US3680625A - Heat reflector - Google Patents

Heat reflector Download PDF

Info

Publication number
US3680625A
US3680625A US88608A US3680625DA US3680625A US 3680625 A US3680625 A US 3680625A US 88608 A US88608 A US 88608A US 3680625D A US3680625D A US 3680625DA US 3680625 A US3680625 A US 3680625A
Authority
US
United States
Prior art keywords
molds
reflector
susceptor
ceramic
mold
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.)
Expired - Lifetime
Application number
US88608A
Other languages
English (en)
Inventor
Frank J Hein
Donald G Fleck
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.)
Northrop Grumman Space and Mission Systems Corp
Original Assignee
TRW Inc
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 TRW Inc filed Critical TRW Inc
Application granted granted Critical
Publication of US3680625A publication Critical patent/US3680625A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C30B11/002—Crucibles or containers for supporting the melt
    • 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
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C30B11/003—Heating or cooling of the melt or the crystallised material

Definitions

  • ABSTRACT Method and apparatus for producing columnar castings by precision investment casting techniques, wherein a refractory reflector is positioned in the furnace behind the molds contained therein to make it possible to control the unidirectional temperature gradient more closely and provide more pieces per mold.
  • HEAT REFLECTOR BACKGROUND OF THE INVENTION 1.
  • Field of the Invention This invention is in the field of precision investment casting to produce columnar structures, and is particularly involved with reflector elements for mold clusters which make it possible to employ more molds on a given cluster than has heretofore been the practice.
  • Columnar structures are generally produced by positioning a doubly open-ended ceramic mold on a chill block composed of copper or other highly heat conductive material.
  • the mold structure is positioned within a furnace, usually heated by selectively energizable induction heating coils and provided with a susceptor which radiates the heat at the cluster of molds within 2 the furnace.
  • the molds are preheated to a temperature at least as high as the solidus temperature of the metal to be cast, and the molten metal is then cast into the molds.
  • solidification proceeds upwardly from the copper chill block and is controlled by a variety of means, including selective deenergization of the induction heating coils to produce a unidirectional temperature gradient throughout the mold during solidification.
  • the number of molds which could be utilized in a given cluster has been limited. This, of course, is undesirable since the greater the number of pieces which can be obtained per casting operation, the more economical is the process.
  • the number of pieces which can be produced from a mold cluster is limited by the geometry of the part and the size of the induction heating coil.
  • the overall geometry of the mold and the proximity of one mold structure to another have an effect on the ability of the system to produce acceptable grain structures. It has been found necessary on some configurations, for example, to thicken the mold at the top as much as one inch to assure proper solidification characteristics.
  • This invention provides improvements in the field of precision investment casting and, more particularly, in the specific field of producing columnar grain structures in castings. Specifically, we have now found that by positioning a ceramic reflector element within the furnace assembly, the interaction between the individual molds in the mold cluster is significantly reduced and more molds can be put on a cluster thereby increasing the yield of the process, and a higher percentage of the castings result in the desired columnar grain structure.
  • the reflector is positioned between the central portion of the mold and the molding cavity so that the molding cavities are disposed between the reflector and the radiating inner wall of the furnace, which is usually a graphite susceptor.
  • the ceramic reflector may be separately introduced into the molding assembly or, more preferably, it may be an integral part of the mold produced at the same time as the remainder of the cluster by the usual precision investment mold making processes.
  • FIG. 1 is a plan view of a pattern cluster which can be used for making the mold assemblies of the present in- VCIIIIIOII;
  • FIG. 2 is a cross-sectional view taken substantially along the line II-II of FIG. 1;
  • FIG. 3 is a view partially in cross-section and partially in elevation of a mold assembly and furnace as- 5 sembly of the type with which the present invention is involved.
  • a pattern assembly for producing shell type investment molds of the present invention is illustrated at reference numeral 10 in FIG. 1. While the particular pattern as shown in the drawings is designed for the production of four molds, it should be understood that any number of mold assemblies can be employed and one of the advantages of the present invention is that the mold assemblies can be placed closer together in the cluster than has heretofore been commonplace.
  • Individual patterns 11 through 14 composed of wax or other pattern material are spaced about a central pouring basin-forming portion 15 is connected to the upper ends of the patterns 11 through 14 by means of upper runners 17 through 20, respectively.
  • the bottom ends of the patterns 11 through 14 are connected to the base of the sprue-forming portion 16 by means of radially extending runners, two of which identified at reference numerals"-2l and 22 are visible in FIG. 2. It will be understood that in keeping with ordinary investment casting procedures, the patterns 11 through 14 may be made in individual pattern molds and thereupon connected to the runners and the pouring basin forming portion 15 and the sprue-forming portion 16 by means of heat welding or solvent welding.
  • the pattern assembly shown in FIGS. 1 and 2 also includes a reflector-forming portion 23 which may consist of a thin sheet of wax which is suitably secured to the bottom runners 21 and 22 as well as the bottom runners feeding the patterns 12 and 14.
  • the sheet 23 may be about 0.1 inch in thickness.
  • the pattern cluster shown in FIGS. 1 and 2 is then used to form a mold cluster through conventional precision investment mold-making techniques.
  • One such method involves coating the wax pattern assembly by dipping it in an aqueous ceramic slurry having atemperature about the same asthat of the pattern material to fonn a refractory layer of a few mils in thickness.
  • a typical slurry may contain ceramic material such as zirconium oxide, a binder such as colloidal silica and a thickener and low temperature binder such as methyl cellulose.
  • the methyl layer while still wet is then dusted with small particles (-40 to 200 mesh) of a refractory glass composition such as that known as Vycor which is a finely divided, high silicon oxide glass containing about 98 percent silica and a small amount of boric acid, together with traces of aluminum, sodium, iron and arsenic.
  • Vycor a refractory glass composition
  • the pattern with the dusted wet refractory layer on it is then suspended on a conveyor and moved to a drying oven having a controlled humidity and temperature, thereby drying the coated pattern assembly adiabatically.
  • the steps of dipping, dusting and adiabatic drying are then repeated using air at progressively lower humidities for succeeding coats.
  • the first two' coats canbe dried with air having a relative humidity of 45 to 55 percent.
  • the third and fourth coats can be dried with a relative humidity of 35 to 45 percent, the fifth and sixth coats with a relative humidity of 45 to 55 percent.
  • the third and fourth coats can be dried with a relative humidity of 35 to 45 percent, the fifth and sixth coats with a relative humidity of to 'percent, and the final coat with a relative humidity of l5 to 25 percent.
  • the first layer is preferably applied to a thickness of 0.005 to 0.020 inch, and the fine refractory particles are dusted onto the wet layer with sufficient force to embed the particles therein. It is preferred that the dusting procedure used provide a dense uniform cloud of fine particles that strike the wet coating with substantial impact force. The force should not be so great, however, as to break or knock off the wet prime layer from the pattern. This process is repeated until a plurality of integrated layers is obtained, the thickness of the layers each being about 0.005 to 0.020 inch.
  • the pattern material can be removed by heat and then the green mold is ready for firing. Generally, firing temperatures on the order of l,500 to 1,900? P.
  • the resulting shell molds are hard, smooth and relatively permeable, and have a thickness on the order of one-eighth to one-fourth inch.
  • the resulting mold cluster produced from the pattern assembly 10 is shown at reference numeral 30 in FIG. 3.
  • the mold assembly 30 is disposed within a furnace having a refractory outer wall 31 about which one or more induction heating coils 32 are disposed.
  • a susceptor 33 composed of graphite or the like which serves to deliver radiant energy to the molds.
  • the top of the furnace is closed by means of a top plate 34 composed of refractory material, and a funnel 35 is provided to deliver molten metal to the casting cavities.
  • the mold assembly 30 itself contains a pouring basin 36 and a cylindrical sprue portion 37 extending downwardly therefrom.
  • the pouring basin 36 communicates with the interior of the casting molds, two of which have been identified at. reference numerals 38 and 39 in FIG. 3.
  • Runners 40 and 41 are used to deliver molten metal from the common source into the casting cavities of the respective molds.
  • the mold assemblies are open ended and their bottom ends are positioned on a chill block 42 composed of copper or other highly heat conductive material. If desired, a circulating fluid may be passed through the chill block 42 to increase the rate of heat transfer.
  • the mold assembly also includes a refractory reflector 43 which in the form of the invention illustrated in FIG. 3 consists of a continuousannulus of ceramic mold fonning material with a hollow center.
  • the reflector 43 can consists of a preformed ceramic material which is placed in the mold prior to pouring and it need not be continuous.
  • a plurality of ceramic bafi'les can be positioned closely adjacent the individual molds, the width of the baffles being at least as large as the projected widths'of the mold assemblies with which they are associated.
  • the molding assembly in operation, is operated under vacuum conditions, and the molds are heated to a temperature above the solidus temperature of the metal to be poured in the mold.
  • the metal is melted and cast into the mold and the temperature of the mold is gradually reduced in order to obtain unidirectional solidification from the chill block 42 upwardly to the top of the casting.
  • One convenient means of doing this is to progressively deenergize individual coils making up the induction heating coil 32 .so that as solidification I proceeds upwardly, a unidirectional temperature gradient exists longitudinally of the mold, and a columha grain structure having a longitudinal orientation is produced.
  • a casting mold assembly comprising a plurality of circumferentially spaced ceramic molds enclosed by said wall, a common feed means disposed centrally of said molds for introducing molten metal radially into each of said molds, and refractory reflector means separate from said ceramic molds disposed in closely spaced relation to said molds on the sides thereof opposite to said susceptor.
  • the method of producing columnar castings which comprises positioning a plurality of spaced, openended ceramic molds on a highly heat conductive surface within a furnace including a susceptor which radiates heat at said molds, preheating said molds to a temperature above the solidus temperature of the metal to be cast, positioning a ceramic reflector inwardly of said molds so that such molds are disposed between said reflector and said susceptor, said reflector being separate from said ceramic molds and being positioned to reflect heat radiated from said susceptor to portions of said molds which would otherwise be screened from such radiated heat, pouring molten metal into said molds, and providing a unidirectional 5 temperature gradient within said molds during the solidification of the metal therein.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Molds, Cores, And Manufacturing Methods Thereof (AREA)
  • Crucibles And Fluidized-Bed Furnaces (AREA)
US88608A 1970-11-12 1970-11-12 Heat reflector Expired - Lifetime US3680625A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US8860870A 1970-11-12 1970-11-12

Publications (1)

Publication Number Publication Date
US3680625A true US3680625A (en) 1972-08-01

Family

ID=22212358

Family Applications (1)

Application Number Title Priority Date Filing Date
US88608A Expired - Lifetime US3680625A (en) 1970-11-12 1970-11-12 Heat reflector

Country Status (4)

Country Link
US (1) US3680625A (enrdf_load_stackoverflow)
JP (1) JPS514186B1 (enrdf_load_stackoverflow)
FR (1) FR2113833B1 (enrdf_load_stackoverflow)
GB (1) GB1303028A (enrdf_load_stackoverflow)

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3810504A (en) * 1971-03-26 1974-05-14 Trw Inc Method for directional solidification
US3926245A (en) * 1973-09-28 1975-12-16 Gen Motors Corp Method for producing directionally solidified cast alloy articles and apparatus therefor
US3931847A (en) * 1974-09-23 1976-01-13 United Technologies Corporation Method and apparatus for production of directionally solidified components
US4033401A (en) * 1974-05-29 1977-07-05 Sulzer Brothers Limited Precision casting process
US4240495A (en) * 1978-04-17 1980-12-23 General Motors Corporation Method of making cast metal turbine wheel with integral radial columnar grain blades and equiaxed grain disc
US4673021A (en) * 1986-01-28 1987-06-16 Trw Inc. Method and apparatus for casting articles
WO1987004376A1 (en) * 1986-01-28 1987-07-30 Trw Inc. Method and apparatus for casting articles
US4813470A (en) * 1987-11-05 1989-03-21 Allied-Signal Inc. Casting turbine components with integral airfoils
US4850419A (en) * 1982-09-01 1989-07-25 Trw Inc. Method of casting a one-piece wheel
US5072771A (en) * 1988-03-28 1991-12-17 Pcc Airfoils, Inc. Method and apparatus for casting a metal article
US5175008A (en) * 1988-11-24 1992-12-29 Chugoku Shiken Kabushiki Kaisha Device for supplying plastic material for denture base and flask with the same
WO1999012679A1 (en) * 1997-09-12 1999-03-18 General Electric Company Method and apparatus for producing directionally solidified castings
US6471397B2 (en) * 1999-08-06 2002-10-29 Howmet Research Corporation Casting using pyrometer apparatus and method
FR2874340A1 (fr) * 2004-08-20 2006-02-24 Snecma Moteurs Sa Procede de fonderie de pieces en carapace, grappe et carapace pour sa mise en oeuvre, aube de turboreacteur obtenue par un tel procede, et moteur d'aeronef comportant de telles aubes
US20080096043A1 (en) * 2004-07-27 2008-04-24 Universidade Do Minho Process and Equipment For Obtaining Metal Or Metal Matrix Components With A Varying Chemical Composition Along The Height Of The Component And Components Thus Obtained
US8087450B2 (en) 2007-01-29 2012-01-03 Evonik Degussa Corporation Fumed metal oxides for investment casting
US20150209861A1 (en) * 2014-01-24 2015-07-30 Snecma Method of preheating a set of shell molds for lost-wax casting
US20170216912A1 (en) * 2016-02-03 2017-08-03 Rolls-Royce Plc Apparatus for casting multiple components using a directional solidification process
US12121962B2 (en) * 2022-09-27 2024-10-22 GM Global Technology Operations LLC System and method of making a tilt-poured cradle for a fuel cell
US12128476B2 (en) * 2023-01-24 2024-10-29 GM Global Technology Operations LLC System and method of making a cast reverse tilt-poured fuel cell cradle
US12257629B2 (en) 2020-01-09 2025-03-25 Tundra COmpoistes, LLC Apparatus and methods for sintering

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2116867C1 (ru) * 1997-09-12 1998-08-10 Всероссийский научно-исследовательский институт авиационных материалов Устройство для получения отливок с направленной и монокристаллической структурой
US6557618B1 (en) 1997-09-12 2003-05-06 General Electric Company Apparatus and method for producing castings with directional and single crystal structure and the article according to the method
RU2211746C1 (ru) * 2001-12-26 2003-09-10 Федеральное государственное унитарное предприятие "Всероссийский научно-исследовательский институт авиационных материалов" Способ получения отливок с направленной и монокристальной структурой и устройство для его осуществления
CN114130994B (zh) * 2021-12-20 2023-12-19 成都航宇超合金技术有限公司 一种减少单晶叶片平台处杂晶缺陷的装置及其方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3248764A (en) * 1964-01-08 1966-05-03 Trw Inc Method for improving grain structure and soundness in castings
US3417809A (en) * 1965-07-16 1968-12-24 United Aircraft Corp Method of casting directionally solidified articles
US3515205A (en) * 1968-03-20 1970-06-02 United Aircraft Corp Mold construction forming single crystal pieces
US3627015A (en) * 1970-06-01 1971-12-14 Hughes Aircraft Co Cocoon casting of directionally solidified articles

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3248764A (en) * 1964-01-08 1966-05-03 Trw Inc Method for improving grain structure and soundness in castings
US3417809A (en) * 1965-07-16 1968-12-24 United Aircraft Corp Method of casting directionally solidified articles
US3515205A (en) * 1968-03-20 1970-06-02 United Aircraft Corp Mold construction forming single crystal pieces
US3627015A (en) * 1970-06-01 1971-12-14 Hughes Aircraft Co Cocoon casting of directionally solidified articles

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3810504A (en) * 1971-03-26 1974-05-14 Trw Inc Method for directional solidification
US3926245A (en) * 1973-09-28 1975-12-16 Gen Motors Corp Method for producing directionally solidified cast alloy articles and apparatus therefor
US4033401A (en) * 1974-05-29 1977-07-05 Sulzer Brothers Limited Precision casting process
US3931847A (en) * 1974-09-23 1976-01-13 United Technologies Corporation Method and apparatus for production of directionally solidified components
US4240495A (en) * 1978-04-17 1980-12-23 General Motors Corporation Method of making cast metal turbine wheel with integral radial columnar grain blades and equiaxed grain disc
US4850419A (en) * 1982-09-01 1989-07-25 Trw Inc. Method of casting a one-piece wheel
US4673021A (en) * 1986-01-28 1987-06-16 Trw Inc. Method and apparatus for casting articles
WO1987004376A1 (en) * 1986-01-28 1987-07-30 Trw Inc. Method and apparatus for casting articles
US4813470A (en) * 1987-11-05 1989-03-21 Allied-Signal Inc. Casting turbine components with integral airfoils
US5072771A (en) * 1988-03-28 1991-12-17 Pcc Airfoils, Inc. Method and apparatus for casting a metal article
US5175008A (en) * 1988-11-24 1992-12-29 Chugoku Shiken Kabushiki Kaisha Device for supplying plastic material for denture base and flask with the same
WO1999012679A1 (en) * 1997-09-12 1999-03-18 General Electric Company Method and apparatus for producing directionally solidified castings
US6471397B2 (en) * 1999-08-06 2002-10-29 Howmet Research Corporation Casting using pyrometer apparatus and method
US20080096043A1 (en) * 2004-07-27 2008-04-24 Universidade Do Minho Process and Equipment For Obtaining Metal Or Metal Matrix Components With A Varying Chemical Composition Along The Height Of The Component And Components Thus Obtained
FR2874340A1 (fr) * 2004-08-20 2006-02-24 Snecma Moteurs Sa Procede de fonderie de pieces en carapace, grappe et carapace pour sa mise en oeuvre, aube de turboreacteur obtenue par un tel procede, et moteur d'aeronef comportant de telles aubes
US8087450B2 (en) 2007-01-29 2012-01-03 Evonik Degussa Corporation Fumed metal oxides for investment casting
US20150209861A1 (en) * 2014-01-24 2015-07-30 Snecma Method of preheating a set of shell molds for lost-wax casting
US9694421B2 (en) * 2014-01-24 2017-07-04 Snecma Method of preheating a set of shell molds for lost-wax casting
US20170216912A1 (en) * 2016-02-03 2017-08-03 Rolls-Royce Plc Apparatus for casting multiple components using a directional solidification process
EP3202512A1 (en) * 2016-02-03 2017-08-09 Rolls-Royce plc Apparatus for casting multiple components using a directional solidification process
US10675678B2 (en) 2016-02-03 2020-06-09 Rolls-Royce Plc Apparatus for casting multiple components using a directional solidification process
US12257629B2 (en) 2020-01-09 2025-03-25 Tundra COmpoistes, LLC Apparatus and methods for sintering
US12121962B2 (en) * 2022-09-27 2024-10-22 GM Global Technology Operations LLC System and method of making a tilt-poured cradle for a fuel cell
US12128476B2 (en) * 2023-01-24 2024-10-29 GM Global Technology Operations LLC System and method of making a cast reverse tilt-poured fuel cell cradle

Also Published As

Publication number Publication date
GB1303028A (enrdf_load_stackoverflow) 1973-01-17
FR2113833A1 (enrdf_load_stackoverflow) 1972-06-30
JPS514186B1 (enrdf_load_stackoverflow) 1976-02-09
FR2113833B1 (enrdf_load_stackoverflow) 1975-02-07

Similar Documents

Publication Publication Date Title
US3680625A (en) Heat reflector
US3596703A (en) Method of preventing core shift in casting articles
US3204303A (en) Precision investment casting
US3662816A (en) Means for preventing core shift in casting articles
US3659645A (en) Means for supporting core in open ended shell mold
US3810504A (en) Method for directional solidification
US3620289A (en) Method for casting directionally solified articles
US3401738A (en) Core location in precision casting
US3835913A (en) Investment casting
GB1438693A (en) Metho- for producing directionally solidified castings
US3598167A (en) Method and means for the production of columnar-grained castings
US2420003A (en) Temperature control mold
US2752653A (en) Method of and dies for forming hollow expendable patterns for casting
US4724891A (en) Thin wall casting
EA031934B1 (ru) Железнодорожное колесо, устройство и способ производства
US3441078A (en) Method and apparatus for improving grain structures and soundness of castings
US3385346A (en) Method and apparatus for removal of condensed deposits from mold covers
US3754592A (en) Method for producing directionally solidified cast alloy articles
US3667533A (en) Making directionally solidified castings
US3283377A (en) Turbine wheel manufacturing method
US3515205A (en) Mold construction forming single crystal pieces
US4809764A (en) Method of casting a metal article
US3981346A (en) Method and apparatus for directional solidification
US3336970A (en) Methods of casting
CA1195817A (en) Investment casting using metal sprue