METHOD FOR MANUFACTURING A WATCH COMPONENT

Description

Technical field of the invention

[0001] The present invention relates to a method for manufacturing a watch dial. Technological background of the invention

[0002] Numerous processes for manufacturing and decorating in relief on the surface of a mechanical part, such as a watch dial, are known in the prior art. Among all these known processes, several involve manufacturing the decorative elements separately from the mechanical part to be decorated, and then affixing these decorative elements to the mechanical part for which they are intended.

[0003] Another method for decorating a mechanical part such as a dial is known from European patent application EP 2 370 865 A1 filed by The Swatch Group Research and Development Ltd. This decoration method consists of: to obtain the mechanical part to be decorated; to make a mask of the type of a plate whose thickness is at least equal to the desired thickness of the decorative elements and in which openings are machined whose contours correspond to the shape of the decorative elements sought; to position the mask on the surface to be decorated of the mechanical part, so that the openings of the mask coincide with the locations of the mechanical part intended to receive the decorative elements; to place said at least one opening of the mask (4) against the place to be decorated in order to form at least one mold; to fill said at least one mold by injection with a metallic material brought to a temperature at least above its glass transition temperature Tg and then cooled so as to give this metal an amorphous structure to form the element; to remove the mask to reveal the decorative elements on the surface of the decorated mechanical part.

[0004] One advantage of this decoration process lies in its relative simplicity of implementation. Indeed, while in the case of many decoration processes the decorative elements are made separately from the mechanical part to be decorated, and only then fixed to this mechanical part, when a mask is used, the decorative elements are directly made and fixed to the mechanical part to be decorated in the same step of the process, which saves time.

[0005] One drawback of the decoration process using masks placed on the surface of the mechanical part to be decorated is the risk that the mask may not be in close contact with the surface. During the filling of the various molds, some of the filling material may leak onto the surface of the mechanical part, necessitating the disposal of some of these parts. This is particularly problematic when decorating watch dials, as such dials are expensive mechanical components.

[0006] Another drawback of this type of decoration is that the complex geometric shapes used to decorate the dial are difficult to produce and generally require very expensive handwork. Document EP 0 294 661 B1 shows a method for manufacturing a watch dial with a mosaic decoration. Summary of the invention

[0007] The present invention aims to remedy the problems mentioned above, as well as others, by providing a method for manufacturing a watch dial that avoids, in particular, transferring decorative elements to the dial's surface. The present invention also aims to provide a method for manufacturing a dial in which the decorative elements are integrated directly into the dial body, forming a monolithic component.

[0008] For this purpose, the present invention relates to a method for manufacturing a watch dial according to the attached claim 1.

[0009] According to special embodiments, the manufacturing process for a watch component according to the invention is characterized in that: the filling material is an amorphous metal or a partially amorphous metal; the amorphous or partially amorphous metal is a platinum alloy, a palladium alloy or a zirconium alloy; the material of the watch component is chosen from materials having a melting point higher than the Tg of the amorphous metal (metals, ceramics, glass, sapphire, diamond, mother-of-pearl, silicon, precious and semi-precious stones, etc.) the reassembled watch component is subjected to at least one of the following finishing operations: sandblasting, brushing, satin finishing, polishing, sunburst finishing or laser matting; the watch component is chosen from: a bezel, a case back, a bridge, a mainplate, an oscillating weight or a piece of jewelry.

[0010] The invention also relates to a watch dial obtained by implementing a manufacturing process according to the invention. Brief description of the figures

[0011] Other features and advantages of the present invention will become clearer from the following detailed description of an example of implementation of the method according to the invention, this example being given purely for illustrative purposes and not as a limitation, only in connection with the accompanying drawing on which: there figure 1 represents the different stages of the manufacturing process; the figure 2 is a top view of a watch dial obtained by implementing the manufacturing process according to the invention. Detailed description of an embodiment of the invention

[0012] According to the invention, one begins by obtaining a watch dial for step a). Of course, and not as claimed, the watch component manufactured can be of any type, such as a bezel, case back, bridge, mainplate, oscillating weight, or even a piece of jewelry. The only constraint on this watch component is that it must be made of a material whose mechanical properties are not altered within the temperature range involved in the process of the invention. In other words, the watch component must not deform, soften, or even melt during the decoration operations according to the invention.

[0013] Once equipped with the watch face 1, it is broken into several pieces 10 during the next step b). This operation can be carried out in a completely random way to obtain unique patterns later, or in a controlled way to obtain predetermined patterns.

[0014] According to one variant of the invention, already broken pieces such as waste or scrap can be used in place of the previously broken watch component.

[0015] The material used for dial 1 can be a metallic material such as steel, brass, aluminum, or titanium, but it can also be a so-called brittle material. A brittle material is defined as one that does not have usable plastic deformation, such as quartz, ruby, sapphire, glass, silicon, diamond, graphite, carbon, or a ceramic like silicon nitride and silicon carbide, or a cermet-type composite. It follows that a part made from such a material is very fragile and can be easily broken.

[0016] The material forming watch component 1 is chosen from materials having a melting point higher than the Tg of the amorphous metal used later in the process.

[0017] In step c), the pieces 10 of the dial 1 are transferred onto a support 2, such as a block or base, to create a desired pattern for reassembly. This pattern has gaps 11 between the different pieces. The dial pieces 10 are sized and positioned relative to each other so that at least one gap 11 is visible. These gaps 11 are used to allow the insertion of another material, which serves as a connecting and decorative element between the pieces of the dial 1.

[0018] Once the pieces 10 are placed on the support 2, the latter is transferred into a mold suitable for hot shaping and a metal preform 3 is placed on the dial pieces (step d).

[0019] According to the invention, the material used for the preform 3 and acting as a connecting element between the pieces 10 of the dial, is an amorphous or partially amorphous metallic material.

[0020] A partially amorphous material is defined as one capable of solidifying at least partially in an amorphous state. This means that when subjected to a temperature rise above its melting point, it locally loses all crystalline structure. This temperature rise is then followed by cooling to a temperature below its glass transition temperature, allowing it to become at least partially amorphous. This material can then be a metallic alloy.

[0021] According to one variant of the invention, the preform 3 is manufactured by compacting a mixture of powders (already amorphous metallic powder for example) using for example hot pressing or extrusion between the glass transition temperature Tg and the crystallization temperature Tx.

[0022] In the following step e), the mold comprising the base 2, the dial pieces 10, and the preform 3 is heated to a temperature above the glass transition temperature of the preform 3. A force F is then applied to the preform 3 via a piston 4 to fill the gaps 11 and obtain a reassembled dial 1'. This heating step involves heating the assembly to a temperature between the glass transition temperature Tg and the crystallization temperature Tx of the preform. At this temperature, the viscosity of amorphous metals decreases sharply, with the decrease in viscosity being temperature-dependent.

[0023] Once the preform 3 has reached the desired viscosity, it is pressed to fill the gaps 11 between the pieces 10 of dial 1 as visible in the figure 2 Obviously, the pressure exerted on the preform 3 depends on the metal or alloy used and its glass transition temperature Tg.

[0024] Once the expansion of the preform 3 within the gaps 11 is complete and the dial pieces 10 are joined together in their final position with the preform 3 filling the gaps 11, a cooling step is carried out. This cooling step is performed to solidify the preform 3 and form a reassembled dial 1' exhibiting increased toughness and a unique decorative pattern.

[0025] In a final step, the reassembled dial 1' undergoes at least one of the following finishing operations: sandblasting, brushing, satin finishing, or polishing. The reassembled dial 1' can also be cut to the desired final dimensions or its thickness adjusted on the back.

[0026] It goes without saying that the present invention is not limited to the embodiments just described, and that various simple modifications and variants can be envisaged by a person skilled in the art without departing from the scope of the invention as defined by the attached claims.

Claims

1. Method for manufacturing a timepiece dial comprising the successive steps of: - providing a dial (1); - breaking the dial (1) into a plurality of pieces (10) or using the pieces of an already broken dial; - depositing the pieces (10) on a support (2) and creating a desired pattern to be reassembled, the pattern having interstices (1) between the various pieces (10) of the dial (1); - transferring the support (2) into a mould adapted by hot forming and placing a preform (3) on the pieces (10) of the dial ; - heating the whole to a temperature higher than the vitreous transition temperature of the preform (3) and applying a force on the preform to fill the interstices (11) and obtain a reassembled dial (1'); - cooling the whole below the vitreous transition temperature of the preform (3) to form the reassembled dial (1'); - recovering the reassembled dial (1') and machining it to the required dimensions.

2. Manufacturing method according to claim 1, characterised in that the preform (3) is made of an amorphous metal or a partially amorphous metal.

3. Manufacturing method according to claim 2, characterised in that the amorphous or partially amorphous metal is a platinum alloy, a palladium alloy, a zirconium alloy, a gold or silver alloy.

4. Manufacturing method according to claim 2, characterised in that the material forming the dial (1) is selected from materials having a melting temperature higher than the Tg of the amorphous metals such as metals, ceramics, glass, sapphire, diamond, mother-of-pearl, silicon, precious and semi-precious stones.

5. Manufacturing method according to one of claims 1 to 4, characterised in that the reassembled dial (1') is subjected to one at least of the following finishing operations: sanding, brushing, sunray brushing, satin finishing, polishing or laser matte finishing.

6. Timepiece dial characterised in that it is obtained by implementing a manufacturing method according to claims 1 to 5.