Enamel engraving and texturing method

Abstract

To develop a method for engraving and texturing an enamel capable of overcoming drawbacks of enamel engraving which is not widely used since it requires a mastery of the engraving technique to avoid scratching an enamel surface or altering its color.SOLUTION: A method for engraving and texturing an item (1) including a decoration (2) filled at least partially with an enamel (3) includes a step of laser ablation using a femtosecond laser or a picosecond laser onto a surface of the enamel (3) and / or within the enamel (3) to form a structure (7).SELECTED DRAWING: Figure 4A-4C

Description

[Technical Field]

[0001] The present invention relates to a method for engraving and patterning an article with an enamel decoration, for example a plique-à-jour enamel decoration.The invention further relates to a method for producing an article and to the article obtained by this method. [Background technology]

[0002] Several ancient techniques can be used to decorate translucent stone or glass paste. Many intaglios were made in ancient times with semi-precious stones or glass paste. The decoration is therefore obtained by hand cutting and polishing, and sometimes by shaping the glass paste. Most of the finds are decorated on the top surface, and in rare cases also on the underside, creating a holographic effect.

[0003] In-material engraving has been used in the watch industry for many years. It can be used, for example, to create anti-counterfeit markings or to incorporate decorative filigree into sapphire crystal. In-material engraving can also be used to customize ornaments made from crystal or polycarbonate.

[0004] To date, enamel engraving is not widely used because it requires skill in the engraving technique to avoid damaging the enamel surface or altering its color. Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to develop a method for engraving and patterning enamel that overcomes the above-mentioned drawbacks. [Means for solving the problem]

[0006] This method can be used for any enamel decoration, especially for plique-à-jour enamel decoration, i.e., openwork enamel decoration, in which light shines through the transparent or translucent enamel, creating the effect of a miniature stained-glass window. More specifically, this method can be applied to plique-à-jour enamel decorations with a thickness of 0.5 mm or more to reduce the brittleness of the enamel, which is especially important for enamel decorations subjected to high stresses, such as watch bezels and other exterior watch components.

[0007] More specifically, the present invention relates to a method for engraving and patterning an article with a decoration at least partially filled with enamel, said method comprising a step of laser ablation using a femtosecond or picosecond laser on the surface of the enamel and / or inside the enamel to form structures.

[0008] The engraving and texturing method of the present invention allows for laser ablation with controlled surface finish and limited color change to the enamel.

[0009] Upstream of this engraving and patterning method, plique-à-jour enamel decorated articles can be produced using manufacturing methods that allow for the rapid deposition of thick layers of enamel, leading to low-cost mass production with increased enamel robustness.

[0010] For this purpose, a method for manufacturing an article with an openwork decoration at least partially filled with enamel to form a so-called plique-à-jour enamel is proposed, which method comprises an engraving and patterning step, before or during which: obtaining a blank defined by an upper surface and a lower surface opposite the upper surface; removing a portion of the blank from its upper surface to form a decoration that does not penetrate to the lower surface or 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 is deposited; machining the underside, preferably by grinding, to expose the enamel and thereby produce an article with an enamel-filled openwork decoration; Includes:

[0011] 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.

[0012] 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.

[0013] The clear enamel decoration with engraving creates a depth that is impossible to achieve today. [Brief explanation of the drawings]

[0014] [Figure 1A] 3A-3C show the steps of a first alternative embodiment of a method for manufacturing an article with enamelled decoration, namely a bezel, according to the invention. [Figure 1B] 3A-3C show the steps of a first alternative embodiment of a method for manufacturing an article with enamelled decoration, namely a bezel, according to the invention. [Figure 1C] 3A-3C show the steps of a first alternative embodiment of a method for manufacturing an article with enamelled decoration, namely a bezel, according to the invention. [Figure 1D] 3A-3C show the steps of a first alternative embodiment of a method for manufacturing an article with enamelled decoration, namely a bezel, according to the invention. [Figure 1E] 3A-3C show the steps of a first alternative embodiment of a method for manufacturing an article with enamelled decoration, namely a bezel, according to the invention. [Figure 1F]1A and 1F show steps of a first alternative embodiment of a method for manufacturing an article, i.e., a bezel, with an enameled decoration according to the present invention. Each figure shows a schematic cross-sectional view of a portion of the article or blank and a three-dimensional view of a portion of the article or blank. The three-dimensional views in FIGS. 1A and 1F are views from above the blank or article, respectively, while FIGS. 1B to 1E show views from below the blank.

[0015] [Figure 2] FIG. 10 is a three-dimensional view of a bezel manufactured by a manufacturing method according to a first alternative embodiment.

[0016] [Figure 3A] 5 shows five steps of a second alternative embodiment of a method for manufacturing an article with an enameled decoration, namely a vibrating weight, according to the invention. [Figure 3B] 5 shows five steps of a second alternative embodiment of a method for manufacturing an article with an enameled decoration, namely a vibrating weight, according to the invention. [Figure 3C] 5 shows five steps of a second alternative embodiment of a method for manufacturing an article with an enameled decoration, namely a vibrating weight, according to the invention. [Figure 3D] 5 shows five steps of a second alternative embodiment of a method for manufacturing an article with an enameled decoration, namely a vibrating weight, according to the invention. [Figure 3E] 5 shows five steps of a second alternative embodiment of a method for manufacturing an article, i.e., a vibrating weight, with an enamel decoration according to the invention, in which each figure shows a schematic cross-section of a portion of the article or blank and a three-dimensional view of a portion of the article or blank.

[0017] [Figures 4A-4C] 4A to 4C are schematic cross-sectional views of an article illustrating the method of engraving and patterning the article with an enamel decoration, for example obtained by a first alternative embodiment of the manufacturing method according to the invention.

[0018] [Figures 5A-5C]Figures 5A to 5C are schematic diagrams of the steps for engraving and patterning enamel decoration by laser ablation. In Figure 5A, engraving is performed on the surface of the enamel, while in Figure 5B, engraving is performed inside the enamel. In Figure 5C, engraving is performed on the side opposite to the point of laser beam incidence. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present invention relates to a method for engraving and patterning enameled articles on an object. 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 the manufacture of articles subject to high stresses, such as exterior components. The article may also comprise a movement component, such as an oscillating weight. The invention will be described more specifically below with respect to a bezel and an oscillating weight.

[0020] This engraving and patterning method can be used for any enamelling. The decoration may be openwork or not. The decoration may be completely filled with enamel or may be filled with enamel and other materials, such as luminescent materials. In the case of openwork decorations that are at least partially filled with enamel, this is called plique-à-jour enamel decoration.

[0021] The engraving and texturing method according to the present invention is carried out by laser ablation into the enamel or on the surface of the enamel. Note that the term "engraving" is used somewhat imprecisely to refer to the formation of recesses typically a few tenths of a millimeter deep, while the term "texturing" is used for shallower engravings, down to a few hundredths of a millimeter deep. For simplicity, the term "engraving" will be used hereinafter to refer generally to either engraving or texturing.

[0022] To perform these engravings, very short pulsed lasers are used, the order of magnitude of which can range from picoseconds to femtoseconds. Typically, values ​​range from 250 to 500 femtoseconds.

[0023] Near-infrared wavelengths, i.e., wavelengths between 700 and 2500 nm, and green wavelengths, i.e., wavelengths between 510 and 560 nm, can be used. UV lasers with wavelengths between 200 and 400 nm can also be used, and this technique is particularly suitable for fine engraving.

[0024] In-enamel engraving is achieved by focusing the beam 8 on the enamel 3 to create a matrix of impacts, as shown in Figure 5B, while surface engraving requires focusing close to the surface to remove (ablate) material, as shown in Figure 5A. Typically, for in-enamel engraving, the wavelength is 1030 nm, i.e., in the near-infrared range, and for surface engraving, the wavelength is 515 nm, i.e., in the green range. For UV lasers, the wavelength is usually 355 nm.

[0025] Typically, the beam energy is between 10 μJ and 30 μJ and the frequency is between 200 KHz and 1000 KHz.

[0026] In the case of enamel surface engraving, the top surface of the part can be engraved directly from above. However, the bottom surface can also be engraved using a "bottom-up" technique. This method involves passing a transparent material without interaction and focusing the beam 8 on the bottom surface to remove material, as illustrated in Figure 5C. In the case of translucent / transparent enamel, engraving on the bottom surface creates a depth effect from above or a hologram. In the case of bottom engraving, additional materials, especially luminescent materials, can be added to enhance the depth effect. In the case of laser ablation on the top surface, a decoration made of another material, such as lacquer, inlaid metal, or another enamel, can then be deposited. For example, a transparent enamel matrix can be created, and then an opaque enamel can be deposited within it.

[0027] Different positions inside or on the surface of the enamel 3 are shown in Figures 4A to 4C. In Figures 4A and 4C, an engraving 7, also referred to as a structure below, is made on one of the faces of the enamel 3 within the decoration 2, which in the example shown is a through-decoration. If the engraving is made on the surface, the structure can be filled with material 4, which can be, for example, a luminescent material. It can also be another enamel, for example, an enamel with a different color or opacity. In Figure 4B, the engraving 7 is made inside the enamel 3. If the engraving is made between the deposition of the various layers of enamel 3 during the manufacturing method of the enamel decoration, the structure 7 can be filled with material 4. If the engraving 7 is made after the enamel layers have been deposited, the engraving simply forms a structure inside the enamel.

[0028] Before or during engraving and patterning, the article with enamel decoration can be manufactured using various methods. In the following, manufacturing methods are described for two preferred alternative embodiments that allow the production of plique-à-jour enamel decoration with an enamel thickness of 0.5 mm or more in short cycle times. It is understood that other manufacturing methods are also possible.

[0029] The manufacturing method described below 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.

[0030] A manufacturing method according to one alternative embodiment is shown in five steps a) to e) for an oscillating weight in Figures 3A to 3E. In the first step a), an undecorated article, called a blank 5 or substrate, is obtained. The blank 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-through decoration 2a is formed on the upper surface 5a. The non-through decoration can be formed, for example, by laser ablation. Optionally, if a blank with the non-through decoration 2a is obtained directly in step a), for example, this step b) can be omitted. In the third step c), an enamel 3 is deposited on the non-through 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 sprinkling 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. Next, a fourth machining step d) is 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 a perfectly flush enamel decoration 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 top and / or bottom surfaces can be machined with an inclined plane to obtain a gradation from translucent to opaque. It should be noted that the opaque, transparent or translucent appearance depends on the presence of pigment within the enamel and the thickness of the layer.

[0031] Another alternative manufacturing method is shown in Figures 1A to 1E and 2 for a watch bezel in six steps a) to e). The manufacturing method is essentially the same, except that a luminescent material is deposited on the upper surface 5a after depositing the enamel layer to form a back-illuminated plique-à-jour enamel decoration. In this method, the lower surface 5b is the surface intended to be visible during use. For this reason, the lower surface 5b is shown in an upper position in the figures. However, it should be noted that in practice, the upper surface 5a is in an upper position during the enamel layer deposition step to facilitate deposition without the risk of the enamel layer running off.

[0032] Steps a, b, and c are the same as above. In the fourth step d), after the decoration is at least partially filled with enamel and fired, a layer of material 4, i.e., luminescent material, is deposited on the enamel 3, i.e., from the top surface 5a of the blank. For example, the luminescent material can be Super-LumiNova®, a phosphorescent pigment in a lacquer or adhesive. This material offers a wide range of luminescent colors, including blue, green, purple, white, yellow, orange, and pink. In the fifth step e), a protective layer 6, such as lacquer, is deposited on the layer of luminescent material 4. Next, a sixth machining step f) is performed on the bottom surface 5b of the blank 5, preferably by grinding, to expose the enamel 3, resulting in an openwork decoration 2 illuminated from the inside by the luminescent material 4. A final polishing operation is then performed to achieve a completely glossy finish and ensure good transparency of the enamel. The resulting bezel is shown in Figure 2.

[0033] For both of the above alternative embodiments, the engraving and patterning steps can be performed during the manufacturing method, for example between the enamel layer deposition and firing steps.

[0034] Finally, for both alternative embodiments of the method, one or both surfaces can optionally be subjected to a finishing process such as supercalendering in addition to laser ablation for engraving and patterning in accordance with the present invention.

Claims

1. A method for engraving and patterning an article (1) comprising a decoration (2) at least partially filled with enamel (3), comprising a step of laser ablation using a femtosecond or picosecond laser on the surface of and / or inside the enamel (3) to form structures (7).

2. 2. The engraving and patterning method according to claim 1, which concerns an openwork (2) that is at least partially filled with enamel (3) to form a so-called plique-à-jour enamel.

3. 2. The engraving and texturing method according to claim 1, comprising the step of filling said structure (7) with a material (4).

4. 2. The engraving and texturing method according to claim 1, wherein the wavelength of the laser is in the near-infrared range, i.e. between 700 nm and 2500 nm, in the green range, i.e. between 510 nm and 560 nm, or in the ultraviolet range, i.e. between 200 nm and 400 nm.

5. 2. The engraving and texturing method according to claim 1, wherein the structure (7) in the enamel (3) is obtained by focusing a laser beam (8) in the enamel (3) and generating a matrix of impacts, while the structure (7) on the surface requires focusing the laser beam (8) close to the surface.

6. 6. The engraving and texturing method according to claim 5, wherein the laser beam (8) passes through the entire enamel (3) and forms a structure (7) on the surface opposite the point of incidence of the laser beam (8).

7. 5. The engraving and texturing method according to claim 4, wherein for the internal structure (7) of the enamel (3), the wavelength of the laser is in the near-infrared range, and for the surface structure (7), the wavelength of the laser is in the green range.

8. 1. A method for manufacturing an article (1) comprising an openwork (2) at least partially filled with enamel (3) to form a so-called plique-à-jour enamel, comprising the steps of engraving and patterning according to claim 2, before or during said steps of engraving and patterning: - 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 its upper surface (5a) to form a decoration (2a) that does not penetrate to its lower surface (5b) or directly obtaining the blank (5) with a non-penetrating decoration (2a) in a previous step; depositing one or more layers of enamel (3) within said blind decoration (2a) and firing said enamel (3) after each layer is deposited; machining said lower surface (5b), preferably by grinding, to expose said enamel (3) and thereby produce said article (1) with said openwork (2) filled with said enamel (3); A manufacturing method comprising:

9. 9. The method of claim 8, wherein the lower surface (5b) is the surface intended to face an observer during use, and the method comprises the steps of depositing a layer of luminescent material on the enamel (3) after the step of firing the enamel (3) and depositing a protective layer (6) on the layer of luminescent material before the step of machining.

10. 9. A method according to claim 8, wherein the blank (5) is made from a material having a melting point above 650°C.

11. 9. The method according to claim 8, wherein the deposition of one or more layers of enamel (3) is carried out by liquid spraying, by using a brush or by dusting with a powder.

12. 9. A method according to claim 8, wherein the number of layers of enamel (3) deposited is between 2 and 15, preferably between 3 and 10.

13. 9. A method according to claim 8, wherein during the step of depositing one or more layers of enamel (3), layers of enamel (3) of different colours are deposited and / or the colour is varied within the same layer.

14. An article (1) comprising a decoration (2) made of enamel (3), said decoration (2) comprising a structure (7) on the surface and / or in the interior of said enamel (3).

15. 15. An article (1) according to claim 14, characterized in that said structure (7) is filled with a material (4), said material (4) being other enamels or a material different from the enamel (3).

16. 16. An article (1) according to claim 15, comprising an openwork (2) made of plicajour enamel, the thickness of the enamel being greater than or equal to 0.5 mm, preferably greater than or equal to 0.8 mm.

17. 17. The article (1) according to claim 16, wherein the decoration (2) comprises a layer of luminescent material covering the enamel (3).

18. 18. The article (1) according to claim 17, wherein the article (1) is an exterior part or a movement part of a watch.

19. 15. The article (1) according to claim 14, wherein said article (1) is made of ceramic, preferably zirconium oxide, sapphire or cermet.

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