Method for reducing bearing ring carburizing deformation based on finite element simulation design of flow guide tooling

Abstract

The application discloses a method for reducing bearing ring carburizing deformation by designing a guide device based on finite element simulation, and aims to solve the problem of large deformation of a bearing ring in a carburizing heat treatment process.The method for reducing bearing ring carburizing deformation comprises the following steps: first, a three-dimensional geometric model of a vacuum carburizing furnace is established, and the positions of air inlets and outlets are determined; second, a flow field distribution diagram of the bearing ring is derived by calculating a flow field through a k-omega model of a CFD module of COMSOL finite element software, and the opening positions and aperture sizes of the guide device are adjusted and optimized according to the flow field distribution diagram; third, the optimal distance between the guide device and the uppermost bearing ring is optimized through a Nelder-Mead algorithm; fourth, the guide device is installed below an air inlet of the vacuum carburizing furnace, the distance between the guide device and the uppermost bearing ring is selected as the optimal distance, and gas quenching treatment is carried out after carburizing.The application reduces bearing ring carburizing deformation by establishing a finite element model of a carburizing process and calculating a flow field of a gas quenching cooling process.

Description

Technical Field

[0001] This invention relates to a method for reducing the carburizing deformation of bearing rings by designing a flow guiding tool based on COMSOL finite element simulation. Background Technology

[0002] As the "heart" of an aircraft, the performance, lifespan, and reliability of an aircraft engine largely depend on its key component—the aircraft bearing. The quality of the aircraft bearing directly affects the overall performance of the aircraft engine and is a crucial factor determining its safe and reliable operation.

[0003] Carburized bearing steel is a high-quality low-carbon or medium-carbon alloy steel with excellent mechanical properties, comprehensive mechanical properties, and high-temperature resistance. After carburizing and quenching, the surface carbon content of the bearing rings increases, forming acicular martensite and retained austenite structures, which enhances surface strength and wear resistance. The core maintains a low carbon content, ensuring high strength and impact toughness. Carburizing also creates residual compressive stress on the surface of the bearing steel, which helps improve the bearing's fatigue life.

[0004] Bearing rings undergo deformation during heat treatment. In actual production, excessive deformation after grinding can lead to uneven hardening layers and uneven residual stress distribution, affecting bearing life. To improve bearing strength, precision, and lifespan, heat treatment deformation must be minimized during bearing manufacturing. Deformation during carburized steel heat treatment is caused by the combined effects of thermal strain, elastic strain, plastic strain, structural strain, and phase transformation plastic strain. While the laws and mechanisms of heat treatment deformation have been extensively studied, reports on the deformation mechanism of carburizing heat treatment are relatively few. This is mainly because carburizing heat treatment results in different carbon contents on the surface and in the core of the workpiece, leading to differences in phase transformation temperatures and products. The vacuum environment also increases the difficulty of controlling bearing ring deformation, further complicating the analysis.

[0005] Currently, controlling the carburizing deformation of bearing rings through experiments is time-consuming and costly. Furthermore, the carburizing heat treatment process is relatively fixed and difficult to adjust due to the influence of material microstructure and properties. Additionally, the complex environment of a vacuum furnace makes some control measures difficult to implement. Some scholars have also used the finite element method to simulate the carburizing deformation of parts; however, there is limited research on the simulation of carburizing heat treatment for bearing rings, and the models do not consider the overall working environment, making them suitable for revealing the deformation mechanism but difficult to control the deformation based on the model. Summary of the Invention

[0006] The present invention aims to solve the problem of large deformation of bearing rings during carburizing heat treatment, and provides a method for reducing the deformation of bearing rings during carburizing by designing a flow guiding tool based on finite element simulation.

[0007] The present invention, based on finite element simulation design, provides a method for reducing the carburization deformation of bearing rings using a flow guiding fixture. This method is implemented through the following steps:

[0008] 1. The heating chamber and cooling chamber of the ECM vacuum carburizing furnace were measured in actual operation. A three-dimensional geometric model of the ECM vacuum carburizing furnace was established to determine the position of the air inlet and outlet. Then, the geometric model of the bearing ring and the material frame was drawn to obtain the vacuum carburizing furnace model.

[0009] 2. Import the vacuum carburizing furnace model obtained in step 1 into the COMSOL finite element software, mesh the vacuum carburizing furnace model, and then perform flow field calculation using the k-ω model of the CFD module in the COMSOL finite element software. Export the (lateral) flow field distribution diagram at the uppermost bearing ring (near the air inlet). Adjust and optimize the opening position and aperture size of the flow guiding tool according to the flow field distribution diagram to obtain the optimized flow guiding tool.

[0010] 3. The optimal distance L between the flow guiding tool and the uppermost bearing ring is optimized by using the Nelder-Mead algorithm. The value of L is adjusted to reduce the value of η, which characterizes the uniformity of the flow field. When the value of η is minimized, the optimal distance L is obtained.

[0011] The formula for calculating the value of η is as follows:

[0012]

[0013] In the formula, spf.U represents the flow velocity magnitude, ave.U represents the linear average value of the flow velocity in the circumferential direction of the ring, and s represents the unit area (in the furnace cavity);

[0014] Fourth, based on the optimized opening position and diameter of the flow guide tool in step two, the flow guide tool is fabricated using high-temperature alloy material. The flow guide tool is installed below the air inlet of the ECM vacuum carburizing furnace. The distance between the flow guide tool and the uppermost bearing ring is selected from the optimal distance L determined in step three. After carburizing, gas quenching treatment is performed, thus completing the method of reducing the carburizing deformation of the bearing ring based on the design of the flow guide tool using finite element simulation.

[0015] This invention calculates the flow field distribution in a vacuum air quenching furnace using finite element method simulation, and designs a flow-guiding fixture based on the model to control the flow field distribution. The diameter and position of the orifices in the flow-guiding fixture, as well as the distance between the fixture and the bearing ring, are optimized to ensure a uniform flow field distribution near the bearing ring. A high-temperature alloy material is selected for machining the designed flow-guiding fixture. The flow-guiding fixture is applied to actual carburizing processes, and the roundness, major and minor axis positions, and shrinkage of the bearing ring before and after carburizing are tested to reduce bearing ring deformation during carburizing. This method, which uses model design to guide fixture design, saves time and costs, and reduces deformation of aero-engine bearing rings during carburizing.

[0016] The present invention provides a method for reducing the carburizing deformation of bearing rings based on finite element simulation design of flow guiding fixtures, which has the following beneficial effects:

[0017] This invention proposes a method for reducing bearing ring carburizing deformation by designing flow-guiding fixtures based on finite element simulation. This method establishes a finite element model of the carburizing process and calculates the flow field during air quenching. The flow-guiding fixture is then designed and its placement optimized based on the flow field distribution. Compared to traditional experimental methods for reducing deformation, this model-guided method effectively reduces costs and avoids the operational difficulties of experimental methods due to the solidification of heat treatment process parameters and complex vacuum environments.

[0018] In addition, this invention uses high-temperature alloy materials to process the flow guide tooling for actual carburizing deformation test verification of the bearing rings. Through the demonstration method of combining test data and simulation results, it achieves the effect of reasonable design, effective guidance for production, and good structural safety and reliability. Attached Figure Description

[0019] Figure 1 Finite element mesh generation diagram of the gas quenching process in the embodiment;

[0020] Figure 2 Longitudinal distribution diagram of the flow field in the embodiment;

[0021] Figure 3 Lateral flow field distribution diagram of the uppermost bearing ring in the embodiment;

[0022] Figure 4 A schematic diagram of the optimized flow guiding tool dimensions in the embodiment;

[0023] Figure 5 Lateral flow field distribution diagram after installing the flow guiding tool in the embodiment;

[0024] Figure 6 The diagram showing the relationship between the flow field uniformity η and the distance L from the collar to the baffle in the embodiment. Detailed Implementation

[0025] Specific Implementation Method 1: This implementation method, based on finite element simulation design of a flow guiding fixture to reduce the carburizing deformation of bearing rings, is carried out according to the following steps:

[0026] 1. The heating chamber and cooling chamber of the ECM vacuum carburizing furnace were measured in actual operation. A three-dimensional geometric model of the ECM vacuum carburizing furnace was established to determine the position of the air inlet and outlet. Then, the geometric model of the bearing ring and the material frame was drawn to obtain the vacuum carburizing furnace model.

[0027] 2. Import the vacuum carburizing furnace model obtained in step 1 into the COMSOL finite element software, mesh the vacuum carburizing furnace model, and then perform flow field calculation using the k-ω model of the CFD module in the COMSOL finite element software. Export the (lateral) flow field distribution diagram at the uppermost bearing ring (near the air inlet). Adjust and optimize the opening position and aperture size of the flow guiding tool according to the flow field distribution diagram to obtain the optimized flow guiding tool.

[0028] 3. The optimal distance L between the flow guiding tool and the uppermost bearing ring is optimized by using the Nelder-Mead algorithm. The value of L is adjusted to reduce the value of η, which characterizes the uniformity of the flow field. When the value of η is minimized, the optimal distance L is obtained.

[0029] The formula for calculating the value of η is as follows:

[0030]

[0031] In the formula, spf.U represents the flow velocity magnitude, ave.U represents the linear average flow velocity along the circumference of the ring, and s represents the unit area;

[0032] Fourth, based on the optimized opening position and diameter of the flow guide tool in step two, the flow guide tool is fabricated using high-temperature alloy material. The flow guide tool is installed below the air inlet of the ECM vacuum carburizing furnace. The distance between the flow guide tool and the uppermost bearing ring is selected from the optimal distance L determined in step three. After carburizing, gas quenching treatment is performed, thus completing the method of reducing the carburizing deformation of the bearing ring based on the design of the flow guide tool using finite element simulation.

[0033] The Nelder-Mead algorithm in this implementation is a direct search method, which effectively solves the optimization problem when there is no derivative information.

[0034] This embodiment utilizes a multiphysics coupling model to simulate the flow field distribution and bearing ring deformation behavior in the carburizing furnace. Based on the flow field distribution characteristics, a flow guiding fixture is designed to ensure a uniform flow field distribution, thereby improving the temperature field distribution of the bearing rings during the cooling process and reducing bearing ring deformation. The actual carburizing deformation of the bearing rings is then verified through machining experiments using the fixture.

[0035] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that a three-dimensional geometric model of the ECM vacuum carburizing furnace is established using Solidworks software in step one.

[0036] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the air inlet in step 1 is located at the top of the furnace cavity of the ECM vacuum carburizing furnace, and the air outlet is located at the bottom of the front and rear furnace walls of the furnace cavity.

[0037] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that, in step one, multiple layers of material frames are arranged along the height direction of the vacuum carburizing furnace cavity, and the ring bearings are placed in the material frames.

[0038] Specific Implementation Method 5: This implementation method differs from Specific Implementation Methods 1 to 4 in that a free tetrahedral mesh is used to divide the vacuum carburizing furnace model in step 2.

[0039] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One through Five in that the flow field calculation in step two uses the k-ω model. The calculation formula for the k-ω model is as follows:

[0040]

[0041] In the formula, ρ is the fluid density, k is the turbulent kinetic energy, and u is the velocity vector. t For turbulent dynamic viscosity, P k Let ε be the turbulent kinetic energy generation term, t be the turbulent dissipation rate, t be the time, and ▽ be the divergence.

[0042]

[0043] In the formula, ω is the turbulence frequency, and β and γ are empirical constants.

[0044] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the flow guiding tool in step four is made of 1Cr28Ni48 high-temperature alloy material.

[0045] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the thickness of the flow guiding tool in step four is 5mm.

[0046] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the carburizing in step four is carried out under vacuum conditions using acetylene at a temperature of 960°C.

[0047] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 9 in that the gas quenching treatment in step 4 is performed using nitrogen gas at a pressure of 2 bar for cooling.

[0048] Example: This example demonstrates a method for reducing bearing ring carburizing deformation based on finite element simulation design of a flow guiding fixture, implemented according to the following steps:

[0049] 1. The heating chamber and cooling chamber of the ECM vacuum carburizing furnace were measured. A three-dimensional geometric model of the ECM vacuum carburizing furnace was established using Solidworks software. The air inlet was set at the top of the furnace cavity, and the air outlet was set at the bottom of the front and rear furnace walls. Multiple layers of material frames were set along the height of the furnace cavity, and the ring bearings were placed in the material frames to obtain the vacuum carburizing furnace model.

[0050] 2. Import the vacuum carburizing furnace model obtained in step one into the COMSOL finite element software. Mesh the vacuum carburizing furnace model using a free tetrahedral mesh, and then perform flow field calculations using the k-ω model. The calculation formula for the k-ω model is as follows:

[0051]

[0052] In the formula, ρ is the fluid density, k is the turbulent kinetic energy, and u is the velocity vector. t For turbulent dynamic viscosity, P k Let ε be the turbulent kinetic energy generation term, t be the turbulent dissipation rate, t be the time, and ▽ be the divergence.

[0053]

[0054] In the formula, ω is the turbulence frequency, and β and γ are empirical constants.

[0055] The longitudinal distribution of the flow field during the air quenching cooling process calculated in this embodiment is shown below. Figure 2 The lateral distribution of the flow field near the uppermost bearing ring is shown in the figure. Figure 3 The spatial flow field distribution within the gas quenching furnace was adjusted by modifying the opening design on the flow guiding fixture. Through multiple numerical simulations, the influence of the opening position and size on the spatial velocity distribution was determined. Specifically, the flow field uniformity around the ring was highest when the opening was located directly above it, and the opening diameter affected the velocity of the flow field below. The process involved designing the opening design, calculating the flow field distribution around the ring, and then adjusting the opening position based on the flow field distribution feedback. This process was repeated until the most suitable opening design was found. The optimized flow guiding fixture's dimensions and structure are shown below. Figure 4 As shown;

[0056] 3. The optimal distance L between the flow guiding tool and the bearing ring is optimized by using the Nelder-Mead algorithm. The value of L is adjusted to reduce the value of η, which characterizes the uniformity of the flow field. When the value of η is minimized, the optimal distance L is obtained.

[0057] The formula for calculating the value of η is as follows:

[0058]

[0059] In the formula, spf.U represents the flow velocity magnitude; ave.U represents the linear average flow velocity along the circumference of the ring; and s represents the unit area.

[0060] Fourth, based on the optimized opening position and diameter of the flow guide tool in step two, the flow guide tool is fabricated using high-temperature alloy material. The flow guide tool is installed below the air inlet of the ECM vacuum carburizing furnace. The distance between the flow guide tool and the uppermost bearing ring is selected from the optimal distance L determined in step three. The carburizing process is vacuum acetylene carburizing at a temperature of 960℃. The gas quenching process uses nitrogen cooling at a pressure of 2 bar. This completes the method of reducing bearing ring carburizing deformation based on finite element simulation design of the flow guide tool.

[0061] In this embodiment, a 3D model of the carburizing chamber, gas quenching chamber, and ring of the ECM carburizing furnace was constructed using Solidworks, and then imported into Comsol multiphysics coupling software for numerical simulation. The gas quenching chamber of the ECM carburizing furnace consists of a furnace cavity, a gas inlet at the top, gas outlets on both sides, and a material frame, and is used to construct the gas quenching cooling model.

[0062] In step three of this embodiment, the integral of η is defined using a nonlocally coupled integral operator. Calculations show that the value of η without the flow guiding device is 0.05345. After applying the optimized flow guiding device for shielding, the value of η decreases significantly to 0.009928. This indicates that the shielding and flow guiding of the flow guiding device makes the flow field distribution around the ring more uniform.

[0063] In step three of this embodiment, adjusting the distance L between the flow guiding tool and the uppermost ring yields a series of η values. The Nelder-Mead optimization algorithm is then used to find the minimum η value corresponding to the minimum spacing η. The relationship between the L value and the corresponding η value during the optimization process is as follows: Figure 6 As shown in the figure, when L is 0.128m, η reaches its minimum value, which means that when the distance between the flow guiding tool and the uppermost ring is 0.128m, the flow field distribution in the circumferential direction of the ring is the most uniform during the air quenching process.

[0064] Based on the above model, this embodiment calculates the flow field distribution near the bearing ring when the flow guiding fixture is present. Figure 5 The flow field distribution around the ring is made uniform through the design of the flow guiding tool.

[0065] A flow-guiding fixture was fabricated using high-temperature alloy materials, and actual carburizing deformation tests were conducted on the bearing rings. Using a roundness gauge, the changes in the roundness of the inner and outer diameters and the major and minor axes of the bearing rings before and after carburizing were measured with and without the flow-guiding fixture, as shown in Table 1. The changes in roundness and major and minor axes indicate the magnitude of the bearing ring carburizing deformation; larger roundness and greater changes in major and minor axes indicate greater deformation. By placing the flow-guiding fixture, the shrinkage of the inner and outer diameters of the bearing rings and their roundness were reduced, thus minimizing deformation during the carburizing process.

[0066] Table 1 Deformation data with and without baffles

[0067]

[0068] By comparing calculation and experimental data, the method of designing a flow guiding fixture based on finite element simulation to reduce the deformation of bearing rings during carburizing, as proposed in this invention, improves the uniformity of the flow field distribution in the vacuum quenching furnace and reduces the deformation of bearing rings during the carburizing process.

Claims

1. A method for reducing the carburizing deformation of bearing rings based on finite element simulation design of flow guiding fixtures, characterized in that... The method for reducing the carburization deformation of bearing rings by designing a flow guiding fixture based on finite element simulation is implemented according to the following steps:

1. The heating chamber and cooling chamber of the ECM vacuum carburizing furnace were measured in actual operation. A three-dimensional geometric model of the ECM vacuum carburizing furnace was established to determine the position of the air inlet and outlet. Then, the geometric model of the bearing ring and the material frame was drawn to obtain the vacuum carburizing furnace model.

2. Import the vacuum carburizing furnace model obtained in step 1 into the COMSOL finite element software, mesh the vacuum carburizing furnace model, and then perform flow field calculation using the k-ω model of the CFD module in the COMSOL finite element software. Export the flow field distribution diagram at the uppermost bearing ring. Adjust and optimize the opening position and aperture size of the flow guiding tool according to the flow field distribution diagram to obtain the optimized flow guiding tool.

3. The optimal distance L between the flow guiding tool and the uppermost bearing ring is optimized by using the Nelder-Mead algorithm. The value of L is adjusted to reduce the value of η, which characterizes the uniformity of the flow field. When the value of η is minimized, the optimal distance L is obtained. The formula for calculating the value of η is as follows: In the formula Indicates the magnitude of the flow velocity. The value represents the linear average velocity along the circumference of the ring, and s represents the unit area.

4. Based on the optimized opening position and aperture size of the flow guide tool in step 2, the flow guide tool is fabricated using high-temperature alloy material. The flow guide tool is installed below the air inlet of the ECM vacuum carburizing furnace. The distance between the flow guide tool and the uppermost bearing ring is selected from the optimal distance L determined in step 3. After carburizing, gas quenching treatment is performed, thus completing the method of reducing the carburizing deformation of the bearing ring based on the design of the flow guide tool using finite element simulation. The flow field calculation in step two uses the k-ω model, and the calculation formula for the k-ω model is as follows: In the formula, ρ is the fluid density, k is the turbulent kinetic energy, and u is the velocity vector. t For turbulent dynamic viscosity, P k Let ε be the turbulent kinetic energy generation term, t be the turbulent dissipation rate, and t be the time term. For divergence; In the formula, ω is the turbulence frequency, and β and γ are empirical constants.

2. The method for reducing bearing ring carburizing deformation based on finite element simulation design of flow guiding fixtures according to claim 1, characterized in that... In step one, a three-dimensional geometric model of the ECM vacuum carburizing furnace is created using Solidworks software.

3. The method for reducing bearing ring carburizing deformation based on finite element simulation design of flow guiding fixtures according to claim 1, characterized in that... In step one, the air inlet is set at the top of the furnace cavity of the ECM vacuum carburizing furnace, and the air outlet is set at the bottom of the front and rear furnace walls of the furnace cavity.

4. The method for reducing bearing ring carburizing deformation based on finite element simulation design of flow guiding fixtures according to claim 1, characterized in that... In step one, multiple layers of material frames are set along the height of the vacuum carburizing furnace cavity, and the ring bearings are placed in the material frames.

5. The method for reducing bearing ring carburizing deformation based on finite element simulation design of flow guiding fixtures according to claim 1, characterized in that... In step two, a free tetrahedral mesh is used to mesh the vacuum carburizing furnace model.

6. The method for reducing bearing ring carburizing deformation based on finite element simulation design of flow guiding fixtures according to claim 1, characterized in that... In step four, the flow guiding tooling is made of 1Cr28Ni48 high-temperature alloy material.

7. The method for reducing bearing ring carburizing deformation based on finite element simulation design of flow guiding fixtures according to claim 1, characterized in that... The thickness of the flow guiding tool in step four is 5mm.

8. The method for reducing bearing ring carburizing deformation based on finite element simulation design of flow guiding fixtures according to claim 1, characterized in that... The carburizing in step four is carried out under vacuum conditions using acetylene at a temperature of 960°C.

9. The method for reducing bearing ring carburizing deformation based on finite element simulation design of flow guiding fixtures according to claim 1, characterized in that... In step four, the gas quenching process involves cooling with nitrogen gas at a pressure of 2 bar.

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