Patent Application
20200089166
The present invention concerns a method for assembling at least two elements to form an external component, particularly made of ceramic, for a portable device, together with an external component obtained by this method. Each element is formed from a material with distinct physical and/or aesthetic characteristics.
The invention will find application in the assembly manufacturing of an external component intended, preferably but not exclusively, for the field of horology. Preferably, such a component may be, for example, a watch bezel intended to be placed on a watch case, a bracelet link, a dial, a watch case, or a clasp element.
The invention will also find application in the manufacturing of external components used in the fields, non-exhaustively, of mobile and cellular telephones, portable computer terminals, for example to form mobile phone or tablet cases, or in the field of jewelry or tableware.
The invention is particularly intended for the assembly of elements made of hard materials, i.e. shock and scratch resistant materials. These hard materials may, in particular, be technical ceramics. Further, each element can be made of zirconium dioxide or ‘zirconia’, aluminium dioxide or ‘alumina’, or of another composite material integrating a ceramic support and a metal matrix or ‘cermet’. Each element of the external component according to the invention can also be made of synthetic sapphire or ruby.
For aesthetic reasons, it is sometimes desirable to make external components, especially external timepiece components, which have a different appearance depending on the area of the component. By way of example, it is well known to make watch bezels in two-colour ceramic, having two different coloured areas.
A known technique consists in subjecting the component made of a first material to successive surface treatments, for example by applying paint or metal layers of different appearance using chemical or physical vapour deposition (CVD or PVD) technologies, by partially masking the area or areas of the component whose appearance is not desired to be changed. The main drawback of these treatments lies in the fact that, when a treated surface of the component comes into contact with a foreign body higher in hardness than the deposited layer, it is likely to be scratched and expose the first material, which is unacceptable for products whose aesthetic appearance is vital to the consumer.
When the external component is made of a technical ceramic, it is known to make two-colour components directly by injection moulding, particularly by bi-injection moulding two different coloured ceramic materials, and sintering. However, this manufacturing technique is complex to implement with a view to obtaining a clear demarcation between the two materials which is difficult to obtain. Indeed, it is difficult to adapt the sintering parameters so that, on the one hand, the colours are in their optimum configuration, and on the other hand, to avoid the phenomena of diffusion of one colour into the other which is detrimental to the obtention of a clear demarcation between the different coloured parts of the component.
Purely aesthetically, it is possible to colour a component formed of a single element by impregnation, making it possible to obtain different colours in different areas of said component. However, the colours are limited by the colouring of the material forming the component and by impregnation techniques. Moreover, once again, the sintering step involves adaptation of parameters and does not produce an optimal result.
Another known approach for making two-colour components consists in assembling elements of different colours to each other by gluing abutting portions of the elements. However, the components obtained by this technique are inevitably more fragile than one-piece components. Further, depending on the dimensions of the elements to be assembled, the gluing operations can be complex and tedious.
It is an object of the invention to overcome the drawbacks of the aforementioned prior art by providing an external component, particularly an external timepiece component, having a different appearance depending on the area of the component, which is simple and economical to make.
It is also an object of the invention to provide an external component, particularly a two-colour component, wherein the demarcation between the different coloured parts of the component is clear.
To this end, the invention concerns a method for assembling at least a first element and a second element to form, once assembled, an external component for a portable device, including the steps of:
a) making the first element;
b) making the second element;
c) arranging at least a first groove in the first element and at least a second groove in the second element;
d) placing and holding the first and second element end-to-end by means of at least a third connecting element which is inserted and locked in the first and second grooves.
The invention thus proceeds from the general inventive idea which consists in assembling at least two, previously individually manufactured elements, of different natures and/or colours, in order to obtain an optimal configuration for each element in both mechanical and aesthetic terms.
According to an advantageous embodiment, the step of inserting and locking the third element in the first and second grooves consists in filling the first and second grooves by inlaying an at least partially amorphous metallic material.
Indeed, the viscosity of amorphous materials drops sharply at low temperatures, which means they can be shaped at low-stress levels. More particularly an amorphous metal is shaped between its glass transition temperature and its crystallization temperature. For example, for a platinum-based amorphous metal, the inlaying process is performed at around 300° C. (degrees Celsius) for a viscosity of up to 103 Pa·s (pascal-seconds) and at a stress of 1 MPa (Megapascal), instead of a viscosity of 1012 Pa·s-1 at the glass transition temperature. This viscosity makes it possible to obtain improved adhesion characteristics. The low viscosity of amorphous metals at this temperature range firstly allows them to perfectly fill the space in which they are constrained and at low pressure levels. Thus, in the case of filling a groove, this ability to perfectly match the contours makes it possible to exactly fill the recesses.
Low-temperature shaping henceforth allows the use of materials that have not previously been used due to their poor thermal resistance (such as a fall in mechanical properties, oxidation or a low melting point) or their poor thermal shock resistance.
The use of an inlay made of at least partially amorphous metallic material allows for low-stress and low-temperature shaping, for example using a hot press.
The metal inlay can be made on a visible or non-visible face of the external component, on junction portions extending at least on either side of the contact surfaces of said elements placed end-to-end. Such a metal inlay is made inside at least one groove, particularly in the form of at least one recess made along each portion joining the elements to each other.
According to an alternative embodiment, the first and second elements are made of an electrically conductive material or the walls of the grooves are coated with an electrically conductive layer, characterized in that the step of inserting and locking the third element in the first and second grooves consists in filling the first and second grooves with a metal by an electroforming process.
According to other advantageous variants of the invention:
The invention also concerns an external component obtained by implementing such an assembly method.
The invention also concerns an external component, including at least:
According to an advantageous first embodiment of the external component of the invention, said third element is an at least partially amorphous metallic material inlaid in said first and second grooves.
According to a second embodiment of the external component of the invention, said third element is a metallic material electroformed in said first and second grooves.
Advantageously, the external component forms a watch bezel, a bracelet link, a dial, a watch case or clasp element. This component may thus have an annular shape in which each element consists of an annular arc portion, particularly to form a watch bezel.
The invention will be described in more detail hereinafter with reference to the annexed drawings, given by way of non-limiting examples, representing different steps for assembling several elements in order to obtain an external component, in which:
Said Figures show an example of certain implementation steps of the assembly method of the invention for obtaining an external component, on the one hand, of flattened annular shape, from two semi-annular elements capable of forming a ring intended to be placed on a portable timepiece device. On the other hand, the Figures show an example of a mobile telephone case, made from three elements.
More broadly, the invention makes it possible to obtain an external component from more elements, assembled to each other by a metal inlay. The component obtained can have any shape—circular, annular, oval or polygonal—and the assembled elements have complementary shapes, the arrangement of which provides said overall shape of the external component. Such a component can have a polygonal, parallelepiped, tapered or more complex shape, or have convex or concave side edges.
The present invention concerns a method for making an external component 1 by assembling several elements, at least a first element 2 and a second element 3. Such an assembly to obtain such a component 1 can be achieved with more elements, such as a third element 4, as seen in the example represented in
As mentioned above, the invention proposes to obtain an assembly from elements 2, 3, 4 while maintaining the optimal aesthetic and/or physical properties of each element. To achieve this, in a first phase, first element 2 is made. Second element 3 is also made. Another element 4 could also be made, as well as any other additional elements.
Advantageously, if first element 2 and second element 3 have an identical shape, they can be made successively in the same mould, with different materials and/or treatments.
According to another embodiment, several elements 2, 3, 4 can be made at the same time in a single piece inside the same mould, with different materials and/or treatments. The part created is then separated, particularly via a cutting operation, into as many elements 2, 3, 4, shaped and subsequently assembled to form said component 1.
The first and second elements 2, 3 can be made from similar or identical materials, but preferably the material of first element 2 is different from the material of second element 3. As regards other elements 4, the material can be different from the other two elements 2, 3, or only different from the material of the element 2, 3 intended to be assembled thereto (i.e. the other element 4 can be made of identical material to an element 2, 3 which is not adjoined thereto).
The difference in material includes both structure and aesthetics. Indeed, the same base material can have a different appearance, while maintaining virtually identical characteristics. Hence, the appearance of the material of first element 2 can be different from that of the material of second element 3, or from the other elements 4.
Preferably, said first material and said second material are polycrystalline or single crystal ceramic materials, made from aluminium oxide, zirconium oxide, tungsten carbide, silicon nitride, silicon carbide, tungsten carbide or cermets.
The shape of elements 2, 3, 4 corresponds to one part of the overall shape of the component 1 to be made. In the example embodiment seen in
According to another embodiment, represented in
Other shapes can be envisaged, such as a polygonal component 1, wherein each of elements 2, 3, 4 then represents one or more of its sides. In short, the shapes of elements 2, 3, 4 are complementary to obtain the shape of external component 1 assembled as one piece.
To achieve this, the invention proposes to arrange at least a first groove 6 in first element 2 and at least a second groove 7 in second element 3. There are at least as many grooves 6, 7 made as there are elements 2, 3, 4. The same element 2, 3, 4 can include several grooves 6, 7, as in the example of
Grooves 6, 7 can be machined mechanically, using a tool provided for this purpose, by abrasion or laser cutting, or any other suitable technique.
Preferably, each groove 6, 7 is machined so that it has a trapezoidal cross section, the side walls of each groove being inclined and converging outwards from the inside, i.e. from the bottom of the groove. Advantageously, the width of each groove 6, 7 is larger than its depth.
Further, each groove 6, 7 can have a depth comprised between 0.05 mm and 4 mm. Further, to avoid weakening component 1, the depth of each groove 6, 7 cannot exceed 90% of the thickness of each element 2, 3, 4.
It will be noted that, depending on the machining operation performed, the depth and width of groove 6, 7 may vary over its length. In particular, as seen in the example of
Each groove 6, 7 can have inclined flanks or walls 8 converging from the inside in the direction of the exterior of the groove. In other words, side walls 8 have a negative angle, which will make it possible to retain the assembly material. In short, each groove 6, 7 has a tapered shape, open on one of the sides of elements 2, 3, 4.
To this end, grooves 6, 7 can be machined either on the upper face or on the lower face of said first element 2 and second element 3, and on any other element 4. In short, they can be made from above or below, so that they are or are not visible depending on how component 1 is used as an external part. The filler material can thus be used as a decorative element in the case where the grooves are made on a visible face of the component once it is mounted, for example, on a watch case. In the case of a bezel, it is, for example, possible to envisage the grooves having edges which delimit figurative and/or decorative elements, such as a numeral, a letter or any other motif.
Further, each groove 6, 7 can extend over the entire length of first element 2 and second element 3, and any other element 4. This is the case of the example embodiment of
In the example embodiment seen in
In any event, a first groove 6 of a first element 2 is in communication with second groove 7 of a second element 3 when the two elements 2, 3 are placed end-to-end. In short, grooves 6, 7 are made so that at least one of their respective ends coincides with an edge joining their elements 2, 3, 4 to provide continuity of grooves 6, 7 between elements 2, 3, 4.
During the assembly of the invention, first element 2 and second element 3 are placed end-to-end. They are thus positioned opposite each other, in a certain alignment, in order to obtain the desired shape configuration of component 1.
Elements 2, 3, 4 are placed end-to-end in this manner at one of their respective joining edges. Their respective edges are then joined together, placed in tight contact. Consequently, when elements 2, 3, 4 are made, there may be an adjustment step of machining the joining edges of said elements 2, 3, 4, to obtain perfect lines of contact between them, at least in junction areas 9.
Further, elements 2, 3, 4 may be temporarily locked or joined to each other in said configuration, particularly on a support provided for this purpose, by any appropriate means, especially mechanical means, by temporary bonding, etc.
Advantageously, the assembly according to the invention entails maintaining by means of at least a third connecting element 10, which is inserted and locked in first and second grooves 6 and 7. In short, grooves 6, 7 are filled with a third element 10, which ensures the seamless assembly between elements 2, 3, 4, forming a continuous mechanical connection at least in junction areas 9.
As mentioned above, with grooves having a section with inclined side walls converging towards the opening of each groove 6, 7, inserting third element 10 thus forms a dovetail type mechanical connection which retains the third element in the groove.
Third element 10 has a material that is different from the other materials of elements 2, 3, 4, in both composition and appearance. In particular, in a first embodiment, third element 10 comprises an at least partially amorphous metallic material, namely an amorphous or partially amorphous metallic material having properties of malleability, which can be hot pressed to change shape without cracking or breaking and which can be inlaid inside grooves 6, 7. Such an inlay completely fills the internal volume of each groove 6, 7 particularly through deformation of third material 10 which is partially amorphous.
Typically, but non-exhaustively, such amorphous metal alloys which can be implemented in the method of the invention may be zirconium alloys, for example with chemical compositions in the following atomic percentages: Zr67.5Ti8.65Ni9.65Cu10.44Be3.76. Advantageously, said material forming third element 10 is chosen from the following group: precious or semi-precious metals. More precisely, said material forming third element 10 can be chosen from the group including alloys of gold, platinum or palladium. For example, non-exhaustively, the chemical compositions of such amorphous precious metal alloys that can be implemented may have the following atomic percentages: for ‘Pt852’ platinum Pt57.5Cu14.7Ni5.3P22.5, ‘Au18K’ gold, ‘Pd600’ palladium Pd43Cu27Ni10P20 or ‘Pd900’ palladium Pd77.5Cu6Si16.5.
Advantageously, said material forming third element 10 is of the crystalline type. Such a material may be metallic, such as, for example, aluminium or an alloy containing aluminium. Third element 10 made of aluminium can easily be inlaid using a hot process.
According to a second embodiment of the assembly method of the invention, the first and second elements 2, 3 are made of an electrically conductive material or the walls of grooves 6, 7 are coated with an electrically conductive material. Thus, the step of inserting and locking third element 10 in first and second grooves 6 and 7 can consist in metal filling by an electroforming (or electroplating) process.
It will be noted that a sufficient amount of third element 10 is provided during the inlaying phase to completely fill each groove 6, 7 in junction areas 9 and preferably over all the remaining length of grooves 6, 7. However, recesses in the filling by third element 10 on portions outside junction areas 9 may be envisaged, to provide a distinctive look.
During the inlaying or electroforming filling process, a surplus of third element 10 is formed outside the opening of grooves 6, 7. Consequently, once third element 10 is inserted, the method of the invention provides a subsequent step consisting in trimming said third element 10 until the surfaces of the first 2, second 3 and third 10 elements are seamlessly connected to each other. Preferably, trimming is achieved by milling or turning. This step removes the excess material of third element 10 until it is flush with the surfaces of elements 2, 3, 4. Third element 10 is thus perfectly incorporated in the other elements 2, 3, 4.
An optional additional step of polishing elements 2, 3, 4, 10 to smooth the surfaces and, in the case of a partly visible assembly, to give a smooth and flawless aesthetic appearance.
The assembly method according to the invention thus makes it possible to obtain an external component 1 including at least a first element 2 and second element 3 assembled by means of the assembly method described above.
In every method, the invention also concerns an external component 1 including at least a first element 2 and a second element 3 assembled in at least one junction area 9. A first groove 6 is arranged in said first element 2 and a second groove 7 is arranged in said second element 3, said first groove 6 and second groove 7 extending at least into each junction area 9. Such a component 1 also includes an inlay of an at least partially amorphous metallic material, at least partially filling first groove 6 and second groove 7 in each junction area 9 of first element 2 and second element 3.
As previously suggested, such a component 1 can be formed of more than two elements 2, 3, with one or more other elements 4, and with one or more third elements 10 inserted into the respective grooves 6, 7.
External component 1 is intended to be placed on a portable timepiece device, such as a watch. In particular, external component 1 may, in a non-limiting manner, form a watch bezel. Component 1 may be fixedly or movably mounted on the watch, by any securing means, particularly in a snap fit.
It is thus understood that timepiece component 1 may form all or part of an external component, such as, for example, a watch bezel, a bracelet link, a dial, a watch case or a clasp member, or may form all or part of a member of a timepiece movement. By way of example, it is possible to envisage making the balance, pallets, bridges or bars, oscillating weights or even the wheel sets, such as the escape wheels, completely or partially from ceramic. It is also possible to envisage making a case, a dial, a display, a decoration, an index, an applique, a flange, a bezel, a pusher, a crown, a case back, a hand or a bracelet wholly or partially from ceramic according to the invention.
Of course, the present invention is not limited to the illustrated example but is capable of various variants and modifications that will appear to those skilled in the art. In particular, the invention is not limited to an external component or even to the field of horology. Thus, by way of example, there is nothing to preclude using the assembly of the invention of a ceramic component 1 for an application in the field of tableware, or jewelry.
| Number | Date | Country | Kind |
|---|---|---|---|
| 18194458.8 | Sep 2018 | EP | regional |
