METHOD FOR THE THREE-DIMENSIONAL DECORATION OF A SUBSTRATE FOR THE MANUFACTURING OF A CLADDING PART

Description

Technical field of the invention

[0001] The invention falls within the field of decoration of watch parts, jewelry or fashion articles, and in particular the manufacture of dress parts.

[0002] More specifically, the invention relates to a three-dimensional decoration method for a substrate in order to create a decorative component. This method can be advantageously applied to any decorative component in the fields of watchmaking, jewelry, fashion items such as leather goods, eyewear, writing instruments, or portable electronic devices. Technological background

[0003] There are many processes for creating relief decorations on a substrate surface to form a finishing piece, such as a dial, a plate, a bridge, a gear train, an oscillating weight, a bezel, a case, links of a bracelet or a clasp of a bracelet, in the field of watchmaking.

[0004] Among these processes are those that generate a mask on a substrate. The mask has openings whose contours correspond to the shape of the desired decorative elements. These openings are filled with a material that constitutes the decorative elements, and then the mask is removed. Document EP3839659A describes such a process. It consists first of preparing the part by defining the thickness and contour of the desired decorative element, and then applying a masking coating to the surface to be decorated. The thickness of this coating is at least equal to that of the element to be created. One or more cavities are made in this coating that correspond exactly to the contour of the decorative element, thus defining a volume with the surface of the part. This volume is then filled with a filler material to form the decorative element, and finally, the masking coating is removed, leaving the decorative element integrated into the surface of the part.

[0005] Although simple, this process has several drawbacks. In some cases, the mask may not be in close contact with the substrate surface, which can lead to problems with respecting the manufacturing tolerances of the decoration.

[0006] Another drawback is that this method requires that the application of decorative elements not damage the mask, otherwise manufacturing tolerances would be exceeded, and that the mask can be removed without damaging the substrate or the decorations. This method therefore offers very little freedom regarding the materials available for creating the substrate and decorations. Summary of the invention

[0007] The invention solves the aforementioned drawbacks by proposing a solution that ensures compliance with manufacturing tolerances for decorations and guarantees that the mask will remain in place when decorative elements are deposited and that the integrity of the substrate and decorations will be maintained when the mask is removed.

[0008] To this end, the invention relates to a three-dimensional decoration method for a substrate in order to produce a decorative part comprising the steps of: Deposition of at least one base layer of enamel on a ceramic substrate surface; firing of the substrate covered with the base layer; engraving of the base layer according to a predefined decorative pattern so as to generate one or more blind cavities extending between a background formed by the substrate and an opening formed by the base layer; deposition of a decorative layer of ceramic and / or metallic material on the base layer and the cavities so as to fill said cavities in order to form decorative elements; surfacing of the decorative layer so as to remove all of said layer deposited on the base layer; tribofinishing of the substrate and the base and decorative layers so as to remove all of the base layer.

[0009] In particular embodiments, the invention may further comprise one or more of the following features, taken individually or in all technically possible combinations.

[0010] In certain implementation methods, the base layer is surfaced following the baking step.

[0011] In certain implementation methods, the decorative layer is deposited in such a way that, in the cavities, it has a thickness greater than or equal to the thickness of the decorative elements at the end of the process.

[0012] In certain implementation methods, the base layer is made of borosilicate enamel.

[0013] In certain implementation methods, the base layer is made of sodium borosilicate enamel.

[0014] In particular implementation methods, during the baking stage the temperature to which the substrate covered with the base layer is subjected is between 500°C and 1500°C, preferably approximately equal to 1000°C. Brief description of the figures

[0015] Other features and advantages of the invention will become apparent from the following detailed description, given by way of non-limiting example, with reference to the accompanying drawings in which: THE figures 1a to 1f schematically represent a section view of the steps in carrying out a substrate decoration process for the production of a cladding part according to the preferred embodiment of the invention.

[0016] Note that the figures are not necessarily drawn to scale for reasons of clarity. Detailed description of the invention

[0017] The present invention relates to a method of three-dimensional decoration of a substrate 11 in order to produce a covering piece 10, as shown in successive figures 1a to 1f.

[0018] The process first involves a step of depositing at least one base layer 12 of enamel onto a coating surface 110 of a substrate 11 made of ceramic, as shown in the figure 1a The cladding surface 110 is intended to be visible to a user once the cladding part 10 has been produced. Preferably, the base layer 12 is deposited over the entire cladding surface 110.

[0019] In the preferred embodiment of the invention, the base coat 12 is made of borosilicate enamel, in particular sodium borosilicate enamel, for reasons that are described in detail later in the text. The base coat 12 can be deposited by dipping, spraying, or brush application. In this text, for the sake of simplicity and readability, the singular form is used when referring to the base coat 12; however, the base coat 12 may be composed of a stack of layers.

[0020] Advantageously, the substrate 11 can be made of any dense ceramic, such as zirconia, alumina, yttrium aluminum garnet, also known by the acronym "YAG" meaning Yttrium Aluminium Garnet in sapphire or a mixture of these elements.

[0021] The base layer 12 and the substrate 11 are then baked in an oven at a temperature between 500 and 1500 degrees Celsius, preferably at 1000 degrees, so as to cause the base layer 12 to melt and adhere chemically to the substrate 11. Thanks to its composition, the adhesion of the base layer 12 to the substrate 11 is guaranteed following this step.

[0022] The base layer 12 is preferably surfaced after the firing stage in order to flatten its visible surface and even out its thickness. Indeed, as the figure 1aIf the representation is exaggerated, the base layer 12 is likely to exhibit a variation in thickness. In particular, the surface of the base layer 12 may display a series of depressions and bumps due to a surface tension phenomenon occurring during the firing of the base layer 12, and the thickness of the base layer 12 may be greater in the center of the cladding surface 110 than at its periphery due to the wettability of said layer. Furthermore, if the cladding surface 110 does not extend horizontally, i.e., if it forms a slope, the base layer 12 may tend to flow, during firing, in the direction of the slope, and thus generate an excess thickness, under the effect of gravity and due to its viscosity when hot.

[0023] The surface treatment of the base layer 12 is preferably carried out by mechanical abrasion, for example by grinding or sanding. The result of this step is shown schematically on the figure 1b .

[0024] The base layer 12 is subsequently engraved according to a predefined decorative pattern. More specifically, this engraving step aims to generate one or more blind cavities 120 in the base layer 12 in order to house decorative elements 130 in relief, as discussed in more detail later in the text. The cavities 120 extend between a background formed by the substrate 11 and an opening formed by the base layer 12, as visible on the figure 1c The surfacing step, following which the visible surface of the base layer 12 is flattened, allows control of the manufacturing tolerances of the cavities 120.

[0025] Advantageously, the cavities 120 can also extend into the substrate 11, as shown in the figures 1c to 1f This feature further increases the adhesion of the decorative elements 130 in the substrate 11.

[0026] Preferably, the engraving step is carried out by laser, but can be carried out by any suitable technical solution, for example by mechanical machining.

[0027] Next, a decorative layer 13 is deposited on the base layer 12 and in the cavities 120, as shown in the figure 1d Such a decorative layer 13 can be deposited by spraying, pressing, thermal and plasma spraying, or slip deposition, depending on the material intended to constitute the decorative layer 13. In particular, the decorative layer 13 can be made of a ceramic material, for example, an enamel such as a borosilicate enamel or a feldspar, and / or of a metallic material. In this text, the term "metallic material" refers to any metallic alloy, any pure metal, or any metallic composite.

[0028] The material constituting the decorative layer 13 advantageously has a melting point lower than the glass transition temperature of the material constituting the base layer 12, so that the base layer 12 is not damaged during the deposition of the decorative layer 13. For example, the melting temperature of the material constituting the base layer 12 is below 600 degrees Celsius.

[0029] The decorative layer 13 is deposited so that it has, in the cavities 120, a thickness greater than or equal to the desired thickness of the decorative elements 130 at the end of the process.

[0030] A surfacing step is implemented after the application of the decorative layer 13 in order to remove all of said decorative layer 13 deposited on the base layer 12, as shown in the figure 1eSuch a surface finishing operation is advantageously carried out by mechanical abrasion, for example by grinding or sanding.

[0031] Once the decorative layer 13 is present only in the cavities 120, a tribofinishing step is implemented so as to remove the entire base layer 12 and to form the cladding piece 10. Advantageously, thanks to the material of the base layer 12, it is removed very easily and quickly by the tribofinishing step, without the abrasive elements uncontrollably damaging the cladding surface 110 of the substrate 11 or the decorative elements 130 formed by the remnants of the decorative layer 13.

[0032] There figure 1fschematically illustrates this trim piece 10 and the potential effects of the tribofinishing step on the decorative element 130. In particular, the sharp angles of the decorative element 130 can be rounded by the abrasion caused during the tribofinishing step.

[0033] The material of the decorative layer 13 is chosen so as to better withstand the tribofinishing stage than the base layer 12, the latter having a sacrificial purpose.

[0034] More generally, it should be noted that the implementation and realization methods considered above have been described as non-limiting examples, and that other variants are therefore conceivable.

Claims

1. Method for the three-dimensional decoration of a substrate (11) to produce an external part (10), which method comprises the steps of: - depositing at least one enamel base layer (12) on an external surface (110) of a ceramic substrate (11); - firing the substrate (11) covered with the base layer (12); - etching the base layer (12) in a predefined decorative pattern so as to generate one or more blind cavities (120) extending between a bottom formed by the substrate (11) and an opening formed by the base layer (12); - depositing a decorative layer (13) of ceramic material and / or metallic material on the base layer (12) and the cavities (120) so as to fill said cavities (120) in order to form decorative elements (130), the material of the decorative layer (13) being chosen such that its melting point is below the glass transition temperature of the material constituting the base layer (12); - surfacing the decorative layer (13) so as to remove all of said layer deposited on the base layer (12); - tribofinishing the substrate (11), the base layer (12) and the decorative layer (13) to remove the entire base layer (12).

2. Method according to claim 1, wherein the base layer (12) is surfaced after the firing step.

3. Method according to one of claims 1 or 2, wherein the decorative layer (13) is deposited so that its thickness in the cavities (120) is greater than or equal to the thickness of the decorative elements (130) at the end of the method.

4. Method according to one of claims 1 to 3, wherein the base layer (12) is made of borosilicate enamel.

5. Method according to claim 4, wherein the base layer (12) is made of sodium borosilicate enamel.

6. Method according to one of claims 1 to 5, wherein during the firing step, the temperature to which the substrate (11) covered with the base layer (12) is subjected is between 500°C and 1500°C, preferably substantially equal to 1000°C.