CH719329B1 - Component for a timepiece or jewelry piece and its manufacturing process - Google Patents

Abstract

The invention relates to a component for a timepiece or piece of jewelry, such as a decorative element (1), made using a composite material with a polymer matrix reinforced by fibers. This component (1) comprises on at least one of its faces (2) at least one cavity (4) in which an insert made of metallic glass is housed. The invention also relates to a method for manufacturing such a component, comprising a step of injecting the metallic glass into the cavity (4) to form the insert.

Description

Technical field of the invention

[0001] The present invention relates to a decorative element for a timepiece or piece of jewelry. The present invention also relates to a method of manufacturing such a decorative element.

Technological background

[0002] Numerous methods for manufacturing decorative elements for timepieces or jewelry pieces such as backs, middles, bezels or even bracelet links have already been proposed. Among these known manufacturing methods, mention may be made of methods for manufacturing such decorative elements using composite materials obtained by dispersing fibers in a polymer matrix. Examples of these composite materials are, for example, polymer matrices in which carbon fibers are dispersed, also known by their English name Carbon Fiber Reinforced Polymers or CFRP.

[0003] In practice, it has been observed that the exterior elements for timepieces or jewelry pieces made using such composite materials regularly suffered from two major defects: poor mechanical resistance to external aggression and low gloss. Indeed, the polymer matrices in which the carbon fibers were dispersed proved to be relatively soft and easily scratched. Consequently, producing decorations or reliefs on exterior elements obtained using such composite materials proved to be a technical solution that was not very durable. Furthermore, the matte appearance of the exterior elements obtained using composite materials of the polymer matrix type reinforced with carbon fibers made the use of such elements for the exterior of a high-end watch difficult to envisage.

[0004] To overcome these problems, alternative solutions have already been proposed. For the production of the decorative elements most exposed to external aggressions, such as bezels and control members such as crowns or pushers, metallic or ceramic materials have been used. Other composite materials of the metal matrix and fiber reinforcement type have also been used. More recently, it has also been proposed to produce decorative elements for timepieces or jewelry using composite materials commonly called "cermet" which consist of a ceramic reinforcement and a metal matrix.

[0005] Even if, from the point of view of the mechanical resistance of the exterior elements, progress has been achieved thanks to the use of composite materials with a metal matrix and fiber or ceramic reinforcement, the resulting exterior elements still do not completely satisfy the requirements in the field of watchmaking and jewelry with regard to the mechanical resistance of their decorations or reliefs. Indeed, the technique usually used to produce decorations or reliefs on these exterior elements consists of combining physical vapor deposition (PVD) and electroforming and only allows very thin layers to be obtained. Consequently, although such thin layers are metallic and therefore have a more brilliant appearance, their thickness is so low that the mechanical resistance of these thin layers to friction and wear is poor.

[0006] Yet another technique for decorating, for example, a wristwatch bezel has been proposed in European patent application EP2315673A1. Briefly summarized, this technique consists of providing a bezel, for example made of ceramic, on the surface of which recesses are provided to receive, for example, time markers. An annular strand of amorphous metal is then deposited on the surface of the bezel. Then this strand of amorphous metal is heated to a temperature above its glass transition temperature Tg and pressed so that the amorphous metal penetrates into the recesses. Subsequently, the amorphous metal is cooled and the excess material is removed.

[0007] This technique advantageously makes it possible to obtain decorative elements for timepieces with solid decorations that are more resistant to mechanical stresses and wear. This technique, which requires the preparation of a roll of amorphous metal, heating, pressing and then cooling the latter, and finally the elimination of excess amorphous metal on the surface of the decorative element, is however long to implement and therefore expensive.

Summary of the invention

[0008] The present invention aims to overcome the drawbacks mentioned above and others by providing decorative elements for timepieces or jewelry pieces made from a material that fully meets the requirements in force in the field of watchmaking and jewelry, particularly in terms of mechanical strength and aesthetics. The present invention also provides a method for manufacturing such decorative elements.

[0009] To this end, the present invention relates to a decorative element for a timepiece or piece of jewelry made using a composite material with a polymer matrix reinforced by fibers, this decorative element comprising on at least one of its faces at least one cavity in which is housed an insert made of metallic glass.

[0010] According to a special embodiment of the invention, the polymer material used to form the matrix is thermoplastic or thermosetting.

[0011] According to another special embodiment of the invention, the polymer material is chosen from the group formed by polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE) and polyamide-imide (PAI).

[0012] According to yet another special embodiment of the invention, the fibers which reinforce the polymer matrix are chosen from the group formed by glass fibers, carbon fibers and aramid fibers.

[0013] According to yet another special embodiment of the invention, the metallic glass used to produce the insert is of the solid type (Bulk Metallic Glass or BMG).

[0014] According to yet another special embodiment of the invention, the metallic glass used to produce the insert contains zirconium or platinum.

[0015] According to yet another special embodiment of the invention, the metallic glass used to produce the insert results, apart from unavoidable impurities, from an alloy of zirconium, copper, titanium, nickel, aluminium and niobium.

[0016] According to yet another special embodiment of the invention, the metallic glass used to produce the insert comprises, in mass percentage, zirconium, copper, titanium, nickel, aluminum and niobium in the following quantities: – 60 ≤ Zr ≤ 75 – 10 ≤ Cu ≤ 20 – 0 ≤ Ti ≤ 6 – 7 ≤ Ni ≤ 15 – 0 ≤ Al ≤ 8 – 0 ≤ Nb ≤ 6

[0017] According to yet another embodiment of the invention, the metallic glass used to produce the insert is the alloy Vit106a of composition Zr70Cu13Ni9.9AI3.65Nb3.4 in mass percentage, or Vit105 of composition Zr65.7Cu15.6Ni11.7Al3.7Ti3.3 in mass percentage.

[0018] According to yet another special embodiment of the invention, the metallic glass used to produce the insert results, apart from unavoidable impurities, from an alloy of platinum, copper, nickel and phosphorus.

[0019] According to yet another special embodiment of the invention, the metallic glass used to produce the insert comprises, in mass percentage, platinum, copper, nickel and phosphorus in the following quantities: – 80 ≤ Pt ≤ 90 – 5 ≤ Cu ≤ 10 – 1 ≤ Ni ≤ 3 – 4 ≤ P ≤ 7

[0020] According to yet another embodiment of the invention, the metallic glass used to produce the insert is, in mass percentage, given by the composition Pt85Cu7Ni2.3P5.7.

[0021] According to yet another special embodiment of the invention, the metallic glass used to produce the insert has a glass transition temperature less than or equal to 350°C.

[0022] According to yet another special embodiment of the invention, the decorative element for a timepiece or piece of jewelry is a back, a case middle, a bezel, a bracelet link or a clasp.

[0023] The present invention also relates to a method for manufacturing a covering element for a timepiece or piece of jewelry comprising the steps of: – producing the covering element using a composite material with a polymer matrix reinforced by fibers; – machining at least one cavity in at least one of the faces of the covering element; – bringing a metallic glass to its melting temperature; – filling the at least one cavity with metallic glass by injection to form an insert; – carrying out, if necessary, finishing operations.

[0024] According to a special embodiment of the invention, the cavity is produced by milling.

[0025] According to yet another special embodiment of the invention, the finishing operations consist of removing excess material, polishing and/or deburring the insert.

[0026] Thanks to these characteristics, the present invention provides decorative elements for timepieces or jewelry pieces which are externally coated with one or more inserts such as hour markers, numerals, a logo or any other inscription of a technical or fancy nature. These inserts, produced by injection of a metallic glass, are in the form of solid blocks and therefore have excellent mechanical resistance to friction and wear. They also have an appearance which is in accordance with the aesthetic requirements in force in the fields of watchmaking and jewelry. Indeed, given that these inserts are thick, it is possible to subject them to all types of finishing operations to give them a brilliant metallic luster. Similarly, these inserts are produced in a single step of injecting a metallic glass, which allows for significant savings in time and money, and guarantees excellent manufacturing precision of these inserts. For all practical purposes, it will be noted that, for the purposes of this description, the term "metallic glass" means the range of metal alloys which have the particularity of being able to be solidified in an at least partially amorphous state, that is to say without a regular arrangement of atoms. Metallic glasses are therefore clearly distinguished from traditional metals which crystallize according to ordered structures such as, in particular, simple cubic, centered or face-centered or even hexagonal as well as variants of these structures. These metallic glasses are generally derived from ternary, quaternary or higher alloys whose ability to solidify in the amorphous state results from the combination of elements which have between them a dimensional incompatibility such that, from a given cooling rate, the solidification kinetics is controlled to allow a disordered solid crystallographic structure to be obtained. The behavior of this family of materials allows for implementation similar to that of polymer materials such as injection molding or hot forming. This family of materials has the particular advantage of presenting improved corrosion resistance, high hardness and elastic behavior which limits internal mechanical losses.

Brief description of the figures

[0027] Other characteristics and advantages of the present invention will emerge more clearly from the following detailed description of an embodiment of a decorative element for a timepiece or piece of jewelry in accordance with the invention, this example being given purely for illustrative and non-limiting purposes only in conjunction with the appended drawing in which: – Figure 1 is a top view of a watch bezel in accordance with the invention; – Figure 2 is a sectional view along line B-B of Figure 1.

Detailed description of the invention

[0028] The present invention proceeds from the general inventive idea which consists of providing exterior elements for a timepiece or piece of jewelry which have mechanical and aesthetic characteristics meeting the requirements required in the field of watchmaking. To this end, the present invention teaches to produce such exterior elements by means of a composite material with a polymer matrix reinforced by fibers, then to provide on the surface of such exterior elements at least one cavity in which will be housed an insert of a decorative or functional nature made of metallic glass. Thanks to the use of a composite material with a polymer matrix reinforced by fibers, the exterior element according to the invention has mechanical resistance to wear and aesthetic characteristics which make it perfectly suitable for watchmaking applications. Furthermore, the inserts, produced by injection of a metallic glass, form solid studs having a sufficient thickness to enable them to resist external mechanical aggressions. Furthermore, since these inserts are thick, they easily withstand finishing operations that will give them maximum shine and brilliance. Finally, the production of the inserts is done in a single injection step, which saves considerable time and guarantees excellent manufacturing precision of these inserts.

[0029] Designated as a whole by the general reference numeral 1, the bezel shown in FIG. 1 is an example of a decorative element for a timepiece according to the invention. Other decorative elements such as the back, caseband, links and bracelet clasp are also conceivable.

[0030] According to the invention, the bezel 1 is made using a composite material with a polymer matrix reinforced by fibers. 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 from the group formed by polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE) and polyamide-imide (PAI). This matrix is reinforced by fibers which are preferably chosen from the group formed by glass fibers, carbon fibers and aramid fibers. A plurality of these bezels 1 can be individualized in a plate of composite material of required thickness.

[0031] By way of example, a trim element such as a bezel 1 according to the invention can be produced by a filament winding process of the SPIDE TP type which was developed by the French mechanical expertise center CETIM. Very briefly explained, this filament winding process consists of winding fibers previously impregnated with a polymer material onto a mold, for example such as a tube of cylindrical section, in order to obtain a profile. At the same time as these fibers pre-impregnated with polymer are wound around the mold according to a given number of layers and at an angle relative to the longitudinal axis of symmetry of the mold which is chosen in particular according to the subsequent use of the resulting parts which will be obtained by cutting the profile, they are heated to a temperature high enough to cause the melting of the polymer with which they are impregnated and pressed against the mold. Finally, the resulting parts are conventionally machined using lathes and milling machines to bring them to their final dimensions.

[0032] In the case of the present invention, the glasses 1 are cut from a tubular profile whose internal diameter is typically of the order of 30 mm and whose external diameter is 45 mm. The tubular profile from which the glasses 1 according to the invention are cut is obtained by winding carbon fibers whose diameter is typically of the order of 5 to 25 µm and which are impregnated with polyetheretherketone (PEEK) whose melting temperature is 341°C. To obtain the desired tubular profiles from which the glasses 1 according to the invention will subsequently be cut, the carbon fibers are preferably wound at an angle of 90° perpendicular to the longitudinal axis of symmetry of the tubular profile.

[0033] The tubular profiles used to produce in particular the glasses 1 are typically composed of approximately 35% PEEK polymer and 65% carbon fibers to within plus or minus 10%. It is therefore understood that the cladding elements obtained from these tubular profiles contain a large proportion of carbon fibers, which significantly improves their thermal conductivity and allows them to quickly diffuse the heat provided during the injection of the metallic glass. Consequently, although the temperature at which the metallic glass is injected is higher than the melting temperature of the polymer matrix, the glasses 1 will not decompose, nor will they deform. It will also be noted that the reduced thickness of the injected inserts combined with the good thermal conductivity of the mold and the composite material considerably reduce the time of exposure of the polymer to a temperature higher than its melting point. Consequently, it is not necessary to take any particular additional measures to limit the degradation of the polymer during brief contact with the metallic glass. The visible parts of the composite that have potentially been in contact with the metallic glass will also be removed during surface finishing operations after leaving the mold.

[0034] The bezel 1 comprises on an upper face 2 one or more cavities 4 typically produced by milling. According to the invention, these cavities 4 will be filled using a material of the metallic glass type to form inserts 6. Non-limitingly, as visible in FIG. 1, these inserts 6 materialize numerals and indexes, for example of triangular or circular shape. Preferably, these cavities 4 have an undercut angle α of between 5 and 10° to ensure better mechanical strength of the inserts 6.

[0035] The metallic glass used to produce the inserts 6 is of the solid type (Bulk Metallic Glass or BMG). Preferably, this metallic glass contains zirconium. For example, an alloy containing, apart from unavoidable impurities, zirconium, copper, titanium, nickel, aluminum and niobium can be used. According to a non-limiting example, the metallic glass used to produce the insert comprises these materials in mass percentage according to the following quantities: – 60 ≤ Zr ≤ 75 – 10 ≤ Cu ≤ 20 – 0 ≤ Ti ≤ 6 – 7 ≤ Ni ≤ 15 – 0 ≤ Al ≤ 8 – 0 ≤ Nb ≤ 6

[0036] An example of a metallic glass containing zirconium which is well suited to the needs of the invention is the alloy Vit106a of composition Zr70Cu13Ni9.9Al3.65Nb3.4 in mass percentage, or Vit105 of composition Zr65.7Cu15.6Ni11.7Al3.7Ti3.3 in mass percentage.

[0037] The metallic glass used to make the inserts 6 can also be platinum-based. For example, it is possible to use an alloy containing, apart from unavoidable impurities, platinum, copper, nickel, aluminium and phosphorus. According to a non-limiting example, the metallic glass used to make the insert comprises these materials in mass percentage according to the following quantities: – 80 ≤ Pt ≤ 90 – 5 ≤ Cu ≤ 10 – 1 ≤ Ni ≤ 3 – 4 ≤ P ≤ 7

[0038] According to yet another embodiment of the invention, the metallic glass used to produce the insert is, in mass percentage, given by the composition Pt85Cu7Ni2.3P5.7.

[0039] According to yet another special embodiment of the invention, the metallic glass used to produce the insert has a glass transition temperature less than or equal to 350°C.

[0040] According to the invention, to form the inserts 6, the cavities 4 are filled with metallic glass by injection. To this end, a metallic glass ingot is provided, which is placed in a melting chamber and heated to a temperature above its melting temperature. Once the metallic glass ingot has melted, the metallic glass is injected into a mold in which the bezel 1 is placed and which is arranged so that the metallic glass fills the cavities 4 of this bezel 1. The injection of the metallic glass into the mold in which the bezel 1 is placed can be ensured by mechanical pressure provided by a piston or by gas pressure. The cavities 4 are preferably filled with a slight excess thickness of metallic glass so as to ensure an optimal connection between the bezel 1 and the inserts 6.

[0041] After cooling of the metallic glass, the bezel 1 is removed from its mold and can be subjected to finishing operations such as the removal of excess material, grinding and/or mechanical or chemical polishing. Any excess thickness and burrs are also removed by deburring.

[0042] It goes without saying that the present invention is not limited to the embodiment which has just been described and that various simple modifications and variants can be envisaged by those 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 bring the metallic glass to its melting temperature so that it can be injected by means of an injection machine.

Nomenclature

[0043] 1 Bezel 2 Upper face 4 Cavities 6 Inserts

Claims (18)

1. Component for a timepiece or piece of jewelry made using a composite material with a polymer matrix reinforced by fibers, this component comprising on at least one of its faces (2) at least one cavity (4) in which is housed an insert (6) made of metallic glass. 2. Component according to claim 1, characterized in that the polymer material used to form the matrix is thermoplastic or thermosetting. 3. Component according to claim 2, characterized in that the polymer material is chosen from the group formed by polyetheretherketone PEEK, polytetrafluoroethylene PTFE and polyamide-imide PAI. 4. Component according to one of claims 2 and 3, characterized in that the fibers which reinforce the polymer matrix are chosen from the group formed by glass fibers, carbon fibers and aramid fibers. 5. Component according to claims 3 and 4, characterized in that the composite material used is composed of 35% PEEK polymer and 65% carbon fibers to within plus or minus 10%. 6. Component according to one of claims 1 to 5, characterized in that the metallic glass used to produce the insert is of the solid type known by its Anglo-Saxon name Bulk Metallic Glass abbreviated BMG. 7. Component according to claim 6, characterized in that the metallic glass used to produce the insert contains zirconium or platinum. 8. Component according to claim 7, characterized in that the metallic glass used to produce the insert results, apart from unavoidable impurities, from an alloy of zirconium, copper, nickel, aluminum and/or niobium and/or titanium. 9. Component according to claim 8, characterized in that the metallic glass used to produce the insert comprises, in mass percentage, zirconium, copper, titanium, nickel, aluminum and niobium in the following quantities: – 60 ≤ Zr ≤ 75 – 10 ≤ Cu ≤ 20 – 0 ≤ Ti ≤ 6 – 7 ≤ Ni ≤ 15 – 0 ≤ Al ≤ 8 – 0 ≤ Nb ≤ 6 10. Component according to claim 9, characterized in that the metallic glass used to produce the insert is an alloy of composition Zr70Cu13Ni9.9AI3.65 Nb3.4 in mass percentage, or an alloy of composition Zr65.7Cu15.6Ni11.7AI3.7Ti3.3 in mass percentage. 11. Component according to claim 7, characterized in that the metallic glass used to produce the insert comprises, in mass percentage, platinum, copper, nickel and phosphorus in the following quantities: – 80 ≤ Pt ≤ 90 – 5 ≤ Cu ≤ 10 – 1 ≤ Ni ≤ 3 – 4 ≤ P ≤ 7 12. Component according to claim 11, characterized in that the metallic glass used to produce the insert is, in mass percentage, given by the composition Pt85Cu7Ni2.3P5.7. 13. Component according to one of claims 6 to 12, characterized in that the metallic glass used to produce the insert has a glass transition temperature less than or equal to 350°C. 14. Component according to one of claims 1 to 13, characterized in that the component is a decorative element for a timepiece or piece of jewelry such as a back, a case middle, a bezel (1), a bracelet link or a clasp. 15. A method for manufacturing a component for a timepiece or jewelry piece, comprising the steps of: – producing the component using a fiber-reinforced polymer matrix composite material; – machining at least one cavity (4) in at least one of the faces (2) of the component; – heating a metallic glass to its melting temperature; – filling the at least one cavity (4) with metallic glass by injection to form an insert (6); – carrying out, if necessary, finishing operations. 16. Manufacturing method according to claim 15, characterized in that the cavity is produced by milling. 17. Manufacturing method according to claim 16, characterized in that the finishing operations consist of removal of excess material, mechanical and/or chemical polishing and/or deburring of the insert (6). 18. Manufacturing method according to one of claims 15 to 17, characterized in that the cavities (4) have an undercut angle (α) of between 5 and 10°.