A method for predicting the shape of hot strip rolled considering the hot roll shape of the work roll

Abstract

The present application provides a method for predicting the shape of hot-rolled strip steel considering the hot roll type of the working roll, and relates to the field of data processing. The method establishes a three-dimensional finite element model of the working roll thermal convexity, a rolling finite element model, and a strip cooling finite element model according to the data collected at the actual production site. The segmented modeling method is adopted to decompose the entire hot rolling process into multiple sub-models, and data transmission and grid re-division can ensure that the strip steel plate convexity, width and temperature between the sub-models are basically consistent, and all sub-models are coupled into a whole. The model is made closer to reality, which not only solves the problem of excessive unit elongation during the hot rolling of the strip steel, improves the accuracy of the model, but also greatly reduces the time cost of errors and modifications in the simulation process, and the calculation speed is faster and the requirements for the computing platform are lower.

Description

Technical Field

[0001] The present application belongs to the technical field of data processing, relates to the automatic control technology of rolling process, and specifically to a method for predicting the shape of hot-rolled strip steel taking into account the hot roll type of working rolls. Background Art

[0002] With the rapid development of computer technology and commercial finite element software, multi-pass continuous hot rolling simulation has become possible and has been promoted. The hot rolling process has typical characteristics such as high control accuracy requirements, multiple process parameter couplings, short dynamic response time, and strong production stability and continuity. The study of a single stand will inevitably ignore the influence of the previous field on the next field, which will inevitably introduce a certain degree of calculation error between the stands. In order to eliminate this error, it is necessary to establish a multi-stand continuous finite element model for hot rolling. In addition, since the hot roll shape of the roll directly affects the shape of the loaded roll gap, studying the thermal behavior of the working roll and predicting its thermal convexity to eliminate its disturbance to the quality of the plate and strip, such as plate shape and plate thickness, is not only of direct and important significance to plate shape control, but also has an important guiding and reference role in the study of hot rolling free schedule rolling.

[0003] Regarding the simulation of hot rolling process and roller thermal crown, we found that some domestic researchers have done some related research:

[0004] The Chinese invention patent "A finite element simulation method for hot rolling multi-stand plate shape" with publication number CN111695279A invented a finite element simulation method for hot rolling multi-stand plate shape. Based on the segmented modeling strategy, a hot rolling thermal-mechanical elastic-plastic three-dimensional coupling finite element model was established, and the finishing mill was divided into multiple sub-models. A data transmission technology was proposed to integrate the sub-models into a complete model by transmitting the strip convexity and temperature information between the sub-models. The active and non-active unit methods, rigid push technology and unit re-gridding technology were used to improve the calculation efficiency and accuracy of the model;

[0005] The Chinese invention patent with publication number CN115709223A, “A method for obtaining the effectiveness of plate shape regulation based on digital twin of cold rolling process”, invented a method for obtaining the effectiveness of plate shape regulation based on digital twin of cold rolling process. The thermal convexity of the working roll was predicted by establishing a finite element model of the temperature field of the cold rolling working roll, and the thermal convexity of the working roll was coupled with the rolling finite element model to construct the digital twin of the cold rolling process. The strip outlet thickness and the relative length difference of the longitudinal fiber strips of the strip were simulated when different plate shape adjustment mechanisms participated in the regulation, and the regulation effectiveness coefficient curve of each plate shape control actuator was calculated and obtained.

[0006] The Chinese invention patent "A method for analyzing the influence of thermal convexity on plate shape during cold rolling" with publication number CN114798755A invented a numerical simulation method to establish an indirect coupling model of the thermal convexity of cold rolling working rolls to analyze and obtain the thermal convexity of the working rolls of each frame, and based on the thermal convexity combined with LS-DYNA to establish a numerical simulation model of the rolling process of each machine, and analyze the plate shape under different thermal convexities of working rolls; the Chinese journal paper "Research on the temperature field and thermal convexity of rolls in the continuous casting and rolling process of thin slabs" proposed a simplified method for analyzing the temperature and thermal convexity of rolls, established a two-dimensional roll temperature field and thermal convexity model, considered the transient thermal contact and complex boundary conditions of the rolling process, and used the finite element analysis software ANSYS to simulate the transient temperature field and thermal convexity of the rolls, and obtained the temperature changes at each point on the roll surface and the law of the thermal convexity of the rolls. The Chinese master's thesis "Research on Temperature Distribution in the Finishing Zone of Hot Rolling" uses ANSYS finite element to establish a three-dimensional indirect coupling finite element model of the working roll in the hot rolling process, and systematically analyzes the influence of roll parameters such as roll diameter, workpiece parameters such as width and temperature, and process parameters such as rolling time and rolling speed on the roll temperature distribution, and obtains the temperature distribution law of the working roll in radial, axial and circumferential directions due to each parameter.

[0007] There are two main deficiencies in the above research: (1) The working roll thermal convexity model does not adopt the three-dimensional thermal-mechanical direct coupling method. The existing technology uses a two-dimensional model that ignores the temperature transfer and thermal expansion in the circumferential direction of the roll. An indirect coupling model is used to first perform thermal analysis, and then the node temperature is added as a body load to the structural stress analysis. The model accuracy is low; (2) The working roll thermal roll shape is not coupled with the rolling finite element model of the entire hot rolling process. The rolling model of a single stand or several stands ignores the genetic effect of the upstream and downstream stands of the plate shape. The failure to combine the hot roll shape results in a difference in the roll gap shape from the actual rolling process, and cannot accurately predict the change in plate shape during hot rolling. Summary of the invention

[0008] The present application provides a method for predicting the shape of hot rolled strip steel taking into account the hot roll shape of the working roll, which is used to improve the simulation accuracy of the temperature field and thermal convexity of the hot rolling roll.

[0009] A method for predicting the shape of a hot-rolled strip considering the hot roll shape of a working roll, comprising:

[0010] Step 1: Collecting the field data of each stand, wherein the field data includes rolling process parameters, roll parameters, strip parameters and air temperature;

[0011] Step 2: According to the field data obtained in step 1, a three-dimensional finite element model of the thermal crown of the working rolls of each frame is established and the corresponding model parameters are set, and the three-dimensional finite element model of the thermal crown is solved to obtain the simulation temperature and thermal roll shape of the working rolls of each frame;

[0012] Step 3: Collect the measured temperature of the working rolls of each stand at the rolling site, compare it with the simulated temperature of the working rolls obtained by the three-dimensional finite element model of thermal crown, and verify the accuracy of the three-dimensional finite element model of thermal crown of the working rolls;

[0013] If the simulation temperature is inconsistent with the measured temperature, the model parameters of the three-dimensional finite element model of the working roll thermal crown are adjusted until the simulation temperature is consistent with the measured temperature;

[0014] If the simulated temperature is consistent with the measured temperature, the three-dimensional finite element model of the thermal crown of the working roll is solved to obtain the thermal roll shape of the working roll;

[0015] Step 4: establishing a rolling finite element model of the first stand according to the hot roll profile of the working roll and the field data collected in step 1, and solving to obtain strip steel result data;

[0016] Step 5: Based on the strip result data, a finite element model of inter-stand strip cooling corresponding to the next stand is established through data transfer between rolling finite element models of adjacent stands, so as to simulate the inter-stand strip cooling process;

[0017] Step 6: According to the inter-stand strip cooling finite element model obtained in step 5, the strip result data, the hot roll profile of the working roll and the field data obtained after solving are used to establish the rolling finite element model of the next stand, which is used to simulate the rolling process of the stand;

[0018] Step 7: Repeat steps 5 and 6 to sequentially establish the strip cooling finite element model between each stand and the rolling finite element model of each stand until the rolling finite element model of the last stand is established;

[0019] The rolling process of each stand and the cooling process of the strip between stands are established as sub-models respectively. The temperature, convexity and width of the strip are transmitted through data transmission between sub-models, so that each sub-model is connected into an integrated three-dimensional multi-stand simulation model of hot rolling.

[0020] Step 8: Establish a strip cooling finite element model based on the strip result data, strip parameters, and air temperature of the last stand in the hot rolling three-dimensional multi-stand simulation model, and cool the strip to room temperature;

[0021] Step 9: Collect the measured values ​​of the last stand at the rolling site and compare them with the data simulation values ​​obtained by the strip cooling finite element model to verify whether the results are consistent with the actual situation;

[0022] If not, return to adjust the model parameters until the data simulation value is consistent with the measured value; if it is consistent, proceed to the next step;

[0023] Step 10: According to the hot roll profile of the working rolls at different rolling times, a three-dimensional multi-stand simulation model of hot rolling is established and solved.

[0024] By adopting the above technical solution, the model is established completely according to the field data collected at the actual production site, so that the three-dimensional finite element model of the working roll thermal crown, the rolling finite element model and the strip cooling finite element model are closer to the actual production, so that the simulation results of the model are in line with the actual situation. This method adopts segmented modeling, decomposes the entire hot rolling process, establishes multiple sub-models by data transmission, and then connects the multiple sub-models into a whole by data transmission, effectively ensuring the data continuity between the sub-models, ensuring the model accuracy, and fast calculation speed.

[0025] Preferably, the step 2 is specifically:

[0026] Step 2.1: Divide the model into heat exchange areas according to the thermal boundary conditions of the working roll during the production process;

[0027] Step 2.2: Determine the equivalent convection heat transfer coefficient of each heat exchange area;

[0028] Step 2.3: Using the ANSYS / LSDYNA platform, a three-dimensional finite element model of the thermal crown of the work roll is established according to the thermal boundary conditions of the work roll and the equivalent convection heat transfer coefficient of each heat exchange area, and the model parameters are set;

[0029] Step 2.4: Solve the three-dimensional finite element model of the thermal crown of the working roll to obtain the working roll temperature field and the working roll thermal roll shape under the thermal stability state of the working roll.

[0030] By adopting the above technical scheme, a three-dimensional finite element model of the thermal crown of the working rolls of each frame is established and the corresponding model parameters are set. The thermal boundary conditions of the working rolls are divided. Considering the temperature change in the circumferential direction of the working rolls under the influence of on-site heat exchange, the heat exchange areas are divided. Different areas use different convection heat transfer coefficients, thereby establishing a more accurate three-dimensional finite element model of the thermal crown of the working rolls.

[0031] Preferably, the step 3 is specifically:

[0032] Step 3.1: Measure the temperature of the working roll after it leaves the machine by using an infrared thermal imager and a contact thermometer;

[0033] Step 3.2: Compare the temperatures recorded by the infrared thermal imager and the contact thermometer, and adjust the parameters of the infrared thermal imager so that the temperature measured by the infrared thermal imager is consistent with the temperature recorded by the contact thermometer;

[0034] Step 3.3: Compare the temperature measured by the infrared thermal imager with the simulated temperature, and adjust the model parameters to make the roller temperature distribution trend consistent with the measured temperature distribution trend;

[0035] Step 3.4: Based on the adjusted three-dimensional finite element model of the thermal crown of the working roll, the thermal roll shape of the working roll is obtained by solving.

[0036] By adopting the above technical solution, the simulation data calculated by modeling is compared with the measured data to verify their consistency, the accuracy of the model is verified, and the model parameters are adjusted to ensure that the hot roll shape of the working roll in the model is consistent with the actual one.

[0037] Preferably, the step 4 is specifically:

[0038] Step 4.1: Modeling in ANSYS / LS-DYNA module, using SOLID164 units for both strip and roll, full integration mode for work roll shell, backup roll shell and strip units, reduced integration for the rest, and viscous hourglass control;

[0039] Step 4.2: During the modeling process, select the B-spline curve to draw the hot roll curve of the working roll, and first establish the surface mesh of the strip and then stretch it into a volume mesh;

[0040] Step 4.3: Create the rolling finite element model after meshing, and create components to impose constraints and initial conditions;

[0041] Step 4.4: Set the parameters required for the rolling finite element model, and start the thermal-structural coupling analysis mode to obtain the strip result data.

[0042] By adopting the above technical solution and following the above steps to establish a rolling finite element model, firstly, the data of the first stand is used as parameters to establish a rolling finite element model of the first stand, and then the model is solved.

[0043] Preferably, the data transmission in step 5 includes the convexity and width of the strip, specifically:

[0044] Step 5.1: Use LS-PrePost to open the strip result data, and then extract the node coordinates of multiple sections located in the middle area of ​​the strip during the stable rolling stage;

[0045] Step 5.2: Calculate the average value of the node coordinates of multiple sections to generate the node coordinates of the initial section of the next model strip;

[0046] Step 5.3: Based on the initial section node coordinates, use ANSYS / LSDYNA to establish the cross section of the strip, divide the grid with mesh200 units, and then evenly expand the two-dimensional grid into a three-dimensional strip grid. While completing the transfer of the strip convexity and width in the upper and lower sub-models, a new strip grid is re-divided.

[0047] By adopting the above technical solution and using data transmission method, the convexity and width of the strip are transmitted through the node coordinates of the previous model to establish a new strip cooling finite element model.

[0048] Preferably, the data transmission in step 5 includes the temperature of the strip steel, specifically:

[0049] Step 5.4: Use LS-PrePost to open the strip result data of step 4 and extract the strip temperature of the last time step in the strip result data;

[0050] Step 5.5: Assign the strip temperature after rolling extracted in step 5.4 to the strip nodes of the new strip grid in step 5.3 according to the node order as the initial temperature of the strip to ensure the transfer of the strip temperature in the upper and lower sub-models.

[0051] By adopting the above technical solution and using data transfer method, the strip temperature of the previous model is assigned to the new strip nodes according to the node order, and the strip temperature is transferred to establish a new strip cooling finite element model.

[0052] Preferably, the process of verifying whether the result in step 9 is consistent with the actual situation is specifically as follows:

[0053] Step 9.1: Compare the simulated value and the measured value of the transverse thickness distribution data of the strip steel after cooling to room temperature after rolling;

[0054] Step 9.2: Compare the simulated value and the measured value of the outlet temperature of the last rack;

[0055] Step 9.3: Compare the simulated value and the measured value of the rolling force of each stand.

[0056] By adopting the above technical solution, the strip simulation data output by the last stand of the hot rolling three-dimensional multi-stand simulation model is verified to be consistent with the measurement data of the last stand obtained by actual measurement, thereby verifying the accuracy of the hot rolling three-dimensional multi-stand simulation model.

[0057] Preferably, the step 10 is specifically as follows:

[0058] Step 10.1: Simulate and obtain the hot roll profile of the working roll under the required rolling time;

[0059] Step 10.2: Establish a three-dimensional multi-stand simulation model of hot rolling according to the hot roll profile under this rolling time;

[0060] Step 10.3: Solve the hot rolling three-dimensional multi-stand simulation model to obtain the strip shape under each stand.

[0061] By adopting the above technical solution, the three-dimensional multi-stand simulation model of hot rolling that has been built and verified is used to predict the shape of hot-rolled strip. The hot roll shape of the working roll and the strip shape at the outlet of each stand under different rolling times can be predicted, so as to judge whether the strip production meets expectations.

[0062] An electronic device comprises a processor and a memory, wherein the memory is used to store instructions, and the processor is used to execute the instructions stored in the memory so that the electronic device executes any one of the methods described above.

[0063] A computer-readable storage medium stores instructions, and when the instructions are executed, any one of the above methods is executed.

[0064] In summary, one or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0065] 1. The three-dimensional finite element model of the working roll thermal crown, the rolling finite element model and the strip cooling finite element model are established completely according to the data collected from the actual production site, making the three-dimensional finite element model of the working roll thermal crown, the rolling finite element model and the strip cooling finite element model closer to reality.

[0066] 2. The three-dimensional finite element model of the thermal crown of the working roll established by this method not only takes into account the temperature change of the roll in the circumferential direction, but also takes into account the mutual influence of the temperature field and the force field during the rolling process, further improving the simulation accuracy of the temperature field and thermal crown of the hot rolling roll.

[0067] 3. The segmented modeling method adopted in this method decomposes the entire hot rolling process into multiple sub-models, and data transfer and mesh re-division can ensure that the strip convexity, width and temperature between sub-models are basically consistent, and all sub-models are coupled into a whole. This not only solves the problem of excessive unit elongation during the hot rolling process of strip steel, improves the accuracy of the model, but also greatly reduces the time cost of errors and modifications in the simulation process, and the calculation speed is faster and the requirements for the computing platform are lower.

[0068] 4. This method adopts a simulation experiment method based on rolling theory and three-dimensional thermal-mechanical coupling finite element simulation, which can reduce the equipment, time and cost losses caused by actual experiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 It is a flow chart of establishing a three-dimensional multi-stand simulation model of hot rolling by the method;

[0070] Figure 2 This is a cross-sectional schematic diagram of the boundary conditions of the three-dimensional finite element model of the working roll thermal crown of the method;

[0071] Figure 3 It is a schematic diagram of the axial boundary conditions of the three-dimensional finite element model of the thermal crown of the working roll of the method;

[0072] Figure 4 It is the mesh division of the three-dimensional finite element model of the working roll thermal crown of the method;

[0073] Figure 5 It is a thermal image of a working roll of a certain stand of this method;

[0074] Figure 6 It is a comparison chart between the measured value of the working roll temperature field of this method and the simulation result;

[0075] Figure 7 It is a schematic diagram of the hot rolling simulation idea of ​​this method;

[0076] Figure 8 It is the flow chart of the transfer of strip crown and width between sub-models of this method;

[0077] Fig. 9 It is the flow chart of the temperature transfer of strip steel nodes between sub-models of this method;

[0078] Fig.10 It is the result diagram of data transfer between sub-models of this method;

[0079] Fig.11 is a schematic diagram of the grid re-division technique of the present method;

[0080] Fig.12 This is a comparison chart between the measured data and the simulation data of the transverse distribution of the strip thickness after finishing rolling of the present method;

[0081] Fig.13 It is a comparison chart between the simulated strip temperature and the measured temperature of this method;

[0082] Fig.14 It is a comparison diagram between the simulated rolling force of each stand and the measured rolling force of the method;

[0083] Fig.15 is the hot roll profile curve of each working roll under different rolling times of the method;

[0084] Fig.16 is the lateral distribution of the relative thickness difference of the strip steel of each stand at different rolling times of the method;

[0085] Fig.17 The present method is to reduce the convexity and edge thinning of the strip in each stand under different working roll hot roll profile curves.

[0086] Explanation of the accompanying reference numerals: 1. steel strip; 2. water baffle; 3. nozzle; 4. working roll; 5. support roll. DETAILED DESCRIPTION

[0087] In order to enable technicians in this field to better understand the technical solutions in this specification, the technical solutions in the embodiments of this specification will be clearly and completely described below in conjunction with the drawings in the embodiments of this specification. Obviously, the described embodiments are only part of the embodiments of this application, not all of the embodiments.

[0088] In the description of the embodiments of the present application, words such as "for example" or "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "for example" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "for example" or "for example" is intended to present related concepts in a specific way.

[0089] In the description of the embodiments of the present application, the meaning of the term "multiple" refers to two or more. For example, multiple systems refer to two or more systems, and multiple screen terminals refer to two or more screen terminals. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. The terms "include", "comprise", "have" and their variations all mean "including but not limited to", unless otherwise specifically emphasized.

[0090] In this embodiment, a four-roller hot rolling mill of a certain factory is taken as an example, and the thermal crown numerical simulation model is combined with the rolling process numerical simulation model to simulate and analyze the entire hot rolling process. The rolling mill rolls are all flat rolls. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0091] Reference Figure 1 As shown in the figure, the establishment and verification process of the three-dimensional finite element model of the working roll thermal crown and the three-dimensional multi-stand simulation model of hot rolling.

[0092] A method for predicting the shape of a hot-rolled strip considering the hot roll shape of a working roll, comprising:

[0093] Step 1: Obtain the rolling process parameters, roll and strip size parameters, roll and strip material parameters, cooling water temperature, air temperature, and hot rolling line instrument distribution map at the rolling site. The specific contents are as follows:

[0094] Step 1.1: Collect rolling process parameters, including friction coefficient, working roll bending force, rolling speed, rolling force, strip finishing inlet temperature, and strip finishing outlet temperature. The rolling process parameters of the eight stands F1-F8 in this embodiment are shown in Table 1.

[0095] Table 1 Rolling process parameters

[0096]

[0097] Step 1.2: Collect roll parameters, including: work roll diameter, work roll body length, support roll diameter, support roll body length, roll density, roll yield modulus, roll tangent modulus, roll elastic modulus, roll Poisson's ratio, roll thermal expansion coefficient, roll thermal conductivity, and roll specific heat capacity. The work roll body length is 1060 mm, the support roll body length is 1040 mm, and the other roll size parameters are shown in Table 2a, and the material parameters are shown in Table 2b.

[0098] Table 2a Roller size parameters

[0099]

[0100] Table 2b Roller material parameters

[0101]

[0102] Step 1.3: Collect strip steel parameters, including strip steel thickness, strip steel width, strip steel temperature, and strip steel type. The strip steel parameters are shown in Table 3.

[0103] Table 3 Strip material parameters

[0104]

[0105] Step 2: According to the rolling process parameters, roll size parameters, roll material parameters, cooling water temperature, air temperature, and hot rolling line instrument distribution diagram of the rolling site described in step 1, a three-dimensional finite element model of the thermal crown of the working rolls of each stand is established to obtain the temperature field distribution of the working rolls;

[0106] Step 2.1: Make reasonable simplifications and assumptions on the model based on the actual boundary conditions of the working rolls in the production process, and divide the model into 10 areas in the circumferential direction and 3 areas in the axial direction according to the heat exchange form. The specific contents are as follows:

[0107] (1) The radial boundary conditions of the working roll are adjusted according to the heat exchange form, such as Figure 2 As shown; the working roll 4 is arranged horizontally and longitudinally, and the upper end of the working roll 4 rotates to contact the supporting roll 5 arranged coaxially; nozzles 3 are respectively arranged on both sides of the horizontal lateral direction of the working roll 4, and the nozzles 3 are used to spray cooling water to the working roll 4, and water baffles 2 are arranged on both sides of the working roll 4 below the nozzles 3 for receiving the cooling water sprayed from the nozzles; the lower end of the working roll abuts the strip steel 1.

[0108] The working roll 4 is divided into 10 different areas along the circumferential direction, specifically: A~B strip steel outlet radiation area; B~C outlet water accumulation area; C~D outlet water spray cooling area; D~E outlet natural convection area; E~F working roll and support roll contact area; F~G inlet natural convection area; G~H inlet water spray cooling area; H~I inlet water accumulation area; I~J strip steel inlet radiation area; J~A working roll and strip steel contact area.

[0109] (2) The axial boundary conditions of the working roll are divided into three different regions according to the heat exchange form, such as Figure 3 As shown. The middle area II is the contact area between the strip and the roll. The working roll contacts the high-temperature strip to obtain heat, and contacts the cooling water and air to remove some of the heat. In the I and III areas, the working roll only contacts the cooling water and air, not the strip, and only loses heat.

[0110] (3) The material and initial temperature field of the working roll are uniform, and there is no internal heat source.

[0111] (4) Ignore the heat radiation of the working roll, ignore the heat transfer between the roll neck and the air, and assume that the temperature changes of the upper and lower working rolls are consistent.

[0112] (5) The heat exchange in the model is all in the form of convection.

[0113] (6) Ignore the heat transfer between the working roll and the support roll, because the support roll takes away part of the heat from the working roll and transfers the friction heat to the working roll at the same time. These two parts of heat can be approximately considered to be offset.

[0114] Step 2.2: Determine the equivalent convection heat transfer coefficient of each heat exchange area;

[0115] (1) The contact area between the working roll and the strip (J~A). The contact heat transfer between the working roll and the strip is the main source of heat input to the working roll. Due to the small contact area and the presence of oxide scale, cooling water and other media in the contact area, it is also the most complicated heat exchange process of the working roll. For high-speed rolled thin strips, the calculation formula is:

[0116]

[0117] In the formula, h s , S, T s They are the heat transfer coefficient between the strip and the working roll, the thickness of the oxide scale between the roll gap, and the strip inlet temperature.

[0118] (2) Natural convection zone (A~B, D~E, F~G, I~J). During the rolling process, except for the contact area between the working roll and the strip, the temperature of other areas of the working roll is relatively low, and the influence of thermal radiation on the calculation results is relatively small, and the influence of thermal radiation on the temperature field can be ignored. The convection heat transfer coefficient between the working roll and the air is usually calculated using the following formula:

[0119]

[0120] In the formula, λ air is the thermal conductivity of air; Gr is the Grashof number; R ε is the Reynolds number; P r is the Prandtl number; R is the radius of the working roll. According to the Grashof criterion, the Reynolds number R can be ignored ε . Then the natural convection coefficient formula can be simplified to:

[0121]

[0122] In the formula, ΔT is the difference between the temperature of the working roll surface and the surrounding air temperature. According to experience, the convection heat transfer coefficient between the working roll and the air ranges from 12 to 59 W / (m 2 ·℃).

[0123] (3) Water accumulation area (B-C and H-I). In the production of hot-rolled strip steel, in order to prevent the roller cooling water from spraying directly onto the strip steel, a water baffle device is required to block the roller cooling water. The accumulated water on the water baffle also has a great cooling effect on the working roll. The heat exchange coefficient formula between the accumulated water at the water baffle and the working roll surface is:

[0124]

[0125] In the formula, R ε is the Reynolds number; P r is the Prandtl number; λ w is the thermal conductivity of water; l wd It is the contact arc length between the water accumulated on the water retaining plate and the working roller.

[0126] (4) Water spray cooling zone (C~D and G~H). Water spray cooling is the main way to remove the heat of the working roll. The heat exchange between cooling water and the working roll is forced convection cooling. The convection heat transfer coefficient h wp The value is related to cooling water pressure, temperature, distance between nozzle and working roll surface, spray angle and spray water density. Based on these factors, the formula for convection heat transfer coefficient is:

[0127] 1) When the working roll surface temperature T wr <100℃

[0128]

[0129] 2) When the working roll surface temperature T wr >200℃

[0130]

[0131] 3) When the working roll surface temperature is 100℃≤T wr ≤200℃

[0132]

[0133] Where Q is the water flow density, Q=V sp / A sp ; V sp is the cooling water flow rate; A sp is the injection area; P sp is the injection pressure; T water is the cooling water temperature; when Q<10000L / (s·m -2 ), B=(T water / 16) -0.17 ; When Q≥10000L / (s·m -2 ), B=1.

[0134] Step 2.3: Use ANSYS / LSDYNA platform to build a three-dimensional finite element model of the thermal crown of the work roll and set the model parameters;

[0135] Step 2.3.1: Establish a working roll geometric model according to the working roll size parameters in Table 2, and determine the material properties of the thermal crown numerical simulation model according to the working roll material parameters in Table 3a;

[0136] Step 2.3.2: Mesh the working roll geometry model, such as Figure 4 As shown. Set some solution conditions and establish a three-dimensional finite element model of the thermal crown of the working roll;

[0137] Step 2.3.3: Determine the thermal boundary conditions of the working roll according to step 2.1, and then calculate the convective heat transfer coefficient of each heat exchange area according to step 2.2, set the convective heat transfer coefficient of different areas of the working roll with the external environment during the rolling process, and start the thermal structure coupling analysis mode.

[0138] Step 2.4: Solve the model to obtain the working roll temperature field and hot roll shape under the thermal stability state of the working roll.

[0139] Step 3: The temperature of the working roll after it leaves the machine is measured by an infrared thermal imager and a contact thermometer, and compared with the temperature of the working roll obtained by simulation to verify whether the model is consistent with reality.

[0140] If not, adjust the process parameters of the simulation model to make the simulation temperature consistent with the measured temperature, and then solve the work roll thermal profile based on the adjusted three-dimensional finite element model of the work roll thermal crown. The specific steps are as follows:

[0141] Step 3.1: Stick tape on the working roll axially, place the infrared thermal imager two meters away from the center of the working roll, wait for two or three minutes to make the tape temperature the same as the roll temperature, and record the roll temperature with the infrared thermal imager. Immediately measure the roll temperature with a contact thermometer, and record the roll temperature every 50mm;

[0142] Step 3.2: Compare the temperatures recorded by the infrared thermal imager and the contact thermometer, and adjust the emissivity, atmospheric temperature, relative humidity, external optical temperature, external optical transmittance, etc. of the infrared thermal imager so that the temperature measured by the infrared thermal imager is basically consistent with the temperature recorded by the contact thermometer;

[0143] Step 3.3: Compare the temperature measured by the infrared thermal imager with the simulated temperature, and adjust the model parameters so that the temperature distribution trend of the roller is basically consistent with the measured temperature distribution trend;

[0144] Step 3.4: Based on the adjusted three-dimensional finite element model of the working roll thermal crown, the hot roll profile of the working roll at different rolling times of all stands is solved.

[0145] Figure 5 The temperature distribution of the working roll was taken using a thermal imager. Figure 6 : This is a comparison diagram of the measured values ​​of the working roll temperature field and the simulation results (F1-F8 represent the 8 stands on site in this embodiment respectively). The temperature distribution trends are in good agreement, and the accuracy of the three-dimensional finite element model of the working roll thermal crown is high.

[0146] Step 4: The overall modeling idea of ​​hot rolling model is as follows Figure 7 As shown, according to the hot roll profile of the working roll obtained in step 3, the rolling process parameters on site, the roll size parameters, the strip size parameters, the roll and strip material parameters, and the air temperature, the rolling finite element model of the first stand is established and the strip result data is obtained by solving. The specific steps are as follows:

[0147] Step 4.1: Modeling in ANSYS / LS-DYNA module, the strip and roll are both made of eight-node hexahedral SOLID164 elements, the work roll shell, backup roll shell and strip elements are made in full integration mode, and the rest are made in reduced integration mode, and viscous hourglass control is adopted;

[0148] Step 4.2: During the modeling process, a high-order B-spline curve is selected to draw the hot roll curve of the working roll, and the strip is firstly established into a surface mesh and then stretched into a volume mesh;

[0149] Step 4.3: After meshing, create PART, define the surface-to-surface contact mode between the strip and the work roll shell, the work roll shell and the backup roll shell, and create components to impose constraints and initial conditions;

[0150] Step 4.4: Define the thermal analysis related cards in LS-PrePost, set the parameters required for the model, and turn on the thermal-structural coupling analysis mode to obtain the strip result data.

[0151] Step 5: According to the strip steel result data after the model solution in step 4, the material parameters of the strip steel, and the air temperature, a finite element model for inter-rack strip steel cooling is established to simulate the inter-rack strip steel cooling process. The specific steps are as follows:

[0152] See also Figure 8 The crown and width transfer flow chart of the strip shown;

[0153] Step 5.1: Use LS-PrePost to open the strip result data, and then extract the node coordinates of multiple sections located in the middle area of ​​the strip during the stable rolling stage;

[0154] Step 5.2: Calculate the average value of multiple cross-section node coordinates to generate the initial cross-section node coordinates of the next model strip;

[0155] Step 5.3: Use ANSYS / LSDYNA to create the cross section of the strip, divide the mesh using mesh200 units, and then evenly expand the two-dimensional mesh into a three-dimensional strip mesh. Complete the transfer of the strip convexity and width in the upper and lower sub-models and re-divide the strip mesh;

[0156] Fig. 9 The figure shows the temperature transfer flow chart of the strip steel node;

[0157] Step 5.4: Use LS-PrePost to open the strip result data of step 4 and extract the strip temperature of the last time step;

[0158] Step 5.5: Assign the strip temperature after rolling extracted in step 5.4 to the strip nodes of the model in step 3 according to the node order as the initial temperature of the strip, thus ensuring the transfer of the strip temperature in the upper and lower sub-models.

[0159] The results of strip data transfer are as follows: Fig.10 The grid re-division results are shown in Fig.11 shown.

[0160] Step 6: According to the strip result data after solving the strip cooling finite element model in step 5, the hot roll shape of the working roll obtained in step 3, the on-site rolling process parameters, roll size parameters, material parameters of the rolls and strip, and air temperature, a rolling finite element model of the second stand is established to simulate the rolling process of the second stand.

[0161] Step 7: Repeat steps 5 and 6 until the rolling finite element model of the final stand is established.

[0162] The rolling process of each stand and the cooling process of the strip between stands are established as sub-models respectively, and the temperature, convexity and width of the strip are transmitted through data transmission between sub-models, so that each sub-model is connected into an integral hot rolling three-dimensional multi-stand simulation model; the data transmission process in step 7 is the same as the data transmission process in step 5.

[0163] Step 8: Establish a strip cooling finite element model based on the strip result data after rolling at the final stand, the material parameters of the strip, and the air temperature, and cool the strip to room temperature;

[0164] Step 9: Compare the simulated value of the transverse thickness distribution data of the strip cooled to room temperature after rolling with the measured value, compare the simulated value of the outlet temperature of the last stand with the measured value, and compare the simulated value of the rolling force of each stand with the measured value. The specific steps are as follows:

[0165] Step 9.1: Compare the simulated value and the measured value of the transverse thickness distribution data of the strip steel after cooling to room temperature after rolling, such as Fig.12 As shown; the specific steps are: divide the strip cooled to room temperature into an edge thinning zone (100mm away from the edge on both sides of the strip) and a center zone, take points at unit intervals of 25mm, measure the thickness value of each point, and you can get the transverse thickness distribution of the strip.

[0166] Step 9.2: Compare the simulated value and the measured value of the strip outlet temperature of the last stand, such as Fig.13 shown.

[0167] Step 9.3: Compare the simulated and measured values ​​of the rolling force of each stand, such as Fig.14 shown.

[0168] Step 10: According to the hot roll profile of the working rolls at different rolling times, a three-dimensional multi-stand simulation model of hot rolling is established and solved to obtain the strip shape under each stand at this time. The specific steps are as follows:

[0169] Step 10.1: Simulate and obtain the hot roll profile of the working roll under different rolling times, such as Fig.15 The figure shows the hot roll profile of the working roll corresponding to four different rolling times: 0s, 2700s, 5400s, and 8100s;

[0170] Step 10.2: Establish a three-dimensional multi-stand simulation model of hot rolling according to the hot roll profile at the corresponding rolling time;

[0171] Step 10.3: Solve the three-dimensional multi-stand simulation model of hot rolling to obtain the strip shape under each stand, such as Fig.16 The figure shows the lateral distribution of the relative thickness difference of the strip steel of each stand at four times: 0s, 2700s, 5400s, and 8100s;

[0172] Fig.17 Shown are the convexity and edge thinning of the strip in each stand under three different working roll hot roll profiles.

[0173] C 40 : The average value of the difference between the thickness in the middle of the strip and the thickness 40 mm away from the edge of the strip.

[0174] C 150 : The average value of the difference between the thickness in the middle of the strip and the thickness 150 mm away from the edge of the strip.

[0175] E 40 : The average value of the difference between the thickness at 40mm away from the edge of the strip and the thickness at the edge of the strip.

[0176] The present application also provides an electronic device, which may include: at least one processor and at least one memory.

[0177] The processor may include one or more processing cores. The processor uses various interfaces and lines to connect various parts of the entire server, and executes various functions of the server and processes data by running or executing instructions, programs, code sets or instruction sets stored in the memory, and calling data stored in the memory.

[0178] Optionally, the processor can be implemented in at least one hardware form of digital signal processing (DSP), field-programmable gate array (FPGA), and programmable logic array (PLA). The processor can integrate one or a combination of a central processing unit (CPU), a graphics processing unit (GPU), and a modem. Among them, the CPU mainly processes the operating system, user interface, and application programs; the GPU is responsible for rendering and drawing the content to be displayed on the display; and the modem is used to process wireless communications. It is understandable that the above-mentioned modem may not be integrated into the processor, but may be implemented separately through a chip.

[0179] The memory may include a random access memory (RAM) or a read-only memory (ROM). Optionally, the memory includes a non-transitory computer-readable storage medium. The memory may be used to store instructions, programs, codes, code sets or instruction sets. The memory may include a program storage area and a data storage area, wherein the program storage area may store instructions for implementing an operating system, instructions for at least one function (such as a touch function, a sound playback function, an image playback function, etc.), instructions for implementing the above-mentioned various method embodiments, etc.; the data storage area may store data involved in the above-mentioned various method embodiments, etc. The memory may also be at least one storage device located away from the aforementioned processor. The memory as a computer storage medium may include an operating system, a network communication module, a user interface module, and an application for a method for predicting the shape of hot-rolled strip steel considering the hot roll type of the working roll.

[0180] The present application also provides a computer-readable storage medium, which stores instructions. When executed by one or more processors, the electronic device executes one or more of the methods described in the above embodiments.

[0181] In addition, each functional unit in the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0182] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a memory and includes several instructions for a computer device (which can be a personal computer, server or network device, etc.) to execute all or part of the steps of the various embodiments of the present application. The aforementioned memory includes: various media that can store program codes, such as USB flash drives, mobile hard drives, magnetic disks or optical disks.

[0183] The above is only an exemplary embodiment of the present disclosure, and the scope of the present disclosure cannot be limited thereto. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the disclosure of the specification and the truth of practice, it will be easy for those skilled in the art to think of other embodiments of the present disclosure. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the technical field that are not recorded in the present disclosure. The description and examples are regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

Claims

1. A method for predicting the shape of hot-rolled strip steel considering the hot roll shape of the working roll, characterized in that: include: Step 1: Collecting the field data of each stand, wherein the field data includes rolling process parameters, roll parameters, strip parameters and air temperature; Step 2: According to the field data obtained in step 1, a three-dimensional finite element model of the thermal crown of the working rolls of each frame is established and the corresponding model parameters are set, and the three-dimensional finite element model of the thermal crown is solved to obtain the simulation temperature and thermal roll shape of the working rolls of each frame; Step 3: Collect the measured temperature of the working rolls of each stand at the rolling site, compare it with the simulated temperature of the working rolls obtained by the three-dimensional finite element model of thermal crown, and verify the accuracy of the three-dimensional finite element model of thermal crown of the working rolls; If the simulation temperature is inconsistent with the measured temperature, the model parameters of the three-dimensional finite element model of the working roll thermal crown are adjusted until the simulation temperature is consistent with the measured temperature; If the simulated temperature is consistent with the measured temperature, the three-dimensional finite element model of the thermal crown of the working roll is solved to obtain the thermal roll shape of the working roll; Step 4: establishing a rolling finite element model of the first stand according to the hot roll profile of the working roll and the field data collected in step 1, and solving to obtain strip steel result data; Step 5: Based on the strip result data, a finite element model of inter-stand strip cooling corresponding to the next stand is established through data transfer between rolling finite element models of adjacent stands, so as to simulate the inter-stand strip cooling process; Step 6: According to the inter-stand strip cooling finite element model obtained in step 5, the strip result data, the hot roll profile of the working roll and the field data obtained after solving are used to establish the rolling finite element model of the next stand, which is used to simulate the rolling process of the stand; Step 7: Repeat steps 5 and 6 to sequentially establish the strip cooling finite element model between each stand and the rolling finite element model of each stand until the rolling finite element model of the last stand is established; The rolling process of each stand and the cooling process of the strip between stands are established as sub-models respectively, and the temperature, convexity and width of the strip are transmitted through data transmission between sub-models, so that each sub-model is connected into an integral three-dimensional multi-stand simulation model of hot rolling; Step 8: Establish a strip cooling finite element model based on the strip result data, strip parameters, and air temperature of the last stand in the hot rolling three-dimensional multi-stand simulation model, and cool the strip to room temperature; Step 9: Collect the measured values ​​of the last stand at the rolling site and compare them with the data simulation values ​​obtained by the strip cooling finite element model to verify whether the results are consistent with the actual situation; If not, return to adjust the model parameters until the data simulation value is consistent with the measured value; If it meets the requirements, proceed to the next step; Step 10: According to the hot roll profile of the working rolls at different rolling times, a three-dimensional multi-stand simulation model of hot rolling is established and solved.

2. The method for predicting the shape of hot-rolled strip considering the hot roll shape of the work roll according to claim 1, characterized in that: The step 2 is specifically as follows: Step 2.1: Divide the model into heat exchange areas according to the thermal boundary conditions of the working roll during the production process; Step 2.2: Determine the equivalent convection heat transfer coefficient of each heat exchange area; Step 2.3: Using the ANSYS / LSDYNA platform, a three-dimensional finite element model of the thermal crown of the work roll is established according to the thermal boundary conditions of the work roll and the equivalent convection heat transfer coefficient of each heat exchange area, and the model parameters are set; Step 2.4: Solve the three-dimensional finite element model of the thermal crown of the working roll to obtain the working roll temperature field and the working roll thermal roll shape under the thermal stability state of the working roll.

3. The method for predicting the shape of hot-rolled strip considering the hot roll shape of the work roll according to claim 1, characterized in that: The step 3 is specifically as follows: Step 3.1: Measure the temperature of the working roll after it leaves the machine by using an infrared thermal imager and a contact thermometer; Step 3.2: Compare the temperatures recorded by the infrared thermal imager and the contact thermometer, and adjust the parameters of the infrared thermal imager so that the temperature measured by the infrared thermal imager is consistent with the temperature recorded by the contact thermometer; Step 3.3: Compare the temperature measured by the infrared thermal imager with the simulated temperature, and adjust the model parameters to make the roller temperature distribution trend consistent with the measured temperature distribution trend; Step 3.4: Based on the adjusted three-dimensional finite element model of the thermal crown of the working roll, the thermal roll shape of the working roll is obtained by solving.

4. The method for predicting the shape of hot-rolled strip considering the hot roll shape of the work roll according to claim 1, characterized in that: The step 4 is specifically as follows: Step 4.1: Modeling in ANSYS / LS-DYNA module, using SOLID164 units for both strip and roll, full integration mode for work roll shell, backup roll shell and strip units, reduced integration for the rest, and viscous hourglass control; Step 4.2: During the modeling process, select the B-spline curve to draw the hot roll curve of the working roll, and first establish the surface mesh of the strip and then stretch it into a volume mesh; Step 4.3: Create the rolling finite element model after meshing, and create components to impose constraints and initial conditions; Step 4.4: Set the parameters required for the rolling finite element model, and start the thermal-structural coupling analysis mode to obtain the strip result data.

5. The method for predicting the shape of hot-rolled strip steel considering the hot roll shape of the work roll according to claim 4, characterized in that: The data transmission in step 5 includes the convexity and width of the strip, specifically: Step 5.1: Use LS-PrePost to open the strip result data, and then extract the node coordinates of multiple sections located in the middle area of ​​the strip during the stable rolling stage; Step 5.2: Calculate the average value of the node coordinates of multiple sections to generate the node coordinates of the initial section of the next model strip; Step 5.3: Based on the initial section node coordinates, use ANSYS / LSDYNA to establish the cross section of the strip, divide the grid with mesh200 units, and then evenly expand the two-dimensional grid into a three-dimensional strip grid. While completing the transfer of the strip convexity and width in the upper and lower sub-models, a new strip grid is re-divided.

6. The method for predicting the shape of hot-rolled strip considering the hot roll shape of the work roll according to claim 5, characterized in that: The data transmission in step 5 includes the temperature of the strip, specifically: Step 5.4: Use LS-PrePost to open the strip result data of step 4 and extract the strip temperature of the last time step in the strip result data; Step 5.5: Assign the strip temperature after rolling extracted in step 5.4 to the strip nodes of the new strip grid in step 5.3 according to the node order as the initial temperature of the strip to ensure the transfer of the strip temperature in the upper and lower sub-models.

7. The method for predicting the shape of hot-rolled strip considering the hot roll shape of the work roll according to claim 1, characterized in that: The specific process of verifying whether the result in step 9 is consistent with the actual situation is as follows: Step 9.1: Compare the simulated value and the measured value of the transverse thickness distribution data of the strip steel after cooling to room temperature after rolling; Step 9.2: Compare the simulated value and the measured value of the outlet temperature of the last rack; Step 9.3: Compare the simulated value and the measured value of the rolling force of each stand.

8. The method for predicting the shape of hot-rolled strip considering the hot roll shape of the work roll according to claim 1, characterized in that: The step 10 is specifically as follows: Step 10.1: Simulate and obtain the hot roll profile of the working roll under the required rolling time; Step 10.2: Establish a three-dimensional multi-stand simulation model of hot rolling according to the hot roll profile under this rolling time; Step 10.3: Solve the hot rolling three-dimensional multi-stand simulation model to obtain the strip shape under each stand.

9. An electronic device, characterized in that: The electronic device comprises a processor and a memory, wherein the memory is used to store instructions, and the processor is used to execute the instructions stored in the memory, so that the electronic device executes the method according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores instructions, and when the instructions are executed, the method according to any one of claims 1 to 8 is performed.

Images