EP4310598A1 - Verfahren zur kontrolle und herstellung von uhrwerk-spiralfedern - Google Patents

Verfahren zur kontrolle und herstellung von uhrwerk-spiralfedern Download PDF

Info

Publication number
EP4310598A1
EP4310598A1 EP22185552.1A EP22185552A EP4310598A1 EP 4310598 A1 EP4310598 A1 EP 4310598A1 EP 22185552 A EP22185552 A EP 22185552A EP 4310598 A1 EP4310598 A1 EP 4310598A1
Authority
EP
European Patent Office
Prior art keywords
hairspring
thermal coefficient
blank
resonance
frequency
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP22185552.1A
Other languages
English (en)
French (fr)
Inventor
Kevin SOOBBARAYEN
Susana Tobenas
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Richemont International SA
Original Assignee
Richemont International SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Richemont International SA filed Critical Richemont International SA
Priority to EP22185552.1A priority Critical patent/EP4310598A1/de
Priority to PCT/EP2023/069829 priority patent/WO2024017847A1/fr
Publication of EP4310598A1 publication Critical patent/EP4310598A1/de
Pending legal-status Critical Current

Links

Images

Classifications

    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B17/00—Mechanisms for stabilising frequency
    • G04B17/04—Oscillators acting by spring tension
    • G04B17/06—Oscillators with hairsprings, e.g. balance
    • G04B17/066—Manufacture of the spiral spring
    • G—PHYSICS
    • G04—HOROLOGY
    • G04D—APPARATUS OR TOOLS SPECIALLY DESIGNED FOR MAKING OR MAINTAINING CLOCKS OR WATCHES
    • G04D7/00—Measuring, counting, calibrating, testing or regulating apparatus
    • G04D7/10—Measuring, counting, calibrating, testing or regulating apparatus for hairsprings of balances
    • G—PHYSICS
    • G04—HOROLOGY
    • G04D—APPARATUS OR TOOLS SPECIALLY DESIGNED FOR MAKING OR MAINTAINING CLOCKS OR WATCHES
    • G04D7/00—Measuring, counting, calibrating, testing or regulating apparatus
    • G04D7/12—Timing devices for clocks or watches for comparing the rate of the oscillating member with a standard
    • G04D7/1257—Timing devices for clocks or watches for comparing the rate of the oscillating member with a standard wherein further adjustment devices are present
    • G04D7/1271—Timing devices for clocks or watches for comparing the rate of the oscillating member with a standard wherein further adjustment devices are present for the control mechanism only (from outside the clockwork)

Definitions

  • the present invention relates to the field of control and manufacturing of parts for watchmaking.
  • the invention relates more particularly to a method for controlling and manufacturing watch spiral springs, otherwise called resonators.
  • the movements of mechanical watches are regulated by means of a mechanical regulator or oscillator comprising a resonator, that is to say an elastically deformable component whose oscillations determine the running of the watch.
  • a mechanical regulator or oscillator comprising a resonator, that is to say an elastically deformable component whose oscillations determine the running of the watch.
  • Many watches include, for example, an oscillator comprising a hairspring as a resonator, mounted on the axis of a balance wheel and set into oscillation thanks to an escapement.
  • the natural frequency of the balance-spring couple makes it possible to regulate the movement of the watch and depends on several parameters, in particular the stiffness of the balance-spring and the operating temperature.
  • the stiffness of the hairspring also defines its intrinsic vibrational characteristics, such as the natural frequency and resonance frequencies.
  • the natural frequency of an elastic system is the frequency at which this system oscillates when it is in free evolution, that is to say without an exciting force.
  • a resonance frequency of an elastic system is a frequency at which a local maximum of displacement amplitude can be measured for a given point of the system elastic.
  • the displacement amplitude follows an upward slope before this resonance frequency, and follows a downward slope after, in all point which does not correspond to a vibration node.
  • the recording of the displacement amplitude as a function of the excitation frequency presents a displacement amplitude peak or resonance peak which is associated with or which characterizes the resonance frequency.
  • the natural frequency of the regulating member formed by the hairspring of stiffness R coupled to a balance wheel of inertia I is in particular proportional to the square root of the stiffness of the hairspring.
  • the main specification of a spiral spring is its stiffness, which must be within a well-defined interval to be able to be paired with a balance wheel, which forms the inertial element of the oscillator. This pairing operation is essential to precisely adjust the frequency of a mechanical oscillator.
  • silicon spirals can be manufactured on a single wafer using micro-manufacturing technologies. It is particularly known to produce a plurality of silicon resonators with very high precision using photolithography and machining/etching processes in a silicon wafer.
  • the methods for producing these mechanical resonators generally use monocrystalline silicon wafers, but wafers made of other materials can also be used, for example polycrystalline or amorphous silicon, other semiconductor materials, glass, ceramic, carbon, carbon nanotubes or a composite comprising these materials.
  • monocrystalline silicon belongs to the cubic crystal class m3m whose thermal expansion coefficient (alpha) is isotropic.
  • the characteristics of the oscillator are as stable as possible, in order to have a rate of the watch which is also stable, with in particular as few differences in rate as possible depending on the operating temperature (summer -winter, wristwatch worn or not worn).
  • Silicon has a very negative value of the first thermoelastic coefficient, and consequently, the stiffness of a silicon resonator, and therefore its natural frequency, varies greatly depending on the temperature.
  • the documents EP1422436 , EP2215531 And WO2016128694 describe a spiral type mechanical resonator made from a core (or two cores in the case of WO2016128694 ) in monocrystalline silicon and whose temperature variations in Young's modulus are compensated by a layer of amorphous silicon oxide (SiO2) surrounding the core (or cores), the latter being one of the rare materials presenting a positive thermoelastic coefficient .
  • SiO2 amorphous silicon oxide
  • thermal coefficient CT which depends in particular on the thermal coefficient of Young's modulus, the thermal coefficient of expansion of the hairspring and the thermal coefficient of expansion of the balance wheel.
  • the silicon hairsprings and their thermo-compensation therefore make it possible to adjust the terms of equation 5 relating to the hairspring to obtain a thermal coefficient CT of the oscillator.
  • the final functional yield will be given by the number of hairsprings whose stiffness corresponds to the pairing interval, divided by the total number of hairsprings. spirals on the plate.
  • the micro-fabrication and more particularly etching steps used in the manufacture of hairsprings on a wafer typically result in a significant geometric dispersion between the dimensions of the hairsprings on the same wafer, and therefore in a significant dispersion between their stiffness, notwithstanding that the engraving pattern is the same for each hairspring.
  • the measured stiffness dispersion normally follows a Gaussian distribution. In order to optimize manufacturing yield, we are therefore interested in centering the average of the Gaussian distribution on a nominal stiffness value and also in reducing the standard deviation of this Gaussian.
  • the documents WO2015113973 And EP3181938 propose to remedy this problem by forming a hairspring with dimensions greater than the dimensions necessary to obtain a hairspring of a predetermined stiffness, by measuring the stiffness of this hairspring formed by coupling it with a balance wheel equipped with a predetermined inertia, by calculating the thickness of material to be removed to obtain the dimensions necessary to obtain the hairspring with the predetermined stiffness, and by removing this thickness from the hairspring.
  • the document EP3181939 proposes to remedy this same problem by forming a hairspring according to dimensions smaller than the dimensions necessary to obtain a hairspring of a predetermined stiffness, by determining the stiffness of this hairspring formed by coupling it with a balance wheel equipped with a predetermined inertia, by calculating the thickness of material to be added to obtain the dimensions necessary to obtain the hairspring with the predetermined stiffness, and by adding this thickness of material to the hairspring.
  • the stiffness dispersion curve Rd1, Rd2, etc. can be refocused in relation to a nominal stiffness value Rnom.
  • the present invention aims to propose an approach free from the above drawbacks, which allows a faster production flow and/or with less risk of pollution(s), and/or greater sampling, and/or a more precise measurement of the thermal coefficient of the Young's modulus (CTE) of the hairspring and/or of the thermal coefficient (CT) of a watch system including the hairspring, and therefore a more individualized correction of the hairsprings of the plate to obtain watch systems including walking is little or not disturbed by temperature variations.
  • CTE Young's modulus
  • CT thermal coefficient
  • the method according to the implementation above comprises a step of vibratory excitation of the hairspring or the hairspring blank and the measurement of a characteristic of a resonance frequency, to then deduce by prediction a thermal coefficient of the Young's modulus (CTE) of the hairspring and/or a thermal coefficient (CT) of a watch system including the hairspring.
  • CTE Young's modulus
  • CT thermal coefficient
  • the vibration excitation is applied to the part or the unitary blank, not coupled to any balance, weight or oscillating system.
  • the process makes it possible to control unitary and free parts (that is to say with at least one free end, not attached to any mechanism or balance), which provides at least the advantages of productivity gains (no assembly with an oscillating system), gains in quality (no pollution of parts, no breakage, and more parts can be tested within the same budget), gains in precision (no errors linked to other components of 'an oscillating system).
  • the determination of the thermal coefficient of the Young's modulus (CTE) of the hairspring or of the hairspring blank by the method according to the invention is well suited for oxidized parts for which the thickness of the balance is not precisely known. oxide layer at this stage of the manufacturing process.
  • CTE Young's modulus
  • the vibration excitation can be carried out with a shock device which applies excitation to the part to be tested in a relatively short time.
  • a shock device which applies excitation to the part to be tested in a very short time (over a period of less than a second, less than 500 ms, less than 100 ms, less than 10 ms).
  • the shock device can apply a shock to the balance spring or to its support to make the parts vibrate.
  • An impact hammer or any device with a moving mass can be used.
  • provision can be made to apply the shock to the plate, or to a fixture supporting the plate.
  • the parts begin to vibrate and we can record the vibration response over time, to extract resonance peaks and their frequencies from this measurement, for example with a Fourrier transform.
  • the vibration excitation is applied to the hairspring or to the hairspring blank having a free end (typically the central ferrule) and another end fixed to the plate or to a clamp.
  • a free end typically the central ferrule
  • the vibratory excitation is applied to a mass (located at the center of gravity of the hairspring) connected to a frame of reference (a gripping pliers for a hairspring alone, or the rest of a substrate or a plate for a blank, for example made of silicon and not detached) by a spring (the elastic part of the hairspring).
  • the vibrational excitation sets the suspended mass in motion.
  • the method according to the implementation above therefore makes it possible to test spiral blanks during manufacture while limiting the risks of pollution or assembly errors. A dimensional correction (section, height and/or thickness) and/or additional treatment(s) are then possible.
  • the method according to the implementation above also makes it possible to test completed hairsprings for example to carry out a classification by increments of stiffness, or to plan a pairing with a particular balance wheel.
  • the first resonant frequency is used to determine a parameter different from the thermal coefficient of the Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system comprising the hairspring , such as for example stiffness or a defect in the hairspring or the hairspring blank.
  • the second resonance frequency is used to determine the thermal coefficient of Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system comprising the hairspring.
  • the first vibrational excitation step makes it possible to determine a stiffness or the presence of a defect
  • the second vibrational excitation step makes it possible to determine the thermal coefficient of the Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system.
  • CTE Young's modulus
  • CT thermal coefficient
  • a planar resonance mode is a resonance mode in which the different parts of the hairspring or the hairspring blank move mainly in the plane of the part at rest. If this plane is defined by directions X and Y, with a direction Z normal to the plane, then the displacements in X or Y are greater than or equal to the displacements in Z. In an out-of-plane resonance mode, the displacements in Z are greater than or equal to the displacements in X or Y, and preferably the displacements in Z are two to three times greater than the displacements in It is seen that an oxidized part can present significantly different frequencies of out-of-plane resonance modes compared to the same non-oxidized parts. Consequently, to predict a thermal coefficient of Young's modulus (CTE) of the hairspring and/or a thermal coefficient (CT) of a watch system including the hairspring precisely, it may be preferable to take into account a resonance mode out of plan.
  • CTE Young's modulus
  • CT thermal coefficient
  • step b. may consist of identifying a characteristic of a resonance frequency sensitive to the thermal coefficient of the hairspring or the hairspring blank.
  • the frequency range of the spectrum obtained does not only depend on the source of vibration excitation but also on the sensor of the measuring instrument used.
  • the frequency range is linked both to the excitation frequency range and to the frequency range over which the measurement instrument the amplitude of oscillation (vibrometer or other) is sensitive.
  • the excitation frequency range will be chosen so as to include at least one resonance frequency of the hairspring or blank tested.
  • the predetermined resonance frequency that the hairspring must present once finished can be a target natural frequency or a target resonance frequency, or a target natural frequency range, or a target resonance frequency range defined by a tolerance around a target value.
  • the characteristic of a resonance frequency is a characteristic of the oscillatory response measured over a predetermined frequency range, comprising at least one resonance frequency.
  • a characteristic is typically identified after processing a raw measurement signal (for example measurement of the amplitudes or speeds or accelerations of movement of certain points of the hairspring or of the hairspring blank), the processing being able to include for example a transform of Fourier to identify resonance peaks and therefore resonance frequencies.
  • the method can determine a thermal coefficient of the Young's modulus (CTE) of the hairspring and/or a thermal coefficient (CT) of a watch system comprising the hairspring to classify the part, and/or to predict a pairing with other particular components and/or to then calculate/deduce a dimensional correction and/or additional treatment(s) to be applied to obtain a thermal coefficient of the target Young's modulus (CTE) of the hairspring and/or a coefficient thermal (CT) target of a watch system including the hairspring.
  • CTE Young's modulus
  • CT coefficient thermal
  • the frequency range is applied simultaneously to a plurality of hairsprings or hairspring blanks.
  • the speed is improved, because it is typically possible to impose the vibrational excitation on a plate supporting several hundred hairspring blanks, which would for example still be attached to the plate.
  • the hairspring can have at least two expected predetermined resonance frequencies, and the frequency range is predetermined to cover at least the two expected predetermined resonance frequencies. By covering or sweeping a wide frequency range, multiple resonance peaks (or resonant frequencies) can be measured, which can provide greater accuracy.
  • step a comprises the use of a source, such as a piezoelectric source, making it possible to induce or impose acoustic excitation on a edge of a plate supporting the spiral blank , or preferably on, or even under the hairspring or the hairspring blank to be specifically excited.
  • a source such as a piezoelectric source
  • the acoustic source can be coupled to an excitation cone chosen to excite at least one hairspring or a hairspring blank.
  • the acoustic source can be coupled to an excitation cone chosen to excite at least part and preferably all of the spiral blanks.
  • step b comprises the use of an optical measuring means, such as a laser Doppler effect vibrometer.
  • step b can be based on a measurement over time of an amplitude or a speed or an acceleration of movement of at least one point of the balance spring or of the blank of spiral, preferably carried out at least partially during step a.
  • the characteristic of the resonant frequency can be identified based on the width of the resonance peak, at half height of the maximum value of the resonance peak.
  • step b comprises a step of processing the measurement signal with for example a Fourier transform, to identify resonance peaks of displacement amplitude or speed or acceleration, and/or of phase, depending on the excitation frequency.
  • the thermal coefficient prediction machine can be a calculation machine for predicting or calculating from the frequency characteristics the thermal coefficient of the Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system including the hairspring.
  • the prediction machine is not a regulated or self-regulated or feedback loop system for adjusting a resonant frequency in response to measurement and comparison with a target value.
  • the thermal coefficient prediction machine can implement a classification carried out for example by a neural network to predict the thermal coefficient of the Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system including the hairspring.
  • CTE Young's modulus
  • CT thermal coefficient
  • the thermal coefficient prediction machine can implement a regression method, for example a linear regression to predict the thermal coefficient of the Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system including the hairspring.
  • a regression method for example a linear regression to predict the thermal coefficient of the Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system including the hairspring.
  • the thermal coefficient prediction machine can implement a classification based on partitioning into k-means or k-medians to predict the thermal coefficient of the Young's modulus (CTE) of the hairspring and/or or the thermal coefficient (CT) of a watch system including the hairspring.
  • CTE Young's modulus
  • CT thermal coefficient
  • control method may comprise a preliminary step consisting of taking into account the material of the hairspring or the hairspring blank, and of adjusting a maximum amplitude of the vibrational excitation and/or a frequency range of the predetermined frequency range depending on the material of the hairspring or the hairspring blank.
  • step c. determines that the thermal coefficient of the Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system comprising the hairspring is outside a range of expected values
  • the method may comprise at least one step consisting of identifying or isolating or retouching or discarding the hairspring or the hairspring blank.
  • step c. determines that the thermal coefficient of the Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system comprising the hairspring is outside a range of expected values
  • the method may comprise at least one step consisting of defining a step of processing the hairspring or the hairspring blank, such as a thermo-compensation, oxidation or deoxidation step, to obtain the thermal coefficient of the Young's modulus (CTE) of the hairspring and /or the thermal coefficient (CT) of a watch system including the hairspring in the range of expected values
  • step a. is carried out for a plurality of hairsprings or hairspring blanks attached to a plate, and if step c. determines that the thermal coefficient of Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system comprising the hairspring is outside a range of expected values for first hairsprings or first blanks of hairsprings and included in the range of expected values for second hairsprings or second hairspring blanks, then we can plan to detach only the second hairsprings or second hairspring blanks and provide a step of processing the first hairsprings or first hairsprings of hairspring blanks, such as a thermo-compensation, oxidation or deoxidation step, to obtain the thermal coefficient of Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a system watchmaker including the hairspring within the range of expected values.
  • CTE Young's modulus
  • CT thermal coefficient
  • step a and step b are repeated at least several times for the same measuring point of the hairspring or the hairspring blank.
  • step a and step b are synchronized.
  • Such synchronization provides the possibility of detecting a phase shift, or an attenuation, or a coupling whose taking into account can improve the precision of the prediction, or make it possible to adjust or realign the source of vibration excitation.
  • the manufacturing process may comprise a step consisting of: C/ identify or isolate or retouch or discard the hairspring or the hairspring blank formed during step A/, if step c. determines that the thermal coefficient of Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system including the hairspring is outside a range of expected values.
  • CTE Young's modulus
  • CT thermal coefficient
  • the hairspring blank can be formed on a plate, with a plurality of other hairspring blanks.
  • THE figures 3A-3F are a simplified representation of a method of manufacturing a mechanical resonator 100 on a plate 10.
  • the resonator is in particular intended to equip a regulating member of a timepiece and, according to this example, is in the shape of a silicon spiral spring 100 which is intended to equip a balance wheel with a mechanical watch movement.
  • Plate 10 is illustrated in Figure 3A as an SOI wafer (“silicon on insulator”) and comprises a substrate or “handler” 20 carrying a sacrificial layer of silicon oxide (SiO 2 ) 30 and a layer of monocrystalline silicon 40.
  • the substrate 20 may have a thickness of 500 ⁇ m
  • sacrificial layer 30 may have a thickness of 2 ⁇ m
  • silicon layer 40 may have a thickness of 120 ⁇ m.
  • the monocrystalline silicon layer 40 can have any crystalline orientation.
  • lithography we mean all the operations making it possible to transfer an image or pattern on or above the wafer 10 to the latter.
  • the layer 40 is covered with a protective layer 50, for example made of a polymerizable resin.
  • This layer 50 is structured, typically by a photolithography step using an ultraviolet light source as well as, for example, a photo mask (or another type of exposure mask) or a stepper and reticle system. This structuring by lithography forms the patterns for the plurality of resonators in layer 50, as illustrated in Figure 3C .
  • the patterns are machined, in particular engraved, to form the plurality of resonators 100 in the layer 40.
  • the etching can be carried out by a deep reactive ion etching technique (also known by the acronym DRIE for “Deep Reactive Ion Etching”). . After etching, the remaining part of the protective layer 50 is subsequently eliminated.
  • the resonators are released from the substrate 20 by locally removing the sacrificial layer 30 or even by etching all or part of the silicon from the substrate or handler 20. Smoothing (not illustrated) of the etched surfaces can also take place before the release step, for example example by one step thermal oxidation followed by a deoxidation step, consisting for example of wet etching based on hydrofluoric acid (HF).
  • HF hydrofluoric acid
  • the turns 110 of the silicon resonator 100 are covered with a layer 120 of silicon oxide (SiO2), typically by a thermal oxidation step to produce a thermo-compensated resonator.
  • This layer 120 which generally has a thickness of 2-5 ⁇ m, also affects the final stiffness of the resonator and therefore must be taken into account during the previous steps to obtain vibrational characteristics of the hairspring leading to obtaining a particular natural frequency of the hairspring-balance couple in a given watch mechanism.
  • the different resonators formed in the wafer generally have a significant geometric dispersion between them and therefore a significant dispersion between their stiffnesses, notwithstanding that the stages of formation of the patterns and the machining/engraving through these patterns are the same for all resonators.
  • the above description relates to silicon resonators 100, but we can consider making the resonators in glass, ceramic, carbon nanotubes, or even metal.
  • the metal hairspring or detached from the plate is pinched or taken as a reference by a tool which positions it opposite the emission source and the displacement measuring device.
  • the stiffness of the hairspring can be measured in a so-called static manner, that is to say without putting the hairspring into oscillation, but by determining its torque.
  • An alternative to the method described in this last document consists of carrying out a torque measurement using a rheometer, as marketed by the company Anton Paar.
  • a device provided for this purpose is illustrated on the Figure 4 .
  • the spring 200 it makes it possible to arrange the spring 200 to be evaluated on a mounting 202, and to position it so that it can be fixed at the level of its last turn by a holding member 204. Once the last turn fixed, the installation 202 is distant from the hairspring 200 which is thus completely free from any elastic constraint.
  • the head of the rheometer 206 is then positioned opposite the ferrule of the hairspring.
  • the present invention proposes to determine at least one characteristic of a resonance frequency of a sample of resonators 100 on the wafer in step 3F, to deduce a thermal coefficient of the Young's modulus (CTE) of the hairspring and/or a thermal coefficient (CT) of a watch system comprising the hairspring and possibly in step 3E, to deduce a stiffness and/or a structural defect.
  • CTE Young's modulus
  • CT thermal coefficient
  • the invention proposes to determine at least one characteristic of a resonance frequency of a sample of resonators by vibration measurement and apply a predictive method (for example a digital model or a classification or categorization method) to connect the result of said vibration measurement to the identification of the thermal coefficient of the Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system comprising the hairspring.
  • a predictive method for example a digital model or a classification or categorization method
  • the result of the prediction can be used to validate produced parts, and/or decide on additional processing to correct the thermal coefficient of Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system comprising the hairspring and/or scrapping non-compliant parts in terms of thermal coefficient of Young's modulus (CTE) of the hairspring and/or thermal coefficient (CT) of a watch system including the hairspring.
  • CTE Young's modulus
  • CT thermal coefficient
  • control process into a manufacturing process to obtain parts capable of reaching, maintaining, generating a particular and predetermined natural oscillation frequency and independent of temperature variations, once the resonators are each coupled to a balance wheel of a given watch mechanism.
  • the measurements can be carried out following a particular sampling, for example according to a sampling range of 4, 2 or 1 Hz.
  • a sampling range of 4, 2 or 1 Hz for example, the resolution for processing the acquisition data according to for example a Fourier transform depends directly from the duration of this acquisition.
  • a signal sampling frequency of at least 600 kHz if the frequency range extends up to 300 kHz for example.
  • FIG. 5 schematically represents a silicon wafer 25 on which a plurality of spiral blanks 200 are formed.
  • a source of vibration excitation 400 is coupled to the wafer 25, so as to be able to impose vibration excitation. Consequently, each hairspring blank 200 will begin to vibrate, and a laser vibrometer 300, here focused on a point of the right-hand hairspring blank 200, will be able to measure the vibration amplitudes of the measuring point over time.
  • a laser vibrometer 300 here focused on a point of the right-hand hairspring blank 200, will be able to measure the vibration amplitudes of the measuring point over time.
  • the laser vibrometer 300 can be moved to another measuring point on the balance spring blank 200, or move to another balance spring blank 200 on the plate 25. Of course, one can alternatively move the balance spring blank 200. 'spring blank 200 compared to the laser vibrometer.
  • FIG. 6 represents an example of vibrational excitation over time.
  • the excitation frequency varies over time, between 0 Hz and 50 kHz (but we can plan to go up to 300 kHz), and we can impose a succession of rising edges, each spaced of a period of rest without excitement.
  • we can impose a plurality of rising edges between 2 rising edges and 60 rising edges, each lasting between 0.5 s and 2 s for example.
  • a step can be provided consisting of identifying points of the resonator for which the vibration response is significant. Indeed, in the case of a hairspring to which a vibration is imposed, especially if the frequency varies over time, the vibration response will cause nodes to appear on the hairspring, that is to say particular points of the hairspring whose amplitude of movement is small or zero. If a displacement measurement is made at a point on the hairspring that turns out to be a node at a particular frequency(ies), the identification of resonant frequency characteristics will be negatively affected.
  • a preliminary step of measuring displacement on a plurality of predetermined points of the hairspring for example at least ten predetermined points, preferably at least twenty predetermined points, and very preferably at least thirty of predetermined points.
  • this preliminary step of measuring amplitude on the predetermined points we can plan to identify resonance frequencies for each measurement point, and then a step of selecting reference points for which the measurement of amplitude of displacement during excitation shows that they are not nodes at these resonant frequencies.
  • the identified nodes present, at at least one resonant frequency, a displacement amplitude of zero or less than a first threshold peak value, and these points forming nodes are separated from the reference points to be considered for subsequent measurements.
  • the reference points are different depending on the position of the balance spring blank 200 on the plate 25.
  • the ferrule can be considered non-deformable during vibrational excitation and all the points of the ferrule exhibit similar displacements/movements/vibrations. Consequently, a small error in locating the measuring point on the ferrule will have little impact on the final result.
  • a step can be provided consisting of giving a particular orientation to the direction of excitation and/or the direction of measurement.
  • a measurement direction or an axial direction of a laser beam from the measuring device perpendicular to the part to be tested to maximize the precision of measurement of displacements perpendicular to the plane formed by the part at rest.
  • a measurement direction or an axial direction of a laser beam from the measuring device inclined relative to the part to be tested to maximize the precision of measuring the displacements contained in the plane formed by the part at rest.
  • this preliminary sampling makes it possible to test single parts in good conditions (measurement errors and interference are limited) to choose the best test conditions for the parts that remain attached to the substrate.
  • the area of the curve located between 25% and 75% of the maximum amplitude value of the resonance peak has better precision than the part above 75% (typically the peak), which offers better precision on the exact frequency of determined resonance. For example, we can take the middle of the segment connecting the two points halfway up the resonance peak to determine the resonance frequency associated with the peak in question.
  • FIG. 7 represents an example of a vibration spectrum for a point of a balance spring 200 of the Figure 5 free of defects, reconstructed from measurements of the displacement amplitude of the measuring point considered in response to the vibratory excitation of the Figure 6 , between 10 kHz and 15 kHz.
  • between 10 and 250 amplitude peaks can typically be identified if the vibrational excitation sweeps over a frequency range between 0 Hz and 300 kHz. Each peak amplitude has a resonant frequency, and peak amplitudes vary greatly.
  • FIG 8 represents in detail the processing that can be done on an amplitude peak for a part free of defects, that at 11 kHz for example.
  • the goal is to find the resonant frequency and give it as precise a value as possible. Instead of basing this treatment on the maximum value of the peak, the applicant realized that better precision could be achieved by determining the length of the segment connecting the rising part and the falling part of the curve, halfway up the peak.
  • the resonant frequency typically being the value in the middle of this segment.
  • FIG. 9 represents, for the example of an amplitude peak at approximately 10 kHz, the amplitude peaks constructed for around ten hairspring blanks 200 tested. It can be noted that from one spiral blank to another, the frequency position of the amplitude peak varies (from approximately 9.8 kHz to 10.02 kHz), and that the maximum displacement amplitude varies in a ratio of 1 to 5 approximately. Since the tops of amplitude peaks are not truly symmetrical, it may be wise to determine the resonant frequency based on the width of the peak at half height. We can also use the width of the peak at half height to determine damping, and compare this damping to a reference value.
  • an optional first measurement can be carried out on the parts described Figure 3E to estimate the stiffness of non-oxidized parts, to determine whether dimensional correction is required or not.
  • the invention proposes to make a second measurement to determine a thermal coefficient of the Young's modulus (CTE) of the hairspring and/or a coefficient thermal (CT) of a watch system including the hairspring.
  • CTE Young's modulus
  • CT coefficient thermal
  • Two alternatives can be implemented.
  • a predetermined balance directly to the resonator still attached to the plate, and measure a natural frequency of oscillation of the resonator - balance wheel couple to compare this natural frequency with an expected natural frequency and above all calculate the real stiffness or actual dimensions based on equations 1 to 3 above.
  • a second alternative we can finish manufacturing the resonators tested, in order to mount or couple them with a balance wheel individually to measure here again a natural frequency of oscillation of the resonator - balance wheel couple.
  • the stiffness can also be deduced from a measurement of reaction torque at the shell using a rheometer.
  • the acquired signal represents the evolution of the torque as a function of the amplitude. Analysis of the slope of this curve for low amplitudes (linear part) makes it possible to deduce the stiffness, and then the dimensions of the resonator bar. We can then determine the dimensions of the hairspring bar.
  • a high-resolution 3D X-ray tomography approach would make it possible to extract point clouds giving the 3D material density of the hairsprings, and, through appropriate image reconstruction, a map of the hairspring section.
  • These different types of data make it possible to deduce the dimensions of the bar from the bar and to estimate the stiffness of the hairspring using a geometric approach.
  • Another approach consists of analyzing the forced oscillations of a hairspring on a reference balance wheel with an escapement.
  • a laser measurement of the passage times of the balance arms (point clouds), as presented above, makes it possible to measure the frequency and deduce the stiffness.
  • An alternative can be considered based on an acoustic acquisition (Witschi type microphone) which records the shocks of the different operating phases of the escapement/anchor system.
  • the measured data are either point clouds of the moments of passage of the balance arms, or the temporal evolution of the sound pressure level.
  • reference data To be able to predict the stiffness, reference data must first be established or constructed, such as a reference spectrum.
  • oscillation amplitude measurements are carried out on physical resonators, and resonance frequencies are identified.
  • this database can be constructed from numerical simulations on a finite element model of a hairspring. These simulations make it possible to generate reference spectra or oscillation periods associated with stiffnesses.
  • This database can also be supplemented by experimental measurements by measuring vibration spectra, oscillation periods and the positions of hairsprings on the plate as well as their associated stiffnesses.
  • One of the advantages of this approach lies in the fact that the training database is enriched as the tests are carried out. This can make it possible to have an adaptive model depending on the plates and hairsprings and contributes to the reduction of the standard deviation in stiffness on the plates.
  • This database can be used to build a prediction model, and several solutions are offered.
  • a digital model for example polynomial, to calculate, as a function of a resonant frequency value, a real thickness, a dimensional correction or a real stiffness.
  • a neural network for example a perceptron
  • a classification according to stiffness or dimensions of the bar, the classes being able to be defined by increments of values.
  • the learning phase includes a test phase (excitation of resonators with measurement of vibration characteristics to reconstruct a vibration spectrum and identify resonance frequencies).
  • a phase of measuring the stiffness and/or dimensions of the resonator bar is also carried out.
  • the established prediction model has good sensitivity, that is to say that for two different input values, the model gives two distinct output values.
  • the sensitivity of the prediction model was not the same for all the resonance peaks.
  • the slope coefficient is 0.0015 10 -7 N.mm/Hz.
  • the leading coefficient could be larger for high resonance frequencies, which provides better prediction sensitivity, to predict distinct stiffness or dimensional correction values, even from close resonance frequency values.
  • the resonance modes in particular the modes of deformation and/or movement of the resonators
  • the resonance modes could differ significantly, which can also affect the sensitivity of the prediction of stiffness and/or dimensional correction. It is advantageous to provide, during the learning phase, a step of comparing the sensitivity of the prediction to choose to subsequently consider this or that resonance frequency and not another to predict as precisely as possible a stiffness and /or a dimensional correction depending on the vibration response.
  • the learning phase makes it possible to choose either resonance peaks at high frequencies and/or resonance peaks which correspond to particular resonance modes making it possible to predict precise and reliable values, and the frequency range will be predetermined. to include at least one resonance peak and preferably several, to be able to make either a a single prediction as precise as possible, or several predictions (one per resonance peak deemed interesting) to then carry out cross-checking, averages or even adjustments of the predicted values.
  • the control process can typically be carried out on hairspring blanks made on a plate and still attached to this plate, so as to estimate the stiffness and/or the dimensions of the bar of the hairsprings of the sample, in order to determine whether a correction dimension is to be provided.
  • the correction step then consists of adding material, as for example described in the document EP3181939 aforementioned.
  • the method consisting of identifying resonant frequencies by imposing vibratory excitation on the hairspring blanks alone, makes it possible to quickly obtain measurement data, without having to, for example, carry out assembly operations on a balance wheel, while limiting measurement errors. measure because only the hairspring blank is tested (there are no errors that could be linked to the balance, such as its mass, its mounting position, etc.).
  • the resonant frequency was significantly affected by different oxidation values (implying variations in the thermal coefficient of the Young's modulus (CTE) of the hairspring and therefore variations in the thermal coefficient (CT) of a watch system including the hairspring) for certain resonance modes only.
  • Step 3 can be carried out by detaching the parts measured in step 1 and mounting them in a reference movement, and the progress of these movements can be measured according to the three temperatures 8°C, 23°C, 38° vs.
  • a thermal coefficient prediction machine can use it to predict, for example from resonance frequency data for an out-of-plane resonance mode having a high resonance frequency, the thermal coefficient of Young's modulus (CTE) of the hairspring and/or the thermal coefficient (CT) of a watch system including the hairspring.
  • CTE Young's modulus
  • CT thermal coefficient
  • the thermal coefficient prediction machine can receive as input the reference of the watch device in question, or its value or contribution to the thermal coefficient.
  • the different parameters which intervene in the CT of the movement are constant and do not constitute adjustment variables.
  • CT thermal coefficient
  • thermo-compensation step oxidation and/or deoxidation
  • the data taken from the vibration response and used for these predictions of stiffness or presence of defects are not necessarily the same as those for the prediction of thermal coefficient and we can even consider that in a preferred manner, the data taken from the vibration response and used are different and distinct from those for the prediction of the thermal coefficient.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
EP22185552.1A 2022-07-18 2022-07-18 Verfahren zur kontrolle und herstellung von uhrwerk-spiralfedern Pending EP4310598A1 (de)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP22185552.1A EP4310598A1 (de) 2022-07-18 2022-07-18 Verfahren zur kontrolle und herstellung von uhrwerk-spiralfedern
PCT/EP2023/069829 WO2024017847A1 (fr) 2022-07-18 2023-07-17 Procédé de controle et de fabrication de ressorts spiraux d'horlogerie

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP22185552.1A EP4310598A1 (de) 2022-07-18 2022-07-18 Verfahren zur kontrolle und herstellung von uhrwerk-spiralfedern

Publications (1)

Publication Number Publication Date
EP4310598A1 true EP4310598A1 (de) 2024-01-24

Family

ID=82655325

Family Applications (1)

Application Number Title Priority Date Filing Date
EP22185552.1A Pending EP4310598A1 (de) 2022-07-18 2022-07-18 Verfahren zur kontrolle und herstellung von uhrwerk-spiralfedern

Country Status (2)

Country Link
EP (1) EP4310598A1 (de)
WO (1) WO2024017847A1 (de)

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH281496A (de) * 1949-01-04 1952-03-15 Smith & Sons Ltd S Einrichtung für das selbsttätige Regulieren der Frequenz eines Systems Unruhe-Spiralfeder.
EP1422436A1 (de) 2002-11-25 2004-05-26 CSEM Centre Suisse d'Electronique et de Microtechnique SA Spiraluhrwerkfeder und Verfahren zu deren Herstellung
EP2215531A1 (de) 2007-11-28 2010-08-11 Manufacture et fabrique de montres et chronomètres Ulysse Nardin Le Locle SA Mechanischer oszillator mit einem optimierten thermoelastischen koeffizienten
CN103105769A (zh) * 2011-11-09 2013-05-15 天津海鸥表业集团有限公司 一种摆轮游丝系统周期及摆幅光电测量仪
WO2015113973A1 (fr) 2014-01-29 2015-08-06 Cartier Création Studio Sa Ressort spiral thermocompensé en céramique comprenant l' élément silicium dans sa composition et son procédé de réglage
WO2016128694A1 (fr) 2015-02-13 2016-08-18 Tronic's Microsystems Oscillateur mécanique et procédé de réalisation associe
EP3181939A1 (de) 2015-12-18 2017-06-21 CSEM Centre Suisse d'Electronique et de Microtechnique SA - Recherche et Développement Herstellungsverfahren einer spiralfeder mit einer vorbestimmten steifigkeit durch zugabe von material
EP3181938A1 (de) 2015-12-18 2017-06-21 CSEM Centre Suisse d'Electronique et de Microtechnique SA - Recherche et Développement Herstellungsverfahren einer spiralfeder mit einer vorbestimmten steifigkeit durch wegnahme von material
JP6486697B2 (ja) * 2014-02-26 2019-03-20 シチズン時計株式会社 ひげぜんまいの製造方法及びひげぜんまい
EP3654111A1 (de) 2018-11-15 2020-05-20 Nivarox-FAR S.A. Verfahren zur messung des drehmoments einer spiralfeder einer uhr
EP3845770A1 (de) * 2019-09-16 2021-07-07 Sigatec SA Verfahren zur herstellung von uhrwerk-spiralfedern

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH281496A (de) * 1949-01-04 1952-03-15 Smith & Sons Ltd S Einrichtung für das selbsttätige Regulieren der Frequenz eines Systems Unruhe-Spiralfeder.
EP1422436A1 (de) 2002-11-25 2004-05-26 CSEM Centre Suisse d'Electronique et de Microtechnique SA Spiraluhrwerkfeder und Verfahren zu deren Herstellung
EP2215531A1 (de) 2007-11-28 2010-08-11 Manufacture et fabrique de montres et chronomètres Ulysse Nardin Le Locle SA Mechanischer oszillator mit einem optimierten thermoelastischen koeffizienten
CN103105769A (zh) * 2011-11-09 2013-05-15 天津海鸥表业集团有限公司 一种摆轮游丝系统周期及摆幅光电测量仪
WO2015113973A1 (fr) 2014-01-29 2015-08-06 Cartier Création Studio Sa Ressort spiral thermocompensé en céramique comprenant l' élément silicium dans sa composition et son procédé de réglage
JP6486697B2 (ja) * 2014-02-26 2019-03-20 シチズン時計株式会社 ひげぜんまいの製造方法及びひげぜんまい
WO2016128694A1 (fr) 2015-02-13 2016-08-18 Tronic's Microsystems Oscillateur mécanique et procédé de réalisation associe
EP3181939A1 (de) 2015-12-18 2017-06-21 CSEM Centre Suisse d'Electronique et de Microtechnique SA - Recherche et Développement Herstellungsverfahren einer spiralfeder mit einer vorbestimmten steifigkeit durch zugabe von material
EP3181938A1 (de) 2015-12-18 2017-06-21 CSEM Centre Suisse d'Electronique et de Microtechnique SA - Recherche et Développement Herstellungsverfahren einer spiralfeder mit einer vorbestimmten steifigkeit durch wegnahme von material
EP3654111A1 (de) 2018-11-15 2020-05-20 Nivarox-FAR S.A. Verfahren zur messung des drehmoments einer spiralfeder einer uhr
EP3845770A1 (de) * 2019-09-16 2021-07-07 Sigatec SA Verfahren zur herstellung von uhrwerk-spiralfedern

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
M. VERMOT ET AL., DANS LE TRAITÉ DE CONSTRUCTION HORLOGÈRE, 2011, pages 178 - 179

Also Published As

Publication number Publication date
WO2024017847A1 (fr) 2024-01-25

Similar Documents

Publication Publication Date Title
EP1828744B1 (de) Messkopf für nanoeinschnittvorrichtung und verfahren zur messung damit
EP2992298B1 (de) Mems-ausgeglichener inerter winkelsensor und verfahren zum ausgleichen solch eines sensors
JP5977495B2 (ja) ひげぜんまいのトルクを測定するための装置
EP3181940B1 (de) Herstellungsverfahren einer spiralfeder mit einer vorbestimmten steifigkeit durch lokalisierte wegnahme von material
EP2145237A2 (de) Uhrenkomponente und verfahren zu ihrer herstellung
EP2843484A1 (de) Kontrollverfahren zur Identifizierung der mechanischen Bewegung einer Armbanduhr
EP3071976B1 (de) Sensor mit beweglichem empfindlichem element mit gemischtem vibrierendem und pendelartigem betrieb und verfahren zur steuerung solch eines sensors
WO2022152857A1 (fr) Procédé de controle et de fabrication de ressorts spiraux d'horlogerie
WO2019180558A1 (fr) Procede de fabrication de spiraux horlogers thermocompenses de raideur precise
EP3114535B1 (de) Verfahren zur paarung einer unruh und spiralfeder in einem regelungselement
FR2827040A1 (fr) Systeme d'elimination de decalage pour un gyroscope vibrant
EP2864844B1 (de) Verfahren zur bestimmung einer unwuchteigenschaft eines oszillators
EP4310598A1 (de) Verfahren zur kontrolle und herstellung von uhrwerk-spiralfedern
WO2023117350A1 (fr) Procédé de controle et de fabrication de ressorts spiraux d'horlogerie
EP4202576A1 (de) Verfahren zur kontrolle und herstellung von uhrwerk-spiralfedern
EP3304216B1 (de) Thermokompensierte resonator für uhrwerk und verfahren zur herstellung einer solchen resonator
CH718081A2 (fr) Élément élastique pour un système micromécanique.
EP4030241A1 (de) Verfahren zur herstellung von uhrwerk-spiralfedern
WO2021122331A1 (fr) Dispositif d'horloge
EP3982205A1 (de) Verfahren zur herstellung einer uhrfeder mit einer präzisen steifigkeit
EP4273632A1 (de) Verfahren zur herstellung von uhrenkomponenten
WO2022017699A1 (fr) Procede de calibration d'un capteur inertiel vibrant
EP4303668A1 (de) Verfahren zur bestimmung der steifigkeit einer spiralfeder
CH719864A2 (fr) Dispositif de détermination de la raideur d'un spiral.
EP3889617A1 (de) Verfahren zur steuerung eines sensors

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN PUBLISHED

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR