Device for separating a wound hairspring after an expansion cycle and method for manufacturing a hairspring including a separation step performed by such a device

Abstract

To provide a device for separating an assembly of balance springs which have been wound in and undergone an expansion cycle.SOLUTION: A device 100 for separating an assembly 10 of balance springs 12 that have been wound in and undergone an expansion cycle is provided, the device 100 comprising a support 110 having notches 113 intended to receive inner strands of the wound balance springs 12 making up the assembly, and a vibrating table 120 configured to define a vibration plane and to be movable along two different axes extending in the same plane, the vibrating table 120 also being configured to cause the support 110 to vibrate in a plane parallel to the vibration plane.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a hairspring intended to be fitted to the balance or balance of a timepiece movement, and to a method for manufacturing such a hairspring.

[0002] The present invention relates to a device for separating a hairspring, for facilitating the step of separating the hairspring after heat treatment in a method for manufacturing a hairspring.

[0003] The invention further relates to a method for manufacturing a balance spring intended to be equipped in the balance of a timepiece movement. [Background technology]

[0004] The manufacture of watch balance springs is subject to the following seemingly contradictory constraints: The need for high yield strength, Ease of manufacturing, specifically ease of wire drawing and roller rolling; Excellent fatigue strength, Stable performance levels over time, Small cross section is.

[0005] Furthermore, balance spring manufacturing places a greater emphasis on thermal compensation to ensure stable chronometric performance, which requires a thermoelastic coefficient close to zero, as well as a balance spring with limited sensitivity to magnetic fields.

[0006] Thus, any improvement in at least one of these respects, in particular limited sensitivity to magnetic fields, thermal compensation, and ease of manufacture, especially for the drawing, wire stretching and rolling operations, would represent a significant advance.

[0007] In the hairspring manufacturing cycle, the winding operation consists of winding a rolled wire on a barrel by a winding star or spindle to form an assembly or plate of hairsprings wound in the same plane.

[0008] The assembly typically contains three to six helically wound wires.

[0009] The various windings in the balance spring are then fixed by an expansion cycle, typically heat treatment, to give it its final Archimedes spiral shape and to obtain the desired thermoelastic coefficient (TEC) and increase its hardness. The next step involves separating the various interlocking windings in the balance spring.

[0010] This step can be particularly difficult in the case of compensating balance springs, and even more so in the case of titanium alloy balance springs, as the presence of titanium in the alloy increases the frictional forces between the various balance springs.

[0011] As a result, there is a need to improve this step of separating the balance spring after winding and heat treatment in order to minimize the rejection rate when manufacturing such balance springs, and in particular compensation balance springs. Summary of the Invention

[0012] In this context, the present invention proposes a device for separating an assembly of a hairspring that has been wound and has undergone an expansion cycle, said device comprising: a support including a notch intended to receive the inner strand of the wound balance spring that constitutes the assembly; a vibration table movable along two different axes extending in the same plane, which define a vibration plane P1, and configured to vibrate the support in a plane parallel to the vibration plane P1; Includes:

[0013] Such a device facilitates the separation of multiple assemblies of multiple wound springs after heat treatment, and is particularly useful for compensation balance springs, particularly balance springs made from titanium alloys.

[0014] Preferably, the two vibration axes are perpendicular to each other.

[0015] Oscillating in two directions in the same plane can cause oscillatory movements, particularly in the tangential direction of the balance spring coils.

[0016] By matching the geometry of the multiple coils, such vibrations originate at the center of the assembly and propagate toward the outermost coils of the multiple balance springs, elastically deforming the individual coils of the multiple balance springs.

[0017] In addition to the features mentioned in the preceding paragraph, the device according to the invention may also have one or more of the following complementary features, considered individually or in any technically possible combination: The vibration table vibrates in a circular translational motion; the support comprises a body integral with the vibration table and a spindle integral with said body, said spindle extending perpendicular to said body and to the vibration plane P1 of the vibration table; The notch is formed in the free end of the spindle; The free end of the spindle is conical in shape; the device includes an air ejector that ejects the separated balance spring when the vibration table is vibrated; the device includes a collection tray for receiving the expelled balance spring; the apparatus including a removable cover configured to at least partially cover the free end of the spindle; the removable cover being movable between a closed position that prevents the balance spring from being removed from the support and an open position that allows the wound balance spring assembly to be inserted into the support and allows the balance spring separated from the support to be removed; The removable cover is capable of translational movement along an axis perpendicular to the vibration plane P1 of the vibration table; the removable cover including a recess configured to receive the free end of the spindle when in the closed position; the apparatus includes a motor configured to vibrate the vibration table at a frequency between 1,000 Hz and 12,000 Hz, preferably between 4,000 Hz and 8,000 Hz; The motor is an air motor or a piezoelectric motor; may have

[0018] Another aspect of the invention relates to a method for manufacturing a hairspring intended to be fitted to the balance or balance of a timepiece movement.

[0019] According to the invention, this manufacturing method includes in particular a step of separating the assembly of the hairspring that has been wound and has undergone an expansion cycle, this step being carried out by implementing a separating device according to the invention.

[0020] Preferably, the manufacturing method includes, before the separating step, a winding step consisting of winding a plurality of roller-rolled wires into a barrel by a winding star so as to form an assembly of wound balance springs.

[0021] Preferably, the method of manufacturing includes, after the winding step, an expansion step of the wound balance spring of the assembly to relieve stress within the assembly.

[0022] Preferably, the balance spring is a compensation spring.

[0023] Preferably, the balance spring is made from an alloy of niobium and titanium. [Brief explanation of the drawings]

[0024] The objects, advantages and features of the present invention will be better understood upon reading the detailed description given below in conjunction with the following drawings.

[0025] [Figure 1] 1A and 1B illustrate diagrammatically an exemplary embodiment of a device for separating an assembly of wound balance springs that has undergone an expansion cycle, according to the present invention; [Figure 2] 2 shows diagrammatically the device according to the invention shown in FIG. 1 in a step of closing, causing the wound balance spring assembly to oscillate; [Figure 3] 2 shows diagrammatically the device according to the invention shown in FIG. 1 in the step of ejecting the separated balance spring after oscillation; [Figure 4] FIG. 2 is a top view of the vibration table and supports of the apparatus shown in FIG. 1. [Figure 5] 1 shows a block diagram illustrating the main steps of a method for manufacturing a hairspring intended to be equipped in the balance of a timepiece movement according to the invention; [Figure 6] 1 shows diagrammatically a barrel containing an assembly of multiple wound balance springs fixed by an expansion cycle. [Figure 7] Shown is the balance spring in its final state, intended to be fitted to the balance of a watch movement. DETAILED DESCRIPTION OF THE INVENTION

[0026] In the hairspring manufacturing cycle, the winding operation consists of winding a number of rolled wires into barrel 2 (shown in FIG. 6) by means of a star piece or winding spindle. An assembly or plate is formed consisting of a number of wound wires positioned and wound in the same plane. From this step onwards, the wound wire is considered to be wound on the hairspring, since its shape is definitive and is forced by barrel 2.

[0027] The various wound springs that make up assembly 10 are then fixed by an expansion cycle, typically heat treatment, to achieve the final shape of an Archimedean spiral with a regular pitch.

[0028] FIG. 6 shows diagrammatically an assembly 10 of multiple wound balance springs 12 fixed by an expansion cycle.

[0029] Figure 7 shows the balance spring 12 in its final state, which is intended to be fitted to the balance of a watch movement.

[0030] Typically, the assembly 10 comprises three to six balance springs 12. In the illustrated example, the assembly 10 comprises four balance springs 12.

[0031] The next step involves separating the various wound and thermally fixed balance springs 12 of the assembly 10.

[0032] FIG. 1 shows diagrammatically one exemplary embodiment of a device 100 for separating an assembly 10 consisting of a plurality of wound and thermally secured mainsprings 12.

[0033] The device 100 will be described with reference to FIGS. 1 to 4, which show diagrammatically different states of the device 100 during the operation of separating the balance spring 12.

[0034] The apparatus 100 includes a support 110 configured to receive and hold the assembly 10 during the separation operation.

[0035] Specifically, support 110 includes a base or body 111 and a spindle 112 that extends perpendicular to the general plane defined by body 111 .

[0036] The spindle 112 has a plurality of notches 113 at its free end. Preferably, the number of notches is equal to or greater than the number of turns of the coil spring that make up the assembly 10. That is, in the illustrated exemplary embodiment, the spindle 112 includes four notches 113 evenly distributed around the circumference of the spindle 112.

[0037] Preferably, the free end that at least partially carries the notch 113 has a conical profile to facilitate positioning of the assembly 10 or removal of the individual, separated balance springs 12 .

[0038] The notches 113 are configured to receive the inner strands 13 of the wound balance springs 12 and are configured to hold the assembly 10 at a predetermined distance from the body 111. That is, the various wound balance springs 12 of the assembly 10 are held in the device 100 only by the inner strands that form the inner ends of the wound balance springs 12. The various coils of the wound balance springs 12 are suspended above the body 111 of the support 110.

[0039] The apparatus 100 includes a vibration table 120 that vibrates along two different axes extending in the same plane, the two different axes defining a vibration plane P1 shown in FIG.

[0040] Preferably, the two vibration axes are perpendicular to each other.

[0041] As shown in FIG. 4, the vibration table 120 performs a circular translational motion on a vibration plane P1.

[0042] Circular translational motion is defined as planar motion in which all points on the vibration table 120 have loci that are circles of the same radius but different centers.

[0043] The vibration table 120 vibrates by being mechanically driven by a motor (not shown), for example an air motor or a piezoelectric motor.

[0044] The motor vibrates the vibration table 120 at a frequency between 1,000 Hz and 12,000 Hz, preferably between 4,000 Hz and 8,000 Hz, for example at a frequency of 6,000 Hz.

[0045] The amplitude, frequency and vibration power of the vibration table 120 can be modified via a man-machine interface (not shown).

[0046] The vibration table 120 is integral with the body 111 so that the support 110 also vibrates in a plane parallel to the vibration plane P1.

[0047] The device 100 further includes a removable cover 150 or lid configured to at least partially cover the free end of the spindle 112 so as to limit axial movement of the assembly 10 and separated balance spring 12 along the longitudinal axis z of the spindle 112 when the support 110 is caused to oscillate.

[0048] The removable cover 150 includes an opening or recessed area recessed from its lower surface, i.e., the surface facing the vibrating table 120. This opening or recessed area forms a recess 151 configured to receive the free end of the spindle 112 when the removable cover 150 is in the closed position.

[0049] The removable cover 150 is movable between a closed position and an open position. The closed position limits movement of the balance spring along the z-axis of the spindle 112 and prevents the balance spring 12 from being removed from the spindle 112 of the support 110. The open position allows the wound balance spring assembly 10 to be inserted into the support 110 and removed once the balance spring 12 is separated.

[0050] Preferably, the removable cover 150 can translate along an axis perpendicular to the vibration plane P1 of the vibration table 120. Preferably, the translation axis of the removable cover 150 coincides with the longitudinal axis z of the spindle 112.

[0051] The device 100 further includes an ejector that removes the separated balance spring 12 from the support 110 in preparation for a new cycle of separating the assembly 10. Preferably, the ejector 130 is an air ejector, for example a compressed air ejector.

[0052] The device 100 further includes a collection tray 140 for collecting and collecting the various discharged balance springs 12 .

[0053] The invention further relates to a method 200 for manufacturing a hairspring intended to be equipped in the balance of a timepiece movement, said method comprising at least one step 260 of separating the wound and thermally fixed hairspring, said step being implemented by the device 100 according to the invention.

[0054] The main steps of the manufacturing method 200 are given with reference to FIG.

[0055] The manufacturing method 200 comprises the following successive steps: a step 210 of manufacturing a blank from an alloy, preferably from a compensation alloy, in particular from a titanium alloy, preferably an alloy containing niobium and titanium; applying 220 a precipitation-coupled deformation-heat treatment sequence to the alloy, the sequence comprising applying deformations alternating with heat treatments until a desired microstructure is obtained; a wire drawing step 230 carried out until a wire of round cross section is obtained, and a roller rolling step 230 producing a rectangular profile that matches the entrance cross section of the drawing spindle or star piece; a winding step 240 consisting of winding the rolled wire in the barrel by means of a winding spindle or star piece to form an assembly 10 of wound balance springs 12 in which the various balance springs 12 are wound in the same plane; an expansion step 250 to relieve stress on the wound balance spring 12 assembly 10 to fix the final Archimedes spiral shape of the balance spring 12 due to the expansion cycle; Includes:

[0056] The manufacturing method 200 further includes a step 260 of separating the hairspring heat-set during step 250. This separating step 260 is performed by the device 100 in the following manner: In a first substep 261, shown in detail in FIG. 1 , the assembly 10 formed by the plurality of wound and heat-set balance springs 12 is positioned on the spindle 112 of the support 110 so that the inner strand 13 is positioned in the notch 113 of the spindle 112, after which the assembly 10 is suspended in the device 100, held only by the inner strand 13 of the plurality of wound balance springs 12; In a second substep 262, shown in detail in FIG. 2, the removable cover 150 is lowered to a closed position, thereby preventing the assembly 10 mounted on the spindle 112 from being lost, and the support 100 is vibrated by the vibration table 120, thereby generating a circular translational movement in a plane parallel to the plane of the balance springs 12, after which the balance springs 12 are separated from one another so that they are no longer located in the same plane; In a third sub-step 263 shown in detail in FIG. 3, the removable cover 150 is raised to be positioned in an open position, and the air ejector 130 generates an air flow to eject the separated hairsprings 12; It is implemented in this manner.

Claims

1. A device (100) for separating an assembly (10) of a hairspring (12) that has been wound and has undergone an expansion cycle, comprising: a support (110) including a notch (113) intended to receive the inner strand (13) of the wound balance spring (12) that constitutes the assembly (10); a vibration table (120) movable along two different axes extending in the same plane, which define a vibration plane P1, and configured to vibrate the support (110) in a plane parallel to said vibration plane P1; a motor configured to mechanically drive the vibration table (120); An apparatus (100) comprising:

2. 2. The device (100) of claim 1, wherein said two different axes are orthogonal.

3. 2. The apparatus (100) of claim 1, wherein the vibrating table (120) vibrates in an annular translational motion.

4. 2. The apparatus (100) according to claim 1, characterized in that the support (11) comprises a body (111) integral with the vibration table (120) and a spindle (112) integral with the body (111), the spindle (112) extending perpendicular to the body (111) and to a vibration plane (P1) of the vibration table (120).

5. 5. The device (100) according to claim 4, characterized in that said notch (113) is formed in the free end of said spindle (112).

6. 6. The device (100) according to claim 5, characterized in that the shape of the free end of the spindle (112) is conical.

7. 2. The apparatus (100) according to claim 1, characterized in that the apparatus (100) includes an air ejector (130) that ejects the separated balance spring (12) when the vibration table is vibrated (120).

8. 8. The device (100) according to claim 7, characterized in that the device (100) includes a collection tray (140) for receiving the expelled balance spring (12).

9. The apparatus (100) of claim 5, characterized in that the apparatus (100) includes a removable cover (150) configured to at least partially cover the free end of the spindle (112).

10. 10. The device (100) of claim 9, wherein the removable cover (150) is movable between a closed position that prevents the balance spring (12) from being removed from the support (110) and an open position that allows the assembly (10) of the wound balance spring (12) to be inserted into the support (110) and that allows the balance spring (12) separated from the support (110) to be removed.

11. 11. The apparatus (100) according to claim 10, characterized in that the removable cover (150) is translatable along an axis perpendicular to the vibration plane (P1) of the vibration table (120).

12. 11. The apparatus (100) of claim 10, wherein the removable cover (150) includes a recess (151) configured to receive the free end of the spindle (112) when the spindle (112) is in the closed position.

13. The apparatus (100) of claim 1, characterized in that the motor is configured to vibrate the vibration table (120) at a frequency between 1,000 Hz and 12,000 Hz.

14. 14. The device (100) according to claim 13, characterized in that the motor is a pneumatic motor or a piezoelectric motor.

15. 1. A method (200) for manufacturing a hairspring intended to be equipped in the balance of a timepiece movement, said method (200) comprising a step (260) of separating an assembly (10) of wound hairsprings (12) that have undergone an expansion cycle, said step (260) being performed by implementing the device (100) according to claim 1.

16. 16. The method (200) according to claim 15, characterized in that it comprises, before the separating step (260), a winding step (240) consisting of winding a plurality of roller-rolled wires into a barrel (2) by means of a winding star so as to form the assembly (10) of wound hairsprings (12).

17. 17. The method (200) of claim 16, further comprising, after the winding step (240), an expansion step (250) to relieve stress in the wound balance spring (12) assembly (10).

18. 16. The method (200) of claim 15, characterized in that the wound balance spring (12) is a compensation spring.

19. 20. The method (200) of claim 18, wherein the wound balance spring (12) is made from an alloy of niobium and titanium.

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