CH716550A2 - Process for bonding watch components. - Google Patents

Abstract

The invention relates to a method for bonding watch components, comprising the application of an adhesive to a first (12, 14) and/or a second (16) watch component to be bonded one on the other and the formation of a bonding layer on at least one of the first and second components to be bonded by spraying a primer composition into a localized bonding zone, followed by the solidification of the primer composition. The formation of the tie layer is carried out before the application of the glue if the glue is applied to the same component as the tie layer.

Description

Description

Technical area

[0001] The present invention relates to the field of watchmaking and relates more particularly to a process for gluing watchmaking components aimed at forming a one-piece assembly of watchmaking components.

Technological background

In the field of watchmaking, some watch components can be assembled together by means of an adhesive (liquid adhesive at the time of its application).

[0003] By way of example, in a lever escapement of a mechanical watch, palettes (or „raises, generally made of rubies) are fixed to the anchor by gluing, typically by means of a dissolved shellac in an alcohol solvent. Shellac is a natural thermofusible resin, i.e. it is smooth at temperatures above its melting temperature (Tm) and solid below its melting temperature (Tm) or its glass transition temperature (Tg). Depending on the anchor's manufacturing process, it is possible that the result of the bonding does not comply with the requirements, either because the mechanical strength of the blade is insufficient, or because the aesthetics of the drop is compromised. - outside the specifications. In both cases, the cause of the nonconformity is often a surface tension problem.

[0004] Shellac is secreted by the female Cochineal in the forests of Southeast Asia. The composition of the lacquer strongly depends on the diet of the mealybugs and the season of harvest. The material collected is purified and processed, but the purity and composition obtained are never guaranteed. It is therefore very difficult, if not impossible, to guarantee the constant performance of this natural product over time.

[0005] On the other hand, the industrial processes are not robust enough to guarantee cleanliness of the body of the anchor and therefore an always identical surface tension. There may be various physical or chemical pollutions, such as particles, adsorption of water or other substances, which all modify the reaction of the surface during the deposition of the shellac.

[0006] The paddles are completely or partially epilamed as needed. An epilame is a product that modifies in one way or another the surface tension of the support. It generally comes in the form of an invisible hydrophobic and oleophobic molecular layer, and is deposited in order to prevent the spreading of a lubricant or its components. The epilame hooks the lubricant so that it stays in place or it pushes it back to keep it in well-defined areas. Thanks to epilaming, the surface tension is supposed to be controlled. However, it is noted that during the epilaming process, recourse is regularly had to component cleaning operations after potentially dirty manufacturing steps. Such cleanings can at least partially degrade the epilame effect, which causes fluctuations in the surface properties to the detriment of the sticking of the pallets. Conversely, it is possible to use resistant epilames. These, however, lead to surface tensions which are incompatible with the wetting of the surface by the shellac. In this case, it is impossible to glue the paddle since the shellac will tend to leak from the epilame surface.

[0007] Another example of watch components assembled by gluing is at the level of the balance wheel and more specifically concerns the balance spring glued to its peak.

[0008] An object of the present invention consists in proposing a preparation of a watch component for bonding.

General description of the invention

[0009] One aspect of the invention relates to a method for bonding watch components, comprising the application of an adhesive to a first and/or a second watch component to be bonded one to the other and the formation of a layer bonding agent (primer, adhesion primer) on at least one of the first and second components to be bonded by spraying a primer composition into/onto a bonding zone located on a portion of one face of each of these first and second components. The glue is thus applied so as to form a layer of glue. Gelte application of the glue, or else the formation of this layer of glue, is then followed by the solidification of the primer composition. It will be noted that the bonding zone can be called the bonding zone. The formation of the tack coat is carried out before the application of the adhesive if the adhesive is applied to the same component(s) as the tack coat and, if necessary, before setting contact the first and second timepiece components.

The invention proposes in particular to deposit the bonding layer by spraying. This can be done, for example, by means of Aerosol Jet technology (trademark of the company Optomec) or by any other digital printing technology. These technologies now allow the deposition of fluid materials in a very precise manner, both in terms of volume and location. They can be adapted to watch components, as indicated in patent applications WO 2016/203063 and EP1172714. The present invention exploits in particular the precision potential of this deposition technology to prepare watch components for bonding. The fact of resorting to a bonding layer deposited by digital printing makes it possible to provide the components with a precisely delimited bonding zone and

with surface tension adapted to the glue. This makes possible the use of more resistant epilames which are not or only slightly wettable by the glue that one wishes to use.

[0011] Preferably, the spraying of the fluid primer composition is carried out by a spraying nozzle mounted mobile on a multi-axis robot arm to change its orientation with respect to the first and/or second component on which the bonding layer must to be formed. Alternatively, the spraying of the primer composition can be carried out essentially vertically from top to bottom by a spray nozzle, the first and/or second component on which the bonding layer is to be formed being in this case movably mounted. on a multi-axis robot arm to change its Orientation relative to the projection nozzle. This second possibility has the advantage that the jet can remain vertical, which could facilitate precise delimitation of the bonding layer.

[0012] The primer composition may comprise a material curable by radiation (ultraviolet and/or electron beam) and in this case the solidification of the primer composition layer is effected by exposure to radiation.

[0013] The primer composition may also comprise a thermosetting material in which case the solidification of the primer composition layer is carried out by heat treatment.

[0014] The primer composition may be in the form of an ink comprising the primer composition dissolved or suspended in a solvent. The primer composition could also be in the form of a polymeric resin (with or without mineral fillers) comprising reactive diluents instead of volatile solvents.

[0015] According to one embodiment of the invention, at least one of the first and second timepiece components to be bonded one to the other is epilame. The bonding layer can be formed on the epilame timepiece component.

[0016] The glue could comprise shellac. Alternatively, the glue could comprise epoxy glue.

[0017] According to a specific embodiment, it is a question of bonding Tun to each other of the watch components, of which at least Tun is epilame by means of an adhesive comprising shellac. In this case, the tie layer preferably has a chemical and/or physical affinity both for shellac and for epilame. It is noted that the two watch components could be epilames.

[0018] It is noted that the glue could be applied using the same technology as the tie layer. More precisely, the glue could be applied by a glue projection nozzle, the projection nozzle being:

- mobile mounted on a multi-axis robot arm to change its orientation relative to the first and/or second component on which the glue is to be applied; Or

- substantially vertically from top to bottom, and the first and/or second component to which glue is to be applied being movably mounted on a multi-axis robot arm to change its orientation with respect to the glue spray nozzle.

[0019] It will be noted that various timepiece components can be glued together thanks to the present invention. For example :

- the first horological component can be an escapement anchor and the second horological component an anchor pallet,

- the first watch component can be a balance pin and the second watch component a balance hairspring,

- the first horological component can be a mobile plate and the second horological component an axis, e.g. a metal axis,

- The first timepiece component can be an index stud and the second timepiece component a dial.

[0020] The list of components that could be bonded is not exhaustive. The invention can be used to improve the bonding of timepiece components which are currently already fixed one to the other by bonding (as in the case of the anchor and its pallets). The invention could, however, be useful for allowing the bonding of timepiece components which are currently fixed by other means (eg by clamping or riveting). One thinks in particular of a mobile board of fragile design (due to its low thickness and/or the fact of being made of a fragile material such as, for example, silicon) on a metal axis (for example. in steel). The bonding of these horological components would make it possible to avoid or at least reduce the deformation or the breakage of the plate due to riveting or hunting while guaranteeing the cohesion between the plate and its axis during the stresses which are applied to them.

[0021] The tie layer could be based on polymer(s), eg polyurethane, acrylates or even epoxies. Note that for noble metals, certain products containing thiols can be used. It is understood that the person skilled in the art will choose the composition of the primer according to the nature of the watchmaking components, respectively of the glue. It is noted that in the case of a primer composition based on polymers, polymers which undergo (irreversible) crosslinking are preferred. On the other hand, as far as the glue is concerned, for the bonding of certain components, a thermosetting glue is preferable, whereas in other cases thermoplastic glue is used.

The various aspects of the invention make it possible to improve the bonding of watch components, to reduce the impact of dirt, to use more resistant epilames and/or to facilitate the application of the glue in the compliance with drop quality criteria (position, quantity).

[0023] Another aspect of the invention relates to a one-piece assembly of timepiece components comprising first and second components capable of being connected to each other using such a bonding process.

[0024] In other embodiments:

- The one-piece assembly comprises a connecting part connecting connecting zones of the first and second components;

- the connecting part is formed by a layer of adhesive and a bonding layer, in particular a layer of primer composition;

- the first horological component is an escapement lever and the second horological component is an anchor pallet;

- the first watch component is a balance stud and the second watch component is a spiral spring;

- the first horological component is a mobile board and the second horological component is an axle, and

- the first timepiece component is an index pad and the second timepiece component is a dial.

Another aspect of the invention relates to a timepiece comprising such a one-piece assembly of timepiece components.

Brief description of the drawings

Other particularities and characteristics of the invention will emerge from the detailed description of certain advantageous embodiments presented below, by way of illustration, with reference to the appended drawings which show:

Fig. 1: the diagram of a first embodiment of a bonding process according to the invention;

Fig. 2: the diagram of a second embodiment of a bonding process according to the invention.

Detailed description of embodiments of the invention

Figures 1 and 2 illustrate, schematically, embodiments of a bonding process according to the invention. As discussed above, the method according to the invention can be used to glue the pallets 12, 14 to the lever 16 of the escapement 10 of a mechanical watch. The figures show a Swiss lever escapement 10. It includes an escape wheel 18, typically made of hardened and polished steel. The lever 16 connects the escapement wheel to the balance wheel (the figures of which show the small plate 20, the large plate 22 and Tax 24) and can switch between two positions at the rhythm imposed by the balance and hairspring assembly. At each alternation, the escape wheel 18 gives an impulse to the lever 16, which transfers it to the balance wheel so as to maintain the oscillations of the latter. Pallets 12, 14 are typically made of ruby, because of its hardness and low coefficient of friction, bonded to anchor 16 with a shellac based glue.

The pallets 12, 14 are completely or partially epilamees as needed. Thanks to the invention, it is possible to use resistant epilames, since the bonding areas on the pallets 12, 14 can be prepared before the application of the shellac with the aid of a bonding layer. , which adjusts the surface tension so as to satisfactorily allow wetting of the surface by the shellac. The bond coat is formed by applying a primer composition by a direct digital printing process to the component. In particular, the bonding layer can be deposited by spraying the primer composition in the form of ink 26. The quantity of ink and the position of each droplet are precisely controlled by a control unit 28 (e.g. a microprocessor , a computer, etc.) The control unit 28 regulates in particular the position and the orientation of the component with respect to the ink projection nozzle. The possibility of orienting and positioning the projection nozzle 30 relative to the printing medium is schematically indicated at reference number 32.

[0029] The component on which it is printed could remain stationary during printing. In this case, the spraying of the primer composition is effected by a spray nozzle 30 movably mounted, e.g., on a multi-axis robot arm to change its orientation relative to the component, i.e., in the case illustrates, the pallet 12 or 14 or the anchor 16. Preferably, the projection nozzle 30 remains oriented vertically from top to bottom during printing, and the component is in this case mounted mobile, eg on a multi-axis robot arm, to change its orientation with respect to the projection nozzle 30.

[0030] After deposition on the surface of the component, the primer composition is solidified. This must be done according to the properties of the primer composition, e.g. by UV radiation or by electron beam in the case of radiation hardenable material, by heat treatment in the case of thermohardenable material, by laser sintering "), or simply by evaporation of the solvent. It should be noted that such evaporation can be natural or forced. The hardening method could combine several of these possibilities, e.g. to accelerate the hardening.

Claims (17)

[0031] In addition to the vanes 12, 14, a tie layer can also be applied to the anchor 16. The composition of the tie layer may be the same as that which is applied to the vanes 12, 14, to provided that the adhesion to the two types of components is strong enough. Alternatively, different bonding layers will be used on the anchor 16 and the pallets 12, 14. In this context, these pallets 12, 14 and the anchor 16 then form a one-piece assembly of watch components. While Figure 1 schematically shows a mode in which the primer composition consists of a single fluid, Figure 2 illustrates the case where the primer composition is two-component type mixed in situ. In this case, two reactive fluids 26a and 26b are combined on the watch component in the bonding zone. Another aspect of the invention relates to a one-piece assembly of timepiece components comprising first and second components capable of being connected to each other using such a process. Such a one-piece assembly comprises a connecting part connecting connecting zones of the first and second components. This connecting part is formed by a layer of adhesive and a bonding layer, in particular a layer of primer composition. In this one-piece set: - the first horological component is an escapement lever and the second horological component is an anchor pallet; - the first watch component is a balance stud and the second watch component is a spiral spring; - the first clock component is a mobile plate and the second clock component is an axis; - the first timepiece component is an index pad and the second timepiece component is a dial. Another aspect of the invention relates to a timepiece comprising such a one-piece assembly of timepiece components. [0035] While particular embodiments have just been described in detail, those skilled in the art will appreciate that various modifications and alternatives thereto may be developed in light of the overall teaching provided by this disclosure of the 'invention. Accordingly, the specific arrangements and/or methods described herein are intended to be illustrative only, without the intention of limiting the scope of the invention, which is determined by the scope of the appended claims. Claims 1. Process for bonding watch components, comprising the application of an adhesive to a first and/or a second watch component to be bonded one to the other, characterized by the formation of a bonding layer on at least one first and second components to be bonded by spraying a primer composition into a localized bonding area of the first or second component, said application being followed by the solidification of the primer composition, the formation of the bonding layer being carried out before the application of the adhesive if the adhesive is applied on the same component as the adhesion layer. 2. Method according to claim 1, characterized in that the projection of the primer composition is carried out by a projection nozzle mounted mobile on a multi-axis robot arm to change its orientation relative to the first and / or second component on which the adhesion layer must be formed. 3. Method according to claim 1, characterized in that the spraying of the primer composition is carried out essentially vertically from top to bottom by a spray nozzle, and in which the first and/or second components on which the layer of The attachment must be formed is movably mounted on a multi-axis robot arm to change its orientation relative to the spray nozzle. 4. Process according to any one of claims 1 to 3, characterized in that the primer composition comprises a radiation curable material and in which the solidification of the layer of primer composition is effected by exposure to radiation. 5. Process according to any one of claims 1 to 4, characterized in that the primer composition comprises a thermosetting material and in which the solidification of the layer of primer composition is carried out by heat treatment. 6. Process according to any one of claims 1 to 5, characterized in that at least one of the first and second timepiece components to be bonded one to the other is epilame. 7. Method according to claim 6, characterized in that the bonding layer is formed on the epilame watch component. 8. Process according to any one of claims 1 to 7, characterized in that the glue comprises shellac. 9. Process according to claim 7, characterized in that the adhesive comprises shellac and in which the bonding layer has a chemical and/or physical affinity for both shellac and epilame. 10. Process according to any one of claims 1 to 9, characterized in that the glue is applied by a glue projection nozzle, the projection nozzle being: i. movable mounted on a multi-axis robot arm to change its orientation relative to the first and/or second component on which the glue is to be applied; Or ii. substantially vertically from top to bottom, and the first and/or second component to which glue is to be applied being movably mounted on a multi-axis robot arm to change its orientation relative to the glue spray nozzle. 11. Process according to any one of claims 1 to 14, characterized in that the bonding layer is based on polymer(s), eg polyurethane. 12. Process according to any one of the preceding claims, characterized in that the primer composition consists of a single fluid or is of the two-component type mixed in situ. 13. One-piece assembly of timepiece components comprising first and second components capable of being connected to one another using a bonding process according to any one of the preceding claims. 14. One-piece assembly of timepiece components according to the preceding claim, characterized in that it comprises a connecting part connecting connecting zones of the first and second components. 15. One-piece assembly of watch components according to the preceding claim, characterized in that the connecting part is formed of a layer of adhesive and a bonding layer, in particular a layer of primer composition. 16. One-piece assembly of watch components according to any one of claims 12 to 14, characterized in that: - the first horological component is an escapement anchor and the second horological component is an anchor pallet; - the first watch component is a balance stud and the second watch component is a spiral spring; - the first clock component is a mobile plate and the second clock component is an axis; - the first horological component is an index pad and the second horological component is a dial 17. Timepiece comprising a one-piece assembly of timepiece components according to any one of claims 12 to 15.