Monolithic spiral spring - collet assembly

Abstract

The invention relates to a monolithic spiral spring - ferrule assembly (1) comprising: - a first receiving part not deforming or not substantially deforming during operation or during mounting of the monolithic assembly on the balance staff and intended to bear against a balance staff, - a second receiving part not deforming or not substantially deforming during operation or during mounting of the monolithic assembly on the balance staff and intended to bear against the balance staff, - a first connecting part deforming elastically during operation or during mounting of the monolithic assembly on the balance staff and intended to connect the first and second receiving parts, - a second connecting part deforming elastically during operation or during mounting of the monolithic assembly on the balance staff and intended to connect the first and second receiving parts,and - an element capable of continuously surrounding the balance shaft and comprising receiving and connecting parts.

Description

[0001] The invention relates to a ferrule. The invention also relates to a monolithic assembly of a single or double balance spring and an unslotted ferrule, intended to be mounted on a balance staff, particularly a monolithic assembly including a ferrule according to the invention. In another aspect, the invention also relates to a monolithic balance spring and ferrule assembly comprising at least two stages, as well as to a method for manufacturing such an assembly. Background of the invention

[0002] One of the critical points for using a balance spring in a high-precision watch movement is the reliability of the spring's attachments (fixtures) to the balance staff and balance bridge. Specifically, the spring is generally attached to the balance staff by a ferrule, which was originally a small, slotted cylinder designed to be driven onto the balance staff and laterally pierced to receive the inner end of the balance spring itself. The development of microfabrication techniques, such as DRIE processes for silicon, quartz, and diamond, or UV-Liga for Ni and NiP, opens up possibilities in terms of the shapes and geometries used.

[0003] Silicon is a very interesting material for making watch balance springs, and microfabrication techniques allow the ferrule to be produced monolithically and manufactured with the balance spring. A potential problem is that silicon has no plastic deformation range. The ferrule can therefore break quickly if the stresses exceed the maximum allowable stress and / or the elastic limit of the material. It is therefore essential to carefully design the ferrule both to hold the balance spring on the balance staff during oscillator operation (minimum tightening torque) and to allow assembly of the ferrule with staffs whose diameters fluctuate, without breaking or undergoing plastic deformation if the balance staff diameter remains within a given tolerance range.

[0004] Thus, several documents reveal the geometries of ferrules.

[0005] The European patent application published under number EP 1 826 634 proposes on its figure 4 In connection with line 34 of column 3, a ferrule with elastic zones consisting of curved arms. This document does not indicate where the spiral should be attached.

[0006] European patent applications published under numbers EP 1 513 029 and EP 2 003 523 propose ferrules with a triangular opening. The balance spring is attached at a point (reference 3 in the figures of these documents) located at one of the vertices of the triangles. The ferrule consists of an external stiffening structure to which flexible arms are attached, which deform to accommodate the balance staff.

[0007] European patent application EP 1 655 642 describes in Figure 10D a balance spring resonator with a ferrule having a circular opening. The balance wheel is attached in this case using rounded arms.

[0008] We also know from patent application WO2011026275 of a balance spring-ferrule assembly, with a ferrule having a bore fitted with four circular support portions to receive the balance staff. The support portions are delimited by longitudinal grooves made in the bore of the ferrule.

[0009] The geometries described in these documents are not entirely satisfactory, so many balance springs (made of silicon, diamond, quartz, etc.) mounted on movements are fitted with a classic ferrule which is then pressed and / or glued onto the balance wheel axis. Summary of the invention

[0010] The invention aims to provide new ferrule geometries that offer complete satisfaction, that is, allowing for the highest possible tightening torque on the balance staff and the lowest possible stress in the material. Furthermore, these ferrules must be as balanced as possible to avoid any imbalance, which would degrade the chronometric properties of the balance spring.

[0011] According to one aspect of the invention, objects are defined by the attached claims.

[0012] According to another aspect, the invention relates to a monolithic assembly consisting of a single or double spiral spring and an unslotted ferrule, in which: the contour of the ferrule is closed, the central opening of the ferrule intended to receive a balance staff is non-circular, the contour of the central opening of the ferrule has at least two bearing surfaces for a balance staff; This monolithic structure is distinguished by the fact that: The ferrule is formed of at least two balance staff receiving parts located opposite each other, in particular at 180°, and of which one includes at least the first of the bearing surfaces for the balance staff as well as an attachment or embedding point for the balance spring, and the other at least the second of the bearing surfaces for the balance staff, these two balance staff receiving parts being connected to each other by two connecting parts which have a rigidity lower than that of the receiving parts, so as to be able to deform elastically during the insertion of a balance staff.

[0013] These features notably prevent the balance spring's attachment point from shifting significantly relative to its contact points (support points) with the balance staff after the latter has been driven in. Consequently, the balance spring's positioning and its point of attachment can be precisely defined.

[0014] In another aspect, the invention relates to a monolithic assembly consisting of a single or double balance spring and a ferrule, the latter being either slotted or unslotted. This assembly is characterized by having at least two levels (or stages or parts), with the balance spring located on a different level from that where the ferrule's bearing surfaces for the balance staff are situated. This feature is particularly advantageous because it allows for optimal torque control of the ferrule on the balance staff without increasing its overall size relative to the balance spring. According to another aspect of the invention, this feature allows the attachment point of the balance spring to be positioned closer to the balance staff, without being limited by the ferrule's circumference.

[0015] The invention also relates to a method of manufacturing a monolithic spring-spiral assembly - split or unsplit ferrule, in which the spiral is made on a different level from that where the bearing surfaces of the ferrule for the balance staff are located.

[0016] According to another aspect, the invention is defined by the following propositions: 1. Ferrule (100) comprising a bore (101) intended to receive a balance staff, at least a first part (102) and a second part (103), the first and second parts being separated by a plane (104) perpendicular to the axis (107) of the bore, an element (105) for attaching the ferrule to a spiral spring being exclusively located on the first part and an element (106) for connecting the ferrule to the balance staff being essentially, or even exclusively, located on the second part. 2. Ferrule according to Proposition 1, in which the attachment element or attachment point is located at a distance (D1) from the center of the ferrule (107) less than half the diameter (D2) of a cylinder in which the second part is inscribed, in particular at a distance (D1) less than or equal to the average of half the diameter (D2) of the cylinder in which the second part is inscribed and half the diameter of the circle inscribed (d max) in a central opening of the ferrule. 3.Ferrule according to proposal 1 or 2, in which the second part extends, along the axis of the bore, over a length greater than one times the thickness (E) of the spiral spring, or even greater than 3 times the thickness (E) of the spiral spring. 4.Monolithic spring-corner assembly (1) comprising: a first receiving portion, in particular a first rigid receiving portion, intended to bear against a balance staff; a second receiving portion, in particular a second rigid receiving portion, intended to bear against the balance staff; a first connecting portion, in particular a first deformable connecting portion, intended to connect the first and second receiving portions; a second connecting portion, in particular a second deformable connecting portion, intended to connect the first and second receiving portions; and an element adapted to continuously surround the balance staff and comprising the receiving portions and the connecting portions. 5. Monolithic assembly according to proposal 4, in which the connecting portions occupy 50% or more, or even between 50% and 90%, or even between 60% and 80%, of the total length of the outer contour of the cornice. 6.Monolithic assembly according to proposition 4 or 5, in which each connecting part occupies a sector of angle measured from the center of the ferrule greater than or equal to 90°, or even between 90° and 160°, or even between 110° and 145°. 7. Monolithic assembly according to one of propositions 4 to 6, in which each connecting part has a portion at least 0.5 times the radius of the balance staff, or even at least 0.9 times the radius of the balance staff, once the assembly is mounted on the balance staff. 8. Monolithic assembly according to one of propositions 4 to 7, in which each connecting part is primarily subjected to bending, once the monolithic assembly is mounted on the balance staff. 9. Monolithic assembly according to one of propositions 4 to 8, in which the receiving parts are opposite each other, in particular at 180° to each other with respect to the center of the ferrule. 10.Monolithic assembly according to one of propositions 4 to 9, in which a blade of the balance spring is attached or directly linked to a receiving part, in particular, in the case of an assembly comprising a double balance spring, in which each blade is attached to a different receiving part. 11. Monolithic assembly according to one of propositions 4 to 10, in which a central opening in the ferrule intended to receive a balance staff is non-circular. 12. Monolithic assembly according to one of propositions 4 to 11, in which the contour of the central opening in the ferrule (1) includes, on the same receiving part, at least one bearing surface (2, 3; 4, 5) for the balance staff. 13.A monolithic assembly according to any one of propositions 4 to 12, in which the contour of the central opening of the ferrule (1) comprises, on the same receiving portion, at least one pair of bearing surfaces (2, 3; 4, 5) for the balance shaft axis, the tangents to the bearing surfaces (2, 3) at the bearing points of this pair forming an angle (α) greater than 90 degrees and less than 170 degrees. 14. A monolithic assembly according to any one of propositions 4 to 13, in which the contour of the central opening of the ferrule (1) comprises two pairs (2, 3; 4, 5) of bearing surfaces. 15. A monolithic assembly according to any one of propositions 4 to 14, in which the bearing surfaces (2, 3; 4, 5) are at least partially located on arms (6, 7; 8, 9) or extensions extending from the body of the receiving portions. 16.Monolithic assembly according to one of propositions 13 to 15, in which the bearing surfaces are flat, negatively curved, or positively curved with a radius greater than 0.51 times the diameter (d max) of the circle inscribed in a central opening of the ferrule. 17. Monolithic assembly according to one of propositions 4 to 16, in which two receiving parts are arranged at 180° to each other with respect to the axis of the ferrule. 18. Monolithic assembly according to one of propositions 4 to 17, in which the different connecting parts have identical geometry and / or the different receiving parts have identical geometry. 19.Monolithic assembly according to one of propositions 4 to 18, in which the spiral spring is a double spiral spring comprising a first blade whose attachment point (10) to the ferrule (1) is connected to a first receiving portion and a second blade whose attachment point (11) to the ferrule (1) is connected to a second receiving portion. 20. Monolithic assembly according to one of propositions 4 to 19, in which the geometry of the ferrule has a reflection symmetry of order 2. 21. Monolithic assembly according to one of propositions 4 to 20, in which the geometry of the ferrule has a rotational symmetry of order 2. 22. Monolithic assembly according to one of propositions 4 to 21, the assembly being made of silicon, optionally with an outer and / or inner layer of silicon oxide. 23.24. Monolithic assembly according to one of propositions 4 to 22, wherein the attachment point(s) of the single or double balance spring is / are closer to the central opening of the ferrule than is the contour of the ferrule. 25. Monolithic assembly according to one of propositions 4 to 23, the assembly being made of a brittle material or of a material not exhibiting a plastic deformation range. 26. Monolithic assembly according to one of propositions 4 to 24, the assembly comprising a ferrule according to one of propositions 1 to 3. 27. Manufacturing method for a monolithic assembly according to proposition 25, wherein the balance spring is made on a part different from that where the bearing surfaces of the ferrule against the balance staff are located. 28. Manufacturing method according to proposition 26, wherein the starting material is an SOI slab with a SiO2 layer thicker than 3 microns. 28.A method for manufacturing a ferrule according to one of propositions 1 to 3, in which an element (105) for attaching the ferrule to a balance spring is made on a part different from that in which an element (106) for connecting the ferrule to the balance staff is located. 29. A manufacturing method according to proposition 28, in which a SOI slab with a SiO2 layer thicker than 3 microns is used as the starting material. 30. A monolithic assembly of a balance spring and ferrule (1) made of a material not exhibiting a plastic deformation range, in which: the contour of the ferrule (1) is closed, the central opening of the ferrule (1) intended to receive a balance staff is non-circular, the contour of the central opening of the ferrule has at least two bearing surfaces (2, 3; 4, 5; 14) for a balance staff; . characterized in thatThe ferrule (1) is formed of two balance staff receiving portions situated opposite each other, one of which comprises at least the first of the bearing surfaces (2 or 3) for the balance staff as well as an attachment point (10, 11) for the balance spring, and the other at least the second of the bearing surfaces (4, 5 or 14) for the balance staff. These two balance staff receiving portions are connected to each other by two connecting portions which have a rigidity lower than that of the receiving portions, so as to be able to deform elastically during the insertion of a balance staff. 31. Monolithic assembly of balance spring and ferrule (1) according to Proposition 30, in which the two connecting portions have an average width less than the average width of the receiving portions. 32.- Monolithic spring-ferrule assembly (1) according to Proposition 30, in which the two connecting parts have a minimum width and / or a width at mid-distance from the receiving parts, less than the maximum width of the receiving parts. 33. Monolithic spring-ferrule assembly (1) according to one of Propositions 30 to 32, in which the contour of the central opening of the ferrule (1) comprises, on the same receiving part, at least one pair of bearing surfaces (2,3; 4,5) for the balance staff, the bearing surfaces (2,3) of this pair forming an angle (α) greater than 90 degrees and less than 170 degrees. 34. Monolithic spring-ferrule assembly (1) according to Proposition 33, in which the contour of the central opening of the ferrule (1) comprises two pairs (2,3; 4,5) of bearing surfaces. 35.- Monolithic spiral spring-ferrule assembly (1) according to one of propositions 30 to 34, in which the bearing surfaces (2,3; 4,5) are at least partially located on arms (6,7; 8,9). 36. Monolithic spiral spring-ferrule assembly (1) according to one of propositions 30 to 35, in which the connecting parts have identical geometry. 37. Monolithic spiral spring-ferrule assembly (1) according to one of propositions 30 to 36, in which the spiral spring is a double spiral spring comprising a first leaf (10) whose point of attachment to the ferrule (1) is connected to a first receiving part and a second leaf (11) whose point of attachment to the ferrule (1) is connected to a second receiving part. 38. Monolithic assembly spiral spring - ferrule (1) according to one of the propositions 30 to 37, whose ferrule geometry has a reflection symmetry of order 2. 39.- Monolithic spring-ferrule assembly (1) according to one of propositions 30 to 38, the geometry of which has a rotational symmetry of order 2. 40. - Monolithic spring-ferrule assembly according to one of propositions 30 to 39, this assembly being made of silicon, possibly with an outer layer and / or a stage of silicon oxide. 41. - Monolithic spring-ferrule assembly (1) according to one of propositions 30 to 40, formed on two levels, the spring being located on a different level from that where the bearing surfaces (2, 3; 4, 5; 14) for the balance staff are located. 42. - Monolithic spring-ferrule assembly having at least two levels, the spring being located on a different level from that where the bearing surfaces of the ferrule for a balance staff are located. 43.- Monolithic spring-coil assembly according to proposition 41 or 42, wherein the attachment point(s) of the single or double balance spring is / are closer to the central opening of the ferrule than is the contour of the ferrule. 44. - Method of manufacturing a monolithic spring-coil assembly according to one of propositions 41 to 43, wherein the balance spring is made on a different level from that where the ferrule bearing surfaces for the balance staff are located. 45. - Method of manufacturing according to proposition 44, wherein the starting material is an SOI slab with a SiO2 layer thicker than 3 microns. 46. - Oscillator comprising a monolithic assembly according to one of propositions 4 to 25 or 30 to 45 and a balance staff with a circular cross-section. 47.- Watch movement or timepiece comprising a monolithic assembly according to one of the propositions 4 to 25 or 30 to 45 or comprising an oscillator according to the preceding proposition or comprising a ferrule according to one of the propositions 1 to 3. .

[0017] Other features and advantages of the invention will now be described in detail in the following exposition, which is given with reference to the attached figures, which schematically represent: figure 1 : a ferrule according to the prior art EP 1 513 029 and EP 2 003 523; figure 2 : a ferrule of figure 10D of the prior art EP 1 655 642; figure 3 : a ferrule according to prior art WO2011026725; figure 4 : a monolithic double spiral spring assembly - closed contour ferrule according to the invention; figures 5 to 7 : other monolithic assemblies double spiral spring - closed contour ferrule according to the invention; figure 8: the main steps of the process of obtaining a monolithic double spiral spring - ferrule assembly according to a second aspect of the invention; figures 9 to 11 : a monolithic double spiral spring assembly - ferrule according to a second aspect of the invention; Figures 12 and 13 : other monolithic assemblies double spiral spring - ferrule according to the second aspect of the invention; figure 14 : a graph showing the evolution of the holding torque M of the ferrules of the assemblies figures 12, 13 And 3 depending on the diameter of the balance shaft; figure 15 : a graph showing the evolution of the stress s of the ferrules of the sets of figures 12, 13 And 3 depending on the diameter of the balance shaft; Figures 16 to 17 : a representation of the constraints within the ferrules of the assemblies Figures 12 and 13once a balance shaft is driven into the opening (black: very low elastic deformation, stresses less than half the maximum stress; in grey: significant elastic deformation, stresses greater than half the maximum stress); figure 18 : a representation of the rigid (in black) and flexible (in grey) zones for the ferrule of the figure 12 ; figure 19 : a monolithic double spiral spring - ferrule assembly according to an advantageous variant of the second aspect of the invention, in which the attachment points of the blades of the double spiral are close to the central opening; Figure 20 : a cross-sectional view of a ferrule according to an advantageous variant of the second aspect of the invention; figure 21 : a monolithic double spiral spring assembly - ferrule according to the first aspect of the invention with indication of the position of the mounting points; and figure 22: a monolithic double spiral spring assembly - ferrule according to the second aspect of the invention with indication of the position of the embedding points. Detailed description of the invention

[0018] On the figure 1 represented is the ferrule proposed in the aforementioned European patent applications EP 1 513 029 and EP 2 003 523.

[0019] On the figure 2 is represented the ferrule described in figure 10D of the aforementioned European patent application EP 1 655 642.

[0020] On the figure 3 The ferrule proposed in patent application WO2011026725 is shown.

[0021] The invention applies to both single-spiral and double-spiral assemblies. However, it is best suited to the latter.

[0022] By "double spiral" we mean here a spiral having two blades wound in the same direction, but with an offset of 180 degrees, as described in application EP 2 151 722 A1. The respective inner ends of these blades are fixed to the ferrule and their respective attachment points are arranged symmetrically on opposite sides of the periphery of the ferrule.

[0023] The "attachment point" or "embedded point" of the spiral is generally well-defined when the spiral is mounted on a ferrule made of a different material. In the case of a monolithic ferrule-spiral assembly where both the spiral and ferrule are manufactured, for example, using a microfabrication technique from a silicon wafer or "Silicon-on-Insulator," the embedded point can be defined as the point where the local stiffness along the neutral axis reaches a value 10 times greater than the stiffness of the spiral blade. For a spiral with a variable blade thickness, the minimum value of the local stiffness along the blade is considered. The local stiffness is equivalent to the bending stiffness, determined during blade bending or spiral operation, over a given length, for example, 1 µm.The corresponding 10,11 mounting points are shown as an example on the ferrule-spiral assemblies of the . Figures 21 and 22 In the case of the figure 21 (which corresponds to the ferrule geometry of the figure 12 ), we see that the point of attachment is located on the extension of the external contour or periphery 32 of the ferrule. In the case of the figure 22 (which corresponds to the ferrule geometry of the figure 19 ), we see that the point of embedding is located in the immediate vicinity of the balance axis, closer to the central opening of the ferrule than is the contour 33 of the ferrule level which does not include the spiral.

[0024] The ferrules according to the invention are dimensioned both to retain the balance spring on the balance staff during oscillator operation and to be compatible with staffs whose diameters exhibit a certain degree of variation (no breakage or plastic deformation during pressing for a staff diameter within a given tolerance range). These ferrules normally have at least two, and preferably four, bearing surfaces for the balance staff.

[0025] According to the invention, the precise shape of the connecting parts is not crucial, as long as they can deform elastically, particularly in bending, when a balance shaft is driven in. Under normal operating conditions of the ferrule, the receiving parts are therefore rigid or non-deformable, and the connecting parts are deformable, particularly deformable in bending, or flexible. The flexibility of the latter arises from the fact that they are thinner than the receiving parts. The deformable parts have smaller cross-sectional areas than the non-deformable parts. This thinning is achieved, according to the invention, by making the deformable parts narrower than the receiving parts.By "width" we mean here the thickness measured in the plane of the ferrule, in other words, the distance between the contour of the ferrule and the contour of its central opening (for example, the minimum width e or e' or the width at mid-distance of the rigid receiving parts b or b' on the . Figures 12 and 13 ).

[0026] The junctions between the receiving and connecting parts are generally located approximately at the base of a bearing surface (see below, as well as, by way of example, the figure 18 , or the figure 5 where they can be located each time on one side of the curved part 14). Preferably, we seek to maximize the length of the connecting parts, therefore to maximize the angular sector they occupy.

[0027] There figure 4 represents the central part of an example of a monolithic double spiral spring assembly - non-split ferrule according to the invention.

[0028] As can be seen on the figure 4 The ferrule 1, in particular the receiving portions 17, 18, has two pairs of support points 2, 3 and 4, 5 located on substantially flat arms 6, 7 and 8, 9 which are not elastic and are positioned in pairs near the attachment points 10, 11 of the blades 12, 13 of the double spiral. The inelastic arms of each pair protrude into the central opening of the ferrule and form an angle α with each other which is preferably less than 170 degrees, more preferably greater than 90 degrees and less than 170 degrees, and is here approximately 120 degrees. Each arm 6, 7, 8 or 9 has a free end.

[0029] The V-shaped design of the rigid arms provides better support for the balance staff than a single point of contact would. The key is to ensure the most rigid possible connection between the ferrule and the balance staff, so that the contact points between the ferrule and the balance staff do not shift under the torque generated by the balance spring during operation. This occurs during the oscillations of the balance wheel and balance spring once the entire spring-ferrule assembly is mounted on the balance staff. The geometry, with two receiving sections facing each other (specifically, at 180° intervals), each with a pair of bearing surfaces, acts like a vise held in place by the flexible connecting sections. Under the effect of their elastic deformation, the connecting parts exert elastic restoring actions, pulling the receiving parts towards each other and each in contact against the balance shaft axis.However, it is also possible (but less favorable) to use a single support point, such as a flat, convex or concave contact surface with a radius of curvature greater than the radius planned for the axis of the balance wheel.

[0030] On the figure 4 The arms 6, 7, 8, and 9, and their corresponding bearing surfaces 2, 3, 4, and 5, are planar, meaning their radius of curvature on the side of the central opening 26 is infinite. The bearing surfaces can also be convex, meaning their radius of curvature can be negative on the side of the central opening 26, or concave, meaning their radius of curvature can be positive on the side of the central opening 26.

[0031] In this latter case, however, the positive radius of curvature is strictly greater than 0.51 times the diameter dmax of the largest circle that can be drawn inside the contour of the central opening (when the ferrule is not deformed, particularly when it is not mounted on the balance staff), a circle also referred to as the "inscribed circle" in the following description. Preferably, the positive radius of curvature is greater than 0.62 times the diameter dmax, which allows for a single point of contact between the bearing portion and the balance staff. A radius of curvature greater than 0.75 times, or even 1 times, the diameter dmax of the inscribed circle is also suitable. In the case of a balance staff with a circular cross-section, the diameter of the staff is slightly greater than dmax, for example, within a tolerance range between 1.01 and 1.02 dmax.

[0032] It is important to ensure that there is no flexible part between the points of contact of the ferrule / balance axis and the point of attachment of the balance spring, so that the distance between the point of embedding or attachment and the bearing surfaces varies as little as possible and in particular does not vary substantially following the pressing.

[0033] The ferrule 1 exhibits rotational symmetry of order 2 and has two axes of symmetry in reflection, one formed by the bisector of angle α, the other perpendicular to the latter and located equidistant from the intersection of the arms. It can be considered as comprising two rigid balance shaft receiving sections connected by two flexible connecting sections, as can be seen on the figure 18 which will be detailed below. The rigid parts 17 and 18 (in black on the figure 18) are those from which both arms 6, 7 and 8, 9 and blades 12 and 13 of the double spiral originate. The flexible parts 15 and 16 (in gray on the figure 18 These flexible sections are connecting parts that symmetrically link the rigid parts to form the ferrule 1 with its central opening. These flexible sections are thinner than the rigid parts, and their elasticity or flexibility allows the ferrule 1 to deform during mounting onto the balance staff while ensuring minimal holding torque. Furthermore, the non-circular central opening allows the flexible sections to be offset and their length maximized.

[0034] The symmetry of the geometry of the ferrule of the figure 4aims to achieve balance so as not to create imbalance. The non-circular central opening of the ferrule can be defined as comprising a central recess 26 for receiving the balance shaft, substantially delimited by the 4 bearing surfaces 2, 3, 4 and 5, and two peripheral recesses 27, 28 formed substantially and symmetrically between the arms 6, 8, on the one hand and 7, 9 on the other hand, and the elastic parts 15 and 16. The recesses 27 and 28 are symmetrical to each other with respect to the bisector of the angle α.

[0035] Thus, geometry allows us to precisely define the support points, four in number in the case of the figure 4 Arms 6 through 9 precisely define the support points of the ferrule on the balance staff axis, while maximizing the length of the flexible elastic sections. However, these arms 6 through 9 do not flex, or flex negligibly, and cannot be considered elastic arms.

[0036] This is confirmed by numerical simulations reported on the Figures 16 and 17 , which indicate the levels of stress present following the pressing of a balance shaft with a nominal diameter of 0.503 mm into two ferrules of different geometry shown on the Figures 12 and 13 (one can also refer to Figures 14 and 15 which indicate the holding torques and maximum stresses for these ferrules for different shaft diameters). The parts that are not or only slightly deformed elastically, and which can be considered rigid, are indicated in black on the Figures 16 and 17 (stress level less than half the maximum stress reached following the removal of the shaft, i.e. approximately 500 MPa in the case of the Figures 16 and 17The parts that are elastically deformed, and which can be considered flexible, are shown in gray in the same figures (stress level greater than half the maximum stress). These numerical simulations show that arms 6 to 9, which support the bearing surfaces, are not elastically deformed, unlike the flexible parts 15 and 16. The distance between the support points and the attachment points of the spiral is thus always constant and perfectly defined.

[0037] The ferrule is thus formed of two rigid balance shaft receiving parts 17,18 symbolized in black on the figure 18 , connected to each other by two flexible or elastic connecting parts 15,16, symbolized in grey on the figure 18The advantage of this arrangement is that it maximizes the length of the flexible connecting parts while ensuring sufficient holding torque on the rocker arm axis, with a stress level significantly lower than the maximum allowable stress for the material. Simulations show that the ferrule according to the invention provides a higher holding torque (M) on the axis than with flexible arms located inside a closed contour (for the same overall dimensions). Using the theory of small deformations applied to the case of a flexible beam, it can be shown that the holding torque M depends on the length of the flexible parts L, with M being proportional to L. The longer the flexible parts, the higher the holding torque. The advantage of the ferrule according to the invention is that it maximizes the length of the flexible parts. For example, the figure 18The flexible sections occupy approximately 70% of the total contour length. Preferably, the flexible sections occupy 50% or more of the total contour length, specifically between 50% and 90%, and more preferably between 60% and 80%. Alternatively, the angle sectors measured from the center of the ferrule (which corresponds to the center of the circle inscribed in the central opening) and occupied respectively by a rigid receiving section and a flexible connecting section are approximately 54° and 126°. Preferably, the angle sector measured from the center of the ferrule and occupied by a flexible connecting section is greater than or equal to 50°, specifically between 90° and 160°, and more preferably between 110° and 145°.This angle sector is defined for example as the smallest continuous angle sector between two receiving parts where there is an area where the stress in the material is greater than 50% of the maximum stress reached following the driving of the axis.

[0038] Another example of an embodiment of the invention is shown on the figure 5In this figure, the ferrule comprises only a single pair of inelastic arms 2, 3. Opposite the V formed by these arms, on the other side of the non-circular central opening, is a domed portion 14 intended to serve as a third support surface for the balance staff. The geometry here exhibits only a reflection symmetry around the bisector of angle α (if the attachment point of the balance spring blades is disregarded). The shape and dimensions of the domed portion 14 are chosen to maximize the balance of the ferrule. Alternatively, the third support surface can also be flat or concave, with a radius of curvature strictly greater than 0.51 times, preferably greater than 0.62, 0.75, or 1 times the inscribed diameter d max.

[0039] The ferrule according to the invention is particularly well-suited for attaching a double balance spring to a balance staff. Indeed, most known ferrules in the prior art do not deform symmetrically with respect to their attachment points. With a ferrule like the one shown in the figure 1 One of the blades would be fixed at the same point as the blade of the simple spiral shown, namely at the apex of the triangle formed by the stiffening structure. The second blade must have an attachment point located 180° from the first, that is, opposite it, in the middle of one side of the triangle. The displacement of the attachment points following the adjustment relative to the center of the spiral and / or the external attachments would therefore not be equivalent for both attachment points, which would degrade chronometric performance. Furthermore, the attachment point of the second blade would be susceptible to deformation during the expansion and contraction of the spiral, which would also impair chronometric performance. Second aspect of the invention

[0040] In another aspect, the invention relates to a ferrule having at least two levels, stages, or parts. The attachment or anchoring point of the balance spring (or attachment points in the case of a double balance spring) is then located on a different level from that where most, or even all, of the bearing surfaces are situated. This is particularly applicable to a monolithic spring-balance spring-ferrule assembly.

[0041] The inventors discovered that it was possible to maximize the torque resistance of the ferrule, while minimizing its size, by extending the ferrule in the plane perpendicular to the balance spring. This allows the function of attaching the balance spring to the axis via the ferrule (first level, in the plane of the balance spring) to be separated from its function of holding the axis, particularly holding the ferrule to the axis (first and second levels, and preferably exclusively on the second level, outside the plane of the balance spring), while distributing the elastic stress as evenly as possible along the flexible sections.

[0042] A monolithic spiral spring-ferrule assembly corresponding to that of the figure 4 constructed on two levels, it is represented in front and rear perspectives on the Figures 9 and 10 .

[0043] As can be seen in these figures, the sides are not perfectly superimposed; there is a difference of a few microns between the first and second layers.

[0044] There figure 11 represents the entire spring-spiral assembly according to the Figures 9 and 10 , with the outer ends of the double-spiral blades which are attached to a fixing element intended to be connected to the movement of a timepiece.

[0045] It is evident that such a monolithic spring-spiral-ferrule assembly made on 2 levels can also be applied to other types of ferrules, in particular to split ferrules, and to other types of spirals, in particular to simple spirals. Manufacturing process

[0046] The ferrule or spiral-ferrule assembly can be manufactured using known processes, such as that which is the subject of patent application no. EP 1 655 642. The ferrule or spiral-ferrule spring assembly according to the second aspect of the invention can be manufactured using known processes, such as those which are the subject of patent applications no. EP 1 835 339 or EP 2 104 007.

[0047] The main steps in a manufacturing process for a ferrule or a monolithic spiral spring-ferrule assembly produced on 2 levels, stages or parts are shown on the figure 8 .

[0048] The starting substrate used is a wafer of the "SOI" ("Silicon-on-Insulator") type, composed of two parts of monocrystalline Si separated by a thin layer of silicon oxide, SiO2 ( figure 8a(with monocrystalline Si in white and SiO2 in oblique hatching). After initial cleaning, the slice is oxidized to form a layer of SiO2 on the surface on both sides of the substrate ( figure 8b ) which will serve as a mask for deep reactive ion etching (DRIE). Photolithography is then performed on one face to define a first pattern in photosensitive resin ( figure 8c (resin shown in straight hatching) and this pattern is reproduced in the underlying oxide layer by dry etching ( figure 8d After cleaning ( figure 8e ), the same steps are repeated on the second side with a second pattern: a photolithography process is used to define a second pattern in photosensitive resin ( figure 8f ), which is reproduced in the underlying oxide layer by dry etching ( figure 8g). A deep etching step by DRIE is then carried out on the second side to engrave the pattern into the second layer of Si ( figure 8h ). Then, a deep DRIE etching is performed on the first layer ( figure 8i ). The exposed SiO2 parts (outer layers and central layer) are finally dissolved by BHF attack (buffered HF, i.e. a mixture of HF and NH4F which serves as a buffer to stabilize the attack rate; figure 8j ).

[0049] Various additional steps to the processes described above may be included, such as (but not limited to): the deposition of functional layers (oxides, nitrides, carbon-based layers) on all or part of the surface, for example by PVD, CVD, or ALD type techniques; the deposition of a SiO2 oxide layer to thermocompensate the balance-spring oscillator according to EP 1 422 436; the production of part of the structure, for example arms 6, 7, 8 and 9, in metal or metal alloy by a LiGA type electroforming technique. An advantageous variant of the second aspect of the invention

[0050] According to an advantageous variant of the second aspect of the invention, the ferrule has at least two levels, and the attachment or embedding point of the spiral (or attachment points in the case of a double spiral) is located on a different level from that where the bearing surfaces are located and at a distance from the center of the ferrule less than the distance between the center of the ferrule and its contour or periphery.

[0051] As illustrated in the Figure 20The ferrule 100 comprises a bore 101 for receiving the balance staff, as well as at least a first portion 102 and a second portion 103. The first and second portions are separated by a plane 104 perpendicular to the axis 107 of the bore, this axis also representing the center of the ferrule. The element(s) 105 for attaching the ferrule to a balance spring are located exclusively on the first portion. The element 106 for connecting the ferrule to the balance staff, for example formed by the bearing surfaces, is essentially, preferably exclusively, located on the second portion. By "an element for connecting the ferrule to the balance staff is essentially located on the second portion," it is understood that more than half of the forces connecting the ferrule to the balance staff are applied at the level of the second portion. The 101 bore forms a central opening intended to receive the balance staff.

[0052] Preferably, a silicon dioxide (SOI) wafer is used to fabricate such a ferrule or a monolithic ferrule-spiral assembly including such a ferrule, the first and second parts being made of silicon and separated by a layer of silicon oxide. Indeed, the use of SOI wafers where the internal SiO₂ layer separating the two Si layers is thick, or even very thick (for example, 2-3 microns as is usually the case, but preferably thicker than 5, or even 10 microns) makes it possible to fabricate a flexible ferrule with overlapping turns as shown in the diagram. figure 19 , which shows such a monolithic double spiral spring-ferrule assembly made on 2 levels. The flexible ferrule is in every respect similar to that of the figure 4 However, the attachment points of the spiral are not located on the contour as in the figure 21 , but as close as possible to the central opening of the ferrule and therefore to the balance staff, as in the example of the figure 22 The spiral blades are thus partially superimposed on the ferrule, over slightly less than 180° in the example of the figure 19 (corresponding to slightly less than half a turn of the spiral blade's winding). The two-level manufacturing process makes it possible to create this type of structure, because the dissolution attack of SiO2 ( figure 8j ) will also attack the oxide that binds the blades to the ferrule if the attack time is sufficient, thus freeing them.

[0053] Thus, the attachment point of the spiral to the ferrule, or the point of attachment 10, 11, is located at a distance D1 from the axis of the bore 107 that is less than half the diameter D2 of a cylinder in which the second part is inscribed, specifically at a distance D1 less than or equal to the average of half the diameter D2 and half the diameter of the inscribed circle dmax. This is the case for the spiral-ferrule assembly of the figure 22, for which D1 is 0.330 mm, while D2 is 1.180 mm, and the average of half the diameter D2 and half the diameter of the inscribed circle dmax is (1.180 mm / 2 + 0.495 mm / 2) / 2 = 0.41875 mm. This is equivalent to placing the fixed point 10.11 at a distance of 85 microns from the axis in the case of the figure 22 , compared to 275 microns in the case of the figure 21 Alternatively, the point of embedding is closer to the central opening than is the contour 33 of the ferrule.

[0054] A ferrule such as described above can in particular be included in a monolithic spiral spring-ferrule assembly.

[0055] Bringing the balance staff closer to the balance wheel axis significantly improves chronometric properties. Furthermore, this approach is not limited to a double balance spring but is also perfectly suited to a single balance spring, and is not limited to a closed-contour ferrule but also accommodates a split ferrule. Any combination of ferrule and balance spring can be achieved in this way, resulting in a spring-barrel assembly with markedly improved chronometric properties. Simulations

[0056] Finite element simulations were performed on two monolithic assemblies of a double spiral spring with a two-part, unslotted ferrule, of the type shown in the... Figures 9 and 10 .

[0057] These two similar sets A and B are represented on the figures 12 et 13 Their dimensions are comparable in several respects: the overall length is 1.17 mm along the major axis (dimension d in the figures), the distance c is 0.550 mm, the inscribed diameter at the center of the opening is 0.495 mm, the angle α is 120°, and the radius of curvature of the outer contour at the apex of the flexible connecting parts is 0.538 mm. Only the thickness of the flexible connecting parts differs significantly: if we denote b as the width at the apex of the connecting parts (i.e., at their midpoint, halfway between the receiving parts) and e as the minimum width of the connecting parts, b = 0.085 mm and e = 0.050 mm for the ferrule of the figure 12 and b' = 0.070mm and e' = 0.050mm for the ferrule of the figure 13 The maximum width of the rigid receiving parts also differs: a = 0.224 mm for the ferrule of the figure 12 and a' = 0.200 mm for the ferrule of the figure 13 , but the distance between the attachment points of the double spiral is identical.

[0058] The layer height of the spiral (first part) is 150 microns and the layer height of the level carrying the bearing surfaces (second part) is 500 microns.

[0059] The balance shafts have a permissible diameter between 0.5 and 0.506 mm, with a nominal value of 0.503 mm.

[0060] The graph of the figure 14 shows the evolution of the simulated holding torque M of the ferrule as a function of the balance wheel axis diameter for each of the spiral / ferrule assemblies of the figures 12, 13 And 3 , respectively. The minimum holding torque is indicated on the figure 14 via the interrupted line.

[0061] We observe, for each of the assemblies, that the holding torque is greater than the minimum required torque, even for small diameters below the minimum tolerance.

[0062] The graph of the figure 15 shows the evolution of the stress s of the ferrule as a function of the balance wheel axis diameter for each of the spiral / ferrule assemblies of the figures 12, 13 And 3 , respectively. The maximum allowable stress for the material (elastic limit, with a safety factor) is indicated by the dashed line.

[0063] It can be observed, for each of the assemblies according to the invention, that the maximum stresses are well below the maximum permissible value. The advantage of the ferrule of the figure 13 is that it is more flexible, its stress level is lower, and the slope of the torque as a function of the shaft diameter is lower than for the ferrule of the figure 12 As a corollary, the holding torque is weaker.

[0064] For the assembly according to the prior art, however, the stress very quickly exceeds the maximum permissible value. It is therefore clear that this type of ferrule is not suitable for press-fitting. Indeed, such a contour geometry does not allow for both secure retention and deformation without breakage of the ferrule following the pressing of the balance staff. Furthermore, the inscribed diameter is only 0.2 microns smaller than the lower tolerance limit so that the stresses remain below the maximum permissible stress for the lower tolerance limit, which requires extremely precise manufacturing tolerances.

[0065] The same behavior is predicted for other prior art ferrules, such as the one shown in Figure 10D of document EP 1 655 642. The increase in stress with the shaft diameter is less pronounced than in the case of the ferrule of the figure 3 , but the maximum permissible stress is nevertheless largely exceeded before reaching the upper limit of the tolerance.

[0066] This example illustrates the advantage of a closed-contour ferrule, with rigid receiving sections connected by flexible connecting sections. This difference in stiffness can be estimated as a first approximation using the theory of beams with small deformations: for a beam, the stiffness k of an element of width e, thickness h, and length L is proportional to e3 × h / L3. Assuming that the width e is constant along the sections, the ratio between the stiffness of a receiving section, kr, and a connecting section, kf, is therefore kr / kf = (er3 × hr × L3) / (ef3 × hf × L3) = (er3 × L3) / (ef3 × L3), if the thickness is identical. Reducing the average width of the connecting parts relative to the receiving parts and maximizing the length of these same connecting parts makes it possible to significantly reduce the rigidity of the connecting parts.Preferably, we choose a kr / kf ratio greater than 10, more preferably greater than 50, and even more preferably greater than 100.

[0067] Since stiffness depends on the cube of the width, the difference in width between the rigid receiving parts and the flexible connecting parts is preferable to obtain lower stiffness on the connecting parts than on the receiving parts.

[0068] Various possibilities exist to obtain lower rigidity: thus, the average width of the connecting parts can preferably be less than the average width of the receiving parts, more preferably less than by a factor of two than the average width of the receiving parts.

[0069] Alternatively or cumulatively, the two connecting parts have a minimum width and / or a width at mid-distance from the receiving parts that is less than the maximum width of the receiving parts.

[0070] The minimum width e of the connecting parts is then preferably less than 0.5×a, even more preferably equal to or less than 0.3×a, where a is the maximum width of the receiving parts.

[0071] Alternatively or cumulatively, the width in the middle of the connecting parts, halfway between the receiving parts, is preferably less than 0.7×a, even more preferably equal to or less than 0.5×a.

[0072] We can also vary the thickness of the receiving and connecting parts, in particular by thinning the connecting parts relative to the receiving parts, but it is more favorable to vary the width than the thickness to vary the rigidity.

[0073] Of course, the person in the trade will know how to adapt the dimensions of the ferrule on a case-by-case basis, according to the thickness of the spiral, the available space, ensuring sufficient torque resistance and keeping the stresses well below the maximum permissible stress in order to remain within the elastic deformation range.

[0074] The advantage of a monolithic spiral / ferrule assembly with at least two levels can be explained as follows. For a single-layer spiral / ferrule assembly, the height is determined by the spiral's dimensions, including the required torque and its overall size (diameter). The height of the ferrule, and therefore of the arms supporting the bearing surfaces and flexible parts, will necessarily be fixed by the spiral's height and cannot be freely adjusted. For a single-layer assembly 150 microns high, the holding torque values ​​are 500 / 150 lower than for a multi-layer assembly with a spiral of the same height (150 microns), since the holding force is applied over 150 microns instead of 500 microns. Consequently, these holding torque values ​​would be lower than the minimum value (dashed line on fig. 14 ) required for shaft diameters close to the minimum tolerance (0.5 micron).

[0075] It is also possible to consider having the support elements also borne by the level containing the balance spring, which, in the example mentioned above, would allow the holding torque values ​​to be increased to a ratio of 650 / 150 compared to a single-level assembly. However, the tolerances of the manufacturing process make creating continuous surfaces on two levels very difficult. It is therefore preferable to separate the functions of attaching the balance spring and connecting the ferrule to the balance staff onto two distinct levels, and to avoid providing support elements on the level that houses the ferrule attachment(s) to the balance spring.

[0076] Thus, one way to increase the holding torque of a single-layer or single-stage balance wheel is to increase the torque developed by the flexible parts without increasing the stress, which implies a larger diameter for the balance wheel. This results in the attachment point of the balance spring blades being moved further from the balance staff, which degrades the chronometric properties.

[0077] It follows from the above that a monolithic spiral / ferrule assembly with at least two levels, for example, two layers of silicon separated by a layer of silicon oxide, offers the possibility of maximizing the holding torque while optimizing its size, i.e., by avoiding an increase in the ferrule diameter. A ferrule in which the second part 103 extends, along the axis of the bore 107, over a length greater than one times the thickness E of the spiral spring, or even greater than three times the thickness E of the spiral spring, is therefore particularly suitable, especially for forming a monolithic spiral-ferrule assembly.

[0078] THE figures 6 et 7 represent variants of the monolithic spiral / ferrule assembly according to the invention.

[0079] On the figure 6 , we can see that the elastic parts are bulging in their center 30 towards the inside of the peripheral recesses.

[0080] The monolithic spiral / ferrule assembly with two stages of the figure 7 includes flexible parts that are not symmetrical.

[0081] The thermal compensation of the spiral in a single or double spiral spring-ferrule assembly is achieved using known methods. For example, a layer of material can be applied to the surface of the coils to compensate for the first thermal coefficient of the Young's modulus of the base material. In the case of a silicon spiral, a suitable material for this layer is SiO₂.

[0082] Preferably, in the various variants and embodiments, each connecting part is mainly subjected to bending stress, once the monolithic assembly is mounted on the balance shaft.

[0083] By "primarily stressed in bending", we mean that, in each connecting part, we can identify a neutral fiber oriented substantially along a direction in which the connecting part extends and separating a zone stressed in tension from a zone stressed in compression.

[0084] Preferably, in the various variants and embodiments, each connecting part has a portion distant from the balance axis of at least 0.5 times the radius of the balance axis, or even at least 0.9 times the radius of the balance axis, once the assembly is mounted on the balance axis.

[0085] Preferably, in the various variants and embodiments, the receiving and connecting parts form an element capable of continuously surrounding the balance staff, that is, capable of surrounding the balance staff without topological interruption. They thus form a closed ferrule, as opposed to a split ferrule.

[0086] In this document, "non-deformable part" or "rigid part" means a part that does not deform or does not deform significantly during operation or during assembly of the monolithic assembly on the balance shaft, or a part whose deformation is not sought and / or does not perform any function during operation or during assembly of the monolithic assembly.

[0087] In this document, "deformable part" means a part that deforms elastically during operation or during assembly of the monolithic assembly on the balance shaft or a part whose elastic deformation is sought or performs a function during operation or during assembly of the monolithic assembly.

[0088] According to one aspect of the invention, the monolithic spiral spring-ferrule assembly comprises: a first receiving part intended to bear against a balance shaft, a second receiving part intended to bear against the balance shaft, a first connecting part intended to connect the first and second receiving parts, and a second connecting part intended to connect the first and second receiving parts.

[0089] These different parts are preferably included in a ferrule.

Claims

1. Integrated hairspring-collet assembly (1) comprising: - a first accepting part (17), that suffers no or substantially no deformation during operation or during the mounting of the integrated assembly on the balance staff and that is intended to bear against a balance staff, - a second accepting part (18), that suffers no or substantially no deformation during operation or during the mounting of the integrated assembly on the balance staff and that is intended to bear against the balance staff, - a first connecting part (15) that deforms elastically during operation or during mounting of the integrated assembly on the balance staff and that is intended to connect the first and second accepting parts, - a second connecting part (16), that deforms elastically during operation or during mounting of the integrated assembly on the balance staff and that is intended to connect the first and second accepting parts, and - an element able continuously to surround the balance staff and comprising the accepting parts (17, 18) and the connecting parts (15, 16).

2. Integrated assembly according to Claim 1, wherein: - the connecting parts occupy 50% and more, or even between 50% and 90%, or even between 60% and 80%, of the total length of the exterior contour of the collet, and / or - each connecting part occupies an angular sector measured from the centre of the collet that is greater than or equal to 90°, or even comprised between 90° and 160°, or even comprised between 110° and 145°, and / or - each connecting part has a portion distant from the balance staff by at least 0.5 times the radius of the balance staff, or even by at least 0.9 times the radius of the balance staff, once the assembly has been mounted on the balance staff, and / or - the accepting parts face one another, notably being at 180° from one another with respect to the centre of the collet, and / or - each connecting part is loaded mainly in bending, once the integrated assembly has been mounted on the balance staff.

3. Integrated assembly according to one of Claims 1 to 2, wherein: - one leaf of the hairspring is attached or connected directly to an accepting part, notably, in the case of an assembly comprising a double leaf hairspring, in which each leaf is attached to a different accepting part, and / or - a central opening of the collet intended to accept a balance staff is non-circular, and / or - the contour of the central opening of the collet (1) comprises, on one same accepting part, at least one bearing surface (2, 3; 4, 5) for the balance staff.

4. Integrated assembly according to one of Claims 1 to 3, wherein the contour of the central opening of the collet (1) comprises, on one same accepting part, at least one pair of bearing surfaces (2, 3; 4, 5) for the balance staff, the tangents to the bearing surfaces (2, 3) at the points of contact of this pair making between them an angle (a) greater than 90 degrees and less than 170 degrees.

5. Integrated assembly according to one of Claims 1 to 4, wherein the contour of the central opening of the collet (1) comprises two pairs (2, 3; 4, 5) of bearing surfaces.

6. Integrated assembly according to one of Claims 1 to 5, wherein the bearing surfaces (2, 3; 4, 5) are at least partially situated on arms (6, 7; 8, 9) or extensions extending from the body of the accepting parts.

7. Integrated assembly according to one of Claims 4 to 6, wherein bearing surfaces are planar or of negative curvature or of positive curvature with a radius greater than 0.51 times the diameter (dmax) of the circle inscribed inside a central opening of the collet.

8. Integrated assembly according to one of Claims 1 to 7, wherein: - two accepting parts are positioned 180° apart with respect to the axis of the collet, and / or - the various connecting parts have identical geometries and / or the various accepting parts have identical geometries.

9. Integrated assembly according to one of Claims 1 to 8, wherein: - the hairspring is a double leaf hairspring comprising a first leaf of which the point (10) of attachment to the collet (1) is connected to a first accepting part and a second leaf of which the point (11) of attachment to the collet (1) is connected to a second accepting part, and / or - the assembly being made of silicon, possibly with an external layer and / or an internal layer of silicon oxide, and / or - the assembly being made of a fragile material or of a material that has no plastic deformation domain.

10. Integrated assembly according to one of Claims 1 to 9, the geometry of the collet of which exhibits order 2 reflection symmetry, and / or the geometry of the collet of which exhibits order 2 rotational symmetry.

11. Integrated assembly according to one of Claims 1 to 10, wherein the point(s) of attachment of the single or double leaf hairspring is (are) closer to the central opening of the collet than is the contour of the collet.

12. Integrated assembly according to one of Claims 1 to 11, the assembly comprising a collet (100) comprising a bore (101) intended to accept a balance staff, and at least a first part (102) and a second part (103), the first and second parts being separated by a plane (104) perpendicular to the axis (107) of the bore, an element (105) for attaching the collet to a hairspring being exclusively situated on the first part, and an element (106) for connecting the collet to the balance staff being essentially, and even exclusively, situated on the second part.

13. Method of manufacturing an integrated assembly according to Claim 12, wherein the hairspring is produced on a different part from that on which the surfaces whereby the collet bears against the balance staff lie.

14. Method of manufacture according to Claim 13, wherein the starting material used is an SOI wafer the layer of SiO2 of which has a thickness greater than 3 microns.

15. Oscillator comprising an integrated assembly according to one of Claims 1 to 12 and a balance staff of circular cross section.

16. Timepiece movement or timepiece comprising an integrated assembly according to one of Claims 1 to 12 or comprising an oscillator according to the preceding claim.

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