Micro-tube drawing forming calculation method and system based on finite element analysis

Abstract

The application discloses a micro-tube drawing forming calculation method and system based on finite element analysis and relates to the technical field of metal processing. The method comprises the following steps: obtaining micro-tube parameters and drawing die parameters, establishing a geometric model based on the micro-tube parameters and the drawing die; selecting a constitutive model suitable for material deformation to determine material properties, and combining the geometric model to divide a finite element grid; setting constraint conditions for the grid, determining grid data, and determining fatigue points based on the grid data; determining fatigue point load upper and lower limits based on the fatigue points and the grid data corresponding to the fatigue points; and determining drawing force based on the fatigue point load upper and lower limits. The application realizes high-precision prediction of fatigue points in the micro-tube drawing process, can reduce costs, ensures controllable forming quality, and improves the yield.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal processing, and in particular to a micro tube drawing forming calculation method and system based on finite element analysis. BACKGROUND

[0002] Micro tubes have very wide applications in various industries, and when the wall thickness is reduced to within 100 microns, the drawing forming thereof becomes extremely difficult, and the forming quality is difficult to guarantee. In recent years, due to the demand, some difficult-to-deform materials are applied to thin-walled micro tubes, and the processing and manufacturing are more difficult, and are prone to fracture failure. For example, in the micro tube drawing process, the frictional force accounts for a large proportion, resulting in a large drawing force, and the pipe material is prone to breakage during drawing. The deformation amount of each pass is limited, the drawing pass is large, the annealing frequency between passes is large, and the wall thickness uniformity, surface quality and the like are difficult to control, and in some cases, the micro tube cannot be manufactured.

[0003] Therefore, to solve the problems in the prior art, a micro tube drawing forming calculation method and system based on finite element analysis are provided, which is a problem that needs to be solved by those skilled in the art. SUMMARY

[0004] Therefore, to solve the problems in the prior art, a micro tube drawing forming calculation method and system based on finite element analysis are provided, which is a problem that needs to be solved by those skilled in the art.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0006] A micro tube drawing forming calculation method based on finite element analysis, comprising the following steps:

[0007] Obtaining micro tube parameters and drawing die parameters, and establishing a geometric model based on the micro tube parameters and the drawing die;

[0008] Selecting a constitutive model suitable for material deformation to determine material properties, and dividing a finite element grid in combination with the geometric model;

[0009] Setting a constraint condition for the grid, determining grid data, and determining a fatigue point based on the grid data;

[0010] Determining fatigue point load upper and lower limits based on the fatigue point and the grid data corresponding to the fatigue point;

[0011] Determining a drawing force based on the fatigue point load upper and lower limits.

[0012] Optionally, the dividing of the finite element grid comprises:

[0013] Determine the position of the high stress area in the geometric model, and perform initial meshing on the geometric model;

[0014] Based on the position of the high stress area, obtain a plurality of reference values to optimize the initial mesh, and obtain the finite element mesh.

[0015] Optionally, the grid data includes:

[0016] Determine the loading point of the micro-tube drawing experiment;

[0017] Determine the loading load corresponding to the working condition of the loading point, set the inequality constraint to limit the theoretical upper and lower limits of the load based on the control section error, and obtain the theoretical load of the loading point;

[0018] Based on the position of the loading point and the theoretical load of the loading point, determine the finite element mesh data.

[0019] Optionally, it also includes automatically correcting the finite element mesh, detecting the completeness and coordination of the key information in the finite element mesh.

[0020] Optionally, the determination of the fatigue point includes:

[0021] Obtain the finite element mesh and the finite element mesh data, and determine the fatigue result of each mesh based on the finite element mesh data;

[0022] Select a mesh as a free mesh, compare the fatigue results of the free mesh and adjacent free meshes, if the fatigue results of all adjacent free meshes are greater than the fatigue result of the current free mesh, the current free mesh is recorded as S, if the fatigue results of all adjacent free meshes are less than the fatigue result of the current free mesh, the current free mesh is recorded as B, if the fatigue results of adjacent free meshes and the fatigue result of the current free mesh are compared, there are both less than and greater than parts, the current free mesh is recorded as I, if the fatigue results of adjacent free meshes and the fatigue result of the current free mesh are compared, there are equal parts, then replace the free mesh and recalculate;

[0023] The free mesh recorded as B is taken as the fatigue point.

[0024] Optionally, the determination of the fatigue point load upper and lower limits includes:

[0025] Obtain the mesh data and mesh position of the free mesh recorded as B, the mesh data includes the theoretical loading load of the mesh B;

[0026] Determine the fatigue point theoretical load based on the theoretical loading load of all mesh B.

[0027] A microtube drawing forming calculation system based on finite element analysis, which executes the microtube drawing forming calculation method based on finite element analysis described above, includes a model building module, a mesh generation module, a fatigue point determination module, a load determination module, and a solution module connected in sequence;

[0028] Model building module: Obtain microtube parameters and drawing die parameters, and build a geometric model based on the microtube parameters and drawing die;

[0029] Mesh generation module: Select a constitutive model suitable for material deformation to determine material properties, and generate finite element meshes in combination with the geometric model;

[0030] Fatigue point determination module: Sets constraints on the mesh, determines the mesh data, and determines fatigue points based on the mesh data;

[0031] Load determination module: Determines the upper and lower limits of the fatigue point load based on the fatigue point and the corresponding mesh data;

[0032] Solution module: Determines pull-out force based on upper and lower limits of fatigue point load.

[0033] As can be seen from the above technical solutions, compared with the prior art, the present invention provides a calculation method and system for microtube drawing based on finite element analysis, which has the following beneficial effects: 1) The present invention can avoid the situation of excessive local strain during the drawing process of the component, and ensure safety; 2) The present invention realizes high-precision prediction of fatigue points during the microtube drawing process, which can reduce costs, ensure controllable forming quality, and improve yield. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0035] Figure 1 This is a flowchart of a calculation method for microtube drawing based on finite element analysis disclosed in this invention;

[0036] Figure 2 This is a block diagram of a microtube drawing calculation system based on finite element analysis disclosed in this invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Reference Figure 1 As shown, this invention discloses a calculation method for microtube drawing based on finite element analysis, including the following steps:

[0039] Obtain the microtube parameters and drawing die parameters, and establish a geometric model based on the microtube parameters and drawing die;

[0040] Select a constitutive model suitable for material deformation to determine material properties, and combine it with a geometric model to generate a finite element mesh;

[0041] Set constraints on the mesh, determine the mesh data, and determine fatigue points based on the mesh data;

[0042] The upper and lower limits of the load at the fatigue point are determined based on the fatigue point and the corresponding grid data.

[0043] The pull-out force is determined based on the upper and lower limits of the fatigue point load.

[0044] Furthermore, establishing the geometric model involves determining the microtube parameters and drawing die parameters. The microtube parameters include the initial outer diameter, wall thickness, material density, elastic modulus, and Poisson's ratio. The drawing die parameters include the reduction angle, sizing band length, exit diameter, and surface friction coefficient. An axisymmetric geometric model is constructed using NURBS curves.

[0045] Furthermore, the process of creating a finite element mesh includes:

[0046] Determine the location of high-stress areas in the geometric model and perform initial mesh generation on the geometric model;

[0047] The initial mesh is optimized by obtaining multiple reference values ​​based on the location of the high-stress zone, resulting in a finite element mesh.

[0048] Furthermore, determining the grid data includes:

[0049] Determine the loading point for the microtube pull-out test;

[0050] Determine the loading load corresponding to the loading point, set the theoretical lower and lower limits of the load based on the inequality constraint of the control profile error, and obtain the theoretical load of the loading point.

[0051] The finite element mesh data is determined based on the location of the loading point and the theoretical load at the loading point.

[0052] Specifically, based on the structure of the microtube and the theoretical load distribution under typical working conditions, the fatigue test loading nodes of the component are determined, and each loading node is equivalent to multiple loading points. Each loading point includes multiple loading nodes. The location of the fatigue test loading point is determined, and the distribution ratio of each loading node within each loading point is obtained. The loading load between each loading node and the corresponding loading point can be converted through equivalence.

[0053] Furthermore, it also includes automatic error correction of the finite element mesh and detection of the completeness and consistency of key information in the finite element mesh.

[0054] Specifically, automatic error correction also includes: when key information of the finite element mesh is missing, adaptively filling in the missing key information based on data from adjacent meshes;

[0055] The geometric information of the detection unit grid is checked, and it is determined whether there is any duplication or confusion in the geometric point encoding. If so, the encoding process is performed again.

[0056] The system checks whether the unit grid has corresponding working condition information and determines whether the working condition information is correct. If not, it re-compares and determines the correct information.

[0057] Furthermore, the fatigue result for each free surface can be the fatigue result of the center point of the free surface or the fatigue result of the nodes of the free surface. For the fatigue of the center point of the free surface, a measurement coordinate system with the center point of the surface as the origin and the normal direction of the surface center as the z-axis can be calculated based on the free surface mesh data. Then, the finite element results can be transformed into this coordinate system. Then, an appropriate fatigue algorithm can be selected to calculate and search for the worst fatigue result or safety factor and direction on the XY plane. The direction is represented by the angle between the X-axis of the measurement coordinate system.

[0058] Furthermore, if fatigue points are searched based on the damage values ​​of the fatigue results, the point with the largest damage value is the fatigue point; if fatigue points are searched based on the safety factor values ​​of the fatigue results, the point with the smallest safety factor value is the fatigue point.

[0059] Further, identifying fatigue points includes:

[0060] Acquire finite element meshes and finite element mesh data, and determine the fatigue results for each mesh based on the finite element mesh data;

[0061] Select a grid as the free grid, and compare the fatigue results of the free grid with those of adjacent free grids. If the fatigue results of all adjacent free grids are greater than the fatigue results of the current free grid, the current free grid is denoted as S. If the fatigue results of all adjacent free grids are less than the fatigue results of the current free grid, the current free grid is denoted as B. If the fatigue results of adjacent free grids are both less than and greater than the fatigue results of the current free grid, the current free grid is denoted as I. If the fatigue results of adjacent free grids are equal to the fatigue results of the current free grid, the free grid is replaced and the calculation is repeated.

[0062] The free mesh denoted as B is taken as the fatigue point.

[0063] Furthermore, determining the upper and lower limits of the fatigue point load includes:

[0064] Obtain the mesh data and mesh location of the free mesh denoted as B. The mesh data includes the theoretical loaded load of mesh B.

[0065] The theoretical load at the fatigue point is determined based on the theoretical load applied to all grids B.

[0066] Specifically, the loading loads at each loading point under each working condition are used as variables. Inequality constraints are applied using the theoretical total load moment and the control profile error, including inequality constraints on the bending moment, shear force, and torque errors of the control profile, as well as limiting the upper and lower limits of the loading loads at each loading point. The target response error under the component fatigue test and theoretical state finite element model is used as the target variable to obtain the loading loads at each loading point, and then the loading loads of each free mesh are obtained. Genetic algorithms are used for calculation. For each generation of loading load population, the finite element model load cards are iterated. Finite element analysis of the component fatigue test finite element model is performed using MSC.Nastran software, and the target data is extracted from the result file. A new generation of loading load population is generated through the selection, crossover, and mutation of the loading load population. The component fatigue test finite element model is continuously iterated and the target data is extracted, gradually bringing the loading loads of each free mesh to the optimal solution.

[0067] A microtube drawing forming calculation system based on finite element analysis, executing the microtube drawing forming calculation method based on finite element analysis described above, with reference to... Figure 2 As shown, it includes a model building module, a mesh generation module, a fatigue point determination module, a load determination module, and a solution module connected in sequence;

[0068] Model building module: Obtain microtube parameters and drawing die parameters, and build a geometric model based on the microtube parameters and drawing die;

[0069] Mesh generation module: Select a constitutive model suitable for material deformation to determine material properties, and generate finite element meshes in combination with the geometric model;

[0070] Fatigue point determination module: Sets constraints on the mesh, determines the mesh data, and determines fatigue points based on the mesh data;

[0071] Load determination module: Determines the upper and lower limits of the fatigue point load based on the fatigue point and the corresponding mesh data;

[0072] Solution module: Determines pull-out force based on upper and lower limits of fatigue point load.

[0073] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A calculation method for microtube drawing based on finite element analysis, characterized in that, Includes the following steps: Obtain the microtube parameters and drawing die parameters, and establish a geometric model based on the microtube parameters and drawing die; Select a constitutive model suitable for material deformation to determine material properties, and combine it with a geometric model to generate a finite element mesh; Set constraints on the mesh, determine the mesh data, and determine fatigue points based on the mesh data; The upper and lower limits of the load at the fatigue point are determined based on the fatigue point and the corresponding grid data. Determine the pull-out force based on the upper and lower limits of the fatigue point load; Determining the grid data includes: Determine the loading point for the microtube pull-out test; Determine the loading load corresponding to the loading point, set the theoretical lower and lower limits of the load based on the inequality constraint of the control profile error, and obtain the theoretical load of the loading point. The finite element mesh data is determined based on the location of the loading point and the theoretical load at the loading point. Determining fatigue points includes: Acquire finite element meshes and finite element mesh data, and determine the fatigue results for each mesh based on the finite element mesh data; Select a grid as the free grid, and compare the fatigue results of the free grid with those of adjacent free grids. If the fatigue results of all adjacent free grids are greater than the fatigue results of the current free grid, the current free grid is denoted as S. If the fatigue results of all adjacent free grids are less than the fatigue results of the current free grid, the current free grid is denoted as B. If the fatigue results of adjacent free grids are both less than and greater than the fatigue results of the current free grid, the current free grid is denoted as I. If the fatigue results of adjacent free grids are equal to the fatigue results of the current free grid, the free grid is replaced and the calculation is repeated. The free mesh denoted as B is taken as the fatigue point.

2. The calculation method for microtube drawing based on finite element analysis according to claim 1, characterized in that, Generating a finite element mesh includes: Determine the location of high-stress areas in the geometric model and perform initial mesh generation on the geometric model; The initial mesh is optimized by obtaining multiple reference values ​​based on the location of the high-stress zone, resulting in a finite element mesh.

3. The calculation method for microtube drawing based on finite element analysis according to claim 1, characterized in that... It also includes automatic error correction of finite element meshes and detection of the completeness and consistency of key information in finite element meshes.

4. The calculation method for microtube drawing based on finite element analysis according to claim 1, characterized in that, Determining the upper and lower limits of fatigue point load includes: Obtain the mesh data and mesh location of the free mesh denoted as B. The mesh data includes the theoretical loaded load of mesh B. The theoretical load at the fatigue point is determined based on the theoretical load applied to all grids B.

5. A microtube drawing forming calculation system based on finite element analysis, used to implement the microtube drawing forming calculation method based on finite element analysis as described in any one of claims 1-4, comprising a model building module, a mesh generation module, a fatigue point determination module, a load determination module, and a solution module connected in sequence; Model building module: Obtain microtube parameters and drawing die parameters, and build a geometric model based on the microtube parameters and drawing die; Mesh generation module: Select a constitutive model suitable for material deformation to determine material properties, and generate finite element meshes in combination with the geometric model; Fatigue point determination module: Sets constraints on the mesh, determines the mesh data, and determines fatigue points based on the mesh data; Load determination module: Determines the upper and lower limits of the fatigue point load based on the fatigue point and the corresponding mesh data; Solution module: Determines pull-out force based on upper and lower limits of fatigue point load.

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