Dual-sided laser synchronous welding heat source model establishment method, dual-sided laser synchronous welding heat source simulation method, dual-sided laser synchronous welding system, and medium

Abstract

Disclosed in the present application are a dual-sided laser synchronous welding heat source model establishment method, a dual-sided laser synchronous welding heat source simulation method, a dual-sided laser synchronous welding system, and a medium. Firstly, combined heat sources each comprising a Gaussian cylindrical heat source attenuation model and a Gaussian surface heat source correction model are established, and a dual-sided laser synchronous welding heat source model is established by means of a rotating coordinate system; a three-dimensional geometric model and a three-dimensional mesh model of a T-joint are established; and the consistency between simulated molten metal morphology and an actual weld shape is used as a criterion for determining whether parameter settings of the dual-sided laser synchronous welding heat source model are rational, so as to obtain an optimal finite element simulation heat source model. By establishing two heat sources each obtained by combining a Gaussian cylindrical heat source attenuation model and a Gaussian surface heat source correction model, and symmetrically applying the two heat sources to two sides of a T-joint to act on the interior and surface of a weld, the present invention realizes the accurate simulation of a weld penetration zone in a T-shaped thin-plate weldment, and thus enables the prediction of residual stress and welding deformation during a design phase, thereby optimizing the welding process, improving the welding quality and efficiency, and reducing material waste and production costs.

Description

Modeling, simulation methods, systems, and media for dual-sided laser synchronous welding heat source Technical Field

[0001] This invention relates to the field of laser welding technology, and in particular to a model establishment, simulation method, system and medium for dual-sided laser synchronous welding heat source. Background Technology

[0002] Laser welding technology boasts advantages such as high precision, high speed, minimal welding deformation, excellent joint mechanical properties, and high automation, making it widely used in welding processes across various industries. T-joint double-sided laser synchronous welding technology, as an emerging laser welding technology, has already been deployed on the fuselage panels of the European Airbus A350 / A380 and the domestically produced C919 passenger aircraft. This technology is expected to be applied in the manufacturing of new energy vehicles and the assembly of power battery pack structures in the future. Compared to traditional riveting processes, double-sided laser synchronous welding technology requires less manufacturing time than mechanical fastener assembly, reducing manufacturing costs and improving production efficiency. Simultaneously, the absence of rivets and sealants reduces structural weight, ultimately lowering transportation costs. Compared to T-joint double-sided laser asynchronous welding technology, double-sided laser synchronous welding technology exhibits less welding deformation, more uniform microstructure, and a lower tendency for porosity and cracking. Generally, structural components are complex in shape and expensive. Conducting multiple physical tests in practice would lengthen the testing cycle and significantly increase testing costs, severely impacting the production and manufacturing of structural components. Using finite element simulation to replace unnecessary physical experiments in the early stages can effectively save a lot of manpower, material resources and financial resources, and shorten the product development cycle. In the later stage of structural optimization design, it can reduce the blindness and repetition of actual experiments, save manufacturing costs and improve product competitiveness.

[0003] The core of finite element simulation of laser welding is establishing a reasonable heat source model, which directly affects the accuracy and reliability of the simulation results. Double-sided laser synchronous welding technology applies laser heat sources to both sides of a T-joint, thereby achieving mutual penetration of the molten metal on both sides of the T-joint. Chinese patent applications CN103049623A, CN110866359A, CN103761374A, CN109829200A, and CN111680442A disclose techniques for finite element simulation of flat plate welding processes using heat source models such as double ellipsoidal heat source models, Gaussian cylinder heat source models, Gaussian surface heat source models, and conical heat source models, or combinations of several of these heat source models. However, the morphology of the continuous molten metal in a T-joint is difficult to obtain directly using the aforementioned heat source models. Therefore, to achieve finite element simulation of the double-sided laser synchronous welding process, a suitable welding heat source model must be established.

[0004] Chinese patent application CN 102708237 B discloses a simulation method for the molten pool flow field in simultaneous double-laser-beam welding of T-joints, particularly for the combined molten pool formed during simultaneous double-sided welding of T-structures. The steps include establishing a three-dimensional temperature and flow field model of the combined molten pool, controlling the flow field model through equations, and solving the governing equations using CFD (Computational Fluid Dynamics) software to obtain the results. This invention provides a simulation method for the molten pool flow field in simultaneous double-laser-beam welding of T-joints, establishing a molten pool flow field model under the combined action of two laser beams, while considering the effects of fluid-solid phase transformation during welding. Accurate dynamic flow field details are obtained by solving the flow field model, and the calculated results agree well with experimental results. While this patent's simulation method can well interpret the liquid molten pool flow phenomenon, it cannot solve the simulation problems of welding deformation and residual stress in laser welding of T-joints through rapid modeling. Summary of the Invention

[0005] 1. Technical problems to be solved

[0006] To address the issue that existing liquid molten pool flow simulation methods cannot solve the problem of simulating welding deformation and residual stress in T-joint laser welding, this invention provides a method for establishing a heat source model for dual-sided laser synchronous welding. This method not only achieves accurate simulation of the weld penetration zone of T-shaped thin plate weldments, but also enables the prediction of residual stress and welding deformation through rapid modeling during the design phase.

[0007] 2. Technical Solution

[0008] The objective of this invention is achieved through the following technical solutions.

[0009] In a first aspect, the present invention provides a dual-sided laser synchronous welding heat source model, wherein two laser heat sources are symmetrically applied to both sides of a T-joint, and each laser heat source is a combination of a Gaussian column heat source attenuation model and a Gaussian surface heat source correction model; in the combination heat source, the Gaussian column heat source attenuation model acts on the internal region of the weld on both sides of the T-joint, and the Gaussian surface heat source correction model acts on the surface region of the weld on both sides of the T-joint.

[0010] A second aspect of the present invention provides a method for establishing a heat source model for dual-sided laser synchronous welding, used to establish a heat source model for dual-sided laser synchronous welding as described in the first aspect of the present invention. The method steps are as follows:

[0011] Step 100: Establish a heat source model for dual-sided laser synchronous welding;

[0012] The model uses two laser heat sources symmetrically applied to both sides of the T-joint. Each laser heat source is a combination of a Gaussian column heat source attenuation model and a Gaussian surface heat source correction model. In the combination heat source, the Gaussian column heat source attenuation model acts on the internal area of ​​the weld on both sides of the T-joint, and the Gaussian surface heat source correction model acts on the surface area of ​​the weld on both sides of the T-joint.

[0013] The governing equations for the attenuation model of each Gaussian column heat source are shown in Equation (1):

[0014] q v (x, y, z, t) represents the heat flux density function of the Gaussian column heat source on the workpiece weld, (x, y, z) represents the coordinates of the global coordinate system, t represents the welding time, α represents the laser power distribution coefficient, Q represents the total laser power, H represents the effective heating depth of the volume heat source, and r v The effective heating radius of the heat source represents the volumetric heat source, and v represents the welding speed. The two Gaussian column heat source attenuation model represents a moving heat source moving along the x-axis and an attenuation model along the z-axis.

[0015] The governing equations for each Gaussian surface heat source correction model are shown in equation (2):

[0016] q s (x, y, t) represents the heat flux density function of the Gaussian surface heat source on the workpiece surface, (x, y) represents the coordinates in the global coordinate system, t represents the welding time, α represents the laser power distribution coefficient, β represents the heat flux concentration coefficient, Q represents the total laser power, and r s The effective heating radius of the surface heat source is represented by , and v represents the welding speed. The two Gaussian surface heat source correction models are moving heat sources that move along the x-axis.

[0017] Two laser heat sources are symmetrically applied to both sides of the T-joint. The two laser heat sources simultaneously weld the welding position at an angle θ, where θ is the angle between the beam and the stiffener. A rotating coordinate system is established, and the governing equations are shown in formulas (3)-(6): y1=(y-y0)cosθ+(z-z0)sinθ (3) z1=(z-z0)cosθ-(y-y0)sinθ (4) y2=(y-y0)cosθ-(z-z0)sinθ (5) z2=(z-z0)cosθ+(y-y0)sinθ (6)

[0018] (x, y, z) represent the coordinates of the global coordinate system before the transformation, (x0, y0, z0) represent the absolute coordinates relative to the origin O of the coordinate system, (x1, y1, z1) represent the coordinates after the rotation by an angle θ, (x2, y2, z2) represent the coordinates after the rotation by an angle -θ, x1 = x - x0, x2 = x - x0.

[0019] Substituting (x1, y1, z1) and (x2, y2, z2) into equations (1) and (2) respectively, the total heat flux density function applied to both sides of the T-joint is finally obtained, and the governing equation is shown in equation (7): q Total (x,y,z,t)=q v1 (x,y,z,t)+q v2 (x,y,z,t)+q s1 (x,y,t)+q s2 (x,y,t) (7)

[0020] q Total (x, y, z, t) represents the total heat flux density function applied to both sides of the T-joint; q v1 (x, y, z, t) is obtained by substituting (x1, y1, z1) into formula (1), q v2 (x, y, z, t) is obtained by substituting (x², y², z²) into formula (1), q v1 (x, y, z, t) and q v2 (x, y, z, t) represents the heat flux density function of the two symmetrically distributed laser Gaussian column heat sources on both sides of the T-joint inside the weld seam of the workpiece; q s1 (x, y, t) is obtained by substituting (x1, y1, z1) into formula (2), q s2 (x, y, t) is obtained by substituting (x2, y2, z2) into formula (2), q s1 (x, y, t) and q s2 (x, y, t) represents the heat flux density function of two laser Gaussian surface heat sources symmetrically distributed on both sides of the T-joint on the surface of the workpiece weld.

[0021] Preferably, the control equations (1)-(7) are compiled using FORTRAN language compilation software to write FORTRAN language code programs for the dual-sided laser synchronous welding heat source model.

[0022] Step 200: Establish a three-dimensional finite element model of the T-joint;

[0023] In the same coordinate system as in step 100, a three-dimensional geometric model of the T-joint is established. The mesh is generated using mesh generation software or finite element calculation software with built-in mesh generation function to obtain a three-dimensional mesh model of the T-joint.

[0024] Step 300: Solve the governing equations using finite element method software and perform thermo-mechanical coupling calculations;

[0025] The three-dimensional partial differential equation for heat conduction in a solid with a heat source and a transient temperature field is established as shown in equation (8):

[0026] T represents the transient temperature of the workpiece, t represents the welding and cooling time, k represents the thermal conductivity of the material, ρ represents the material density, and c p q represents the specific heat of the material. Total (x, y, z, t) represents the total heat flux density function applied to both sides of the T-joint as shown in formula (7), and (x, y, z) are the coordinates of the global coordinate system.

[0027] Based on finite element method (FEM) software, the established dual-sided laser synchronous welding heat source model was loaded onto a three-dimensional mesh model. The heat source control position and workpiece loading boundary conditions were set, and the calculation was submitted and solved to obtain welding temperature field and weld cross-sectional morphology data. The laser parameters were adjusted to verify the rationality of the dual-sided laser synchronous welding heat source model parameter settings by comparing the simulated molten metal morphology with the actual weld shape, and the optimized laser parameters were obtained. Using the optimized laser parameters, the welding deformation and residual stress data of the workpiece were obtained. The dual-sided laser synchronous welding heat source model was then established.

[0028] The optimized dual-sided laser synchronous welding heat source model can be directly applied to the simulation of welding deformation and residual stress of large structural components, and the welding process of large structural components can be optimized by adjusting the welding sequence.

[0029] The names of the steps above do not restrict the specific execution order of the method steps.

[0030] In a third aspect, the present invention provides a simulation method for a dual-sided laser synchronous welding heat source. The method uses the dual-sided laser synchronous welding heat source model of the first aspect of the present invention to simulate the welding process of weldable thin sheet metal materials and obtain simulation data of welding deformation and residual stress. The thickness of the thin sheet metal material is in the range of 2mm-5mm.

[0031] A fourth aspect of the present invention provides a dual-sided laser synchronous welding system, comprising a laser, a laser fiber, a welding head, a computing unit, and a control unit, wherein:

[0032] Two lasers are used to generate dual-sided lasers, which are then directed into the welding head via dual-sided laser fibers.

[0033] The welding head is used to focus the laser beam onto the desired welding location;

[0034] The computing unit includes a memory, a processor, and a communication bus; the communication bus enables communication between the processor and the memory, and the processor executes one or more programs stored in the memory; the computing unit is used for finite element simulation calculations and process optimization, and feeds back the simulation results to the control unit;

[0035] The control unit uses the optimized laser parameters in the computing unit to realize the laser welding process, thereby running the method for establishing a dual-sided laser synchronous welding heat source model according to the second aspect of the present invention.

[0036] In a fifth aspect, the present invention provides a computer-readable storage medium storing one or more programs, which can be executed by one or more processors to run a method for establishing a dual-sided laser synchronous welding heat source model provided in the second aspect of the present invention.

[0037] 3. Beneficial effects

[0038] Compared with existing technologies, the advantages of this invention are as follows: This invention establishes a novel dual-sided laser synchronous welding heat source model, using two laser heat sources placed on both sides of the T-joint. Each heat source is a combination of a Gaussian column heat source attenuation model and a Gaussian surface heat source correction model, acting on the inside and surface of the weld, realizing accurate simulation of the weld penetration zone of the T-shaped thin plate weldment. It completes the prediction of residual stress and welding deformation in the design stage, optimizes the welding process, improves welding quality and efficiency, and reduces material waste and production costs. Attached Figure Description

[0039] Figure 1 is a schematic diagram of the combined heat source of the Gaussian column heat source attenuation model and the Gaussian surface heat source correction model established in this invention.

[0040] Figure 2 is a schematic diagram of the dual-sided laser synchronous welding heat source model established in this invention;

[0041] Figure 3 is a schematic diagram of the finite element model mesh generation of the T-type joint of the present invention;

[0042] Figure 4 shows the morphology of the molten metal through the simulated T-joint obtained by the method of the present invention;

[0043] Figure 5 shows a comparison between the simulated molten metal morphology obtained by the method of the present invention and the cross-sectional morphology of the weld in the example test.

[0044] Figure 6 shows the simulated welding deformation field of the T-joint obtained by the method of the present invention;

[0045] Figure 7 shows the simulation results of the T-joint angle deformation obtained by the method of the present invention;

[0046] Figure 8 shows the simulated residual stress field of the T-joint obtained by the method of the present invention. Detailed Implementation

[0047] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The technical solutions in the embodiments of the present invention will be described in detail below with reference to the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments proposed by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0048] Example 1

[0049] In a first aspect, embodiments of the present invention provide a dual-sided laser synchronous welding heat source model. As shown in Figure 2, the model employs two laser heat sources symmetrically applied to both sides of a T-joint. Each laser heat source is a combination of a Gaussian column heat source attenuation model and a Gaussian surface heat source correction model. In the combined heat source, the Gaussian column heat source attenuation model acts on the internal region of the weld on both sides of the T-joint, while the Gaussian surface heat source correction model acts on the surface region of the weld on both sides of the T-joint.

[0050] Example 2

[0051] A second aspect of the present invention provides a method for establishing a heat source model for dual-sided laser synchronous welding, used to establish a heat source model for dual-sided laser synchronous welding according to the first aspect of the present invention, which is achieved through the following steps:

[0052] Step 100: Establish a heat source model for dual-sided laser synchronous welding;

[0053] The model uses two laser heat sources symmetrically applied to both sides of the T-joint. Each laser heat source is a combination of a Gaussian column heat source attenuation model and a Gaussian surface heat source correction model, as shown in Figure 1. In the combined heat source, the Gaussian column heat source attenuation model acts on the internal region of the weld on both sides of the T-joint, and the Gaussian surface heat source correction model acts on the surface region of the weld on both sides of the T-joint, as shown in Figure 2. Based on FORTRAN language, a combined heat source model was developed, in which the governing equation of each Gaussian column heat source attenuation model is shown in Equation (1):

[0054] q v (x, y, z, t) represents the heat flux density function of the Gaussian column heat source on the workpiece weld, (x, y, z) represents the coordinates of the global coordinate system, t represents the welding time, α represents the laser power distribution coefficient, Q represents the total laser power, H represents the effective heating depth of the volume heat source, and r v The effective heating radius of the heat source represents the volumetric heat source, and v represents the welding speed. The two Gaussian column heat source attenuation model represents a moving heat source moving along the x-axis and an attenuation model along the z-axis.

[0055] The governing equations for each Gaussian surface heat source correction model are shown in equation (2):

[0056] q s (x, y, t) represents the heat flux density function of the Gaussian surface heat source on the workpiece surface, (x, y) represents the coordinates in the global coordinate system, t represents the welding time, α represents the laser power distribution coefficient, β represents the heat flux concentration coefficient, Q represents the total laser power, and r s The effective heating radius of the surface heat source is represented by , and v represents the welding speed. The two Gaussian surface heat source correction models are moving heat sources that move along the x-axis.

[0057] Two laser heat sources are symmetrically applied to both sides of the T-joint. The two laser heat sources simultaneously weld the welding position at an angle θ, where θ is the angle between the beam and the stiffener. A rotating coordinate system is established, and the governing equations are shown in formulas (3)-(6): y1=(y-y0)cosθ+(z-z0)sinθ (3) z1=(z-z0)cosθ-(y-y0)sinθ (4) y2=(y-y0)cosθ-(z-z0)sinθ (5) z2=(z-z0)cosθ+(y-y0)sinθ (6)

[0058] In the formula, (x, y, z) represents the coordinates of the global coordinate system before the transformation, (x0, y0, z0) represents the absolute coordinates relative to the origin O of the coordinate system, (x1, y1, z1) represents the coordinates after rotation by an angle θ, (x2, y2, z2) represents the coordinates after rotation by an angle -θ, and x1 = x - x0, x2 = x - x0.

[0059] Substituting (x1, y1, z1) and (x2, y2, z2) into equations (1) and (2) respectively, the total heat flux density function applied to both sides of the T-joint is finally obtained, and the governing equation is shown in equation (7): q Total (x,y,z,t)=q v1 (x,y,z,t)+q v2 (x,y,z,t)+q s1 (x,y,t)+q s2 (x,y,t) (7)

[0060] q Total (x, y, z, t) represents the total heat flux density function applied to both sides of the T-joint; q v1 (x, y, z, t) is obtained by substituting (x1, y1, z1) into formula (1), q v2 (x, y, z, t) is obtained by substituting (x², y², z²) into formula (1), q v1 (x, y, z, t) and qv2 (x, y, z, t) represents the heat flux density function of the two symmetrically distributed laser Gaussian column heat sources on both sides of the T-joint inside the weld seam of the workpiece; q s1 (x, y, t) is obtained by substituting (x1, y1, z1) into formula (2), q s2 (x, y, t) is obtained by substituting (x2, y2, z2) into formula (2), q s1 (x, y, t) and q s2 (x, y, t) represents the heat flux density function of two laser Gaussian surface heat sources symmetrically distributed on both sides of the T-joint on the surface of the workpiece weld.

[0061] Preferably, the control equations (1)-(7) are compiled using FORTRAN language compilation software to write FORTRAN language code programs for the dual-sided laser synchronous welding heat source model.

[0062] Step 200: Establish a three-dimensional finite element model of the T-joint;

[0063] In the same coordinate system as in step 100, a three-dimensional geometric model of the T-joint is established. The mesh is generated using mesh generation software or finite element calculation software with built-in mesh generation function to obtain a three-dimensional mesh model of the T-joint, as shown in Figure 3.

[0064] Step 300: Solve the governing equations using finite element method software and perform thermo-mechanical coupling calculations.

[0065] The three-dimensional partial differential equation for heat conduction in a solid with a heat source and a transient temperature field is established as shown in equation (8):

[0066] T represents the transient temperature of the workpiece, t represents the welding and cooling time, k represents the thermal conductivity of the material, ρ represents the material density, and c p q represents the specific heat of the material. Total (x, y, z, t) represents the total heat flux density function applied to both sides of the T-joint as shown in formula (7), and (x, y, z) are the coordinates of the global coordinate system.

[0067] Based on finite element method (FEM) software, the established dual-sided laser synchronous welding heat source model was loaded onto a 3D mesh model. The heat source control position and workpiece loading boundary conditions were set, and the calculation was submitted and solved to obtain the welding temperature field and weld cross-sectional morphology. By adjusting the laser parameters, the degree of agreement between the simulated molten metal morphology and the actual weld shape was used as the standard for determining the rationality of the dual-sided laser synchronous welding heat source model parameter settings. Using the optimized laser parameters, the welding deformation and residual stress of the workpiece were obtained. The optimized dual-sided laser synchronous welding heat source model can be directly applied to the simulation of welding deformation and residual stress of large structural components. The welding process of large structural components can be optimized by adjusting the welding sequence.

[0068] The names of the steps above do not restrict the specific order in which they are executed.

[0069] Example 3

[0070] In a third aspect, the present invention provides a simulation method for a dual-sided laser synchronous welding heat source, which simulates the welding process of weldable thin sheet metal materials, including but not limited to common metal materials such as aluminum alloys, stainless steel, and titanium alloys, and obtains simulation data of welding deformation and residual stress, with the sheet thickness ranging from 2mm to 5mm.

[0071] A fourth aspect of the present invention provides a dual-sided laser synchronous welding system, comprising a laser, a laser fiber, a welding head, a computing unit, and a control unit. Two lasers are used to generate dual-sided lasers, which are then directed into the welding head via dual-sided laser fibers. The welding head is used to focus the laser onto the desired welding location. The computing unit includes a memory, a processor, and a communication bus; the communication bus enables communication between the processor and the memory, and the processor executes one or more programs stored in the memory; the computing unit is used for finite element simulation calculations and process optimization, and feeds back the simulation results to the control unit. The control unit uses the optimized laser parameters from the computing unit to implement the laser welding process, thereby running the method for establishing a dual-sided laser synchronous welding heat source model according to a second aspect of the present invention.

[0072] In a fifth aspect, the present invention provides a computer-readable storage medium storing one or more programs, which can be executed by one or more processors to run a method for establishing a dual-sided laser synchronous welding heat source model provided in the second aspect of the present invention.

[0073] The following will provide a detailed explanation using specific experimental data.

[0074] The T-shaped structure uses 2000 series aluminum alloy as the flat plate and stiffener, both with a thickness of 2.0 mm. The flat plate is 100 mm × 100 mm in size, and the L-shaped stiffener is 100 mm long and 28 mm high. Before welding, the plate is neutralized by alkaline washing and acid washing with sodium hydroxide solution and nitric acid solution, respectively. It is then rinsed with clean water and dried in a drying oven for later use.

[0075] Based on the actual situation, two laser heat sources are applied to both sides of the T-joint for welding. The effective power of each laser heat source is 3.0kW, the moving speed of the laser heat source is 10m / min, the clamp between each laser heat source and the stiffener is 68°, there is no heat source gap between the two laser heat sources along the x-axis, and the filler wire is 1.2mm diameter aluminum-silicon welding wire with a wire feeding speed of 4m / min.

[0076] Step 1: Using FORTRAN language compilation software, write the program code for the heat source model provided in this invention;

[0077] Step 2: Mesh the 3D geometric model using the built-in meshing function of the finite element software. The mesh type is uniformly selected as an eight-node thermally coupled hexahedral element, which is suitable for thermal coupling calculations. A denser mesh with smaller elements is used near the weld area, and the mesh size increases with distance from the weld. The minimum mesh size is 0.2 mm, the maximum mesh size is 6.0 mm, the total number of meshes is 70,000, and the total number of nodes is 79,413.

[0078] Step 3: Based on the finite element method software, the established double-sided laser synchronous welding heat source model is loaded onto the three-dimensional mesh model. The thermal boundary conditions of the plate, stiffener and other surfaces are thermal convection and thermal radiation. The initial temperature and ambient temperature of the T-shaped structure are both 20℃. The calculation is submitted and solved to obtain the welding temperature field and weld cross-sectional morphology.

[0079] Figure 4 shows the morphology of the molten metal through the T-joint simulated by the method of the present invention. In Figure 5, the left side shows the morphology of the molten metal obtained from the finite element simulation, where the portion above 660℃ is the weld seam, and the right side shows the actual weld seam shape obtained from the welding experiment. Comparing the left and right shapes, it can be seen that the molten metal morphology obtained by introducing the dual-sided laser synchronous welding heat source model matches the weld seam shape obtained from the experiment well. Figure 6 shows the welding deformation field of the T-joint simulated by the method of the present invention. To clearly show the deformation trend, the deformation scaling factor is set to 10 times the deformation magnification under global coordinate system conditions. Figure 7 shows the calculated result of the angular deformation of the T-joint simulated by the method of the present invention. The calculated angular deformation of the T-joint is 0.46°. Figure 8 shows the residual stress field of the T-joint simulated by the method of the present invention. The maximum principal stress inside the weld seam is 202 MPa. The established heat source model can be directly applied to the finite element simulation model of the temperature field of laser welding of large T-shaped structural components with multiple weld seams.

[0080] This invention establishes a novel dual-sided laser synchronous welding heat source model, employing two laser heat sources placed on either side of the T-joint. Each heat source is a combination of a Gaussian column heat source attenuation model and a Gaussian surface heat source correction model, acting on both the weld interior and weld surface. By optimizing welding process parameters, accurate simulation of the weld penetration zone of the T-shaped thin plate weldment is achieved. Functionally, this enables the prediction of residual stress and welding deformation during the design phase, saving significant time and material costs. This demonstrates that this invention is a suitable method for establishing a dual-sided laser synchronous welding heat source model.

[0081] The experimental results and simulation results are in good agreement, indicating that the present invention improves the accuracy of welding simulation results.

[0082] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. The accompanying drawings are only one embodiment of the present invention, and the actual structure is not limited thereto. No reference numerals in the claims should limit the scope of the claims. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the scope of protection of the present invention. Furthermore, the word "comprising" does not exclude other elements or steps, and the word "a" preceding an element does not exclude the inclusion of "a plurality" of that element. Multiple elements stated in the product claims may also be implemented by a single element through software or hardware. The terms "first," "second," etc., are used to indicate names and do not indicate any specific order.

Claims

1. A dual-sided laser synchronous welding heat source model, characterized in that, The model uses two laser heat sources symmetrically applied to both sides of the T-joint. Each laser heat source is a combination of a Gaussian column heat source attenuation model and a Gaussian surface heat source correction model. In the combination heat source, the Gaussian column heat source attenuation model acts on the internal area of ​​the weld on both sides of the T-joint, and the Gaussian surface heat source correction model acts on the surface area of ​​the weld on both sides of the T-joint.

2. A method for establishing a heat source model for dual-sided laser synchronous welding, used to establish the heat source model for dual-sided laser synchronous welding as described in claim 1, characterized in that, The specific steps are as follows: Step 100: Establish a heat source model for dual-sided laser synchronous welding; Step 200: Establish a three-dimensional finite element model of the T-joint; In the same coordinate system as in step 100, a three-dimensional geometric model of the T-joint is established, and a mesh is generated to obtain a three-dimensional mesh model of the T-joint. Step 300: Solve the governing equations using finite element method software and perform thermo-mechanical coupling calculations; Based on finite element method (FEM) software, the established dual-sided laser synchronous welding heat source model was loaded onto a three-dimensional mesh model. The heat source control position and workpiece loading boundary conditions were set, and the calculation was submitted and solved to obtain welding temperature field and weld cross-sectional morphology data. The laser parameters were adjusted to verify the rationality of the dual-sided laser synchronous welding heat source model parameter settings by comparing the simulated molten metal morphology with the actual weld shape, and the optimized laser parameters were obtained. Using the optimized laser parameters, the welding deformation and residual stress data of the workpiece were obtained. The dual-sided laser synchronous welding heat source model was then established.

3. The method for establishing a heat source model for dual-sided laser synchronous welding according to claim 2, characterized in that, The governing equations for the attenuation model of each Gaussian column heat source are shown in Equation (1): q v (x, y, z, t) represents the heat flux density function of the Gaussian column heat source on the workpiece weld, (x, y, z) represents the coordinates of the global coordinate system, t represents the welding time, α represents the laser power distribution coefficient, Q represents the total laser power, H represents the effective heating depth of the volume heat source, and r v The effective heating radius of the heat source represents the volumetric heat source, and v represents the welding speed; the two Gaussian column heat source attenuation models are moving heat sources moving along the x-axis and attenuation models along the z-axis.

4. The method for establishing a heat source model for dual-sided laser synchronous welding according to claim 3, characterized in that, The governing equations for each Gaussian surface heat source correction model are shown in equation (2): q s (x, y, t) represents the heat flux density function of the Gaussian surface heat source on the workpiece surface, (x, y) represents the coordinates in the global coordinate system, t represents the welding time, α represents the laser power distribution coefficient, β represents the heat flux concentration coefficient, Q represents the total laser power, and r s The effective heating radius of the surface heat source is represented by , and v represents the welding speed; the two Gaussian surface heat source correction models are moving heat sources moving along the x-axis.

5. The method for establishing a heat source model for dual-sided laser synchronous welding according to claim 4, characterized in that, The process also includes the following steps: two laser heat sources are symmetrically applied to both sides of the T-joint, and the two laser heat sources simultaneously weld the welding position at an angle θ, where θ is the angle between the beam and the stiffener. A rotating coordinate system is established, and the control equations are obtained as shown in formulas (3)-(6): y1=(y-y0)cosθ+(z-z0)sinθ (3) z1=(z-z0)cosθ-(y-y0)sinθ (4) y2=(y-y0)cosθ-(z-z0)sinθ (5) z2=(z-z0)cosθ+(y-y0)sinθ (6) (x, y, z) represent the coordinates of the global coordinate system before the transformation, (x0, y0, z0) represent the absolute coordinates relative to the origin O of the coordinate system, (x1, y1, z1) represent the coordinates after the rotation by an angle θ, (x2, y2, z2) represent the coordinates after the rotation by an angle -θ, x1 = x - x0, x2 = x - x0.

6. The method for establishing a heat source model for dual-sided laser synchronous welding according to claim 5, characterized in that, The process also includes the following steps: substituting (x1, y1, z1) and (x2, y2, z2) into formulas (1) and (2) respectively, to finally obtain the total heat flux density function applied to both sides of the T-joint. The governing equation is shown in formula (7): q Total (x,y,z,t)=q v1 (x,y,z,t)+q v2 (x,y,z,t)+q s1 (x,y,t)+q s2 (x,y,t) (7) q Total (x, y, z, t) represents the total heat flux density function applied to both sides of the T-joint; q v1 (x, y, z, t) is obtained by substituting (x1, y1, z1) into formula (1), q v2 (x, y, z, t) is obtained by substituting (x², y², z²) into formula (1), q v1 (x, y, z, t) and q v2 (x, y, z, t) represents the heat flux density function of the two symmetrically distributed laser Gaussian column heat sources on both sides of the T-joint inside the weld seam of the workpiece; q s1 (x, y, t) is obtained by substituting (x1, y1, z1) into formula (2), q s2 (x, y, t) is obtained by substituting (x2, y2, z2) into formula (2), q s1 (x, y, t) and q s2 (x, y, t) represents the heat flux density function of two laser Gaussian surface heat sources symmetrically distributed on both sides of the T-joint on the surface of the workpiece weld.

7. The method for establishing a heat source model for dual-sided laser synchronous welding according to claim 6, characterized in that, The control equations are solved using finite element method software, and thermo-mechanical coupling calculations are performed. The three-dimensional partial differential equation for heat conduction in a solid with a heat source and a transient temperature field is established as shown in equation (8): T represents the transient temperature of the workpiece, t represents the welding and cooling time, k represents the thermal conductivity of the material, ρ represents the material density, and c p q represents the specific heat of the material. Total (x, y, z, t) represents the total heat flux density function applied to both sides of the T-joint as shown in formula (7), and (x, y, z) represents the coordinates of the global coordinate system.

8. A simulation method for a heat source in dual-sided laser synchronous welding, characterized in that, Using the dual-sided laser synchronous welding heat source model described in claim 1, the welding process of weldable thin sheet metal materials is simulated to obtain simulation data on welding deformation and residual stress. The thickness of the thin sheet metal material ranges from 2mm to 5mm.

9. A dual-sided laser synchronous welding system, comprising a laser, a laser fiber, a welding head, a computing unit, and a control unit, characterized in that, Two lasers are used to generate dual-sided lasers, which are then directed into the welding head via dual-sided laser fibers. The welding head is used to focus the laser beam onto the desired welding location; The computing unit includes a memory, a processor, and a communication bus; the communication bus enables communication between the processor and the memory, and the processor executes one or more programs stored in the memory; the computing unit is used for finite element simulation calculations and process optimization, and feeds back the simulation results to the control unit; The control unit uses the optimized laser parameters in the computing unit to realize the laser welding process, so as to run the method for establishing a dual-sided laser synchronous welding heat source model as described in any one of claims 2-7.

10. A computer-readable storage medium, characterized in that, The storage contains one or more programs, which can be executed by one or more processors to run the method for establishing a dual-sided laser synchronous welding heat source model as described in any one of claims 2-7.

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