CH709401B1 - Timepiece provided with a dial and associated fastening method. - Google Patents

Abstract

Timepiece comprising a case (2) in which is housed a plate of a movement surmounted by a dial (6), a support being provided on an upper face of the plate for mounting the dial, characterized in that the dial (6) is assembled to the plate using at least one flexible fixing element (61) of the dial arranged in the plane of the dial (6).

Description

The present invention relates to a dial provided with particular fasteners and a method of fixing such a dial in a watch case.

TECHNOLOGICAL BACKGROUND

In the field of watchmaking, there are different methods of fixing dials to the movement of a watch. The most classic used in fine watchmaking consists in using feet, assembled at the periphery of the movement for example by welding or gluing, and which are then driven into orifices arranged in the movement plate for this purpose. The drawback of such a method is that it requires very high machining precision for the placement of the dial on the movement, as well as its angular positioning; moreover, the driving-in operation is tedious and consequently considerably slows down the rate of assembly.

For lower range watches, for example for quartz movements whose movement plate is made of plastic, it is customary to temporarily fix the dial to the movement using a crimping ring before housing the 'assembly thus formed in the housing; the final fixing is then ensured by the subsequent assembly of other parts, such as for example an annular part partially covering the periphery of the dial. During this intermediate assembly operation, the crimping ring is plastically deformed in order to pinch the periphery of the dial and thus hold it against the upper face of the plate. A drawback of this fixing method is that it is unsuitable for dials made of a relatively flexible material, which can then bulge. Furthermore, to prevent any inadvertent slipping or ejection of the dial during subsequent assembly operations, it is often necessary to apply a point of glue to ensure that this temporary fixing is improved.

The installation of a point of glue is however disadvantageous in aesthetic terms, because the point of glue is sometimes visible; it can also result in harmful gas emissions during drying. In addition, this gluing operation also requires the use of an additional station on the assembly line, or even possibly an additional machine, which is on the one hand expensive and on the other hand considerably reduces the production rates. production.

[0005] There is therefore a need for solutions for mounting a dial in a housing free from these known limitations.

SUMMARY OF THE INVENTION

To this end, the present invention relates to a timepiece comprising a case in which is housed a plate of a movement surmounted by a dial, a support being provided on an upper face of said plate for mounting the dial, characterized in that the dial is assembled to the plate using at least one flexible fixing element of the dial arranged in the plane of the dial.

[0007] The present invention also relates to an assembly process for such a timepiece comprising a case, a plate of a movement and a dial, characterized in that it comprises a first step of mounting the dial on a support arranged on an upper face of the plate with the aid of at least one flexible fixing element of the dial arranged in the plane of the dial, a second step of introducing the plate - dial assembly thus formed into the case, followed by a third step of locking the dial resting against the support of the plate using a locking element.

Finally, the present invention also relates to a dial and a plate for the claimed timepiece, each taken separately according to a preferred embodiment, namely: a dial characterized in that it comprises at least one flexible fixing tongue extending in the plane of the dial, and a movement plate provided with a support on its upper face, characterized in that it contains at least one fixing stud oriented in a direction perpendicular to the plane in which the support extends.

An advantage of the solution proposed in the context of the present invention is to allow easier and faster mounting of the dial to the plate, without requiring an additional station on an assembly line for the axial locking of the dial on the platinum, that is to say to ensure that it is kept resting on its support.

Another advantage of the proposed solution is to avoid any undue deformation of the dial during assembly, in particular for plastic dials, and more particularly still for plastic dials.

BRIEF DESCRIPTION OF THE FIGURES

Other characteristics and advantages of the invention will emerge more clearly from the detailed description and from the drawings, given by way of example and with a non-limiting vocation, in which: FIGS. 1A and 1B show respectively top and sectional views of a dial assembled according to a method of the prior art with a crimping ring, the ring not yet being deformed in FIG. 1A and deformed in FIG. Figure 1B; FIG. 2 shows a top view of a dial assembled according to a preferred embodiment of the invention; FIG. 3 shows a timepiece in the complete assembled position, after mounting the crystal; FIGS. 4A and 4B show two preferred embodiments of dials used to implement the assembly solution of the present invention.

DETAILED DESCRIPTION

In what follows we first describe a solution for fixing a dial known from the prior art using a crimping ring using Figures 1A and 1B to then better explain the differences and advantages of the solution proposed in the context of the present invention with respect to this assembly method.

In Figure 1A, there is a movement plate 3 on the upper face of which is affixed a dial 6, which is crossed at its center by a barrel 9 of the seconds hand 91, of the hand of minutes 92, and the hour hand 93, which extends along an axis AA perpendicular to the plane of the dial 6. On the periphery of the dial are arranged a series of parts arranged along a ring extending around the perimeter of the dial disc 6, and commonly referred to as the crimping ring 330 of dial 6.

Figure 1B, which shows a sectional view along the axis BB visible in Figure 1A passing through the crimping ring 330, explains how the dial 6 is held pressed against the plate 3. Once the dial 6 has been affixed to its support 30, arranged on the upper face of the plate, the crimping ring 330 is deformed inwards thanks to the application of a deformation torque D, illustrated by the arrow pointing towards the center of the dial 6, for example using pliers, so that it comes to rest against the edge 60 of the dial 6 at the level of the edge 67. In FIG. 1B, its end even slightly covers the face upper 68 of the dial. The dial 6 is thus certainly held against its support 30, but the folding of the crimping ring 330 simultaneously at the level of two diametrically opposed edges 60 of the dial 6 also tends to deform the latter, because the pinching of the edges 67 exerts a torque. of torsion which may result in a slight bulging of the dial 6. Depending on the hardness of the material used for the dial 6, the center of the latter then rises more or less from its support 30.

In order to overcome this drawback, the proposed solution no longer uses the crimping ring 330, and instead offers flexible fixing elements which no longer exert any torsional stress on it. To this end, according to the preferred embodiment illustrated by FIG. 2, showing a dial 6 - movement plate 3 assembly inserted into the case 2 of a wristwatch provided with a control rod 7, the dial 6 is provided with integrated flexible fasteners, preferably in the form of tabs 61 made of the same material as the dial 6 itself, in order to limit the costs of machining these fasteners. Thus, depending on requirements, these tabs 61 can be made of metal or plastic. For fixing to the plate 3, these tabs 61, which are also arranged in the plane of the dial 6 to facilitate their machining and limit the vertical bulk in the housing 2, cooperate with fixed elements of the plate, formed here by studs 31 extending vertically along the axis of the axis AA of the barrel 9 of the hands (that is to say the seconds 91, minutes 92 and hours 93) hand.

The dial 6, which can also be seen a window 65 for displaying the date, is thus preferably affixed vertically on a support arranged on the upper face of the plate 3 in the direction of the axis AA of the barrel until it comes into abutment on a bearing surface of the support 30 (not shown in FIG. 2 but visible in FIG. 3 in section detailed below). The positioning of the dial 6 on the support is facilitated by the peripheral stop elements 33 extending along a peripheral ring of the dial 6; the latter also make it possible to recover machining tolerances between the barrel 9 of the movement hands and the central orifice 65 of the dial 6, the latter being introduced.

When placing the dial 6 on the support 30 of the plate 3, each of the fixing tabs 61, none of which here protrudes radially from the periphery of the dial 6, engages around a stud 31 of corresponding fixing arranged on the support 30 of the plate 3 by automatically deforming slightly outwardly, without requiring external intervention. The stud 31 then slides into the groove 62 arranged between the body of the dial and the tongue 61, and remains gripped by the tongue 61 which exerts a restoring force towards the inside of the dial 6. The frictional forces exerted between the stud 3 , the body of the dial 6 and the tongue 61 then make it possible to jointly prevent any rotational movement of the dial relative to the plate 3 as well as any vertical movement along the axis AA of the barrel 9. In this way, not only the tongues 61 are arranged in the plane of the dial 6 at rest, but they deform to pinch the studs 31 also while always remaining in this same plane, which considerably facilitates the assembly operation.

In order to more effectively prevent the angular locking of the position of the dial 6 relative to the plate 3, a foolproof type system is provided between these two parts; for this purpose, an internal radial protuberance 32 is provided on the plate to fit into a notch 64 of the dial. According to a variant, this angular locking could be achieved by means of an assembly device of the bayonet type, by inserting the fixing stud 31 up to the stop at the bottom 620 of the groove 62. The angular locking would in this case however be ensured. only thanks to frictional forces and would require, in the case of the use of a plurality of fixing tongues 61 - and therefore associated grooves 62 - and of studs 31, more precise machining to ensure the consistency of each of the angular positions relative to the abutting positioning of a fixing pad 31 against the bottom 620 of a corresponding groove.

An advantage of this proposed solution for fixing the dial 6 to the plate 3 is, in addition to no longer deforming the dial 6, no longer requiring an assembly station dedicated to locking the degrees of freedom, even temporarily , of the dial 6 with respect to the plate 3. In fact, thanks to the fact that the dial is introduced along the axis AA on the plate 3 to be affixed to the support 30, and that the tongues 61 are arranged in the plane of the dial 6, or perpendicular to the axis AA, the mounting of the dial 6 on the support 30 automatically causes the deformation of the flexible tongues 61 around the fixing pads 31, oriented along this same axis AA, that is to say according to a direction perpendicular to the dial 6 and to the plane in which the bearing surface of the support 30 extends. Thus, these tabs do not need to be handled specifically by a dedicated machine or by an external operator to ensure their locking function, which confers e additional productivity gains.

However, given that the locking of the degree of freedom along the axis AA is only ensured by means of frictional forces, this solution for mounting the dial 6 on the plate 3 will preferably be completed by a step of subsequent locking of the dial resting against the support 30 of the plate.

Figure 2 shows the dial 6 assembled to the plate 3 according to a preferred embodiment using flexible tongues 61 arranged in the plane of the dial 6 and extending in a tangential direction at its periphery, after their step mutual assembly, and their introduction into the housing 2, but before the assembly of the lens 5. After this first mutual assembly step and this second step of introduction into the housing, according to one embodiment, Preferential assembly, a third step of locking the dial 6 resting against the support 30 using a locking element preferably constituted precisely by the crystal 5 of the timepiece, closing the case by coming resting against a bearing 21 of the middle part.

Figure 3 shows a sectional view of a timepiece 1 in fully assembled position, showing the locking according to the vertical degree of freedom of the dial 6 along the axis AA of the barrel 9 of the hands relative to to the plate 3. According to a preferred embodiment, the timepiece was assembled first of all by mounting the dial 6 on the support 30 arranged on the upper surface of the plate, the support 30 here having the shape of 'an annular bearing surface of a first width "L". Thus, only an annular peripheral edge 63 of the dial, of a corresponding width, rests on this support 30. Once the dial 6 has been assembled to the plate 3, the hands (namely the hour hand 93, the minute hand 92 and seconds 91) can be mounted on the barrel 9 above the dial 6. The plate 3 - dial 6 assembly is then introduced into the case 2, which is formed here of a one-piece case back, the back of the case 4 being formed integrally with the middle part 20, for example by driving the net of the movement 34 against an internal shoulder of the middle part 20. It then remains to fit the crystal 5 - bezel 8 assembly, preferably assembled first, to the caseband 20.

As illustrated in FIG. 2 above, the caseband 20 preferably comprises a bearing surface 21 for the crystal 5, against which the heel 51 of the crystal bears. The crystal 5 is then preferably heat-sealed to the caseband 20 at the heat-sealing zones 22, illustrated by small nozzles at the level of the outer periphery of the heel 51. During this step of heat-sealing the crystal 5 to the caseband 20 of the housing 2, a portion 52 of the heel 51 of the crystal 5 bears against the upper surface of the peripheral edge 63 of the dial 6 which is thus sandwiched between this portion 52 of the heel 51 and the annular bearing surface of the support 30 , thus definitively preventing any movement of the dial 6 along the axis AA. This embodiment is thus particularly advantageous because it does not require any dedicated operation for the axial locking of the dial 6, which is carried out jointly with the mounting of the crystal 5 to the middle part 20 of the case 2. Furthermore, it will be noted that according to this preferred embodiment the portion 52 of the heel 51 of the lens 5 has a second width "I" equal to the first width "L" of the annular bearing surface of the support 30, so that the torsional stresses are optimized for the dial 6 in the event of deformation of the case 2 or of the crystal 5 under high pressure constraints, in particular during a very deep underwater immersion, for example from a depth greater than 100 meters, and this in particular if the housing 2 is made of plastic, which is more plastically deformable than metal.

Figure 4A shows a dial 6 preferably made of plastic and used according to the preferred embodiment of the attachment illustrated in Figure 2, comprising a central opening 66 to pass the barrel of the needles and conventionally a window 65. According to this preferred embodiment, the flexible fastening elements are integrated tongues 61 arranged at the periphery of the dial 6, without however going beyond the periphery thereof, in the immediate vicinity of which grooves 62 are arranged for the introduction of the studs. 31 for fixing integral with the plate 3. Each groove 62 has a bottom 620 which acts as a stop surface, opens onto an opening 621 which allows the fixing studs 31 to be introduced under the tongue 61, that is to say. ie between the body of the dial 6 and the tongue 61. Although according to this preferred embodiment, a notch 64 is provided for the angular locking of the dial 6, one could also Also plan to affix the dial 6 on its support 30, then lock it in rotation by turning the dial anti-clockwise S until the studs 31 come into abutment against the bottoms 620 of the grooves 62. The number of tongues, here equal to 3, makes it possible to increase the frictional forces between the fixing pads 31 and the tongues 61, and thus to maximize the locking force without requiring a very high height. the dial 6, materialized by the thickness of the edge 60.

However, according to an alternative embodiment, one can however only use two flexible fixing tongues 61, but arranged not in a direction tangential to the periphery of the dial 6, but in a radial direction. Such an embodiment for the dial is illustrated by FIG. 4B, where one distinguishes a dial 6 comprising the same basic elements as the dial 6 of FIG. 4A, namely a central opening 66 for the passage of the barrel 9 , as well as a window 65 and a notch 64 for the angular locking of the position of the dial 6. The tongues 61 are in the form of two radial studs, separated by a slot corresponding to the groove 62 of the embodiment of the figure 4A. This slot thus also ends in a bottom 620 forming a radial stop and also opens onto an opening 621 allowing the introduction of the fixing stud 31 between the two tongues 61, the deformation of which exerts a return force which takes the latter in pincers. and guarantees its maintenance by friction. The advantage of this solution is to better guarantee the angular locking of the dial 6 thanks to the presence of elements whose radial orientation does not structurally allow any rotational movement, and thus has a form of double security with respect to the keying system. formed by the notch 64 in the dial 6 and the internal radial protuberance 32 at the level of the plate 3; nevertheless, the friction surfaces are more limited due to the small number of tongues 61, with equal wafer thickness 60. The deformation of each tongue 61 is carried out, however, as for the other preferred embodiment described above with reference to FIG. 4A, still only in the plane of the dial, which makes the assembly operation particularly easy and intuitive to use. to achieve.

A person skilled in the art will understand that other arrangements of the fixing elements of the "male" and "female" type for fixing are also possible, the flexible tabs 61 making it possible here to form fixing elements of the "female" type. “, That is to say the grooves 62 in which are inserted the fixing studs 31 - of the„ male “type - but these fixing elements could also be inverted between the plate 3 and the dial 6. It will be understood moreover that the fixing solution also applies to dials 6 provided with digital display modules of the LCD type, and not exclusively to analog displays for needle movements.

Claims (12)

1. Timepiece (1) comprising a case (2) in which is housed a plate (3) of a movement surmounted by a dial (6), a support (30) being provided on an upper face of said. plate (3) for mounting said dial (6), characterized in that said dial (6) is assembled to said plate (3) using at least one flexible fixing element of the dial (6) arranged in the plane of said dial (6). 2. Timepiece according to claim 1, characterized in that said flexible fixing element is a tongue (61) which cooperates with a stud (31) for fixing. 3. Timepiece according to claim 1 or 2, characterized in that said dial (6) and said support (30) further comprise angular locking means for the angular position of said dial (6) on said support (30). ). 4. Timepiece according to one of the preceding claims, characterized in that said support (30) of said dial (6) comprises an annular bearing surface and peripheral stops (32) for positioning said dial (6) resting on said support (3). 5. Timepiece according to one of the preceding claims, characterized in that it further comprises additional locking means for maintaining said dial (6) in abutment against said support (3). 6. Timepiece according to claim 5, said additional locking means being constituted by the heel (51) of a watch crystal (5). 7. Timepiece according to one of the preceding claims, characterized in that said dial (6) and said plate (3) have a bayonet assembly device comprising said flexible fixing element. 8. Assembly method for a timepiece (2) according to one of claims 1 to 7 comprising a housing (2), a plate (3) of a movement and a dial (6), characterized in that that it comprises a first step of mounting said dial (6) on a support (30) disposed on an upper face of said plate (3) using at least one flexible fixing element of the dial, arranged in the plane of said dial (6), a second step of inserting the plate (3) - dial (6) assembly thus formed in said housing (2), followed by a third step of locking said dial (6) in support against said support (30) of said plate (3) using a locking element. 9. Assembly method according to claim 8, characterized in that said third locking step is carried out jointly with the mounting of the lens (5) to said housing (2), at least a portion of the heel (51) of said lens coming from bearing against a peripheral annular portion (63) of said dial (6). 10. Dial (6) for a timepiece according to one of claims 1 to 7, characterized in that it comprises at least one flexible fixing tongue (61) extending in the plane of said dial, the tongue (61) forming said flexible fastening element. 11. Dial (6) according to claim 10, characterized in that it further comprises a notch (64) for the angular locking of the position of said dial on said support (30). 12. Movement plate (3) for a timepiece according to one of claims 2 to 7, said plate (3) being provided with a support (30) on its upper face, characterized in that it comprises at least one said fixing stud (31) oriented in a direction perpendicular to the plane in which said support (30) extends.