EP0509938B1 - Unfoldable clasp - Google Patents

Abstract

The unfoldable clasp for a bracelet comprises a central shaft (1) formed from two parallel longitudinal members (2, 3) which are connected at their ends (4, 5), where unfoldable arms (6, 7), folding over and locking in the shaft (1) over a member (81, 82, respectively), transversely connecting the two longitudinal members (2, 3), are articulated. Each arm (6, 7) comprises a head (9, 10) which both receives a strand of the bracelet and ensures locking of the arm inside the shaft, and these heads (9, 10) each have, on their front face, a concavity (13, 14) which, upon locking, bears in compression on the transverse member (81, 82) and thus immobilises the unfoldable arm. The locking heads (9, 10) each have on their lower face (15, 16), a transverse groove (17, 18) placed to the rear of the concavity (13, 14). <IMAGE>

Description

The present invention relates to a folding clasp for a bracelet of the type comprising a central stretcher formed by two parallel beams connected at their ends. On these ends are articulated folding arms that fold back and lock in the stretcher.

For many years, we have endeavored to create bracelet clasps, which for aesthetic reasons, can be hidden when the bracelet is in the closed position. To achieve this objective, which consists in masking the clasp when the bracelet is closed, clasps with stretcher and folding arms have been proposed, the arms of which fold back into the stretcher to avoid any excess thickness, considered unsightly.

The problem is to properly lock these folding arms in the closed position, without seeing anything from the outside and various technical solutions have been adopted.

A first solution consists in locking the folding arms laterally in the stretcher, a solution which is described for example in the disclosures US 1 839 788, FR 537 072 and EP 0 115 740. The major drawback of this solution is that, in order to have a closure that is both safe and openable with sufficient ease, the lateral profiles of the folding arms and side members constituting the stretcher must be machined with great care, making the operation expensive.

A second solution consists in locking the folding arms at the end, and in this connection reference will be made to the presentation FR 2 619 292, in which each folding arm is blocked, by its beak-shaped head, in a corresponding rod connecting the side members.

Mention will also be made of the clasp described in the presentation CH 633 698 where the locking of the arms is carried out on a single central member.

The invention incorporates the simplicity of the technical solutions described in the disclosures FR 2 619 292 and CH 633 698, while eliminating the drawbacks which make them unrealistic.

According to the invention, in fact, a folding clasp for a bracelet is described comprising a central clasp formed by two parallel longitudinal members connected at their ends. On these are articulated folding arms which fold back and lock in the stretcher on a member transversely connecting the two side members. Each arm has a head which at the same time receives a strand of bracelet and ensures locking inside the stretcher. These heads each have a concavity on their anterior face which, when locked, comes to bear in compression on the transverse member and thus blocks the folding arms. The locking heads each have on their underside a transverse groove placed behind the concavity.

In a first embodiment, the transverse locking member is unique. On its own, it receives and blocks the two heads in closing.

In a second embodiment, each head has its own transverse locking member, these being for example placed side by side.

Preferably, the locking member or members are rods and, preferably also, the arms, each with its respective head, are in one piece.

In a particularly advantageous manner, the transverse groove formed on the underside of each of the folding arms is a U-shaped groove or of square or rectangular shape, and its width can be modified.

First of all, it will be observed that, with respect to the solution adopted in the description FR 2 619 292, the locking takes place in compression on the folding arms, and not in extension. The mechanism is more robust, simpler and better tolerates machining deviations.

Compared to the solution of the description CH 633 698, the presence of a central groove on each of the folding arms gives a shape of beak to the locking heads and thus ensuring the necessary flexibility allowing an easy locking and unlocking, which seems totally unrealistic with full rooms.

The fact also that the locking heads can, if desired, be made in one piece (monoblocks) with their arms leads to a great solidity of the assembly, which is not the case in the clasp of the exposed CH 633 698, where according to the figures, the head is in two added parts. The assembly described in this presentation therefore presents great fragility to repeated efforts.

In addition, the fact that the heads are in one piece makes it possible to dig relatively deep grooves on their underside, leaving enough material at the junction of these with their respective arms to geometrically provide additional flexibility, in addition to the flexibility inherent in the beak shape of the heads.

Finally, it will be noted that, since the width of the transverse groove can be modified, for example using a screwdriver or a knife point, it will thus be possible to compensate for the fatigue that the spout of the head, i.e. the part of the head between the concavity and the transverse groove. This ensures that the locking of the clasp will never be faulty, since if this locking would gradually become looser, it would be enough to open the throat very slightly to make up for this weakness.

• la figure 1 est vue de côté, en coupe, du fermoir de l'invention en position partiellement repliée, dans une première forme d'exécution ;
• la figure 2 est une vue de dessus du même fermoir, dont les longerons et bras dépliants sont illustrés partiellement en coupe ;
• la figure 3 est une vue en perspective de ce même fermoir en position ouverte ou dépliée ;
• la figure 4 est une vue de côté, en coupe, du fermoir de l'invention en position partiellement repliée, dans une deuxième forme d'exécution ;
• la figure 5 est une vue de dessus du fermoir de la figure 4, en position fermée, c'est-à-dire totalement repliée ; et
• la figure 6 est une vue en perspective du même fermoir de la figure 4, en position ouverte ou dépliée.

The invention will be better understood with reference to the appended figures given by way of nonlimiting examples. In these figures:

• Figure 1 is a side view, in section, of the clasp of the invention in partially folded position, in a first embodiment;
• Figure 2 is a top view of the same clasp, the side members and folding arms are shown partially in section;
• Figure 3 is a perspective view of the same clasp in the open or unfolded position;
• Figure 4 is a side view, in section, of the clasp of the invention in partially folded position, in a second embodiment;
• Figure 5 is a top view of the clasp of Figure 4, in the closed position, that is to say fully folded; and
• Figure 6 is a perspective view of the same clasp of Figure 4, in the open or unfolded position.

As seen in Figures 1 to 3, the clasp consists of a stretcher 1 formed of two parallel beams 2,3 which are connected at their ends by pins 4,5 on which are articulated two folding arms 6,7 .

These folding arms 6,7 fold back towards the center and are locked in the stretcher 1 around a single member 8 transversely connecting the two beams 2,3. As illustrated in the figures, this member 8 is a rod or pin arranged perpendicular to the side rails 2,3 and crimped therein. It is placed in the central position of the stretcher 1. In this way, the two folding arms 6,7 are of the same length.

In a variant not shown, the rod is not in the central position, but offset with respect to the transverse axis of symmetry of the stretcher 1, in which case, the two folding arms 6, 7 are of unequal length.

In another variant not illustrated, independent of the first, the rod serving as a locking member 8 is sheathed by a metal tube which covers and can rotate freely around it; alternatively, the metal sheath can be replaced by a plastic sheath, for example Teflon (registered trademark) either in the form of the sheath itself, or in the form of an adherent deposit.

The folding arms 6,7 each comprise a head 9,10 respectively, which are the extension and are integral with their respective arms 7,8. The two arms with their heads are therefore in one piece.

Each head 9, 10 has a bulge in which are provided fixing means making it possible to connect the latter to a strand of the bracelet; the same for the other head. These fixing means are shown diagrammatically in the figures by the axes 11, 12, the corresponding strands not being illustrated for the clarity of the figures.

The heads 9, 10 have on their anterior faces, that is to say on their faces which will come into contact with the locking member 8, a concavity 13, respectively 14, the depth and curvature of which are adjusted to the shape of the member 8, which may be as indicated above, a rod 8 cylindrical, ovoid or even polygonal.

On the lower faces 15, 16 of the arms, at the level of the heads 9, 10, grooves or grooves 17, respectively 18 are formed, so as to give the heads 9, 10 a form of beak 19, respectively 20, between the concavity 13, respectively 14, and the grooves 17, respectively 18. The depth of the grooves 17,18 is such that it allows a narrowing at the junction between the arm and the corresponding head, so as to bring to the assembly a some flexibility. However, most of the flexibility required for closing and locking, unlocking and opening, results from the elasticity of the spouts 19, respectively 20, due to the cooperation between the concavities 13,14 and the grooves 17.18.

The clasp of Figures 4 to 6 differs from the clasp of Figures 1 to 3 in that the single locking member 8 is replaced by two identical members 81,82 placed side by side, perpendicular to the beams 2,3 and symmetrically with respect to in the middle of the clasp (they could just as well be offset from the center, if the arms are of unequal length). Each head 9, 10 is locked on its own transverse member 81, respectively 82, rod or pin for example.

It will be observed that the concavities 13, 14 produced in the heads 9, 10 are hollower than in the execution of FIGS. 1 to 3. In either case, the objective aimed for technical reasons and aesthetic, is that, once the clasp is closed, the high and visible parts of the heads just come into contact with each other or are as close as possible. The shape and depth of the concavities will take this into account.

Locking the bracelet is a very simple operation since it suffices to fold the folding arms 6,7 into the stretcher 1 and to press lightly so that, by deformation of the spouts 19.20 of the heads 9,10, these spouts pass the resistance on the locking member 8, respectively the members 81, 82, and come to lock on their concavity 13, 14. For unlocking, the reverse operation is carried out just as easily.

It will be appreciated that the locking and unlocking operations are made particularly easy and can be repeated numerous times without risk of breakage, since the necessary flexibility is taken into account by the deformation of the spouts 19, 20 when the member 8 passes, organs 81.82 respectively, flexibility, part of which is also taken into account by the head 9.10 as a whole, due to the existence of grooves 17.18 in the thickness of the arms 6.7.

A huge advantage of the clasp according to the invention is that, if the material constituting the spouts 19,20 comes under repeated efforts, to deform slightly, no longer allowing satisfactory locking, it will suffice to catch up with this deformation by even imperceptibly widening the grooves 17,18, which can be done very easily with a simple tip of a screwdriver or knife.

To fix ideas, without the values given below being in any way limiting, we can retain, for a thickness of folding arms between 1.60 and 2.10 mm, a depth of grooves between 1.00 and 1.60 mm, with a thickness of spout between the groove and the bottom of the concavity of between 0.40 and 0.80 mm. These values are typical values which are well suited to the materials usually used to make clasps, such as metals, for example stainless steels, brasses, nickel silver, or certain plastics.

Claims (7)

1. A folding clasp for a bracelet comprising a central shank (1) formed by two parallel side members (2, 3) connected at their ends (4, 5), where folding arms (6, 7) are articulated, folding down and locking in the shank (1) on a member connecting the two side members (2, 3) transversely, each arm (6, 7) having a head (9, 10) which both receives a bracelet end and ensures the locking of the arm inside the shank, these heads (9, 10) each having on their front face a concavity (13, 14) which, when locking takes place, bears in compression on the transverse member and thus locks the folding arm, wherein the locking heads (9, 10) each have on their bottom face (15, 16) a transverse recess (17, 18) located behind the concavity (13, 14).
2. A clasp as claimed in Claim 1, wherein the transverse locking member is a single member (8).
3. A clasp as claimed in Claim 1, wherein it comprises two transverse locking members (81, 82) placed side by side, one for each arm (6, 7).
4. A clasp as claimed in Claim 1, 2 or 3, wherein the transverse recess (17, 18) has a width which can be modified.
5. A clasp as claimed in Claim 1, 2, 3 or 4, wherein the transverse member (8) and locking members (81, 82) respectively are rods.
6. A clasp as claimed in Claim 1 or 4, wherein the arms (6, 7), each with their respective head (9, 10), are made in a single piece.
7. A clasp as claimed in Claim 5, wherein the rod is covered with a sheath which is able to rotate freely about it.

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