Apparatus and method for testing the mechanical properties of watch shafts

Abstract

To provide a test device for reliably testing a timepiece component with a geometry exhibiting symmetry of revolution.SOLUTION: A device for testing a timepiece shaft (1) having at least one first pivot (10, 10') and an axis of rotation (A1) includes: a rest having two supports (12, 12') intended to accommodate the timepiece shaft (1), at least one of the two supports (12, 12') being intended to accommodate the at least one first pivot (10); and an element (4) for applying a mechanical force to the timepiece shaft, positioned such that the force is at least partially taken up by the support (12, 12') at the at least one first pivot (10). The element (4) for applying a mechanical force is arranged such that the timepiece shaft (1) is driven in rotation by a relative movement of the element (4) for applying a mechanical force and the rest.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a device for testing the mechanical properties of watch shafts. The present invention also relates to a method for testing the mechanical properties of watch shafts. The present invention further relates to a method for manufacturing and / or testing watch shafts or watch movements or watches. [Background technology]

[0002] There is a need to specifically define the bending strength and tensile strength of tenons on watch shafts in order to differentiate between proposed solutions and to prove that minimum strength is guaranteed in manufactured parts.

[0003] A method known from the prior art, which allows determining the bending strength of a balance shaft, consists in clamping the shaft with a knife so that the tenon can be subjected to a radial load by static force. The longitudinal position of the knife is adjusted taking into account the shape of the watch shaft. The contact point approximately corresponds to the contact point of the shaft, specifically the tenon, with the pin in its mounting configuration in the pin. The deformation angle formed in the generatrix of the tenon due to the radial load is measured visually, for example with a goniometer. The knife is connected to a force sensor which measures the load applied to the tenon.

[0004] The device applying this method makes it possible to measure, for example, the failure angle, the failure load, and the elastic deformation limit (residual deformation angle) (Non-Patent Document 1).

[0005] While such methods are suitable for classifying metallic watch shafts, they are destructive and therefore do not allow for the definition and / or testing of shafts within a manufacturing workflow that involves systematic inspection of a significant percentage of, or even all, the parts produced. The methods also do not allow for testing over the entire periphery of a part. Therefore, they do not allow for reliable and repeatable testing of parts made from materials with failure modes that are not exposed due to the point-like nature of the applied forces.

[0006] Bending test methods have been developed, particularly for ceramics, such as the three-point or four-point test, in which a generally rectangular, monolithic test specimen is placed on a support having two contact points, and one or two loads are applied to the test specimen at predetermined distances from the two contact points with the support.

[0007] However, while these methods are useful for testing materials, they are not suitable for testing parts whose geometry is a special feature and whose properties often depend on their manufacturing history.

[0008] Furthermore, the tests were carried out in a local mode and are not representative of the stresses to which a watch shaft must be subjected over its entire circumference. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] Measurements of the fragility of tenons (Measurements of the fragility of tenons), 46th Congress of the Swiss Chronometric Society, Communication No. 4, pp. 9-10, October 1971 Summary of the Invention [Problem to be solved by the invention]

[0010] The object of the present invention is to provide a testing device that improves on the devices known from the prior art, in particular, a testing device that allows any timepiece part having a shape exhibiting rotational symmetry to be reliably defined and / or tested, such as for example a watch stem or shaft, more particularly a balance stem or escape wheel shaft, pin, axle, tube, screw or bar. [Means for solving the problem]

[0011] The test device according to the present invention is defined in claim 1.

[0012] Various embodiments of the device are defined in claims 2 to 10.

[0013] The test method according to the invention is defined in claim 11.

[0014] Various embodiments of the method are defined in claims 12 to 14.

[0015] A manufacturing and / or testing method according to the invention is defined in claim 15.

[0016] The accompanying drawings illustrate one embodiment of a test device. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram of one embodiment of a test fixture that accommodates a watch shaft. [Figure 2] FIG. 2 is a partial perspective view of an embodiment of a test device containing a watch shaft. [Figure 3] FIG. 3 is a partial cross-sectional view of an embodiment of a test fixture containing a watch shaft. [Figure 4] 4A and 4B are schematic diagrams of the support element of the test device that accommodates the clock shaft. [Figure 5] FIG. 5 is a partial cross-sectional view of an embodiment of a test fixture containing a watch shaft. [Figure 6]FIG. 6 is a perspective view of an embodiment of a test device. [Figure 7] FIG. 7 is a perspective view of an embodiment of a test device. [Figure 8] FIG. 8 is a schematic diagram of the position of the axis of the clock shaft at the start and during the test. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of the testing device 3 is described below with reference to figures 1 to 8. The device defines and / or tests the mechanical properties of a watch shaft, in particular the mechanical strength of the tenons, in particular the bending strength of the tenons or the elastic limit of the tenons.

[0019] The test device 3 or instrument or device dynamically tests the strength of, among other things, clock shafts, in particular balance or escape wheel shafts. The test device 3 is more particularly suitable for clock shafts made of ductile or brittle materials. The test device 3 includes a support that simulates the guidance of the clock shaft in a clock movement so that the dynamic test reproduces with the greatest accuracy the stresses to which the clock shaft may be exposed, for example to identify faulty clock shafts or to verify particular shaft geometries.

[0020] A watch movement contains various types of shafts, such as balance shafts or escape wheel shafts, that are exposed to mechanical stresses during operation within the movement, especially in the event of shocks. Testing device 3 tests the bending and / or shock resistance of these various watch shafts.

[0021] Clock shafts, particularly balance shafts, include tenon shanks at both ends, extended by tenons. During acceleration, particularly as a result of one or more impacts, each tenon is subjected to forces from the bearing with which it interacts. Depending on the direction of acceleration, the tenon is subjected to forces from the end stone (axial compressive load) and / or the hole stone (radial bending and / or shear load) since the stones are embedded in the bearing. For this reason, the mechanical properties of the tenon must be sufficient to resist compression relative to the end stone and bending and / or shear relative to the hole stone without exhibiting plastic deformation, crack formation, or fracture. The strength of the tenon is influenced by the material structure and the geometry of the clock shaft, in particular its dimensions, shape, and surface finish. More specifically, in the case of clock shafts made of brittle materials, local stress concentrations can propagate very quickly, even with dramatic consequences if localized at the site of an inherent material defect, such as a crack, which can lead to premature failure of the clock shaft.

[0022] The device 3 for testing clock shafts makes it possible to apply a load over the entire circumference of the clock shaft by subjecting the latter to rotation about its geometric axis during the test.

[0023] The clock shaft 1 to be defined and / or tested comprises at least one first tenon 10, 10' and a rotation axis A1. For example, the clock shaft 1 comprises a first tenon 10, a second tenon 10' and a rotation axis A1. The clock shaft is preferably a balance shaft or an escape wheel shaft. The rotation axis A1 is preferably the axis of a shaft shape that exhibits rotational symmetry.

[0024] Test device 3 is - a base 2 including two supports 12, 12' intended to receive a clock shaft 1 at its two ends, at least one of the two supports 12, 12' intended to receive at least one first tenon 10; an element 4; 4' which applies a mechanical force to the clock shaft, at least substantially perpendicular to the axis of rotation A1, said force being at least partly absorbed by a support 12 in at least one tenon 10; - means 7, 43; 43' for displacing one or the other of the base 2 and the element 4; 4', applying a mechanical force perpendicular to the axis A1, displacing the base and the element relative to each other in a plane perpendicular to the applied force; Includes:

[0025] Furthermore, the element 4;4' for applying a mechanical force may be an element 4;4' for driving the clock shaft 1 in rotation relative to the base 2 about the axis of rotation A1.

[0026] In other words, the testing device comprises a base 2 comprising two supports 12, 12' and elements 4, 4' for applying mechanical forces to the clock shaft 1, which place the clock shaft 1 under mechanical stress by means of a relative displacement of the base 2 with respect to the elements 4, 4', driving the clock shaft in rotation. Preferably, only one or the other of the base 2 and the elements 4, 4' for applying mechanical forces to the machine shaft 1 is moved relative to the geocentric reference system. Alternatively, the base 2 and the elements 4, 4' for applying mechanical forces to the clock shaft 1 are movable relative to the geocentric reference system.

[0027] The test device 3 advantageously comprises: - means for checking the force applied to the clock shaft 1, for example one or more force sensors integrated into the supports 12, 12' and / or into the elements 4; 4' applying mechanical forces to the clock shaft 1; - means for controlling the displacement and position of the clock shaft 1 and / or the element 4; 4' exerting a mechanical force on the clock shaft 1 relative to the support 12, 12', for example one or more drivers or actuators 7, 43; 43'; - means for checking the absolute or relative position of the element 4; 4' exerting a mechanical force on the clock shaft 1 relative to the clock shaft 1 and / or the support 12, 12', for example one or more position sensors (not shown) and / or visualization means 8; - optionally lighting means E, - Management and Records Unit 9; Further includes: The position / displacement control means and the position inspection means make it possible to realize feedback control of the position / displacement.

[0028] As will be explained in detail in one embodiment, the clock shaft 1 is displaced in rotation about the axis A1 by rolling, preferably by rolling without sliding, under the influence of the mechanical force-imparting elements 4, 4'. A relative rolling movement of the clock shaft 1 is generated by the mechanical force-imparting elements 4, 4'. This causes the clock shaft 1 to pivot relative to the supports 12, 12' under the influence of the mechanical force-imparting elements 4, 4'. In said movement, the clock shaft 1 pivots on the supports 12, 12'.

[0029] The supports 12, 12' are part of a mount 2 designed to adapt to the particular shape of the clock shaft 1 in order to support it, preferably horizontally, and preferably by imitating the swivel means, i.e. bearings, with which the clock shaft is intended to cooperate. In other words, in this embodiment, an attempt is made to reproduce on the supports as accurately as possible the swivel conditions faced by a clock shaft mounted in a clock movement.

[0030] The arrangement of the supports 12, 12' and the force-applying elements is determined by the shape of the clock shaft 1. After these initial positions have been defined and adjusted, the test device 3 makes it possible to test several shafts having the same shape in succession.

[0031] The supports 12, 12' may be identical or different. If the tenons 10, 10' of the clock shafts are identical, the supports 12, 12' are preferably identical as well.

[0032] When the clock shaft is fitted on the mount 2, the axis A1 of the clock shaft is preferably parallel to the axis x, in particular to the horizontal axis x. The axes y and z are perpendicular to the axis x and to each other. Finally, the axis z is preferably vertical. The axes x, y and z are preferably in an orthogonal reference system.

[0033] In the exemplary embodiment shown, the base 2 is designed to support the balance stem 1 in a horizontal position on its two tenons 10, 10'. The clock shaft 1 is free to pivot about a horizontal axis x defined by the support, which corresponds to the axis A1 when the clock shaft is resting on the base.

[0034] For simplicity, only support 12 will be described here, since supports 12, 12' have identical shapes.

[0035] The support 12 includes a notch 122 dimensioned to receive the tenon 10 of the watch shaft 1 .

[0036] Advantageously, the notch 122 has dimensions and a shape corresponding to half of a bearing intended to cooperate with the clock shaft 1 in order to guide the clock shaft in horizontal rotation. In particular, the notch 122 has a contact area suitable for contacting a tenon of the clock shaft 1. The contact area may be, for example, cylindrical or olive-shaped, so as to resemble as closely as possible the contact area of ​​the bearing of the movement intended to accommodate the clock shaft 1. To this end, the support 12 may comprise a tenon stone (hole stone) or a tenon half-stone for accommodating the tenon. Alternatively, the support may simply have a structure substantially identical to the half-stone or substantially identical to the stone, machined into the material of the support 12.

[0037] As shown in Fig. 4A, the support 12 advantageously comprises two V-shaped guide surfaces 121 that fit into the notches 122. The two guide surfaces form an angle between 10° and 180°, for example 90°, so that the clock shaft 1 can be easily fitted in. Alternatively, the support 12 does not have guide surfaces, but has an angle greater than 180° below the notch 122, as shown in Fig. 4B, so that the clock shaft 1 can be fitted onto the notch 122 in an automated manner, for example. Of course, the support 12 may have any shape that allows the notch 122 to be formed.

[0038] In a variant, if the two supports 12, 12' are different, one of the two supports 12, 12' has a hole into which one of the two tenons is inserted, the hole advantageously having the same diameter as the hole in the perforated stone it imitates. The other support part has a notch 122 as described above.

[0039] In another variant, the two supports 12, 12' each have a hole with the same diameter as the hole in the perforated stone that the hole in the support imitates. In this variant, at least one of the supports 12, 12' is movable along the axis x to allow for the axial adjustment. The clock shaft 1 is adjusted in several steps: inserting the first tenon 10 into the hole in the first support 12; temporarily holding the clock shaft 1 in a horizontal position and translating the second support 12' along the axis x to match the hole in the second support 12' with the second tenon 10'; calibrating the relative positions of the supports 12, 12' to optimize the hold of the clock shaft 1 (avoiding gaps, applying a predetermined force along the shaft axis, etc.).

[0040] Furthermore, the support 12, 12' may have multiple notches 122 and / or multiple holes so that multiple watch shafts of the same or different shapes can be tested in succession.

[0041] The cross section of the support 12 in the direction of the axis x is defined so as to determine the bearing area or bearing point of the tenon 10. By way of example, the notch 122 comprises a surface in the shape of a post of revolution to simplify the manufacture of the support 12. The length of the bearing area is preferentially greater than 10% of the length of the tenon in the direction of the axis x. The length of the bearing area is ideally between 10% and 90%, or between 15% and 80%, or between 20% and 60% of the length of the tenon in the direction of the axis x. Alternatively, the notch 122 comprises a radially progressive surface of revolution (or a non-cylindrical surface of revolution) to limit the bearing surface of the tenon 10 on the support 12. The bearing area of ​​the tenon preferably consists of a bearing point corresponding to the smallest diameter of the olive stone or olive half-stone within which the tenon 10 is to pivot.

[0042] In addition to the supports 12, 12', the base 2 preferably comprises stops 13, 13' which serve to limit the axial clearance of the clock shaft 1. These stops 13, 13' thus make it possible to control very precisely the bearing area or bearing point of the tenons 10, 10' on the supports 12, 12'. Consequently, the testing device preferably comprises at least one axial stop 13, 13' intended to limit the displacement of the clock shaft 1 along the axis x.

[0043] The shape of the surface of the stop that is brought into contact with the tenon is preferably selected to resemble the shape of the endstone that it imitates. The shape may be concave, convex, or flat. In addition, one and / or the other of the stops may be elastic or spring back to facilitate the performance of the test.

[0044] The stops 13, 13' may be in the form of plates having a thickness sufficient to make them functional. The stops may have a thickness on the scale of micrometers, millimeters or centimeters. The stops may have a thickness of, for example, 200 μm. Alternatively, the stops 13, 13' may be integrated into the support 12, 12' and implemented via machining of a more complex notch 122 and the adjacent area.

[0045] The materials of the support 12 and stop 13 are selected to most closely mimic the clock movement bearings in which the clock shaft 1 is intended to be guided. These materials should preferably have tribological properties that prevent wear while preventing any deterioration of the surface integrity of the clock shaft 1 to be defined and / or tested, in particular during demonstration experiments. The support 12 and / or stop 13 may be made of the same material as the clock movement bearings in which the clock shaft 1 is intended to be guided, for example ruby, ceramic, hard metal alloys, cuprous alloys, precious metals, or any other suitable material, for example nickel or nickel (Ni) alloys, in particular nickel-phosphorus (NiP) alloys.

[0046] The support 12 and the stop 13 may be made of the same material or different materials.

[0047] The support 12 is made, for example, of nickel (Ni) and is manufactured using LiGA technology, so that, as a variant, the support 12 can incorporate a hole or semi-hole made of ruby, which can be inserted during the LiGA manufacturing process.

[0048] The fastener 13 is made of, for example, nickel (Ni) and is manufactured from LiGA, so that, as a variant, the fastener 13 can incorporate a ruby ​​hole piece that can be inserted during the LiGA manufacturing.

[0049] The surfaces of the support 12 and / or stop 13 that are intended to come into contact with the clock shaft 1 to be defined and / or tested may optionally be provided with a suitable coating or surface treatment. The coating or surface treatment may, for example, be applied only to the surfaces of the support 12 and / or stop 13 that are intended to come into contact with the tenon of the clock shaft 1. Other surfaces of the support or stop may also have such a coating or surface treatment.

[0050] The supports 12 and stops 13 are provided to be easily replaceable in order to adapt the base 2 to the size or type of clock body 1 or to correct wear of these elements by replacing the supports 12 and / or stops 13.

[0051] The supports 12, 12' and the stops 13, 13' are assembled on positioning units U, U' on the platform 2. These units incorporate force sensors which measure the forces absorbed by the supports 12, 12' during the test.

[0052] Each of the units U and U' is preferably independently movable in the plane xy to allow positioning of the clock shaft on the support, including adjustment of the gap between the stops 13, 13', and to allow positioning of the axle shaft 1 relative to the elements 4; 4' which apply mechanical forces to the clock shaft. Alternatively, the units U and U' are integral. The units U and U' are preferably displaceable together in the plane xy to allow positioning of the axle shaft 1 relative to the elements 4; 4' which apply mechanical forces to the clock shaft, in particular during testing.

[0053] An independent adjustment of the units U and U' along the axis z is optionally provided to adapt the clock shaft to the test as required or to allow customization of the horizontal position of the clock shaft during the test.

[0054] The units U and U' are optionally displaceable together along the axis z in order to apply a force F, in particular during testing, to the bearing points of the clock shaft on the supports 12, 12' and to the element 4 which applies a mechanical force to the clock shaft. The displacement may be driven or not.

[0055] The element 4;4' for applying a mechanical force to the clock shaft comprises a rigid structure arranged to abut the clock shaft 1, in particular against a surface 42 of the clock shaft 1, in particular against the rotation surface 42 of the axis A1. The surface 42 of the clock shaft is cylindrical or frustoconical. The element 4;4' for applying a mechanical force to the clock shaft 1 is preferably arranged to exert a force perpendicular or substantially perpendicular to the axis A1. The force is preferably a vertical or substantially vertical force, directed along the axis z.

[0056] Thus, the element 4, 4' for applying a mechanical force to the clock shaft is designed to apply a force to a clock axle resting on the support 12, 12'. In the following, with reference to the illustrated embodiment, the element 4 for applying a mechanical force to the clock shaft may also be more specifically referred to as a "knife".

[0057] The end 41 of the knife 4 in contact with the clock shaft is dimensioned such that its thickness in the direction of the axis x of rotation of the shaft ensures that the forces exerted on the surface 42 of the clock shaft 1 are transmitted accurately in supports 12, 12' so that they can be absorbed by the tenons 10, 10' of the clock shaft 1.

[0058] Furthermore, the end 41 of the knife 4 that contacts the clock shaft is dimensioned in length so that relative displacement of the knife 4 and the base 2 allows the clock shaft to be rotated.

[0059] The length of the end 41 of the knife 4 in the direction y perpendicular to the axis of rotation A1 of the shaft is at least equal to the circumference of the surface 42. The length is advantageously 1.5 times the circumference of the surface 42 of the shaft, so as to be able to support, load, and generate at least one revolution of the shaft, or a multiple of the circumference of the surface 42 plus 0.5 times the circumference, so as to be able to carry out several measurement revolutions. The length of the end 41 is, for example, between 0.5 mm and 150 mm. This means that the knife 4 has a length that allows it to achieve at least one revolution of the clock shaft 1 when displacing the knife 4 on the clock shaft 1 without slipping along the complete movement of the knife 4.

[0060] The knife 4 should be sufficiently rigid so as not to deform significantly and to maintain the integrity of its shape during the test.

[0061] The knife 4 is thus made of a suitable material in order to best transmit forces to the clock shaft 1. The end 41 is designed to rotate the clock shaft 1 (due to friction at the contact surface between the end 41 and the clock shaft) when the knife is moved relative to the balance shaft or when the base 2 is moved relative to the knife in a translational movement along the direction y perpendicular to the axis A1 of the clock shaft being defined and / or tested, without damaging the surface 42 of the clock shaft.

[0062] The end 41 is preferably made of a reinforced or non-reinforced polymer or composite material, for example of rubber, elastomer, polypropylene, polycarbonate, polymethyl methacrylate, photopolymerizable resin, nylon, etc. This means that the surface 42 of the watch shaft 1 cannot be damaged during the measurement, ensuring that the watch shaft 1 rotates due to the displacement of the knife on the shaft surface. A certain degree of flexibility of the end 41 optimizes the effective contact surface between the knife and the defined and / or tested watch shaft, preventing peaks in the contact pressure values.

[0063] The material of the knife is preferably selected so that the coefficient of friction between the clock shaft and the knife is greater than or equal to 0.3.

[0064] The knife may be in one piece or in several parts, for example it may have a hard core and be provided with a softer coating or surface treatment on at least part of its surface, in particular on its end 41 which is suitable for contact with the watch shaft to be defined and / or tested.

[0065] As shown in Figures 6 and 7, the knife 4 may be mounted on a support structure 5 suitable for optimizing the transfer of the applied force.

[0066] Alternatively, the element applying the mechanical force may comprise a gear 4' rotatable about an axis parallel to the axis A1, in which case the displacement of the base 2 and / or the support structure 5 makes it possible to position the gear in contact with the surface 42 of the clock shaft 1 relative to one another.

[0067] During the test, a force is applied by displacement of the base 2 or the support structure 5 along the axis z. The driven rotation of a gear (driven by means of an actuator 43'), which is of a similar nature (shape, material of the periphery 41') as the rotation by the knife 4, drives the clock shaft 1. This displaces the gear 4' relative to the base 2. Alternatively, the base 2 may incorporate a rotating support 12, 12'.

[0068] An exemplary embodiment of the knife 4 is shown in Figure 5. The cross section of the knife, in a cross section in the plane xz, has the shape of a right triangle, whose first side 48 is parallel to the axis z (and perpendicular to the axis of rotation A1 of the shaft) and whose second side 49 forms an angle θ with the first side 48. The cross section of the knife thus has an angle θ at the end 41 intended to come into contact with the watch shaft 1. The angle θ is between 1° and 30°. For example, the angle is 10°.

[0069] Said shape is advantageous for positioning the knife as close as possible to the tenon 10 without interference with the support 12 and / or without a possible change in the diameter of the clock shaft 1. The knife 4 is placed on the surface 42 of the clock shaft 1 at a predetermined distance from the contact point or contact area of ​​the tenon 10 on the support 12 so that the distribution of the force exerted by the knife 4 on the two supports 12, 12' can be calculated exactly.

[0070] Alternatively, the cross-section of the knife, in the plane xz, has the shape of an isosceles triangle with an apex angle θ′, θ′ being between 1° and 30°. Alternatively or additionally, the cross-section of the knife may have a square, polygonal or rounded cross-section.

[0071] In order to be able to subject at least one tenon 10, 10' to pressure over its entire circumference, the test requires that the base 2 and the knife 4 are moved relative to one another so as to drive the clock shaft 1 in rotation while a force F is continuously applied to the surface 42 of the clock shaft.

[0072] In a preferred embodiment, the stage 2 is placed on a driven structure suitable for displacing the stage 2 precisely in the horizontal plane xy. The test fixture 3 comprises a first actuator for displacing the stage 2 along the axis x and a second actuator for displacing the stage along the axis y.

[0073] The driven structure allows the base 2 to be positioned precisely towards the knife 4 in order to ultimately allow contact of the end 41 of the knife 4 with the surface 42 of the watch shaft 1 and to allow relative displacement between the knife 4, which is held in a fixed position, and the base 2 in order to carry out the test.

[0074] In the variant with gear 4', support structure 5 is complemented by an actuator that rotates gear 4' about an axis parallel to shaft axis A1. In this variant, rotation of gear 4' replaces translation of knife 4 relative to the table during testing. Everything described herein for an embodiment including knife 4 applies equally to the embodiment including gear 4'.

[0075] Alternatively, the stage 2 may be fixed and the knife movable along the axis y during testing.

[0076] For example, the relative motion of the base 2 and the knife 4 along the axis y is defined to reproduce the speeds and accelerations to which the clock shaft 1 is intended to be exposed in a clock movement. As a result, the speed of the knife along the axis y may be non-constant during its movement.

[0077] The support structure 5 with the knife 4 or gear 4' is driven along axis z relative to the frame 99 of the test device 3 so as to allow the knife 4 or gear 4' to be positioned relative to the clock shaft 1 in order to place the end 41 of the knife 4 or gear 4' on the surface 42 of the clock shaft 1 and subsequently to apply a force to the clock shaft 1 during the test. The frame is a fixed frame, in other words it is intended to be held in a fixed position relative to a geocentric reference system during normal use, and in particular during the test.

[0078] In addition to or as an alternative to the preferred embodiment, the support structure 5 may be drivable along three axes x, y and z using three actuators to position the end 41 of the knife 4 relative to the clock shaft 1 solely by displacement of the support structure 5.

[0079] In addition to or as an alternative to the preferred embodiment, the stage 2 may be drivable along three axes x, y and z using three actuators to position the end 41 of the knife 4 relative to the clock shaft 1 by displacement of the stage 2 alone.

[0080] In a preferred embodiment, the force exerted by the knife 4 is controlled by the displacement of the structure 5 along the axis z. The knife 4 and / or the support structure 5 are optionally connected to a force sensor that measures the force exerted on the clock shaft. The force absorbed by the knife 4 corresponds to the total load exerted on the clock shaft. The force may be constant or variable during the test. The force is typically between 0 and 10 N.

[0081] Alternatively, the knife 4 is fixed along the axis z and the application of the force F is provided by the displacement of the table 2 along the axis z.

[0082] The force applied by the knife 4 is feedback controlled in a control loop during measurement to maintain the desired force within a predetermined tolerance during the test, regardless of any irregularities that may be present on the periphery of the surface 42.

[0083] The base 2 is displaced along the axes x and y in order to position the clock shaft 1 vertically below the end 41 of the knife 4, in particular to place the surface 42 below the end 41 of the knife 4. This displacement can be done manually or automatically. A magnifying system or a camera checks the relative positions of the knife 4 and the clock shaft 1.

[0084] In the illustrated embodiment, when the end 41 of the knife 4 contacts the clock shaft 1 and a force F is applied, the base 2 is displaced along the axis y so as to rotate the clock shaft 1 .

[0085] Of course, any other combination of displacements that allows relative movement of the knife 4 and the table 2 is also possible.

[0086] The displacement of the table 2 and the knife 4 or gear 4' is controlled by a management and recording unit 9, which also collects data from force sensors integrated into the support structure 5 and supports 12, 12' of the knife 4 or gear 4'. Displacement velocity and acceleration are typically between 0 and 3 m / s and 0 and 85 m.s, respectively. -2 is.

[0087] The management and recording unit thus integrates data from various sensors or instruments measuring, for example, the following parameters: - the position of the knife 4 relative to a given frame of reference and / or relative to the clock shaft 1 to be tested, - the displacement of the knife 4 relative to the clock shaft 1 to be tested along the axis z, - the displacement of the table 2 in the plane xy, more specifically in the direction y, - The power absorbed by Knife 4, - the forces absorbed by the supports 12, 12'.

[0088] From these measurements, the management and recording unit: - the speed of rotation of clock shaft 1 around axis A1, - rotational acceleration of clock shaft 1 around axis A1, - the angle of rotation of clock shaft 1 around axis A1, can be calculated.

[0089] The control and recording unit 9 defines the test parameters and the test sequence. The measurement results are recorded, in particular the force as a function of the relative position of the table 2 and the knife 4. In the case of strength tests, the relative failure angle and the failure load are recorded. The relative failure angle is the angle A1 between the horizontal axis x and the end of the tenon at the moment of failure, as shown in Figure 8. r is the angle between

[0090] The measurement of the angle of rotation of the clock shaft 1 about its axis A1 ensures, inter alia, that the clock shaft 1 rotates at least one full revolution during the entire displacement of the knife 4, so that the clock shaft 1 is tested over its entire circumference. If appropriate, said measurement makes it possible to determine the number of revolutions performed by the clock shaft 1.

[0091] An embodiment of a method for testing a watch shaft 1 including at least one first tenon 10, 10' is described below.

[0092] The method includes the following steps. a) positioning the clock shaft 1 so that it rests on the supports 12, 12' with at least one first tenon 10 and one second tenon 10' or with at least one first tenon 10 and one surface of the shaft; b) applying a force F to the clock shaft 1 at the surface 42, at least substantially perpendicular to the axis of rotation A1, with the end 41 of the knife 4, so that the applied force is at least partly or mainly or almost completely or completely absorbed by the support 12 at the at least one first tenon 10; c) Due to the contact established between the end 41 of the knife and the surface 42 of the clock shaft 1, the relative movement of the knife 4 and the support 12 drives the clock shaft 1 in rotation about the axis of rotation A1.

[0093] The method also advantageously comprises, during the step of applying a force and / or the step of moving the clock shaft 1, a measuring step, which comprises: - measurement of the forces transmitted through the bearing surfaces of the tenons 10, 10' on the supports 12, 12' and absorbed by the supports 12, 12', and / or - measurement of the angular position of the clock shaft 1 around the axis x, and / or - measuring the degree of deformation of the clock shaft 1, and / or - measurement of the position and / or amplitude of the displacement of the knife 4, Includes:

[0094] In the particular case of a demonstration experiment, the method may not include a measurement step, but simply a structure to which a force F is applied during testing.

[0095] The applied force F is preferably controlled and checked as a function of a fixed-point value, where the fixed-point value is constant and / or defined by a function, in particular by a function consisting of gradually and / or gradually increasing the force and / or determining the fixed-point value as a function of the displacement of the knife 4.

[0096] During the above steps a) and b), the knife 4 is placed in contact with the watch shaft 1 to be tested so that its end 41 is in contact with a defined surface 42 of the watch shaft 1 and so that the knife 4 can apply a force perpendicular to the axis of rotation A1 of the watch shaft 1 against a precise portion of the watch shaft, for example against the tenon shank. The initial position of the knife 4 along axis y is adjusted taking into account the diameter of the watch shaft 1 to be tested and the length of the end 41 of the knife 4. By means of a displacement of the support structure 5 along axis z, the knife 4 is placed in contact with the watch shaft 1 with an initial force F0 perpendicular and perpendicular to the axis of rotation A1 of the shaft, which initial force is measured by a force sensor, in particular a force sensor positioned on the support structure 5. The approach may initially be performed visually, using optical devices such as a magnifying glass or other suitable devices such as a camera 8, to ensure the positioning of the knife relative to the surface 42, and then the load may be adjusted by the management and recording unit 9 so that the load is gradually and precisely applied up to the predetermined force F. The knife 4 is also connected to a position sensor to check its spatial position.

[0097] The above steps b) and c) are preferably carried out simultaneously. The end 41 of the knife 4 is preferably placed on the surface 42 of the clock shaft, and the base 2 is moved in translation tangential to said surface along the axis y, thereby making it possible to rotate the clock shaft 1 by rolling due to friction. The rolling is advantageously carried out without slippage. The rotation speed of the clock shaft 1 is proportional to the displacement speed of the knife 4 relative to the base 2 along the axis y.

[0098] By checking the rotational speed of the clock shaft 1 and the acceleration of the translational movement of the knife, it is possible to rotate and / or monitor the rotation of the clock shaft.

[0099] Alternatively, the base 2 is fixed and the knife 4 is moved in translation along the axis y, so as to rotate the clock shaft 1 .

[0100] Alternatively, the base 2 and the support structure 5 are fixed and the gear 4' rotates, causing the clock shaft 1 to rotate.

[0101] The base 2 and / or knife 4 are movable in relative translation in two directions along the axis y so that the clockshaft pivots clockwise or counterclockwise around the axis A1. Depending on the relative movement performed by the base 2 and / or knife 4, the clockshaft 1 pivots on itself a partial rotation, a full rotation, or more. The clockshaft 1 preferably pivots at least one rotation so that the entire circumference of the tenon is tested. By way of example, the clockshaft pivots at least two or more complete rotations, one rotation clockwise and a second rotation counterclockwise, or vice versa.

[0102] The force required to rotate the clock shaft is, inter alia: - the ratio between the diameter of the tenon 10 to be tested and the diameter of the surface 42 of the clock shaft at the place where the knife 4 is located, the nature of the contact surfaces of the end 41 of the knife 4 and the clock shaft 1 (coefficient of friction and / or rolling resistance), and the nature of the contact surfaces of the support 12, 12' and the tenon 10, 10' of the clock shaft 1 (coefficient of friction and / or rolling resistance); It is determined depending on.

[0103] The coefficient of friction between the knife 4 and the clock shaft 1 is preferably greater than 0.3.

[0104] More specifically, the test can be carried out according to the following steps, with the fixed points of force adapted to the purpose of the test. E1. Select the elements of the units U and U' (supports 12, 12'; stops 13, 13') according to the dimensions of the clock axle to be tested; E2. Position the previously assembled units U and U' on platform 2; E3. Position the clock shaft 1 on the supports 12, 12' so that it can rotate freely; E4. Position the end 41 of the knife 4 in contact with the surface 42 of the watch shaft 1 to be tested at a predetermined distance from the bearing point of the tenon 10 on the support 12; E5. Stress and displacement fixed points, e.g. a force F exerted by the knife 4 on the clock shaft 1, which corresponds to the position of the knife 4, in particular along the axis z, - the displacement movement of the table 2 or the knife 4, which determines the number of rotations to be measured; - the displacement speed of the base 2 or the knife 4, which determines the rotation speed of the clock shaft; Initiate the trial by granting; E6. At the same time as step E5, various parameters, e.g. the evolution of the force exerted by the knife 4 as a function of the displacement of the knife 4 and / or the angle of rotation of the clock shaft 1 and / or the time, - angular position of clock shaft 1, - the force measured at the support 12, 12' or at the knife 4, - the force exerted when the clock shaft broke, Measure and record.

[0105] The applied force may be the only force applied for the duration of the test, may be gradually or progressively increased with each back and forth movement of the knife, or may be configured according to a defined protocol.

[0106] During step E6, the forces exerted on at least one tenon 10 or two tenons 10, 10' are preferably measured and recorded via sensors located on the units U, U' of the base 2 and / or on the knife 4. This involves recording the respective development of the forces as a function of the relative displacement of the base 2 and the knife 4 and / or the rotation of the clock shaft 1.

[0107] Each of the tenons 10, 10' can be tested independently by displacing the knife 4 in the direction x to position it along the axis of rotation A1 of the clock shaft 1 as close as possible to the tenon 10, 10' to be tested so as to load the knife 4 primarily on the bearing of the tenon 10 or 10'.

[0108] The fitting of the clock shaft 1 to the base 2 and the access of the knife 4 is facilitated by the use of visualization means 8, such as a stereo microscope with or without eyepieces, a CCD camera, or other suitable device.

[0109] The visualization means 8 are suitable for carrying out inspections and / or measurements of the positioning of the clock shaft 1 on the base.

[0110] Illumination means E may optionally complement the visualization means 8. The illumination means E may be separate from the visual inspection device or integrated into said device.

[0111] The test described above may have two purposes: on samples taken from the test, the maximum strength limit at break of a batch of watch shafts can be determined, i.e., it can be used for strength tests. The test can also be used for demonstration experiments to eliminate watch shafts with defects that could lead to premature failure due to the theoretical forces that the watch shaft must withstand, and for fatigue tests to test the behavior of the watch over time.

[0112] In a strength test, the force applied to the clock shaft 1 is increased until the clock shaft breaks.

[0113] In the demonstration experiment, the force applied to the clock shaft 1 is predetermined to be equal to or greater than the force corresponding to the normal stress load during use, but to be kept below the theoretical maximum allowable value of the material. The clock shaft 1 does not need to break after the test.

[0114] In a fatigue test, a predetermined force is applied to the clock shaft 1 for a long, determined duration.

[0115] An embodiment of a method for manufacturing and / or testing a clock shaft 1 or a clock movement or a clock is described below.

[0116] The method includes the steps of carrying out the test method described above.

[0117] By carrying out the method, a tested or inspected clock shaft 1, or clock movement or clock, is obtained.

[0118] Although a testing device and method for watch movement shafts has been described herein, they can be applied to any watch shaft, regardless of its nature or its function, and to any part with rotational symmetry, such as a pin, pinion, axle, tube or bracelet bar.

[0119] Although the present specification describes an apparatus and method for testing a clock shaft having two tenons, it is applicable to any clock shaft, particularly a clock shaft having a single tenon.

[0120] The testing apparatus and methods described herein are particularly suited to testing watch shafts made of ductile materials, especially steel or high performance or high entropy alloys, but they can also be used to test watch shafts made of other materials, such as amorphous alloys, glass, ruby, ceramics, metal matrix or ceramic matrix composites, or materials containing carbon fiber.

[0121] In the test method, the force is preferably applied to the clockshaft while it is rotating. This makes it possible to load the clockshaft at all angular positions around its axis A1. However, the described test device and the described test method alternatively make it possible to carry out tests in which a load is applied to the clockshaft only at a finite, defined number of positions around its axis. For this reason, the above-mentioned steps b) and c) are alternated with a test force F, and during the driving step c) only a minimum force Fm is applied that is necessary to drive the clockshaft in rotation. This means that the clockshaft is not rotating when the test force F is applied, and therefore a mechanical load is applied to the clockshaft in a stationary state.

[0122] The solution of the present invention is preferably realized simply by means of the rolling phenomenon of the surface 42 of the watch shaft 1 under the edge of the knife 4, - mechanical loading, and - Rotational drive of the clock shaft, This combination provides a means for defining a watch part with rotational symmetry of the clock shaft type. For this purpose, the knife 4 is moved relative to the clock shaft 1 in the tangential direction of the clock shaft 1, in particular by means of a displacement of the mount 2 on which the clock shaft 1 is placed.

[0123] The testing method and device according to the invention make it possible to test a watch shaft over the entire circumference of one of its cross sections. This makes the solution particularly useful for testing watch shafts made of materials that are sensitive to localized defects, since it prevents the test from being carried out at a strategic position around the shaft and ensures that any defects are loaded and detected regardless of where they are located on the circumference of the tested shaft. The solution can therefore be used on watch shafts regardless of their construction material. [Explanation of symbols]

[0124] 1 clock shaft 2 units 3 Test equipment 4. Elements that apply mechanical force 7 Second Actuator 10 Tenon 12 Supports 13 Fasteners 41 End 43 First Actuator 99 frames

Claims

1. A device (3) for testing a clock shaft (1) comprising at least one first tenon (10, 10') and an axis of rotation (A1), said device comprising: a mount (2) comprising two supports (12, 12') intended to accommodate the clock shaft (1), at least one of the two supports (12) intended to accommodate the at least one first tenon (10); an element (4; 4') for applying a mechanical force to the clock shaft, the element (4; 4') being positioned so that the force is at least partially absorbed by the support (12) at the at least one first tenon (10); Including, The element (4; 4') for applying a mechanical force is arranged in such a way that the clock shaft (1) is driven in rotation by the relative movement of the element (4; 4') for applying a mechanical force and the base (2).

2. the relative movement of the element (4; 4') exerting a mechanical force on the mount (2) is a displacement along a direction perpendicular or substantially perpendicular to the axis (A1) of the clock shaft (1), and / or the mechanical force on the clock shaft is at least substantially perpendicular to the axis of rotation (A1); A test device (3) according to claim 1.

3. The device comprises: a fixed frame (99); a first actuator (43; 43') for driving the element (4; 4') that applies the mechanical force to the fixed frame (99), and / or a second actuator (7) for driving the platform (2) relative to the fixed frame (99); Including, A test device (3) according to claim 1 or 2.

4. the device is arranged so that the relative movement of the element (4; 4') exerting a mechanical force on the mount (2) results in at least 1 rotation or at least 1.5 rotations of the clock shaft (1) around the axis of rotation (A1); A test device (3) according to any one of claims 1 to 3.

5. the at least one support includes a notch (122, 122') that receives the at least one first tenon (10, 10'); A test device (3) according to any one of claims 1 to 4.

6. at least one support comprises a half-hole or hole-stone bearing element for the pivoting of said at least one first tenon (10, 10') relative to said at least one support; A test device (3) according to any one of claims 1 to 5.

7. at least one axial stop (13, 13') intended to limit the displacement of the clock shaft (1) along the axis of rotation (A1); A test device (3) according to any one of claims 1 to 6.

8. said element (4; 4') for applying a mechanical force is in the form of an edge and comprises an end (41) intended to come into contact with said clock shaft (12); A test device (3) according to any one of claims 1 to 7.

9. The end (41) reinforced or unreinforced polymers, or composite materials, or Rubber, or elastomer, or Polypropylene (PP), or Polycarbonate (PC), or Polymethyl methacrylate (PMMA), or photopolymerizable resin, or nylon Made of Test device (3) according to claim 8.

10. the edge is formed by two planes forming an angle between 1° and 30°, preferably 10°, and / or the edge has a length between 0.9 mm and 150 mm; Test device (3) according to claim 8 or 9.

11. A method for testing a clock shaft (1) comprising at least one first tenon (10, 10') and an axis of rotation (A1), said method comprising: placing said clock shaft (1) against a mount (2) comprising two supports (12, 12') intended to accommodate said clock shaft (1), at least one of said two supports (12) intended to accommodate said at least one first tenon (10); a step of applying a mechanical force (F) to the clock shaft (1), said force being applied so as to be at least partially absorbed by the support (12, 12') at the at least one first tenon (10, 10'), said mechanical force (F) being applied by means of an element (4; 4') for applying a mechanical force to the clock shaft (1); moving the element (4; 4') applying a mechanical force relative to the base (2) in such a way that the relative movement of the element (4; 4') applying a mechanical force and the base (2), in particular the translational movement of the element (4; 4') applying the mechanical force to the surface (42) of the clock shaft (1), drives the clock shaft (1) in rotation about the axis of rotation (A1); A test method comprising:

12. During the step of applying a mechanical force and / or during the step of moving, the mechanical force applied to the clock shaft (1), and / or said movement of said clock shaft (1), is measured, The test method according to claim 11.

13. said mechanical force (F) being applied to said clock shaft (1) according to a predefined fixed point force; 13. The test method according to claim 11 or 12.

14. the mechanical force (F) is applied to the clock shaft (1) such that the force is at least substantially perpendicular to the axis of rotation (A1); 14. The test method according to any one of claims 11 to 13.

15. A method for manufacturing and / or testing a watch shaft (1), comprising carrying out a test method according to any one of claims 11 to 14.

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