CH711739A2 - Method of manufacturing a metal part with at least one optical illusion pattern - Google Patents

Abstract

The invention relates to a method of manufacturing a single-piece piece of simple shape based on metal with the illusion of faceting and / or chamfering to form all or part of the cladding of a room watchmaking. The method includes the steps of forming a mold on a substrate, and filling mold cavities by electroplating.

Description

Description

Field of the Invention [0001] The invention relates to a method of manufacturing a metal-based part comprising at least one optical illusion pattern and, more specifically, at least one pattern that makes the surface upper is not flat.

BACKGROUND OF THE INVENTION [0002] It is known to form trim parts whose upper surface is faceted and / or chamfered in order to improve the aesthetics of a timepiece. Document EP 1557 729 discloses, in particular, the very great difficulty of developing a process for manufacturing faceted parts that does not require a retouching step. SUMMARY OF THE INVENTION [0003] The object of the present invention is to overcome all or part of the aforementioned drawbacks by proposing a manufacturing process that does not require faceting or retouching to obtain a simple metal-based part offering the illusion of faceting and / or chamfering.

For this purpose, the invention relates to a method of manufacturing a metal-based part with at least one optical illusion pattern characterized in that it comprises the following steps: a) forming a substrate whose planar upper surface is electrically conductive and has negative ribs of said at least one optical illusion pattern of said workpiece; b) forming a mold on the substrate, the mold having cavities whose bottom is formed by said upper face of the substrate; c) electroplating the cavities of the mold to form said metal-based part with at least one optical illusion pattern; d) releasing the thus formed part of the substrate and the mold.

It is therefore understood that the manufacturing method allows, thanks to the flatness of the substrate, to obtain a workpiece whose upper flat surface does not need to be faceted or, more generally, retouched.

In addition, the manufacturing process provides a very high accuracy of the dimensions and very reproducible of the same one-piece piece based on metal or several different pieces of metal-based onebloc on the same substrate.

Finally, the very high accuracy and reproducibility of the manufacturing process allows, advantageously according to the invention, to obtain a very simple piece provided with at least one very fine and easily reproducible pattern making believe that the surface upper is not flat in the manner of machining such as bevelling or chamfering.

According to other advantageous variants of the invention: according to a first embodiment, the ribs form at least two series of parallel segments, the first series of parallel segments joining the second series of parallel segments at an angle between 10 and 170 degrees in order to offer the said piece the illusion of an upper face with two bevelled faces forming an edge; according to a second embodiment, the ribs form at least one series of curved segments in order to offer to said part the illusion of a convex upper face; according to a third embodiment, the ribs form at least one series of recesses distributed symmetrically with respect to each other, said at least one series of recesses being formed adjacent to a portion whose upper surface of the substrate does not comprise any negative rib to provide the said piece with the illusion of an upper face with two bevelled faces forming an edge; according to a fourth embodiment, the ribs are distributed at the periphery of the cavities of the mold and form at least two series of parallel segments, the parallel segments of the first series being perpendicular to the parallel segments of the second series and joining in a a 90-degree angle to provide the said piece with the illusion of a chamfered upper face; whatever the embodiment, the ribs have a height of between 2 and 100 micrometers; the method further comprises, between step c) and step d), step e): selectively machining a part of the metal-based part to form a part with a fixing means; the upper surface of the substrate is rendered electrically conductive by the doping of a silicon substrate and / or by the deposition of an electrically conductive layer on a silicon substrate; the substrate comprises a thickness of between 0.3 and 1 mm; step b) comprises the phases f): depositing a layer of photoresist on the electrically conductive top surface of the substrate, g) selectively illuminating a portion of the photoresist and h): developing the photoresist to form the photoresist cavities of the mold; the part is formed based on nickel or nickel-phosphorus; several pieces are formed on the same substrate; - the piece forms all or part of a dial, a decoration of a window, a flange, a telescope, a pusher, a crown, a caseback, a needle , a bracelet, a link, a clasp, a decoration, an oscillating weight or a wall lamp.

The invention also relates to the cladding of a timepiece comprising a metal-based part obtained from the method according to one of the preceding variants, characterized in that the part comprises a top surface. substantially planar with at least one optical illusion pattern suggesting that the upper surface is not flat.

BRIEF DESCRIPTION OF THE DRAWINGS [0010] Other particularities and advantages will become clear from the description which is given below, by way of indication and in no way limitative, with reference to the appended drawings, in which: FIGS. 1 to 5 are schematic representations of steps of a method according to the invention; figs. 6-9 show examples of needles obtained according to the invention; figs. 10 to 15 represent examples of index hours obtained according to the invention; fig. 16 represents an example of a window decoration obtained according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [0011] The present invention relates to a method of manufacturing a single-piece piece of simple metal-based form with the illusion of faceting and / or chamfering to form all or part of the dressing of a timepiece. By way of non-limiting example, the piece may thus form all or part of a dial, a counter decoration, a flange, a bezel, a pusher, a crown, a a caseback, an oscillating weight, a needle, a bracelet, a link, a clasp, a decoration or a wall lamp.

Of course, such a piece can not be limited to the field of watchmaking. By way of non-limiting example, such a piece could alternatively form all or part of an article of jewelry or jewelery.

The method is intended to manufacture a metal-based part. The term "metal-based" means that one or more metals can enter the composition of the piece. Thus, by way of non-limiting example, the part may for example be formed based on nickel or nickel-phosphorus.

Advantageously according to the invention, the metal-based part obtained by the method comprises at least one optical illusion pattern. More specifically, the part advantageously comprises a substantially flat upper surface with at least one optical illusion pattern making it appear that the upper surface is not flat, which makes it possible to have a single piece offering, for example , the illusion of faceting and / or chamfering.

For the sake of simplification, the figures presented show the manufacture of a single piece on a substrate. However, advantageously according to the invention, the method allows several identical or different parts to be formed on the same substrate.

As shown in FIG. 1, the method according to the invention comprises a first step a) intended to form a substrate 1 whose upper planar surface 3 is electrically conductive and comprises negative ribs of said at least one optical illusion pattern of the part to be manufactured . The general shape of said at least one optical illusion pattern will be better explained below. For reasons of intelligibility, the ribs 5 are diagrammatically represented by three studs projecting from the upper surface 3 of the substrate 1 in FIG. 1.

A wide variety of substrates 1 is possible. Preferably, the material of the substrate 1 is chosen for its ease in being made flat and its very low roughness, that is to say its naturalness in presenting a smooth surface. For example, a substrate 1 based on silicon has these two advantages.

In the case where the substrate 1 is made of silicon, step a) may then comprise a first phase intended to coat the substrate 1 with a mask having cut-outs leaving a top of the substrate 1 uncovered. second phase, an engraving according to the openwork of the mask could be done. Such etching can be achieved by a dry or wet attack. Finally, in a third phase illustrated in FIG. 1, the mask 2 is removed leaving only the ribs 5 formed on the upper surface 3 of the substrate 1.

In the case where the substrate 1 is silicon, the upper surface 3 of the substrate 1 can be made electrically conductive by the doping of silicon, that is to say using a substrate 1 already doped before etching, and / or by depositing an electrically conductive layer.

In addition, the substrate 1 may have a thickness between 0.3 and 1 mm while the ribs 5 may extend at a height of between 2 and 100 micrometers from the upper surface 3 of the substrate 1.

As illustrated in FIG. 2, the process continues with a second step b) intended to form a mold 7 on the substrate 1. It is thus clear that the mold 7 having cavities 6 whose bottom is formed by the upper face 3 of the substrate 1.

Step b) preferably comprises the three phases f) to h). Step b) comprises a first phase f) intended to deposit a photoresist layer on the electrically conductive upper surface 3 of the substrate 1. Such a phase f) can be obtained by centrifugal coating (also known as "spin"). coating ") or by spraying (also known as" spray coating "). The second phase g) is intended to selectively illuminate a portion of the photosensitive resin. It is therefore understood that depending on the nature of the photosensitive resin, that is to say if the resin is of the positive or negative type, the illumination will be focused on the desired future cavities 6 or on the parts other than the future cavities 6 desired.

Finally, step b) ends with a third phase h) intended to develop the selectively illuminated photosensitive resin in order to form the mold 7, that is to say harden the photosensitive resin remaining between the cavities 6. This third phase h) is generally obtained by a heat treatment intended to harden the resin followed by a development intended to form the cavities 6.

As illustrated in FIG. 3, the process continues with a third step c) for filling the cavities 6 of the mold 7 by electroplating to form the blank or the metal-based part with at least one optical illusion pattern 14. According to the invention, the metal-based part has the same projection pattern. However, by structuring the substrate 1, the ribs 5 will form during step c), recesses 15 on the outer surface of the blank or the metal-based part. Indeed, as explained below, an optional step e) can be implemented after step c).

Advantageously according to the invention, the method makes it possible, thanks to the very precise photolithography step b), to obtain a metal-based block 9 with external and, possibly, internal dimensions of high precision. to respect the very high tolerances of a piece in the field of watchmaking. By internal dimensions, it should be understood that from any structured resin parts 7 which are enclosed in cavities 6, perforations and / or holes in the metal part can be directly formed during step c) .

As explained above, the galvanic filling of the cavities 6 during step c) may, for example, be carried out with an alloy formed of nickel and phosphorus (NiP) and in particular such an alloy whose proportion of phosphorus is substantially equal to 12% (NiP12).

Finally, the process ends with a fourth and last step d) intended to release the part thus formed of the substrate 1 and the mold 7. Therefore, in the example above in which the substrate 1 is silicon step d) may consist of a selective etching of the silicon and a selective etching of the mold material 7. The etching of the silicon may, for example, be obtained by chemical etching by means of a bath comprising potassium hydroxide (known by the abbreviation KOH).

According to a variant of the invention illustrated in FIGS. 4 and 5, the method further comprises, between step c) and step d), the optional step e) for selectively machining a portion of the metal-based part to form a part 11 with less a means 16 for fixing.

As explained above, the block 9 having the same pattern projection is then modified in its thickness to form at least one means 16 for fixing. The piece 11 is thus obtained without having to form several stacked functional levels or touching the surface of the part comprising said at least one pattern 14 with an optical illusion.

Because of the precise positioning of each block 9 on the substrate 1, it is possible, during step e), to machine each block 9 again on the substrate 1 with a programmable controller according to precise dimensions. Note that, even if step e) is intended to machine each block 9, part of the resin 7 may also be machined by the constraints due to the size of the tools used or the volumes to be removed as illustrated by the visible clearances in fig. 4. Of course, this step e) can also allow to level, by running in, the mold 7 and the block 9.

It is then understood that in addition to the upper plane surface 13 and recesses 15 forming said at least one optical illusion pattern 14, the part 11 further comprises at least one attachment means 16 for attaching the room. The attachment means 16 can thus take the form of a foot or a cannon.

Figs. 6 to 16 show examples of parts obtained according to the method for better explaining an optical illusion pattern according to the invention. By way of no limitation, four embodiments of optical illusion pattern are explained.

According to a first embodiment, the substrate 1 comprises ribs for obtaining the examples of FIGS. 6,7,10 and 12. The pattern 114,214, 514 and 714 optical illusion of FIGS. 6,7,10 and 12 thus form at least two series 118,120,218,220,518,520,718,720 of segments 119,121,219,221,519,521,719,721 parallel. Preferably according to the first embodiment, the first series 118, 218, 518, 718 of segments 119, 219, 519, 719 parallel joining the second series 120, 220, 520, 720 segments 121, 221, 521, 721 parallel according an angle between 10 and 170 degrees to offer the piece 111, 211, 511, 711 the illusion of an upper face with two bevelled faces forming an edge while it is flat.

Claims (14)

According to a second embodiment, the substrate 1 comprises ribs for obtaining the examples of FIGS. 8, 13 and 15. The optical illusion pattern 314, 814 and 1114 of FIGS. 8, 13 and 15 thus form at least one series 318, 320, 818, 820, 1118 of segments 319, 321, 819, 821, 1119 curved in order to offer to said part the illusion of a curved upper surface whereas it is flat. According to a variant of the second embodiment shown in FIGS. 8 and 13, a first series 318, 818 of segments 319, 819 curves joins a second series 320, 820 of segments 321, 821 curves at an angle of between 10 and 170 degrees in order to offer to said part the illusion of an upper face with two convex sides joining together forming a groove while the upper face is flat. According to a third embodiment, the substrate 1 comprises ribs in the form of pads for obtaining the examples of FIGS. 9 and 11. The optical illusion pattern 414 and 614 of FIGS. 9 and 11 thus form at least one series 418, 618 of recesses 419, 619 distributed symmetrically with respect to each other. Preferably according to the third embodiment, said at least one series 418, 618 of recesses being formed adjacent to a part 432, 632 whose surface of the part 411, 611 does not include any optical illusion pattern in order to offer to said part the illusion of an upper face with two bevelled faces forming an edge while it is flat. As visible in FIGS. 9 and 11, the recesses 419, 619 are of circular section and regularly spaced apart from each other. Of course, the geometry and distribution of the recesses 419, 619 may differ according to the desired effect without departing from the scope of the invention. According to a fourth embodiment, the substrate 1 comprises ribs which are distributed at the periphery of the cavities of the mold to obtain the examples of FIGS. 14 and 16. The optical illusion pattern 914 and 1014 of FIGS. 14 and 16 thus form at least two series 918, 920, 922, 1018, 1020, 1022, 1024 of segments 919, 921, 923, 1019, 1021, 1023, 1025 parallel, segments 919, 923, 1019, 1023 parallel of the first series 918,922,1018,1022 being perpendicular to the parallel segments 921, 1021, 1025 of the second series 920, 1020, 1024 and joining at a 90 degree angle in order to give the part the illusion of a chamfered upper surface surrounding a portion 932, 1032 whose surface of the part 911, 1011 has no optical illusion pattern. Of course, the present invention is not limited to the example shown but is susceptible to various variations and modifications that will occur to those skilled in the art. In particular, the parts 11, 111, 211, 31, 411, 511, 611, 711, 811, 911, 1011 could be the subject of a final curing step as for example disclosed in the document EP 15184 492 incorporated by reference herein. request. It is also conceivable that the ribs 5 may alternatively be formed by photolithography of a photosensitive resin on the flat upper surface of a substrate. In a particular alternative, the substrate 1 could also be chosen to form ribs 5 of different geometry from that shown in FIGS. 1 to 4. Thus, by way of non-limiting example, the substrate 1 could be monocrystalline silicon oriented in the plane (100) and undergo wet etching with potassium hydroxide (KOH) to form etchings whose flanks are oblique and not vertical as shown in figs. 1 to 4. [0041] Finally, optical illusion patterns can not be limited to those described above. Thus, other embodiments are possible without departing from the scope of the invention. In addition, the four embodiments presented above are likely to be combined with each other, that is to say that several different patterns may appear on the same piece. claims A method of manufacturing a metal-based part (11, 111, 211, 311, 411, 511, 611, 711, 811, 911, 1011, 1111) with at least one pattern (14, 114, 214, 314, 414, 514, 614, 714, 814, 914, 1014, 1114) with optical illusion characterized in that it comprises the following steps: a) forming a substrate (1) whose upper surface (3) plane is electrically conductive and has negative ribs (5) of said at least one optical illusion pattern of said workpiece; b) forming a mold (7) on the substrate (1), the mold (7) having cavities (6) whose bottom is formed by said upper face of the substrate (1); c) filling the cavities (6) of the mold by electroplating to form said metal-based part with at least one optical illusion pattern; d) releasing the part (11, 111, 211, 311, 411, 511, 611, 711, 811, 911, 1011, 1111) thus formed of the substrate (1) and the mold (7). 2. Method according to the preceding claim, characterized in that the ribs (5) form at least two series of parallel segments, the first series of parallel segments joining the second series of parallel segments at an angle of between 10 and 170 degrees to to offer the said piece the illusion of an upper face with two bevelled faces forming an edge. 3. Method according to claim 1, characterized in that the ribs (5) form at least one series of curved segments in order to provide said part with the illusion of a convex upper face. 4. Method according to claim 1, characterized in that the ribs (5) form at least one series of recesses distributed symmetrically with respect to each other, said at least one series of recesses being formed adjacent to a portion of which the upper surface of the substrate has no negative rib to provide the said part the illusion of an upper face with two bevelled faces forming an edge. 5. Method according to claim 1, characterized in that the ribs (5) are distributed at the periphery of the cavities of the mold and form at least two series of parallel segments, the parallel segments of the first series being perpendicular to the parallel segments of the second series and joining at a 90 degree angle to provide the said piece with the illusion of a chamfered upper face. 6. Method according to one of the preceding claims, characterized in that the ribs (5) have a height of between 2 and 100 micrometers. 7. Method according to one of the preceding claims, characterized in that the method further comprises, between step c) and step d), the following step: e) selectively machining a portion of the workpiece (11,111,211,311 , 411, 511, 611, 711, 811, 911, 1011, 1111) to form a workpiece (11, 111, 211, 311, 411, 511, 611, 711, 811, 911, 1011, 1111) with fastening means (16). 8. Method according to one of the preceding claims, characterized in that the upper surface (3) of the substrate is made electrically conductive by doping a silicon substrate and / or by depositing an electrically conductive layer on a silicon substrate. 9. Method according to one of the preceding claims, characterized in that the substrate (1) has a thickness of between 0.3 and 1 mm. 10. Method (1) according to one of the preceding claims, characterized in that step b) comprises the following steps: f) depositing a layer of photoresist on the upper electrically conductive surface of the substrate; g) selectively illuminating a portion of the photoresist; h) developing the photoresist to form the cavities of the mold. 11. Method according to one of the preceding claims, characterized in that the part (11, 111, 211, 311, 411, 511, 611, 711, 811, 911, 1011, 1111) is formed based on nickel or nickel- phosphorus. 12. Method according to one of the preceding claims, characterized in that several parts are formed on the same substrate. 13. Method according to one of the preceding claims, characterized in that the part (11, 111, 211, 311, 411, 511, 611, 711, 811, 911, 1011, 1111) forms all or part of a dial , a counter decoration, a flange, a telescope, a pusher, a crown, a caseback, a needle, a bracelet, a link, a clasp, a decoration, an oscillating weight or a wall lamp. 14. Cladding of a timepiece comprising a metal-based part (11, 111, 211, 311, 411, 511, 611, 711, 811, 911, 1011, 1111) obtained from the process according to one of the preceding claims, characterized in that the piece (11, 111, 211, 311, 411, 511, 611, 711, 811, 911, 1011, 1111) comprises a surface (13) substantially flat upper with at least one pattern (14, 114, 214, 314, 414, 514, 614, 714, 814, 914, 1014, 1114) with an optical illusion suggesting that the upper surface (13) is not flat.