Classifications

• • A—HUMAN NECESSITIES
  • A44—HABERDASHERY; JEWELLERY
  • A44C—PERSONAL ADORNMENTS, e.g. JEWELLERY; COINS
  • A44C27/00—Making jewellery or other personal adornments
  • A44C27/001—Materials for manufacturing jewellery
  • A44C27/002—Metallic materials
  • A44C27/003—Metallic alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/11—Making amorphous alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C5/00—Alloys based on noble metals
  • C22C5/02—Alloys based on gold
• • 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
  • C22F1/14—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of noble 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
  • G04B13/00—Gearwork
  • G04B13/02—Wheels; Pinions; Spindles; Pivots
• • 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
  • G04B37/00—Cases
  • G04B37/22—Materials or processes of manufacturing pocket watch or wrist watch cases

Definitions

• This hardening occurs by a change from the austenitic, disordered (AuCu)a phase, in which the alloy supplied by the refiner is located, to the AuCuII phase, then to the martensitic, ordered AuCuI phase which is stable below the AuCuII / AuCuI phase transition temperature which is around 350°C.
• This phase transformation occurs in alloys with contents between 14 K and 22K, including 18K.
• Such a process advantageously makes it possible to obtain a watch or jewelry component in a gold/copper alloy of at least 14K which respects manufacturing tolerances.
• the process of the invention advantageously makes it possible to improve the control dimension of the parts and thus reduce the number of defective components and rework operations.
• the present invention relates to a method of manufacturing a watch or jewelry component comprising at least one part made of at least binary metal alloy based on gold and copper comprising at least 58% gold by weight, and for example 34 % copper and 8% silver, which corresponds to a 14K alloy.
• the metal alloy can include up to 92% gold by weight, with 8% copper, which corresponds to a 22K alloy.
• the method according to the invention comprises at least one step a) consisting of providing a part comprising at least one solid part composed of the metal alloy defined above.
• These alloys are very generally supplied to watchmakers and jewelers prepared by refiners in an annealed state (for example at 650°C) then quenched in water at 25°C, so that said alloys are in the phase ( AuCu)a which is soft (around 165 HV for a 5N alloy as defined above) when the parts arrive at watchmaking and jewelry users.
• the watch or jewelry component manufactured according to the process of the invention can be any watch, jewelry or jewelry component made at least partially in the metal alloy defined above, such as an element of the exterior or movement of a watch, such as a wheel or a bridge, or a piece of jewelry.
• the method according to the invention also comprises a step b) consisting of applying different manufacturing operations to the part to obtain the watch or jewelry component in its finished state.
• These manufacturing operations to produce the watch or jewelry component 6 according to step b) include all the production operations necessary to obtain a finished product. They can be chosen for example from the group comprising storage, stamping, machining, such as machining by turning or milling, sintering, treatment thermal, engraving, such as laser engraving, punching, 3D printing, crimping, bonding, polishing, diamond plating, washing and soldering, different operations which can be used in combination.
• the theoretical phase transition temperatures AuCuI to AuCuII and AuCuII to (AuCu)a are close to each other (difference of 20°C in general, the elements of the alloy being able to increase or decrease this difference ), said temperatures being quite close to the real phase transition temperature AuCuI to (AuCu)a.
• the temperature drop to the ambient temperature of 25°C of step c) is a descent in temperature immediately after the first maintenance BC at the temperature TR, said descent taking place continuously at a speed of between 0.1 °C/min and 2°C/min, preferably between 0.5°C/min and 2°C/min, more preferably between 0.5°C/min and 1°C/min, up to the ambient temperature of 25°C, without temperature rise, according to the CD temperature curve shown in Figure 2.
• Such an implementation method makes it possible to obtain at least 95% of AuCuI ordered phase without it being necessary to apply a second hold at the temperature TP.
• the first drop in temperature is carried out at a speed between 0.1 °C/min and 6,000°C/min, preferably between 1°C/min and 10°C/min, preferably between 2°C/min and 10°C/min, the duration of the second holding at the temperature TP being between 1 minute to 48 hours, preferably between 10 minutes and 300 minutes, preferably between 30 minutes and 90 minutes, said duration being chosen to allow the alloy to transform into a state in which it has at least 25 % of AuCuI ordered phase for less than 75% of (AuCu)a phase, preferably at least 60% of AuCuI ordered phase for less than 40% of (AuCu)a phase, preferably at least 95% of AuCuI ordered phase for less than 5% (AuCu)a phase, and more preferably at least 99% AuCuI ordered phase for less than 1% (AuCu)a phase.
• There speed between 0.1 °C/min and 6,000°C/min, preferably between 1°C/min and 10°C/min, preferably between 2°C
• the duration of maintaining the temperature TP is chosen to allow the alloy to transform according to the desired transformation rate. For the same temperature TP, maintaining the temperature TP for a longer period makes it possible to increase the rate of transformation of the (AuCu)a phase into the AuCuI phase. The skilled person knows also that the choice of the temperature TP also makes it possible to obtain the rate of transformation of the (AuCu)a phase into the desired AuCuI phase.
• Step c) advantageously makes it possible to stabilize, that is to say preserve, the geometry that the part has at the time of implementation of step c).
• the flatness and circularity of the part are preserved during the implementation of step c).
• the heat treatment implemented in step c) of the process of the invention is chosen to obtain a transformation of at least 25%, preferably at least 60%, more preferably at least 95%. %, and more preferably at least 99%, of the disordered (AuCu)a phase in ordered AuCuI phase, perfectly thermodynamically stable below the phase transition temperature TTP, in order to obtain dimensional variations during the process of controlled and acceptable manufacturing in the watchmaking and jewelry fields.
• the shrinkage is approximately 0.18% for a 95% transformation, this shrinkage being constant for a 95% transformation rate and therefore repeatable whatever the the shape of the room.
• the shrinkage is approximately 0.19% for a 99% transformation, this shrinkage being constant for a 99% transformation rate and therefore repeatable whatever the the shape of the room.
• the shrinkage is all the more significant when the ratio atomic concentration of gold/atomic concentration of copper is close to 1.
• the heat treatment of step c) can be implemented to allow the alloy to transform into a state in which it has an ordered phase rate AuCuI d approximately 25% (with for example a temperature TP of approximately 120°C), so that the part obtained has controlled dimensional variations and a percentage of stabilized dimensional variation (i.e. stable dimensions) when 'a manufacturing operation is applied to it at a temperature between 25°C and approximately 110°C (such as storage at room temperature or washing at 110°C), said part exhibiting controlled dimensional variations if it is subjected at a temperature above 110°C.
• an ordered phase rate AuCuI d approximately 25% with for example a temperature TP of approximately 120°C
• a percentage of stabilized dimensional variation i.e. stable dimensions
• the AuCuI phase being perfectly stable at a temperature lower than the phase transition temperature which is below 350°C for the 5N alloy as defined above, the part will retain its geometry, properties, microstructure and aesthetics intact during short or prolonged exposure to a temperature below this value.
• the AuCuI phase has a hardness of approximately 300HV compared to that of the (AuCu)a phase which is 165HV. This therefore helps to improve the life of the manufactured component by increasing its resistance to scratches.
• a manufacturing process will preferably be used in which the heat treatment is carried out to transform at least 99% of the (AuCu)a phase into AuCuI in order to guarantee hardening of the 18K gold/copper alloy without deformation of the geometry. that the part had before the implementation of step c), while having perfect stability of the dimensions making it possible to guarantee stability of the dimensions during a next heat treatment at a temperature lower than the phase transition temperature TTP AuCuII / AuCuI.
• TTP AuCuII phase transition temperature
• Three other rings A4, A5, A6 are prepared according to step c) of the process of the invention and hardened at 300 HV by applying the TMM maximized stabilization heat treatment defined by a rise in temperature at a speed of 30°C/ min, a first maintenance at the temperature TR of 450°C for 60 minutes, a first drop in temperature to the temperature TP of 250°C at a speed of 2°C/min followed by the second maintenance at the temperature TP for 60 minutes followed by the second temperature drop at a speed of 20°C/min, as shown in Figure 3, the duration of the second maintenance at the temperature TP being non-zero.
• This TMM heat treatment for maximized stabilization of the alloy allows a transformation of 99% of the (AuCu)a phase into the AuCuI phase.
• three rings A7, A8, A9 supplied in the annealed state (at 650°C) then quenched in water at room temperature are hardened to 300 HV in the traditional way by exposing them to a temperature of 300° C for 60 min according to the TD heat treatment.
• the specimen E1 is simply treated according to the heat treatment R consisting of annealing at 650°C and quenching in water at room temperature.
• the E3 specimen was hardened by the standard TD treatment at 300°C for 60 minutes.
• Figure 6 shows the reduction in the average diameter of the rings A10, A11, A12 expected after the implementation of the TMM stabilization heat treatment, but in a very repeatable manner, being linked to the change in volume of the mesh.

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

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• 2023
  • 2023-06-01 WO PCT/EP2023/064674 patent/WO2023232938A1/fr not_active Ceased
  • 2023-06-01 EP EP23731562.7A patent/EP4533186A1/de active Pending
  • 2023-06-01 CH CH000580/2023A patent/CH719741A2/fr unknown

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