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Publication numberUS3598169 A
Publication typeGrant
Publication dateAug 10, 1971
Filing dateMar 13, 1969
Priority dateMar 13, 1969
Also published asCA926737A, CA926737A1, DE2010570A1, DE2010570B2
Publication numberUS 3598169 A, US 3598169A, US-A-3598169, US3598169 A, US3598169A
InventorsStephen M Copley, Anthony F Giamei, Merton F Hornbecker, Bernard H Kear
Original AssigneeUnited Aircraft Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Method and apparatus for casting directionally solidified discs and the like
US 3598169 A
Abstract  available in
Images(4)
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Claims  available in
Description  (OCR text may contain errors)

United States Patent Inventors Stephen M. Copley Madison: Anthony 1-. Gialnei, Middletown; Merton F. Hornbecker, Woodbury; Bernard H. Kear, Madison, all of, Conn.

Appl. No. 807,637

Filed Mar. 13. 1969 Patented Aug. 10, 1971 Assignee United Aircraft Corporation East Hartford, Conn.

mmion AND APPARATUS ron CASTING 1 DIRECTIONALLY sounrrnzn DISCS AND THE um:

14 Claims, 9 Drawing Figs.

US. Cl. 164/60, 164/125, 164/338, 164/353, 164/361 int. Cl 822d 25/06 Primary Examiner.l. Spencer Overholser Assistant Examiner-John E. Roethel Attorney-Charles A. Warren ABSTRACT: Apparatus and method for inducing radial directional solidification in parts having a relatively large dimension at right angles to the major axis such as discs and the like, in which, for example, a [010] radial and [100] tangential orientation is generated.

PATENTEUAUGIOISYI 3,598,169

sum 1 or 4 Q Q N g INVENTORS BERNARD H. KEAR STEPHEN M. COPLEY ANTHONY F. GIAME! MERTON F. HORNBECKER WWW ATTORNEY PATENTED AUG] 0 I971 SHEET 2 OF 4 PATENTED mm 0 nan SHEET 3 0F 4 O O-0 O located above and below the-mold nearer to the METHOD AND APPARATUS FOR CASTING DIRECTIONALLY SOLIDIFIED DISCS AND THE LIKE BACKGROUND OF THE INVENTION The US. Pat. No. 3,260,505 to VerSnyder describes the casting'of directionally solidified parts with a particular orientation of the crystalline growth with respect to the longitudinal axis of the part. In casting large diameter parts it is desirable to control the orientation of the dendritic growth in order to control the strength characteristics. In casting large diameter parts it is desirable to control the solidification to produce the desired crystalline orientation throughout the disc in order to obtain the desired strength or other characteristics in the desired direction within the disc.

SUMMARY OF INVENTION BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view paratus embodying the invention.

FIG. 2 is a fragmentary sectional view similar to a portion of partially schematic of ap FIG. 1 showinga modification.

FIG; 3 is a schematic view showing the dendritic orientation.

. FIG. 4 is a vertical sectionalview ofa complete turbine disc including blades.

FIG. 5 is a fragmentary sectional view along line 5-5 of FIG.

mold for producing a FIG. 6 is a view similar to FIG. 1 ofanother modification. FIG. 7 is a horizontal sectional view of the modification of FIG. 6.

FIG. 8'is a vertical sectional view similar to FIG. 6 of another modification.

FIG. 9 is a fragmentary horizontal view through the mold of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the apparatus includes a chill plate 10 supporting a mold 12, the latter having a relatively large horizontal dimension, and shown as a mold for producing a disc. Atone side of the mold an axial projection 14 extends downwardly to engage the chill plate, and an upwardly extending axial projection 16 provides a filling opening for the mold. The mold is shown as a split-shell mold, being in two parts 120 and 12b although a single piece shell mold may be utilized.- The mold may be enclosed in part by insulation 18 around the axial extension 14 and the disc forming portion is covered 1 from the periphery inwardly by insulation 20 that decreases in thickness toward the center of the disc. Annular heating coils 22 and 24 are positioned above and below the mold adjacent to the axial projections. and other heating coils 26 and 28 are periphery and concentric to the coils 22 and 24. A heating coil 30 surrounds the periphery of the mold, as shown.

In operation. the technique described in US. Pat. No.

3.260.505 to VerSnyder Is Iollowed obtaina directionally solidified casting. The mold is positioned within a heating chamber, not shown, to raise the temperature of the entire mold above the melting point of the alloy to be poured and, when adequate heating is accomplished, the molten alloy, su-

' perheated to at least 100 I produce a more tions 46 defining blade-shaped -with the disc cavity as shown in FIG. 5. Following the method above the melting point is poured into the mold through a sprue 32,and coolant is supplied to the chill plate to'establish a steeptemperature gradient within the mold. This causes the formation of vertically oriented directionally solidified grains in the axial projection 14 and solidification proceeds upwardly.

While this is occuring heat has been supplied to the mold by the heating coils thereby maintaining the portion of the mold peripherally out from the axial projections and the metal thereon above the melting point. As solidification begins to take place into the portion of the mold directly above the axial portion 14 the grain growth continues vertically by reason of the heat loss to the chill plate and the vertical grains on the periphery of the solidifying portion begin to grow radially outward. When the solidification reaches a position represented by the dotted line 34, a radial thermal gradient is produced in the disc portion of the mold by gradually reducing the heating effect from the axis outwardly toward the periphery of the disc. Thusthe power'to coils 22 and 24 is reduced first then the power to coils 26 and 28, and finally to coil 30. The radial thermal gradient thus produced causes radial growth of the dendrites in the peripheral vertical columnar grains extending upwardly from the axial portion 14 and the radial competition between the several orientations of dendrites in the several rains will result in the radially oriented grains growing the fastest and producing substantially radially arranged dendrites in the entire disc. The radial thermal gradient produces the radial growth within the disc in the same way that the vertically oriented grains outgrow the other grains in the axial portion 14. This effect is described in the US. Pat. No. 3,260,505 to VerSnyder. Grain growth occuring in this manner produces an radial orientation and tangential orientation.

Much the same arrangement may be used in producing a more idealized orientation of grain structure. As shown, in FIG. 2, the axially extending portion 14' ofa mold 12' which is otherwise arranged as in FIG. 1 has a seed 36 therein resting on the chill plate. This seed is made up of wedges 38 each having the desired orientation for the portion of the disc extending outwardly therefrom. In operation the same procedure is followed as above. When the molten alloy is poured into the -mold', the seed wedges cause vertical dendritic growth with each of the several seed wedges providing the desired horizontal orientation for the adjacent portion of the cast disc.

The resulting orientation is shown in FIG. 3 where the seed 36 is made up of wedges, for example, as shown, theseed is made up of eight wedges each of 45 and each having the orientation indicated. The result is a disc made up of interacting dendritic growths producing approximately a radial and a tangential orientation. Use of many more wedge elements will disc. Obviously the controlled radial thermal gradient provided by the structure of FIG. 1 permits controlled grain growth through the entire disc to its periphery.

One particular article that may prove particularly useful in a casting of this character is representedby FIGS. 4 and 5. In these figures is a mold 40 defining a disc-shaped cavity 42, and having the downwardly extending axial projection 44 corresponding to the extension 14 of FIG. 1. Projecting outwardly from the periphery of the mold 40 are blade formingprojeccavities 48 communicating above described. and using the heat controlling arrangement of FIG. 1, the disc and blades for a turbine disc may all be cast in a single piece with the preferred orientation of the grain growth in the disc and with the desired radial orientation in the blades for the desired strength characteristics. In this arrangement the number of seed wedges would be selected to insure the precise radial grain growth in the blades. Thus, for example, the seed used would have possibly one wedge for each two blades, the-orientation of the several wedges being carefully selected for precise radial grain growth.

Another alternative is shown in FIGS. 6 and 7 where the mold is made up of individual mold elements 50 extending precisely radial grain'distribution within the v radially outward from a central casting cavity 52 surrounding a vertical cylindrical chill 54. The chill 54 is surrounded by seed segments 56, one for each mold element 50 and these segments establish the direction of the grain growth in each mold. The grain growth proceeds radially outward in each mold 50 and its connecting mold passage 58, with the temperature gradient in a radial direction controlled by the central chill and the use of annular heating coils as in FIG. 1. This controlled thermal gradient which will produce directionally solidified alloy in each mold element 50 with the direction of the grains radial in each cast article, is described in U.S. Pat. No. 3,260,505 to VerSnyder above referred to. The cast articles are represented as turbine blades and would be cast from the type of high temperature alloy of which several examples are given in the VerSnyder patent.

An alternate proposed method of producing discs, with or without integral blades, is shown in FIG. 8 in which the mold 60 has an annular disc cavity 62 and surrounds a central vertical cylindrical chill 64. The periphery of the mold may have recesses 66 therein for forming the individual blades on the periphery of the disc when the cast article is intended as a bladed turbine disc. A ring 68 of individual seed segments 70, each of directionally solidified material with properly oriented grains surrounds the chill at the disc level to control the directional orientation of the grain growth in the disc. Obviously annular heat control coils similar to those in FIG. 1 are used here to produce the desired radial thermal gradient. By using the appropriate number of seed segments the precise radial grain growth desired may be obtained throughout the disc and into the individual blades.

We claim:

1. Apparatus for casting relatively flat articles with a selected grain orientation including a chill plate, a mold hav' ing an article-shaped cavity and a centrally located downward extension forming a vertically positioned cavity communicating with said first cavity and opening onto the chill plate, and a plurality of heating means adjacent to the mold and arranged on top and bottom of the article cavity and in steps outwardly from the downward extension to the remote edge of the mold to establish a thermal gradient radially outward from the extension toward the remote edge ofthe mold.

2. Apparatus as in claim 1 in which the heating means are arranged in concentric rings from the extension to the periphery of the mold.

3. Apparatus as in claim 2 in which insulation is placed on the mold from the extension to the periphery in gradually decreasing thickness from the periphery toward the extension.

4. Apparatus as in claim I in which a selectively oriented seed is placed on the chill plate and within the extension.

5. Apparatus as in claim I in which a seed having multiple orientations is placed on the chill plate and within the extension.

6. The method of casting discs and the like including the step of providing a mold having an article forming cavity and a downward extension thereon forming a vertical cavity communicating with said first cavity and open at the bottom, providing a chill plate on which the downward extension rests, heating the mold to a point above the melting point of the al loy, pouring the alloy into the mold, cooling the chill plate to remove heat from the alloy, and cooling the mold in steps radially outward from the extension thereby providing a radially outward thermal gradient from the downward extension of the mold to the outer periphery of the mold laterally remote therefrom.

7. In the method of claim 6 in which the mold cavity is relatively flat, the extension is located centrally of the cavity, and the step of cooling the mold in steps radially outward produces a radial thermal gradient horizontally from the central extension to the periphery of the annulus thereby promoting a radial grain growth horizontally in the mold.

8. In the method of claim 6 the step of providing a seed in the extension before pouring the alloy with the orientation of the grain of the seed in the desired orientation for the solidified alloy in the cast article.

9. In the method of claim 7 the added step of providing a suitably oriented seed in the extension before pouring the alloy.

10. In the method of claim 7 the added step of providing a seed made up of wedges each of radially oriented grains to produce an annulus in which the grains are substantially all radially oriented.

11. Apparatus for casting relatively flat articles with a selected grain orientation including a chill, a mold defining a ring-shaped cavity, one surface of which is defined by the chill, and a plurality of annular heating means adjacent to the mold and arranged in steps radially outward outwardly from the axis of the ring and on opposite sides thereof to establish a thermal gradient from the axis to the periphery of the mold.

12. Apparatus as in claim 11 in which the chill is a cylinder extending axially of and surrounded by the mold.

13. Apparatus as in claim 11 in which the cavity defines a plurality of radially extending article forming cavities all communicating with a central cavity in contact with the chill.

14. Apparatus as in claim 11 in which the chill is a vertically extending centrally located chill surrounded by the mold, and in which a seed made up of properly oriented segments surrounds the chill within the cavity.

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2791813 *Oct 28, 1954May 14, 1957Delano James KApparatus and method for growing crystals having a controlled internal junction structure
US3373795 *Aug 10, 1965Mar 19, 1968Trw IncGating of unshrouded airfoils to permit directional solidification
US3405220 *Jul 16, 1965Oct 8, 1968United Aircraft CorpInduction electric mold heater
US3515205 *Mar 20, 1968Jun 2, 1970United Aircraft CorpMold construction forming single crystal pieces
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3729050 *Aug 10, 1971Apr 24, 1973Howmet CorpRefractory support for shell molds
US3858641 *Apr 23, 1973Jan 7, 1975Minnesota Mining & MfgMetal casting in thin walled molds
US4016829 *Feb 26, 1974Apr 12, 1977Hitachi, Ltd.Apparatus for crystal growth
US4096025 *Jun 23, 1975Jun 20, 1978The United States Of America As Represented By The Secretary Of The ArmyMethod of orienting seed crystals in a melt, and product obtained thereby
US4213497 *Aug 21, 1978Jul 22, 1980General Electric CompanyMethod for casting directionally solidified articles
US4240495 *Apr 17, 1978Dec 23, 1980General Motors CorporationMethod of making cast metal turbine wheel with integral radial columnar grain blades and equiaxed grain disc
US4289570 *Dec 13, 1978Sep 15, 1981United Technologies CorporationSeed and method for epitaxial solidification
US4469160 *Dec 23, 1981Sep 4, 1984United Technologies CorporationSingle crystal solidification using multiple seeds
US4499155 *Jul 25, 1983Feb 12, 1985United Technologies CorporationArticle made from sheet having a controlled crystallographic orientation
US4605452 *Dec 14, 1981Aug 12, 1986United Technologies CorporationSingle crystal articles having controlled secondary crystallographic orientation
US4659288 *Dec 10, 1984Apr 21, 1987The Garrett CorporationDual alloy radial turbine rotor with hub material exposed in saddle regions of blade ring
US4804311 *Dec 14, 1981Feb 14, 1989United Technologies CorporationTransverse directional solidification of metal single crystal articles
US4813470 *Nov 5, 1987Mar 21, 1989Allied-Signal Inc.Casting turbine components with integral airfoils
US4850419 *Sep 1, 1982Jul 25, 1989Trw Inc.Method of casting a one-piece wheel
US5061154 *Dec 11, 1989Oct 29, 1991Allied-Signal Inc.Radial turbine rotor with improved saddle life
US5292385 *Dec 18, 1991Mar 8, 1994Alliedsignal Inc.Turbine rotor having improved rim durability
US5611389 *Dec 30, 1981Mar 18, 1997Societe Nationale D'etude Et De Construction De Moterus D'aviation S.N.E.C.M.A.Procedure for the fabrication of crystalline blades
US5730582 *Jan 15, 1997Mar 24, 1998Essex Turbine Ltd.Impeller for radial flow devices
US7958928Jun 14, 2011Pcc Airfoils, Inc.Method and apparatus for casting metal articles
US20100206510 *Aug 19, 2010Garlock Robert MMethod and apparatus for casting metal articles
DE2242111A1 *Aug 26, 1972Mar 22, 1973United Aircraft CorpVerfahren und vorrichtung zum giessen von gegenstaenden mit gerichtet erstarrtem gefuege
DE2949446A1 *Dec 8, 1979Jun 26, 1980United Technologies CorpVerfahren und form fuer epitaxiale erstarrung
EP0066971A2 *May 14, 1982Dec 15, 1982Trw Inc.Method of casting an article
Classifications
U.S. Classification164/122.1, 164/353, 416/244.00A, 164/361, 416/241.00R, 117/939, 164/125
International ClassificationB22D27/04, C30B11/00
Cooperative ClassificationC30B11/00, B22D27/045
European ClassificationC30B11/00, B22D27/04A