US20170173685A1

US20170173685A1 - Method and assembly for forming components having internal passages using a lattice structure

Info

Publication number: US20170173685A1
Application number: US14/973,595
Authority: US
Inventors: Jacob John Kittleson
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 2015-12-17
Filing date: 2015-12-17
Publication date: 2017-06-22
Also published as: JP2017140650A; CN106890938A; EP3181265A1

Abstract

A mold assembly for use in forming a component having a first internal passage defined therein includes a mold that defines a mold cavity therein. The mold assembly also includes a lattice structure selectively positioned at least partially within the mold cavity and formed from a first material. The first material is at least partially absorbable by a component material in a molten state. The mold assembly further includes a first segmented core that includes at least one joint segment coupled to the lattice structure. The at least one joint segment is coupled in serial flow communication to at least one extension segment such that a first hollow structure is defined. A first inner core is disposed within the first hollow structure such that at least a portion of the first inner core defines the first internal passage when the component is formed in the mold assembly.

Description

BACKGROUND

The field of the disclosure relates generally to components having an internal passage defined therein, and more particularly to mold assemblies and methods for forming such components using a lattice structure to position a core that defines the internal passage.
Some components require an internal passage to be defined therein, for example, in order to perform an intended function. For example, but not by way of limitation, some components, such as hot gas path components of gas turbines, are subjected to high temperatures. At least some such components have internal passages defined therein to receive a flow of a cooling fluid, such that the components are better able to withstand the high temperatures. For another example, but not by way of limitation, some components are subjected to friction at an interface with another component. At least some such components have internal passages defined therein to receive a flow of a lubricant to facilitate reducing the friction.
At least some known components having an internal passage defined therein are formed in a mold, with a core of ceramic material extending within the mold cavity at a location selected for the internal passage. After a molten metal alloy is introduced into the mold cavity around the ceramic core and cooled to form the component, the ceramic core is removed, such as by chemical leaching, to form the internal passage. However, at least some known cores are difficult to position precisely with respect to the mold cavity and with respect to each other, resulting in a decreased yield rate for formed components. For example, some molds used to form such components are formed by investment casting, in which a material, such as, but not limited to, wax, is used to form a pattern of the component for the investment casting process, and at least some known cores are difficult to position precisely with respect to a cavity of a master die used to form the pattern. Moreover, at least some known ceramic cores are fragile, resulting in cores that are difficult and expensive to produce and handle without damage. For example, at least some known ceramic cores lack sufficient strength to reliably withstand injection of the pattern material to form the pattern, repeated dipping of the pattern to form the mold, and/or introduction of the molten metal alloy.
Alternatively or additionally, at least some known components having an internal passage defined therein are initially formed without the internal passage, and the internal passage is formed in a subsequent process. For example, at least some known internal passages are formed by drilling the passage into the component, such as, but not limited to, using an electrochemical drilling process. However, at least some such drilling processes are relatively time-consuming and expensive. Moreover, at least some such drilling processes cannot produce an internal passage curvature required for certain component designs.

BRIEF DESCRIPTION

In one aspect, a mold assembly for use in forming a component having a first internal passage defined therein is provided. The component is formed from a component material. The mold assembly includes a mold that defines a mold cavity therein. The mold assembly also includes a lattice structure selectively positioned at least partially within the mold cavity and formed from a first material. The first material is at least partially absorbable by the component material in a molten state. The mold assembly further includes a first segmented core that includes at least one joint segment coupled to the lattice structure. The at least one joint segment of the first segmented core is coupled in serial flow communication to at least one extension segment such that a first hollow structure is defined. A first inner core is disposed within the first hollow structure such that at least a portion of the first inner core defines the first internal passage when the component is formed in the mold assembly.
In another aspect, a method of forming a component having a first internal passage defined therein is provided. The method includes selectively positioning a lattice structure at least partially within a cavity of a mold. The lattice structure is formed from a first material. At least one joint segment of a first segmented core is coupled to the lattice structure. The at least one joint segment of the first segmented core is coupled in serial flow communication to at least one extension segment of the first segmented core such that a first hollow structure is defined. A first inner core is disposed within the first hollow structure. The method also includes introducing a component material in a molten state into the cavity, such that the component material in the molten state at least partially absorbs the first material from the lattice structure. The method further includes cooling the component material in the mold cavity to form the component. At least a portion of the first inner core defines the first internal passage within the component.

DRAWINGS

FIG. 1 is a schematic diagram of an exemplary rotary machine;

FIG. 2 is a schematic perspective view of an exemplary component for use with the rotary machine shown in FIG. 1;

FIG. 3 is a schematic perspective view of an exemplary mold assembly for making the component shown in FIG. 2;

FIG. 4 is a schematic cross-section of an exemplary segmented core for use with the mold assembly shown in FIG. 3, taken along lines 4-4 shown in FIG. 3;

FIG. 5 is a schematic perspective view of an exemplary segmented core coupled to an exemplary lattice structure for use with the mold assembly shown in FIG. 3 and with the pattern die assembly shown in FIG. 6;

FIG. 6 is a schematic perspective view of an exemplary pattern die assembly for making a pattern of the component shown in FIG. 2, the pattern for use in making the mold assembly shown in FIG. 3;

FIG. 7 is a schematic perspective detail view of a portion of the exemplary lattice structure and segmented core shown in FIG. 5;

FIG. 8 is a schematic perspective view of a pair of exemplary segmented cores coupled to another exemplary lattice structure for use with the mold assembly shown in FIG. 3 and with the pattern die assembly shown in FIG. 6;

FIG. 9 is a schematic perspective detail view of a portion of the exemplary lattice structure and pair of segmented cores shown in FIG. 8;

FIG. 10 is a schematic sectional view of three exemplary embodiments of a joint between an exemplary joint segment and an exemplary extension segment that may be used to form a hollow structure of the segmented core shown in FIGS. 5 and 7;

FIG. 11 is a flow diagram of an exemplary method of forming a component having an internal passage defined therein, such as the component shown in FIG. 2; and

FIG. 12 is a continuation of the flow diagram from FIG. 11.

DETAILED DESCRIPTION

In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings.
The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms such as “about,” “approximately,” and “substantially” is not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be identified. Such ranges may be combined and/or interchanged, and include all the sub-ranges contained therein unless context or language indicates otherwise.
The exemplary components and methods described herein overcome at least some of the disadvantages associated with known assemblies and methods for forming a component having an internal passage defined therein. The embodiments described herein provide a lattice structure selectively positioned at least partially within a mold cavity. The lattice structure is coupled to at least one joint segment of a hollow structure. The hollow structure defines a segmented core, and the segmented core is positioned within the mold cavity by the lattice structure. The remainder of the hollow structure is formed from at least one extension segment that extends from the at least one joint segment. An inner core disposed within the hollow structure defines a position of the internal passage within the component when the component is cast in the mold. The lattice structure is formed from a first material selected to be absorbable by a component material introduced into the mold cavity to form the component. Thus, the lattice structure used to position and/or support the core need not be removed from the mold assembly prior to casting the component therein. In certain embodiments, each joint segment is integrally formed with a corresponding portion of the lattice structure.
FIG. 1 is a schematic view of an exemplary rotary machine 10 having components for which embodiments of the current disclosure may be used. In the exemplary embodiment, rotary machine 10 is a gas turbine that includes an intake section 12, a compressor section 14 coupled downstream from intake section 12, a combustor section 16 coupled downstream from compressor section 14, a turbine section 18 coupled downstream from combustor section 16, and an exhaust section 20 coupled downstream from turbine section 18. A generally tubular casing 36 at least partially encloses one or more of intake section 12, compressor section 14, combustor section 16, turbine section 18, and exhaust section 20. In alternative embodiments, rotary machine 10 is any rotary machine for which components formed with internal passages as described herein are suitable. Moreover, although embodiments of the present disclosure are described in the context of a rotary machine for purposes of illustration, it should be understood that the embodiments described herein are applicable in any context that involves a component suitably formed with an internal passage defined therein.
In the exemplary embodiment, turbine section 18 is coupled to compressor section 14 via a rotor shaft 22. It should be noted that, as used herein, the term “couple” is not limited to a direct mechanical, electrical, and/or communication connection between components, but may also include an indirect mechanical, electrical, and/or communication connection between multiple components.
During operation of rotary machine 10, intake section 12 channels air towards compressor section 14. Compressor section 14 compresses the air to a higher pressure and temperature. More specifically, rotor shaft 22 imparts rotational energy to at least one circumferential row of compressor blades 40 coupled to rotor shaft 22 within compressor section 14. In the exemplary embodiment, each row of compressor blades 40 is preceded by a circumferential row of compressor stator vanes 42 extending radially inward from casing 36 that direct the air flow into compressor blades 40. The rotational energy of compressor blades 40 increases a pressure and temperature of the air. Compressor section 14 discharges the compressed air towards combustor section 16.
In combustor section 16, the compressed air is mixed with fuel and ignited to generate combustion gases that are channeled towards turbine section 18. More specifically, combustor section 16 includes at least one combustor 24, in which a fuel, for example, natural gas and/or fuel oil, is injected into the air flow, and the fuel-air mixture is ignited to generate high temperature combustion gases that are channeled towards turbine section 18.
Turbine section 18 converts the thermal energy from the combustion gas stream to mechanical rotational energy. More specifically, the combustion gases impart rotational energy to at least one circumferential row of rotor blades 70 coupled to rotor shaft 22 within turbine section 18. In the exemplary embodiment, each row of rotor blades 70 is preceded by a circumferential row of turbine stator vanes 72 extending radially inward from casing 36 that direct the combustion gases into rotor blades 70. Rotor shaft 22 may be coupled to a load (not shown) such as, but not limited to, an electrical generator and/or a mechanical drive application. The exhausted combustion gases flow downstream from turbine section 18 into exhaust section 20. Components of rotary machine 10 are designated as components 80. Components 80 proximate a path of the combustion gases are subjected to high temperatures during operation of rotary machine 10. Additionally or alternatively, components 80 include any component suitably formed with an internal passage defined therein.
FIG. 2 is a schematic perspective view of an exemplary component 80, illustrated for use with rotary machine 10 (shown in FIG. 1). Component 80 includes at least one internal passage 82 defined therein. For example, a cooling fluid is provided to internal passage 82 during operation of rotary machine 10 to facilitate maintaining component 80 below a temperature of the hot combustion gases. Although only one internal passage 82 is illustrated, it should be understood that component 80 includes any suitable number of internal passages 82 formed as described herein.
Component 80 is formed from a component material 78. In the exemplary embodiment, component material 78 is a suitable nickel-based superalloy. In alternative embodiments, component material 78 is at least one of a cobalt-based superalloy, an iron-based alloy, and a titanium-based alloy. In other alternative embodiments, component material 78 is any suitable material that enables component 80 to be formed as described herein.
In the exemplary embodiment, component 80 is one of rotor blades 70 or stator vanes 72. In alternative embodiments, component 80 is another suitable component of rotary machine 10 that is capable of being formed with an internal passage as described herein. In still other embodiments, component 80 is any component for any suitable application that is suitably formed with an internal passage defined therein.
In the exemplary embodiment, rotor blade 70, or alternatively stator vane 72, includes a pressure side 74 and an opposite suction side 76. Each of pressure side 74 and suction side 76 extends from a leading edge 84 to an opposite trailing edge 86. In addition, rotor blade 70, or alternatively stator vane 72, extends from a root end 88 to an opposite tip end 90, defining a blade length 96. In alternative embodiments, rotor blade 70, or alternatively stator vane 72, has any suitable configuration that is capable of being formed with an internal passage as described herein.
In certain embodiments, blade length 96 is at least about 25.4 centimeters (cm) (10 inches). Moreover, in some embodiments, blade length 96 is at least about 50.8 cm (20 inches). In particular embodiments, blade length 96 is in a range from about 61 cm (24 inches) to about 101.6 cm (40 inches). In alternative embodiments, blade length 96 is less than about 25.4 cm (10 inches). For example, in some embodiments, blade length 96 is in a range from about 2.54 cm (1 inch) to about 25.4 cm (10 inches). In other alternative embodiments, blade length 96 is greater than about 101.6 cm (40 inches).
In the exemplary embodiment, internal passage 82 extends from root end 88 to tip end 90. In alternative embodiments, internal passage 82 extends within component 80 in any suitable fashion, and to any suitable extent, that enables internal passage 82 to be formed as described herein. In certain embodiments, internal passage 82 is nonlinear. For example, component 80 is formed with a predefined twist along an axis 89 defined between root end 88 and tip end 90, and internal passage 82 has a curved shape complementary to the axial twist. In some embodiments, internal passage 82 is positioned at a substantially constant distance 94 from pressure side 74 along a length of internal passage 82. Alternatively or additionally, a chord of component 80 tapers between root end 88 and tip end 90, and internal passage 82 extends nonlinearly complementary to the taper, such that internal passage 82 is positioned at a substantially constant distance 92 from trailing edge 86 along the length of internal passage 82. In alternative embodiments, internal passage 82 has a nonlinear shape that is complementary to any suitable contour of component 80. In other alternative embodiments, internal passage 82 is nonlinear and other than complementary to a contour of component 80. In some embodiments, internal passage 82 having a nonlinear shape facilitates satisfying a preselected cooling criterion for component 80. In alternative embodiments, internal passage 82 extends linearly.
In some embodiments, internal passage 82 has a substantially circular cross-section. In alternative embodiments, internal passage 82 has a substantially ovoid cross-section. In other alternative embodiments, internal passage 82 has any suitably shaped cross-section that enables internal passage 82 to be formed as described herein. Moreover, in certain embodiments, the shape of the cross-section of internal passage 82 is substantially constant along a length of internal passage 82. In alternative embodiments, the shape of the cross-section of internal passage 82 varies along a length of internal passage 82 in any suitable fashion that enables internal passage 82 to be formed as described herein.
FIG. 3 is a schematic perspective view of a mold assembly 301 for making component 80 (shown in FIG. 2). Mold assembly 301 includes a lattice structure 340 selectively positioned with respect to a mold 300, and a segmented core 310 coupled to lattice structure 340. FIG. 4 is a schematic cross-section of segmented core 310 taken along lines 4-4 shown in FIG. 3. FIG. 5 is a schematic perspective view of segmented core 310 coupled to lattice structure 340. FIG. 6 is a schematic perspective view of a pattern die assembly 501 for making a pattern (not shown) of component 80 (shown in FIG. 2). Pattern die assembly 501 includes lattice structure 340 selectively positioned with respect to a pattern die 500, and segmented core 310 coupled to lattice structure 340. It should be recalled that, although component 80 in the exemplary embodiment is rotor blade 70 or, alternatively stator vane 72, in alternative embodiments component 80 is any component suitably formable with an internal passage defined therein, as described herein.
With reference to FIGS. 2-6, an interior wall 502 of pattern die 500 defines a die cavity 504. At least a portion of lattice structure 340 is positioned within die cavity 504. Interior wall 502 defines a shape corresponding to an exterior shape of component 80, such that a pattern material (not shown) in a flowable state can be introduced into die cavity 504 and solidified to form a pattern (not shown) of component 80. Segmented core 310 is positioned by lattice structure 340 with respect to pattern die 500 such that a portion 315 of segmented core 310 extends within die cavity 504. Thus, lattice structure 340 and segmented core 310 become encased by the pattern when the pattern is formed in pattern die 500.
Segmented core 310 includes a hollow structure 320 formed from a first material 322, and an inner core 324 disposed within hollow structure 320 and formed from an inner core material 326. Inner core 324 is shaped to define a shape of internal passage 82. Hollow structure 320 is shaped to substantially enclose inner core 324 along a length of inner core 324. In certain embodiments, hollow structure 320 defines a generally tubular shape suitably formed as a nonlinear shape, such as a curved or angled shape, as necessary to define a selected nonlinear shape of inner core 324 and, thus, of internal passage 82. In alternative embodiments, hollow structure 320 defines any suitable shape that enables inner core 324 to define a shape of internal passage 82 as described herein.
Lattice structure 340 is selectively positioned in a preselected orientation within die cavity 504, such that inner core 324 of portion 315 of segmented core 310 fixedly coupled to lattice structure 340 subsequently defines internal passage 82 within component 80 when component 80 is formed in mold 300 (shown in FIG. 3). In some embodiments, lattice structure 340 at least partially supports segmented core 310 suspended within die cavity 504 and/or within a mold cavity 304 defined within mold 300.
In certain embodiments, lattice structure 340 defines a perimeter 342 shaped to couple against interior wall 502, such that lattice structure 340 is selectively positioned within die cavity 504. More specifically, perimeter 342 conforms to the shape of interior wall 502 to position and/or maintain lattice structure 340 in the preselected orientation with respect to die cavity 504. Additionally or alternatively, lattice structure 340 is selectively positioned and/or maintained in the preselected orientation within die cavity 504 in any suitable fashion that enables pattern die assembly 501 to function as described herein. For example, but not by way of limitation, lattice structure 340 is securely positioned with respect to die cavity 504 by suitable external fixturing (not shown).
In the exemplary embodiment, hollow structure 320 has a wall thickness 328 that is less than a characteristic width 330 of inner core 324. Characteristic width 330 is defined herein as the diameter of a circle having the same cross-sectional area as inner core 324. In alternative embodiments, hollow structure 320 has a wall thickness 328 that is other than less than characteristic width 330. A shape of a cross-section of inner core 324 is circular in the exemplary embodiment shown in FIGS. 3 and 4. Alternatively, the shape of the cross-section of inner core 324 corresponds to any suitable shape of the cross-section of internal passage 82 that enables internal passage 82 to function as described herein.
In the exemplary embodiment, inner core material 326 is a refractory ceramic material selected to withstand a high temperature environment associated with the molten state of component material 78 used to form component 80. For example, but without limitation, inner core material 326 includes at least one of silica, alumina, and mullite. Moreover, in the exemplary embodiment, inner core material 326 is selectively removable from component 80 to form internal passage 82. For example, but not by way of limitation, inner core material 326 is removable from component 80 by a suitable process that does not substantially degrade component material 78, such as, but not limited to, a suitable chemical leaching process. In certain embodiments, inner core material 326 is selected based on a compatibility with, and/or a removability from, component material 78. In alternative embodiments, inner core material 326 is any suitable material that enables component 80 to be formed as described herein.
In some embodiments, segmented core 310 is formed by filling hollow structure 320 with inner core material 326. For example, but not by way of limitation, inner core material 326 is injected as a slurry into hollow structure 320, and inner core material 326 is dried within hollow structure 320 to form segmented core 310. Moreover, in certain embodiments, hollow structure 320 substantially structurally reinforces inner core 324, thus reducing potential problems that would be associated with production, handling, and use of an unreinforced inner core 324 to form component 80 in some embodiments. For example, in certain embodiments, inner core 324 is a relatively brittle ceramic material subject to a relatively high risk of fracture, cracking, and/or other damage. Thus, in some such embodiments, forming and manipulating segmented core 310 coupled to lattice structure 340 presents a much lower risk of damage to inner core 324, as compared to using an unjacketed inner core 324. Similarly, in some such embodiments, forming a suitable pattern around lattice structure 340 and segmented core 310 to be used for forming mold 300, such as by injecting a wax pattern material into a pattern die around segmented core 310, presents a much lower risk of damage to inner core 324, as compared to using an unjacketed inner core 324. Thus, in certain embodiments, use of segmented core 310 coupled to lattice structure 340 presents a much lower risk of failure to produce an acceptable component 80 having internal passage 82 defined therein, as compared to the same steps if performed using an unjacketed inner core 324 rather than segmented core 310. Thus, segmented core 310 and lattice structure 340 facilitate obtaining advantages associated with positioning inner core 324 with respect to mold 300 to define internal passage 82, while reducing or eliminating fragility problems associated with inner core 324.
In certain embodiments, lattice structure 340 includes a plurality of interconnected elongated members 346 that define a plurality of open spaces 348 therebetween. Elongated members 346 are arranged to provide lattice structure 340 with a structural strength and stiffness such that, when lattice structure 340 is positioned in the preselected orientation within die cavity 504, inner core 324 is maintained in the selected orientation to subsequently define the position of internal passage 82 within component 80. In some embodiments, pattern die assembly 501 includes suitable additional structure configured to maintain inner core 324 in the selected orientation, such as, but not limited to, while the pattern material (not shown) is added to die cavity 504 around inner core 324.
In the exemplary embodiment, elongated members 346 include sectional elongated members 347. Sectional elongated members 347 are arranged in groups 350. Each group 350 of sectional elongated members 347 is directly coupled to segmented core 310. In certain embodiments, each group 350 defines a respective cross-sectional portion of perimeter 342 shaped to conform to a corresponding cross-section of die cavity 504 to maintain each group 350 in the preselected orientation. Additionally or alternatively, elongated members 346 include stringer elongated members 352, and each stringer elongated member 352 extends between at least two of groups 350 of sectional elongated members 347 to facilitate positioning and/or maintaining each group 350 in the preselected orientation. In some embodiments, stringer elongated members 352 further define perimeter 342 conformal to interior wall 502. Additionally or alternatively, at least one group 350 is coupled to suitable additional structure, such as but not limited to external fixturing, configured to maintain group 350 in the preselected orientation, such as, but not limited to, while the pattern material (not shown) is added to die cavity 504 around inner core 324.
In alternative embodiments, elongated members 346 are arranged in any suitable fashion that enables lattice structure 340 to function as described herein. For example, elongated members 346 are arranged in a non-uniform and/or non-repeating arrangement. In other alternative embodiments, lattice structure 340 is any suitable structure that enables selective positioning of core 324 as described herein.
In some embodiments, plurality of open spaces 348 is arranged such that each region of lattice structure 340 is in flow communication with substantially each other region of lattice structure 340. Thus, when the flowable pattern material is added to die cavity 504, lattice structure 340 enables the pattern material to flow through and around lattice structure 340 to fill die cavity 504. In alternative embodiments, lattice structure 340 is arranged such that at least one region of lattice structure 340 is not substantially in flow communication with at least one other region of lattice structure 340. For example, but not by way of limitation, the pattern material is injected into die cavity 504 at a plurality of locations to facilitate filling die cavity 504 around lattice structure 340.
Mold 300 is formed from a mold material 306. In the exemplary embodiment, mold material 306 is a refractory ceramic material selected to withstand a high temperature environment associated with the molten state of component material 78 used to form component 80. In alternative embodiments, mold material 306 is any suitable material that enables component 80 to be formed as described herein. Moreover, in the exemplary embodiment, mold 300 is formed from the pattern made in pattern die 500 by a suitable investment casting process. For example, but not by way of limitation, a suitable pattern material, such as wax, is injected into pattern die 500 around lattice structure 340 and segmented core 310 to form the pattern (not shown) of component 80, the pattern is repeatedly dipped into a slurry of mold material 306 which is allowed to harden to create a shell of mold material 306, and the shell is dewaxed and fired to form mold 300. After dewaxing, because lattice structure 340 and segmented core 310 were at least partially encased in the pattern used to form mold 300, lattice structure 340 and segmented core 310 remain positioned with respect to mold 300 to form mold assembly 301, as described above. In alternative embodiments, mold 300 is formed from the pattern made in pattern die 500 by any suitable method that enables mold 300 to function as described herein.
An interior wall 302 of mold 300 defines mold cavity 304. Because mold 300 is formed from the pattern made in pattern die assembly 501, interior wall 302 defines a shape corresponding to the exterior shape of component 80, such that component material 78 in a molten state can be introduced into mold cavity 304 and cooled to form component 80. It should be recalled that, although component 80 in the exemplary embodiment is rotor blade 70, or alternatively stator vane 72, in alternative embodiments component 80 is any component suitably formable with an internal passage defined therein, as described herein.
In addition, at least a portion of lattice structure 340 is selectively positioned within mold cavity 304. More specifically, lattice structure 340 is positioned in a preselected orientation with respect to mold cavity 304, substantially identical to the preselected orientation of lattice structure 340 with respect to die cavity 504. In addition, lattice structure 340 in the preselected orientation orients inner core 324 of portion 315 of segmented core 310 to define internal passage 82 within component 80 when component 80 is formed in mold 300 (shown in FIG. 3).
In various embodiments, at least some of the previously described elements of embodiments of lattice structure 340 are positioned with respect to mold cavity 304 in a manner that corresponds to the positioning of those elements described above in corresponding embodiments with respect to die cavity 504 of pattern die 500. For example, it should be understood that, after shelling of the pattern formed in pattern die 500, removal of the pattern material, and firing to form mold assembly 301, each of the previously described elements of embodiments of lattice structure 340 are positioned with respect to mold cavity 304 as they were positioned with respect to die cavity 504 of pattern die 500. Alternatively, lattice structure 340 and segmented core 310 are not embedded in a pattern used to form mold 300, but rather are subsequently positioned with respect to mold 300 to form mold assembly 301 such that, in various embodiments, perimeter 342, elongated members 346, sectional elongated members 347, plurality of open spaces 348, groups 350 of sectional elongated members 347, and/or stringer elongated members 352, are positioned in relationships to interior wall 302 and mold cavity 304 of mold 300 that correspond to the relationships described above with respect to interior wall 502 and die cavity 504.
Thus, in certain embodiments, perimeter 342 is shaped to couple against interior wall 302, such that lattice structure 340 is selectively positioned within mold cavity 304, and more specifically, perimeter 342 conforms to the shape of interior wall 302 to position lattice structure 340 in the preselected orientation with respect to mold cavity 304. Additionally or alternatively, elongated members 346 are arranged to provide lattice structure 340 with a structural strength and stiffness such that, when lattice structure 340 is positioned in the preselected orientation within mold cavity 304, inner core 324 is maintained in the selected orientation to subsequently define the position of internal passage 82 within component 80. Additionally or alternatively, plurality of open spaces 348 is arranged such that each region of lattice structure 340 is in flow communication with substantially each other region of lattice structure 340. Additionally or alternatively, groups 350 of sectional elongated members 347 are each directly coupled to segmented core 310. Additionally or alternatively, each group 350 defines a respective cross-sectional portion of perimeter 342 shaped to conform to a corresponding cross-section of mold cavity 304 to maintain each group 350 in the preselected orientation. Additionally or alternatively, stringer elongated members 352 each extend between at least two of groups 350 of sectional elongated members 347 to facilitate positioning and/or maintaining each group 350 in the preselected orientation, and/or to further define perimeter 342 conformal to interior wall 302. Additionally or alternatively, in some embodiments, at least one group 350 is coupled to suitable additional structure, such as but not limited to external fixturing, configured to maintain group 350 in the preselected orientation, such as, but not limited to, while component material 78 in a molten state is added to mold cavity 304 around inner core 324.
In certain embodiments, segmented core 310 is further secured relative to mold 300 such that segmented core 310 remains fixed relative to mold 300 during a process of forming component 80. For example, segmented core 310 is further secured to inhibit shifting of lattice structure 340 and segmented core 310 during introduction of molten component material 78 into mold cavity 304 surrounding segmented core 310. In some embodiments, segmented core 310 is coupled directly to mold 300. For example, in the exemplary embodiment, a tip portion 312 of segmented core 310 is rigidly encased in a tip portion 314 of mold 300. Additionally or alternatively, a root portion 316 of segmented core 310 is rigidly encased in a root portion 318 of mold 300 opposite tip portion 314. For example, but not by way of limitation, tip portion 312 and/or root portion 316 extend out of die cavity 504 of pattern die 500, and thus extend out of the pattern formed in pattern die 500, and the investment process causes mold 300 to encase tip portion 312 and/or root portion 316. Additionally or alternatively, segmented core 310 is further secured relative to mold 300 in any other suitable fashion that further enables the position of segmented core 310 relative to mold 300 to remain fixed during a process of forming component 80.
Lattice structure 340 is formed from a first material 322 selected to be at least partially absorbable by molten component material 78. In certain embodiments, first material 322 is selected such that, after molten component material 78 is added to mold cavity 304 and first material 322 is at least partially absorbed by molten component material 78, a performance of component material 78 in a subsequent solid state is not degraded. For one example, component 80 is rotor blade 70, and absorption of first material 322 from lattice structure 340 does not substantially reduce a melting point and/or a high-temperature strength of component material 78, such that a performance of rotor blade 70 during operation of rotary machine 10 (shown in FIG. 1) is not degraded.
Because first material 322 is at least partially absorbable by component material 78 in a molten state such that a performance of component material 78 in a solid state is not substantially degraded, lattice structure 340 need not be removed from mold assembly 301 prior to introducing molten component material 78 into mold cavity 304. Thus, as compared to methods that require a positioning structure for the core to be mechanically or chemically removed, a use of lattice structure 340 in pattern die assembly 501 to position segmented core 310 with respect to die cavity 504 decreases a number of process steps, and thus reduces a time and a cost, required to form component 80 having internal passage 82.
In some embodiments, component material 78 is an alloy, and first material 322 is at least one constituent material of the alloy. For example, component material 78 is a nickel-based superalloy, and first material 322 is substantially nickel, such that first material 322 is substantially absorbable by component material 78 when component material 78 in the molten state is introduced into mold cavity 304. For another example, first material 322 includes a plurality of constituents of the superalloy that are present in generally the same proportions as found in the superalloy, such that local alteration of the composition of component material 78 by absorption of a relatively large amount of first material 322 is reduced.
In alternative embodiments, component material 78 is any suitable alloy, and first material 322 is at least one material that is at least partially absorbable by the molten alloy. For example, component material 78 is a cobalt-based superalloy, and first material 322 is at least one constituent of the cobalt-based superalloy, such as, but not limited to, cobalt. For another example, component material 78 is an iron-based alloy, and first material 322 is at least one constituent of the iron-based superalloy, such as, but not limited to, iron. For another example, component material 78 is a titanium-based alloy, and first material 322 is at least one constituent of the titanium-based superalloy, such as, but not limited to, titanium.
In certain embodiments, lattice structure 340 is configured to be substantially absorbed by component material 78 when component material 78 in the molten state is introduced into mold cavity 304. For example, a thickness of elongated members 346 is selected to be sufficiently small such that first material 322 of lattice structure 340 within mold cavity 304 is substantially absorbed by component material 78 when component material 78 in the molten state is introduced into mold cavity 304. In some such embodiments, first material 322 is substantially absorbed by component material 78 such that no discrete boundary delineates lattice structure 340 from component material 78 after component material 78 is cooled. Moreover, in some such embodiments, first material 322 is substantially absorbed such that, after component material 78 is cooled, first material 322 is substantially uniformly distributed within component material 78. For example, a concentration of first material 322 proximate an initial location of lattice structure 340 is not detectably higher than a concentration of first material 322 at other locations within component 80. For example, and without limitation, first material 322 is nickel and component material 78 is a nickel-based superalloy, and no detectable higher nickel concentration remains proximate the initial location of lattice structure 340 after component material 78 is cooled, resulting in a distribution of nickel that is substantially uniform throughout the nickel-based superalloy of formed component 80.
In alternative embodiments, the thickness of elongated members 346 is selected such that first material 322 is other than substantially absorbed by component material 78. For example, in some embodiments, after component material 78 is cooled, first material 322 is other than substantially uniformly distributed within component material 78. For example, a concentration of first material 322 proximate the initial location of lattice structure 340 is detectably higher than a concentration of first material 322 at other locations within component 80. In some such embodiments, first material 322 is partially absorbed by component material 78 such that a discrete boundary delineates lattice structure 340 from component material 78 after component material 78 is cooled. Moreover, in some such embodiments, first material 322 is partially absorbed by component material 78 such that at least a portion of lattice structure 340 remains intact after component material 78 is cooled.
FIG. 7 is a schematic perspective detail view of a portion of lattice structure 340 and segmented core 310. With reference to FIGS. 5 and 7, in the exemplary embodiment, hollow structure 320 is formed from a plurality of separate segments coupled together in serial flow communication. More specifically, hollow structure 320 is defined by at least one joint segment 354 coupled in serial flow communication to at least one extension segment 360. Each joint segment 354 is coupled to lattice structure 340, such that selective positioning of lattice structure 340 within mold cavity 304 also selectively orients segmented core 310 within mold cavity 304.
For example, in the exemplary embodiment, each joint segment 354 is coupled to a corresponding group 350 of sectional elongated members 347. In alternative embodiments, the at least one joint segment 354 is coupled to any suitable portion of lattice structure 340. In the exemplary embodiment, each joint segment 354 is integrally formed, that is, formed in the same process as a single unit, with a corresponding group 350 of sectional elongated members 347. In alternative embodiments, each joint segment 354 is coupled to a corresponding group 350 of sectional elongated members 347, or to another suitable portion of lattice structure 340, in any other suitable fashion that enables segmented core 310 to function as described herein. Each extension segment 360 extends in flow communication between a pair of joint segments 354, or, alternatively, in flow communication between one of a first end 321 and an opposite second end 323 of hollow structure 320 and a joint segment 354.
More specifically, joint segments 354 and extension segments 360 are coupled together in serial flow communication such that inner core 324 is formable by filling hollow structure 320 with core material 326 from at least one of first end 321 and second end 323. For example, but not by way of limitation, core material 326 is injected as a slurry into at least one of first end 321 and second end 323 of hollow structure 320, such that inner core material 326 substantially fills joint segments 354 and extension segments 360 coupled together in serial flow communication. Inner core material 326 is dried within hollow structure 320 to form inner core 324. In alternative embodiments, inner core is formed in any suitable fashion that enables segmented core 310 to function as described herein.
In some embodiments, a longitudinal position of at least one joint segment 354 along hollow structure 320 corresponds to a region 356 of relatively high curvature of hollow structure 320. Additionally or alternatively, a longitudinal position of at least one joint segment 354 along hollow structure 320 corresponds to a region 366 at which hollow structure 320 defines a change in cross-sectional flow area of internal passage 82. Additionally or alternatively, a longitudinal position of at least one joint segment 354 along hollow structure 320 corresponds to a region 358 at which structural support from lattice structure 340 facilitates stabilization of a position of segmented core 310 with respect to another segmented core 310 (not shown) coupled to lattice structure 340, die cavity 504 and/or mold cavity 304. Thus, in certain embodiments, formation of segmented core 310 from separate joint segments 354 and extension segments 360 facilitates detailed shaping of each joint segment 354 as necessary to meet requirements for curvature, transition of internal cross-section, and/or precision of positioning of internal passages 82 relative to each other and within component 80, and relatively faster and inexpensive shaping of extension segments 360 for coupling to joint segments 354 to complete hollow structure 320.
In the exemplary embodiment, each joint segment 354 and extension segment 360 of hollow structure 320 is formed from at least one of first material 322 and a second material (not shown) that is also selected to be at least partially absorbable by molten component material 78. Thus, as with lattice structure 340, after molten component material 78 is added to mold cavity 304 and first material 322 and/or the second material is at least partially absorbed by molten component material 78, a performance of component material 78 in a subsequent solid state is not substantially degraded. Because first material 322 and/or the second material is at least partially absorbable by component material 78 in the molten state such that a performance of component material 78 in a solid state is not substantially degraded, hollow structure 320 need not be removed from mold assembly 301 prior to introducing molten component material 78 into mold cavity 304. In alternative embodiments, each joint segment 354 and each extension segment 360 is formed from any suitable material that enables segmented core 310 to function as described herein.
In certain embodiments, each group 350 of sectional elongated members 347 is integrally formed with the corresponding joint segment 354 of hollow structure 320 using a suitable additive manufacturing process. For example, a computer design model of the group 350 of sectional elongated members 347 and joint segment 354 is sliced into a series of thin, parallel planes between a first end 371 and a second end 373. A computer numerically controlled (CNC) machine deposits successive layers of first material 322 from first end 371 to second end 373 in accordance with the model slices to simultaneously form the group 350 of sectional elongated members 347 and joint segment 354. In some embodiments, the successive layers of first material 322 are deposited using at least one of a direct metal laser melting (DMLM) process, a direct metal laser sintering (DMLS) process, and a selective laser sintering (SLS) process. Additionally or alternatively, at least one group 350 of sectional elongated members 347 and the corresponding joint segment 354 are integrally formed using another suitable additive manufacturing process.
In certain embodiments, at least one stringer elongated member 352 is formed integrally with at least one group 350 of sectional elongated members 347. Additionally or alternatively, at least one stringer elongated member 352 is coupled between at least two separately formed groups 350 of sectional elongated members 347. In alternative embodiments, lattice structure does not include stringer elongated members 352.
In some embodiments, each extension segment 360 is initially formed from a substantially straight metal tube that is suitably manipulated into a nonlinear shape, such as a curved or angled shape, as necessary to define a selected nonlinear shape of the corresponding portion of inner core 324 and, thus, of the corresponding portion of internal passage 82. For example, each extension segment 360 is formed from an extruded tube segment. In certain embodiments, each extension segment 360 is formed from a standard or commercial-off-the-shelf tube, reducing a cost of manufacture of hollow structure 320. In alternative embodiments, each extension segment 360 is formed in any suitable fashion that enables segmented core 310 to function as described herein.
In some embodiments, the integral formation of each group 350 of sectional elongated members 347 and the corresponding joint segment 354 of hollow structure 320 by an additive manufacturing process enables the combination of lattice structure 340 and joint segments 354 to be formed with a structural intricacy, precision, and/or repeatability that is not achievable by other methods. Moreover, the integral formation of each group 350 of sectional elongated members 347 and the corresponding joint segment 354 of hollow structure 320 by an additive manufacturing process enables joint segments 354 to be formed with a high degree of nonlinearity, if necessary to define a correspondingly nonlinear internal passage 82, and to simultaneously be supported by lattice structure 340, without design constraints imposed by a need to insert a nonlinear core into lattice structure 340 in a subsequent separate step. Accordingly, the integral formation of each group 350 of sectional elongated members 347 and the corresponding joint segment 354 of hollow structure 320 by an additive manufacturing process enables the shaping and positioning of joint segments 354, and thus the positioning of inner core 324 and internal passage 82, with a correspondingly increased structural intricacy, precision, and/or repeatability.
In addition, the integral formation of each group 350 of sectional elongated members 347 and the corresponding joint segment 354 of hollow structure 320 by an additive manufacturing process enables lattice structure 340 and joint segments 354 to be formed using first material 322 that is a combination of materials, such as, but not limited to, a plurality of constituents of component material 78, as described above. For example, the additive manufacturing process includes alternating deposition of each a plurality of materials, and the alternating deposition is suitably controlled to produce lattice structure 340 and joint segments 354 having a selected proportion of the plurality of constituents. In alternative embodiments, each group 350 of sectional elongated members 347 and the corresponding joint segment 354 are formed and coupled together in any suitable fashion that enables lattice structure 340 and hollow structure 320 to function as described herein.
In certain embodiments, an inner surface of joint segments 354 formed by an additive manufacturing process has a relatively high surface roughness that results in a relatively high surface roughness of the corresponding portions of inner core 324 and internal passage 82. The resulting relatively high surface roughness of internal passage 82 alters a characteristic, such as but not limited to a heat transfer characteristic, of internal passage 82 along portions defined by joint segments 354. In some such embodiments, extension segments 360 are formed in a non-additive fashion, such as but not limited to a tube extrusion process, that results in a relatively low surface roughness of an inner wall of extension segments 360 as compared to joint segments 354 and, thus, a relatively low surface roughness of the corresponding portions of inner core 324 and internal passage 82. Moreover, in some such embodiments, joint segments 354 constitute a relatively short portion of an overall length of hollow structure 320, as compared to extension segments 360. Thus, in some embodiments, the integral formation of each group 350 of sectional elongated members 347 and the corresponding joint segment 354 of hollow structure 320 by an additive manufacturing process, in combination with the use of non-additively formed extension segments 360, enables formation of internal passage 82 defined by an inner wall having a low surface roughness over a portion of its length defined by extension segments 360, while providing the above-described benefits associated with additive manufacture of lattice structure 340 and joint segments 354.
As described above, although only one internal passage 82 is illustrated in FIG. 2, and thus only one segmented core 310 is illustrated in FIGS. 3, 5, and 6, it should be understood that component 80 includes any suitable number of internal passages 82 formed as described herein. For example, FIG. 8 is a schematic perspective view of two segmented cores 310, which will also be referred to as first segmented core 801 and second segmented core 802 for purposes of discussion, coupled to lattice structure 340. FIG. 9 is a schematic perspective detail view of a portion of lattice structure 340 and first segmented core 801 and second segmented core 802.
With reference to FIGS. 8 and 9, in various embodiments, each of first segmented core 801 and second segmented core 802 has the features described above with respect to corresponding embodiments of segmented core 310. For example, in the exemplary embodiment, hollow structure 320 of each of first segmented core 801 and second segmented core 802 is again formed from a plurality of separate segments coupled together in serial flow communication. More specifically, each hollow structure 320 again includes at least one joint segment 354 coupled in serial flow communication to at least one extension segment 360. Each joint segment 354 is again coupled to a corresponding group 350 of sectional elongated members 347, for example by integral formation or another suitable fashion, such that the at least one joint segment 354 couples the respective segmented core 801 or 802 to lattice structure 340. Each extension segment 360 of each hollow structure 320 again extends in flow communication between a pair of joint segments 354 of the respective hollow structure 320, or, alternatively, with one of a first end 321 and an opposite second end 323 of the respective hollow structure 320. Inner core 324 of each of first segmented core 801 and second segmented core 802 is again formable by filling the respective hollow structure 320 with core material 326 from at least one of first end 321 and second end 323, or alternatively in another suitable fashion.
In some embodiments, a longitudinal position of at least one joint segment 354 corresponds to a region 356 of relatively high curvature of hollow structure 320 of at least one of first segmented core 801 and second segmented core 802. Additionally or alternatively, a longitudinal position of at least one joint segment 354 corresponds to a region 366 at which hollow structure 320 of at least one of first segmented core 801 and second segmented core 802 defines a change in cross-sectional flow area of the respective internal passage 82. Additionally or alternatively, a longitudinal position of at least one joint segment 354 corresponds to a region 358 at which structural support from lattice structure 340 facilitates stabilization of a position of at least one of first segmented core 801 and second segmented core 802 with respect to another of first segmented core 801 and second segmented core 802, and/or with respect to die cavity 504 and/or mold cavity 304. Thus, in certain embodiments, formation of first segmented core 801 and second segmented core 802 from separate joint segments 354 and extension segments 360 again facilitates detailed shaping of each joint segment 354 as necessary to meet requirements for curvature, transition of internal cross-section, and/or precision of positioning of internal passages 82 relative to each other and within component 80, and relatively faster and inexpensive shaping of extension segments 360 for coupling to joint segments 354 to complete hollow structure 320.
In the exemplary embodiment, each joint segment 354 and extension segment 360 of hollow structure 320 is again formed from at least one of first material 322 and a second material (not shown) that is also selected to be at least partially absorbable by molten component material 78, as described above.
In certain embodiments, each group 350 of sectional elongated members 347 is integrally formed with the corresponding joint segment 354 of hollow structure 320 using a suitable additive manufacturing process, also as described above. For example, a computer design model of the group 350 of sectional elongated members 347 and joint segment 354 of each of first segmented core 801 and second segmented core 802 is sliced into a series of thin, parallel planes between a first end 371 and a second end 373. A computer numerically controlled (CNC) machine deposits successive layers of first material 322 from first end 371 to second end 373 in accordance with the model slices to simultaneously form the group 350 of sectional elongated members 347 and respective joint segments 354. In some embodiments, the successive layers of first material 322 are again deposited using a direct metal laser melting (DMLM) process, a direct metal laser sintering (DMLS) process, a selective laser sintering (SLS) process, or another suitable additive manufacturing process.
Again, in certain embodiments, at least one stringer elongated member 352 is formed integrally with at least one group 350 of sectional elongated members 347. Additionally or alternatively, at least one stringer elongated member 352 is coupled between at least two separately formed groups 350 of sectional elongated members 347. In alternative embodiments, lattice structure does not include stringer elongated members 352.
In some embodiments, each extension segment 360 of each of first segmented core 801 and second segmented core 802 is initially formed from a substantially straight metal tube that is suitably manipulated into a nonlinear shape as necessary to define a selected nonlinear shape of the corresponding portion of the respective inner core 324 and, thus, of the corresponding portion of the respective internal passage 82.
In some embodiments, the integral formation of each group 350 of sectional elongated members 347 and the corresponding joint segments 354 of first segmented core 801 and second segmented core 802 by an additive manufacturing process enables the combination of lattice structure 340 and joint segments 354 to be formed with a structural intricacy, precision, and/or repeatability that is not achievable by other methods. Moreover, the integral formation of each group 350 of sectional elongated members 347 and the corresponding joint segments 354 of first segmented core 801 and second segmented core 802 by an additive manufacturing process enables joint segments 354 to be formed with a high degree of nonlinearity, if necessary to define a correspondingly nonlinear internal passage 82, and to simultaneously be supported by lattice structure 340, without design constraints imposed by a need to insert a plurality of nonlinear cores into lattice structure 340 in a subsequent separate step. Accordingly, the integral formation of each group 350 of sectional elongated members 347 and the corresponding joint segments 354 of first segmented core 801 and second segmented core 802 by an additive manufacturing process enables the shaping and positioning of joint segments 354, and thus the positioning of respective inner cores 324 and internal passages 82 defined by first segmented core 801 and second segmented core 802, with a correspondingly increased structural intricacy, precision, and/or repeatability.
In addition, in certain embodiments, the integral formation of each group 350 of sectional elongated members 347 and the corresponding joint segments 354 of first segmented core 801 and second segmented core 802 by an additive manufacturing process again enables lattice structure 340 and joint segments 354 to be formed using first material 322 that is a combination of materials, such as, but not limited to, a plurality of constituents of component material 78, as described above.
Again, in some embodiments, the integral formation of each group 350 of sectional elongated members 347 and the corresponding joint segments 354 of first segmented core 801 and second segmented core 802 by an additive manufacturing process, in combination with the use of non-additively formed extension segments 360, enables formation of each internal passage 82 defined by an inner wall having a low surface roughness over a portion of its length defined by extension segments 360, while providing the above-described benefits associated with additive manufacture of lattice structure 340 and joint segments 354.
FIG. 10 is a schematic sectional view of three exemplary embodiments of a joint 380 between joint segment 354 and extension segment 360 that may be used to form hollow structure 320 of segmented core 310. With reference to FIGS. 5 and 7-10, in the first embodiment shown on the left in FIG. 10, joint 380 is an externally flush joint between joint segment 354 and extension segment 360. In the exemplary embodiment, an inner width 386 of joint segment 354 is less than an inner width 388 of extension segment 360, and an outer width of a mating end 382 of joint segment 354 is reduced in step fashion to be received within inner width 388 of a mating end 384 of extension segment 360, such that the outer surfaces of joint segment 354 and extension segment 360 are flush. In alternative embodiments (not shown), inner width 386 of joint segment 354 is substantially equal to inner width 388 of extension segment 360, and inner width 388 of mating end 384 of extension segment 360 is increased in step fashion, such that the outer and inner surfaces of joint segment 354 and extension segment 360 are flush. In other alternative embodiments (not shown), inner width 386 of joint segment 354 is greater than inner width 388 of extension segment 360, and the outer width of mating end 384 of extension segment 360 is reduced in step fashion to be received within inner width 386 of mating end 382 of joint segment 354, such that the outer surfaces of joint segment 354 and extension segment 360 are flush.
In the second embodiment shown in the middle in FIG. 10, joint 380 is a diverging joint between joint segment 354 and extension segment 360. In the exemplary embodiment, mating end 382 of joint segment 354 is flared in diverging fashion to receive mating end 384 of extension segment 360 therewithin. In alternative embodiments (not shown), mating end 384 of extension segment 360 is flared in diverging fashion to receive mating end 382 of joint segment 354 therewithin. In the exemplary embodiment, inner width 386 of joint segment 354 is substantially equal to inner width 388 of extension segment 360. In alternative embodiments (not shown), inner width 386 of joint segment 354 is other than substantially equal to inner width 388 of extension segment 360.
In the third embodiment shown on the right in FIG. 10, joint 380 is a converging joint between joint segment 354 and extension segment 360. In the exemplary embodiment, mating end 382 of joint segment 354 is narrowed in converging fashion to be received within mating end 384 of extension segment 360. In alternative embodiments (not shown), mating end 384 of extension segment 360 is narrowed in converging fashion to be received within mating end 382 of joint segment 354. In the exemplary embodiment, inner width 386 of joint segment 354 is greater than inner width 388 of extension segment 360. In alternative embodiments (not shown), inner width 386 of joint segment 354 is less than or equal to inner width 388 of extension segment 360.
In alternative embodiments, joint segment 354 and extension segment 360 are joined in any suitable fashion that enables hollow structure 320 to function as described herein.
An exemplary method 900 of forming a component, such as component 80, having an internal passage defined therein, such as internal passage 82, is illustrated in a flow diagram in FIGS. 11 and 12. With reference also to FIGS. 1-10, exemplary method 900 includes selectively positioning 902 a lattice structure, such as lattice structure 340, at least partially within a cavity of a mold, such as mold cavity 304 of mold 300. The lattice structure is formed from a first material, such as first material 322. At least one joint segment, such as joint segment 354, of a first segmented core, such as segmented core 310 or 801, is coupled to the lattice structure. The at least one joint segment is coupled in serial flow communication to at least one extension segment, such as extension segment 360, of the first segmented core such that a first hollow structure, such as hollow structure 320, is defined. A first inner core, such as inner core 324, is disposed within the first hollow structure.
Method 900 also includes introducing 904 a component material, such as component material 78, in a molten state into the mold cavity, such that the component material in the molten state at least partially absorbs the first material from the lattice structure. Method 900 further includes cooling 906 the component material in the mold cavity to form the component. At least a portion of the first inner core defines the first internal passage within the component.
In some embodiments, the mold includes an interior wall, such as interior wall 302 of mold 300, that defines the cavity and the lattice structure defines a perimeter, such as perimeter 342, and the step of selectively positioning 902 the lattice structure includes coupling 928 the perimeter of the lattice structure against the interior wall of the mold.
In certain embodiments, at least one joint segment of a second segmented core, such as second segmented core 802, is coupled to the lattice structure, the at least one joint segment of the second segmented core is coupled in serial flow communication to at least one extension segment of the second segmented core such that a second hollow structure is defined, a second inner core is disposed within the second hollow structure, and the step of cooling 906 the component material in the cavity to form the component further includes cooling 930 the component material in the cavity wherein at least a portion of the second inner core defines a second internal passage within the component.
In some embodiments, the step of coupling 902 the perimeter of the lattice structure against the interior wall includes coupling 908 the perimeter of the lattice structure that includes a plurality of sectional elongated members, such as sectional elongated members 347, and each at least one joint segment is coupled to a corresponding group, such as group 350, of the sectional elongated members. Moreover, in some such embodiments, the step of coupling 902 the perimeter of the lattice structure against the interior wall includes coupling 910 the perimeter of the lattice structure that includes each at least one joint segment formed integrally with the corresponding group of sectional elongated members by an additive manufacturing process.
In certain embodiments, the step of selectively positioning 902 the lattice structure includes selectively positioning 912 the lattice structure wherein an inner wall of the at least one extension segment has a relatively low surface roughness as compared to an inner wall of the at least one joint segment.
In some embodiments, the step of selectively positioning 902 the lattice structure includes selectively positioning 914 the lattice structure wherein a longitudinal position of the at least one joint segment corresponds to a region of relatively high curvature of the first hollow structure, such as region 356. Additionally or alternatively, the step of selectively positioning 902 the lattice structure includes selectively positioning 916 the lattice structure wherein a longitudinal position of the at least one joint segment corresponds to a region at which the first hollow structure defines a change in a cross-sectional flow area of the first internal passage, such as region 366. Additionally or alternatively, the step of selectively positioning 902 the lattice structure includes selectively positioning 918 the lattice structure wherein a longitudinal position of the at least one joint segment corresponds to a region at which structural support from the lattice structure facilitates stabilization of a position of the first segmented core.
In certain embodiments, the step of selectively positioning 902 the lattice structure includes selectively positioning 920 the lattice structure wherein the at least one extension segment is formed from at least one extruded tube segment.
In some embodiments, the step of introducing 904 the component material includes introducing 922 the component material such that a performance of the component material in a solid state is not degraded by the at least partial absorption of the first material. In some such embodiments, the step of introducing 904 the component material includes introducing 924 an alloy in a molten state into the mold cavity, and the first material comprises at least one constituent material of the alloy.
In certain embodiments, the step of selectively positioning 902 the lattice structure includes selectively positioning 926 the lattice structure wherein the at least one joint segment and the at least one extension segment are coupled together by at least one of an externally flush joint, a diverging joint, and a converging joint, such as joints 380 shown on the left, middle, and right, respectively, of FIG. 10.
Embodiments of the above-described lattice structure provide a cost-effective method for positioning and/or supporting ceramic cores used in pattern die assemblies and mold assemblies to form components having internal passages defined therein. The embodiments are especially, but not only, useful in forming components with internal passages having nonlinear and/or complex shapes, thus reducing or eliminating fragility problems associated with the core. Specifically, the lattice structure is selectively positionable at least partially within a pattern die used to form a pattern for the component. Subsequently or alternatively, the lattice structure is selectively positionable at least partially within a cavity of a mold, for example, a mold formed by investment of the pattern. The lattice structure is coupled to at least one joint segment of a hollow structure that defines a segmented core, such that the segmented core is positioned within the mold cavity by the lattice structure. The remainder of the hollow structure is formed from extension segments that extend from the joint segments. The segmented core also includes an inner core disposed within the hollow structure that defines a position of the internal passage within the component when the component is cast in the mold. The lattice structure is formed from a material that is at least partially absorbable by the molten component material introduced into the mold cavity to form the component, and does not interfere with the structural or performance characteristics of the component or with the later removal of the core from the component to form the internal passage. Thus, the use of the lattice structure eliminates a need to remove the core support structure and/or clean the mold cavity prior to casting the component.
In addition, separate formation of the joint segments and extension segments of the hollow structure enables a decreased cost of forming the segmented core and an improved performance of the internal passage defined by the segmented core. Specifically, in certain embodiments, the joint segments are formed integrally with at least a portion of the lattice structure to improve an ease and accuracy of coupling the hollow structure to the lattice structure, while the extension segments are formed in a lower cost fashion and then coupled to the joint segments. Also specifically, in some embodiments, the joint segments are formed by additive manufacturing, and the extension segments are formed in a fashion, such as from extruded tubing, that produces a relatively decreased surface roughness as compared to the joint segments, enabling formation of the internal passage with decreased surface roughness over a large portion of its length. Further, specifically, the ceramic core is disposed within the assembled hollow structure, such that the hollow structure provides structural reinforcement to the core, enabling the reliable handling and use of cores that are, for example, but without limitation, longer, heavier, thinner, and/or more complex than conventional cores for forming components having an internal passage defined therein.
An exemplary technical effect of the methods, systems, and apparatus described herein includes at least one of: (a) reducing or eliminating fragility problems associated with forming, handling, transport, and/or storage of the core used in forming a component having an internal passage defined therein; (b) enabling the use of longer, heavier, thinner, and/or more complex cores as compared to conventional cores for forming internal passages for components; (c) increasing a speed and accuracy of positioning the core with respect to other cores, a pattern die, and/or a mold used to form the component; (d) yielding acceptable surface roughness characteristics for the internal passage defined by the core, while still obtaining manufacturing complexity and accuracy benefits associated with additive manufacture; and (e) reducing or eliminating time and labor required to remove a positioning and/or support structure for the core from the mold cavity used to cast the component.
Exemplary embodiments of lattice structures and segmented cores for pattern die assemblies and mold assemblies are described above in detail. The lattice structures and segmented cores, and methods and systems using such lattice structures and segmented cores, are not limited to the specific embodiments described herein, but rather, components of systems and/or steps of the methods may be utilized independently and separately from other components and/or steps described herein. For example, the exemplary embodiments can be implemented and utilized in connection with many other applications that are currently configured to use cores within pattern die assemblies and mold assemblies.
Although specific features of various embodiments of the disclosure may be shown in some drawings and not in others, this is for convenience only. In accordance with the principles of the disclosure, any feature of a drawing may be referenced and/or claimed in combination with any feature of any other drawing.
This written description uses examples to disclose the embodiments, including the best mode, and also to enable any person skilled in the art to practice the embodiments, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

What is claimed is:

1. A mold assembly for use in forming a component having a first internal passage defined therein, the component formed from a component material, said mold assembly comprising:

a mold defining a mold cavity therein;

a lattice structure selectively positioned at least partially within said mold cavity, said lattice structure formed from a first material that is at least partially absorbable by the component material in a molten state; and

a first segmented core comprising at least one joint segment coupled to said lattice structure, said at least one joint segment of said first segmented core coupled in serial flow communication to at least one extension segment such that a first hollow structure is defined, wherein a first inner core is disposed within said first hollow structure such that at least a portion of said first inner core defines the first internal passage when the component is formed in said mold assembly.

2. The mold assembly of claim 1, wherein said mold comprises an interior wall that defines said mold cavity and said lattice structure defines a perimeter, said lattice structure is selectively positioned within said mold cavity by said perimeter coupled against said interior wall.

3. The mold assembly of claim 1, wherein the component has a second internal passage defined therein, said mold assembly further comprising a second segmented core comprising at least one joint segment coupled to said lattice structure, said at least one joint segment of said second segmented core coupled in serial flow communication to at least one extension segment of said second segmented core such that a second hollow structure is defined, wherein a second inner core is disposed within said second hollow structure such that at least a portion of said second inner core defines the second internal passage when the component is formed in said mold assembly.

4. The mold assembly of claim 1, wherein said lattice structure comprises a plurality of sectional elongated members, each said at least one joint segment is coupled to a corresponding group of said sectional elongated members.

5. The mold assembly of claim 4, wherein each said joint segment is formed integrally with said corresponding group of sectional elongated members by an additive manufacturing process.

6. The mold assembly of claim 1, wherein an inner wall of said at least one extension segment has a relatively low surface roughness as compared to an inner wall of said at least one joint segment.

7. The mold assembly of claim 1, wherein a longitudinal position of said at least one joint segment corresponds to a region of relatively high curvature of said hollow structure.

8. The mold assembly of claim 1, wherein a longitudinal position of said at least one joint segment corresponds to a region at which said first hollow structure defines a change in a cross-sectional flow area of the first internal passage.

9. The mold assembly of claim 1, wherein a longitudinal position of said at least one joint segment corresponds to a region at which structural support from said lattice structure facilitates stabilization of a position of said first segmented core.

10. The mold assembly of claim 1, wherein said at least one extension segment is formed from at least one extruded tube segment.

11. The mold assembly of claim 1, wherein said first material is at least partially absorbable by the component material in a molten state such that a performance of the component material in a solid state is not degraded.

12. The mold assembly of claim 9, wherein the component material is an alloy, and said first material comprises at least one constituent material of the alloy.

13. The mold assembly of claim 1, wherein said at least one joint segment and said at least one extension segment are coupled together by at least one of an externally flush joint, a diverging joint, and a converging joint.

14. A method of forming a component having a first internal passage defined therein, said method comprising:

selectively positioning a lattice structure at least partially within a cavity of a mold, wherein:

the lattice structure is formed from a first material,

at least one joint segment of a first segmented core is coupled to the lattice structure,

the at least one joint segment of the first segmented core is coupled in serial flow communication to at least one extension segment of the first segmented core such that a first hollow structure is defined, and

a first inner core is disposed within the first hollow structure;

introducing a component material in a molten state into the cavity, such that the component material in the molten state at least partially absorbs the first material from the lattice structure; and

cooling the component material in the cavity to form the component, wherein at least a portion of the first inner core defines the first internal passage within the component.

15. The method of claim 14, wherein the mold includes an interior wall that defines the cavity and the lattice structure defines a perimeter, said selectively positioning the lattice structure comprises coupling the perimeter of the lattice structure against the interior wall of the mold.

16. The method of claim 14, wherein at least one joint segment of a second segmented core is coupled to the lattice structure, the at least one joint segment of the second segmented core is coupled in serial flow communication to at least one extension segment of the second segmented core such that a second hollow structure is defined, and a second inner core is disposed within the second hollow structure, said cooling the component material in the cavity to form the component further comprises cooling the component material in the cavity wherein at least a portion of the second inner core defines a second internal passage within the component.

17. The method of claim 14, wherein said selectively positioning the lattice structure comprises selectively positioning the lattice structure that includes a plurality of sectional elongated members, each at least one joint segment is coupled to a corresponding group of the sectional elongated members.

18. The method of claim 17, wherein said selectively positioning the lattice structure comprises selectively positioning the lattice structure that includes each at least one joint segment formed integrally with the corresponding group of sectional elongated members by an additive manufacturing process.

19. The method of claim 14, wherein said selectively positioning the lattice structure comprises selectively positioning the lattice structure wherein an inner wall of the at least one extension segment has a relatively low surface roughness as compared to an inner wall of the at least one joint segment.

20. The method of claim 14, wherein said selectively positioning the lattice structure comprises selectively positioning the lattice structure wherein a longitudinal position of the at least one joint segment corresponds to a region of relatively high curvature of the first hollow structure.

21. The method of claim 14, wherein said selectively positioning the lattice structure comprises selectively positioning the lattice structure wherein a longitudinal position of the at least one joint segment corresponds to a region at which the first hollow structure defines a change in a cross-sectional flow area of the first internal passage.

22. The method of claim 14, wherein said selectively positioning the lattice structure comprises selectively positioning the lattice structure wherein a longitudinal position of the at least one joint segment corresponds to a region at which structural support from the lattice structure facilitates stabilization of a position of the first segmented core.

23. The method of claim 14, wherein said selectively positioning the lattice structure comprises selectively positioning the lattice structure wherein the at least one extension segment is formed from at least one extruded tube segment.

24. The method of claim 14, wherein said introducing the component material in the molten state into the cavity comprises introducing the component material such that a performance of the component material in a solid state is not degraded by the at least partial absorption of the first material.

25. The method of claim 24, wherein said introducing the component material in the molten state into the cavity comprises introducing an alloy in a molten state into the cavity, wherein the first material comprises at least one constituent material of the alloy.

26. The method of claim 14, wherein said selectively positioning the lattice structure comprises selectively positioning the lattice structure wherein the at least one joint segment and the at least one extension segment are coupled together by at least one of an externally flush joint, a diverging joint, and a converging joint.