Finite element-based modeling and simulation method for continuous rolling of automobile steel sheet billet

Abstract

According to the modeling simulation method for continuous rolling of the automobile steel sheet billet based on the finite element, a sheet billet continuous rolling system model is composed of a plurality of rolling sub-models, each rolling sub-model corresponds to one rolling pass in an actual production line, and besides finite element analogue simulation of the first pass of sheet billet rolling, the finite element analogue simulation of the second pass of sheet billet rolling is simulated; before the finite element analogue simulation of the subsequent pass of thin slab rolling is started, calling the current pass of rolling sub-model, and mapping the stress field, the strain field, the temperature field and the work hardening degree of the rolled thin slab obtained in the previous pass to the same coordinate position of the current pass by adopting a Map Solution mapping method; in the prior art, only a single-stand model is used for analog simulation, dynamic coupling of a stress field, a strain field and a temperature field among multi-pass rolling in an actual production line and transmission of the work hardening degree of a plate blank among the multi-pass rolling are neglected, and continuous deformation characteristics of the thin plate blank in the actual hot continuous rolling production line cannot be accurately reflected; and prediction deviation is generated.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hot continuous rolling simulation, and in particular to a thin slab continuous rolling modeling and simulation method for automobile steel based on finite elements. BACKGROUND

[0002] Automobile steel, as the core material of modern automobile manufacturing, its mechanical properties and forming quality directly affect the safety and lightweight level of vehicles. Hot continuous rolling process significantly improves the strength and ductility of steel through multi-pass continuous rolling at high temperature, and is a key technology for large-scale production of automobile steel plate blanks. Before actual production, numerical simulation of the rolling process is usually carried out with the help of finite element analysis method to predict the metal flow law, optimize the rolling parameters and evaluate the internal residual stress distribution of the plate, so as to reduce the trial and error cost and improve the yield.

[0003] However, the finite element analysis in the prior art is usually simulated by using a single stand model. This simulation method can only reflect the local deformation behavior in a single rolling pass, ignores the dynamic coupling effect of stress field, strain field and temperature field in the multi-pass continuous rolling process, and also ignores the transfer of the degree of work hardening of the slab between different passes, resulting in that the simulation result cannot accurately reflect the continuous deformation characteristics of the thin slab in the actual hot continuous rolling line, and produces prediction deviation, which restricts the fine adjustment of the process parameters and the improvement of the product quality. SUMMARY

[0004] The purpose of the embodiments of the present application is to provide a thin slab continuous rolling modeling and simulation method for automobile steel based on finite elements, which solves the technical problem that in the prior art, only a single stand model is used for simulation, this simulation method can only reflect the local deformation behavior in a single rolling pass, ignores the dynamic coupling of stress field, strain field and temperature field in the actual multi-pass rolling line, ignores the transfer of the degree of work hardening of the slab between different passes in the actual multi-pass rolling line, cannot accurately reflect the continuous deformation characteristics of the thin slab in the actual hot continuous rolling line, and produces prediction deviation.

[0005] To achieve the above-mentioned purpose, the technical solutions adopted by the embodiments of the present application are as follows:

[0006] A thin slab continuous rolling modeling and simulation method for automobile steel based on finite elements, the method comprising the following steps:

[0007] S100: Based on the actual process parameters of the thin slab continuous rolling line, a plurality of rolling sub-models for simulating the rolling process of a single-pass thin slab are established in sequence, and the plurality of rolling sub-models collectively constitute a thin slab continuous rolling system model;

[0008] S200: finite element simulation of the first pass thin slab rolling is performed to obtain a calculation result file containing stress field, strain field, temperature field and work hardening degree data of the rolled thin slab;

[0009] S300: finite element simulation of subsequent pass thin slab rolling is performed in sequence to obtain calculation result files containing stress field, strain field, temperature field and work hardening degree data of the thin slab after each pass rolling, wherein before performing finite element simulation of each pass thin slab rolling, the rolling sub-model of the current pass is called, and the stress field, strain field, temperature field and work hardening degree of the rolled thin slab obtained in the previous pass are mapped into the same coordinate position of the current pass by using the Map Solution mapping method;

[0010] S400: the calculation result files of each pass are read in sequence, and animation demonstration of each pass thin slab rolling, thin slab surface node stress, strain and temperature data and thin slab core node stress, strain and temperature data are output.

[0011] In the finite element-based thin slab continuous rolling modeling and simulation method for automobile steel described in the embodiments of the present application, the step S100 includes the following steps:

[0012] S101: based on the actual geometric dimensions of the thin slab and the roll in each rolling pass on the thin slab continuous rolling production line, the thin slab and the roll in each pass are modeled, and a drive rod model is established in each pass to control the thin slab biting into the roll by the displacement of the drive rod;

[0013] S102: a half-simplified model is used for the thin slab and the roll in a single pass;

[0014] S103: based on the distance from the thin slab inlet to the roll in each pass and the roll pressing amount in each pass, the thin slab and the roll in each pass are assembled, the thin slab, the roll and the drive rod in each pass are taken as a rolling sub-model, and multiple rolling sub-models are connected in series to form a thin slab continuous rolling system model.

[0015] In the finite element-based thin slab continuous rolling modeling and simulation method for automobile steel described in the embodiments of the present application, the step S200 includes the following steps:

[0016] S201: the thin slab and the roll material and cross-section attributes are assigned: including the density, elastic modulus, stress-strain curve, Poisson's ratio, thermal conductivity, specific heat capacity and thermal expansion rate of the material at different temperatures;

[0017] S202: setting two analysis steps: setting a first analysis step of a first pass and a second analysis step of the first pass, the first analysis step of the first pass is used to simulate the transmission process of the thin slab between the thin slab inlet and the first pass roller, and the second analysis step of the first pass is used to simulate the rolling process of the thin slab in the first pass;

[0018] S203: setting interaction: the interaction of the thin slab and the roller, the interaction of the thin slab and the driving rod, the convection heat exchange of the thin slab with air, and the radiation heat exchange of the thin slab with air;

[0019] S204: setting constraints and boundary conditions: selecting the center of the roller as a reference point, constraining the whole roller as a rigid body, and constraining the horizontal displacement of the roller, selecting the center of the driving rod as a reference point, constraining the whole driving rod as a rigid body, defining the symmetry constraint of the thin slab about its bottom surface, defining the initial rotating speed of the roller, defining the initial temperature of the roller, defining the initial temperature of the thin slab, defining the initial speed of the thin slab, and defining the initial displacement of the driving rod;

[0020] S205: setting mesh division: mesh division is performed on the roller and the thin slab;

[0021] S206: submitting a finite element simulation modeling task of the first pass thin slab rolling, and obtaining a calculation result file containing the stress field, strain field, temperature field and work hardening degree data of the rolled thin slab.

[0022] In the finite element-based modeling and simulation method of the thin slab continuous rolling of the automobile steel described in the embodiments of the present application, the step S300 comprises the following steps:

[0023] S301: calling the thin slab, roller and driving rod model of the current pass;

[0024] S302: using the Map Solution mapping method to map the stress field, strain field, temperature field and work hardening data of the rolled thin slab obtained in the previous pass to the same coordinate position in the current pass;

[0025] S303: based on the principle of equal flow rate, the thickness of the thin slab in the previous pass, the speed of the thin slab in the previous pass, the thickness of the thin slab in the current pass and the size of the roller in the current pass, the speed of the thin slab in the current pass and the rotating speed of the roller are obtained;

[0026] S304: re-assign material and cross-section properties to the current pass slab and rolls, set the first analysis step and the second analysis step of the current pass, set the interaction of the current pass, set the constraints and boundary conditions of the current pass, re-mesh the current pass slab and rolls, submit the finite element simulation task of the current pass slab rolling, and obtain the calculation result file containing the stress field, strain field, temperature field and work hardening degree data of the rolled slab of the current pass.

[0027] S305: repeat steps S301 to S304 until the finite element simulation of the entire pass slab rolling is completed, and obtain the calculation result file containing the stress field, strain field, temperature field and work hardening degree data of the rolled slab of each pass.

[0028] In the finite element-based modeling and simulation method for automobile steel thin slab continuous rolling described in the embodiments of the present application, the second analysis step opens the Nlgeom switch.

[0029] In the finite element-based modeling and simulation method for automobile steel thin slab continuous rolling described in the embodiments of the present application, when meshing, the mesh element uses a thermal-mechanical coupled plane strain reduced integration element CPE4RT.

[0030] In the finite element-based modeling and simulation method for automobile steel thin slab continuous rolling described in the embodiments of the present application, when the thin slab first contacts the roll, the meshing of the thin slab near one end of the roll uses smaller mesh elements.

[0031] In the finite element-based modeling and simulation method for automobile steel thin slab continuous rolling described in the embodiments of the present application, the step S400 includes the following steps:

[0032] S401: call the Python program for blocking batch processing, read the calculation result files of the first pass and all subsequent passes in turn, set the symmetric mirror, generate the complete model result file of each pass, and obtain the complete rolling window;

[0033] S402: based on the complete model result file of each pass, export the animation demonstration of the stress field, strain field and temperature field of the thin slab rolling process of each pass;

[0034] S402: according to the assembly position of each pass thin slab in the thin slab continuous rolling system model, position the surface nodes and core nodes of each pass thin slab, read and export the stress, strain and temperature data of each pass thin slab surface node changing with time from the complete model result file of each pass in turn, and read and export the stress, strain and temperature data of each pass thin slab core node changing with time from the complete model result file of each pass in turn.

[0035] Compared with the prior art, the embodiments of the present application have the following beneficial effects:

[0036] From the above technical solution, the modeling and simulation method for thin slab continuous rolling of automobile steel based on finite elements provided by the embodiments of the present application, by dividing the thin slab continuous rolling system model into multiple rolling sub-models, each rolling sub-model corresponds to one rolling pass in the actual production line, in addition to the finite element simulation of the first pass thin slab rolling, before the start of the finite element simulation of the subsequent pass thin slab rolling, the rolling sub-model of the current pass is called, the stress field, strain field, temperature field and work hardening degree of the rolled thin slab obtained by the finite element simulation of the previous pass thin slab rolling are mapped into the same coordinate position of the current pass, ensuring the continuity of the stress field, strain field, temperature field and work hardening degree in the finite element simulation of the multi-pass thin slab rolling, solving the technical problem that in the prior art, since only a single stand model is used for simulation and simulation, this simulation method can only reflect the local deformation behavior in a single rolling pass, ignoring the dynamic coupling of the stress field, strain field and temperature field between the multi-pass rolling in the actual production line, ignoring the transmission of the work hardening degree of the slab between the multi-pass rolling in the actual production line, and cannot accurately reflect the continuous deformation characteristics of the thin slab in the actual hot continuous rolling production line, resulting in prediction deviation. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below, the drawings are not intended to be drawn to scale, and in order to be clear, not every component will be marked in each figure. The drawings in the following description are only some embodiments of the present application, and other drawings can be obtained from these drawings without creative labor for those skilled in the art. Among them:

[0038] Figure 1 The step flow chart of the modeling and simulation method of the embodiments of the present application.

[0039] Figure 2 The schematic diagram of the thin slab and the half model of the rolling mill in the embodiments of the present application.

[0040] Figure 3 The temperature distribution comparison chart before and after the grid redivision of the thin slab after the first pass rolling in the embodiments of the present application.

[0041] Figure 4 The stress distribution chart of the thin slab at a certain time from the first pass to the seventh pass in the embodiments of the present application.

[0042] Figure 5 The surface node temperature curve chart and the stress curve chart of the thin slab after seven pass rolling in the embodiments of the present application. DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0044] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" and the like are based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly specified and limited.

[0045] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0046] In the present application, unless otherwise explicitly specified and limited, the "upper" or "lower" of the first feature to the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the "upper", "above" and "on" of the first feature to the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "below", "under" and "under" of the first feature to the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0047] The following disclosure provides many different embodiments, or examples, for implementing different structures of the present application. For the purpose of simplifying the present application, the components and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeatedly refer to numbers and / or letters in different examples, and such repetition is for the purpose of simplification and clarity, which does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the present application provides examples of various specific processes and materials, but those of ordinary skill in the art can realize the application of other processes and / or the use of other materials.

[0048] The embodiment of the present application provides a finite element-based thin slab continuous casting and rolling modeling simulation method for automobile steel, as shown in the figure. Figures 1 to 5 The finite element-based thin slab continuous casting and rolling modeling simulation method for automobile steel comprises the following steps:

[0049] Step S100: Based on the actual process parameters of the thin slab continuous casting and rolling production line, a plurality of rolling sub-models for simulating single-pass thin slab rolling process are sequentially established, and the plurality of rolling sub-models collectively constitute a thin slab continuous casting and rolling system model.

[0050] In the embodiment, the actual thin slab continuous casting and rolling production line has 7 stands, and the thin slab is continuously rolled 7 times.

[0051] In some embodiments, the step S100 comprises the following steps:

[0052] S101: Based on the actual geometric dimensions of the thin slab and the roll on each rolling pass on the thin slab continuous casting and rolling production line, the thin slab and the roll on each pass are modeled, and a driving rod model is established on each pass to control the thin slab biting into the roll by the displacement of the driving rod.

[0053] In the embodiment of the present application, the thin slab, the roll and the driving rod model are established in Abaqus software, the dimensions of the thin slab, the roll and the driving rod in each rolling pass are shown in Table 1, the roll is a solid in the actual production line, and is simplified as a concentric cylinder model in modeling to optimize the calculation efficiency, and the wall thickness is set to 20mm. The length of the driving rod is shown in Table 1, which needs to be greater than the thickness of the slab before rolling to provide uniform stress, and cannot be too long to avoid collision with the roll, and the values in the table are reasonable values obtained by test.

[0054] Table 1 Dimensions of thin slab, roll and driving roll

[0055]

[0056] S102: A half-simplified model is used for the thin slab and the roll in a single pass.

[0057] Wherein, by setting the thin slab and the roll as a half simplified model, the three-dimensional hot rolling process is simplified as a two-dimensional plane strain problem, and the calculation amount is reduced.

[0058] S103: Assembling the thin slab and the roll in each pass based on the distance from the thin slab inlet to the roll in each pass and the roll reduction in each pass, the thin slab and the roll in each pass and the driving rod as a rolling sub-model, and a plurality of rolling sub-models in series to form a thin slab continuous rolling system model.

[0059] Wherein, the distance from the thin slab inlet to the roll in each pass is 3000mm, 8500mm, 14000mm, 19500mm, 25000mm, 30500mm and 36000mm, i.e. the distance from the thin slab inlet to the roll in the first pass is 3000mm, the distance between the rolls in adjacent passes is 5500mm, and the roll reduction in the first to seventh passes is 44.89%, 53.99%, 51.97%, 40.51%, 28.53%, 30.47% and 14.20% respectively, for example, in the first pass, the roll reduction is 44.89%, and the thin slab with a thickness of 90mm before rolling is rolled to 49.6mm.

[0060] Step S200: Finite element simulation of the first-pass thin slab rolling is performed to obtain a calculation result file containing the stress field, strain field, temperature field and work hardening degree data of the rolled thin slab.

[0061] In some embodiments, the step S200 includes the following steps:

[0062] Step S201: Assigning material and cross-section attributes to the thin slab and the roll: including the density, elastic modulus, stress-strain curve, Poisson's ratio, thermal conductivity, specific heat capacity and thermal expansion rate of the material at different temperatures.

[0063] Wherein, the thermal simulator applies a constant true strain rate (0.01s-1, 0.1s-1, 1s-1) at 1100℃ and 900℃ respectively until the end to obtain the stress-strain curve, density, elastic modulus, Poisson's ratio, thermal conductivity, specific heat capacity and thermal expansion rate as shown in Table 2. -1 ,0.1s -1 , 0.01s -1

[0064] Table 2 Material and cross-section attributes

[0065]

[0066] ​​Step S202: Set two analysis steps: Set the first analysis step and the second analysis step of the first pass. The first analysis step of the first pass is used to simulate the transfer process of the thin slab from the thin slab inlet to the first pass rolls. The second analysis step of the first pass is used to simulate the rolling process of the thin slab in the first pass. Considering the geometric nonlinear effect, the Nlgeom switch is turned on in the second analysis step.

[0067] Among them, the time of the first analysis step of the first pass. , The distance from the slab inlet to the first pass roll is 3000 mm. The length of the thin slab before the first rolling pass is 500 mm. The slab speed before the first rolling pass is 186.78 mm / s. The initial increment step of the first analysis step in the first pass is 0.1, and the minimum step size is 1 × 10⁻⁶. -5 The maximum step size is 0.1, and the time for the second analysis step in the first pass is... The initial increment step for the second analysis step is 0.005, and the minimum step size is 1×10. -6 The maximum step size is 0.005.

[0068] Step S203: Set the interaction: interaction between the slab and the roll, interaction between the slab and the drive rod, convective heat transfer between the slab and the air, and radiative heat transfer between the slab and the air.

[0069] Specifically, the thin slab and the rolls are configured for surface-to-surface contact, with the outer ring of the rolls designated as the master surface. The front, upper, and rear planes of the thin slab are collectively designated as slave surfaces to prevent deformation during rolling from causing contact between the rolls and the front and rear planes. Normal contact is configured as hard contact, allowing separation after contact. Tangential contact employs a penalty function method, with a tangential friction coefficient set to 0.35 to ensure continuous feeding of the thin slab by the rolls. The thermal conductivity of the thin slab in contact with the rolls is set to 12 mW / (mm²K). The thin slab and the drive rod are configured for surface-to-surface contact. The drive rod is set as... The main face and the back plane of the thin slab are set as the secondary face, the normal is set as hard contact, separation is allowed after contact, the tangential is the penalty contact method, and the tangential friction coefficient is set to 0.005. Considering the convective heat transfer caused by air flow during the hot rolling of the thin slab, heat is transferred between the air and the surface of the thin slab. Assuming that the rolling process is in a windless state, the convective heat transfer coefficient of the upper surface of the thin slab is set to 0.25mW / (mm²K), the ambient temperature is 30℃, and considering the radiative heat transfer of the thin slab through electromagnetic wave radiation and absorption, the emissivity of the upper surface of the thin slab is set to 0.7.

[0070] Step S204: setting constraints and boundary conditions: taking the center of the roll as the reference point, the entire roll is constrained as a rigid body, and the horizontal displacement of the roll is constrained, taking the center of the driving rod as the reference point, the entire driving rod is constrained as a rigid body, defining the symmetry constraint of the thin slab about its bottom surface, defining the initial rotational speed of the roll, defining the initial temperature of the roll, defining the initial temperature of the thin slab as 80℃, defining the initial speed of the thin slab as 186.78mm / s, and defining the initial displacement of the driving rod.

[0071] Specifically, the symmetry constraint of the thin slab bottom surface is defined, the freedom degrees of its Y direction, around X axis and around Z axis are set to 0, the freedom degrees of X direction and Y direction of the roll center are set to 0, the initial temperature of the roll is 80℃, and the initial displacement of the driving rod is 3000mm, that is, in the first pass, the displacement of the driving rod is 3000mm.

[0072] Step S205: setting grid division: grid division is performed on the roll and the thin slab.

[0073] Specifically, when grid division is performed, the thermal force coupling plane strain reduced integration element CPE4RT is used. When the thin slab first contacts the roll, the grid division of the thin slab near the end of the roll uses smaller grid elements, for example, in the first pass, when the thin slab first contacts the roll, the element length of the thin slab near the end of the roll is 2mm, and the element length of the thin slab away from the end of the roll is 4mm.

[0074] Step S206: submitting a finite element simulation task for the first-pass thin slab rolling, and obtaining a calculation result file containing the stress field, strain field, temperature field and work hardening degree data of the rolled thin slab.

[0075] Step S300: sequentially performing finite element simulation of subsequent pass thin slab rolling, and obtaining calculation result files containing stress field, strain field, temperature field and work hardening degree data of the thin slab after each pass, wherein before performing finite element simulation of each pass of thin slab rolling, the rolling sub-model of the current pass is called, and the stress field, strain field, temperature field and work hardening degree data of the rolled thin slab obtained in the last pass are mapped into the same coordinate position of the current pass by using the Map Solution mapping method.

[0076] In some embodiments, the step S300 includes the following steps:

[0077] S301: calling the thin slab, roll and driving rod model of the current pass, that is, calling the rolling sub-model of the current pass.

[0078] S302: Map the stress field, strain field, temperature field and work hardening data of the sheet bar after rolling obtained in the previous pass to the same coordinate position in the current pass by using the Map Solution mapping method;

[0079] wherein the same coordinate position means that the coordinate position of the sheet bar at the end of the previous pass is the same as the coordinate position of the sheet bar at the beginning of the current pass.

[0080] Step S303: Obtain the sheet bar speed and roll speed in the current pass based on the principle of equal flow rate, the thickness of the sheet bar in the previous pass, the speed of the sheet bar in the previous pass, the thickness of the sheet bar in the current pass, and the roll size in the current pass.

[0081] Specifically, , represents the thickness of the sheet bar in the i-th pass, which is obtained from Table 1, , is the roll speed in the i-th pass, is the sheet bar speed in the i-th pass, is the roll radius in the i-th pass, which can be obtained from the roll diameter in Table 1.

[0082] wherein the sheet bar speed in each pass and the roll speed in each pass are shown in Table 3 below.

[0083] Table 3: Sheet bar speed in each pass and roll speed in each pass

[0084]

[0085] Step S304: Re-assign material and cross-section properties to the sheet bar and roll in the current pass, set the first analysis step and the second analysis step in the current pass, turn on the Nlgeom switch in the second analysis step, set the interaction in the current pass, set the constraint and boundary conditions in the current pass, re-mesh the sheet bar and roll in the current pass, submit the finite element simulation task for rolling the sheet bar in the current pass, and obtain the calculation result file containing the stress field, strain field, temperature field and work hardening degree data of the sheet bar after rolling in the current pass.

[0086] wherein, different from the finite element simulation of the first pass sheet bar rolling, from the finite element simulation of the second pass sheet bar rolling, the first analysis step is used to simulate the mapping inheritance of stress field, strain field, temperature field and work hardening degree and simulate the transmission process of the sheet bar between adjacent passes, and the time of the first analysis step in the subsequent passes is , is 5500 mm, is the length of the sheet bar in the current pass, which is obtained from Table 1, the time of the second analysis step in each subsequent pass for the current pass thin slab speed the driving rod displacement in each subsequent pass is the distance between adjacent rolls minus the thin slab length in each pass, which is - .

[0087] Step S305: Steps S301 to S304 are repeatedly executed until the finite element simulation of the entire pass thin slab rolling is completed, and the calculation result file containing the stress field, strain field, temperature field and work hardening degree data of the thin slab after each pass rolling is obtained.

[0088] Specifically, the grid division of the thin slab and the roll in each pass is shown in Table 4.

[0089] Table 4 Grid division of thin slab and roll in each pass

[0090]

[0091] Step S400: Read each pass calculation result file in turn, output the animation demonstration of each pass thin slab rolling, export the thin slab surface node stress, strain, temperature data, and export the thin slab core node stress, strain, temperature data.

[0092] In some embodiments, the step S400 includes the following steps:

[0093] Step S401: Call the Python program for blocking batch processing, read the calculation result file of the first pass and all subsequent passes in turn, set the symmetric mirror image, generate the complete model result file of each pass, and obtain the complete rolling window.

[0094] S402: Based on the complete model result file of each pass, export the animation demonstration of the stress field, strain field and temperature field of each pass thin slab rolling process.

[0095] S402: According to the assembly position of each pass thin slab in the thin slab continuous rolling system model, position the surface nodes and core nodes of each pass thin slab, read and export the data of the stress, strain and temperature of the surface nodes of each pass thin slab changing with time from the complete model result file of each pass in turn, and read and export the data of the stress, strain and temperature of the core nodes of each pass thin slab changing with time from the complete model result file of each pass in turn.

[0096] Specifically, define (0, 0) as the coordinate origin, at this time, the center coordinates of the first pass roll are (0, 498.8), the lowest point coordinates of the first pass roll are (0, 24.8), and the surface node and core node coordinates of each pass thin slab are shown in Table 5.

[0097] Table 5 Surface node and core node coordinates of each pass thin slab

[0098]

[0099] In summary, the automobile steel thin slab continuous rolling modeling simulation method based on finite elements provided by the embodiments of the present application divides the thin slab continuous rolling system model into multiple rolling sub-models, each rolling sub-model corresponds to one rolling pass in the actual production line, in addition to the finite element simulation of the first pass thin slab rolling, before the start of the finite element simulation of the subsequent pass thin slab rolling, the rolling sub-model of the current pass is called, and the stress field, strain field, temperature field and work hardening degree of the rolled thin slab obtained by the finite element simulation of the previous pass thin slab rolling are mapped into the same coordinate position of the current pass, ensuring the continuity of the stress field, strain field, temperature field and work hardening degree in the finite element simulation of the multi-pass thin slab rolling, solving the technical problem that the existing technology only uses single stand model for simulation, this simulation method can only reflect the local deformation behavior in a single rolling pass, ignoring the dynamic coupling of the stress field, strain field and temperature field between the multi-pass rolling in the actual production line, ignoring the transmission of the work hardening degree of the slab between the multi-pass rolling in the actual production line, and cannot accurately reflect the continuous deformation characteristics of the thin slab in the actual hot continuous rolling production line, resulting in prediction deviation.

[0100] The automobile steel thin slab continuous rolling modeling simulation method based on finite elements provided by the embodiments of the present application is described in detail above, and the principles and implementation modes of the present application are described by applying specific examples; the above embodiment description is only used to help understand the technical solutions and core ideas of the present application; those skilled in the art should understand that the technical solutions recorded in the above embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A finite element-based modeling and simulation method for thin slab casting and rolling of automotive steel sheets, characterized in that, The method comprises the following steps: S100: based on the actual process parameters of the thin slab continuous rolling production line, a plurality of rolling sub-models for simulating single-pass thin slab rolling process are sequentially established, and the plurality of rolling sub-models collectively constitute a thin slab continuous rolling system model; S200: finite element simulation of the first-pass thin slab rolling is performed to obtain a calculation result file containing stress field, strain field, temperature field and work hardening degree data of the rolled thin slab; S300: finite element simulation of subsequent-pass thin slab rolling is sequentially performed to obtain calculation result files containing stress field, strain field, temperature field and work hardening degree data of the rolled thin slab at each pass, wherein before performing the finite element simulation of each-pass thin slab rolling, the rolling sub-model of the current pass is called, and the Map Solution mapping method is used to map the stress field, strain field, temperature field and work hardening degree of the rolled thin slab obtained at the previous pass to the same coordinate position of the current pass; S400: the calculation result files of each pass are sequentially read, and animation demonstration of each-pass thin slab rolling, thin slab surface node stress, strain and temperature data and thin slab core node stress, strain and temperature data are output.

2. The finite element-based thin slab casting and rolling modeling and simulation method of an automotive steel sheet as claimed in claim 1, characterized in that, The step S100 comprises the following steps: S101: based on the actual geometric dimensions of the thin slab and the roll at each rolling pass on the thin slab continuous rolling production line, the thin slab and the roll at each pass are modeled, and a driving rod model is established at each pass to control the thin slab biting into the roll by the displacement of the driving rod; S102: a half-simplified model is used for the thin slab and the roll in the single pass; S103: based on the distance from the thin slab inlet to the roll at each pass and the roll pressing amount at each pass in the thin slab continuous rolling production line, the thin slab and the roll at each pass are assembled, the thin slab, the roll and the driving rod at each pass are taken as a rolling sub-model, and a plurality of rolling sub-models are connected in series to constitute a thin slab continuous rolling system model.

3. The finite element-based thin slab casting and rolling modeling and simulation method of an automotive steel sheet as claimed in claim 2, characterized in that, The step S200 comprises the following steps: S201: the thin slab and the roll material and cross-section attributes are assigned, including the density, elastic modulus, stress-strain curve, Poisson's ratio, thermal conductivity, specific heat capacity and thermal expansion rate of the material at different temperatures; S202: two analysis steps are set: a first analysis step of the first pass and a second analysis step of the first pass, the first analysis step of the first pass is used to simulate the transmission process of the thin slab between the thin slab inlet and the roll of the first pass, and the second analysis step of the first pass is used to simulate the thin slab rolling process of the first pass; S203: interaction is set: interaction between the thin slab and the roll, interaction between the thin slab and the driving rod, convective heat transfer between the thin slab and the air, and radiative heat transfer between the thin slab and the air; S204: setting constraints and boundary conditions: selecting the center of the roll as the reference point, constraining the entire roll as a rigid body, and constraining the horizontal displacement of the roll; selecting the center of the drive rod as the reference point, constraining the entire drive rod as a rigid body, defining the symmetry constraint of the thin slab about its bottom surface, defining the initial rotational speed of the roll, defining the initial temperature of the roll, defining the initial temperature of the thin slab, defining the initial speed of the thin slab, and defining the initial displacement of the drive rod; S205: setting grid division: performing grid division on the roll and the thin slab; S206: submitting a finite element simulation task for the first-pass thin slab rolling, and obtaining a calculation result file containing the stress field, strain field, temperature field, and work hardening degree data of the rolled thin slab.

4. The finite element-based thin slab casting and rolling modeling and simulation method of an automotive steel sheet as claimed in claim 3, characterized in that, The step S300 includes the following steps: S301: calling the thin slab, roll, and drive rod models of the current pass; S302: using the Map Solution mapping method to map the stress field, strain field, temperature field, and work hardening data of the rolled thin slab obtained in the previous pass to the same coordinate position in the current pass; S303: based on the principle of equal flow rate, the thickness of the thin slab in the previous pass, the speed of the thin slab in the previous pass, the thickness of the thin slab in the current pass, and the size of the roll in the current pass, obtaining the speed of the thin slab and the rotational speed of the roll in the current pass; S304: re-assigning material and cross-sectional properties to the thin slab and roll in the current pass, setting the first analysis step and the second analysis step in the current pass, setting the interaction in the current pass, setting the constraints and boundary conditions in the current pass, re-dividing the grid of the thin slab and roll in the current pass, submitting a finite element simulation task for the thin slab rolling in the current pass, and obtaining a calculation result file containing the stress field, strain field, temperature field, and work hardening degree data of the rolled thin slab in the current pass.

5. S305: repeating steps S301 to S304 until the finite element simulation of the entire-pass thin slab rolling is completed, and obtaining calculation result files containing the stress field, strain field, temperature field, and work hardening degree data of the rolled thin slab in each pass.

6. The finite element-based thin slab casting and rolling modeling and simulation method of an automotive steel sheet as claimed in claim 4, characterized in that, The second analysis step opens the Nlgeom switch.

7. The finite element-based thin slab casting and rolling modeling and simulation method of an automotive steel sheet as claimed in claim 3 or 4, characterized in that, When performing grid division, the grid elements use thermal-mechanical coupled plane strain reduced integration elements CPE4RT.

8. The finite element-based thin slab casting and rolling modeling and simulation method of an automotive steel sheet as claimed in claim 3 or 4, characterized in that, When the thin slab first contacts the roll, the grid division of the thin slab near the end of the roll uses smaller grid elements.

9. The finite element-based thin slab mill modeling and simulation method for automotive steel sheets of claim 2, wherein, The step S400 includes the following steps: S401: calling the Python program for blocking batch processing, sequentially reading the calculation result files of the first pass and all subsequent passes, setting the symmetric mirror, generating complete model result files for each pass, and obtaining a complete rolling window; S402: based on the complete model result files of each pass, exporting an animation demonstration of the stress field, strain field, and temperature field of the thin slab during rolling in each pass; S402: According to the assembly position of the thin slab in each pass of the thin slab continuous rolling system model, the surface nodes and core nodes of the thin slab in each pass are positioned, the data of the stress, strain and temperature of the surface nodes of the thin slab in each pass changing with time are read and exported from the complete model result file of each pass in turn, and the data of the stress, strain and temperature of the core nodes of the thin slab in each pass changing with time are read and exported from the complete model result file of each pass in turn.

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