EP3740332A1 - Procédé de fabrication d'un noyau céramique destiné à la fabrication d'une pièce coulée dotée de structures creuses, et noyau céramique - Google Patents

Procédé de fabrication d'un noyau céramique destiné à la fabrication d'une pièce coulée dotée de structures creuses, et noyau céramique

Info

Publication number
EP3740332A1
EP3740332A1 EP19701592.8A EP19701592A EP3740332A1 EP 3740332 A1 EP3740332 A1 EP 3740332A1 EP 19701592 A EP19701592 A EP 19701592A EP 3740332 A1 EP3740332 A1 EP 3740332A1
Authority
EP
European Patent Office
Prior art keywords
core
casting
ceramic
model
cnc
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Withdrawn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
EP19701592.8A
Other languages
German (de)
English (en)
Inventor
Wolfram Beele
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.)
Flc Flowcastings GmbH
Original Assignee
Flc Flowcastings 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 Flc Flowcastings GmbH filed Critical Flc Flowcastings GmbH
Publication of EP3740332A1 publication Critical patent/EP3740332A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C7/00—Patterns; Manufacture thereof so far as not provided for in other classes
    • B22C7/02—Lost patterns
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/02—Sand moulds or like moulds for shaped castings
    • B22C9/04—Use of lost patterns
    • B22C9/043—Removing the consumable pattern
    • 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
    • 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
    • B22C9/108—Installation of cores
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/18—Finishing
    • 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
    • B28B1/00—Producing shaped prefabricated articles from the material
    • B28B1/001—Rapid manufacturing of 3D objects by additive depositing, agglomerating or laminating of material
    • 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
    • B28B11/002—Apparatus for washing concrete for decorative purposes or similar surface treatments for exposing the texture
    • 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
    • B28B7/00—Moulds; Cores; Mandrels
    • B28B7/34—Moulds, cores, or mandrels of special material, e.g. destructible materials
    • B28B7/342—Moulds, cores, or mandrels of special material, e.g. destructible materials which are at least partially destroyed, e.g. broken, molten, before demoulding; Moulding surfaces or spaces shaped by, or in, the ground, or sand or soil, whether bound or not; Cores consisting at least mainly of sand or soil, whether bound or not
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y80/00—Products made by additive manufacturing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • This invention relates in the field of investment casting verbes a method for producing a ceramic core for preparing the preparation, by means of a ceramic mold, a casting with cavity structures, which is adapted to form the ceramic core, using a 3D model of digital geometry coordinates of the casting as well as improving a sol chen ceramic core.
  • the invention improves the manufacture of all types of high quality castings, because it allows, much less limited in complexity and geometrical inaccuracy than heretofore, the image of a lost model in a lost form with lost cores, not just without molds for making the cores They need to be able to directly map the geometry of the cores, as is usually the case with Ceramic Injection Molding (CIM).
  • CIM Ceramic Injection Molding
  • it makes it possible even with much larger casting and in particular special core dimensions and / or smaller-sized and more complex details, in particular the cavity structures and the core thereof, the latter such as undercuts, than previously possible.
  • Investment casting is known to take place using a lost Mo model in a lost form, which is formed in the form of a disposable ceramic coating of the model.
  • the known method comprises the following steps:
  • investment casting of hollow metal parts is a lost-mold process and is also referred to as lost wax casting.
  • the manufacturing process then typically takes place in the following typical steps:
  • a core of ceramic material is obtained by ceramic injection molding (CIM) into a multi-part reusable injection mold, followed by debinding, firing and finishing.
  • CIM ceramic injection molding
  • the core forms, complementary (as negative), the geometry of the cavity in the later casting.
  • a wax pattern is produced around the core by wax injection molding into a multi-part reusable injection mold.
  • the core is inserted in the wax injection mold.
  • the wax model depicts the outer contour of the metal part that is to be poured.
  • the wax model together with the core, or several such wax models, shall become a structure (a guard cluster), a complete continuous casting grape added, namely with feeders (sprues) and sprues, as well as filters and in the case of DS and SX casting, for example, with starters, seed selectors and Keimlei.
  • the wax model is melted out of the dish, typically in a steam autoclave at elevated pressure.
  • the shell is fired at temperatures between 700 ° C and 1100 ° C. As a result, residues of wax and other organic substances are burned out, and the ceramic shell material comes the required strength. Inspection and repair will ensure that the shell is free of damage.
  • the shell is removed from the castings by chemical leaching and machining.
  • the components are separated from the sprue system.
  • the core is removed from the cavity of the metal casting by chemical leaching in a pressure autoclave.
  • Investment casting is one of the oldest known forming processes that was first used thousands of years ago to produce more detailed crafts from metals such as copper, bronze and gold. Industrial investment casting became common in the 1940s, when World War II increased the need for custom-made parts made from specialized metal alloys. Today, investment casting is commonly used in aerospace and power plant construction to produce gas turbine components such as blades and vanes with complex shapes and internal cooling channel geometries.
  • the manufacture of a gas turbine blade or nozzle made of investment casting usually involves the production of a Kerami rule mold with an outer ceramic shell with an In nen description corresponding to the wing shape, and one or more ceramic, within the outer ceramic shell positioning th cores, corresponding to the internal cooling channels to be formed within the wing.
  • Molten alloy is poured into the ceramic mold, then cooled and cured.
  • the outer ceramic shell and ceramic core or cores are then removed mechanically or chemically to expose the molded airfoil having the external profile shape and the internal cooling channel (in the shape of the or each one of the ceramic cores).
  • a common technique for retaining cores in mold assemblies is the positioning of small ceramic pins formed integrally with the mold or the core or both which protrude from the surface of the mold to the surface of the core and serve to position and support the core insert.
  • the holes are filled in the casting, for example by welding or the like, preferably with the alloy from which the casting is formed.
  • the cores can also be held by core locks and core marks, which are part of the respective core. If required, additional ceramic pins can be attached for stabilization.
  • the holes of additional ceramic supports can be welded shut. Functionally necessary holes (such as for cooling) can be left open.
  • platinum wire pins that come out of the shell and abut the core surface. These become part of the casting structure, only the length of the platinum pins projecting beyond the metal surface is removed during trimming.
  • the ceramic core is typically brought by injection molding (Ceramic Injection Molding - CIM), or injection molding of ceramic core material into the desired core shape.
  • the plastic injection molding compound for the ceramic core material comprises one or more ceramic powder components, a plastic binder and optional additives that are injection molded into a suitably shaped core molding tool.
  • a ceramic core is conventionally manufactured by injection molding by first forming the desired core mold in respective mold halves of the wear-resistant hardened steel core by precision machining, and then halving the mold to an injection volume corresponding to the desired core shape, followed by injecting ceramic molding compound in the injection volume under pressure he follows.
  • the molding composition contains a mixture of ceramic powder and binder as described. After the ceramic molding compound is cured to a "green", the mold is opened to release the green ling.
  • the green body mandrel After the green body mandrel has been removed from the mold, it is debindered and fired at high temperature in one or more steps to remove the volatile binder and achieve the desired density and strength of the core for use in casting of metallic material such as a nickel or cobalt based superalloy. These are normally used to cast single crystal gas turbine blades.
  • the fired ceramic core When casting the hollow gas turbine blades with internaldekanä len the fired ceramic core is placed in a ceramic investment casting shell mold to form the internal cooling channels in the casting.
  • the fired ceramic core in investment casting of hollow blades typically has a flow-optimized contour with a leading edge and a trailing edge of thin cross-section. Between these front and rear edge regions, the core may have elongate but differently shaped openings to form interior walls, steps, baffles, ribs, and similar profiles for defining and forming the cooling channels in the cast turbine blade.
  • the fired ceramic core is then used in the manufacture of the outer shell mold in the known lost wax process, the ceramic core in a model forming tool angeord net and a lost model is formed around the core, by injection under pressure of model material such as wax, Ther moplast or the like in the mold in the space between the core and the inner walls of the mold.
  • model material such as wax, Ther moplast or the like
  • the complete ceramic casting mold is made by positioning the ceramic core within the assembled mold of finely worked hardened steel (referred to as a wax mold or wax mold). model tool) which defines an injection volume corresponding to the desired shape of the blade to then inject melted wax into the wax pattern mold around the ceramic core.
  • a wax mold or wax mold finely worked hardened steel
  • model tool which defines an injection volume corresponding to the desired shape of the blade to then inject melted wax into the wax pattern mold around the ceramic core.
  • the wax mold is opened and removed, and it is given the ceramic core wrapped free of a wax model, which now speaks the blade shape ent.
  • the temporary model with the ceramic core in it is again subjected to steps to build up the shell mold on it.
  • the model / core assembly is repeatedly dipped in ceramic slurry, excess slurry is allowed to drain, sanded with ceramic stucco and then air dried to build up several ceramic layers that form the shell on the assembly.
  • the resulting sheathed model / core assembly is then subjected to the step of, for example, removing the model by steam autoclave to selectively remove the temporary or lost model so that the shell mold with the ceramic core disposed therein remains.
  • the mold shell is then fired at a high temperature to produce an adequate Fes activity of the mold shell for metal casting.
  • Molten metallic material such as a nickel or cobalt base superalloy
  • a nickel or cobalt base superalloy is poured into the preheated shell mold and solidified to produce a cast polycrystalline or monocrystalline grain casting.
  • the resulting cast blade sheet still contains the ceramic core so as to form the internal cooling channels after removal of the core.
  • the core can be removed by leaching in hot concentrated caustic or other conventional techniques.
  • the hollow cast metalli cal flow profile casting has emerged.
  • the manufacture of the mold and core are limited in the ability to reliably form fine details with sufficient resolution.
  • the known systems are very limited.
  • the core inserts are typically molded parts made using conventional spraying or molding of ceramics, followed by suitable firing techniques. It is in the nature of these ceramic cores that the accuracy is much lower than that achievable in metal casting processes. There is much greater shrinkage in common ceramic casting compositions or flaws such as a high tendency to crack, blister and other defects. There is therefore a high defect and reject rate resulting from uncorrectable defects caused by defective cores and core positioning. Or at least a great deal of reworking is required to correct the castings that lie outside the tolerances, if they are a correction by reworking, grinding and the like, accessible at all. The productivity and efficiency of the fine casting process are essentially limited by these limitations.
  • cores are conventionally taken gefer by the CIM process (Ceramic Injection Molding, ceramic injection molding).
  • CIM Ceramic Injection Molding, ceramic injection molding.
  • the complete geometry of the core is imaged by the injection molding tool After removal from the mold, the core is debinded and with a specific temperature curve (FIG. Firing temperatures typically between 1000 ° C and 1300 ° C) burned.
  • Finishing the cores for example, for removing burrs or for other corrections as required, is known to take place in various ways:
  • the post-processing is typically done manually with diamond grinding tools.
  • the CNC-based post-processing with diamond grinding tools is also known.
  • the cores are fixed by mechanical stapling in a device.
  • Casting cores are hereby manufactured according to the CIM method, wherein certain geometric details in the form of machining allowance are included in order to enable the subsequent realization by CNC milling.
  • CIM Compute Injection Molding
  • the core production by CIM requires the use of highly complex injection molding tools.
  • the high complexity of these tools corresponds to the complicated cooling circuits (for example with serpentines, turbulators, outlet channels, ...) inside high-pressure turbine blades.
  • the production of these tools is associated with high costs (often several hundred thousand euros) and long lead times (usually several months) until a tool for a new component geometry is available.
  • Foundry products rotary and static high-pressure turbine blades
  • Iterative adaptations of the component geometry often lead to a necessary change in the tool in the design process, which requires a correspondingly long time.
  • a shortening of the iterative geometry adjustments can in particular contribute to shorten the development cycles of gas turbines, so that manufacturers of gas turbines can react more quickly to the changing requirements of the market.
  • a method for precision casting of hollow components is described.
  • a casting core is made from a blank of ceramic material subtractive by CNC machining.
  • the ceramic blank material is already burned and must not be burned after the final contour has been produced by CNC machining.
  • this core is embedded in model wax and the wax model outer contour is again produced by CNC machining.
  • the conformational positioning of the coordinate systems of Kern and Wax model within tolerances of +/- 0.05 mm or better is ensured by the special mechanical structure of the CNC machining device.
  • the advantages of this technology included the fact that highly complex and high-precision injection molding tools were no longer required for the production of investment casting wax models with ceramic cores, which directly reproduced the component geometry and thus eliminated the associated costs and lead times.
  • the CIM-finished core blank could be contoured larger, because more complex geometries could be produced precisely in the later CNC step.
  • the direct CNC machining of the core in the Endkon structure already dimensioneile distortion and rejection avoided, as they occur in the previously (and still today) usual production of the core by means of CIM.
  • the blank according to this improved technology of the prior art was, as stated, also produced as usual by means of CIM.
  • a method for the production of casting cores in particular with complex geometries for use in investment casting of hollow metal parts (according to a 3D model of digital Geomet riekoordinaten of the respective casting).
  • Cast cores are used to model the geometry of the cavities in the component interior, such as cooling circuits with complex geometries.
  • the (preferably casting tool-free) production of the cores according to the invention preferably requires in particular no injection molded tools.
  • the shaping is done in particular by CNC milling in particular not close to final form blanks from geeigne tem ceramic material - particularly preferably in combination with core sections, which are produced 3D printing technology - and / or in combination with core sections, the are also produced by casting (the latter in particular to make particular special cores with overall dimensions to produce that were previously not so producible in this size).
  • “Casting production” in the sense according to the invention is therefore in particular also the molding of a ceramic semifinished product of the core containing any casting step (for example ceramic slip casting or ceramic injection molding CIM) in particular (but not necessarily) with excess, in particular over the entire surface of the final contour ( according to the geometry coordinates - ie in particular the entire surface of the final contour, which belongs to the forming surface of the core during the final casting - which therefore does not necessarily include, for example, flange surfaces or positioning reference surfaces), and then especially without partial (and consequently possibly also without at all a) mapping of the final contour (which, in turn, means that the excess can also be an image of the final contour, that is, an excess that only follows the criterion of being somehow any larger than the exact nominal dimension of the K) ns (according to the geometry data of the core), and thus possibly without any other criterion for the excess, such as an excess of a certain size or of a certain minimum size or size with a certain tolerance - ie that the outer contour
  • the cast ceramic part for example, in this embodiment is not yet useful as a final contour-accurate core, but only as a semi-finished.
  • "3D printing-technical production” in the sense of the invention can also be referred to as generative or additive production of a ceramic molding, for example.
  • the blanks in the casting process according to the invention are manufactured, for example, by slip casting of ⁇ ßri gene ceramic suspensions and subsequent firing of the ceramic moldings.
  • the usual in the traditional foundry technology CIM (Ceramic Injection Molding, ceramic injection molding) for the production of cores is preferably not used.
  • This method offers over the traditional method we sentliche advantages in terms of lead time, with the case of the first casting cores can be made with changed geometries, as well as with respect to the dimensional tolerances of the finished casting cores.
  • a method for producing a ceramic core for preparing the ceramic core for the manufacture of a casting with cavity structures adapted to form the ceramic core is described, using a 3D model of digital geometry coordinates of the casting in the method in a preferred embodiment comprising the following steps:
  • the total core at the joints can be composed of at least two core component regions. They can either all be produced by casting, with the casting manufacturing comprising the following steps:
  • At least one core component area beyond the joining point can be produced by 3D printing technology, in particular in order to be able to produce smaller and more complex details there, such as undercuts, such as undercuts, as being feasible by casting.
  • the definition follows the preferred rule to perform particularly finely detailed details or particularly small-sized and complex details in 3D printing technology, for example, to gain greater freedom in terms of gap widths, undercuts and the like of (for example, in CNC milling problematic) details , Design of the counter body for the in Fig. B) designated Fügestruk structure, so design of the first matching second Fu structure of the at least one cut or joint, with the second, in particular 3D printed, core component area is joined to the CNC-machined core body , (In particular, pressure-free or low-pressure) casting a Kerami rule core blank, with an oversize based on the core according to the geometry coordinates.
  • the method and the core characterized in that the casting process manufacturing part in step 1. by Schlickergie day, Druckschlickergie day, cold isostati crushing, hot isostatic pressing, uniaxialem pressing, hot casting, low pressure injection molding, gel casting, or extrusion takes place and / or in step 1.
  • the CNC machining is CNC milling.
  • the further method comprises the following steps:
  • 3D printing of at least one core component area in ceramic printing technology It can aluminum oxides are printed, vorzugswei se, but for example, a silicate used who the, namely preferably a ceramic material based on silicate ceramic, for example fused silica (SiO 2), possible with additions of other oxides.
  • the 3D printing process can be, for example, stereolithographically (SLA), laser selectively (selective laser sintering, SLS), by powder bed pressure (binder jetting) - or alternatively according to a Sin terkar from a plastic mass by means of ceramic injection molding (CIM ) respectively.
  • the positive connection of the core parts can be adjusted, for example, directly by the firing cycle of the outer contour mass or by a speci fically modified heat treatment guide to the desired final strength.
  • a core body is defined as such, since this can absorb the main parts of the force introductions currency ing of ingrowth, the growth and burning ofmindkon structure, but also during the metal casting and the metal solidification and can endure. Therefore, a ceramic in the CNC-shaped core body can be specifically used here, which speaks ent in their properties to the known, CIM-made core materials or identifies even higher strengths with proven releasability after casting.
  • Finely detailed core geometries for example exit edge channels or (at least) second core shells in multi-walled cooling image designs ("onion principle"), can then be produced in 3D printing technology with joining surfaces, resulting in even finer details and geometrically sophisticated elements, for example with undercuts , allows.
  • the realization of the casting core geometry and / or -Endkontur according to the invention can therefore be done completely and exclusively by CNC machining.
  • the production of the blank is preferably by slip casting of aqueous ceramic suspensions with subsequent drying and firing:
  • a ceramic core material suitable for use in SX (single crystal), DS (Directional Solidification) or Equiaxed vacuum investment casting is made from known raw materials.
  • the properties mechanical strength, high-temperature resistance, thermomechanical behavior from room temperature to over 1550 ° C, for example dilatometry and creep resistance, porosity, solubility in concrete Centered liquor can be adjusted in a suitable manner, adjust the proportions and particle size distributions of the individual mineral components in a suitable manner.
  • the formation of cristobalite due to crystallization of the main component fused silica can be limited to a low level by the mineralogical composition in conjunction with the firing curve.
  • the geometry of the blanks does not need to be close to final contour.
  • the blank has a machining allowance in particular on all geometry-relevant points of the final contour of 1 mm or larger.
  • the geometry of the blanks can be optimized for the best possible uniform and repeatable ceramic properties.
  • the feedstock for shaping the blanks may be a water-based ceramic suspension ("other possible solvents.") This is mixed from the individual raw material components of the ceramic core material, namely meh reren usually powdered ceramic raw materials, in particular special fused silica as the main component, as well as other oxides and organic additives.
  • the shaping of the blanks takes place, preferably, not as in the traditional casting core production by CIM, but by pressure-free or low-pressure casting in plaster molds.
  • the ceramic shaped bodies are dried and fired with a defined temperature curve. Firing temperatures are typically between 1000 ° C and 1300 ° C. The ceramic shaped bodies thereby obtain their own shafts of density, porosity and mechanical strength as required. Water and all organic additives are removed. The moldings obtained in this way have compared to the prior art, a much better, ho mogenes microstructure and are poor or even free of internal clamping voltages. This voids and cavity freedom as well as the favorable internal stress state are ideal conditions for the successful CNC machining.
  • the properties of density, porosity and mechanical strength of the fired blanks can be selectively modified by appropriate additives in a suitable concentration in the ceramic suspension (feedstock, slurry). This makes it possible to adapt the starting material in order to enable and optimize the processing by means of CNC machining and in the subsequent precision casting process.
  • the properties of density, porosity and mechanical strength of the fired blanks can also be set selectively locally. This also makes it possible to locally adapt the starting material in order to enable and optimize the processing by means of CNC machining and in the subsequent fine casting process in certain areas.
  • a treatment with organic or inorganic substances take place, which penetrate the Poren sharehoff me of the ceramic material or form a surface layer. These substances modify the mechanical, thermomechanical and chemical properties of the ceramic in a suitable manner.
  • the fen through the ceramic molding in a defined orientation which is favorable for the CNC machining.
  • the fixation of the blank for CNC machining is vorzugswei se by a device.
  • the device can fi x the blank at multiple locations or from multiple sides or from one side, thereby providing sufficient mechanical stability even on delicate areas of the core geometry.
  • the fixation of the blank for CNC machining is not mechanically by a releasable connection force, form and / or frictionally, but cohesively by tying with means of a suitable compound compound with the device.
  • the fixation of the blank for CNC machining can be temporarily supplemented by a removable investment material that adapts to the contour, or by temporary supports.
  • a removable investment material that adapts to the contour, or by temporary supports.
  • this mass can be used, which connects at the same time firmly both with the ceramic core material and with the metal (typically eg steel or aluminum) Vorrich the device.
  • the mass should not be attacked by the operating media possibly used during CNC machining (eg compressed air, oils, water, anti-corrosion agents). It is suitable, for example, "Nigrin 72111 Performance Filling Spatula".
  • the machining is done by CNC milling, ie in particular by means of a milling tool with defined cutting geometry and / or by CNC grinding, ie in particular by means of a grinding tool with abrasive coating.
  • the CNC tools are preferably, according to the machining of the abrasive core material wear with minimized tool wear, those with cutting polycrystalline diamond (PCD) or cubic boron nitride (CBN). Because possible deviations from the dimensional tolerances of the final contour as a result of ver schl redesign employment changes the cutting edge geometry can be avoided or kept low.
  • PCD polycrystalline diamond
  • CBN cubic boron nitride
  • the foundry technical use of an inventively Herge presented form includes, for example, single crystal, DS and Equiaxed vacuum investment casting only for example of turbine components made of nickel-based alloys.
  • An essential advantageous feature of the method according to the invention is the shaping only on the finished fired Kernmate rial.
  • a very high dimensional accuracy of the finished cores within within tolerances in the range ⁇ +/- 0.1 mm of the final contour he be targeted.
  • the above-described disadvantages in the traditional core production by means of CIM with respect to the dimensional stability and the yield are thereby eliminated.
  • the fully CNC-based realization of the core end contour also makes it possible, based on a newly obtained geometry, to produce first cores with a very short lead time, which are suitable for precision casting of investment-grade components without restrictions. Minor changes to an existing component geometry can now be implemented by simply modifying CAM and CNC programs without changing fixtures or blank geometry. The reaction times for such minor changes are therefore very short.
  • the core product has, in addition be particularly advantageous, on a significantly improved Materialhomo gentician and / or additionally locally adjusted special Materi aleigenschaften.
  • the possible way of fixing the Keramikroh- Lings in the CNC device also allows a significantly improved quality and improved ver the inventively manufactured cores.
  • Figure 1 to 7 are schematic views of successive
  • Steps of a method according to the invention for producing a casting the cavity structure has ren.
  • FIGS. 8a to c are schematic views of Ker nen invention from the side ( Figure 8a) and in two alterna tive sections,
  • Figure 9a and b are schematic views of an inventive
  • FIG. 7 These (highly schematic) figures illustrate the fabrication of a casting 2 (FIG. 7) having void structures 3, 3 '(using a 3D model, a three-dimensional CAD model of digital geometry coordinates, of the casting) on the example of a gas turbine blade 2 7 with internal cooling channels 3, 3 ', including the production of a ceramic core 4, 4' ( Figure 1, also using the 3D model of the casting).
  • the ceramic core 4, 4 ' is adapted to form the hollow space structures 3, 3'.
  • a core 4, 4 ' shown in FIG. 1 is produced according to the 3D model. 2
  • the core 4, 4 ' posi tioned in a processing holder 6.
  • Around the core around a vessel (volume) 8 is arranged and also positioned in the processing holder 6 and be strengthened.
  • model wax 10 is poured around the core 4 into the volume 8 in a next method step.
  • the volume 8 is larger than the casting cubature 12, and thus the model wax 10 is poured into the volume 8 around the core 4 on all sides, beyond the casting cubature 12.
  • the spatial position of the casting cubature 12 in the volume 8 is determined according to the 3D model of the cast component 2 (FIG. 7) by the position of the core 4 in the machining fixture 6.
  • the model material 10 is now in a next process step solidified around the core 4 and removed the volume 8.
  • the outer contour of a temporary (lost) model 14 of the casting 2 (FIG. 7) is made around the core 4, from which it stared model material 10 according to the 3D model by CNC. Milling (not shown).
  • the resulting wax model 14, with the core 4 therein is removed from the machining fixture 6 (for example, by releasing an adhesive bond or severing ceramic core material at the transition to the fixture).
  • the processing fixture 6 is no longer present in the next steps. Instead, the wax model 14 with core 4 is mounted on a so-called "wax cluster" (not shown), which images the gating system and mechanically fixes the model.
  • a ceramic mold 16 is carried on the outer contour of the lost model 14, thereby forming a positioning connection 18 of the ceramic mold 16 via a core mark 18 with the core 6, so that the ceramic mold 16 With respect to the core 4 dimensionally ge according to the 3D model (not shown) of the cast component 2 (Fig. 7) by the core mark 18 remains positioned.
  • the lost model 14 is removed from the ceramic mold 16 around the core 4 (both of which are further held by the locating joint 18 and positioned relative to each other).
  • a hollow mold 20 is ent between the surface of the ceramic core 4 and the inner surface 14 of the ceramic mold 16.
  • the actual (after casting to be destroyed, so "lost") mold is fertigge presents.
  • molten metal (not shown) is poured into it. Subsequently, this is allowed to cool. The molten metal (not shown) solidifies to the solid casting 2, which is visible in FIG. 7 in a next step (by removing the lost ceramic mold 16 and the kera mixing core 4 of the casting 2) and as a component with one (the core 4 exactly corresponding) cavity structure 22 is available with great dimensional accuracy.
  • the method of manufacturing the ceramic core 4, 4 'shown in FIG. 1 now serves, so to speak, to prepare the actual production by casting (according to FIGS. 6 and 7) of the casting 2 with cavity structures 3, 3', as described above, by inserting a initial process section for making the core 4, 4 'as a constituent of the (lost) mold 16 of the casting 2, to which the subsequent process sections (according to FIGS. 2 to 6) for producing the (lost) mold 16 of the casting 2 follow - and thereby orient geo metrically with high precision as described.
  • This particular method of manufacturing the ceramic core 4, 4 'shown in FIG. 1 and also the cores 4, 4' according to FIGS. 8-10 is based on the production of the ceramic core from (at least) two subregions 4 and 4 '. and comprises the following steps: a) producing the first subregion 4 of the ceramic core - by casting - including at least one first joining structure 24 in a surface of the subregion; b) producing at least a second portion 4 'of the ceramic core - namely 3D printing technology - finally at least one second, to the first Fu structure 24 matching joint structure 26 in a Oberflä surface of the second portion 4'; c) joining the at least one first portion 4 and the at least one second portion 4 'of the core to the mating joining structures 24, 26 to the core according to geometry coordinates of the casting.
  • the casting production comprises the following steps: i. Pressure-free or at least low pressure casting a Kerami's blank of the core portion 4 pour by slip, Druckschlickergie day, cold isostatic pressing, hot isostatic pressing, uniaxial pressing, H adoptedgie Shen, low-pressure injection molding, gel casting or Extrudie ren, with excess based on the Geometriekoor coordinates of the core ; ii. CNC machining, in particular CNC milling of the core, according to the 3D model in a first CNC machining process.
  • At least one cut or joint 28 is defined, to which the Kerngeometriedetails casting technically as a one-piece core component area 4 or core body 4 (as I said, especially by means of a core blank and its subsequent CNC machining) to be made len.
  • the entire core 4, 4 'at the joints 28 from at least two core component regions 4, 4' are composed.
  • the core component regions 4, 4 ' can either all be produced by casting (for example in order to be able to exceed dimensional limits, for example the manufacturability of a one-piece overall core).
  • At least one core component area 4 'beyond the joint 28 is (as shown in the example Beispie len) 3D-produced by printing, in particular smaller sized and more complex details 29 (the latter as for example undercuts - or more complex cavities of the core (29 in Thus, webs or other massivities of more complex shape can be produced in the cavity (to be formed later by the core) of the component to be produced than can be realized by casting.
  • the selection of the core component regions 4 ', which are executed as "3D ceramics" in 3D printing technology, follows the preferred rule, For example, in order to obtain greater freedom in terms of gap widths, undercuts and the like of details (especially problematic in CNC milling), particularly finely detailed details or particularly small dimensioned and complex details can be performed in 3D printing technology.
  • the two core component areas are joined.
  • Preparatory steps can be included (alternative or cumulative): cleaning, drying, deburring, chemical surface treatment, application of adhesive 30.
  • FIG. 10 Shown schematically in FIG. 10 are variously designed joints 28 of the core component regions 4 and 4 'in positive engagement with clearance fit in the conical or wedge seat: without adhesion (FIG. 10a); with adhesion 30 (FIG. 10 b ff), namely in a cavity 32 formed in the joining surface 28 (FIG. 10 b); with adhesion in augmentedför shaped chambers 34, which cross the joining surface 28 (Figure 10c); with spacers 36, the form-fitting in grooves 38 sitting the joining contours 24, 26 keep at a distance for the adhesive 30, wel holes filled with the adhesive 30 ( Figure lOd).
  • the core component regions 4 and 4 ' can also be "locked" in a form-fitting manner, for example by a dovetail contour 40, (Fi gur 10e) and then possibly additionally glued.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)

Abstract

L'invention concerne un procédé pour fabriquer un noyau céramique (4, 4') - ainsi qu'un noyau fabriqué au moyen du procédé - pour préparer la fabrication d'une pièce coulée dotée de structures creuses, le noyau céramique étant conçu pour mouler ces dernières, à l'aide d'un modèle 3D de coordonnées géométriques numériques de la pièce coulée, le procédé comportant les étapes suivantes : a) la fabrication par technique de coulage d'au moins une première sous-région (4) du noyau céramique comprenant au moins une première structure d'assemblage (24) dans une surface de la sous-région ; b) la fabrication par technique de coulage ou technique d'impression 3D d'au moins une seconde sous-région (4') du noyau céramique comprenant au moins une seconde structure d'assemblage (26) correspondant à la première structure d'assemblage dans une surface de la sous-région, la fabrication par technique de coulage comportant les étapes suivantes : i. le coulage sans pression ou à faible pression d'une ébauche de noyau céramique, et ce, avec interférence par rapport au noyau (4, 4') conformément aux coordonnées géométriques ; ii. le traitement à commande numérique du noyau (4, 4') conformément au modèle 3D dans un premier procédé de traitement à commande numérique ; c) l'assemblage de ladite première sous-région et de ladite seconde sous-région du noyau au niveau des structures d'assemblage correspondant l'une à l'autre pour obtenir le noyau conformément aux coordonnées géométriques de la pièce coulée.
EP19701592.8A 2018-01-17 2019-01-17 Procédé de fabrication d'un noyau céramique destiné à la fabrication d'une pièce coulée dotée de structures creuses, et noyau céramique Withdrawn EP3740332A1 (fr)

Applications Claiming Priority (2)

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DE102018200705.5A DE102018200705A1 (de) 2018-01-17 2018-01-17 Verfahren zur Herstellung eines keramischen Kerns für das Herstellen eines Gussteils mit Hohlraumstrukturen sowie keramischer Kern
PCT/EP2019/051169 WO2019141783A1 (fr) 2018-01-17 2019-01-17 Procédé de fabrication d'un noyau céramique destiné à la fabrication d'une pièce coulée dotée de structures creuses, et noyau céramique

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EP3740332A1 true EP3740332A1 (fr) 2020-11-25

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US (1) US20200338630A1 (fr)
EP (1) EP3740332A1 (fr)
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GB201901550D0 (en) * 2019-02-05 2019-03-27 Rolls Royce Plc Method of investment casting chaplet
CN110523927B (zh) * 2019-09-30 2023-09-05 华南农业大学 一种砂芯3d打印机及其打印方法
CN112661521B (zh) * 2020-12-22 2022-05-10 西安鑫垚陶瓷复合材料有限公司 一种陶瓷基复合材料零件沉积校型工装及方法
CN113211601B (zh) * 2021-05-10 2022-09-06 昆山奥维三维科技有限公司 一种陶瓷芯及其制备方法和应用
CN114227899B (zh) * 2021-12-20 2023-04-18 中国工程物理研究院材料研究所 一种金属氢化物陶瓷薄壁管与不锈钢薄壁管复合的方法
CN114274536B (zh) * 2021-12-21 2023-10-03 东北电力大学 联合3d打印与类消失模铸造的叠层式人工肌肉构建工艺
CN114433789B (zh) * 2022-01-27 2023-08-25 清华大学 一种易脱芯陶瓷型芯及其制备方法

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DE102018200705A1 (de) 2019-07-18
WO2019141783A1 (fr) 2019-07-25

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