Method for bonding timepiece components

Abstract

The invention relates to a method for bonding timepiece components, comprising applying an adhesive to a first and/or second timepiece component to be bonded to one another, and depositing an adhesion layer onto at least one of the first and second components to be bonded by spraying a primer composition in a localised joining area followed by the solidification of the primer composition. The adhesion layer is deposited prior to the application of the adhesive if the adhesive is applied to the one or more same components as the adhesion layer.

Claims

1. A method for bonding timepiece components, at least one whereof is coated with epilame, comprising: applying an adhesive to a first and/or second timepiece component to be bonded to one another, depositing an adhesion layer onto at least one of the first and second components to be bonded by spraying a primer composition in a localised joining area of the first or second component, and solidifying the primer composition.

2. The method according to claim 1, wherein said application of the adhesive is followed by the solidification of the primer composition.

3. The method according to claim 1, wherein the adhesion layer is deposited prior to the application of the adhesive if the adhesive is applied to the same component as the adhesion layer.

4. The method according to claim 1, wherein the primer composition is sprayed using a spray nozzle mounted such that it can move on a multi-axis robotic arm in order to change the orientation thereof relative to the first and/or second components on which the adhesion layer is to be formed.

5. The method according to claim 1, wherein the primer composition is sprayed substantially vertically from top to bottom using a spray nozzle, and wherein the first and/or second components on which the adhesion layer is to be formed is/are mounted such that it/they can move on a multi-axis robotic arm in order to change the orientation thereof relative to the spray nozzle.

6. The method according to claim 1, wherein the primer composition comprises a radiation-curable material and wherein the primer composition layer is solidified by exposure to the radiation.

7. The method according to claim 1, wherein the primer composition comprises a thermosetting material and wherein the primer composition layer is solidified by heat treatment.

8. The method according to claim 1, wherein the adhesion layer is deposited on the timepiece component coated with epilame.

9. The method according to claim 1, wherein the adhesive comprises shellac.

10. The method according to claim 1, wherein the adhesive comprises shellac and wherein the adhesion layer has a chemical and/or physical affinity for both shellac and epilame.

11. The method according to claim 1, wherein the adhesive is applied by an adhesive spray nozzle, the spray nozzle being: mounted such that it can move on a multi-axis robotic arm in order to change the orientation thereof relative to the first and/or second components to which the adhesive must be applied; or essentially vertically-oriented from top to bottom, and the first and/or second components to which adhesive must be applied being mounted such that it/they can move on a multi-axis robotic arm in order to change the orientation thereof relative to the adhesive spray nozzle.

12. The method according to claim 1, wherein the adhesion layer is polyurethane-based.

13. The method according to claim 1, wherein the primer composition consists of a single fluid or is a two-component composition mixed in-situ.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) Other features and characteristics of the invention will be better understood upon reading the detailed description of certain advantageous embodiments presented hereinbelow for illustration purposes, with reference to the accompanying drawings which show:

(2) FIG. 1: the diagram of a first embodiment of a bonding method according to the invention;

(3) FIG. 2: the diagram of a second embodiment of a bonding method according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

(4) FIGS. 1 and 2 diagrammatically show embodiments of a bonding method according to the invention. As discussed hereinabove, the method according to the invention can be used to bond the pallet-stones 12, 14 to the pallet-lever 16 of the escapement 10 of a mechanical watch. The figures show a Swiss lever escapement 10. It comprises an escape wheel 18, typically made of quenched, polished steel. The pallet-lever 16 connects the escape wheel to the balance (the figures showing the small roller 20, the large roller 22 and the staff 24) and can switch between two positions at the rate imposed by the balance and balance spring assembly. With each alternation, the escape wheel 18 provides an impulse to the pallet-lever 16, which transfers it to the balance so as to maintain the oscillations thereof. The pallet-stones 12, 14 are typically made of ruby, because of the hardness and low coefficient of friction thereof, and are bonded to the pallet-lever 16 by means of a shellac-based adhesive.

(5) The pallet-stones 12, 14 are fully or partially coated with epilame as required. The invention makes it possible for high-resistance epilames to be used, since the bonding areas on the pallet-stones 12, 14 can be prepared prior to the application of the shellac using an adhesion layer, which adjusts the surface tension so as to satisfactorily allow the surface to be wet by the shellac. The adhesion layer is formed by applying a primer composition by a method for digitally printing directly on the component. In particular, the adhesion layer can be deposited by spraying the primer composition in the form of an ink 26. The amount of ink and the position of each droplet are precisely controlled by a control unit 28 (for example a microprocessor, or a computer, etc.). The control unit 28 in particular adjusts the position and orientation of the component relative to the ink spray nozzle. The possibility of orienting and positioning the spray nozzle 30 relative to the print medium is diagrammatically shown with the reference numeral 32.

(6) The component being printed on could remain stationary during printing. In such a case, the primer composition is sprayed using a spray nozzle 30 mounted such that it can move, for example on a multi-axis robotic arm in order to change the orientation thereof relative to the component, i.e. in the case shown, the pallet-stone 12 or 14 or the pallet-lever 16. Preferably, however, the spray nozzle 30 remains vertically-oriented from top to bottom during printing, and the component is, in such a case, mounted such that it can move, for example on a multi-axis robotic arm, in order to change the orientation thereof relative to the spray nozzle 30.

(7) According to a first alternative embodiment, after deposition on the surface of the component, the primer composition is solidified. According to a second alternative embodiment, the primer composition is solidified after the application of the adhesive onto the first and/or second timepiece components to be bonded to one another. It should be noted that, in these two alternative embodiments, the adhesion layer can be deposited prior to the application of the adhesive if the adhesive is applied to the same component as the adhesion layer. Such solidification of the primer composition contributes to ensuring strong adhesion of the timepiece components bonded to one another.

(8) In both of these alternative embodiments, solidification is carried out as a function of the properties of the primer composition, for example by UV radiation or by electron beam in the case of a radiation-curable material, by heat treatment in the case of a thermosetting material, by laser sintering, or simply by evaporation of the solvent. It should be noted that such evaporation can be natural or forced. The curing method could combine a plurality of these possibilities, for example to accelerate curing.

(9) In addition to the pallet-stones 12, 14, an adhesion layer can also be applied to the pallet-lever 16. The composition of the adhesion layer can be the same as that applied to the pallet-stones 12, 14, provided that the adhesion on the two types of components is strong enough. Alternatively, different adhesion layers can be used on the pallet-lever 16 and on the pallet-stones 12, 14. In this context, these pallet-stones 12, 14 and the pallet-lever 16 thus form a one-piece assembly of timepiece components.

(10) While FIG. 1 diagrammatically shows an embodiment wherein the primer composition consists of a single fluid, FIG. 2 shows the case wherein the primer composition is a two-component composition mixed in situ. In such a case, two reactive fluids 26a and 26b are brought together on the timepiece component in the bonding area.

(11) A further aspect of the invention relates to a one-piece assembly of timepiece components comprising first and second components capable of being connected to one another by such a method. Such a one-piece assembly comprises a joining part that connects the joining areas of the first and second components. This joining part is formed by a layer of adhesive and an adhesion layer, in particular a primer composition layer. In this one-piece assembly: the first timepiece component is an escapement lever and the second timepiece component is a lever pallet-stone; the first timepiece component is a balance stud and the second timepiece component is a balance spring; the first timepiece component is a wheel plate and the second timepiece component is a staff; the first timepiece component is an index block and the second timepiece component is a dial.

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

(13) Although specific embodiments have been described in detail, a person skilled in the art will know that various modifications and alternatives to the above can be developed in light of the general teachings of the present disclosure of the invention. As a result, the specific arrangements and/or methods described herein are intended for illustration purposes only and are not intended to limit the scope of the invention, which is determined by the scope of the accompanying claims.