CH719840A2 - Process for manufacturing a watchmaking hand with a circular section. - Google Patents

Abstract

The present invention relates to a watchmaking hand (20) comprising a body of one-piece circular section, and its manufacturing method, the manufacturing method comprising a first step consisting of providing a one-piece part of predefined material, the part s 'extending along a longitudinal axis; a second step consisting of rotating said one-piece part; a third step consisting of emitting a first modulation of said laser light in power, geometry and time; a fourth step consisting of exposing a first portion of said at least one monobloc part to said first modulation of said laser light so as to form at least a first volume of circular section of a length L 1 and an average diameter D 1 , the ratio being less than or equal to 20 or 10, or even less than or equal to 5; a fifth step consisting of emitting a second modulation of said laser light in power, geometry and time; and a sixth step consisting of exposing a second portion of said at least one monobloc part to said second modulation of said laser light, so as to form at least a second volume of circular section of a length L 2 and an average diameter D 2, the ratio being less than or equal to 10, or even less than or equal to 5.

Description

Technical field of the invention

[0001] The field of the invention concerns that of manufacturing processes for timepieces, in particular a watchmaking hand of circular section.

Technology background

The needles are generally flat with two dimensions, and are obtained by a needle manufacturing process usually consisting of cutting a metal plate.

[0003] In order to assemble them on the movement, a hole is formed in the hands, to then be fitted onto a rod passing through the dial. Today, laser processes can be used to cut sheet metal.

This manufacturing process is easy to implement, but it is limited to the production of two-dimensional needles. For aesthetic reasons, if one wishes to obtain a circular section shape of the needle, this process cannot be used. By circular section is meant in particular a needle with rotating geometry.

[0005] To form watch movement axes or pivots, there are laser turning processes, consisting of rotating a one-piece body to machine it and cut it with the laser beam. The body is held by a machine, which rotates it at a predefined speed, while the laser beam is applied to the periphery of the body to carve it. Thus, we obtain a part of circular section, for example cylindrical or conical.

However, such a process cannot be used as is to form needles of circular section, because geometric defects appear on the needle. Indeed, as the needles are thin and long, the turning operation can vibrate or shift the body, so that laser machining loses precision to obtain a needle with a circular section.

Summary of the invention

[0007] The present invention proposes to resolve all or part of these drawbacks by means of a needle manufactured according to a process for manufacturing a one-piece watchmaking hand using laser light.

[0008] Said process is remarkable in that it comprises: - a first step consisting of providing a single piece of predefined material, the part extending along a longitudinal axis; - a second step consisting of rotating said one-piece part; - a third step consisting of emitting a first modulation of said laser light, for example in power, and/or in geometry, and/or in time; - a fourth step consisting of exposing a first portion of said at least one monobloc part to said first modulation of said laser light so as to form at least a first volume of circular section, for example cylindrical or conical, of a length L1and d an average diameter D1, the ratio being less than or equal to 10, or even less than or equal to 5; - a fifth step consisting of emitting a second modulation of said laser light, for example in power, and/or in geometry and/or in time; And - a sixth step consisting of exposing a second portion of said at least one single piece to said second modulation of said laser light, so as to form at least a second volume of circular section, for example cylindrical or conical, of a length L2et with an average diameter D2, the ratio being less than or equal to 10, or even less than or equal to 5.

[0009] Thanks to this process, it is possible to manufacture three-dimensional needles of circular section, which are in particular cylindrical or conical. Indeed, on the one hand, thanks to rotary machining, we obtain a circular section shape of the needle. But by making the needle in portions of length L and average diameter D, the ratio of which is less than or equal to 10, or even less than or equal to 5, we avoid the risk of vibration of the one-piece part, and therefore the risk of geometric defects.

[0010] According to a particular embodiment of the invention, the second portion is chosen adjacent to the first portion during the sixth step of the manufacturing process.

[0011] According to a particular embodiment of the invention, said manufacturing method comprises additional steps of modulating emissions of said laser light and exposing additional portions, preferably adjacent to each other, to form additional circular section volumes, for example cylindrical or conical, with a ratio less than or equal to 10, or even less than or equal to 5, in order to obtain a desired needle length.

[0012] According to a particular embodiment of the invention, the first portion is chosen at a free end of the one-piece part.

[0013] According to a particular embodiment of the invention, at least the first volume of circular section has a diameter smaller than the other volumes of circular section.

[0014] According to a particular embodiment of the invention, the volumes of circular section form a needle of a total length Lt, and of an average diameter Dt whose ratio is greater than or equal to 10, or even greater than or equal to 100.

According to a particular embodiment of the invention, most of the portions are machined so that the volumes of circular section have substantially the same length L.

[0016] According to a particular embodiment of the invention, most of the portions are machined so that the volumes of circular section are cylindrical and have substantially the same diameter D.

[0017] According to a particular embodiment of the invention, most of the portions are machined so that the volumes of circular section have a decreasing diameter to form a conical needle.

[0018] According to a particular embodiment of the invention, the method comprises an additional step preceding the sixth step and/or an additional exposure step, in which the one-piece part is moved to expose the second portion or the additional portion .

[0019] According to a particular embodiment of the invention, the method comprises a preliminary step in which a hole is drilled in the one-piece part, for example by laser, in particular in order to be able to insert a watch movement rod.

According to a particular embodiment of the invention, a portion intended for the volume of circular section for the hole is previously machined with a diameter greater than the other volumes of circular section.

[0021] According to a particular embodiment of the invention, the material comprises, preferably in its entirety, either a metal such as steel, titanium, brass, aluminum, an amorphous metal, or an alloy of these metals, either composite or metallic ceramic, or glass, sapphire, diamond, or ruby.

[0022] According to a particular embodiment of the invention, the method comprises an additional step of applying a layer of phosphorescent material to a volume of circular section, the volume of circular section preferably having a reduced diameter compared to to other volumes of circular section.

[0023] The invention also relates to a watchmaking hand capable of being obtained by the method according to the invention, the needle comprising a body of circular section, for example cylindrical or conical, in one piece.

[0024] According to a particular embodiment of the invention, the watch hand comprises a hole.

[0025] According to a particular embodiment of the invention, the watchmaking hand comprises, preferably in its entirety, either a metal such as steel, titanium, brass, aluminum, an amorphous metal, or an alloy of these metals, either composite or metallic ceramic, or glass, sapphire, diamond, or ruby.

The invention also relates to a timepiece comprising such a needle.

Brief description of the figures

[0027] The aims, advantages and characteristics of the present invention will appear on reading several embodiments given solely by way of non-limiting examples, with reference to the appended drawings in which: - Figure 1 represents a method of manufacturing a watchmaking hand of one-piece circular section by laser light according to the invention, – Figure 2 schematically represents a side view of the machining of a watchmaking hand of one-piece circular section obtained by the method of the figure 1, – Figures 3 to 5 schematically represent a side view of the needle after several stages of the method of producing according to the invention, – Figure 6 schematically represents a perspective view of a watchmaking hand of section one-piece circular section obtained by the method of Figure 1, and - Figure 7 schematically represents a side sectional view of a watchmaking hand of one-piece circular section produced by said manufacturing process according to the invention.

Detailed description of the invention

The present invention relates to the use of a laser light source to form a one-piece clockwork hand of circular section. In the embodiment described below, the needle is cylindrical in shape.

According to the invention, said manufacturing method 1, shown in Figures 1 to 5, comprises several stages.

[0030] In a first step 1, we provide ourselves with a one-piece part 7 made of a predefined material. For example, the predefined material comprises, preferably entirely, either a metal such as steel, titanium, brass, aluminum, an amorphous metal, or an alloy of these metals, or composite or metallic ceramic , either glass, sapphire, diamond, or ruby.

Preferably, the titanium alloy is chosen for its lightness. Other materials compatible with laser machining are of course possible.

The one-piece part 7 is preferably elongated along a longitudinal axis 17 with a length at least equal to the length of the desired needle. The one-piece part 7 may be in one piece or has already gone through a roughing stage by machining. The one-piece part 7 is preferably solid, that is to say without any cavity.

The second step 2 consists of rotating said one-piece part 7 to obtain the desired circular section shape, here cylindrical. The one-piece part 7 is machined by a laser machining device. The one-piece part 7 is arranged on a rotating turning device 9, which rotates the one-piece part 7 around its longitudinal axis 17 in order to machine it at its periphery.

[0034] In a third step 3, a first modulation of said laser light 8 is emitted, for example in power, and/or in geometry and/or in time, to cut a portion to the desired diameter, for example using a laser device .

The fourth step 4 consists of exposing a first portion 11 of said at least one monobloc part 7 to said first modulation of said laser light 8, so as to form at least a first cylindrical volume 14 of length L1 and average diameter D1 . In fact, said laser light is modulated according to certain parameters so that upon exposure of at least a first portion 11 of said one-piece part 7, a first cylindrical volume 14 is formed.

[0036] A portion length L1 is chosen so that the ratio is less than or equal to 20 or 10, or even less than or equal to 5. With such a ratio, manufacturing defects are avoided, which occur when the machining length is too large in relation to the diameter of the portion. Indeed, as the laser 8 moves along the portion 11, a portion 11 that is too long in relation to the diameter D tends to bend, so that the machining is no longer precise and causes defects.

[0037] To machine the one-piece part 7, it can also be movable in translation relative to the laser device, the laser device being stationary. Alternatively, the laser device is movable in translation, while the one-piece part 7 is only movable in rotation. The laser device and the one-piece part 7 can both still be movable in translation.

[0038] We then emit in a fifth step 5 a second modulation of said laser light 8, for example in power, and/or in geometry and/or in time.

[0039] In a sixth step 6, at least a second portion 12 of said one-piece part 7 is exposed to said second modulation of said laser light 8, so as to form at least a second cylindrical volume 15 of a length L2 and an average diameter D2. the ratio being less than or equal to 20, preferably 10, or even less than or equal to 5.

The second portion 12 is adjacent to the first portion 11. In other words, they are consecutive, and oriented around the same longitudinal axis 17. Furthermore, it is also possible to configure said second modulation just like said first modulation of the laser light in power and time.

[0041] In this embodiment, we choose to make cylindrical volumes of equal lengths, so that L1=L2=L. In alternative embodiments, the cylindrical volumes can be machined with lengths different from each other, provided that a ratio of less than or equal to 20 or 10, or even less than or equal to 5 is kept for each cylindrical volume.

Depending on the total length Lt of the needle that we wish to obtain, we proceed to expose additional portions 13 of the one-piece part 7, so as to obtain a longer needle 20.

The steps of emission and exposure to modulation of the laser 8 are repeated several times to obtain a plurality of consecutive adjacent cylindrical volumes 14, 15, 16.

[0044] In Figure 2, the first portion 11 of length L is laser machined to form a first cylindrical volume 14 of diameter D and length L at the end of the one-piece part 7, as shown in Figure 3 A second portion 12 of length L is then selected, which is adjacent to the first portion 11.

After laser machining of the second portion 12, a second cylindrical volume 15 is obtained, forming with the first cylindrical volume 14 the end of the needle, as shown in Figure 4.

We then choose a third portion 13 of length L of the one-piece part 7, which is adjacent to the second cylindrical volume 15. The third portion 13 is laser machined to form a third cylindrical volume 16 of average diameter D and length L, shown in Figure 5.

The needle 20 has for example a length of 15 to 20 mm, and an average diameter of 0.2mm to 0.5mm at one end and 0.3mm to 0.6mm at the other end.

The laser machining steps are repeated on additional adjacent portions until the desired total length Lt for the needle 20 is obtained. Thus, the needle 20 comprises a one-piece cylindrical body.

Preferably, the cylindrical volumes 14, 15, 16 obtained have substantially the same diameter D, so that the needle 20 has a substantially equal diameter over its entire length Lt.

The consecutive cylindrical volumes 14, 15, 16 form a needle 20 of a total length Lt whose ratio is preferably greater than or equal to 10, or even greater than or equal to 100.

[0051] The method may further include a subsequent surface finishing step on the adjacent volumes 14, 15, 16 to ensure that the shape and finish are substantially continuous. This step can be carried out by laser with gentler parameters to produce a surface with low roughness and make the interface between two consecutive treated volumes disappear.

[0052] The method may further comprise a step of drilling a hole 21 to be able to insert a rod, the drilling step being able to be carried out before or after laser machining.

Preferably, the hole is made beforehand through a portion of the one-piece part 7, that is to say before the machining of the cylindrical volume 24 comprising the hole 21. Thus, the needle 20 of Figures 6 and 7 has a hole 21 for inserting the stem of a watch movement. By drilling hole 21 before laser machining, we avoid doing it in the needle, which is too thin. The one-piece part 7 being wider, it is easier to hold it to drill hole 21.

[0054] Preferably, at least part of the cylindrical volume 24 comprising the hole 21 has a diameter greater than the other cylindrical volumes, in particular so that the hole 21 is deep enough to accommodate the rod and the cylindrical volume 24 is sufficiently solid. . The hole 21 can be drilled by different machining techniques, in particular by laser.

[0055] In a particular variant embodiment, shown in Figures 6 and 7, at least one cylindrical volume 22 of the end of the needle 20 has a reduced diameter. Reducing the diameter makes it possible to deposit on the reduced cylindrical volume a layer of phosphorescent material 23. This makes it possible, for example, to obtain an end of the needle 20 of the same diameter as the other cylindrical volumes 22. For this, we choose a diameter of cylindrical volume 22 reduced by the thickness of the layer of phosphorescent material 23 applied subsequently.

One of the advantages of this process is the manufacture of a one-piece cylindrical watchmaking hand 20, which is more rigid than a flat needle, and which also provides a particular aesthetic effect to the needle 20.

[0057] Furthermore, the needle 20 also having a hole 21 formed directly in the one-piece needle 20, we avoid adding an additional part provided with a barrel, and which must be assembled on the needle 20 in order to be able to hold the needle 20 on a rod of the clockwork movement. Thus, assembly difficulties are reduced, as well as the risk of disassembly.

Naturally, the invention is not limited to the embodiment described with reference to the figures, and variants could be considered without departing from the scope of the invention. Thus, the process can be used to form a needle of conical shape, by forming conical portions whose diameter decreases one after the other. It is also possible to form a needle whose diameter varies with different volumes provided that they are of circular section.

Claims (18)

1. Process for manufacturing (10) a one-piece watchmaking hand using laser light, characterized in that said manufacturing process (1) comprises: – a first step (1) consisting of providing a single piece part (7) of predefined material, the part extending along a longitudinal axis; – a second step (2) consisting of rotating said one-piece part (7); – a third step (3) consisting of emitting a first modulation of said laser light (8), for example in power, and/or in geometry, and/or in time; – a fourth step (4) consisting of exposing a first portion (11) of said at least one single piece (7) to said first modulation of said laser light (8), so as to form at least a first volume of circular section (14), for example cylindrical or conical, of a length L1 and an average diameter D1, the ratio being less than or equal to 20, preferably 10, or even less than or equal to 5; – a fifth step (5) consisting of emitting a second modulation of said laser light (8), for example in power, and/or in geometry, and/or in time; And – a sixth step (6) consisting of exposing a second portion (12) of said at least one single piece (7) to said second modulation of said laser light (8), so as to form at least a second volume of circular section (15), for example cylindrical or conical, of a length L2 and an average diameter D2, the ratio being less than or equal to 20, preferably 10, or even less than or equal to 5. 2. Manufacturing method (10) according to claim 1, wherein the second portion (12) is chosen adjacent to the first portion (11) during the sixth step (6). 3. Manufacturing method (10) according to claim 1 or 2, comprising additional steps of modulating emissions of said laser light (8) and exposing additional portions (13), preferably adjacent to each other, to form additional circular section volumes (16), for example cylindrical or conical, with a ratio less than or equal to 20, preferably 10, or even less than or equal to 5, in order to obtain a needle length (20) desired. 4. Manufacturing method (10) according to any one of the preceding claims, wherein the first portion (11) is chosen at a free end of the one-piece part (7). 5. Manufacturing method (10) according to any one of the preceding claims, in which at least the first volume of circular section (14) has a diameter smaller than the other volumes of circular section (15, 16). 6. Manufacturing method (10) according to any one of the preceding claims, in which the volumes of circular section (14, 15, 16) form a needle (20) of a total length Lt and a diameter average Dt, whose ratio is greater than or equal to 10, or even greater than or equal to 100. 7. Manufacturing method (10) according to any one of the preceding claims, in which most of the portions (11, 12, 13) are machined so that the volumes of circular section (14, 15, 16) have substantially the same length L. 8. Manufacturing method (10) according to any one of the preceding claims, in which most of the portions (11, 12, 13) are machined so that the volumes of circular section (14, 15, 16) are cylindrical and have substantially the same diameter D. 9. Manufacturing method (10) according to any one of claims 1 to 7, in which most of the portions are machined so that the volumes of circular section have a decreasing diameter to form a conical needle. 10. Manufacturing method (10) according to any one of the preceding claims, comprising an additional step preceding the sixth step (6) and/or an additional exposure step, in which the one-piece part (7) is moved. to expose the second portion (12) or the additional portion (13). 11. Manufacturing method (10) according to any one of the preceding claims, comprising a preliminary step in which a hole (21) is drilled in the one-piece part (7), for example by laser, in particular in order to be able to insert a clockwork stem. 12. Manufacturing method (10) according to claim 11, in which the portion of one-piece part (7) provided with the hole (21) is machined with a diameter greater than the other volumes of circular section (11, 12, 13). 13. Manufacturing method (10) according to any one of the preceding claims, in which the material comprises, preferably entirely, either a metal such as steel, titanium, brass, aluminum, a amorphous metal, or an alloy of these metals, either composite or metallic ceramic, or glass, sapphire, diamond, or ruby. 14. Manufacturing method (10) according to any one of the preceding claims, comprising an additional step of applying a layer of phosphorescent material (23) to a circular section volume (22), the section volume circular (22) preferably having a reduced diameter. 15. Watchmaking hand (20) capable of being obtained by the method (10) according to any one of the preceding claims, characterized in that it comprises a body of circular section, for example cylindrical or conical, monobloc. 16. Clockwork hand (20) according to claim 15 comprising a hole (21) for a clockwork movement rod. 17. Watchmaking hand (20) according to claim 15 or 16, comprising, preferably entirely, either a metal such as steel, titanium, brass, aluminum, an amorphous metal, or an alloy of these metals, either composite or metallic ceramics, or glass, sapphire, diamond, or ruby. 18. Timepiece comprising a timepiece hand (20) according to any one of claims 15 to 17.