Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21F—WORKING OR PROCESSING OF METAL WIRE
  • B21F35/00—Making springs from wire
  • B21F35/04—Making flat springs, e.g. sinus springs
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
  • C21D8/1266—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest between cold rolling steps
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
  • C21D8/1277—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties involving a particular surface treatment
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
  • C21D9/02—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for springs
• • 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
• • 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
• • 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
  • 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
  • G04B17/20—Compensation of mechanisms for stabilising frequency
  • G04B17/22—Compensation of mechanisms for stabilising frequency for the effect of variations of temperature
  • G04B17/227—Compensation of mechanisms for stabilising frequency for the effect of variations of temperature composition and manufacture of the material used
• • 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
  • G04B43/00—Protecting clockworks by shields or other means against external influences, e.g. magnetic fields
  • G04B43/007—Antimagnetic alloys

Definitions

• the invention relates to a method of manufacturing a spiral spring for equipping a balance of a watch movement.
• spiral springs are also centered on the concern of thermal compensation, so as to ensure regular chronometric performance. This requires a thermoelastic coefficient close to zero. Spiral springs with limited sensitivity to magnetic fields are also desired.
• New spirals have been developed from niobium and titanium alloys.
• these alloys pose problems of sticking and seizing in drawing dies or wire drawing (diamond or hard metal) and against rolling rolls (hard metal or steel), which makes them almost impossible to transform into wires by the standard processes used for example for steel.
• An object of the present invention is to provide a method of manufacturing a spiral spring for equipping a balance of a clockwork movement to facilitate deformation, and more particularly to obtain easy rolling.
• the process comprises, before the deformation step, a step of depositing, on the alloy blank, a surface layer of a ductile material selected from the group consisting of copper, nickel, cupro-nickel, cupro-manganese, gold, silver, nickel-phosphorus Ni-P and nickel-boron Ni-B, to facilitate forming in wire form, the thickness of the layer of deposited ductile material being chosen so that the ratio of ductile material surface / NbTi alloy surface for a given wire section is less than 1, preferably lower at 0.5, and more preferably between 0.01 and 0.4.
• Such a manufacturing method facilitates the shaping in the form of wire NbTi alloy blank, and more specifically to facilitate drawing, drawing and rolling.
• the invention relates to a method of manufacturing a spiral spring for equipping a balance of a watch movement and made of a binary type alloy comprising niobium and titanium.
• the ⁇ -form titanium content in the alloy of the blank is preferably less than or equal to 2.5% by volume, or even close to or equal to 0.
• the alloy used in the present invention comprises between 40 and 49% by weight of titanium, preferably between 44 and 49% by weight of titanium, and more preferably between 46% and 48% by weight of titanium. , and preferably said alloy comprises more than 46.5% by weight of titanium and said alloy comprises less than 47.5% by weight of titanium.
• titanium content is too high, it appears a martensitic phase causing problems of fragility of the alloy during its implementation. If the level of niobium is too high, the alloy will be too soft.
• the development of the invention has made it possible to determine a compromise, with an optimum between these two characteristics close to 47% by weight of titanium.
• the titanium content is greater than or equal to 46.5% by weight relative to the total of the composition.
• the titanium content is less than or equal to 47.5% by weight relative to the total of the composition.
• the NbTi alloy used in the present invention does not include other elements with the exception of possible and inevitable traces. This avoids the formation of fragile phases.
• the oxygen content is less than or equal to 0.10% by weight of the total, or even less than or equal to 0.085% by weight of the total.
• the tantalum content is less than or equal to 0.10% by weight of the total.
• the carbon content is less than or equal to 0.04% by weight of the total, especially less than or equal to 0.020% by weight of the total, or even less than or equal to 0.0175% by weight of the total.
• the iron content is less than or equal to 0.03% by weight of the total, in particular less than or equal to 0.025% by weight of the total, or even less than or equal to 0.020% by weight of the total.
• the nitrogen content is less than or equal to 0.02% by weight of the total, especially less than or equal to 0.015% by weight of the total, or even less than or equal to 0.0075% 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 0.0005% by weight of the total.
• the silicon content is less than or equal to 0.01% by weight of the total.
• the nickel content is less than or equal to 0.01% by weight of the total, especially less than or equal to 0.16% by weight of the total.
• the content of ductile material, such as copper, in the alloy is less than or equal to 0.01% by weight of the total, especially less than or equal to 0.005% by weight of the total.
• the aluminum content is less than or equal to 0.01% by weight of the total.
• the spiral spring produced according to the invention has a yield strength greater than or equal to 600 MPa.
• this spiral spring has a modulus of elasticity less than or equal to 100 GPa, and preferably between 60 GPa and 80 GPa.
• the spiral spring produced according to the invention has a thermoelastic coefficient, also called CTE, which enables it to guarantee the maintenance of chronometric performance despite the variation of the operating temperatures of a watch incorporating such a spiral spring.
• the CTE of the alloy must be close to zero ( ⁇ 10 ppm / ° C) to obtain a thermal coefficient of the oscillator equal to ⁇ 0.6 s / d / ° C.
• E is the Young's modulus of the spiral spring, and in this formula, E, ⁇ and ⁇ are expressed in ° C -1 .
• CT is the thermal coefficient of the oscillator
• (1 / E, dE / dT) is the CTE of the spiral alloy
• ⁇ is the coefficient of expansion of the balance and ⁇ that of the spiral.
• Such a thickness of ductile material, and in particular of copper, makes it easy to draw, draw and roll the Cu / NbTi composite material.
• the ductile material preferably copper, is thus deposited at a given moment to facilitate the shaping of the wire by drawing and drawing, so that there remains a thickness preferably between 1 and 500 microns on the wire with a total diameter of 0.2 to 1 millimeter.
• the supply of ductile material in particular copper, may be galvanic, PVD or CVD, or mechanical, it is then a jacket or a ductile material tube such as copper which is fitted on a niobium alloy bar titanium to a large diameter, and which is thinned during the step or steps of deformation of the composite bar.
• the method of the invention may comprise, after the deformation step, a step of eliminating said superficial layer of ductile material.
• the ductile material is removed once all deformation processing operations have been performed, i.e. after the last rolling, prior to strapping.
• the yarn is stripped of its layer of ductile material, such as copper, in particular by etching, with a solution based on cyanides or based on acids, for example nitric acid.
• the surface layer of ductile material is preserved on the spiral spring, the thermoelastic coefficient of the niobium and titanium alloy being adapted accordingly to compensate for the effect of the ductile material.
• the thermoelastic coefficient of the niobium and titanium alloy can be easily adjusted by choosing the rate of deformation and the appropriate heat treatments.
• the surface layer of preserved ductile material makes it possible to obtain a final section of perfectly regular thread.
• the ductile material may be here copper or gold, deposited by galvanic, PVD or CVD.
• the method of the invention may further comprise a step of depositing, on the surface layer of preserved ductile material, a final layer of a material chosen from the group comprising Al 2 O 3 , TiO 2 , SiO 2 AlO, by PVD or CVD. It is also possible to provide a final layer of gold deposited by flash of galvanic gold if gold has not already been used as a ductile material of the superficial layer. Copper, nickel, cupro-nickel, cupro-manganese, silver, nickel-phosphorus Ni-P and nickel-boron Ni-B may also be used for the final layer, provided that the the final layer is different from the ductile material of the surface layer.
• This final layer has a thickness of 0.1 .mu.m to 1 .mu.m and makes it possible to color the hairspring or to obtain an insensitivity to climatic aging (temperature and humidity).
• the ⁇ quenching step is a dissolution treatment, with a duration of between 5 minutes and 2 hours at a temperature of temperature between 700 ° C and 1000 ° C, under vacuum, followed by cooling under gas.
• this beta quench is a solution treatment, between 5 minutes and 1 hour at 800 ° C under vacuum, followed by cooling under gas.
• the heat treatment is carried out for a period of between 1 hour and 80 hours or more, preferably between 1 hour and 15 hours at a temperature between 350 ° C and 700 ° C. More preferably, the heat treatment is carried out for a period of between 5 hours and 10 hours at a temperature between 350 ° C and 600 ° C. Even more preferentially, the heat treatment is carried out for a period of between 3 hours and 6 hours at a temperature of between 400 ° C. and 500 ° C.
• a deformation step generally refers to one or more deformation treatments, which may include drawing and / or rolling.
• the drawing may require the use of one or more dies during the same deformation step or during different deformation steps if necessary.
• the drawing is carried out until a wire of round section is obtained.
• the rolling can be carried out during the same deformation step as drawing or in another subsequent deformation step.
• the last deformation treatment applied to the alloy is a rolling, preferably rectangular profile compatible with the input section of a pinning pin.
• the total strain rate, the number of heat treatment and the parameters of the heat treatments are chosen to obtain a spiral spring having a thermoelastic coefficient as close as possible to 0. Moreover, depending on the rate of total deformation, the number of heat treatment and the parameters of the heat treatments, one obtains a NbTi alloy single-phase or two-phase.
• the number of heat treatment and deformation steps is limited so that the niobium and titanium alloy of the spiral spring obtained retains a structure in which the titanium of said alloy is essentially in the form of solid solution with niobium in the ⁇ -phase (centered cubic structure), the ⁇ -phase titanium content being less than or equal to 10% by volume, preferably less than or equal to 5% by volume, more preferably less than or equal to 2.5% in volume.
• the total deformation ratio is between 1 and 5, preferably between 2 and 5.
• a blank whose dimensions are closer to the desired final dimensions is used so as to limit the number of heat treatment and deformation steps and maintain a substantially single phase structure ⁇ of the NbTi alloy.
• the final structure of the alloy NbTi of the spiral spring may be different from the initial structure of the blank, for example the titanium content in ⁇ -form may have varied, the essential being that the final structure of the alloy NbTi of the spiral spring is substantially single-phase, the titanium of said alloy being essentially in the form of a solid solution with niobium in the ⁇ -phase, the ⁇ -phase titanium content being less than or equal to 10% by volume, preferably less than or equal to 5% by volume, more preferably less than or equal to 2.5% by volume.
• the ⁇ -phase titanium content is preferably less than or equal to 5% by volume, more preferably less than or equal to 2.5% by volume, or even close to or equal to 0.
• the method comprises a single deformation step with a strain rate of between 1 and 5, preferably between 2 and 5.
• a particularly preferred method of the invention comprises, after the quenching step ⁇ , the deposition step, on the alloy blank, of the surface layer of ductile material, a deformation step including drawing by means of several dies then a rolling, a step of strapping and a final step of heat treatment (called fixing).
• the method of the invention may further comprise at least one intermediate heat treatment step, so that the method comprises for example after the quenching step ⁇ , the deposition step, on the alloy blank, of the superficial layer of ductile material, a first deformation step, an intermediate heat treatment step, a second deformation step, the step of strapping and then a final heat treatment step.
• a series of sequences of an alternating deformation step with a heat treatment step is applied until an alloy of niobium and titanium of two-phase structure comprising a solid solution of niobium with ⁇ -phase titanium (centered cubic structure) and a niobium solid solution with ⁇ -phase titanium (compact hexagonal structure), the ⁇ -phase titanium content being greater than 10% by volume.
• heat treatments it is necessary to precipitate part of the ⁇ phase by heat treatments, according to the parameters indicated above, with a strong deformation between the heat treatments.
• longer heat treatments are applied than those used to obtain a single-phase spring alloy, for example heat treatments carried out for a period of between 15 hours and 75 hours at a temperature of between 350 ° C. and 500 ° C. .
• heat treatments are applied from 75h to 400h at 350.degree. C., from 25h to 400.degree. C. or from 18h to 480.degree.
• this second "two-phase" variant a blank is used which, after quenching, has a diameter much larger than that of the blank prepared for the first "single-phase" variant.
• use is made, for example, of a blank 30 mm in diameter after the ⁇ quenching, while using, for the first variant, a blank 0.2 to 2.0 mm in diameter after the ⁇ quenching.
• each deformation is carried out with a degree of deformation of between 1 and 5, the overall accumulation of the deformations over the whole of said succession of sequences bringing a total rate of deformation between 1 and 14.
• the degree of deformation corresponds to the conventional formula 21n (d0 / d), where d0 is the diameter of the last beta quench or that of a deformation step, and d is the diameter of the hardened yarn obtained at the stage of deformation. following deformation.
• the method comprises in this second variant between three and five coupled deformation-heat treatment sequences.
• the first coupled deformation-heat treatment sequence comprises a first deformation with at least 30% section reduction.
• each deformation-heat treatment coupled sequence other than the first, has a deformation between two heat treatments with at least 25% section reduction.
• the hardened ⁇ -phase alloy exhibits a strongly positive CT, and the precipitation of the ⁇ phase which has a strongly negative CT makes it possible to reduce the two-phase alloy to a CTE close to zero, which is particularly favorable.
• the method of the invention allows the realization, and more particularly the shaping, of a spiral spring for a balance of alloy of niobium-titanium type, typically 47% by weight of titanium (40-60%), having a essentially single phase ⁇ -Nb-Ti microstructure in which the titanium is in the form of a solid solution with niobium in the ⁇ phase or a very fine lamellar two-phase microstructure comprising a solid solution of niobium with ⁇ -phase titanium and a solid solution of niobium with titanium in the ⁇ phase.
• 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 80 GPa. This combination of properties is well suited for a spiral spring.
• Such an alloy is known and used for the manufacture of superconductors, such as magnetic resonance imaging apparatus, or particle accelerators, but is not used in watchmaking.
• a binary type alloy comprising niobium and titanium, of the type selected above for the implementation of the invention, also has an effect similar to that of the "Elinvar", with a substantially zero thermoelastic coefficient. in the temperature range of usual use of watches, and suitable for the manufacture of self-compensating spirals.
• such an alloy is paramagnetic.
• niobium alloy consisting of 53% by weight of niobium and 47% by weight of single phase titanium (Examples 1 to 3) and two-phase (Example 4) and covered with a surface layer of copper of different thicknesses, before drawing.

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• 2017
  • 2017-12-21 EP EP17209686.9A patent/EP3502288B1/de active Active
• 2018
  • 2018-12-06 US US16/211,289 patent/US20190196406A1/en not_active Abandoned
  • 2018-12-14 JP JP2018234274A patent/JP6751749B2/ja active Active
  • 2018-12-20 CN CN201811562272.5A patent/CN110007582B/zh active Active
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