CLOCK DIAL

Description

Technical field

[0001] The present invention relates to a dial for a timepiece, in particular for a wristwatch, and more particularly to such a polished and / or enamelled dial whose visible surface includes a relief. State of the art

[0002] It is well known to manufacture dials that include a relief, formed for example by a conical or pyramidal part outside a flat, circular part. Dials of this type are usually manufactured by machining the base material of the dial, such as stone or ceramic, to obtain the three-dimensional shape, followed by polishing and / or enameling steps. A problem that is often encountered is that these polishing and enameling processes round off the edges between the surfaces of the relief after machining, which detracts from the aesthetic appearance of the watch.

[0003] Document EP0294661A1 discloses a watch dial comprising a mosaic-type coating, and comprising a plurality of metal blocks juxtaposed on a base. Summary of the invention

[0004] The present invention aims to provide a method of manufacturing a dial for a timepiece which overcomes the problems identified above.

[0005] To this end, the invention provides a method of manufacturing a dial as defined in the appended claim 1. Preferred embodiments of this method are defined in dependent claims 2 to 5.

[0006] The invention also relates to a dial for a timepiece, as defined in appended claim 6. Preferred embodiments are defined in claims 7 to 9. A timepiece comprising such a dial is defined in claim 10.

[0007] Other features and advantages of the present invention will become apparent from the following description of preferred embodiments, presented by way of non-limiting example with reference to the accompanying drawings. Brief description of the figures

[0008] There figure 1 represents a dial of a watch comprising a relief, as it is currently known. Figure 2a represents the constituent parts of a dial manufactured according to the method of the invention. The figures 3a-3c represent the steps of assembling the dial according to the method of the invention. The figure 4 represents another example of a dial manufactured according to the method of the invention. The Figure 5 represents an alternative form of execution for manufacturing the dial of the Figure 3c . There figure 6 represents a dial manufactured according to the method of the invention comprising a base with different levels. The figure 7represents a dial manufactured according to the invention, comprising a negative relief. The figure 8 represents a dial manufactured according to the invention, comprising a local relief. Detailed description of embodiments of the invention

[0009] An illustration of a dial 1 as known in the state of the art is shown in figure 1The dial comprises a single-piece part 9 comprising a flat lower surface 2, attached for example by gluing to a base or substrate 3 intended to be attached above a watch movement for example by means of dial feet (not shown). The upper surface comprises a relief, comprising a flat central part 4 which is located at a first level A1 measured from a horizontal reference plane which is here the plane of the base 3, and twelve surfaces 5 inclined from the first level A1 towards a second level A2 outside the dial 1, the second level A2 being lower than the first level A1. The method of manufacturing this dial as it is currently known consists of machining a cylindrical part made of metal, stone or ceramic for example. After machining, the inclined surfaces 5 as well as the central surface 4 are polished.During the polishing operation, the edges between the surfaces of the relief are rounded and poorly defined, harming the aesthetics of the dial. Depending on the material of the part 9, the process may also include a step of enameling the upper surface of the relief; this step is particularly applicable when the dial is made of metal. Here again, the enameling operation will have the effect of rounding the edges.

[0010] To produce the same dial using the method of the invention, several separate parts are first manufactured by machining to produce semi-finished elementary parts having an upper surface. The upper surfaces of the elementary parts are treated to give these elementary surfaces a specific aesthetic appearance. The upper surfaces of these elementary parts are, for example, polished and / or possibly enameled. These upper surfaces may also be subjected to structuring treatments to form decorations such as Côtes de Genève, perlage, circular ribs, sandblasting, satin finishing, etc. The elementary parts having undergone treatment of their upper surface are then cut according to a contour having a specific geometry, then assembled on the base 3 by juxtaposition, preferably edge to edge.

[0011] A set of elementary parts manufactured according to an embodiment of the method of the invention are shown in figure 2: the set of these elementary parts comprises a parallelepiped 10 having a thickness A1 and twelve straight lateral faces, as well as twelve identical parts 11 having a lateral face whose width corresponds to the width of the lateral faces of the parallelepiped 10. The upper surface of the parts 11 is inclined between the thicknesses A1' and A2. The thicknesses A1 and A1' may be equal but preferably A1' is slightly less than or greater than A1, for example by a few tens of micrometers. The manufacture of the elementary parts 10 and 11 may be carried out using machining techniques known per se, such as grinding, laser ablation, ultrasonic-assisted machining and / or laser cutting.The upper surfaces 4 and 5 of the parts 10 and 11 are then subjected to a surface treatment to give the upper surfaces a determined aesthetic appearance, in this case polishing, using techniques known in the state of the art, such as polishing by barrel, by flat disc or by fine grinding wheels.

[0012] When parts 10 and 11 are made of metal or ceramic, the upper surfaces of the parts may be all or partly subjected to an enamelling step, alternatively.

[0013] According to one embodiment, the single-piece part 9 used in the state-of-the-art method illustrated in figure 1 is manufactured by machining using a conventional process, polished, and then cut, for example by laser cutting, to obtain the elementary parts 10 and 11.

[0014] The elementary parts 10 and 11 obtained and whose upper surfaces 4 and 5 are polished and / or enameled are then assembled edge to edge, placing them on the base 3 of the watch, as illustrated in Figures 3a to 3c The fixing of the elementary parts 10 and 11 on the base can be carried out by a method known per se, preferably by gluing or by a mechanical connection such as by rods, or by a combination of these methods.

[0015] Preferably, the parallelepiped 10 is mounted first, followed by the side pieces 11 which are juxtaposed to the side faces of the parallelepiped 10, and to the faces of two adjacent pieces 11. The polished and / or enameled pieces 10 and 11 are produced with strict dimensional tolerances, so that gap-free contact is achieved for all of the adjacent interfaces of the contiguous elementary pieces. Thus, this method makes it possible to produce a dial 1 in relief with sharp edges 12, each of these edges 12 being defined by the junction between the vertex lines 12a, 12b of two contiguous elementary pieces 10, 11.

[0016] There figure 4represents another example of a dial manufactured according to the method of the invention, and the relief of which is produced by the assembly of two elementary parts: a cylindrical part 20 having a thickness A1 and a conical part 21 which produces a relief between A1' and A2, A2 being less than A1' (the relationship between A1 and A1' is the same as that described for the embodiment shown in figures 2 And 3a-3c ). The two parts 20 and 21 are manufactured separately. The upper surfaces 4' and 5' are polished and / or enameled and then cut into their final shape. The parts 20 and 21 are then assembled on the base 3.

[0017] There Figure 5 represents an example of the dial with twelve inclined surfaces, i.e. the same dial which is represented in figures 1 to 3, but produced by an assembly of two parts 10 and 31: the parallelepiped 10 and a ring 31. The ring 31 comprising the twelve inclined surfaces 5 between A1' and A2, is produced as a single piece, preferably by laser cutting of the part 9 shown in figure 1 . The upper surfaces 4 and 5 of parts 10 and 31 are then polished and / or enamelled, then cut into their final shape before being assembled on the base 3.

[0018] According to one embodiment, the base 3 comprises several levels, and the thickness of the pieces which define the relief takes into account the height of these levels. figure 6 represents a dial assembled according to the method of the invention and which has the same external appearance as the dial of the figures 2 And 3a-3c, but in which the parallelepiped 10 is mounted on a central raised part of the base 3. The level of the central part of the base is higher than the level of the outer part 33 of the base, on which the parts 11 are mounted.

[0019] It is also possible to produce a negative relief using the method of the invention. An example is shown in figure 7 This dial comprises four pieces 40 to 43 mounted on the base 3, which create a relief between a thickness A1 on the outside of the dial and a thickness A2 less than A1 in the center of the dial.

[0020] The invention is not limited to the embodiments described above. The relief does not necessarily have to extend over the entire surface of the dial. An example of a local relief produced by the method of the invention is illustrated in figure 8The relief comprises a central cylindrical piece 50 surrounded by a conical piece 51, the pieces being integrated into a cylindrical hole 53 provided in a flat dial 52. The assembly of the relief is therefore carried out by manufacturing the pieces 50, 51 and 52, followed by polishing and / or enameling the pieces, cutting them into their final shape and then by assembling the pieces on the base 3.

Claims

1. Method for manufacturing a dial (1) for a timepiece, the dial comprising a relief portion which extends over the entire surface of the dial, wherein the relief portion is made as an assembly of elementary pieces (10, 11; 20, 21; 30, 31; 41, 42, 43, 44; 50, 51, 52), at least some of which have an upper surface that is inclined relative to the plane of the dial, and which are juxtaposed on a base (3), such that the relief portion is formed by the upper surfaces (4, 5) of the elementary pieces, the method comprising the steps consisting in: a) manufacturing semi-finished elementary pieces by machining, b) treating said upper surfaces of the elementary pieces after step a) to give the upper surfaces a defined aesthetic appearance, c) cutting said treated elementary pieces along a contour of defined geometry, d) assembling the elementary pieces obtained after step c), by juxtaposing the elementary pieces edge to edge, with gap-free contact, on the base (3).

2. Method according to claim 1, characterized in that step b) is a step of polishing, enamelling or structuring the surface to form a decoration.

3. Method according to claim 1 or 2, characterized in that the relief portion is defined by a flat, polygonal, central surface (4) which is situated at a first level (A1) measured from a horizontal reference plane, and a plurality of inclined flat side surfaces (5), which extend from a level (A1') essentially equal to the first level to a second level (A2) outside the dial, the second level being lower than the first level, the number of inclined surfaces corresponding to the number of sides of the polygonal surface (4), and in that: - one of said elementary pieces is a parallelepiped (10) whose upper surface forms the polygonal central surface (4), and which has a number of side faces corresponding to the number of sides of the polygonal surface (4), - the parallelepiped (10) is mounted centrally on said base (3), - each of the inclined surfaces (5) is made by the assembly, on said base (3), of elementary pieces (11) which are juxtaposed with the side faces of said parallelepiped (10).

4. Method according to claim 1 or 2, characterized in that the relief portion is defined by a flat, polygonal, central surface (4) which is situated at a first level (A1) measured from a horizontal reference plane, and a plurality of inclined flat side surfaces (5), which extend from a level (A1') essentially equal to the first level to a second level (A2) outside the dial, the second level being lower than the first level, the number of inclined surfaces corresponding to the number of sides of the polygonal surface (4), wherein the relief portion is formed by two elementary pieces of which: - the first elementary piece is a parallelepiped (10) whose upper surface forms the polygonal central surface (4), and which has a number of external side faces corresponding to the number of sides of the polygonal surface (4), - the second elementary piece is a ring (31) whose upper surface is formed by the plurality of inclined surfaces (5), and which has a number of inner side faces corresponding to the number of sides of the polygonal surface (4), and in that: - the parallelepiped (10) is mounted centrally on said base (3), - the inclined surfaces (5) are made by the assembly, on said base (3), of the second elementary piece (31) juxtaposed with the first elementary piece.

5. Method according to any of claims 1 to 3, characterized in that the relief portion is defined by a flat, circular, central surface which is situated at a first level (A1) measured from a horizontal reference plane, and a conical surface, which extends from a level (A1') essentially equal to the first level to a second level (A2) outside the dial, the second level being lower than the first level, wherein the relief portion is formed by two elementary pieces of which: - the first elementary piece is a cylinder (20) whose upper surface forms the circular central surface, - the second elementary piece is a ring (21) whose upper surface is formed by said conical surface, and in that: - the cylinder (20) is mounted centrally on said base (3), - the conical surface is made by the assembly, on said base (3), of the second elementary piece (21) juxtaposed with the first elementary piece (20).

6. Dial (1) for a timepiece, the dial comprising a relief portion which extends over the entire surface of the dial, wherein the relief portion is made as an assembly of elementary pieces (10, 11; 20, 21; 30, 31; 41, 42, 43, 44; 50, 51, 52), at least some of which have an upper surface that is inclined relative to the plane of the dial, and which are juxtaposed edge to edge, with gap-free contact, on a base (3), such that the relief portion is formed by the upper surfaces (4, 5) of the elementary pieces.

7. Dial according to claim 6, wherein the dial comprises relief portions with straight edges, each of these edges being defined by the junction between the apex lines of two contiguous elementary pieces.

8. Dial according to any of claims 6 or 7, wherein said pieces forming the relief portion are made of a material with an HV hardness greater than 500, preferably greater than 800 and more preferably greater than 1000.

9. Dial according to claim 8, wherein said pieces are made of sapphire, alumina, zirconia or natural stones.

10. A timepiece comprising a dial according to any of claims 6 to 9.