Tool and method for separating balance spring after winding and heat treatment

Abstract

One aspect of the invention relates to a tool (100) for separating a plate (123) of a balance spring (1, 2, 3) after winding, said tool comprising substantially parallel lower and upper rolling surfaces (4; 5) which are movable vertically or longitudinally relative to each other in order to deform the plate (123) by ellipticization and to cause the plate (123) to move between the rolling surfaces (4; the invention relates to a tool (100) for separating balance springs (1, 2, 3) from a plate (123), said tool (100) being subjected to a rolling motion between the plates (1, 5), and also to a method for separating balance springs (1, 2, 3) from the plate (123) using the tool (100) in order to mechanically crush the springs in the elastic range and to initiate a sequence of compressing and rolling the plates (123).

Description

Technical Field

[0001] The invention relates to a tool for separating a substantially cylindrical or annular balance-spring plate after winding and heat treatment, said tool being arranged to initiate or perform the separation of said balance-spring.

[0002] The invention also relates to a method for separating a balance spring from a plate after winding and heat treatment.

[0003] The present invention relates to the manufacture of a timepiece balance spring, in particular to the manufacture of an oscillator balance spring. Background Art

[0004] The oscillator balance spring is formed by winding a number of metal leaves between 3 and 6 to form a balance spring plate; this creates an Archimedean spiral with a regular pitch between each coil. These plates are then heat treated (fixed) so that they retain this spiral shape. This method creates a large contact surface between the small metal plates, and the steps of separating the balance springs from each other can be complicated: the balance spring is said to "stick". This problem is particularly prevalent when the balance spring is made of titanium-based alloys, while steel balance springs generally do not have separation problems.

[0005] The traditional method of separating balance springs is to place them in a small cardboard box and tap the box by hand against a rigid surface. A similar but more industrial method involves the use of a tapping machine, which produces repeated impacts on the balance spring through a cam and a spring.

[0006] An alternative solution is to chemically create a layer of specific compounds to significantly reduce the sticking between the blades and allow a good separation. However, this approach limits the possibility of correcting the thermal conductivity of the balance spring. Summary of the invention

[0007] The present invention proposes to develop another method for separating a balance spring, based on mechanically crushing the balance spring before it passes through the striking machine.

[0008] To this end, the invention relates to a tool for separating a substantially cylindrical or annular balance-spring plate after winding and heat treatment, said tool being arranged to initiate or perform the separation of said balance-spring.

[0009] According to the present invention, the tool includes a first lower rolling surface and a second upper rolling surface, the first lower rolling surface and the second upper rolling surface are parallel or approximately parallel to each other and parallel to a reference plane, and are movable relative to each other in a longitudinal direction parallel to the reference plane on the one hand and in a vertical direction perpendicular to the reference plane on the other hand, and are arranged to clamp the plate between a lower generatrix and an upper generatrix under the action of at least one actuator, the at least one actuator being arranged to bring the first lower rolling surface and the second upper rolling surface closer to each other so as to deform the plate by ellipticalization, and to subject the approximately cylindrical outer peripheral surface of the plate to a rolling motion between the first lower rolling surface and the second upper rolling surface under the action of the at least one actuator, the at least one actuator being arranged to impose a relative motion between the first lower rolling surface and the second upper rolling surface in the longitudinal direction.

[0010] Another aspect of the invention relates to a method for separating a balance spring from a plate after winding and heat treatment.

[0011] According to the present invention, such a tool is used to mechanically crush the plate within the elastic range, determine the minimum and maximum values ​​of the crushing ratio of the roughly cylindrical outer peripheral surface of the plate, the plate undergoes at least one of the rolling sequences in the compressed position, determines the minimum and maximum values ​​of the rotation of each sequence, determines the minimum and maximum values ​​of the cumulative rotation for a group of sequences, determines the number of sequences, positions one of the plates between the first lower rolling surface and the second upper rolling surface of the tool through the action of an operator or an automated manipulator, and for each of the sequences, performs the following steps: a first step of compressing the plate to a predetermined vertical stroke; a second step of moving the first lower rolling surface and the second upper rolling surface relative to each other through a predetermined longitudinal stroke; and a third step of moving the first lower rolling surface and the second upper rolling surface away from each other to a spaced-apart position in which the plate is not subjected to any compressive stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The objects, advantages and features of the present invention will become more apparent from the following detailed description with reference to the accompanying drawings, in which:

[0013] - Figure 1 schematically shows a side view of a balance spring plate comprising a plurality of balance springs wound one on top of the other and staggered along their length after winding and heat treatment;

[0014] - Figure 2 Schematically shows Figure 1 Perspective view of the balance spring plate in the figure;

[0015] - Figure 3 A side view of a tool according to the invention is schematically shown, the tool comprising an upper rolling surface and a lower rolling surface, the two rolling surfaces being respectively along Figure 1 The upper and lower generatrix of the balance spring plate are supported against the edge of the plate;

[0016] - Figure 4 With Figure 3 The same tool including a mandrel to restrict radial movement of the plate is schematically shown in a similar manner;

[0017] - Figure 5 With Figure 3 The same tool is schematically illustrated in a similar manner, wherein the plate is placed on the lower rolling surface along the edge, and wherein the upper rolling surface is separated from the plate and spaced a distance from the plate;

[0018] - Figure 6 With Figure 5 The same tool is schematically illustrated in a similar manner and wherein the upper rolling surface is adjacent to the lower rolling surface and compressively bears against the plate which is ovalized due to the compression;

[0019] - Figure 7 With Figure 6 The same tool is schematically illustrated in a similar manner and wherein the upper and lower rolling surfaces are longitudinally displaced relative to each other, still bearing in compression against the plate which is ovalized due to the compression;

[0020] - Figure 8 With Figure 7 The same tool is schematically illustrated in a similar manner and wherein the upper rolling surface is moved away from the plate which has resumed its generally cylindrical shape;

[0021] - Fig. 9 Schematically shown is a perspective view of the same tool having two side plates on either side of the plate to limit its lateral play;

[0022] - Fig.10 With Fig. 9 The same tool is schematically shown in a similar manner, and the tool includes Figure 4 The mandrel is similar to the mandrel which is guided relative to the side plates. DETAILED DESCRIPTION

[0023] The invention relates to a method for mechanically crushing the plate of a wound and fixed balance spring within the elastic range, which method makes it possible to significantly increase the release rate of the balance spring.

[0024] The accompanying drawings illustrate a particular and by no means limiting application of the invention to a balance spring plate 123, the invention relating to the separation of the springs 1, 2, 3 constituting this balance spring plate 123. This example of three balance springs is purely instructive and it will be understood that the invention is applicable to any common balance spring plate.

[0025] Rolling by crushing consists in subjecting the balance-spring plates, directly after fixing, to a mechanical stress which will cause them to deform elastically so as to help separate the leaves of the balance-spring from each other and facilitate the separation process. It is therefore important to note that this rolling is not a separation method in the strict sense, but rather a preliminary step which, if correctly carried out, can significantly reduce the rejection rate during separation.

[0026] The plate of the wound and fixed balance spring is placed vertically in the vertical Z direction (ie, along the edge) on a horizontal support in the plane XY. The tool 100 comprises a mechanical actuator which then crushes the plate by moving it in the vertical direction Z. This action generates compressive stresses at the poles and tensile stresses at the equator of the balance spring plate 123; it is this tensile stress that is used locally to help separate the blades of the balance springs 1, 2, 3. Once the balance spring plate 123 has been crushed, the mechanical actuator (which can be the same as the one that initiated the crushing) causes a lateral displacement in the longitudinal direction X; this will cause the balance spring plate 123 to rotate (hence the term "rolling") while maintaining the crushing in the vertical direction Z. The result is that the tensile stress affects all parts of the blades successively as the balance spring plate 123 rolls. There is also a gradual sliding of the blades relative to each other, which also contributes to the separation effect. Once the longitudinal displacement is complete, the crushing ends and the balance spring returns to its initial shape. The tool then begins its reverse longitudinal displacement in order to return to its initial position. This cycle is repeated several times to ensure that each part of the balance-spring plate is subjected to several stages of tensile stress.

[0027] The crush rolling process is controlled by many key parameters.

[0028] The crush ratio is a critical parameter, since it will determine the intensity of the tensile stress that will contribute to the separation of the blades. However, the crush ratio must not be too high to avoid plastic deformation of balance spring plate 123. The crush ratio is preferably selected within the range of 1.5% to 5.6% of the diameter of balance spring plate 123.

[0029] The length of the longitudinal displacement of the actuator makes it possible to vary the extent of the area where the tensile stress is applied. To achieve effective rolling, it is important that all parts of the balance spring 123 are under tensile stress at some point. Typically, each lateral displacement cycle causes a rotation of between 1 / 8 and 1 full turn of the balance spring.

[0030] The number of rolling cycles depends on the longitudinal displacement of the actuator per cycle and the length of the base of the rolling device. It has been noted that there is an optimum, since too few rolling cycles have a very limited effect on improving the separation rate, while too many rolling will lead to a mechanical locking of the blades, which will then become unable to separate. The number of turns varies between 0.5 and 100, preferably between 1 and 10, even more preferably between 2 and 4.

[0031] The balance spring plates are inserted so that they roll in the opposite direction to the Archimedean spiral, otherwise the ends of the blades at the periphery of balance spring plate 123 might get caught on the base and plastically deform the balance spring.

[0032] It is advantageous to place a plate (in particular a Perspex plate) in the transverse direction Y, ie perpendicular to the rolling plane, whose function is to limit the displacement of the balance-spring plate in this transverse direction Y, while giving the necessary space for rolling with minimum friction. It also allows the blades to be pinned together at regular intervals.

[0033] Once balance-spring plate 123 has passed through tool 100 constituting a rolling device according to the invention, standard separation processes (cartons or tapping machines) can be successfully applied.

[0034] More particularly, the invention is based on the use of a tool 100 for separating a substantially cylindrical or annular plate 123 of a balance-spring 1, 2, 3 after winding and heat treatment. This tool 100 is intended for initiating or performing the separation of a balance-spring 1, 2, 3.

[0035] According to the invention, the tool 100 comprises a first lower rolling surface 4 and a second upper rolling surface 5 which are parallel or substantially parallel to each other and to a reference plane XY and which are movable relative to each other in a longitudinal direction X parallel to the reference plane XY on the one hand and in a vertical direction Z perpendicular to the reference plane XY on the other hand.

[0036] The first lower rolling surface 4 and the second upper rolling surface 5 are arranged to clamp the plate 123 between the lower busbar 1234 and the upper busbar 1235 under the action of at least one actuator 6, 7, and the actuator is arranged to bring the first lower rolling surface 4 and the second upper rolling surface 5 closer together to deform the plate 123 by ellipticalization.

[0037] The first lower rolling surface 4 and the second upper rolling surface 5 are also arranged so that the substantially cylindrical outer peripheral surface 10 of the plate 123 undergoes rolling motion between the first lower rolling surface 4 and the second upper rolling surface 5 under the action of at least one actuator 6, 7, and the actuator is arranged to apply relative motion along the longitudinal direction X between the first lower rolling surface 4 and the second upper rolling surface 5.

[0038] More particularly, the tool 100 comprises a control device 200 arranged to activate a vertical travel of the first lower rolling surface 4 in a vertical direction Z relative to the second upper rolling surface 5 and to activate a longitudinal travel of the first lower rolling surface 4 in a longitudinal direction X relative to the second upper rolling surface 5 .

[0039] More particularly, these control devices 200 are arranged to initiate at least one sequence, comprising: a first step of compressing the plate 123 by a predetermined vertical stroke of the first actuator 6 after the plate 123 has been positioned between the first lower rolling surface 4 and the second upper rolling surface 5 by an operator or an automated manipulator, a second step of moving the first lower rolling surface 4 and the second upper rolling surface 5 relative to each other through a predetermined longitudinal stroke, and a third step of moving the first lower rolling surface 4 and the second upper rolling surface 5 away from each other to a spaced-apart position in which the plate 123 is not subjected to any compressive stress.

[0040] More specifically, the predetermined vertical stroke is between 1.5% and 5.6% of the maximum diameter of the substantially cylindrical outer peripheral surface 10 of the plate 123 .

[0041] More specifically, the predetermined longitudinal travel is intended to impart to the plate 123 a rotation of between 1 / 8 of a turn and 1 turn.

[0042] More particularly, the control means 200 are arranged to initiate, in at least one sequence, a fourth step of moving the first lower rolling surface 4 and the second upper rolling surface 5 relative to each other so as to return them to the position they occupied relative to each other in the first step.

[0043] More particularly, control device 200 is arranged to initiate a plurality of such sequences with cumulative rotations of plate 123 of between 0.5 and 100 revolutions.

[0044] More particularly, control device 200 is arranged to initiate a plurality of such sequences with cumulative rotations of plate 123 of between 1 and 10 revolutions.

[0045] More particularly, control device 200 is arranged to activate a plurality of such sequences with cumulative rotations of plate 123 of between 2 and 4 revolutions.

[0046] More particularly, transversely in a transverse direction Y perpendicular to the longitudinal direction X and the vertical direction Z, the tool 100 comprises at least one plate 400 comprising a flat surface for limiting the transverse travel of the plate 123. More particularly, transversely and on both sides of the plate 123, the tool 100 comprises two such plates for limiting the transverse travel of the plate 123, at least one of which is transparent.

[0047] More particularly, the tool 100 comprises a mandrel 300 insertable in said plate 123 and arranged to limit the travel of the plate 123 when it is processed in the tool 100. More particularly, the mandrel 300 is dimensioned with respect to the plate 123 of a given geometry to have a radial clearance greater than a predetermined vertical travel, the predetermined vertical travel being the maximum compression travel activated by the control device 200. More particularly, this mandrel 300 is guided by recesses or trunnions included in two such parallel plates 400.

[0048] More particularly, the first lower rolling surface 4 is a surface of a rigid lower plate 40 , and / or the second upper rolling surface 5 is a surface of a rigid upper plate 50 .

[0049] In a first alternative embodiment, the first lower rolling surface 4 and / or the second upper rolling surface 5 are flat surfaces.

[0050] In a second alternative embodiment, the first lower rolling surface 4 and / or the second upper rolling surface 5 comprises a corrugation. More particularly, the corrugation is aperiodic.

[0051] In a second alternative embodiment, the first lower rolling surface 4 and the second upper rolling surface 5 may be oriented relative to each other in a position in which, on the plate 123 side, planes tangent to the inside of the first lower rolling surface 4 and the second upper rolling surface 5 are inclined relative to each other at a predetermined angle of less than 5°.

[0052] More particularly, the tool 100 comprises a first actuator 6 arranged to bring the first lower rolling surface 4 and the second upper rolling surface 5 closer together in the vertical direction Z so as to deform the plate 123 by ovalization.

[0053] More particularly, the tool 100 comprises a second actuator 7 arranged to subject the substantially cylindrical outer peripheral surface 10 of the plate 123 to a rolling motion on the first lower rolling surface 4 and the second upper rolling surface 5. More particularly, the second actuator 7 is arranged to initiate a relative motion in the longitudinal direction X between the first lower rolling surface 4 and the second upper rolling surface 5.

[0054] More particularly, the second actuator 7 is merged with the first actuator 6, which is the only actuator included in the tool 100 and includes a switching device for individually initiating relative movement between the first lower rolling surface 4 and the second upper rolling surface 5 in the vertical direction Z or longitudinal direction X.

[0055] In particular, the control device 200 is automatic.

[0056] In particular, the control device 200 is manual.

[0057] The invention also concerns a method for separating balance-spring 1 , 2 , 3 from plate 123 after winding and heat treatment.

[0058] According to the present invention, such a tool 100 is used to mechanically crush a plate 123 within an elastic range, minimum and maximum crushing rate values ​​are determined for a substantially cylindrical outer peripheral surface 10 of the plate 123, the plate 123 is subjected to at least one rolling sequence in a compressed position, minimum and maximum rotation values ​​for each sequence are determined, minimum and maximum cumulative rotation values ​​are determined for a group of sequences, the number of such groups of sequences is determined, the plate 123 is positioned between a first lower rolling surface 4 and a second upper rolling surface 5 of the tool 100 by the action of an operator or an automated manipulator, and for each sequence, the following steps are performed successively: a first step of compressing the plate 123 to a predetermined vertical stroke; a second step of moving the first lower rolling surface 4 and the second upper rolling surface 5 relative to each other through a predetermined longitudinal stroke; a third step of moving the first lower rolling surface 4 and the second upper rolling surface 5 away from each other to a spaced-apart position, in which the plate 123 is not subjected to any compressive stress.

[0059] More specifically, during this sequence, the blades of the balance springs 1 , 2 , 3 are radially crushed at regular intervals. In another alternative embodiment, the blades of the balance springs 1 , 2 , 3 are radially crushed at irregular intervals between the first lower rolling surface 4 and the second upper rolling surface 5 .

[0060] More particularly, after several crushing operations have been carried out by rolling according to the method, balance springs 1, 2, 3 are mechanically separated by placing plate 123 in a cardboard box which is impacted on a rigid surface and / or by subjecting plate 123 to the impacts of a striking machine which produces repeated impacts on balance springs 1, 2, 3 of plate 123.

[0061] In short, crushing the material by rolling it through its elastic range facilitates separation, and the method leaves no marks on the balance spring.

[0062] This process of separating the balance spring on a suitable tool, based on crushing by rolling, makes it possible to significantly increase the rate of separated balance springs for balance springs made of titanium alloys and to very significantly increase the proportion of balance springs suitable for maintenance.

Claims

1. A tool (100) for separating a substantially cylindrical or annular plate (123) of a balance spring (1, 2, 3) after winding and heat treatment, said tool (100) being arranged to initiate or perform the separation of said balance spring (1, 2, 3), characterized in that The tool (100) comprises a first lower rolling surface (4) and a second upper rolling surface (5), which are parallel or substantially parallel to each other and to a reference plane (XY), and are movable relative to each other in a longitudinal direction (X) parallel to the reference plane (XY) on the one hand and in a vertical direction (Z) perpendicular to the reference plane (XY) on the other hand, and are arranged to clamp the plate (123) between a lower busbar (1234) and an upper busbar (1235) under the action of at least one actuator (6, 7), the At least one actuator is arranged to bring the first lower rolling surface (4) and the second upper rolling surface (5) closer together so that the plate (123) is deformed by ovation and the substantially cylindrical outer peripheral surface (10) of the plate (123) is subjected to rolling motion between the first lower rolling surface (4) and the second upper rolling surface (5) under the action of at least one actuator (6, 7), and the at least one actuator is arranged to apply relative motion between the first lower rolling surface (4) and the second upper rolling surface (5) along the longitudinal direction (X).

2. The tool (100) according to claim 1, characterized in that The tool (100) comprises a control device (200) which is arranged to activate a vertical stroke of the first lower rolling surface (4) relative to the second upper rolling surface (5) in the vertical direction (Z), and to activate a longitudinal stroke of the first lower rolling surface (4) relative to the second upper rolling surface (5) in the longitudinal direction (X).

3. The tool (100) according to claim 2, characterized in that The control device (200) is arranged to initiate at least one sequence, the sequence comprising: a first step of compressing the plate (123) by a predetermined vertical stroke of the first actuator (6) after the plate (123) has been positioned between the first lower rolling surface (4) and the second upper rolling surface (5) by an operator or an automated manipulator, a second step of moving the first lower rolling surface (4) and the second upper rolling surface (5) relative to each other through a predetermined longitudinal stroke, and a third step of moving the first lower rolling surface (4) and the second upper rolling surface (5) away from each other into a spaced-apart position in which the plate (123) is not subjected to any compressive stress.

4. The tool (100) according to claim 3, characterized in that The predetermined vertical stroke is between 1.5% and 5.6% of the maximum diameter of the substantially cylindrical outer peripheral surface (10) of the plate (123).

5. The tool (100) according to claim 3 or 4, characterized in that The predetermined longitudinal travel is arranged to impart a rotation of between 1 / 8 and 1 turn to the plate (123).

6. The tool (100) according to any one of claims 3 to 5, characterized in that The control device (200) is arranged to initiate in the at least one sequence a fourth step of moving the first lower rolling surface (4) and the second upper rolling surface (5) relative to each other so as to return them to the positions they occupied relative to each other in the first step.

7. The tool (100) according to any one of claims 3 to 6, characterized in that The control device (200) is arranged to initiate a plurality of said sequences wherein the cumulative rotation of the plate (123) is between 0.5 and 100 revolutions.

8. The tool (100) according to claim 7, characterized in that The control device (200) is arranged to initiate a plurality of said sequences wherein the cumulative rotation of the plate (123) is between 1 and 10 revolutions.

9. The tool (100) according to claim 8, characterized in that The control device (200) is arranged to initiate a plurality of said sequences wherein the cumulative rotation of the plate (123) is between 2 and 4 revolutions.

10. The tool (100) according to any one of claims 1 to 9, characterized in that Transversely, in a transverse direction Y perpendicular to the longitudinal direction X and the vertical direction Z, the tool (100) comprises at least one plate (400) comprising a flat surface for limiting the transverse travel of the plate (123).

11. The tool (100) according to claim 10, characterized in that Laterally and on both sides of the plate (123), the tool (100) comprises two plates for limiting the lateral travel of the plate (123), at least one of the two plates being transparent.

12. The tool (100) according to any one of claims 1 to 11, characterized in that The tool (100) comprises a mandrel (300) which is insertable into the plate (123) and is arranged to limit the travel of the plate (123) when the plate (123) is manipulated in the tool (100).

13. The tool (100) according to claims 3 and 12, characterized in that The spindle (300) is dimensioned relative to the plate (123) to have a radial clearance that is greater than the predetermined vertical stroke, which is the maximum compression stroke activated by the control device (200).

14. The tool (100) according to any one of claims 1 to 13, characterized in that The first lower rolling surface (4) is a surface of a rigid lower plate (40), and / or the second upper rolling surface (5) is a surface of a rigid upper plate (50).

15. The tool (100) according to any one of claims 1 to 14, characterized in that The first lower rolling surface (4) and / or the second upper rolling surface (5) are flat surfaces.

16. The tool (100) according to any one of claims 1 to 14, characterized in that The first lower rolling surface (4) and / or the second upper rolling surface (5) comprises corrugations.

17. The tool (100) according to claim 16, characterized in that The corrugations are non-periodic.

18. The tool (100) according to any one of claims 1 to 17, characterized in that The first lower rolling surface (4) and the second upper rolling surface (5) are capable of being oriented relative to each other in a position in which, on the plate (123) side, planes tangent to the first lower rolling surface (4) and the second upper rolling surface (5) are inclined relative to each other at a predetermined angle of less than 5°.

19. The tool (100) according to any one of claims 1 to 18, characterized in that The tool (100) comprises a first actuator (6) arranged to bring the first lower rolling surface (4) and the second upper rolling surface (5) closer together in the vertical direction (Z) so as to deform the plate (123) by ovalization.

20. The tool (100) according to any one of claims 1 to 19, characterized in that The tool (100) comprises a second actuator (7) arranged to subject the substantially cylindrical outer peripheral surface (10) of the plate (123) to a rolling motion on the first lower rolling surface (4) and the second upper rolling surface (5).

21. The tool (100) according to claim 20, characterized in that The second actuator (7) is arranged to initiate a relative movement between the first lower rolling surface (4) and the second upper rolling surface (5) in the longitudinal direction (X).

22. Tool (100) according to claim 19 and according to claim 20 or 21, characterized in that The second actuator (7) is merged with the first actuator (6), the first actuator being the only actuator included in the tool (100), and the first actuator comprising a switching device for individually initiating the relative movement between the first lower rolling surface (4) and the second upper rolling surface (5) according to the vertical direction (Z) or according to the longitudinal direction (X).

23. The tool (100) according to any one of claims 1 to 22 and claim 2, characterized in that The control device (200) is automatic.

24. The tool (100) according to any one of claims 1 to 22 and claim 2, characterized in that The control device (200) is manual.

25. A method for separating a balance spring (1, 2, 3) from a plate (123) after winding and heat treatment, characterized in that a tool (100) according to any one of claims 1 to 21 is provided for mechanically crushing the plate (123) within the elastic range, minimum and maximum values ​​of the rate of crushing are determined for the substantially cylindrical outer peripheral surface (10) of the plate (123), the plate (123) is subjected to at least one of said rolling sequences in a compressed position, minimum and maximum values ​​of rotation are determined for each sequence, minimum and maximum cumulative rotation values ​​are determined for a group of sequences, the number of said sequences is determined, and the minimum and maximum cumulative rotation values ​​are determined by an operator or an automated operator. The action of the manipulator positions the plate (123) between the first lower rolling surface (4) and the second upper rolling surface (5) of the tool (100), and the following steps are performed successively for each of the sequences: a first step of compressing the plate (123) to a predetermined vertical stroke, a second step of moving the first lower rolling surface (4) and the second upper rolling surface (5) relative to each other through a predetermined longitudinal stroke, a third step of moving the first lower rolling surface (4) and the second upper rolling surface (5) away from each other to a spaced-apart position, in which the plate (123) is not subjected to any compressive stress.

26. The method according to claim 25, characterized in that During said sequence, the blades of said balance spring (1, 2, 3) are radially crushed at regular intervals between said first lower rolling surface (4) and said second upper rolling surface (5).

27. The method according to claim 25 or 26, characterized in that After having carried out a plurality of crushing operations by rolling according to the method, the balance springs (1, 2, 3) are mechanically separated by placing the plate (123) in a cardboard box subjected to impacts on a rigid surface and / or subjecting the plate (123) to impacts by a striking machine which produces repeated impacts on the balance springs (1, 2, 3) of the plate (123).

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