HK1192195B - Piece of casing for a time piece and system for manufacturing same - Google Patents

Description

External part for a timepiece and system for manufacturing the same

Technical Field

The invention relates to an external part for a timepiece and a system for manufacturing the external part.

Background

It is known to form sapphire cover glasses that are very scratch resistant. These surface glasses are usually manufactured by placing a rotating grinding wheel in contact with the surface of a drum carrying several surface glasses. The resulting grinding operation can form a cylindrical or spherical surface glass. However, there is currently a need to form an asymmetric crystal, for example to be fitted to a timepiece display that is not centred with respect to the timepiece case, which is not possible with current continuous manufacturing techniques.

Disclosure of Invention

It is an object of the present invention to overcome all or part of the aforementioned drawbacks by proposing a new manufacturing system that allows the continuous production of a specific surface glass, the longitudinal curvature/bending (courbury) of which is independent of the transverse curvature.

The invention therefore relates to a system for manufacturing an external part for a timepiece, comprising: a fixture comprising a drum rotatably mounted along a first axis and carrying at least one blank of the component; -a processing apparatus comprising grinding means rotatably mounted along a second axis and intended for processing said at least one blank so as to form a first curvature, said system being characterized in that said processing apparatus further comprises means for moving said second axis so that said apparatus is movably mounted along a curved directrix for selectively forming a second curvature in said at least one blank; and the first axis and the second axis are perpendicular such that the processing lines intersect.

It is therefore clear that at least one of the curvatures of the external part is directly formed by the selective movement (i.e. completely free and controlled movement) of the axis of rotation of the grinding device. Thus, very complex surface glasses can be manufactured continuously with a favorable reject rate, while facilitating the subsequent polishing step.

According to other advantageous features of the invention:

-the directrix of the moving means is symmetrical so as to form the second curvature on a single radius;

-the directrix of the moving means is asymmetric so as to form the second curvature over several radii;

-according to a first embodiment, the drum is a ring, the at least one blank is fixed against the inner wall of the ring, and the grinding means are moved in the hollow of the ring so as to form a first and a second concave curvature;

according to a second embodiment, the drum is a disc, the at least one blank is fixed against the outer wall of the disc, and the grinding means are moved in front of the disc so as to form a first and a second concave curvature;

-the grinding means are formed by a grinding wheel;

according to a first variant, the moving means are formed by an actuator moving back and forth against the profile of a fixed cam corresponding to the second curvature;

according to a second variant, the moving means are formed by an automated apparatus programmed to move along the second curvature;

-the outer part is formed from crystalline alumina.

Furthermore, the invention relates to an external part comprising a top face and a bottom face, characterized in that at least one of the faces has a different longitudinal curvature and a transverse curvature; and at least one of the longitudinal curvature and the transverse curvature is asymmetric.

It is therefore clear that the external part can be complex and can for example form an asymmetric crystal or a crystal whose outline appears to be asymmetric, for example to be fitted to a timepiece display which is not centred with respect to the timepiece case.

According to other advantageous features of the invention:

-the bottom and top faces comprise different longitudinal and transverse curvatures;

-the outer part is formed from crystalline alumina.

Finally, the invention relates to a timepiece, characterized in that it comprises an external part according to any one of the preceding variants.

Drawings

Further characteristics and advantages will emerge clearly from the description that follows, given by way of non-limiting illustration, with reference to the accompanying drawings, in which:

figure 1 is a view of a manufacturing system according to a first embodiment of the invention;

figures 2 to 4 are views of a manufacturing system according to a second embodiment of the invention;

figures 5 to 7 are views of an external part according to a first variant of the invention;

figures 8 to 10 are views of an external part according to a second variant of the invention.

Detailed Description

The present invention relates to an asymmetric outer part, such as a watch crystal, case or dial, made of a material based on crystalline alumina, such as sapphire, corundum or ruby. In order to manufacture these new components, new manufacturing systems have been developed, for example suitable for timepiece displays that are not centred with respect to the timepiece case. For example, the housing may be substantially tear drop shaped and/or non-planar in form, requiring an off-centre display to be provided to allow the timepiece to be coordinated.

Of course, although the invention has been developed in the field of timepieces, it is not limited thereto. Other applications, such as optics, tableware or electronics, are also contemplated.

According to a first embodiment, shown in fig. 1, a manufacturing system 1 has been developed for manufacturing an external part 3, said external part 3 comprising a curvature C thereof₁、C₂A concave surface. The manufacturing system 1 includes a fixing apparatus 5 and a processing apparatus 7.

The fixing device 5 comprises a drum 11, which drum 11 is rotatably mounted along a first axis a1 and carries at least one blank 3' of the future part 3. Preferably, as shown in fig. 1, the drum 11 is a ring comprising a faceted inner wall, i.e. provided with a continuous plane P_x. As shown in fig. 1, each successive plane P_xReceiving a blank 3' which can be fixed, for example, by gluing.

The processing device 7 comprises grinding means 13, said grinding means 13 being along a second axis a₂Rotatably mounted and used for machining each blank 3'. Preferably, the grinding means 13 move in the hollow of the annular drum 11. The grinding device 13 shown in fig. 1 is formed by a conventional grinding wheel, i.e. its contact area does not have any particular shape. Of course, the grinding means 13 may be different, for example, may be curved or conicalIn the form of a boring bar (sabot).

Advantageously according to the invention, the machining device 7 comprises a second axis a₂Means 15 for moving said apparatus so that said apparatus follows a curved directrix C₂Movably mounted to selectively form a second curvature in each blank 3'. It is thus clear that the manufacturing system 1 can form the first and second concave curvatures C₁、C₂。

According to the invention, in a non-limiting manner, the movement means 15 can be caused to abut in correspondence with the second curvature C₂Or for example by an automated device programmed to move along said second curvature.

Therefore, the first curvature C₁To be on the axis A₁The radius extending between the contact area between the grinding means 13 and each blank 3' is perpendicular to the axis A₁And (4) generating. Due to the drum 11 along the axis A₁A rotary movement, whereby each blank 3' is hollowed out transversely along a single radius, so as to form a first concave curvature C₁。

Furthermore, advantageously according to the invention, the second curvature C₂By selectively moving the second axis A₂But is directly obtained. Therefore, the first curvature C is generated₁At the same time, the contact area between the grinding means 13 and each blank 3' is gradually shifted with respect to the thickness of the annular drum 11. Thus, each blank 3' is hollowed longitudinally along a curved directrix, so as to form a second concave curvature C₂。

It is therefore clear that the bending directrix of the moving means 15 can be symmetrical or asymmetrical so as to form the second curvature C on one or several radii₂。

Finally, preferably according to the invention, the first axis a₁And a second axis A₂Are perpendicular so that the processing lines cross. This feature advantageously facilitates subsequent polishing of the outer component 3.

According to a second embodiment, illustrated in figures 2 to 4, the manufacturing system 21 has been developed to form an external part 23, said external part 23 comprising a curvature C thereof₃、C₄Is a convex surface. The manufacturing system 21 includes a fixture 25 and a processing device 27.

The fixing device 25 comprises a drum 31, the drum 31 being along a first axis a₃Rotatably mounted and carrying at least one blank 23' of a future part 23. Preferably, as shown in fig. 2, the drum 21 is a circular disc, to the outer wall of which each blank 23' is fixed, for example by gluing.

The machining device 27 comprises grinding means 33, said grinding means 33 being along a second axis a₄Rotatably mounted and used to machine each blank 23'. Preferably, the grinding device 33 moves in front of the drum 31. The grinding device 33 shown in fig. 2 is formed by a conventional grinding wheel, i.e. its contact area does not have any particular shape. Of course, the grinding device 33 may be different, for example in the form of a curved or conical boring bar, as will be explained below.

Advantageously according to the invention, the machining device 27 comprises a second axis a₄Means 35 for moving the apparatus so that it follows the curved directrix C₄Movably mounted to selectively form a second curvature in each blank 23'. It is thus clear that the manufacturing system 21 can form the first and second convex curvatures C₃、C₄。

According to the invention, in a non-limiting manner, the movement means 35 may be caused to abut in correspondence with the second curvature C₄Or for example by an automated device programmed to move along said second curvature.

Therefore, the first curvature C₃To be on the axis A₃The radius extending between the contact area between the grinding means 33 and each blank 23' is perpendicular to the axis A₃And (4) generating. Due to the drum 31 along the axis A₃The rotation of the rotating body is carried out,each blank 23' is therefore hollowed out transversely on a single radius, so as to form a first convex curvature C₃。

Furthermore, advantageously according to the invention, the second curvature C₄By selectively moving the second axis A₄But is directly obtained. Thus, the first curvature C is generated₃At the same time, the contact area between the grinding means 33 and each blank 23' is gradually shifted with respect to the thickness of the annular drum 31. Thus, each blank 23' is hollowed longitudinally along a curved directrix, so as to form a second convex curvature C₄。

It is therefore clear that the bending directrix of the moving means 35 can be symmetrical or asymmetrical so as to form the second curvature C on one or several radii₄。

Finally, preferably according to the invention, the first axis a₃And a second axis A₄Are perpendicular so that the processing lines cross. This feature advantageously facilitates subsequent polishing of the outer member 23. The polishing may be performed, for example, using a fixing and processing device close to the fixing device 25 and the processing device 27 of the blank forming the part 23 described above. However, since the polishing step is much less invasive to the thickness to be removed, it is mainly only a modified grinding device.

Thus, two polishing examples are shown in fig. 3 and 4. According to a first alternative of the second embodiment shown in fig. 3, the manufacturing system 41 has been developed to polish an outer part 43, said outer part 43 comprising a curvature C thereof₃、C₄Is a convex surface. The manufacturing system 41 includes a fixture 45 and a processing device 47.

The holding device 45 comprises a rotatably mounted drum 51, said drum 51 carrying at least one component 43 to be polished. The processing device 47 comprises a rotatably mounted grinding device 53 designed to polish each component 43. Preferably, the grinding device 53 moves in front of the drum 51. The grinding device 53 shown in fig. 3 is preferably formed by a conical boring bar, for example made of metal, regularly coated with a liquid polishing agent. Of course, other types of abrading devices, such as substantially flat devices, may also be suitable.

Advantageously according to the invention, the machining device 47 comprises moving and pressing means 55 to force the grinding means 53 to rub on each part 43, so as to selectively follow the second curvature C₄The part is polished. It is thus clear that the manufacturing system 41 polishes the first and second convex curvatures C₃、C₄。

According to the invention, in a non-limiting manner, the movement means 55 can be caused to abut in correspondence with the second curvature C₄Or for example by an automated device programmed to move along said second curvature.

According to a second alternative of the second embodiment shown in fig. 4, the manufacturing system 61 has been developed to polish an outer part 63, said outer part 63 comprising a curvature C thereof₃、C₄Is a convex surface. The manufacturing system 61 includes a fixture 65 and a processing device 67.

The fixture 65 comprises a rotatably mounted drum 71, said drum 71 carrying at least one component 63 to be polished. The machining device 67 comprises an abrasive means 73 designed to polish each part 63. Preferably, the grinding device 73 moves in front of the drum 71. The grinding device 73 shown in fig. 4 is preferably formed by a curved boring bar, for example made of metal, regularly coated with a liquid polishing agent.

Advantageously according to the invention, the machining device 67 comprises moving and pressing means 75 to force the grinding means 73 to rub on each part 63, so as to selectively follow the second curvilinear portions C₄The part is polished. It is thus clear that the manufacturing system 61 polishes the first and second convex curvatures C₃、C₄。

According to the invention, in a non-limiting manner, the movement means 75 can be caused to abut against a portion corresponding to the second curvature C₄To be fixedAn actuator moving back and forth along the profile of the fixed cam, or for example by an automated device programmed to move along said second curvature.

These first and second embodiments and their variations may be used alone or in combination. Thus, a wide variety of exterior parts can be obtained, especially depending on whether the top and/or bottom surfaces thereof are machined. It is clear that advantageously according to the invention at least one of the top and bottom surfaces may comprise different longitudinal and transverse curvatures.

Furthermore, at least one of said longitudinal and transversal curvatures may be symmetrical or asymmetrical, depending on the orientation of each component 3', 23', 43, 63 with respect to the fixing device 5, 25, 45, 65. It is therefore clear that an asymmetric outer part of this type can be well formed, for example, as a crystal glass, case or dial for a timepiece, made of a material based on crystalline alumina, such as sapphire, corundum or ruby.

Two variant parts 83, 103 forming a watch crystal that can be made according to the invention are shown in figures 5-7 and 8-10. According to a first variant, the external part 83 comprises a top surface 82 and a bottom surface 84, said top and bottom surfaces 82, 84 being machined so as to obtain a substantially constant thickness e, regardless of the complex shape of the part 83₁。

Thus, FIG. 5 is a top view of a generally oval-shaped member 83. Longitudinal curvature C₄At point O₁And a transverse curvature part C₃And (6) cutting. It should be noted that point O₁Not centered with respect to the generally oval shape, but closer to the flared portion than to the tip portion. This configuration of the part 83, when added to the timepiece case, visually enhances the eccentric integration of the timepiece display.

As seen in FIG. 7, which shows section A-A (i.e., a longitudinal section) of FIG. 5, a curvature C is seen₂And C₄Are parallel. In the examples of fig. 5 to 7, it should be noted that the curvature portion C₂And C₄In fact each form a single radius R₂And R₄So that R is₄=R₂+e₁。

Also, as seen in FIG. 6, which shows section B-B (i.e., a transverse section) of FIG. 5, a curvature C can be seen₁And C₃Are parallel. In the examples of fig. 5 to 7, it should be noted that the curvature portion C₁And C₃In fact each form a single radius R₁And R₃So that R is₃=R₁+e₁。

The part 83 is thus well curved and may for example form a seemingly asymmetric crystal, for example to be fitted to a timepiece display that is not centred with respect to the timepiece case.

According to a second variant, the external part 103 comprises a top surface 102 and a bottom surface 104, wherein only the top surface is machined so as to obtain a substantially constant thickness e on its edges, irrespective of the complex shape of the part 103₂。

Thus, fig. 9 is a perspective view of a generally oval-shaped member 103. Longitudinal curvature C₄At point O₂And a transverse curvature part C₃And (6) cutting. It should be noted that point O₂Not centered with respect to the generally oval shape, but closer to the flared portion than to the tip portion. This configuration of part 103, when added to a timepiece case, visually enhances the off-center integration of the timepiece display.

As seen in FIG. 10, which shows section C-C (i.e., a longitudinal section) of FIG. 9, the curvature C is seen₄Is asymmetrical. In the examples of fig. 8 to 10, it should be noted that the curvature portion C₃In fact forming a single radius R₃Curvature part C₄Form two adjacent radii R₄And R'₄. Thus, between the edge of the expansion part and the point O₂Radius R between₄Greater than the edge between the tip and the point O₂Radius R 'of'₄。

Thus, the component 103 is very complex and may for example be formed as a non-planarA symmetrical crystal, for example to be fitted to a timepiece display that is not centred with respect to the timepiece case. In this respect, the maximum thickness e of the component 103₃Passing through virtual point O₂Vertically oriented and of minimum thickness e₂All around the edge of the part 103.

Of course, the invention is not limited to the illustrated examples, but is capable of variations and modifications that may occur to those skilled in the art. In particular, other variants are conceivable, depending on whether the top and/or bottom surface is/are machined transversely and longitudinally with one or several radii.

Claims (13)

1. A system (1, 21, 41, 61) for manufacturing an external part (3, 23, 43, 63, 83, 103) for a timepiece, said system comprising: a fixing device (5, 25, 45, 65) comprising a first axis (A)₁，A₃) A drum (11, 31, 51, 71) rotatably mounting and carrying at least one blank (3', 23') of said component; a processing device (7, 27, 47, 67) comprising a second axis (A)₂，A₄) Rotatably mounted and used for machining said at least one blank so as to form a first curvature (C)₁，C₃) Said system being characterized in that said processing means (7, 27, 47, 67) further comprise a second axis (A)₂，A₄) Moving means (15, 35, 55, 75) for movably mounting the tooling along a curved guideline for selectively forming a second curvature (C) in the at least one blank₂，C₄) (ii) a And, the first axis (A)₁，A₃) And said second axis (A)₂，A₄) Are perpendicular so that the processing lines intersect.

2. The system (1, 21, 41, 61) according to claim 1, characterized in that the directrix of the moving means is symmetrical so as to form the second curvature on a single radius.

3. The system (1, 21, 41, 61) according to claim 1, wherein the directrix of the moving means is asymmetric so as to form the second curvature over a plurality of radii.

4. System (1, 21, 41, 61) according to claim 1, characterized in that said drum (11, 31, 51, 71) is a ring, said at least one blank (3', 23') being fixed against the inner wall of said ring; and the grinding means (13, 33, 53, 73) are moved in the hollow of the ring so as to form a first and a second concave curvature.

5. System (1, 21, 41, 61) according to claim 1, characterized in that said drum (11, 31, 51, 71) is a disc, against the outer wall of which said at least one blank (3', 23') is fixed; and the grinding means (13, 33, 53, 73) are moved in front of the disc so as to form a first and a second convex curvature.

6. System (1, 21, 41, 61) according to claim 1, characterized in that said grinding means (13, 33, 53, 73) are formed by a grinding wheel.

7. System (1, 21, 41, 61) according to claim 1, characterized in that said moving means (15, 35, 55, 75) are formed by an actuator moving back and forth against the profile of a fixed cam corresponding to said second curvature.

8. The system (1, 21, 41, 61) according to claim 1, characterized in that said moving means (15, 35, 55, 75) are formed by an automated device programmed to move along said second curvature.

9. The system (1, 21, 41, 61) according to claim 1, wherein said components are formed of crystalline alumina.

10. External part (3, 23, 43, 63, 83, 103) for a timepiece comprising a top face (82, 102) and a bottom face (84, 104), characterized in that at least one of the top face (82, 102) and bottom face (84, 104) comprises portions of different longitudinal curvature (C)₂，C₄) And a lateral curvature part (C)₁，C₃) (ii) a And, the longitudinal curvature section (C)₂，C₄) And a lateral curvature part (C)₁，C₃) Is asymmetric.

11. Component (3, 23, 43, 63, 83, 103) according to claim 10, characterized in that the top surface (82, 102) and the bottom surface (84, 104) comprise different longitudinal curvatures (C)₂，C₄) And a lateral curvature part (C)₁，C₃)。

12. The component (3, 23, 43, 63, 83, 103) of claim 10, characterized in that the component is formed of crystalline alumina.

13. Timepiece, characterized in that it comprises an external part (3, 23, 43, 63, 83, 103) according to any one of claims 10 to 12.