EP2001621A2 - Method for production of a honeycomb seal - Google Patents

Method for production of a honeycomb seal

Info

Publication number
EP2001621A2
EP2001621A2 EP07722126A EP07722126A EP2001621A2 EP 2001621 A2 EP2001621 A2 EP 2001621A2 EP 07722126 A EP07722126 A EP 07722126A EP 07722126 A EP07722126 A EP 07722126A EP 2001621 A2 EP2001621 A2 EP 2001621A2
Authority
EP
European Patent Office
Prior art keywords
cells
honeycomb
shaped body
injection molding
honeycomb seal
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP07722126A
Other languages
German (de)
French (fr)
Inventor
Reinhold Meier
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.)
MTU Aero Engines AG
Original Assignee
MTU Aero Engines GmbH
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 MTU Aero Engines GmbH filed Critical MTU Aero Engines GmbH
Publication of EP2001621A2 publication Critical patent/EP2001621A2/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • B22F3/22—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip
    • B22F3/225—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces for producing castings from a slip by injection molding
    • 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
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/009—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of turbine components other than turbine blades
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B11/00—Apparatus or processes for treating or working the shaped or preshaped articles
    • B28B11/003—Apparatus or processes for treating or working the shaped or preshaped articles the shaping of preshaped articles, e.g. by bending
    • B28B11/006—Making hollow articles or partly closed articles
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/0006—Honeycomb structures
    • C04B38/0012—Honeycomb structures characterised by the material used for sealing or plugging (some of) the channels of the honeycombs
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
    • F01D11/00—Preventing or minimising internal leakage of working-fluid, e.g. between stages
    • F01D11/08—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator
    • F01D11/12—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator using a rubstrip, e.g. erodible. deformable or resiliently-biased part
    • F01D11/127—Preventing or minimising internal leakage of working-fluid, e.g. between stages for sealing space between rotor blade tips and stator using a rubstrip, e.g. erodible. deformable or resiliently-biased part with a deformable or crushable structure, e.g. honeycomb
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02C—GAS-TURBINE PLANTS; AIR INTAKES FOR JET-PROPULSION PLANTS; CONTROLLING FUEL SUPPLY IN AIR-BREATHING JET-PROPULSION PLANTS
    • F02C7/00—Features, components parts, details or accessories, not provided for in, or of interest apart form groups F02C1/00 - F02C6/00; Air intakes for jet-propulsion plants
    • F02C7/04—Air intakes for gas-turbine plants or jet-propulsion plants
    • F02C7/045—Air intakes for gas-turbine plants or jet-propulsion plants having provisions for noise suppression
    • 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
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B3/00—Producing shaped articles from the material by using presses; Presses specially adapted therefor
    • B28B3/20—Producing shaped articles from the material by using presses; Presses specially adapted therefor wherein the material is extruded
    • B28B2003/203—Producing shaped articles from the material by using presses; Presses specially adapted therefor wherein the material is extruded for multi-channelled structures, e.g. honeycomb structures
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00982—Uses not provided for elsewhere in C04B2111/00 as construction elements for space vehicles or aeroplanes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05D—INDEXING SCHEME FOR ASPECTS RELATING TO NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, GAS-TURBINES OR JET-PROPULSION PLANTS
    • F05D2230/00—Manufacture

Definitions

  • the invention relates to a method for producing a honeycomb seal according to the preamble of claim 1.
  • titanium alloys The most important materials used today for aircraft engines or other gas turbines are titanium alloys, nickel alloys (also called superalloys) and high-strength steels.
  • the high strength steels are used for shaft parts, gear parts, compressor casings and turbine casings.
  • Titanium alloys are typical materials for compressor parts.
  • Nickel alloys are suitable for the hot parts of the aircraft engine.
  • As a manufacturing method for gas turbine components made of titanium alloys, nickel alloy or other alloys are known from the prior art primarily investment casting and forging. All highly stressed gas turbine components, such as components for a compressor, are forgings. Components for a turbine, however, are usually designed as precision castings.
  • Powder metallurgical injection molding represents an alternative for the manufacture or production of complex components.
  • Powder metallurgical injection molding is related to plastic injection molding and is also referred to as metal mold injection or metal injection molding (MIM-V experienced).
  • MIM-V metal mold injection or metal injection molding
  • With the powder metallurgical injection molding components can be produced, which reach almost the full density and approximately the static strength of forgings. As a rule, the reduced dynamic strength compared to forgings can be compensated for by suitable material selection. be siert.
  • the procedure is such that in a first process step a powder, preferably a metal powder and / or a ceramic powder, is mixed with a binder and optionally a plasticizer and optionally further additives to form a homogeneous mass. From this homogeneous mass, a molding for the honeycomb seal is made by injection molding.
  • the injection-molded body already has the geometric shape of the honeycomb seal to be produced and thus honeycomb-like cells, but its volume is increased by the volume of the binder and plasticizer added.
  • the injection-molded article is deprived of binder and plasticizer in a debinding process. Subsequently, during the sintering, the molded body is compressed or shrunk to the finished honeycomb seal.
  • honeycomb seals produced by powder metallurgical injection molding are suitable, for example, for sealing in a gas turbine a radially outer gap between blade tips of rotating blades and a stationary housing. If such honeycomb seals also assume a heat transfer function in addition to the sealing function, it is already known from practice to arrange a heat-insulating filling in the honeycomb cells of the finished honeycomb seal, this heat-insulating filling being firmly connected to the honeycomb seal by soldering. The soldering of heat-insulating fillings with the honeycomb cells of a honeycomb seal is technically particularly complex.
  • the present invention is based on the problem to provide a novel method for producing a honeycomb seal with fauxdärnmfunktion.
  • At least some of the cells of the molding are at least partially sintered before sintering. each filled with at least one hollow body, wherein then the shaped body is sintered together with the introduced into the cells hollow bodies.
  • heat-insulating hollow bodies at least in each case one heat-insulating hollow body in at least some of the cells of the shaped body before sintering a shaped body of a honeycomb seal to be produced by powder metallurgical injection molding.
  • the heat-curable hollow bodies are firmly connected to the honeycomb cells of the molded body.
  • soldering of heat-insulating fillings with the cells of the honeycomb seal can be dispensed with, resulting in a particularly efficient manufacturing process for honeycomb seals with a thermal insulation function.
  • the present invention relates to the production of a honeycomb seal by powder metallurgical injection molding.
  • Powder metallurgy injection molding is also referred to as Metal Injection Molding (MIM).
  • MIM Metal Injection Molding
  • the procedure is such that a metal powder and / or a ceramic powder is provided in a first step.
  • a binder and optionally a plasticizer and optionally further additives are provided in a second step.
  • the provided metal powder and / or ceramic powder and the provided binder and optionally the plasticizer and optionally the other additives are mixed in a third step, so that forms a homogeneous mass.
  • the volume fraction of the metal powder and / or ceramic powder in the homogeneous mass is preferably between 50% and 70%.
  • the proportion of binder and optionally plasticizer on the homogeneous mass varies approximately between 30% and 50%.
  • This homogeneous mass of metal powder and / or ceramic powder, binder and optionally plasticizer is then further processed by injection molding in a further process step.
  • injection molding a shaped body of the honeycomb seal to be produced is manufactured.
  • This shaped body already has all the typical features of the honeycomb seal to be produced.
  • the shaped body has the geometric shape of the honeycomb seal to be produced, that is to say honeycomb-like cells.
  • the molded article has a volume increased by the binder content and plasticizer content.
  • the moldings provided by injection molding are also called greenware.
  • the binder and the plasticizer is expelled from the molding.
  • This step can also be called a de-bonding process.
  • the expulsion of binder and plasticizer can be done in different ways. This is usually done by fractional, thermal decomposition or evaporation. Another possibility consists of sucking out the thermally liquefied binding and plasticizing agents by capillary forces, by sublimation or by solvents.
  • the shaped body after the debindering process is also called browning.
  • the shaped body is sintered. During the sintering, the shaped body is compacted to the honeycomb seal with the final geometric properties. During sintering, therefore, the shaped body decreases, wherein the dimensions of the shaped body must uniformly decrease in all three spatial directions. The linear shrinkage is dependent on the binder content and plasticizer content between 10% and 20%.
  • the sintering can be carried out under different protective gases or under vacuum. After sintering, the finished honeycomb seal is present. If necessary, after the sintering, the honeycomb seal can be subjected to a refining process. However, the refining process is optional. nal. It can already be present immediately after sintering a ready-to-install honeycomb seal.
  • the heat-insulating hollow body with the honeycomb cells of the molded body enter a firm connection.
  • the heat-insulating hollow bodies are preferably introduced before the debinding process into the cells of the green body, still soft molded body.
  • the honeycomb cells of the molding are at least partially filled with at least one heat-insulating hollow body. It is therefore possible to introduce in each honeycomb cell of the molding exclusively a heat-insulating hollow body. It is also possible to introduce in each honeycomb cell a plurality of heat-insulating hollow body. By filling the honeycomb cells with at least one hollow body, they may be filled either partially or completely by the or each thermally insulating hollow body.
  • a homogeneous mass is used for injection molding of the shaped body of the honeycomb seal to be produced, which was obtained using a metal powder, metallic or metallized hollow body are used as a heat-insulating hollow body.
  • Metallized hollow bodies are those hollow bodies which are metallically coated on their outer surface.
  • ceramic bodies or hollow bodies ceramized on its outer surface are used as hollow bodies.
  • they may optionally be provided on their outer surface with a slip layer.
  • the heat-insulating hollow bodies to be introduced into the honeycomb cells of the shaped body are preferably adapted in size and shape to the honeycomb-like cells of the shaped body.
  • Particularly preferably hollow bodies designed as hollow spheres are used, which are pressed into the honeycomb cells of the shaped body.
  • the honeycomb cells of the shaped body may have different geometric shapes, e.g. round, oval or even polygonal, in particular hexagonal, be contoured.
  • honeycomb seal By filling the honeycomb cells of a molded article produced by injection molding for a honeycomb seal before sintering the same with hollow bodies, a honeycomb seal with thermal insulation function can be produced in a particularly simple manner. By filling the honeycomb cells with the hollow bodies, the sealing effect of the honeycomb seal is further improved. Furthermore, when rubbing blade tips of rotating blades into the honeycomb seal, the abrasion thereof is reduced, so that it has a longer service life.
  • the hollow bodies are subcooled before they are imported into the honeycomb cells of the molded body, ie cooled to a temperature which is lower than the temperature of the shaped body. This can avoid that the honeycomb cells are damaged during insertion of the hollow body.

Abstract

The invention relates to a method for production of a honeycomb seal by powder metallurgical injection moulding. A metal powder and/or a ceramic powder is first mixed with a binder to give a homogeneous mass for the powder metallurgical injection moulding, a moulded body with honeycomb cells is subsequently produced from the homogeneous mass by injection moulding for the honeycomb seal, the moulded body is then subjected to a release process and finally compressed by sintering the moulded body to give the honeycomb seal with the desired geometrical properties. According to the invention, at least some of the cells of the moulded body are at least partly filled with at least one hollow body before sintering, wherein the moulded body is subsequently sintered together with the hollow bodies introduced into the cells.

Description

Verfahren zum Herstellen einer Wabendichtung Method for producing a honeycomb seal
Die Erfindung betrifft ein Verfahren zum Herstellen einer Wabendichtung nach dem Oberbegriff des Anspruchs 1.The invention relates to a method for producing a honeycomb seal according to the preamble of claim 1.
Moderne Gasturbinen, insbesondere Flugtriebwerke, müssen höchsten Ansprüchen im Hinblick auf Zuverlässigkeit, Gewicht, Leistung, Wirtschaftlichkeit und Lebensdauer gerecht werden. In den letzten Jahrzehnten wurden insbesondere auf dem zivilen Sektor Flugtriebwerke entwickelt, die den obigen Anforderungen voll gerecht werden und ein hohes Maß an technischer Perfektion erreicht haben. Bei der Entwicklung von Flugtriebwerken spielt unter anderem die Werkstoffauswahl, die Suche nach neuen, geeigneten Werkstoffen sowie die Suche nach neuen Fertigungsverfahren eine entscheidende Rolle.Modern gas turbines, in particular aircraft engines, must meet the highest demands in terms of reliability, weight, performance, economy and service life. In recent decades, aircraft engines have been developed, particularly in the civil sector, which fully meet the above requirements and have achieved a high degree of technical perfection. Among other things, the selection of materials, the search for new, suitable materials and the search for new production processes play a crucial role in the development of aircraft engines.
Die wichtigsten, heutzutage für Flugtriebwerke oder sonstige Gasturbinen verwendeten Werkstoffe sind Titanlegierungen, Nickellegierungen (auch Superlegierungen genannt) und hochfeste Stähle. Die hochfesten Stähle werden für Wellenteile, Getriebeteile, Verdichtergehäuse und Turbinengehäuse verwendet. Titanlegierungen sind typische Werkstoffe für Verdichterteile. Nickellegierungen sind für die heißen Teile des Flugtriebwerks geeignet. Als Fertigungsverfahren für Gasturbinenbauteile aus Titanlegierungen, Nickellegierung oder sonstigen Legierungen sind aus dem Stand der Technik in erster Linie das Feingießen sowie Schmieden bekannt. Alle hochbeanspruchten Gasturbinenbauteile, wie zum Beispiel Bauteile für einen Verdichter, sind Schmiedeteile. Bauteile für eine Turbine werden hingegen in der Regel als Feingussteile ausgeführt.The most important materials used today for aircraft engines or other gas turbines are titanium alloys, nickel alloys (also called superalloys) and high-strength steels. The high strength steels are used for shaft parts, gear parts, compressor casings and turbine casings. Titanium alloys are typical materials for compressor parts. Nickel alloys are suitable for the hot parts of the aircraft engine. As a manufacturing method for gas turbine components made of titanium alloys, nickel alloy or other alloys are known from the prior art primarily investment casting and forging. All highly stressed gas turbine components, such as components for a compressor, are forgings. Components for a turbine, however, are usually designed as precision castings.
Für die Fertigung bzw. Herstellung von komplexen Bauteilen stellt das pulvermetallurgische Spritzgießen eine Alternative dar. Das pulvermetallurgische Spritzgießen ist mit dem Kunststoffspritzguss verwandt und wird auch als Metallform-Spritzen oder Metal Injection Moulding-Verfahren (MIM-V erfahren) bezeichnet. Mit dem pulvermetallurgischen Spritzgießen können Bauteile hergestellt werden, die fast die volle Dichte sowie annähernd die statische Festigkeit von Schmiedeteilen erreichen. Die gegenüber Schmiedeteilen in der Regel verringerte dynamische Festigkeit kann durch geeignete Werkstoffauswahl kompen- siert werden. So ist es aus dem Stand der Technik gemäß DE 102 59 963 Al bereits bekannt, mit dem pulvermetallurgischen Spritzgießen Wabendichtungen herzustellen.Powder metallurgical injection molding represents an alternative for the manufacture or production of complex components. Powder metallurgical injection molding is related to plastic injection molding and is also referred to as metal mold injection or metal injection molding (MIM-V experienced). With the powder metallurgical injection molding components can be produced, which reach almost the full density and approximately the static strength of forgings. As a rule, the reduced dynamic strength compared to forgings can be compensated for by suitable material selection. be siert. Thus, it is already known from the prior art according to DE 102 59 963 Al to produce with the powder metallurgical injection molding honeycomb seals.
Beim pulvermetallurgischen Spritzgießen einer Wabendichtung wird in groben Zügen so vorgegangen, dass in einem ersten Verfahrensschritt ein Pulver, vorzugsweise ein Metallpulver und/oder ein Keramikpulver, mit einem Bindemittel und gegebenenfalls einem Plastifizierungsmittel und gegebenenfalls weiteren Additiven zu einer homogenen Masse vermischt wird. Aus dieser homogenen Masse wird durch Spritzgießen ein Formkörper für die Wabendichtung gefertigt. Der spritzgegossene Formkörper besitzt bereits die geometrische Form der herzustellenden Wabendichtung und damit wabenartige Zellen, sein Volumen ist jedoch um das Volumen des zugesetzten Bindemittels und Plastifϊzierungsmittels vergrößert. Dem spritzgegossenen Formkörper wird in einem Entbinderungsprozess das Bindemittel sowie Plastifizierungsmittel entzogen. Darauffolgend wird während des Sinters der Formkörper zur fertigen Wabendichtung verdichtet bzw. geschrumpft.In powder metallurgical injection molding of a honeycomb seal, the procedure is such that in a first process step a powder, preferably a metal powder and / or a ceramic powder, is mixed with a binder and optionally a plasticizer and optionally further additives to form a homogeneous mass. From this homogeneous mass, a molding for the honeycomb seal is made by injection molding. The injection-molded body already has the geometric shape of the honeycomb seal to be produced and thus honeycomb-like cells, but its volume is increased by the volume of the binder and plasticizer added. The injection-molded article is deprived of binder and plasticizer in a debinding process. Subsequently, during the sintering, the molded body is compressed or shrunk to the finished honeycomb seal.
Derartige, durch pulvermetallurgisches Spritzgießen hergestellte Wabendichtungen eignen sich beispielsweise dazu, in einer Gasturbine einen radial außenliegenden Spalt zwischen Schaufelspitzen rotierender Laufschaufeln und einem feststehenden Gehäuse abzudichten. Sollen derartige Wabendichtungen neben der Dichtfunktion auch eine Wärmedä^nmfunkti- on übernehmen, so ist es aus der Praxis bereits bekannt, in den wabenartigen Zellen der fertig hergestellten Wabendichtung eine wärmedämmende Füllung anzuordnen, wobei diese wärmedämmende Füllung durch Verlöten mit der Wabendichtung fest verbunden ist. Das Verlöten wärmedämmender Füllungen mit den wabenartigen Zellen einer Wabendichtung ist prozesstechnisch besonders aufwendig.Such honeycomb seals produced by powder metallurgical injection molding are suitable, for example, for sealing in a gas turbine a radially outer gap between blade tips of rotating blades and a stationary housing. If such honeycomb seals also assume a heat transfer function in addition to the sealing function, it is already known from practice to arrange a heat-insulating filling in the honeycomb cells of the finished honeycomb seal, this heat-insulating filling being firmly connected to the honeycomb seal by soldering. The soldering of heat-insulating fillings with the honeycomb cells of a honeycomb seal is technically particularly complex.
Hiervon ausgehend liegt der vorliegenden Erfindung das Problem zu Grunde, ein neuartiges Verfahren zum Herstellen einer Wabendichtung mit Wärmedärnmfunktion zu schaffen.On this basis, the present invention is based on the problem to provide a novel method for producing a honeycomb seal with Wärmedärnmfunktion.
Dieses Problem wird durch ein Verfahren im Sinne von Anspruch 1 gelöst. Erfindungsgemäß werden vor dem Sintern zumindest einige der Zellen des Formkörpers zumindest teil- weise mit jeweils mindestens einem Hohlköper befüllt, wobei anschließend der Formkörper zusammen mit den in die Zellen eingeführten Hohlkörpern gesintert wird.This problem is solved by a method in the sense of claim 1. According to the invention, at least some of the cells of the molding are at least partially sintered before sintering. each filled with at least one hollow body, wherein then the shaped body is sintered together with the introduced into the cells hollow bodies.
Mit der hier vorliegenden Erfindung wird vorgeschlagen, wärmedämmende Hohlkörper vor dem Sintern eines Formkörpers einer durch pulvermetallurgisches Spritzgießen herzustellenden Wabendichtung in zumindest einige der Zellen des Formkörpers mindestens jeweils einen wärmedämmenden Hohlkörper anzuordnen.With the present invention, it is proposed to arrange heat-insulating hollow bodies at least in each case one heat-insulating hollow body in at least some of the cells of the shaped body before sintering a shaped body of a honeycomb seal to be produced by powder metallurgical injection molding.
Beim anschließenden Sintern werden die wärrnedärnrnenden Hohlkörper mit den wabenartigen Zellen des Formkörpers fest verbunden. Auf das nach der Praxis übliche Verlöten von wärmedämmenden Füllungen mit den Zellen der Wabendichtung kann so verzichtet werden, wodurch sich ein besonders effizientes Herstellverfahren für Wabendichtungen mit einer Wärmedämmfunktion ergibt.During the subsequent sintering, the heat-curable hollow bodies are firmly connected to the honeycomb cells of the molded body. On the usual in practice soldering of heat-insulating fillings with the cells of the honeycomb seal can be dispensed with, resulting in a particularly efficient manufacturing process for honeycomb seals with a thermal insulation function.
Bevorzugte Weiterbildungen der Erfindung ergeben sich aus den Unteransprüchen und der nachfolgenden Beschreibung.Preferred embodiments of the invention will become apparent from the dependent claims and the description below.
Die hier vorliegende Erfindung betrifft die Herstellung einer Wabendichtung durch pulvermetallurgisches Spritzgießen. Pulvermetallurgisches Spritzgießen wird auch als Metal Injection Moulding (MIM) bezeichnet.The present invention relates to the production of a honeycomb seal by powder metallurgical injection molding. Powder metallurgy injection molding is also referred to as Metal Injection Molding (MIM).
Beim pulvermetallurgischen Spritzgießen einer Wabendichtung wird so vorgegangen, dass in einem ersten Schritt ein Metallpulver und/oder ein Keramikpulver bereitgestellt wird. In einem zweiten Schritt werden ein Bindemittel und gegebenenfalls ein Plastifizierungsmittel sowie gegebenenfalls weitere Additive bereitgestellt.In powder metallurgical injection molding of a honeycomb seal, the procedure is such that a metal powder and / or a ceramic powder is provided in a first step. In a second step, a binder and optionally a plasticizer and optionally further additives are provided.
Das bereitgestellte Metallpulver und/oder Keramikpulver sowie das bereitgestellte Bindemittel und gegebenenfalls das Plastifizierungsmittel sowie gegebenenfalls die weiteren Additive werden in einem dritten Schritt gemischt, so dass sich eine homogene Masse ausbildet. Der Volumenanteil des Metallpulvers und/oder Keramikpulver in der homogenen Masse beträgt dabei vorzugsweise zwischen 50% und 70%. Der Anteil von Bindemittel und gegebenenfalls Plastifizierungsmittel an der homogenen Masse schwankt in etwa zwischen 30% und 50%.The provided metal powder and / or ceramic powder and the provided binder and optionally the plasticizer and optionally the other additives are mixed in a third step, so that forms a homogeneous mass. The volume fraction of the metal powder and / or ceramic powder in the homogeneous mass is preferably between 50% and 70%. The proportion of binder and optionally plasticizer on the homogeneous mass varies approximately between 30% and 50%.
Diese homogene Masse aus Metallpulver und/oder Keramikpulver, Bindemittel und gegebenenfalls Plastifizierungsmittel wird anschließend in einem weiteren Verfahrensschritt durch Spritzgießen weiterverarbeitet. Beim Spritzgießen wird ein Formkörper der herzustellenden Wabendichtung gefertigt. Dieser Formkörper weist schon alle typischen Merkmale der herzustellenden Wabendichtung auf. Insbesondere verfügt der Formkörper über die geometrische Form der zu fertigenden Wabendichtung, also über wabenartige Zellen. Der Formkörper verfügt jedoch über ein um den Bindemittelgehalt sowie Plastifizierungs- mittelgehalt vergrößertes Volumen. Den durch Spritzgießen bereitgestellten Formkörper bezeichnet man auch als Grünling.This homogeneous mass of metal powder and / or ceramic powder, binder and optionally plasticizer is then further processed by injection molding in a further process step. In injection molding, a shaped body of the honeycomb seal to be produced is manufactured. This shaped body already has all the typical features of the honeycomb seal to be produced. In particular, the shaped body has the geometric shape of the honeycomb seal to be produced, that is to say honeycomb-like cells. However, the molded article has a volume increased by the binder content and plasticizer content. The moldings provided by injection molding are also called greenware.
In einem nachgeschalteten Verfahrensschritt wird das Bindemittel und das Plastifizierungsmittel aus dem Formkörper ausgetrieben. Diesen Schritt kann man auch als Entbinde- rungsprozess bezeichnen. Das Austreiben von Bindemittel und Plastifizierungsmittel kann auf unterschiedliche Art und Weise erfolgen. Üblicherweise erfolgt dies durch fraktionierte, thermische Zersetzung bzw. Verdampfung. Eine weitere Möglichkeit besteht durch Heraussaugen der thermisch verflüssigten Binde- und Plastifizierungsmittel durch Kapillarkräfte, durch Sublimation oder durch Lösungsmittel. Den Formkörper nach dem Entbin- derungsprozess bezeichnet man auch als Bräunung.In a downstream process step, the binder and the plasticizer is expelled from the molding. This step can also be called a de-bonding process. The expulsion of binder and plasticizer can be done in different ways. This is usually done by fractional, thermal decomposition or evaporation. Another possibility consists of sucking out the thermally liquefied binding and plasticizing agents by capillary forces, by sublimation or by solvents. The shaped body after the debindering process is also called browning.
Im Anschluss an den Entbinderungsprozess wird der Formkörper gesintert. Während des Sinters wird der Formkörper zu der Wabendichtung mit den endgültigen, geometrischen Eigenschaften verdichtet. Während des Sinterns verkleinert sich demnach der Formkörper, wobei die Dimensionen des Formkörpers in allen drei Raumrichtungen gleichmäßig schwinden müssen. Der lineare Schwund beträgt abhängig vom Bindemittelgehalt und Plastifizierungsmittelgehalt zwischen 10% und 20%. Das Sintern kann unter verschiedenen Schutzgasen oder unter Vakuum durchgeführt werden. Nach dem Sintern liegt die fertige Wabendichtung vor. Falls erforderlich, kann nach dem Sintern die Wabendichtung noch einem Veredelungsprozess unterzogen werden. Der Veredelungsprozess ist jedoch optio- nal. Es kann bereits auch unmittelbar nach dem Sintern eine einbaufertige Wabendichtung vorliegen.After the debinding process, the shaped body is sintered. During the sintering, the shaped body is compacted to the honeycomb seal with the final geometric properties. During sintering, therefore, the shaped body decreases, wherein the dimensions of the shaped body must uniformly decrease in all three spatial directions. The linear shrinkage is dependent on the binder content and plasticizer content between 10% and 20%. The sintering can be carried out under different protective gases or under vacuum. After sintering, the finished honeycomb seal is present. If necessary, after the sintering, the honeycomb seal can be subjected to a refining process. However, the refining process is optional. nal. It can already be present immediately after sintering a ready-to-install honeycomb seal.
Zum Herstellen einer Wabendichtung mit Wärmedäirmifunktion wird im Sinne der hier vorliegenden Erfindung vorgeschlagen, vor dem Sintern zumindest einige der wabenartigen Zellen des Formkörpers zumindest teilweise mit jeweils mindestens einem wärmedämmenden Hohlkörper zu befüllen, wobei der Formkörper anschließend zusammen mit den in die wabenartigen Zellen eingeführten Hohlkörpern gesintert wird. Dabei gehen die wärmedämmenden Hohlkörper mit den wabenartigen Zellen des Formkörpers eine feste Verbindung ein.For producing a honeycomb seal with Wärmedäirmifunktion is proposed in the context of the present invention, before sintering at least some of the honeycomb cells of the molding at least partially filled with at least one thermally insulating hollow body, wherein the shaped body then sintered together with the introduced into the honeycomb cells hollow bodies becomes. In this case, the heat-insulating hollow body with the honeycomb cells of the molded body enter a firm connection.
Im Sinne der hier vorliegenden Erfindung werden die wärmedämmenden Hohlkörper vorzugsweise noch vor dem Entbinderungsprozess in die Zellen des als Grünling ausgebildeten, noch weichen Formkörpers eingeführt. Alternativ ist es jedoch auch möglich, die Hohlkörper nach dem Entbinderungsprozess in die wabenartigen Zellen des als Bräunung ausgebildeten, bereits teilweise verfestigten Formkörpers einzuführen.For the purposes of the present invention, the heat-insulating hollow bodies are preferably introduced before the debinding process into the cells of the green body, still soft molded body. Alternatively, however, it is also possible to introduce the hollow bodies after the debinding process into the honeycomb cells of the formed as a tanning, already partially solidified shaped body.
Wie bereits oben erwähnt, werden die wabenartigen Zellen des Formkörpers zumindest teilweise mit jeweils mindestens einem wärmedämmenden Hohlkörper befüllt. Es ist demnach möglich, in jede wabenartige Zelle des Formkörpers ausschließlich einen wärmedämmenden Hohlkörper einzuführen. Ebenso ist es möglich, in jede wabenartige Zelle mehrere wärmedämmende Hohlkörper einzuführen. Durch das Befüllen der wabenartigen Zellen mit mindestens einem Hohlkörper können dieselben entweder teilweise oder vollständig von dem oder jedem wärmedämmenden Hohlkörper ausgefüllt sein.As already mentioned above, the honeycomb cells of the molding are at least partially filled with at least one heat-insulating hollow body. It is therefore possible to introduce in each honeycomb cell of the molding exclusively a heat-insulating hollow body. It is also possible to introduce in each honeycomb cell a plurality of heat-insulating hollow body. By filling the honeycomb cells with at least one hollow body, they may be filled either partially or completely by the or each thermally insulating hollow body.
Dann, wenn zum Spritzgießen des Formkörpers der herzustellenden Wabendichtung eine homogene Masse verwendet wird, die unter Verwendung eines Metallpulvers gewonnen wurde, werden als wärmedämmende Hohlkörper metallische oder metallisierte Hohlkörper verwendet. Metallisierte Hohlkörper sind solche Hohlkörper, die an ihrer äußeren Oberfläche metallisch beschichtet sind. Dann, wenn die zum Spritzgießen des Formkörpers verwendete homogene Masse aus einem Keramikpulver gewonnen wird, werden als Hohlkörper keramische oder an ihrer äußeren Oberfläche keramisierte Hohlkörper verwendet. Um die Sinterfähigkeit der Hohlkörper zu verbessern, können dieselben gegebenenfalls an ihrer äußeren Oberfläche mit einer Schlickerschicht versehen werden.Then, if a homogeneous mass is used for injection molding of the shaped body of the honeycomb seal to be produced, which was obtained using a metal powder, metallic or metallized hollow body are used as a heat-insulating hollow body. Metallized hollow bodies are those hollow bodies which are metallically coated on their outer surface. Then, when the homogeneous mass used for injection molding of the molded body is obtained from a ceramic powder, ceramic bodies or hollow bodies ceramized on its outer surface are used as hollow bodies. In order to improve the sinterability of the hollow body, they may optionally be provided on their outer surface with a slip layer.
Die in die wabenartigen Zellen des Formkörpers einzuführenden, wärmedämmenden Hohlkörper sind vorzugsweise in Größe und Form an die wabenartigen Zellen des Formkörpers angepasst. Besonders bevorzugt finden als Hohlkugeln ausgebildete Hohlkörper Verwendung, die in die wabenartigen Zellen des Formkörpers eingedrückt werden. Die wabenartigen Zellen des Formkörpers können unterschiedliche geometrische Formen aufweisen, so z.B. rund, oval oder auch mehreckig, insbesondere sechseckig, konturiert sein.The heat-insulating hollow bodies to be introduced into the honeycomb cells of the shaped body are preferably adapted in size and shape to the honeycomb-like cells of the shaped body. Particularly preferably hollow bodies designed as hollow spheres are used, which are pressed into the honeycomb cells of the shaped body. The honeycomb cells of the shaped body may have different geometric shapes, e.g. round, oval or even polygonal, in particular hexagonal, be contoured.
Durch die Befüllung der wabenartigen Zellen eines durch Spritzgießen hergestellten Formkörpers für eine Wabendichtung vor dem Sintern desselben mit Hohlkörpern kann auf besonders einfache Art und Weise eine Wabendichtung mit Wärmedämmfunktion hergestellt werden. Durch die Befüllung der wabenartigen Zellen mit den Hohlkörpern wird des Weiteren auch die Dichtwirkung der Wabendichtung verbessert. Weiterhin wird beim Anstreifen von Schaufelspitzen rotierender Laufschaufeln in die Wabendichtung der Abrieb an derselben verringert, sodass dieselbe eine höhere Lebensdauer aufweist.By filling the honeycomb cells of a molded article produced by injection molding for a honeycomb seal before sintering the same with hollow bodies, a honeycomb seal with thermal insulation function can be produced in a particularly simple manner. By filling the honeycomb cells with the hollow bodies, the sealing effect of the honeycomb seal is further improved. Furthermore, when rubbing blade tips of rotating blades into the honeycomb seal, the abrasion thereof is reduced, so that it has a longer service life.
Vorzugsweise werden die Hohlkörper vor dem Einfuhren derselben in die wabenartigen Zellen des Formkörpers unterkühlt, also auf eine Temperatur abgekühlt, die geringer ist als die Temperatur des Formkörpers. Hierdurch kann vermieden werden, dass die wabenartigen Zellen beim Einführen der Hohlkörper beschädigt werden. Preferably, the hollow bodies are subcooled before they are imported into the honeycomb cells of the molded body, ie cooled to a temperature which is lower than the temperature of the shaped body. This can avoid that the honeycomb cells are damaged during insertion of the hollow body.

Claims

Patentansprüche claims
1. Verfahren zum Herstellen einer Wabendichtung durch pulvermetallurgisches Spitzgießen, wobei beim pulvermetallurgischen Spitzgießen zuerst ein Metallpulver und/oder ein Keramikpulver mit zumindest einem Bindemittel zu einer homogenen Masse vermischt wird, wobei anschließend aus der homogenen Masse durch Spritzgießen ein wabenartige Zellen aufweisender Formkörper für die Wabendichtung gefertigt wird, wobei der Formkörper darauffolgend einem Entbinderungsprozess unterzogen wird, und wobei im Anschluss durch Sintern der Formkörper zu der Wabendichtung mit gewünschten geometrischen Eigenschaften verdichtet wird, dadurch gekennzeichnet, vor dem Sintern zumindest einige der Zellen des Formkörpers zumindest teilweise mit jeweils mindestens einem Hohlköper befüllt werden, und dass anschließend der Formkörper zusammen mit den in die Zellen eingeführten Hohlkörpern gesintert wird.1. A method for producing a honeycomb seal by powder metallurgy injection molding, wherein the powder metallurgy injection molding first a metal powder and / or a ceramic powder is mixed with at least one binder to form a homogeneous mass, then from the homogeneous mass by injection molding a honeycomb cells exhibiting shaped body for the honeycomb seal is subsequently subjected to a debindering process, and wherein subsequently compacted by sintering the shaped body to the honeycomb seal with desired geometric properties, characterized, before sintering, at least partially filled with at least some of the cells of the shaped body with at least one hollow body be sintered, and then that the shaped body is sintered together with the introduced into the cells hollow bodies.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass die Hohlköper vor dem Entbinderungsprozess in Zellen des als Grünling ausgebildeten Formkörpers eingeführt werden.2. The method according to claim 1, characterized in that the hollow bodies are introduced before the Entbinderungsprozess in cells of the molded body formed as a green body.
3. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass die Hohlköper nach dem Entbinderungsprozess in Zellen des als Bräunung ausgebildeten Formkörpers eingeführt werden. 3. The method according to claim 1, characterized in that the hollow bodies are introduced after the debinding process in cells of the shaped body formed as a tanning.
4. Verfahren nach einem oder mehreren der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass dann, wenn die zum Spritzgießen verwendete homogene Masse ausMetallpulver gewonnen wird, als Hohlköper metallische oder an ihrer äußeren Oberfläche metallisierte Hohlköper verwendet werden.4. The method according to one or more of claims 1 to 3, characterized in that when the homogeneous mass of metal powder used for injection molding is obtained, are used as a hollow body metallic or metallized on its outer surface hollow body.
5. Verfahren nach einem oder mehreren der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass dann, wenn die zum Spritzgießen verwendete homogene Masse aus Keramikpulver gewonnen wird, als Hohlköper keramische oder an ihrer äußeren Oberfläche keramisierte Hohlköper verwendet werden.5. The method according to one or more of claims 1 to 3, characterized in that when the homogeneous mass used for injection molding is obtained from ceramic powder, used as a hollow body ceramic or ceramicized on its outer surface Hohlköper.
6. Verfahren nach einem oder mehreren der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass Hohlkörper verwendet werden, die an die Größe und vorzugsweise Form der Zellen des Formkörpers angepasst sind.6. The method according to one or more of claims 1 to 5, characterized in that hollow bodies are used, which are adapted to the size and preferably shape of the cells of the shaped body.
7. Verfahren nach einem oder mehreren der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass die Hohlköper vor dem Einführen derselben in Zellen des Formkörpers auf eine Temperatur abgekühlt werden, die geringer als die Temperatur des Formkörpers ist. 7. The method according to one or more of claims 1 to 6, characterized in that the hollow bodies are cooled before introducing the same into cells of the shaped body to a temperature which is lower than the temperature of the shaped body.
EP07722126A 2006-04-06 2007-03-29 Method for production of a honeycomb seal Withdrawn EP2001621A2 (en)

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DE102006016147A DE102006016147A1 (en) 2006-04-06 2006-04-06 Method for producing a honeycomb seal
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