Method for integrated fixturing of direct print mold for cast component

Abstract

To provide a method for integrated fixturing of a direct print mold for a cast component.SOLUTION: The present application provides a method of optimizing strength in an improved mold (100) for a cast component (55). The method may include the steps of evaluating a flaw (90) in an existing mold (88), adding external reinforcement features (120) to a design of the improved mold (100), manufacturing the improved mold (100) in an additive manufacturing process, and casting the cast component (55) in the improved mold (100).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This application and the resulting patent relate generally to cast components, such as cast parts, cast components, cast gas parts, and more particularly to an improved method and system for integrated fixturing of strengthened direct print molds to produce castings of components in a highly efficient and accurate manner. [Background technology]

[0002] A gas turbine engine traditionally includes a compressor that compresses ambient air and multiple combustors that mix a flow of air with a flow of fuel to generate hot combustion gases. A turbine receives the flow of hot combustion gases and extracts energy therefrom to power the compressor and to generate output power for an external load, such as an electrical generator. Hot gas path components of gas turbine engines, such as turbine airfoils, have traditionally been manufactured using an investment casting process. In such a process, a molten metal alloy is introduced into a mold cavity defined between a shell and a core and allowed to solidify to form a finished casting. In some applications, turbine components must withstand thermal stresses due to high temperatures, centrifugal forces, and large temperature fluctuations. As such, turbine components may include internal cooling passages and other complex geometries.

[0003] Traditional mold techniques for producing turbine components can be time-consuming and have limited mold and / or core resolution. Additionally, the shell that forms after slurry immersion can limit heat transfer. In contrast, additive manufacturing techniques and 3D printing can produce first molds in a fast and efficient manner. However, the production of highly complex shapes and / or the rigors of multiple process steps between printing and casting can develop stress features that result in cracking or deformation of the additively manufactured mold. Previous attempts to strengthen such molds have focused on developing mold compositions and firing processes to slow down burnout schedules. Similarly, other attempts have used designs with internal recesses with different types of inserts. However, the use of such inserts adds time and cost to the manufacturing process. Summary of the Invention

[0004] The present application and resulting patent provide a method for optimizing strength in an improved mold for a cast part, the method including the steps of evaluating defects in an existing mold, adding external reinforcement features to a design of the improved mold, producing the improved mold with an additive manufacturing process, and casting the cast part with the improved mold.

[0005] The present application and the resulting patent may further provide a mold for a cast part. The mold may include a part body of a ceramic material produced from an additive manufacturing process and one or more external reinforcing features fabricated in the part body.

[0006] These and other features and improvements of the present application and the resulting patent will become apparent to those of ordinary skill in the art upon review of the following detailed description, when considered in conjunction with the several drawing figures and the appended claims. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a gas turbine engine including a compressor, a combustor, a turbine, and an external load. [Diagram 2] FIG. 1 is a perspective view of a turbine airfoil. [Diagram 3] FIG. 2 is a perspective view of an example of a defective turbine component fired mold. [Figure 4] FIG. 2 is a perspective view of an example turbine component firing mold with external reinforcing features. [Diagram 5] FIG. 2 is a perspective view of a turbine component mold with added external reinforcing features. [Figure 6] FIG. 2 is a perspective view of a turbine component mold with added external reinforcing features. [Figure 7] 4 is a flow chart of exemplary process steps in creating a turbine component mold with external reinforcing features. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Referring now to the drawings, where like numerals indicate like elements throughout the several views, FIG. 1 is a schematic diagram of a gas turbine engine 10 as may be described herein. The gas turbine engine 10 may include a compressor 15. The compressor 15 compresses an incoming airflow 20. The compressor 15 delivers the compressed airflow 20 to a number of combustor cans 25. The combustor cans 25 mix the compressed airflow 20 with a pressurized fuel flow 30 and ignite the mixture to generate a hot combustion gas flow 35. Although only a single combustor can 25 is shown, the gas turbine engine 10 may include any number of combustor cans 25 arranged, such as in a circumferential array. Alternatively, the combustor 25 may be an annular combustor. The flow of combustion gases 35 is in turn delivered to a turbine 40. The flow of combustion gases 35 drives the turbine 40 to generate mechanical work. The mechanical work generated in the turbine 40 drives the compressor 15 via a rotor shaft 45. The turbine 40 and rotor shaft 45 may also drive an external load 50, such as an electrical generator.

[0009] The gas turbine engine 10 may use natural gas, hydrogen gas, various types of synthetic gas, liquid fuels, and / or other types of fuels and mixtures thereof. The gas turbine engine 10 may be any of a number of different gas turbine engines offered by GE Bernova, Schenectady, New York, including, but not limited to, a 7-series or 9-series heavy duty gas turbine engine. The gas turbine engine 10 may be part of a simple cycle or combined cycle power system or other type of power generation system. The gas turbine engine 10 may have a different configuration and may use other types of components. Other types of gas turbine engines may also be used herein. Multiple gas turbine engines, other types of turbines, and other types of power generation devices may also be used herein.

[0010] FIG. 2 illustrates an example of a turbine component 55 that may be used with the turbine 40. In this example, the turbine component 55 is a turbine blade 56. Generally, the turbine blade 56 includes an airfoil 60, a shank portion 65, and a platform 70 disposed between the airfoil 60 and the shank portion 65. The airfoil 60 generally extends radially outward from the platform 70 and includes a leading edge 72 and a trailing edge 74. The airfoil 60 may also include a concave wall defining a pressure side 76 and a convex wall defining a suction side 78. The platform 70 may be substantially horizontal and planar. The platform 70 may be exposed to the flow of hot combustion gases 35. The shank portion 65 may include a shank cavity 80 therein. The shank portion 65 may also include one or more angel wings 82 and a root structure 84, such as a dovetail. The root structure 84 may be configured to secure the turbine blade 56 to a rotor disk.

[0011] The turbine blade 56 may include one or more cooling circuits 86 extending therethrough for flowing a cooling medium, such as air from the compressor 15 or air from another source. The cooling circuits 86 and cooling medium may circulate through at least a portion of the airfoil 60, shank 65, and platform 70 in any order, direction, or path to form a flow path for the cooling medium. Many different types of turbine components 55 may be used herein. The turbine blade 56 as defined herein is for illustrative purposes only. Other components and other configurations may be used herein.

[0012] Additive manufacturing techniques for producing turbine component casting molds typically include many process steps. These steps include mold design via a CAD process, printing the mold via a ceramic slurry, preparing the mold via evacuation, cleaning, and firing the mold. However, these processes can introduce stress concentrations and other defects into the mold. This is especially true during the firing step, which can highly stress the ceramic part and lead to cracking and dimensional non-compliance. For example, FIG. 3 shows an existing airfoil fired mold 88 created by an additive manufacturing process. As shown, the airfoil mold 88 collapses during the firing step. This collapse is considered a defect 90 in the overall mold design. Another defect 96 is a crack that forms in one of the walls of the mold 88.

[0013] FIG. 4 shows a turbine component fired mold 100 made with ceramic 110 from a slurry in an additive manufacturing process. The additive manufacturing process can utilize optimization of mold external features, for example, to improve mold strength or impart microstructural advancement anywhere during the mold manufacturing process by adding external reinforcement features 120 to the component body 125. For example, the external reinforcement features 120 of the turbine component fired mold 100 can include external ribbing 130 to the airfoil 140 of the turbine part mold 100. The external ribbing 130 can extend vertically or horizontally or in any convenient direction. The external ribbing 130 can be arranged on the surface in any shape / form calculated by structural methods and verified by experience. Similarly, the size and shape of the external ribbing 130 may vary depending on the application. The addition of external ribs 130 to the turbine component mold 100 allows the turbine component mold 100 to maintain a desired dimensional fit during firing steps, etc. The external ribs 130 and other types of external stiffening features 120 help distribute stress more evenly during 3D printing and post-printing steps to improve the overall stiffness and strength of the turbine component mold 100. Traditionally, the exterior surface of the mold has been largely ignored due to multiple shell dips and uniformly thick shells.

[0014] These external reinforcing features 120 can be designed into the CAD programming for mold printing, for example, by methods and principles of topological optimization (TPO) used in various engineering disciplines and computational mechanics. TPO is a process used to optimize the distribution of material within a given design space (e.g., a 3D casting mold) to achieve specific performance goals (e.g., strengthening the shell exterior for easier handling, minimizing internal cracks in the fired microstructure, etc.).

[0015] Specifically, topology optimization is a mathematical technique that optimizes the material layout within a given design space for a given set of loads, boundary conditions, and constraints, with the goal of maximizing the performance of the system. Topology optimization differs from shape and sizing optimization in the sense that rather than working with predefined configurations, the design can take any shape within the design space. Traditional topology optimization formulations use the finite element method (FEM) to evaluate the design performance. There are currently many different TPO systems available.

[0016] 5 and 6 show further examples of turbine component firing molds 100. In these examples, a turbine blade mold 150. The turbine blade mold 150 may be a combination of a core and shell 155 or the like. In the example of FIG. 5, only the shank portion 160 of the turbine blade mold 100 has external ribs 130. In the example of FIG. 6, both the shank portion 160 and the airfoil 140 have external ribs 130. Additionally, the shank portion 160 and / or the base portion 170 (pour cup region) may also include multiple gussets 180 formed therein. The use of external ribs 130 increases the stiffness of the airfoil 140 of the turbine blade mold 150, allowing for tighter control of its deformation. Similarly, the use of gussets 180 adds rigidity to shank portion 160 and base portion 170 for optimal upright positioning of turbine component mold 100 during firing and other processing steps.

[0017] Other areas of topology optimization may include reinforced corners and edges 190. Such corners and edges 190 may typically be high stress areas of the turbine component mold 100. Topology optimization may reinforce these areas by adding material to make them more resistant to deformation and cracking. Topology optimization may also smooth out stress concentration points in the overall shape of the turbine component mold 100. By redistributing the ceramic slurry material 110, the turbine component mold 100 may become more resilient and less prone to fracture in critical areas.

[0018] Similarly, the topology optimization process can identify the load-bearing regions 200 that bear the most stress (per cast geometry and melt properties) during the casting process. These load-bearing regions 200 can be strengthened and optimized to withstand higher pressures and maintain shape integrity with less creep during the casting process. Similarly, fillets 210 (i.e., rounded corners or edges) can be used to smooth the transitions between different surfaces of the turbine component mold 100. Through topology optimization, the size and shape of the fillets 210 can be optimized to minimize stress concentrations and increase the strength of the overall mold.

[0019] Other concerns include the overall material thickness 220. Topology optimization can help identify areas to increase or decrease the material thickness 220. Such modifications can allow the turbine component mold 100 to use materials more efficiently while maintaining or improving overall structural integrity. Similarly, the optimization process can be used to tailor the external structure of the turbine component mold 100 to provide anisotropic properties, i.e., different mechanical properties along different directions. Such properties are beneficial for applications where directional strength is important. The specific features and designs resulting from topology optimization will vary based on the intended application, loading conditions, and manufacturing constraints. The optimization process considers these factors to arrive at the most suitable and efficient design for the external reinforcing feature 120 and the turbine component mold 100.

[0020] The use of the external reinforcement features 120 in the turbine component mold 100 speeds up and improves the entire casting process. The processing steps of CAD design, printing, firing, casting, and finishing are all simplified and more efficient. The combination of additive manufacturing and local optimization provides the necessary stiffness in areas of the turbine component mold 100 that are prone to cracking and deformation. Similarly, the external reinforcement features 120 allow the turbine component mold 100 to stand stably in any firing orientation. Furthermore, the overall design of the turbine component mold 100 can be quickly modified to account for specific applications and / or customizable designs.

[0021] FIG. 7 is a flow chart showing exemplary steps in a method for maximizing the design of a turbine component mold 100 to minimize productions flaws. In step 230, a portion of the turbine component mold 100 having a flaw 90 is determined, such as a crack in the airfoil 140. In step 240, the nature of the flaw 90 is determined, such as a crack. In step 250, a topology optimization process can be applied to create an external reinforcement feature 120 to eliminate the flaw 90. For example, the external reinforcement feature 120 can be an outer rib 130 or other structure to reduce stress concentrations and accommodate material thickness variations as well as load bearing areas. In step 260, a modified or improved turbine component mold 100 design can be created, such as by a CAD process. In step 270, the improved turbine component mold 100 can be created by an additive manufacturing process. In step 280, the turbine component mold 100 can be fired. In step 290, the turbine component mold 100 may be used for casting. Different other process steps may be used herein.

[0022] It should be apparent that the foregoing relates only to specific embodiments of this application and the resulting patent. Numerous changes and modifications may be made herein by those skilled in the art without departing from the general spirit and scope of the invention as defined by the following claims and their equivalents.

[0023] Further aspects of the invention are provided by the subject matter of the following clauses. [Embodiment 1] A method for optimizing strength in an improved mold for a cast component, the method comprising the steps of evaluating a flaw in an existing mold, adding external reinforcement features to a design of the improved mold, manufacturing the improved mold in an additive manufacturing process, and casting the cast component in the improved mold. [Embodiment 2] A method as described in any of the preceding embodiments, wherein the step of adding external reinforcement features to a design of the improved mold comprises adding external ribbing to a section of the improved mold. [Embodiment 3] A method according to any of the preceding embodiments, wherein the cast component is a turbine component, and the step of adding external reinforcement features to a design of the improved mold comprises adding external ribbing to at least one of an airfoil portion and a shank portion of the improved mold. [Embodiment 4] A method according to any of the preceding embodiments, wherein the step of adding external reinforcement features to a design of the improved mold comprises adding gussets to a base portion and / or a shank portion of the improved mold. [Embodiment 5] A method as described in any of the preceding embodiments, wherein the cast component is a turbine component and the step of adding external reinforcement features to a design of the improved mold comprises adding a fillet about an airfoil portion of the improved mold. [Embodiment 6] A method as described in any of the preceding embodiments, wherein the step of adding external reinforcement features to a design of the improved mold comprises adding external reinforcement features to a load bearing area of ​​the improved mold. [Embodiment 7] A method described in any of the preceding embodiments, wherein the step of adding external reinforcement features to a design of the improved mold comprises a topological optimization process. [Embodiment 8] A method according to any of the preceding embodiments, wherein the topological optimization process reduces stress concentrations in the improved mold as compared to the existing mold. [Embodiment 9] A method as described in any of the preceding embodiments, wherein the step of manufacturing the improved mold in an additive manufacturing process comprises using a ceramic material. [Embodiment 10] A method as described in any of the preceding embodiments, wherein the topological optimization process comprises redistributing the ceramic material in the improved mold. [Embodiment 11] A method as described in any of the preceding embodiments, wherein the topological optimization process comprises changing a thickness of the ceramic material in the improved mold. [Embodiment 12] The method of any of the preceding embodiments, further comprising the step of firing the improved mold. [Embodiment 13] A method as described in any of the preceding embodiments, wherein the step of adding external reinforcement features to a design of the improved mold comprises a Computer Aided Design process. [Embodiment 14] The method described in any of the preceding embodiments, wherein the improved mold comprises a combined core and shell. [Embodiment 15] A mold for a cast component, comprising a component body, wherein the component body comprises a ceramic material made from an additive manufacturing process, and one or more external reinforcement features manufactured in the component body. [Embodiment 16] A mold for a cast part as described in any of the preceding embodiments, wherein the one or more external reinforcement features comprise external ribbing. [Embodiment 17] A mold for a cast component as described in any of the preceding embodiments, wherein the cast component is a turbine component, the component body comprises at least one of an airfoil portion and a shank portion, and the one or more external reinforcement features comprise external ribbing. [Embodiment 18] A mold for a cast part described in any of the preceding embodiments, wherein the one or more external reinforcement features comprise gussets. [Embodiment 19] A mold for a cast part described in any of the preceding embodiments, wherein the one or more external reinforcement features comprise fillets. [Embodiment 20] A mold for a cast part described in any of the preceding embodiments, wherein the one or more external reinforcement features comprise external ribbing, gussets, and / or fillets. [Explanation of symbols]

[0024] 10:Gas turbine engine 15:Compressor 20:Air flow 25:Combustor can 30:Fuel flow 35:Combustion gas flow 40:Turbine 45:Rotor shaft 50:External load 55:Turbine component 56:Turbine blade 60:Airfoil 65:Shank 70:Platform 72:Leading edge 74:Trailing edge 76:Pressure side 78:Suction side 80:Shank cavity 82:Angel wing 84:Root structure 86:Cooling circuit 88:Airfoil fired mold 90:Defect 100:Turbine component fired mold 110:Ceramic 120:External reinforcement feature 125:Component body 130:External rib 140:Airfoil 150:Turbine blade mold 155:Combined core and shell 160:Shank 170:Base portion 180:Gusset 190: Corners and edges 200: Load-bearing areas 210: Fillets 220: Material thickness

Claims

1. A method for optimizing the strength of an improved mold (100) for a cast part (55), comprising the steps of: assessing an existing mold (88) for defects (90); adding external reinforcing features (120) to the design of the improved mold (100); Manufacturing an improved mold (100) by an additive manufacturing process; Casting a cast part (55) in the modified mold (100); A method comprising:

2. The method of claim 1, wherein adding external reinforcing features (120) to a design of the improved mold (100) comprises adding external ribs (130) to a portion (140) of the improved mold (100).

3. 2. The method of claim 1, wherein the cast component is a turbine component (55) and adding external reinforcing features (120) to a design of the improved mold (100) comprises adding external ribs (130) to at least one of an airfoil (140) and a shank portion (160) of the improved mold (100).

4. 2. The method of claim 1, wherein adding external reinforcing features (120) to the design of the improved mold (100) comprises adding gussets (180) to a base portion (170) and / or a shank portion (160) of the improved mold (100).

5. 2. The method of claim 1, wherein the cast component is a turbine component (55) and adding external reinforcement features (120) to a design of the improved mold (100) comprises adding a fillet (210) to an airfoil (140) of the improved mold (100).

6. 2. The method of claim 1, wherein adding external reinforcement features (120) to a design of the improved mold (100) comprises adding external reinforcement features (120) to a load-bearing area (200) of the improved mold (100).

7. The method of claim 1 , wherein adding external reinforcing features (120) to the design of the improved mold (100) comprises a topology optimization process.

8. The method of claim 7, wherein the topology optimization process reduces stress concentrations in the improved mold (100) as compared to the existing mold (88).

9. The method of claim 7, wherein producing the improved mold (100) in an additive manufacturing process includes using a ceramic material (110).

10. The method of claim 9, wherein the topology optimization process includes redistributing the ceramic material (110) within the modified mold (100).

11. The method of claim 10, wherein the topology optimization process includes varying a thickness of the ceramic material (110) in the improved mold (100).

12. The method of claim 1 further comprising the step of firing the improved mold (100).

13. The method of claim 1 , wherein the improved mold (100) comprises a combined core and shell (155).

14. A mold (100) for a cast part (55), comprising: a part body (125) including a ceramic material (110) produced from an additive manufacturing process; one or more external reinforcement features (120) fabricated on the part body (125); A mold for a cast part, comprising:

15. The mold for cast parts of claim 14, wherein the one or more external reinforcing features (120) include an outer rib (130), a gusset (180), and / or a fillet (210).

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