Simulation method of high-voltage multi-electron-beam selective melting forming process

Abstract

The invention discloses a simulation method for a high-voltage multi-electron-beam selective melting forming process, which is characterized by comprising the following steps of: establishing a plurality of high-voltage electron gun integral models, and performing electromagnetic simulation to obtain an electron space-time movement track and a working plane electron beam spot shape; according to the collision model and the energy loss model, energy and power distribution conditions of the electrons impacting the powder bed under high-pressure acceleration are obtained, and a heat source model is obtained; according to the heat source model, the energy field distribution condition of the component is obtained, the single-layer and single-channel stress and plastic strain of the structural component are calculated, and the overall stress deformation of the structural component is obtained according to the single-layer and single-channel energy field distribution. The invention provides an additive manufacturing process simulation method for a high-pressure multi-electron-beam selective melting forming difficult-to-weld high-temperature material, belongs to the field of additive manufacturing numerical simulation, and can help to predict stress deformation of a formed part so as to adjust the process and reduce the crack occurrence rate during electron beam powder bed melting additive manufacturing of the difficult-to-weld high-temperature material. And deformation is reduced.

Description

Technical Field

[0001] The present invention relates to a simulation method for a high-pressure multi-electron beam selective melting forming process. Background Art

[0002] With the rapid development of additive manufacturing technology, especially its application in fields such as aerospace, the high-pressure electron gun large-size additive manufacturing technology for difficult-to-weld high-temperature materials has gradually become a research and production hotspot. However, traditional single-electron beam simulations ignore the multi-beam cooperative effects (such as heat source interference and stress superposition), and it is difficult to reflect the complex thermo-mechanical coupling behavior in actual multi-beam processes. Moreover, the deep penetration characteristics of high-pressure electron beams (at the 120 kV level) lead to large errors in the energy deposition model. Existing heat source models (such as Gaussian distribution) do not consider the inelastic collision energy loss of high-energy electrons with the powder bed, and it is difficult to accurately predict the evolution behavior of the temperature field and stress field during the forming process.

[0003] During the electron beam selective melting process, the changes in the temperature field and stress field and their effects on material properties are the fundamental reasons for the deformation, warping, and cracking of the formed parts. Although existing research has provided a thermo-structural coupling model for a single electron beam, when facing the working environment of multiple high-pressure electron beams and the complex behavior of difficult-to-weld high-temperature materials, existing methods often have problems such as inaccurate prediction, large computational amount, and many experimental trials and errors. Therefore, developing an efficient and accurate simulation method for the high-pressure multi-electron beam selective melting forming process has important practical significance for improving the quality and efficiency of additive manufacturing. Summary of the Invention

[0004] To solve the defects of the existing technology, the present invention provides a simulation method for a high-pressure multi-electron beam selective melting forming process, including the following steps: Establish an overall model of multiple high-pressure electron guns, and perform electromagnetic simulation to obtain the electron spatio-temporal motion trajectory and the electron beam spot morphology on the working plane; According to the collision model and the energy loss model, obtain the energy and power distribution of electrons hitting the powder bed under high-pressure (120 kV) acceleration, that is, obtain an accurate heat source model; According to the heat source model, obtain the energy field distribution of the component, calculate the stress and plastic strain of a single layer and a single pass of the structural part, and obtain the overall stress deformation of the structural part according to the energy field distribution of a single layer and a single pass.

[0005] Preferably, the simulation method for the high-pressure multi-electron beam selective melting forming process provided by the present invention includes the following specific steps: Step 1: Based on COMSOL Multiphysics, establish a high-pressure electron gun simulation model, including a cathode, an anode, a focusing coil, and a deflection system, etc., simulate to obtain the electron trajectory and beam spot morphology, and output spatio-temporal coordinate data; Step 2: Simulate the mutual collision and absorption between electrons and powder bed materials through the Monte Carlo collision model (MCC), establish a high-energy electron energy loss model based on the Bethe-Bloch formula, and then establish a power density distribution model, and obtain a heat source model by fitting the equation; Step 3: Establish a thermo-elasto-viscoplastic material constitutive model based on the deposition temperature range using elastoplastic theory, use the established heat source model to calculate the temperature field and local stress and deformation fields, and extract its plastic strain parameters; Step 4: Based on the finite element birth and death element technology and the flash heating method, establish a thermo-mechanical behavior simulation model for the forming area of a single electron gun; Step 5: According to the inherent strain theory, and based on the characteristics of multi-electron beam forming, adopt the steps of forming separately and splicing in segments to calculate the stress and deformation of the overall part.

[0006] The advantages and beneficial effects of the present invention are as follows: The present invention provides an additive manufacturing process simulation method for difficult-to-weld high-temperature materials by high-pressure multi-electron beam selective melting forming, belonging to the field of additive manufacturing numerical simulation, which can help predict the stress and deformation of the formed parts, so as to adjust the process and reduce the crack incidence rate during the electron beam powder bed melting additive manufacturing of difficult-to-weld high-temperature materials and reduce deformation. Specific embodiments

[0007] The following combines embodiments to further describe the specific embodiments of the present invention. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and cannot be used to limit the protection scope of the present invention.

[0008] The technical solution specifically implemented by the present invention is as follows: The present invention provides a simulation method for a high-pressure multi-electron beam selective melting forming process, including the following steps: Establish a whole model of multiple high-pressure electron guns, and perform electromagnetic simulation to obtain the electron spatio-temporal motion trajectory and the electron beam spot morphology on the working plane; Obtain the energy and power distribution of electrons hitting the powder bed under high-pressure (120 kV) acceleration according to the collision model and energy loss model, that is, obtain an accurate heat source model; According to the heat source model, obtain the energy field distribution of the component, calculate the stress and plastic strain of a single layer and single pass of the structural part, and obtain the overall stress and deformation of the structural part according to the energy field distribution of a single layer and single pass.

[0009] The simulation method for the high-pressure multi-electron beam selective melting forming process provided by the present invention includes the following specific steps: Step 1: Based on COMSOL Multiphysics, establish a high-pressure electron gun simulation model, including a cathode, an anode, a focusing coil, and a deflection system, etc., simulate to obtain the electron trajectory and beam spot morphology, and output spatio-temporal coordinate data; Step 2: Simulate the mutual collision and absorption between electrons and powder bed materials through the Monte Carlo Collision (MCC) model, establish a high-energy electron energy loss model based on the Bethe-Bloch formula, and then establish a power density distribution model. Obtain the heat source model by fitting the equation. Step 3: Establish a thermo-elasto-viscoplastic material constitutive model based on the deposition temperature range using elastoplastic theory. Use the established heat source model to calculate the temperature field and local stress deformation field, and extract its plastic strain parameters. Step 4: Based on the finite element birth and death element technology and the flash heating method, establish a thermal-mechanical behavior simulation model for the single electron gun forming area. Step 5: According to the inherent strain theory and the characteristics of multi-electron beam forming, adopt the steps of separate forming and segmented splicing to calculate the stress and deformation of the overall part.

[0010] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A simulation method for a high-voltage multi-electron beam selective melting forming process, characterized in that It includes the following steps: Establish multiple overall models of high-voltage electron guns, and conduct electromagnetic simulations to obtain the electron spatio-temporal motion trajectories and the morphology of the electron beam spot on the working plane; Based on the collision model and the energy loss model, obtain the energy and power distribution of electrons hitting the powder bed under high-voltage acceleration, that is, obtain the heat source model; According to the heat source model, obtain the energy field distribution of the component, calculate the stress and plastic strain of a single layer and single pass of the structural component, and based on the energy field distribution of the single layer and single pass, obtain the overall stress deformation of the structural component.

2. The simulation method of the high-voltage multi-electron beam selective melting forming process according to claim 1, characterized in that, The high voltage is 120 kV.

3. The simulation method of the high-voltage multi-electron beam selective melting forming process according to claim 1, wherein, It includes the following specific steps: Step 1: Based on COMSOL Multiphysics, establish a high-voltage electron gun simulation model, including the cathode, anode, focusing coil, and deflection system, etc., simulate to obtain the electron trajectory and beam spot morphology, and output the spatio-temporal coordinate data.

4. The simulation method of the high-voltage multi-electron beam selective melting forming process according to claim 3, characterized in that, It also includes the following specific steps: Step 2: Simulate the mutual collision and absorption between electrons and the powder bed material through the Monte Carlo collision model, establish a high-energy electron energy loss model based on the Bethe-Bloch formula, and then establish a power density distribution model, and obtain the heat source model by fitting the equation.

5. The simulation method of the high-voltage multi-electron beam selective melting forming process according to claim 4, characterized in that It also includes the following specific steps: Step 3: Adopt the elastoplastic theory to establish a thermo-elasto-viscoplastic material constitutive model based on the deposition temperature range, use the established heat source model to calculate the temperature field and the local stress deformation field, and extract its plastic strain parameters.

6. The simulation method of the high-voltage multi-electron beam selective melting forming process according to claim 5, characterized in that, It also includes the following specific steps: Step 4: Based on the finite element birth and death element technology and the flash heating method, establish a thermo-mechanical behavior simulation model for the forming area of a single electron gun.

7. The simulation method of the high-voltage multi-electron beam selective melting forming process according to claim 6, characterized in that, It also includes the following specific steps: Step 5: According to the characteristics of multi-electron beam forming, adopt the steps of forming separately and splicing in segments to calculate the stress deformation of the overall part.