Classifications

• • 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
  • B22D17/007—Semi-solid pressure die casting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/06—Permanent 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
  • B22D25/00—Special casting characterised by the nature of the product
  • B22D25/06—Special casting characterised by the nature of the product by its physical properties
• • 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
• • 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

Definitions

• the present invention relates to a method for manufacturing a part made of at least partially amorphous metal or metal alloy, said part comprising at least one area of primary interest made of at least partially amorphous metal or metal alloy and at least one area of secondary interest for which the dimensions and/or the surface condition and/or the properties of the at least partially amorphous metal or metal alloy can be modified during the method for manufacturing said part.
• the invention also relates to a metallic glass part obtained by such a manufacturing method.
• Metallic glasses or amorphous metals are metal alloys whose atomic structure is not crystalline. These alloys are generally produced by cooling sufficiently rapidly to prevent the formation of crystalline structures. The amorphous structure of the constituent material of these alloys gives them mechanical properties that are radically different from those of crystalline metals.
• metallic glasses have mechanical, physical, and chemical properties that are likely to have promising applications.
• parts made of Bulk Metallic Glass (BMG) generally have a yield strength, endurance limit, tensile strength, corrosion resistance, hardness, and wear resistance that are all higher than those of parts made of crystalline metal.
• BMG Bulk Metallic Glass
• These differences make metallic glasses materials of choice for the production of small parts, particularly in the field of watchmaking.
• the resistance of metallic glasses to wear and their ability to store a significant amount of energy through elastic deformation are two extremely interesting characteristics.
• Metallic glasses are, however, difficult to work with. Particularly during casting, it is necessary to find a good compromise when choosing the casting temperature. A high casting temperature allows for good mold filling but makes it difficult to quickly dissipate heat. If the casting temperature is relatively low, the liquid becomes too viscous to be distributed throughout the mold. In addition, some metallic glasses are more viscous than others. Furthermore, current knowledge of casting requires the development of impressions that facilitate mold filling in order to take into account the viscosity of the molten metallic glass. As a result, the long, thin blades sought after in the watchmaking field are difficult, if not impossible, to cast. Furthermore, metallic glasses are fragile materials with a limited, or sometimes non-existent, plastic deformation range.
• metallic glasses since they do not have a crystalline structure, metallic glasses also do not have dislocations. However, it is the latter which, by moving, propagate the plastic deformations and give the metal its ductility.
• metallic glasses have crystallization and melting temperatures which are relatively low. When working these glasses, it is therefore important to limit the heat input, so as not to risk heating them to their crystallization temperature, otherwise they lose their integrity and in particular alter their mechanical properties. Finally, the low thermal conductivity of metallic glasses makes it very difficult to cool them "to the core” quickly. It will be understood from the above that the machining methods traditionally used in watchmaking are not suitable for these new materials.
• machining methods traditionally used in watchmaking may not be optimal when manufacturing parts with complex geometry. Such parts require a very large number of machining operations. The risk of deforming, damaging, or even breaking the part throughout the manufacturing process and multiple machining steps is high, especially when the parts are thin.
• the present invention relates to a method for manufacturing a part made of at least partially amorphous metal or metal alloy, said part comprising at least one area of main interest made of at least partially amorphous metal or metal alloy, preferably amorphous, and at least one area of secondary interest for which the dimensions and/or the surface condition and/or the properties of the at least partially amorphous metal or metal alloy can be modified during the method for manufacturing said part.
• the method according to the invention does not include any step likely to modify the dimensions and/or the surface condition and/or the properties at least partially amorphous, and preferably entirely amorphous, metal or metal alloy of the at least one area of primary interest of the raw casting.
• the manufacturing method according to the invention makes it possible to obtain a metallic glass part whose areas of primary interest are obtained directly by molding and do not require any subsequent machining operation likely to harm the integrity of the metallic glass and whose areas of secondary interest can then be reworked during subsequent manufacturing steps, the possible loss of integrity of the metallic glass during these subsequent manufacturing steps being of no importance for the conformity of the part with respect to its specifications and its performance.
• the at least one area of main interest is intended to be subjected to stress during use of the part and is identified by a modeling method prior to step a) of producing the mold.
• a method of the invention comprising such a step makes it possible to obtain an optimally configured area of main interest and to ensure that the manufactured part has this area of main interest in accordance with its optimal configuration and without loss of integrity of the metallic glass.
• the present invention also relates to a part made of at least partially amorphous metal or metal alloy manufactured by the manufacturing method as defined above, said part comprising at least one area of main interest made of at least partially amorphous molded metal or metal alloy and at least one area of secondary interest for which the dimensions and/or the surface condition and/or the properties of the at least partially amorphous metal or metal alloy may have to be modified during the manufacturing method of said part.
• the present invention relates to a method for manufacturing a metallic glass part.
• metallic glass is used to generally designate an at least partially amorphous metal or metal alloy.
• Said metallic glass part comprises at least one area of primary interest made of at least partially amorphous, and preferably entirely amorphous, metal or metal alloy and at least one area of secondary interest.
• Said at least one area of primary interest is advantageously an area for which the dimensions and/or the surface condition and/or the properties of the at least partially amorphous, and preferably entirely amorphous, metal or metal alloy must not not be modified during the manufacturing process of said part, once the raw molding part has been obtained.
• a zone of main interest is therefore an area of the raw molding part, preferably entirely amorphous, which will not be modified once molded and extracted from the mold and for which the metallic glass will not be reworked, once the raw molding part has been molded and extracted from the mold, in order to maintain its integrity.
• the manufacturing method according to the invention does not include any step likely to harm the integrity of the metallic glass, preferably entirely amorphous, of a molded zone of main interest.
• the manufacturing method according to the invention does not include any step likely to modify the dimensions and/or the surface condition and/or the properties of the at least partially amorphous, and preferably entirely amorphous, metal or metal alloy of the at least one zone of main interest of the raw molding part.
• a zone of main interest may be formed, for example, depending on the function of the part, of all or part of the exterior or interior walls or surfaces of a part, such as the exterior side walls, the interior side walls, the upper face, the lower face, for which, for example, the surface condition or the dimensions must not be modified once the raw molding part has been molded.
• Such zones of main interest are, for example, surfaces in contact with other parts, elastic functioning zones, surfaces allowing precise positioning of the part, etc.
• An area of primary interest may also be an area intended to be mechanically stressed and subjected to stress during use of the part and for which the properties of the metallic glass, in particular the mechanical properties, must not be modified during the manufacturing process of said part, once the raw molded part has been obtained.
• a secondary area of interest is an area where the integrity of the metallic glass can be lost after the raw part is molded without affecting the performance of the manufactured part.
• a secondary area of interest is an area where the dimensions and/or surface finish and/or properties of the metal or metal alloy that is at least partially amorphous may be modified during the manufacturing process of said part.
• a secondary area of interest may be, depending on the function of the part, an area that links areas of primary interest, an area formed from all or part of the exterior or interior walls or surfaces of a part, such as the interior side walls, the outline of an orifice or an interior cutout, exterior side walls.
• the part manufactured according to the method of the invention may advantageously constitute a timepiece organ, such as a watch spring, a lever or a control member.
• a timepiece organ such as a watch spring, a lever or a control member.
• Such a spring may have, as areas of primary interest, the areas intended to be subjected to stress during its use, and as areas of secondary interest, the contours of an internal cutout.
• a lever or a control member may have, as areas of primary interest, its external contours, such as the external contours of a control element, such as a control beak, and at least part of the lower and upper faces, and as areas of secondary interest, the contours of internal cutouts or orifices provided in the part.
• the manufactured part for example a spring, may be formed at least partially from at least one blade of at least partially amorphous metal or metal alloy.
• the at least one area of primary interest is obtained directly by molding the raw molded part and the at least one area of secondary interest is obtained by at least one other process different from molding, said process making it possible to work the metallic glass of the sacrificial part.
• "Sacrificial" means that the metallic glass of the sacrificial part may lose its integrity, in particular its mechanical properties, its dimensions, its surface condition, without any consequence on the performance of the manufactured part.
• the metallic glass of the area of secondary interest may be altered without harming the quality of the part.
• the working of the at least partially amorphous metal or metal alloy of the sacrificial part according to step d) may consist of modifying the surface state of the at least partially amorphous metal or metal alloy of the sacrificial part or of eliminating all or part of the at least partially amorphous metal or metal alloy of said sacrificial part.
• a sacrificial part may be provided on the raw molding part in place of openings or orifices provided on the part to be manufactured.
• This sacrificial part makes it possible to obtain a raw molding part that is sufficiently rigid not to deform when it is removed from the mold.
• a sacrificial part may also be provided on the raw molding part to facilitate filling of the mold, in particular when the mold corresponding to the part to be manufactured includes long areas of small section. Such sacrificial parts are then completely eliminated during step d) to leave in place an internal cutout or a hole whose walls constitute a secondary area of interest.
• the at least one secondary area of interest is produced according to step d) by a laser process, water jet cutting and/or an electroerosion machining process. Since the sacrificial parts intended to form secondary areas of interest are to be repeated, the method implemented in step d) does not require very high precision or to be specifically adapted to the different areas to be treated. Different methods can be used to treat the different sacrificial parts depending on the needs.
• the dimensions of the at least one area of primary interest have a manufacturing tolerance equal to a minimum tolerance predetermined by the specifications.
• the impression made in the mold in step a) then comprises at least one first molding part configured to receive a molten metal or metal alloy to form said at least one area of main interest during molding, said at least one molding part corresponding to said at least one area of main interest plus or minus the predetermined minimum manufacturing tolerance.
• Said impression also comprises at least one second molding portion configured to receive a sacrificial molten metal or metal alloy to form said at least one sacrificial portion of the raw molding part intended to form said at least one secondary area of interest.
• the raw molded part comprises said at least one area of primary interest plus or minus the minimum manufacturing tolerance predetermined by the specifications and the at least one sacrificial part.
• the at least one molding part of the impression intended to form the at least one area of main interest is configured to have the same surface condition as that imposed by the specifications relating to said area of main interest.
• the area of main interest obtained by molding directly on the raw molded part does not present any defects and has dimensions and a surface condition corresponding to the dimensions and surface condition imposed by the specifications.
• the at least one area of primary interest can be identified by a modeling method prior to step a) of producing the mold.
• a modeling method uses, for example, finite element modeling software known per se. It advantageously makes it possible, before manufacturing the mold, to identify an area of primary interest on the part to be manufactured and to dimension it in an optimized manner with respect to the function of said area of primary interest.
• the molding part of the mold corresponding to at least one area of primary interest will then be produced with said optimized dimensions identified during modeling, plus or minus the predetermined minimum manufacturing tolerance. For the other parts of the mold corresponding to the areas of secondary interest, such precision is not necessary.
• the mold can therefore be manufactured more simply.
• a method is advantageously used which makes it possible to respect the minimum manufacturing tolerance predetermined by the specifications at least for the at least one first molding part of the cavity which is intended to form the at least one area of primary interest.
• the manufacturing method of the invention may comprise, after step d), a finishing step e), said finishing step not being capable of modifying the dimensions and/or the surface condition and/or the properties of the at least partially amorphous metal or metal alloy of the at least one zone of main interest of the raw molding part obtained in step c).
• the mold produced in step a) may comprise an intermediate element produced at least partially using a LIGA process and/or by laser cutting and defining at least partly the mold, in particular the at least one molding part corresponding to the at least one main area of interest.
• This intermediate element inserted into the mold makes it possible to obtain a raw molding part whose at least one main area of interest has high precision. dimensional.
• Such an intermediate element is described for example in the published patent application EP 4 282 557 of the applicant.
• the mold produced in step a) may comprise a base on which the negative impression is made and two movable flaps arranged to close the base and to form at least one orifice for introducing the molten metal or metal alloy.
• Said base and said flaps form a volume preferably corresponding substantially to that of the part to be manufactured. Thus, preferably no excess thickness is formed.
• the orifice for introducing the molten metal or metal alloy is positioned at the level of the at least one sacrificial part of the raw molding part.
• the metallic glass formed at the outlet of the introduction orifice after molding can then be cut without risk of harming the conformity of the manufactured part.
• the area corresponding to the section of the metallic glass forms a secondary area of interest.
• the bottom of the mold comprises at least one ejection zone arranged to allow the ejection of the raw molding part from the mold during step c).
• said ejection zone is positioned at the level of the at least one sacrificial part of the raw molding part.
• the metallic glass of a zone of main interest is not altered during the ejection of the raw molding part.
• the ejection zone will then preferably be eliminated with the sacrificial part so that it does not appear on the manufactured part.
• the metal alloy used in the present invention may advantageously be a NiNb38.0 alloy (atomic percentage) such as Medalium N1 distributed by Amorphous Metal Solutions GmbH, a Ni(57-67)Nb(28-38)Zr(0-10) alloy (atomic percentages) such as Vulkalloys ® distributed by Vulkam, in particular Ni1, a TiZr35.0Cu17.0S8.0 alloy (atomic percentages) such as Medalium T1 distributed by Amorphous Metal Solutions GmbH, a ZrCu17.9Ni14.6AI10.0Ti5.0 alloy (atomic percentages) such as Medalium Z2 distributed by Amorphous Metal Solutions GmbH or an alloy Zr59.3Cu28.8Al10.4Nb1.5 (atomic percentages) such as ZR01 distributed by Heraeus Group.
• NiNb38.0 alloy atomic percentage
• Medalium N1 distributed by Amorphous Metal Solutions GmbH
• a Ni(57-67)Nb(28-38)Zr(0-10) alloy atomic percentages
• a first embodiment of the method of the invention is described for the manufacture of a watch spring 1.
• a watch spring 1 is for example a spring of a clasp mechanism 2 of a watch strap shown in the figure 1 .
• a clasp is described in the patent EP 3 162 241 of the applicant.
• the spring 1 is formed of a blade which has a closed plane curve shape and comprises locking lugs 4 to 7 formed on the side of the spring 1.
• the locking lugs 4 to 7 are arranged to engage in locking recesses, here referenced 8 and 9, made in the pivoting blades 10, 11.
• the spring 1 constitutes a return spring for pushers 12, 13 which can be actuated by a user to retract the locking lugs 4 to 7, the spring 1 returning the pushers 12, 13 to their rest position as soon as the pressure exerted by the user's fingers disappears.
• the spring 1 therefore comprises areas of primary interest intended to be mechanically stressed and subjected to a constraint when the pushers 12, 13 are actuated.
• FIG. 1 represents the modeled spring 1 and allows the identification of the main areas of interest 14 to 19 as the main areas of interest subject to constraints and for which the mechanical properties of the metallic glass must not be altered once molded.
• Spring 1 also includes areas of primary interest 20 to 25 as areas of primary interest for which the dimensions and surface condition are not to be changed during the spring manufacturing process.
• a mold is produced comprising a negative impression configured to correspond to the raw molding part 26 shown in the figure 4 . More specifically the footprint is configured to obtain a raw molding part 26 which corresponds overall to a blank of the spring 1 and which includes the areas of main interest 14 to 25, which will be obtained directly by molding with a minimum tolerance predetermined by the specifications, as well as at least one sacrificial part 28, here constituted by material (therefore metallic glass) added to the interior of the spring 1.
• the sacrificial part 28 is intended to form a zone of secondary interest which will be constituted here by a part of the interior walls 30 of the spring 1, once said sacrificial part 28 has been eliminated.
• Such a sacrificial part 28 makes it easier to fill the mold and to stiffen the raw molding part 26 so that it does not deform when it is ejected from the mold.
• a molten metal alloy is injected into the mold and cooled rapidly to be solidified in an at least partially amorphous, preferably amorphous, form, according to step b).
• the raw molded part 26 is extracted from the mold according to step c). It is a part made of at least partially amorphous, preferably amorphous, metal alloy, which has the areas of main interest 14 to 25, made of preferably entirely amorphous metallic glass, molded with the predetermined minimum tolerance as well as the sacrificial part 28.
• ejection zones 32 to 35 are also visible on sacrificial part 28.
• step d) of the method of the invention the sacrificial part 28 is eliminated for example by water jet cutting or a wire electroerosion machining process to reveal a part of the interior walls 30 of the spring 1 which constitutes a secondary area of interest.
• a spring 1 made of metallic glass which comprises areas of primary interest 14 to 25 for which the metallic glass is not altered, and an area of secondary interest 30 at the level of a part of the inner contour of the spring 1, for which the metallic glass may have been altered during the manufacturing process of the spring 1.
• the metallic glass having possibly been altered only at the level of the area of secondary interest 30, the spring 1 manufactured by the method of the invention complies with the specifications and has all the required performance.
• This control member 40 comprises areas of main interest which are essentially constituted by the side walls of the outer contour of the control member 40 and in particular by the outer walls of a beak 41 provided on the control member.
• the dimensions and surface condition of these areas of main interest must correspond to the specifications and must not be modified during the manufacturing process of the control member 40.
• the positioning and dimensions of the beak 41 must be precise with respect to the reference hole 43 of axis XY.
• the control member 40 also comprises holes 42 to 48 for receiving other members whose walls define areas of secondary interest.
• the control member 40 also comprises internal cutouts 49, 50 which can be formed during the molding of the raw part, either directly in a precise manner to be able to preserve the integrity of the metallic glass, or in a less precise manner to be reworked after molding and constitute areas of secondary interest.
• a mold is produced comprising a negative impression configured to correspond to the raw molding part 52 shown in the figure 6 .
• the imprint is configured to obtain a raw molding part 52 which corresponds overall to a rough version of the control member 40, and which comprises the side walls of the outer contour of the control member 40, and in particular the outer walls of the spout 41, constituting areas of primary interest which will be obtained directly by molding with a minimum tolerance predetermined by the specifications as well as sacrificial parts 54 to 60, here constituted by material (therefore metallic glass) added in correspondence of the holes 42 to 48.
• These sacrificial parts 54 to 60 are intended to form areas of secondary interest which will be constituted here by walls of the holes 42 to 48, once the sacrificial parts 54 to 60 have been eliminated.
• the sacrificial parts 54 to 60 make it possible to facilitate the filling of the mold and to obtain a practically solid raw molding part 52 so that it does not deform when it is ejected from the mold.
• the impression is here configured to form the internal cutouts 49, 50 on the raw molding part 52. It is also possible to provide sacrificial parts in place of these cutouts if it is not necessary to preserve the integrity of the metallic glass of these cutouts.
• a molten metal alloy is injected into the mold and rapidly cooled to be solidified in an at least partially amorphous, preferably amorphous, form according to step b).
• the raw molding part 52 is extracted from the mold according to step c). It is a part made of at least partially amorphous, preferably amorphous, metal alloy, which already has the side walls of the outer contour of the control member 40, in particular the outer walls of the spout 41, molded with the predetermined minimum tolerance, constituting the areas of main interest in preferably entirely amorphous metallic glass, as well as the sacrificial parts 54 to 60, and here the inner cutouts 49, 50.
• step d) of the method of the invention the sacrificial parts 54 to 60 are eliminated for example by one or other of the methods of water jet cutting and wire EDM machining to precisely reveal the holes 42 to 48 whose internal walls constitute areas of secondary interest. Different methods can be used to eliminate the different sacrificial parts 54 to 60.
• the interior cutouts 49, 50 are here formed during the molding of the raw part 52. If the metallic glass of these interior cutouts 49, 50 must not be altered, the impression will be configured so that said interior cutouts 49, 50 constitute areas of main interest which will be obtained directly by molding with a minimum tolerance predetermined by the specifications. If the metallic glass of these interior cutouts 49, 50 can be altered, said interior cutouts 49, 50 can be molded without great precision, and the metallic glass can be worked according to step d) of the method to refine said interior cutouts 49, 50.
• a control member 40 is thus obtained made of metallic glass having an external contour, and in particular a spout 41, for which the metallic glass is not altered, and holes 42 to 48 for which the metallic glass of the internal walls may have been altered during the manufacturing process of said control member 40.
• the control member 40 manufactured by the method of the invention being made of metallic glass is generally more resistant.
• the metallic glass having possibly been altered only at the walls of the holes 42 to 48, the control member 40 complies with the specifications and has all the required performances.
• the manufacturing method according to the invention makes it possible to manage the manufacturing steps of the different parts of a metallic glass part differently depending on the interest in preserving the integrity of the metallic glass or not for one or other of the parts.
• the areas of primary interest of the metallic glass part preferably entirely amorphous, are obtained directly by molding and do not require any subsequent machining operation likely to harm the integrity of the metallic glass.
• They have a very high precision, in accordance with the specifications.
• the secondary areas of interest can then be reworked during subsequent manufacturing steps by standard processes whose parameters do not need to be adapted according to the different parts of the part to be treated.
• the possible loss of integrity of the metallic glass during these subsequent manufacturing steps is of no importance for the conformity of the part with respect to its specifications and its performance. Overall, the manufacturing method according to the invention is simpler to implement.
• the method according to the invention also makes it possible to manufacture a mold more simply, with only the parts of the mold corresponding to the areas of main interest of the part to be manufactured needing to be produced with the precision imposed by the specifications.
• the method according to the invention also makes it possible to obtain in a few steps metallic glass parts which cannot be easily obtained with materials and machining processes traditionally used in watchmaking.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)

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Citations (8)

• 2024
  • 2024-02-02 EP EP24155530.9A patent/EP4596138A1/de active Pending

Patent Citations (8)

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