EP0578705A1 - Process for casting an aluminium-alloy engine part, in particular a cylinder head. - Google Patents

Process for casting an aluminium-alloy engine part, in particular a cylinder head.

Info

Publication number
EP0578705A1
EP0578705A1 EP92907886A EP92907886A EP0578705A1 EP 0578705 A1 EP0578705 A1 EP 0578705A1 EP 92907886 A EP92907886 A EP 92907886A EP 92907886 A EP92907886 A EP 92907886A EP 0578705 A1 EP0578705 A1 EP 0578705A1
Authority
EP
European Patent Office
Prior art keywords
casting
mold
casting mold
parts
components
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.)
Granted
Application number
EP92907886A
Other languages
German (de)
French (fr)
Other versions
EP0578705B1 (en
Inventor
Herbert Schilling
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.)
VAW Motor GmbH
Original Assignee
EB BRUEHL ALUMINIUMTECHNIK GmbH
BRUEHL ALUMINIUMTECHNIK
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 EB BRUEHL ALUMINIUMTECHNIK GmbH, BRUEHL ALUMINIUMTECHNIK filed Critical EB BRUEHL ALUMINIUMTECHNIK GmbH
Publication of EP0578705A1 publication Critical patent/EP0578705A1/en
Application granted granted Critical
Publication of EP0578705B1 publication Critical patent/EP0578705B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D19/00—Casting in, on, or around objects which form part of the product
    • B22D19/0009—Cylinders, pistons

Definitions

  • Aluminum alloy in particular a cylinder head
  • the invention relates to a method for casting an engine part, in particular a cylinder head, from aluminum alloy by means of a casting mold composed of several parts.
  • valve seat rings In the case of engine parts which are made from aluminum alloy, it is necessary to use components made of a different material at locations which are subjected to high mechanical stress, for example on the valve seats of cylinder heads, which can withstand the stresses required here.
  • the arrangement of such valve seat rings has so far been carried out in such a way that a corresponding recess has been machined into the cylinder head at this point after the casting.
  • the valve seat rings to be used were strongly cooled, for example with liquid nitrogen, and then inserted into the recess, so that the valve seat ring expanded due to heating in the form of a "shrink connection" frictionally stuck in the recess of the cylinder head.
  • valve seat ring which has undercuts on its outside and which is to be cast as a blank to be reworked directly into the cylinder head.
  • undercuts On DE 39 37 402 AI a valve seat ring is also known which has undercuts on its outside and which is to be cast as a blank to be reworked directly into the cylinder head.
  • the invention is based on the fact that in the manufacture of engine parts, in particular cylinder heads made of aluminum alloy, the introduction of components made of materials that are stronger and different from the base material of the engine part is simplified and the precision is improved.
  • This object is achieved in that the parts of the casting mold consist of a non-metallic material and that components to be firmly connected to the engine part to be cast are made of a different, higher melting material than the aluminum alloy when the parts are joined to form the complete casting mold inserted into these at predetermined fixing points and then the casting takes place.
  • This procedure takes advantage of the fact that such casting molds can today be manufactured with great precision in what is known as core molding technology.
  • the actual casting mold is made like a core from a flowable, hardenable molding material, the mold being composed of a total of several parts.
  • the high precision is possible in that the individual core parts are each formed in a core mold consisting of at least two molded parts, that after the molding process of the individual core parts has been completed, their shape is opened such that the core part remains connected to a molded part and then the individual core parts to be joined together with their shaped parts are joined together by defined relative movements of the shaped parts.
  • such a casting mold In the manufacture of engine blocks, cylinder heads or the like, such a casting mold, referred to above as the "core”, is composed of more than two core parts, so that the molded part for a core part defined as a basic core part remains connected to this as a carrier and centering element until all subsequent joining operations have been completed, in which the other core parts are placed on the base core part with the aid of their molded parts. Only then is the complete core, i.e. the complete casting mold, ejected from the carrier element.
  • the joining process can be carried out with great precision Carry out, since the core parts held in their molded part show a spatial orientation that can never be achieved after complete molding. It is advantageously used here that in a molding process in which the binder of the molding material or the core sand is activated not by temperature but by chemical-catalytic processes, the moldings of the individual molding machines have practically the same temperature and so there are no dimensional deviations individual moldings to each other due to thermal expansion.
  • valve seat rings with a conical shape of the outer surface.
  • This enables an optimal shape and dimension for the components, in particular for the valve seat rings.
  • these may have a larger outer diameter than previously, with an increase in diameter of only 1 mm already offering considerable advantages. Since such a valve seat ring is held in a form-fitting manner, it remains permanently connected to the cylinder head.
  • the components are heated before being inserted into the casting mold. This avoids excessive temperature differences, which can have a negative effect on the structure of the aluminum alloy surrounding them.
  • This method is possible because the entire joining process for the production of the casting mold is mechanized, so that it is also possible here to preheat components, in particular preheated valve seat rings, into the corresponding core part via a manipulator integrated in the course of the joining operations to insert. Since the casting mold is made of a non-metallic molding material, there is only a relatively small outflow of heat until the start of the casting.
  • the components are heated electro-inductively after insertion into the casting mold.
  • the electro-inductive heating of the components in the casting mold is possible because the casting mold as a whole does not consist of metal but only of mineral molding material or core sand, so that the components, in particular the valve seat rings, are wholly or partially assembled mold form the only metallic component. This also makes it possible to carry out the heating without contact, preferably immediately before the start of the casting process.
  • Component is necessary, is provided in a particularly advantageous embodiment of the method according to the invention, the components with a fully assembled mold to be heated electro-inductively from the outside. This ensures that the temperature influences on the casting mold which are possible via the heat flow out of the heated component only take place when the casting mold is completely assembled, and therefore no changes in shape can occur here.
  • This also enables a further advantageous embodiment of the method according to the invention, which consists in flushing the mold cavity of the casting mold with a protective gas before starting the heating.
  • This has the advantage that, for example, inserted components made of ferrous materials can be heated up to the temperature of the melt to be poured in of about 800 ° C.
  • Another advantage of heating when the casting mold is completely assembled is that, depending on the position of the component to be cast in the casting mold, in particular in the case of molds above, casting can still be started during the heating phase, so that the desired final temperature for the heat to be heated Component is reached at the moment when contact with the melt occurs.
  • Fig. 1 shows the process flow in the form of a
  • Fig. 3 shows the finished cylinder head with a cast-in valve seat ring.
  • Cylinder head must be assembled from several core parts due to the many undercuts and channels.
  • the individual core parts are manufactured using separate core molding machines and then assembled.
  • the flow picture acc. 1 shows the process sequence in a simplified representation for a casting mold composed of only two core parts.
  • a core molding machine I which has a molding box formed from two molded parts 1 and 2
  • a first core part 3 is produced in a customary manner, for example by the cold box process, from a corresponding molding sand.
  • the associated core part 4 which together with the core part 3 forms the complete casting mold, is produced in a second core molding machine II, which has a core mold composed of a molded part 5 and an associated molded part 6.
  • a component 7 to be cast in, for example a valve seat ring is now placed with the aid of a manipulator.
  • the associated core part 4 which is still connected to the molded part 5, is now positioned by the core molding machine II and then lowered onto the core part 3 or that Core part 3 raised so that both core parts 3 and 4 are joined together to form the finished casting mold.
  • the molded part 5 is then detached from the core part 4 and in a further station V the finished casting mold 3-4, which now also encloses the inserted valve seat ring 7, from the molded part 1, which has served as a centering and guiding means during the entire process , loosened and moved to the casting station VI and poured there. After cooling, the casting mold is destroyed and the molding sand is reprocessed.
  • the valve seat ring 7 is expedient in the process sequence shown here. first heated up and then placed over the manipulator.
  • the temperature loss is up to the point in time when the valve seat ring with the melt is in Contact comes in, of minor importance.
  • valve seat rings to be cast in since cylinder heads represent relatively flat components which enable electro-inductive heating without excessive energy expenditure, i.e. from the outside, i.e. when the casting mold is already fully assembled and is in contact with the casting device.
  • the valve seat ring 7 is placed on a core mark 8 of the core part 3, so that when the casting mold 3-4 is closed, as shown in FIG. 1 for the station V, with an associated part 9 of the core part 4 the valve channel is kept clear and at the same time the valve seat blank is fixed in the casting mold. 2 shows, the outer surface of the valve seat ring 7 is conical, so that after removal of the casting mold, as shown schematically in FIG. 3, it is held in a form-fitting manner in the finished casting 10.
  • the core part 3 has a downwardly open recess 11 into which a water-cooled induction coil 12 can be inserted, which , the end region directly facing the valve seat ring to be heated is provided with an iron core 13.
  • This form of heating is possible because the casting mold 3-4 overall, in addition to the inserted components, here the valve seat rings 7, has no metallic parts. Since the mold 3-4 is already completely closed at this point, the mold cavity 14 can first be flushed with a protective gas, for example nitrogen, so that the valve seat rings 7 can then be heated to temperatures up to 800 ° C. without oxidation. Because of the low mass, the valve seat rings can be heated up in a few seconds, so that casting can still be started during the heating process, so that the heating up phase
  • a protective gas for example nitrogen
  • FIGS. 2 and 3 The example of a cylinder head for an engine with four valves per cylinder, which is shown schematically in FIGS. 2 and 3, shows the considerable manufacturing advantage of the method. Since the valve blanks 7 are cast geometrically precisely in the desired assignment, the subsequent finishing 5 is simplified.

Abstract

In engine parts made of aluminium alloy, components such as the cylinder-head valve-seat rings which are made of high-strength materials must be held rigidly in place. Machining them is long. The invention proposes a process for casting an aluminium-alloy engine part using a casting mould made up of one ore more parts. In this process, the components, in particular the valve-seat rings, which have to be rigidly joined to the engine part, and which are made of a different material, whose melting point is at least as high as that of the engine material, are introduced into the mould, before the mould is assembled, at points indicated by suitable marks, the mould assembled, and the motor part itself then cast.

Description

Bezeichnung: Verfahren zum Gießen eines Motorenteils ausName: Process for casting an engine part from
Aluminiumlegierung, insbesondere eines Zylin¬ derkopfesAluminum alloy, in particular a cylinder head
Beschreibung:Description:
Die Erfindung betrifft ein Verfahren zum Gießen eines Motorenteiles, insbesondere eines Zylinderkopfes, aus Aluminiumlegierung mittels einer aus mehreren Teilen zu¬ sammengesetzten Gießform.The invention relates to a method for casting an engine part, in particular a cylinder head, from aluminum alloy by means of a casting mold composed of several parts.
Bei Motorteilen, die aus Aluminiumlegierung hergestellt sind, ist es erforderlich, an mechanisch hochbeanspruchten Stellen Bauelemente, beispielsweise an den Ventilsitzen von Zylinderköpfen Ventilsitzringe aus einem anderen Material einzusetzen, die den hier geforderten Beanspru¬ chungen standhalten. Speziell die Anordnung derartiger Ventilsitzringe wurde bisher in der Weise vorgenommen, daß an dieser Stelle in den Zylinderkopf eine entsprechende Ausnehmung nach dem Gießen mechanisch eingearbeitet wurde. Die einzusetzenden Ventilsitzringe wurden stark gekühlt, beispielsweise mit flüssigem Stickstoff, und dann in die eingearbeitete Ausnehmung eingelegt, so daß der Ventil¬ sitzring aufgrund seiner Ausdehnung infolge Erwärmung in Form einer "Schrumpfverbindung" reibschlüssig in der Ausnehmung des Zylinderkopfes festsitzt. Der Nachteil dieser Verfahrensweise besteht darin, daß die Ausnehmung sehr präzise gefertigt werden muß, da für derartige Schrumpf- Verbindung verhältnismäßig enge Toleranzen zwischen dem lichten Innendurchmesser der Ausnehmung einerseits und dem Außendurchmesser des einzusetzenden Ventilsitzringes andererseits eingehalten werden müssen. Bei herkömmlichen, insbesondere aber bei modernen Motoren mit mehr als zwei Ventilen je Zylinder ergibt sich somit ein hoher Fertigungs¬ aufwand. Ferner besteht der Nachteil, daß in Einzelfällen im späteren Betrieb ein Ventilsitzring herausfallen kann, so daß der Motor stark beschädigt wird. Das Einbringen anderer Bauelemente, wie beispielsweise Ventilführungen oder dergl. erfordert ebenfalls eine Bearbeitung nach dem Guß.In the case of engine parts which are made from aluminum alloy, it is necessary to use components made of a different material at locations which are subjected to high mechanical stress, for example on the valve seats of cylinder heads, which can withstand the stresses required here. In particular, the arrangement of such valve seat rings has so far been carried out in such a way that a corresponding recess has been machined into the cylinder head at this point after the casting. The valve seat rings to be used were strongly cooled, for example with liquid nitrogen, and then inserted into the recess, so that the valve seat ring expanded due to heating in the form of a "shrink connection" frictionally stuck in the recess of the cylinder head. The disadvantage of this procedure is that the recess has to be manufactured very precisely, since for such shrink connection relatively narrow tolerances between the inside diameter of the recess on the one hand and the outside diameter of the valve seat ring to be used on the other must be observed. In conventional, but especially in modern engines with more than two valves per cylinder, this results in a high manufacturing cost. There is also the disadvantage that a valve seat ring can fall out in individual cases in later operation, so that the engine is severely damaged. The introduction of other components, such as valve guides or the like. Also requires processing after casting.
Aus der DE 39 37 402 AI ist ferner ein Ventilsitzring bekannt, der auf seiner Außenseite Hinterschneidungen aufweist und der als nachzuarbeitender Rohling unmittel¬ bar in den Zylinderkopf eingegossen werden soll. Es hat sich jedoch gezeigt, daß trotz der durch die Hinterschnei¬ dungen bewirkten formschlüssigen Einbindung , keine befrie¬ digenden Ergebnisse erzielt werden konnten. Dies beruht ■ darauf, daß bei den bisher verwendeten Gießfor¬ men eine exakte Positionierung des einzulegenden Ventil¬ sitzringrohlings nicht möglich war, so daß bei der an¬ schließenden Bearbeitung der Ventilsitzflache aufgrund von Verschiebungen erhebliche Abweichungen in der Zentrie- rung auftraten.From DE 39 37 402 AI a valve seat ring is also known which has undercuts on its outside and which is to be cast as a blank to be reworked directly into the cylinder head. However, it has been shown that, despite the form-fitting integration brought about by the undercuts, no satisfactory results could be achieved. This is based on the fact that, in the casting molds previously used, exact positioning of the valve seat ring blank to be inserted was not possible, so that during the subsequent machining of the valve seat surface considerable deviations in the centering occurred due to displacements.
Der Erfindung liegt nun die Aufgrund zugrunde, bei der Herstellung von Motorteilen, insbesondere Zylinderköpfen aus Aluminiumlegierung das Einbringen von Bauelementen aus anderen, festeren Werkstoffen als dem Grundwerkstoff des Motorteils zu vereinfachen und die Präzision zu verbes¬ sern. Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß die Teile der Gießform aus einem nicht-metallischen Werk¬ stoff bestehen, und daß mit dem zu gießenden Motorteil fest zu verbindende Bauelemente aus einem anderen höher- schmelzendem Werkstoff als sie Aluminiumlegierung beim Zusammenfügen der Teile zur vollständigen Gießform in diese an vorgegebenen Fixierpunkten eingelegt und danach der Abguß erfolgt. Bei dieser Verfahrensweise wird mit Vorteil ausgenutzt, daß derartige Gießformen heute in der sogenannten Kernformtechnik mit großer Präzision her¬ gestellt werden können. Hierbei wird die eigentliche Gie߬ form wie ein Kern aus einem fließfähigen, aushärtbaren Formstoff hergestellt, wobei die Form insgesamt aus mehre¬ ren Teilen zusammengesetzt ist. Die hohe Präzision ist dadurch möglich, daß die einzelnen Kernteile jeweils in einer aus wenigstens zwei Formteilen bestehenden Kernform für sich geformt werden, daß jeweils nach Abschluß des Formprozesses der einzelnen Kernteile deren Form so geöffnet wird, daß der Kernteil mit einem Formteil verbunden bleibt und danach die einzelnen zusammenzufügenden Kernteile mit ihren Formteilen durch definierte Relativbewegungen der Formteile zueinander zusammengefügt werden. Bei der Herstellung von Motorblöcken, Zylinderköpfen oder dergl. ist eine derartige, vorstehend als "Kern" bezeichnete Gießform aus mehr als zwei Kernteilen zusammengesetzt, so daß das Formteil für einen als Basiskernteil definierten Kernteil als Träger und Zentrierelement mit diesem ver¬ bunden bleibt, bis alle nachfolgenden Fügeoperationen abgeschlossen sind, in denen jeweils die weiteren Kernteile mit Hilfe ihrer Formteile auf das Basiskernteil aufgesetzt sind. Erst danach wird der vollständige Kern, also die vollständige Gießform, aus dem Trägerelement ausgestoßen. Da bei diesem Verfahren die für das Zusammenfügen erforder¬ liche geometrische Zuordnung und die daraus resultierende Relativbewegung der zusammenzufügenden Kernteile zueinander durch die entsprechende Ausrichtung und Bewegung der Form¬ teile zueinander und nicht mehr durch die Kernteile selbst erfolgt, läßt sich der Fügevorgang mit großer Präzision durchführen, da die jeweils in ihrem Formteil gehaltenen Kernteile eine räumliche Ausrichtung ausweisen, wie sie nach einem vollständigen Ausformen nie wieder zu erreichen ist. Hierbei wird mit Vorteil ausgenutzt, daß bei einem Formprozeß, bei dem das Bindemittel des Formstoffes bzw. des Kernsandes nicht durch Temperatur sondern durch chemisch-katalytische Vorgänge aktiviert wird, die Form¬ teile der einzelnen Formmaschinen praktisch die gleiche Temperatur aufweisen und so keinerlei Maßabweichungen der einzelnen Formteile zueinander durch Wärmedehnungen auftreten. Damit ist es möglich, die einzelnen Formteile mit einander zuordenbaren Führungs- und Zentrierflächen zu versehen, so daß die Genauigkeit beim Zusammenfügen der Kernteile über die mit ihnen verbundenen Formteile zu einer Gießform aus einem nicht-metallischen Formstoff unterstützt wird. Da alle einzelnen Teile der Gießform jeweils neu hergestellt und mit großer Präzision zusammen¬ gefügt werden, ist es nunmehr möglich, auch mit dem herzu¬ stellenden Motorteil fest zu verbindende Bauelemente aus einem anderen Werkstoff, insbesondere Ventilsitzringe an Zylinderköpfen, die in ihrer geometrischen Anordnung mit großer Genauigkeit angeordnet sein müssen, unmittelbar einzugießen. Hierzu ist es lediglich notwendig, an den betreffenden Teilen der Gießform entsprechende Fixierpunkte vorzusehen, auf die oder in die die einzugießenden Bau¬ elemente beim Zusammenfügen der Gießform eingelegt werden. Damit ist es möglich, beispielsweise Ventilsitzringe mit konischem Verlauf der Außenfläche formschlüssig einzugießen. Hierdurch ist eine optimale Formgebung und Abmessung für die Bauelemente, insbesondere für die Ventilsitzringe, möglich. Diese können beispielsweise einen größeren Außen¬ durchmesser als bisher aufweisen, wobei eine Durchmesser- vergrδßerung von nur 1 mm bereits erhebliche Vorteile bietet. Da ein derartiger Ventilsitzring formschlüssig gehalten ist, bleibt er unlösbar mit dem Zylinderkopf verbunde . In Ausgestaltung der Erfindung ist vorgesehen, daß die Bauelemente vor dem Einlegen in die Gießform aufgeheizt werden. Hierdurch werden allzu große Temperaturunterschiede, die sich nachteilig auf das Gefüge der sie umschließenden Aluminiumlegierung auswirken können, vermieden. Dieses Verfahren ist schon deshalb möglich, weil der gesamte Fügevorgang zur Herstellung der Gießform mechanisiert ist, so daß es auch hier möglich ist, vorgeheizte Bau¬ elemente, insbesondere vorgeheizte Ventilsitzringe, über einen in den Ablauf der Fügeoperationen integrierten Manipu¬ lator in das entsprechende Kernteil einzulegen. Da die Gießform aus einem nicht-metallischen Formstoff besteht, erfolgt auch nur ein verhältnismäßig geringer Wärmeabfluß bis zum Beginn des Abgusses.The invention is based on the fact that in the manufacture of engine parts, in particular cylinder heads made of aluminum alloy, the introduction of components made of materials that are stronger and different from the base material of the engine part is simplified and the precision is improved. This object is achieved in that the parts of the casting mold consist of a non-metallic material and that components to be firmly connected to the engine part to be cast are made of a different, higher melting material than the aluminum alloy when the parts are joined to form the complete casting mold inserted into these at predetermined fixing points and then the casting takes place. This procedure takes advantage of the fact that such casting molds can today be manufactured with great precision in what is known as core molding technology. Here, the actual casting mold is made like a core from a flowable, hardenable molding material, the mold being composed of a total of several parts. The high precision is possible in that the individual core parts are each formed in a core mold consisting of at least two molded parts, that after the molding process of the individual core parts has been completed, their shape is opened such that the core part remains connected to a molded part and then the individual core parts to be joined together with their shaped parts are joined together by defined relative movements of the shaped parts. In the manufacture of engine blocks, cylinder heads or the like, such a casting mold, referred to above as the "core", is composed of more than two core parts, so that the molded part for a core part defined as a basic core part remains connected to this as a carrier and centering element until all subsequent joining operations have been completed, in which the other core parts are placed on the base core part with the aid of their molded parts. Only then is the complete core, i.e. the complete casting mold, ejected from the carrier element. Since in this method the geometric assignment required for the joining and the resulting relative movement of the core parts to be joined to one another takes place through the corresponding alignment and movement of the molded parts relative to one another and no longer through the core parts themselves, the joining process can be carried out with great precision Carry out, since the core parts held in their molded part show a spatial orientation that can never be achieved after complete molding. It is advantageously used here that in a molding process in which the binder of the molding material or the core sand is activated not by temperature but by chemical-catalytic processes, the moldings of the individual molding machines have practically the same temperature and so there are no dimensional deviations individual moldings to each other due to thermal expansion. This makes it possible to provide the individual molded parts with mutually assignable guide and centering surfaces, so that the accuracy when the core parts are joined together via the molded parts connected to them is supported to form a casting mold made of a non-metallic molding material. Since all individual parts of the casting mold are each newly manufactured and joined together with great precision, it is now possible to also connect components made of a different material to the engine part to be manufactured, in particular valve seat rings on cylinder heads, in their geometric arrangement must be arranged with great accuracy to pour immediately. For this purpose, it is only necessary to provide corresponding fixing points on the relevant parts of the casting mold, onto which or into which the components to be cast in are inserted when the casting mold is joined. This makes it possible, for example, to form-fit valve seat rings with a conical shape of the outer surface. This enables an optimal shape and dimension for the components, in particular for the valve seat rings. For example, these may have a larger outer diameter than previously, with an increase in diameter of only 1 mm already offering considerable advantages. Since such a valve seat ring is held in a form-fitting manner, it remains permanently connected to the cylinder head. In an embodiment of the invention it is provided that the components are heated before being inserted into the casting mold. This avoids excessive temperature differences, which can have a negative effect on the structure of the aluminum alloy surrounding them. This method is possible because the entire joining process for the production of the casting mold is mechanized, so that it is also possible here to preheat components, in particular preheated valve seat rings, into the corresponding core part via a manipulator integrated in the course of the joining operations to insert. Since the casting mold is made of a non-metallic molding material, there is only a relatively small outflow of heat until the start of the casting.
In einer anderen Ausgestaltung der Erfindung ist vorgesehen, daß die Bauelemente nach dem Einlegen in die Gießform elektro-induktiv aufgeheizt werden. Hierdurch wird der Einlegevorgang beispielsweise für die Ventilsitzringe vereinfacht, da diese bei Raumtemperatur gehandhabt werden können, wohingegen der Aufheizvorgang erst dann in einer weiteren Station erfolgt, wenn die Ventilsitzringe bereits eingelegt sind. Das elektro-induktive Aufheizen der Bau¬ elemente in der Gießform ist deshalb möglich, weil die Gießform insgesamt nicht aus Metall sondern nur aus minera¬ lischem Formstoff bzw. Kernsand besteht, so daß die Bau¬ elemente, insbesondere die Ventilsitzringe in der ganz oder teilweise zusammengefügten Gießform den einzigen metallischen Bestandteil darstellen. Damit ist es auch möglich, die Aufheizung berührungslos vorzunehmen, vorzugs¬ weise unmittelbar vor dem Beginn des Gießvorganges.In another embodiment of the invention it is provided that the components are heated electro-inductively after insertion into the casting mold. This simplifies the insertion process, for example for the valve seat rings, since these can be handled at room temperature, whereas the heating process only takes place in a further station when the valve seat rings have already been inserted. The electro-inductive heating of the components in the casting mold is possible because the casting mold as a whole does not consist of metal but only of mineral molding material or core sand, so that the components, in particular the valve seat rings, are wholly or partially assembled mold form the only metallic component. This also makes it possible to carry out the heating without contact, preferably immediately before the start of the casting process.
Während es grundsätzlich möglich ist, die in die Gießform eingelegten Bauelemente bei noch geöffneter Form elektro- induktiv aufzuheizen, was je nach Form des betreffendenWhile it is fundamentally possible to heat the components inserted into the casting mold with the mold still open, this is dependent on the shape of the relevant component
Bauelementes notwendig ist, ist in besonders vorteilhafter Ausgestaltung des erfindungsgemäßen Verfahrens vorgesehen, die Bauelemente bei vollständig zusammengefügter Gießform von außen elektro-induktiv aufzuheizen. Hierdurch ist sichergestellt, daß die über den Wärmeabfluß aus dem aufge¬ heizten Bauelement möglichen Temperaturbeeinflussungen der Gießform erst bei vollständig zusammengefügter Gieß- form erfolgen und somit hier keine Formveranderungen auf¬ treten können. Dies ermöglicht darüber hinaus eine weitere vorteilhafte Ausgestaltung des erfindungsgemäßen Verfahrens, die darin besteht, daß der Formhohlraum der Gießform vor Beginn des Aufheizens mit einem Schutzgas gespült wird. Dies hat den Vorteil, daß beispielsweise eingelegte Bau¬ elemente aus Eisenwerkstoffen bis auf die Temperatur der einzugießenden Schmelze von etwa 800°C aufgeheizt werden können, ohne daß die einzugießenden Oberflächen oxidieren können und somit ein einwandfrei rein-metallischer Flächen- kontakt zwischen dem Bauelement und dem Gießwerkstoff erzielt wird. Ein weiterer Vorteil des Aufheizens bei vollständig zusammengefügter Gießform besteht darin, daß je nach der Lage des einzugießenden Bauelementes in der Gießform, insbesondere bei obenliegenden Gießformen, mit dem Abguß noch während der Aufheizphase begonnen werden kann, so daß die gewünschte Endtemperatur für das aufzuhei¬ zende Bauelement in dem Augenblick erreicht ist, in dem der Kontakt mit der Schmelze eintritt.Component is necessary, is provided in a particularly advantageous embodiment of the method according to the invention, the components with a fully assembled mold to be heated electro-inductively from the outside. This ensures that the temperature influences on the casting mold which are possible via the heat flow out of the heated component only take place when the casting mold is completely assembled, and therefore no changes in shape can occur here. This also enables a further advantageous embodiment of the method according to the invention, which consists in flushing the mold cavity of the casting mold with a protective gas before starting the heating. This has the advantage that, for example, inserted components made of ferrous materials can be heated up to the temperature of the melt to be poured in of about 800 ° C. without the surfaces to be poured in being able to oxidize and thus a perfectly pure metallic surface contact between the component and the casting material is achieved. Another advantage of heating when the casting mold is completely assembled is that, depending on the position of the component to be cast in the casting mold, in particular in the case of molds above, casting can still be started during the heating phase, so that the desired final temperature for the heat to be heated Component is reached at the moment when contact with the melt occurs.
Die Erfindung wird anhand einer schematischen Darstellung näher erläutert. Es 'zeigen:The invention is explained in more detail with reference to a schematic representation. It ' show:
Fig. 1 den Verfahrensablauf in Form einesFig. 1 shows the process flow in the form of a
Fließbildes,Flow diagram,
Fig. 2 in einem vertikalen Teilschnitt einen in eine Gießform eingelegten Ventil¬ sitzring,2 in a vertical partial section, a valve seat ring inserted into a casting mold,
Fig. 3 den fertigen Zylinderkopf mit eingegossenem Ventilsitzring. Eine aus Kernformsand hergestellte Gießform für einenFig. 3 shows the finished cylinder head with a cast-in valve seat ring. A mold made from core molding sand for one
Zylinderkopf muß wegen der vielen Hinterschneidungen und Kanälen aus mehreren Kernteilen zusammengesetzt werden. Die einzelnen Kernteile werden über gesonderte Kernform- maschinen hergestellt und dann zusammengefügt. Das Flie߬ bild gem. Fig. 1 zeigt den Verfahrensablauf in vereinfachter Darstellung für eine aus nur zwei Kernteilen zusammenge¬ setzte Gießform. Hierbei wird in einer Kernformmaschine I, die einen aus zwei Formteilen 1 und 2 gebildeten Form- kästen aufweist, ein erster Kernteil 3 in üblicher Weise, beispielsweise nach dem cold-box-Verfahren aus einem ent¬ sprechenden Formsand hergestellt. Das zugehörige Kernteil 4, das zusammen mit dem Kernteil 3 die vollständige Gie߬ form bildet, wird in einer zweiten Kernformmaschine II hergestellt, die eine aus einem Formteil 5 und einem zugehö¬ rigen Formteil 6 zusammengesetzte Kernform aufweist. Sobald die beiden Kernteile 3 und 4 "geschossen" sind, öffnen die Kernformen, wobei in der Kernformmaschine I der Kern¬ teil 3 im Formteil 1 verbleibt und in eine erste Fügesta- tion III verfahren wird. Auf das offenliegende KernteilCylinder head must be assembled from several core parts due to the many undercuts and channels. The individual core parts are manufactured using separate core molding machines and then assembled. The flow picture acc. 1 shows the process sequence in a simplified representation for a casting mold composed of only two core parts. In this case, in a core molding machine I, which has a molding box formed from two molded parts 1 and 2, a first core part 3 is produced in a customary manner, for example by the cold box process, from a corresponding molding sand. The associated core part 4, which together with the core part 3 forms the complete casting mold, is produced in a second core molding machine II, which has a core mold composed of a molded part 5 and an associated molded part 6. As soon as the two core parts 3 and 4 have been “shot”, the core molds open, the core part 3 remaining in the mold part 1 in the core molding machine I and being moved into a first joining station III. On the exposed core part
3 wird nun ein einzugießendes Bauelement 7, beispielsweise ein Ventilsitzring, mit Hilfe eines Manipulators aufgelegt. In einem nächsten Verfahrensschritt, der in der Fügestation III oder in einer nächstfolgenden Fügestation IV erfolgen kann, wird nun von der Kernformmaschine II das zugehörige Kernteil 4, das noch mit dem Formteil 5 verbunden ist, positioniert und anschließend auf das Kernteil 3 abgesenkt bzw. das Kernteil 3 angehoben, so daß beide Kernteile 3 und 4 zur fertigen Gießform zusammengefügt werden. Das Formteil 5 wird dann vom Kernteil 4 gelöst und in einer weiteren Station V die fertige Gießform 3-4, die nunmehr den eingelegten Ventilsitzring 7 mit umschließt, vom Form¬ teil 1, das während des ganzen Verfahrensablaufs als Zen¬ trierung und Führungsmittel gedient hat, gelöst und zur Gießstation VI verfahren und dort abgegossen. Nach dem Erkalten wird die Gießform zerstört und der anfallende Formsand wieder aufbereitet. Der Ventilsitzring 7 wird bei dem hier dargestellten Verfahrensablauf zweckmäßiger- weise erst aufgeheizt und dann über den Manipulator auf¬ gelegt. Da die Gießform aus einem nicht-metallischen Werk¬ stoff besteht und die Fügeoperation und die Weiterfüh¬ rung der vollständigen Gießform bis zur GießStation VI in kurzer Zeit von statten geht, ist der Temperaturverlust bis zu dem Zeitpunkt, in dem der Ventilsitzring mit der Schmelze in Kontakt kommt, von untergeordneter Bedeutung.3, a component 7 to be cast in, for example a valve seat ring, is now placed with the aid of a manipulator. In a next process step, which can take place in the joining station III or in a subsequent joining station IV, the associated core part 4, which is still connected to the molded part 5, is now positioned by the core molding machine II and then lowered onto the core part 3 or that Core part 3 raised so that both core parts 3 and 4 are joined together to form the finished casting mold. The molded part 5 is then detached from the core part 4 and in a further station V the finished casting mold 3-4, which now also encloses the inserted valve seat ring 7, from the molded part 1, which has served as a centering and guiding means during the entire process , loosened and moved to the casting station VI and poured there. After cooling, the casting mold is destroyed and the molding sand is reprocessed. The valve seat ring 7 is expedient in the process sequence shown here. first heated up and then placed over the manipulator. Since the casting mold consists of a non-metallic material and the joining operation and the continuation of the complete casting mold up to the casting station VI take place in a short time, the temperature loss is up to the point in time when the valve seat ring with the melt is in Contact comes in, of minor importance.
Das Verfahren zur Aufheizung des einzugießenden Bauelemen- tes läßt sich beispielsweise bei einzugießenden Ventilsitz¬ ringen noch verbessern, da Zylinderköpfe verhältnismäßig flache Bauelemente darstellen, die ein elektro-induktives Aufheizen ohne allzu hohen Energieaufwand auch von außen ermöglichen, d.h. wenn die Gießform bereits vollständig zusammengefügt ist und sich in Kontakt mit der Gießvor¬ richtung befindet. Wie in Fig. 2 in einem vergrößerten Teilschnitt dargestellt ist, wird der Ventilsitzring 7 auf eine Kernmarke 8 des Kernteils 3 aufgesetzt, so daß bei geschlossener Gießform 3-4, wie in Fig. 1 für die Station V dargestellt, mit einem zugehörigen Teil 9 des Kernteils 4 der Ventilkanal freigehalten und zugleich der Ventilsitzrohling in der Gießform fixiert ist. Wie Fig. 2 zeigt, ist die Außenfläche des Ventilsitzringes 7 konisch ausgebildet, so daß er nach Entfernen der Gießform, wie Fig. 3 schematisch zeigt, formschlüssig im fertigen Gußstück 10 gehalten ist.The method for heating the component to be cast in can be further improved, for example, in the case of valve seat rings to be cast in, since cylinder heads represent relatively flat components which enable electro-inductive heating without excessive energy expenditure, i.e. from the outside, i.e. when the casting mold is already fully assembled and is in contact with the casting device. As shown in an enlarged partial section in FIG. 2, the valve seat ring 7 is placed on a core mark 8 of the core part 3, so that when the casting mold 3-4 is closed, as shown in FIG. 1 for the station V, with an associated part 9 of the core part 4 the valve channel is kept clear and at the same time the valve seat blank is fixed in the casting mold. 2 shows, the outer surface of the valve seat ring 7 is conical, so that after removal of the casting mold, as shown schematically in FIG. 3, it is held in a form-fitting manner in the finished casting 10.
Damit nun der eingelegte Ventilsitzring 7 unmittelbar im Bereich der GießStation VI elektro-induktiv in der geschlossenen Form aufgeheizt werden kann, weist der Kern¬ teil 3 eine nach unten offene Ausnehmung 11 auf, in die eine wassergekühlte Induktionsspule 12 eingeführt werden kann, die in ihrem, dem aufzuheizenden Ventilsitzring unmittelbar zugekehrten Stirnbereich mit einem Eisen- kern 13 versehen ist. Diese Form der Aufheizung ist des¬ halb möglich, weil die Gießform 3-4 insgesamt außer den eingelegten Bauelementen, hier den Ventilsitzringen 7, keine metallischen Teile aufweist. Da die Gießform 3-4 zu diesem Zeitpunkt bereits vollständig geschlossen ist, kann der Formhohlraum 14 zunächst mit einem Schutzgas, beispielsweise Stickstoff durchspült werden, so daß dann die Ventilsitzringe 7 oxidationsfrei auf Temperaturen bis zu 800°C aufgeheizt werden können. Wegen der geringen Masse sind hierbei die Ventilsitzringe in wenigen Sekunden aufheizbar, so daß noch während des Aufheizvorganges mit dem Guß begonnen werden kann, so daß die AufheizphaseSo that the inserted valve seat ring 7 can be heated electro-inductively in the closed form directly in the area of the casting station VI, the core part 3 has a downwardly open recess 11 into which a water-cooled induction coil 12 can be inserted, which , the end region directly facing the valve seat ring to be heated is provided with an iron core 13. This form of heating is possible because the casting mold 3-4 overall, in addition to the inserted components, here the valve seat rings 7, has no metallic parts. Since the mold 3-4 is already completely closed at this point, the mold cavity 14 can first be flushed with a protective gas, for example nitrogen, so that the valve seat rings 7 can then be heated to temperatures up to 800 ° C. without oxidation. Because of the low mass, the valve seat rings can be heated up in a few seconds, so that casting can still be started during the heating process, so that the heating up phase
10 bei der gewünschten Endtemperatur erst in dem Augenblick beendet ist, wenn die in die Form einlaufende Schmelze mit den einzugießenden Bauelementen, hier den Ventilsitz¬ ringen 7, in Kontakt kommt. Durch diese zeitlichen Über¬ schneidungen des Endes der Aufheizphase einerseits und •■•••*• des Beginns der Gießphase andererseits, kann eine für die Serienproduktion wünschenswerte Zeitverkürzung des Gießvorganges insgesamt erreicht werden.10 at the desired final temperature is only completed when the melt entering the mold comes into contact with the components to be poured in, here the valve seat rings 7. By this time Über¬ the end of the heating phase overlaps one hand, and • ■ ••• * • the beginning of the casting phase, on the other hand, a desirable time for mass production can shorten the casting process as a whole achieved.
Das in Fig. 2 und 3 schematisch dargestellte Ausführungs¬ 0 beispiel eines Zylinderkopfes für einen Motor mit vier Ventilen je Zylinder läßt den erheblichen fertigungstech¬ nischen Vorteil des Verfahrens erkennen. Da die Ventilroh¬ linge 7 geometrisch genau in der gewünschten Zuordnung eingegeossen sind, wird die anschließende Fertigbearbei- 5 tung vereinfacht.The example of a cylinder head for an engine with four valves per cylinder, which is shown schematically in FIGS. 2 and 3, shows the considerable manufacturing advantage of the method. Since the valve blanks 7 are cast geometrically precisely in the desired assignment, the subsequent finishing 5 is simplified.
00
5 5

Claims

Ansprüche: Expectations:
1. Verfahren zum Gießen eines Motorteils, insbesondere eines Zylinderkopfes, aus Alumiumlegierung mittels einer aus mehreren Teilen zusammengesetzten Gießform, dadurch gekennzeichnet, daß die Teile (3, 4) der Gießform aus einem nicht-metalli¬ schen Formstoff bestehen, daß mit dem zu gießenden Motor¬ teil fest zu verbindende Bauelemente (7) aus einem anderen höherschmelzenden Werkstoff als die Aluminiumlegierung beim Zusammenfügen der Teile zur vollständigen Gießform in diese an vorgegebenen Fixierungspunkten (8) eingelegt werden und danach der Abguß erfolgt.1. A method for casting a motor part, in particular a cylinder head, made of aluminum alloy by means of a casting mold composed of several parts, characterized in that the parts (3, 4) of the casting mold consist of a non-metallic molding material that with the to be cast Components (7) which are to be firmly connected to the motor and are made of a higher melting material than the aluminum alloy when the parts are assembled to form the complete casting mold are inserted into them at predetermined fixing points (8) and the casting is then carried out.
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Bauelemente (7) vor dem Einlegen in die Gießform aufgeheizt werden.2. The method according to claim 1, characterized in that the components (7) are heated before insertion into the mold.
3. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Bauelemente (7) nach dem Einlegen in die Gießform elektro-induktiv aufgeheizt werden.3. The method according to claim 1, characterized in that the components (7) are heated electro-inductively after insertion into the mold.
4. Verfahren nach Anspruch 1 und 3, dadurch gekennzeichnet, daß die Bauelemente (7) bei vollständig zusammengefügter Gießform (3-4) von außen elektro-induktiv ausgeheizt werden,4. The method according to claim 1 and 3, characterized in that the components (7) are completely electro-inductively heated from the outside when the casting mold (3-4) is fully assembled,
5. Verfahren nach Anspruch 4, dadurch gekennzeichnet, daß der Formhohlraum (14) der Gießform (3-4) vor Beginn des Aufheizens mit einem Schutzgas gespült wird.5. The method according to claim 4, characterized in that the mold cavity (14) of the casting mold (3-4) is flushed with a protective gas before the start of heating.
6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß der Abguß noch vor Beendigung der Aufheizphase beginnt. 6. The method according to any one of claims 1 to 5, characterized in that the casting begins before the end of the heating phase.
EP92907886A 1991-04-10 1992-04-03 Process for casting an aluminium-alloy engine part, in particular a cylinder head Expired - Lifetime EP0578705B1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE4111676 1991-04-10
DE4111676A DE4111676A1 (en) 1991-04-10 1991-04-10 METHOD FOR CASTING AN ALUMINUM ALLOY ENGINE BLOCK
PCT/EP1992/000747 WO1992018269A1 (en) 1991-04-10 1992-04-03 Process for casting an aluminium-alloy engine part, in particular a cylinder head

Publications (2)

Publication Number Publication Date
EP0578705A1 true EP0578705A1 (en) 1994-01-19
EP0578705B1 EP0578705B1 (en) 1995-01-25

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JP (1) JPH07500291A (en)
AT (1) ATE117607T1 (en)
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WO (1) WO1992018269A1 (en)

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DE19612500A1 (en) * 1996-03-29 1997-10-02 Bleistahl Prod Gmbh & Co Kg Process for the production of cylinder heads for internal combustion engines
DE19703399A1 (en) * 1997-01-30 1998-08-06 Itt Mfg Enterprises Inc Method for producing a housing block for a hydraulic unit
DE19746167A1 (en) * 1997-10-18 1999-04-22 Volkswagen Ag Cast light metal component with insert incorporated during casting
DE19852595A1 (en) * 1998-11-14 2000-05-18 Georg Fischer Disa Ag Process and plant for the production of castings from aluminum with inlays
DE10211053A1 (en) * 2002-03-13 2003-10-09 Vaw Ver Aluminium Werke Ag Process for casting cylinder crankcases and core package for casting cylinder crankcases, core box and core package

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Publication number Priority date Publication date Assignee Title
CH251502A (en) * 1944-03-18 1947-10-31 Mecanique Du Centre Societe An A method of manufacturing a light alloy engine cylinder head, and an engine cylinder head obtained by this method.
FR1238335A (en) * 1959-06-29 1960-08-12 Hispano Suiza Sa Improvements made to light metal parts, in particular engine cylinder heads, which must contain metal inclusions, and to the processes for their production
JPS57115964A (en) * 1981-01-08 1982-07-19 Kubota Ltd Insert casting method for steel core
US4691754A (en) * 1985-12-31 1987-09-08 Deere & Company Method for forming castings having inserts
JPS6415262A (en) * 1987-07-09 1989-01-19 Nissan Motor Method for casting cylinder block inserting cylinder liner as cast-in

Non-Patent Citations (1)

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Title
See references of WO9218269A1 *

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DE59201300D1 (en) 1995-03-09
EP0578705B1 (en) 1995-01-25
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ATE117607T1 (en) 1995-02-15
JPH07500291A (en) 1995-01-12
DE4111676A1 (en) 1992-10-15

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