Simulation Method for Precision Casting of Hollow Turbine Blades Based on Ceramic Core Preheating Deformation

Abstract

This invention discloses a simulation method for precision casting of hollow turbine blades based on the preheating deformation of ceramic cores, belonging to the field of investment casting technology. It addresses the problem of inaccurate simulated dimensions of hollow turbine blades due to the failure to consider creep deformation caused by preheating of the ceramic core in the simulation. The method mainly includes the following steps: (1) generating a corresponding shell model based on the CAD model of the blade's ceramic core model; (2) implementing numerical simulation of preheating of the ceramic core in the furnace, consistent with actual production; (3) extracting the displacement field of the ceramic core caused by preheating and mapping it to the initial state of the ceramic core in the blade solidification simulation, and then performing solidification simulation of the turbine blade based on this; (4) comparing the solidification simulation results of the turbine blade considering and not considering the preheating process with the dimensional deviations of the design model. This invention can more accurately predict the dimensional changes of the blade, providing more reliable data for the study of dimensional deformation of hollow turbine blades.

Description

Technical Field

[0001] This invention patent relates to the investment casting process of hollow turbine blades, which is a new numerical simulation method that uses simulation to simulate the changes in the solidification dimensions of turbine blades caused by the preheating creep deformation of the ceramic core. Technical Background

[0002] Hollow turbine blades, as a crucial component of aero-engines, must operate under high temperature and high pressure conditions for extended periods, thus requiring complex internal cooling structures to extend their lifespan. Ceramic cores are key components used to create complex cold zone channels during the investment casting process of hollow turbine blades.

[0003] In the investment casting process of turbine blades, the single-crystal alloy is poured at 1550℃. A ceramic core is pre-fixed in the mold shell. To avoid casting defects caused by excessive temperature difference between the core / mold and the molten metal when the molten metal is poured into the shell, the ceramic core and mold shell need to be preheated before pouring the molten metal. During preheating, the ceramic core undergoes creep deformation due to the high temperature environment and its own gravity, affecting the dimensions of the turbine blade after solidification. Previous simulation techniques did not consider the impact of ceramic core preheating deformation on the final turbine blade dimensions, resulting in significant discrepancies between simulation results and measured blade dimensions. Therefore, it is essential to propose a simulation method for investment casting solidification that considers the ceramic core preheating process. Summary of the Invention

[0004] To more accurately predict the deformation of hollow turbine blades during investment casting, this invention proposes a numerical simulation method for investment casting of hollow turbine blades that considers the preheating deformation of the ceramic core. Using specific simulation techniques, the thermal deformation of the ceramic core under preheating conditions is simulated, and the deformation state of the ceramic core is mapped to the initial state of the turbine blade solidification simulation. This results in predicted turbine blade deformation that better matches actual investment casting conditions, providing more reliable data for the dimensional study of hollow turbine blades.

[0005] The technical solution of the present invention to achieve the above objectives includes the following steps:

[0006] Step 1

[0007] The completed CAD model consists of seven parts: blades, ceramic core, feeding section, crystal selector, gating system, condenser plate, and furnace body. At this point, a shell needs to be generated. The steps for generating the shell are as follows:

[0008] [1] Export the 7 CAD models from the 3D modeling software (UG) as PRT format files respectively.

[0009] [2] The model exported from ug is simultaneously imported into Hypermesh software to generate surface meshes, and the surface meshes are exported in OUT format.

[0010] [3] Import the OUT format file into the casting finite element software (ProCAST), and use the Shelling command to generate a shell for the casting model based on the surface mesh in the software.

[0011] [4] Based on the surface mesh in [3], generate a tetrahedral mesh for the finite element model. At this time, there will be 8 volumes in the software: blade, ceramic core, feeding section, crystal selector, casting system, condenser plate, furnace body, and shell.

[0012] [5] Save the finite element model in [4] as two files in vdb format.

[0013] Step 2

[0014] The numerical simulation of ceramic core preheating in the furnace, which conforms to actual production, is achieved through the following steps:

[0015] [1] Open the first vdb file and use the Delete command to delete the blades, feeding section, crystal selector, gating system, and condenser plate from the 8 volumes in ProCAST in step 1, leaving only the ceramic core, shell, and furnace body.

[0016] [2] Set the ceramic core material to Elasto-Viscoplastic properties using the Add Materials command.

[0017] [3] The temperature of the furnace body is set to rise from room temperature to 1550°C within 1 hour according to the actual preheating temperature. The initial temperature of the shell and the ceramic core is set to room temperature.

[0018] [4] Set the heating method of the furnace body shell and ceramic core to radiation heating.

[0019] [5] Set the corresponding simulation parameters and perform finite element solution for heating creep deformation.

[0020] Step 3

[0021] The preheating deformation of the ceramic core is mapped to the solidification simulation, and the solidification casting simulation of the blade is completed:

[0022] [1] Open the second vdb file, use the Extract command to extract the creep simulation results of the ceramic core obtained in step 2, and use the Mapping command to map the extracted creep deformation results (displacement field) onto the ceramic core of the simulation model, and set the initial temperature conditions of the ceramic core. Set the initial temperature conditions for other bodies as well.

[0023] [2] Assign material to each body.

[0024] [3] Set the boundary conditions.

[0025] [4] Set the simulation parameters and submit the blade solidification calculation.

[0026] Step 4

[0027] Extract the outer contour dimensions of the corresponding cross section, and compare the deviations between the turbine blade solidification simulation results considering the ceramic core preheating process and those not considering the preheating process with the dimensions of the design model.

[0028] The expected effect of this invention is that, based on actual production, the solidification simulation of turbine blades with preheated deformation of ceramic core can more accurately predict the deformation of hollow turbine blades caused by preheated deformation of ceramic core, which is more consistent with the actual size distribution of the blades and has certain guiding significance for improving the dimensional accuracy of turbine blades.

[0029] The present invention will be further described below with reference to the accompanying drawings and examples. Attached Figure Description

[0030] Figure 1 This is a flowchart of the present invention patent.

[0031] Figure 2 It is an assembly diagram showing the relationship between the feeding section, crystal selector, condenser plate, blades, gating system, and ceramic core.

[0032] Figure 3 It is the generated shell.

[0033] Figure 4 Assembly diagram of ceramic core and shell.

[0034] Figure 5 This is a displacement field mapping diagram of the ceramic core.

[0035] Figure 6 This is a diagram showing the selection of the measurement section.

[0036] Figure 7 This is a comparison chart of the deviations between the simulation dimensions and the design model dimensions at section 1, considering and not considering the preheating process.

[0037] Figure 8 This is a comparison chart of the deviations between the simulation dimensions and the design model dimensions, considering and not considering the preheating process, at section 2.

[0038] Figure 9 This is a comparison chart of the deviations between the simulation dimensions and the design model dimensions, considering and not considering the preheating process, at section 3. Detailed Implementation

[0039] The following detailed description of embodiments of the present invention is provided with reference to the accompanying drawings: These embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and processes are given. However, the scope of protection of the present invention is not limited to the following embodiments. Taking a hollow turbine blade as an example, the specific implementation process of the present invention is as follows: Figure 1 As shown:

[0040] Step 1

[0041] The completed CAD model consists of seven parts: blades, ceramic core, feeding section, crystal selector, gating system, condenser plate, and furnace body. At this point, a shell needs to be generated. The steps for generating the shell are as follows:

[0042] [1] Export the 7 CAD models from the 3D modeling software (UG) as PRT format files respectively.

[0043] Figure 2 It is an assembly diagram of the shrinkage section, crystal selector, condenser plate, blades, gating system, and ceramic core.

[0044] [2] The model exported from ug is simultaneously imported into Hypermesh software to generate surface meshes, and the surface meshes are exported in OUT format.

[0045] [3] Import the OUT format file into the casting finite element software (ProCAST), and use the Shelling command to generate a shell for the casting model based on the surface mesh in the software.

[0046] Figure 3 It is the generated shell.

[0047] [4] Based on the surface mesh in [3], generate a tetrahedral mesh for the finite element model. At this time, there will be 8 volumes in the software: blade, ceramic core, feeding section, crystal selector, casting system, condenser plate, furnace body, and shell.

[0048] [5] Save the finite element model in [4] as two files in vdb format.

[0049] Step 2

[0050] The numerical simulation of preheating both the medium-sized shell and the ceramic core together in the furnace, consistent with actual production, is achieved through the following steps:

[0051] [1] Open the first vdb file and use the Delete command to delete the blades, feeding section, crystal selector, gating system, and condenser plate from the 8 volumes in ProCAST in step 1, leaving only the ceramic core, shell, and furnace body.

[0052] Figure 4It is an assembly drawing of the ceramic core and shell.

[0053] [2] Set the ceramic core material to elasto-viscoplastic properties using the Add Materials command.

[0054] [3] The furnace body temperature is set to rise from room temperature to 1550°C within 1 hour according to the actual preheating conditions, and the initial temperature of the shell and ceramic core is set to room temperature.

[0055] [4] Set the heating method of the furnace body shell and ceramic core to thermal radiation heating.

[0056] [5] Set the corresponding simulation parameters and solve the heating creep deformation.

[0057] Step 3

[0058] The preheating deformation of the ceramic core is mapped to solidification simulation to complete the solidification casting simulation of the blade.

[0059] [1] Open the second vdb file, use the extract command to extract the creep simulation results of the ceramic core obtained in step 2, and use the Mapping command to map the extracted creep results onto the ceramic core of the simulation model, setting it as the initial temperature condition of the ceramic core. Set the initial temperature conditions for other bodies as well.

[0060] Figure 5 It maps the displacement field of the preheated ceramic core onto the ceramic core in the solidification simulation.

[0061] [2] Assign material to each body.

[0062] [3] Set the boundary conditions.

[0063] [4] Set the simulation parameters and submit the calculation.

[0064] Step 4

[0065] Extract the outer contour dimensions of the corresponding cross section, and compare the deviations between the turbine blade solidification simulation results considering the ceramic core preheating process and those not considering the ceramic core preheating process with the dimensions of the design model.

[0066] Figure 6 Select a diagram for the measurement section.

[0067] Figure 7-9 Therefore Figure 6 The selected section is the object. The simulated solidification dimensions of the blade are calculated with and without considering the preheating process, and a comparison chart of the differences between these dimensions and the design model is created. (See figure.) Figure 7-9It can be seen that the numerical simulation method for blade solidification based on the preheating deformation of the ceramic core, which takes into account the influence of the preheating deformation of the ceramic core on the deformation during the blade solidification process, is more consistent with the actual working conditions, making the simulation results closer to the design model. The average deviation of section 1 decreased by 0.073 mm, and the maximum deviation decreased by 0.441 mm; the average deviation of section 2 decreased by 0.005 mm, and the maximum deviation decreased by 0.165 mm; and the average deviation of section 3 decreased by 0.009 mm, and the maximum deviation decreased by 0.133 mm. Therefore, the numerical simulation method for blade solidification based on the preheating deformation of the ceramic core can effectively improve the accuracy of the simulation.

Claims

1. A simulation method for precision casting of hollow turbine blades based on preheating deformation of ceramic cores, characterized in that... Follow these steps: Step 1 The completed CAD model consists of seven parts: blades, ceramic core, feeding section, crystal selector, gating system, condenser plate, and furnace body. At this point, a shell needs to be generated. The steps for generating the shell are as follows: [1] Export the 7 CAD models from the 3D modeling software UG as PRT format files respectively; [2] The model exported from ug is simultaneously imported into Hypermesh software to generate surface meshes, and the surface meshes are exported in OUT format; [3] Import the OUT format file into the casting finite element software ProCAST, and use the Shelling command to generate a shell for the casting model based on the surface mesh in the software; [4] Based on the surface mesh in [3], generate a tetrahedral mesh for the finite element model. At this time, there will be 8 volumes in the software: blade, ceramic core, feeding section, crystal selector, casting system, condenser plate, furnace body, and shell. [5] Save the finite element model in [4] as two files in vdb format; Step 2 The numerical simulation of ceramic core preheating in the furnace, which conforms to actual production, is achieved through the following steps: [1] Open the first vdb file and use the Delete command to delete the blades, feeding section, crystal selector, gating system, and condenser plate in the 8 volumes of ProCAST in step 1, leaving only the ceramic core, shell, and furnace body; [2] Set the ceramic core material to an elasto-viscoplastic material property using the Add Materials command; [3] The temperature of the furnace body is set to rise from room temperature to 1550°C within 1 hour according to the actual preheating temperature change, and the initial temperature of the shell and ceramic core is set to room temperature; [4] Set the heating method for the furnace body shell and ceramic core to radiation heating; [5] Set the corresponding simulation parameters and perform finite element solution for heating creep deformation; Step 3 The preheating deformation of the ceramic core is mapped to the solidification simulation, and the solidification casting simulation of the blade is completed: [1] Open the second vdb file, use the Extract command to extract the creep simulation results of the ceramic core obtained in step 2, and use the Mapping command to map the extracted creep deformation results (displacement field) onto the ceramic core of the simulation model, set the initial temperature conditions of the ceramic core, and set the initial temperature conditions for other bodies. [2] Assign materials to each body; [3] Set the boundary conditions; [4] Set the simulation parameters and submit the blade solidification calculation; Step 4 Extract the outer contour dimensions of the corresponding cross section, and compare the deviations between the solidification simulation results of the turbine blade considering the preheating process of the ceramic core and those not considering the preheating process with the dimensions of the design model.

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