HK1243780B - Economical timepiece display component - Google Patents

Description

Economical watch display components

Technical Field

The invention relates to an economical method for producing a timepiece display element or a hand-mounting element having at least one aesthetic and/or visible surface.

The present invention relates to the field of timepiece display elements or hand-mounting elements.

Background Art

In horology, the manufacture of small display elements, hand-mounting elements or exterior elements has always presented practical production problems due to the importance of these elements in terms of the appearance of the watch and how this is evaluated by the customer or user.

Indeed, the user's gaze must be drawn to these elements, which must therefore have an impeccable appearance, be extremely fine, and also have a very uniform surface finish and, in general, brightness and reflection properties that are difficult to achieve in a reproducible manner. Indeed, elements such as appliqués are distributed in large numbers on the watch dial and must be identical.

The production costs of these elements and their weight must also be kept under control, especially when they are movable elements such as hands. Therefore, a convenient solution in luxury timepieces consists in machining said elements from a block of a precious metal alloy (such as gold), but this solution is not always the most suitable.

It is also known that manufacturing such components by machining followed by surface treatment results in a relatively high scrap rate, as the surface treatment may reveal visual and/or surface defects that were not visible during the machining stage, which is wasteful when the components are expensive due to the desired finish.

Summary of the Invention

The present invention proposes to develop an alternative method for manufacturing timepiece display elements or hand-mounting elements at manageable costs, said method comprising at least one aesthetic and/or visible surface, while ensuring the visual and surface reproducibility of these aesthetic and/or visible surfaces and with improved production reliability compared to the prior art.

To this end, the present invention relates to a manufacturing method having the following technical features: performing the following steps in sequence:

- selecting a first material that can be easily shaped by deformation and/or machining and/or injection molding and/or casting and/or electrogrowing to produce the workpiece;

- forming a workpiece from the first material;

- a second material is selected to form each of said aesthetic and/or visible surfaces, said second material being an amorphous metal alloy or having a nanocrystalline structure or comprising nickel or a nickel-phosphorus alloy, or said second material being a pure metal or an alloy of gold and/or silver and/or copper and/or rhodium and/or titanium and/or aluminum;

- coating the workpiece with a thick layer of the second material, at least on the surface intended to remain visible on the element in its operating position, the layer having an initial thickness greater than or equal to 20 micrometers;

- performing a diamond tool machining operation on at least one of said aesthetic and/or visible surfaces intended to remain visible, in order to remove at least a portion of the thick layer of said second material.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will become more apparent upon reading the following detailed description with reference to the accompanying drawings, in which:

1 to 10 show schematic cross-sectional views of different steps for implementing the method according to the invention in different alternatives:

- FIG. 1 shows the production of a workpiece from a first material.

- FIG. 2 shows a blank formed from the same workpiece, coated with a thick layer of a second material.

- Figure 3 shows the diamond turning of the upper aesthetic and/or visible surface of the blank.

- Figure 4 shows the finished element by diamond turning all the aesthetic and/or visible surfaces of the blank.

- FIG. 5 shows a perspective view of such a finished element ready for use.

- Figures 6 to 13 show schematic perspective views of non-limiting examples of implementation of the invention:

- Figure 6 shows a hollow pointer with transverse and longitudinal sections in Figures 6A and 6B.

- Figure 7 shows an appliqué block provided with two legs.

- Figure 8 shows a digital block provided with two legs.

- Figure 9 shows a marker block provided with two legs.

- Figure 10 shows a monogram provided with one foot.

– Figure 11 shows the indicator block.

- Figure 12 shows an index provided with two legs.

- Figure 13 shows a window edge block provided with four legs.

- Figure 14 is a block diagram representing a watch comprising elements manufactured by the method according to the invention.

DETAILED DESCRIPTION

The present invention proposes to reduce both the cost and the weight of the external element or pointer mounting element, while ensuring a flawless appearance of this visible element and minimizing the manufacturing scrap rate.

The invention proposes to form an element whose surface portion is made of a material compatible with fine machining in order to obtain a uniform surface finish with very low roughness.

This surface portion is formed with a thickness sufficient to ensure the homogeneity of the material and thus the quality of the final finish after the machining process.

The preferred finishing process is diamond tool cutting.

The invention thus concerns an economical method for manufacturing a timepiece display element or hand-mounting element 1 formed by a hand 11 , an appliqué 12 or the like, comprising at least one aesthetic and/or visible surface 2 intended to be visible to a user of the watch or the like.

According to the present invention, the following steps are performed successively:

- selecting a first material that can be easily shaped by deformation and/or machining and/or injection molding and/or casting and/or electrogrowing in order to produce the workpiece 3;

- producing a workpiece 3 from a first material;

- a second material is selected to form each aesthetic and/or visible surface 2, said second material being an amorphous metal alloy or having a nanocrystalline structure or comprising nickel or a nickel-phosphorus alloy, or said second material being a pure metal or an alloy of gold and/or silver and/or copper and/or rhodium and/or titanium and/or aluminum;

- coating the workpiece 3 with a thick layer 4 of a second material, at least on the surface intended to remain visible on the component in its operating position, said layer 4 having an initial thickness E greater than or equal to 20 micrometers;

- Diamond turning of at least one aesthetic and/or visible surface 2 intended to remain visible, removing at least a portion of the excess thickness 5 included in the thick layer 4 of the second material relative to the geometrical position of the aesthetic and/or visible surface 2 concerned.

More particularly, the excess thickness 5 is completely removed on the relevant aesthetic and/or visible surface 2 during this first diamond machining operation, which may also be the only operation depending on the desired appearance of the finished element 1 .

In a particular embodiment of the invention, the thick layer 4 of the second material is made with an initial thickness E greater than or equal to 50 micrometers.

In a particular embodiment of the invention, element 1 is made with at least one such aesthetic and/or visible surface 2 bordered by a raised edge 9 and during the diamond turning process, the raised edge 9 is produced and defines the aesthetic and/or visible surface 2 .

In a particular embodiment of the invention, during the diamond turning operation, all aesthetic and/or visible surfaces 2 intended to remain visible are diamond turned, at least a portion of the excess thickness 5 comprised in the thick layer 4 of the second material is removed, and, when protruding edges 9 are included in the element 1, all protruding edges 9 delimiting these aesthetic and/or visible surfaces 2 are diamond turned.

In one particular embodiment of the invention, during the diamond turning operation, diamond turning is performed on at least one aesthetic and/or visible surface 2 intended to remain visible, removing a portion of the thick layer 4 of the second material and having a surface profile/surface roughness comprised between 2 nm Ra and 100 nm Ra.

In a particular embodiment of the invention, during the diamond turning operation, on each aesthetic and/or visible surface 2 , a residual thickness ER of the thick layer 4 of the second material is maintained that is greater than or equal to 5 micrometers.

In a particular embodiment of the invention, at least 50% of the initial thickness E of the thick layer 4 of the second material is removed during the diamond turning operation.

In a particular embodiment of the invention, after the diamond turning operation, a galvanic or PVD or CVD or ALD coloring operation is performed to a small thickness of less than 5 microns, at least on the aesthetic and/or visible surface 2 intended to remain visible.

In a particular embodiment of the invention, the first material is selected from alloys of copper and/or aluminum and/or zinc.

In a particular embodiment of the invention, brass is chosen for the first material.

In a particular embodiment of the invention, an aluminum alloy is selected for the first material.

In a particular embodiment of the invention, a zinc alloy is chosen for the first material.

In a particular embodiment of the present invention, POM or PS or PC or a polymer is selected for the first material.

In a particular embodiment of the invention, the charged material is selected for the first material so as to be electrically conductive.

In a particular embodiment of the invention, the second material is chosen to be different from the first material.

In a particular embodiment of the invention, a nickel-phosphorus alloy is selected for the second material.

In a particular embodiment of the invention, the workpiece 3 is coated with a thick layer 4 of the second material by bulk chemical deposition.

In a particular embodiment of the invention, the workpiece 3 is coated with the thick layer 4 of the second material by electrodeposition.

In a particular embodiment of the invention, the workpiece 3 is produced by deformation or forging or stamping.

In a particular embodiment of the invention, the workpiece 3 is made hollow and/or comprises at least one mounting foot 10 .

Making the element 1 hollow with the chamber 70 is advantageous in terms of economy of material and weight, particularly when the element 1 is a pointer 11 (which is shown here with a tube 110), so as to minimize unbalance.

In various specific embodiments of the present invention, the display element or pointer mounting element 1 is made in the following forms: pointer 11 or appliqué block 12 or number block 13 or logo block 14 or letter combination block 15 or indicator block 16 or logo block 17 or window edge block 18.

The invention also relates to a watch 100 comprising at least one display element or hand-mounting element 1 produced by the method described above.

The excellence of the diamond tool cutting finishing of this element lies in the perfect quality of its surface condition (mirror finish) and the flank intersections defining sharp edges, which cannot be guaranteed by any other manufacturing method.

Claims (19)

1. An economical method for manufacturing a watch display element or a pointer mounting element, the watch display element or pointer mounting element comprising at least one aesthetic and/or visible surface (2), characterized in that the following steps are performed sequentially: – Select a first material that is readily shaped by deformation and/or cutting and/or injection molding and/or casting and/or electro-growth to manufacture a workpiece (3); – The workpiece (3) is made from the first material; – Select a second material to form each of the aesthetic and/or visible surfaces (2), the second material being an amorphous metal alloy or having a nanocrystalline structure or comprising nickel or nickel-phosphorus alloy, or the second material being a pure metal or an alloy of gold and/or silver and/or copper and/or rhodium and/or titanium and/or aluminum; - At least on a surface of the workpiece (3) that remains visible on the element at the operating position of the workpiece (3), a thick layer (4) of the second material is coated on the workpiece (3), the initial thickness (E) of the thick layer (4) being greater than or equal to 20 micrometers; – For at least one of the aesthetically pleasing and/or visible surfaces (2) intended to remain visible, diamond cutting is performed to remove at least a portion of the thick layer (4) composed of the second material. During the diamond cutting operation, diamond cutting is performed on at least one of the aesthetically pleasing and/or visible surfaces (2) intended to remain visible, to remove a portion of the thick layer (4) composed of the second material, and the surface roughness includes between 2 nm Ra and 100 nm Ra. 2. The method according to claim 1, wherein the thick layer (4) made of the second material is made to have a thickness of 50 micrometers or more. 3. The method according to claim 1, wherein the display element or pointer mounting element (1) is formed to have at least one of the aesthetic and/or visible surfaces (2) edged by a protruding edge (9); and the protruding edge (9) defining the aesthetic and/or visible surface (2) is formed during diamond cutting. 4. The method according to claim 1, characterized in that, during the diamond cutting operation, diamond cutting is performed on all aesthetically pleasing and/or visible surfaces (2) intended to remain visible in order to remove a portion of the thick layer (4) made of the second material, and if the display element or pointer mounting element (1) includes protruding edges (9), diamond cutting is performed on all protruding edges (9) defining the aesthetically pleasing and/or visible surfaces (2). 5. The method according to claim 1, characterized in that, during the diamond cutting operation, on each of the aesthetic and/or visible surfaces (2), the remaining thickness (ER) of the thick layer (4) made of the second material is maintained to be greater than or equal to 5 micrometers. 6. The method according to claim 1, characterized in that, during the diamond cutting operation, at least 50% of the initial thickness (E) of the thick layer (4) made of the second material is removed. 7. The method according to claim 1, characterized in that, after the diamond cutting operation, an electric current or PVD or CVD or ALD or chemical coloring operation is performed on at least one of the aesthetically pleasing and/or visible surfaces (2) intended to remain visible to a small thickness of less than 5 micrometers. 8. The method according to claim 1, wherein the first material is selected from an alloy of copper and/or zinc. 9. The method according to claim 8, wherein the first material is selected as brass. 10. The method according to claim 8, wherein the first material is selected as a zinc alloy. 11. The method according to claim 1, wherein the first material is selected from POM, PS, PC, or a polymer. 12. The method according to claim 11, wherein the first material is selected as a charged material such that the first material is conductive. 13. The method according to claim 1, wherein the second material is selected to be different from the first material. 14. The method according to claim 1, wherein the second material is selected as a nickel-phosphorus alloy. 15. The method according to claim 1, characterized in that the workpiece (3) is coated with the thick layer (4) of the second material by batch chemical deposition. 16. The method according to claim 1, characterized in that the workpiece (3) is coated with the thick layer (4) made of the second material by electrodeposition. 17. The method according to claim 1, wherein the workpiece (3) is formed by deformation, forging or stamping. 18. The method according to claim 1, wherein the workpiece (3) is made hollow and/or includes at least one mounting leg (10). 19. The method according to claim 1, wherein the display element or pointer mounting element (1) is manufactured in the form of a pointer (11) or an inlay block (12) or a number block (13) or a sign block (14) or a letter combination block (15) or an indicator block (16) or a marker block (17) or a window edge block (18).