EP2060342A1 - Appareil et procédé de moulage directionnel à métal liquide - Google Patents

Appareil et procédé de moulage directionnel à métal liquide Download PDF

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Publication number
EP2060342A1
EP2060342A1 EP08168814A EP08168814A EP2060342A1 EP 2060342 A1 EP2060342 A1 EP 2060342A1 EP 08168814 A EP08168814 A EP 08168814A EP 08168814 A EP08168814 A EP 08168814A EP 2060342 A1 EP2060342 A1 EP 2060342A1
Authority
EP
European Patent Office
Prior art keywords
mold
mold assembly
channel
shell
chill plate
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Withdrawn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
EP08168814A
Other languages
German (de)
English (en)
Inventor
Shyh-Chin Huang
Andrew John Elliott
Michael Francis Xavier Gigliotti Jr.
Adegboyega Masud Makinde
Roger J. Petterson
Stephen Francis Rutkowski
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.)
General Electric Co
Original Assignee
General Electric Co
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
Priority claimed from US11/942,198 external-priority patent/US20090126894A1/en
Priority claimed from US11/942,196 external-priority patent/US20090126893A1/en
Application filed by General Electric Co filed Critical General Electric Co
Publication of EP2060342A1 publication Critical patent/EP2060342A1/fr
Withdrawn legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D27/00—Treating the metal in the mould while it is molten or ductile ; Pressure or vacuum casting
    • B22D27/04—Influencing the temperature of the metal, e.g. by heating or cooling the mould
    • B22D27/045—Directionally solidified castings

Definitions

  • the present disclosure generally relates to an apparatus and processes for casting an article, and more specifically, to an apparatus and processes for directionally casting an article.
  • Certain components such as turbine blades and stator vanes for gas turbine engines, are often manufactured using a directional solidification casting.
  • a shell mold is specifically configured for the particular component being cast, such as the turbine engine blade or vane.
  • a mold assembly generally, includes a shell mold (cavity) and a chill plate, wherein the chill plate is at the lowest position of the mold assembly.
  • the entire mold assembly is then raised into a heating chamber where it is preheated, and subsequently filled with a desired superalloy in a superheated liquid melt condition.
  • the bottom of the mold assembly is then subjected to preferential cooling, immersed into a liquid metal cooling bath, such as molten tin or aluminum, to create a large temperature gradient in the casting and commence the unidirectional solidification process necessary for a desired crystal formation, which travels upwardly through the mold assembly.
  • a liquid metal cooling bath such as molten tin or aluminum
  • the mold is lowered into the liquid metal cooling bath at a controlled rate to translate the thermal gradient across the part, thus resulting in directional solidification.
  • the mold assembly is removed from the bath, furnace, and housing.
  • a typical mold assembly has at its bottom a chill plate adapted to effect cooling of the shell mold by conducting heat from the shell mold to the liquid metal bath.
  • a chill plate adapted to effect cooling of the shell mold by conducting heat from the shell mold to the liquid metal bath.
  • one of the problems with current designs is the effectiveness of the seal between the chill plate and the shell mold.
  • Current designs are prone to leakage, i.e., ingress of liquid metal into the mold assembly and egress of cast metal from the mold assembly into the cooling bath. Without an effective seal, the cast metal is oftentimes subject to surface attack, e.g., oxidation, hot corrosion, and thermal fatigue, by the liquid metal from the melt. In addition, the melt metal will also get contaminated from the escaped cast metal. Therefore, without an effective seal, the reliability of the casting process is compromised.
  • the process for directionally casting an article comprises compressing a seal member intermediate a mold chill plate and a mold assembly, wherein the seal member circumscribes a shell mold in the mold assembly; filling the shell mold in the mold assembly with molten metal; immersing the mold assembly into a liquid metal cooling bath at a controlled rate from a first position to a second position of the mold assembly; and transmitting heat from the mold assembly to the liquid metal cooling bath to directionally solidify the molten metal as the molten metal assembly is immersed from the first position to the second position of the mold assembly.
  • the process for sealing a shell mold in a mold assembly comprises forming a channel in a bottom surface of the mold assembly, wherein the channel circumscribes the shell mold; placing a first ring in the channel; and securing the mold assembly to a mold chill plate and compressing the first ring against the mold chill plate and the mold assembly.
  • the process for directionally casting an article comprises securing a mold assembly to a chill plate, wherein the mold assembly comprises an opening for receiving molten metal, at least one shell mold in fluid communication with the opening, and a skirt laterally extending from at least one shell mold, wherein the skirt comprises a channel disposed in a bottom surface and configured to surround the at least one shell mold, the channel further comprising a ring formed of a compressible material disposed therein, wherein the chill plate comprises a boss having a shape complementary to the channel of the mold assembly; heating the mold assembly; filling at least one shell mold in the mold assembly with molten metal; lowering the chill plate and the mold assembly into a liquid metal cooling bath at a controlled rate from a first position to a second position of the mold assembly; and transmitting heat from the mold assembly to the liquid metal cooling bath to solidify the molten metal as the mold assembly transitions from the first position to the second position.
  • an apparatus for directionally casting an article comprises a mold assembly, which comprises an opening for receiving molten metal, at least one shell mold in fluid communication with the opening, and a skirt laterally extending from the at least one shell mold wherein the skirt comprises a selected one of a channel and a boss disposed in a bottom surface that is configured to surround the at least one shell mold; and a chill plate which comprises the other of the selected one of the channel and the boss having a complementary shape such that the boss is seated within the channel to define a seal about the at least one shell mold when the mold assembly is attached to the chill plate.
  • FIG. 1 shows a cutaway perspective view of a mold assembly 10 sitting on a chill plate 12.
  • the mold assembly 10 generally includes an opening 14, e.g., funnel in fluid communication with runners 16 that are in fluid communication with one or more shell mold 18.
  • the shell molds i.e., cavities, define the shape of the part to be cast.
  • a mold assembly having more than one shell mold is often referred to as a cluster mold assembly.
  • a skirt 20 extends laterally across a bottommost portion of the mold assembly.
  • a groove (i.e., channel) 22 is formed in a bottom surface of the skirt such that the shell molds 18 are contained within a perimeter defined by the groove, i.e., the channel circumscribes the shell mold.
  • the chill plate 12 includes a substantially planar surface 24 and a boss 26 radially circumscribing about a perimeter of the surface 24.
  • the boss 26 has a shape complementary to the groove 22 such that the boss is seated within the channel prior to mechanical fastening, e.g., by a mechanical connector such as but not limited to tie rods, cords, clamps, or any other fixture that can mechanically perform the clamping function required while sustaining the high temperatures of the furnace and melt.
  • the shape of the boss 26 or the channel 22 is not intended to be limited and is generally configured to surround the shell mold 18 or one or more shell molds in the case of a cluster mold assembly.
  • Surface 24 also serves to enclose an opening of the shell mold that faces the chill plate, i.e., at a bottom surface of the mold assembly (shown more clearly in FIG. 7 ).
  • a support shaft 28 is coupled to the chill plate 12 to effect lowering of the mold assembly 10 into a liquid metal cooling bath.
  • the groove can be formed in a top surface of the chill plate and a boss formed in a bottom surface of the mold assembly, wherein the groove and boss have complementary shapes such that the boss seats within the groove when the mold assembly and the chill plate are fastened together.
  • multiple grooves and bosses can be formed in an opposing relationship e.g., a labyrinth type seal.
  • the mold assembly may be utilized to cast many different articles, it is believed that it will be particularly advantageous to cast turbine engine blades, e.g., airfoils, or vanes formed of a nickel-based, iron-based, and/or cobalt-based superalloys.
  • the method and apparatus is not to be limited to the casting of any particular article or metal.
  • the apparatus and method can be used during the casting of articles formed of titanium and/or other metals having any desired configuration.
  • cluster mold assemblies such as the one shown, multiple parts such as blades or vanes can be simultaneously cast using multiple shell molds. The parts can be the same or different.
  • the mold assembly 10 Prior to use, the mold assembly 10 is mechanically fastened to the chill plate 12.
  • a furnace 30 encapsulates the mold assembly 10 and is of a conventional design.
  • the furnace is not intended to be limited to any particular type and the illustrated furnace is exemplary.
  • the furnace can include coils 32 that are energized to provide heat within an evacuated space of the furnace in which the mold assembly is seated.
  • molten metal is poured into the mold through the funnel 14 to fill the mold cavities 18.
  • the illustrated furnace can include an additional funnel 34 or opening that is in coaxial alignment with the funnel 14. The space around the additional funnel or opening is often evacuated to prevent contamination of the molten metal as it is poured into the mold assembly 10.
  • a liquid metal cooling bath 36 is disposed beneath the mold assembly 10 and chill plate 12.
  • the liquid metal cooling bath is maintained at a temperature below the solidus temperature of the metal in the mold.
  • the chill plate 12 ensures the directional solidification of the casting as it cools.
  • the directional solidification of the molten metal in the mold is particularly advantageous when it is desired to cast a metal article with a columnar grain or to cast the metal article as a single crystal.
  • Cast material can also solidify in the runners 16. In some instances, the solidified runner castings are intended to be part of the final cast part; the rest of the time they are discarded or recycled.
  • the mold assembly 10 and chill plate 12 further includes a ring 40, i.e., seal member, formed of a ceramic or metal material.
  • the channel 22 would have a length and height dimension effective to accommodate the boss and the ring.
  • the ring can be configured to have a smaller diameter than the boss such that it abuts an interior surface of the boss.
  • the ring can have a larger diameter than the boss such that it abuts the exterior surface of the boss.
  • inner and outer rings relative to the boss can be utilized.
  • FIGS. 2-4 illustrate the various arrangements of the ring 40. Although reference is made specifically to a ring, it should be noted that the shape can vary and is not intended to be limited. Suitable shapes include circular, elliptical, and/or any polygonal shape.
  • FIG. 5 illustrates an alternative embodiment for providing a seal between the mold assembly 10 and the chill plate 12.
  • the chill plate 12 includes an annular shaped channel 42 into which the ring 40 is disposed.
  • the ring 40 can be dimensioned to protrude from the planar surface 24 of the chill plate and extend into the channel 22 of the skirt 20 upon attachment of the mold assembly 10 to the chill plate 12. That is, the ring 40 has a cross-sectional diameter that is larger than the height dimension of the annular channel in the mold assembly.
  • the channel 22 can be chamfered as may be desired for some applications.
  • the planar surface 24 of the chill plate 12 is free from the boss or the channel as described above.
  • the ring 40 is disposed within the annular channel 22 in the skirt 20 of the mold assembly 10 such that upon attachment of the mold assembly 10 to the chill plate 12, the ring 40 compresses against the planar surface to provide an effective seal.
  • the diameter of the ring is slightly oversized so as to provide a compressive force against the planar surface when the mold assembly and the chill plate are mechanically fastened.
  • the ring can be coated with a material effective to prevent relatively small leaks in this or any of the other embodiments where applicable.
  • the ring can be coated with a ceramic-based paste.
  • the ring can be formed of ceramics, metals and the like. Suitable materials include, without limitation, silicon carbide, carbon, graphite, alumina, aluminum, copper, and the like.
  • the ring can be formed of a number of filaments, which may be wound together into a single unit or left separately in a bunch.
  • the ring can be configured to have a solid cross section or may be configured to have a hollow cross-sectional structure.
  • the rope can be made of ceramic-fiber filaments, for example, alumina-boria-silica fibers with high strength and low shrinkage up to 2200 degrees Fahrenheit (1204 degrees Celsius).
  • a cloth made of ceramic fibers can be used. Some specific materials for the cloth are alumina, alumina-silica fibers, or alumina-boria-silica fibers. The cloth can be specifically layered, rolled, or twisted. A specific example of a ceramic cloth, also sold by 3M, is a cloth trademarked under the name "Nextel.”
  • the ring can be formed of ductile metals such as aluminum, copper, and the like, that can be compressed as may be desired for some applications so as to provide conformality when compressed between the mold and the chill plate.
  • the metal is selected to have a melting point higher than that exposed to during the liquid metal casting process.
  • FIG. 7 illustrates a sectional view of an exemplary cluster mold assembly that includes four shell molds 18.
  • the seal as described in the embodiments shown in relation to FIGS 1-6 is disposed around each of the mold openings provided by the shell mold 18. In this manner, each individual mold will be sealed and prevent egress of metal within the mold or ingress of metal from the liquid metal cooling bath. Alternatively, selected ones of the mold openings provided by the individual shell mold 18 in a cluster mold assembly apparatus can be sealed in this manner.
  • two of the shell molds in a four shell mold cluster assembly apparatus can be sealed with one of the seals and the remaining shell molds can be individually or collectively sealed.
  • the various combinations of seal arrangements are not intended to be limited.
  • the sealing arrangement is created by mechanically compressing the ring, if present, or by aligning the boss in the chill plate with the correspondingly shaped annular channel of the mold assembly as previously described.
  • the mold assembly including the shell molds 18, is placed on the chill plate 12 and moved into the furnace 30.
  • the exemplary furnace includes coils 32 that can be energized to heat the mold assembly 10. Molten metal is then poured though opening 34 into the preheated mold assembly through the funnel 14 in a known manner. The furnace maintains the molten metal at a temperature above the solidus temperature of the metal. The mold assembly is then lowered at a controlled rate into the liquid metal cooling bath 36. To lower the mold from the furnace, the support shaft 28 coupled to the chill plate 12 is moved downward. This causes the chill plate to move into the liquid metal cooling bath. As the lower end of the mold assembly is cooled, the molten metal solidifies upward from the lower end portion of the mold assembly to the upper end portion of the mold assembly.
  • the seal configurations as described herein prevents molten metal from running out of the shell mold or the liquid-metal cooling agent from flowing inside of the shell mold before solidification of the cast metal.
  • An exemplary embodiment can provide a tight seal between the shell mold and its supporting chill plate. The tight seal is necessary to prevent molten metal from leaking out of the mold before the completion of solidification, or, conversely, the cooling medium from ingression into the molds and reaction with the casting.
  • This embodiment of this seal has several aspects including surface features in the shell and chill plate, a gasket, and a configuration of seals around mold openings.
  • productivity of a liquid-metal-cooled directional solidification process is beneficially increased. Better sealing decreases the ingress and egress of undesired metal into the shell mold 18 and liquid metal cooling bath resulting in less leaking and fewer corrupted castings.
  • the casting yield of a liquid metal cooled casting process will be improved and more efficient by minimizing shell mold run-out and producing castings with minimal surface attack by the cooling medium.
  • the increased yield provided by the embodiments mentioned above will make liquid metal casting cost competitive with conventional casting processes, a critical step in the commercialization of the liquid metal casting process.
  • each shell mold opening will have increased protection because of the individual seal configurations and possible redundancy.
  • the term “comprising” means various compositions, compounds, components, layers, steps and the like can be conjointly employed in the present invention. Accordingly, the term “comprising” encompasses the more restrictive terms “consisting essentially of” and “consisting of.”

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
EP08168814A 2007-11-19 2008-11-11 Appareil et procédé de moulage directionnel à métal liquide Withdrawn EP2060342A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US11/942,198 US20090126894A1 (en) 2007-11-19 2007-11-19 Liquid metal directional casting apparatus
US11/942,196 US20090126893A1 (en) 2007-11-19 2007-11-19 Liquid Metal Directional Casting Process

Publications (1)

Publication Number Publication Date
EP2060342A1 true EP2060342A1 (fr) 2009-05-20

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EP08168814A Withdrawn EP2060342A1 (fr) 2007-11-19 2008-11-11 Appareil et procédé de moulage directionnel à métal liquide

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EP (1) EP2060342A1 (fr)
JP (1) JP2009125809A (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3062588A1 (fr) * 2017-02-06 2018-08-10 Safran Aircraft Engines Systeme de raccordement d'une sole de four a une embase de moule carapace pour la fabrication d'un element aubage

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6288641B2 (ja) * 2014-03-07 2018-03-07 三菱重工業株式会社 鋳造装置

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4673021A (en) * 1986-01-28 1987-06-16 Trw Inc. Method and apparatus for casting articles
EP0477136A1 (fr) * 1990-09-21 1992-03-25 Sulzer Innotec Ag Procédé pour fabriquer des pièces coulées par solidification dirigée ou monocristalline
DE19647313A1 (de) * 1996-11-13 1998-05-14 Siemens Ag Verfahren und Vorrichtung zum gerichteten Erstarren einer Schmelze
US6367538B1 (en) * 1998-12-21 2002-04-09 General Electric Company Mold and mold basket for use in uni-directional solidification process in a liquid metal bath furnace
EP1321208A2 (fr) * 2001-12-21 2003-06-25 Mitsubishi Heavy Industries, Ltd. Procédé et dispositif de coulée à solidification directionnelle
US20040079510A1 (en) * 2002-10-29 2004-04-29 Pcc Airfoils, Inc. Method and apparatus for use during casting
US20050045300A1 (en) * 2003-09-02 2005-03-03 General Electric Company Apparatus and method for producing single crystal metallic objects

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4673021A (en) * 1986-01-28 1987-06-16 Trw Inc. Method and apparatus for casting articles
EP0477136A1 (fr) * 1990-09-21 1992-03-25 Sulzer Innotec Ag Procédé pour fabriquer des pièces coulées par solidification dirigée ou monocristalline
DE19647313A1 (de) * 1996-11-13 1998-05-14 Siemens Ag Verfahren und Vorrichtung zum gerichteten Erstarren einer Schmelze
US6367538B1 (en) * 1998-12-21 2002-04-09 General Electric Company Mold and mold basket for use in uni-directional solidification process in a liquid metal bath furnace
EP1321208A2 (fr) * 2001-12-21 2003-06-25 Mitsubishi Heavy Industries, Ltd. Procédé et dispositif de coulée à solidification directionnelle
US20040079510A1 (en) * 2002-10-29 2004-04-29 Pcc Airfoils, Inc. Method and apparatus for use during casting
US20050045300A1 (en) * 2003-09-02 2005-03-03 General Electric Company Apparatus and method for producing single crystal metallic objects

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3062588A1 (fr) * 2017-02-06 2018-08-10 Safran Aircraft Engines Systeme de raccordement d'une sole de four a une embase de moule carapace pour la fabrication d'un element aubage

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Publication number Publication date
JP2009125809A (ja) 2009-06-11

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