EP2165787A1 - Moule de solidification directionnelle - Google Patents

Moule de solidification directionnelle Download PDF

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Publication number
EP2165787A1
EP2165787A1 EP09251609A EP09251609A EP2165787A1 EP 2165787 A1 EP2165787 A1 EP 2165787A1 EP 09251609 A EP09251609 A EP 09251609A EP 09251609 A EP09251609 A EP 09251609A EP 2165787 A1 EP2165787 A1 EP 2165787A1
Authority
EP
European Patent Office
Prior art keywords
spiral
selector
mould
pattern
cavity
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Withdrawn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
EP09251609A
Other languages
German (de)
English (en)
Inventor
John Harold Boswell
Simon Travis Lockwood
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.)
Rolls Royce PLC
Original Assignee
Rolls Royce PLC
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 Rolls Royce PLC filed Critical Rolls Royce PLC
Publication of EP2165787A1 publication Critical patent/EP2165787A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • 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
    • B22C7/023—Patterns made from expanded plastic materials
    • B22C7/026—Patterns made from expanded plastic materials by assembling preformed parts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22C—FOUNDRY MOULDING
    • B22C9/00—Moulds or cores; Moulding processes
    • B22C9/22—Moulds for peculiarly-shaped castings
    • B22C9/24—Moulds for peculiarly-shaped castings for hollow articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D25/00—Special casting characterised by the nature of the product
    • B22D25/02—Special casting characterised by the nature of the product by its peculiarity of shape; of works of art

Definitions

  • the present invention relates to a mould for use in directionally solidifying a component, and a pattern for forming such a mould.
  • Directional solidification can be used to produce cast components such as gas turbine blades.
  • An advantage of a directionally solidified structure is that grain boundaries can be aligned along the length of a blade, providing increased creep strength at the high operating temperatures and stresses to which turbine blades may be exposed.
  • Creep strength can be increased still further by casting blades as single crystals in which there are no grain boundaries.
  • the metal solidifies to form chill crystals 11 on the surface of the chill plate 2.
  • the chill plate sets up a thermal gradient causing heat to flow in the direction from the heated chamber to the chill plate, and after a short period the chill crystals with the most favourable crystallographic orientations grow epitaxially as columnar grains 12 in the direction opposite to the heat flow direction to form a starter block 6 of solidified metal at the base portion of the mould cavity.
  • the mould has a grain selector spiral 7, which is a helical passage connecting the base portion of the mould cavity to the component portion 8 of the mould cavity.
  • the crystals which grow fastest are most likely to reach the entrance to the grain selector spiral first.
  • the spiral 7 acts as choke, reducing the number of crystals growing towards the exit of the spiral and the component portion 8 of the mould cavity above the spiral.
  • a single crystal 13 of the desired crystallographic emerges from the spiral 6 into the component portion 8 of the mould cavity.
  • the mould is withdrawn via baffle plates 9 into a cooled lower chamber 10, thus maintaining the thermal gradient and the epitaxial growth.
  • the mould continues to be withdrawn until the single crystal has grown the entire length and width of the component portion 8 of the mould cavity.
  • a pre-cast seed crystal can be located in the base portion of the mould cavity, the seed crystal already having the desired crystallographic orientation. Epitaxial growth on this crystal will then produce a suitably oriented grain.
  • chill crystals tend to form at the melt back interface on the seed crystal, and these crystals can grow as fast or faster than the seed crystal itself.
  • a selector spiral, or some non-helical variant thereof to choke secondary grains.
  • the role of the selector spiral is particularly important when no seed crystal is used, even with a seed crystal it can be difficult to ensure that only one crystal enters the component portion of the mould cavity from the selector spiral.
  • the result can be a bi-crystal component, or a component containing a high angle grain boundary. In either case, the component will generally have to be scrapped.
  • a first aspect of the present invention provides a mould for use in directionally solidifying a component, the mould having a casting cavity including a single crystal selector spiral, wherein the selector spiral is a helical passage having not less than 1 1 ⁇ 4 and not more than 11 ⁇ 2 turns.
  • the helical passage has a diameter of at least 4.5 mm, which helps to prevent the flow of molten metal into the mould being blocked at the spiral during bottom filling.
  • the component may be an aerofoil (such as a blade) of a gas turbine engine, and the casting cavity may further include a component cavity portion for forming the aerofoil, the selector spiral and the component cavity portion being in fluid communication.
  • the selector spiral and the component cavity portion can then be arranged such that the axis of the selector spiral aligns with the stacking axis of the aerofoil when the aerofoil is formed in the component cavity portion.
  • the single grain selected by the selector spiral can fill the component cavity portion starting from a central position in that cavity portion. This helps to reduce the likelihood of secondary grain nucleation and growth within the component cavity portion.
  • the mould can be adapted to be connectable to a second mould having a second casting cavity for forming the component, the selector spiral and the second casting cavity being in fluid communication when the moulds are thus connected.
  • the two moulds are formed from respective wax or plastic patterns which are coated and then eliminated.
  • the first casting cavity may further include a starter block cavity portion in fluid communication with the selector spiral, the selector spiral and the starter block cavity portion being arranged such that, during directional solidification, growing crystals enter the selector spiral from the starter block cavity portion.
  • a mould can be used, for example, with a chill plate positioned at a base end of the starter block cavity portion to form, chill crystals forming on the chill plate, the crystals growing with a columnar habit to form a starter block in the starter block cavity portion.
  • the starter block cavity portion is configured so that, when the selector spiral is positioned above the starter block cavity portion, a part of the starter block cavity portion extends vertically above the entrance to the selector spiral to provide a trap for debris in the cavity. That is, any debris in the trapped in the mould cavity may preferentially be washed or float into the trap, rather than into the selector spiral where it can initiate nucleation of secondary grains.
  • the mould may further have a seed crystal in fluid communication with the selector spiral, the selector spiral and the seed crystal being arranged such that, during directional solidification, the seed crystal grows and enters the selector spiral.
  • a second aspect of the invention provides a pattern for use in forming a mould according to the first aspect, the pattern being formed of material (such as wax or plastic) that can be eliminated to form the casting cavity of the mould when the pattern is coated with a material (such as ceramic) which forms the walls of the mould, and at least a portion of the pattern corresponding to the selector spiral.
  • material such as wax or plastic
  • a material such as ceramic
  • the pattern may have a cap portion extending from the part of the pattern corresponding to the entrance to the selector spiral, the cap portion being configured to cap, in use, a seed crystal or a further pattern corresponding to a starter block cavity portion.
  • the production of the pattern for the selector spiral can be separated from the production of the pattern for the starter block cavity portion or the seed crystal, which can make it is easier to control quality and to avoid accidental damage to the pattern for the spiral.
  • the cap portion may be positioned on the seed crystal or the further pattern only shortly prior to coating to form the mould walls.
  • the cap portion may be configured so that, when the portion of the pattern corresponding to the selector spiral is positioned above the cap portion, a part of the cap portion extends vertically above the part of the pattern corresponding to the entrance to the selector spiral, whereby said part of the cap portion corresponds to a trap for debris in the cavity of the mould.
  • the pattern may have an engagement portion which extends from a part of the pattern corresponding to the exit from the selector spiral for a growing crystal, in use, the pattern being joinable to a further pattern having a complementary engagement portion.
  • the two patterns After the two patterns are engaged they may be coated to form a mould.
  • the further pattern will be for forming a component cavity portion in the mould.
  • the engagement portions can make it easier to join two separately produced patterns prior to coating.
  • the engagement portion and complementary engagement portion may be a male-female pair. Another aspect of the invention provides the combination of the two patterns.
  • a further aspect of the invention provides the use of the mould of the first aspect for directionally solidifying a component.
  • a further aspect of the invention provides the use of the pattern or patterns of the second aspect for forming a mould.
  • a further aspect of the invention provides a component moulded using the mould of the first aspect and still attached to material solidified in the single crystal selector spiral.
  • Figures 2(a) and (b) are respectively front and side schematic views of a pattern 20 for a selector spiral.
  • the pattern may be a plastics part, eg injection moulded polystyrene.
  • the pattern has a helical part 21 with 11 ⁇ 4 to 11 ⁇ 2 turns.
  • a disc 22 which has a slightly conical upper surface. In use the disc is wax welded or glued to a pattern for the starter block (not shown).
  • a curved extension 23 joins to an inverted elliptical frustocone 24, which is the connecting part to a wax pattern (not shown) of the component to be cast.
  • a protrusion 25 at the top surface of the conical ellipse part is an engagement portion which couples to a corresponding recess in the component wax pattern in the manner of a male-female pair.
  • the complete pattern assembly is coated with ceramic layers which form the walls of the mould.
  • the pattern assembly is then eliminated by heating, leaving a single crystal directional solidification mould, having a mould cavity including a helical passage selector spiral.
  • the 11 ⁇ 4 to 11 ⁇ 2 turns of the selector spiral are sufficient to choke off secondary grains when the mould is used for single crystal directional solidification.
  • the number of turns is not so high that secondary grain nucleation and growth in the selector spiral becomes excessive.
  • the selector spiral is effective at reducing bi-crystal growth in the component, and hence at reducing component scrap rates.
  • the component is typically a turbine blade of a gas turbine engine.
  • the curved extension 23 allows the axis of the selector spiral to be aligned with the stacking axis of the turbine blade. This helps to reduce secondary grain nucleation in the component cavity of the mould.
  • Figure 3 illustrates the use of a variant of the pattern of Figure 2 .
  • disc 22 is replaced by a cap 26 which can be positioned over the pattern for the start block 27, or indeed over a seed crystal. This can speed up pattern assembly and improve alignment of the selector spiral and the starter block or seed crystal.
  • Figure 4 illustrates the use of a further variant of the pattern of Figure 2 .
  • the disc 22 is again replaced by a cap 28 positioned over the pattern for the starter block 27 or over a seed crystal.
  • an annular part 28 of the cap now extends vertically above the part 29 of the pattern corresponding to the entrance to the selector spiral.
  • the annular part provides a gravity trap for buoyant debris that may be in the mould cavity. Trapping the debris in this location can prevent it entering the selector spiral where it may promote secondary grain nucleation.
  • Figure 5 shows schematically a cross-section through a ceramic mould 30 which has a cavity comprising a single crystal selector spiral 31 (ie a helical passage having not less than 1 11 ⁇ 4 and not more than 11 ⁇ 2 turns) and a starter block or seed crystal holding cavity portion 32 in fluid communication with the bottom end of the selector spiral.
  • the mould may be formed, eg by an investment moulding process.
  • the top of the mould can be joined to the bottom of a second mould which has a cavity for the component to be cast, ie so that the selector spiral and the component cavity are in fluid communication.
  • this allows the process for forming the mould containing the selector spiral to be separated from the process for forming the mould for forming the component.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Turbine Rotor Nozzle Sealing (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
EP09251609A 2008-08-26 2009-06-20 Moule de solidification directionnelle Withdrawn EP2165787A1 (fr)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GBGB0815384.3A GB0815384D0 (en) 2008-08-26 2008-08-26 Directional solidification mould

Publications (1)

Publication Number Publication Date
EP2165787A1 true EP2165787A1 (fr) 2010-03-24

Family

ID=39846711

Family Applications (1)

Application Number Title Priority Date Filing Date
EP09251609A Withdrawn EP2165787A1 (fr) 2008-08-26 2009-06-20 Moule de solidification directionnelle

Country Status (3)

Country Link
US (1) US20100051142A1 (fr)
EP (1) EP2165787A1 (fr)
GB (1) GB0815384D0 (fr)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102794402A (zh) * 2012-08-21 2012-11-28 沈阳黎明航空发动机(集团)有限责任公司 一种单晶叶片螺旋选晶器的压型模具
CN104439068A (zh) * 2014-10-31 2015-03-25 贵州安吉航空精密铸造有限责任公司 一种含有凸耳孔的凸耳合金零件的制作工艺
CN107745093A (zh) * 2017-12-06 2018-03-02 安徽应流航源动力科技有限公司 一种精铸模组及利用其制备可精控晶体取向的镍基单晶导叶的铸造方法
EP3453972A3 (fr) * 2017-09-12 2019-04-24 United Technologies Corporation Procédé de production d'un assemblage de tuiles de bouclier thermique pour chambre de combustion d'un reacteur
WO2020112087A1 (fr) * 2018-11-27 2020-06-04 General Electric Company Dispositifs de sélection à grains multiples, procédés de fabrication d'articles à grains colonnaires utilisant les dispositifs de sélection et articles à grains colonnaires fabriqués à l'aide des dispositifs de sélection
CN112589048A (zh) * 2020-12-09 2021-04-02 保定风帆精密机械科技有限公司 螺旋上锥体铸造模具及工艺
EP4310398A3 (fr) * 2017-09-12 2024-01-31 RTX Corporation Procédé de production d'un ensemble de panneaux de bouclier thermique de chambre de combustion de moteur à réaction

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR3095972B1 (fr) 2019-05-13 2023-07-07 Safran Aircraft Engines Moule pour la fabrication d’une pièce par coulée de métal et croissance épitaxiale et procédé de fabrication associé

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0087379A1 (fr) * 1982-01-27 1983-08-31 United Technologies Corporation Coulée d'une pièce de métal monocristalline en utilisant un germe cristallin et une hélice
EP0105823A1 (fr) * 1982-08-20 1984-04-18 United Technologies Corporation Moule avec une hélice pour la coulée d'articles en monocristal
GB2364006A (en) * 2000-06-27 2002-01-16 Rolls Royce Plc Crystal selector pattern

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6497272B1 (en) * 1999-10-14 2002-12-24 Howmet Research Corporation Single crystal casting mold
GB0015673D0 (en) * 2000-06-27 2000-08-16 Rolls Royce Plc Crystal selector pattern

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0087379A1 (fr) * 1982-01-27 1983-08-31 United Technologies Corporation Coulée d'une pièce de métal monocristalline en utilisant un germe cristallin et une hélice
EP0105823A1 (fr) * 1982-08-20 1984-04-18 United Technologies Corporation Moule avec une hélice pour la coulée d'articles en monocristal
GB2364006A (en) * 2000-06-27 2002-01-16 Rolls Royce Plc Crystal selector pattern

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102794402A (zh) * 2012-08-21 2012-11-28 沈阳黎明航空发动机(集团)有限责任公司 一种单晶叶片螺旋选晶器的压型模具
CN102794402B (zh) * 2012-08-21 2014-07-16 沈阳黎明航空发动机(集团)有限责任公司 一种单晶叶片螺旋选晶器的压型模具
CN104439068A (zh) * 2014-10-31 2015-03-25 贵州安吉航空精密铸造有限责任公司 一种含有凸耳孔的凸耳合金零件的制作工艺
EP3453972A3 (fr) * 2017-09-12 2019-04-24 United Technologies Corporation Procédé de production d'un assemblage de tuiles de bouclier thermique pour chambre de combustion d'un reacteur
US10940530B2 (en) 2017-09-12 2021-03-09 Raytheon Technologies Corporation Method to produce jet engine combustor heat shield panels assembly
EP4310398A3 (fr) * 2017-09-12 2024-01-31 RTX Corporation Procédé de production d'un ensemble de panneaux de bouclier thermique de chambre de combustion de moteur à réaction
CN107745093A (zh) * 2017-12-06 2018-03-02 安徽应流航源动力科技有限公司 一种精铸模组及利用其制备可精控晶体取向的镍基单晶导叶的铸造方法
CN107745093B (zh) * 2017-12-06 2023-06-06 安徽应流航源动力科技有限公司 一种精铸模组及利用其制备可精控晶体取向的镍基单晶导叶的铸造方法
WO2020112087A1 (fr) * 2018-11-27 2020-06-04 General Electric Company Dispositifs de sélection à grains multiples, procédés de fabrication d'articles à grains colonnaires utilisant les dispositifs de sélection et articles à grains colonnaires fabriqués à l'aide des dispositifs de sélection
US11931801B2 (en) 2018-11-27 2024-03-19 Ge Infrastructure Technology Llc Multi-grain selector devices, methods for manufacturing columnar grained articles using the selector devices, and columnar grained articles manufactured using the selector devices
CN112589048A (zh) * 2020-12-09 2021-04-02 保定风帆精密机械科技有限公司 螺旋上锥体铸造模具及工艺
CN112589048B (zh) * 2020-12-09 2022-07-08 保定风帆精密机械科技有限公司 螺旋上锥体铸造模具及工艺

Also Published As

Publication number Publication date
GB0815384D0 (en) 2008-10-01
US20100051142A1 (en) 2010-03-04

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