CH713998B1 - Watch component made of composite material and method of manufacturing such a component. - Google Patents

Abstract

The invention relates to a watch component (1), in particular a watch strap component, a covering component, for example a caseband, a back, a bezel, plate or a bridge, made of composite material, the composite material comprising an open cell aluminum alloy foam (2) (21) and a plastic material (3), the plastic material filling the cells with the foam. The invention also relates to a method of manufacturing such a component.

Description

The invention relates to a watch component. The invention also relates to a horological mechanism comprising such a component. The invention also relates to a timepiece comprising such a component or such a timepiece. The invention finally relates to a method of making or manufacturing such a component, such a mechanism or such a timepiece.

In the watchmaking field, different materials can be used to make different components of a timepiece, depending on the specifications of this component and the properties of the materials.

[0003] The production of certain watch components in specific materials must be excluded in view of functional constraints.

[0004] For the production of a wristwatch, there is a particular need for lightweight components because the watch is worn by the user. Even more, there is a particular need for hypoallergenic components since components of the watch are in direct contact with the skin of the user.

[0005] Furthermore, the components must also be resistant to environmental attacks (ultraviolet rays, sea water, soap, detergents, perspiration, etc.).

The aim of the invention is to provide a component making it possible to remedy the drawbacks mentioned above and to improve the components known from the prior art. In particular, the invention provides a component which is light, hypoallergenic and resistant to environmental attacks.

A component according to the invention is defined by claim 1.

[0008] Different embodiments of the component are defined by dependent claims 2 to 8 and 13.

A method according to the invention is defined by claim 9.

Different embodiments of the method are defined by dependent claims 10 to 12.

A mechanism according to the invention is defined by claim 14.

A timepiece according to the invention is defined by claim 15.

The accompanying figures show, by way of example, an embodiment of a method of manufacturing or producing a timepiece according to the invention. FIG. 1 is a schematic view of a first embodiment of a timepiece according to the invention. FIGS. 2 to 6 are partial sections illustrating different steps of an embodiment of a method for manufacturing a component according to the invention.

One embodiment of a timepiece 30 is described below with reference to FIG. 1. The timepiece is for example a watch, in particular a wristwatch. The timepiece comprises a bracelet 25 and a case 20, the case 20 containing a watch movement 10. The bracelet, the case and the movement are grouped together under the generic term “mechanism”.

The movement 10 comprises at least one component 1a, in particular a blank such as a plate or a bridge, made of a particular material described below and / or the case comprises at least one component 1b made of this particular material and / or the bracelet comprises at least one component 1c made of this particular material.

[0016] One embodiment of the watch component 1, 1a, 1b, 1c is therefore in particular a watch strap component, a covering component, a caseband, a back, a bezel, a plate or a bridge.

The component is made of composite material.

The composite material comprises, as shown in Figure 6: an open-cell aluminum alloy foam 2 21, and a plastic material 3, the plastic material filling the cells of the foam.

Preferably, the composite material comprises only the foam 2 of open-cell aluminum alloy 21 and the plastic material 3.

The foam is of the open cell or open cell type. Thus, from any open cell or cell of the foam, it is possible to find a path, out of the solid material, which makes it possible to reach another cell or open cell of the foam.

The fact that the foam is open-celled does not exclude that some cells can be closed. This can occur in particular depending on the production process of the foam. By "open cell foam", we therefore mean a foam in which a significant portion of cells, in particular a majority of cells, is of the "open cell" type.

The aluminum alloy can be of any kind provided that it is possible to produce a foam from it.

[0023] For example, the aluminum alloy comprises: between 0.7% and 1.3% by mass of silicon; and or between 0.4% and 1% by mass of manganese; and or between 0.6% and 1.2% by mass of magnesium.

The aluminum alloy further comprises at least 80%, or even at least 90%, by weight of aluminum.

For example, the aluminum alloy can be aluminum alloy 6082 (EN AW-6082) (also designated: AlSi1MgMn or 3.2315 or H30 or A96082 according to other standards).

The 6082 aluminum alloy comprises (by mass): Aluminum: 95.2% to 98.3%; Chromium: at most 0.25%; Copper: not more than 0.1%; Iron: at most 0.5%; Magnesium: 0.6 to 1.2%; Manganese: 0.4% to 1.0%; Silicon: 0.7 to 1.3%; Titanium: at most 0.1%; Zinc: at most 0.2%; the remainder: at most 0.15%.

The foam can be produced by any means.

Preferably, the size of the cells is less than 2 mm. Advantageously, at least 80% of the cells have a size of between 0.05 mm and 2 mm.

For a given volume of material, the aluminum alloy occupies between 20%, or even 10%, and 40%, or even 50%, of the volume, typically around 30%. The complement is formed by the alveoli.

The plastic material completely or almost completely fills the cells of the foam. For example, the plastic material fills at least 80% of the volume of the cells of the foam. The rest can be gas inclusions.

The plastic material is preferably based on a polymer or is a polymer.

The polymer can be a thermoplastic, in particular a transparent or translucent thermoplastic.

The polymer is preferably of acrylic type, in particular polymethyl methacrylate (PMMA). Polymethyl methacrylate has the advantage of easy infiltration into the aluminum alloy foam.

For example, the plastic material can be produced by mixing the product ACRIFIX® 2R 1900 and an ACRIFIX® CA 0020 product, the two products being marketed by the company EVONIK.

The plastic material can include: pigments; and or one or more dyes.

The pigments can be luminescent or phosphorescent pigments.

As a consequence of what has been seen above, the composite material comprises more than 50% by volume of plastic material and / or the composite material comprises less than 90% by volume of plastic material. Preferably, the composite material preferably comprises about 70% by volume of plastic material.

An embodiment of a method of manufacturing a watch component 1 (corresponding to references 1a, 1b, 1c used previously) is described below with reference to Figures 2 to 6. Figures 2 to 6 being section type views (therefore in two dimensions), not all the links or communications between the cells of the foam are visible.

In a first phase, a foam 2 of aluminum alloy with open cells 21 is produced.

In a second phase, the cells 21 are filled with the plastic material.

In a first step of the first phase, a mold is provided 5. The mold is suitable for the foundry. It is resistant, for example, to the melting temperature of the aluminum alloy. Preferably, the mold 5 has a negative shape of the blank of the watch component that is to be obtained.

In a second step, there are grains of a salt in the mold. The mold is advantageously filled with grains 4 of salt, as shown in FIG. 2. For example, the salt is sodium chloride. This salt is appreciated because it is not harmful. Any other salt can be used. However, the salt must be adapted so as not to melt at the melting temperature of the aluminum alloy. The grains 4 of salt can be more or less packed, in particular by vibration. The geometric characteristics of the grains (shapes and sizes) as well as the settlement of the grains ultimately determine, for a given volume of composite material, the volume percentage of aluminum alloy in the composite material.

In a third step, the molten aluminum alloy is poured into the mold. The liquid aluminum alloy fills, in the mold, the interstices formed between the grains 4. A vacuum can be made in the mold to promote the filling of the interstices. Likewise, it is possible to vibrate the mold and / or manipulate the mold, in particular invert the mold, to promote the filling of the interstices.

In a fourth step, the aluminum alloy is allowed to solidify as shown in Figure 3. A material is obtained made of aluminum alloy with salt inclusions.

In a fifth step, the salt inclusions are dissolved. To do this, the material obtained in the previous step is immersed in a solvent for this salt. In the case of sodium chloride, water can be used. To promote and accelerate the dissolution of the salt, the bath can be agitated and / or heated.

Thus, after dissolution of the salt, a foam 2 of aluminum alloy with open cells 21 is obtained as shown in FIG. 4. The cells are in fact formed by the volumes previously occupied by the grains of salts.

The aluminum foam can of course be alternatively obtained by any other process.

In a first step of the second phase, a mold 6 is provided. The mold is suitable for molding plastics. It may be different from the foundry mold 5. Preferably, the mold 6 has a negative shape of the blank of the watch component that is to be obtained.

In a second step, the aluminum foam is placed in the mold.

In a third step, the plastic material 3 is poured in the liquid phase in the mold. The liquid plastic material fills the open cells in the mold, as shown in FIG. 5. A vacuum can be made in the mold to promote filling of the cells. Likewise, it is possible to vibrate the mold and / or manipulate the mold, in particular invert the mold, to promote the filling of the cells. The liquid plastic material can be prepared by mixing two products, one of these products constituting a hardener.

In a fourth step, the plastic material 3 is allowed to solidify or harden, in particular to polymerize. Depending on the nature of the plastic material, this solidification can be activated or accelerated by heat.

In a fifth step, the component is demolded and a component or a component blank of composite material is obtained as shown in FIG. 6.

In a sixth step, it is also optionally possible to shape the component or to apply one or more surface treatments to the component. In particular, the component can be machined and / or the component polished and / or the component sandblasted and / or the component shotblasted.

Throughout this document, by "aluminum alloy" is meant any alloy in which aluminum is predominant or predominant by mass. Preferably, the alloy contains at least 80%, or even at least 90%, of aluminum by weight.

The watch component obtained has many advantages and interests: it is extremely light: the density of the composite material can be of the order of 1600 kg.m <-3>, in particular between 1500 kg.m <-3> and 1800 kg.m <-3>; it has an original appearance: in fact, the surface of the component is made up of zones made of plastic material and zones made of aluminum alloy; its appearance can be radically modified by the addition of dye and / or pigments in the plastic material; it has a smooth surface appearance unlike an aluminum alloy foam alone which has pores on the surface; it is hypoallergenic, the aluminum alloy foam alone although hypoallergenic as such exhibiting the defect of having pores (cells opening to the surface of the component) which become clogged; it is resistant to common environmental attacks (ultraviolet rays, sea water, soap, detergents, perspiration, etc.); it has good machinability, in particular compared to an aluminum alloy foam not impregnated with plastic material; it is much more mechanically resistant than if it were made of plastic material only.

Claims (15)

1. Watch component (1; 1a; 1b; 1c), in particular watch strap component, trim component, for example middle, back or bezel, plate or bridge, made of composite material, the composite material comprising a foam ( 2) of open cell aluminum alloy (21) and plastic material (3), the plastic material filling the cells with the foam. 2. Watch component according to the preceding claim, characterized in that the aluminum alloy is an aluminum alloy comprising: - between 0.7% and 1.3% by mass of silicon; and or - between 0.4% and 1% by mass of manganese; and or - between 0.6% and 1.2% by mass of magnesium; in particular in that the aluminum alloy is aluminum alloy 6082. 3. Watch component according to one of the preceding claims, characterized in that the plastic material is based on a polymer or is a polymer. 4. Watch component according to the preceding claim, characterized in that the polymer is a thermoplastic, in particular a transparent or translucent thermoplastic. 5. Watch component according to claim 3 or 4, characterized in that the polymer is of acrylic type, in particular is polymethyl methacrylate PMMA. 6. Watch component according to one of the preceding claims, characterized in that the plastic material comprises: - pigments; and or - one or more dyes. 7. Watch component according to one of the preceding claims, characterized in that the composite material comprises more than 60% by volume of plastic material and / or the composite material comprises less than 80% by volume of plastic material, the composite material comprising preferably about 70% by volume of plastic material. 8. Watch component according to one of the preceding claims, characterized in that the composite material has a density of between 1500 kg.m <-3> and 1800 kg.m <-3>, in particular of the order of 1600 kg.m <-3>. 9. A method of manufacturing a watch component (1; 1a; 1b; 1c) according to one of claims 1 to 8, comprising the following steps: - providing the foam (2) of open-cell aluminum alloy (21); - fill the cells with the plastic material (3) in the liquid phase; - hardening, in particular polymerizing, the plastic material. 10. The manufacturing method according to the preceding claim, comprising an additional step of shaping or treatment of the watch component, this additional step being a machining step and / or a surface treatment step of polishing type and / or of sandblasting type and / or shotblasting type. 11. The manufacturing method according to claim 9 or 10, wherein the step of providing the foam comprises the following steps: - provide a mold (5); - filling the mold with grains (4) of a salt, in particular grains of sodium chloride; - pour the molten aluminum alloy into the mold; - after solidification of the alloy, dissolve the grains of salt. 12. The manufacturing method according to one of claims 9 to 11, wherein the step of filling the cells with the plastic material in the liquid phase comprises the following steps: - place the aluminum alloy foam in a mold (6); - optionally, creating an at least partial vacuum in the mold; - pouring the plastic material in liquid phase into the mold. 13. Timepiece component (1) obtained according to the method according to one of claims 9 to 12. 14. Watch mechanism (10, 20, 25), in particular watch movement (10), comprising a component (1, 1a, 1b, 1c) according to one of claims 1 to 8 and 13. 15. Timepiece (30), in particular wristwatch, comprising a mechanism according to the preceding claim or a component according to one of claims 1 to 8 and 13.