CH718208A2 - Assembly of elements such as links of a bracelet. - Google Patents

Abstract

The invention relates to relates to a part (21), in particular a bracelet, comprising at least two sets (1) of elements (3,5,7), in particular links, assembled together. According to the invention, the fixing between the elements (3,5,7) within an assembly and between assemblies is carried out via gluing (15) and not screwing. The invention also relates to the method of manufacturing the part (21).

Description

Field of the invention

The invention relates to an assembly of elements and more specifically to a part comprising several sets of elements assembled together. The elements can form the links of a bracelet, a decorative article or an article of jewellery.

Prior art

[0002] In the watch industry or in jewelry, various materials are used for the manufacture of bracelets of various appearance. It is in particular known to manufacture bracelets in a hard material. By hard material is meant materials having a Vickers hardness greater than 1000 HV. These hard materials are, for example, ceramics such as silicon nitride, zirconium oxide or aluminum oxide. They may also be cermets. Hard materials are used for their mechanical properties, in particular because they are difficult to scratch. The bracelet links made of these materials are generally obtained after an injection step giving the desired shape to the link, then by a sintering step to harden the material.

[0003] The assembly of bracelet links requires the presence of holes provided with a thread on the link for screwing in a screw or an element provided with a thread. The machining of these threads in a hard material is difficult.

[0004] In addition, the realization of tapping requires complex molds which limit the possibilities of injection on these links. Thus, the injection point must be arranged on a face not comprising the thread, that is to say on a visible face of the link. At the level of this injection point, there may be defects such as segregations, flow lines and this in particular during the injection of colored ceramics. The presence of these defects on a visible face requires this face to be machined to remove the defects. It is therefore not possible to directly inject the link into its final shape.

Summary of the invention

The object of the present invention is to overcome the aforementioned drawbacks by proposing an assembly without screwing between the links to avoid the realization of threads within the link.

To this end, the invention relates to a part, in particular a bracelet, comprising at least two sets of elements, in particular links, assembled together. According to the invention, the fixing between the elements within an assembly and between assemblies is carried out via gluing and not screwing.

More specifically, the present invention relates to a part comprising at least two sets of elements assembled together, each set comprising a first, a second and a third element with the first element and the second element arranged on either side. else of the third element. The first and the second elements each comprise a first and a second blind recess and the third element comprises a first and a second through-hole, the first through-hole of the third element being placed opposite the first blind recess of the first and second elements within of each set, the second through-hole of the third element of a set being placed opposite the second blind recess of the first and second elements of another set. Fastening within each assembly and between the two assemblies is respectively ensured by: a first rod mounted in the first through hole of the third element and fixed at its ends with an adhesive in the first blind recess of the first and second elements, a second rod mounted in the second through-hole of the third element and fixed at its ends with said glue in the second blind recess of the first and second elements.

According to the invention, the blind recesses have a particular shape which ensures the anchoring of the rods within the blind recesses. The first blind recess and the second blind recess conventionally delimit a longitudinal zone for housing the end of the first and second rods. According to the invention, this longitudinal zone opens into at least one cavity extending laterally with respect to said longitudinal zone. This cavity forms a housing where the glue is contained and fixed around the end of the rods, which ensures their firm hold within the recess.

Preferably, said first blind recess and said second blind recess each delimit two cavities extending laterally with respect to the longitudinal zone, the two cavities being respectively positioned on each side of the longitudinal zone.

[0010] Thus, the cavity or cavities make it possible to achieve a mechanical grip between the glue and the links, which makes it possible to firmly secure the various assemblies.

[0011] In addition, fixing by gluing makes it possible to reduce the costs of mounting the strap and to simplify mounting.

[0012] The absence of tapping in the blind recesses also makes it possible to simplify the injection mold with the corollary that the injection point can be on the face comprising the blind recesses, that is to say on one side non visible. This makes it possible to avoid the machining step and to inject directly to form the link.

[0013] According to particular embodiments of the invention, the part has one or an appropriate combination of the following characteristics: the two cavities are positioned opposite each other on each side of the longitudinal zone; the longitudinal zone extends on either side of said at least one cavity; the first rod and the second rod comprise at their ends a head provided with a notch on its periphery, said notch being filled with the glue and positioned facing said at least one cavity; at least a part of the first and second elements is made of an enamel, a stone, a sapphire, a cermet or a ceramic. within each set, the third element is formed of several elements with an intermediate element disposed between each of said several elements; the first through-hole and/or the second through-hole of the third element comprise a cross-section of corresponding non-circular shape with that of the first and second rods respectively in order to prevent any relative pivoting of the first, second and third elements; the first through-hole and the second through-hole of the third element have a cross-section of corresponding circular shape with that of the first and second rods in order to allow the pivoting of the third element with respect to the first and second elements; it comprises at least five interconnected sets; it is a bracelet, a decorative article or an article of jewelry.

The present invention also relates to the process for manufacturing the part comprising a step of producing at least one of the first, second and third elements by additive manufacturing or by injection and sintering and comprising a step of assembling and fixing by gluing of the first, second and third elements.

According to a particular mode of the process, the first element and the second element are produced by injection and sintering according to the following steps: a) a step of producing a precursor from a mixture of at least one material powder with a binder, b) a step of producing an insert made of polymer material, the insert having at least partly a negative shape of the first and second blind recesses, c) a step of overmolding the precursor onto the insert made of polymer material by injection into a mold in order to form a green body, and d) a step of sintering said green body in order to form said first element and second element in said material.

Other characteristics and advantages of the present invention will appear in the following description of a preferred embodiment, presented by way of non-limiting example with reference to the accompanying drawings.

Brief description of figures

Figure 1 is a sectional view of a part according to the invention with an assembly by gluing between the links. Figure 2 is a plan view of another part according to the invention with the mounting by gluing between the links. Figures 3a and 3b illustrate the step of fixing the rod in a link by gluing. Figure 4 is a block diagram of the process for making the links provided with a blind recess. Figures 5a to 5c represent schematic cross-sectional views of a link obtained according to the method of Figure 4. Figure 6 is a perspective view of a link according to the invention.

detailed description

The present invention relates to an assembly of elements which are, for example, links intended to form a bracelet, a decorative article or an article of jewelry. The assembly is more specifically adapted for elements made in whole or in part with hard materials. The term “hard materials” according to the invention designates materials whose hardness is substantially equal to or greater than 600 HV, or even equal to or greater than 1000 HV, and which accept little or no plastic deformation before breaking. Mention may be made, without limitation, as hard materials, for example, enamels, precious or non-precious stones such as ruby, sapphire or quartz, ceramics such as an oxide, a carbide or a metal nitride or non-metallic, cermets or even hard metals.

The part according to the invention, which is illustrated below for a bracelet, comprises at least two sets of elements assembled together. According to the invention, the fixing between the elements within an assembly and between assemblies is carried out by gluing.

Each assembly 1, delimited by dotted lines in Figure 1, comprises at least three elements 3,5,7 which can be formed wholly or partly in hard materials. It comprises a first lateral element 3 and a second lateral element 5 substantially symmetrical with respect to a third element 7 disposed between the lateral elements. Note that the elements 3,5,7 are preferably staggered.

The first and second elements 3.5 each comprise a first blind recess 2.4 while the third element 7 comprises a first through hole 6. As shown in Figure 1, the recesses 2.4 and the hole 6 are intended to be aligned in order to secure the first, second and third elements 3,5,7 together via a rod 11 mounted in the through hole 6 of the third central element 7 and glued at its ends within the recesses 2,4. The blind recesses 2.4 delimit a longitudinal zone 2a, 4a for housing the ends of the rod 11 and at least one cavity 2b, 4b extending laterally with respect to said longitudinal zone (fig.3a). This cavity receives the glue 15 to ensure a mechanical grip of the glue within the first and second elements (fig.3b). Preferably, there are two lateral cavities 2b, 4b arranged on either side of the longitudinal zone 2a, 4a and preferably one opposite the other. Still preferably, the longitudinal zone 2a, 4a extends on either side of the cavities 2b, 4b with the end of the rod 11 which bears against the end of the longitudinal zone 2a, 4a.

In addition, preferably, the rod 11 has at its ends a head 11a with a notch 11b provided over its entire periphery. This notch is filled with the glue and placed opposite the cavities. The rod 11 comprises a main part 10 received in the through hole 6 of the third element 7 (fig.1). Depending on the clearance left or the respective shape of the through-hole 6 and of the part 10, the first and second lateral elements 3.5 may or may not pivot with respect to the third central element 7 . By way of non-limiting example, the through-hole 6 may comprise a cross section of corresponding non-circular shape with that of the central part 10 of the rod 11 in order to prevent any relative pivoting of the first, second and third 3.5, 7 elements. On the contrary, it can be envisaged that the through hole 6 has a cross section of corresponding circular shape with that of the part 10 of the rod 11 in order to allow the pivoting of the third central element 7 with respect to the first and second elements 3, 5 side.

In a variant shown in Figure 2, each assembly 31 comprises five elements. Indeed, in addition to the three elements 33,35',37 comparable to those 3,5,7 of the first type of assembly 1, the assembly 31 of the second type comprises an intermediate row with a second central element 37' and a intermediate element 35.

1.31 The set is assembled with another set and so on to form a piece such as, for example, a bracelet, a decorative item or an item of jewelry. As shown in Figure 2, several sets 31 can be interconnected by a clasp 61 to form the bracelet intended to be mounted on a timepiece caseband.

The two sets 1.31 are also interconnected via a rod 11′ mounted in a second through-hole 24 of the third element 7 of a set 1. Each end of the rod 11′ is mounted and glued respectively in a second blind recess 27, 28 made in a first and second elements 3, 5 of another set 1 adjacent. The rod 11' intended to be mounted in the second through-hole 24 has a configuration similar to that intended to be mounted in the first through-hole 6. Similarly, the blind recesses 27, 28 have the same characteristics as the blind recesses 2, 4.

It is understood that, as for the first through hole 6, depending on the clearance left or the respective shape of the through hole 24 and of the rod 11 'the third central element 7 may or may not pivot relative to the first and second elements 3 .5 sides that frame it. Just as for the first through-hole 6, the through-hole 24 may comprise a cross-section of corresponding non-circular shape with that of the rod 11' in order to prevent any relative pivoting between the third element and the first and second side elements. On the contrary, it can be envisaged that the through hole 24 has a cross section of corresponding circular shape with that of the rod 11' in order to allow this relative pivoting.

The assembly method of sets 1 is explained below. Initially, the elements 3,5,7 are made with the different holes or recesses 2,4,6,27,28,24. Preferably, at least the elements 3.5 with the blind recesses 2,4,27,28 are made by additive manufacturing or by injection and sintering according to a method described in more detail below. Secondly, the rods 11,11' are mounted and fixed by gluing respectively in the recesses 2 and 27 of the side element 3 (fig.3a and fig.3b). The glue can, for example, be an epoxy glue with a viscosity > 400 Pas and a tensile strength > 40N/mm2. Bonding is carried out by deposition with a syringe under pressure. In a third step, the parts of the rods 11,11 'projecting from the first lateral element 3 are threaded respectively for the first rod 11 in the first through hole 6 of a third element 7 of an assembly 1 and for the second rod 11' in the second through-hole 24 of the third element 7 of an adjacent assembly 1. Fourthly, the second end of each rod 11,11' projecting from the third elements 7 is mounted and fixed by gluing in the recesses 4 and 28 of the second lateral element 5 . At the end of the fourth time, the elements 3, 5 and 7 within each set, as well as the sets between them are totally united.

In the presence of more than three elements as shown in Figure 2, the principle is substantially the same with the elements 37,37 'forming the third central element. The first and second through-holes of these elements 37,37' communicate with two through-holes provided respectively in the intermediate elements 35 of two adjacent assemblies 31 to respectively receive the two rods 11,11' extending between the side elements 33,35 'provided with blind recesses.

As explained above, the side elements 3.5 with the blind recesses can be made by additive manufacturing or by injection and sintering. Blind recesses can be made directly during additive manufacturing. For manufacture by injection and sintering, the side elements with the blind recesses can be made by overmolding the hard material on a lost plastic insert having the shape of the recesses in accordance with application EP 20194714. In accordance with this application and as schematized at FIG. 4, method 8 comprises a first step of production a) of a precursor from a mixture of at least one hard material which is in powder form with a binder. In this context, the ceramic-based powder can comprise at least one metal oxide, a metal nitride or a metal carbide. By way of example, the ceramic-based powder may comprise aluminum oxide or a mixture of aluminum oxide and chromium oxide in order to form synthetic ruby, zirconium oxide, which may be optionally pigmented, alumina, which may be optionally pigmented, silicon nitride, cermets, metals and composites of these metals. The cermets are for example titanium carbide or tungsten carbide. The metals are for example tungsten, titanium, 316L stainless steel or steel, preferably without nickel. The binder is of the organic type.

The method 8 comprises a second step b) of producing an insert 9 of polymer material, the insert having at least partly a negative shape of that desired for the recesses of the side elements 3.5 (fig. 5a). The polymer is for example chosen from the following list: PVD (for plasticized Polyvinyl Butyral), CAB (for Plasticized Cellulose Acetate Butyrate), acrylic resin of the PBMA type (for Polybutyl methacrylate).

A third step c) consists in molding the precursor 16 on the insert 9 in polymer material in order to form a green body 14 (fig.5b). Overmolding is in particular carried out by injection into a mould. The mold has at least partly the shape of the desired part given a shrinkage coefficient of the part. The precursor is injected into the mold through a tube, then through precursor distribution circuits throughout the mold. The precursor thus takes the shape of the mold which is that of the side elements. Alternatively, it is also possible to carry out the injection by circular layer or by channels. The green body takes the shape of the mold and at least partly the shape of the insert on which it is overmolded.

In a fourth step d), the green body is machined to eliminate unnecessary parts of the green body produced by the injection. For example, tubing or channels formed because of the tube or distribution circuits of the injection system are eliminated. Thus, a machined green body is obtained.

In a fifth step e), the polymer insert 9 is removed by thermal debinding. Preferably, the green body overmoulded on the insert is immersed in an alcohol bath at 80°. The alcohol bath dissolves the polymer insert, so that the green body is obtained with the desired shape given by the insert. Alternatively, thermal debinding can be carried out to remove the polymer insert. The body overmoulded on the insert is thus heated to high temperature to make the polymer disappear. The green body is therefore freed from the polymer insert. The insert leaves a positive shape in the green body 14, which is that of the blind recess 2,4,27,28 (fig.5c).

The sixth step f) has the function of sintering said machined green body in order to form a body of the future part in said at least one hard material. Sintering consists of heating the precursor so that the powder grains agglomerate. During sintering, the green body hardens by shrinking to result in a hard body with a sintering coefficient. Preferably according to the invention, the sintering step may include pyrolysis. The resulting part body is substantially hardened by this step. Thus, the body of the part has a final shape as shown in figure 6.

[0035] A seventh step g) may also be necessary to carry out satin finishing and/or polishing of the hard material. Thus, the aesthetic appearance of the side element is improved.

Then the side elements are assembled within each set in accordance with the assembly process described above.

Alternatively, for manufacturing by injection and sintering as well as for additive manufacturing, the blind recesses can be made by machining in the green body before sintering or in the hard body after sintering.

The central element 7 can also be manufactured by additive manufacturing, or by injection and sintering.

Claims (13)

1. Part (21,51) comprising at least two sets (1,31) of elements (3,5,7,33,35,35',37,37') assembled together, each set (1,31 ) comprising a first (3,33), a second (5,35') and a third (7,37,37') elements with the first element (3,33) and the second element (5,35') arranged on either side of the third element (7,37,37'), the first (3,33) and the second (5,35') elements each comprising a first (2,4) and a second blind recesses ( 27,28) and the third element (7,37,37') comprising a first (6) and a second (24) through-hole, the first through-hole (6) of the third element (7,37,37') being placed opposite the first blind recess (2.4) of the first (3.33) and second (5.35') elements within each set (1.31), the second through-hole (24) of the third element ( 7,37,37') of a set (1,31) being placed facing the second blind recess (27,28) of the first (3,33) and second (5,35') elements of another set (1.31), the fixing within each set (1.31) and between the two sets (1.31) being respectively ensured by: – a first rod (11) mounted in the first through hole (6) of the third element (7,37,37') and fixed at its ends in the first blind recess (2,4) of the first (3,33) and second (5.35') elements, – a second rod (11') mounted in the second through-hole (24) of the third element (7,37,37') and fixed at its ends in the second blind recess (27,28) of the first (3,33) and second (5.35') elements, the part (21,51) being characterized in that: – said first rod (11) and said second rod (11') are respectively fixed in the first blind recess (2,4) and in the second blind recess (27,28) with an adhesive (15), – said first blind recess (2,4) and said second blind recess (27,28) form a longitudinal zone (2a,4a) for housing respectively the ends of the first (11) and the second (11') rod , said longitudinal zone (2a, 4a) opening onto at least one cavity (2b, 4b) extending laterally relative to said longitudinal zone (2a, 4a), said cavity (2b, 4b) receiving the glue (15) and ensuring a mechanical grip of the glue (15) within the first (3.33) and second (5.35') elements. 2. Part (21,51) according to claim 1, characterized in that said longitudinal zone (2a, 4a) leads to two cavities (2b, 4b) extending laterally with respect to the longitudinal zone (2a, 4a), the two cavities (2b, 4b) being respectively positioned on each side of the longitudinal zone (2a, 4a). 3. Part (21,51) according to claim 2, characterized in that the two cavities (2b, 4b) are positioned opposite each other on each side of the longitudinal zone (2a, 4a). 4. Part (21,51) according to one of the preceding claims, characterized in that the longitudinal zone (2a, 4a) extends on either side of said at least cavity (2b, 4b). 5. Part (21,51) according to one of the preceding claims, characterized in that the first rod (11) and the second rod (11 ') comprise at their ends a head (11a, 11'a) provided with a notch (11b, 11'b) on its periphery, said notch (11b, 11'b) being filled with the glue (15) and positioned opposite said at least cavity (2b, 4b). 6. Part (21,51) according to one of the preceding claims, characterized in that at least a part of the first and second elements (3, 5, 33, 35 ') is made of an enamel, a stone, a sapphire, cermet or ceramic. 7. Part (21,51) according to one of the preceding claims, characterized in that, within each set, the third element (7,37,37 ') is formed of several elements (37,37') with an intermediate element (35) arranged between each of said several elements (37,37'). 8. Part (21,51) according to one of the preceding claims, characterized in that the first through hole (6) and / or the second through hole (24) of the third element (7,37,37 ') comprise a cross-section of corresponding non-circular shape with that respectively of the first and second rods (11,11') in order to prevent any relative pivoting of the first, second and third elements (3,5,33,35',7, 37',37). 9. Part (21,51) according to one of claims 1 to 7, characterized in that the first through hole (6) and the second through hole (24) of the third element (7,37,37 ') comprise a cross section of corresponding circular shape with that of the first and second rods (11,11') in order to allow the pivoting of the third element (7,37,37') with respect to the first and second elements (3,5 ,33,35'). 10. Part (21,51) according to one of the preceding claims, characterized in that it comprises at least five assemblies (1,31) interconnected. 11. Part (21,51) according to one of the preceding claims, characterized in that it is a bracelet, a decorative article or an article of jewelry. 12. Method of manufacturing the part (21,51) according to one of claims 1 to 11, characterized in that it comprises a step of producing at least one of the first (3,33), second (5 ,35') and third (7,37,37') elements by additive manufacturing or by injection and sintering and in that it comprises a step of assembling and fixing by bonding the first (3,33), second ( 5.35') and third (7,37,37') elements. 13. Manufacturing process according to the preceding claim, characterized in that the first element (3.33) and the second element (5.35 ') are made by injection and sintering according to the following steps: a) a step of producing a precursor (16) from a mixture of at least one powdered material with a binder, b) a step of producing an insert (9) of polymer material, the insert (9) having at least partly a negative shape of the first (2,4) and second blind recesses (27,28), c) a step of overmolding the precursor (16) on the insert (9) in polymer material by injection into a mold in order to form a green body (14), and d) a step of sintering said green body (14) in order to form said first element (3.33) and second element (5.35') in said material.