EP4030243A1 - Verfahren zur kontrolle und zur herstellung von uhrwerk-spiralfedern - Google Patents

Verfahren zur kontrolle und zur herstellung von uhrwerk-spiralfedern Download PDF

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Publication number
EP4030243A1
EP4030243A1 EP21152144.8A EP21152144A EP4030243A1 EP 4030243 A1 EP4030243 A1 EP 4030243A1 EP 21152144 A EP21152144 A EP 21152144A EP 4030243 A1 EP4030243 A1 EP 4030243A1
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EP
European Patent Office
Prior art keywords
hairspring
blank
predetermined
frequency
balance
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
EP21152144.8A
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English (en)
French (fr)
Inventor
David Gachet
Kevin SOOBBARAYEN
Susana Tobenas
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Richemont International SA
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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 EP21152144.8A priority Critical patent/EP4030243A1/de
Priority to PCT/EP2022/050760 priority patent/WO2022152857A1/fr
Priority to CN202280010309.1A priority patent/CN116783558A/zh
Priority to EP22700645.9A priority patent/EP4278234A1/de
Priority to JP2023542990A priority patent/JP2024507061A/ja
Priority to US18/261,472 priority patent/US20240069496A1/en
Publication of EP4030243A1 publication Critical patent/EP4030243A1/de
Pending legal-status Critical Current

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    • 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
    • G04D7/1207—Timing devices for clocks or watches for comparing the rate of the oscillating member with a standard only for measuring
    • G04D7/1235—Timing devices for clocks or watches for comparing the rate of the oscillating member with a standard only for measuring for the control mechanism only (found from outside the clockwork)
    • G04D7/125—Timing devices for clocks or watches for comparing the rate of the oscillating member with a standard only for measuring for the control mechanism only (found from outside the clockwork) for measuring frequency
    • 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)
    • G04D7/1285—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) whereby the adjustment device works on the mainspring

Definitions

  • the present invention relates to the field of control and manufacture of parts for watchmaking.
  • the invention relates more particularly to a method for checking and manufacturing clockwork spiral springs, otherwise known as resonators.
  • the movements of mechanical watches are regulated by means of a mechanical regulator comprising a resonator, that is to say an elastically deformable component whose oscillations determine the rate of the watch.
  • a mechanical regulator comprising a resonator, that is to say an elastically deformable component whose oscillations determine the rate of the watch.
  • Many watches include, for example, a regulator comprising a hairspring as a resonator, mounted on the axis of a balance wheel and set in oscillation by means of an escapement.
  • the stiffness of the hairspring also defines its intrinsic vibratory characteristics, such as the natural frequency and the 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 exciting force.
  • a resonance frequency of an elastic system subjected to an exciting force is a frequency at which one can measure a local maximum of displacement amplitude for a given point. of the elastic system.
  • the displacement amplitude follows an upward slope before this resonance frequency, and follows a downward slope afterwards, in all point that does not correspond to a vibration node.
  • the recording of the displacement amplitude as a function of the excitation frequency shows a displacement amplitude peak or resonance peak which is associated with or which characterizes the resonance frequency.
  • the natural frequency of the regulator member formed by the balance spring of stiffness R coupled to a balance wheel of inertia I is in particular proportional to the square root of the stiffness of the balance spring.
  • the main specification of a spiral spring is its stiffness, which must be within a well-defined range in order to be able to be paired with a pendulum, which forms the inertial element of the oscillator. This pairing operation is essential to precisely adjust the frequency of a mechanical oscillator.
  • silicon hairsprings can be manufactured on a single wafer using micro-fabrication technologies. It is in particular known to produce a plurality of silicon resonators with very high precision by 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 crystalline class m3m whose coefficient of thermal expansion (alpha) is isotropic.
  • 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 according to 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 variations in temperature of the 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 having a positive thermoelastic coefficient .
  • SiO2 amorphous silicon oxide
  • 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 on the plate.
  • the micro-manufacturing 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 of the same wafer, and therefore 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 the manufacturing yield, it is therefore of interest to center the mean of the Gaussian distribution on a value of nominal stiffness and also to reduce the standard deviation of this Gaussian.
  • the dispersion of stiffness is even greater between hairsprings of two wafers engraved at different times according to the same process specifications. This phenomenon is shown in figure 1 where the stiffness dispersion curves Rd1, Rd2 and Rd3 for hairsprings on three different pads are shown.
  • the distribution of the stiffnesses R (relative to the number of hairsprings N with this stiffness) follows the normal or Gaussian law, each dispersion curve being centered on its respective mean value Rm1, Rm2 and Rm3.
  • 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 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 with 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 equipped with a predetermined inertia, by calculating the thickness of material to be added to obtain the dimensions necessary for obtaining 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 recentered with respect to a nominal stiffness value Rnom.
  • the aim of the present invention is 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, and therefore a more individualized correction of the hairsprings of the insert.
  • the method according to the implementation above comprises a step of vibratory excitation of the hairspring or of the hairspring blank and the measurement of a characteristic of a resonant frequency, in order then to deduce therefrom by prediction a stiffness and/or or if a dimensional correction is necessary.
  • a pendulum or other component which saves time.
  • the measurement is carried out on the hairsprings or the blanks alone, which limits the errors induced by other components or their assembly, as well as any pollution. Measurement accuracy is improved because there are fewer sources of variability due to other components or pollution.
  • the method according to the above implementation therefore makes it possible to test balance-spring blanks during manufacture while limiting the risks of pollution or assembly errors. A dimensional correction (of section, height and/or thickness) is then possible.
  • the method according to the implementation above makes it possible just as well to test finished hairsprings in order for example to carry out a classification by increments of stiffness, in order to provide pairing with a particular balance wheel.
  • the frequency range of the spectrum obtained does not only depend on the source of vibratory 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 instrument for measuring 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 of the tested blank.
  • 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 dimensional correction predicted by the prediction machine can typically be a correction of the section of the flexible bar forming the hairspring or the hairspring blank, that is to say a correction either of the height or of the thickness, or both.
  • the characteristic of a resonant frequency is a characteristic of the oscillatory response measured over a predetermined frequency range, comprising at least one resonant frequency.
  • a characteristic is typically identified after processing a raw measurement signal (for example measuring the amplitudes or speeds or displacement accelerations of certain points of the hairspring or of the hairspring blank), the processing possibly including for example a transform of Fourier to identify resonance peaks and therefore resonance frequencies.
  • the frequency range is applied simultaneously to a plurality of balance-springs or balance-spring blanks.
  • the speed is improved, because the vibratory excitation can typically be imposed on a wafer supporting several hundred balance-spring blanks, which would for example still be attached to the wafer.
  • the hairspring has at least two predetermined resonance frequencies, and the frequency range is predetermined to cover at least the two predetermined resonance frequencies. By covering or sweeping a wide range of frequencies, several resonance peaks (or resonance frequencies) can be measured, which can provide better accuracy.
  • step a comprises the use of a source, such as a piezoelectric source, making it possible to induce or impose an acoustic excitation on a slice of a wafer supporting the balance-spring 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 balance spring or a balance spring blank.
  • the acoustic source can be coupled to an excitation cone chosen to excite at least some and preferably all of the balance-spring blanks.
  • step b comprises the use of an optical measuring means, such as a laser vibrometer by Doppler effect.
  • step b is based on a measurement over time of an amplitude or a speed, or even an acceleration of displacement of at least one point of the hairspring or of the blank of hairspring, preferably performed at least partially during step a.
  • the mode of vibration in response to vibrational excitation may vary.
  • 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 phase, depending on the excitation frequency.
  • the resonance frequency is identified based on the width of the resonance or amplitude peak, halfway up the maximum value of the amplitude resonance peak.
  • step c comprises a step of calculating a stiffness of the hairspring or of the hairspring blank.
  • the calculation of the stiffness makes it possible to determine with improved precision whether a dimensional correction is necessary, and of what value this correction must be. In addition, this also makes it possible to pre-dimension or choose a balance wheel to couple the hairspring once it is finished manufacturing.
  • the method comprises a step: d. calculating, with the prediction machine, the dimensional modification (modification of section, height and/or thickness) to be applied from the resonance frequency characteristic identified in step b.
  • the prediction machine implements a polynomial formula to predict whether a dimensional correction is necessary.
  • a polynomial formula to predict whether a dimensional correction is necessary.
  • the prediction machine implements a classification performed for example by a neural network to predict whether a dimensional correction is necessary.
  • the prediction machine implements a classification based on a partitioning into k-means or into k-medians to predict whether a dimensional correction is necessary.
  • the hairspring blank being formed on a wafer comprising a plurality of hairspring blanks distributed over several sectors of the wafer
  • step b comprises a step consisting in identifying at least one characteristic of a resonance frequency of at least one balance-spring blank for each sector
  • step c comprises a step consisting in determining a stiffness of the balance-spring blank and/or in determining, for the balance-spring blanks of each sector, whether a dimensional correction is necessary.
  • the precision of the dimensional correction (section, height and/or thickness) is improved by refining the analysis by sectors of the wafer.
  • control method comprises a step of calculating, with the prediction machine, the dimensional modification to be applied for the balance-spring blanks of each sector.
  • step a comprises a step consisting in modifying a direction of vibratory excitation over time, preferably in a direction pointing to the balance spring or the balance spring blank whose resonance frequency characteristic is identified in step b.
  • control method comprises a preliminary step consisting in taking into account the material of the hairspring or of the hairspring blank, and in adjusting a maximum amplitude of the vibratory excitation and/or a frequency range of the predetermined frequency range as a function of the material of the hairspring or of the hairspring blank.
  • the frequency range obtained extends over a frequency range ranging from 0 Hz to 100 kHz, preferably from 0 Hz to 50 kHz, more preferably from 0 Hz to 40 kHz, and very preferably from 10 kHz at 35kHz.
  • step a and step b are repeated at least several times for the same measurement point of the hairspring or of 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, the consideration of which can improve the precision of the prediction, or make it possible to adjust or recalibrate the vibratory excitation source.
  • the dimensions can be corrected by shrinking or adding material.
  • the hairspring or the hairspring blank is formed in silicon, or in glass, or in ceramic, or in metal, or in carbon nanotubes.
  • the hairspring blank is formed on a wafer, with a plurality of other hairspring blanks.
  • the chosen frequency range Preferably, it will be chosen to use a sufficiently sensitive measuring instrument on the chosen frequency range, and ensuring that the vibratory behavior of the hairspring is exploitable on this chosen frequency range.
  • Such a step of identifying the reference points makes it possible to eliminate the points or the zones which are nodes (that is to say immobile points) at one or more resonance frequencies.
  • the Figures 3A-3F are a simplified representation of a method of manufacturing a mechanical resonator 100 on a plate 10.
  • the resonator is intended in particular to equip a regulating member of a timepiece and, according to this example, is in the form of a spiral spring 100 in silicon which is intended to equip a balance of a mechanical clock movement.
  • Plate 10 is illustrated in Figure 3A as an SOI (“silicon on insulator”) wafer and comprises a substrate or “handler” 20 bearing 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.
  • a lithography step is shown to figure 3B and 3C .
  • 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 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 patterning by lithography forms the patterns for the plurality of resonators in layer 50, as illustrated in Fig. 3C .
  • the patterns are machined, in particular etched, to form the plurality of resonators 100 in the layer 40.
  • the etching can be performed by a deep reactive ion etching technique (also known by the acronym DRIE for “Deep Reactive Ion Etching”) .
  • DRIE deep reactive ion etching technique
  • 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 of the substrate or handler 20. Smoothing (not shown) of the etched surfaces can also take place before the release step, by for example by a thermal oxidation step 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 the vibratory characteristics of the hairspring leading to obtaining a particular natural frequency. of the balance-spring couple in a given watch mechanism.
  • the various resonators formed in the wafer generally have a significant geometric dispersion between them and therefore a significant dispersion between their stiffnesses, notwithstanding that the steps for forming the patterns and for machining/etching through these patterns are the same for all the resonators.
  • this dispersion of stiffness is even greater between the hairsprings of two wafers engraved at different times even if the same process specifications are used.
  • resonators 100 made of silicon, but it is possible to envisage making the resonators out of glass, ceramic, carbon nanotubes, or even metal.
  • the resonators obtained in step 3E on the wafer 10 in question can be deliberately formed with dimensions d which are different from the dimensions necessary (for example greater) for obtaining a nominal or target stiffness.
  • d the dimensions necessary (for example greater) for obtaining a nominal or target stiffness.
  • the present invention proposes to determine from at least one characteristic of a resonance frequency of a sample of resonators 100 on the wafer in step 3E and whether a geometric correction of the resonators is necessary. If so, the present invention proposes to precisely calculate the thickness of material to be modified (to be removed or added), around each turn, to obtain the dimensions leading to obtain the vibratory characteristics of the resonators (natural frequency and/or resonance frequencies, and/or stiffness) corresponding to target values, according to a more efficient method than the methods of the prior art.
  • the invention proposes to determine at least one characteristic of a resonance frequency of a sample of resonators by measuring vibration and apply a predictive method (for example a numerical model or a classification or categorization method) to link the result of said vibration measurement to the necessary geometric correction.
  • a predictive method for example a numerical model or a classification or categorization method
  • the modal properties of the hairspring attached to the wafer are thus exploited.
  • a prediction machine by establishing a predictive model linking the dimensions (in particular the thickness) and/or the stiffness at certain frequencies (natural frequency or resonance frequencies associated with a resonance peak or a width at mid-height) specifically chosen.
  • the learning phase is complete (once the modes to be exploited as well as the excitation frequencies have been determined), it is possible to move on to a prediction phase and use the prediction machine by exploiting the predictive model to control the resonators of a wafer produced, in order to predict whether a correction of the dimensions is necessary, and if necessary, calculate or predict the exact correction to be made to the dimensions of the resonators (by shrinkage if the blank is produced with dimensions greater than the final dimensions required, or by adding material if the blank is made with dimensions smaller than the final dimensions required, for example).
  • control method into a manufacturing process to correct, if necessary, the vibratory characteristics of the resonators (natural frequency and/or resonance frequencies, and/or stiffness) to obtain a particular natural oscillation frequency. and predetermined, once the resonators are each coupled to a balance wheel of a given watch mechanism.
  • the measurements can be performed by 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 the resolution for processing the acquisition data according to for example a Fourier transform depends directly from the duration of this acquisition.
  • provision may be made to couple the acoustic source to a divergent cone directed towards the resonators to be excited, and to adjust the acoustic source to emit an excitation signal with sufficient amplitude to impose vibratory excitation of the resonator(s) and having an amplitude sufficient to be detected and measured accurately by the chosen measuring instruments.
  • the figure 5 schematically represents a silicon wafer 25 on which are formed a plurality of balance-spring blanks 200.
  • a vibratory excitation source 400 is coupled to the wafer 25, so as to be able to impose a vibratory excitation. Consequently, each hairspring blank 200 will begin to vibrate, and a laser vibrometer 300, here focused on a point of the hairspring blank 200 on the right, will be able to measure the vibration amplitudes of the measurement point over time. Provision can be made to measure the displacements in a direction normal to the plane of the wafer 25, but it is just as possible to measure the displacements in one or more directions contained in the plane of the wafer 25.
  • the laser vibrometer 300 can be moved to another measurement point of the hairspring blank 200, or move on to another hairspring blank 200 of the wafer 25. Of course, one can alternatively move the draft of hairspring 200 with respect to the laser vibrometer.
  • the figure 6 represents an example of vibratory excitation over time.
  • the excitation frequency varies over time, between 0 Hz and 50 kHz, and a succession of rising edges can be imposed, each spaced by a rest period without excitation.
  • a plurality of rising edges can be imposed (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 in identifying points of the resonator for which the vibratory response is significant. Indeed, in the case of a hairspring on which a vibration is imposed, especially if the frequency varies over time, the vibratory response will cause nodes to appear on the hairspring, that is to say particular points of the hairspring whose displacement amplitude is low or zero. If a displacement measurement is performed on a point of the hairspring which turns out to be a knot at one or more particular frequency(ies), the identification of resonant frequency characteristics will be adversely 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 predetermined points. Provision can be made to select the predetermined points arranged on an X-Y orthonormal reference mark in the plane of the hairspring.
  • this preliminary step of amplitude measurement on the predetermined points provision can be made to identify resonance frequencies for each measurement point, and then a step of selecting reference points for which the measurement of displacement amplitude during excitation shows that they are not nodes at these resonant frequencies.
  • the identified nodes have, at at least one resonance frequency, a zero displacement amplitude 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 spiral blank 200 on the wafer 25.
  • the area of the curve located between 25% and 75% of the maximum amplitude value of the resonance peak has better accuracy than the part above 75% (typically the peak), which offers better accuracy on the exact frequency of determined resonance.
  • the figure 7 shows an example of a vibration spectrum for a point on a 200 balance-spring blank from the figure 5 , reconstructed from the displacement amplitude measurements of the measurement point considered in response to the vibratory excitation of the figure 6 , between 10 kHz and 15 kHz.
  • the figure 8 shows in detail the processing that can be done on an amplitude peak, the one at 11 kHz for example.
  • the goal is to find the resonance frequency and give it as precise a value as possible.
  • the applicant noticed that better accuracy could be achieved by determining the length of the segment connecting the rising part and the falling part of the curve, at mid-height of the peak.
  • the resonance frequency being typically the value in the middle of this segment.
  • the figure 9 represents, for the example of an amplitude peak at around 10 kHz, the amplitude peaks constructed for ten or so balance-spring blanks 200 tested. It can be noted that from one balance-spring 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 approx. The tops of amplitude peaks not being really symmetrical, it seems judicious to determine the resonance frequency on the basis of the width of the peak at mid-height.
  • Two alternatives can be implemented. It is possible, according to a first alternative, to couple a predetermined balance directly to the resonator still attached to the wafer, and to measure a natural frequency of oscillation of the resonator-balance couple to compare this natural frequency with an expected natural frequency and above all to calculate the stiffness actual size or actual dimensions based on equations 1-3 above. According to a second alternative, it is possible to finish manufacturing the resonators tested, in order to mount them or couple them individually with a pendulum to measure here again a natural frequency of oscillation of the resonator-pendulum couple.
  • the stiffness can also be deduced from a reaction torque measurement at the ferrule using a rheometer.
  • the acquired signal represents the evolution of the torque as a function of the amplitude.
  • the analysis of the slope of this curve for the low amplitudes (linear part) makes it possible to deduce the stiffness, and then the dimensions of the bar of the resonator. The dimensions of the hairspring bar can then be determined.
  • a high-resolution 3D X-ray tomography approach would make it possible to extract clouds of points giving the 3D material density of the balance-springs, and, subject to appropriate image reconstruction, a cartography of the section of the balance-spring.
  • clouds of points giving the 3D material density of the balance-springs and, subject to appropriate image reconstruction, a cartography of the section of the balance-spring.
  • 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 in analyzing the forced oscillations of a hairspring on a reference balance wheel with an escapement.
  • An alternative can be envisaged from an acoustic acquisition (Witschi type microphone) which records the shocks of the different operating phases of the escapement/anchor system. The data measured are either scatter plots of the passage times of the arms of the balance wheel, or the temporal evolution of the sound pressure level.
  • oscillation amplitude measurements are performed on physical resonators, and resonance frequencies are identified.
  • a correlation phase must be provided during which a predictive model is constructed.
  • This database can also be supplemented by experimental measurements by measuring vibration spectra, oscillation periods and the positions of hairsprings on the wafer as well as their associated stiffnesses.
  • One of the advantages of this approach lies in the fact that the learning database is enriched as the trials progress. This can make it possible to have an adaptive model according to the pads and the hairsprings and contributes to the reduction of the standard deviation in stiffness on the pads.
  • This database can be used to build a prediction model, and several solutions are available.
  • a digital model for example polynomial, can be constructed to calculate, as a function of a resonance frequency value, a real thickness, a dimensional correction or a real stiffness.
  • a neural network for example a perceptron
  • the learning phase includes a test phase (excitation of resonators with measurement of the vibration characteristics to reconstruct a vibration spectrum and identify resonance frequencies).
  • a phase of measuring the stiffnesses and/or the dimensions of the bar of the resonators is also carried out.
  • the construction phase of the prediction model can be 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 resonance modes in particular the modes of deformation and/or displacement of the resonators
  • the resonance modes could differ significantly, which can also affect the sensitivity of the stiffness and/or dimensional correction prediction. It is advantageous to provide, during the learning phase, a step of comparing the sensitivity of the prediction to choose to consider later such or such resonance frequency and not another to predict as accurately 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 single prediction as precise as possible, or several predictions (one per resonance peak deemed interesting) to then carry out cross-checks, averages or even readjustments of the predicted values.
  • the control process can typically be carried out on hairspring blanks made on a wafer and still attached to this wafer, 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 brought.
  • corrections can be made for the entire wafer in a homogeneous manner, or differentiated by region, if the results obtained vary from one hairspring to another. It is thus possible to reduce the standard deviation of the dispersion of the stiffnesses. Moreover, if the stiffnesses of all the hairsprings are known by applying the model, it is possible to determine the optimum correction making it possible to reduce the overall dispersion.
  • the correction step then consists in adding material, as for example described in the document EP3181939 aforementioned.
  • the method consisting in identifying resonance frequencies by imposing a vibratory excitation on the balance-spring blanks alone, makes it possible to quickly obtain measurement data, without having to carry out operations to mount a balance wheel, for example, while limiting the errors of measured because only the balance-spring blank is tested (there is no error that could be linked to the balance wheel, such as its mass, its mounting position, etc.).
EP21152144.8A 2021-01-18 2021-01-18 Verfahren zur kontrolle und zur herstellung von uhrwerk-spiralfedern Pending EP4030243A1 (de)

Priority Applications (6)

Application Number Priority Date Filing Date Title
EP21152144.8A EP4030243A1 (de) 2021-01-18 2021-01-18 Verfahren zur kontrolle und zur herstellung von uhrwerk-spiralfedern
PCT/EP2022/050760 WO2022152857A1 (fr) 2021-01-18 2022-01-14 Procédé de controle et de fabrication de ressorts spiraux d'horlogerie
CN202280010309.1A CN116783558A (zh) 2021-01-18 2022-01-14 一种钟表游丝的检测和制造方法
EP22700645.9A EP4278234A1 (de) 2021-01-18 2022-01-14 Verfahren zum testen und herstellen von spiralfedern für uhr
JP2023542990A JP2024507061A (ja) 2021-01-18 2022-01-14 時計用ぜんまいばねの試験及び製造方法
US18/261,472 US20240069496A1 (en) 2021-01-18 2022-01-14 Method for testing and manufacturing spiral springs for a timepiece

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EP4303668A1 (de) * 2022-07-05 2024-01-10 Richemont International S.A. Verfahren zur bestimmung der steifigkeit einer spiralfeder

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DE921320C (de) * 1948-11-30 1954-12-16 Epsylon Res & Dev Company Ltd Vorrichtung zum Abstimmen von Unruhspiralen
FR1502464A (fr) * 1966-09-15 1967-11-18 Straumann Inst Ag Dispositif pour la mesure électrique du moment de la force de spiraux mis à longueur et du moment d'inertie des balanciers
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
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

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DE921320C (de) * 1948-11-30 1954-12-16 Epsylon Res & Dev Company Ltd Vorrichtung zum Abstimmen von Unruhspiralen
CH281496A (de) * 1949-01-04 1952-03-15 Smith & Sons Ltd S Einrichtung für das selbsttätige Regulieren der Frequenz eines Systems Unruhe-Spiralfeder.
FR1502464A (fr) * 1966-09-15 1967-11-18 Straumann Inst Ag Dispositif pour la mesure électrique du moment de la force de spiraux mis à longueur et du moment d'inertie des balanciers
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
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

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Publication number Priority date Publication date Assignee Title
EP4303668A1 (de) * 2022-07-05 2024-01-10 Richemont International S.A. Verfahren zur bestimmung der steifigkeit einer spiralfeder

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US20240069496A1 (en) 2024-02-29
EP4278234A1 (de) 2023-11-22

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