EP1854569B1 - Verfahren zur Herstellung von keramischen Kernen zum Gießen von Laufradschaufeln für Turbomaschinen - Google Patents

Verfahren zur Herstellung von keramischen Kernen zum Gießen von Laufradschaufeln für Turbomaschinen Download PDF

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Publication number
EP1854569B1
EP1854569B1 EP07290555A EP07290555A EP1854569B1 EP 1854569 B1 EP1854569 B1 EP 1854569B1 EP 07290555 A EP07290555 A EP 07290555A EP 07290555 A EP07290555 A EP 07290555A EP 1854569 B1 EP1854569 B1 EP 1854569B1
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EP
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Prior art keywords
core
machining
mould
overthickness
carried out
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EP07290555A
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English (en)
French (fr)
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EP1854569A1 (de
Inventor
Didier Guerche
Serge Prigent
Patrick Wehrer
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Safran Aircraft Engines SAS
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SNECMA SAS
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/10—Cores; Manufacture or installation of cores
    • B22C9/103—Multipart cores

Definitions

  • the present invention relates to the manufacture of parts such as metal blades of turbomachines, having internal cavities with complex geometry forming in particular cooling circuits, according to the lost wax casting technique.
  • the manufacture of such blades passes by the realization of a model in wax or other equivalent material which comprises an inner part forming a foundry core and the cavities of the vane.
  • a wax injection mold is used in which the core is placed and the wax is injected.
  • the wax model is then soaked several times in slips consisting of a suspension of ceramic particles to make a shell mold. We remove the wax and cook the carapace mold. Blading is achieved by casting a molten metal which occupies the voids between the inner wall of the shell mold and the core. Thanks to an appropriate germ or selector and controlled cooling, the metal solidifies in a desired structure.
  • DS columnar structure
  • SX monocrystalline structure
  • EX equiaxed solidification
  • the shell and the core are unchecked. It reveals the desired blading.
  • the foundry cores used are composed of a ceramic material with a generally porous structure. They are made from a mixture consisting of a refractory filler in the form of particles and a more or less complex organic fraction forming a binder. Examples of compositions are given in patents EP 328452, FR 2371257 or FR 2 785 836 A1 . As is known, casting cores are molded using, for example, injection molding. This shaping is followed by a debinding operation during which the organic fraction of the core is removed by a means such as sublimation or thermal degradation, depending on the materials used. A porous structure results. The core is then consolidated by heat treatment in an oven.
  • a finishing step is possibly necessary to eliminate and deburr the traces of joint planes and obtain the geometry of the core. Abrasive tools are used for this purpose. It may still be necessary to strengthen the core so that it is not damaged in subsequent cycles of use. In this case, the core is impregnated with an organic resin.
  • the geometry of the nuclei is always more complex, especially the walls of some areas are always thinner. As a result, filling limits are often reached and require the development of smoother pastes or the use of greater pressure for the filling of mold cavities.
  • Thick cores are more dimensionally stable due to pasta composition.
  • the binder-to-filler ratio and the proportion of fine and coarse ceramic particles are suitable.
  • the injection method of the prior art does not therefore make it possible to respond economically to changes in the design of the core, in particular to the need for thinning of the fine areas whose thickness is less than 0.4mm.
  • a known technique consists in producing ceramic cores in a mold with which the fine and / or critical zones are obtained either by the implementation of more fluid ceramic pastes or also by the modification of the injection parameters and in particular flows or pressures higher than the traditional conditions of use.
  • this technique has certain limitations.
  • the ceramic material has abrasive properties, and the shear generated by the new filling conditions is the cause of premature wear of the fine areas of the tools. This results in multiple periods of downtime and a high cost of maintaining the tools.
  • some fine areas freeze the filling front.
  • a method of manufacturing a foundry core comprising at least one zone or a thin wall with a thickness "e" of between 0.1 and 0.5 mm, on a trailing edge for example turbomachine blade, comprising shaping in a mold a mixture comprising a ceramic particle filler and an organic binder, extraction from the mold, debinding and a heat treatment of consolidation of the core.
  • This method is characterized in that in said mold is formed a core of which said zone is thickened with respect to the thickness "e" of an excess thickness E and that said excess thickness is machined after having extracted the core of the mold until said thickness "e” so as to create an opening channel sufficient for the flow of said mixture during its injection into the mold.
  • the machining operation can be performed before or after heat treatment.
  • the present invention results from a different approach relating to the reduction of the losses of charges. related to the definition of the cavity to be filled.
  • the invention acts on the diameter of passage in a narrow zone by increasing it so as to create an opening sufficient for the flow of the dough.
  • the costs of obtaining foundry cores are reduced. While the quantity of cores with injection-type and / or firing-type indications obtained by injection into a mold with a fine trailing edge reaches several tens of%, the solution allows a significant gain in quality and the obtaining cores having finer trailing edges than with the method of the prior art.
  • the target limit goes down to thicknesses of 0.1 mm
  • the machining of the thickened zone of the core is performed mechanically by milling, although it can also be operated by hand.
  • the core comprises from 80 to 85% mineral filler and 15 to 20% organic binder.
  • the composition advantageously corresponds to one of those described in the patent EP 328452 of the plaintiff. We seek a low fluid composition, which must have a small variation in shrinkage production series of cores.
  • the present invention thus allows the formulation of a single paste for all blade core fabrications, while the method of the prior art requires suitable pasta formulations.
  • the machining is performed by successive passages of the tool removing at each passage a specified material thickness, between 0.05 and 2 mm.
  • a specified material thickness between 0.05 and 2 mm.
  • the machining is performed by successive passages of the tool removing at each passage a specified material thickness, between 0.05 and 2 mm.
  • a milling cutter before baking the machining is performed by means of a milling cutter, while after baking the machining is performed by means of a tool, often diamond, by removal of material on a milling machine. at least three axes and preferably four or five axes.
  • This technique makes it possible to machine an uncured core from an existing CAD / CAM (computer-aided design and manufacturing) file without being penalized by the kernel withdrawals during the cooking step that are not always identical.
  • the uncured core has the dimensions of the mold in which it is made.
  • the nuclei before cooking are geometrically identical.
  • the machining step may also include a step of shelving the stud surface.
  • a blade 1 of turbine comprises a surface intrados IN an extrados surface EX, a leading edge BA and a trailing edge BF.
  • the blade comprises internal cavities, here 7: 1A to 1G.
  • the trailing edge comprises an opening 1H extending parallel thereto. It is fed from the last cavity 1G by a plurality of channels 1GH, calibrated, parallel to each other, for the exhaust of the cooling fluid which is air taken from the compressor.
  • the cavities are separated from each other by partitions: 1AB, 1BC, etc.
  • partitions 1AB, 1BC, etc.
  • a core 100 from a mold comprises a portion corresponding to the cavities of the blade 100A, a portion 100B corresponding to the cavities of the root of the blade and a portion 100C forming a gripping handle during manufacture.
  • a part 100D corresponding to what is designated bathtub in the jargon of the domain.
  • the trailing edge of the core ie the part referenced 100H leading to the formation of the cavity 1H of the figure 1 and the 100GH tenons leading to the formation of the 1GH channels of the figure 1 are shown on the figure 3 or the figure 4 .
  • the particular case of the first 100GH1 stud according to the invention is discussed below.
  • This core is produced by injection into a mold in which the fine areas formed by the tenons 100GH must be filled.
  • the usual technique is to design the mold with sub-pieces which have a certain mobility to be able to extract the core after injection of the material in the mold and its solidification. As explained above, the injection of these zones is all the more complicated as they are fine.
  • the object of the invention is to provide a core having such a complex structure without having to develop more fluid pastes or to increase injection parameters such as pressure or flow rate.
  • a modified mold is made, that is to say a mold whose core after molding has at least one thin zone which is thickened.
  • the thickened thin zone of the first tenon 100GH1 is obtained by suitably conforming the mold at this point to obtain such a thickened zone for the first 100GH1 stud.
  • the first tenon is the first seen from the foot of the dawn from which is injected the paste of the nucleus.
  • This part is shown in section on the Figures 8 and 9 .
  • On the figure 8 we see the extra thickness E of the tenon 100GH1 relative to the extrados surface 100Ex of the core 100.
  • the faces of the extrados side of the parts 100G and 100H are substantially in the same plane, with the exception of this extra thickness.
  • This extra thickness is determined according to the final thickness "e" that is desired for the 100GH1 post and the quality of the paste that is injected. This is to create an opening channel sufficient for the flow of the dough during the injection.
  • the contour of the extra thickness E takes into account the rounded edges of the post.
  • the rounded edges of the post can also be shelved by machining.
  • the paste used preferably comprises an organic binder associated with a mineral filler.
  • the mixture is made according to the teaching of the patent application EP 328452 .
  • the core has a good hold in hand and its constitution allows the work by means of a milling tool by removal of chips or abrasion.
  • the next step is to machine, in this blank core, or the thickened areas.
  • the machining is advantageously carried out by means of a tool as shown on the figure 7 .
  • This is a milling cutter 200 having a cutting end 200A and a thread or cutting edge helically along its rod 200B.
  • the cutter is moved perpendicular to the surface to be machined.
  • the speed of the tool as well as that of its displacement are fixed. This limits the effort on the material and prevents the tool from bending.
  • a five-axis type numerical control machine tool is preferably used, for example, three axes for positioning the milling cutter in the space and two axes for positioning the core. This machine can be easily programmed to automate the machining of the recesses if necessary.
  • the channels are of the size in particular of the thickness that they will form, with the close shrinkage, in the casting piece of the molten metal in the shell mold.
  • the core is machined before firing, the following treatments, known per se, are carried out in the process of manufacturing the foundry cores. debinding, that is to say the elimination of the organic binder.
  • the core is heated to a temperature sufficient to degrade the organic components it contains.
  • the other steps consist in heating the core to the sintering temperature of the ceramic particles that compose it. If additional consolidation is necessary, impregnation with an organic resin is carried out.
  • the figure 6a shows a phase of filling a mold of the prior art in hatched lines.
  • the thickness of the channels for the formation of the tenons in this example is 0.35mm.
  • a channel 60 has been arranged on the 100H zone side so that the supply is more direct. Indeed the injection pressure is lower; 85 units of pressure are enough. However the welding is still not satisfactory because the front of the paste remains fixed in the channels of the tenons.
  • the thickening of the first tenon of the core is represented mainly but it can be applied to all the tenons.
  • This technique therefore allows more generally the realization of core parts which are very thin and narrow as the part of the core located near the trailing edge and having channels for the passage of air escaping from the inside of dawn at the end of the cooling circuit and injected into the gas vein.
  • it can be extended to the machining of any part of the core for which the same problem of freedom of flow arises.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)

Claims (9)

  1. Verfahren zur Herstellung eines Formkerns (100) mit mindestens einer dünnen Zone mit einer Dicke "e" zwischen 0,1 und 0,5 mm einer Schaufelhinterkante einer Turbomaschine, umfassend die Formung eines Gemischs, das eine Ladung keramischer Partikel und ein organisches Bindemittel enthält, in einer Form, das Lösen aus der Form, die Entbinderung und eine thermische Behandlung zur Verfestigung des Kerns, dadurch gekennzeichnet, dass die Zone mit der Dicke "e" einen Zapfen (100GH) bildet für die Bildung eines Kanals für den Ablass der internen Kühlluft, in der Form ein Kern gebildet wird, wobei die Zone relativ zu der Dicke "e" um eine Überdicke E verdickt ist, derart, dass ein Kanal mit einer Öffnung erzeugt wird, die für das Fließen des Gemischs während seiner Einspritzung in die Form ausreicht, und dass die Überdicke bearbeitet wird, nachdem der Kern aus der Form gelöst wurde.
  2. Verfahren nach Anspruch 1, wobei die Bearbeitung vor dem Arbeitsgang der thermischen Behandlung erfolgt.
  3. Verfahren nach dem vorhergehenden Anspruch, wobei die Bearbeitung der Überdicke mechanisch durch Fräsen mit Abheben von Spänen erfolgt.
  4. Verfahren nach Anspruch 1, wobei die Bearbeitung nach dem Arbeitsgang der thermischen Behandlung erfolgt.
  5. Verfahren nach dem vorhergehenden Anspruch, wobei die Bearbeitung der Überdicke mechanisch durch Abschleifen erfolgt.
  6. Verfahren nach Anspruch 5, wobei die Bearbeitung mittels einer Fräse durch Abheben von Material auf einer Fräsmaschine mit mindestens drei Achsen und vorzugsweise mit vier oder fünf Achsen erfolgt.
  7. Verfahren nach Anspruch 1, wobei der Zapfen vom Fuß der Schaufel aus gesehen der erste ist, wo das Gemisch zum Befüllen der Form eingespritzt wird.
  8. Verfahren nach Anspruch 1, wobei die Bearbeitung einen Schritt für die strahlenförmige Ausbreitung der Oberfläche des Zapfens (100GH) umfasst.
  9. Verfahren nach einem der Ansprüche 1 bis 4 für die Herstellung eines Kerns, aufweisend eine Vielzahl von dünnen Zonen, wobei die Überdicke auf mehrere dünne Zonen aufgebracht wird.
EP07290555A 2006-05-10 2007-05-02 Verfahren zur Herstellung von keramischen Kernen zum Gießen von Laufradschaufeln für Turbomaschinen Active EP1854569B1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR0651682A FR2900850B1 (fr) 2006-05-10 2006-05-10 Procede de fabrication de noyaux ceramiques de fonderie pour aubes de turbomachine

Publications (2)

Publication Number Publication Date
EP1854569A1 EP1854569A1 (de) 2007-11-14
EP1854569B1 true EP1854569B1 (de) 2012-01-11

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Country Link
US (1) US7533714B2 (de)
EP (1) EP1854569B1 (de)
JP (1) JP5398964B2 (de)
CA (1) CA2587100C (de)
FR (1) FR2900850B1 (de)
RU (1) RU2432224C2 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3980202B1 (de) * 2019-06-06 2023-07-26 Safran Verbesserte giessform zur herstellung von keramischen kernen für turbinenschaufeln

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Publication number Priority date Publication date Assignee Title
FR2914871B1 (fr) 2007-04-11 2009-07-10 Snecma Sa Outillage pour la fabrication de noyaux ceramiques de fonderie pour aubes de turbomachines
JP2009140062A (ja) 2007-12-04 2009-06-25 Hitachi Ltd ストレージ装置とストレージシステム及びパス情報設定方法
FR2930188B1 (fr) * 2008-04-18 2013-09-20 Snecma Procede pour ebavurer une piece en matiere ceramique.
FR2933884B1 (fr) * 2008-07-16 2012-07-27 Snecma Procede de fabrication d'une piece d'aubage.
US20140166229A1 (en) * 2012-12-19 2014-06-19 United Technologies Corporation Minimization of Re-Crystallization in Single Crystal Castings
FR3022810B1 (fr) * 2014-06-30 2019-09-20 Safran Aircraft Engines Procede de fabrication d'un noyau pour le moulage d'une aube
FR3037830B1 (fr) * 2015-06-29 2024-02-16 Snecma Ensemble de moulage d'une aube de turbomachine, comprenant une portion en relief de grande section
FR3046736B1 (fr) 2016-01-15 2021-04-23 Safran Noyau refractaire comprenant un corps principal et une coque
FR3047767B1 (fr) * 2016-02-12 2019-05-31 Safran Procede de formation de trous de depoussierage pour aube de turbine et noyau ceramique associe
GB201610783D0 (en) * 2016-06-21 2016-08-03 Rolls Royce Plc Trailing edge ejection cooling
FR3059259B1 (fr) 2016-11-29 2019-05-10 Jy'nove Procede de fabrication d'un noyau ceramique de fonderie
DE102017122973A1 (de) * 2017-10-04 2019-04-04 Flc Flowcastings Gmbh Verfahren zur Herstellung eines keramischen Kerns für das Herstellen eines Gussteils mit Hohlraumstrukturen sowie keramischer Kern

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3980202B1 (de) * 2019-06-06 2023-07-26 Safran Verbesserte giessform zur herstellung von keramischen kernen für turbinenschaufeln

Also Published As

Publication number Publication date
JP5398964B2 (ja) 2014-01-29
FR2900850B1 (fr) 2009-02-06
CA2587100A1 (fr) 2007-11-10
US7533714B2 (en) 2009-05-19
EP1854569A1 (de) 2007-11-14
FR2900850A1 (fr) 2007-11-16
RU2007117300A (ru) 2008-11-20
CA2587100C (fr) 2014-02-25
RU2432224C2 (ru) 2011-10-27
US20070261811A1 (en) 2007-11-15
JP2007313562A (ja) 2007-12-06

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