DESCRIPTION

The present invention relates to a method lor making a chain link Tor jewel lery and goldsmith's applications, as well as to a chain li nk and a device for manufacturing it.

In the jeweller and goldsmith's art. necklaces and oilier accessories, such as bracelets and earrings, are known which are chain-shaped, i .e. they include a scries of chained metal links which may also be made of precious metals, e.g. gold . In these links, stones o f various nature can be set. cut: into various faceted shapes, such as zircons or precious or semi-precious gems. Such links are therefore given suitable shapes, such as cylinders, cubes and reel angular prisms.

The chain of the present invention belongs to the typology commonly referred to as "tennis chain ^" or "cup chain ^" .

In a tennis chain, the links have a partial or through central cavity; on the side which is open to al low the gem to be positioned (cal led "setting ^-' ) there are prongs which, when appropriately wrought, al low to lock the gem in the desired position. In addition, the l inks of a tennis chain may feature side slots used for both connect ing the links together and al lowing more light to pass, thus improving (lie brilliance of the gems used in [lie jewel,

Tennis chai n l inks arc known to be manufactured through microcasting processes using lost wax models. In this case, the connection between the links is obtained by means of a suitably modelled peduncle or by inserti ng an additional element, between the links, generally consisting of a suitably shaped ring. As a rule, a weld is made on the connection element in order to improve the strength of the manufactured article. T hese steps are carried out manual ly by using speci fic jigs and tools.

Microcast solutions suffer from the drawback that, the necklace becomes heavy due to the fact that ofe links are substantial ly solid and their thickness must be such as to al low them to be obtained by microcasting; since gold is expensive, this weight translates into high cost of the raw materials needed for manufacturing, the necklace, which is not desirable for products intended for large market portions. Additionally, microcast solutions also have the drawback that Ihey require manual work for assembl ing and welding the links and for selling the gems, so that production vol umes are necessarily limited. Tennis chain links are known to be manufactured through mechanical chip-removal machining processes. Typical ly by micromilling.

The links obtained by micromilling suffer from the drawback that, the necklace is heavy due to the fact that the links are substantial ly solid: this translates into high raw material costs. Furthermore, the machining process removes precious material from the necklace, which is then difficult to recover, finally, although micromil ling gives a pleasant appearance and can be automated to a certain extent, it has the drawbacks that it is complex due to the small dimensions of the manufactured articles and that it does not leave much freedom in creating complex shapes.

Tennis chain l inks are also known to be made by mechanically pressing a flat strap, e.g. as described in patents US1573927 and US641 2303. I n these cases, the strap is suitably shaped to create links havi ng the shape of a cube or a rectangular-base prism, in which gems can beset. The pressing solution allows to manufacture links which are lighter than those obtained by microcast ing or micromil ling. When pressing is used, the connection between t he links can be achieved through an I -shaped element formi ng a link connection portion held in its seat at. both ends by suitable projecting regions, as shown also in ( IS641 230.3. As an alternative, the connection may be achieved by means of prongs inserted in suitable slots, as shown in US 1573927. Even for pressed links, the link and to connection element are usual ly welded, e.g. by means of laser techniques. The pressing production steps can be carried out automatical ly by using suitable equipment and machinery, leading to faster production rates. However, the solutions known in the art for manufacturing chain links by pressing suffer from, the drawback that the link can only be shaped l ike a cube or a rectangular-base prism; moreover, the known pressed solutions also have the drawback that the l inks require that precious material be used even in the hidden bottom region. Final ly, pressed solutions have the drawback, that they require an accurate welding of the connection elements because, due to their shape, they would otherwise naturally tend to position themselves incorrect ly when worn ; in fact, the pressed chains known in the art have a tendency to turn over when they arc bent in order to be worn around the neck, thus hiding the gems from view.

Links are a lso known to be made by pressing a flat strap, e.g. as described in patent. US47S 1038. In this ease, the links have through apertures, and the gems are held by thin prongs also acting, as a connection with the adjacent link. Though l ighter, this solution is excessively fragile because the chain, even when subjected to smal l stresses, wi l l tend to open and lose the set uems. I t is an object of the present invention to provide a link-type chain for jewel lery and goldsmith's appl ications and a manufacturing method thereof which can overcome the drawbacks of the prior art.

in particular, it is an object of the present invention to provide a link-type chain which can be automat ical ly produced in a simple manner, and wherein the l inks may have a variety o f shapes, even complex ones. To this end, the present invention also relates to a device for making such links.

It is another object of the present invention to provide a link-type chain which is lighter and stronger than the prior art. wherein a smal ler quantity of raw material is needed, and w herei n the connection between the links is strong and al lows the chain to position i tsel f correctly when worn as a necklace.

These and other objects of the present invention are achieved through a method for making a chain link for jewellery and goldsmith's appl ications, a chain link and a device for making said link incorporating the features set out in the appended claims, which are intended as an integral part of the present description.

The present invention is based on the general idea of providing a method for making a chain l ink for jewel lery and goldsmith's appl ications which comprises the steps o f cutting out a template from a flat metal strap, wherein said template has a direction o f extension that defines two ends thereof (208). and bending said template in order to match the two ends together.

Furthermore, the present invention is also based on the idea of providing a chain link and a device for making such a chain link.

This solution allows to overcome the drawbacks of the prior art; first of all , it allows to create a chain link having walls that define an open portion of any shape, e.g. circular or square or even more complex, into which gems can be set .

Furthermore, this solution allows to create chain links which are lighter and use a smaller quantity of raw material, si nce the open portion goes through the link and it is not strictly necessary to use any material to close the link bottom.

Advantageously, these links are connected together by means o f prongs made in one piece with said walls and engaged into suitable slots obtained in the wal ls of the adjacent links, without needing any additional connection elements. This type of connection provides the additional advantage that the chain, when worn as a necklace, will naturally tend to stay in the correct position, i .e. with the gems exposed. liven more advantageously, the present, l ink-type chai n is lighter than known chains, and it is more suited to fully automated machining; this reduces both raw material and production costs-.

Preferably, the chain of the present invention can be further strengthened by means of local welds. Still preferably, this chain allows brilliant stones to be set. held by additional prongs, in order to improve the bril liance and charm of the chain itself.

Further objects and advantages of the. present invention will become more apparent from the following detai led description and from the annexed drawings, which arc supplied by way of non-l im iting example, wherein:

Fig. 1 shows a chain for jewellery applications with pressed links according to the prior art;

- Fig. 2a shows an example of a chain li nk for jewel lery and goldsmith's applications according to the present invention;

Fig. 2b shows the planar extension of the surface of the l ink of Fig. 2a:

- Fig. 3a shows the connection between two links of Fig. 2a;

- Fig. 3 b shows an example of a chain for jewellery and goldsmith's appl ications comprising links according to the present invention;

Fig. 4 shows an example of processing of a strap from which l inks according to the present invention are obtained:

Figs. Sa, 5b, 5c, 5d, 5e. 511 5g. 5h. 5i. 5j. 5k. 51. 5m. 5n. 5o show an example of a device for making link-type chains according to the present invention and. ill ustrates the operating steps thereo f;

- Figs. 6a, 6h. 6c. 6d. 6e. 611 6g, 6h, 6i, 6j show further examples of l ink-type chains according to the present invention;

Fig. 7 shows a second example of processing of a strap from which links according to the present invention are obtained;

Fig. 8 shows a second example of a device for mak ing link-type chai ns according to the present invention;

Figs. 9a and 9b show a third example of a device for making link-type chains according to the present invention.

Fig. 1 shows a chain for jewellery and goldsmith's appl ications creaicd by pressing a strap according to the prior art . Each of the three links 101 is shaped l ike a rectangular-base prism, and the side walls are bent upwards from the bottom to al low the gem 1 02 to be set. held in its seat by four prongs. In the links there are also slots for inserting the connection elements 103. which will create the chain.

Fig. 2a shows a chain link 201. for jewellery and goldsmith's applications according to one embodiment of the present invention.

The side walls of the link 201 are bent about a vertical central axis 202. thus creating a shape which is substantially contained in a cylinder having the same axis 202; the inside of the link is completely hol low, and there is a through aperture at the axis 202. On one side of the link 201 two junction prongs 203 have been obtained, which face upwards and are used for connecting each link to an adjacent link of the chain: for this purpose, the link also features two passage slots 204 for the junction prongs, which slots are suitably sized to receive the prongs of the preceding l ink (only one slot is visible in Fig. 2 ). In the region of the link where the setting is formed (i.e. that portion into which the gem is to be set), there are gem support surfaces 205. in the proximity of which there are retaining prongs 206 which, once bent downwards, wil l retai n the gem in the setting. On the sides without junction prongs there are two slots 207 al lowing more light to pass and hit the gem, thus i mproving the bri l liance and charm of the jewel, in the l ink junction points 208 a weld can be made to strengthen the link, e.g. by using laser welding techniques.

Fig. 2b shows the planar extension of the template 201 ' representing the link 201 of Fig. 2a. wherein the same items are designated by the same reference numerals. I n this figure it can be appreciated that, prior to three-dimensional shaping, the template 201 ' is perfectly contained in a plane; this feature is very important for the manufacturing method described below, which creates the link stalling from a flat strap.

Fig. 2b also shows the direction of extension 209 of the template 20Γ ( in this case a horizontal direction), with its left and right ends 208; the ends 208 are so shaped as to create a perfect coupl ing when the template 201 ' is bent to form the l ink 201 , as shown in Fig. 2a. In fact, the ends 208 have such a shape that allows the edges of the template 201 ' (o be matched together and create a single junction, which may then be further welded as previously described.

Fig. 3a is a top view of a pai r of links 201 and 301 , both manufactured according to the above-described example. The drawing shows the connection between two links, obtained by inserting the junction prongs 302 of the link. 301 into the matching slots of the link 201 . Once inserted, the junction prongs 302 are bent head to head in the region 303 : i n this region, a. weld may be made in order to make the connection stronger. The gap between one link and the next, i.e. the distance between the links when mounted into a chain, depends on the intended use of the manufactured jewel . In particular, if the chai n is to be able to fol low large curvatures, it wi ll be necessary to leave a long distance between the li nks; otherwise, if more rigidity is required, the links will have to be kepi closer to one another.

Still with reference to Fig. 3a. there is shown the curvature 304 of the side wal ls of the link 201 ; the link 201 is bent about the vertical central axis 202 and has two straightcr portions near the chain axis (i.e. where the junction prongs 302 are located). The link 201 or 30 1 is bent starting from a flat template (like the template 201 ' of Fig. 2b) by following l ines belonging to the side walls of the link itsel f, said bending l ines being substantially orthogonal to the direction of extension of the l ink (i.e. the direction 209 of Fig. 2b). As will become apparent from the description of the method for making a l ink according to the present invention, the link shape is thus very flexible and may have any cross-section (e.g. circular, square, rectangular or polygonal), depending on the processing steps carried out.

Fig. 3b shows an example of a jewel chain made out of links according to the present invention; of these eleven links connected together, four l inks 305 have no gem set (to exemplify a jewel chain during the production process), whi le the remaining seven links 306 have a gem set and held in position by inward-bent retaining prongs.

Compared with microcast chain l inks, the solution proposed herein is lighter by about 50%, while the ligh! irradiation area on t he gem can be increased by 50%. I n addition, when compared with known solut ions pressed from a strap., this solution has no shape constraints, provides weight savings up to 1 5%, and the light irradiation area can increase up to 300%. The solut ion proposed herein is also stronger than prior-art chain links, because the stress generated when placing the gem. into the setti ng is distributed evenly along the entire edge of the link, without any free corners weakeni ng the structure.

Furthermore, the connection between the links 305 and 306 by means of junction prongs located in the middle of the height of the link, on the side wall thereof, allows the chain to remain in the correct position when worn, i.e, with the gems ex posed and without any torsion about the longitudinal axis.

As aforementioned, the link-type chain for jewellery applications according to the present invention is well suited to being manufactured by using fully automated machinery; a device will now be described which allows said links to be manufactured also in the form of a chain, along wi th an exemplified illustration of the manufacturing method thereof.

Fig. 4 shows an example of a si rap 401 from which (lie links for a chain according to the present invention are obtained. The thickness of the strap 401 , made of precious metal, is such as to allow it to he easi ly worked, typically between 0.1 mm and 0.5 mm. preferably 0.2 mm; the raw strap 401 is placed into a suitable device, typically a shearing/bending machine, which processes it "continuously" according to known mechanical working methods, so that di fferent portions of the strap 401 represent di fferent product processing stages. For this very reason, while describing the strap 401 it is possible to exempli fy some steps of the process for producing chain l inks according to the present invention.

The processing of the strap 401 begins with dril li ng a pi lot hole 402 for centering the strap, which hole is located at the centre of the width of the strap 401 . The width of the strap 401 is such that it allows for making Hat links, and is typically between 5 mm and 30 mm, more preferably between ¾ mm and 1 4 mm. The hole 402 will be used as a reference during the next steps of processing the strap 401 ; the strap's feed pitch must be such as to al low the links to be formed for their entire height , and is preferably between 3 mm and 8 mm, more preferably 5 mm.

The processi ng (if the strap 401 then continues wi th a step of dri ll ing the passage, slots 403 (or 204 with reference to Figs. 2a and 2b), followed by a step of drilling the light slots 404 (or 207 with reference to Figs. 2a and 2b).

After this step there is a step where no machining lakes place; the processing of the strap 401 includes steps wherein no culling or bending occurs, but which allow to make room lengthwise between t he various workstations, where the tools and actuators of the device can be accommodated.

The extension of the external profi le of the l ink is then sheared from the strap 401 on the lower side 405 and upper side 406, so as to free up its edges; of course. the material removed from the strap is recovered and mel ted again, since it typically is precious metal.

Subsequently, the junction prongs 407 (or 203 with reference to Figs, 2a and 2b) are hal f- sheared, i.e. sheared partially with shears from the strap profile while keeping t he innermost side in contact therewi th, and are then bent downwards along this side whi le staying connected to the link.

Finally, the first bend of the link 408 is made in a manner such as to lilt its ends and arrange the junction prongs perpendicular to said ends and lacing outwards (see 203 in Figs. 2a and 2b).

T he portion 4W. which represents a semifinished link (hereafter referred to as "link" for simplicity), is then detached from the strap 401 and conveyed to the next processing steps. e.g. after being picked up by on automated transport mechanism.

Once the link template has been obtained by pressing, it must be further worked in order to be closed and connected into a chain. Referring now to Figs. 5a to 5o, the following will describe the operation of a device adapted to continue the above-described process in order to create a chain of links according to the present invention. This device, which will now be described only by way of non-limiting example, allows to implement the steps of the process for manufacturing a chain for jewellery applications.

Fig. 5a schematically shows the chain-mak ing device 50 1 . which comprises: a pai r of combs 502 for bending the links, a holding carriage 503 arranged on the support 504. also acting as a l ink spacer, a link positioning device 505. a pair of hammers 506 for closing the prongs, and a support 507 for a pai r of centering pins 508 and 509 (not shown in Fig. 5a).

I he operation o f the device 50 1 will become more apparent J rom the fol lowing description: it must, be pointed out that it requires suitable actuators and actuator control means per se known in the goldsmith's art, which arc not shown in the drawings for simplicity.

Referring now to Fig. 5a. the positioning device 505 receives the semifinished l ink 409 (obtained as described with reference to Fig. 4 ) from the link transport system (not shown). The holding carriage 503 already contains Ihe link 201 produced as described during the previous processing steps according to a "sequential" process adapted to create a chain of interconnected links.

Fig. 5b shows the support 504 moving until it positions the hold ing carriage 503 in contact with the positioning device 505 , In this manner, since the holding carriage 503 also acts as a spacer, the junction prongs of the link 201 are inserted into matching passage slots in the link 409. In addit ion, the prong closing hammers 506 are brought to the outside of the junction prongs of the link 201 : thanks to their particular flared shape, the hammers 506 do not interfere with the other portions of the link 409.

Fig. 5c shows the hammers 506 closing to bend the prongs of the link 201 inwards, thus establishing the connection with the link 409 as previously described.

Fig. 5d shows the posit ioning device 505 disengaging from the link 409, which is now integral with the chain.

Fig. 5c shows the hammers 506 rising to the idle position and the support 504 descending to bring the holding carriage 503 at the same level as the combs 502.

Fig. 5 f more clearly shows the two centering pins 508 and 509 in the idle posit ion; in this step, the junction prongs of the link 409 arc butt welded by the laser beam 510, as already described.

Fig. 5g shows the movement of the support 507 to the work i ng position, during which the centering pin 509 enters the link 201 white the centering pin 508 moves to the central portion of l he l ink 409.

Fig. 5h shows the combs 502 which, after having moved to the centre i n contact with the holding carriage 503, act upon the l ink 409 by making a second bend.

Ftg, 5i shows the combs 502 convergi ng towards the centre and. thanks to the suitably curved shape of the lower portion thereof in contact with the link 409, finishing the second bending step by bringing the edges of the link 409 in head-to-hcad contact, so that the two ends of the link are matched in this region only. This figure also shows the junction prongs of the link 409 l i fted outwards from the l ink.

Fig. 5j shows the execution of a weld on the matched ends of the Unk 409 by means of a laser beam 511 .

Fig. 5k shows the combs 502 openi ng and descendi ng to the idle position.

Fig. 51 show ^' s the holding carriage 503 opening and releasing the l inks 201 and 409 fitted on the centering pins 508 and 509.

Fig. 5ni shows the support 507 descending to bring the pins of the links 201 and 409 near the holding carriage 503, which also acts as a link spacer, as previously described. In this way. the l inks can be connected one onto the other in sequence, thus forming a chain.

Fig, 5n shows the holdi ng carriage 503 closing around the links 409 and 201 . from which the junction prongs of the link 509 protrude.

Fig. 5o shows the backward movement of the support 507 to the idle position, which thus disengages the centering pins 508 and 509 from the chain links 409 and 20 ! . As can be seen. Fig. 5o shows a setup which is substantially eq uivalent to that shown in Fig. 5a, but at a later stage in which one link has been added to the chain. The steps shown in Figs. 5a to 5o are repeated cyclically in sequence, thus allowi ng a chain to be manufactured.

The steps described with reference to Figs, 5a to 5o merely exempl ify the production process: likewise, the shape of the elements of the device 501 may be varied depending on the shapes to be obtained. The circular-base shape described so far is particularly representative of the teachings of the present invention, because a completely hol low circular shape could not otherwise be obtained by bending or pressing in accordance with the teachings of the prior art. Sti l l in accordance with the teachings of the present invention, it is also possible to modify the shape of the combs 502 in order to change the final shape of the chain links. Figs. 6a to 6j show further embod iments of a chain for jewel lery and goldsmith's applicat ions according to the present invention.

Fig. 6a shows a chain in which the links 601 have a square-base shape and gem retaining prongs 601b arranged at the vertices of the setting. This variant can be implemented by using a centering pin with a substantially square shape, around wh ich the bending combs are adapted to position themselves.

Fig. 6b shows a chain in which the links 602 have a square-base shape with rounded edges. This variant can be implemented by using a square centering pin wi!h smoothed edges.

Fig. 6c shows a chain in which the links 603 have an oetagonal-ba.se shape, with retaining prongs 603 b engaging the four sides that are oblique relati ve to the chain axis. This variant can be implemented by using an octagonal centeri ng pin.

Fig. 6d shows a chain in which the links 604 have a circular-base shape, and in which retaining prongs 604b and 604c are present on both free faces of the chain, thereby al lowing gems to be set on both sides of the chain. Th is variant can be implemented by using a different shape in the strap shearing step which takes into account the presence of additional retaining prongs, This variant, advantageously obtained i n accordance with the teachings of the present invention, would be impossible to make on the basis of prior-art teachings.

Fig. 6c shows a chain in which the links 605 have a circular base, and on the lace opposite to the setting there are a pair of fins 605b partially closing the bottom. This variant can be implemented by using a d ifferent shape in the strap shearing step which lakes into account the presence of these additional fins.

Fig. 6f shows a chain i n which the links 606 have a circular base, and on the face opposite to the setting there, are a pair of fins 606b contacting each other head to head: this solution offers the advantage that the chain can be further strengthened by a weld. This variant, can also be implemented by using a di fferent shape in the strap shearing step which takes into account the presence of the additional fins.

Fig. 6g shows a chain in which the links 607 have a rectangular base wilh radiused edges, the prongs being positioned at the edges. The Sinks 607 can house gems with semicircular edges 607b or faceted gems 607b' as shown in Fig. 6h. This variant can be implemented by using a rectangular centering pin.

Fig. 6i shows a chai n in which the links 608 have a rectangular base and the gem retaining prongs 608b are positioned in pairs on the longer sides of the links 608. This variant can be implemented by using a rectangular centering pin. Finally. Fig, 6j shows a chain in which the links 609 have a square base and the retaining prongs 609b are positioned i n pairs on the opposed external sides of the chain. This variant can be implemented by using a square centering pin acting upon a flat template.

Fig. 7 shows a second example of a strap 701 from wh ich the links for a chain according to the present invention are obtained, in this second embodiment, the processing of the strap 701 begins with drill ing a pilot hole 702, fol lowed by drilling the passage slots 703 (or 204 with reference to Fig. 2) and by dril ling the light slots 704 (or 207 with reference to Fig, 2).

The extension of the externa! profile of the l ink is then sheared on the lower side 705 and on the upper side 706, so as to free up its edges; subsequently, the junction prongs 707 (or 203 with reference to Fig, 2) are half-sheared.

In this embodiment, the first bending of the link 708 for l ifting the ends thereof and arranging the junction prongs perpendicular to said ends is followed by an additional processing step, In fact, a shearing 709 is made to further release the l ink edges prior to the detachment step: on this draft a second bending 7 1 0 is made to lift and curve the link edges partially upwards. The l ink 71 1 is then fully detached and is conveyed to the next processing steps, as previously described.

The link produced by means of the method described above with reference to Fig, 7 is particularly suited to being further processed by the device shown in Fig. X.

Fig. 8 shows an embodiment of the l ink-making device S01 wherein the hammers 806 have a thi nner profi le that, allows them to be inserted into the link 71 1 and close the junction prongs of the preceding l ink, simi larly to what has been described with reference to Fig. 5b. This variant is characterised in that. it. limits the defomialion undergone by the link 71 1 during the bending step, since a greater deformation occurs in the strap processing step.

Figs. 9a and 9b show a further variant of the device 901 , wherein the elosing hammers 906 are suitably shaped like two halves of a centering pin.

The two halves 906a and 906b converge to close the junction prongs between the links and, once closed as shown in Fig. 9b, form a structure 906 which is equivalent to a centering pin as previously described, around which the combs 502 wil l bend the link 409, This variant, is characterised in that it reduces the number of elements of the device to be positioned near the link to be processed.

It is apparent that many changes may be made to the present invention by those sk i l led in the art without departing from the protection scope thereof as stated in the appended claims.

For example, links having more complex shapes than rectangular or circular may also be obtained, e.g. elliptic or lobed shapes.

Furthermore, a chain-making device is also conceivable which has only one centering pin 508: this solution can be fully operational provided that the movement of the .support 507 is ensured by a su fficiently accurate guide suffering no misal ignment problems.

A different strap processing cycle may also be conceived, wherein the strap can be pressed in. just one step or be placed into the shearing/bending machine in order to be processed horizontally, i .e. to obtain links lengthwise. Although alternative to the embodiment described herein, these solutions ore nonetheless substantially analogous thereto and do not depart from the teachings of the present, invention.