Patent Application
20230015564
This application claims priority to European Patent Application No. 21186468.1 filed Jul. 19, 2021, the entire contents of which are incorporated herein by reference.
The present invention relates to an article obtained by multi-compression of ceramics and/or cermets. It relates more particularly to a watch component such as a bezel, produced by compression of ceramic and/or cermet materials of different colours with a colour forming a decoration of the watch component.
Ceramic or cermet watch components are generally obtained by a method for injecting or compressing a material followed by sintering. These components often have decoration, such as indexes and numbers for a bezel, which is of distinct colour from the rest of the component. The elements of the decoration are generally added by soldering or gluing on the blank resulting from the sintering. This mechanical assembly between the blank and the decorative elements can be costly and complicated to implement.
An alternative to this mechanical assembly consists, as described in document EP 2 746 243, in impregnating part of the green body before sintering with a solution comprising a metal acting as a pigment. However, this method has the disadvantage that it is difficult to obtain a uniform colour in the mass of the coloured part.
The object of the present invention is to overcome the aforementioned disadvantages by proposing a new method of multi-material compression of distinct colours, with a subsequent step of machining the decoration in one of the colours.
To this end, the present invention relates to a manufacturing method comprising a laser ablation step to produce the decoration in one of the colours.
More specifically, the invention relates to a method for manufacturing by compression a cermet and/or ceramic multi-coloured article with a relief decoration, said method comprising the following steps:
Advantageously, the method further comprises another machining step before and/or after the sintering step to dimension the green body and/or the blank respectively.
The present invention also relates to the ceramic and/or cermet article resulting from the manufacturing method. The article according to the invention includes at least two distinct materials that differ by their colour, more generally by their aesthetic appearance. According to the invention, the decorated article is made in one piece without discontinuity between the decoration and the rest of the article, unlike an article decorated by adding the elements of the decoration to the article by soldering or gluing. According to the invention, the decoration has a distinct colour from the rest of the article with a uniform colour in the mass for each colour.
Other features and advantages of the present invention will appear in the following description of a preferred embodiment, shown by way of non-limiting example with reference to the appended drawings.
The present invention relates to a manufacturing method by compressing an article made with at least two distinct materials which are either a cermet or a ceramic. The term “distinct materials” means materials that differ in their aesthetic appearance, and in particular their colour. This results in differences in chemical compositions. It can be the same base material with different pigments to change the colour or different base materials. By way of example, it may be the same base material of zirconium oxide with, on the one hand, a black pigment to obtain a black material and, on the other hand, alumina to obtain the colour white. More generally, the ceramics can be nitrides, carbides and/or oxides. Similarly, cermets may include a ceramic phase including carbides, nitrides and/or oxides and a phase of a metallic binder selected, for example, from precious elements such as ruthenium, rhodium, palladium, osmium, iridium, platinum, gold and silver.
The article according to the invention can be a decorative article such as a constituent element of watches, jewelry, bracelets, etc. In the watchmaking field, this article can be an external component such as a middle part, a back, a bezel, a bezel insert, a push-piece, a crown, a bracelet link, a buckle, a dial, a hand, a dial index, etc. It can also be a component of the movement such as an oscillating mass, a plate, etc. By way of illustration, the article is a bezel 1 made with two ceramics of different colours, for example black and white, with a colour which forms the background and another colour which forms the decoration 8 as shown in
The article is made by compressing different materials to form a green body and by sintering said green body. The manufacturing method is illustrated below for an article comprising two distinct materials, but it could be an article comprising 3, 4, etc. different materials. Similarly, it is illustrated for an article with a decoration of the same colour when there could be decorations of different colours.
The manufacturing method includes the following steps with reference to
The laser ablation machining step can be carried out before sintering, that is to say on the green body, or after sintering, that is to say on the blank.
In the presence of more than two materials of different colours, the different materials can be hollowed to draw decorations of different colours. Thus, at least a third cermet or ceramic material of a distinct colour from those of the first and second material is provided. This third material is compressed on the second material in the same compression tool or in another compression tool. The green body is then sintered. The decoration in this third material is produced by laser engraving by hollowing this material to at least the second material to form a decoration standing on the second material. The third material can also be hollowed to the first material to create a decoration standing on the first material. The third material can also be hollowed over one part to the second material and over another part to the first material to produce a decoration standing, for one part, on the first material, and for another part, on the second material.
The laser ablation is preferably carried out with a pulsed laser such as a picosecond, nanosecond or femtosecond laser.
The method may also include another machining step, also called second machining step, intended to dimension the green body and/or the blank. Preferably, it is operated on the green body before sintering so that the material is not too hard. The present invention does not exclude that this machining step is carried out partly before sintering and partly after sintering. Laser engraving to obtain the decoration can also be carried out before or after this other machining step.
The method may optionally include a debinding step before the sintering step if the materials have been injected with a system of organic binders (paraffin, polyethylene, etc.).
Finally, the manufacturing method includes a finishing step such as polishing, satin-finishing, matting, etc.
According to the variant of
According to the variant of
In the example shown, the compression tool 5, 6, which can also be described as a press, includes a fixed part 5a with a mould having a ring-shaped impression for making a bezel, the movable part which ensures the compression of the materials not being shown.
Before or after the sintering and optionally the second machining, the second material 3 is hollowed, by laser ablation, at least to the first material 2 to form the decoration 8 in a distinct colour from the substrate formed by the bezel 1 as shown in
Typically, a bezel 1 according to
| Number | Date | Country | Kind |
|---|---|---|---|
| 21186468.1 | Jul 2021 | EP | regional |
