The present invention concerns a procedure as defined in the preamble to Claim 1 for making a chain, and a chain as defined in the preamble to Claim 8.

The chain constituting the object of the in¬ vention is primarily intended to be used as suspension chain in needs of the jewelry industry, e.g. as a neck¬ lace chain or bracelet chain. In such uses the struc- ture (appearance) of the chain is the main and deter¬ mining factor.

On the basis of appearance, the most closely equivalent chains are the so-called spiral chain and the so-called Etruscan chain. The spiral chain is made of one or several continuous filaments. The objectionable feature of the spiral chain is its poor bendability, due to the way of making it of one single filament. The durability of the spiral chain is also fairly poor because in such a chain comparatively sharp kinks are made in the chain, which invariably detract from its strength. Moreover, repairing a spiral chain is an awkward job, because a junction has to be made in the normally continuous filament in order to repair the chain. An Etruscan chain is made of separate, oval shaped loops, which are disposed within each other, "loop-in-loop". The drawback of the Etruscan chain is its rigidity (poor flexibility), which is due to the manufacturing process, making the chain of loops going one into the other. Owing to the manufacturing mode, the chain will also be comparatively heavy. Repairing an Etruscan chain is also cumbersome work, owing to the compact structure of the chain.

The object of the invention is to eliminate the drawbacks mentioned. Specifically, the object of the invention is to disclose a resilient, strong, light construction, easy to repair, also industrially easy to

produce, and visually attractive chain, and the manu¬ facturing procedure thereof.

Regarding the features characterizing the invention, reference is made to the claims section. In the procedure of the invention, separate closed rings are made of filamentary material. The rings are bent to have at least three loops advantage¬ ously with regular spacing, that is, the circumference of the ring is pressed inward so that outward extending loops are formed between the points where pressure is applied. The loops are thereafter slipped through the loops of the preceding ring on the chain which is being manufactured, and the loops of the ring are bent up¬ ward, or in the direction in which the chain is growing, to receive the corresponding loops of the next ring.

Advantageously, the separate closed rings are produced by winding the filamentary material to a helix, cutting up the helix into separate pieces and joining the ends of each piece to form a closed ring.

Advantageously, the loops on the ring are initially bent towards the loops of the preceding ring, i.e., towards the end of the chain in the process of forming, which makes it easier to pass the loops of the ring through those of that preceding ring on the end of the chain. On having been slipped through, the downward bent loops are then turned up in the opposite direc¬ tion, to receive the downward pointing loops of the ring next in order to be mounted. Advantageously, the loops which are made on the ring are bent in such manner that the ring con¬ taining these loops will present a roundedly and smoothly undulating or meandering stellate configura¬ tion with no sharp angles or abrupt bends. Hereby the chain which is formed will be uniform in quality, and strong.

Advantageously, the chain which is finished as

to its length is calibrated by drawing it through a calibration ring, whereby the chain acquires the final, uniform cross sectional dimension.

The chain of the invention comprises a plu- rality of closed rings connected with each other and which in aggregate constitute an elongated chain. As taught by the invention, the rings are separately closed and connected to each other by bending them so that each ring comprises at least three loops which are passed through the corresponding loops of the preceding ring on the chain and have been bent forward in the assembly direction of the chain, to receive the corre¬ sponding loops of the next ring.

Advantageously, the rings used in the inven- tion are metal rings and specifically in needs occur¬ ring in jewelry industry, noble metal rings.

The chain of the invention can equally be made of steel rings, and appropriate dimensioning provided it may then be used e.g. as protective and transport packaging for elongated objects because the chain de¬ fines in itself a hollow space and the shell thereof is comparatively thick and resilient. In this way an ap¬ propriately dimensioned chain will furnish efficient protection to the elongated object within it against external impacts.

In the chain structure of the invention, the ring may equally have several loops and their location relative to each other may be suitably variable, whereby it is possible to produce chains, and pieces of jewelry, of different cross sections and different appearance so that the shape of the chain varies from flat to completely round. The chain may be made varia¬ ble of its cross section as well.

The advantage of the invention over prior art is that in this way a very thin and flexible chain can be produced without sacrificing any of its durability, owing to the fact that in no phase are any sharp angles

made in the filament which is used or in the individual rings. The production of the chain of the invention is easy to mechanize, and in mechanical production this chain will be economically well competitive owing to its strength/weight ratio.

In the following the invention is described in detail, referring to the enclosed drawings, wherein Fig. 1 presents the ring used in a chain according to the invention, Fig. 2 presents the ring bending step,

Fig. 3 presents the chain assembly step, and Fig. 4 shows the finished chain construction.

The chain of the invention is made as follows. First, a number of rings 1 as depicted in Fig. 1, or round, solid rings, are made. The ring 1 is pressed with suitable members 5 in the direction towards the centre of the ring so that loops 2 are formed of the ring periphery, between the points where pressure is applied, in the present embodiment four loops. The loops, as well as the intervening ring regions, are smoothly curved and round-shaped.

As shown in Fig. 3, the loops 2 of the ring being mounted on the end of the chain are bent in the direction towards the end of the chain, that is down- ward in Fig. 3, and the loops 2 can then be slipped through the corresponding loops 4 of the preceding ring 3 on the end of the chain. The loops 4 are pointing upward, that is towards the new ring 1 which is being mounted. After the loops 2 of the ring 1 have been passed through the loops 4 of the ring 3, the loops 2 are turned upward, whereby they are now ready to re¬ ceive the downward bent loops of the ring to be mounted next.

By carrying on in this way and by joining to each other rings provided with loops, one obtains a chain as shown in Fig. 4, which is highly elastic, light in construction and strong.

In the foregoing the invention has been de¬ scribed by way of example with the aid of the drawings, while different embodiments can be contemplated within the scope of the inventive idea delimited by the claims.