A simulation analysis device and analysis method for powder pressing

Abstract

A simulation analysis device and analysis method for powder pressing, belonging to the field of powder metallurgy. To solve the problem of inaccurate numerical model of powder pressing. The present invention applies Comsol Multiphysics to establish a two-dimensional axisymmetric space dimension, and selects solid mechanics to establish a geometric model of powder pressing, respectively setting a definition part, a solid mechanics 1 part, and a solid mechanics 2 part; setting the material properties of the metal powder part and the mold part, and meshing the geometric model; setting a study-two-stage pressing, including setting and modifying the model configuration of the research step, and auxiliary scanning; setting a study-single-stage pressing, including establishing a research setting, modifying the model configuration of the research step, and auxiliary scanning; performing solution calculations to obtain simulation results of powder pressing, and processing each of the simulation results. The present invention provides theoretical guidance and technical support for the application of powder pressing.

Description

Technical Field

[0001] The invention belongs to the field of powder metallurgy, and in particular relates to a simulation analysis device and an analysis method for powder pressing. Background Art

[0002] Powder pressing is a critical process in powder metallurgy. Powder pressing is to compact the powder into a green body with a certain size, shape, density, porosity and strength. The green body formed by powder pressing is not the final product of powder metallurgy, but it affects the quality of subsequent processes and the final product, and also affects the performance of the product to a certain extent.

[0003] Traditional powder metallurgy requires repeated mold trials and improved design and forming processes during production and manufacturing, which is usually called "trial and error", which may cause a large waste of resources. In today's society dominated by economic development, the traditional trial and error method cannot meet the development needs. In the context of high efficiency, economy and green development, we are constantly looking for low-cost, short-cycle process approaches, and trying to improve the quality of powder metallurgy products by continuously optimizing process parameters.

[0004] Therefore, in view of the above shortcomings, it is necessary to provide an accurate numerical simulation model for studying powder pressing simulation. Summary of the invention

[0005] The problem to be solved by the present invention is that the real-time monitoring of parameters of single-stage powder pressing and two-stage powder pressing is subject to many restrictions, and it is difficult to study parameters such as stress, strain, relative density, and pore volume fraction. The present invention proposes a simulation analysis device and analysis method for powder pressing.

[0006] To achieve the above object, the present invention is implemented through the following technical solutions:

[0007] A simulation analysis method for powder pressing comprises the following steps:

[0008] S1. Use Comsol Multiphysics to establish the two-dimensional axisymmetric spatial dimension and select solid mechanics;

[0009] S2. Establishing a geometric model of powder pressing, wherein the geometric model includes a metal powder part and a mold part, and the calculation domain of the geometric model includes a mold geometric area and a metal powder calculation domain;

[0010] S3, respectively establish a definition part for setting mechanical parameters of two-stage pressing and single-stage pressing, a solid mechanics 1 part for setting simulation of two-stage pressing, and a solid mechanics 2 part for setting simulation of single-stage pressing;

[0011] S4, setting material properties of the metal powder part and the mold part, and meshing the geometric model;

[0012] S5. Select two-stage pressing and single-stage pressing, perform solution calculation, and obtain simulation results of powder pressing;

[0013] S6. Process the simulation results to generate stress distribution diagram, relative density distribution diagram, volume plastic strain distribution diagram, current hole volume fraction distribution diagram, powder and mold contact force distribution diagram, two-stage pressing average elastic volume strain change distribution diagram, punch pressure and compact displacement distribution diagram.

[0014] Furthermore, the specific implementation method of step S3 includes the following steps:

[0015] S3.1. Set the definition part to integral function intop1 and integral function intop2, set the variable Force1 to two-stage pressing, Force2 to single-stage pressing, and delta to axial pressing;

[0016] S3.2. Set the solid mechanics 1 part as a linear elastic material, including setting the plastic strain, yield function F, and activation expression; set the rigid domain, including setting the initial value and fixed constraints; set the friction coefficient; set the specified displacement, including setting the boundary and specifying the displacement direction; set the boundary load 1, including setting the boundary load 1 boundary and the total force F. tot Function; Set boundary load 2, including setting boundary load 2 boundary, total force F tot function;

[0017] S3.3. Set the Solid Mechanics 2 part as a linear elastic material, including setting the plastic strain and the yield function F; set the rigid domain, including setting the initial value and the fixed constraint; set the friction coefficient; set the specified displacement 1, including setting the boundary and specifying the displacement direction; set the specified displacement 2, including setting the boundary and specifying the displacement function in the z direction.

[0018] Further, in step S3.1, the integral function intop1 boundary of the definition part is set to the selection boundary 5;

[0019] Set the boundaries of the integral function intop2 to select the contact boundaries 6 and 7 of the metal powder part and the mold part, and do not calculate the integral of the rotational geometry; set the function Force1 = PunchForce (para) for two-stage pressing, Force2 = intop1 (-solid2.sz) for single-stage pressing, and delta = 1-intop2 (1) / (2*H0) for axial pressing.

[0020] Furthermore, in step S3.2, the yield function F of the solid mechanics part 1 is set to Gurson-Tvergaard-Needleman, which represents the mesoscopic pore model theory;

[0021] The activation expression is set to para>1, para is the parameter, and the activation domain is 2;

[0022] Set the rigid domain to selection domain 3;

[0023] Set the friction coefficient to 0.05;

[0024] Set the specified displacement boundary to Select boundary 2, specified in the z direction;

[0025] Set the boundary load 1 boundary to select boundary 4,

[0026] Set the total force F of boundary load 1 tot The function is: r = 0, z = -PunchForce(para)*(para<=1),

[0027] PunchForce, which means applying load in the z direction;

[0028] Set the boundary load 2 boundary to selected boundary 5,

[0029] Set the total force F of boundary load 2 tot The function is r=0, z=-PunchForce(para)*(para>=1.1).

[0030] Furthermore, in step S3.3, the yield function F of the solid mechanics part 2 is set to Gurson-Tvergaard-Needleman, which represents the mesoscopic pore model theory;

[0031] Set the rigid domain to select only domain 3;

[0032] Set the friction coefficient to 0.05;

[0033] Set the specified displacement 1 boundary to selected boundary 2, specified in the z direction;

[0034] Set the specified displacement boundary to selected boundary 2 and the function in the z direction to disp to indicate the magnitude of the displacement suppressed in the positive direction.

[0035] Further, in step S4, the method for setting the material properties of the metal powder part and the mold part is: selecting a material for the metal powder part, selecting magnesium (solid) in the material library and adding it, and setting the initial yield stress to 200 MPa, the initial pore volume fraction to 0.28, the Tvergaard correction coefficient q1 to 1.5, the Tvergaard correction coefficient q2 to 1, the Tvergaard correction coefficient q3 to 2.25, the critical pore volume fraction to 0.36, and the failure pore volume fraction to 0.4;

[0036] The method for meshing the geometric model is: meshing the geometric model in a customized form, setting the mapping to select boundary 10, the distribution boundary to select boundary 11, fixing the number of cells to 1, and setting the mesh cells to include 243 domain cells and 81 boundary cells.

[0037] Furthermore, the specific implementation method of step S5 includes the following steps:

[0038] S5.1. Set up the study - two-stage pressing: including setting up the model configuration for modifying the study steps, canceling the deformation of the coordinate system controlled by Solid Mechanics 2, disabling Solid Mechanics 2 in the model, the auxiliary scanning type is the specified combination, the parameter is para (Parameter), the parameter value list is range (0, 0.1, 2) to describe the calculation starting from 0, calculating every 0.1, and ending at 2, and performing the solution calculation to obtain the simulation results of powder pressing, including the simulation results of stress distribution, the simulation results of relative density, the simulation results of parameter value volume plastic strain distribution, the simulation results of pore volume fraction distribution, the simulation results of powder and die contact force distribution, the simulation results of average elastic volume strain distribution, and the simulation results of punch pressure distribution of compact displacement;

[0039] S5.2. Set up the study - single-stage pressing: including setting up to cancel the generation of default drawings, modify the model configuration of the study step, cancel the solid mechanics 1 control coordinate system deformation, disable solid mechanics 1 in the model, the auxiliary scanning type is a specified combination, the parameter is disp (Displacement parameter), the parameter value list is range (0, 0.1, 6.2) to describe the calculation starting from 0, every 0.1, and ending at 6.2, and perform a solution calculation to obtain the simulation results of powder pressing, including the simulation results of stress distribution, the simulation results of relative density, the simulation results of parameter value volume plastic strain distribution, the simulation results of pore volume fraction distribution, the simulation results of average elastic volume strain distribution, and the simulation results of punch pressure distribution of compact displacement.

[0040] Furthermore, the specific implementation method of step S6 includes the following steps:

[0041] S6.1. For the two-stage pressing stress distribution diagram, select the two-dimensional drawing group, select the simulation result of stress distribution to generate the stress distribution diagram; for the single-stage pressing stress distribution diagram, select the two-dimensional drawing group, select the simulation result of stress distribution of parameter value to generate the stress distribution diagram;

[0042] S6.2. For the relative density distribution diagram of two-stage pressing, select the three-dimensional drawing group, replace the expression with solid.lemm1.popl1.rhorel-current relative density, and select the simulation result of relative density to generate the relative density distribution diagram; for the relative density distribution diagram of single-stage pressing, select the three-dimensional drawing group, replace the expression with solid.lemm1.popl1.rhorel-current relative density on the basis of two-dimensional rotation, and select the simulation result of stress distribution to generate the relative density distribution diagram;

[0043] S6.3, Volume Plastic Strain Distribution Diagram Select the 2D drawing group, copy the contour line, set the expression to: if(isnan(solid2.f), NaN, solid2.f), which indicates volume plastic strain, Gaussian point calculation, translation y50[mm], which indicates moving the single-stage pressing volume plastic strain diagram 50 mm to the y axis, and select the parameter value Volume Plastic Strain Distribution Simulation Results to generate the volume plastic strain distribution diagram;

[0044] S6.4, Current void volume fraction distribution diagram Select the 2D drawing group, copy the contour line, set the expression to if(isnan(solid2.f), NaN, solid2.f), which indicates the current void volume fraction, translate y50[mm], which indicates moving the single-stage current void volume fraction distribution diagram 50 mm to the y-axis, and select the simulation result of the parameter value current void volume fraction distribution;

[0045] S6.5, Powder-die contact force distribution diagram Select the 2D plot group and select the parameter value Powder-die contact force distribution simulation result;

[0046] S6.6. Distribution of average elastic volume strain variation in two-stage pressing Select a one-dimensional plot group to characterize and display the average elastic volume strain distribution of two-stage pressing with different parameter values, where the horizontal axis is the parameter value and the vertical axis is the average elastic volume strain;

[0047] S6.7, Punch pressure and blank displacement distribution diagram Select a one-dimensional drawing group to characterize and display the punch pressure distribution for different blank displacements, where the horizontal axis is the blank displacement and the vertical axis is the punch pressure.

[0048] A simulation analysis device for powder pressing is implemented based on a simulation analysis method for powder pressing, including a creation module for establishing a two-dimensional axisymmetric space dimension and selecting solid mechanics;

[0049] A modeling module, used for establishing a geometric model of powder pressing, wherein the geometric model includes a metal powder part and a mold part, and the calculation domain of the geometric model includes a geometric region and a metal powder calculation domain;

[0050] The first setting module is used to set the definition part, the solid mechanics 1 part, and the solid mechanics 2 part respectively;

[0051] A second setting module is used to set the material properties of the metal powder part and the mold part;

[0052] A partitioning module, used for performing mesh partitioning on the geometric model, wherein the mesh units include 243 domain units and 81 boundary units;

[0053] A solution module is used to set up a study-two-stage pressing, including setting and modifying the model configuration and auxiliary scanning of the study steps; setting up a study-single-stage pressing, including establishing the study settings, modifying the model configuration and auxiliary scanning of the study steps; and performing solution calculation to obtain the simulation results of each powder pressing;

[0054] A generation module is used to process each of the simulation results to generate a stress distribution diagram, a relative density distribution diagram, a volume plastic strain distribution diagram, a current pore volume fraction distribution diagram, a powder and mold contact force distribution diagram, a two-stage pressing average elastic volume strain change distribution diagram, and a mold pressure and displacement distribution diagram.

[0055] Beneficial effects of the present invention:

[0056] The simulation analysis method for powder pressing described in the present invention simulates single-stage powder pressing and two-stage powder pressing based on Comsol Multiphysics and compares them, so as to efficiently and accurately obtain the characteristic distribution of powder stress, strain, relative density and pore volume fraction. The operation is convenient, and the test time and cost are greatly reduced, thus providing theoretical guidance and technical support for the application of powder pressing. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 A flow chart of a simulation analysis method for powder pressing according to the present invention;

[0058] Figure 2 It is a schematic diagram of a geometric model of a simulation analysis method for powder pressing according to a specific embodiment of the present invention;

[0059] Figure 3 It is a schematic diagram of the distribution of the geometric model domain of a simulation analysis method for powder pressing according to the first specific embodiment of the present invention;

[0060] 1 is the lower part of the metal powder, defined as domain 1, 2 is the upper part of the metal powder, defined as domain 2, and 3 is the mold part, defined as domain 3;

[0061] Figure 4 It is a schematic diagram of the boundary distribution of a geometric model of a simulation analysis method for powder pressing according to a specific embodiment of the present invention;

[0062] 1 is the left side of the lower half of the metal powder, defined as boundary 1, 2 is the lower side of the lower half of the metal powder, defined as boundary 2, 3 is the left side of the upper half of the metal powder, defined as boundary 3, 4 is the connecting edge between the lower half of the metal powder and the upper half of the metal powder, defined as boundary 4, 5 is the upper side of the upper half of the metal powder, defined as boundary 5, 6 is the connecting edge between the lower half of the metal powder and the mold part, defined as boundary 6, 7 is the connecting edge between the upper half of the metal powder and the mold part, defined as boundary 7, 8 is the left side of the mold part, defined as boundary 8, 9 is the lower side of the mold part, defined as boundary 9, 10 is the upper side of the mold part, defined as boundary 10, and 11 is the right side of the mold part, defined as boundary 11;

[0063] Figure 5 It is a stress distribution diagram generated by single-stage pressing corresponding to a compact displacement of 0 mm in a simulation analysis method for powder pressing described in the first specific embodiment of the present invention;

[0064] Figure 6 It is a stress distribution diagram generated by single-stage pressing corresponding to a compact displacement of 3.1 mm in a simulation analysis method for powder pressing described in the first specific embodiment of the present invention;

[0065] Figure 7 It is a stress distribution diagram generated by single-stage pressing corresponding to a compact displacement of 6.2 mm in a simulation analysis method for powder pressing described in the first specific embodiment of the present invention;

[0066] Figure 8 It is a stress distribution diagram generated by two-stage pressing corresponding to a compact displacement of 0 mm in a simulation analysis method for powder pressing described in the first specific embodiment of the present invention;

[0067] Fig. 9 It is a stress distribution diagram generated by two-stage pressing corresponding to a compact displacement of 3.1 mm in a simulation analysis method of powder pressing described in the first specific embodiment of the present invention;

[0068] Fig.10 It is a stress distribution diagram generated by two-stage pressing corresponding to a compact displacement of 6.2 mm in a simulation analysis method of powder pressing described in the first specific embodiment of the present invention;

[0069] Fig.11It is a single-stage pressing relative density distribution diagram corresponding to a compact displacement of 6.2 mm in a simulation analysis method for powder pressing described in the first specific embodiment of the present invention;

[0070] Fig.12 It is a two-stage pressing relative density distribution diagram corresponding to a compact displacement of 6.2 mm in a simulation analysis method for powder pressing described in the first specific embodiment of the present invention;

[0071] Fig.13 It is a volume plastic strain distribution diagram corresponding to a compact displacement of 6.2 mm in a simulation analysis method for powder compacting described in a specific embodiment of the present invention;

[0072] Fig.14 It is a current pore volume fraction distribution diagram corresponding to a compact displacement of 6.2 mm in a simulation analysis method for powder compacting described in the first specific embodiment of the present invention;

[0073] Fig.15 It is a distribution diagram of the contact force between powder and die corresponding to a 6.2 mm displacement of a green sheet in two-stage pressing of a simulation analysis method for powder pressing described in the first embodiment;

[0074] Fig.16 It is a distribution diagram of the average volume elastic strain change of two-stage pressing of a simulation analysis method of powder pressing described in the first specific implementation mode;

[0075] Fig.17 It is a mold pressure and displacement distribution diagram of a simulation analysis method for powder pressing described in specific implementation mode one. DETAILED DESCRIPTION

[0076] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention, that is, the specific embodiments described are only part of the embodiments of the present invention, rather than all of the specific embodiments. The components of the specific embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations, and the present invention can also have other embodiments.

[0077] Therefore, the following detailed description of the specific embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents the selected specific embodiments of the present invention. Based on the specific embodiments of the present invention, all other specific embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0078] In order to further understand the content, features and effects of the present invention, the following specific implementation methods are given as examples, and the attached Figure 1-17 The detailed instructions are as follows:

[0079] Since the powder pressing process involves complex mechanical properties, the real-time monitoring of single-stage powder pressing and two-stage powder pressing parameters is subject to many limitations, making it difficult to study parameters such as stress, strain, volume deformation, and pore volume fraction.

[0080] Comsol Multiphysics is a numerical simulation software based on the finite element method. When the present invention uses Comsol Multiphysics to realize the simulation research of powder pressing, the characteristic distribution of powder stress, strain, relative density and pore volume fraction can be accurately obtained. Specific implementation method one:

[0082] A simulation analysis method for powder pressing comprises the following steps:

[0083] S1. Use Comsol Multiphysics to establish the two-dimensional axisymmetric spatial dimension and select solid mechanics.

[0084] In Comsol Multiphysics, you can create a two-dimensional axisymmetric space dimension and select and set up appropriate physical fields based on the properties of powder compaction, so that real physical conditions can be simulated through the solid mechanics part. In addition, you can choose a steady-state study.

[0085] S2. Establish a geometric model for powder pressing, which is used to simulate powder pressing. The geometric model includes a metal powder part and a mold part. The calculation domain of the geometric model includes a geometric area and a metal powder calculation domain, such as Figure 2 shown.

[0086] S3. The definition part is used to set the mechanical parameters of two-stage pressing and single-stage pressing respectively; the solid mechanics 1 part is used to set the simulation of two-stage pressing; the solid mechanics 2 part is used to set the simulation of single-stage pressing.

[0087] In order to study the influence of pressing process on powder pressing, two-stage and single-stage powder pressing were set up respectively, so as to study the characteristic distribution of powder stress, strain, relative density and pore volume fraction.

[0088] Furthermore, the specific implementation method of step S3 includes the following steps:

[0089] S3.1. Set the definition part to integral function intop1 and integral function intop2, set the variable Force1 to two-stage compression, Force2 to single-stage compression, and delta to axial compression;

[0090] In step S3.1, the boundary of the integral function intop1 of the definition part is set to the selection boundary 5;

[0091] Set the integration function intop2 boundary to select the contact boundary 6 and 7 of the metal powder part and the mold part, and do not calculate the integral in the rotational geometry;

[0092] Set the function Force1 = PunchForce(para) for two-stage pressing, Force2 = intop1(-solid2.sz) for single-stage pressing, and delta = 1-intop2(1) / (2*H0) for axial pressing;

[0093] S3.2. Set the solid mechanics 1 part as a linear elastic material, including setting the plastic strain, yield function F, and activation expression; set the rigid domain, including setting the initial value and fixed constraints; set the friction coefficient; set the specified displacement, including setting the boundary and specifying the displacement direction; set the boundary load 1, including setting the boundary load 1 boundary and the total force F. tot Function; Set boundary load 2, including setting boundary load 2 boundary, total force F tot function;

[0094] In step S3.2, the yield function F of the solid mechanics part 1 is set to Gurson-Tvergaard-Needleman, which represents the mesoscopic pore model theory;

[0095] The activation expression is set to para>1, para is the parameter, and the activation domain is 2;

[0096] Set the rigid domain to selection domain 3;

[0097] Set the friction coefficient to 0.05;

[0098] Set the specified displacement boundary to Select boundary 2, specified in the z direction;

[0099] Set the boundary load 1 boundary to select boundary 4,

[0100] Set the total force F of boundary load 1 tot The function is: r = 0, z = -PunchForce(para)*(para<=1),

[0101] PunchForce, which means applying load in the z direction;

[0102] Set the boundary load 2 to select boundary 5 and set the total force F of boundary load 2 tot The function is r=0, z=-PunchForce(para)*(para>=1.1), which means that the load is applied in the z direction;.

[0103] S3.3, set the solid mechanics 2 part as a linear elastic material, including setting the plastic strain and the yield function F; set the rigid domain, including setting the initial value and the fixed constraint; set the friction coefficient; set the specified displacement 1, including setting the boundary and the specified displacement direction; set the specified displacement 2, including setting the boundary and the specified displacement function in the z direction;

[0104] In step S3.3, the yield function F of the solid mechanics part 2 is set to Gurson-Tvergaard-Needleman, which represents the mesoscopic pore model theory;

[0105] Set the rigid domain to select only 3;

[0106] Set the friction coefficient to 0.05;

[0107] Set the specified displacement 1 boundary to selected boundary 2, specified in the z direction;

[0108] Set the specified displacement boundary to selected boundary 2, and the function in the z direction to disp to indicate the magnitude of the positive direction displacement suppression;

[0109] S4, setting material properties of the metal powder part and the mold part, and meshing the geometric model;

[0110] Furthermore, in step S4, the method for setting the material properties of the metal powder part and the mold part is as follows: select a material for the metal powder part, select magnesium (solid) in the material library to add, and set the initial yield stress to 200MPa, the initial pore volume fraction to 0.28, the Tvergaard correction coefficient q1 to 1.5, the Tvergaard correction coefficient q2 to 1, the Tvergaard correction coefficient q3 to 2.25, the critical pore volume fraction to 0.36, and the failure pore volume fraction to 0.4. The mold part is set as a rigid domain model, and the material properties do not need to be considered;

[0111] The method for meshing the geometric model is as follows: meshing the geometric model in a customized form, setting the mapping to select boundary 10, the distribution boundary to select boundary 11, the fixed number of cells to 1, and setting the mesh cells to include 243 domain cells and 81 boundary cells;

[0112] S5. Select two-stage pressing and single-stage pressing, perform solution calculation, and obtain simulation results of powder pressing;

[0113] Furthermore, the specific implementation method of step S5 includes the following steps:

[0114] S5.1. Set up the study - two-stage pressing: including setting up the model configuration for modifying the study steps, canceling the deformation of the coordinate system controlled by Solid Mechanics 2, disabling Solid Mechanics 2 in the model, the auxiliary scanning type is the specified combination, the parameter is para (Parameter), the parameter value list is range (0, 0.1, 2) to describe the calculation starting from 0, calculating every 0.1, and ending at 2, and performing the solution calculation to obtain the simulation results of powder pressing, including the simulation results of stress distribution, the simulation results of relative density, the simulation results of parameter value volume plastic strain distribution, the simulation results of pore volume fraction distribution, the simulation results of powder and die contact force distribution, the simulation results of average elastic volume strain distribution, and the simulation results of punch pressure distribution of compact displacement;

[0115] S5.2, setting up research - single-stage pressing: including setting up to cancel the generation of default drawings, modifying the model configuration of the research step, canceling the solid mechanics 1 control coordinate system deformation, disabling solid mechanics 1 in the model, the auxiliary scanning type is a specified combination, the parameter is disp (Displacement parameter), the parameter value list is range (0, 0.1, 6.2) describing the calculation starting from 0, calculating every 0.1, and ending at 6.2, and performing a solution calculation to obtain the simulation results of powder pressing, including the simulation results of stress distribution, the simulation results of relative density, the simulation results of parameter value volume plastic strain distribution, the simulation results of pore volume fraction distribution, the simulation results of average elastic volume strain distribution, and the simulation results of punch pressure distribution of compact displacement;

[0116] S6. Process the simulation results to generate a stress distribution diagram, a relative density distribution diagram, a volume plastic strain distribution diagram, a current hole volume fraction distribution diagram, a powder and die contact force distribution diagram, a two-stage pressing average elastic volume strain change distribution diagram, and a punch pressure and compact displacement distribution diagram;

[0117] Furthermore, the specific implementation method of step S6 includes the following steps:

[0118] S6.1. For the two-stage pressing stress distribution diagram, select the two-dimensional drawing group, select the simulation result of stress distribution to generate the stress distribution diagram; for the single-stage pressing stress distribution diagram, select the two-dimensional drawing group, select the simulation result of stress distribution of parameter value to generate the stress distribution diagram;

[0119] S6.2. For the relative density distribution diagram of two-stage pressing, select the three-dimensional drawing group, replace the expression with solid.lemm1.popl1.rhorel-current relative density, and select the simulation result of relative density to generate the relative density distribution diagram; for the relative density distribution diagram of single-stage pressing, select the three-dimensional drawing group, replace the expression with solid.lemm1.popl1.rhorel-current relative density on the basis of two-dimensional rotation, and select the simulation result of stress distribution to generate the relative density distribution diagram;

[0120] S6.3, Volume Plastic Strain Distribution Diagram Select the 2D drawing group, copy the contour line, set the expression to: if(isnan(solid2.f), NaN, solid2.f), which indicates volume plastic strain, Gaussian point calculation, translation y50[mm], which indicates moving the single-stage pressing volume plastic strain diagram 50 mm to the y axis, and select the parameter value Volume Plastic Strain Distribution Simulation Results to generate the volume plastic strain distribution diagram;

[0121] S6.4, Current void volume fraction distribution diagram Select the 2D drawing group, copy the contour line, set the expression to if(isnan(solid2.f), NaN, solid2.f), which indicates the current void volume fraction, translate y50[mm], which indicates moving the single-stage current void volume fraction distribution diagram 50 mm to the y-axis, and select the simulation result of the parameter value current void volume fraction distribution;

[0122] S6.5, Powder-die contact force distribution diagram Select the 2D plot group and select the parameter value Powder-die contact force distribution simulation result;

[0123] S6.6. Distribution of average elastic volume strain variation in two-stage pressing Select a one-dimensional plot group to characterize and display the average elastic volume strain distribution of two-stage pressing with different parameter values, where the horizontal axis is the parameter value and the vertical axis is the average elastic volume strain;

[0124] S6.7, Punch pressure and blank displacement distribution diagram Select a one-dimensional drawing group to characterize and display the punch pressure distribution for different blank displacements, where the horizontal axis is the blank displacement and the vertical axis is the punch pressure.

[0125] Attached Figure 5-17 ComsolMultiphysics can process and analyze the simulation results and display them in the form of graphs. Figure 5 , 6, 7, 8, 9, 10) are used to show the effect of each green sheet displacement on stress distribution; the relative density distribution diagrams corresponding to the green sheet displacement of 6.2 mm for single-stage and two-stage pressing (for example, attached Fig.11 , 12 ) is used to show the effect of single-stage and two-stage pressing on relative density; the volume plastic strain distribution diagram corresponding to the single-stage and two-stage pressing blank displacement of 6.2 mm (for example, attached Fig.13 ) is used to show the effect of single-stage and two-stage pressing on volume plastic strain; the current pore volume fraction distribution diagram corresponding to the single-stage and two-stage pressing blank displacement of 6.2 mm (for example, attached Fig.14 ) is used to show the effect of single-stage and two-stage pressing on the pore volume fraction; the distribution diagram of the contact force between powder and mold (such as the attached Fig.15 ) is used to show the contact force distribution between the powder and the mold when the displacement of the green sheet is 6.2 mm in the two-stage pressing; the average elastic volume strain change distribution diagram is used to show the average elastic volume strain change distribution in the single stage and two stages under different parameter values. The average elastic volume strain change distribution in the single stage and two stages under different parameter values ​​can be drawn into the same diagram (for example, the attached Fig.16 ); The mold pressure and displacement distribution diagram is used to show the single-stage and two-stage mold pressure distribution under different green sheet displacements. The single-stage and two-stage mold pressure distribution under different green sheet displacements can be plotted in the same diagram (for example, Fig.17 ).

[0126] The following is a detailed description of the attached drawings:

[0127] In order to study the influence of the single-stage and two-stage pressing on the stress generated by the green sheet displacement, at least three green sheet displacements can be taken to study the stress distribution characteristics under different green sheet displacements.

[0128] In order to study the effects of single-stage and two-stage pressing on volume plastic strain, relative density and pre-hole volume fraction, the blank displacement was 6.2 mm, and the distribution characteristics of single-stage and two-stage pressing on volume plastic strain, relative density and pre-hole volume fraction were studied.

[0129] The blank displacement is set to take values ​​every 0.1 mm from 0 mm to 6.2 mm, and simulation analysis is performed according to steps S1 to S6, and finally a stress distribution diagram, a relative density distribution diagram, a volume plastic strain distribution diagram, a current pore volume fraction distribution diagram, a powder and mold contact force distribution diagram, an average elastic volume strain change distribution diagram, and a punch pressure and blank displacement distribution diagram corresponding to different blank displacements are generated.

[0130] Attached Figure 5 , 67 and 8 are the single-stage pressing stress distribution diagrams corresponding to the blank displacement of 0mm, 3.1mm, and 6.2mm, respectively. When the blank displacement is 0mm, no pressure is applied and the minimum stress is 0N / m 2 , maximum stress 3.82×10 -5 N / m 2 As the mold pressure increases, the displacement of the pressed green sheet increases. When the displacement of the pressed green sheet reaches 3.1 mm, the stress distribution shows a continuous gradient, and the minimum stress is 6.12×10 7 N / m 2 , the maximum stress is 8.40×10 7 N / m 2 When the blank displacement reaches 6.2 mm, the single-stage pressing is completed, and the minimum stress is 6.21×10 7 N / m 2 , the maximum stress is 9.65×10 7 N / m 2 .

[0131] Attached Figure 8 , 9 10 and 11 are the two-stage pressing stress distribution diagrams corresponding to the blank displacement of 0mm, 3.1mm, and 6.2mm, respectively. In the two-stage powder pressing, half of the metal powder is first placed in the mold and pressed to 3.1mm, and then the other half of the powder is placed in and pressed to 3.1mm to complete the two-stage powder pressing. When the blank displacement is 0mm, only half of the metal powder is placed in the mold, and no pressure is applied. The minimum stress is 1.14×10 -10 N / m 2 , the maximum stress is 1.24×10 -5 N / m 2 When the blank displacement reaches 3.1 mm, the stress distribution shows a continuous gradient, and the minimum stress is 5.41×10 7 N / m 2 , the maximum stress is 1.10×10 8 N / m 2 When the blank displacement reaches 6.2 mm, the two-stage pressing is completed and the minimum stress is 5.41×10 7 N / m 2 , the maximum stress is 1.10×10 8 N / m 2 .

[0132] Attached Fig.11 , 12 The relative density distribution diagrams of single-stage and two-stage pressing corresponding to a blank displacement of 6.2 mm are shown respectively. The relative density of the two-stage pressing is evenly distributed in layers, while the relative density of the single-stage process changes significantly from top to bottom. The change in relative density for two-stage pressing is smaller than that for single-stage pressing.

[0133] Attached Fig.13 The following are the volumetric plastic strain distribution diagrams corresponding to the blank displacement of 6.2 mm. The volumetric plastic strain of the two-stage pressing process is evenly distributed in layers, while the volumetric plastic strain of the upper and lower boundaries of the single-stage pressing process varies greatly.

[0134] Attached Fig.14 This is the current pore volume fraction distribution diagram corresponding to the compact displacement of 6.2 mm. The pore volume fraction of the two-stage pressing process is evenly distributed in layers, while the pore volume fractions of the upper and lower boundaries of the single-stage pressing process vary greatly.

[0135] Attached Fig.15 This is the distribution diagram of the contact force between the powder and the die corresponding to the two-stage pressing and the pressing displacement of 6.2 mm. The minimum contact stress between the powder and the die is 6.45×10 7 N / m 2 , the maximum contact stress is 1.33×10 8 N / m 2 .

[0136] Attached Fig.16 is the distribution diagram of the average volume elastic strain change during the two-stage pressing. In the first stage of pressing (parameter between 0 and 1), the volume elastic strain of the powder changes linearly in the first stage, while there is no strain in the second stage. This is expected because the upper part of the powder is not present in the first stage of pressing. When the parameter increases from 1 to 1.1 (punch retraction after the first compaction), the powder rebounds elastically. The second stage of pressing starts when the parameter value reaches 1.1 and ends at a value of 2. During this loading process, the volume elastic strain of both the upper and lower parts of the powder changes linearly.

[0137] Attached Fig.17 is a punch pressure vs compact displacement plot. Shows punch pressure vs compact displacement for a two-stage and a single-stage process. The yield point and end point are almost the same for both cases, but the intermediate states are different. For the two-stage process, the punch motion has three stages: the first forward motion of the punch on the first powder die, the punch retracting backwards, and finally the first forward motion of the punch on the second powder die. For single-stage pressing, only the punch moves forward on the die.

[0138] It should be noted that relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0139] Although the present application has been described above with reference to specific embodiments, various modifications may be made thereto and parts thereof may be replaced with equivalents without departing from the scope of the present application. In particular, as long as there is no structural conflict, the various features in the specific embodiments disclosed in the present application may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A simulation analysis method for powder pressing, characterized in that: The steps include: S1. Use Comsol Multiphysics to establish the two-dimensional axisymmetric spatial dimension and select solid mechanics; S2. Establishing a geometric model of powder pressing, wherein the geometric model includes a metal powder part and a mold part, and the calculation domain of the geometric model includes a mold geometric area and a metal powder calculation domain; S3, respectively establish a definition part for setting two-stage pressing, a single-stage pressing mechanical simulation, a solid mechanics 1 part for setting simulation target parameters of two-stage pressing, and a solid mechanics 2 part for setting simulation target parameters of single-stage pressing; S4, setting material properties of the metal powder part and the mold part, and meshing the geometric model; S5. Select two-stage pressing and single-stage pressing, perform solution calculation, and obtain simulation results of powder pressing; S6. Process the simulation results to generate stress distribution diagram, relative density distribution diagram, volume plastic strain distribution diagram, current hole volume fraction distribution diagram, powder and mold contact force distribution diagram, two-stage pressing average elastic volume strain change distribution diagram, punch pressure and compact displacement distribution diagram.

2. A simulation analysis method for powder pressing according to claim 1, characterized in that: The specific implementation method of step S3 includes the following steps: S3.

1. Set the definition part to integral function intop1 and integral function intop2, set the variable Force1 to two-stage compression, Force2 to single-stage compression, and delta to axial compression; S3.

2. Set the solid mechanics 1 part as a linear elastic material, including setting the plastic strain, yield function F, and activation expression; set the rigid domain, including setting the initial value and fixed constraints; set the friction coefficient; Set specified displacement, including setting boundary and specifying displacement direction; set boundary load 1, including setting boundary load 1 boundary and total force F tot Function; Set boundary load 2, including setting boundary load 2 boundary, total force F tot function; S3.

3. Set the Solid Mechanics 2 part as a linear elastic material, including setting the plastic strain and the yield function F; set the rigid domain, including setting the initial value and the fixed constraint; set the friction coefficient; set the specified displacement 1, including setting the boundary and specifying the displacement direction; set the specified displacement 2, including setting the boundary and specifying the displacement function in the z direction.

3. A simulation analysis method for powder pressing according to claim 2, characterized in that: In step S3.1, the boundary of the integral function intop1 of the definition part is set to the selection boundary 5; Set the boundaries of the integral function intop2 to select the contact boundaries 6 and 7 between the metal powder part and the mold part, and do not calculate the integral in the rotational geometry; set the function Force1 = PunchForce (para) for two-stage pressing, Force2 = intop1 (-solid2.sz) for single-stage pressing, and delta = 1-intop2 (1) / (2*H0) for axial pressing.

4. A simulation analysis method for powder pressing according to claim 3, characterized in that: In step S3.2, the yield function F of the solid mechanics part 1 is set to Gurson-Tvergaard-Needleman, which represents the mesoscopic pore model theory; The activation expression is set to para>1, para (please give the meaning of the letters), activation domain 2; Set the rigid domain to selection domain 3; Set the friction coefficient to 0.05; Set the specified displacement boundary to Select boundary 2, specified in the z direction; Set the boundary load 1 boundary to select boundary 4, Set the total force Ftot1 function of boundary load 1 to: r = 0, z = -PunchForce(para)*(para<=1), PunchForce, which means applying load in the z direction; Set the boundary load 2 boundary to selected boundary 5, Set the total force Ftot2 function of boundary load 2 to r=0, z=-PunchForce(para)*(para>=1.1).

5. A simulation analysis method for powder pressing according to claim 4, characterized in that: In step S3.3, the yield function F of the solid mechanics part 2 is set to Gurson-Tvergaard-Needleman, which represents the mesoscopic pore model theory; Set the rigid domain to select only domain 3; Set the friction coefficient to 0.05; Set the Prescribed Displacement 1 boundary to Select Boundary 2, specified in the z direction; Set the specified displacement boundary to selected boundary 2 and the function in the z direction to disp to indicate the magnitude of the displacement suppressed in the positive direction.

6. A simulation analysis method for powder pressing according to claim 2, characterized in that: The method for setting the material properties of the metal powder part and the mold part in step S4 is: select a material for the metal powder part, select solid magnesium in the material library and add it, and set the initial yield stress to 200 MPa, the initial pore volume fraction to 0.28, the Tvergaard correction coefficient q1 to 1.5, the Tvergaard correction coefficient q2 to 1, the Tvergaard correction coefficient q3 to 2.25, the critical pore volume fraction to 0.36, and the failure pore volume fraction to 0.4; The method for meshing the geometric model is: meshing the geometric model in a customized form, setting the mapping to select boundary 10, the distribution boundary to select boundary 11, fixing the number of cells to 1, and setting the mesh cells to include 243 domain cells and 81 boundary cells.

7. A simulation analysis method for powder pressing according to claim 6, characterized in that: The specific implementation method of step S5 includes the following steps: S5.

1. Set up the study - two-stage pressing: including setting up the model configuration for modifying the study steps, canceling the deformation of the coordinate system controlled by Solid Mechanics 2, disabling Solid Mechanics 2 in the model, the auxiliary scanning type is the specified combination, the parameter is para (Parameter), the parameter value list is range (0, 0.1, 2) to describe the calculation starting from 0, calculating every 0.1, and ending at 2, and performing the solution calculation to obtain the simulation results of powder pressing, including the simulation results of stress distribution, the simulation results of relative density, the simulation results of parameter value volume plastic strain distribution, the simulation results of pore volume fraction distribution, the simulation results of powder and die contact force distribution, the simulation results of average elastic volume strain distribution, and the simulation results of punch pressure distribution of compact displacement; S5.

2. Set up the study - single-stage pressing: including setting up to cancel the generation of default drawings, modify the model configuration of the study step, cancel the solid mechanics 1 control coordinate system deformation, disable solid mechanics 1 in the model, the auxiliary scanning type is a specified combination, the parameter is disp (Displacement parameter), the parameter value list is range (0, 0.1, 6.2) to describe the calculation starting from 0, every 0.1, and ending at 6.2, and perform a solution calculation to obtain the simulation results of powder pressing, including the simulation results of stress distribution, the simulation results of relative density, the simulation results of parameter value volume plastic strain distribution, the simulation results of pore volume fraction distribution, the simulation results of powder and mold contact force distribution, the simulation results of average elastic volume strain distribution, and the simulation results of punch pressure distribution of compact displacement.

8. A simulation analysis method for powder pressing according to claim 7, characterized in that: The specific implementation method of step S6 includes the following steps: S6.

1. For the two-stage pressing stress distribution diagram, select the two-dimensional drawing group, select the simulation result of stress distribution to generate the stress distribution diagram; for the single-stage pressing stress distribution diagram, select the two-dimensional drawing group, select the simulation result of stress distribution of parameter value to generate the stress distribution diagram; S6.

2. For the relative density distribution diagram of two-stage pressing, select the three-dimensional drawing group, replace the expression with solid.lemm1.popl1.rhorel-current relative density, and select the simulation result of relative density to generate the relative density distribution diagram; for the relative density distribution diagram of single-stage pressing, select the three-dimensional drawing group, replace the expression with solid.lemm1.popl1.rhorel-current relative density on the basis of two-dimensional rotation, and select the simulation result of stress distribution to generate the relative density distribution diagram; S6.3, Volume Plastic Strain Distribution Diagram Select the 2D drawing group, copy the contour line, set the expression to: if(isnan(solid2.f), NaN, solid2.f), which indicates volume plastic strain, Gaussian point calculation, translation y50[mm], which indicates moving the single-stage pressing volume plastic strain diagram 50 mm to the y axis, and select the parameter value Volume Plastic Strain Distribution Simulation Results to generate the volume plastic strain distribution diagram; S6.4, Current void volume fraction distribution diagram Select the 2D drawing group, copy the contour line, set the expression to if(isnan(solid2.f), NaN, solid2.f), which indicates the current void volume fraction, translate y50[mm], which indicates moving the single-stage current void volume fraction distribution diagram 50 mm to the y-axis, and select the simulation result of the parameter value current void volume fraction distribution; S6.5, Powder-die contact force distribution diagram Select the 2D plot group and select the parameter value Powder-die contact force distribution simulation result; S6.

6. Distribution of average elastic volume strain variation in two-stage pressing Select a one-dimensional plot group to characterize and display the average elastic volume strain distribution of two-stage pressing with different parameter values, where the horizontal axis is the parameter value and the vertical axis is the average elastic volume strain; S6.

7. Select a one-dimensional drawing group to characterize and display the punch pressure distribution for different blank displacements, where the horizontal axis is the blank displacement and the vertical axis is the punch pressure.

9. A simulation analysis device for powder pressing, implemented by a simulation analysis method for powder pressing according to any one of claims 1 to 8, characterized in that: Includes creation modules for establishing the spatial dimensions of two-dimensional axisymmetry and selecting solid mechanics; A modeling module, used for establishing a geometric model of powder pressing, wherein the geometric model includes a metal powder part and a mold part, and the calculation domain of the geometric model includes a geometric region and a metal powder calculation domain; The first setting module is used to set the definition part, the solid mechanics 1 part, and the solid mechanics 2 part respectively; A second setting module is used to set the material properties of the metal powder part and the mold part; A partitioning module, used for performing mesh partitioning on the geometric model, wherein the mesh units include 243 domain units and 81 boundary units; A solution module is used to set up a study-two-stage pressing, including setting and modifying the model configuration and auxiliary scanning of the study steps; setting up a study-single-stage pressing, including establishing the study settings, modifying the model configuration and auxiliary scanning of the study steps; and performing solution calculation to obtain the simulation results of each powder pressing; A generation module is used to process each of the simulation results to generate a stress distribution diagram, a relative density distribution diagram, a volume plastic strain distribution diagram, a current pore volume fraction distribution diagram, a powder and mold contact force distribution diagram, a two-stage pressing average elastic volume strain change distribution diagram, and a mold pressure and displacement distribution diagram.

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