WO2004098811A1 - Moulding material, moulding part and method for the production of a casting mould - Google Patents

Moulding material, moulding part and method for the production of a casting mould Download PDF

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Publication number
WO2004098811A1
WO2004098811A1 PCT/EP2004/004936 EP2004004936W WO2004098811A1 WO 2004098811 A1 WO2004098811 A1 WO 2004098811A1 EP 2004004936 W EP2004004936 W EP 2004004936W WO 2004098811 A1 WO2004098811 A1 WO 2004098811A1
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Prior art keywords
molding
casting
molding material
solidification
produced
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PCT/EP2004/004936
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German (de)
French (fr)
Inventor
Thomas Steinhäuser
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Hydro Aluminium Deutschland Gmbh
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Application filed by Hydro Aluminium Deutschland Gmbh filed Critical Hydro Aluminium Deutschland Gmbh
Priority to DE502004000846T priority Critical patent/DE502004000846D1/en
Priority to EP04731830A priority patent/EP1620216B1/en
Priority to AU2004235962A priority patent/AU2004235962A1/en
Priority to MXPA05011996A priority patent/MXPA05011996A/en
Priority to PL04731830T priority patent/PL1620216T3/en
Publication of WO2004098811A1 publication Critical patent/WO2004098811A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
    • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
    • B22C1/18—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents
    • B22C1/186—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents contaming ammonium or metal silicates, silica sols
    • B22C1/188—Alkali metal silicates

Definitions

  • the invention relates to a molding material for the production of moldings for casting molds for casting molten metals, in particular light metal melts, such as Aluminiumgussschmelzen. Moreover, the invention relates to moldings produced from such a molding material. Finally, the invention provides a method with which molded parts can be produced from molded materials according to the invention.
  • quartz sand is usually used as a raw material of molded materials from which moldings, such as casting cores, are produced for casting molds. This sand is placed in advance in a mixer and mixed with a binder. The molding material obtained by this mixture is then injected into the mold cavity defining the shape of the molding to be produced. Subsequently, the solidification of the molding takes place in the mold. If an organic binder, for example synthetic resin-based binder, is used, a chemical reaction in the molding material injected into the molding tool is brought about.
  • an organic binder for example synthetic resin-based binder
  • an inorganic for example, water-glass-based binder
  • heat is usually added to the molding material contained in the mold in order to bring about the solidification of the molded part to be produced by evaporation of the water contained in the molding material.
  • quartz sand as a raw material for the production of moldings has proven itself in many ways, especially in the field of casting of light metal materials.
  • quartz sand can be obtained inexpensively and is characterized by a simple processability and a good quality in the image of the mold elements of each mold part to be produced.
  • the object of the invention was to provide a molding material, which allows the cost-effective production of mold parts, in particular casting cores.
  • low cost manufacturable molded parts and a method should be specified, which makes it possible to produce such moldings.
  • this object is achieved in that such a Foritistoff from a base material produced based on quartz-free sand and mixed with the mold base, based on water glass produced inorganic binder is produced.
  • quartz-free sand Particularly suitable as quartz-free sand is olivine sand, which is a widely used mineral that is available inexpensively in large quantities.
  • molding materials which are produced according to the invention on the basis of a wholly or at least predominantly quartz-free sand base material also detach themselves perfectly from the finished casting when they are bonded with a waterglass binder.
  • the remaining sand retention on the casting is reduced to a minimum. In this way, even when using Moldings made of novel moldings containing a water glass binder can be guaranteed to give sanding adherence-free castings.
  • the molding material produced on the basis of quartz-free sand, in particular olivine, according to the invention creates the prerequisite for cost-effective production of castings.
  • the outlay for sand removal is reduced compared with that which is obtained in the cleaning of cast parts which have been cast using molded parts produced from conventional, quartz-containing molding materials.
  • the molding material used according to the invention can consist entirely of quartz-free sand.
  • quartz-free sand, in particular olivine mixed with the main constituent supports mullite content which supports the automatic disintegration of the moldings produced on the basis of the molding base material in the course of the solidification of the casting component. This proves to be particularly advantageous if it s in the molding 'concerns cores that map cavities in the finished Cast.
  • a particularly satisfying the requirements of the practice molding composition is characterized in that it contains 1.5 to 3.0 wt .-% of water glass.
  • To improve the sand life of the molding material of the invention may contain 0.3 to 0.5 wt .-% sodium hydroxide solution.
  • a molded part according to the invention for casting molds which is in particular a casting core, is produced from a molding material according to the invention.
  • the advantageous effects achieved by using a molding material system based on the mixture of quartz-free sands and an inorganic water glass binder in the casting of light metal melts are independent of the process by which the respective molded parts, in particular casting cores, have been produced.
  • the molding is then removed from the molding box and cured fully under the influence of microwave heating.
  • moldings which are produced by mixing quartz-free sands according to the invention, in particular olivine sand precursors, with an inorganic binder can reliably produce molded parts which not only have a particularly high strength and image fidelity, but moreover have the property of to disintegrate without adhesion during the production of the castings. Decay promoting additives in the binder system are no longer required. Therefore, in the application of the invention, environmental stresses and hazards to the operator are avoided by escaping gases whose formation and unwanted spread can be minimized in conventional manufacturing only with great technical effort.
  • the temperature of the mold box in the first phase of solidification should be 150 ° C to '200 ° C.
  • the complete curing of the molding then adjusts safely when the exposure time of the microwave heating in the second phase of solidification is 2 - 5 minutes.
  • the respective exposure time can be adjusted taking into account the complexity of the shaping so that at the end of the microwave treatment sufficient for the casting process final strength and dryness of the molding is guaranteed.
  • a molding material has subsequently been produced by mixing the molding material with a waterglass binder.
  • a proportion of sodium hydroxide solution has been added to the molding base to improve its durability.
  • the mold base material thus composed contained 2.5% by weight of waterglass binder, 0.3% by weight of sodium hydroxide solution and the remainder the molding base material of the above-described composition.
  • This molding material has been placed in the cavity of a preheated molding box which images the finished casting core. Due to the excellent flowability of the molding material while difficult-shaped, small-part mold elements of the cavity have been filled safely. This secure mold filling has also been supported by the fact that the mold box has already been subjected to negative pressure during the filling process. The negative pressure was 0.3 bar.
  • the temperature of the mold box was 180 ° C when filling the molding material. At this temperature, after completion of the filling operation in the molding box, the molding material has been held for 30 seconds with still effective negative pressure. At this time formed in the area of the inner walls of the Mold box adjacent areas of the molding material, a solid outer shell. In this way, at the end of the completed in the mold box first stage of solidification, a molding was available, the strength was sufficient to be able to safely transport it in a microwave oven can.
  • the molded article In the microwave oven, the molded article has been microwave heated for 3 minutes until it has reached a final strength sufficient for the casting insert.
  • the casting core thus produced has then been placed in a casting mold, in which subsequently the melt produced from the aluminum casting alloy has been cast to the cylinder head to be produced.
  • the casting core is automatically disintegrated into many small fragments due to the temperature influence of the casting heat and its due to the solidification of the casting mechanical stress, which could be easily removed after complete solidification of the casting.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Mold Materials And Core Materials (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
  • Moulds For Moulding Plastics Or The Like (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

The invention relatest to a moulding material for moulding parts of casting moulds used to cast metal melts, especially light metal melts such as aluminium casting melts. Said moulding material makes it possible to produce non-sand-adherent cast moulding parts which are, especially casting cores, in an economical manner by virtue of the fact that it is produced using a basic mould material which is based on quartz-free sand, especially olivin sand, and an inorganic binder based on waterglass mixed with the basic mould material. The invention also relates to moulding parts which can be produced in an economical manner and a method enabling said moulding parts to be produced.

Description

Formstoff, Formteil und Verfahren zur Herstellung von Formteilen für eine Gießform Molded material, molded part and method for the production of moldings for a casting mold
Die Erfindung betrifft einen Formstoff für die Herstellung von Formteilen für Gießformen zum Vergießen von Metallschmelzen, insbesondere Leichtmetallschmelzen, wie AIuminiumgussschmelzen. Darüber hinaus betrifft die Erfindung aus einem derartigen Formgrundstoff erzeugte Formteile. Schließlich stellt die Erfindung ein Verfahren zur Verfügung, mit dem sich aus erfindungsgemäßen Formstoffen Formteile herstellen lassen.The invention relates to a molding material for the production of moldings for casting molds for casting molten metals, in particular light metal melts, such as Aluminiumgussschmelzen. Moreover, the invention relates to moldings produced from such a molding material. Finally, the invention provides a method with which molded parts can be produced from molded materials according to the invention.
Als Grundstoff von Formstoffen, aus denen Formteile, wie Gießkerne, für Gießformen hergestellt werden, wird üblicherweise Quarzsand verwendet. Dieser Sand wird im Vorfeld in einen Mischer gegeben und darin mit einem Binder vermischt. Der durch diese Mischung erhaltene Formstoff wird dann in den die Form des zu erzeugenden Formteils bestimmenden Hohlraum eines Formwerkzeugs eingeschossen. Anschließend erfolgt die Verfestigung des Formteils in dem Formwerkzeug. Wird ein organischer, beispielsweise kunstharzbasierter Binder eingesetzt, wird dazu eine chemische Reaktion in dem in das Formwerkzeug eingeschossenen Formstoff hervorgerufen. Wird dagegen ein anorganischer, beispielsweise wasserglasbasierter Binder verwendet, so wird im Regelfall dem im Formwerkzeug enthaltenen Formstoff Wärme zugeführt, um durch Verdampfung des im Formstoff enthaltenen Wassers die Verfestigung des zu erzeugenden Formteils herbeizuführen. Es ist jedoch auch möglich, den Wasserglas enthaltenden Formstoff durch eine Begasung mit C02-Gas chemisch zu härten.As a raw material of molded materials from which moldings, such as casting cores, are produced for casting molds, quartz sand is usually used. This sand is placed in advance in a mixer and mixed with a binder. The molding material obtained by this mixture is then injected into the mold cavity defining the shape of the molding to be produced. Subsequently, the solidification of the molding takes place in the mold. If an organic binder, for example synthetic resin-based binder, is used, a chemical reaction in the molding material injected into the molding tool is brought about. If, on the other hand, an inorganic, for example, water-glass-based binder is used, heat is usually added to the molding material contained in the mold in order to bring about the solidification of the molded part to be produced by evaporation of the water contained in the molding material. However, it is also possible to contain the water glass To chemically harden molding material by gassing with C0 2 gas.
Die Verwendung von Quarzsand als Grundstoff für die Herstellung von Gießformteilen hat sich insbesondere im Bereich des Vergießens von Leichtmetallwerkstoffen in mehrfacher Hinsicht bewährt. So lässt sich derartiger Quarzsand kostengünstig beschaffen und zeichnet sich durch eine einfache Verarbeitbarkeit und eine gute Qualität bei der Abbildung der Formelemente des jeweils zu erzeugenden Gießformteils aus.The use of quartz sand as a raw material for the production of moldings has proven itself in many ways, especially in the field of casting of light metal materials. Thus, such quartz sand can be obtained inexpensively and is characterized by a simple processability and a good quality in the image of the mold elements of each mold part to be produced.
Bei Verwendung eines Formstoffs mit Quarzsand als Grundstoff, der einen auf Wasserglas basierenden Binder enthält, steht diesen Vorteilen allerdings der Nachteil gegenüber, dass an den von den Formteilen abgebildeten Gussteiloberflächen Sandanhaftungen verbleiben. Diese Anhaftungen können nur entfernt werden, indem die Gussteile in einem separaten Bearbeitungsprozess beispielsweise mit einem Strahlgut gestrahlt oder mit Druckwasser gereinigt werden.When using a molding material with quartz sand as the base material, which contains a water-glass-based binder, these advantages, however, is offset by the disadvantage that sand deposits remain on the casting surfaces depicted by the molded parts. These adhesions can only be removed by blasting the castings with blasting material or by cleaning them with pressurized water, for example, in a separate machining process.
Der Bearbeitungsaufwand und damit einhergehend die Kosten der Herstellung von Gussteilen steigt durch die Notwendigkeit der Nachbearbeitung an. Dabei ist der mit der Nachbearbeitung verbundene Aufwand insbesondere dann hoch, wenn die Formteile als Gießkerne eingesetzt werden, die Innenräume des Gussteils abbilden.The processing costs and, associated with this, the costs of producing cast parts increase due to the need for reworking. In this case, the expense associated with the post-processing is particularly high when the moldings are used as casting cores, which depict the interiors of the casting.
Es ist versucht worden, den mit der Reinigung von Gussteilen verbundenen Aufwand durch den Einsatz von Formstoffen zu vermindern, deren Formgrundstoff hohe Anteile von synthetischem Mullit enthalten. Formstoffe dieser Art besitzen die Eigenschaft, im Zuge der Erstarrung im Gussteil selbsttätig zu zerfallen, so dass sie nach abgeschlossener Gussteilerstarrung einfach entfernt werden können. Allerdings führen die dazu erforderlichen Mengen an Mullit zu hohen Kosten des Formgrundstoffs.Attempts have been made to reduce the expense associated with the cleaning of cast parts through the use of molding materials whose molding base material contains high proportions of synthetic mullite. Moldings of this type possess the property in the course of Solidification in the casting to disintegrate automatically, so that they can be easily removed after completion of casting solidification. However, the required amounts of mullite lead to high costs of the molding material.
Die Aufgabe der Erfindung bestand daher darin, einen Formstoff zu nennen, der die kostengünstige Herstellung von Gießformteilen, insbesondere Gießkernen, ermöglicht. Darüber hinaus sollten kostengünstig herstellbare Formteile und ein Verfahren angegeben werden, das es ermöglicht, derartige Formteile zu erzeugen.The object of the invention was to provide a molding material, which allows the cost-effective production of mold parts, in particular casting cores. In addition, low cost manufacturable molded parts and a method should be specified, which makes it possible to produce such moldings.
In Bezug auf den Formstoff für Formteile von Gießformen zum Vergießen von Metallschmelzen, insbesondere Leichtmetallschmelzen, wie Aluminiumgussschmelzen, wird diese Aufgabe dadurch gelöst, dass ein solcher Foritistoff aus einem auf Basis von quarzfreiem Sand erzeugten Formgrundstoff und einem mit dem Formgrundstoff vermischten, auf Basis von Wasserglas erzeugten anorganischen Binder hergestellt ist.With respect to the mold material for moldings of casting molds for casting molten metals, in particular light metal melts, such as cast aluminum melts, this object is achieved in that such a Foritistoff from a base material produced based on quartz-free sand and mixed with the mold base, based on water glass produced inorganic binder is produced.
Als quarzfreier Sand besonders geeignet ist Olivin-Sand, bei dem es sich um ein weitverbreitetes Mineral handelt, das in großen Mengen kostengünstig erhältlich ist.Particularly suitable as quartz-free sand is olivine sand, which is a widely used mineral that is available inexpensively in large quantities.
Überraschend hat es sich gezeigt, dass Formstoffe, die erfindungsgemäß auf Grundlage eines ganz oder zumindest zum weitaus überwiegenden Teil aus quarzfreien Sanden bestehenden Basisstoffes hergestellt werden, sich vom fertigen Gussteil auch dann einwandfrei ablösen, wenn sie mit einem Wasserglasbinder gebunden sind. Dabei sind die am Gussteil verbleibenden Sandhaftungen auf ein Minimum reduziert. Auf diese Weise kann auch bei Verwendung von Formteilen, die aus erfindungsgemäßen, einen Wasserglasbinder enthaltenden Formstoffen hergestellt sind, garantiert werden, dass sandanhaftungsfreie Gussteile erhalten werden.Surprisingly, it has been shown that molding materials which are produced according to the invention on the basis of a wholly or at least predominantly quartz-free sand base material also detach themselves perfectly from the finished casting when they are bonded with a waterglass binder. The remaining sand retention on the casting is reduced to a minimum. In this way, even when using Moldings made of novel moldings containing a water glass binder can be guaranteed to give sanding adherence-free castings.
Der erfindungsgemäße, auf Grundlage von quarzfreiem Sand, insbesondere Olivin, erzeugte Formstoff schafft die Vorraussetzung für eine kostengünstige Herstellung von Gussteilen. So ist bei Verwendung erfindungsgemäßer Formstoffe der Aufwand für die Sandentfernung gegenüber demjenigen Aufwand verringert, der bei der Reinigung von Gussteilen anfällt, die unter Verwendung von aus herkömmlichen, quarzhaltigen Formstoffen erzeugten Formteilen gegossen worden sind.The molding material produced on the basis of quartz-free sand, in particular olivine, according to the invention creates the prerequisite for cost-effective production of castings. Thus, when using molding materials according to the invention, the outlay for sand removal is reduced compared with that which is obtained in the cleaning of cast parts which have been cast using molded parts produced from conventional, quartz-containing molding materials.
Grundsätzlich kann der erfindungsgemäß verwendete Formgrundstoff vollständig aus quarzfreiem Sand bestehen. Um jedoch neben der Anhaftungsfreiheit auch eine besonders einfache Entfernung der Formteile vom fertig erstarrten Gussteil zu gewährleisten, ist es gemäß einer vorteilhaften Ausgestaltung der Erfindung möglich, dem Formgrundstoff einen Anteil an synthetischem Mullit zuzugeben. Dieser mit dem Hauptbestandteil quarzfreier Sand, insbesondere Olivin, vermischte Mullitanteil unterstützt den selbsttätigen, im Zuge der Erstarrung des Gießbauteils einsetzenden Zerfall der auf Basis des erfindungsgemäßen Formgrundstoffs erzeugten Formteile. Dies erweist sich als besonders günstig, wenn es sich bei den Formteil'en um Gießkerne handelt, die im fertigen Gusstück Hohlräume abbilden.In principle, the molding material used according to the invention can consist entirely of quartz-free sand. However, in order to ensure, in addition to the freedom of adhesion, a particularly simple removal of the molded parts from the completely solidified casting, it is possible according to an advantageous embodiment of the invention to add a proportion of synthetic mullite to the molding base material. This quartz-free sand, in particular olivine, mixed with the main constituent supports mullite content which supports the automatic disintegration of the moldings produced on the basis of the molding base material in the course of the solidification of the casting component. This proves to be particularly advantageous if it s in the molding 'concerns cores that map cavities in the finished Cast.
Die durch den Einsatz von erfindungsgemäßen Formstoffen erreichten positiven Wirkungen stellen sich bei allen gängigen Wassergläsern ein. Dies gilt insbesondere für solche Wassergläser, die ein Modul von 3,3 - 2 aufweisen.The positive effects achieved by the use of molding materials according to the invention are found in all common water glasses. This applies in particular to those water glasses which have a modulus of 3.3-2.
Eine die Anforderungen der Praxis besonders gut erfüllende FormstoffZusammensetzung zeichnet sich dabei dadurch aus, dass sie jeweils 1,5 - 3,0 Gew.-% Wasserglas enthält .A particularly satisfying the requirements of the practice molding composition is characterized in that it contains 1.5 to 3.0 wt .-% of water glass.
Zur Verbesserung der Sandlebenszeit kann der erfindungsgemäße Formstoff 0,3 - 0,5 Gew.-% Natronlauge enthalten.To improve the sand life of the molding material of the invention may contain 0.3 to 0.5 wt .-% sodium hydroxide solution.
In Bezug auf das Formteil wird die oben genannte Aufgabe dadurch gelöst, dass ein erfindungsgemäßes Formteil für Gießformen, bei dem es sich insbesondere um einen Gießkern handelt, aus einem erfindungsgemäßen Formstoff hergestellt ist.With regard to the molded part, the abovementioned object is achieved in that a molded part according to the invention for casting molds, which is in particular a casting core, is produced from a molding material according to the invention.
Grundsätzlich stellen sich die durch Verwendung eines auf der Mischung von quarzfreien Sanden und einem anorganischen Wasserglasbinder basierenden FormstoffSystem beim Abguss von Leichtmetallschmelzen erreichten vorteilhaften Effekte unabhängig davon ein, nach welchem Verfahren die jeweiligen Formteile, insbesondere Gießkerne, hergestellt worden sind.In principle, the advantageous effects achieved by using a molding material system based on the mixture of quartz-free sands and an inorganic water glass binder in the casting of light metal melts are independent of the process by which the respective molded parts, in particular casting cores, have been produced.
Es hat sich jedoch herausgestellt, dass sich das so genannte "Anorganische Warmbox Verfahren" für diesen Zweck besonders eignet. Erfindungsgemäß wird die oben genannte Aufgabe in Bezug auf das Verfahren zum Herstellen eines Formteils für Gießformen, insbesondere zur Herstellung von Gießkernen, dementsprechend dadurch gelöst, dass folgende Arbeitsschritte durchlaufen werden: - Herstellen eines erfindungsgemäßen Formstoffs,However, it has been found that the so-called "inorganic warm box method" is particularly suitable for this purpose. According to the invention, the abovementioned object with respect to the method for producing a molded part for casting molds, in particular for the production of casting cores, is accordingly solved by carrying out the following work steps: Preparing a molding material according to the invention,
- Einfüllen des Formstoffs in einen das Formteil abbildenden Hohlraum eines temperierten Formkasten,Filling of the molding material into a molding cavity of a tempered molding box,
- Verfestigen des Formstoffs in zwei Phasen,Solidifying the molding material in two phases,
- wobei in der ersten Verfestigungsphase der Formstoff in dem temperierten Formkasten gehalten wird, bis eine abriebfeste Randschale des Formteils entstanden ist, und- Wherein in the first solidification phase of the molding material is held in the tempered mold box until an abrasion-resistant edge shell of the molding is formed, and
- wobei das Formteil anschließend aus dem Formkasten entnommen und unter Einwirkung einer Mikrowellenheizung fertig ausgehärtet wird.- The molding is then removed from the molding box and cured fully under the influence of microwave heating.
Mit dieser Vorgehensweise lassen sich aus Formstoffen, die durch Mischen von erfindungsgemäß quarzfreien Sanden, insbesondere Olivinsand-Grundstoffen, mit einem anorganischen Binder hergestellt sind, zuverlässig Formteile fertigen, die nicht nur eine besonders hohe Festigkeit und Abbildungstreue besitzen, sondern darüber hinaus die Eigenschaft haben, bei der Herstellung der Gussteile anhaftungsfrei zu zerfallen. Zerfallsfördernde Zusätze im Bindersystem sind nicht mehr erforderlich. Daher werden bei der Anwendung der Erfindung Belastungen der Umwelt und Gefährdungen der Bedienpersonen durch entweichende Gase vermieden, deren Entstehung und ungewollte Verbreitung bei konventioneller Fertigungsweise nur mit großem technischen Aufwand minimiert werden können.With this procedure, moldings which are produced by mixing quartz-free sands according to the invention, in particular olivine sand precursors, with an inorganic binder can reliably produce molded parts which not only have a particularly high strength and image fidelity, but moreover have the property of to disintegrate without adhesion during the production of the castings. Decay promoting additives in the binder system are no longer required. Therefore, in the application of the invention, environmental stresses and hazards to the operator are avoided by escaping gases whose formation and unwanted spread can be minimized in conventional manufacturing only with great technical effort.
Die Ausbildung der festen, den Weitertransport in den Mikrowellenofen ermöglichenden Außenschale kann dadurch unterstützt werden, dass' der Formstoff während der ersten Phase der Verfestigung unter Unterdruck gehalten wird. In dieser ersten Phase der Verfestigung härtet der Formstoff soweit aus, dass in seinem an die Formwandungen angrenzenden Randbereich eine feste Schicht entsteht, die eine ausreichende Formstabilität des Formstoffs beim nächsten Fertigungsschritt gewährleistet.The formation of the solid, the further transport in the microwave oven enabling outer shell can thereby be supported, that ' the molding material is kept under vacuum during the first phase of solidification. In this first phase of solidification of the molding material hardens to the extent that in its adjoining the mold walls edge region creates a solid layer that ensures sufficient dimensional stability of the molding material in the next manufacturing step.
Abhängig von der Komplexität der Formgebung des jeweils herzustellenden Formteils sollte die Temperatur des Formkastens in der ersten Phase der Verfestigung 150 °C bis '200 °C betragen. Bei Einhaltung dieses Temperaturbereichs während der Bildung des festen Randbereichs der Formteile lassen sich auch solche Gießkerne sicher herstellen, die stark variierende Durchmesserverläufe oder stark ungleichförmige Massenverteilungen aufweisen.Depending on the complexity of the shape of the molding to be produced in each case the temperature of the mold box in the first phase of solidification should be 150 ° C to '200 ° C. By maintaining this temperature range during the formation of the fixed edge region of the moldings, it is also possible to produce such casting cores which have greatly varying diameter profiles or greatly non-uniform mass distributions.
Es hat sich gezeigt, dass sich bei geeigneter Temperaturwahl eine für die Weiterverarbeitung ausreichend beständige Außenschale des Formteils schon dann einstellt, wenn die erste Phase der Verfestigung 10 s bis 50 s dauert.It has been found that, with a suitable choice of temperature, an outer shell of the molded part which is sufficiently resistant to further processing already sets itself up when the first phase of solidification lasts 10 s to 50 s.
Die vollständige Aushärtung des Formteils stellt sich anschließend sicher ein, wenn die Einwirkzeit der Mikrowellenheizung in der zweiten Phase der Verfestigung 2 - 5 Minuten beträgt. Innerhalb dieser Zeitspanne kann die jeweilige Einwirkdauer unter Berücksichtigung der Komplexität der Formgebung so eingestellt werden, dass am Ende der Mikrowellenbehandlung eine für den Abgussprozess ausreichende Endfestigkeit und Trockenheit des Formteils gewährleistet ist. Nachfolgend wird die Erfindung anhand eines Ausführungsbeispiels näher erläutert.The complete curing of the molding then adjusts safely when the exposure time of the microwave heating in the second phase of solidification is 2 - 5 minutes. Within this period of time, the respective exposure time can be adjusted taking into account the complexity of the shaping so that at the end of the microwave treatment sufficient for the casting process final strength and dryness of the molding is guaranteed. The invention will be explained in more detail with reference to an embodiment.
Zur Herstellung eines für den Guss eines Zylinderkopfes aus einer Aluminiumgusslegierung bestimmten Gießkerns ist zunächst ein Formgrundstoff erzeugt worden, der vollständig aus Olivin-Sanden bestand.In order to produce a casting core intended for the casting of a cylinder head from an aluminum casting alloy, first of all a molding base material has been produced which consisted entirely of olivine sands.
Aus diesem Formgrundstoff ist anschließend ein Formstoff erzeugt worden, indem der Formgrundstoff mit einem Wasserglasbinder vermengt worden ist. Zusätzlich ist dem Formgrundstoff ein Anteil Natronlauge zur Verbesserung seiner Haltbarkeit zugegeben worden. Der so zusammengestellte Formgrundstoff enthielt 2,5 Gew.-% Wasserglasbinder, 0,3 Gew.-% Natronlauge und als Rest Formgrundstoff mit der voranstehend erläuterten Zusammensetzung.From this molding material, a molding material has subsequently been produced by mixing the molding material with a waterglass binder. In addition, a proportion of sodium hydroxide solution has been added to the molding base to improve its durability. The mold base material thus composed contained 2.5% by weight of waterglass binder, 0.3% by weight of sodium hydroxide solution and the remainder the molding base material of the above-described composition.
Dieser Formstoff ist in den den fertigen Gießkern abbildenden Hohlraum eines vorgewärmten Formkastens gegeben worden. Aufgrund der ausgezeichneten Fließfähigkeit des Formstoffs sind dabei auch schwierig geformte, kleinteilige Formelemente des Hohlraums sicher gefüllt worden. Diese sichere Formfüllung ist zudem dadurch unterstützt worden, dass der Formkasten schon während des Füllvorgangs mit Unterdruck beaufschlagt wurde. Der Unterdruck betrug 0,3 bar.This molding material has been placed in the cavity of a preheated molding box which images the finished casting core. Due to the excellent flowability of the molding material while difficult-shaped, small-part mold elements of the cavity have been filled safely. This secure mold filling has also been supported by the fact that the mold box has already been subjected to negative pressure during the filling process. The negative pressure was 0.3 bar.
Die Temperatur des Formkastens betrug beim Einfüllen des Formstoffs 180 °C. Bei dieser Temperatur ist der Formstoff nach Beendigung des Füllvorgangs in dem Formkasten für 30 Sekunden bei nach wie vor wirksamer Unterdruckbeaufschlagung gehalten worden. In dieser Zeit bildete sich im Bereich der an die Innenwandungen des Formkastens angrenzenden Bereiche des Formstoffs eine feste Außenschale. Auf diese Weise war am Ende der im Formkasten absolvierten ersten Phase der Verfestigung ein Formteil vorhanden, dessen Festigkeit ausreichte, um es sicher in einen Mikrowellenofen transportieren zu können.The temperature of the mold box was 180 ° C when filling the molding material. At this temperature, after completion of the filling operation in the molding box, the molding material has been held for 30 seconds with still effective negative pressure. At this time formed in the area of the inner walls of the Mold box adjacent areas of the molding material, a solid outer shell. In this way, at the end of the completed in the mold box first stage of solidification, a molding was available, the strength was sufficient to be able to safely transport it in a microwave oven can.
In dem Mikrowellenofen ist das Formteil für 3 Minuten durch Mikrowellen beheizt worden, bis es eine für den Gießeinsatz ausreichende Endfestigkeit erreicht hat.In the microwave oven, the molded article has been microwave heated for 3 minutes until it has reached a final strength sufficient for the casting insert.
Der derart erzeugte Gießkern ist dann in eine Gießform gesetzt worden, in der anschließend die aus der Aluminiumgusslegierung erzeugte Schmelze zu dem herzustellenden Zylinderkopf vergossen worden ist. Im Zuge der Erstarrung ist der Gießkern aufgrund des Temperatureinflusses der Gießwärme und seiner infolge der Erstarrung des Gussstücks eintretenden mechanischen Belastung selbsttätig in viele kleine Bruchstücke zerfallen, die nach der vollständigen Erstarrung des Gussstücks leicht entfernt werden konnten.The casting core thus produced has then been placed in a casting mold, in which subsequently the melt produced from the aluminum casting alloy has been cast to the cylinder head to be produced. In the course of solidification, the casting core is automatically disintegrated into many small fragments due to the temperature influence of the casting heat and its due to the solidification of the casting mechanical stress, which could be easily removed after complete solidification of the casting.
Nach dem Entfernen der Bruchstücke des Gießkerns zeigte sich, dass an den Wänden des Gussstücks, die in unmittelbaren Kontakt mit dem Gießkern gekommen waren, ■ kein Sand mehr anhaftet. Eine nachträgliche Säuberung der durch den Gießkern abgebildeten Kanäle und Hohlräume des Zylinderkopfes war nicht mehr erforderlich. After removing the fragments of the casting core, it was found that no sand adhered to the walls of the casting which had come into direct contact with the casting core. Subsequent cleaning of the ducts and cavities of the cylinder head represented by the casting core was no longer necessary.

Claims

PA T E N T AN S P RÜ C H E PA TENT TO SP RÜ CHE
1. Formstoff für Formteile von Gießformen zum Vergießen von Metallschmelzen, insbesondere1. molding material for moldings of casting molds for casting molten metal, in particular
Leichtmetallschmelzen, wie Aluminiumgussschmelzen, hergestellt aus einem auf Basis von quarzfreiem Sand erzeugten Formgrundstoff und einem mit dem Formgrundstoff vermischten, auf Basis von Wasserglas erzeugten anorganischen Binder.Alloy melts, such as cast aluminum melts, made from a base material made from quartz-free sand and an inorganic binder mixed with the base material and based on water glass.
2. Formstoff nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t, d a s s der quarzfreie Sand Olivin ist.2. The molding material according to claim 1, wherein a quartz-free sand is olivine.
3. Formstoff nach einem der voranstehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, d a s s der Formgrundstoff einen Anteil an synthetischem Mullit enthält.3. The molding material according to claim 1, wherein the molding material contains a proportion of synthetic mullite.
4. Formstoff nach einem der voranstehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, d a s s das Wasserglas ein Modul von 3,3 - 2 aufweist.4. Shaped material according to one of the preceding claims, characterized in that the water glass has a modulus of 3.3 to 2.
5. Formstoff nach einem der voranstehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, d a s s er 1,5 - 3,0 Gew.-% Wasserglas enthält. 5. molding material according to one of the preceding claims, characterized in that it contains 1.5 to 3.0 wt .-% water glass.
6. Formstoff nach einem der voranstehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t, d a s s er 0,3 - 0,5 Gew.-% Natronlauge enthält.6. The molding material according to claim 1, wherein it contains 0.3-0.5% by weight of caustic soda solution.
7. Formteil für Gießformen, insbesondere Gießkerne, hergestellt aus einem gemäß einem der voranstehenden Ansprüche zusammengesetzten Formstoff.7. molding for casting molds, in particular casting cores, made of a composite according to one of the preceding claims molding material.
8. Verfahren zum Herstellen eines Formteils für- Gießfor en, insbesondere zur Herstellung von Gießkernen, umfassend folgende Arbeitsschritte:8. A method for producing a molded article for casting, in particular for the production of casting cores, comprising the following steps:
- Herstellen eines gemäß einem der Ansprüche 1 bis 7 beschaffenen Formstoffs,Preparing a molded article obtained according to one of claims 1 to 7,
- Einfüllen des Formstoffs in einen das Formteil abbildenden Hohlraum eines temperierten Formkastens ,Filling of the molding material into a cavity of a tempered molding box which images the molding,
- Verfestigen des Formstoffs in zwei Phasen,Solidifying the molding material in two phases,
- wobei in der ersten Verfestigungsphase der- wherein in the first solidification phase of
Formstoff in dem temperierten Formkasten gehalten wird, bis eine abriebfeste Randschale des Formteils entstanden ist, undMolded material is held in the tempered mold box until an abrasion-resistant edge shell of the molded part is formed, and
- wobei das Formteil anschließend aus dem Formkasten entnommen und unter Einwirkung einer Mikrowellenheizung fertig ausgehärtet wird.- The molding is then removed from the molding box and cured fully under the influence of microwave heating.
9. Verfahren nach Anspruch 8, d a d u r c h g e k e n n z e i c h n e t, d a s s der Formstoff während der ersten Phase der Verfestigung unter Unterdruck gehalten wird. 9. The method according to claim 8, characterized in that the molding material is kept under negative pressure during the first phase of solidification.
10. Verfahren nach einem der Ansprüche 8 oder 9, d a d u r c h g e k e n n z e i c h n e t, d a s s die Temperatur des Formkastens in der ersten Phase der Verfestigung 150 - 200 °C beträgt.10. A process according to any one of claims 8 or 9, wherein the temperature of the mold box in the first stage of solidification is 150-200 ° C.
11. Verfahren nach einem der Ansprüche 8 bis 10, d a d u r c h g e k e n n z e i c h n e t, d a s s die erste Phase der Verfestigung 10 - 50 Sekunden dauert.11. A process according to any of claims 8 to 10, wherein the first phase of solidification lasts 10 to 50 seconds.
12. Verfahren nach einem der Ansprüche 8 bis 11, d a d u r c h g e k e n n z e i c h n e t, d a s s die Einwirkungszeit der Mikrowellenheizung in der zweiten Phase der Verfestigung 2 - 5 Minuten beträgt. 12. A method according to any one of claims 8 to 11, wherein the exposure time of the microwave heating in the second phase of solidification is 2-5 minutes.
PCT/EP2004/004936 2003-05-09 2004-05-08 Moulding material, moulding part and method for the production of a casting mould WO2004098811A1 (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
DE502004000846T DE502004000846D1 (en) 2003-05-09 2004-05-08 MOLDING MATERIAL, MOLDING AND METHOD FOR PRODUCING SHAPES FOR A MOLDING FORM
EP04731830A EP1620216B1 (en) 2003-05-09 2004-05-08 Moulding material, moulding part and method for the production of a casting mould
AU2004235962A AU2004235962A1 (en) 2003-05-09 2004-05-08 Moulding material, moulding part and method for the production of a casting mould
MXPA05011996A MXPA05011996A (en) 2003-05-09 2004-05-08 Moulding material, moulding part and method for the production of a casting mould.
PL04731830T PL1620216T3 (en) 2003-05-09 2004-05-08 Moulding material, moulding part and method for the production of a casting mould

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DE10321106A DE10321106A1 (en) 2003-05-09 2003-05-09 Molded material, molded part and method for the production of moldings for a casting mold
DE10321106.3 2003-05-09

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EP2163328A1 (en) 2008-09-05 2010-03-17 Minelco GmbH Core or foundry sand coated and/or mixed with soluble glass with a water content in the area of >= approx. 0.25 weight % to approx 0.9 weight %
EP2916976B1 (en) 2013-10-19 2017-03-08 Peak Deutschland GmbH Method for producing lost cores or molded parts for the production of cast parts
DE102014221994B4 (en) * 2014-10-29 2023-03-30 Bayerische Motoren Werke Aktiengesellschaft Manufacture and processing of castings

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ATE330733T1 (en) 2006-07-15
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MXPA05011996A (en) 2006-02-02
DE10321106A1 (en) 2004-12-23

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