Spherical tank shell blanking method based on stamping forming inversion algorithm

Abstract

The present invention proposes a spherical tank shell plate blanking method based on a stamping forming inversion algorithm, statistically analyzes a large amount of stamping forming data of the spherical tank shell plate, combines actual production data with simulation through three-dimensional modeling software and finite element software, simulates the stamping process, and fits the model data on the basis of the simulation forming model to screen out abnormal data, and then fits the screened model data for inversion calculation to obtain an empirical formula corresponding to the material and size of the spherical tank, and calculates the size of the spherical tank shell plate blank for stamping processing with the empirical formula; the present invention generates a spherical tank shell plate stamping animation by generating stamping displacement, stress and strain cloud maps, so that the stamping process of the entire spherical shell plate can be intuitively observed, the real-time changes of displacement, stress and strain with mold stamping can be obtained, and the one-time blanking size of the spherical shell plate can be obtained, so as to provide reference and guidance for the actual production and processing of the spherical shell plate and improve production efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of stamping processing, in particular to a spherical tank shell plate blanking method based on a stamping forming inversion algorithm. Background Art

[0002] Spherical tanks have the advantages of low steel consumption, small footprint, good stress resistance, high pressure bearing capacity, can be transported to the site in pieces for installation and forming, and the volume size is basically not restricted by transportation. They are widely used in the fields of petroleum, chemical industry, urban gas, metallurgy, etc. At present, spherical tanks are developing in the direction of large-scale, diversified structures, and high parameters. Many high-parameter spherical tanks have been domestically produced, making positive contributions to my country's economic development. The economic benefits of large-scale spherical tanks are very obvious, but on the way to large-scale development, they are restricted by different factors at different times.

[0003] At present, the most common stamping forming method is cold forming, which accounts for more than 90% of the forming of spherical tanks. Cold forming is the process of stamping and deforming steel plates into spherical shell plates at room temperature. At present, the cold forming technology of spherical tanks at home and abroad mainly relies on the experience of manufacturers. Based on the accumulation of years of experience, a certain experience database has been formed, and the curvature of the mold is determined based on experience in production and manufacturing. Therefore, the accuracy and production efficiency of cold-pressed spherical pieces from different manufacturers vary greatly. Foreign countries started research on large-scale manufacturing technology of spherical tanks earlier, and the manufacturing technology and precision control of large-petal spherical tanks are relatively mature. Domestic large-scale manufacturing technology has also developed rapidly. In recent years, there have been many research works on spherical tank manufacturing technology, including blanking technology, large petals, thin plate pressing technology, etc., but the manufacturing accuracy of extra-large petals (over 30m2) has not been fully mastered.

[0004] From the data analysis, there are simulation studies on the forming process of large heads, but there are few simulation studies on parameters such as different mold diameters, different steel materials, different loads, and different stamping schemes in the pressing and forming of spherical shell plates at home and abroad, and there are few data and research results on the one-time blanking method of spherical shell plates. Due to the problems of manufacturing accuracy, the blanking deviation and material waste, the assembly operation is difficult, the angular deformation and misalignment are serious, and the spherical tank has a large residual stress. Summary of the invention

[0005] The present invention proposes a spherical tank shell plate blanking method based on a stamping forming inversion algorithm, performs statistical analysis on a large amount of stamping forming data of the spherical tank shell plate (such as the diameter, thickness, material stiffness, yield strength and stamping deformation of the spherical tank shell plate), combines the actual production data with simulation through three-dimensional modeling software and finite element software, generates stamping displacement, stress and strain cloud maps by stamping forming simulation, and generates a spherical shell plate stamping animation, so that the stamping process of the entire spherical shell plate can be observed intuitively, the real-time changes of displacement, stress and strain with the stamping of the mold can be obtained, and the one-time blanking size of the spherical shell plate blank can be obtained, so as to provide reference and guidance for the actual production and processing of the spherical shell plate and improve production efficiency.

[0006] The present invention adopts the following technical solutions.

[0007] The spherical tank shell plate blanking method based on the stamping inversion algorithm is based on a statistical analysis of a large amount of stamping forming data of spherical tank shell plates in actual production (such as spherical tank diameter, thickness, material stiffness, yield strength and stamping deformation, etc.), and then combined with 3D modeling and finite element analysis, and the actual production data is combined with simulation through 3D modeling software and finite element software to simulate the stamping process. On the basis of the simulated forming model, the model data is fitted to screen out abnormal data, and then the screened model data is further fitted and inverted to obtain the empirical formula corresponding to the material and size of the spherical tank, and the size of the spherical tank shell plate blank used for stamping is calculated by the empirical formula.

[0008] The blanking method comprises the following steps:

[0009] Step S1, constructing a three-dimensional model of each spherical shell plate constituting the spherical tank based on Solidworks;

[0010] Step S2, using the one-step forming module of UG to analyze and process the three-dimensional models of each spherical shell plate to obtain the blank plate model required for stamping simulation forming;

[0011] Step S3, based on Solidworks, according to the corresponding characteristic dimensions of the blank plate model and the corresponding spherical shell plate three-dimensional model, establish the spherical shell plate stamping die required for stamping process simulation;

[0012] Step S4, dividing the blank plate model into blocks;

[0013] Step S5, assembling the divided blank plate model and the spherical shell plate stamping die based on Solidworks, and exporting the assembly into *.xt format;

[0014] Step S6, importing the *.xt format model into ANSYS Workbench, setting material parameters, contact conditions, boundary conditions and meshing, and then calculating and solving the assembly model after pre-processing;

[0015] Step S7, processing the solution results in ANSYS Workbench to generate a stamping simulation result model with a grid;

[0016] Step S8, exporting the gridded blank plate model and the stamping simulation result model with the grid into *.STL format, and using Solidworks to read the exported models respectively;

[0017] Step S9, using the dimension measurement and evaluation function of Solidworks, setting the center origin of the blank plate model and the spherical shell plate model, and under the premise of maintaining a one-to-one correspondence, respectively measuring the coordinates of each grid point of the blank plate model and the spherical shell plate model and the chord length from the center origin, and performing statistics on the measurement data;

[0018] Step S10, obtaining the longitude and latitude of the spherical coordinates of each point after deformation by geometric relationship, and establishing the initial corresponding relationship between the chord length of the blank plate and the spherical coordinates of the spherical shell plate;

[0019] Step S11, taking each grid point of the spherical shell plate model as the sample point of the curved spherical shell plate model, preliminarily screening the sample points according to the measurement data, and deleting abnormal points;

[0020] Step S12, performing curve fitting on each column of the screened data in MATLAB, deleting the prominent abnormal points in each column, and obtaining the screened data;

[0021] Step S13, after data screening, perform surface fitting on each column of data in MATLAB, and then delete the points where the calculated results differ greatly from the actual values;

[0022] Step S14, based on the above fitting, the data points of the spherical shell plates at different parts of the spherical tank and the corresponding blank plate surface are run and calculated in MATLAB to repeatedly correct the initial corresponding relationship between the chord length of the blank plate and the spherical surface coordinates of the spherical shell plate, until the difference between the calculation result and the actual value reaches a certain error range, and the corrected empirical formula is obtained;

[0023] Step S14, using the modified empirical formula, based on the known parameters of the spherical tank and the spherical shell plate, calculate the size of the blank plate used for actual stamping processing.

[0024] In step S7, the solution results are processed in ANSYS Workbench to generate displacement, stress and strain cloud diagrams, and generate animations corresponding to the results.

[0025] In step S11, the method for preliminarily screening and deleting outliers is as follows: if the coordinate deviation of a point is too large compared with the adjacent points, the point is evaluated as an outlier, selected and deleted.

[0026] In step S12 and step S13, each column of data is data at the same longitude of the curved spherical shell plate model.

[0027] When constructing the spherical tank and the spherical shell plate of the upper temperate zone in step S1, the parameters required for constructing the spherical shell plate three-dimensional model include: spherical tank diameter, spherical tank wall thickness, number of spherical shell zones, center angle of each zone and number of blocks of each zone.

[0028] The specific steps of step S2 are: importing the spherical shell plate three-dimensional model, extracting the mid-plane to divide the grid, generating the blank contour, and stretching to generate the blank plate model.

[0029] The corresponding characteristic dimensions in step S3 include the diagonal length of the blank plate, the arc length of each side of the 3D model of the spherical shell plate, the diagonal chord length of the spherical shell plate, and the thickness of the blank plate;

[0030] In step S4, during the block processing, the block division method is to take the midpoints of each side of the blank plate, connect the midpoints of the opposite sides, and then divide the blocks.

[0031] The specific method of step S6 is to set the mold as a rigid body; the contact condition is to take the friction contact between the surface of the blank plate and the surface of the stamping mold, and set the corresponding friction coefficient; the boundary condition is to take the convex mold fixed and the concave mold moving; the grid division method is hexahedral grid, and the grid size is selected according to the corresponding spherical tank shell plate and stamping die size.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The present invention starts from the stamping forming inversion algorithm and can realize accurate blanking of spherical tank shell plates in one time. The main technical scheme includes four major parts. (1) Establishment of spherical tank shell plate stamping model (2) Simulation of spherical tank shell plate stamping simulation process (3) Spherical tank shell plate forming inversion calculation (4) Determination of the spherical tank shell plate blank plate lofting and blanking dimensions. The present invention simulates the spherical tank shell plate stamping forming, and performs inversion calculation based on the results to obtain the spherical tank shell plate blank plate lofting and blanking dimensions, thereby realizing accurate blanking of spherical tank shell plates in one time. It can be combined with actual production to provide reference and guidance for actual production and processing, thereby improving the actual production and processing technology, saving production materials, and improving production efficiency.

[0034] The present invention generates stamping displacement, stress and strain cloud maps, generates spherical shell plate stamping animation, can visually observe the stamping process of the entire spherical shell plate, can obtain the real-time changes of displacement, stress and strain with the stamping of the mold, can obtain the one-time cutting size of the spherical shell plate blank, can provide reference and guidance for the actual production and processing of the spherical shell plate, and improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0036] Attached Figure 1 It is a schematic diagram of the process of the present invention;

[0037] Attached Figure 2 is a schematic diagram of step S1 constructing a spherical tank and an upper temperate zone spherical shell plate (taking the upper temperate zone as an example);

[0038] Attached Figure 3 is another schematic diagram of step S1 constructing an upper temperate spherical shell plate (taking the upper temperate zone as an example);

[0039] Attached Figure 4 is a schematic diagram of generating an upper temperate zone blank plate model in step S2;

[0040] Attached Figure 5 is a schematic diagram of the block division of the blank plate model in step S4;

[0041] Attached Figure 6 is a schematic diagram of the assembly involved in step S5;

[0042] Attached Figure 7 is a schematic diagram of the solution result obtained in step S7;

[0043] Attached Figure 8 is a schematic diagram of the blank plate model after meshing in step S8;

[0044] Attached Fig. 9 is a schematic diagram of the blank sheet stamping result model after the grid is divided in step S8;

[0045] Attached Fig.10 is a schematic diagram of a method for measuring grid point coordinates involved in step S9. DETAILED DESCRIPTION

[0046] As shown in the figure, the spherical tank shell plate blanking method based on the stamping inversion algorithm performs statistical analysis on a large amount of stamping forming data of the spherical tank shell plate (such as the diameter, thickness, material stiffness, yield strength and stamping deformation of the spherical tank), and combines the actual production data with simulation through 3D modeling software and finite element software. The stamping process is simulated first, and then the model data is fitted on the basis of the simulated forming model to filter out abnormal data. The filtered model data is further fitted and inverted to obtain the empirical formula corresponding to the material and size of the spherical tank, and the size of the spherical tank shell plate blank used for stamping is calculated by the empirical formula.

[0047] The blanking method comprises the following steps:

[0048] Step S1, constructing a three-dimensional model of each spherical shell plate constituting the spherical tank based on Solidworks;

[0049] Step S2, using the one-step forming module of UG to analyze and process the three-dimensional models of each spherical shell plate to obtain the blank plate model required for stamping simulation forming;

[0050] Step S3, based on Solidworks, according to the corresponding characteristic dimensions of the blank plate model and the corresponding spherical shell plate three-dimensional model, establish the spherical shell plate stamping die required for stamping process simulation;

[0051] Step S4, dividing the blank plate model into blocks;

[0052] Step S5, assembling the divided blank plate model and the spherical shell plate stamping die based on Solidworks, and exporting the assembly into *.xt format;

[0053] Step S6, importing the *.xt format model into ANSYS Workbench, setting material parameters, contact conditions, boundary conditions and meshing, and then calculating and solving the assembly model after pre-processing;

[0054] Step S7, processing the solution results in ANSYS Workbench to generate a stamping simulation result model with a grid;

[0055] Step S8, exporting the gridded blank plate model and the stamping simulation result model with the grid into *.STL format, and using Solidworks to read the exported models respectively;

[0056] Step S9, using the dimension measurement and evaluation function of Solidworks, setting the center origin of the blank plate model and the spherical shell plate model, and under the premise of maintaining a one-to-one correspondence, respectively measuring the coordinates of each grid point of the blank plate model and the spherical shell plate model and the chord length from the center origin, and performing statistics on the measurement data;

[0057] Step S10, obtaining the longitude and latitude of the spherical coordinates of each point after deformation by geometric relationship, and establishing the initial corresponding relationship between the chord length of the blank plate and the spherical coordinates of the spherical shell plate;

[0058] Step S11, taking each grid point of the spherical shell plate model as the sample point of the curved spherical shell plate model, preliminarily screening the sample points according to the measurement data, and deleting abnormal points;

[0059] Step S12, performing curve fitting on each column of the screened data in MATLAB, deleting the prominent abnormal points in each column, and obtaining the screened data;

[0060] Step S13, after data screening, perform surface fitting on each column of data in MATLAB, and then delete the points where the calculated results differ greatly from the actual values;

[0061] Step S14, based on the above fitting, the data points of the spherical shell plates at different parts of the spherical tank and the corresponding blank plate surface are run and calculated in MATLAB to repeatedly correct the initial corresponding relationship between the chord length of the blank plate and the spherical surface coordinates of the spherical shell plate, until the difference between the calculation result and the actual value reaches a certain error range, and the corrected empirical formula is obtained;

[0062] Step S14, using the modified empirical formula, based on the known parameters of the spherical tank and the spherical shell plate, calculate the size of the blank plate used for actual stamping processing.

[0063] In step S7, the solution results are processed in ANSYS Workbench to generate displacement, stress and strain cloud diagrams, and generate animations corresponding to the results.

[0064] In step S11, the method for preliminarily screening and deleting outliers is as follows: if the coordinate deviation of a point is too large compared with the adjacent points, the point is evaluated as an outlier, selected and deleted.

[0065] In step S12 and step S13, each column of data is data at the same longitude of the curved spherical shell plate model.

[0066] When constructing the spherical tank and the spherical shell plate of the upper temperate zone in step S1, the parameters required for constructing the spherical shell plate three-dimensional model include: spherical tank diameter, spherical tank wall thickness, number of spherical shell zones, center angle of each zone and number of blocks of each zone.

[0067] The specific steps of step S2 are: importing the spherical shell plate three-dimensional model, extracting the mid-plane to divide the grid, generating the blank contour, and stretching to generate the blank plate model.

[0068] The corresponding characteristic dimensions in step S3 include the diagonal length of the blank plate, the arc length of each side of the 3D model of the spherical shell plate, the diagonal chord length of the spherical shell plate, and the thickness of the blank plate;

[0069] In step S4, during the block processing, the block division method is to take the midpoints of each side of the blank plate, connect the midpoints of the opposite sides, and then divide the blocks.

[0070] The specific method of step S6 is to set the mold as a rigid body; the contact condition is to take the friction contact between the surface of the blank plate and the surface of the stamping mold, and set the corresponding friction coefficient; the boundary condition is to take the convex mold fixed and the concave mold moving; the grid division method is hexahedral grid, and the grid size is selected according to the corresponding spherical tank shell plate and stamping die size.

Claims

1. A spherical tank shell blanking method based on a stamping inversion algorithm performs statistical analysis on a large amount of stamping data of spherical tank shells, and combines actual production data with simulation through 3D modeling software and finite element software, which is characterized by: The stamping process is simulated. Based on the simulated model, the model data is fitted to filter out abnormal data. The filtered model data is further fitted and inverted to obtain the empirical formula corresponding to the material and size of the spherical tank. The size of the spherical tank shell blank used for stamping is calculated with the empirical formula. The blanking method comprises the following steps: Step S1, constructing a three-dimensional model of each spherical shell plate constituting the spherical tank based on Solidworks; Step S2, using the one-step forming module of UG to analyze and process the three-dimensional models of each spherical shell plate to obtain the blank plate model required for stamping simulation forming; Step S3, based on Solidworks, according to the corresponding characteristic dimensions of the blank plate model and the corresponding spherical shell plate three-dimensional model, establish the spherical shell plate stamping die required for stamping process simulation; Step S4, dividing the blank plate model into blocks; Step S5, assembling the divided blank plate model and the spherical shell plate stamping die based on Solidworks, and exporting the assembly into *.xt format; Step S6, importing the *.xt format model into ANSYS Workbench, setting material parameters, contact conditions, boundary conditions and meshing, and then calculating and solving the assembly model after pre-processing; Step S7, processing the solution results in ANSYS Workbench to generate a stamping simulation result model with a grid; Step S8, exporting the gridded blank plate model and the stamping simulation result model with the grid into *.STL format, and using Solidworks to read the exported models respectively; Step S9, using the dimension measurement and evaluation function of Solidworks, setting the center origin of the blank plate model and the spherical shell plate model, and under the premise of maintaining a one-to-one correspondence, respectively measuring the coordinates of each grid point of the blank plate model and the spherical shell plate model and the chord length from the center origin, and performing statistics on the measurement data; Step S10, obtaining the longitude and latitude of the spherical coordinates of each point after deformation by geometric relationship, and establishing the initial corresponding relationship between the chord length of the blank plate and the spherical coordinates of the spherical shell plate; Step S11, taking each grid point of the spherical shell plate model as the sample point of the curved spherical shell plate model, preliminarily screening the sample points according to the measurement data, and deleting abnormal points; Step S12, performing curve fitting on each column of the screened data in MATLAB, deleting the prominent abnormal points in each column, and obtaining the screened data; Step S13, after data screening, perform surface fitting on each column of data in MATLAB, and then delete the points where the calculated results differ greatly from the actual values; Step S14, based on the above fitting, the data points of the spherical shell plates at different parts of the spherical tank and the corresponding blank plate surface are run and calculated in MATLAB to repeatedly correct the initial corresponding relationship between the chord length of the blank plate and the spherical surface coordinates of the spherical shell plate, until the difference between the calculation result and the actual value reaches a certain error range, and the corrected empirical formula is obtained; Step S14, using the modified empirical formula, based on the known parameters of the spherical tank and the spherical shell plate, calculate the size of the blank plate used for actual stamping processing.

2. The method for blanking spherical tank shell plates based on stamping forming inversion algorithm according to claim 1 is characterized in that: In step S7, the solution results are processed in ANSYS Workbench to generate displacement, stress and strain cloud diagrams, and generate animations corresponding to the results.

3. The method for blanking spherical tank shell plates based on stamping forming inversion algorithm according to claim 1 is characterized in that: In step S11, the method for preliminarily screening and deleting outliers is as follows: if the coordinate deviation of a point is too large compared with the adjacent points, the point is evaluated as an outlier, selected and deleted.

4. The method for blanking spherical tank shell plates based on stamping forming inversion algorithm according to claim 1 is characterized in that: In step S12 and step S13, each column of data is data at the same longitude of the curved spherical shell plate model.

5. The method for blanking spherical tank shell plates based on stamping forming inversion algorithm according to claim 1 is characterized in that: When constructing the spherical tank and the spherical shell plate of the upper temperate zone in step S1, the parameters required for constructing the spherical shell plate three-dimensional model include: spherical tank diameter, spherical tank wall thickness, number of spherical shell zones, center angle of each zone and number of blocks of each zone.

6. The method for blanking spherical tank shell plates based on stamping forming inversion algorithm according to claim 2 is characterized in that: The specific steps of step S2 are: importing the spherical shell plate three-dimensional model, extracting the mid-plane to divide the grid, generating the blank contour, and stretching to generate the blank plate model.

7. The method for blanking spherical tank shell plates based on stamping forming inversion algorithm according to claim 1 is characterized in that: The corresponding characteristic dimensions in step S3 include the diagonal length of the blank plate, the arc lengths of the sides of the 3D model of the spherical shell plate, the chord length of the diagonal of the spherical shell plate, and the thickness of the blank plate.

8. The method for blanking spherical tank shell plates based on stamping forming inversion algorithm according to claim 1 is characterized in that: In step S4, during the block processing, the block division method is to take the midpoints of each side of the blank plate, connect the midpoints of the opposite sides, and then divide the blocks.

9. The method for blanking spherical tank shell plates based on stamping forming inversion algorithm according to claim 1 is characterized in that: The specific method of step S6 is to set the mold as a rigid body; The contact condition is that the surface of the blank plate and the surface of the stamping die are in friction contact, and the corresponding friction coefficient is set; the boundary condition is that the convex die is fixed and the concave die is movable; the grid division method is hexahedral grid, and the grid size is selected according to the corresponding spherical tank shell plate and stamping die size.

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