A real-time analysis method and system for sheet metal forming based on online data

Abstract

The present invention discloses a real-time analysis method and system for sheet metal forming based on online data, including using a node deformation displacement analysis model to calculate the full-field displacement data of the material based on the boundary displacement data of the sheet metal blank collected online, and on this basis using a formula to directly calculate the distribution data of the three-dimensional strain, wall thickness and stress field of the material, thereby realizing the synchronization of data analysis and sheet metal forming. The present invention uses a formula to directly obtain the physical information such as stress, strain, wall thickness, etc. inside the material based on the blank boundary displacement information and the sheet metal node deformation displacement analysis model in the sheet metal forming process. Compared with the finite element method, it does not need to perform stiffness matrix calculation, simplifies the operation, improves the calculation efficiency, and can perform real-time analysis of sheet metal deformation.

Description

Technical Field

[0001] The present invention relates to the technical field of sheet metal forming analysis and processing, and in particular to a sheet metal forming real-time analysis method and system based on online data. Background Art

[0002] Sheet metal forming can produce thin-walled parts with complex structures by plastically deforming metal materials through the action of molds. It has been widely used in aerospace, automobile and other fields. With the increasing application of lightweight and difficult-to-deform materials, the difficulty of sheet metal forming has gradually increased. On the other hand, the intensification of competition has led to increasing requirements for the surface quality, shape accuracy, and forming performance of sheet metal parts in the industry. These all restrict the improvement of the production capacity of complex sheet metal parts. By collecting the operating data of sheet metal forming and obtaining real-time information on sheet metal deformation during the forming process, it is possible to achieve precise control of process parameters and solve the processing and manufacturing problems of high-performance sheet metal parts.

[0003] In sheet metal forming, the forming of sheet metal parts is often simulated and predicted by establishing a multi-physics field coupled finite element model, and the cracking, wrinkling and springback problems that occur during the forming process are analyzed to achieve process optimization. At present, this technology is mature. Sheet metal forming is a complex nonlinear problem. Solving it involves a large number of stiffness matrix calculations, which is time-consuming and cannot be predicted in real time. At the same time, there are uncertain factors in the sheet metal forming process, such as fluctuations in equipment operating parameters, mold wear, etc. This optimization based on offline data cannot achieve precise control of the forming process. The patent with publication number CN114841028A proposes the use of multiple optical digital image sensors to track and record the flow of the sheet metal at multiple measured positions on the sheet metal during the forming process, but it is necessary to combine the material forming limit diagram to adjust the forming process parameters, and this method is only applicable to occasions where optical digital image sensors can be installed. Summary of the invention

[0004] In order to solve the problem that the existing technology is mainly focused on the inability to perform real-time analysis of material deformation during sheet metal forming, the present invention provides a real-time analysis method and system for sheet metal forming based on online data. Based on the real-time data of sheet metal boundary displacement during the forming process, a sheet metal node deformation displacement analysis model is used to obtain the deformation displacement of each node on the sheet metal, and then the real-time strain, stress and thickness of the sheet metal deformation are calculated, thereby avoiding the calculation of the stiffness matrix and realizing the real-time analysis of material deformation information during the sheet metal forming process.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A real-time analysis method for sheet metal forming based on online data, comprising the following steps:

[0007] S10. Online displacement preprocessing: preprocessing the acquired online sheet metal boundary displacement data;

[0008] S20. Sheet metal node deformation and displacement analysis: input the data processed in step S10 into the sheet metal node deformation and displacement analysis model to calculate the coordinates of each node in the sheet metal after deformation;

[0009] S30. Sheet metal forming analysis: Calculate the strain, thickness and stress distribution information of the sheet metal according to the coordinates of the deformed nodes output in step S20.

[0010] As a preferred solution of the present invention: the establishment of the sheet metal node deformation displacement analysis model in step S20 includes the following steps:

[0011] S201. Formulate sheet metal forming plan: set n groups of process parameters according to the requirements of the forming process;

[0012] S202. Trial production of sheet metal parts: Select a representative combination of process parameters in the scheme of step S201, conduct trial production of sheet metal parts, and collect data of sheet metal parts;

[0013] S203. Constructing a numerical simulation model: constructing a three-dimensional model of the sheet metal blank and the mold, meshing the model, setting a material model of the sheet metal blank, combining several groups of process parameters in step S202 as boundary conditions of the numerical simulation model, and performing numerical simulation, comparing the simulation results with the corresponding experimental results in step S202, and correcting the sheet metal numerical simulation model;

[0014] S204. Optimizing the numerical simulation model: Under the premise of ensuring the calculation accuracy, the number of grids of the numerical simulation model established in step S203 is optimized to reduce the calculation scale as much as possible. The number of units of the optimized numerical simulation model is k, the number of nodes is l, and the incremental step is m;

[0015] S205. Carry out numerical simulation: Use the numerical simulation model of step S204, set boundary conditions according to the forming scheme in step S201, and complete the numerical simulation solution of n sets of process parameters;

[0016] S206. Extract displacement data: according to the deformation characteristics of the sheet metal blank, select i boundary nodes on the sheet metal blank in the numerical simulation model built in step S204, extract their numbering information, and simultaneously extract the displacement information of the i boundary nodes of each incremental step of the n numerical simulation models in step S205, to obtain n×m groups of displacement data of the i nodes, extract the numbering information of l nodes in the numerical model of step S204, and simultaneously extract the coordinate information of l nodes of each incremental step of the n numerical simulation models in step S205, to obtain n×m groups of coordinate data of l nodes;

[0017] S207. Algorithm selection: Select the algorithm for node deformation and displacement prediction based on the characteristics of sheet metal forming and data features;

[0018] S208. Data processing: clearing invalid or erroneous data in the boundary displacement and node coordinate data extracted in step S206, and or normalizing the cleared data;

[0019] S209. Establish a node deformation and displacement analysis model: divide the data processed in step S208 into a training set and a test set, use the training set data to train the algorithm selected in step S207, establish a node deformation and displacement fitting model, use the test set data to evaluate the established node deformation and displacement fitting model, check the performance and accuracy of the fitting model, and optimize it to complete the establishment of the mapping relationship between the boundary displacement and the node deformation coordinates.

[0020] As a preferred solution of the present invention: the process parameters of the forming process solution in step S201 include key factors affecting sheet metal forming, and the setting range covers the feasible range of the process parameters.

[0021] As a preferred solution of the present invention: in step S203, the numerical simulation model uses shell elements to perform meshing of the sheet metal blank.

[0022] As a preferred solution of the present invention: the step S10 specifically comprises: fitting the collected online sheet metal boundary displacement data, and distributing the fitted boundary displacement to each boundary node selected in step S206.

[0023] As a preferred solution of the present invention: the step S30 is specifically as follows:

[0024] S301. Calculation of unit edge length: In one increment, three adjacent nodes A, B and C on any unit in the sheet metal are deformed to A1, B1 and C1. The coordinate of node A before deformation is (X a , Y a , Z a ), the coordinates of node B are (X b , Y b , Z b ), the coordinates of node C are (X c , Y c , Z c ), the lengths of the sides AB, AC, and BC

[0025]

[0026] are a, b and d respectively, then, by the same logic, the side lengths a1, b1 and d1 of A1B1, A1C1 and B1C1 after deformation can be obtained;

[0027] S302. Calculation of intermediate variables: Substitute a, b, and d obtained in step S301 into

[0028]

[0029] Obtain the intermediate variables for calculating the strain of node A before deformation. Similarly, the intermediate variables k1′ and k2′ for calculating the strain of node A1 after deformation can be obtained.

[0030] S303. Calculation of node principal strain increment: Substitute k1, k2, k1′ and k2′ obtained in step S302 into

[0031] and

[0032] The first principal strain increment and the second principal strain increment of point A are obtained, and Δε1 and Δε2 are substituted into Δε3=-(Δε1+Δε2) to obtain the third principal strain increment Δε3;

[0033] S304. Calculation of node principal strains: Integrate and accumulate the first principal strain increment Δε1, the second principal strain increment Δε2 and the third principal strain increment Δε3 obtained in step S303 to obtain the first principal strain ε1, the second principal strain ε2 and the third principal strain ε3;

[0034] S305. Calculation of node material thickness: Substitute the initial material thickness T0 of the sheet metal and the third principal strain ε3 calculated in step S304 into T=T0exp(ε3) to obtain the material thickness T of the node after deformation;

[0035] S306. Related calculations of the remaining nodes of the unit: repeat steps S301-S305 to respectively solve the three-dimensional principal strains ε1, ε2, and ε3 of the same unit node;

[0036] S307. Equivalent strain calculation: Calculate the average value of the first principal strain ε1, the second principal strain ε2 and the third principal strain ε3 of each node of the same unit obtained in step S304 and step S306, and then calculate the equivalent strain according to

[0037]

[0038] Solving for the equivalent strain

[0039] S308. Equivalent stress solution: For isotropic materials, the equivalent strain obtained in step S307 is Substitute the material model used in constructing the sheet metal numerical simulation model in step S203 to calculate the equivalent stress For anisotropic materials, first substitute the principal strain increment of node A obtained in step S303 into the formula Δσ=C:Δε, where C is the stiffness tensor of the sheet metal material, and solve for the principal stress increment Δσ. Then, use the material model used in constructing the sheet metal numerical simulation model in step S203 to solve for the equivalent stress.

[0040] S309. Repeat S301-S308 to obtain the deformation information of the remaining (k-1) units, and the overall deformation information of the sheet metal can be obtained.

[0041] A sheet metal forming real-time analysis system based on online data that adopts the sheet metal forming real-time analysis method based on online data, comprising any one of the sheet metal forming real-time analysis methods based on online data described above: a data acquisition unit, a data processing unit, a sheet metal forming unit, a forming analysis unit, and a data display unit, wherein the data acquisition unit acquires data of the sheet metal forming unit in a contact or non-contact manner, the output end of the data acquisition unit is electrically connected to the input end of the data processing unit, the output end of the data processing unit is electrically connected to the input end of the forming analysis unit, and the output end of the forming analysis unit is electrically connected to an analysis result display unit.

[0042] As a preferred solution of the present invention: the sheet metal forming unit includes sheet metal forming equipment, a mold and a formed sheet metal blank.

[0043] As a preferred solution of the present invention: the data acquisition unit is used to collect boundary displacement data of the sheet metal blank; the data processing unit is used to process the sheet metal online data collected by the data acquisition unit to generate input data for the forming analysis unit; the forming analysis unit is used to predict the sheet metal forming data; the data display unit is used to display the sheet metal forming data predicted by the forming analysis unit.

[0044] As a preferred solution of the present invention: the forming analysis unit includes a memory, a processor and a computer program, the computer program is stored in the memory, and when the computer program is executed by the processor, the above-mentioned real-time analysis method of sheet metal forming based on online data is implemented.

[0045] The beneficial effects brought by the present invention are:

[0046] 1. Based on the calculation of the deformation displacement of each node in the sheet metal by using the blank boundary displacement information and the sheet metal node deformation displacement analysis model during the sheet metal forming process, the formula is used to directly calculate the physical information such as stress, strain, wall thickness, etc. inside the material. Compared with the finite element method, it does not require stiffness matrix calculation, simplifies the calculation, improves the calculation efficiency, can perform real-time analysis of sheet metal deformation, and can be used for closed-loop control of sheet metal forming quality;

[0047] 2. Use the blank boundary displacement information during sheet metal forming to perform real-time analysis of sheet metal forming, which is suitable for the complex and changeable forming environment of sheet metal forming;

[0048] 3. The use of online data of sheet metal forming can reflect the impact of uncertain factors such as the fluctuation of forming equipment loading and the wear of tools and dies during the sheet metal forming process, which is conducive to improving the accuracy of sheet metal deformation analysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic diagram of the T-type tee hydraulic forming proposed by the present invention;

[0050] Figure 2 Schematic diagram of the T-type tee hydroforming numerical simulation model before and after optimization.

[0051] Figure 3 Schematic diagram of the unit and node before and after deformation;

[0052] Figure 4 It is a structural diagram of the data acquisition unit.

[0053] In the figure: 1. data acquisition unit; 2. data processing unit; 3. sheet metal forming unit; 31. sheet metal forming equipment; 32. mold; 33. tee blank; 4. forming analysis unit; 41. memory; 42. processor; 43. computer program; 5. data display unit; 10. tee branch pipe; 101 main pipe; 102. boundary node; 103. left push rod; 104. cavity; 105. ejector rod; 106. tee main pipe; 107. right push rod. DETAILED DESCRIPTION

[0054] Please refer to the instruction manual Figure 1-Figure 4 As shown:

[0055] This embodiment is a real-time analysis method based on online data for T-type tee 4 hydroforming, comprising the following steps:

[0056] S10. Preprocess the online displacement data of the three-way main pipe 106 and the three-way branch pipe 10;

[0057] The specific steps of step S10 are as follows: fitting the collected online displacement data at the three-way main pipe 106, distributing the fitted boundary displacement to the 34 boundary nodes 102 selected in step S206, and applying the collected online data at the three-way branch pipe 10 to the selected one boundary node 102, such as Figure 1 shown.

[0058] S20. Input the processed data into the sheet metal node deformation displacement analysis model to calculate the deformation displacement of 1435 nodes of the sheet metal;

[0059] The process of establishing the sheet metal node deformation displacement analysis model in step S20 is as follows:

[0060] S201. According to the requirements of the forming process, 64 sets of process parameters are set. The tee forming process scheme of step S201 adopts a comprehensive experimental scheme. The process parameters are two key factors affecting the tee forming, namely, the pressure rise time t and the forming pressure P. The pressure rise time t has 9 levels, namely, 3s, 6s, 9s, 12s, 15s, 18s, 21s and 24s, covering the minimum value of 3s and the maximum value of 24s of the pressure rise time. The forming pressure P has 8 levels, namely, 15MPa, 25MPa, 35MPa, 45MPa, 55MPa, 65MPa, 75MPa and 85MPa, covering the minimum value of 15MPa and the maximum value of 85MPa of the forming pressure.

[0061] S202. In the scheme of step S201, 9 representative process parameter combinations are selected, namely 3s-15MPa, 3s-55MPa, 3s-85MPa, 18s-15MPa, 18s-55MPa, 18s-85MPa, 24s-15MPa, 24s-55MPa and 24s-85MPa to carry out trial production of TA2 tee hydroforming, and use a 3D scanner to measure the wall thickness data of the T-type tee;

[0062] S203. Construct a three-dimensional model of the tee blank 33, the left push rod 103, the right push rod 107, the ejector rod 105 and the cavity 104, and mesh the model. After the tee blank is meshed, a total of 5440 units and 5520 nodes are obtained. The material model of TA2 of the tee is set, and the 9 sets of process parameter combinations in step S202 are used as the boundary conditions of the numerical simulation model for numerical simulation. The wall thickness of the simulation result is compared with the wall thickness obtained from the corresponding experiment in step S202. The maximum wall thickness deviation between the two exceeds 8%. The friction coefficient and other parameters of the numerical simulation model are adjusted to control the wall thickness deviation to within 5%;

[0063] Step S203: the numerical simulation model uses four-node shell elements to perform mesh division on the sheet metal blank;

[0064] S204. Considering the symmetry of the tee part, take one quarter of the blank for simulation and set the boundary conditions on the symmetry plane, such as Figure 2 As shown, in order to reduce the calculation scale as much as possible, the number of elements of the optimized billet is reduced to 1360, the number of nodes is reduced to 1435, and the incremental step is 52;

[0065] S205. Using the numerical simulation model of step S204, setting boundary conditions according to the forming scheme in step S201, and completing the solution of the numerical simulation model of 64 sets of process parameters;

[0066] S206. According to the deformation characteristics of the sheet metal blank, the 35 boundary nodes of the sheet metal blank 4 in contact with the push rod and the 1 boundary node in contact with the ejector rod in the numerical model of step S204 are as follows: Figure 1 As shown, the numbering information is extracted, and at the same time, the displacement information of 36 boundary nodes is extracted in 52 incremental steps in 64 numerical simulation models in step S205, and 3328 groups of displacement data of 36 nodes are obtained. The numbering information of 1435 nodes is extracted in the numerical model in step S204, and at the same time, the coordinate information of 1435 nodes is extracted in 52 incremental steps in 64 numerical simulation models in step S205, and 3328 groups of coordinate data of 1435 nodes are obtained;

[0067] S207. Selecting XGBoost algorithm as the algorithm for node deformation and displacement prediction according to the characteristics of sheet metal forming and data features;

[0068] S208. Clear the data of the blank that collapsed in step S206;

[0069] S209. The data processed in step S208 is divided into a training set and a test set in a ratio of 80%:20%. The XGBoost algorithm selected in step S207 is trained using 2662 sets of training set data to establish a node deformation displacement fitting model. The established node deformation displacement fitting model is evaluated using 666 sets of test set data. The performance and accuracy of the model are checked using standard deviation analysis, and the model is optimized to complete the establishment of the mapping relationship between the boundary node displacement and the deformation node displacement.

[0070] S30. Calculate the displacement, strain, stress and thickness distribution of 1360 units in the current sheet metal according to the deformation and displacement of 1435 nodes;

[0071] Step S30 is specifically as follows:

[0072] S301. Calculation of unit edge length: In one increment, any unit in the sheet metal is deformed, and the three adjacent nodes A, B and C on the unit are deformed to A1, B1 and C1, such as Figure 3 As shown, the coordinates of node A before deformation are (X a , Y a , Z a ), the coordinates of node B are (X b , Y b , Z b ), the coordinates of node C are (X c , Y c, Z c ), the lengths of the sides AB, AC, and BC can be calculated using formula (1).

[0073]

[0074] Where: a, b and d are the lengths of the sides of AB, AC and BC respectively.

[0075] The same method can be used to calculate the side lengths a1, b1 and d1 of A1B1, A1C1 and B1C1 after deformation;

[0076] S302. Formula (2) can be used to calculate the intermediate variables k1 and k2 for solving the strain of node A before deformation.

[0077]

[0078] Where: a, b and d are the side lengths of AB, AC and BC respectively. The same method can be used to obtain the intermediate variables k1′ and k2′ for solving the strain of node A1 after deformation;

[0079] S303. The first principal strain increment and the second principal strain increment of node A can be obtained by using formula (3) and formula (4).

[0080]

[0081]

[0082] Where: k1 and k2 are the intermediate variables for calculating the node strain before deformation, k1′ and k2′ are the intermediate variables for calculating the node strain after deformation. Formula (5) is used to calculate the third principal strain increment of node A.

[0083] Δε3=-(Δε1+Δε2) Formula (5)

[0084] Where: Δε1 and Δε2 are the first principal strain increment and the second principal strain increment of the node;

[0085] S304. Calculate the first principal strain increment Δε of node A obtained in step S303 1A , the second principal strain increment Δε 2A and the three principal strain increments Δε 3A Integrate and accumulate to solve the first principal strain ε of node A 1A , the second principal strain ε 2A and the third principal strain ε 3A ;

[0086] S305. Formula (6) can be used to calculate the material thickness T of the node after deformation.

[0087] T=T0exp(ε3) Formula (6)

[0088] Where: T0 is the initial thickness of the sheet metal,

[0089] ε3 is the third principal strain;

[0090] S306. Repeat steps S301-S305 to respectively solve the three-dimensional principal strains ε of the same unit node B, C and D 1B , ε 2B , ε 3B , ε 1C , ε 2C , ε 3C , ε 1D , ε 2D , ε 3D ;

[0091] S307. Using formula (7), the equivalent strain can be solved

[0092]

[0093] Where: ε1=(ε 1A +ε 1B +ε 1C +ε 1D ) / 4,

[0094] ε2=(ε 2A +ε 2B +ε 2C +ε 2D ) / 4,

[0095] ε3=(ε 3A +ε 3B +ε 3C +ε 3D ) / 4;

[0096] S308.TA2 is an anisotropic material. First, substitute the node principal strain increment obtained in step S303 into the formula Δσ=C:Δε, where C is the stiffness tensor of the sheet metal material, and solve for the principal stress increment Δσ. Then use formula (8) input in S203 to solve for the equivalent stress

[0097]

[0098] Where: y is the yield stress, S, K, h, ε0, ε s , a, t are fitting material constants, ε p For equivalent

[0099] Plastic strain;

[0100] S309. Repeat steps S301-S308 to obtain the deformation information of the remaining 1359 units, and the overall deformation information of the sheet metal can be obtained.

[0101] Correspondingly, the present invention also provides a real-time analysis system for forming a TA2 tee, comprising: a data acquisition unit 1, a data processing unit 2, a sheet metal forming unit 3, a forming analysis unit 4, and a data display unit 5, wherein the data acquisition unit 1 uses a displacement sensor to collect displacement information at the tee main pipe in the sheet metal forming unit 3, and uses an optical sensor to collect data on displacement information at the branch pipe, the output end of the data acquisition unit 1 is electrically connected to the input end of the data processing unit 2, the output end of the data processing unit 2 is electrically connected to the input end of the forming analysis unit 4, and the output end of the forming analysis unit 4 is electrically connected to the analysis result display unit 5;

[0102] The sheet metal forming unit 3 comprises a sheet metal forming device 31, a die 32 and a formed sheet metal blank 33;

[0103] The data acquisition unit 1 is used to collect the online data of the displacement of the main pipe and the branch pipe of the tee blank 33; the data processing unit 2 is used to process the online data collected by the data acquisition unit 1 to generate input data for the forming analysis unit 4; the forming analysis unit 4 is used to predict the sheet metal forming data; the data display unit 5 is used to display the sheet metal forming data predicted by the forming analysis unit 4;

[0104] The forming analysis unit 4 includes a memory 41 , a processor 42 , and a computer program 43 . The computer program 43 is stored in the memory 41 . When the computer program 43 is executed by the processor 42 , any of the above methods is implemented.

[0105] The above are only preferred specific implementation modes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A real-time analysis method for sheet metal forming based on online data, characterized in that: The specific process of the method is as follows: S10. Online displacement preprocessing: preprocessing the acquired online sheet metal boundary displacement data; S20. Sheet metal node deformation and displacement analysis: input the data processed in step S10 into the sheet metal node deformation and displacement analysis model to calculate the coordinates of each node in the sheet metal after deformation; S30. Sheet metal forming analysis: Calculate the strain, thickness and stress distribution information of the sheet metal according to the coordinates of the deformed nodes output in step S20.

2. The real-time analysis method for sheet metal forming based on online data according to claim 1, characterized in that: The process of establishing the deformation node displacement analysis model in step S20 is as follows: S201. Formulate sheet metal forming plan: set n groups of process parameters according to the requirements of the forming process; S202. Trial production of sheet metal parts: Select a representative combination of process parameters in the scheme of step S201, conduct trial production of sheet metal parts, and collect data of sheet metal parts; S203. Constructing a numerical simulation model: constructing a three-dimensional model of the sheet metal blank and the mold, meshing the model, setting a material model of the sheet metal blank, combining several groups of process parameters in step S202 as boundary conditions of the numerical simulation model, and performing numerical simulation, comparing the simulation results with the corresponding experimental results in step S202, and correcting the sheet metal numerical simulation model; S204. Optimizing the numerical simulation model: Under the premise of ensuring the calculation accuracy, the number of grids of the numerical simulation model established in step S203 is optimized, and the number of units of the optimized numerical simulation model is k, the number of nodes is l, and the incremental step is m; S205. Carry out numerical simulation: Use the numerical simulation model of step S204, set boundary conditions according to the forming scheme in step S201, and complete the numerical simulation solution of n sets of process parameters; S206. Extract displacement data: according to the deformation characteristics of the sheet metal blank, select i boundary nodes on the sheet metal blank in the numerical simulation model built in step S204, extract their numbering information, and simultaneously extract the displacement information of the i boundary nodes of each incremental step of the n numerical simulation models in step S205, to obtain n×m groups of displacement data of the i nodes, extract the numbering information of l nodes in the numerical model of step S204, and simultaneously extract the coordinate information of l nodes of each incremental step of the n numerical simulation models in step S205, to obtain n×m groups of coordinate data of l nodes; S207. Algorithm selection: Select the algorithm for node deformation and displacement prediction based on the characteristics of sheet metal forming and data features; S208. Data processing: clearing invalid or erroneous data in the boundary displacement and node coordinate data extracted in step S206, and or normalizing the cleared data; S209. Establish a node deformation and displacement analysis model: divide the data processed in step S208 into a training set and a test set, use the training set data to train the algorithm selected in step S207, establish a node deformation and displacement fitting model, use the test set data to evaluate the established node deformation and displacement fitting model, check the performance and accuracy of the fitting model, and optimize it to complete the establishment of the mapping relationship between the boundary displacement and the node deformation coordinates.

3. The real-time analysis method of sheet metal forming based on online data according to claim 2 is characterized in that: The process parameters of step S201 include key factors that affect sheet metal forming, and the setting range covers the feasible range of the process parameters.

4. The real-time analysis method of sheet metal forming based on online data according to claim 2 is characterized in that: The numerical simulation model in step S203 uses shell elements to perform meshing of the sheet metal blank.

5. A real-time analysis method for sheet metal forming based on online data according to claim 1 or 2, characterized in that: The step S10 specifically includes: fitting the collected online sheet metal boundary displacement data, and distributing the fitted boundary displacement to each boundary node selected in step S206.

6. The real-time analysis method of sheet metal forming based on online data according to claim 1 is characterized in that: The step S30 is specifically as follows: S301. Calculation of unit edge length: In one increment, three adjacent nodes A, B and C on any unit in the sheet metal are deformed to A1, B1 and C1. The coordinate of node A before deformation is (X a , Y a , Z a ), the coordinates of node B are (X b , Y b , Z b ), the coordinates of node C are (X c , Y c , Z c ), the lengths of the sides of AB, AC, and BC are a, b, and d respectively. Similarly, the side lengths a1, b1 and d1 of A1B1, A1C1 and B1C1 after deformation can be obtained; S302. Calculation of intermediate variables: Substitute a, b, and d obtained in step S301 into Obtain the intermediate variables for calculating the strain of node A before deformation. Similarly, the intermediate variables k1′ and k2′ for calculating the strain of node A1 after deformation can be obtained. S303. Calculation of node principal strain increment: Substitute k1, k2, k1′ and k2′ obtained in step S302 into and The first principal strain increment and the second principal strain increment of point A are obtained, and Δε1 and Δε2 are substituted into Δε3=-(Δε1+Δε2) to obtain the third principal strain increment Δε3; S304. Calculation of node principal strains: Integrate and accumulate the first principal strain increment Δε1, the second principal strain increment Δε2 and the third principal strain increment Δε3 obtained in step S303 to obtain the first principal strain ε1, the second principal strain ε2 and the third principal strain ε3; S305. Calculation of node material thickness: Substitute the initial material thickness T0 of the sheet metal and the third principal strain ε3 calculated in step S304 into T=T0exp(ε3) to obtain the material thickness T of the node after deformation; S306. Related calculations of the remaining nodes of the unit: repeat steps S301-S305 to respectively solve the three-dimensional principal strains ε1, ε2, and ε3 of the same unit node; S307. Equivalent strain calculation: Calculate the average value of the first principal strain ε1, the second principal strain ε2 and the third principal strain ε3 of each node of the same unit obtained in step S304 and step S306, and then calculate the equivalent strain according to Solving for the equivalent strain S308. Equivalent stress solution: For isotropic materials, the equivalent strain obtained in step S307 is Substitute the material model used in constructing the sheet metal numerical simulation model in step S203 to calculate the equivalent stress For anisotropic materials, first substitute the principal strain increment of node A obtained in step S303 into the formula Δσ=C:Δε, where C is the stiffness tensor of the sheet metal material, and solve for the principal stress increment Δσ. Then, use the material model used in constructing the sheet metal numerical simulation model in step S203 to solve for the equivalent stress. S309. Repeat S301-S308 to obtain the deformation information of the remaining (k-1) units, and the overall deformation information of the sheet metal can be obtained.

7. A real-time analysis system for sheet metal forming based on online data, comprising a real-time analysis method for sheet metal forming based on online data as described in any one of claims 1 to 6, characterized in that The system comprises: a data acquisition unit (1), a data processing unit (2), a sheet metal forming unit (3), a forming analysis unit (4), and a data display unit (5); the data acquisition unit (1) acquires data of the sheet metal forming unit (3) in a contact or non-contact manner; the output end of the data acquisition unit (1) is electrically connected to the input end of the data processing unit (2); the output end of the data processing unit (2) is electrically connected to the input end of the forming analysis unit (4); and the output end of the forming analysis unit (4) is electrically connected to the analysis result display unit (5).

8. The real-time analysis system for sheet metal forming based on online data according to claim 7 is characterized by: The sheet metal forming unit (3) comprises sheet metal forming equipment (31), a mould (32) and a formed sheet metal blank (33).

9. A real-time analysis system for sheet metal forming based on online data according to claim 7 or 8, characterized in that: The data acquisition unit (1) is used to acquire boundary displacement data of a sheet metal blank (33); the data processing unit (2) is used to process online data acquired by the data acquisition unit (1) to generate input data for a forming analysis unit (4); the forming analysis unit (4) is used to predict sheet metal forming data; and the data display unit (5) is used to display the sheet metal forming data predicted by the forming analysis unit (4).

10. According to a real-time analysis system for sheet metal forming based on online data as described in claim 7 or 8, the forming analysis unit (4) includes a memory (41), a processor (42) and a computer program (43), and the computer program (43) is stored in the memory (41). When the computer program (43) is executed by the processor (42), the method described in any one of claims 1 to 6 is implemented.

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