TECHNICAL FIELD The present invention refers to a process for the production of necklaces, particularly of noble metal necklaces, gold for example, which are barrel shaped or have more complex shapes, their pieces having the several possible shapes being subsequently subjected to further working phases like for example diamond cutting.

The present invention finds a particularly suitable application in the field of industrial scale production of jewellery items, particularly necklaces.

BACKGROUND ART A process for the production of golden necklaces is known, be them of the sphere, barrel type or with elements having any other shape, that consists of feeding a golden thread having a suitable thickness to a first dying station, said feeding being accomplished on a continuous basis with a motion of the intermittent type, according to a predefined step and suitable to the type of die that was previously chosen, that is to the shape that is meant to be given to the chain itself.

For a better understanding of the present specification, it is necessary to emphasise that by the term"barrel necklace"it is meant to define a necklace that is made up of a sequence of elements that are substantially cylindrical or have an elongated shape and that are joined together by a thread, whereas by the term"sphere necklace"it is meant to define a necklace that is made up of a sequence of spherical elements that are joined together by means of a thread.

The process for the production of necklaces of the above types is carried out by the concurring action of a first dying station whose die and counterdie are shaped in such a way as to gradually modify the shape of the golden thread which is fed with intermittent motion and with a suitable step.

This means that such a first dying station is actually made of a sequence of dies and counterdies that are distanced one form the others by a length equalling one step, so that a certain stretch of necklace fed to said first station is subjected to a

plurality of consecutive dyings as this progressively advances within the station itself.

Said dies and counterdies have shapes with substantially different sizes so that a golden thread that is fed reaches the desired profile in a gradual and progressive fashion as it moves through them, being died at each subsequent advancement made stepwise within said first dying station.

According to the state of the art, in case the production of a sphere or barrel necklace is aimed at, the dies used in said first dying station are such that they gradually and progressively confer a suitable shape onto each stretch of fed thread, said shape furher having a minimum thickness section in the area corresponding with the longitudinal axis of the thread itself.

This means that the golden thread coming out of the first dying station results to be died at definite distances determined by the predetermined step, so that they are capable of highlighting specific conformations each of which has a minimum thickness section that is of paramount importance in the process for the production of necklaces, as it is going to be more evident from reading the rest of the present specification.

The golden thread thereby obtained and shaped is then forwarded to a second dying station that was specifically meant for the production of spheres or of barrels or of any other type that is meant to be obtained so that the necklace acquires its desired aesthetic features.

The production of the spheres or of the barrels is made possible by the introduction of the golden thread into said second dying station simultaneously with a precious metal tape or plate having a suitable thickness and size, said precious metal being for example gold.

Even in this case the feeding both of the thread and of the tape or plate to said second station, is carried out in an intermittent and synchronised manner, according to the step previously set for the specific production cycle that is meant to be accomplished.

Said second dying station has the straightforward function to shape the tape or the plate in order to obtain the spheres or barrels around the golden thread that is being fed and, more precisely, at a point corresponding to each stretch of golden thread provided with the reduced peculiar shape that is obtained during the first dying step; in such a way in fact said thread is bound to result to be centrally positioned with respect to the sphere or the barrel dealt with, once the second dying stage has

been performed.

In order to reach such a result, similarly to what stated with reference to the first dying station, the second station is also provided with a plurality of dies and counterdies that operate with a consequential and progressive fashion along each stretch of tape or plate fed with an intermittent step and motion as it was described above.

At its inlet the dies and counterdies of said second station are provided with a guide that is initially flat shaped and such that at the inlet of said second station, the thread coming from the first station is found to move above the tape or plate.

Moreover, said guide is provided with walls that become ever more round shaped and convergent, so much that they fold over each other, along the second dying station, and they die the tape or plate up to obtaining the sphere or barrel shaped structure which is aimed at, within which the thread is positioned so as to be parallel to the longitudinal axis of the guide.

Clearly, depending on whether a sphere, a barrel or whatever other type of necklace is aimed at, dies and counterdies of the second dying station are bound to have suitable shapes and steps so that the desired type of necklace can be obtained.

For example, in case a barrel having the size of a couple of balls is aimed at, the dies to be employed for such an operation are made in such a way that a stretch of thread comprising two areas with a minimum thickness section and coming from the first dying station, as described above, is wrapped with a stretch of tape, said tape and thread being simultaneously motioned and with an intermittent fashion according to a suitably predetermined step for the production of a given barrel.

At the outlet of said second dying station, the necklace bears a sequence of spheres or barrels or differently shaped elements which are folded over around the central thread of the necklace itself, said spheres or barrels needing a suitable welding which is capable of joining the two perimetral edges of the portion of tape or plate employed to wrap said thread and obtain said spheres or barrels.

Such an operation is indeed necessary whenever the sequence of operations carried out on the spheres or on the barrels, diamond cutting in particular, is carried out by dint of tools that operate along a direction that is normal to the necklace itself, therefore transversally to said spheres or barrels.

In case such a specific welding operation were not carried out, the tools which have just been defined would cause the unavoidable breakage of the spheres or the

barrels, therefore the breakage of the whole necklace, exerting its action on the joining area of the tape.

Prior to being translated to said welding station, a necklace at the outlet of the second welding station is subjected to a shaking action caused by a device which is provided with a suitable arm, said action aiming at breaking the thread inside each sphere or barrel exactly where the section thereof is the thinnest, that is where there are found to be the easy breaking points.

The shape given to the thread during its first dying action is such that once severed, said thread is provided with a suitable shape at its ends that makes it possible for it to be kept inside the sphere or barrel without running the risk of nipping out of the sphere or barrel.

The breakage of the thread following the first dying action which has just been described, makes it possible for each sphere or barrel to be more tightly constrained to the thread, therefore to be capable of rotating around its longitudinal axis that is in fact the longitudinal axis of the thread itself.

It is necessary to emphasise that in case the production of a sphere necklace is pursued, inside each sphere there is found to be lust one minimum thickness section of the thread, which on breaking gives way to the appearance of two distinct ends within the thread that runs across said sphere, during the shaking stage.

Instead, in case the production of a barrel necklace is pursued, each barrel is provided with a stretch of thread inside it comprising at least two sections having minimum thickness, this meaning that at the very moment these sections come to their breaking point, the formation of one or more stretches of thread ensues, said stretches of thread being technically defined as"bones", that are free from the thread itself and trapped inside the barrel.

As it was previously mentioned, the necklace resulting from the above operations need be subjected to a welding operation that should be carried out along the edges of each sphere or of each barrel which has not perfectly folded and closed over itself.

In order to accomplish the above operation, the necklace is sunk into a suitable welding powder and after that, into a talc powder, to be then forwarded into the oven wherein the welding of said welding powder and the ensuing welding of the spheres or of the barrels of the necklace takes place.

Said oven which is for example of the electrical resistance type, provides such

a temperature that the welding powder is made to melt, nevertheless the gold that is contained in the tape which the sphere or barrel are made of keeps its original solid state, said temperature being in the 900° C range.

As previously mentioned, the necklace is first of all immersed into talc powder too because talc is required in order to fulfill its lubrifying function, which is definitely needed mostly around the poles of said spheres or barrels, that is at the points where the thread intersects their surface.

This results to be particularly important because the presence of talc powder prevents the spheres and the barrels from being welded to the thread at their poles, thus making it possible for them to freely rotate, thing which is absolutely necessary in the following working phases that the necklace is subjected to.

At this point of the production process, necklaces are often subjected to a diamond cutting operation which is meant to refine and work the spheres or the barrels according to predefined shapes and/or patterns.

Said diamond cutting must be carried out with extreme precision, blocking at its poles each sphere or barrel by suitable means and operating with tools that act longitudinally and/or transversally to the surface of said spheres or barrels which are gradually rotated as the chiselling that is being performed progresses.

According to the state of the art described above, the production of barrel necklaces or of necklaces having other shapes and enclosing two or more sections having minimum thickness of the above mentioned type inside them, has several inconvenients and drawbacks caused by the presence of said stretches of detached thread that end up caged inside the barrels, said stretches having been previously defined as"bones".

In fact, these being able to move inside the barrels, because of the rotary movement that the barrels have when the necklace is worn they may well get stuck with the thread ends coming out of the polar areas of the barrels themselves.

Therefore this may cause the barrels to be prevented from rotating and the impossibility to carry out a diamond cutting with the tools that are meant to be used.

Furthermore, since that particular operation is carried out automatically, it often happens that said tools compel the barrels to rotate, causing their breakage or even the breakage of the whole necklace, thing which causes an interruption of the operation and the necessary substitution of the necklace with a waste of time and material.

It can further happen that the bones end up getting stuck following the penetration of the welding powder into the barrel of which above, this again giving way to the impossibility for the barrels to rotate that has the consequences detailed above.

A further drawback found in the production of said necklaces and once again caused by the presence of said bones is that these often end up hindering the diamond cutting operation, despite leaving the barrel rotation undisturbed, because of the position they take.

In fact it may well happen that these bones gain a point that corresponds with one of the areas whereon the tool operates, said aspect being rather disadvantageous as the tool is hindered by the presence of the bone.

In some cases however if the bone is in an unsuitable position, it may cause the need for the diamond cutting tool to be a rather excessively strained effort, this itself leading for example to the breakage of the barrel and of the whole necklace, for example.

DESCRIPTION OF THE INVENTION The present invention aims at overcoming the disadvantages and drawbacks which are typical of the prior art, therefore at proposing a process for the production of necklaces, particularly of precious metal necklaces, for example of golden necklaces, of the barrel type or having other different more complicated shapes, by which it is possible to obtain a high quality product without risking breaking the necklace during its working phases.

The above aim is accomplished thanks to the process described in the main claim.

Dependent claims outline particularly advantageous forms of embodiment of the present invention.

A further aim of the present invention is that of supplying a first dying station that is provided with suitable dies that are capable of a regular and an optimal accomplishment of the following working stages, among which the diamond cutting stage for example.

This is accomplished by the operational features detailed in claim 3.

According to the present invention, in case the idea is that of producing necklaces of the barrel type or having even more complex elongated shapes, dies and counterdies which the first dying station is equipped with and dealt with above, are

shaped in such a way that during the shaking and breaking phases of the thread contained inside the barrels, said thread may break at just one point and not cause the development of any bone typical of the prior art.

This means that it is an aim of the present invention to propose the preparation of a particular type of dies that are suitable for producing a thread that is subjected to working and has a one section with minimum thickness, therefore just one breaking point within each barrel or other shape whose production is desired.

It is therefore clear that the employment of such a type of dies makes it possible to devise a process for the working of chains that has undoubtedly got several advantages when compared with the backgound art, said advantages being determined by the absence of development of said bone that is typical of the prior art.

In fact contriving just one breaking point and concurrently avoiding the formation of said bone, following the shaking action there are found to arise two loose ends of the thread inside the barrel that are shaped in such a way not to be extractable from the barrel which they belong to.

That situation is particularly advantageous as the barrel is free to rotate around its own axis and inside it there is not found to be present anything hindering said rotation and the subsequent workings that it is subjected to, such as diamond cutting for example.

According to the present invention, the tools used for the operations that follow the welding stage are therefore capable of operating both longitudinally and transversally to the barrel itself, without risking deforming or piercing the barrel, or even breaking the necklace, each barrel being capable of being clamped and rotated in an optimal manner.

ILLUSTRATION OF DRAWINGS Other features and advantages of the present invention will become more apparent from reading the description that follows, which is given by way of not limiting example, with reference to the annexed figures given in the following tables, where: -figure 1 shows a schematic plan view from above of a stretch of sphere necklace coming out of a first dying section according to the background art; -figure 2 shows a schematic plan view from above of a stretch of barrel necklace as it comes out of a first dying according to the background art; -figure 3 shows a schematic plan view from above of a barrel according

to the backgorund art, shown after breakage of the sections having minimum thickness; -figure 4 shows a schematic plan view from above of a stretch of barrel necklace coming out of a first dying section according to the present invention; and -figure 5 shows a schematic plan view from above of a stretch of barrel chain according to the invention.

DESCRIPTION OF A FORM OF EMBODIMENT With particular reference to figure 1, a thread 10 coming out of a first dying station which is suitable for the production of sphere necklaces according to the background art has a plurality of sections 11 having minimum thickness, and distanced one from the other by a predetermined step.

By the side of each minimum thickness section 11 there is found a couple of symmetrical elements 12,12'obtained during the following dying operations and joined to each other by a stretch 13 of the thread having minimum thickness, said section having minimum thickness being the above mentioned breaking point 11 of necklace 10.

According to the backgound art, once the second dying operation has been accomplished, this being aimed particularly in the case shown in figure 1 at the production of a sphere shaped element 14 (drawn with a dotted line as figure 12 refers to a stretch of thread that is coming out of the first dying station), necklace 10 is subjected to a shaking action that is severe enough to give way to the separation of elements 12,12'in correspondence with section 11 having minimum thickness.

The particular conformation given to elements 12,12'by the dying operation does not make it possible for thread 10 to be extracted from sphere 14 which is free to rotate around its own axis 15 (which is also the axis of thread 10) therefore it can be clamped by the suitable tools that were devised for executing the ensuing workings on the sphere itself.

In figure 2, a thread 10 is shown coming out of a first dying section according to the background art and suitable for the production of necklaces of the barrel type.

In the example therein shown, each barrel 16 (drawn with dotted lines as figure 2 refers to a stretch of thread that is still coming out of the first dying station) results to consist of the coupling between two sections having minimum thickness 17, 17'of the type shown in figure 1.

According to that specific barrel shaped form of embodiment, analogously to

what shown in the case of sphere shaped necklaces (figure 1), each section having minimum thickness 17,17'respectively bears a couple of symmetrical elements 18, 18'and 19,19', said symmetrical elements being joined to each other by a stretch 20, 21 of thread having minimum thickness, within each couple.

Once the second dying operation has been accomplished, by which with particular reference to figure 2, barrel 10 is obtained, necklace 10 is subjected to a shaking action that gives way to the separation of elements 18,18'along stretch 20 with minimum thickness stretch, and division of elements 19,19'along stretch 21 with minimum thickness.

Once again, the particular shaping of elements 18,19'does not make it possible for thread 10 to be extracted from barrel 16; moreover in such a case and differently from what shown in figure 1, the breaking action of the sections having minimum thickness brings about the development of the so called bone 22 as it clearly appears in figure 3.

It is clear that the occurrence of said bone 22 inside barrel 16 may be cause of remarkable hindrance during the rotation of the barrel itself, said bone 22 being for example capable of interacting and getting stuck with elements 18 and 19'of necklace 10, preventing a proper rotation of barrel 16 from taking place.

In figure 4 a stretch of necklace 10 is shown as it was obtained by the process for the production of necklaces of the barrel type or having more complex shapes according to the present invention.

Stretch of necklace 10 shown in figure 4 highlights the particular shape that the golden thread acquires during the dying action exerted according to the invention.

According to the form of embodiment shown (figure 4), barrel 23 (even in this case drawn with a dotted line because figure 4 refers to a stretch of thread coming out of the first dying station) is obtained from the matching of a couple of symmetrical elements 24,24'joined to each other by an only stretch 25 of thread with minimum thickness.

Each of said elements 24,24'is shaped in a way similar to that of respective couples 18,18'and 19,19'of the background art, save the substantial difference that in the solution proposed by the background art two or more breaking points can be envisaged inside each barrel, whereas according to the present invention just one breaking point 25 can be identified inside each barrel.

There are therefore found to be avoided the risks of breakages and blockages

of the barrel and/or of the entire necklace which are typical of the background art.

The invention has been so far described with particular reference to one of its forms of embodiment.

It is nonetheless to be taken for granted that the invention is not limited to this form of embodiment, but that it includes all the modifications and variants that may be taken into consideration, without in so doing stepping out of the scope of the present patent as claimed.

For example, the operational methodology according to the present invention can be applied to necklaces other than those of the barrel type (as shown in figure 4), like for example whatever type of necklace having even the most complex shapes.