EP3889691B1 - Horological hairspring made of a nb-hf alloy - Google Patents

Horological hairspring made of a nb-hf alloy Download PDF

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Publication number
EP3889691B1
EP3889691B1 EP21170773.2A EP21170773A EP3889691B1 EP 3889691 B1 EP3889691 B1 EP 3889691B1 EP 21170773 A EP21170773 A EP 21170773A EP 3889691 B1 EP3889691 B1 EP 3889691B1
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alloy
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EP21170773.2A
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German (de)
French (fr)
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EP3889691A1 (en
Inventor
Christian Charbon
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Nivarox Far SA
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Nivarox Far SA
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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
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C27/00—Alloys based on rhenium or a refractory metal not mentioned in groups C22C14/00 or C22C16/00
    • C22C27/02—Alloys based on vanadium, niobium, or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
    • C22F1/18—High-melting or refractory metals or alloys based thereon
    • 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
    • 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
    • G04B17/063—Balance construction

Definitions

  • the invention relates to a method of manufacturing a spiral spring intended to equip a balance wheel with a watch movement. It also relates to the spiral spring resulting from this process made in an Nb-Hf alloy.
  • spiral springs are also centered on the concern for thermal compensation, so as to guarantee regular chronometric performance. To do this, it is necessary to obtain a thermoelastic coefficient close to zero. We are also seeking to produce spiral springs with limited sensitivity to magnetic fields.
  • An object of the present invention is to propose a spiral spring intended to equip a balance wheel with a clock movement and for which deformations during its manufacture are facilitated and rolling is easy.
  • the invention relates to a spiral spring as defined in appended claim 1.
  • the invention relates to a spiral spring intended to equip a balance wheel with a watch movement and made from an alloy comprising niobium and hafnium.
  • the blank comprises by weight between 8 and 12% hafnium, Ti in a percentage between 0.5 and 1.5%, Zr in a percentage between 0.5 and 0.9%, Ta in a percentage between 0.3 and 0.7% , W in a percentage between 0.3 and 0.7%.
  • the NbHf alloy blank used for the present invention does not include other elements with the exception of possible and inevitable traces. This makes it possible to avoid the formation of fragile phases.
  • the oxygen content is less than or equal to 0.10% by weight of the total, in particular less than or equal to 0.05% by weight of the total, or even less than or equal to 0.03% by weight of the total.
  • the carbon content is less than or equal to 0.04% by weight of the total, in particular less than or equal to 0.02% by weight of the total, or even less than or equal to 0.015% by weight of the total.
  • the iron content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.02% by weight of the total, or even less than or equal to 0.005% by weight of the total.
  • the nitrogen content is less than or equal to 0.04% by weight of the total, in particular less than or equal to 0.02% by weight of the total, or even less than or equal to 0.015% by weight of the total.
  • the hydrogen content is less than or equal to 0.01% by weight of the total, in particular less than or equal to 0.0035% by weight of the total, or even less than or equal to 0.001% by weight of the total.
  • the silicon content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.02% by weight of the total, or even less than or equal to 0.005% by weight of the total.
  • the nickel content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.
  • the content of element in ductile solid solution, such as copper, in the alloy is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.05% by weight of the total. equal to 0.004% by weight of the total.
  • the aluminum content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.
  • the chromium content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.
  • the manganese content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.
  • the vanadium content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.
  • the tin content is less than or equal to 0.01% by weight of the total, in particular less than or equal to 0.0035% by weight of the total, or even less than or equal to 0.001% by weight of the total.
  • the magnesium content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.
  • the molybdenum content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.
  • the lead content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.
  • the cobalt content is less than or equal to 0.01% by weight of the total, in particular less than or equal to 0.0035% by weight of the total, or even less than or equal to 0.001% by weight of the total.
  • the boron content is less than or equal to 0.005% by weight of the total, in particular less than or equal to 0.0001% by weight of the total.
  • the annealing step is a solution treatment, with a duration of preferably between 5 minutes and 2 hours at a temperature of between 650°C and 1750°C, under vacuum, followed by quenching for example under gas to obtain Hf in supersaturated solid solution in Nb ß.
  • natural cooling under vacuum can also be considered.
  • the deposition step of the process making it possible to manufacture the spiral spring which is more particularly the subject of the invention consists of depositing a layer of a ductile material chosen from the group comprising copper, nickel, cupro-nickel, cupro-manganese, gold, silver, nickel-phosphorus Ni-P and nickel-boron Ni-B, to facilitate shaping into wire form.
  • a ductile material chosen from the group comprising copper, nickel, cupro-nickel, cupro-manganese, gold, silver, nickel-phosphorus Ni-P and nickel-boron Ni-B, to facilitate shaping into wire form.
  • the thickness of the layer of ductile material deposited is chosen so that the ratio of surface area of ductile material/surface area of the NbHf alloy for a given wire section is less than 1, preferably less than 0.5, and more preferably between 0.01 and 0.4.
  • the layer of ductile material can have a thickness of 7 ⁇ m for an NbHf alloy section of 0.086 mm in diameter. This corresponds to a ratio between the copper surface area (0.002 mm 2 ) and the NbHf surface area (0.0058 mm 2 ) of 0.35.
  • Such a thickness of ductile material, and in particular of copper makes it possible to easily stretch, draw and roll the Cu/NbHf composite material.
  • the copper thickness is optimized so that the tip, created by filing or hot drawing, necessary for introducing the wire into the die during drawing or drawing, is covered with copper.
  • the ductile material preferably copper, is thus deposited at a given moment to facilitate the shaping of the wire by drawing, drawing and rolling, in such a way that a thickness remains, preferably between 1 and 500 micrometers on the wire with a total diameter of 0.2 to 1 millimeter.
  • ductile material can be galvanic, by PVD or CVD, or mechanical, it is then a jacket or a tube of ductile material such as copper which is adjusted to an NbHf alloy bar with a large diameter, then which is thinned during the step(s) of deformation of the composite bar.
  • ductile material can be galvanic, by PVD or CVD, or mechanical, it is then a jacket or a tube of ductile material such as copper which is adjusted to an NbHf alloy bar with a large diameter, then which is thinned during the step(s) of deformation of the composite bar.
  • the deformation step generally designates one or more deformation treatments, which may include wire drawing and/or rolling.
  • Wire drawing may require the use of one or more dies during the same deformation stage or during different deformation stages if necessary.
  • Drawing is carried out until a round section wire is obtained.
  • Rolling can be carried out in the same deformation step as wire drawing or in another subsequent deformation step.
  • the last deformation treatment applied to the alloy is rolling, preferably with a rectangular profile compatible with the entry section of a strapping pin.
  • the process may comprise one step or several deformation steps with a deformation rate for each step of between 1 and 5, preferably between 2 and 5, the deformation rate corresponding to the classic formula 2ln(d0/d) where d0 and d are respectively the diameter before and after deformation.
  • the total strain rate can be between 1 and 14.
  • the process may include intermediate annealing stages between the different deformation stages.
  • the method which makes it possible to manufacture the spiral spring according to the invention preferably comprises, after the deformation step, a step of eliminating said layer of ductile material.
  • the ductile material is eliminated once all the deformation operations have been carried out, that is to say after the last rolling, before strapping.
  • the wire is freed from its layer of ductile material, such as copper, in particular by chemical attack, with a solution based on cyanides or based on acids, for example nitric acid.
  • the annealing prior to the deformation stage as well as the intermediate annealing carried out between the deformation stages is carried out during a duration of between 5 minutes and 2 hours, preferably between 10 minutes and 1 hour at a temperature of between 650°C and 1750°C.
  • the final heat treatment after strapping is carried out at a temperature between 500 and 1250°C for a time between 30 minutes and 30 hours.
  • a single-phase structure of centered cubic or two-phase type with a centered cubic structure and a compact hexagonal structure can be obtained at the end of this heat treatment.
  • the above process allows the production, and more particularly the shaping, of a spiral spring for a balance wheel made of a niobium-hafnium type alloy, as claimed.
  • This alloy has high mechanical properties, combining a very high elastic limit, greater than 600 MPa, and a very low modulus of elasticity, of the order of 60 GPa to 100 GPa. This combination of properties is well suited for a spiral spring.
  • such an alloy is paramagnetic.
  • a binary type alloy comprising niobium and hafnium, of the type selected above for the implementation of the invention also has an effect similar to that of "Elinvar", with a thermo-elastic coefficient practically zero in the usual temperature range of watches, and suitable for the manufacture of self-compensating hairsprings.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Springs (AREA)
  • Heat Treatment Of Steel (AREA)

Description

Domaine de l'inventionField of the invention

L'invention concerne un procédé de fabrication d'un ressort spiral destiné à équiper un balancier d'un mouvement d'horlogerie. Elle se rapporte également au ressort spiral issu de ce procédé réalisé dans un alliage Nb-Hf.The invention relates to a method of manufacturing a spiral spring intended to equip a balance wheel with a watch movement. It also relates to the spiral spring resulting from this process made in an Nb-Hf alloy.

Arrière-plan de l'inventionBackground of the invention

La fabrication de ressorts spiraux pour l'horlogerie doit faire face à des contraintes souvent à première vue incompatibles :

  • nécessité d'obtention d'une limite élastique élevée,
  • facilité d'élaboration, notamment de tréfilage et de laminage,
  • excellente tenue en fatigue,
  • stabilité des performances dans le temps,
  • faibles sections.
The manufacture of spiral springs for watchmaking must face constraints that are often at first glance incompatible:
  • need to obtain a high elastic limit,
  • ease of production, in particular drawing and rolling,
  • excellent fatigue resistance,
  • stability of performance over time,
  • weak sections.

La réalisation de ressorts spiraux est en outre centrée sur le souci de la compensation thermique, de façon à garantir des performances chronométriques régulières. Il faut pour cela obtenir un coefficient thermoélastique proche de zéro. On recherche également à réaliser des ressorts spiraux présentant une sensibilité aux champs magnétiques limitée.The production of spiral springs is also centered on the concern for thermal compensation, so as to guarantee regular chronometric performance. To do this, it is necessary to obtain a thermoelastic coefficient close to zero. We are also seeking to produce spiral springs with limited sensitivity to magnetic fields.

Des spiraux ont été développés à partir d'alliages de niobium et d'hafnium. Toutefois, ces alliages posent des problèmes de collement et de grippage dans les filières d'étirage ou de tréfilage (diamant ou métal dur) et contre les rouleaux de laminage (métal dur ou acier), ce qui les rend quasiment impossibles à transformer en fils fins par les procédés standards utilisés par exemple pour l'acier.Hairsprings were developed from niobium and hafnium alloys. However, these alloys pose sticking and seizing problems in the drawing or drawing dies (diamond or hard metal) and against the rolling rolls (hard metal or steel), which makes them almost impossible to transform into wires. fine by standard processes used for example for steel.

Toute amélioration sur au moins l'un de ces points, et en particulier sur la facilité d'élaboration, notamment de tréfilage et de laminage, représente donc une avancée significative.Any improvement on at least one of these points, and in particular on the ease of production, in particular of wire drawing and rolling, therefore represents a significant advance.

Le document EP1258786A1 décrit un ressort spiral d'horlogerie constitué de:

  1. i) Niobium;
  2. ii) Hafnium en pourcentage entre 2% et 30% ;
  3. iii) des éléments tels que Ti, Zr, Ta, W avec des pourcentages très bas.
The document EP1258786A1 describes a watch spiral spring consisting of:
  1. (i) Niobium;
  2. ii) Hafnium in percentage between 2% and 30%;
  3. iii) elements such as Ti, Zr, Ta, W with very low percentages.

Résumé de l'inventionSummary of the invention

Un objet de la présente invention est de proposer un ressort spiral destiné à équiper un balancier d'un mouvement d'horlogerie et pour lequel les déformations pendant sa fabrication sont facilitées et le laminage est aisé.An object of the present invention is to propose a spiral spring intended to equip a balance wheel with a clock movement and for which deformations during its manufacture are facilitated and rolling is easy.

A cet effet, l'invention concerne un ressort spiral tel que défini dans la revendication 1 annexée.For this purpose, the invention relates to a spiral spring as defined in appended claim 1.

Description de l'inventionDescription of the invention

L'invention concerne un ressort spiral destiné à équiper un balancier d'un mouvement d'horlogerie et réalisé dans un alliage comportant du niobium et de l'hafnium.The invention relates to a spiral spring intended to equip a balance wheel with a watch movement and made from an alloy comprising niobium and hafnium.

On va décrire un procédé de fabrication d'un tel ressort spiral.We will describe a process for manufacturing such a spiral spring.

Le procédé comprend les étapes suivantes :

  • une étape d'élaboration d'une ébauche dans un alliage de niobium et d'hafnium constitué de :
    • niobium : balance à 100% en poids,
    • hafnium: entre 8 et 12% en poids,
  • les éléments : Ti, Zr, Ta, W avec un pourcentage pour chaque élément compris entre 0.2 et 1.5% en poids et dont les pourcentages spécifiques seront donnés dans la suite,
    • impuretés avec un pourcentage total de ces dernières compris entre 0 et 0.5% en poids. Plus précisément, les impuretés peuvent être des traces d'éléments sélectionnés parmi le groupe constitué de O, H, C, Fe, N, Ni, Si, Cu, Al, Cr, Mn, V, Sn, Mg, Mo, Pb, Co, B, chacun desdits éléments étant présent dans une quantité comprise entre 0 et 1000 ppm en poids,
  • une étape de recuit suivi d'un refroidissement de ladite ébauche,
  • une étape de dépôt d'un matériau ductile sur l'ébauche,
  • au moins une étape de déformation de l'ébauche pour former un fil, avec une étape de recuit et refroidissement entre les étapes de déformation lorsqu'il y a plusieurs étapes de déformation,
  • une étape d'estrapadage pour former le ressort spiral,
  • une étape finale de traitement thermique permettant de fixer la forme du ressort spiral et d'ajuster le coefficient thermoélastique.
The process includes the following steps:
  • a step of developing a blank in an alloy of niobium and hafnium consisting of:
    • niobium: balance at 100% by weight,
    • hafnium: between 8 and 12% by weight,
  • the elements: Ti, Zr, Ta, W with a percentage for each element between 0.2 and 1.5% by weight and the specific percentages of which will be given below,
    • impurities with a total percentage of the latter between 0 and 0.5% by weight. More precisely, the impurities may be traces of elements selected from the group consisting of O, H, C, Fe, N, Ni, Si, Cu, Al, Cr, Mn, V, Sn, Mg, Mo, Pb, Co, B, each of said elements being present in a quantity between 0 and 1000 ppm by weight,
  • an annealing step followed by cooling of said blank,
  • a step of depositing a ductile material on the blank,
  • at least one step of deformation of the blank to form a wire, with an annealing and cooling step between the deformation steps when there are several deformation steps,
  • a step of strapping to form the spiral spring,
  • a final heat treatment step allowing the shape of the spiral spring to be fixed and the thermoelastic coefficient to be adjusted.

L'ébauche comprend en poids entre 8 et 12% d'hafnium, du Ti compris dans un pourcentage entre 0.5 et 1.5%, du Zr dans un pourcentage compris entre 0.5 et 0.9%, du Ta dans un pourcentage compris entre 0.3 et 0.7%, du W dans un pourcentage compris entre 0.3 et 0.7%.The blank comprises by weight between 8 and 12% hafnium, Ti in a percentage between 0.5 and 1.5%, Zr in a percentage between 0.5 and 0.9%, Ta in a percentage between 0.3 and 0.7% , W in a percentage between 0.3 and 0.7%.

Avantageusement, l'ébauche en alliage NbHf utilisé pour la présente invention ne comprend pas d'autres éléments à l'exception d'éventuelles et inévitables traces. Cela permet d'éviter la formation de phases fragiles.Advantageously, the NbHf alloy blank used for the present invention does not include other elements with the exception of possible and inevitable traces. This makes it possible to avoid the formation of fragile phases.

Plus particulièrement, la teneur en oxygène est inférieure ou égale à 0.10% en poids du total, notamment inférieure ou égale à 0.05% en poids du total, voire encore inférieure ou égale à 0.03% en poids du total.More particularly, the oxygen content is less than or equal to 0.10% by weight of the total, in particular less than or equal to 0.05% by weight of the total, or even less than or equal to 0.03% by weight of the total.

Plus particulièrement, la teneur en carbone est inférieure ou égale à 0.04% en poids du total, notamment inférieure ou égale à 0.02% en poids du total, voire encore inférieure ou égale à 0.015% en poids du total.More particularly, the carbon content is less than or equal to 0.04% by weight of the total, in particular less than or equal to 0.02% by weight of the total, or even less than or equal to 0.015% by weight of the total.

Plus particulièrement, la teneur en fer est inférieure ou égale à 0.05% en poids du total, notamment inférieure ou égale à 0.02% en poids du total, voire encore inférieure ou égale à 0.005% en poids du total.More particularly, the iron content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.02% by weight of the total, or even less than or equal to 0.005% by weight of the total.

Plus particulièrement, la teneur en azote est inférieure ou égale à 0.04% en poids du total, notamment inférieure ou égale à 0.02% en poids du total, voire encore inférieure ou égale à 0.015% en poids du total.More particularly, the nitrogen content is less than or equal to 0.04% by weight of the total, in particular less than or equal to 0.02% by weight of the total, or even less than or equal to 0.015% by weight of the total.

Plus particulièrement, la teneur en hydrogène est inférieure ou égale à 0.01% en poids du total, notamment inférieure ou égale à 0.0035% en poids du total, voire encore inférieure ou égale à 0.001% en poids du total.More particularly, the hydrogen content is less than or equal to 0.01% by weight of the total, in particular less than or equal to 0.0035% by weight of the total, or even less than or equal to 0.001% by weight of the total.

Plus particulièrement, la teneur en silicium est inférieure ou égale à 0.05% en poids du total, notamment inférieure ou égale à 0.02% en poids du total, voire encore inférieure ou égale à 0.005% en poids du total.More particularly, the silicon content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.02% by weight of the total, or even less than or equal to 0.005% by weight of the total.

Plus particulièrement, la teneur en nickel est inférieure ou égale à 0.05% en poids du total, notamment inférieure ou égale à 0.01% en poids du total, voire encore inférieure ou égale à 0.002% en poids du total.More particularly, the nickel content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.

Plus particulièrement, la teneur en élément en solution solide ductile, tel que le cuivre, dans l'alliage, est inférieure ou égale à 0.05% en poids du total, notamment inférieure ou égale à 0.01% en poids du total, voire encore inférieure ou égale à 0.004% en poids du total.More particularly, the content of element in ductile solid solution, such as copper, in the alloy, is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.05% by weight of the total. equal to 0.004% by weight of the total.

Plus particulièrement, la teneur en aluminium est inférieure ou égale à 0.05% en poids du total, notamment inférieure ou égale à 0.01% en poids du total, voire encore inférieure ou égale à 0.002% en poids du total.More particularly, the aluminum content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.

Plus particulièrement, la teneur en chrome est inférieure ou égale à 0.05% en poids du total, notamment inférieure ou égale à 0.01% en poids du total, voire encore inférieure ou égale à 0.002% en poids du total.More particularly, the chromium content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.

Plus particulièrement, la teneur en manganèse est inférieure ou égale à 0.05% en poids du total, notamment inférieure ou égale à 0.01% en poids du total, voire encore inférieure ou égale à 0.002% en poids du total.More particularly, the manganese content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.

Plus particulièrement, la teneur en vanadium est inférieure ou égale à 0.05% en poids du total, notamment inférieure ou égale à 0.01% en poids du total, voire encore inférieure ou égale à 0.002% en poids du total.More particularly, the vanadium content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.

Plus particulièrement, la teneur en étain est inférieure ou égale à 0.01% en poids du total, notamment inférieure ou égale à 0.0035% en poids du total, voire encore inférieure ou égale à 0.001% en poids du total.More particularly, the tin content is less than or equal to 0.01% by weight of the total, in particular less than or equal to 0.0035% by weight of the total, or even less than or equal to 0.001% by weight of the total.

Plus particulièrement, la teneur en magnésium est inférieure ou égale à 0.05% en poids du total, notamment inférieure ou égale à 0.01% en poids du total, voire encore inférieure ou égale à 0.002% en poids du total.More particularly, the magnesium content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.

Plus particulièrement, la teneur en molybdène est inférieure ou égale à 0.05% en poids du total, notamment inférieure ou égale à 0.01% en poids du total, voire encore inférieure ou égale à 0.002% en poids du total.More particularly, the molybdenum content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.

Plus particulièrement, la teneur en plomb est inférieure ou égale à 0.05% en poids du total, notamment inférieure ou égale à 0.01% en poids du total, voire encore inférieure ou égale à 0.002% en poids du total.More particularly, the lead content is less than or equal to 0.05% by weight of the total, in particular less than or equal to 0.01% by weight of the total, or even less than or equal to 0.002% by weight of the total.

Plus particulièrement, la teneur en cobalt est inférieure ou égale à 0.01% en poids du total, notamment inférieure ou égale à 0.0035% en poids du total, voire encore inférieure ou égale à 0.001% en poids du total.More particularly, the cobalt content is less than or equal to 0.01% by weight of the total, in particular less than or equal to 0.0035% by weight of the total, or even less than or equal to 0.001% by weight of the total.

Plus particulièrement, la teneur en bore est inférieure ou égale à 0.005% en poids du total, notamment inférieure ou égale à 0.0001% en poids du total.More particularly, the boron content is less than or equal to 0.005% by weight of the total, in particular less than or equal to 0.0001% by weight of the total.

L'étape de recuit est un traitement de mise en solution, avec une durée comprise, de préférence, entre 5 minutes et 2 heures à une température comprise entre 650°C et 1750°C, sous vide, suivie d'une trempe par exemple sous gaz pour obtenir l'Hf en solution solide sursaturée dans le Nb ß. Selon une variante, un refroidissement naturel sous vide peut aussi être envisagé.The annealing step is a solution treatment, with a duration of preferably between 5 minutes and 2 hours at a temperature of between 650°C and 1750°C, under vacuum, followed by quenching for example under gas to obtain Hf in supersaturated solid solution in Nb ß. According to a variant, natural cooling under vacuum can also be considered.

L'étape de dépôt du procédé permettant de fabriquer le ressort spiral qui fait plus particulièrement l'objet de l'invention consiste à déposer une couche d'un matériau ductile choisi parmi le groupe comprenant le cuivre, le nickel, le cupro-nickel, le cupro-manganèse, l'or, l'argent, le nickel-phosphore Ni-P et le nickel-bore Ni-B, pour faciliter la mise en forme sous forme de fil. Préférentiellement, l'épaisseur de la couche de matériau ductile déposée est choisie de sorte que le rapport surface de matériau ductile/surface de l'alliage NbHf pour une section de fil donnée est inférieur à 1, de préférence inférieur à 0.5, et plus préférentiellement compris entre 0.01 et 0.4. A titre d'exemple, pour un diamètre total du fil de 0.1 mm, la couche de matériau ductile peut avoir une épaisseur de 7 µm pour une section en alliage de NbHf de 0.086 mm de diamètre. Cela correspond à un rapport entre la surface de cuivre (0.002 mm2) et la surface de NbHf (0.0058 mm2) de 0.35.The deposition step of the process making it possible to manufacture the spiral spring which is more particularly the subject of the invention consists of depositing a layer of a ductile material chosen from the group comprising copper, nickel, cupro-nickel, cupro-manganese, gold, silver, nickel-phosphorus Ni-P and nickel-boron Ni-B, to facilitate shaping into wire form. Preferably, the thickness of the layer of ductile material deposited is chosen so that the ratio of surface area of ductile material/surface area of the NbHf alloy for a given wire section is less than 1, preferably less than 0.5, and more preferably between 0.01 and 0.4. For example, for a total wire diameter of 0.1 mm, the layer of ductile material can have a thickness of 7 µm for an NbHf alloy section of 0.086 mm in diameter. This corresponds to a ratio between the copper surface area (0.002 mm 2 ) and the NbHf surface area (0.0058 mm 2 ) of 0.35.

Une telle épaisseur de matériau ductile, et notamment de cuivre, permet d'étirer, de tréfiler et de laminer aisément le matériau composite Cu/NbHf. En effet, l'épaisseur de cuivre est optimisée pour que la pointe, créée par limage ou par étirage à chaud, nécessaire à l'introduction du fil dans la filière lors de l'étirage ou du tréfilage soit recouverte de cuivre.Such a thickness of ductile material, and in particular of copper, makes it possible to easily stretch, draw and roll the Cu/NbHf composite material. In fact, the copper thickness is optimized so that the tip, created by filing or hot drawing, necessary for introducing the wire into the die during drawing or drawing, is covered with copper.

Le matériau ductile, de préférence du cuivre, est ainsi déposé à un moment donné pour faciliter la mise en forme du fil par étirage, tréfilage et laminage, de telle manière à ce qu'il en reste une épaisseur de préférence comprise entre 1 et 500 micromètres sur le fil au diamètre total de 0.2 à 1 millimètre.The ductile material, preferably copper, is thus deposited at a given moment to facilitate the shaping of the wire by drawing, drawing and rolling, in such a way that a thickness remains, preferably between 1 and 500 micrometers on the wire with a total diameter of 0.2 to 1 millimeter.

L'apport de matériau ductile peut être galvanique, par PVD ou CVD, ou bien mécanique, c'est alors une chemise ou un tube de matériau ductile tel que le cuivre qui est ajusté sur une barre d'alliage NbHf à un gros diamètre, puis qui est amincie au cours de la ou des étapes de déformation du barreau composite. Ainsi, une possibilité est de former une billette composite par assemblage d'une barre de Nb-Hf et d'une chemise de cuivre qui est ensuite extrudée.The addition of ductile material can be galvanic, by PVD or CVD, or mechanical, it is then a jacket or a tube of ductile material such as copper which is adjusted to an NbHf alloy bar with a large diameter, then which is thinned during the step(s) of deformation of the composite bar. Thus, one possibility is to form a composite billet by assembling a Nb-Hf bar and a copper jacket which is then extruded.

L'étape de déformation désigne d'une manière globale un ou plusieurs traitements de déformation, qui peuvent comprendre le tréfilage et/ou le laminage. Le tréfilage peut nécessiter l'utilisation d'une ou plusieurs filières lors de la même étape de déformation ou lors de différentes étapes de déformation si nécessaire. Le tréfilage est réalisé jusqu'à l'obtention d'un fil de section ronde. Le laminage peut être effectué lors de la même étape de déformation que le tréfilage ou dans une autre étape de déformation ultérieure. Avantageusement, le dernier traitement de déformation appliqué à l'alliage est un laminage, de préférence à profil rectangulaire compatible avec la section d'entrée d'une broche d'estrapadage.The deformation step generally designates one or more deformation treatments, which may include wire drawing and/or rolling. Wire drawing may require the use of one or more dies during the same deformation stage or during different deformation stages if necessary. Drawing is carried out until a round section wire is obtained. Rolling can be carried out in the same deformation step as wire drawing or in another subsequent deformation step. Advantageously, the last deformation treatment applied to the alloy is rolling, preferably with a rectangular profile compatible with the entry section of a strapping pin.

Le procédé peut comporter une étape ou plusieurs étapes de déformation avec un taux de déformation pour chaque étape compris entre 1 et 5, de préférence entre 2 et 5, le taux de déformation répondant à la formule classique 2ln(d0/d) où d0 et d sont respectivement le diamètre avant et après déformation. Le taux total de déformation peut être compris entre 1 et 14.The process may comprise one step or several deformation steps with a deformation rate for each step of between 1 and 5, preferably between 2 and 5, the deformation rate corresponding to the classic formula 2ln(d0/d) where d0 and d are respectively the diameter before and after deformation. The total strain rate can be between 1 and 14.

Le procédé peut comporter des étapes intermédiaires de recuit entre les différentes étapes de déformation.The process may include intermediate annealing stages between the different deformation stages.

Le procédé qui permet de fabriquer le ressort spiral selon l'invention comprend préférentiellement, après l'étape de déformation, une étape d'élimination de ladite couche de matériau ductile. De préférence, le matériau ductile est éliminé une fois toutes les opérations de déformation effectuées, c'est-à-dire après le dernier laminage, avant l'estrapadage. Cependant, il n'est pas exclu d'éliminer la couche de matériau ductile avant d'avoir finalisé toutes les opérations de déformation. Il est ainsi envisageable lors d'un laminage en plusieurs passes d'éliminer la couche de matériau ductile avant la dernière passe de laminage. De préférence, le fil est débarrassé de sa couche de matériau ductile, tel que le cuivre, notamment par attaque chimique, avec une solution à base de cyanures ou à base d'acides, par exemple d'acide nitrique.The method which makes it possible to manufacture the spiral spring according to the invention preferably comprises, after the deformation step, a step of eliminating said layer of ductile material. Preferably, the ductile material is eliminated once all the deformation operations have been carried out, that is to say after the last rolling, before strapping. However, it is not excluded to eliminate the layer of ductile material before having finalized all the deformation operations. It is therefore possible during rolling in several passes to eliminate the layer of ductile material before the last rolling pass. Preferably, the wire is freed from its layer of ductile material, such as copper, in particular by chemical attack, with a solution based on cyanides or based on acids, for example nitric acid.

Le recuit préalable à l'étape de déformation de même que les recuits intermédiaires effectués entre les étapes de déformation est réalisé pendant une durée comprise entre 5 minutes et 2 heures, de préférence entre 10 minutes et 1 heure à une température comprise entre 650°C et 1750°C.The annealing prior to the deformation stage as well as the intermediate annealing carried out between the deformation stages is carried out during a duration of between 5 minutes and 2 hours, preferably between 10 minutes and 1 hour at a temperature of between 650°C and 1750°C.

Le traitement thermique final après l'estrapadage est réalisé à une température comprise entre 500 et 1250°C pendant un temps compris entre 30 minutes et 30 heures. Selon la composition de l'alliage et les températures, une structure monophasée de type cubique centrée ou biphasée avec une structure cubique centrée et une structure hexagonale compacte peut être obtenue à l'issue de ce traitement thermique.The final heat treatment after strapping is carried out at a temperature between 500 and 1250°C for a time between 30 minutes and 30 hours. Depending on the composition of the alloy and the temperatures, a single-phase structure of centered cubic or two-phase type with a centered cubic structure and a compact hexagonal structure can be obtained at the end of this heat treatment.

Le procédé ci-dessus permet la réalisation, et plus particulièrement la mise en forme, d'un ressort spiral pour balancier en alliage de type niobium-hafnium, tel que revendiqué. Cet alliage présente des propriétés mécaniques élevées, en combinant une limite élastique très élevée, supérieure à 600 MPa, et un module d'élasticité très bas, de l'ordre de 60 GPa à 100 GPa. Cette combinaison de propriétés convient bien pour un ressort spiral. De plus, un tel alliage est paramagnétique.The above process allows the production, and more particularly the shaping, of a spiral spring for a balance wheel made of a niobium-hafnium type alloy, as claimed. This alloy has high mechanical properties, combining a very high elastic limit, greater than 600 MPa, and a very low modulus of elasticity, of the order of 60 GPa to 100 GPa. This combination of properties is well suited for a spiral spring. In addition, such an alloy is paramagnetic.

Un alliage de type binaire comportant du niobium et de l'hafnium, du type sélectionné ci-dessus pour la mise en oeuvre de l'invention, présente également un effet similaire à celui de l' « Elinvar », avec un coefficient thermo-élastique pratiquement nul dans la plage de températures d'utilisation usuelle de montres, et apte à la fabrication de spiraux auto-compensateurs.A binary type alloy comprising niobium and hafnium, of the type selected above for the implementation of the invention, also has an effect similar to that of "Elinvar", with a thermo-elastic coefficient practically zero in the usual temperature range of watches, and suitable for the manufacture of self-compensating hairsprings.

Claims (1)

  1. Balance spring intended to equip a balance of a horological movement, the balance spring being made of a niobium and hafnium alloy containing;
    - niobium: the remainder to 100 wt%,
    - hafnium: between 8 and 12 wt%,
    - Ti between 0.5 and 1.5 wt%,
    - Zr between 0.5 and 0.9 wt%,
    - Ta between 0.3 and 0.7 wt%,
    - W between 0.3 and 0.7 wt%,
    - impurities, the total percentage whereof lies in the range 0 to 0.5 wt%.
EP21170773.2A 2019-05-07 2019-05-07 Horological hairspring made of a nb-hf alloy Active EP3889691B1 (en)

Priority Applications (1)

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EP21170773.2A EP3889691B1 (en) 2019-05-07 2019-05-07 Horological hairspring made of a nb-hf alloy

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EP19173114.0A EP3736639A1 (en) 2019-05-07 2019-05-07 Method for manufacturing a hairspring for clock movement
EP21170773.2A EP3889691B1 (en) 2019-05-07 2019-05-07 Horological hairspring made of a nb-hf alloy

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EP3889691B1 true EP3889691B1 (en) 2024-02-21

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EP4060424A1 (en) 2021-03-16 2022-09-21 Nivarox-FAR S.A. Hairspring for timepiece movement
EP4123393A1 (en) 2021-07-23 2023-01-25 Nivarox-FAR S.A. Hairspring for clock movement

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1521206A (en) * 1966-06-08 1968-04-12 Vacuumschmelze Gmbh Process for the preparation of non-ferromagnetic alloys with adjustable temperature coefficient of modulus of elasticity, as well as products conforming to those obtained by the present process or similar process
EP0886195B1 (en) * 1997-06-20 2002-02-13 Montres Rolex Sa Auto-compensating spring for mechanical oscillatory spiral spring of clockwork movement and method of manufacturing the same
DE69911913T2 (en) * 1999-03-26 2004-09-09 Rolex Sa Self-compensating coil spring for clockwork coil spring balance and method for treating the same
DE1258786T1 (en) 2001-05-18 2003-08-14 Rolex Sa Self-compensating spring for a mechanical oscillator of the balance spring type
JP2005140674A (en) * 2003-11-07 2005-06-02 Seiko Epson Corp Spring, spiral spring and hair spring for watch, and watch
US10372083B2 (en) * 2012-07-06 2019-08-06 Rolex Sa Method for treating a surface of a timepiece component, and timepiece component obtained from such a method
WO2014034766A1 (en) * 2012-08-31 2014-03-06 シチズンホールディングス株式会社 Hair spring material for mechanical clock and hair spring using same
EP3040790A1 (en) * 2014-12-29 2016-07-06 Montres Breguet S.A. Timepiece or piece of jewellery made of a light titanium-based precious alloy
EP3252542B1 (en) * 2016-06-01 2022-05-18 Rolex Sa Part for fastening a timepiece hairspring
EP3422116B1 (en) 2017-06-26 2020-11-04 Nivarox-FAR S.A. Timepiece hairspring

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JP2020183940A (en) 2020-11-12
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CN111913380A (en) 2020-11-10
US20200356057A1 (en) 2020-11-12
US11550263B2 (en) 2023-01-10

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