Method for calculating rolling force of short-stress rolling mill based on thermosetting coupling simulation

Abstract

The invention discloses a short-stress rolling mill rolling force calculation method based on thermosetting coupling simulation. The method comprises the following steps that 1, an existing short-stress rolling mill model is simplified and then imported into engineering simulation software; 2, dynamic analysis of the rolling process is conducted through explicit dynamics of engineering simulation software; 3, the Sims hot rolling formula is adjusted by combining the contact area of the roller and the rolled piece in the simulation result, and the rolling force load is obtained through calculation; and 4, comparing the rolling force average value obtained by simulation with the rolling force obtained by theoretical calculation, and verifying the accuracy of a simulation result. According to the invention, the Johnson-Cook constitutive model is utilized to simulate the stress and strain of the rolled piece, so that the simulation result is more in line with the actual situation.

Description

Technical Field

[0001] The invention relates to the technical field of rolling mill equipment, and in particular to a method for calculating rolling force of a short stress rolling mill based on thermal-solid coupling simulation. Background Art

[0002] With the rapid development of my country's economy, the demand for steel in various industries is increasing. For example, the military industry, aerospace, shipbuilding, etc., or the construction industry, machinery manufacturing industry, automobile industry and other industries are inseparable from steel. At present, the domestic output of steel plates and strips exceeds demand, while large-scale bars are in short supply. Some high-quality special steels still need to be imported from abroad. Short stress rolling mills can effectively solve the problem of unreasonable production structure in this market. The working environment of the rolling mill is harsh and has the characteristics of high temperature, high pressure, and continuous operation. Therefore, it is extremely important to study the rolling force load of the short stress rolling mill and reveal its load transfer law, which is of great significance to improving the precision of the rolled piece and the overall quality of the rolled piece.

[0003] The basic information of the relevant patents is as follows: ① Application number CN202311074118.4 ② Patent name: A method for predicting hot rolling damage of high Mg aluminum alloy ③ Abstract: The present invention discloses a method for predicting hot rolling damage of high Mg aluminum alloy, comprising the following steps: S1. Based on thermophysical tests and thermal simulation tests, the thermophysical properties and mechanical properties of high Mg aluminum alloy are obtained; S2. A high temperature damage model and a welding model are constructed; S3. A hot rolling simulation model and simulation calculation of hot rolling coupled damage and welding are established; S4. Hot rolling process tests and damage organization analysis are performed. The present invention creatively proposes a new damage mathematical model and a damage-welding composite simulation model that couples temperature, strain rate, stress, and strain, which can effectively predict the hot rolling damage and welding distribution of high Mg aluminum alloy, and plays an important supporting role in guiding the formulation and optimization of hot rolling process parameters of high Mg aluminum alloy.

[0004] The basic information of the relevant patents is as follows: ① Application number CN201510194490.8 ② Patent name: Design method for power load distribution of low-temperature controlled rolling motor for rod and wire hole ③ Abstract: A design method for power load distribution of low-temperature controlled rolling motor for rod and wire hole, belonging to the field of steel rolling engineering design and production technology. The method flow is as follows: design the product outline of the new production line → use the steel deformation resistance measured by Gleeble thermal simulation as the input parameter → use DEFORM finite element software to simulate the rolling deformation of each pass under the actual hole of the rod and wire → simulate and calculate the rolling force of each pass of biting, rolling and throwing → calculate the rolling torque → calculate the power of the rolling mill. The advantage is that the calculation of rolling force fully considers the actual distribution difference of deformation temperature at different positions in each pass hole, the actual distribution difference of strain at different positions in the hole, and the actual distribution difference of strain rate at different positions in the hole for the first time. It is currently the most accurate method for calculating the power of low-temperature controlled rolling motors for rod and wire hole types, thus providing an important and reliable basis for the design of rated power distribution of new production line rolling mills and the formulation of low-temperature rolling process parameters.

[0005] It can be seen that the existing technology uses theoretical derivation, numerical simulation and experimental observation to study the rolling force load variation law under hot-rolled plates or cold-rolled conditions, and proposes rolling force calculation models suitable for their respective rolling conditions. However, there is less research on hot-rolled bars in short-stress rolling mills, and the research on rolling force is more focused on calculating the rolling force through the change in steel thickness before and after rolling. Summary of the invention

[0006] The object of the present invention is to provide a method for calculating the rolling force of a short stress rolling mill based on thermal-solid coupling simulation.

[0007] The technical solution adopted by the present invention is:

[0008] A method for calculating rolling force of a short stress rolling mill based on thermal-solid coupling simulation comprises the following steps:

[0009] Step 1, simplifying the existing short stress rolling mill model and importing it into engineering simulation software to obtain an engineering model;

[0010] Step 2: Use explicit dynamics of engineering simulation software to perform dynamic analysis of the rolling process; simulate the stress and strain of the rolled piece through the Johnson-Cook constitutive model to calculate a new plastic deformation curve;

[0011] Step 3, adjusting the Sims hot rolling formula based on the contact area between the rolling roller and the rolled piece in the simulation results, and calculating the rolling force load;

[0012] Step 4: Compare the average rolling force obtained by simulation with the rolling force obtained by theoretical calculation to verify the accuracy of the simulation results.

[0013] Furthermore, step 1 specifically includes the following steps:

[0014] Step 1-1, simplifying the two-dimensional CAD drawing of the short stress rolling mill roll system through the model and then performing geometric modeling in a three-dimensional modeling software (Solidworks);

[0015] Step 1-2, importing the obtained geometric modeling into the engineering simulation software for assembly to obtain the engineering model;

[0016] Steps 1-3, based on the Johnson-Cook constitutive model, set the parameters of the corresponding engineering model in the engineering simulation software.

[0017] Furthermore, in step 1-2, the parts of the roller that are not involved in the rolling contact in the original geometric modeling are deleted and replaced by two rigid plates that are bound and connected to the shaft body. The parts that are not involved in the rolling contact include the shaft neck and the shaft head.

[0018] Furthermore, the engineering simulation software adopts Abaqus software; the three-dimensional modeling software adopts Solidworks software.

[0019] Furthermore, in step 2, the calculation formula for calculating the stress and strain of the material affected by temperature using the Johson-Cook constitutive model is:

[0020]

[0021] Wherein, σ is the equivalent flow stress, A is the yield stress at the reference strain rate and reference temperature, B is the material strain hardening modulus, C is the strain rate strengthening parameter, ε is the plastic strain, m is the thermal softening index, is the effective strain rate, n is the material hardening exponent, T * is the relative temperature.

[0022] Furthermore, step 2 specifically includes the following steps:

[0023] Step 2-1, setting the boundary conditions and loads of the rolling process according to the actual production situation of the factory;

[0024] Specifically, the rolling speed is set to 13m / s, the rolling temperature is set to 1050℃, and the reduction is set to 35mm; the rollers are constrained and fixed to rotate only around the Z axis; friction contact is added between the rollers and the workpiece and the friction coefficient is set to 0.3, and heat exchange is established between the rollers and the workpiece, and between the workpiece and the air.

[0025] Step 2-2, the entire engineering model is meshed using hexahedral units, the surface of the roller is meshed finely, and the temperature-displacement coupling is selected as the mesh type.

[0026] Furthermore, the rolling force formula in step 3 is as follows:

[0027] F=S C Q p K m (1)

[0028]

[0029]

[0030]

[0031]

[0032] q1=0.8062-0.302·δ (6)

[0033] q2=0.0419+0.4055·δ-0.2246·δ 2 (7)

[0034]

[0035] In the formula, S c is the average contact area between the roll and the workpiece during rolling; Q p is the external friction stress state coefficient; K m is the deformation resistance; R′ is the roller flattening radius; C and D are rolling parameters; is the Poisson's ratio of the roll; E is the Young's modulus of the roll; Δh is the reduction; δ is the reduction rate; q1 and q2 are parameters related to the reduction rate; T is the dimensionless deformation temperature parameter; ε is the true strain; is the strain rate, h0 is the thickness at the entrance of the rolled piece, h1 is the thickness at the exit of the rolled piece, and R is the roller radius.

[0036] Furthermore, step 4 compares the difference value after comparison with a preset allowable error. If the difference value is less than the allowable error, it is determined that the simulation structure of the current simulation calculation is accurate; otherwise, step 2 is executed.

[0037] The present invention adopts the above technical solution. The present invention adopts the above technical solution, and only the contact part model of the roller and the rolled piece is required, and there is no need to simulate and analyze the roller as a whole. The present invention uses the Johnson-Cook constitutive model to simulate the stress and strain of the rolled piece, so that the simulation result is more in line with the actual situation. The contact area between the roller and the rolled piece calculated by simulation is used to replace the parameters of the rolled piece width and the contact arc length in the original formula, so that the formula is also applicable to the rolling force calculation of hot-rolled bars, and the calculation amount of determining parameters is also reduced. The result of the simulation calculation is a dynamic load history. Through the results of the visualization processing of the simulation software, the stress and deformation of the rolled piece during the rolling process are more intuitively displayed to the designers. It can play a good guiding role in the design stage for other types of rolling mills, shorten the research and development cycle, save costs, avoid waste of manpower and material resources, and improve the market competitiveness of enterprises. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments;

[0039] Figure 1 It is a schematic flow chart of a method for calculating rolling force of a short stress rolling mill based on thermal-solid coupling simulation of the present invention;

[0040] Figure 2 It is a schematic diagram of the structure of the short stress rolling mill of the present invention;

[0041] Figure 3 It is a simplified structural diagram of the rolling mill roll system;

[0042] Figure 4 Schematic diagram of rolling load setting;

[0043] Figure 5 Set up schematics for boundary conditions;

[0044] Figure 6 Schematic diagram of roller surface mesh refinement;

[0045] Figure 7 It is the schematic diagram of the overall grid division of the rolling mill roll system;

[0046] Figure 8 It is the cloud diagram of node temperature change;

[0047] Fig. 9 It is the rolling force history diagram;

[0048] Fig.10 Schematic diagram of the contact area between the workpiece and the roller. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application.

[0050] The present invention is mainly for the calculation of the rolling force of a short stress rolling mill. The main purpose of the present invention is to fill the gap in the market for the calculation of the rolling force of a short stress rolling mill for hot rolled bars. Second, in the current calculation of rolling force, due to the complex structure of the model and the numerous material property parameters involved, there are certain difficulties in dynamic modeling and solving. The Johnson-Cook constitutive model is introduced in the present invention to simulate the plastic deformation of the material during hot rolling. Third, referring to the Sims hot rolling formula, combined with the contact area between the workpiece and the roller during hot rolling calculated by the simulation software, the rolling force is calculated after a certain correction to the formula.

[0051] like Figures 1 to 10 As shown in one, the present invention discloses a method for calculating the rolling force of a short stress rolling mill based on thermo-solid coupling simulation, which comprises the following steps:

[0052] Step 1, simplifying the existing short stress rolling mill model and importing it into engineering simulation software to obtain an engineering model;

[0053] Furthermore, step 1 specifically includes the following steps:

[0054] Step 1-1, simplifying the two-dimensional CAD drawing of the short stress rolling mill roll system through the model and then performing geometric modeling in a three-dimensional modeling software (Solidworks);

[0055] Step 1-2, importing the obtained geometric modeling into the engineering simulation software for assembly to obtain the engineering model;

[0056] Steps 1-3, based on the Johnson-Cook constitutive model, set the parameters of the corresponding engineering model in the engineering simulation software.

[0057] Furthermore, the engineering simulation software adopts Abaqus software.

[0058] Step 2, using explicit dynamics of engineering simulation software (Abaqus / explicit) to perform dynamic analysis of the rolling process; using the Johnson-Cook constitutive model to simulate the stress and strain of the rolled piece to calculate a new plastic deformation curve;

[0059] Furthermore, step 2 specifically includes the following steps:

[0060] Step 2-1, setting the boundary conditions and loads of the rolling process according to the actual production situation of the factory;

[0061] Step 2-2, the entire engineering model is meshed using hexahedral units, the surface of the roller is meshed finely, and the temperature-displacement coupling is selected as the mesh type.

[0062] Step 3, adjusting the Sims hot rolling formula based on the contact area between the rolling roller and the rolled piece in the simulation results, and calculating the rolling force load;

[0063] Step 4: Compare the average rolling force obtained by simulation with the rolling force obtained by theoretical calculation to verify the accuracy of the simulation results.

[0064] The specific principle of the present invention is described in detail below:

[0065] like Figure 2 As shown, the short stress rolling mill is a large-scale equipment specially used for metal rolling, which is composed of a rolling mill support 1, a rolling mill roll system 2, and a rolling mill roll gap adjustment device 3. Due to its high rigidity, high precision, and ability to quickly adjust the roll gap, it is now widely used in the construction industry, automobile manufacturing, machinery manufacturing and other industries. Rolling force is the most important mechanical performance parameter in the production process of hot-rolled steel. Accurately obtaining the rolling force of the rolling mill is of great significance to improving the dimensional accuracy of the rolled piece, shape and position errors, optimizing load distribution, and ensuring equipment safety. The present invention is based on display dynamics and combines Abaqus numerical simulation software to calculate the rolling process of the short stress rolling mill.

[0066] The present invention provides a method for calculating the rolling force of a short stress rolling mill based on thermo-solid coupling simulation, and the specific operation steps are as follows:

[0067] Step 1, such as Figure 3 As shown, based on the two-dimensional CAD drawing of the short stress rolling mill roll system, the model is simplified and then geometrically modeled in the three-dimensional modeling software Solidworks. The geometric model is then imported into Abaqus for assembly. The parts that do not participate in the rolling contact, such as the journal and shaft head of the roll in the original model, are deleted and replaced by two rigid plates that are bound and connected to the shaft body.

[0068] Considering the effect of temperature on the plasticity of rolled pieces during hot rolling in a short stress rolling mill, the Johnson-Cook constitutive model is introduced. The parameters are shown in Table 1 to calculate the new plastic deformation curve, and the parameters are input into the Abaqus software.

[0069] Table 1Q235 Johnson-Cook constitutive model

[0070]

[0071] In step 2, set the analysis step type to display dynamics, temperature displacement coupling unit, and time length to 0.35.

[0072] Furthermore, in step 2, the calculation formula for calculating the stress and strain of the material affected by temperature using the Johson-Cook constitutive model is:

[0073]

[0074] Wherein, σ is the equivalent flow stress, A is the yield stress at the reference strain rate and reference temperature, B is the material strain hardening modulus, C is the strain rate strengthening parameter, ε is the plastic strain, m is the thermal softening index, is the effective strain rate, n is the material hardening exponent, T * is the relative temperature.

[0075] like Figure 4 and 5 As shown in the figure, the boundary conditions and load settings are based on the actual production situation of the factory. The rolling speed is set to 13m / s, the rolling temperature is set to 1050℃, and the reduction is set to 35mm. The roller needs to be constrained and fixed to rotate only around the Z axis. Friction contact needs to be added between the roller and the workpiece, and the friction coefficient is set to 0.3. At the same time, heat exchange between the roller and the workpiece, and between the workpiece and the air is established.

[0076] like Figure 6 and 7 As shown in the figure, meshing is performed. Hot rolling simulation involves plastic deformation of materials at high temperatures, as well as heat conduction between the rolled piece and the roll, and between the rolled piece and the air. There are many parameters and the calculation is complex. Therefore, hexahedral units are used for meshing the entire model, and the surface of the roll is meshed. The temperature displacement coupling is selected as the mesh type. After the division, the total number of nodes is 98144 and the total number of units is 81178.

[0077] Step 3, calculate the theoretically required rolling force. The rolling force formula used in the present invention is as follows.

[0078] F=S C Q p K m (1)

[0079]

[0080]

[0081]

[0082]

[0083] q1=0.8062-0.302·δ (6)

[0084] q2=0.0419+0.4055·δ-0.2246·δ2 (7)

[0085]

[0086] In the formula, S C is the average contact area between the roll and the workpiece during rolling; Q p is the external friction stress state coefficient; K m is the deformation resistance; R′ is the roller flattening radius; C and D are rolling parameters; is the Poisson's ratio of the roll; E is the Young's modulus of the roll; Δh is the reduction; δ is the reduction rate; q1 and q2 are parameters related to the reduction rate; T is the dimensionless deformation temperature parameter; ε is the true strain; is the strain rate, h0 is the thickness at the entrance of the rolled piece, h1 is the thickness at the exit of the rolled piece, and R is the roller radius.

[0087] Step 4, the theoretical calculation result is 1181519.947N, which is only 1.83% different from the average rolling force of 1159793N calculated by simulation, which verifies the accuracy of the simulation result. Table 2 shows some rolling force results obtained by simulation.

[0088] Table 2 Partial rolling force data

[0089]

[0090]

[0091] The hot rolling process is simulated to solve the temperature change cloud diagram of the workpiece and the roller, the rolling force change history diagram over time, and the contact area change diagram between the workpiece and the roller during the rolling process. Figure 8 , Fig. 9 and Fig.10 shown.

[0092] The present invention adopts the above technical scheme, and only needs a model of the contact part between the roller and the rolled piece, and does not need to simulate and analyze the roller as a whole. The present invention uses the Johnson-Cook constitutive model to simulate the stress and strain of the rolled piece, so that the simulation result is more in line with the actual situation. The contact area between the roller and the rolled piece calculated by simulation is used to replace the parameters of the rolled piece width and the contact arc length in the original formula, so that the formula is also applicable to the rolling force calculation of hot-rolled bars, and the amount of calculation to determine the parameters is also reduced. The result of the simulation calculation is a dynamic load history. Through the results of the visualization processing of the simulation software, the stress and deformation of the rolled piece during the rolling process are more intuitively displayed to the designers. It can play a good guiding role in the design stage for other types of rolling mills, shorten the R&D cycle, save costs, avoid waste of manpower and material resources, and improve the market competitiveness of enterprises.

[0093] Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. In the absence of conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians of the art without making creative work are within the scope of protection of the present application.

Claims

1. A method for calculating rolling force of a short stress rolling mill based on thermo-solid coupling simulation, characterized in that: It includes the following steps: Step 1, simplifying the existing short stress rolling mill model and importing it into engineering simulation software to obtain an engineering model; Step 2: Use explicit dynamics of engineering simulation software to perform dynamic analysis of the rolling process; simulate the stress and strain of the rolled piece through the Johnson-Cook constitutive model to calculate a new plastic deformation curve; Step 3, adjusting the Sims hot rolling formula based on the contact area between the rolling roller and the rolled piece in the simulation results, and calculating the rolling force load; Step 4: Compare the average rolling force obtained by simulation with the rolling force obtained by theoretical calculation to verify the accuracy of the simulation results.

2. The method for calculating rolling force of a short stress rolling mill based on thermo-solid coupling simulation according to claim 1, characterized in that: Step 1 specifically includes the following steps: Step 1-1, simplifying the two-dimensional CAD drawing of the short stress rolling mill roll system through the model and then performing geometric modeling in the three-dimensional modeling software; Step 1-2, importing the obtained geometric modeling into the engineering simulation software for assembly to obtain the engineering model; Steps 1-3, based on the Johnson-Cook constitutive model, set the parameters of the corresponding engineering model in the engineering simulation software.

3. The method for calculating rolling force of a short stress rolling mill based on thermo-solid coupling simulation according to claim 2, characterized in that: In step 1-2, the parts of the roller that are not involved in the rolling contact in the original geometric modeling are deleted and replaced by two rigid plates that are bound and connected to the shaft body; Parts that do not participate in rolling contact include the journal and the shaft head.

4. The method for calculating rolling force of a short stress rolling mill based on thermo-solid coupling simulation according to claim 2, characterized in that: The engineering simulation software used is Abaqus software; the 3D modeling software used is Solidworks software.

5. The method for calculating rolling force of a short stress rolling mill based on thermo-solid coupling simulation according to claim 1, characterized in that: In step 2, the calculation formula for the stress and strain of the material affected by temperature using the Johson-Cook constitutive model is: Wherein, σ is the equivalent flow stress, A is the yield stress at the reference strain rate and reference temperature, B is the material strain hardening modulus, C is the strain rate strengthening parameter, ε is the plastic strain, m is the thermal softening index, is the effective strain rate, n is the material hardening exponent, T * is the relative temperature.

6. The method for calculating rolling force of a short stress rolling mill based on thermo-solid coupling simulation according to claim 1, characterized in that: Step 2 specifically includes the following steps: Step 2-1, setting the boundary conditions and loads of the rolling process according to the actual production situation of the factory; Step 2-2, the entire engineering model is meshed using hexahedral units, the surface of the roller is meshed finely, and the temperature-displacement coupling is selected as the mesh type.

7. The method for calculating rolling force of a short stress rolling mill based on thermo-solid coupling simulation according to claim 1, characterized in that: The rolling force formula in step 3 is as follows: F=S C Q p K m (1) q1=0.8062-0.302·δ (6) q2=0.0419+0.4055·δ-0.2246·δ 2 (7) In the formula, S C is the average contact area between the roll and the workpiece during rolling; Q p is the external friction stress state coefficient; K m is the deformation resistance; R′ is the roller flattening radius; C and D are rolling parameters; θ is the roller Poisson's ratio; E is the roller Young's modulus; Δh is the reduction; δ is the reduction rate; q1 and q2 are parameters related to the reduction rate; T is the dimensionless deformation temperature parameter; ε is the true strain; is the strain rate, h0 is the thickness at the entrance of the rolled piece, h1 is the thickness at the exit of the rolled piece, and R is the roller radius.

8. The method for calculating rolling force of a short stress rolling mill based on thermo-solid coupling simulation according to claim 1, characterized in that: Step 4 compares the difference value after comparison with the preset allowable error. If it is less than the allowable error, it is determined that the simulation structure of the current simulation calculation is accurate; otherwise, execute step 2.

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