HK1225931B - Method of producing a decorated element for a timepiece or piece of jewellery, and element made by the method - Google Patents

Description

Method for producing a decorative element for timepieces or jewelry and decorative element produced by the method

Technical Field

The present invention relates to a method for manufacturing at least one decorative element for a timepiece or jewelry.

The invention also relates to a decorative element obtained according to this manufacturing method.

Background Art

To decorate elements or parts of timepieces or jewelry, hot-enameling techniques can be used, particularly after a series of cells or partitions have been formed in the element or part. This traditional technique, known as "cloisonné enamel," is one of a variety of enamel techniques that include, among others, "grisaille enamel," dry marquetry, painted enamel, "openwork/filling enamel," "bass-taille enamel," "plique-à-jour enamel," relief enamel, and "paillonné enamel," to name the main techniques. The principle of this traditional decorative technique involves artificially forming a design formed by wire partitions, which are then filled with successive layers of transparent or opaque enamel on a metal or ceramic support. The raw materials of the vitreous substance known as enamel are primarily silica in the form of very pure sand, feldspar, pegmatite, chalk, lime, and sometimes kaolin, which are combined with metal compounds to give the enamel its color. This substance deposited on the surface of the component is fired until it melts and adheres to the metal or ceramic component. The process of forming the decoration through various manual steps is long and cannot be reproduced in the same way from one component to another, which is a disadvantage.

In the "cloisonné enamel" or partition wall technique, at least nine steps are typically required to create the decorative elements. In the first step, a drawing of the pattern must be created directly on paper or on a computer, in which case a full-size print of the drawing is also performed. In the second step, the decorative pattern is manually formed using wire on the drawing serving as a basis. In the third step, the drawing is reproduced on a metal or ceramic support, typically by hand engraving, mechanical engraving, or freehand carving. In the fourth step, the metal or ceramic support is enameled using a first transparent enamel layer. In the fifth step, the decorative pattern is applied to the enameled ceramic or metal support to form the "cloisonné enamel" or partition wall pattern. In the sixth step, the decorative pattern is bonded to the metal or ceramic support to secure the partition wall. In a sixth additional step, the decorative pattern fixed to the ceramic or metal support is leveled. The seventh step involves firing the enameled support with the bonded partition wall, so that the enamel melts and the partition wall is trapped in the enamel, resulting in a solid, hardened partition wall. In the eighth step, the enamelling operation is performed in several setting and firing stages. The ninth step consists of stony and polishing the enameled part. This constitutes a very large number of steps in this method of manufacturing a decorative element, which is a drawback.

It should also be noted that the aforementioned technology for producing decorative elements still presents several problems. These problems are, firstly, the manual production of the decorative elements and their geometry, placement, and retention. The decorative elements are metal wires or strips bent into simple geometric shapes. These wires or strips are held together by gluing, which is neither stable nor impermeable.

Swiss patent application No. 707533A2 describes a method for producing a watch dial decorated with embroidery. First, an applique etching is formed in a canvas or embroidery. Once the desired design has been punctured into a cover or replica sheet, powder is spread on the cover sheet. The design is then printed on the canvas to highlight it for the embroidery operation, which follows the printing step. Once the embroidery is complete, the decorated canvas is bonded to a carrier, such as a watch dial. This method also involves a very large number of steps for decorating the watch dial, which is a disadvantage. Furthermore, decorative objects with complex shapes cannot be formed using this method.

European Patent Application No. 2316299A1 describes a timepiece or piece of jewelry and a method for manufacturing the same. The timepiece or piece of jewelry comprises a metal base structure with a relief decoration and an elastomeric layer deposited on the surface of the structure using an adhesive layer. This decorative design is achieved by milling, chemical etching, laser engraving, or stamping. However, this method is limited in its ability to produce sufficiently fine decorative objects with complex shapes, which is a drawback.

European Patent Application No. 2806315A2 describes the formation of watch components such as colored dials or displays. To this end, an opaque silicon wafer is used as a base, onto which a first thin film of silicon nitride is deposited. A photosensitive resin mask is placed on the first film for photolithography. The illuminated portions of the resin are removed, and the first film is etched. Thereafter, a metal or ceramic layer is deposited. However, achieving sufficiently fine and complex decorative elements is difficult, which is a drawback.

Summary of the Invention

One object of the present invention is therefore to provide a method for manufacturing a decorative element for timepieces or jewellery which overcomes the above-mentioned drawbacks of the prior art in order to facilitate the reproducible manufacture of such a decorative element.

To this end, the invention relates to a method for manufacturing a decorative element for a timepiece or jewelry, comprising the features of the independent claim 1 .

Specific steps of the method for producing a decorative element are defined in dependent claims 2 to 12 .

One advantage of this method for producing decorative elements is that it allows the creation of three-dimensional decorative objects with complex shapes. The decorative objects can be produced on an industrial scale directly on metal, ceramic, or ceramic-metal objects (such as cermet). To improve adhesion to the decorative object, the object can be treated with a layer of metal, ceramic, or cermet from the same family as the decorative material. The decorative objects can be pre-drawn or pre-programmed on a computer, making it possible to create highly complex and reproducible decorative objects in large quantities. This reduces the number of steps required to produce the decorative elements. Using the "cloisonné" technique, only five production steps are required, and the resulting partition wall is impermeable.

One advantage of the method for producing decorative elements lies in the fact that the partitions, walls, or molds can be obtained on the substrate by, for example, selective laser or electron beam sintering or melting techniques performed on at least one metal or ceramic or ceramic-metal powder (such as enamel). The term "melting" is associated with metal powders, while the term "sintering" is associated with ceramic or ceramic-metal powders. Once the metal or ceramic or ceramic-metal powder partitions have been produced on the substrate, a filler material, such as enamel, is inserted into the partitions for the enamel application operation. For certain applications using cold enameling techniques, a thermosetting polymer containing a pigment can be used. Such a polymer may be an epoxy-type resin.

Advantageously, the LIGA method can also be used on metal or semiconductor substrates (such as silicon) to form walls or partitions or a mold on the substrate before inserting the filling material, which can be enamel or polymer or metal or ceramic alloy or porcelain. Subsequently, the substrate can be removed to obtain a decorative element consisting only of the partitions and the colored filling material arranged between the partitions.

Advantageously, once the filling material is partially or completely inserted into the partition wall or the mold, one or more additional selective sintering or selective melting operations may be performed on the powder to obtain a three-dimensional decoration that may or may not be confined within the filling material.

To this end, the invention also relates to a decorative element obtained according to the method for manufacturing a decorative element, comprising the features stated in independent claim 13 .

Particular embodiments of the decorative element are defined in dependent claims 14 and 15 .

BRIEF DESCRIPTION OF THE DRAWINGS

The method for manufacturing a decorative element for a timepiece or jewellery and the objects, advantages and characteristics of the decorative element obtained will become more apparent from the following description made with reference to the accompanying drawings, in which:

FIG1 shows a simplified view of a selective sintering or selective melting machine according to the invention for producing walls or partitions on watch parts or jewelry elements,

FIG2 shows a watch part or a jewelry element having walls or partitions made according to the invention, and

FIG3 shows a watch part or an element of jewellery after the enameling operation according to the invention.

DETAILED DESCRIPTION

In the following description, any technique known in the art for forming a decorative pattern for a watch or jewelry element will be mentioned only in a simplified manner.The decorative pattern involves walls or partitions or molds deposited on a substrate by a technique defined as micromachining technology.

Preferably, the present invention particularly relates to applying mass production processes to certain steps of the "cloisonné" and "openwork" enamel techniques. For both techniques, the enamel can be applied to create a three-dimensional pattern by first creating walls with metal wires or strips. These walls are preferably placed on a substrate, which can be metal or another material as described below.

The method for manufacturing a decorative element for a watch or jewelry comprises the following first essential step: creating a partition wall or wall or mold on a substrate by micromachining technology. The substrate can be a crystalline or amorphous metal material, a ceramic, a semiconductor, a porcelain gold, or any other material. As for ceramics, it involves aluminum oxide, zirconium oxide, magnesium oxide, boron nitride, silicon nitride, silicon carbide, aluminum titanate and aluminum nitride, or other types of ceramics. The substrate can also be made of quartz, glass, sapphire, corundum or other types of gemstones. The material of the mold or partition wall can be the same as that of the substrate. When the operation of applying enamel is carried out after the first step, the material used for the substrate and the material of the partition wall must be able to withstand the firing in the furnace during the application of the enamel.

The decorative pattern defined by the partition walls is first drawn or programmed in a computer, and the stored drawing or pattern data is sent to a micromachining machine to form the partition walls. Thereafter, another operation is performed to fill the partition walls with a filler material, which can be a thermosetting polymer, a metal alloy, a ceramic, a porcelain metal, or, preferably, an enamel containing a pigment. The enamel can be deposited or set either hot or cold. In the case of an enamel application operation, this operation will be briefly described below.

FIG1 illustrates one of the techniques for forming walls, partitions, or molds on a substrate for a watch or jewelry component. This technique involves selective laser sintering or selective laser melting a powder (especially a metal, ceramic, or ceramic-metal powder) on a substrate. The metal powder can be steel, nickel, nickel-chromium, nickel-chromium-molybdenum, titanium, copper, gold, or other metals or metal alloys. If enamel is subsequently applied, this type of metal material generally must have a higher melting point than the enamel.

The selective melting or selective sintering machine 1 essentially comprises a laser unit and a scanner 2 for generating a laser beam 3 directed toward a metal, ceramic, or ceramic-metal powder 5 arranged on a plate 8, on which a substrate 7' is initially disposed. The laser beam 3 is directed toward the powder along the lines of a stored pattern to be formed. As a result of the heating by the laser beam 3 as an energy source, a portion of the metal powder melts and agglomerates or solidifies to form a structural portion 7 of the pattern to be created on the substrate 7'.

Since selective melting of powder is typically performed in layers, once the laser beam 3 has scanned the entire surface of the powder 5 along the defined line, the plate 8 can be moved down one notch. Another layer of metal powder 5 can be pushed from another plate 4 in the powder reservoir by a powder feeder or a powder distribution device (such as a roller 6 or scraper above the plate 8). The laser beam 3 scans the new powder again, causing a portion of the powder 5 to agglomerate on the previous structure portion 7. The other plate 4 can also be moved up one notch to remove another portion of the powder 5 from the powder reservoir so that it can be pushed by the powder feeder in a subsequent step.

Of course, as an alternative to using a laser beam, it is also conceivable to perform a selective electron beam melting (SLM) operation or a selective electron beam sintering operation. It is also possible to use an additive fabrication machine to form a metal and/or ceramic and/or ceramic-metal layer, or a superposition of multiple metal and/or ceramic and/or ceramic-metal layers, in order to create a metal or ceramic or ceramic-metal (such as porcelain-metal) sandwich layer.

It should be noted that in the case of metal powder 5, it is deposited in thin layers (typically about 50 μm) on the substrate 7' of the component on the plate 8. These successive layers are selectively melted one after another to form the complex metal partition walls of the desired pattern. Depending on the particle size and the selective melting conditions used, i.e., the scanning speed and energy of the laser or electron beam 3, the precision of selective laser or electron beam melting ranges from 0.1 mm to 0.02 mm. This allows for very precise decoration of the component.

It should be noted that selective sintering can also be performed on a substrate, for example, for ceramic or porcelain powders. For example, selective laser sintering can be performed on yttria-stabilized zirconia-type ceramic powders. For such selective sintering, the ceramic powder may or may not include a binder, which may be a polymeric material. One type of binder may be methyl methacrylate, polyvinyl butyral, or methyl ethyl ketone (MEK). For metal powders, no binder is used, as the irradiated powder melts and subsequently solidifies.

In principle, in order to achieve selective melting or selective sintering of the powder on the substrate, at least one intermediate layer can also be formed on the substrate to ensure good bonding of the fused or sintered powder to the substrate material. Initially, a first enamel layer, for example white or transparent, can be formed on the metal substrate, on which ceramic or ceramic-metal powder is subjected to selective laser or electron beam sintering to obtain the mold or decorative partition wall. One or more PVD or electroplated metal layers can also be deposited, which can also serve as a base conductive layer for electroplated growth. Prior to the selective laser or electron beam melting operation, for example, of the metal powder, a low-temperature solder can also be melted at the surface of the substrate. Once the partition wall or mold has been formed and the filler material has been inserted, additional layers of metal or ceramic or ceramic-metal types can be added to create a three-dimensional pattern.

Once the pattern 7 is complete, the element with this pattern can be removed from the selective melting or selective sintering machine 1 by removing any unsolidified metal powder surrounding the pattern structure. In the three-dimensional view of FIG2 , this element, for example in the form of a watch dial, is shown with its pattern. Preferably, for components to be hot-enameled, it is conceivable to deposit an electroplated layer on the partition wall or mold to prevent oxidation during the hot-enameling process. This electroplated layer consists of a precious metal or metal alloy, such as 24k gold, fine platinum, fine rhodium, fine palladium, or any other precious metal or metal alloy.

Afterwards, the element with the created patterned walls or mold can be enameled. To do this, the spaces between the walls are filled with a glassy substance. The raw materials for this glassy substance are primarily silica, feldspar, pegmatite, chalk, lime, and sometimes kaolin, which are combined with metallic compounds to color the enamel. Once the walls of the element's pattern have been filled with the glassy substance, the enamel is fired in a furnace, for example, at temperatures approaching 800°C, fusing the enamel to the metal object. A decorative element in the form of a dial is shown in Figure 3.

Once the enamel application operation is complete, it is also conceivable to remove the substrate, for example metallic or ceramic or ceramic-metallic, or even made of a semiconductor material, by machining or selective dissolution operations. The decorative element obtained after this method thus comprises an enamel portion surrounded by a patterned structure.

Of course, once the pattern 7 has been completed on the substrate after the selective melting or selective sintering operation, it is conceivable to fill the resulting partition walls with a filling material other than enamel. In particular, thermosetting polymers (epoxy type), metals, ceramics, or other materials can be used as filling materials, which are placed in the partition walls in powder or liquid form before the curing or consolidation or polymerization operation. The filling material 7 can be selected from various colors to fill the partition walls, in order to create decorative elements.

Another technique for forming walls, partitions, or molds on a substrate for a watch or jewelry component is also conceivable. According to the present invention, the LIGA method (German for Lithographie, Galvanofomung und Abformung) can be used to form walls, partitions, or molds on a substrate. In this case, the substrate is preferably a semiconductor substrate, such as silicon or even gallium arsenide, which may have an upper conductive layer for electroforming operations. However, a metal substrate, typically made of copper, can also be used, which avoids the need for a conductive layer on the surface of the substrate.

A photosensitive resin is deposited on a substrate having a conductive layer on top. This photosensitive resin can be a polyimide (PMMA)-based resin, an octafunctional epoxidized phenolic resin designated SU-8 available from Shell Chemical Company, and a photoinitiator selected from triarylsulfonates. This resin can be photopolymerized by irradiation with ultraviolet (UV) light. However, it is also conceivable to use a resin sensitive to X-rays generated by a synchrotron, but this operation is too expensive for manufacturing molds or partitions on the substrate.

A mask outlining the pattern to be formed on the substrate of the element is placed on the resin. The mask can be a glass plate on which a masking layer with opaque and transparent portions is formed according to the pattern to be produced. Light irradiation, such as ultraviolet light, is directed onto the mask to irradiate the unmasked portions of the resin. When using this type of resin (negative photosensitive resin), the unirradiated portions can be removed by physical or chemical means. This allows the shape of the partition wall or mold to be defined in the removed portion of the resin.

It should be noted that a positive-type photosensitive resin can also be used with a mask comprising a masking layer having opaque and transparent portions depending on the pattern to be produced. This mask is the inverse of the mask used with negative-type resin. In this case, it is the irradiated portions of the resin that are removed.

Thereafter, an electroforming or electroplating operation is performed. At least one metallic material is grown from the conductive layer formed on the surface of the substrate within the openings in the resin. Once the thickness of the deposited metallic layer is sufficient to define the desired decorative pattern, the resin can be removed. Thereafter, the enamel can be applied immediately by inserting one or more glassy substances into the defined partition walls and firing them in a furnace. However, as mentioned above, different types of filler materials can also be used to fill the partition walls.

It should be noted that the metal material deposited by the LIGA process can be nickel or nickel-phosphorus alloys, or copper-based alloys, gold or even steel. In principle, any metal or metal alloy that can be deposited by electroplating methods, or even amorphous metals, can be used.

According to a technique very similar to that described with reference to the LIGA method, it is conceivable to use a low-temperature solder instead of the electroplating or electrodeposition operation in the partition walls formed in the resin. The solder can advantageously be fixed directly to the substrate (in the case of a substrate made of a metallic material) or to a conductive layer, such as a metal layer, at the surface of the substrate.

Preferably, the manufacture of decorative elements such as watch dials is sought through different techniques for forming decorative patterns on elements. For watch dial decorations, a filling material can be inserted into the mold or partition formed. This filling material can be a thermosetting polymer, a metal alloy, a ceramic, a porcelain gold or any other type of colored filling material. This type of filling material can be fixed in the partition at room temperature or at a temperature that must be lower than the melting point of the materials of the partition and the substrate. If the filling material is enamel, the dial with the glassy substance arranged in the partition must also be fired in a furnace at a relatively high temperature.

It should also be noted that an intermediate adhesive layer can be added to the substrate at each step of the manufacturing process, for example, to form a partition wall or mold. Subsequently, another adhesive layer can be added to the decorative element or partition wall with the filling material, thereby adding one or more additional decorative layers using one of the aforementioned techniques. The decorative layer can be a metal, ceramic, and/or ceramic-metal layer obtained by selective laser or electron beam sintering or melting of powder on a transparent or opaque enamel to form one or more two-dimensional or three-dimensional patterns in the enamel-applied structure. The substrate can also have hollow sections to improve the mechanical adhesion of the filling material between the partition walls.

During the selective firing or selective melting operation, it is conceivable to combine metal powder with ceramic or ceramic-metal powder. First, a first selective melting operation can be performed on the metal powder, followed by a filling operation with the filler material, and then a second selective sintering operation can be performed on the ceramic or ceramic-metal powder. One or more additional selective melting or selective sintering operations can be performed on the powders of the previous layer of the component to form a sandwich structure. Thus, by a series of fused or sintered powder layers, a two-dimensional or three-dimensional pattern can be formed on the filler material or also on the partition wall or mold. Of course, ceramic powder or ceramic-metal powder can be used in the first operation and metal powder in the second operation.

Based on the description given above, a person skilled in the art will be able to conceive of numerous variations of the method for producing a decorative element for a timepiece or jewellery, without departing from the scope of the invention as defined in the claims. The decorative element may also be a watch dial, a watch hand, or a date disc, or other watch components such as a seconds wheel, an oscillating weight or a back cover of a watch case.

Claims (15)

1. A method for manufacturing decorative elements for watches or jewelry, the method comprising the following steps: - Obtain the base (7'), - In a selective melting or selective sintering machine (1) using a laser beam (3) or an electron beam, or in an additive manufacturing machine for metals, ceramics, or ceramic-metal materials, a first powder on a substrate (7') is selectively melted or selectively sintered along the lines of a stored pattern to be formed to obtain a first mold or decorative partition. - Fill the first mold or decorative partition with at least one filler material. - Perform one or more additional selective melting or selective sintering operations on or in the filler material and/or on the first mold or decorative partition to obtain at least one additional mold or decorative partition. - The additional mold or decorative partition is filled with at least one filler material to obtain the decorative element. 2. The method of manufacturing a decorative element according to claim 1, characterized in that the first and/or additional mold or decorative partition is filled with a vitreous substance for applying an enamel operation, the enamel operation comprising firing the vitreous substance in a furnace to obtain the decorative element. 3. The method of manufacturing decorative elements according to claim 1, characterized in that, once the additional mold or decorative partition is filled with solidified filler material attached to the wall of the additional mold or decorative partition, machining or selective dissolution operations are performed to remove the substrate, which is metal, ceramic, or ceramic-metal material. 4. The method for manufacturing decorative elements according to claim 1, characterized in that the substrate is provided with at least one metal and/or ceramic and/or porcelain-gold layer in order to improve the adhesion of the substrate to the metal and/or ceramic and/or porcelain-gold powder during selective melting or selective sintering using a laser beam (3) or an electron beam. 5. The method for manufacturing decorative elements according to claim 1, characterized in that the first and/or additional molds or decorative partitions are obtained by continuous selective melting or sintering of multiple powder layers with a laser beam (3) or an electron beam, or by stacking multiple metal or ceramic or porcelain-gold layers in an additive manufacturing machine. 6. The method for manufacturing decorative elements according to claim 3, wherein the substrate is ceramic. 7. The method of manufacturing decorative elements according to claim 1, characterized in that the first and/or additional molds or decorative partitions are protected by an electroplating layer made of a precious metal or metal alloy to prevent oxidation during the hot enamel process. 8. The method for manufacturing decorative elements according to claim 1, wherein the first powder and the second powder used are any one of metal powder, ceramic powder, and ceramic-metal powder. 9. The method for manufacturing decorative elements according to claim 8, characterized in that the ceramic powder used is a ceramic powder with or without a binder. 10. The method for manufacturing decorative elements according to claim 8, wherein the ceramic-metal powder used is ceramic gold powder. 11. A method for manufacturing decorative elements for watches or jewelry, wherein the method comprises the following steps: - Obtain the base (7'), - In a selective melting or selective sintering machine (1) using a laser beam (3) or an electron beam, or in an additive manufacturing machine for metals, ceramics, or ceramic-metal materials, a first powder on a substrate (7') is selectively melted or selectively sintered along the lines of a stored pattern to be formed to form a first mold or decorative partition. - Fill the first mold or decorative partition with at least one filler material. - Deposit a layer of positive or negative photosensitive resin on or in the filler material and/or on the first mold or decorative partition; - Place the outline mask of the pattern to be formed on the photosensitive resin. - Irradiate the resin through the mask. - Remove the irradiated portion of the resin when the photosensitive resin is a positive photosensitive resin, or remove the unirradiated portion of the resin when the photosensitive resin is a negative photosensitive resin. - Fill the removed resin portion with metal to form another metal mold or decorative partition. -Remove all resin, and - Fill the additional mold or decorative partition with at least one filler material to obtain decorative elements. 12. The method of manufacturing decorative elements according to claim 11, wherein the additional mold or decorative partition is generated by growing at least one metallic material in the opening portion of the resin through an electroplating or electrodeposition operation. 13. A decorative element for a watch or jewelry, characterized in that the decorative element is obtained by the method according to any one of claims 1 to 12. 14. The decorative element according to claim 13, characterized in that the first and/or additional molds or decorative partitions are made of metal and the filler material is colored enamel, the color of which is different from one mold or decorative partition to another. 15. The decorative element according to claim 13, characterized in that the first and/or additional molds or decorative partitions are made of metal, and the filler material is a thermosetting polymer, metal, metal alloy, ceramic or porcelain gold, and the filler material has different colors from one mold or decorative partition to another.