Method for constructing temperature field simulation model of aluminum steel electric arc welding-brazing workpiece

Abstract

The invention discloses a method for constructing a temperature field simulation model of an aluminum-steel arc welding-brazing workpiece, and relates to the technical field of welding machining.According to the method, aluminum metal and a steel substrate are modeled into solids, arc plasma in welding is modeled into fluid, meanwhile, an arc is modeled into an arc computational domain, and the temperature field simulation model of the aluminum-steel arc welding-brazing workpiece is obtained. The electric arc computational domain is set as a moving grid, and the moving grid can move along the modeled workpiece body and conduct heat transfer; then, in simulation software, energy and momentum source items representing the fluid flowing and fluid heat transfer process and the solid heat transfer process are added to the fluid and the solid, that is to say, welding parameters, namely the welding current, the welding speed and the shielding gas flow in the welding process, can be obtained in the heat transfer process of analogue simulation only by obtaining the welding parameters, namely the welding current, the welding speed and the shielding gas flow in the welding process. Heat transfer is directly simulated through a moving grid equivalent to an electric arc computational domain to calculate the electric arc temperature, the workpiece temperature and a welding thermal cycle curve of any point, and the experiment cost can be greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of welding processing, in particular to a construction method and device of an aluminum-steel arc fusion brazing workpiece temperature field simulation model, equipment and medium. BACKGROUND

[0002] Aluminum-steel arc fusion brazing is a welding method combining the characteristics of fusion welding and brazing. Based on the difference in melting points of aluminum alloy and steel, the welding heat input is precisely controlled to ensure that only aluminum is in a molten state while steel is not molten, and then the molten aluminum and solid steel / iron are combined together through metallurgical reaction, thereby realizing high-quality and high-strength metallurgical connection of aluminum and steel. Aluminum-steel arc fusion brazing is sensitive to welding parameters (such as welding current, welding speed, butt gap, arc position, welding gun angle, etc.), and small changes in parameters can cause significant changes in weld formation and joint performance. If a numerical model is used to simulate the temperature field changes of the workpiece during the entire welding process, the melting state of the aluminum-steel workpiece can be predicted, and then the joint performance can be predicted.

[0003] Most of the current aluminum-steel arc fusion brazing workpiece temperature field simulation models are models of workpieces, and the arc heat input is applied to the surface of the workpiece by using an analytical formula method, such as a Gaussian heat source or a double-ellipsoid heat source. However, some parameters in these analytical formulas are related to current and voltage, and these parameters need to be approximately determined in advance through welding experiments. Therefore, when simulating the aluminum-steel arc fusion brazing workpiece temperature field with different parameters, the accuracy is low, and it is difficult to perform high-precision simulation. SUMMARY

[0004] The construction method of the aluminum-steel arc fusion brazing workpiece temperature field simulation model provided by the embodiments of the present application can solve the problem of low accuracy in simulating the aluminum-steel arc fusion brazing workpiece temperature field with different parameters in the prior art, and high-precision simulation is difficult to perform.

[0005] The construction method of the aluminum-steel arc fusion brazing workpiece temperature field simulation model provided by the embodiments of the present application comprises the following steps: According to the geometric size of the aluminum-steel lap joint, a three-dimensional geometric model suitable for the aluminum-steel arc fusion brazing workpiece is constructed. The three-dimensional geometric model is imported into a simulation software to construct an aluminum-steel arc fusion brazing workpiece temperature field simulation model. The specific steps of constructing the aluminum-steel arc fusion brazing workpiece temperature field simulation model include: In the simulation software, the arc plasma in the aluminum-steel arc fusion brazing is set as a fluid, the aluminum metal and the steel substrate in the aluminum-steel arc fusion brazing are set as solids, and the arc in the aluminum-steel arc fusion brazing is set as a region containing high-temperature plasma to form an arc calculation domain, and the arc calculation domain is set as a moving mesh; wherein the moving mesh can move along the aluminum-steel welding direction, and the arc calculation domain and the workpiece domain formed by the solid can perform heat transfer in the movement; In the simulation software, the heat transfer and fluid flow state of the fluid are determined, and the heat transfer state of the solid is determined, the fluid energy and momentum source terms representing the fluid flow and the fluid heat transfer process through the moving mesh are added to the fluid, the solid energy and momentum source terms representing the solid heat transfer process through the moving mesh are added to the solid, and the boundary conditions and fluid physical property parameters of the fluid and the solid are set; wherein, based on the fluid energy and momentum source terms, the solid energy and momentum source terms, and the welding parameters in the welding process, the temperature field and heat of the arc calculation domain and the workpiece domain in the heat transfer between the arc calculation domain and the solid workpiece domain, and the temperature field in the welding process are obtained.

[0006] Preferably, the three-dimensional geometric model suitable for aluminum-steel arc fusion brazing is constructed, including: Obtain the physical properties of aluminum and steel at different temperatures, including thermal conductivity, specific heat capacity, density, thermal expansion coefficient, yield strength and elastic modulus; At the same time, the geometric size of the aluminum-steel lap joint is obtained, and a three-dimensional geometric model is constructed by using three-dimensional modeling software, which reflects the geometric characteristics of the thickness, overlap length, gap or pre-welding material shape of aluminum and steel.

[0007] Preferably, when simulating in the simulation software, the fluid and the solid also follow the conservation control equation, and the control equation includes: The mass conservation equation is expressed as: ; The energy conservation equation is expressed as: ; The momentum conservation equation is expressed as: ; Wherein: t represents time, T represents temperature; p , H , l , m density, enthalpy, thermal conductivity and viscosity, respectively; represents the velocity vector, p represents the pressure, represents the stress tensor; S represents the energy source term, represents the momentum source term.

[0008] Preferably, the fluid energy and momentum source terms characterizing the fluid flow and fluid heat transfer process through the moving mesh are added to the fluid, and the solid energy and momentum source terms characterizing the solid heat transfer process through the moving mesh are added to the solid, including: energy source term of the arc plasma S including Joule heat source term, electron migration heat transfer source term and radiation loss source term, represented as: ; energy source term between the welding wire and the arc plasma interface is represented as: ; energy source term between the arc plasma and the aluminum steel interface is represented as: ; wherein: represents the current density, represents the electrical conductivity, K B represents the Boltzmann constant, e represents the electron charge, S R represents the radiation loss, j a and j c respectively represent the current density in the anode sheath and the cathode sheath, V a and V c respectively represent the drop voltage of the anode sheath and the cathode sheath, f a and f c respectively represent the work function of the anode and the cathode, e a and e c respectively represent the emissivity of the anode material and the cathode material, α represents the Stefan-Boltzmann constant; the momentum source term of the arc plasma is represented as: ; wherein: represents the gravity of the arc plasma; represents the electromagnetic force of the arc plasma; the electromagnetic force of the arc plasma is represented as: ; wherein: B represents the self-induced magnetic flux density generated by the welding current; B represents the external magnetic flux density induced by the electromagnet; J represents the current density.

[0009] Preferably, the setting of the moving grid comprises: In the simulation software, the arc is set as a region containing high-temperature plasma, the region containing high-temperature plasma forms an arc calculation domain, and the arc calculation domain is set as a moving grid, the moving grid moves along the aluminum-steel welding direction, and the moving speed is the welding speed; When the arc calculation domain moves, the moving grid is meshed by Ansys Mesh; in the region far away from the arc, the temperature gradient and the fluid flow speed are small, and a large-size grid is used; in the region close to the arc, the high temperature and the high energy density cause the temperature gradient and the fluid flow speed of the region to be large, and then a small-size grid is selected; At the same time, the length-width ratio, the Jacobian ratio and the grid element quality of the grid element are checked by using the quality index command in Ansys Mesh.

[0010] Preferably, the setting of the boundary conditions and the fluid physical parameters of the fluid and the solid comprises: The boundary conditions comprise initial conditions, temperature field boundaries, momentum boundaries and electric field boundaries; The initial conditions are that when the initial moment t=0s when the arc starts to burn, the room temperature T0=300K, and the initial speed V=0.01 m / s of the grid; The temperature field boundary is that the temperature of the wire end is set to 2600K, the temperature of the workpiece is set to room temperature 300K, and the total temperature of the pressure outlet backflow is set to 700K; The momentum boundary is that the inlet of the shielding gas, that is, the lower end face of the actual MIG welding gun nozzle, has a radial flow speed of 0 and a longitudinal flow speed of: ; Wherein: Q Q is the shielding gas flow rate, R R is the outer radius of the shielding gas inlet, r r is the inner radius of the shielding gas inlet; The electric field boundary is that the electric field boundary of the anode is set according to the actual welding parameters, the z-direction current density is set at the wire end face, and the heat absorbed by the molten droplet in the unit heat input is represented as: ; The effective current for heating the arc is represented as: ; The effective current density of the wire end is represented as: ; wherein: C p Cp represents the specific heat capacity of the welding wire, p p represents the density of the welding wire, r 1 represents the radius of the welding wire, V f V represents the wire feed speed, Δ T represents the temperature difference, U represents the arc voltage, I represents the welding current, S represents the surface area of the welding wire end face; The cathode voltage is set to 0, the rest of the boundary is insulated, and the magnetic vector A The gradient at each boundary is 0. The fluid physical property parameters include viscosity, density, thermal fusion, radiation coefficient, thermal conductivity and electrical conductivity.

[0011] The embodiment of the present application also provides a construction device of an aluminum-steel arc fusion brazing workpiece temperature field simulation model, comprising: A three-dimensional geometric model construction module is configured to construct a three-dimensional geometric model suitable for aluminum-steel arc fusion brazing workpieces according to the geometric dimensions of the aluminum-steel lap joint. A simulation model construction module is configured to import the three-dimensional geometric model into simulation software and construct an aluminum-steel arc fusion brazing workpiece temperature field simulation model. In the simulation software, the arc plasma in the aluminum-steel arc fusion brazing is set as a fluid, the aluminum metal and the steel substrate in the aluminum-steel arc fusion brazing are set as solids, and the arc in the aluminum-steel arc fusion brazing is set as a region containing high-temperature plasma to form an arc calculation domain, and the arc calculation domain is set as a moving mesh; wherein the moving mesh can move along the aluminum-steel welding direction, and the arc calculation domain and the workpiece domain formed by the solid can perform heat transfer in the moving process. In the simulation software, the heat transfer and fluid flow state of the fluid are determined, and the heat transfer state of the solid is determined, fluid energy and momentum source terms representing fluid flow and fluid heat transfer process through the moving mesh are added to the fluid, solid energy and momentum source terms representing solid heat transfer process through the moving mesh are added to the solid, and the boundary conditions and fluid physical property parameters of the fluid and the solid are set; wherein, based on the fluid energy and momentum source terms, the solid energy and momentum source terms, and the welding parameters in the welding process, the temperature field and heat of the arc calculation domain and the workpiece domain in the heat transfer between the arc calculation domain and the solid workpiece domain, and the temperature field in the welding process are obtained.

[0012] The embodiment of the present application also provides an electronic device, comprising a memory and a processor; The memory is configured to store a computer program. The processor is used for realizing the steps of the construction method of the aluminum-steel electric arc fusion brazing workpiece temperature field simulation model when executing the computer program stored in the memory.

[0013] The embodiment of the present application further provides a computer readable storage medium for storing a computer program, and the computer program is executed by a processor to realize the steps of the construction method of the aluminum-steel electric arc fusion brazing workpiece temperature field simulation model.

[0014] The embodiment of the present application provides a construction method of an aluminum-steel electric arc fusion brazing workpiece temperature field simulation model, and the beneficial effects are as follows compared with the prior art. In the construction of the simulation model, not only the aluminum metal and the steel substrate are modeled as solids, but also the electric arc plasma in the welding is modeled as a fluid, and the electric arc is modeled as an electric arc calculation domain, and the electric arc calculation domain is set as a moving grid which can move along the modeled workpiece body and perform heat transfer; then in the simulation software, energy and momentum source terms are added to the fluid and the solid to characterize the fluid flow and the fluid heat transfer process and the solid heat transfer process, that is, only the welding parameters, i.e. the welding current, the welding speed and the protective gas flow in the welding process, are needed to directly simulate the heat transfer through the equivalent moving grid of the electric arc calculation domain in the simulation heat transfer process to calculate the electric arc temperature, the workpiece temperature and the welding thermal cycle curve of any point, and the experimental cost can be greatly reduced. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 A schematic diagram of the overall process of the construction method of the aluminum-steel electric arc fusion brazing workpiece temperature field simulation model is provided for the embodiment of the present application. Figure 2 A schematic diagram of the three-dimensional model of the magnetic control aluminum / steel electric arc fusion brazing lap joint of the construction method of the aluminum-steel electric arc fusion brazing workpiece temperature field simulation model is provided for the embodiment of the present application. Figure 3 A schematic diagram of the model cross-section of the magnetic control aluminum / steel electric arc fusion brazing lap joint of the construction method of the aluminum-steel electric arc fusion brazing workpiece temperature field simulation model is provided for the embodiment of the present application. Figure 4 A schematic diagram of the electric arc calculation domain of the construction method of the aluminum-steel electric arc fusion brazing workpiece temperature field simulation model is provided for the embodiment of the present application. Figure 5 A schematic diagram of the three-dimensional grid model after division of the magnetic control aluminum / steel electric arc fusion brazing lap joint of the construction method of the aluminum-steel electric arc fusion brazing workpiece temperature field simulation model is provided for the embodiment of the present application. Figure 6A viscosity diagram of pure argon at different temperatures of a construction method of an aluminum-steel electric arc brazing workpiece temperature field simulation model provided by the embodiment of the present application; Figure 7 A density diagram of pure argon at different temperatures of a construction method of an aluminum-steel electric arc brazing workpiece temperature field simulation model provided by the embodiment of the present application; Figure 8 A thermal melting diagram of pure argon at different temperatures of a construction method of an aluminum-steel electric arc brazing workpiece temperature field simulation model provided by the embodiment of the present application; Figure 9 A radiation coefficient diagram of pure argon at different temperatures of a construction method of an aluminum-steel electric arc brazing workpiece temperature field simulation model provided by the embodiment of the present application; Figure 10 A thermal conductivity diagram of pure argon at different temperatures of a construction method of an aluminum-steel electric arc brazing workpiece temperature field simulation model provided by the embodiment of the present application; Figure 11 An electrical conductivity diagram of pure argon at different temperatures of a construction method of an aluminum-steel electric arc brazing workpiece temperature field simulation model provided by the embodiment of the present application; Figure 12 An electric arc shape simulation diagram of a construction method of an aluminum-steel electric arc brazing workpiece temperature field simulation model provided by the embodiment of the present application; Figure 13 An electric arc plasma flow rate simulation diagram of a construction method of an aluminum-steel electric arc brazing workpiece temperature field simulation model provided by the embodiment of the present application; Figure 14 An aluminum / steel lap joint brazing temperature field evolution diagram of a construction method of an aluminum-steel electric arc brazing workpiece temperature field simulation model provided by the embodiment of the present application; Figure 15 A joint temperature cloud diagram of a construction method of an aluminum-steel electric arc brazing workpiece temperature field simulation model provided by the embodiment of the present application. DETAILED DESCRIPTION

[0016] In order to make the above objectives, features and advantages of the present application more apparent, specific embodiments of the present application are described in detail below with reference to the accompanying drawings. In the following description, a large number of specific details are set forth in order to provide a sufficient understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the scope of the present application, so the present application is not limited to the specific embodiments disclosed below.

[0017] Reference Figure 1The embodiment of the application provides a construction method of an aluminum-steel electric arc fusion brazing workpiece temperature field simulation model, in particular, an aluminum / steel electric arc fusion brazing electric arc-workpiece coupling numerical model, that is, not only the workpiece is modeled, but also the electric arc plasma is modeled; when the welding process parameters are given, the model constructed by the application can calculate the temperature field and heat of the entire electric arc, and the heat is transferred to the workpiece through a fluid-solid coupling model, and then the temperature field of the entire workpiece in the welding process is calculated; thus, by using the scheme, only the process parameters such as welding current, welding speed, and protective gas flow need to be known, and the electric arc temperature, workpiece temperature, and welding thermal cycle curve of any point can be calculated, and the experimental cost is greatly reduced.

[0018] Specifically, I. Simplified conditions.

[0019] In the aluminum / steel MIG electric arc fusion brazing process, the melting point of the base material is different, the heat input control has many influencing factors, and the welding arc is a complex plasma, and the flow and heat transfer process is very complex, the thermodynamic parameters are difficult to solve, and all factors are difficult to consider in numerical calculation; thus, based on the complexity of the aluminum / steel fusion brazing process, the following assumptions and simplifications are made to simplify the model, improve the calculation efficiency, and reduce the calculation cost: ①The initial temperature of the welding part is the same as the environmental temperature, and is set to 300K.

[0020] ②The flow of the entire fluid calculation domain belongs to a laminar state.

[0021] ③The thermodynamic and transport performance parameters of the plasma are temperature-dependent factors.

[0022] ④The plasma is optically thin, does not absorb radiation, and the effects of gravity and viscous dissipation are ignored.

[0023] ⑤The heat conduction between the test bench and the clamp, and the effect of the clamp on the welding part are not considered, and the evolution of the welding stress in the free state is simulated.

[0024] ⑥The lap gap of the intermetallic compound layer, the aluminum plate and the steel plate, and the influence of the aluminum alloy side pad on the temperature field and the stress and strain distribution are not considered.

[0025] ⑦The material is a homogeneous continuous medium, and is isotropic, and the physical property parameters change with temperature.

[0026] II. Control equation and source term.

[0027] In the model designed in the application, the electric arc plasma is regarded as a fluid, and the aluminum metal and the steel plate are regarded as solids; for the fluid, heat transfer and fluid flow are considered, and for the solid, only heat transfer is considered; the same conservation equation is solved in the entire calculation domain, but various energy and momentum source terms are added for different stages. The used conservation equation is as follows:

[0028] The mass conservation equation is: .

[0029] The energy conservation equation is: .

[0030] The momentum conservation equation is: .

[0031] Wherein: t represents time, T represents temperature; p , H , l , m respectively represent density, enthalpy, thermal conductivity and viscosity; represents the velocity vector, p represents the pressure, represents the stress tensor; S represents the energy source term, represents the momentum source term.

[0032] The energy source term of the arc plasma includes Joule heat, electron migration heat transfer and radiation loss, so the calculation formula of S is: .

[0033] There are anode / cathode sheath layers deviating from thermal dynamic equilibrium state at the welding wire-plasma interface and the plasma-workpiece interface; therefore, the present application adopts the “LTE-diffusion approximation” method proposed by Lowke et al., which simplifies the complex sheath thermal effect, and is applied to the energy source term of the welding wire-plasma interface S is represented as: .

[0034] In the plasma-workpiece interface, the energy source term S is represented as: .

[0035] Wherein: represents the current density, represents the electrical conductivity, K B represents the Boltzmann constant, e represents the electronic charge, S R represents the radiation loss, j a and j c respectively represent the current density in the anode sheath and the cathode sheath, V ​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​a and V c Vdown,anodeand Vdown,cathode represent the decreasing voltage of anode sheath and cathode sheath, respectively, f a and f c φanodeand φcathode represent the work function of anode and cathode, respectively, e a and e c εanodeand εcathode represent the emissivity of anode material and cathode material, respectively, α σ represents the Stefan-Boltzmann constant.

[0036] The source term of the additional momentum of the fluid region is expressed as: .

[0037] In the arc plasma, only the gravity and electromagnetic force are considered; the electromagnetic force is expressed as: .

[0038] where: Bself represents the self-induced magnetic flux density generated by the welding current, Bext represents the external magnetic flux density induced by the electromagnet.

[0039] The current continuity equation is: .

[0040] where: φ represents the electric potential.

[0041] According to Ohm's law, the current density can be obtained as: .

[0042] where: s σ represents the electrical conductivity of the fluid.

[0043] In the three-dimensional non-axisymmetric model, the magnetic vector potential method can be used to solve the magnetic induction intensity with known current density distribution. The magnetic vector potential equation is expressed as:

[0044] .

[0045] The magnetic induction intensity is: .

[0046] where: φ represents the electric potential; m 0 μ0 represents the vacuum permeability; It represents the magnetic vector potential.

[0047] III. Model Establishment.

[0048] This invention establishes a three-dimensional model suitable for aluminum / steel lap arc brazing, such as... Figure 2 and Figure 3 As shown; the joint workpiece is constructed by overlapping a 200mm×50mm×1mm aluminum alloy plate and a 200mm×50mm×2mm galvanized steel plate; the arc calculation area is a 20mm×20mm×19mm cube, as shown. Figure 4 As shown; the arc calculation domain is set as a moving grid, that is, the arc domain moves along the welding direction, and the moving speed is the welding speed.

[0049] In numerical simulations, the number of grid cells directly impacts computational efficiency. Too many grid cells may cause errors or even crashes during computation, while too few may compromise accuracy. Therefore, it is crucial to consider the impact of grid cell number on computational accuracy while ensuring efficient computation to meet accuracy requirements. The number of elements in the model of this invention is shown in Table 1, ensuring both computational accuracy and high efficiency.

[0050] Table 1 Number of Model Nodes and Elements The mesh density plays a crucial role in the computational efficiency and accuracy of the model. By appropriately controlling the mesh density, both computational efficiency and accuracy can be improved. A denser mesh is used in the main stress-bearing areas of the model to ensure more accurate calculation results in these critical regions. In non-critical areas, a relatively sparse mesh is used to reduce the computational burden and improve efficiency. This invention imports the established 3D model into Ansys Workbench and uses Ansys Mesh for mesh generation. When simulating the temperature field, due to the extremely high and drastic temperature changes in the arc region, a fine mesh is used to obtain more accurate temperature gradient data. Simultaneously, a local mesh refinement method is employed to balance computational efficiency. Larger mesh sizes are selected in areas far from the arc to reduce computational load and increase calculation speed, while smaller mesh sizes are used in areas close to the arc. For the simulation of the stress-strain field, since the stress is located in the plate, the mesh size, although slightly larger than that in the arc region, is still considered fine. Based on the above analysis, the resulting mesh model is as follows: Figure 5 As shown, there are a total of 415,177 nodes and 209,001 cells.

[0051] After the mesh is completed, it is essential to evaluate the rationality of the mesh geometry; the mesh quality has an important influence on the calculation accuracy, so it must be ensured to meet certain standards; when evaluating the mesh quality, the main indicators are the aspect ratio of the unit, the Jacobian ratio, and the unit quality; through the quality index command in Ansys Mesh to check multiple indicators in the mesh.

[0052] Four, boundary conditions and fluid physical parameters.

[0053] 1. Boundary conditions.

[0054] ① Initial conditions: At the initial moment t = 0 s when the electric arc starts to burn, the room temperature T0 = 300 K, and the initial velocity of the grid V = 0.01 m / s.

[0055] ② Temperature field boundary: The temperature of the wire end is set to 2600 K; the temperature of the workpiece is set to room temperature 300 K; the total temperature of the pressure outlet backflow is set to 700 K.

[0056] ③ Momentum boundary: The inlet of the protective gas, which is the lower end surface of the actual MIG welding gun nozzle, has a radial flow velocity of 0 and a longitudinal flow velocity of: .

[0057] Where: Q is the protective gas flow rate, R is the outer radius of the protective gas inlet, r is the inner radius of the protective gas inlet.

[0058] The protective gas outlet is a one-way pressure outlet, and the relative pressure is set to 0.

[0059] ④ Electric field boundary: The electric field boundary of the anode is set according to the actual welding parameters, and the z-direction current density is set at the wire end surface; the heat absorbed by the molten droplet in the unit heat input is represented as: .

[0060] The effective current for heating the electric arc is represented as: .

[0061] Then the effective current density at the wire end is represented as: .

[0062] Where: C p represents the specific heat capacity of the wire, p represents the density of the wire, r1 represents the radius of the welding wire, V f represents the wire feed speed, Δ T represents the temperature difference, U represents the arc voltage, I represents the welding current, S represents the surface area of the welding wire end face.

[0063] The cathode voltage is set to 0; the rest of the boundaries are insulated; the magnetic vector A The gradient at each boundary is 0; the boundary conditions of the arc model are shown in Table 2.

[0064] Table 2 Boundary conditions of the arc model 2, fluid physical parameters.

[0065] It is assumed that the physical parameters of argon plasma are only related to temperature; the values of the thermal physical parameters, transport coefficients and radiation coefficients of pure argon at different temperatures are all from literature, and the specific values are shown in Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 and Figure 11 .

[0066] The simulated arc shape diagram is shown in Figure 12 ; the simulated arc plasma flow rate is shown in Figure 13 ; the temperature field evolution of the aluminum / steel lap joint brazing is shown in Figure 14 ; the simulated joint temperature cloud map is shown in Figure 15 .

[0067] The above-described embodiments only express several embodiments of the present application, and the description is more specific and detailed, but it should not be understood as limiting the scope of the patent. It should be noted that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the scope of protection of the present application patent should be subject to the appended claims.

Claims

1. A method for constructing a simulation model of the temperature field of an aluminum-steel electric arc brazing workpiece, characterized in that, Includes the following steps: Based on the geometric dimensions of the lap joint of aluminum and steel, a three-dimensional geometric model suitable for aluminum-steel arc welding workpieces is constructed. Importing the three-dimensional geometric model into simulation software, a temperature field simulation model of the aluminum-steel electric arc brazing workpiece is constructed; the specific steps for constructing the temperature field simulation model of the aluminum-steel electric arc brazing workpiece include: In the simulation software, the arc plasma in aluminum-steel arc fusion brazing is treated as a fluid, the aluminum metal and steel substrate in aluminum-steel arc fusion brazing are treated as solids, and the arc in aluminum-steel arc fusion brazing is treated as a region containing high-temperature plasma to form an arc calculation domain, and the arc calculation domain is treated as a moving mesh; wherein, the moving mesh can move along the aluminum-steel welding direction, and heat can be transferred between the arc calculation domain and the workpiece domain formed by the solid during the movement; In the simulation software, the heat transfer and flow state of the fluid and the heat transfer state of the solid are determined. Fluid energy and momentum source terms characterizing the fluid flow and the heat transfer process through the moving mesh are added to the fluid, and solid energy and momentum source terms characterizing the heat transfer process through the moving mesh are added to the solid. Boundary conditions and fluid property parameters are set for the fluid and solid. Based on the fluid energy and momentum source terms, solid energy and momentum source terms, and welding parameters in the welding process, the temperature field and heat in the arc calculation domain and the workpiece domain during heat transfer, as well as the temperature field during the welding process, are obtained.

2. The method for constructing a temperature field simulation model for aluminum-steel electric arc brazing workpiece according to claim 1, characterized in that, The construction of a three-dimensional geometric model suitable for aluminum-steel arc welding includes: The physical properties of aluminum and steel at different temperatures were obtained, including thermal conductivity, specific heat capacity, density, coefficient of thermal expansion, yield strength, and elastic modulus. Simultaneously, the geometric dimensions of the aluminum-steel lap joint are obtained, and a three-dimensional geometric model is constructed using three-dimensional modeling software. The three-dimensional geometric model reflects the geometric characteristics of the aluminum and steel thickness, lap length, gap, or pre-set welding material shape.

3. The method for constructing a temperature field simulation model of an aluminum-steel arc-welded workpiece according to claim 1, characterized in that, When the simulation is performed in the simulation software, the fluid and solid also follow the conservation control equations, which include: The mass conservation equation is expressed as: ； The energy conservation equation is expressed as: ； The momentum conservation equation is expressed as: ； in: t Indicates time, T Indicates temperature; ρ , H , λ , μ These represent density, enthalpy, thermal conductivity, and viscosity, respectively. Represents the velocity vector. p Indicates pressure, Represents the stress tensor; S Represents the energy source term. This represents the momentum source term.

4. The method for constructing a temperature field simulation model of an aluminum-steel electric arc brazing workpiece according to claim 3, characterized in that, The addition of fluid energy and momentum source terms characterizing fluid flow and heat transfer through a moving grid to the fluid, and the addition of solid energy and momentum source terms characterizing heat transfer through a moving grid to the solid, include: Energy source term of electric arc plasma S Including the Joule heat source term, the electron migration heat transfer term, and the radiation loss term, it is represented as: ； The energy source term at the interface between the welding wire and the electric arc plasma is represented as: ； The energy source term between the arc plasma and the aluminum-steel interface is represented as: ； in: Indicates current density, Indicates electrical conductivity. K B Represents Boltzmann's constant. e Represents electron charge, S R Indicates radiation loss. j a and j c These represent the current densities in the anode sheath and cathode sheath, respectively. V a and V c These represent the voltage drops at the anode and cathode sheaths, respectively. φ a and φ c These represent the operating functions of the anode and cathode, respectively. ε a and ε c These represent the emissivity of the anode and cathode materials, respectively. α This represents the Stefan-Boltzmann constant; The momentum source term of the electric arc plasma is expressed as: ； in: Represents the gravity of the electric arc plasma; The electromagnetic force representing the electric arc plasma; The electromagnetic force of an electric arc plasma is represented as: ； in: This represents the self-induced magnetic flux density generated by the welding current. This represents the external magnetic flux density induced by an electromagnet. This represents the current density.

5. The method for constructing a temperature field simulation model of an aluminum-steel arc-welded workpiece according to claim 1, characterized in that, The settings for the moving grid include: In the simulation software, the electric arc is set as a region containing high-temperature plasma, and the region containing high-temperature plasma forms the electric arc calculation domain. The electric arc calculation domain is set as a moving mesh, and the moving mesh moves along the aluminum-steel welding direction at the welding speed. When moving within the electric arc computational domain, Ansys Mesh is used to generate the moving mesh. In regions far from the electric arc, where the temperature gradient and fluid flow velocity are small, a large mesh is used. In regions close to the electric arc, where the high temperature and high energy density result in a large temperature gradient and fluid flow velocity, a small mesh is selected. At the same time, use the quality index command in Ansys Mesh to check the aspect ratio, Jacobian ratio, and mesh cell quality of the mesh cells.

6. The method for constructing a temperature field simulation model of an aluminum-steel electric arc brazing workpiece according to claim 1, characterized in that, The setting of boundary conditions and fluid property parameters for fluid and solid includes: The boundary conditions include initial conditions, temperature field boundaries, momentum boundaries, and electric field boundaries; The initial conditions are: at the initial moment when the electric arc starts to burn, t=0s, the room temperature T0=300K, and the initial velocity of the grid V=0.01 m / s; The temperature field boundaries are as follows: the welding wire tip temperature is set to 2600K; the workpiece temperature is set to room temperature 300K; and the total reflow temperature at the pressure outlet is set to 700K. The momentum boundary is defined as follows: the inlet of the shielding gas, i.e., the lower end face of the actual MIG welding torch nozzle, has a radial flow velocity of 0 and a longitudinal flow velocity of: ； in: Q To protect the airflow, R To protect the outer radius of the air inlet, r To protect the inner radius of the air inlet; The electric field boundary is defined as follows: the electric field boundary of the anode is set according to the actual welding parameters, and the z-direction current density is set at the end face of the welding wire; the heat absorbed by the molten droplet per unit heat input is expressed as: ； The effective current used to heat the electric arc is expressed as: ； The effective current density at the end of the welding wire is expressed as: ； in: C p This indicates the specific heat capacity of the welding wire. ρ This indicates the density of the welding wire. r 1 indicates the radius of the welding wire. V f Indicates the wire feeding speed, Δ T Indicates temperature difference. U Indicates arc voltage. I Indicates welding current. S This indicates the surface area of ​​the welding wire end face; The cathode voltage is set to 0, the remaining boundaries are insulated, and the magnetic vector... A The gradient is 0 at each boundary; Fluid properties include viscosity, density, heat flux, radiation coefficient, thermal conductivity, and electrical conductivity.

7. A device for constructing a simulation model of the temperature field of an aluminum-steel electric arc welding workpiece, characterized in that, include: The 3D geometry model building module is used to build a 3D geometry model suitable for aluminum-steel arc welding workpieces based on the geometric dimensions of the lap joint of aluminum and steel. The simulation model construction module imports the three-dimensional geometric model into the simulation software to construct a simulation model of the temperature field of the aluminum-steel electric arc brazing workpiece; the specific steps for constructing the simulation model of the temperature field of the aluminum-steel electric arc brazing workpiece include: In the simulation software, the arc plasma in aluminum-steel arc fusion brazing is treated as a fluid, the aluminum metal and steel substrate in aluminum-steel arc fusion brazing are treated as solids, and the arc in aluminum-steel arc fusion brazing is treated as a region containing high-temperature plasma to form an arc calculation domain, and the arc calculation domain is treated as a moving mesh; wherein, the moving mesh can move along the aluminum-steel welding direction, and heat can be transferred between the arc calculation domain and the workpiece domain formed by the solid during the movement; In the simulation software, the heat transfer and flow state of the fluid and the heat transfer state of the solid are determined. Fluid energy and momentum source terms characterizing the fluid flow and the heat transfer process through the moving mesh are added to the fluid, and solid energy and momentum source terms characterizing the heat transfer process through the moving mesh are added to the solid. Boundary conditions and fluid property parameters are set for the fluid and solid. Based on the fluid energy and momentum source terms, solid energy and momentum source terms, and welding parameters in the welding process, the temperature field and heat in the arc calculation domain and the workpiece domain during heat transfer, as well as the temperature field during the welding process, are obtained.

8. An electronic device, characterized in that, include: Memory and processor; The memory is used to store computer programs; When the processor executes the computer program stored in the memory, it implements the steps of the method for constructing a temperature field simulation model of an aluminum-steel electric arc welding workpiece as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, Used to store a computer program, which, when executed by a processor, implements the steps of a method for constructing a temperature field simulation model of an aluminum-steel electric arc welding workpiece as described in any one of claims 1 to 6.

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