EP1319453B1 - Apparatus and method for filling hollow profiles with a metal foam - Google Patents

Apparatus and method for filling hollow profiles with a metal foam Download PDF

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Publication number
EP1319453B1
EP1319453B1 EP02027181A EP02027181A EP1319453B1 EP 1319453 B1 EP1319453 B1 EP 1319453B1 EP 02027181 A EP02027181 A EP 02027181A EP 02027181 A EP02027181 A EP 02027181A EP 1319453 B1 EP1319453 B1 EP 1319453B1
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EP
European Patent Office
Prior art keywords
hollow profile
filling
metal foam
hollow
induction means
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.)
Expired - Fee Related
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EP02027181A
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German (de)
French (fr)
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EP1319453A1 (en
Inventor
Eric Keetman
Karl-Heinz Süss
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Airbus Defence and Space GmbH
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EADS Deutschland GmbH
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Publication of EP1319453A1 publication Critical patent/EP1319453A1/en
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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00—Heating by electric, magnetic or electromagnetic fields
    • H05B6/02—Induction heating
    • H05B6/10—Induction heating apparatus, other than furnaces, for specific applications
    • H05B6/105—Induction heating apparatus, other than furnaces, for specific applications using a susceptor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/11—Making porous workpieces or articles
    • B22F3/1121—Making porous workpieces or articles by using decomposable, meltable or sublimatable fillers
    • B22F3/1125—Making porous workpieces or articles by using decomposable, meltable or sublimatable fillers involving a foaming process
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
    • B22F7/002—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of porous nature
    • B22F7/004—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of porous nature comprising at least one non-porous part
    • B22F7/006—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of porous nature comprising at least one non-porous part the porous part being obtained by foaming
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/10—Sintering only
    • B22F3/105—Sintering only by using electric current other than for infrared radiant energy, laser radiation or plasma ; by ultrasonic bonding
    • B22F2003/1053—Sintering only by using electric current other than for infrared radiant energy, laser radiation or plasma ; by ultrasonic bonding by induction
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

  • the present invention relates to an arrangement and a method for in-situ foaming of hollow profiles with metal foam, according to claim 1 or 11.
  • profiles foamed with metal foam offer application potential in particular for lightweight construction applications in the automotive industry and in aerospace engineering.
  • the metal foam serves as an insulating material and for increasing the rigidity and as a shock absorber, for example. in crash structures.
  • DE 198 34 394 A1 describes an apparatus and a method for the production of metal foam, in which or in which the foam is applied directly during foam formation.
  • the foamable raw material is foamed in a so-called foaming cell.
  • the metal foam is produced directly at the point of its processing under defined boundary conditions, eg. regardless of the shape of navalCumenden profile, and is introduced without major transport routes in the profile.
  • the foaming cell may be attached to the top of a rod-like Shuumlanze.
  • the heating of the ausferumbaren raw material using conventional heat sources, such as gas burners, electrical resistance heating, induction coils, electron beam and laser sources.
  • conventional heat sources such as gas burners, electrical resistance heating, induction coils, electron beam and laser sources.
  • the document DE 199 28 997 C2 describes foaming raw material by irradiation with a laser or an electron beam.
  • the heat input is concentrated on the raw material furFiumende without a profile surrounding the raw material is heated significantly.
  • damage to the hollow profile is avoided.
  • the disadvantage is that the method is essentially limited to the applications in which profile material and Schaummateriel are different. With a combination of similar materials, such as aluminum profile and aluminum foam, it comes to problems due to the required process temperature, which is above the melting temperature of the foam material.
  • the present invention has the object to provide an arrangement or a method for in-situ foaming of hollow profiles with metal foam, which allows a partial foaming of hollow sections, if necessary with undercuts, especially if hollow section and metal foam consist of similar materials.
  • the arrangement or the method should be easy to use.
  • the central idea here is that the hollow profile itself, due to the contact with the induction means, forms part of the induction means. This is possible because, furthermore, in the hollow profile in its longitudinal direction extending an electrical interruption is arranged so that a short circuit of the induction means is effectively prevented. This means at the same time that the electrical interruption extends over the entire longitudinal direction in any manner. Due to this configuration, the hollow profile for "quasi-inductor", which undergoes only slight warming during inductive heating of the raw material itself and positively influenced the formation of the magnetic field.
  • the arrangement according to the invention has the advantage that the metal foam is produced directly at the point where it is ultimately needed. This ensures a very effective foaming, since no further or introduction of the metal foam is required. This eliminates introduction difficulties. Further, it is advantageous that also undercuts are filled with foam inside a hollow profile reliably, since due to the all-round heating of the raw material, a uniform expansion of the foaming raw material is achieved.
  • the foam density can be varied via the process parameters. Of course, the process parameters can also be varied during the foaming process so that the hollow profile is filled with a gradient material. Another advantage is that only a few components (induction means, hollow profile and raw material) are required, so that a simple arrangement is realized with low process costs.
  • the induction agent coolable.
  • This is realized for example by a cooling water circuit arranged within the induction means.
  • This has the advantage that the hollow profile is also co-cooled due to its contacting of the induction means, which in particular during a foaming of the hollow profile with similar Foam material is advantageous because in this way the temperature of the hollow profile is kept below the melting temperature of the raw material.
  • the shape of the induction means substantially corresponds to the shape of the hollow profile. This ensures a uniform contact over the entire circumference of the hollow profile, which causes a uniform foaming and thus has a positive effect on the AusSum characterizing.
  • the required for inductive heating of the raw material magnetic field is optimally adapted to the circumstances. It is particularly advantageous to form-adapt the induction means, which adapts automatically, flexibly to the shape of the hollow profile.
  • the hollow profile has a circular, oval, rectangular or any other desired cross-section.
  • a flexible application is guaranteed.
  • the electrical interruption is particularly useful to form the electrical interruption as a slot. This provides a reliable electrical interruption to avoid a short circuit of the inductor and is also technically easy to implement.
  • the electrical interruption is an electrically non-conductive material which is integrated in the wall of the hollow profile or is introduced into a slot disposed therein.
  • induction means and hollow profile are arranged displaceable relative to each other.
  • induction means and hollow profile are arranged displaceable relative to each other.
  • the device is mobile, which in particular simplifies the use in series production and repairs locally possible.
  • a method which according to the invention is characterized in that a researcher2020endes hollow profile is introduced into an induction means or enclosed by the induction means, so that the hollow profile touches the induction means at least at one point; wherein the hollow profile has an electrical interruption extending in its longitudinal direction; that a foamable raw material is disposed within the hollow profile; and that the raw material is foamed, wherein the hollow profile forms part of the induction means
  • Such a method has the advantage that the foaming process takes place where it is needed. This eliminates difficulties that occur in known methods when introducing the foamed metal into a hollow profile.
  • profiles can be filled discontinuously, continuously or partially, without undercuts or other asymmetries of the profile impede the foaming process. Due to the fact that the hollow profile forms part of the induction means, and thus is not or only slightly heated, a foaming of hollow profiles with foam of similar material as the hollow profile is possible.
  • Aluminum profiles are easily foamed with aluminum foam.
  • the electrical interruption is introduced into the hollow profile before it is introduced into the induction means.
  • the electrical interruption is introduced by cutting the hollow profile in the longitudinal direction, so that a slot is formed. This constitutes one Such a slot can be made very narrow, so that the flexural rigidity of the hollow profile is hardly or only marginally affected.
  • the slot is filled with an insulating material. This is particularly advantageous if the outer contour of the hollow profile to be maintained or the hollow profile is to be given additional stability.
  • a raw material consisting of a mixture of different materials may also be used so that the foamed metal foam has a composite structure.
  • the process parameters can be changed during the foaming of the raw material, so that the hollow profile is foamed with a metal foam having a gradient structure.
  • foams having desired structures and properties can be easily produced.
  • the induction means and the hollow profile disposed therein in the longitudinal direction relative to each other.
  • either the hollow profile can be moved within the induction means, or the induction means with respect to a fixed hollow profiles.
  • the method according to the invention can be adapted to the given circumstances.
  • the method according to the invention can be used mobile. This allows the process to be easily integrated into existing production processes. It eliminates e.g. a supply of appropriately foamed components, which facilitates the production process and lowers production costs.
  • the method is used for producing a semi-finished product for crash structures in automotive engineering and in the aerospace industry, in particular for weight-specific increase in rigidity and crash resistance.
  • FIG. 1 shows a sectional view in the longitudinal direction (arrow direction A) of a hollow profile 2 to be foamed, which is introduced into an induction means 1.
  • the induction means may be formed as an induction coil or loop, to name just a few examples.
  • a foamable raw material 3 consisting of a known compacted mixture of metal powder (e.g., aluminum, magnesium or zinc powder) and propellant powder. The compacting is optionally followed by an extrusion process.
  • the raw material 3 is in a rod-shaped form. But it can also be used tablet or granular raw material. Under tablet-shaped raw material are, for example. to understand pressed beads. Further, a mixture of different raw materials may be used, e.g.
  • the hollow profile 2 in Fig. 1 is tubular and consists of aluminum, magnesium, steel or the like. In addition, however, differently shaped hollow profiles can be used, for example, have an oval, rectangular or other suitable cross-section. In addition, the hollow profile 2 may have not shown undercuts.
  • the hollow profile 2 is arranged inside the induction means 1, wherein it touches the induction means 1 at least at one point. In the one shown in Fig.1 In the preferred embodiment, the contact extends along the entire inner surface of the induction means 1 in order to bring about as homogeneous and uniform foaming as possible.
  • the shape of the induction means 1 is thus ideally adapted to that of the hollow profile 2.
  • an induction means 1 is used which has a circular inner cross-section.
  • an appropriately rectangular induction means is used.
  • a conformable induction means can be used, which consists of a plurality of individual, movable elements that automatically adapt to the shape of the hollow profile.
  • the induction means can be formed hinged, which facilitates handling when enclosing the hollow profile.
  • the induction means 1 is preferably designed to be coolable.
  • cooling channels 1a are arranged in the induction means 1 through which, for example, cooling water is passed.
  • Such an arrangement of cooling channels is also possible with the shape-adaptable or chain-shaped induction means.
  • the flow through the induction means 1 with cooling water simultaneously causes cooling of the hollow profile 2. The cooling is better, the closer or better the contact between the hollow profile 2 and the induction means 1 is.
  • the hollow profile 2 is provided a substantially along the longitudinal direction A extending electrical interruption 4 (see Fig. 2). Due to the contacting of the hollow profile 2 and the induction means 1 there is an electrically conductive connection between these two components, which without interruption 4 would lead to a short circuit of the induction means 1. In the case of a short circuit, therefore, no magnetic field would form to heat the raw material.
  • the electrical interruption 4 is formed in FIG. 2 as a slot.
  • the electrical interruption 4 may consist of an electrically non-conductive material which is integrated in the wall of the hollow profile 2.
  • a slit-shaped electrical break 4 may also be filled with a suitable insulating material (e.g., mica) to improve the strength properties, if necessary.
  • the introduction of the slot is preferably effected before foaming and before arranging the hollow section 2 in the induction means 1 by cutting the hollow section 2 in the longitudinal direction A.
  • the slot can be straight, oblique or in any other desired form (for example, L-shaped, U-shaped, Z-shaped, etc.) introduced into the wall of the hollow profile.
  • this processing step is omitted from the outset.
  • the induction means 1 is supplied by an HF source 5 and during operation forms a magnetic field, whereby the arranged inside the hollow profile 2 raw material 3 is heated inductively and foams. Due to the conductive contact between the induction means 1 and the hollow profile 2, the hollow profile 2 is quasi part of the induction means 1 and the magnetic field forming due to the current flow has substantially in the longitudinal direction A.
  • the concentration of the magnetic field in the center of the induction means 1, ie where the raw material 3 is arranged the largest.
  • the hollow profile 2 heats up during operation hardly or only to temperatures up to about 100 ° C, so that the profile properties are maintained. The low heating of the hollow profile 2 is also supported by the cooling effect described above.
  • the hollow profile 2 is homogeneously, partially foamed, wherein the metal foam is formed at the point where it is actually needed.
  • One further transport step is not required.
  • the foaming of undercuts, which are arranged within the hollow profile, due to the symmetrical arrangement and the all-round heating of the raw material is unproblematic.
  • the hollow section 2 can also be filled with foam continuously.
  • the inner wall of the hollow section 2 is coated with an insulating material (for example stove enamel) before foaming.
  • the insulating material prevents a short circuit on the electrical interruption 4 when the interior of the hollow section 2 fills with metal foam and thereby rests against the inner wall of the hollow section 2 instead. If the insulating material-lined hollow profile 2 is moved relative to the induction means 1 in the longitudinal direction A, a continuous foaming of the hollow section 2 is possible. It is irrelevant whether the induction means 1 is moved relative to the hollow profile 2, or vice versa. Regardless, the metal foam is again generated where it is needed.
  • foamed hollow section 2 can be closed by welding again.
  • the invention is mobile due to the simple structure, especially for use in automated manufacturing. Furthermore, foamed hollow profile semi-finished products can be produced with the invention described above, which are used, for example, as crash structures in vehicle technology and in aerospace engineering.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Composite Materials (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Casting Or Compression Moulding Of Plastics Or The Like (AREA)
  • Laminated Bodies (AREA)

Description

Die vorliegende Erfindung betrifft eine Anordnung sowie ein Verfahren zum in-situ Ausschäumen von Hohlprofilen mit Metalischaum, gemäß Patentanspruch 1 bzw. 11.The present invention relates to an arrangement and a method for in-situ foaming of hollow profiles with metal foam, according to claim 1 or 11.

Es ist bekannt, dass mit Metalischaum ausgeschäumte Profile insbesondere für Leichtbauanwendungen in der Automobilindustrie sowie in der Luft- und Raumfahrttechnik Anwendungspotential bieten. Der Metallschaum dient dabei als Dämmmaterial sowie zur Steifigkeitserhöhung und als Stoßabsorber z.B. in Crashstrukturen.It is known that profiles foamed with metal foam offer application potential in particular for lightweight construction applications in the automotive industry and in aerospace engineering. The metal foam serves as an insulating material and for increasing the rigidity and as a shock absorber, for example. in crash structures.

Es sind verschiedene Vorrichtungen und Verfahren bekannt, mit denen derartige ausgeschäumte Strukturen erzeugt werden. Die Druckschriften DE 197 44 300 A1 und EP 0 804 982 A2 beschreiben zum Beispiel Anordnungen, bei denen das Aufschäumen eines Rohmaterials in einer Vorkammer durchgeführt wird. Der in der Vorkammer erzeugte Metallschaum hat eine fließfähige, flexible Konsistenz und wird durch geeignete Austrittsöffnungen in gewünschte auszuschäumende Profile eingebracht und dort zum Erstarren gebracht. Folglich wird bei einem derartigen Verfahren der Metallschaum an einer anderen Stelle aufgeschäumt, als er letztendlich benötigt wird. Es ist somit ein separater Transportschritt notwendig. Dies erfordert einen hohen technischen Aufwand, da Schaumbildung und Einbringung getrennt überwacht und koordiniert werden müssen. Des weiteren ist ein Ausschäumen von Profilen mit gleichartigem Schaummaterial (z.B. das Ausschäumen von Aluminiumprofilen mit Aluminiumschaum) sehr schwierig, da aufgrund der hohen Wärmeleitfähigkeit des auszuschäumenden Profils der Schaum beim Einbringen sehr schnell abkühlt und erstarrt. Dies bringt den Nachteil mit sich, dass Profile mit Hinterschneidungen vor dem Ausschäumen erst erwärmt werden müssen. Die dafür nötige Temperatur liegt jedoch im Bereich der Fließtemperatur des Schaumes und wirkt sich somit negativ auf die Profileigenschaften aus.Various devices and methods are known with which such foamed structures are produced. The documents DE 197 44 300 A1 and EP 0 804 982 A2, for example, describe arrangements in which the foaming of a raw material is carried out in an antechamber. The metal foam produced in the pre-chamber has a flowable, flexible consistency and is introduced through suitable outlet openings in desired Auszuschäumende profiles and there solidified. Consequently, in such a process, the metal foam is foamed at a different location than it is ultimately needed. It is thus necessary a separate transport step. This requires a high technical effort, since foaming and introduction must be separately monitored and coordinated. Furthermore, foaming of profiles with similar foam material (eg the foaming of aluminum profiles with aluminum foam) is very difficult because due to the high thermal conductivity of the auszuschäumenden profile of the foam cools very quickly during introduction and solidifies. This brings the Disadvantage with that profiles with undercuts must first be heated before foaming. However, the temperature required for this is in the range of the flow temperature of the foam and thus has a negative effect on the profile properties.

Des weiteren ist in der DE 198 34 394 A1 eine Vorrichtung und ein Verfahren zur Herstellung von Metallschaum beschrieben, bei der bzw. bei dem der Schaum unmittelbar während der Schaumentstehung aufgebracht wird. Zu diesem Zweck wird das aufschäumbare Rohmaterial in einer sogenannten Schäumzelle aufgeschäumt. Der Metalischaum wird direkt an der Stelle seiner Verarbeitung unter definierten Randbedingungen erzeugt, also zB. unabhängig von der Gestalt des auszuschäumenden Profils, und wird ohne größere Transportwege in das Profil eingebracht. Um an sehr unzugängliche Stellen im Inneren des auszuschäumenden Profils zu gelangen, kann die Schäumzelle an der Spitze einer stabartigen Schäumlanze angebracht sein. Die Erwärmung des ausschäumbaren Rohmaterials erfolgt mit Hilfe von üblichen Wärmequellen, wie Gasbrenner, elektrische Widerstandsheizung, induktionsspulen, Elektronenstrahl- und Laserquellen. Hierbei besteht jedoch weiterhin das Problem, Profile mit Hinterschneidungen homogen auszuschäumen, da der Schaum während des Fließens abkühlt. Dieses Problem tritt wiederum insbesondere dann auf, wenn Profile mit gleichartigem Schaummaterial ausgeschäumt werden sollen.Furthermore, DE 198 34 394 A1 describes an apparatus and a method for the production of metal foam, in which or in which the foam is applied directly during foam formation. For this purpose, the foamable raw material is foamed in a so-called foaming cell. The metal foam is produced directly at the point of its processing under defined boundary conditions, eg. regardless of the shape of auszuschäumenden profile, and is introduced without major transport routes in the profile. In order to reach very inaccessible places in the interior of the auszuschäumenden profile, the foaming cell may be attached to the top of a rod-like Schäumlanze. The heating of the ausschäumbaren raw material using conventional heat sources, such as gas burners, electrical resistance heating, induction coils, electron beam and laser sources. Here, however, there is still the problem of foaming profiles with undercuts homogeneous, since the foam cools during flow. This problem again occurs in particular when profiles with similar foam material are to be foamed.

Ferner beschreibt die Druckschrift DE 199 28 997 C2, Rohmaterial durch Bestrahlen mit einem Laser oder einem Elektronenstrahl aufzuschäumen. Dabei wird der Wärmeeintrag auf das auszuschäumende Rohmaterial konzentriert, ohne dass ein das Rohmaterial umgebendes Profil signifikant erwärmt wird. Dadurch wird eine Beschädigung des Hohlprofils vermieden. Ferner ist es vorteilhaft, dass der Schäumvorgang dort stattfindet, wo das aufgeschäumte Material benötigt wird, so dass eine flexible und im wesentlichen formunabhängige Herstellung des Metallschaumes gewährleistet ist. Nachteilig ist jedoch, dass das Verfahren im wesentlichen auf die Anwendungsfälle beschränkt ist, bei denen Profilmaterial und Schaummateriel unterschiedlich sind. Bei einer Kombination gleichartiger Materialien, z.B. Aluminiumprofil und Aluminiumschaum, kommt es aufgrund der erforderlichen Prozesstemperatur, die oberhalb der Schmelztemperatur des Schaummaterials liegt, zu Problemen. Ferner ist beim Erhitzen des aufzuschäumenden Rohmaterials mittels Laser zu Beachten, dass Sichtkontakt zum Rohmaterial besteht. Werden aufeinanderliegende Schichten aufgeschäumt, so ist dies nur sukzessiv möglich und eine geeignete Zufühnrng des Rohmaterials ist erforderlich, was in der Regel technisch problematisch ist.Furthermore, the document DE 199 28 997 C2 describes foaming raw material by irradiation with a laser or an electron beam. In this case, the heat input is concentrated on the raw material auszuschäumende without a profile surrounding the raw material is heated significantly. As a result, damage to the hollow profile is avoided. Furthermore, it is advantageous that the foaming process takes place where the foamed material is needed, so that a flexible and substantially independent of the production of the mold Metal foam is guaranteed. The disadvantage, however, is that the method is essentially limited to the applications in which profile material and Schaummateriel are different. With a combination of similar materials, such as aluminum profile and aluminum foam, it comes to problems due to the required process temperature, which is above the melting temperature of the foam material. Further, when heating the foaming raw material by laser, it is to be noted that visual contact with the raw material exists. If superimposed layers are foamed, this is only successively possible and a suitable Zufährng of the raw material is required, which is technically problematic in the rule.

Somit liegt der vorliegenden Erfindung die Aufgabe zugrunde, eine Anordnung bzw. ein Verfahren zum in-situ Ausschäumen von Hohlprofilen mit Metalischaum zu schaffen, die bzw. das ein partielles Ausschäumen von Hohlprofilen ggf. mit Hinterschneidungen ermöglicht, insbesondere auch dann, wenn Hohlprofil und Metallschaum aus gleichartigen Materialien bestehen. Dabei soll die Anordnung bzw. das Verfahren einfach anwendbar sein.Thus, the present invention has the object to provide an arrangement or a method for in-situ foaming of hollow profiles with metal foam, which allows a partial foaming of hollow sections, if necessary with undercuts, especially if hollow section and metal foam consist of similar materials. In this case, the arrangement or the method should be easy to use.

Die Aufgabe wird erfindungsgemäß durch eine Anordnung gemäß Anspruch 1 gelöst,The object is achieved by an arrangement according to claim 1,

Zentraler Gedanke hierbei ist, dass das Hohlprofil selbst, aufgrund der Kontaktierung mit dem Induktionsmittel, einen Teil des Induktionsmittels darstellt. Dies ist dadurch möglich, dass ferner in dem Hohlprofil in dessen Längsrichtung verlaufend eine elektrische Unterbrechung angeordnet ist, so dass ein Kurzschluss des Induktionsmittels wirkungsvoll verhindert wird. Dies bedeutet gleichzeitig, dass sich die elektrische Unterbrechung über die gesamte Längsrichtung in beliebiger Art und Weise erstreckt. Aufgrund dieser Ausgestaltung wird das Hohlprofil zum "Quasi-Induktor", der beim induktiven Erwärmen des Rohmaterials selber nur geringe Erwärmung erfährt und die Ausbildung des Magnetfeldes positiv beeinflusst.The central idea here is that the hollow profile itself, due to the contact with the induction means, forms part of the induction means. This is possible because, furthermore, in the hollow profile in its longitudinal direction extending an electrical interruption is arranged so that a short circuit of the induction means is effectively prevented. This means at the same time that the electrical interruption extends over the entire longitudinal direction in any manner. Due to this configuration, the hollow profile for "quasi-inductor", which undergoes only slight warming during inductive heating of the raw material itself and positively influenced the formation of the magnetic field.

Die erfindungsgemäße Anordung hat den Vorteil, dass der Metallschaum direkt an der Stelle erzeugt wird, an der er letztendlich benötigt wird. Dadurch ist ein sehr effektives Ausschäumen gewährleistet, da kein Weiter- bzw. Einleiten des Metallschaumes erforderlich ist. Damit entfallen Einbringungsschwierigkeiten. Ferner ist es vorteilhaft, dass auch Hinterschneidungen im Inneren eines Hohlprofils zuverlässig ausgeschäumt werden, da aufgrund der allseitigen Erwärmung des Rohmaterials eine gleichmäßig Ausdehnung des aufschäumenden Rohmaterials erzielt wird. Dabei kann die Schaumdichte über die Prozessparameter variiert werden. Die Prozessparameter können selbstverständlich auch während des Aufschäumprozesses variiert werden, so dass das Hohlprofil mit einem Gradientenwerkstoff gefüllt wird. Ein weiterer Vorteil besteht darin, dass lediglich wenig Bauteile (Induktionsmittel, Hohlprofil sowie Rohmaterial) erforderlich sind, so dass eine einfache Anordnung mit geringen Prozesskosten realisiert ist.The arrangement according to the invention has the advantage that the metal foam is produced directly at the point where it is ultimately needed. This ensures a very effective foaming, since no further or introduction of the metal foam is required. This eliminates introduction difficulties. Further, it is advantageous that also undercuts are filled with foam inside a hollow profile reliably, since due to the all-round heating of the raw material, a uniform expansion of the foaming raw material is achieved. The foam density can be varied via the process parameters. Of course, the process parameters can also be varied during the foaming process so that the hollow profile is filled with a gradient material. Another advantage is that only a few components (induction means, hollow profile and raw material) are required, so that a simple arrangement is realized with low process costs.

Es ist zweckmäßig, das Induktionsmittel kühlbar auszubilden. Dies wird beispielsweise durch einen innerhalb des Induktionsmittels angeordneten Kühlwasserkreislauf realisiert. Dies hat den Vorteil, dass das Hohlprofil aufgrund seiner Kontaktierung des Induktionsmittels gleichzeitig mitgekühlt wird, was insbesondere bei einem Ausschäumen des Hohlprofils mit gleichartigem Schaummaterial vorteilhaft ist, da auf diese Weise die Temperatur des Hohlprofils unterhalb der Schmelztemperatur des Rohmaterials gehalten wird .It is expedient to form the induction agent coolable. This is realized for example by a cooling water circuit arranged within the induction means. This has the advantage that the hollow profile is also co-cooled due to its contacting of the induction means, which in particular during a foaming of the hollow profile with similar Foam material is advantageous because in this way the temperature of the hollow profile is kept below the melting temperature of the raw material.

Vorteilhafterweise entspricht die Form des Induktionsmittels im wesentlichen der Form des Hohlprofils. Dadurch wird eine gleichmäßige Kontaktierung über den gesamten Umfang des Hohlprofils gewährleistet, was ein gleichmäßiges Ausschäumen bewirkt und sich folglich positiv auf die Ausschäumcharakteristik auswirkt. Zudem wird dadurch das zur induktiven Erwärmung des Rohmaterials erforderliche Magnetfeld an die Gegebenheiten optimal angepasst. Dabei ist es besonders vorteilhaft, das Induktionsmittel formanpassbar auszugestalten, das sich automatisch, flexibel an die Form des Hohlprofils anpasst.Advantageously, the shape of the induction means substantially corresponds to the shape of the hollow profile. This ensures a uniform contact over the entire circumference of the hollow profile, which causes a uniform foaming and thus has a positive effect on the Ausschäumcharakteristik. In addition, the required for inductive heating of the raw material magnetic field is optimally adapted to the circumstances. It is particularly advantageous to form-adapt the induction means, which adapts automatically, flexibly to the shape of the hollow profile.

Ferner ist es zweckmäßig, dass das Hohlprofil einen kreisförmigen, ovalen, rechteckigen oder einen anderen beliebigen Querschnitt aufweist. Somit ist eine flexible Anwendung gewährleistet.Furthermore, it is expedient that the hollow profile has a circular, oval, rectangular or any other desired cross-section. Thus, a flexible application is guaranteed.

Besonders zweckmäßig ist es, die elektrische Unterbrechung als Schlitz auszubilden. Dies gewährt eine zuverlässige elektrische Unterbrechung zur Vermeidung eines Kurzschlusses des Induktionsmittels und ist zudem technisch einfach realisierbar.It is particularly useful to form the electrical interruption as a slot. This provides a reliable electrical interruption to avoid a short circuit of the inductor and is also technically easy to implement.

Gemäß einer alternativen Ausführung ist die elektrische Unterbrechung ein elektrisch nicht leitendes Material, das in die Wand des Hohlprofils integriert ist oder in einen darin angeordneten Schlitz eingebracht ist.According to an alternative embodiment, the electrical interruption is an electrically non-conductive material which is integrated in the wall of the hollow profile or is introduced into a slot disposed therein.

Ferner ist es besonders vorteilhaft, dass Induktionsmittel und Hohlprofil relativ zueinander verschiebbar angeordnet sind. Somit ist nicht nur ein partielles sondern auch ein kontinuierliches Ausschäumen von Hohlprofilen auf einfache Weise möglich.Furthermore, it is particularly advantageous that induction means and hollow profile are arranged displaceable relative to each other. Thus, not only a partial but also a continuous foaming of hollow sections in a simple manner possible.

Daneben ist es von Vorteil, dass die Vorrichtung mobil einsetzbar ist, was insbesondere den Einsatz in der Serienherstellung vereinfacht sowie Reparaturen lokal vor Ort ermöglicht.In addition, it is advantageous that the device is mobile, which in particular simplifies the use in series production and repairs locally possible.

Die Aufgabe wird ferner durch ein Verfahren gelöst, das sich erfindungsgemäß dadurch auszeichnet, dass ein auszuschäumendes Hohlprofil in ein Induktionsmittel eingeführt bzw. von dem Induktionsmittel umschlossen wird, so dass das Hohlprofil das Induktionsmittel wenigstens an einer Stelle berührt; wobei das Hohlprofil eine in dessen Längsrichtung verlaufende elektrische Unterbrechung aufweist; dass ein aufschäumbares Rohmaterial innerhalb des Hohlprofils angeordnet wird; und dass das Rohmaterial aufgeschäumt wird, wobei das Hohlprofil einen Teil des Induktionsmittels bildetThe object is further achieved by a method which according to the invention is characterized in that a auszuschäumendes hollow profile is introduced into an induction means or enclosed by the induction means, so that the hollow profile touches the induction means at least at one point; wherein the hollow profile has an electrical interruption extending in its longitudinal direction; that a foamable raw material is disposed within the hollow profile; and that the raw material is foamed, wherein the hollow profile forms part of the induction means

Ein derartiges Verfahren hat den Vorteil, dass der Schäumprozess dort stattfindet, wo er benötigt wird. Damit entfallen Schwierigkeiten, die bei bekannten Verfahren beim Einbringen des aufgeschäumten Metalls in ein Hohlprofil auftreten. Dabei können Profile diskontinuierlich, kontinuierlich oder partiell ausgeschäumt werden, ohne dass Hinterschneidungen oder andere Asymmetrien des Profils den Ausschäumvorgang behindern. Aufgrund der Tatsache, dass das Hohlprofil einen Teil des Induktionsmittels bildet, und somit nicht oder nur gering erwärmt wird, ist ein Ausschäumen von Hohlprofilen mit Schaum aus ähnlichem Material wie das Hohlprofil möglich. Somit können z.B. Aluminiumprofile ohne weiteres mit Aluminiumschaum ausgeschäumt werden.Such a method has the advantage that the foaming process takes place where it is needed. This eliminates difficulties that occur in known methods when introducing the foamed metal into a hollow profile. In this case, profiles can be filled discontinuously, continuously or partially, without undercuts or other asymmetries of the profile impede the foaming process. Due to the fact that the hollow profile forms part of the induction means, and thus is not or only slightly heated, a foaming of hollow profiles with foam of similar material as the hollow profile is possible. Thus, e.g. Aluminum profiles are easily foamed with aluminum foam.

Es ist zweckmäßig, dass die elektrische Unterbrechung in das Hohlprofil eingebracht wird, bevor es in das Induktionsmittel eingeführt wird. Vorzugsweise wird die elektrische Unterbrechung dabei durch Aufschneiden des Hohlprofils in dessen Längsrichtung eingebracht, so dass ein Schlitz entsteht. Dies stellt eine besonders einfache Vorgehensweise dar. Ein derartiger Schlitz kann sehr schmal ausgebildet werden, so dass die Biegesteifigkeit des Hohlprofils kaum oder nur marginal beeinflusst wird.It is expedient that the electrical interruption is introduced into the hollow profile before it is introduced into the induction means. Preferably, the electrical interruption is introduced by cutting the hollow profile in the longitudinal direction, so that a slot is formed. This constitutes one Such a slot can be made very narrow, so that the flexural rigidity of the hollow profile is hardly or only marginally affected.

Gemäß einer alternativen Ausführungsform wird der Schlitz mit einem Isolierstoff aufgefüllt. Dies ist insbesondere dann vorteilhaft, wenn die Außenkontur des Hohlprofiles aufrechterhalten werden soll oder dem Hohlprofil zusätzlich Stabilität verliehen werden soll.According to an alternative embodiment, the slot is filled with an insulating material. This is particularly advantageous if the outer contour of the hollow profile to be maintained or the hollow profile is to be given additional stability.

Vorteilhafterweise kann auch ein Rohmaterial verwendet werden, das aus einem Gemisch unterschiedlicher Materialien besteht, so dass der aufgeschäumte Metalischaum eine Verbundstruktur aufweist.Advantageously, a raw material consisting of a mixture of different materials may also be used so that the foamed metal foam has a composite structure.

Daneben ist es zudem von Vorteil, dass die Prozessparameter während dem Aufschäumen des Rohmaterials geändert werden können, so dass das Hohlprofil mit einem Metallschaum ausgeschäumt wird, der eine Gradientenstruktur aufweist. Somit können auf einfache Weise Schäume mit gewünschten Strukturen und Eigenschaften leicht erzeugt werden.In addition, it is also advantageous that the process parameters can be changed during the foaming of the raw material, so that the hollow profile is foamed with a metal foam having a gradient structure. Thus, foams having desired structures and properties can be easily produced.

Ferner ist es vorteilhaft, die Innenwand des Hohlprofils vor dem Ausschäumen mit einer Isolierschicht zu versehen. Dieser Verfahrensschritt ist insbesondere dann zweckmäßig, wenn das Hohlprofil kontinuierlich ausgeschäumt werden soll, um somit einen Kurzschluss über die elektrische Unterbrechung aufgrund des in dem Hohlprofil sich ausbreitenden Metallschaumes zu verhindern.Furthermore, it is advantageous to provide the inner wall of the hollow profile before foaming with an insulating layer. This method step is particularly useful when the hollow profile is to be foamed continuously, so as to prevent a short circuit on the electrical interruption due to the propagating in the hollow profile metal foam.

Bei einem derartigen kontinuierlichen Ausschäumen ist es von Vorteil, das Induktionsmittel sowie das darin angeordnete Hohlprofil in Längsrichtung relativ zueinander zu bewegen. Dabei kann entweder das Hohlprofil innerhalb des Induktionsmittels verschoben werden, oder das Induktionsmittel bezüglich eines fest angeordneten Hohlprofils. Damit ist das erfindungsgemäße Verfahren an die gegebenen Umstände anpassbar.In such a continuous foaming, it is advantageous to move the induction means and the hollow profile disposed therein in the longitudinal direction relative to each other. In this case, either the hollow profile can be moved within the induction means, or the induction means with respect to a fixed hollow profiles. Thus, the method according to the invention can be adapted to the given circumstances.

Ferner ist es bei manchen Anordnungen zweckmäßig, den Schlitz nach dem Ausschäumen des Hohlprofils durch Schweißen wieder zu verschließen. Dies stellt einen einfachen Arbeitsschritt dar, der ohne weiteres in bestehende Verfahrensabläufe bzw. Anordnungen integriert werden kann.Furthermore, it is expedient in some arrangements to close the slot again after welding of the hollow profile by welding. This represents a simple step, which can be easily integrated into existing procedures or arrangements.

Besonders vorteilhaft ist es, dass das erfindungsgemäße Verfahren mobil eingesetzt werden kann. Dadurch kann das Verfahren einfach in bestehende Produktionsabläufe integriert werden. Es entfällt z.B. ein Zuliefem von entsprechend ausgeschäumten Bauteilen, was den Herstellungsprozess erleichtert und die Produktionskosten senkt.It is particularly advantageous that the method according to the invention can be used mobile. This allows the process to be easily integrated into existing production processes. It eliminates e.g. a supply of appropriately foamed components, which facilitates the production process and lowers production costs.

Das Verfahren wird zur Herstellung eines Halbzeuges für Crashstrukturen in der Kraftfahrzeugtechnik sowie in der Luft- und Raumfahrt verwendet, insbesondere zur gewichtsspezifischen Erhöhung der Steifigkeit und Crashbeständigkeit.The method is used for producing a semi-finished product for crash structures in automotive engineering and in the aerospace industry, in particular for weight-specific increase in rigidity and crash resistance.

Im folgenden wird die Erfindung an Hand der beigefügten Abbildungen in näheren Einzelheiten erläutert. In denen zeigt:

Fig. 1
eine Schnittansicht in Längsrichtung des Hohlprofils, das in ein Induktionsmittel eingeführt ist; und
Fig. 2
eine Querschnittsansicht der in Fig. 1 dargestellten Anordnung.
In the following the invention with reference to the accompanying drawings will be explained in more detail. In which shows:
Fig. 1
a sectional view in the longitudinal direction of the hollow profile, which is inserted in an induction means; and
Fig. 2
a cross-sectional view of the arrangement shown in Fig. 1.

Fig. 1 zeigt eine Schnittansicht in Längsrichtung (Pfeilrichtung A) eines auszuschäumenden Hohlprofils 2, das in ein Induktionsmittel 1 eingeführt ist. Das Induktionsmittel kann als Induktionsspule oder -schleife ausgebildet sein, um nur einige Beispiele zu nennen. Im Inneren des Hohlprofils 2 befindet sich ein aufschäumbares Rohmaterial 3, das aus einem bekannten mittels Kompaktieren hergestellten Gemisch aus Metallpulver (z.B. Aluminium-, Magnesium- oder Zinkpulver) und Treibmittelpulver besteht. Dem Kompaktieren folgt gegebenenfalls ein Strangpressprozess. In Fig. 1 liegt das Rohmaterial 3 in stabförmiger Form vor. Es kann aber auch tabletten- oder granulatförmiges Rohmaterial verwendet werden. Unter tablettenförmigem Rohmaterial sind zB. gepresste Kügelchen zu verstehen. Ferner kann ein Gemisch aus unterschiedlichen Rohmaterialien verwendet werden, das z.B. auf Al-basierende Kügelchen sowie Keramikkügelchen enthält. Es können jedoch auch verschiedene Rohmaterialien verwendet werden, die auf unterschiedlichen Al-Legierungen basieren. Gleiches ist denkbar für auf Magnesium, Zink etc. basierende Rohmaterialien, die in beliebiger Weise - auch mit Keramik-Rohmaterial - kombiniert werden können. Bei einem stabförmigen Rohmaterial können verschiedene Rohmaterialien sektorförmig, konzentrische oder auf eine andere beliebige Weise angeordnet sein. Die Verwendung von derartigen Rohmaterial-Gemischen führt zum Erzeugen von Verbundschäumen.1 shows a sectional view in the longitudinal direction (arrow direction A) of a hollow profile 2 to be foamed, which is introduced into an induction means 1. The induction means may be formed as an induction coil or loop, to name just a few examples. Inside the hollow section 2 is a foamable raw material 3 consisting of a known compacted mixture of metal powder (e.g., aluminum, magnesium or zinc powder) and propellant powder. The compacting is optionally followed by an extrusion process. In Fig. 1, the raw material 3 is in a rod-shaped form. But it can also be used tablet or granular raw material. Under tablet-shaped raw material are, for example. to understand pressed beads. Further, a mixture of different raw materials may be used, e.g. contains Al-based beads and ceramic beads. However, various raw materials based on different Al alloys may be used. The same is conceivable for magnesium, zinc, etc. based raw materials, which can be combined in any way - even with ceramic raw material. In a rod-shaped raw material, various raw materials may be sector-shaped, concentric, or arranged in any other way. The use of such raw material mixtures leads to the production of composite foams.

Das Hohlprofil 2 in Fig. 1 ist rohrförmig ausgebildet und besteht aus Aluminium, Magnesium, Stahl oder dergleichen. Daneben können aber auch andersartig geformte Hohlprofile verwendet werden, die beispielsweise einen ovalen, rechteckigen oder einen anderen geeigneten Querschnitt aufweisen. Zusätzlich kann das Hohlprofil 2 nicht dargestellte Hinterschneidungen aufweisen. Das Hohlprofil 2 ist innerhalb des Induktionsmittels 1 angeordnet, wobei es das Induktionsmittel 1 wenigstens an einer Stelle berührt. In der in Fig.1 dargestellten bevorzugten Ausführungsform erstreckt sich die Berührung entlang der gesamten innenfläche des Induktionsmittels 1, um einen möglichst homogenen und gleichmäßigen Ausschäumvorgang zu bewirken. Die Form des Induktionsmittels 1 ist also idealerweise an die des Hohlprofils 2 angepasst. Bei einem rohrförmigen Hohlprofil 2 wird beispielsweise ein Induktionsmittel 1 verwendet, das einen kreisförmigen Innenquerschnitt aufweist. Weist das Hohlprofil:einen rechteckigen Querschnitt auf, so wird ein entsprechend rechteckig ausgebildetes Induktionsmittel verwendet. Altemativ kann ein formanpassbares Induktionsmittel verwendet werden, das aus einer Vielzahl von einzelnen, bewegbaren Elementen besteht, die sich automatisch an die Form des Hohlprofils anpassen. Darüberhinaus kann das Induktionsmittel aufklappbar ausgebildet werden, was die Handhabung beim Umschließen des Hohlprofils erleichtert. Ferner ist das Induktionsmittel 1 vorzugsweise kühlbar ausgebildet Zu diesem Zweck sind im Induktionsmittel 1 Kühlkanäle 1a angeordnet, durch die z.B. Kühlwasser geleitet wird. Eine derartige Anordnung von Kühlkanälen ist auch bei dem formanpassbaren bzw. kettenförmigen Induktionsmittel möglich. Das Durchströmen des Induktionsmittels 1 mit Kühlwasser bewirkt gleichzeitig eine Kühlung des Hohlprofils 2. Dabei ist die Kühlung umso besser, je enger bzw. besser der Kontakt zwischen Hohlprofil 2 und Induktionsmittel 1 ist.The hollow profile 2 in Fig. 1 is tubular and consists of aluminum, magnesium, steel or the like. In addition, however, differently shaped hollow profiles can be used, for example, have an oval, rectangular or other suitable cross-section. In addition, the hollow profile 2 may have not shown undercuts. The hollow profile 2 is arranged inside the induction means 1, wherein it touches the induction means 1 at least at one point. In the one shown in Fig.1 In the preferred embodiment, the contact extends along the entire inner surface of the induction means 1 in order to bring about as homogeneous and uniform foaming as possible. The shape of the induction means 1 is thus ideally adapted to that of the hollow profile 2. In a tubular hollow profile 2, for example, an induction means 1 is used which has a circular inner cross-section. If the hollow profile has a rectangular cross-section, an appropriately rectangular induction means is used. Alternatively, a conformable induction means can be used, which consists of a plurality of individual, movable elements that automatically adapt to the shape of the hollow profile. In addition, the induction means can be formed hinged, which facilitates handling when enclosing the hollow profile. Furthermore, the induction means 1 is preferably designed to be coolable. For this purpose, cooling channels 1a are arranged in the induction means 1 through which, for example, cooling water is passed. Such an arrangement of cooling channels is also possible with the shape-adaptable or chain-shaped induction means. The flow through the induction means 1 with cooling water simultaneously causes cooling of the hollow profile 2. The cooling is better, the closer or better the contact between the hollow profile 2 and the induction means 1 is.

Für die Wirkungsweise der vorliegenden Erfindung ist es ferner erforderlich, dass in dem Hohlprofil 2 eine sich im wesentlichen entlang der Längsrichtung A erstreckende elektrische Unterbrechung 4 vorgesehen ist (s. Fig. 2). Aufgrund der Kontaktierung von Hohlprofil 2 und Induktionsmittel 1 besteht zwischen diesen beiden Komponenten eine elektrisch leitende Verbindung, was ohne Unterbrechung 4 zu einem Kurzschluss des Induktionsmittels 1 führen würde. Im Kurzschlussfall würde sich also kein Magnetfeld zur Erwärmung des Rohmaterials ausbilden.For the operation of the present invention, it is further required that in the hollow profile 2 is provided a substantially along the longitudinal direction A extending electrical interruption 4 (see Fig. 2). Due to the contacting of the hollow profile 2 and the induction means 1 there is an electrically conductive connection between these two components, which without interruption 4 would lead to a short circuit of the induction means 1. In the case of a short circuit, therefore, no magnetic field would form to heat the raw material.

Die elektrische Unterbrechung 4 ist in Fig. 2 als Schlitz ausgebildet. Alternativ kann die elektrische Unterbrechung 4 aus einem elektrisch nicht leitenden Material bestehen, das in die Wand des Hohlprofils 2 integriert ist. Eine schlitzförmig ausgebildete elektrische Unterbrechung 4 kann aber auch mit einem geeigneten Isoliermaterial (z.B. Glimmer) gefüllt werden, um gegebenenfalls die Festigkeitseigenschaften zu verbessern. Das Einbringen des Schlitzes wird vorzugsweise vor dem Ausschäumen und vor dem Anordnen des Hohlprofils 2 in dem Induktionsmittel 1 durch Aufschneiden des Hohlprofils 2 in Längsrichtung A bewirkt. Dabei kann der Schlitz gerade, schräg oder in einer anderen beliebigen Form (z.B. L-förmig, U-förmig, Z-förmig etc.) in die Wand des Hohlprofils eingebracht werden. Des weiteren werden in jüngster Zeit insbesondere für Leichtbaukomponenten vermehrt zweiteilige oder aus mehreren Komponenten bestehende Profile verwendet, die beabstandet voneinander angeordnet sind, so dass gegebenenfalls dieser Bearbeitungsschritt von vornherein entfällt.The electrical interruption 4 is formed in FIG. 2 as a slot. Alternatively, the electrical interruption 4 may consist of an electrically non-conductive material which is integrated in the wall of the hollow profile 2. However, a slit-shaped electrical break 4 may also be filled with a suitable insulating material (e.g., mica) to improve the strength properties, if necessary. The introduction of the slot is preferably effected before foaming and before arranging the hollow section 2 in the induction means 1 by cutting the hollow section 2 in the longitudinal direction A. In this case, the slot can be straight, oblique or in any other desired form (for example, L-shaped, U-shaped, Z-shaped, etc.) introduced into the wall of the hollow profile. Furthermore, in recent times, especially for lightweight components increasingly used two-part or multi-component profiles, which are spaced from each other, so that optionally this processing step is omitted from the outset.

Das Induktionsmittel 1 wird durch eine HF-Quelle 5 versorgt und im Betrieb bildet sich ein Magnetfeld aus, wodurch das im Inneren des Hohlprofils 2 angeordnete Rohmaterial 3 induktiv erwärmt wird und aufschäumt. Aufgrund des leitenden Kontaktes zwischen Induktionsmittel 1 und Hohlprofil 2 wird dabei das Hohlprofil 2 quasi Teil des Induktionsmittels 1 und das sich aufgrund des Stromflusses ausbildende Magnetfeld weist im wesentlichen in Längsrichtung A. Dabei ist die Konzentration des Magnetfeldes im Zentrum des Induktionsmittels 1, also dort wo das Rohmaterial 3 angeordnet ist, am größten. Das Hohlprofil 2 erwärmt sich im Betrieb kaum bzw. lediglich auf Temperaturen bis zu ca. 100°C, so dass die Profileigenschaften erhalten bleiben. Die geringe Erwärmung des Hohlprofils 2 wird zudem durch die oben beschriebene Kühlwirkung unterstützt.The induction means 1 is supplied by an HF source 5 and during operation forms a magnetic field, whereby the arranged inside the hollow profile 2 raw material 3 is heated inductively and foams. Due to the conductive contact between the induction means 1 and the hollow profile 2, the hollow profile 2 is quasi part of the induction means 1 and the magnetic field forming due to the current flow has substantially in the longitudinal direction A. Here, the concentration of the magnetic field in the center of the induction means 1, ie where the raw material 3 is arranged, the largest. The hollow profile 2 heats up during operation hardly or only to temperatures up to about 100 ° C, so that the profile properties are maintained. The low heating of the hollow profile 2 is also supported by the cooling effect described above.

Auf diese Weise wird das Hohlprofil 2 homogen, partiell ausgeschäumt, wobei der Metallschaum an der Stelle gebildet wird, an der er tatsächlich benötigt wird. Ein weiterer Transportschritt ist nicht erforderlich. Zudem ist auch das Ausschäumen von Hinterschneidungen, die innerhalb des Hohlprofils angeordnet sind, aufgrund der symmetrischen Anordnung und der allseitigen Erwärmung des Rohmaterials unproblematisch.In this way, the hollow profile 2 is homogeneously, partially foamed, wherein the metal foam is formed at the point where it is actually needed. One further transport step is not required. In addition, the foaming of undercuts, which are arranged within the hollow profile, due to the symmetrical arrangement and the all-round heating of the raw material is unproblematic.

Das Hohlprofil 2 kann jedoch auch kontinuierlich ausgeschäumt werden. Zu diesem Zweck wird die Innenwand des Hohlprofils 2 vor dem Ausschäumen mit einem Isolierstoff (z.B. Ofenlack) überzogen. Der Isolierstoff verhindert einen Kurzschluss über die elektrische Unterbrechung 4, wenn sich das Innere des Hohlprofils 2 mit Metalischaum füllt und dabei statt an der Innenwand des Hohlprofils 2 anliegt. Wird das mit Isolierstoff ausgekleidete Hohlprofil 2 relativ zum Induktionsmittel 1 in Längsrichtung A bewegt, ist ein kontinuierliches Ausschäumen des Hohlprofils 2 möglich. Dabei ist es unerheblich, ob das Induktionsmittel 1 bezüglich des Hohlprofils 2 bewegt wird, oder umgekehrt. Unabhängig davon wird der Metallschaum wiederum dort erzeugt, wo er benötigt wird.However, the hollow section 2 can also be filled with foam continuously. For this purpose, the inner wall of the hollow section 2 is coated with an insulating material (for example stove enamel) before foaming. The insulating material prevents a short circuit on the electrical interruption 4 when the interior of the hollow section 2 fills with metal foam and thereby rests against the inner wall of the hollow section 2 instead. If the insulating material-lined hollow profile 2 is moved relative to the induction means 1 in the longitudinal direction A, a continuous foaming of the hollow section 2 is possible. It is irrelevant whether the induction means 1 is moved relative to the hollow profile 2, or vice versa. Regardless, the metal foam is again generated where it is needed.

In einem abschließend Arbeitsschritt kann das mit einer schlitzförmigen elektrischen Unterbrechung 4 versehene, ausgeschäumte Hohlprofil 2 durch Schweißen wieder verschlossen werden.In a final step, the provided with a slot-shaped electrical interruption 4, foamed hollow section 2 can be closed by welding again.

Ferner ist die Erfindung aufgrund des einfachen Aufbaus mobil einsetzbar, insbesondere für den Einsatz in der automatisierten Fertigung. Des weiteren können mit der oben beschriebenen Erfindung ausgeschäumte Hohlprofil-Halbzeuge hergestellt werden, die beispielsweise als Crash-Strukturen in der Fahrzeugtechnik sowie in der Luft- und Raumfahrttechnik Anwendung finden.Furthermore, the invention is mobile due to the simple structure, especially for use in automated manufacturing. Furthermore, foamed hollow profile semi-finished products can be produced with the invention described above, which are used, for example, as crash structures in vehicle technology and in aerospace engineering.

Claims (21)

  1. An arrangement for in-situ back-filling of hollow profiles with metal foam, comprising a hollow profile (2) and an induction means (1), into which the hollow profile (2), which comprises an electrical interruption (4) extending in the longitudinal direction (A) of the hollow profile (2), may be introduced, foamable raw material (3) being introducible into the hollow profile (2), characterised in that the hollow profile (2) is in contact with the induction means (1) at at least one point, so that the hollow profile (2) forms part of the induction means (1) during inductive foaming of the raw material (3).
  2. An arrangement for in-situ back-filling of hollow profiles with metal foam according to claim 1, characterised in that the internal wall of the hollow profile (2) is provided with an insulating material.
  3. An arrangement for in-situ back-filling of hollow profiles with metal foam according to claim 1 or claim 2, characterised in that the induction means (1) is of coolable construction.
  4. An arrangement for in-situ back-filling of hollow profiles with metal foam according to any one of claims 1 to 3; characterised in that the shape of the induction means (1) is substantially conformed to the shape of the hollow profile (2).
  5. An arrangement for in-situ back-filling of hollow profiles with metal foam according to any one of claims 1 to 3, characterised in that the induction means (1) is of shape-adjustable construction.
  6. An arrangement for in-situ back-filling of hollow profiles with metal foam according to any one of claims 1 to 5, characterised in that the hollow profile (2) exhibits a circular, oval, rectangular or any other desired cross-section.
  7. An arrangement for in-situ back-filling of hollow profiles with metal foam according to any one of claims 1 to 6, characterised in that the electrical interruption (4) is a slit.
  8. An arrangement for in-situ back-filling of hollow profiles with metal foam according to any one of claims 1 to 6, characterised in that the electrical interruption (4) consists of an electrically nonconductive material.
  9. An arrangement for in-situ back-filling of hollow profiles with metal foam according to any one of the preceding claims, characterised in that the induction means (1) and the hollow profile (2) are arranged so as to be displaceable relative to one another.
  10. An arrangement for in-situ back-filling of hollow profiles with metal foam according to any one of the preceding claims, characterised in that the device is suitable for mobile use.
  11. A method for in-situ back-filling of hollow profiles with metal foam, comprising the steps:
    - introduction of a hollow profile (2) to be back-filled with foam, which comprises an electrical interruption (4) extending in the longitudinal direction (A) thereof, into an induction means (1) or enclosure of the hollow profile (2) in the induction means (1);
    - arrangement of a foamable raw material (4) inside the hollow profile (2); and
    - inductive foaming of the raw material (4),

    characterised in that the induction means (1) is contacted at at least one point by the hollow profile (2), so that the hollow profile (2) forms part of the induction means (1) during inductive foaming of the raw material (4).
  12. A method for in-situ back-filling of hollow profiles with metal foam according to claim 11, characterised in that the electrical interruption (4) is introduced into the hollow profile (2) before the latter is introduced into the induction means (1).
  13. A method for in-situ back-filling of hollow profiles with metal foam according to claim 11 to claim 12, characterised in that the electrical interruption (4) is introduced by cutting the hollow profile (2) open in the longitudinal direction (A) thereof, so that a slit arises.
  14. A method for in-situ back-filling of hollow profiles with metal foam according to claim 13, characterised in that the slit is filled with an insulating material.
  15. A method for in-situ back-filling of hollow profiles with metal foam according to any one of claims 11 to 14, characterised in that the raw material (3) consists of a mixture of different materials, so that the hollow profile (2) is back-filled with a metal foam that exhibits a composite structure.
  16. A method for in-situ back-filling of hollow profiles with metal foam according to any one of claims 11 to 15, characterised in that the process parameters are varied during foaming of the raw material (3) in such a way that the hollow profile (2) is back-filled with a metal foam that exhibits a gradient structure.
  17. A method for in-situ back-filling of hollow profiles with metal foam according to any one of claims 11 to 16, characterised in that the internal wall of the hollow profile (2) is provided with an insulating layer prior to back-filling with foam.
  18. A method for in-situ back-filling of hollow profiles with metal foam according to any one of claims 1 to 17, characterised in that the induction means (1) and the hollow profile (2) arranged therein are moved relative to one another in the longitudinal direction (A), in order to back-fill the hollow profile (2) continuously with foam.
  19. A method for in-situ back-filling of hollow profiles with metal foam according to claim 14, characterised in that the slit is closed by welding after back-filling of the hollow profile (2) with foam.
  20. A method for in-situ back-filling of hollow profiles with metal foam according to any one of claims 11 to 19, characterised in that the method is suitable for mobile use.
  21. A method according to any one of claims 11 to 20 for producing a semi-finished product for crash structures in automotive technology and in aerospace technology.
EP02027181A 2001-12-14 2002-12-05 Apparatus and method for filling hollow profiles with a metal foam Expired - Fee Related EP1319453B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10161563 2001-12-14
DE10161563A DE10161563C1 (en) 2001-12-14 2001-12-14 Device for the in-situ foaming of hollow profiles with metal foam used in the production of a crash structure in vehicles and in aircraft and spacecraft comprises an induction unit into which a hollow profile is inserted

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EP1319453A1 EP1319453A1 (en) 2003-06-18
EP1319453B1 true EP1319453B1 (en) 2006-02-22

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EP (1) EP1319453B1 (en)
DE (2) DE10161563C1 (en)
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EP1319453A1 (en) 2003-06-18
US6889744B2 (en) 2005-05-10
DE10161563C1 (en) 2003-06-05
ES2254592T3 (en) 2006-06-16
US20030131965A1 (en) 2003-07-17
DE50205868D1 (en) 2006-04-27

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