Systems and methods for enhanced cooling during directional solidification of cast components

Abstract

A casting system for forming a directionally solidified cast component is provided. The casting system defines an axial direction, a radial direction, and a circumferential direction. The casting system includes a chamber and a baffle plate disposed within the chamber. The chamber and the baffle plate generally define a heating zone and a cooling zone. The heating zone and the cooling zone are separated by the baffle plate. The casting system further includes a shaft and a cooling plate disposed on the shaft. The cooling plate is movable between the heating zone and the cooling zone. A mold shell is disposed on the cooling plate. The casting system further includes a cooling system for directing a cooling fluid toward the mold shell.

Description

[Technical Field]

[0001] The present invention relates generally to materials and processes for producing directionally solidified castings, and more particularly to reducing defects in alloys cast as single-crystal (SX) and directionally solidified (DS) articles suitable for use as components in gas turbines and other high-temperature applications. [Background technology]

[0002] Gas turbine components, such as blades, vanes, and combustor components, are typically made from nickel, cobalt, or iron-base superalloys and are characterized by desirable mechanical properties at the turbine's operating temperatures. Because gas turbine efficiency depends on its operating temperature, components—particularly turbine buckets, nozzles, combustor components, and other hot-gas-path components—must be able to withstand higher temperatures. As the material requirements for gas turbine components increase, various processing methods and alloying elements have been used to improve the mechanical, physical, and environmental properties of components made from superalloys. For example, buckets, nozzles, and other components used in demanding applications are often cast using directional casting techniques to produce columnar polycrystalline or single-crystal articles with DS or SX microstructures characterized by selected directional crystal orientations or growth directions.

[0003] Casting techniques for producing SX and DS castings generally involve pouring a melt of the desired alloy into an investment mold maintained above the alloy's liquidus temperature. Solidification of the molten alloy within the mold occurs by gradually withdrawing the mold from a directional heating zone to a cooling zone, where cooling occurs by convection and / or radiation. Solidification begins at the bottom of the mold, and the solidification front progresses to the top of the mold. A high thermal gradient is required at the solidification front to prevent the nucleation of new grains during directional solidification processes.

[0004] During the directional solidification process of parts with complex geometries, grain defects can occur due to localized hot spots that do not cool at the same rate as the rest of the part. Therefore, improved systems and methods for cooling cast parts during the directional solidification process are desirable and appreciated in the art. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2014 / 0127032 Summary of the Invention

[0006] Aspects and advantages of the casting system and method according to the present disclosure will be set forth in part in the description that follows, or will be obvious from the description, or may be learned by practice of the art.

[0007] According to one embodiment, a casting system for forming a directionally solidified cast part is provided. The casting system defines an axial direction, a radial direction, and a circumferential direction. The casting system includes a chamber and a baffle plate disposed within the chamber. The chamber and the baffle plate collectively define a heating zone and a cooling zone. The heating zone and the cooling zone are separated by the baffle plate. The casting system further includes a shaft and a cooling plate disposed on the shaft. The cooling plate is movable between the heating zone and the cooling zone. A mold shell is disposed on the cooling plate. The casting system further includes a cooling system that directs a cooling fluid toward the mold shell.

[0008] According to another embodiment, there is provided a method of forming a directionally solidified cast part using a casting system. The casting system includes a chamber having a heating zone and a cooling zone separated by a baffle plate. The method includes pouring a liquid alloy into a mold shell. The mold shell is positioned on a cooling plate within the heating zone. The method moves the mold shell from the heating zone to the cooling zone, and the alloy changes from the liquid state to a solid state within the mold shell while moving the mold shell from the heating zone to the cooling zone. The method further includes directing a cooling fluid toward the mold shell using a cooling system.

[0009] These and other features, aspects, and advantages of the present casting system and method will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present technology and, together with the description, serve to explain the principles of the technology. [Brief explanation of the drawings]

[0010] A full and enabling disclosure of the present casting system and method, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the following specification, which makes reference to the accompanying drawings. [Figure 1]1 shows a schematic diagram of a turbomachine according to an embodiment of the present disclosure; [Figure 2] 1 illustrates a cross-sectional view of a casting system in a first position according to an embodiment of the present disclosure. [Figure 3] 3 illustrates a cross-sectional view of the casting system shown in FIG. 2 in a second position according to an embodiment of the present disclosure. [Figure 4] 4 shows a cross-sectional view of the casting system shown in FIG. 3 taken along line 4-4. [Figure 5] 1 illustrates a cross-sectional view of a casting system in a first position according to an embodiment of the present disclosure. [Figure 6] 6 illustrates a cross-sectional view of the casting system shown in FIG. 5 in a second position according to an embodiment of the present disclosure. [Figure 7] 7 shows a cross-sectional view of the casting system shown in FIG. 3 taken along line 7-7. [Figure 8] 1 illustrates a cross-sectional view of a casting system in a first position according to an embodiment of the present disclosure. [Figure 9] 9 illustrates a cross-sectional view of the casting system shown in FIG. 8 in a second position according to an embodiment of the present disclosure. [Figure 10] FIG. 1 illustrates a flow diagram of one embodiment of a method for forming a directionally solidified cast part using a casting system according to embodiments of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] Reference will now be made in detail to embodiments of the casting system and method of the present invention. One or more examples of these embodiments are illustrated in the drawings. Each example is provided for illustrative purposes, not limiting. Indeed, it will be apparent to those skilled in the art that modifications and variations can be made in the teachings of the present invention without departing from the scope or spirit of the claimed teachings. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Accordingly, the present disclosure is intended to cover such modifications and variations within the scope of the appended claims and their equivalents.

[0012] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, unless otherwise specified, all embodiments described herein are to be considered exemplary.

[0013] The detailed description uses numbers and letters to refer to features in the drawings. Like or similar designations in the drawings and description are used to refer to like or similar parts of the invention. In this specification, the terms "first," "second," and "third" may be used interchangeably to distinguish one component from another and are not intended to denote the location or importance of the individual components.

[0014] A "fluid" may be a gas or a liquid. "Fluid communication" means that a fluid can communicate between designated areas.

[0015] As used herein, the terms "upstream" (or "forward") and "downstream" (or "rearward") refer to relative directions with respect to fluid flow in a fluid pathway. For example, "upstream" refers to the direction in which a fluid flows, and "downstream" refers to the direction in which a fluid flows. However, as used herein, the terms "upstream" and "downstream" can also refer to the flow of electricity. The term "radial" refers to a relative direction that is substantially perpendicular to an axial centerline of a particular component, the term "axial" refers to a relative direction that is substantially parallel and / or coaxially aligned with an axial centerline of a particular component, and the term "circumferential" refers to a relative direction that extends around an axial centerline of a particular component.

[0016] Approximate terms such as "about," "approximately," "generally," and "substantially" are not limited to the exact value specified. In at least some instances, approximate terms may correspond to the precision of an instrument that measures a value, or the precision of a method or machine that constructs or manufactures a component and / or system. In at least some instances, approximate terms may correspond to the precision of an instrument that measures a value, or the precision of a method or machine that constructs or manufactures a component and / or system. For example, approximate terms may refer to within a margin of 1, 2, 4, 5, 10, 15, or 20 percent of an individual value, a range of values, and / or any of the endpoints that define a range of values. When used in the context of angles or directions, such terms include angles within 10 degrees of the specified angle or direction. For example, "generally vertical" includes directions within 10 degrees of vertical in any direction, such as clockwise or counterclockwise.

[0017] Terms such as "coupled," "fixed," and "attached" refer to both direct coupling, fixing, or attachment, as well as indirect coupling, fixing, or attachment via one or more intermediate components or features, unless otherwise specified herein. As used herein, the terms "comprise," "includes," "includes," "including," "has," "having," or other variations thereof are intended to cover a non-exclusive inclusion. For example, a process, method, article, or apparatus consisting of a list of features is not necessarily limited to only those features but may include other features not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, unless expressly stated to the contrary, "or" means an inclusive or, not an exclusive or. For example, condition A or condition B is satisfied by any one of the following: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), and both A and B are true (or present).

[0018] Throughout this specification and claims, range limitations are combinable and interchangeable, and such ranges are specified and include all subranges contained therein, unless the context or language dictates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0019] Referring now to the drawings, Figure 1 shows a schematic diagram of one embodiment of a turbomachine, which in the illustrated embodiment is a gas turbine 10. Although industrial or land-based gas turbines are shown and described herein, unless otherwise expressly stated in the claims, the present invention is not limited to land-based and / or industrial gas turbines. For example, the invention described herein may be used with any type of turbomachine, including, but not limited to, a steam turbine, an aircraft gas turbine, or a marine gas turbine.

[0020] As shown, the gas turbine 10 generally includes an inlet section 12, a compressor section 14 disposed downstream from the inlet section 12, multiple combustors (not shown) in a combustor section 16 disposed downstream from the compressor section 14, a turbine section 18 disposed downstream from the combustor section 16, and an exhaust section 20 disposed downstream from the turbine section 18. Additionally, the gas turbine 10 may include one or more shafts 22 coupled between the compressor section 14 and the turbine section 18.

[0021] Compressor section 14 generally includes a plurality of rotor disks 24 (one of which is shown) and a plurality of rotor blades 26 extending radially outward from and connected to each rotor disk 24. Each rotor disk 24 may be coupled to or form part of a shaft 22 that extends through compressor section 14.

[0022] Turbine section 18 may typically include a plurality of rotor disks 28 (one of which is shown) and a plurality of rotor blades 30 extending radially outward from and interconnected to each rotor disk 28. Each rotor disk 28 may be coupled to or form a part of a portion of a shaft 22 that extends through turbine section 18. Turbine section 18 further includes an outer casing 31 circumferentially surrounding the portion of shaft 22 and rotor blades 30, thereby at least partially defining a hot gas path 32 through turbine section 18.

[0023] During operation, a working fluid, such as air, flows through the inlet section 12 and into the compressor section 14, where it is progressively compressed, providing compressed air to the combustors in the combustion section 16. The compressed air is mixed with fuel and combusted in each combustor to generate combustion gases 34. The combustion gases 34 flow from the combustion section 16 through the hot gas path 32 and into the turbine section 18, where energy (kinetic and / or thermal energy) is transferred from the combustion gases 34 to the rotor blades 30, causing the shaft 22 to rotate. This mechanical rotational energy can then be used to power the compressor section 14 or generate electricity. The combustion gases 34 exit the turbine section 18 and leave the gas turbine 10 through the exhaust section 20.

[0024] 2 through 9, various views of a casting system 100 for forming a directionally solidified cast component are shown in accordance with an embodiment of the present disclosure. As described in more detail below, the directionally solidified cast component may be formed from a molten alloy solidifying within a mold shell 122. In an exemplary embodiment, the directionally solidified cast component may be a turbomachine component (e.g., a rotor blade, a stator vane, a fuel nozzle, etc.). For example, the directionally solidified cast component may be a rotor blade, in which case the cast component includes a shank and an airfoil extending from the shank. As such, the mold shell 122 may define a shank portion 102 and an airfoil portion 104 that correspond to the shapes of the shank and airfoil portions of a turbomachine rotor blade. The casting system 100 may define a cylindrical coordinate system having an axial direction A, a radial direction R extending generally perpendicular to the axial direction A, and a circumferential direction C extending around the axial direction A.

[0025] As shown, the casting system 100 includes a chamber 108 and a baffle plate 110 disposed within the chamber 108. In many embodiments, the chamber 108 may include a bottom 140, a top 142, and a sidewall 144 extending between the bottom 140 and the top 142. Further, the chamber 108 may define an axial centerline 150. For example, the chamber 108 may be a solid structure (i.e., as used herein, the term "chamber" refers to solid walls that define an interior volume) that defines an interior volume 112. The baffle plate 110 may separate the interior volume 112 into a heating zone 114 and a cooling zone 116. For example, the chamber 108 and the baffle plate 110 may collectively define the heating zone 114 and the cooling zone 116. The heating zone 114 and the cooling zone 116 may be separated by a baffle plate 110, with a first side of the baffle plate 110 defining the heating zone 114 and a second side of the baffle plate 110 defining the cooling zone 116. The bottom 140 may partially define the cooling zone 116, and the top 142 may partially define the heating zone 114.

[0026] The casting system 100 may further include a cooling plate 118 that is movable (e.g., axially movable) between the heating zone 114 and the cooling zone 116. For example, the cooling plate 118 may be coupled to a shaft 120, which may be actuable along an axial direction A (e.g., via one or more linear actuators 301, represented by a circled "A"). In various embodiments (not shown), the cooling plate 118 may be water-cooled. For example, the cooling plate 118 may have one or more water cooling circuits therein through which water circulates within the cooling plate 118. Furthermore, in many embodiments, the cooling plate 118 may be constructed of a material with high thermal conductivity, such as copper or a copper alloy.

[0027] The casting system 100 may further include a mold shell 122 disposed on the cooling plate 118 (e.g., disposed on an upper surface 119 of the cooling plate 118). For example, the mold shell 122 may extend axially from a base 125 disposed on the cooling plate 118 to a tip 126. The mold shell 122 may define a cavity 128 into which the liquid alloy 162 (i.e., the liquid alloy 164) is poured in the heating zone 114 (e.g., from the crucible 124). The mold shell 122 may then be moved (e.g., by actuating the shaft 120 to move the cooling plate 118 and the mold shell 122 along the axial centerline 150 from the heating zone 114 to the cooling zone 116). As the mold shell 122 moves into the cooling zone 116, the alloy solidifies within the mold shell 122 in an axial direction A (i.e., directionally solidifying) from the base 125 toward the tip 126 of the mold shell 122 to a solid state (i.e., solid state alloy 166), thereby forming a directionally solidified cast part. For example, as the mold shell 122 moves from the heating zone 114 and cooling zone 116, the alloy 162 may change from a liquid state to a solid state. As shown, horizontal dashed lines within the mold shell 122 may represent the alloy 162 in a liquid state (e.g., liquid state alloy 164), and cross-hatching within the mold shell 122 may represent the alloy 162 in a solid state (e.g., solid state alloy 166).

[0028] As the mold shell 122 moves from the heating zone 114 to the cooling zone 116, a solidification front 130 may form within the mold shell 122 between the liquid state of the alloy 162 and the solid state of the alloy 162. While the solidification front 130 is illustrated as a line, it should be understood that the solidification front 130 may be a range (e.g., an axial range) within the mold shell 122. More specifically, the solidification front 130 may be the portion of the alloy 162 that is within a solidification temperature range. The solidification temperature range may be a range of temperatures at which the alloy 162 may transition from a liquid state to a solid state. Furthermore, the alloy 162 at (and above) the solidification front 130 may be above the solidus temperature of the alloy 162. That is, the solidus temperature is the highest temperature at which the alloy 162 becomes completely solid, and the temperature of the solidification line (above it in the axial direction A) may be above the solidus temperature.

[0029] In many embodiments, the chamber 108 can be a vacuum chamber that is evacuated by a vacuum system 132. An electric heating element 134 can be disposed within the heating zone 114 to maintain the alloy 162 above the solidus temperature within the mold shell 122 (e.g., maintain the alloy 164 in a liquid state) while located within the heating zone 114. For example, the electric heating element 134 can surround the mold shell 122 when it is positioned within the heating zone 114. The baffle plate 110 can define an opening 111 through which the cooling plate 118, the shaft 120, and the mold shell 122 travel between the heating zone 114 and the cooling zone 116.

[0030] To produce a directionally solidified cast part, the mold shell 122 is inserted into the heating zone 114 by moving the shaft 120 axially upward. The crucible 124 pours the liquid alloy 164 into the mold shell 122, and then the shaft is moved axially downward, causing the mold shell 122 to pass through the opening 111 from the heating zone 114 to the cooling zone 116. As a result, the alloy 162 changes from a liquid state to a solid state in the axial direction from the base 125 to the tip 126. For example, the alloy 162 first solidifies at the base 125 of the mold shell 122, and the solidification front moves axially upward toward the tip 126 of the mold shell 122.

[0031] Due to the geometric complexity of directionally solidified cast parts, various portions of the alloy 162 within the mold shell 122 may not solidify at the same rate (e.g., some solidify slower than others), potentially resulting in one or more part defects. Therefore, the example casting system 100 described herein includes a cooling system 200 for directing a coolant fluid 201 into the mold shell 122 (e.g., within the cooling zone 116), thereby increasing the solidification rate of the alloy and preventing the formation of defects.

[0032] The cooling system 200 may include a coolant fluid supply 202 and a coolant fluid supply line 204. The coolant fluid supply 202 may be a container, tank, or other coolant fluid reservoir. The coolant fluid supply line 204 may transport the coolant fluid 201 from the coolant fluid supply 202 to the cooling zone 116 and direct it toward the mold shell 122. In an exemplary implementation, the coolant fluid 201 may be a fluid that does not react with the alloy 162. For example, in an exemplary embodiment, the coolant fluid 201 may be an inert or noble gas, such as helium or argon. The coolant fluid 201 introduced into a chamber (e.g., the cooling zone of the chamber 108) may then be evacuated by the vacuum system 132. For example, the vacuum system 132 may continuously remove (or evacuate) the coolant fluid 201 introduced into the cooling zone 116 to maintain a vacuum within the chamber 108.

[0033] In many embodiments, as shown in FIGS. 2 through 7, the cooling system 200 may include multiple ejection devices 206 axially spaced apart from one another. The multiple ejection devices 206 may be disposed in the cooling zone 116 (e.g., axially between the baffle plate 110 and the bottom 140). Each ejection device 206 may be in fluid communication with a cooling fluid supply 202 via a cooling fluid supply line 204 (i.e., the cooling fluid supply line 204 may fluidly couple each ejection device 206 to the cooling fluid supply 202). The multiple ejection devices 206 may eject (or inject) cooling fluid 201 toward the mold shell 122. For example, in some embodiments, as shown in FIGS. 2 through 4, the ejection device 206 may include multiple nozzles 208, each extending radially to an outlet 210. Alternatively, or additionally, as shown in FIGS. 5-7 , each ejector 206 may include a ring 212 surrounding the mold shell 122 and defining a plurality of outlets 214. In both embodiments, the ejector 206 may define outlets sized and oriented to impinge discrete jets of cooling fluid 201 on the mold shell 122 (e.g., the outer surface 123 of the mold shell). The individual jets of cooling fluid 201 impinge on (or strike) the outer surface 123 of the mold shell 122, thereby enabling heat transfer from the alloy 162 to the cooling fluid 201. As the individual jets of cooling fluid 201 impinge on the mold shell 122, the cooling fluid 201 undergoes energy transfer and has different properties (e.g., higher temperature and lower pressure than before impingement), and may therefore be referred to as “post-impingement fluid” and / or “spent cooling fluid.” Spent cooling fluid may be evacuated from the cooling zone 116 via a vacuum system 132 .

[0034] 2-4, various views of a casting system 100 according to an embodiment of the present disclosure are shown. For example, FIG. 2 shows a cross-sectional view of casting system 100 in a first position (e.g., a heating position), FIG. 3 shows a view of casting system 100 in a second position (e.g., during the withdrawing stage), and FIG. 4 shows a cross-sectional view of casting system 100 along line 4-4 shown in FIG. 3.

[0035] 2-4 , cooling system 200 may include a cooling fluid supply 202, a plurality of axially spaced ejectors 206, and a cooling fluid supply line 204 extending between cooling fluid supply 202 and the plurality of ejectors 206. Each ejector 206 may include a plurality of nozzles 208 extending toward mold shell 122. For example, each nozzle 208 of the plurality of nozzles 208 may extend generally radially from cooling fluid supply line 204 through chamber 108 to an outlet 210 within cooling zone 116.

[0036] 2 and 3 , each nozzle 208 of the plurality of nozzles 208 is movable in a radial direction R to adjust a radial gap 218 between an outlet 210 of the nozzle 208 and the outer surface 123 of the mold shell 122. For example, each nozzle 208 may be formed at least in part from a flexible conduit or hose such that the nozzle 208 may extend and / or retract in a radial direction. For example, in many embodiments, each nozzle 208 of the plurality of nozzles 208 may include an actuator 301 in operative communication with a controller 300. The actuator 301 is operable to adjust the radial position of the nozzle 208; for example, the actuator may extend and / or retract the nozzle 208 such that the radial position of the outlet 210 is changed. The outlet 210 of each nozzle 208 is movable in a radial direction R between the sidewall 144 of the chamber 108 and the axial centerline 150 of the chamber 108. As will be appreciated, the radial gap 218 can affect the effectiveness of impingement cooling because the shorter the distance the cooling fluid 201 travels, the higher the velocity of the cooling fluid 201, thereby removing more heat from the mold shell 122. Therefore, in an exemplary embodiment, each nozzle 208 can be selectively actuated to vary the radial gap 218 based on the cooling needs. For example, if more cooling is needed at a particular axial location of the mold shell 122, the nozzle 208 at that axial location can be actuated to shorten the radial gap 218, thereby increasing the velocity of the cooling fluid 201 impinging on the surface of the mold shell 122 and thereby increasing the effectiveness of the impingement cooling.

[0037] Further, in many embodiments, each nozzle of the plurality of nozzles may include a valve 305 in operable communication with the controller 300. Each valve 305 may be fluidly coupled to a respective nozzle 208 of the plurality of nozzles 208. The valves 305 may be operable between an open position and a closed position. In the open position, cooling fluid is permitted to pass through the valve 305, and in the closed position, cooling fluid is blocked or restricted from passing through the valve 305. Thus, in many embodiments, the controller 300 may selectively open and close one or more valves 305 based on the cooling needs of the alloy 162 within the mold shell 122. For example, while the mold shell 122 is moving from the heating zone 114 to the cooling zone 116, the one or more valves 305 may be in a closed position until at least a portion of the mold shell 122 moves into the axial circumferential plane of the nozzle 208 to which the one or more valves 305 are fluidly coupled. At this point, one or more valves 305 may be switched (or actuated) from a closed position to an open position when the mold shell 122 is moved into the axial circumferential plane of the nozzle 208 to which the one or more valves 305 are fluidly coupled.

[0038] 4, the cooling fluid supply line 204 may further include a ring portion 205 that surrounds the chamber 108. For example, each nozzle 208 of the plurality of nozzles 208 extends generally radially from the ring portion 205 to a respective outlet 210. Further, as shown in FIG. 4, the plurality of nozzles 208 may be circumferentially spaced apart from one another (e.g., equally circumferentially spaced apart).

[0039] The multiple ejection devices 206 may be axially spaced apart from one another. For example, the cooling system 200 may include an initial ejection device 220 adjacent to (or near) the baffle plate 110, a final ejection device 224 adjacent to (or near) the bottom 140, and multiple intermediate ejection devices 222 disposed between the initial ejection device 220 and the final ejection device 224. In the embodiment shown in Figures 2 and 3, the multiple ejection devices 206 may be configured as multiple radially movable nozzles 208 extending through the chamber 108.

[0040] 5-7, each of the plurality of ejectors 206 may be configured as a ring 212 axially movably disposed within the cooling zone 116. In operation, as the mold shell 122 is moved axially from the heating zone 114 to the cooling zone 116, the mold shell 122 moves axially through the opening 111, the initial ejector 220, the plurality of intermediate ejectors 222, and the final ejector 224, in that order, until the cooling plate 118 reaches the bottom 140.

[0041] The ring 212 of each ejector 206 may be movable in the axial direction A within the cooling zone 116 between the baffle plate 110 and the bottom 140. For example, FIG. 5 illustrates the casting system 100 in a first position, e.g., before the mold shell 122 is moved into the cooling zone. FIG. 6 illustrates the casting system 100 in a second position, e.g., while the mold shell 122 is being moved into the cooling zone 116. For example, the shaft 120 may move the mold shell 122 through the opening 111 and into the cooling zone 116 such that the rings 212 surround the mold shell 122 within the cooling zone 116. The rings 212 may be movable from a first position ( FIG. 5 ) in which the rings 212 are spaced a first axial distance 228 apart and proximate the baffle plate 110 to a second position ( FIG. 6 ) in which the rings 212 are spaced a second axial distance 230 apart. The second axial distance 230 may be greater than the first axial distance 228. Additionally, in the first position ( FIG. 5 ), all of the rings 212 may be positioned closer to the baffle plate 110 than to the bottom 140, which advantageously provides a greater cooling effect to the mold shell 122 immediately upon entering the cooling zone 116 through the opening 111. As the base 125 of the mold shell 122 retracts (or moves) axially beyond the last ring 212 (i.e., the lowest ring 212), the ring 212 begins to move axially with the mold shell 122 until the mold shell 122 is fully positioned within the cooling zone 116.

[0042] Each ring 212 may be in fluid communication with the cooling fluid supply line 204 via a branch 240. For example, each branch 240 may extend between the cooling fluid supply line 204 and the ring 212. A valve 305 may be fluidly coupled to each branch 240. In various embodiments, each ring 212 may be coupled to an actuator 303 that can change the axial position of the ring 212. For example, the actuator 303 may be disposed on each branch 240 (e.g., at the junction of the branch 240 and the cooling fluid supply line 204). In many embodiments, each actuator 303 may be in operable communication with the controller 300. For example, each actuator may be operable to adjust the axial position of the ring 212, e.g., the actuator extends and / or retracts to adjust the axial position of each ring 212 within the cooling zone 116. Each ring 212 is axially movable between the baffle plate 110 and the bottom 140.

[0043] As shown in FIG. 7 , each ring 212 surrounds the mold shell 122 and may define a plurality of outlets 214. The outlets 214 may be defined in an inner portion of the ring 212 and may be circumferentially spaced apart from one another. In some embodiments, the rings 212 may be circularly shaped, as shown. In other embodiments, the rings 212 may have other shapes, such as an oval. Notably, in many embodiments, each ring 212 may correspond in cross-sectional shape to the mold shell 122, and the rings 212 may define a uniform radial gap between the outlets 214 and the portion of the mold shell 122 that is cooled by the cooling fluid 201. Furthermore, the outlets 214 may be oriented toward the mold shell 122.

[0044] In many embodiments, the ring 212 of each ejector 206 may define a diameter 250, and the diameter 250 of each ring 212 may be different (particularly, the inner diameter of each ring 212 may be different). For example, the ring 212 of a first ejector 206 of the plurality of ejectors 206 may define a first diameter, and the ring 212 of a second ejector 206 of the plurality of ejectors 206 may define a second diameter. The first and second diameters may be different. Particularly, as shown in FIGS. 5 and 6 , the diameters of the rings 212 of each ejector 206 may be different. For example, the diameter of the ring of the initial ejector 220, the diameter of the ring of each intermediate ejector 222, and the diameter of the ring of the final ejector 224 may be different, which advantageously maintains a desired radial gap between the mold shell 122 and the outlet 214 of the ring 212.

[0045] 8 and 9, a casting system 100 is illustrated in accordance with another embodiment of the present disclosure. For example, FIG. 8 illustrates a cross-sectional view of the casting system 100 in a first position, and FIG. 9 illustrates a cross-sectional view of the casting system shown in FIG. 8 in a second position, in accordance with an embodiment of the present disclosure.

[0046] As shown in FIGS. 8 and 9 , the mold shell 122 may define a cooling circuit 252. For example, the cooling circuit 252 may be defined between the outer surface 123 and the inner surface 121 of the mold shell 122. The cooling circuit 252 may be in fluid communication with the cooling system 200. For example, the cooling system 200 may include passages 254 defined in the shaft 120 and the cooling plate 118. For example, the passages 254 may extend from an inlet disposed in the shaft 120 to an outlet disposed in the upper surface 119 of the cooling plate 118. The cooling fluid supply line 204 may be in fluid communication with the inlet of the passages 254 (e.g., the cooling fluid supply line 204 may extend between the cooling fluid supply 202 and the inlet of the passages 254). The passages 254 may be in fluid communication with the cooling circuit 252 of the mold shell 122. For example, the base 125 of the mold shell 122 may define an inlet to a cooling circuit 252 that is fluidly coupled to the outlet of the passage 254 .

[0047] As shown in FIGS. 2-9, the casting system 100 may further include a controller 300, which is illustrated as a block diagram illustrating suitable components that may be included within the controller 300. As illustrated, the controller 300 may include one or more processors 302 and associated memory devices 304 configured to perform various computer-implemented functions (e.g., executing methods, steps, calculations, etc., as disclosed herein and storing associated data). Additionally, the controller 300 may also include a communications module 306 to facilitate communication between the controller 300 and various components of the casting system 100 (e.g., the crucible 124, the shaft 120, the vacuum system 132, the electric heating element 134, the actuator(s) 301, 303, and / or the valves 305). For example, the communications module 306 may communicate with the actuators 301, 303 to enable the processor 302 to selectively move the plurality of nozzles 208 ( FIGS. 2-4 ) or the ring 212 ( FIGS. 5-7 ). It should be understood that the crucible 124, shaft 120, vacuum system 132, electric heating element 134, actuator(s) 301, 303, and valve 305 may be communicatively coupled to the communications module 306 using any suitable means (e.g., a wired connection or a wireless connection using any suitable wireless communications protocol known in the art).

[0048] As used herein, the term "processor" refers not only to integrated circuits referred to in the art as being included in computers, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits, and other programmable circuits. Furthermore, the memory device(s) 304 are generally limited to computer-readable media (e.g., random access memory (RAM)), computer-readable non-volatile media (e.g., flash memory), floppy disks, compact disks-read only memory (CD-ROM), magneto-optical disks (MODs), digital versatile disks (DVDs), and / or other suitable memory elements. Such memory device 304 may be configured to store appropriate computer-readable instructions that configure system 100 to perform various functions and / or operations, including, but not limited to, using crucible 124 to pour alloy 162 in a liquid state into mold shell 122, using shaft 120 to move mold shell 122 from heating zone 114 to cooling zone 116, and directing cooling fluid 201 toward mold shell 122 via cooling system 200, which are generally executed by processor 302.

[0049] Referring to FIG. 10 , a flow diagram of one embodiment of a method 1000 for forming a directionally solidified cast component using the casting system 100 is shown in accordance with an aspect of the present subject matter. Generally, the method 1000 is described herein with reference to the casting system 100 and gas turbine 10 described above with reference to FIGS. 1 through 9 . However, those skilled in the art will understand that the disclosed method 1000 may be generally utilized in connection with any casting system having other suitable system configurations. Furthermore, while FIG. 10 depicts steps performed in a particular order for purposes of illustration and discussion, the methods described herein are not limited to any particular order or arrangement unless otherwise specified in the claims. Those skilled in the art using the disclosure provided herein will understand that various steps of the methods disclosed herein may be omitted, rearranged, combined, and / or adapted.

[0050] 10 , the method 1000 may include pouring (step 1002) the alloy 162 in a liquid state into the mold shell 122. The mold shell 122 may be positioned on a cooling plate 118 within the heating zone 114. Prior to pouring (1002), the alloy 162 may be heated to a molten or liquid state in a crucible 124, and once the alloy 162 is in a liquid state, the alloy 162 may be poured into the mold shell 122 by the crucible 124. For example, the alloy 162 may be poured through an opening in the tip 126 of the mold shell 122 into a cavity 128 defined by the mold shell 122, such that the alloy 162 fills the cavity 128 defined by the mold shell 122. The cavity 128 may correspond in shape to a directionally solidified cast part, such that the cavity 128 may have a rotor blade shape having a shank portion 102 and an airfoil portion 104 .

[0051] In many embodiments, before or after the pouring step, the method 1000 may further include evacuating the chamber 108 with a vacuum system 132. The vacuum system 132 may remove all air from the chamber 108, thereby creating a vacuum. Additionally, in some embodiments, when the mold shell 122 is within the heating zone 114 (e.g., during and / or after the pouring step), an electric heating element 134 may heat the alloy 162 within the mold shell 122 to maintain or maintain the alloy 162 in a liquid state.

[0052] In various embodiments, the method 1000 may further include (step 1004) moving the mold shell 122 from the heating zone 114 to the cooling zone 116. As a result, the alloy 162 changes from a liquid state to a solid state within the mold shell 122 while moving the mold shell 122 from the heating zone 114 to the cooling zone 116. The moving (step 1004) may include actuating the shaft 120 (e.g., sending a signal via the controller 300) to move the shaft 120 in the axial direction A, thereby moving the mold shell 122 from the heating zone 114 to the cooling zone 116 through the opening 111 in the baffle plate 110.

[0053] In an exemplary embodiment, the method 1000 may further include (step 1006) directing the cooling fluid 201 toward the mold shell 122 with the cooling system 100. For example, the instructions in (step 1006) may include ejecting (or injecting) the cooling fluid 201 as individual jets from an ejector 206 located within the cooling zone 116 toward the outer surface 123 of the mold shell 122. Additionally or alternatively, the instructions in (step 1006) may be performed during the moving step 1004. For example, the cooling fluid 201 may be jetted toward the mold shell 122 while the mold shell 122 is being moved axially from the heating zone 114 to the cooling zone 116. In many embodiments, the cooling system 100 may include multiple ejectors 206 that are axially spaced apart from one another and movable (e.g., movable in the axial direction A and / or the radial direction R) within the cooling zone 116.

[0054] 10 , the method 1000 may include (step 1008) adjusting the position of the plurality of ejectors 206 within the cooling zone 116. For example, the plurality of ejectors 206 may be moved axially and / or radially within the cooling zone 116 while the mold shell 122 is being moved from the heating zone 114 to the cooling zone 116.

[0055] In various embodiments, adjusting (step 1008) may further include adjusting (step 1010) the positions of the plurality of ejectors 206 to maintain a constant radial gap between each of the plurality of ejectors 206 and the outer surface 123 of the mold shell 122 while the mold shell 122 is moved axially from the heating zone 114 to the cooling zone 116. For example, while the mold shell 122 is moved axially, each ejector 206 may move axially and / or radially to maintain a constant radial gap. In various embodiments, the constant radial gap may be between an outlet of the ejector 206 (e.g., outlet 210 in FIGS. 2-4 or outlet 214 in FIG. 7 ) and the outer surface 123 of the mold shell 122. The ejector 206 may be moved axially at the same speed as the mold shell 122 , at a faster speed than the mold shell 122 , or at a slower speed than the mold shell 122 as the mold shell 122 is withdrawn from the heating zone 114 .

[0056] As described above, in many embodiments, the multiple ejectors may include multiple nozzles 208 extending radially toward the mold shell 122. In such embodiments, the method may further include radially moving at least one nozzle 208 of the multiple nozzles 208 to vary a radial gap 218 between an outlet 210 of the at least one nozzle 208 and the outer surface 123 of the mold shell 122. The outlet 210 of each nozzle 210 may be moved radially within an envelope corresponding to the outline of the mold shell 122 while the mold shell 122 is retracted, such that a constant radial gap between the outlet 210 and the outer surface 123 of the mold shell 122 is maintained.

[0057] In other embodiments, each ejector 206 of the plurality of ejectors 206 may include a ring 212 surrounding the mold shell 122 and defining a plurality of outlets 214. In such embodiments, the method may further include axially moving the ring 212 of at least one ejector 206 of the plurality of ejectors 206 within the cooling zone 116. The rings 212 may move from a first position ( FIG. 5 ) in which the rings 212 are spaced a first axial distance 228 apart and proximate the baffle plate 110 to a second position ( FIG. 6 ) in which the rings 212 are spaced a second axial distance 230 apart. The second axial distance 230 may be greater than the first axial distance 228. Furthermore, in the first position ( FIG. 5 ), all of the rings 212 may be positioned closer to the baffle plate 110 than to the bottom 140, which advantageously provides a greater cooling effect to the mold shell 122 immediately upon entering the cooling zone 116 through the openings 111. Once the base 125 of the mold shell 122 recedes (or moves) axially beyond the final ring 212 (i.e., the bottom-most ring 212), the ring 212 can begin to move axially with the mold shell 122 until the mold shell 122 is fully positioned within the cooling zone 116.

[0058] In many embodiments, the mold shell 122 may define a cooling circuit 252 (e.g., between an outer surface and an inner surface of the mold shell 122). In such embodiments, the method 1000 may further include directing the cooling fluid 201 to the cooling circuit 252 defined in the mold shell 122 through a passage 254 defined in the cooling plate 118 and a shaft 120 attached to the cooling plate 118.

[0059] This specification uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing methods incorporating the same. The patentable scope of the invention 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 contain structural elements that do not differ from the literal language of the claims, or if they contain equivalent structural elements that do not differ substantially from the literal language of the claims.

[0060] Further aspects of the invention are provided by the subject matter of the following clauses. [Embodiment 1] A casting system for forming a directionally solidified casting component, the casting system defining an axial direction, a radial direction, and a circumferential direction, the casting system including a chamber, a baffle plate disposed within the chamber, the chamber and the baffle plate collectively defining a heating zone and a cooling zone, the heating zone and the cooling zone separated by the baffle plate, a shaft, a cooling plate disposed on the shaft and movable between the heating zone and the cooling zone, and a mold shell disposed on the cooling plate. a cooling system for directing a coolant fluid towards the mold shell. [Embodiment 2] 10. The casting system of any of the previous embodiments, wherein the cooling system comprises a plurality of ejection devices axially spaced apart from one another. [Embodiment 3] 10. The casting system of any preceding embodiment, wherein each ejection device of the plurality of ejection devices comprises a plurality of nozzles extending towards the mold shell. [Embodiment 4]

[0023] The casting system of any preceding embodiment, wherein each nozzle of the plurality of nozzles is movable in the radial direction to adjust a radial gap between an outlet of the nozzle and an exterior surface of the mold shell. [Embodiment 5] 10. The casting system of any preceding embodiment, wherein each nozzle of the plurality of nozzles includes an actuator and a valve in operable communication with a controller. [Embodiment 6] 10. The casting system of any preceding embodiment, wherein each ejection device of the plurality of ejection devices comprises a ring that surrounds the mold shell and defines a plurality of outlets. [Embodiment 7] 10. The casting system of any of the preceding embodiments, wherein the ring of each ejection device is movable in the axial direction within the cooling zone. [Embodiment 8] 10. The casting system of claim 9, wherein the ring of a first ejection device of the plurality of ejection devices defines a first diameter, the ring of a second ejection device of the plurality of ejection devices defines a second diameter, and the first diameter and the second diameter are different. [Embodiment 9] 10. The casting system of any preceding embodiment, wherein the mold shell defines a cooling circuit, the cooling circuit in fluid communication with the cooling system. [Embodiment 10] 10. The casting system of any preceding embodiment, wherein the cooling system includes a passage defined in the shaft and the cooling plate, the passage being fluidly coupled to the cooling circuit of the mold shell. [Embodiment 11] 10. The casting system of any preceding embodiment, wherein the cooling system further comprises a coolant supply and a coolant fluid supply line. [Embodiment 12] A method of forming a directionally solidified casting component using a casting system, the casting system comprising a chamber having a heating zone and a cooling zone separated by a baffle plate, the method comprising the steps of pouring an alloy in a liquid state into a mold shell positioned on a cooling plate within the heating zone, and moving the mold shell from the heating zone to the cooling zone, whereby the alloy transfers from the liquid state to a solid state within the mold shell while moving the mold shell from the heating zone to the cooling zone. and directing a coolant fluid towards the mold shell with a cooling system. [Embodiment 13] 10. The method of any preceding embodiment, wherein the casting system defines an axial direction, a radial direction, and a circumferential direction, the cooling system further comprises a plurality of ejection devices axially spaced apart from one another, and the method further comprises adjusting a position of the plurality of ejection devices within the cooling zone. [Embodiment 14] The method of any preceding embodiment, wherein adjusting the position of the ejection devices further comprises: maintaining a constant radial gap between each ejection device of the plurality of ejection devices and an exterior surface of the mold shell while moving the mold shell axially from the heating zone to the cooling zone by adjusting the position of the plurality of ejection devices. [Embodiment 15] The method of any preceding embodiment, wherein the plurality of ejection devices comprises a plurality of nozzles extending radially towards the mold shell, and adjusting the position of the ejection devices further comprises radially moving at least one nozzle of the plurality of nozzles to modify a radial gap between an outlet of the at least one nozzle and an exterior surface of the mold shell. [Embodiment 16] The method of any preceding embodiment, wherein each ejection device of the plurality of ejection devices comprises a ring that surrounds the mold shell and defines a plurality of outlets, and adjusting the position of the cooling system further comprises axially moving the ring of at least one ejection device of the plurality of ejection devices within the cooling zone. [Embodiment 17] 10. The method of any preceding embodiment, wherein a ring of a first ejection device of the plurality of ejection devices defines a first diameter, and a ring of a second ejection device of the plurality of ejection devices defines a second diameter, and wherein the first diameter and the second diameter are different. [Embodiment 18] The method of any preceding embodiment, wherein the mold shell defines a cooling circuit, and the method further comprises directing the coolant fluid through a passage defined in the cooling plate and a shaft attached to the cooling plate to the cooling circuit defined in the mold shell. [Explanation of symbols]

[0061] 10: Gas turbine 12: Inlet section 14: Compressor section 16: Combustor section 18: Turbine section 20: Exhaust section 22: Shaft 24: Rotor disk 26: Rotor blades 28: Rotor disk 30: Rotor blades 31: Outer casing 32: Hot gas path 34: Combustion gases 100: Casting system 102: Shank section 104: Airfoil section 108: Chamber 110: Baffle plate 111: Opening 112: Internal volume 114: Heating zone 116: Cooling zone 118: Cooling plate 119: Top surface 120: Shaft 122: Mold shell / shell mold 123: Outer surface 124: Crucible 125: Base 126: Tip 128: Cavity 130: Solidification front 132: Vacuum system 134: Electric heating element 140: Bottom portion 142: Top portion 144: Side wall 150: Axial center line 162: Alloy 164: Alloy in liquid state 166: Alloy in solid state 200: Cooling system 201: Cooling fluid 202: Cooling fluid supply portion 204: Cooling fluid supply line 205: Ring portion 206: Discharge device 208: Nozzle 210, 214: Outlet 212: Ring 218: Radial gap 220: Initial discharge device 222: Intermediate discharge device 224: Final discharge device 228: First axial distance 230: Second axial distance 240: Branch 250: Diameter 252: Cooling circuit 254: Passage 300: Controller 301: Actuator / Linear actuator 302: Processor 303: Actuator 304: Memory device 305: Valve 306: Communication module A: Axial direction C: Circumferential direction / Circumferential direction R: Radial direction

Claims

1. 1. A casting system for forming a directionally solidified cast component, the casting system defining an axial direction, a radial direction, and a circumferential direction; a chamber; a baffle plate disposed within the chamber, the chamber and the baffle plate collectively defining a heating zone and a cooling zone, the heating zone and the cooling zone being separated by the baffle plate; A shaft, a cooling plate disposed on the shaft and movable between a heating zone and a cooling zone; a mold shell disposed on a cooling plate; a cooling system for directing a cooling fluid toward the mold shell; , a casting system.

2. The casting system of claim 1 , wherein the cooling system includes a plurality of axially spaced ejectors.

3. The casting system of claim 2 , wherein each of the plurality of ejectors includes a plurality of nozzles extending toward the mold shell.

4. The casting system of claim 3 , wherein each nozzle of the plurality of nozzles is radially movable to adjust a radial gap between an outlet of the nozzle and an outer surface of the mold shell.

5. The casting system of claim 3 , wherein each nozzle of the plurality of nozzles includes an actuator and a valve in operable communication with the controller.

6. The casting system of claim 2 , wherein each of the plurality of ejectors includes a ring surrounding the mold shell and defining a plurality of outlets.

7. The casting system of claim 6 , wherein the ring of each ejector is axially movable within the cooling zone.

8. 7. The casting system of claim 6, wherein a ring of a first ejector of the plurality of ejectors defines a first diameter and a ring of a second ejector of the plurality of ejectors defines a second diameter, the first diameter and the second diameter being different.

9. The casting system of claim 1 , wherein the mold shell defines a cooling circuit, the cooling circuit being in fluid communication with the cooling system.

10. The casting system of claim 9 , wherein the cooling system includes passages defined in the shaft and the cooling plate, the passages being in fluid communication with a cooling circuit of the mold shell.

11. The casting system of claim 1 , wherein the cooling system further comprises a coolant supply and a coolant fluid supply line.

12. 1. A method of forming a directionally solidified cast component using a casting system, the casting system including a chamber having a heating zone and a cooling zone separated by a baffle plate, the method comprising: pouring the alloy in a liquid state into a mold shell positioned on a cooling plate within a heating zone; moving the mold shell from the heating zone to the cooling zone, whereby the alloy changes from a liquid state to a solid state within the mold shell as the mold shell moves from the heating zone to the cooling zone; directing a cooling fluid toward the mold shell using a cooling system; A method comprising:

13. the casting system defines an axial direction, a radial direction, and a circumferential direction, the cooling system further including a plurality of ejectors spaced apart from one another in the axial direction; The method of claim 12 , further comprising adjusting the positions of the plurality of ejectors within the cooling zone.

14. Adjusting the position of the ejector may further include:

14. The method of claim 13, including adjusting the positions of the plurality of ejectors to maintain a constant radial gap between each ejector of the plurality of ejectors and the outer surface of the mold shell while moving the mold shell axially from the heating zone to the cooling zone.

15. The plurality of ejectors includes a plurality of nozzles extending radially toward the mold shell, and adjusting the arrangement of the ejectors is further 14. The method of claim 13, including the step of radially moving at least one nozzle of the plurality of nozzles to vary a radial gap between an outlet of the at least one nozzle and an outer surface of the mold shell.

16. Each ejector of the plurality of ejectors includes a ring surrounding the mold shell and defining a plurality of outlets, and adjusting the position of the cooling system further includes: The method of claim 13, including the step of axially moving a ring of at least one ejector of the plurality of ejectors within the cooling zone.

17. 17. The method of claim 16, wherein a ring of a first ejector of the plurality of ejectors defines a first diameter and a ring of a second ejector of the plurality of ejectors defines a second diameter, the first diameter and the second diameter being different.

18. The mold shell defines a cooling circuit, and the method further comprises: The method of claim 12 including directing cooling fluid to a cooling circuit defined in the mold shell through passages defined in a cooling plate and a shaft attached to the cooling plate.

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