EXTERNAL PART ELEMENT FOR TIMEPIECE OR PIECE OF JEWELLERY AND METHOD FOR MANUFACTURING SUCH AN EXTERNAL PART ELEMENT

Abstract

An external part element or component for a timepiece or piece of jewellery made with a fibre-reinforced polymer matrix composite material, this external part element including on at least one of the faces thereof at least one cavity wherein an insert made of metallic glass is housed. A method for manufacturing such an external part element is also described.

Claims

1. The external part element or component for a timepiece or piece of jewellery made with a fibre-reinforced polymer matrix composite material, said external part element comprising on at least one of the faces thereof at least one cavity wherein an insert made of metallic glass is housed.

2. The external part element or component according to claim 1, wherein the polymer material used to form the matrix is thermoplastic or thermosetting.

3. The external part element or component according to claim 2, wherein the polymer material is chosen in the group formed by polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE) and polyamide-imide (PAI).

4. The external part element or component according to claim 2, wherein the fibres which reinforce the polymer matrix are chosen in the group formed by glass fibres, carbon fibres and aramid fibres.

5. The external part element or component according to claim 3, wherein the fibres which reinforce the polymer matrix are chosen in the group formed by glass fibres, carbon fibres and aramid fibres.

6. The external part element according to claim 5, wherein the composite material is composed of 35% PEEK polymer and 65% carbon fibres within plus or minus 10%.

7. The external part element or component according to claim 1, wherein the metallic glass used to produce the insert is bulk metallic glass or BMG type.

8. The external part element or component according to claim 7, wherein the metallic glass used to produce the insert contains zirconium or platinum.

9. The external part element or component according to claim 8, wherein the metallic glass used to produce the insert results, apart from the unavoidable impurities, from an alloy of zirconium, copper, nickel, aluminium and/or niobium and/or titanium.

10. The external part element or component according to claim 9, wherein the metallic glass used to produce the insert comprises, as a mass percentage, zirconium, copper, titanium, nickel, aluminium and niobium according to the following quantities: 60≤Zr≤75 10≤Cu≤20 0≤Ti≤6 7≤Ni≤15 0≤Al≤8 0≤Nb≤6

11. The external part element or component according to claim 10, wherein the metallic glass used to produce the insert is an alloy with the composition Zr70Cu13Ni9.9A13.65 Nb3.4 as a mass percentage, or an alloy with the composition Zr65.7Cu15.6Ni11.7A13.7Ti3.3 as a mass percentage.

12. The external part element or component according to claim 8, wherein the metallic glass used to produce the insert comprises, as a mass percentage, platinum, copper, nickel and phosphorus according to the following quantities: 80≤Pt≤90 5≤Cu≤10 1≤Ni≤3 4≤P≤7

13. The external part element or component according to claim 12, wherein the metallic glass used to produce the insert is, as a mass percentage, given by the composition Pt85Cu7Ni2.3P5.7.

14. The external part element or component according to claim 7, wherein the metallic glass used to produce the insert has a vitreous transition temperature less than or equal to 350° C.

15. The external part element or component according to claim 1, wherein the external part element for a timepiece or piece of jewellery is a back, a middle, a bezel, a bracelet link or a clasp.

16. A method for manufacturing an external part element or component for a timepiece or piece of jewellery comprising the steps of: producing the external part element or component with a fibre-reinforced polymer matrix composite material; machining at least one cavity in at least one of the faces of the eternal part element; heating a metallic glass to the melting point thereof; filling the at least one cavity with metallic glass by injection to form an insert; performing, if required, finishing operations.

17. The manufacturing method according to claim 16, wherein the cavity is produced by milling.

18. The manufacturing method according to claim 17, wherein the finishing operations consist of removing the excess material, polishing and/or trimming the insert.

19. The manufacturing method according to claim 17, wherein the cavities have an undercut angle between 5 and 10°.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0042] Further features and advantages of the present invention will emerge more clearly from the following detailed description of an embodiment of an external part element for a timepiece or piece of jewellery according to the invention, this example being given purely by way of illustration and not merely limitation, with reference to the appended drawing wherein:

[0043] FIG. 1 is a top view of a watch bezel according to the invention;

[0044] FIG. 2 is a sectional view along the line B-B in FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

[0045] The present invention is based on the general inventive concept which consists of providing external part elements for a timepiece or piece of jewellery which have mechanical and aesthetic features meeting the requirements in the field of watchmaking. To this end, the present invention discloses producing such external part elements by means of a fibre-reinforced polymer matrix composite material, then arranging on the surface of such external part elements at least one cavity wherein a decorative or functional insert made of metallic glass will be housed. Thanks to the use of a fibre-reinforced polymer matrix composite material, the external part element according to the invention has mechanical wear resistance and aesthetic features which make it perfectly suitable for horological applications. Moreover, the inserts, produced by injecting a metallic glass, form solid blocks having a sufficient thickness to enable them to withstand external mechanical attacks. Furthermore, given that these inserts are thick, they easily withstand the finishing operations which will give them maximum brightness and brilliance. Finally, these inserts are produced in a single injection step, which makes it possible to save considerable time and ensure excellent manufacturing precision of these inserts.

[0046] Designated as a whole by the general reference number 1, the bezel represented in FIG. 1 is an example of an external part element for a timepiece according to the invention. Further external part elements such as a back, middle, bracelet links and clasp can also be contemplated.

[0047] According to the invention, the bezel 1 is produced by means of a fibre-reinforced polymer matrix composite material. By way of illustrative and non-limiting example only, the polymer material used to form the matrix is thermoplastic or thermosetting. This polymer material is preferably chosen in the group formed by polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE) and polyamide-imide (PAI). This matrix is reinforced by fibres which are preferably chosen in the group formed by glass fibres, carbon fibres and aramid fibres. A plurality of these bezels 1 can be individualized in a plate of composite material of required thickness.

[0048] For example, an external part element such as a bezel 1 according to the invention can be produced with a SPIDE TP type filament winding method developed by the French mechanical expertise centre CETIM. Explained very briefly, this filament winding method consists of winding fibres previously impregnated with a polymer material on a mould, for example such as a tube of cylindrical cross-section, in order to obtain a profile. At the same time as these pre-impregnated polymer fibres are wound around the mould according to a given number of layers and according to an angle with respect to the longitudinal axis of symmetry of the mould which is chosen particularly as a function of the subsequent use of the resulting parts which will be obtained by cutting the profile, they are heated to a sufficiently high temperature to cause the melting of the polymer with which they are impregnated and pressed against the mould. Finally, the resulting parts are machined conventionally by means of lathes and milling machines to bring them to their final dimensions.

[0049] In the case of the present invention, the bezels 1 are cut in a tubular profile in which the internal diameter is typically of the order of 30 mm and in which the external diameter is 45 mm. The tubular profile wherein the bezels 1 according to the invention are cut is obtained by winding carbon fibres in which the diameter is typically of the order of 5 to 25 μm and which are impregnated with polyetheretherketone (PEEK) in which the melting point is 341° C. To obtain the tubular profiles sought wherein the bezels 1 according to the invention will be subsequently cut, the carbon fibres are preferably wound according to an angle of 90° perpendicularly to the longitudinal axis of symmetry of the tubular profile.

[0050] The tubular profiles used to produce particularly the bezels 1 are typically composed of approximately 35% PEEK polymer and 65% carbon fibres within plus or minus 10%. It is therefore understood that the external part elements obtained from these tubular profiles contain a large proportion of carbon fibres, which substantially improves the thermal conductivity thereof and enables them to rapidly diffuse the heat input during the injection of the metallic glass. Consequently, although the temperature at which the metallic glass is injected is greater than the melting point of the polymer matrix, the bezels 1 are not decomposed, nor are they distorted. It will also be noted that the reduced thickness of the injected inserts combined with the good thermal conductivity of the mould and the composite material considerably reduce the exposure time of the polymer to a temperature higher than the melting point thereof. Consequently, it is not necessary to take specific additional measures to limit the degradation of the polymer during the brief contact with the metallic glass. The visible parts of the composite having potentially been in contact with the metallic glass will moreover be removed during surface finishing operations after removal from the mould.

[0051] The bezel 1 comprises on a top face 2 one or more cavities 4 typically produced by milling. According to the invention, these cavities 4 will be filled by means of a metallic glass type material to form inserts 6. Non-restrictively, as seen in FIG. 1, these inserts 6 indicate numerals and indexes for example of triangular or circular shape. Preferably, these cavities 4 have an undercut angle a between 5 and 10° to ensure superior mechanical strength of the inserts 6.

[0052] The metallic glass used to produce the inserts 6 is bulk metallic glass (BMG) type. Preferably, this metallic glass contains zirconium. It is possible for example to use an alloy containing, apart from the unavoidable impurities, zirconium, copper, titanium, nickel, aluminium and niobium. According to a non-limiting example, the metallic glass used to produce the insert comprises these materials as a mass percentage according to the following quantities: [0053] 60≤Zr≤75 [0054] 10≤Cu≤20 [0055] 0≤Ti≤6 [0056] 7≤Ni≤15 [0057] 0≤Al≤8 [0058] 0≤Nb≤6

[0059] An example of a metallic glass containing zirconium which is suitable for the needs of the invention is the alloy Vit106a with the composition Zr70Cu13Ni9.9A13.65Nb3.4 as a mass percentage, or Vit105 with the composition Zr65.7Cu15.6Ni11.7A13.7Ti3.3 as a mass percentage.

[0060] The metallic glass used for producing the inserts 6 can also be based on platinum. It is possible for example to use an alloy containing, apart from the unavoidable impurities, platinum, copper, nickel, aluminium and phosphorus. According to a non-limiting example, the metallic glass used to produce the insert comprises these materials as a mass percentage according to the following quantities: [0061] 80≤Pt≤90 [0062] 5≤Cu≤10 [0063] 1≤Ni≤3 [0064] 4≤P≤7

[0065] According to a further special embodiment of the invention, the metallic glass used to produce the insert is, as a mass percentage, given by the composition Pt85Cu7Ni2.3P5.7.

[0066] According to a further special embodiment of the invention, the metallic glass used to produce the insert has a vitreous transition temperature less than or equal to 350° C.

[0067] According to the invention, to form the inserts 6, the cavities 4 are filled with metallic glass by injection. For this purpose, a metallic glass ingot is provided, which is placed in a melting chamber and is heated to a temperature greater than the melting temperature thereof. Once the metallic glass ingot has melted, the metallic glass is injected into a mould wherein the bezel 1 is placed and which is arranged such that the metallic glass fills the cavities 4 of this bezel 1. The injection of the metallic glass into the mould wherein the bezel 1 is placed can be carried out by mechanical pressure supplied by a piston or by pressure from a gas. The cavities 4 are preferably filled with a slight extra thickness of metallic glass so as to provide an optimal link between the bezel 1 and the inserts 6.

[0068] After cooling the metallic glass, the bezel 1 is removed from its mould and can undergo finishing operations such as removing excess material, grinding and/or mechanical or chemical polishing. Any additional thicknesses and burrs are also removed by trimming.

[0069] It goes without saying that the present invention is not limited to the embodiment that has just been described, and that miscellaneous modifications and simple variants may be contemplated by the person skilled in the art without departing from the scope of the invention as defined by the appended claims. It will be understood in particular that, within the scope of the invention, it is necessary to momentarily heat the metallic glass to the melting point thereof so that it can be injected by means of an injection machine.

LIST OF REFERENCES

[0070] 1. Bezel

[0071] 2. Top face

[0072] 4. Cavities

[0073] 6. Inserts