EP2586546A1 - Procédé de fabrication de noyaux de sel - Google Patents

Procédé de fabrication de noyaux de sel Download PDF

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Publication number
EP2586546A1
EP2586546A1 EP11187281.8A EP11187281A EP2586546A1 EP 2586546 A1 EP2586546 A1 EP 2586546A1 EP 11187281 A EP11187281 A EP 11187281A EP 2586546 A1 EP2586546 A1 EP 2586546A1
Authority
EP
European Patent Office
Prior art keywords
composition
extruder
salt
nacl
casting
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP11187281.8A
Other languages
German (de)
English (en)
Inventor
Ulrich Jordi
Sascha Padovan
Hermann Jacob Roos
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Buehler AG
Original Assignee
Buehler AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Buehler AG filed Critical Buehler AG
Priority to EP11187281.8A priority Critical patent/EP2586546A1/fr
Priority to PCT/EP2012/068345 priority patent/WO2013064304A1/fr
Publication of EP2586546A1 publication Critical patent/EP2586546A1/fr
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/10—Cores; Manufacture or installation of cores
    • B22C9/105—Salt cores

Definitions

  • the present invention relates to a novel process for producing salt cores for die casting processes.
  • a melt of the material to be molded for example aluminum
  • a casting mold For the production of castings of more complex shape (eg hollow structures and / or non-demoldable undercuts) it is necessary to provide so-called lost cores in the mold.
  • lost cores are molded parts which are positioned in the mold at the corresponding point during the casting process and are removed from the casting without residue after the casting process. These cores are intended for single use only and are then "lost.”
  • salt cores have been increasingly used for this task. These are mixtures of various salts such as sodium carbonate (Na 2 CO 3 ) and sodium chloride (NaCl), as known from the prior art (eg EP-2 277 644 A1 ; Yaokawa et al., Journal of Japan Foundry Engineering Society, vol. 78 (10), 2006, 516-522 ; DE-100 4 785 T1 ) are known. Salt cores withstand the harsh conditions of die casting and - in contrast to, for example, sand cores - can be easily dissolved and removed after completion of the die casting process by treatment with, for example, hot water.
  • salt cores withstand the harsh conditions of die casting and - in contrast to, for example, sand cores - can be easily dissolved and removed after completion of the die casting process by treatment with, for example, hot water.
  • Such salt cores are prepared by mixing the appropriate salt components (in the case of several components) and melting them.
  • the melting is usually carried out in an open crucible in a melting furnace.
  • the melt optionally mixed with binders and others Additives, introduced into a corresponding shape of a die-casting machine, where the melt solidifies under pressure and can be removed as a finished molding.
  • Such a method is for example in the DE 100 84 785 described.
  • This manufacturing method has some disadvantages.
  • the production of the melt in an open crucible is not optimal from the point of view of the temperature balance. On the one hand, no desired temperature gradient can be driven in an open crucible. On the other hand, there are significant energy losses in the open system. During the transfer of the melt from the crucible into the mold, a part of the melt adheres to the scooping and dosing tools, and also during the molding process material losses occur.
  • salt cores can be advantageously prepared by the so-called thixomolding process.
  • the thixomolding process is mainly used for the production of magnesium alloy components.
  • a granulate of magnesium alloy is introduced via a metering device in a screw extruder.
  • the granules are heated by means of arranged on the extruder barrel heaters such as heating bands and transferred to a semi-solid state. Subsequently, it is conveyed in the extruder under constant shear into a collecting space, from where it is pressed by injection molding in a mold cavity.
  • the thixomolding process is well known to those skilled in the art. It is for example in the US 5,040,589 described. The content of this document is incorporated herein by reference for the thixomolding process.
  • a bulk material is understood to mean a solid, free-flowing and free-flowing form of a composition, for example a granulate or a powder.
  • a semi-solid state is understood to be the state which is reached at a transition temperature between the solid and liquid states of the material (ie between the liquidus point and the solidus point).
  • the material In the partly liquid state, the material has a microstructure in which finely divided, crystalline regions are embedded in melting regions.
  • the viscosity of the material In the partially liquid state, the viscosity of the material is reduced; ideally, a thixotropic state forms.
  • the part in the liquid state Material can be very precisely pressed into molds with little pressure.
  • the salt cores can be prepared by conventional thixomolding machines, such as those sold by the company Japan Steel Works. Examples include the machines with the type designation JLM75 JLM150 JLM220 JLM450 JLM650 JLM850 JLM1600.
  • a thixomolding machine which can be used according to the invention is disclosed in Fig. 1 shown.
  • the composition for producing the salt core is introduced into a metering device 1 (for example a funnel-like container with a closable lower outlet opening) as bulk material and subsequently introduced into a screw extruder 2 via a conveyor unit 1a.
  • the extruder 2 comprises a cylinder 3 and a screw conveyor 4 arranged in the cylinder.
  • On the cylinder outer side are one or more heating devices, here heating strips, 5 for heating the composition during its residence time in the extruder. It would also be possible alternatively to heat the cylinder 3 from the inside.
  • the composition is heated to a transition temperature between its solidus temperature and its liquidus temperature and changes to the semi-solid state described above.
  • the composition can be conveyed by the screw 4 through the extruder into a collecting chamber 6 which is located at the end of the extruder which is connected to the injection mold.
  • the screw 4 exerts a constant shearing action on the composition.
  • the collection chamber 6 is on the extruder side by a return flow lock 7, such as a valve, completed.
  • the end of the collection chamber 7 is connected via a nozzle 8 with the interior 10 of a two-part mold 9.
  • an injection molding apparatus 11 which comprises a pressure accumulator 12 and a hydraulic cylinder 13.
  • the hydraulic cylinder 13 can be supplemented by an electric drive.
  • the hydraulic cylinder 13 is connected to the screw conveyor 4 and can move the screw conveyor 4 within the cylinder 3 very quickly forward in the direction of collecting chamber 6 when triggering a shot.
  • the semi-solid material located in the collection chamber 6 is pressed through the nozzle 8 into the interior 10 of the mold 9, where it then solidifies to the salt core of the desired shape.
  • the salt core 9 can be removed and used.
  • the composition for producing the salt cores may in particular be inorganic salts such as fluorides, chlorides, sulfates, nitrates or carbonates of metals, in particular of alkali or alkaline earth metals such as lithium, sodium, potassium, Magnesium, calcium, strontium or barium. It is essential that the composition has the properties required for salt cores such as high water solubility, high strength of the core produced, chemical inertness under die casting conditions, low solidification heat, low volume change during melting and solidification and low or ideally absent toxicity.
  • the composition preferably contains 30 to 80% Nacl and 20 to 70% Na 2 C0 3 , more preferably 30 to 70% NaCl and 30 to 70% Na 2 CO 3 and especially preferably 30 to 60% NaCl and 40 to 70% Na 2 C0 3 .
  • a mixture of 50% Nacl and 50% Na 2 C0 3 may be mentioned by way of example.
  • composition which can be used according to the invention preferably has a melting point of between 550.degree. C. and 1000.degree.
  • the composition for producing the salt core is obtained by mixing the various components to form a homogeneous bulk material. This can be done with conventional mixers, which may advantageously already be integrated into the metering device of the thixomolding machine. If desired, additives may be added to the one or more salt components, for example fine heat-resistant and chemically inert hard particles such as powders, fibers or whiskers of Si, Al 2 O 3 or SiC, lubricants and release agents such as talc and optionally binders.
  • additives may be added to the one or more salt components, for example fine heat-resistant and chemically inert hard particles such as powders, fibers or whiskers of Si, Al 2 O 3 or SiC, lubricants and release agents such as talc and optionally binders.
  • the bulk material thus produced is filled into the metering device of a thixomolding machine and metered into the extruder of this machine.
  • an exchange of the composition used is possible in a simple manner by replacing or modifying the bulk material.
  • a melt of the salt mixture must be prepared in an open pot only outside of the actual molding device in the manner described in the introduction, which is a significantly higher cost.
  • the inventive method is also advantageous in terms of energy balance over the conventional method for the production of salt cores, since the heating and the promotion of the melt takes place in a single closed apparatus. Energy losses are thus minimized.
  • the temperature setting in the extruder of the inventive method can be carried out far more accurately than in the open crucible of the conventional manufacturing process.
  • Particularly advantageous is the possibility of gradually heating the material while it is being conveyed through the extruder.
  • the composition is heated to temperatures of 550 to 900 ° C., preferably 650 to 750 ° C. and more preferably 710 to 750 ° C., the temperature to be set being of course dependent on the type of composition used , It is essential that the composition is heated at least to the above-described transition temperature between liquidus and solidus temperature of the composition and thus assumes a semi-solid state. For some compositions, however, it is desirable to completely melt them to ensure good salt core processability.
  • the liquidus and solidus temperature of a substance can be determined experimentally or by calculation, as described for example in US Pat EP-2 277 644 A1 , Section [0019]. On the appropriate content of EP-2 277 644 A1 is referred to here. For many compositions, the liquidus and solidus temperatures are known.
  • the thus obtained at least semi-solid salt mixture is conveyed in the extruder by means of a screw conveyor into a collection chamber at the mold-side end of the extruder.
  • a constant shearing affects the composition.
  • the resulting constant kneading of the composition produces a particularly homogeneous mixture.
  • eutectic mixtures have a lower melting temperature than other mixtures or having individual components, less energy is required to heat the composition.
  • the energy balance of the method according to the invention is additionally advantageous.
  • an efficient degassing and drying (expulsion of water of crystallization) of the material takes place in the extruder, which reduces the possible gas inclusions in the finished salt core.
  • the material is injection molded into the mold as described above.
  • the injection molding process is well known to those skilled in the art.
  • the explosive force / explosive surface to be applied depends on the size of the salt core to be produced, as is known to the person skilled in the art.
  • the process of the present invention has less cycle material, i. there is less material waste.
  • a more uniform mold filling and a central pressurization of the salt core are obtained towards the gate, since casting is carried out in the middle (and not outside).
  • the salt cores produced according to the invention are outstandingly suitable for die casting applications.
  • a melt of, for example, aluminum, magnesium or zinc alloys is filled into a casting chamber of a die casting machine and pressed from there with a piston under high pressure (about 150 to 1200 bar) into the interior of a die casting mold.
  • the die casting mold is two or three parts and comprises a fixed and a movable mold half (and optionally a middle plate). The two mold halves together define an interior with the shape of the casting to be produced. Casting machines are known in the art and need not be explained in detail here. By way of example, the CARAT series die casting machines of the applicant can be used according to the invention.
  • the salt cores produced according to the invention are positioned in the interior of the die-casting mold before the die-casting process in order to be able to demould non-realizable cavities, undercuts or free-form surfaces.
  • the salt core can be easily removed from the casting by the casting is immersed in a release bath of, for example, acidic media and / or hot water. In these media, the salt core dissolves completely.
  • the dissolution process can also be performed or supplemented by spraying the casting with hot water or steam.
  • a hydrochloric acid-containing medium the dissolution process is supported by the formation of carbonic acid.
  • the salt cores produced according to the invention can also be used in plastic injection molding or in collision casting. These methods are well known to those skilled in the art.
  • the present invention as a whole provides an improved process for the preparation of salt cores which has numerous advantages as compared to the conventional production of salt cores.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
EP11187281.8A 2011-10-31 2011-10-31 Procédé de fabrication de noyaux de sel Withdrawn EP2586546A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP11187281.8A EP2586546A1 (fr) 2011-10-31 2011-10-31 Procédé de fabrication de noyaux de sel
PCT/EP2012/068345 WO2013064304A1 (fr) 2011-10-31 2012-09-18 Procédé de production de noyaux de sel

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP11187281.8A EP2586546A1 (fr) 2011-10-31 2011-10-31 Procédé de fabrication de noyaux de sel

Publications (1)

Publication Number Publication Date
EP2586546A1 true EP2586546A1 (fr) 2013-05-01

Family

ID=46888443

Family Applications (1)

Application Number Title Priority Date Filing Date
EP11187281.8A Withdrawn EP2586546A1 (fr) 2011-10-31 2011-10-31 Procédé de fabrication de noyaux de sel

Country Status (2)

Country Link
EP (1) EP2586546A1 (fr)
WO (1) WO2013064304A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102012022390B3 (de) * 2012-11-15 2014-04-03 Audi Ag Verfahren zur kalten Herstellung eines Salzkerns für das Druckgießen
DE102013007735B4 (de) * 2012-05-08 2015-10-15 Audi Ag Verfahren zum Herstellen eines gussgeeigneten Salzkerns
CN109047671A (zh) * 2018-09-05 2018-12-21 湖南江滨机器（集团）有限责任公司 一种盐芯及其制备方法和盐芯材料

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102014221359A1 (de) * 2014-10-21 2016-04-21 Volkswagen Aktiengesellschaft Verfahren zur Herstellung eines metallischen Druckgussbauteils unter Verwendung eines Salzkerns mit integrierter Stützstruktur und hiermit hergestelltes Druckgussbauteil
US11433627B2 (en) 2018-09-21 2022-09-06 Kohler Co. Method of forming fluid channels on a bathtub

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0056662A2 (fr) * 1978-12-04 1982-07-28 Sherwood Refractories Inc. Compositions extrudables pour la fabrication de noyaux réfractaires pour la coulée des alliages de fer en moules de sable
US5040589A (en) 1989-02-10 1991-08-20 The Dow Chemical Company Method and apparatus for the injection molding of metal alloys
WO2001002112A1 (fr) * 1999-07-06 2001-01-11 Technology Union Co., Ltd. Noyau se desintegrant, destine au moulage sous haute pression, procedes de fabrication et d'extraction associes
DE102006031531A1 (de) * 2006-07-07 2008-01-10 Emil Müller GmbH Salzkerne für Kunststoff(spritz)guß
EP2022578A1 (fr) * 2006-05-19 2009-02-11 National University Corporation Tohoku Unversity Noyau de sel pour coulage
EP2022577A1 (fr) * 2006-05-18 2009-02-11 National University Corporation Tohoku Unversity Noyau de sel pour coulage et son procédé de production
EP2277644A1 (fr) 2008-05-09 2011-01-26 Yamaha Hatsudoki Kabushiki Kaisha Procédé de production d'un noyau de sel pour coulée

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1004785B (de) 1953-06-26 1957-03-21 Muckenfuss Soehne Malag Schwenkbare Tuer fuer Herde, OEfen, Kuehlschraenke, Spueltische u. dgl.

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0056662A2 (fr) * 1978-12-04 1982-07-28 Sherwood Refractories Inc. Compositions extrudables pour la fabrication de noyaux réfractaires pour la coulée des alliages de fer en moules de sable
US5040589A (en) 1989-02-10 1991-08-20 The Dow Chemical Company Method and apparatus for the injection molding of metal alloys
WO2001002112A1 (fr) * 1999-07-06 2001-01-11 Technology Union Co., Ltd. Noyau se desintegrant, destine au moulage sous haute pression, procedes de fabrication et d'extraction associes
DE10084785T1 (de) 1999-07-06 2002-08-29 Technology Union Co Zerfallender Kern für ein Hochdruckgussteil, Verfahren zu dessen Herstellung und Verfahren, um diesen herauszulösen
EP2022577A1 (fr) * 2006-05-18 2009-02-11 National University Corporation Tohoku Unversity Noyau de sel pour coulage et son procédé de production
EP2022578A1 (fr) * 2006-05-19 2009-02-11 National University Corporation Tohoku Unversity Noyau de sel pour coulage
DE102006031531A1 (de) * 2006-07-07 2008-01-10 Emil Müller GmbH Salzkerne für Kunststoff(spritz)guß
EP2277644A1 (fr) 2008-05-09 2011-01-26 Yamaha Hatsudoki Kabushiki Kaisha Procédé de production d'un noyau de sel pour coulée

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
YAOKAWA ET AL., JOURNAL OF JAPAN FOUNDRY ENGINEERING SOCIETY, vol. 78, no. 10, 2006, pages 516 - 522

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102013007735B4 (de) * 2012-05-08 2015-10-15 Audi Ag Verfahren zum Herstellen eines gussgeeigneten Salzkerns
DE102012022390B3 (de) * 2012-11-15 2014-04-03 Audi Ag Verfahren zur kalten Herstellung eines Salzkerns für das Druckgießen
CN109047671A (zh) * 2018-09-05 2018-12-21 湖南江滨机器（集团）有限责任公司 一种盐芯及其制备方法和盐芯材料

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Publication number Publication date
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