Classifications

• • 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
  • B22D17/00—Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
  • B22D17/20—Accessories: Details
  • B22D17/22—Dies; Die plates; Die supports; Cooling equipment for dies; Accessories for loosening and ejecting castings from dies
  • B22D17/2236—Equipment for loosening or ejecting castings from dies
• • 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
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D29/00—Removing castings from moulds, not restricted to casting processes covered by a single main group; Removing cores; Handling ingots
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D30/00—Cooling castings, not restricted to casting processes covered by a single main group

Definitions

• the present invention relates to the field of conformation of parts in an amorphous or vitreous material, that is to say having a glass transition temperature, in particular metal glass parts.
• a part is shaped in a mold, whether it is a part obtained in an injection mold or in a hot forming mold, the mold is cooled, the mold is opened to cool the part and and with the aid of an ejector, ejects the part of the mold part in which this part remains when the mold is opened.
• the cooling of the mold, and therefore of the part must be determined in such a way that the part, and possibly the mold, are not damaged during the ejection.
• DE 198 30 025 discloses a mold part of which is provided with cooling channels.
• Patents EP 0 941 788, US Pat. No. 2,974,379 and WO 96/22852 disclose molding machines equipped with devices for cleaning joint planes and cavities of molds.
• DE 2006/0657660 discloses a molding machine in which such a cleaning device can be used to cool the molded part.
• prior art above Particularly when the pieces are made of a metal glass and of small sizes, in particular less than one cubic centimeter (cm 3 ), one difficulty is the need to obtain rapid cooling to avoid the risk of crystallization of the material.
• Another difficulty relates to the risk of deformation of the workpiece resulting from the wedging effects of the workpiece in the mold and the forces applied by the ejector, due in particular to the difference between the coefficient of expansion of the mold and that of the workpiece and the fact that the material constituting the part does not exhibit a sudden change in volume during its cooling. Mastering the time cycles of conformation and demolding also poses a difficulty.
• the present invention aims to propose a solution including difficulties above.
• a method of demolding a workpiece of a material having a glass transition temperature and a melting temperature greater than its glass transition temperature, formed in a cavity of a mold comprising at least two mold parts delimiting between they this conformation cavity, wherein the mold is at a temperature between said glass transition temperature and said melting temperature.
• the proposed method comprises opening the mold by spacing said mold parts, the part in the mold cavity being at a temperature between said glass transition temperature and said melting temperature; a local projection of a cooling gas towards the part remaining in a mold part, and, after a determined delay following the start of the throwing of the gas, the ejection of the part of this part of the mold , this determined time being such that the part reaches a temperature below its glass transition temperature.
• the method may include stopping the throwing of the gas before ejecting the workpiece.
• the method may include ejecting the workpiece during gas spraying.
• the method may include maintaining the mold at a temperature between the glass transition temperature and the melting temperature of the workpiece material.
• a method of shaping a workpiece of a material having a glass transition temperature and a melting temperature above its glass transition temperature which comprises the aforementioned demolding process and, previously, the setting of a a quantity of material at a temperature between its glass transition temperature and its melting temperature and the injection of that amount of material in that state into said shaping cavity when the mold parts are coupled to conform the material to the shape of the conformation cavity.
• a method of shaping a workpiece of a material having a glass transition temperature and a melting temperature above its glass transition temperature which comprises the aforementioned demolding process and, previously, the setting up of an amount of material in a recessed portion of one of the mold parts, and coupling the mold parts to stamp the material to the shape of the conformation cavity.
• a molding machine which comprises a mold comprising at least a first and a second mold parts delimiting between them, when they are coupled, a conformation cavity of a part made of a material having a glass transition temperature and a melting temperature above its glass transition temperature; means for maintaining the mold at a temperature between said glass transition temperature and said melting temperature; at least one ejection means for withdrawing the workpiece from one of said mold parts; and at least one gas projection nozzle having at least one exit orifice, said projection nozzle being mounted on displacement means adapted to move the nozzle between a withdrawal position in which the mold parts can be mated or spaced apart and an advanced position in which, when the mold parts are spaced apart, the outlet orifice of the nozzle is placed towards and in the vicinity of the part remaining in a mold part; and control means for controlling the opening of the mold, then feeding the nozzle into said advanced position and injecting the cooling gas, and then ejecting the workpiece after a specified time following the start of the projection of the gas, this determined time being
• FIG. 1 shows a partial section of the molding machine, the mold of this machine being closed
• FIG. 2 shows a partial section of the molding machine, the mold of this machine being open
• FIG. 3 shows an injection machine including the molding machine.
• a material having a glass transition temperature Ty_ and a melting temperature Tj greater than its glass transition temperature Ty_ for example a glass such as a glass of oxide, a metal glass or a polymer. Below its glass transition temperature, the material is solid. Between its glass transition temperature and its melting temperature TF, the material is malleable. Above its melting point TF, the material is liquid.
• a molding machine 1 comprises a mold 2 formed for example of two mold parts 3 and 4 which delimit between them a conformation cavity 5.
• This cavity 5 may be delimited by recesses 3 and 4a arranged in the mold parts 3 and 4.
• the mold parts 3 and 4 are equipped with heating means 6 and 7 formed for example by electric resistors.
• the mold part 4 is equipped with a sliding ejector 8 that can be actuated by a jack 8a.
• the molding machine 1 further comprises a cooling gas spraying nozzle 9, which is carried by a displacement mechanism 10, for example translational or rotational.
• the nozzle 9 can be moved between a withdrawal position in which the mold parts 3 and 4 can be coupled (FIG. 1) or spaced apart (FIG. 2) one of the another and an advanced position in which, the mold parts 3 and 4 being spaced ( Figure 2), the free end portion of the nozzle 9 can be introduced between the mold parts 3 and 4 to a position such that its end orifice 9a is at a small distance from and oriented towards, for example, the recessed portion 4a of the mold part 4.
• the nozzle 9 is connected to a source 1 1 of a cooling gas.
• the molding machine 1 can operate and be used in the following manner.
• the mold parts 3 and 4 are coupled and a piece P 2 is shaped in the cavity 5.
• the mold parts 3 and 4 are at a shaping temperature between the glass transition temperature T 1 and the melting temperature Tj of the material constituting the piece P.
• the piece P_ may result from an injection of a quantity of material into the cavity 5 of the closed mold 2, this quantity of material being previously brought to a temperature between the glass transition temperature Ty_ and the melting temperature T F of this material.
• the piece P can result from a stamping in the cavity 5 of a quantity of material by moving the mold parts 3 and 4 towards each other.
• the nozzle 9 is in its retracted position. For the demolding of the piece P, one can proceed as follows.
• the mold 2 is opened by spreading the mold parts 3 and 4. Because of its shape and the corresponding shape of the cavity 5, the piece P remains in the hollow part 4a of the mold part 4 , while being able to be ejected.
• the nozzle 9 is fed with a pressurized cooling gas from the source 11 so that this gas, which is neutral with respect to the material constituting the part P, is projected towards the part P_, on its uncovered part, and possibly partly against the surrounding area of the mold part 4, so as to produce a local cooling which cools the piece P to a temperature below its glass transition temperature T v for it to stiffens.
• the gas supply of the nozzle 9 could begin before it reaches its advanced position.
• the ejector 8 is actuated under the effect of the jack 8a so as to extract the piece P from the hollow part 4a of the mold part 4.
• the demolding operations described above can be performed without cutting the heating means 6 and 7, so that after any cleaning and removal of the nozzle 9, the mold 2 is immediately ready for the conformation of a new room P.
• the implementation of the above demolding steps can be controlled in temperature and time. This control may depend on the shape and size of the part P, the temperature of the mold 2 and the desired cooling rate of the part P.
• the temperature of the mold 2 is between the glass transition temperature Ty_ and the melting temperature Tj of the material constituting the part P so that the workpiece P is sufficiently malleable while retaining the amorphous nature of the material constituting it. that is to say without causing a crystallization of the material.
• the temperature of the mold 2 can be controlled by a control loop including a temperature sensor 12 (FIG. 1) judiciously placed on the mold 2.
• the temperature of the piece P reached at the time of ejection is lower than the glass transition temperature Ty_ of the material constituting the part P so that it has become rigid.
• Ty_ glass transition temperature
• the temperature of the mold 2 can be between 140 ° C and 430 ° C.
• the temperature of the mold 2 may be between 400 ° C and 600 ° C.
• the temperature of the cooling gas for example nitrogen, may be between -195 ° C and 20 ° C.
• the time interval between the start of the cooling gas projection and the moment of actuation of the ejector 8 can be between 0.1 seconds and 10 seconds.
• an injection machine 100 comprises the molding machine 1 in a position such that the joint plane of the mold parts 3 and 4 is arranged vertically.
• the injection machine 100 further comprises an injection apparatus 101, associated with the mold part 3 and for injecting a quantity of material B_ into the conformation cavity 5, when the mold 2 is closed, for example by means of at the piston plunger 102.
• a supply apparatus 103 is associated with the injection apparatus 101 for the purpose of successively placing a quantity of material in the channel of the pusher 102.
• the injection machine 100 also comprises a mechanism 104 for moving the mold part 4 horizontally with respect to the mold part 3.
• the injection machine 100 also includes a recovery tank 105 placed below the parting plane of the mold parts 3 and 4, in order to recover the pieces P after their ejection and demoulding as previously described.
• a stamping machine could comprise the molding machine 1 in a position such that the joint plane of the mold parts 3 and 4 is arranged horizontally, the mold part 3 being placed above the mold part. mold part 4.
• the coining machine could include a mechanism for vertically moving the mold portions 3 and 4 relative to each other.
• This stamping machine could work as follows.
• a mechanism could place a volume or grain of material B in the recessed portion 4a of the mold portion 4.
• the vertical displacement mechanism could bring the mold parts 3 and 4 closer together until the mold 2 is completely closed, so as to conform the volume or grain of material B to the shape of the conformation cavity 5.
• the vertical displacement mechanism could move the mold parts 3 and 4 to open the mold 2.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Injection Moulding Of Plastics Or The Like (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=46201662

Family Applications (1)

Country Status (5)

Families Citing this family (1)

Family Cites Families (12)

• 2011
  • 2011-06-09 FR FR1155076A patent/FR2976208B1/fr not_active Expired - Fee Related
• 2012
  • 2012-06-01 WO PCT/EP2012/060358 patent/WO2012168147A1/fr active Application Filing
  • 2012-06-01 EP EP12725028.0A patent/EP2718045B1/de active Active
  • 2012-06-01 US US14/124,854 patent/US9505055B2/en active Active
  • 2012-06-01 JP JP2014514002A patent/JP2014515992A/ja not_active Ceased

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