WATCH CASE WITH ROTATING BEZEL

Abstract

A watch case (6) including a rotating bezel (1), a middle (3) and a connecting spring (2) between the rotating bezel (1) and the middle (3), the connecting spring (2) being accommodated within a first groove (7) formed in an external wall (3a) of the middle (3) and within a second groove (8) formed in an internal wall (1 a) of the rotating bezel (1), the first and second grooves (7,8) being preferably arranged opposite one another. The connecting spring (2) is made of an alloy with memory of shape.

Claims

1. A watch case (6) comprising a rotating bezel (1), a middle (3) and a connecting spring (2) between the rotating bezel (1) and the middle (3), said connecting spring (2) being accommodated within a first groove (7) formed in an external wall (3a) of the middle (3) and within a second groove (8) formed in an internal wall (1a) of the rotating bezel (1), wherein the connecting spring (2) is made of an alloy with memory of shape.

2. The watch case (6) according to claim 1, wherein the alloy with memory of shape is a copper-based alloy, a nickel-based alloy, a nickel and titanium based alloy or an iron-based alloy.

3. The watch case (6) according to claim 1, wherein the nickel and titanium based alloy consists in weight of nickel with a percentage comprised between 52.5 and 63%, of titanium with a percentage comprised between 36.5 and 47% and of possible impurities with a percentage lower than or equal to 0.5%.

4. The watch case (6) according to claim 2, wherein the copper-based alloy is one of the alloys having the following composition in weight with a percentage of possible impurities lower than or equal to 0.5%: Cu between 64.5 and 85.5%, Zn between 9.5 and 25% and Al between 4.5 and 10%, Cu between 79.5 and 84.5%, Al between 12.5 and 14% and Ni between 2.5 and 6%, Cu between 87 and 88.2%, Al between 11 and 12% and Be between 0.3 and 0.7%.

5. The watch case (6) according to claim 1, wherein the connecting spring (2) has a polygonal shape.

6. The watch case (6) according to claim 1, wherein the connecting spring (2) has an annular shape with circular protrusions alternately disposed over the internal face and over the external face of the ring.

7. The watch case (6) according to claim 1, wherein said first and second grooves (7, 8) are arranged opposite one another.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0010] FIG. 1 represents a watch case provided with the connecting spring according to the invention.

[0011] FIG. 2 represents the connecting spring used in the watch case according to the invention.

[0012] FIGS. 3 to 5 represent the sequences of assembling the spring within the grooves of the middle and of the bezel according to the prior art.

[0013] FIG. 6 represents the stress-strain curve of an alloy with memory of shape.

[0014] FIG. 7 represents an alternative to the connecting spring of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

[0015] The watch case 6 includes a rotating bezel 1 mounted on the middle 3 (FIG. 1). The middle 3 and the rotating bezel 1 respectively include a groove 7 and a groove 8. The groove 7 is formed in the external wall 3a of the middle 3 and the groove 8 is formed in the internal wall 1a of the rotating bezel 1. Preferably, the grooves 7 and 8 are arranged opposite one another and serve as a housing for the connecting spring 2 according to the invention. Thanks to this spring 2, the rotating bezel 1 is pressed downwards against a shoulder 3d of the middle 3. As represented in FIG. 2, the connecting spring may have a polygonal shape. According to a variant represented in FIG. 7, the connecting spring may have an annular shape with circular protrusions 2a alternately disposed over the internal face and over the external face of the ring. Other shapes could also be considered without departing from the scope of the invention.

[0016] The connecting spring is made of an alloy with memory of shape. FIG. 6 illustrates the superelastic behaviour of an alloy with memory of shape which has an austenitic structure at room temperature which is transformed into martensite by the application of a stress, which allows deforming the material reversibly by several percents. The tensile curve has at first an elastic linear behaviour up to a critical stress where the martensitic transformation induces a superelastic behaviour with a deformation increasing under an almost constant stress. This is the level that is observed In FIG. 6. As soon as the stress is relieved, the reverse transformation from martensite into austenite is done and the alloy recovers its first dimension.

[0017] Preferably, the alloy with memory of shape is a nickel and titanium based alloy. This alloy is completely biocompatible and very corrosion-resistant. The nickel and titanium based alloy consists in weight of nickel with a percentage comprised between 52.5 and 63%, of titanium with a percentage comprised between 36.5 and 47% and of possible impurities with a percentage lower than or equal to 0.5%. Advantageously, it could consist of an alloy including 55.8% of titanium, 44% of nickel and of the possible impurities with a level lower than or equal to 0.2% by weight.

[0018] It could also consist of a copper-based alloy. More specifically, the copper-based alloy is one of the alloys having the following composition in weight with a percentage of possible impurities lower than or equal to 0.5%: [0019] Cu between 64.5 and 85.5%, Zn between 9.5 and 25% and Al between 4.5 and 10%, [0020] Cu between 79.5 and 84.5%, Al between 12.5 and 14% and Ni between 2.5 and 6%, [0021] Cu between 87 and 88.2%, Al between 11 and 12% and Be between 0.3 and 0.7%,
for a total percentage of 100%.

[0022] It could also consist of an iron-based alloy, for example a Fe—Mn—Si alloy. It could also consist of a titanium-free nickel-based alloy.

[0023] These alloys have an austenitic microstructure, at room temperature, in the absence of stresses.