Method capable of accurately predicting material deformation rule in roll bending forming process
By obtaining the actual strain state of the material during roll bending forming, constructing a constitutive model and using finite element software to simulate the material deformation laws, the problem of difficult material deformation in traditional processes is solved, and accurate prediction and product quality improvement is achieved.
Patent Information
- Application Number
- CN202510229363.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-28
- Publication Date
- 2025-06-17
AI Technical Summary
The traditional roll bending forming process lacks accurate prediction models, which makes it difficult to control material deformation and affects product quality.
By obtaining the actual strain state of the material during roll bending, conducting bidirectional tensile tests, constructing a constitutive model, and using finite element software to simulate the material deformation law, correcting the constitutive model to accurately predict the material deformation law.
It realizes accurate prediction of material deformation laws during roll bending forming, improves product quality, optimizes manufacturing processes, and reduces resource waste.
Smart Images
Figure CN120162959A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of metal material processing, and particularly to a method for accurately predicting the material deformation law during roll bending forming. Background Art
[0002] Roll bending forming is a metal sheet processing technology. It gradually bends and forms a metal sheet through a series of continuously configured forming rolls to manufacture profiles with specific cross-sectional shapes. This continuous processing method can significantly improve production efficiency and material utilization rate, with low energy consumption and little environmental impact. During the roll bending forming process, the material deformation law has an important impact on the product quality and performance. However, the traditional roll bending forming process often relies on experience and trial-and-error methods and lacks an accurate prediction model, resulting in difficult control of material deformation during the forming process and affecting product quality.
[0003] Predicting the influence of the material deformation law on roll bending forming is multi-faceted, including springback control, forming force adjustment, fracture risk assessment, microstructural changes, and improvement of forming accuracy. These factors jointly determine the quality and efficiency of roll bending forming. At the same time, in the roll bending forming of high-strength steel, the material deformation law also has a direct impact on controlling edge waves, and changes in the yield stress, work hardening coefficient, and normal anisotropy coefficient of the material will all affect the formation of edge waves.
[0004] The material deformation law has a decisive impact on the roll bending forming process, which is directly related to the forming quality, accuracy, and application performance of the product. Therefore, in-depth research and accurate prediction of the material deformation law during roll bending forming are of great significance for improving product quality and optimizing the manufacturing process. Summary of the Invention
[0005] The purpose of the present application is to provide a method for accurately predicting the material deformation law during roll bending forming, which can predict the material deformation law during roll bending forming.
[0006] To achieve the above purpose, the present application provides the following solutions.
[0007] In a first aspect, the present application provides a method for accurately predicting the material deformation law during roll bending forming, including the following steps.
[0008] Obtain the actual strain state of the material to be measured during roll bending forming; the actual strain state is used to characterize the stress-strain distribution of the material to be measured during roll bending forming; the stress-strain distribution includes stress concentration regions and regions with excessive stress.
[0009] Based on the actual strain state, conduct a biaxial tensile test on the material to be measured, simulate the actual stress state during roll bending forming, and determine the biaxial tensile test results.
[0010] Construct a constitutive model based on the results of the biaxial tensile test; the constitutive model is used to describe the deformation behavior of the material to be tested under different stress states.
[0011] Based on the constitutive model, use finite element software to simulate the material deformation law during the roll bending process; the material deformation law includes the plastic deformation law and the springback law.
[0012] According to the simulated material deformation law and the material deformation law during the actual roll bending process, modify the constitutive model to determine the final material deformation law.
[0013] According to the specific embodiments provided in this application, the following technical effects are disclosed in this application:
[0014] Based on the actual strain state of the material to be tested during the roll bending process, this application conducts a biaxial tensile test on the material to be tested, thereby constructing a constitutive model, and uses finite element software to simulate the material deformation law during the roll bending process; this application predicts the material deformation law by constructing an accurate constitutive model, thereby precisely controlling the deformation of the material during the roll bending process and improving the product quality; in addition, this application also compares the simulated material deformation law with the material deformation law during the actual roll bending process, modifies the above-mentioned constitutive model, and further improves the accuracy of the final material deformation law. Description of the Drawings
[0015] In order to more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of this application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0016] Figure 1 It is a flowchart of the method provided in this application that can accurately predict the material deformation law during the roll bending process.
[0017] Figure 2 It is a schematic diagram of the roll bending corner area in the finite element simulation software ABAQUS.
[0018] Figure 3 It is a cross-shaped specimen diagram with slits on the arms when conducting a biaxial tensile test with a cross-shaped specimen. Detailed Description of the Embodiments
[0019] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.
[0020] To make the above objects, features, and advantages of the present application more obvious and understandable, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.
[0021] The embodiment of the present application provides a method capable of accurately predicting the material deformation law during roll bending forming. This method is executed by a computer device, specifically, it can be executed alone by a computer device such as a terminal or a server, or jointly executed by a terminal and a server. In the embodiment of the present application, as Figure 1 shown, the method includes the following steps.
[0022] S1: Obtain the actual strain state of the material to be tested during roll bending forming; the actual strain state is used to characterize the stress-strain distribution of the material to be tested during roll bending forming; the stress-strain distribution includes stress concentration areas and areas with excessive stress.
[0023] S2: Based on the actual strain state, conduct a biaxial tensile test on the material to be tested, simulate the actual stress state during roll bending forming, and determine the biaxial tensile test results.
[0024] S3: Construct a constitutive model according to the biaxial tensile test results; the constitutive model is used to describe the deformation behavior of the material to be tested under different stress states.
[0025] S4: Based on the constitutive model, use finite element software to simulate the material deformation law during roll bending forming; the material deformation law includes plastic deformation law and springback law.
[0026] S5: According to the simulated material deformation law and the material deformation law during the actual roll bending forming process, correct the constitutive model to determine the final material deformation law.
[0027] In an exemplary embodiment, S1 can be replaced by the following steps.
[0028] S11: Use the strain gauges pasted in the bending angle area of the roll bending forming of the material to be tested to obtain the actual strain state of the material to be tested during roll bending forming.
[0029] In practical applications, during the roll bending process, strain is mainly concentrated in the bending angle region. By pasting strain gauges in the bending angle region, the strain distribution in the bending angle region can be obtained.
[0030] Research shows that the transverse bending strain is mainly concentrated at the bending angle and increases with the increase of the forming angle.
[0031] By pasting strain gauges to measure strain, stress data can be calculated according to the relationship between strain and stress. When the object under test is subjected to an external force, the resistance of the strain gauge will change, and this change can be recorded by a measuring instrument and converted into a stress value. At the same time, understanding the strain state of the material during roll bending can ultimately help design more reasonable process parameters to reduce stress concentration and areas with excessive strain, thereby reducing the risk of forming defects and improving material utilization and production efficiency.
[0032] In this application, by analyzing the measured strain state in detail, the stress-strain distribution of the material during roll bending can be understood. This stress-strain distribution includes identifying stress concentration areas and areas with excessive strain, which may lead to early failure or forming defects of the material.
[0033] The measurement results of the strain state can be used to optimize roll bending process parameters such as the number of stands, forming speed, roll gap, and roll diameter. For example, by adjusting the roll diameter, the longitudinal strain difference across the strip cross-section can be significantly reduced, thereby improving the forming performance.
[0034] In an exemplary embodiment, S2 can be replaced by the following steps.
[0035] S21: Based on the actual strain state, perform a biaxial tensile test on the material to be tested, simulate the actual stress state during the roll bending process, and establish equivalent stress and equivalent strain.
[0036] S22: Fit the equivalent stress and the equivalent strain to determine the fitting result; the fitting result is the result of the biaxial tensile test.
[0037] In an exemplary embodiment, the biaxial tensile test can be used to characterize the mechanical properties of the material in different directions, which is crucial for understanding the behavior of the material during roll bending. Through the biaxial tensile test, biaxial stress-strain data of the material can be obtained, and this stress-strain data is the result of the biaxial tensile test. Furthermore, based on the yield criterion applicable to the material, the relationship between equivalent stress and equivalent strain is established, taking the most commonly used HILL48 yield criterion as an example.
[0038] S21 can be replaced by the following steps.
[0039] S211: Utilize Establish the equivalent stress; where f(σ ij ) is the yield criterion; σ ij is the stress component, i = x, y, z, j = x, y, z, and x, y, z are the orthogonal anisotropic principal axes; F, G, H, L, M, N are independent anisotropic characteristic parameters, which are determined by experiments according to different materials.
[0040] S212: Use to establish the equivalent strain; where is the equivalent plastic strain; ε xx is the normal strain in the x direction; ε yy is the normal strain in the y direction; ε xy is the shear strain in the xy plane; N is a material constant.
[0041] In an exemplary embodiment, S22 can be replaced by the following steps.
[0042] S221: Use the Swift plastic model to fit the equivalent stress and the equivalent strain to determine the fitting result; the Swift plastic model is where is the stress of the material; K is the strength coefficient of the material, and the strength coefficient of this material is a constant; is the plastic strain of the material; ε0 is the initial equivalent plastic strain; n is the work hardening index, and this work hardening index is a parameter representing the hardening degree of the material during plastic deformation.
[0043] In an exemplary embodiment, S22 can be replaced by the following steps.
[0044] S221: Use the Voce model to fit the equivalent stress and the equivalent strain to determine the fitting result; the Voce model is where is the stress of the material; σ0 is the initial yield stress of the material; A is the strength coefficient of the material; B is the hardening parameter of the material; is the plastic strain of the material.
[0045] In practical applications, the biaxial tensile test is of great significance for predicting the deformation law and springback phenomenon during roll bending forming. The biaxial tensile test can provide the deformation behavior of the material under complex stress states, which is crucial for predicting and controlling the springback after roll bending forming.
[0046] By understanding the stress-strain characteristics of the material under biaxial tension, the springback phenomenon during roll bending forming can be better predicted and controlled.
[0047] In an exemplary embodiment, the constitutive model in S3 can describe the deformation behavior of materials under different stress states.
[0048] Establish or verify the constitutive model of the material according to the results of the biaxial tensile test. This constitutive model is a mathematical model that describes the behavior of materials under different stress states and plays a core role in the numerical simulation of roll bending forming.
[0049] First, conduct the biaxial tensile test on the material according to the national standard to obtain test data, including key parameters such as the stress-strain curve. Then, the tensile test data needs to be processed to convert the engineering stress and strain obtained from the test into true stress and strain because the actual material constitutive model requires the use of the true stress-strain relationship. Then, according to the properties of the material and the test results, select a suitable constitutive model. For metal materials, the Johnson-Cook model is usually adopted.
[0050] Johnson-Cook model:
[0051] Among them, σ is the true stress; ε is the plastic strain; is the true strain rate; is the reference strain rate; T is the test temperature; T r is the room temperature; T m is the melting temperature of the material; m is the material constant.
[0052] Fit and optimize the parameters in the constitutive model through mathematical optimization methods (such as linear regression), and determine the model parameters according to the data obtained from the biaxial tensile test. For the Johnson-Cook model, it is necessary to determine the initial yield stress, hardening modulus, hardening index, etc.
[0053] In practical applications, in S4, embed the established constitutive model into finite element analysis software such as ABAQUS, ANSYS, etc. to conduct numerical simulation of the roll bending forming process.
[0054] In practical applications, in S5, compare the simulated material deformation law with the material deformation law in the actual roll bending forming process, observe the springback amount, etc., evaluate the accuracy and reliability of the model, and make necessary corrections to the constitutive model according to the comparison results to improve the simulation accuracy.
[0055] This application studies and predicts the deformation law of materials during roll bending forming through biaxial tensile tests. Biaxial tensile tests can evaluate the mechanical properties of materials in two orthogonal directions, which is crucial for understanding the behavior of materials during roll bending forming. Through biaxial tensile tests, the stress-strain curves of materials under complex loading conditions can be obtained, enabling more accurate prediction of the deformation law of materials during roll bending forming. At the same time, biaxial tensile tests can reveal the deformation and fracture characteristics of materials in different directions, which is of guiding significance for optimizing the roll bending forming process, improving material utilization rate, and reducing material waste.
[0056] In this application, the biaxial tensile test provides important material property data and constitutive models for roll bending forming, which helps to optimize process parameters, predict and control springback, understand the evolution of microstructure and texture, and verify and improve numerical simulation models. This is of great significance for improving the accuracy and efficiency of the roll bending forming process.
[0057] Through the study of material properties under different strain states in this application, the roll bending forming process design can be optimized to achieve the processing of different types of workpieces, improving the flexibility and adaptability of the process.
[0058] By embedding the constitutive model into finite element software in this application to predict the deformation law of materials during roll bending forming, empiricism is greatly avoided, and it has stronger general applicability. At the same time, it also avoids exploring the deformation law of materials through the trial-and-error method, greatly reducing the waste of resources and improving work efficiency.
[0059] Taking a specific roll bending forming process as an example below, the technical solution of this application is elaborated.
[0060] As Figure 2 shown, first, a roll bending test is carried out. Strain gauges are pasted in the roll bending corner area 1. The specific operation steps are as follows: After selecting a suitable strain gauge, clean and polish the surface of the area to be measured to ensure the surface is flat and clean, so as to improve the bonding strength between the strain gauge and the material. Paste the strain gauge in the area of concern. When pasting, ensure that there are no air bubbles between the strain gauge and the surface to reduce measurement errors. After pasting, carry out the curing treatment according to the curing requirements of the strain gauge to ensure that the strain gauge adheres firmly to the material surface. Then connect the leads of the strain gauge to a static resistance strain gauge or other measuring equipment.
[0061] During the roll bending test, the strain gauge will deform as the material deforms, thereby generating a resistance change. By collecting the resistance change data of the strain gauge through a measuring device and converting it into a strain value, the actual strain state of the material in the roll bending corner area can be obtained.
[0062] As Figure 3As shown, under the above actual strain state, a biaxial tensile test is carried out using the cruciform specimen 2.
[0063] The biaxial tensile test can provide stress-strain data of the material under complex stress states. Analyze the collected data to determine the stress-strain relationship of the material. Based on the results of the data analysis, establish a mathematical model describing the stress-strain behavior of the material, that is, the constitutive model.
[0064] Then embed the constitutive model into the finite element software, and the deformation law of the material in roll bending can be simulated and predicted in the finite element software. Then repeatedly carry out roll bending tests to observe whether the springback amount in the actual test is consistent with the results simulated in the finite element software. Continuously correct the model by repeatedly comparing the experimental results and the simulation results.
[0065] In summary, this application can accurately predict the deformation law of the material during roll bending forming, which is essentially different from the traditional roll bending forming test method. This application introduces the finite element software and the constitutive model into the test, and predicts the deformation law of the material during roll bending forming by embedding the constitutive model into the finite element software, overcoming various defects such as relying on experience and high trial-and-error costs in the traditional roll bending forming method.
[0066] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.
[0067] Specific examples are used in this article to elaborate on the principle and implementation manner of this application. The description of the above embodiments is only used to help understand the method and its core idea of this application; at the same time, for those of ordinary skill in the art, according to the idea of this application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to this application.
Claims
1. A method for accurately predicting the deformation law of materials during roll forming, characterized in that: The method capable of accurately predicting the deformation law of materials in the roll forming process comprises: Acquire the actual strain state of the material to be tested during the roll bending process; the actual strain state is used to characterize the stress-strain distribution of the material to be tested during the roll bending process; the stress-strain distribution includes stress concentration areas and excessive stress areas; Based on the actual strain state, a biaxial tensile test is performed on the material to be tested, so as to simulate the actual stress state in the roll bending process and determine the biaxial tensile test result; A constitutive model is constructed according to the biaxial tensile test results; the constitutive model is used to describe the deformation behavior of the material to be tested under different stress states; Based on the constitutive model, finite element software is used to simulate the material deformation law during the roll forming process; the material deformation law includes plastic deformation law and springback law; According to the simulated material deformation law and the material deformation law in the actual roll forming process, the constitutive model is modified to determine the final material deformation law.
2. The method for accurately predicting the deformation law of materials during roll forming according to claim 1, characterized in that: Obtain the actual strain state of the material to be tested during roll bending, including: The actual strain state of the material to be measured during the roll bending process is obtained by using the strain gauge pasted on the bending angle area of the material to be measured during the roll bending process.
3. The method for accurately predicting the deformation law of materials during roll forming according to claim 1, characterized in that: Based on the actual strain state, a biaxial tensile test is performed on the material to be tested, the actual stress state in the roll bending forming process is simulated, and the biaxial tensile test result is determined, specifically including: Based on the actual strain state, a biaxial tensile test is performed on the material to be tested to simulate the actual stress state in the roll bending process and establish equivalent stress and equivalent strain; The equivalent stress and the equivalent strain are fitted to determine a fitting result; the fitting result is the biaxial tension test result.
4. The method for accurately predicting the deformation law of materials during roll forming according to claim 3, characterized in that: Based on the actual strain state, a biaxial tensile test is performed on the material to be tested to simulate the actual stress state in the roll bending process and establish equivalent stress and equivalent strain, specifically including: use Establish the equivalent stress; where f(σ ij ) is the yield criterion; σ ij are stress components, i = x, y, z, j = x, y, z, x, y, z are orthogonal anisotropic principal axes; F, G, H, L, M, N are independent anisotropic characteristic parameters; use Establish the equivalent strain; where, is the equivalent plastic strain; ε xx is the positive strain in the x direction; ε yy is the positive strain in the y direction; ε xy is the shear strain in the xy plane; N is the material constant.
5. The method for accurately predicting the deformation law of materials during roll forming according to claim 3, characterized in that: Fitting the equivalent stress and the equivalent strain to determine a fitting result specifically includes: The equivalent stress and the equivalent strain are fitted using the Swift plasticity model to determine the fitting result; the Swift plasticity model is in, is the stress of the material; K is the strength coefficient of the material; is the plastic strain of the material; ε0 is the initial equivalent plastic strain; n is the work hardening exponent.
6. The method for accurately predicting the deformation law of materials during roll forming according to claim 3, characterized in that: Fitting the equivalent stress and the equivalent strain to determine a fitting result specifically includes: The equivalent stress and the equivalent strain are fitted using the Voce model to determine the fitting result; the Voce model is in, is the stress of the material; σ0 is the initial yield stress of the material; A is the strength coefficient of the material; B is the hardening parameter of the material; is the plastic strain of the material.