CH717758A2 - Device for fixing a back to a caseband for a timepiece. - Google Patents

Abstract

The invention relates to a device (100) for fixing a case back (2) to a middle part (1) of a watch, the case back (2) having a shoulder forming a cover arranged to entirely and partly cover the case middle (1) and a body arranged to rest in the caseband (1), said device comprising at least one pin (4) secured to the caseband (1), a seal mounted between the back (2) and the caseband (1). According to the invention, the bottom (2) comprises, close to its periphery, at least one groove (5), the pin (4) being arranged to slide in the groove (5) between a first position, called the position of introduction in which the back (2) is free, and a second position called the locking position in which the back (2) is locked and positioned angularly with respect to the caseband (1), and in that the said groove (5) comprises at least one bump (55) to form a hard point and increase the torque when the pin (4) passes over the bump (55).

Description

Field of the invention

The invention relates to a device for fixing a bottom on a middle part of a watch.

The invention also relates to a timepiece, in particular a watch, comprising such a device.

Background of the invention

[0003] The dressing of watches and similar devices obeys many constraints, in particular sealing, robustness, appearance, and must be carried out in such a way as to prevent any involuntary dismantling resulting irremediably in an intervention after - sale for exchange of seals, cleaning, lubrication, even repair.

[0004] Certain trim or control components must still be indexed angularly with respect to each other, for markings of the original reference position, rest, or actuation, or even to facilitate reading. indications or graduations, or to ensure the continuity of straight surfaces and/or decorations. This angular indexing is often tricky to do well, in combination with good tightening of the components and perfect sealing of the joints.

Summary of the invention

[0005] The invention proposes to produce a sealed and secure assembly of trim components with easy-to-perform angular indexing.

[0006] To this end, the invention relates to a device for fixing a back to a caseband according to claim 1.

The invention also relates to a timepiece comprising such a fixing device.

Brief description of the drawings

Other characteristics and advantages of the invention will appear more clearly on reading the following description of a particular embodiment of the invention, given by way of a simple illustrative and non-limiting example, and the appended figures , among : Figure 1 is an exploded perspective view of a fastening device according to the invention; FIGS. 2a and 2b are respectively a perspective view of a bottom and a middle part of a fixing device according to the invention; FIGS. 3a and 3b are respectively a top view of a bottom and a sectional view of FIG. 3a of the bottom of a fixing device according to the invention; FIGS. 4a and 4b are respectively a bottom view of a middle part and a sectional view of FIG. 4a of the middle part of a fixing device according to the invention; Figures 5a and 5b are respectively a perspective view of the assembled fixing device and a sectional view of Figure 5a; FIG. 6 represent the various possible embodiments for the groove of a fastening device according to the invention.

Detailed Description of Preferred Embodiments

[0009] The invention proposes to produce a sealed and secure assembly of trim components with easy-to-perform angular indexing, and in a guaranteed position, and this with a minimum number of components.

Figures 1 to 5b illustrate the non-limiting example of mounting and angular indexing of a background relative to a watch middle.

The invention relates to a device 100 for fixing a back 2 to a caseband 1 of a watch comprising at least one pin 4 secured to the caseband, a seal mounted on the back, said back comprising, close to its periphery, at least one groove arranged to cooperate with the pin. The bottom 2 comprises, close to its periphery, at least one groove 5, the pin 4 being arranged to slide in the groove 5 between a first position, called the insertion position in which the bottom 2 is free, and a second position said locking position in which the back 2 is locked and positioned angularly with respect to the middle part 1, and in that the said groove 5 comprises at least one bump 55 to form a hard point and increase the torque when the pin 4 passes to the bump level 55.

[0012] The bottom 2 is arranged to pass from a first disassembled insertion position to a second assembled and locked position. As illustrated in Figure 2a, the bottom 2 has a shoulder 20 forming a cover 21 arranged to cover in whole in part with the caseband 1 and a body 22 arranged to rest in the caseband.

In the first disassembled position of insertion, the middle 1 and the bottom 2 have relative to each other a first angular orientation.

[0014] According to the invention, the back 2 comprises sealing means, such as an O-ring seal 3, at the interface between the caseband and the back, the back having a groove to receive the gasket . The passage from the first disassembled insertion position to the second assembled and locked position is carried out under the action of forces exerted by an operator: an axial force to overcome the resistant force of the O-ring seal and assemble the bottom 2 and the caseband 1, and a torque to bring them into an angular indexing position.

In the second assembled and locked position, the caseband and the back have relative to each other a second angular orientation different from the first angular orientation. The back 2 and the middle 1 are held axially by means of a bayonet fitting.

[0016] Advantageously, the attachment of the back and the caseband by bayonet adjustment, in particular around an axial direction D, is reversible, and allows their dismantling. In a manner specific to the invention, this dismantling requires on the part of an operator efforts similar to those exerted during assembly, this dismantling preferably requires the use of a special tool, cooperating for example with holes or peripheral notches arranged on the visible face of the bottom 2. Such an assembly makes it possible to avoid dismantling of the bottom by the wearer, or dismantling following clumsiness or impact.

According to the invention, this fixing device comprises at least a third component, a pin 4, which is arranged to be interposed axially between the bottom 2 and the middle part 1 and fixed in rotation with respect to one of between them, and which comprises at least one elastically deformable zone.

This pin 4 comprises a head 40, a body 41 and a foot 42 and is integral with the middle part. As shown, the body 41, the head 40 and the foot 42 are cylindrical in shape, the body 41 having a diameter smaller than the diameters of the head 40 and the foot 42. The diameter of the head 40 and the foot 42 is identical, but it could very well be different, one could also imagine different geometric shapes for the piece 4, such as a body 41 of parallelepiped shape with a square section.

According to a preferred embodiment of the invention, the pin 4 is mounted in the middle part, the middle part 1 comprising for this purpose a machining 10 with an inverted T-shaped opening for receiving the pin 4, the opening of the machining 10 emerging inside the caseband so as to make the assembly invisible. Advantageously, the machining 10 having at least one rib 11, and preferably two ribs, on the wall of the body of the T so as to perform an assembly by clipping the pin 4 in the machining 10, the head of the pin being housed in the head of the T-shaped machining.

The pin 4 can be made of different materials such as polyoxymethylene, polyurethane, a polymer-based material, or elastomer, known for example asutane® or hytrel®. The material chosen makes it possible to determine the maximum tightening torque, thus a pin 4 allows a tightening torque of approximately 1.5 N.m, lower than that usual for a back screwed onto a middle part, for a conventional assembly. The interest of such a pin 4, preferably in a polymer or similar elastic material, is its facility to accommodate it in a volume whose free space is limited, and where it is impossible to implant an element in complete safety. metal that can break.

Thus, the body 41 of the pin 4 is deformable and is arranged to oppose a resistive torque of variable moment to any relative tangential torque between the back 2 and the caseband 1.

The body 41 of the pin is arranged to cooperate with at least one complementary relief, such as a bump 55, which the bottom 2 has. 21 at least one groove 5 which extends along a radius of the bottom 2 and has a depth at least equal to half the height of the pin 4, and a width of dimension equivalent to the diameter of the body 41 of the pin 4 so that the pin 4 slides within the groove 5. The groove 5 comprises a bottom 50, a first end 51 and a second end 52, and two walls 53, the bottom 50 of the groove being in the form of a groove 54 whose width is equivalent to the dimensions of the head or the foot of the pawn 4 so as to guide the pawn and maintain it axially.

[0023] Thus, any passage of the pin 4 over the bump 55 in the groove 5 generates a resistive torque which tends to oppose the relative rotational movement between the caseband 1 and the back 2.

According to a preferred embodiment, the groove 5 comprises a plurality of bumps 55, which are arranged to oppose successive resistance during the passage of the pin 4. According to the invention, in the same groove 5, the angular distance between the successive bumps 55 decrease so as to oppose an increasing resistance, during a rotation between the back 2 and the caseband 1. The angular distance between the successive bumps 55 can also be provided constant so as to oppose a constant resistive torque.

[0025] Several configurations for the arrangement of the bumps are possible. According to a first embodiment, one or more bumps 55 are present on a single side wall of the groove 5. According to a second embodiment, one or more bumps are arranged on the two side walls of the groove 5, the bumps of each wall being arranged opposite each other. According to a third embodiment, one or more bumps are arranged on the two side walls of the groove 5, the bumps of each wall being offset from each other. Similarly, the distance between bumps positioned opposite each other can vary so as to provide a progressive resistive torque, as shown in Figure 6.

The first end 51 of the groove 5 forms a space for the introduction of the pin 4, and the second end 52 forms a stop 6 and holds the pin 4 in position in the groove 5. To do this, the first end 51 has similar dimensions to the head or foot of pawn 4, and the second end 52 has similar dimensions to the body of pawn 4.

It is understood that the resistant force is all the more important as the number of grooves 5, bumps 55 and complementary pins 4 in cooperation is high. It is therefore possible to play on the number of successive bumps, and/or on the number of pawns and grooves. According to a preferred embodiment of the invention, the back comprises three grooves distributed angularly in a regular manner, and the caseband comprises three complementary pins.

[0028] Naturally, the configuration can be reversed, with at least one groove machined in the middle part and at least one peg integral with the back.

[0029] During assembly, the operator places the bottom on the caseband so as to match the foot of the peg(s) with the first end 51 of the groove(s) 5 so that the pegs fit there when the operator imparts a translational movement to the back 2 to place the cover 21 of the back 2 close to the lower edge 13 of the caseband 1, so that the pin comes into abutment against the back and thus ensures the seal thanks to the seal 3. The peg has a height very slightly greater than the distance between the bottom of the forge and the bottom cover, which can avoid contact between the bottom and the middle, and a clearance of 0.02mm to 0.04mm is present between the back and the middle.

Then the operator prints a progressive torque to print the relative rotation between the caseband 1 and the bottom 2; during this rotation, the operator carrying out the assembly encounters a first resistance when the body 41 of the pin 4 is brought into cooperation with the first bump 55 of the groove 5. Thus, the resistive torque increases during the relative rotation.

In a first case, the first bump 55 cooperating with the pin is unique. In a second case, the throat comprises several bumps 55 so that the operator provides a force in jolts during rotation, the peak of the cumulative resistant torque increasing during each passage of hard point, to reach, at the indexing angle, the maximum value. The operator thus encounters a feeling of increasing resistance, up to the stop 52.

As shown in the figures, the bottom 2 comprises three grooves 55, distributed at 120°, each of the grooves being arranged to cooperate with a pin 4 complementary to the groove. The case middle thus comprises three pins distributed at 120°, and the operator feels a single passage of hard point when the three pins at 120° pass a bump 55 simultaneously.

[0033] The seal exists as soon as the back is in place on the middle part, and the mechanism according to the invention is arranged so that, as in the previous case of a single bump, the securing of the seal of the or seals is ensured as soon as the back is inserted into the caseband, and then no loosening can occur without voluntary action by an operator.

[0034] In practice, very good results are obtained with at least two, and preferably three, or even four, successive bumps, so as to provide an elementary angular stroke sufficient for the passage of each bump.

The invention requires, during assembly, the successive crossing of several bumps so as to form an increasing resistance, but also during dismantling, because, from the indexed final position, in particular on the mechanical stop, any application of a sudden effort results, in the worst case, in the crossing of a single bump 55, without total disassembly, with a visual shift, but above all without loss of water resistance or risk of pollution of the interior of the watch . In the example illustrated, even when the operator successively crosses three thresholds, visible optically due to the offset, sealing is still ensured. To have a loss of tightness, the operator must partially remove the bottom so that the gasket is no longer compressed, the gasket not being impacted by the rotation of the bottom.

According to one embodiment, the distance between each bump 55 is identical, and its passage opposes the same resistive torque.

In an advantageous variant, the distance between each bump is decreasing, and the operator must apply an increasing torque, as in the example of the three bumps 55 of FIG. 3a.

The invention is advantageous because it is perfectly compatible with watchmaking dimensions, while having a capacity for a high resistant force, which can reach a few N.m.

[0039] Moreover, in the case where the timepiece is subject to particular constraints of great magnitude, the dismantling of the mechanism according to the invention requires the maintenance of the application of a possible force of accidental origin. during a significant angular stroke, from 5 to 10° for crossing a single bump in the example illustrated, safety still remaining assured if several bumps follow one another.

According to the invention, the angular indexing is guaranteed by the second end 52 which forms a stop 6 for limiting travel.

The invention thus makes it possible to prevent any unexpected and involuntary dismantling of the bottom of the caseband, for example under the effect of vibrations, of successive expansion cycles, by inadvertent use of the wearer, or otherwise.

[0042] Preferably, the dismantling requires a special tool not marketed, which ensures the execution of maintenance by after-sales personnel with the required qualifications.

[0043] The invention lends itself well to cases where the middle part and the back are made of different materials, with different coefficients of expansion, or even fragile or hard materials (ceramic, sapphire), which do not allow standard fixing methods. Examples of classic configurations include the assembly of a gold caseband with a sapphire back, or a case entirely in ceramic, a metal-ceramic combination, or the like.

[0044] An important advantage of the invention is to eliminate any contact/friction between the caseback and the caseband and thus prevent the appearance of residues due to friction and the addition of a grease to trap them as it is. the case in the prior art.

Another important advantage of the invention is to provide increased security on opening thanks to the successive passage of several notches and the obligation to at least partially remove the bottom before any loss of tightness.

The invention also relates to a timepiece or watch 1000 comprising such a fixing device 100.

In short, the invention provides a fixing device whose design is compact, which maintains the sealing of the watch, it protects against accidental disassembly.

The invention also makes it possible to ensure the perfect orientation of a component held locked in its service position.

The invention provides many advantages: from a first relative angular position, between the caseback and the caseband, where the sealing function is ensured, for example as soon as the compression of a seal is performed, there exists, in the mechanism according to invention, a widened range of relative angular values between the back and the caseband, in which sealing remains guaranteed, for example by several tens of degrees, which is significant in comparison with, for example, a standard screwed back in the case of a caseband-back subassembly, where an unscrewing of only a few degrees leads to the loss of tightness and the need for cleanliness and a new seal, whereas according to the invention this is only after the passage of the very last notch during dismantling that the loss of tightness becomes possible if the rotation is continued and that one begins to extract the back 2 of the middle part 1; a closure by succession of notches which has a largely dimensioned bottom closing torque, both sufficient and acceptable for such an assembly, thanks in particular to the multiplication of the number of bumps distributed in the groove, with, for the operator, a feeling of tightening in stages of increasing the closing torque up to the desired position, deemed to be the closed position, which is also perceptible; opening safety, which is increased by two factors: the need for the operator to provide significant positive energy to pass a notch, and the successive passage of several notches prior to any loss of tightness.

Claims (15)

1. Fixing device (100) of a bottom on a middle part of a watch, the bottom (2) having a shoulder (20) forming a cover (21) arranged to completely cover in part with the middle part (1) and a body (22) arranged to rest in the caseband (1), said device comprising at least one pin (4) secured to the caseband, a seal mounted between the back (2) and the caseband (1), characterized in that that said bottom (2) comprises, close to its periphery, at least one groove (5), the pin (4) being arranged to slide in the groove (5) between a first position, called the insertion position in which the back (2) is free, and a second position called locking position in which the back (2) is locked and positioned angularly with respect to the middle (1), and in that said groove (5) comprises at least one bump (55) to form a hard point and increase the torque during the passage of the pin (4) at the level of the bump (55). 2. Fixing device (100) of a bottom (2) on a middle part (1) of a watch according to claim 1, characterized in that the pin (4) is mounted in the middle part (1), said pin (4) having a body (41), a head (40) and a foot (42), the body having a diameter smaller than the diameters of the head and/or the foot. 3. Fixing device (100) of a bottom (2) on a middle part (1) of a watch according to claim 2, characterized in that the middle part (1) comprises a machining (10) with an opening in the shape of an inverted T for receiving the peg, said machining (10) having at least one rib (11) so as to effect an assembly by clipping the peg (4) into the machining (10). 4. Fixing device (100) of a bottom (2) on a middle part (1) of a watch according to claim 3, characterized in that the opening of the machining (10) opens inside the middle (1). 5. Fixing device (100) of a bottom on a middle part of a watch according to one of the preceding claims, characterized in that the pin (4) is made of a rigid and elastically deformable material, such as polyoxymethylene , polyurethane, a polymer-based material, or even an elastomeric material. 6. Fixing device (100) of a bottom on a middle part of a watch according to claim 1, in which the pin (4) is machined with the middle part (1), the assembly forming an element of a single holding. 7. Fixing device (100) of a bottom on a middle part of a watch according to one of claims 1 to 6, characterized in that the groove (5) extends along a radius of the bottom (2) and has a depth at least equal to half the height of the pin (4), and a width of dimension similar to the diameter of the body (40) of the pin so that the pin slides within the groove (5). 8. Fastening device (100) according to one of claims 1 to 7, characterized in that the groove (5) comprises a bottom (50), a first and a second end (51, 52), and two walls ( 53), the bottom being in the form of a groove (54) with the dimensions of the head (40) or the foot (42) of the pin so as to guide the pin and hold it axially. 9. Fastening device (100) according to claim 8, characterized in that the first end (51) forms a space for the introduction of the pin (4), and the second end (52) forms a stop and holds the pin in position. 10. Fastening device (100) according to claim 8 or 9, characterized in that the first end (51) has dimensions similar to the head or to the foot of the pin (4), and the second end (52) has dimensions similar to the body (40) of the pawn. 11. Fastening device (100) according to one of claims 8 to 10, characterized in that the bump (55) is formed on one of the two walls (53) of the groove (5). 12. Fastening device (100) according to one of claims 1 to 11, characterized in that the groove (5) comprises several bumps (55), the distance between each bump (55) being identical. 13. Fastening device (100) according to one of claims 1 to 11, characterized in that the groove (5) comprises several bumps (55), the distance between each bump (55) being decreasing. 14. Fastening device (100) according to one of claims 1 to 13, characterized in that the device comprises at least three pins (4) distributed angularly on the bottom and arranged at regular intervals. 15. Timepiece characterized in that it comprises a fixing device (100) according to one of claims 1 to 14.