Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
  • B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/02—Sand moulds or like moulds for shaped castings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D13/00—Centrifugal casting; Casting by using centrifugal force
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D15/00—Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D25/00—Special casting characterised by the nature of the product
  • B22D25/02—Special casting characterised by the nature of the product by its peculiarity of shape; of works of art
  • B22D25/026—Casting jewelry articles
• • 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
• • 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
• • 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
  • G04B15/00—Escapements
  • G04B15/14—Component parts or constructional details, e.g. construction of the lever or the escape wheel
• • 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
  • G04B17/28—Compensation of mechanisms for stabilising frequency for the effect of imbalance of the weights, e.g. tourbillon
  • G04B17/285—Tourbillons or carrousels
• • 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
  • G04B19/00—Indicating the time by visual means
  • G04B19/04—Hands; Discs with a single mark or the like
  • G04B19/042—Construction and manufacture of the hands; arrangements for increasing reading accuracy

Definitions

• the present invention relates to a method for manufacturing a micromechanical piece of amorphous metal.
• the technical field of the invention is the technical field of fine mechanics. More specifically, the invention will belong to the technical field of manufacturing methods of amorphous metal parts.
• micromechanical parts Various methods are known for producing micromechanical parts. Indeed, these can be performed by micromachining or stamping or by injection into a mold.
• an advantageous solution consists in directly casting the piece of amorphous metal so as to obtain by foundry the final geometry or a geometry close to the final geometry requiring little retouching.
• the absence of crystalline structure implies that the properties of the amorphous metal part (in particular the mechanical properties, the hardness and the polishability) do not depend on the method of manufacture. This is a major advantage over traditional polycrystalline metals where the castings have lower properties compared to forged parts.
• a first problem comes from the cooling of the mold. This disadvantage can be seen in two aspects.
• a first aspect is that the cooling must not be too slow because there is then a risk of partial or total crystallization and thus lose the properties of the amorphous metals.
• the cooling must not be too slow because there is then a risk of partial or total crystallization and thus lose the properties of the amorphous metals.
• the presence of a single crystallite may be unacceptable for reasons of mechanical properties or visual appearance, since such crystallites will inevitably occur during the finishing steps. It is therefore essential to have a sufficiently rapid cooling during casting to ensure the amorphicity of the room.
• the molds are made of metal, for example steel or copper, for quickly extracting heat. Depending on the capacity of the chosen alloy to become amorphous, it is possible with this method to obtain pieces of thickness of the order of 10mm.
• the second aspect to consider is that the cooling must not be too fast because there is a risk of solidification before the mold cavity is completely filled.
• metal molds such as copper or steel
• the thermal energy is quickly dispersed causing a risk of early solidification.
• a second disadvantage is a formatting problem.
• This formatting problem comes from the small size of the mold and the footprint of the micromechanical part to be manufactured.
• the cost of these inserts and additional operations related thereto can become very high, making the process unusable industrially.
• Another advantageous solution is to use the shaping properties of the amorphous metals. Indeed, the amorphous metals have the particular characteristic of softening while remaining amorphous in a given temperature range [Tg - Tx] specific to each alloy and low because these temperatures Tg and Tx are low. This makes it possible to accurately reproduce fine and precise geometries because the viscosity of the alloy decreases sharply and the latter can be easily deformed in order to match all the details of a mold.
• the time available before the alloy crystallizes is limited. If the geometry has many complexities of small thicknesses, the time required for complete filling of the mold may be longer than the time available, resulting in partial or complete crystallization of the part and a loss of its mechanical properties in particular.
• LIGA A similar known technique is LIGA technology.
• the LIGA consists of three main stages of treatment; lithography, electroplating and molding.
• LIGA structures manufactured by the X-ray method include:
• X-Ray LIGA is a microtechnology manufacturing process developed in the early 1980s.
• an X-ray sensitive photoresist typically PMMA (poly (methylmethacrylate)
• PMMA poly (methylmethacrylate)
• Chemical removal from exposed (or unexposed) areas ) of the photoresist polymer provides a three-dimensional structure that can be filled by metal plating.
• the resin is chemically removed to produce a metal mold insert.
• the mold insert can be used to produce polymer or ceramic parts by injection molding.
• the main advantage of the LIGA technique is the precision achieved by the use of X-ray lithography (DXRL). This technique allows for microstructures with high aspect ratios and high accuracy to be manufactured in a variety of materials (metals, plastics and ceramics).
• the LIGA UV technique uses an inexpensive ultraviolet light source, such as a mercury lamp, to expose a photoresist, typically SU-8. Because heating and transmission are not a problem in optical masks, a simple chrome mask can be substituted for the sophisticated X-ray mask technique. These simplifications make the LIGA UV technique a much cheaper and more accessible technique than its X-ray counterpart. However, the LIGA UV technique is not as efficient in producing precision molds and is therefore used when the cost must be kept low and when very high aspect ratios are not required.
• the LIGA process poses a problem concerning the choice of materials. Indeed, two materials are needed: a material for the substrate and a material that will be deposited.
• the material for the substrate must be photo-structuring so that the plaster or zircon is not usable.
• For the deposited material it must be deposited electroplating so that the metal materials are the only ones that can be envisaged.
• such materials generally have thermal characteristics such that they ensure good heat dissipation and therefore good cooling. This ability to dissipate heat energy would cause, for an amorphous metal alloy formed in the LIGA mold, a hardening too fast and thus prevent good formation of parts.
• the invention relates to a method for producing a first part which overcomes the disadvantages of the prior art by making it possible to obtain a method of manufacturing a component made of a first metallic material, said first material being a material capable of become at least partially amorphous, said process comprising the following steps: a) providing a mold made of a second material, said mold having a cavity forming the negative of the component;
• the second material forming the mold has a thermal effusivity ranging from 250 to 2500 J / K / m 2 / s ° 5 .
• step c) consists of dissolving said mold.
• said first material is subjected to a rise in temperature above its melting point allowing it to lose locally any crystalline structure, said rise being followed by cooling to a temperature below its temperature. transition glass allowing said first material to become at least partially amorphous.
• the shaping step b) is simultaneous with a treatment rendering said first material at least partially amorphous, by subjecting it to a temperature above its melting point followed by cooling to a temperature lower than its glass transition temperature allowing it to become at least partially amorphous, during a casting operation.
• This embodiment is characterized in that the critical cooling speed of the first material is less than 10K / s.
• the shaping is done by injection.
• the shaping is done by centrifugal casting.
• the second material is zircon having an effusivity of 2300 J / K / m 2 / s 0 5 .
• the second material is of the plaster type composed mainly of gypsum and / or silica, having an effusivity of between 250 and 1000 J / K / m 2 / s ° 5 .
• the first material has a critical cooling rate of less than or equal to 10 K / s.
• the invention also relates to a component made in a first material being a metallic material capable of becoming at least partially amorphous, characterized in that it is manufactured using the method according to the invention.
• the invention further relates to a timepiece or jewelery comprising the component according to the invention, said component is selected from the list comprising a middle part, a bezel, a bracelet link, a cog, a needle, a crown, an escapement anchor or balance, a tourbillon cage, a ring, a cufflink or an earring or a pendant.
• FIGS 1 to 6 show the various steps of the method of producing a watch component or jewelry 1 also called first piece 1 according to the present invention.
• This first piece 1 is made of a first material.
• This first piece 1 may be a piece of clothing such as a caseband, a bezel, a bracelet link, a ring, cufflinks or earrings or a pendant or a functional piece such as a cogwheel 3, a needle , a crown, an anchor 5 or a balance 7 exhaust system 9, a tourbillon cage.
• the first material is advantageously an at least partially amorphous material. More particularly, the material is metallic, it is understood that it comprises at least one metal or metalloid element in a proportion of at least 50% by weight.
• the first material may be a homogeneous metal alloy or an at least partially or totally amorphous metal.
• the first material is thus chosen able to locally lose any crystalline structure during a rise in temperature above its melting temperature followed by sufficiently rapid cooling to a temperature below its glass transition temperature, allowing it to become at least partially amorphous.
• the metal element may be valuable or not.
• the first step, shown in Figure 2 is to provide a mold 10. This mold 10 has a cavity 12 which is the negative of the part 1 to achieve. This is a mold called lost wax.
• This type of mold consists of a mold 10 made of a material that can be destroyed or dissolved after use to release said part.
• the advantage of this type of mold is its ease of manufacture and demolding, which is independent of the geometry of the print. It is thus possible to easily make fingerprints of complex geometries and / or recesses, without inserts.
• This mold may be obtained by covering a wax or resin model, itself obtained by injection, additive manufacturing, machining, or sculpture.
• This mold 10 comprises a conduit 14 so that the liquid metal can be poured therein.
• This mold 10 is thus made of a second material.
• the mold material is chosen to have specific thermal properties. Indeed, the aim here is to have a mold for casting lost wax which is made of a material allowing the amorphous material of the micromechanical part not to crystallize while completely filling the mold cavity.
• Crystallization of amorphous metals occurs when these, when in a viscous or liquid state, are not cooled fast enough to prevent the atoms from structuring themselves.
• this characteristic is defined by the critical cooling rate, Rc, ie the minimum cooling rate to be respected between the melting point and the glass transition temperature in order to maintain an amorphous state of the material. Therefore, it becomes necessary to have a mold 10 made of a material that dissipates heat energy well enough to ensure a cooling rate R greater than Rc.
• foundry molds are made of steel or cuprous alloys to have a high R value.
• the present invention proposes to use the criterion of thermal effusivity E in combination with Rc.
• the thermal effusivity of a material characterizes its ability to exchange thermal energy with its environment. It is given by:
• ⁇ is the thermal conductivity of the material (in Wm 1 -K 1 )
• This effusivity makes it possible, according to the thickness of the first part to be produced, to obtain a cooling which guarantees an amorphous state of the material, that is to say R> Rc. Indeed, if the criterion of effusiveness is important, the amorphicity is related to the thickness of the part to be manufactured. It is easily understood that, for a given thickness, a high effusivity may result in solidification of the material before it has been able to fill the entire mold while too little effusivity may cause crystallization. According to the invention, it will be considered that the effusivity will be chosen within a range of 250 to 2500 J / K / m 2 / s 0 5 .
• the effusivity of plaster-type materials is 250 - 1000 J / K / m 2 / s ° 5 while for zircon it will be 2300 J / K / m 2 / s 0 5 .
• the second step is to provide the first material, that is to say the material constituting the first part 1. Once provided with the material, the remainder of this second step consists of shaping it as shown in FIGS. 3 and 4. For this, a casting method is used.
• Such a method consists in taking the first material which was provided during the third step without having subjected it to a treatment making it at least partially amorphous and put it under liquid form. This liquid forming is done by melting said first material in a pouring container 20.
• the first material in liquid form is poured into the cavity 2 of the mold.
• the first material is then cooled so as to give it an amorphous shape.
• the cooling is carried out by heat dissipation of the mold 10, that is to say using only the thermal characteristics of the constituent material of the mold, in other words the cooling is achieved only thanks to the Effusiveness of the mold and the only mold / air interface to give the amorphous or at least partially amorphous character to the metallic material of the component. Cooling is therefore performed without the use of any other quenching medium (quenching medium) than air or a gas, for example helium.
• quenching medium quenching medium
• the constituent material of the mold 10 will be chosen to have effusivity in the range of 250 to 2500 J / K / m 2 / s 0 5 ⁇ this thermal effusivity of a material being the capacity of the latter to exchange thermal energy with its environment.
• the cooling rate R is low compared to the traditionally used metal molds.
• the effusivity of steel is more than 1 0 ⁇ 00 J / K / m 2 / s 0 5 and copper more than 35 ⁇ 00 J / K / m 2 / s 0 5 .
• a mold used in the present invention may be made of a metallic material.
• a first piece of amorphous metal having a thickness of between 0.5 mm and 1 .4 mm, being understood as explained above that lower details thickness are achievable if they are punctual and limited in size.
• parts or parts of parts greater than 1 .4 mm thick can be made without crystallization if they are considered as point details and small dimensions.
• An advantage of casting a metal or alloy capable of being amorphous is to have a low melting point. Indeed, the melting temperatures of metals or alloys capable of having an amorphous form, are in general two to three times lower than those of conventional alloys when one considers compositions of the same types. For example, the melting temperature of the alloy Zr41 .2 ⁇ 1 3.8Cu12.5NM 0Be22.5 is 750 ° C compared to 1500-1700 ° C crystalline alloys based on zirconium Zr and Ti titanium. This avoids damaging the mold.
• Another advantage is that the solidification shrinkage, for an amorphous metal, is very low, less than 1% relative to the shrinkage of 5 to 7% for a crystalline metal. This advantage allows to use the principle of casting without fear of surface defects or significant changes in size that would be the consequence of said withdrawal.
• Another advantage is that the mechanical and polishability properties of the amorphous metals do not depend on the process of as long as they are amorphous.
• the parts obtained by casting will have the same properties as forged parts, machined, or deformed hot, which is a major advantage over crystalline metals whose properties strongly depend on the crystal structure, itself related to the history of the process of obtaining the piece.
• the casting may be of the gravitational type.
• the metal fills the mold under the effect of gravity.
• the casting may be of the centrifugal type.
• centrifugal casting utilizes the principle that the mold is rotated rapidly. The liquid metal poured inside sticks to the wall by centrifugal force and solidifies. This technique allows a centrifugation and a pressure on the material which causes a degassing and expels to the external part the impurities contained in the bath of liquid metal. Smaller cavities can be filled compared to simple gravitational casting.
• the casting may be of the injection type.
• injection molding uses the principle that the mold is filled with a piston that applies a very large force to push the liquid metal. This thrust then makes it possible to introduce the liquid metal into the mold in order to better fill it.
• the casting may be of the counter-gravity type, by die casting, by vacuum casting.
• the third step consists in separating the first piece 1 from the mold 10.
• the mold 10 in which the amorphous metal has been overmolded to form the first part 1, is destroyed using a jet of water under high pressure, by dissolving in water or chemical solution, or by mechanical removal.
• a chemical solution it is chosen to specifically attack the mold 10.
• the purpose of this step is to dissolve the negative 1 without dissolving the first piece 5 made of amorphous metal.
• a solution of hydrofluoric acid is used to dissolve the mold. The final result is then obtaining the first piece of amorphous metal.
• the first step consisting in acquiring the negative 1 can also include the fact of preparing the negative. Indeed, it is possible to decorate the negative 1 so that surface states can be directly made on the first part. . These surface conditions can be a decoration "Geneva coast", beaded, snailed diamond or satin.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Adornments (AREA)

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• 2015
  • 2015-11-18 EP EP15195197.7A patent/EP3170579A1/de not_active Withdrawn
• 2016
  • 2016-10-11 WO PCT/EP2016/074369 patent/WO2017084807A1/fr active Application Filing
  • 2016-10-11 RU RU2018121843A patent/RU2018121843A/ru not_active Application Discontinuation
  • 2016-10-11 CN CN201680067371.9A patent/CN108290213A/zh active Pending
  • 2016-10-11 EP EP16781383.1A patent/EP3377247B1/de active Active
  • 2016-10-11 US US15/776,861 patent/US10981223B2/en active Active
  • 2016-10-11 JP JP2018525451A patent/JP2019501780A/ja active Pending
  • 2016-10-11 CN CN202310723816.6A patent/CN116809900A/zh active Pending
• 2018
  • 2018-12-21 HK HK18116387.7A patent/HK1257133A1/zh unknown
• 2021
  • 2021-01-29 JP JP2021012946A patent/JP2021079451A/ja active Pending
• 2022
  • 2022-10-21 JP JP2022169031A patent/JP2023012487A/ja active Pending

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