A Thermo-Mechanical Coupling Simulation Method for a Robot-Assisted Curved Surface Laser Metal Deposition Process

Abstract

The present invention proposes a thermo-mechanical coupling simulation method for a robot-assisted curved surface laser metal deposition process, belonging to the technical field of laser metal deposition. Calibrate the cross-sectional size of the deposition track; discretize the continuous simulated deposition path into several segments, and use the calibrated deposition track cross-section to scan along the discrete path on the curved surface substrate to form the deposition layer shape, obtaining a geometric model including the curved surface substrate and the deposition layer; perform mesh division and optimization on the geometric model; set the material properties, boundary conditions, and laser path of the substrate and the deposition layer, pre-write the material properties in the deposition layer shape and hide them; perform laser metal deposition simulation, and synchronously activate the material properties of the substrate and the deposition layer in the laser action area as the laser action origin moves, and calculate the evolution results of the stress field and the temperature field. The present invention coordinates calculation accuracy and efficiency, realizes the modeling of the curved surface free path deposition process, and can accurately predict the evolution of the stress field and the temperature field.

Description

Technical Field

[0001] The present invention relates to the technical field of laser metal deposition, and particularly to a thermo-mechanical coupling simulation method for a robot-assisted curved surface laser metal deposition process. Background Art

[0002] The laser metal deposition process has achieved efficient development in the fields of industrial repair and complex-shaped component manufacturing due to its high deposition rate and potential for multi-scenario applications. Laser metal deposition involves complex physical changes and is a multi-scale and multi-physical field coupling process. It is difficult to comprehensively study this process, and factors such as the interaction between materials and energy sources, the dynamics of the molten pool flow field, and the heat conduction between components need to be considered. Currently, the research on the laser metal deposition process mainly carried out in an experimental manner. The relevant experiments involve many links, take a long time, and face many uncertainties and error factors.

[0003] The thermo-mechanical numerical modeling for the laser metal deposition process provides a cost-effective and concise and effective solution for analyzing the physical characteristics of the process, optimizing process parameters, and processing strategies. Existing numerical modeling methods generally involve the coupling of three types of components: heat source-material interaction, molten pool morphology dynamics, and microstructure models. Due to computational cost limitations, the models often need to make corresponding simplified assumptions about materials, molten pools, and heat conduction, and focus on model construction at a single scale according to actual needs.

[0004] With the development of robot-assisted additive manufacturing systems, the application frequency of the laser metal deposition process in the design and manufacturing of complex components, especially curved surface components, has gradually increased. To save computational costs, existing technical solutions tend to build models based on simple geometric shapes, and there is still a lack of methods for problems such as laser path planning, material deposition process, and physical field evolution in the laser metal deposition process for complex-shaped curved surface components. Based on existing computing resources, the workload and computational cost for realizing a complete model construction are very high. In most cases, the model needs to balance computational speed and accuracy. Therefore, existing modeling schemes basically need to make a focused adjustment to the model according to their research purposes. In addition, due to the complexity of the laser metal deposition process, a series of highly simplified assumptions need to be used when performing numerical modeling and simulation, which greatly limits the physical reducibility of the model and the accuracy of characterization. Summary of the Invention

[0005] In order to solve the above problems, the present invention proposes a thermo-mechanical coupling simulation method for a robot-assisted curved surface laser metal deposition process. The present invention coordinates computational accuracy and efficiency, realizes the modeling of the curved surface free-path deposition process, and can accurately predict the evolution of the stress field and temperature field.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention proposes a thermo-mechanical coupling simulation method for a robot-assisted curved surface laser metal deposition process, comprising the following steps:

[0008] Step 1, calibrate the cross-sectional size of the deposition track; during the calibration process, take two partially overlapping deposition tracks as a reference to obtain a rectangular calibration size, and take half of the height and width of the rectangular calibration size as the cross-sectional size of the deposition track;

[0009] Step 2, obtain a continuous simulated deposition path according to the robot data, discretize the continuous path into several segments, and use the calibrated deposition track cross-section to scan along the discrete path on the curved surface substrate to form a deposition layer shape, obtaining a geometric model including the curved surface substrate and the deposition layer;

[0010] Step 3, perform an initial mesh division on the geometric model, and optimize the mesh using the corner refinement and adaptive methods;

[0011] Step 4, set the material properties, boundary conditions, and laser path of the substrate and the deposition layer, pre-write and hide the material properties of the substrate and the deposition layer in the deposition layer shape;

[0012] Step 5, perform a laser metal deposition simulation according to the laser path and boundary conditions, synchronously activate the material properties of the substrate and the deposition layer in the laser action area as the laser action origin moves, and calculate the evolution results of the stress field and temperature field of the curved surface laser metal deposition process as the laser action area moves.

[0013] Preferably, in the present invention, taking two partially overlapping deposition tracks as a reference to obtain a rectangular calibration size during the calibration process includes:

[0014] Obtain actual samples of two partially overlapping deposition tracks in a pre-experiment manner;

[0015] Use a microscope to calibrate the cross-sectional outer contour and area of the deposition track sample;

[0016] Take 90%-97% of the height of the highest point of the cross-sectional outer contour size as the height of the rectangular calibration size, and determine the width of the rectangular calibration size based on the approximate area to obtain the rectangular calibration size;

[0017] The difference between the rectangular area under the rectangular calibration size and the cross-sectional area of the deposition track sample is within a preset threshold range.

[0018] Preferably, in the present invention, obtaining a continuous simulated deposition path according to the robot data includes:

[0019] Obtain robot data, where the robot data includes discrete coordinate points of the action position of the robot's manipulator;

[0020] Generate a continuous simulated deposition path from discrete coordinate points in the form of an interpolation curve.

[0021] As a preference of the present invention, after forming a deposition layer shape by scanning along a discrete path on a curved substrate using a calibrated deposition channel cross-section, it further includes:

[0022] Solve and eliminate the overlapping interference between deposition layer shapes through Boolean operations.

[0023] As a preference of the present invention, the optimization of the mesh using the corner refinement and adaptive method includes:

[0024] For the initially divided mesh, refine the mesh with sharp corners and large curvatures;

[0025] Adaptive adjustment of the mesh density according to the accuracy requirements of the geometric model, the higher the accuracy requirements, the greater the mesh density.

[0026] As a preference of the present invention, the boundary conditions include a heat transfer part and a stress part. The heat transfer part includes a thermal radiation boundary, a heat convection boundary, and a latent heat of phase change boundary. The stress part includes an elastic stress boundary and a stress boundary generated by inelastic thermal strain and plastic strain.

[0027] As a preference of the present invention, the laser path is obtained by matching the discrete coordinate points of the simulated deposition path with a time variable based on the laser speed.

[0028] As a preference of the present invention, during the simulation of laser metal deposition, the range of the laser action area is not less than the range of the deposition channel cross-section size. As the origin of the laser action moves, it is judged whether the center point of the mesh is within the laser action area. If so, the material properties of the mesh element are activated, otherwise it continues to be hidden.

[0029] As a preference of the present invention, the laser action surface is set as the lower surface of the deposition channel, and the laser beam direction is always perpendicular to the action surface.

[0030] In a second aspect, the present invention proposes a thermo-mechanical coupling simulation system for a robot-assisted curved surface laser metal deposition process to implement the above thermo-mechanical coupling simulation method.

[0031] The beneficial effects of the present invention are:

[0032] The present invention is directed to complex curved surface components. By using two partially overlapping deposition channels as a reference to calibrate the deposition channel cross-section size, and freely modeling the curved surface deposition channel by scanning a calibrated rectangular cross-section along the simulated deposition path, the modeling freedom is improved, effectively adapting to the flexibility characteristics of robot-assisted manufacturing.

[0033] In the present invention, by discretizing the simulated deposition path and taking each discrete segment as an analysis step to be solved, the deposition process is decomposed with a single-pass deposition as the discrete unit. First, the material properties of the substrate and the deposited layer are hidden, and then during the laser metal deposition simulation process, as the origin of the laser action moves, the material properties of the substrate and the deposited layer in the laser action area are synchronously activated. Based on a macroscopic perspective, a numerical model of the laser metal deposition process for robot-assisted curved surface components is established, enabling accurate prediction of the temperature field and stress field in the deposition area, which can be applied to the manufacturing process under different process conditions and has high universality.

[0034] The research of the present invention on the robot-assisted laser metal deposition process is of great significance, providing a reference value for analyzing the physical characteristics of the laser metal deposition process, seeking optimal process parameters, and optimizing processing strategies. Description of the Drawings

[0035] Figure 1 is a flow block diagram of a thermo-mechanical coupling simulation method for a robot-assisted curved surface laser metal deposition process in an embodiment of the present invention.

[0036] Figure 2 is a schematic diagram for calibrating the cross-sectional size of a deposition channel in an embodiment of the present invention.

[0037] Figure 3 is a schematic diagram of single-layer multi-pass parallel deposition on a cylindrical surface in an embodiment of the present invention; wherein, 1 - the movement path of the deposition origin at the end of the cladding head, 2 - the starting point of the scanning path, 3 - the ending point of the scanning path, 4 - the cylindrical substrate.

[0038] Figure 4 is a schematic diagram of the principle of the laser action area in an embodiment of the present invention.

[0039] Figure 5 is the fixed-point thermal cycle result during single-pass multi-layer deposition in an embodiment of the present invention.

[0040] Figure 6 is the fixed-point stress change result during single-pass multi-layer deposition in an embodiment of the present invention.

[0041] Figure 7 is the molten pool morphology diagram at a certain moment during single-layer multi-pass deposition in an embodiment of the present invention. Detailed Embodiments

[0042] The following further elaborates and explains the present invention in combination with specific embodiments. The embodiments are only demonstrations of the present disclosure content and do not delimit the scope of limitation. Without conflict, the technical features of each embodiment in the present invention can be combined accordingly.

[0043] The accompanying drawings are only schematic illustrations of the present invention and are not necessarily drawn to scale. Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0044] The flowcharts shown in the accompanying drawings are only exemplary illustrations and do not necessarily include all steps. For example, some steps can be further decomposed, while some steps can be combined or partially combined. Therefore, the actual execution order may be changed according to the actual situation.

[0045] The present invention focuses on the numerical modeling and simulation of the laser metal deposition process of curved components, and predicts the evolution of the temperature field and stress field in the solution domain from a macroscopic perspective. The flowchart of the thermal-mechanical coupling simulation method for the robot-assisted curved surface laser metal deposition process is as Figure 1 shown, and mainly includes the calibration of the deposition channel cross-sectional size, the establishment of the geometric model, the mesh optimization, the setting of material properties, the setting of boundary conditions, the setting of the laser path, the material deposition simulation, and the solution.

[0046] In this embodiment, a thermal-mechanical coupling simulation method for the robot-assisted curved surface laser metal deposition process mainly includes the following steps:

[0047] S1. Calibrate the deposition channel cross-sectional size; during the calibration process, two partially overlapping deposition channels are used as references to obtain the rectangular calibration size, and half of the height and width of the rectangular calibration size are taken as the deposition channel cross-sectional size.

[0048] S2. Obtain a continuous simulated deposition path according to the robot data, discretize the continuous path into several segments, and use the calibrated deposition channel cross-section to scan along the discrete path on the curved surface substrate to form a deposition layer shape, so as to obtain a geometric model including the curved surface substrate and the deposition layer. Here, each discretized segment is used as an analysis step to be solved, the deposition process is decomposed with a single-pass deposition as the discrete unit, and relevant settings for the subsequent laser path and material property activation are carried out for the set of discrete analysis steps.

[0049] S3. Perform an initial mesh division on the geometric model and optimize the mesh using the corner refinement and adaptive methods.

[0050] S4. Set the material properties, boundary conditions, and laser path of the substrate and the deposition layer, pre-write the material properties of the substrate and the deposition layer in the deposition layer shape and hide them.

[0051] S5. Conduct laser metal deposition simulation based on the laser path and boundary conditions. Synchronously activate the material properties of the substrate and the deposited layer in the laser action area as the laser action origin moves, and obtain the evolution results of the stress field and temperature field of the curved surface laser metal deposition process as the laser action area moves.

[0052] The above step S1 is used to calibrate the cross-sectional size of the deposition path. The cross-sectional size of the deposition path is one of the key parameters in numerical modeling and simulation, which reflects the comprehensive effects of process parameters such as laser power, scanning speed, and powder feeding rate in the actual process. By calibrating the cross-sectional size of the deposition path, it can help verify and adjust the heat source model (laser) and the shape and performance of the material deposition, making the simulation results match the actual process.

[0053] In this embodiment, the deposition geometry size is verified through pre-experiments. Select given parameters such as laser power, cladding speed, and overlap rate to print single-pass and multi-pass target materials. Take two partially overlapping deposition paths as a reference, and use a metallurgical microscope to calibrate the outer contour and area size of the cross-section. The height of the cross-section size is an important parameter of the outer contour of the cross-section size. Use a standard rectangle to simplify and replace the irregular cross-section shape of the outer contour of the cross-section size. Figure 2 It is a schematic diagram of calibrating the cross-sectional size of the deposition path in the embodiment of the present invention. Take two deposition paths with 40% overlap as a reference. Under the metallurgical microscope, its cross-section presents an irregular semi-circular shape, with a width of 2.6733 mm and a height of 0.6308 mm. In order to convert it into a standard rectangle with a similar area, preferably use 90%-97% of the height as the height of the rectangle, and determine the width of the rectangle based on the approximate area. In this embodiment, the determined height of the rectangle is 0.6 mm, and the width of the rectangle under the approximate area is 2.4 mm. Take half of the height and width of the rectangle calibration size as the cross-sectional size of the deposition path, that is, the height is 0.6 mm and the width is 1.2 mm.

[0054] The above step S2 is used to establish a geometric model including a curved surface substrate and a deposited layer. The geometric model is the basis of the simulation. The substrate of the geometric model can be directly imported through an external model. Take a cylindrical substrate as an example, such as Figure 3As shown; for the deposition layer of the geometric model, geometric creation is carried out by scanning along the simulated deposition path with the calibrated cross-sectional size of the deposition track. In the robot-assisted laser deposition process, the simulated deposition path is obtained by reading the robot data. The deposition path corresponding to the continuous deposition process is continuous. In the present invention, it is discretized. The deposition process is decomposed with a single-pass deposition as the discrete unit, and then discrete coordinate points are extracted from the single-pass deposition path curve; to match the pose control logic of the robot manipulator, in this embodiment, the discrete coordinate points read from the robot data are generated into a simulated deposition path in the form of an interpolation curve. By discretizing the continuous path into several segments, the calibrated deposition track cross-section is used to scan along the discrete path on the curved surface substrate to form the deposition layer shape, and a geometric model including the curved surface substrate and the deposition layer is obtained. Taking the single-layer multi-pass parallel deposition on a cylindrical surface as an example, as Figure 3 shown, the label 1 in the figure represents the movement path of the deposition origin at the end of the cladding head, the label 2 represents the starting point of the scanning path, the label 3 represents the ending point of the scanning path, and the label 4 represents the substrate. Move the calibrated deposition track cross-section to the starting point 2 of the scanning path, control it to scan along the movement path 1 of the deposition origin at the end of the cladding head, and stop at the position of the ending point 3 of the scanning path. The deposition layer geometric shape generated by cross-section scanning is likely to overlap with adjacent single passes or the substrate 4. In this embodiment, the overlap interference between geometric shapes is eliminated by Boolean operation.

[0055] The above step S3 is used to optimize the mesh. Initial mesh division is performed on the geometric model. Since the large curvature and gap parts in the geometric model will cause higher difficulty in mesh division and it is difficult for the calculation to converge, in this embodiment, local mesh refinement is carried out by combining corner refinement and the adaptive method. Among them, corner refinement refers to refining the sharp corners and large curvature parts, and the adaptive method refers to adjusting the mesh density according to the accuracy requirements of the geometric model. The higher the accuracy requirement, the greater the mesh density.

[0056] The above step S3 is used to set material properties, boundary conditions, and laser paths before material deposition simulation.

[0057] Among them, the material properties can be calculated using professional material property simulation software. The accuracy of the calculation of various material property simulation software in this field has been widely verified. By inputting the composition elements and heat treatment methods of the material, thermophysical parameters and mechanical property parameters such as density, elastic modulus, Poisson's ratio, thermal conductivity, specific heat capacity, and linear expansion coefficient of the material at different temperatures can be calculated. Here, the material properties include the material properties of the substrate and the deposition layer.

[0058] Boundary conditions mainly involve corresponding settings for heat transfer boundaries and stress boundaries. To balance the accuracy and efficiency of numerical model calculations, based on the thermo-mechanical coupling mechanism of laser metal deposition, the following assumptions are introduced in the heat transfer part to appropriately simplify the model and take into account both simulation calculation accuracy and efficiency:

[0059] (1) The material is regarded as a continuous medium, and the thermal properties of the material vary with temperature;

[0060] (2) Only the solid-liquid transformation is considered for the phase change of the molten pool metal, while the evaporation of the molten pool metal is ignored;

[0061] (3) The evolution of the microstructure in the molten pool area is ignored;

[0062] (4) Single-scale simulation is carried out;

[0063] Based on the above assumptions, the heat transfer boundaries mainly include the thermal radiation boundary, the thermal convection boundary, and the latent heat of phase change boundary. Each boundary is introduced below.

[0064] The transient control of the temperature evolution in the simulation area is carried out by Equation (1):

[0065]

[0066] where ρ is the material density, C P is the specific heat capacity, T is the temperature field, u is the velocity field, q is the heat flux vector field, Q is the change in heat in the control process simulation domain, and k is the thermal conductivity.

[0067] The thermal convection boundary is set on the surface where the geometric model contacts the external environment. According to Newton's cooling law, the heat loss caused by convection can be obtained by Equation (2):

[0068] q c =h c (T - T amb )(2)

[0069] where h c is the convective heat transfer coefficient, and T amb is the ambient temperature.

[0070] Thermal radiation is the phenomenon of electromagnetic waves emitted by an object due to its temperature being higher than absolute zero. The thermal radiation boundary is set in the deposition layer and its nearby areas; the heat loss caused by thermal radiation can be determined by the Stephen-Boltzmann formula (3):

[0071] q r =ε·σ r ·(T 4 - T amb 4 )(3)

[0072] Among them, ε is the emissivity, which can be obtained by referring to the total emissivity table of metal materials; σ r = 5.67×10 -8 W / m 2 / K 4 is the Stephen-Boltzmann constant.

[0073] According to the above analysis, the heat transfer boundary control equation considering both heat convection heat dissipation and heat radiation loss in the deposition area is shown in Equation (4).

[0074] -n·q = q c +q r (4)

[0075] During the laser cladding process, the metal material will undergo a process of rapid melting and solidification, involving a rapid transformation of the physical state of the material. Therefore, the latent heat of phase change boundary should be considered when establishing the numerical model. The latent heat of phase change boundary is controlled in the model by modifying the specific heat capacity of the material, as shown in Equation (5).

[0076]

[0077] Among them, L f is the latent heat of phase change, and T m is the temperature at which the material undergoes phase change.

[0078] The stress boundary is introduced as follows.

[0079] The stress-strain relationship of the material is generally described by a linear elastic model. The elastic stress tensor σ e and the elastic strain tensor ε e are related by Hooke's law, as shown in Equation (6):

[0080] σ e = D:ε e (6)

[0081] Among them, D is a fourth-order elastic tensor, which is composed of the Young's modulus and Poisson's ratio affected by the material temperature. On this basis, the non-linear elastic deformation part also needs to be considered. Therefore, the total stress and total strain of the model are shown in Equation (7):

[0082]

[0083] Among them, ε inel and σ inel are the non-linear elastic strain and the corresponding stress part. The non-linear elastic strain includes thermal strain ε th and plastic strain ε pl . The thermal strain is calculated using the actual temperature T and the reference temperature T refThe temperature difference and the temperature-related coefficient of thermal expansion α are calculated as shown in Equation (8):

[0084] ε th = α(T - T ref )(8)

[0085] For plastic strain, the Von Mises yield criterion is adopted, and the plastic strain is calculated using the isotropic hardening model as shown in Equation (9). The yield criterion defines the stress conditions for plastic deformation. The stress outside the yield surface causes permanent deformation (plastic strain), and the stress inside the yield surface causes recoverable deformation (elastic strain).

[0086]

[0087] Among them, σ ys (ε pe ) is the yield stress, σ ys0 is the initial yield stress, ε pe is the effective plastic strain, k is the isotropic hardening modulus, and E Tiso is the isotropic tangential plastic modulus.

[0088] In the laser path setting, the laser speed is defined. By matching the time axis based on the laser speed according to the simulated deposition path, the laser path can be obtained. Similarly, the laser path is discrete. In this embodiment, the laser is characterized by a Gaussian heat source model. The laser path is controlled by the discrete coordinate points of the simulated deposition path. According to the movement speed of the robotic arm of the robot during the actual deposition process, the coordinates of the coordinate points on the simulated deposition path in the X, Y, and Z directions are respectively matched with time variables. The laser action surface is set as the lower surface of the deposition channel, and the beam direction is controlled to be always perpendicular to the action surface.

[0089] After completing the setting of the material properties, boundary conditions, and laser path of the substrate and the deposition layer, the material properties of the substrate and the deposition layer are pre-written in the deposition layer body and hidden. In this embodiment, by multiplying the material properties of each item of the substrate and the deposition layer by a very small scale factor, it can be regarded as non-existent in physical meaning to achieve the "hiding" function.

[0090] The above step S5 is used for material deposition simulation and solution. In this embodiment, first, a circular deposition area is set around the origin of the deposition beam on the laser action surface to limit the laser action area, as Figure 4As shown, adding a range criterion activates the material properties of the deposition area including the laser action area, while the material properties of the remaining areas to be deposited are in an inactive state. Here, the range of the laser action area is not less than the range of the cross-sectional size of the deposition channel. According to the laser path and boundary conditions, laser metal deposition simulation is carried out. As the origin of the laser action moves, the material properties of the substrate and the deposited layer in the laser action area are activated synchronously. In this embodiment, the method of activating each grid cell is adopted. It is judged whether the center point of the grid is within the laser action area. If so, the material properties of the grid cell are activated, and the evolution results of the stress field and temperature field of the curved surface laser metal deposition process moving with the laser action area are obtained.

[0091] In a specific implementation of the present invention, a transient solver is used to solve the stress field and temperature field. The solution settings include tolerance settings, time step selection, time stepping methods, etc. The solution process is common general knowledge in the art and will not be elaborated here. Taking the simple deposition on a cylindrical surface as an example, Figure 5 and Figure 6 respectively show the fixed-point thermal cycle situation and stress change situation during single-pass multi-layer deposition, Figure 7 showing the molten pool morphology under single-layer multi-pass deposition.

[0092] The thermo-mechanical coupling simulation method for the robot-assisted curved surface laser metal deposition process proposed by the present invention can realize the geometric characterization of the laser metal deposition process for any curved surface component with a clear manufacturing process. The key to the deposition process control lies in the division of the solution analysis steps. The deposition process is decomposed with a single-pass deposition as a discrete unit, and relevant settings for the laser path and material property activation are carried out for the set of discrete analysis steps. The present invention designs the thermo-mechanical coupling mechanism, laser heat source design and material activation strategy of the laser metal deposition process from an analytical perspective. While introducing appropriate simplifications to the process, it ensures the reduction degree of the model, and overall considers the calculation efficiency and accuracy of the numerical model. The present invention is oriented to complex curved surface components and has a high modeling freedom.

[0093] Based on the same inventive concept, the embodiment of the present invention also provides a robot-assisted curved surface laser metal deposition process thermo-mechanical coupling simulation system for implementing the above method. The thermo-mechanical coupling simulation system includes:

[0094] A deposition channel cross-sectional size calibration module, which is used to calibrate the cross-sectional size of the deposition channel; during the calibration process, two partially overlapping deposition channels are used as a reference to obtain a rectangular calibration size, and half of the height and width of the rectangular calibration size are taken as the cross-sectional size of the deposition channel;

[0095] A geometric model building module, which is used to obtain a continuous simulated deposition path according to robot data, discretize the continuous path into several segments, and use the calibrated cross-section of the deposition channel to scan along the discrete path on the curved surface substrate to form a deposition layer shape, so as to obtain a geometric model including the curved surface substrate and the deposition layer;

[0096] A mesh optimization module, which is used to perform an initial mesh division on the geometric model and optimize the mesh by using corner refinement and adaptive methods;

[0097] A preprocessing module, which is used to set the material properties, boundary conditions and laser path of the substrate and the deposition layer, pre-write and hide the material properties of the substrate and the deposition layer in the deposition layer shape;

[0098] A material deposition simulation and solution module, which is used to perform laser metal deposition simulation according to the laser path and boundary conditions, synchronously activate the material properties of the substrate and the deposition layer in the laser action area as the laser action origin moves, and calculate the evolution results of the stress field and temperature field of the curved surface laser metal deposition process as the laser action area moves.

[0099] For the system embodiment, since it basically corresponds to the method embodiment, the relevant parts can refer to the partial description of the method embodiment, and the implementation methods of the remaining modules will not be elaborated here. The system embodiments described above are only illustrative. The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of the present invention. Those of ordinary skill in the art can understand and implement it without creative work.

[0100] The embodiments of the system of the present invention can be applied to any device with data processing capabilities, and the any device with data processing capabilities can be a device or apparatus such as a computer. The system embodiment can be implemented by software, or by hardware or a combination of software and hardware. Taking software implementation as an example, as a logically meaningful device, it is formed by the processor of any device with data processing capabilities reading the corresponding computer program instructions in the non-volatile memory into the memory and running.

[0101] The above embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. For those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A robot-assisted curved surface laser metal deposition process thermal-mechanical coupling simulation method, characterized in that: The following steps are involved: Step 1, calibrating the cross-sectional dimensions of the deposition track; during the calibration process, two partially overlapping deposition tracks are used as references to obtain a rectangular calibration dimension, and half of the height and width of the rectangular calibration dimension are taken as the cross-sectional dimensions of the deposition track; Step 2, a continuous simulated deposition path is obtained according to the robot data, the continuous path is discretized into several segments, and a deposition layer shape is formed by scanning along the discrete path on the curved substrate using the calibrated deposition path section, thereby obtaining a geometric model including the curved substrate and the deposition layer; Step 3, perform initial meshing on the geometric model and optimize the mesh using angle refinement and adaptive methods; Step 4, setting the material properties of the substrate and the deposited layer, boundary conditions and laser path, pre-writing the material properties of the substrate and the deposited layer in the deposited layer shape and hiding them; Step 5: Perform laser metal deposition simulation based on the laser path and boundary conditions. As the laser action origin moves, the material properties of the substrate and the deposited layer in the laser action area are synchronously activated, and the evolution results of the stress field and temperature field of the curved surface laser metal deposition process that moves with the laser action area are calculated.

2. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: The calibration process uses two partially overlapping deposition tracks as reference to obtain the rectangular calibration size, including: Obtain actual two partially overlapping sedimentation trace samples in a pre-experimental manner; Use a microscope to calibrate the cross-sectional outer contour and area of ​​the deposition channel sample; The height of the rectangular calibration dimension is determined by taking 90%-97% of the highest point height of the cross-section outer contour as the height, and the width of the rectangular calibration dimension is determined by the approximate area to obtain the rectangular calibration dimension; The difference between the rectangular area at the rectangular calibration size and the cross-sectional area of ​​the deposition track sample is within a preset threshold range.

3. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: The method of obtaining a continuous simulated deposition path according to robot data includes: Acquiring robot data, wherein the robot data includes discrete coordinate points of the action positions of the robot's mechanical arm; The discrete coordinate points are interpolated into a continuous simulated deposition path.

4. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: After forming a deposition layer shape by scanning along a discrete path on a curved substrate using the calibrated deposition path cross section, the method further includes: The overlapping interference between sedimentary layer shapes is eliminated through Boolean operation.

5. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: The method of optimizing the mesh by using the angle refinement and adaptive method includes: For the initially divided mesh, refine the mesh with sharp corners and large curvature; The mesh density is adaptively adjusted according to the accuracy requirements of the geometric model. The higher the accuracy requirement, the greater the mesh density.

6. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: The boundary conditions include a heat transfer part and a stress part. The heat transfer part includes a heat radiation boundary, a heat convection boundary and a phase change latent heat boundary. The stress part includes an elastic stress boundary and a stress boundary generated by inelastic thermal strain and plastic strain.

7. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: The laser path is obtained by matching the discrete coordinate points of the simulated deposition path with the time variable based on the laser speed.

8. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 1, characterized in that: During the laser metal deposition simulation, the range of the laser action area is not less than the range of the deposition path cross-sectional size. As the laser action origin moves, it is determined whether the grid center point is within the laser action area. If so, the material properties of the grid unit are activated, otherwise they remain hidden.

9. The method for thermal-mechanical coupling simulation of robot-assisted curved surface laser metal deposition process according to claim 8, characterized in that: The laser action surface is set as the lower surface of the deposition path, and the direction of the laser beam is always perpendicular to the action surface.

10. A robot-assisted curved surface laser metal deposition process thermal-mechanical coupling simulation system, used to implement the thermal-mechanical coupling simulation method of claim 1; characterized in that: The thermal-mechanical coupling simulation system comprises: A deposition track cross-sectional dimension calibration module is used to calibrate the deposition track cross-sectional dimension; during the calibration process, two partially overlapping deposition tracks are used as references to obtain a rectangular calibration dimension, and half of the height and width of the rectangular calibration dimension are taken as the deposition track cross-sectional dimension; A geometric model building module is used to obtain a continuous simulated deposition path according to robot data, discretize the continuous path into several segments, and use the calibrated deposition path section to scan along the discrete path on the curved substrate to form a deposition layer shape, thereby obtaining a geometric model including the curved substrate and the deposition layer; The mesh optimization module is used to perform initial meshing of the geometric model and optimize the mesh using angle refinement and adaptive methods; A pre-processing module, which is used to set the material properties of the substrate and the deposited layer, boundary conditions and laser path, and pre-write the material properties of the substrate and the deposited layer in the deposited layer shape and hide them; The material deposition simulation and solution module is used to simulate laser metal deposition according to the laser path and boundary conditions. As the laser action origin moves, the material properties of the substrate and deposited layer in the laser action area are synchronously activated, and the evolution results of the stress field and temperature field of the curved surface laser metal deposition process that moves with the laser action area are calculated.

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