a non-penetrating decoration on the lower surface, or alternatively directly obtaining a blank with a non-penetrating decoration in the previous step; depositing one or more layers of enamel in the blind decoration and firing the enamel after each layer; machining the underside, preferably by grinding, to expose the enamel and produce an article with a through-decoration filled with enamel; The present invention relates to a method comprising:

[0008] Preferably, the through decoration is then polished.

[0009] The method is highly reproducible and allows for mass production at very low cost. Complex shapes are limited only by the resistance of the substrate material during firing or impact.

[0010] This method allows for the deposition of thick layers of enamel, typically less than 10 layers, to a total thickness of 0.5 mm or more. This greater thickness of enamel compared to that of prior art enamels means that it is less brittle and can therefore be used to make exterior components such as bezels that are subject to high stresses.

[0011] More generally, the use of enamel rather than lacquer offers superior chemical and mechanical resistance, unlike standard lacquered bezels. Enamel, unlike lacquer, is also one of the materials considered noble in watchmaking and jewelry.

[0012] The invention is also based on the ability to simultaneously grind the substrate and enamel while ensuring an optimum surface finish for both materials. Polishing the enamel also means that the part does not need to be reheated in a kiln to give it its final glossy, translucent appearance.

[0013] Transparent enamel decoration creates depth that is impossible to achieve today. Gradient processes can be used to create gradations from translucent to opaque. Color gradients can also be deposited, for example by spraying. Finishes such as satin finishes and laser texturing can be easily combined on the substrate. [Brief explanation of the drawings]

[0014] [Figure 1a] 1 illustrates one step of the method according to the invention. [Figure 1b] 1 illustrates one step of the method according to the invention. [Figure 1c] 1 illustrates one step of the method according to the invention. [Figure 1d] 1 illustrates one step of the method according to the invention. [Figure 1e] 1 shows one step of the method according to the invention, in each figure a schematic cross-section of a part of an article or blank and a three-dimensional view of a part of the article or blank are shown. DETAILED DESCRIPTION OF THE INVENTION

[0015] The present invention relates to a method for producing an article decorated with plique-à-jour enamel. The article may be, for example, a watch component. More specifically, the article may be an exterior component selected from a non-exhaustive list including a case middle, case back, bezel, crown, push-piece, bracelet link, bracelet, buckle, clasp, dial, and hands. The method is particularly well suited for producing articles subject to high stresses, such as exterior components. The article may also comprise a movement component, such as a rotating shaft. The present invention will be described more specifically below with respect to the rotating shaft.

[0016] The manufacturing method is suitable for any substrate with a melting point higher than the enamel firing temperature (usually between 650°C and 1100°C, depending on the enamel composition). The method is particularly well suited for substrates made of hard materials such as ceramics (e.g., silicon nitride, zirconium oxide, or aluminum oxide), sapphire, or cermets. Some ceramics (e.g., ZrO2) have excellent mechanical and chemical adhesion with enamel, and their expansion coefficients are very similar, which allows the openwork article to retain excellent mechanical strength. These materials can withstand firing cycles up to 1000°C, for example, in the case of high-fired enamels, and can withstand the thermal shock of rapid firing cycles.

[0017] The method is shown in Figures 1a to 1e in five steps a) to e) in relation to the rotation axis. In the first step a), an undecorated article, called a blank 5 or substrate, is obtained. The blank 5 is defined by an upper surface 5a and a lower surface 5b opposite the upper surface 5a. The upper surface may be the surface intended to face the observer during use, or the opposite surface. In the second step b), a non-penetrating decoration 2a is formed on the upper surface 5a. The non-penetrating decoration can be formed, for example, by laser ablation. Optionally, if a blank with a non-penetrating decoration 2a is obtained directly in step a), step b) can be omitted, for example, if the blank is formed by injection molding. In the third step c), an enamel 3 is deposited within the non-penetrating decoration 2a. Ideally, for industrial production purposes, the deposition is performed by liquid spraying. Alternatively, the enamel can be quickly deposited by hand using a brush or by dusting with powder. The blank 5 is then fired to vitrify the deposited enamel. Preferably, multiple layers of enamel are deposited, with a firing cycle after each deposition step to ensure the enamel is bubble-free. Different colored enamel layers can be deposited, and / or the color of the enamel deposited for each layer can vary. The number of deposited enamel layers is typically between 2 and 15, preferably between 3 and 10, with a total thickness of at least 0.5 mm, preferably at least 0.8 mm. A maximum total thickness of up to 1.5 mm is possible, limited only by production time. A fourth machining step d) is then performed on the underside 5b of the blank 5, preferably by grinding, to expose the enamel 3, resulting in the through-decoration 2. A final polishing operation is then preferably performed to achieve a fully glossy polished surface and ensure good transparency of the enamel. Optionally, in step e), the upper surface 5a can be machined by grinding to obtain an enamel decoration perfectly flush with the substrate. Again, this machining can be completed by polishing. For flat parts, a satellite lapidary machine can be used to grind and polish the top and bottom surfaces in one operation.According to the invention, if the enamel layer has an opaque appearance before machining, the upper and / or lower surface can be machined with an inclined surface to obtain a gradation from translucent to opaque. It should be noted that the opaque, transparent or translucent appearance depends on the presence of pigments in the enamel and the thickness of the layer.

[0018] Optionally, one or both surfaces may have a finish such as a satin finish or laser texturing.

Claims

1. A method for manufacturing an article (1) comprising a through-decoration (2) filled with enamel (3) to form a so-called plicajour enamel, comprising the steps of: - obtaining a blank (5) defined by an upper surface (5a) and a lower surface (5b) opposite said upper surface (5a); - removing a portion of the blank (5) from the upper surface (5a) to form a decoration (2a) that does not penetrate to the lower surface (5b), or alternatively directly obtaining the blank (5) with the non-penetrating decoration (2a) in the previous step; depositing one or more layers of enamel (3) within said blind decoration (2a) and firing said enamel (3) after each layer; machining said lower surface (5b), preferably by grinding, to expose said enamel (3) and to produce an article (1) comprising said through-decoration (2) filled with said enamel (3); A method comprising:

2. 2. The method according to claim 1, further comprising a machining step, preferably by grinding off the enamel (3) of the upper surface (5a), to obtain an enamel decoration flush with the upper surface (5a), said further step being able to be carried out simultaneously with the step of machining the lower surface (5b).

3. 3. The method of claim 2, further comprising polishing the upper surface (5a) and / or the lower surface (5b) after the machining step and / or the further machining step.

4. 2. The method according to claim 1, wherein the blank (5) is made of a material having a melting point above 650°C.

5. 2. The method according to claim 1, wherein the deposition of one or more layers of enamel (3) is carried out by liquid spraying, by using a brush, or by sprinkling a powder.

6. 2. The method according to claim 1, wherein the number of layers of enamel (3) deposited is between 2 and 15, preferably between 3 and 10.

7. 2. The method according to claim 1, wherein during the step of depositing one or more layers of enamel (3), layers of enamel (3) of different colors are deposited and / or the color is varied within the same layer.

8. 3. The method according to claim 2, wherein the enamel (3) is machined according to an inclined plane during the machining step and / or during a further machining step to form a gradation of areas of higher or lower transparency.

9. The article (1) has an upper surface (5a) and a lower surface (5b) opposite to the upper surface (5a), and is provided with a through decoration (2) made of plicajour enamel having an enamel thickness of at least 0.5 mm, preferably at least 0.8 mm.

10. 10. The article according to claim 9, wherein the article (1) is an exterior part or a movement part of a watch.

11. 10. The article according to claim 9, wherein the article (1) is an exterior part of a watch.

12. 10. The article according to claim 9, wherein the article (1) is made of ceramic, sapphire or cermet.

13. 13. The article according to claim 12, wherein said article (1) is made of zirconium oxide.

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