A method for predicting the formability of a sheet metal

Abstract

The embodiment of the present application provides a kind of prediction method of sheet forming performance.The method comprises: obtaining the mechanical property parameters of candidate sheet and forming limit curve;According to the forming limit curve, select target theoretical model from at least one candidate theoretical model;According to the mechanical property parameters of the candidate sheet and the target theoretical model, the finite element simulation of target part forming process is carried out, the simulation strain when the target part simulation cracks is determined, and the lowest forming limit curve is generated;Obtain the plane strain point in the lowest forming limit curve, and according to the plane strain point and the target theoretical model, the forming performance prediction of the candidate sheet is completed.The technical scheme of the embodiment of the present application can predict the forming performance of the sheet for a specific part forming process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal processing, in particular to a method for predicting forming performance of a plate. BACKGROUND

[0002] In the field of metal plastic forming, the forming performance of a metal plate has an important influence on the yield of a product. In view of the goal of improving production efficiency and reducing production cost, it is necessary to predict the forming performance of a metal plate for a specific forming process in view of the current situation that the types and thickness specifications of metal plates are various and the forming technology is continuously developed. SUMMARY

[0003] Embodiments of the present application provide a method for predicting forming performance of a plate, so as to at least partly predict the forming performance of a plate for a specific part forming process.

[0004] Other features and advantages of the present application will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, or some of which will be learned by practice of the present application.

[0005] According to an aspect of embodiments of the present application, a method for predicting forming performance of a plate is provided, the method comprising: obtaining mechanical property parameters of a candidate plate and a forming limit curve; selecting a target theoretical model from at least one candidate theoretical model according to the forming limit curve; performing finite element simulation on a target part forming process according to the mechanical property parameters of the candidate plate and the target theoretical model, determining a simulation strain at which the target part simulation cracks, and generating a lowest forming limit curve; obtaining a plane strain point in the lowest forming limit curve, and completing the forming performance prediction of the candidate plate according to the plane strain point and the target theoretical model.

[0006] In some embodiments of the present application, the obtaining of the mechanical property parameters of the candidate plate comprises: performing a uniaxial tensile test on the candidate plate to obtain the mechanical property parameters of the candidate plate.

[0007] In some embodiments of the present application, the obtaining of the forming limit curve of the candidate plate comprises: performing a forming performance test on the candidate plate to obtain the forming limit curve of the candidate plate.

[0008] In some embodiments of the present application, the mechanical property parameters comprise: plate yield strength, tensile strength, elongation, strain hardening index, and plastic strain ratio.

[0009] In some embodiments of the present application, the selecting a target theoretical model from the at least one candidate theoretical model according to the forming limit curve comprises: comparing degrees of fitting of the forming limit curve and each candidate theoretical model; and selecting the target theoretical model from the at least one candidate theoretical model according to the degrees of fitting.

[0010] In some embodiments of the present application, the performing finite element simulation on the target part forming process to determine a simulation strain at which the target part is simulated to crack comprises:

[0011] performing finite element simulation on the target part forming process to determine a simulation main strain and a simulation secondary strain at which the target part is simulated to crack.

[0012] In some embodiments of the present application, based on the foregoing scheme, the generating the lowest forming limit curve comprises: drawing an initial forming limit curve according to the simulation main strain and the simulation secondary strain; and obtaining a safety margin, and drawing the lowest forming curve according to the safety margin and the initial forming limit curve, the safety margin being used to ensure that the lowest forming curve meets the forming process of the target part.

[0013] In some embodiments of the present application, based on the foregoing scheme, the drawing the lowest forming curve according to the safety margin and the initial forming limit curve comprises: adjusting the initial forming limit curve according to the safety margin to draw the lowest forming curve.

[0014] In some embodiments of the present application, the completing the forming performance prediction of the candidate sheet metal according to the plane strain point and the target theoretical model comprises: substituting the plane strain point into the target theoretical model to calculate sheet metal mechanical properties corresponding to the plane strain point; and comparing mechanical property parameters of the candidate sheet metal and the sheet metal mechanical properties corresponding to the plane strain point to predict a suitability of the candidate sheet metal for manufacturing the target part.

[0015] In some embodiments of the present application, based on the foregoing scheme, the comparing the mechanical property parameters of the candidate sheet metal and the sheet metal mechanical properties corresponding to the plane strain point to predict the suitability of the candidate sheet metal for manufacturing the target part comprises: comparing the mechanical property parameters of the candidate sheet metal and the sheet metal mechanical properties corresponding to the plane strain point; if the mechanical property parameters of the candidate sheet metal are superior to the sheet metal mechanical properties corresponding to the plane strain point, predicting that the candidate sheet metal is suitable for manufacturing the target part; and if the mechanical property parameters of the candidate sheet metal are inferior to the sheet metal mechanical properties corresponding to the plane strain point, predicting that the candidate sheet metal is not suitable for manufacturing the target part.

[0016] In the technical scheme provided in some embodiments of the present application, the forming process of a target part is simulated by finite element according to the actual mechanical performance parameters of a candidate sheet material and a forming limit curve, a plane strain point in the minimum forming limit curve is determined, and then the forming performance prediction of the candidate sheet material is completed according to the plane strain point and the target theoretical model. The forming performance of the supply material is predicted by combining the test and the forming process finite element simulation, so that the processing of the part does not exceed the deformation limit of the supply material, the cracking of the part is avoided, and the part production efficiency is improved.

[0017] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and are not limiting to the present application. BRIEF DESCRIPTION OF DRAWINGS

[0018] The drawings incorporated in the specification and constituting a part of it illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. In the drawings:

[0019] Figure 1 A flow chart of a sheet material forming performance prediction method according to an embodiment of the present application is shown;

[0020] Figure 2 A forming limit curve diagram of a sheet material forming performance prediction method according to an embodiment of the present application is shown;

[0021] Figure 3 A flow chart of a sheet material forming performance prediction method according to an embodiment of the present application is shown;

[0022] Figure 4 A plurality of candidate theoretical model diagrams of a sheet material forming performance prediction method according to an embodiment of the present application are shown;

[0023] Figure 5 A forming limit curve and a plurality of candidate theoretical model fitting diagram of a sheet material forming performance prediction method according to an embodiment of the present application is shown;

[0024] Figure 6 A primary and secondary strain diagram of a cracking risk area of a sheet material forming performance prediction method according to an embodiment of the present application is shown;

[0025] Figure 7 A comparison diagram of an initial forming limit curve and a minimum forming curve of a sheet material forming performance prediction method according to an embodiment of the present application is shown;

[0026] Figure 8 A flow chart of a method of predicting sheet forming performance is shown according to one embodiment of the present application.

[0027] Figure 9 A finite element software interface of a method of predicting sheet forming performance is shown. DETAILED DESCRIPTION

[0028] Example implementations will now be described more fully with reference to the accompanying drawings. Example implementations may, however, be implemented in many different forms and should not be construed as limited to the examples set forth herein; rather, these example implementations are provided so that this disclosure will be thorough and complete, and will fully convey the scope of example implementations to those skilled in the art.

[0029] The flow charts shown in the drawings are only illustrative and do not necessarily include all the contents and operations / steps, nor are they necessarily executed in the order described. For example, some operations / steps can be further broken down, while some operations / steps can be combined or partially combined, so the actual execution order can be changed according to the actual situation.

[0030] It should be noted that "multiple" referred to herein means two or more. The "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the three cases of A alone, A and B together, and B alone. The character " / " generally represents that the associated objects before and after are in an "or" relationship.

[0031] The embodiments in the present application are related to the technology of finite element analysis (FEA). FEA is a numerical method for approximating the behavior of real physical systems (geometry and loading conditions) using mathematical approximations. Using simple and interacting elements (i.e. elements), a finite number of unknowns can be used to approximate the infinite unknowns of a real system. FEA is a method of replacing a complex problem with a simpler one and then solving it. It considers the solution domain as being composed of a number of small interconnected sub-domains called finite elements. For each element, a suitable (simpler) approximate solution is assumed and then the overall solution of the domain is derived to satisfy the conditions (such as equilibrium conditions of the structure) to obtain the solution of the problem. Because the actual problem is replaced by a simpler one, the solution is not an exact one but an approximate one. Since most actual problems are difficult to obtain an exact solution, FEA is a practical and effective engineering analysis method because of its high accuracy and adaptability to various complex shapes. Finite elements are discrete elements that are combined together to represent a continuous domain. The concept of finite elements has been generated and applied for several centuries, such as using polygons (a finite number of straight line elements) to approximate a circle to obtain the circumference of the circle. However, as a method, it was proposed recently. FEA was initially called the matrix approximation method and was applied to the structural strength calculation of aircraft. Due to its convenience, practicality and effectiveness, it attracted the interest of scientists engaged in mechanics research. After decades of efforts, with the rapid development and popularization of computer technology, FEA has rapidly expanded from structural engineering strength analysis and calculation to almost all scientific and technical fields, becoming a rich and colorful, widely applied and practical and efficient numerical analysis method.

[0032] Referring to Figure 1 .

[0033] Figure 1 A flowchart of a method for predicting sheet forming performance according to an embodiment of the present application is shown in FIG. 1, which includes at least steps S101 to S104, as shown in FIG. 1, and will be described in detail as follows. Figure 1

[0034] In step S101, the mechanical property parameters and forming limit curve of a sheet to be selected are obtained.

[0035] In step S102, a target theoretical model is selected from at least one selected theoretical model according to the forming limit curve.

[0036] In step S103, a finite element simulation of a target part forming process is performed according to the mechanical property parameters of the selected sheet and the target theoretical model, a simulation strain at which the target part simulation cracks is determined, and a minimum forming limit curve is generated.

[0037] ​Step S104, a plane strain point in the minimum forming limit curve is acquired, and the forming performance prediction of the candidate sheet metal is completed according to the plane strain point and the target theoretical model.

[0038] In the present application, the forming process of a target part can be simulated by finite element method according to the actual mechanical performance parameters and the forming limit curve of the candidate sheet metal, the plane strain point in the minimum forming limit curve is determined, and the forming performance prediction of the candidate sheet metal is completed according to the plane strain point and the target theoretical model. The forming performance of the supply material is predicted by combining the test and the finite element simulation of the forming process, so that the processing of the part does not exceed the deformation limit of the supply material, the cracking of the part is avoided, and the efficiency of the finished part is improved.

[0039] In the present application, the method for acquiring the mechanical performance parameters of the candidate sheet metal can include: performing a uniaxial tensile test on the candidate sheet metal to acquire the mechanical performance parameters of the candidate sheet metal.

[0040] In the present application, the uniaxial tensile test is the most widely used material mechanical performance test method in industrial and material science research. Through the tensile test, the stress-strain relationship of the material under static load and the characteristics and basic laws of the three common failure forms (excessive elastic deformation, plastic deformation and fracture) can be revealed, and the basic mechanical performance indexes of the material, such as yield strength, tensile strength, elongation and reduction of area, can be evaluated. These performance indexes are not only the calculation basis for material engineering application, component design and scientific research, but also the main basis for material evaluation and selection and processing process selection.

[0041] In the present application, the mechanical performance parameters can include: sheet metal yield strength, tensile strength, elongation, strain hardening index, and plastic strain ratio.

[0042] In the present application, the method for acquiring the forming limit curve of the candidate sheet metal can include: performing a forming performance test on the candidate sheet metal to acquire the forming limit curve of the candidate sheet metal.

[0043] It is to be noted that the forming limit diagram (FLD) is also referred to as forming limit curve (FLC), which is a strip-shaped area or curve composed of local instability limit engineering strains e1 and e2 or limit true strains ε1 and ε2 of a sheet metal under different strain paths, commonly denoted as FLD or FLC. It reflects the ability of the sheet metal to resist necking or cracking under the action of uniaxial and biaxial tensile stress, and is often used to analyze and solve cracking problems during forming. Various overall forming performance indicators or forming limits of the sheet metal mostly reflect that some overall size changes of the sample reach a certain degree (e.g., cracking occurs), and cannot reflect the deformation of a local dangerous area of the sheet metal. The FLD can reflect the local forming limit of the sheet metal under the action of uniaxial and biaxial tensile stress, and establishes a foundation for the fixed and quantitative research on the local forming performance of the sheet metal.

[0044] For example, refer to Figure 2 , Figure 2 A forming limit curve diagram of a method for predicting sheet forming performance according to an embodiment of the present application is shown.

[0045] For example, refer to Figure 3 .

[0046] Figure 3 A flowchart of a method for predicting sheet forming performance according to an embodiment of the present application is shown, as shown in Figure 3 The method for selecting a target theoretical model from at least one candidate theoretical model according to the forming limit curve can include steps S301-S302:

[0047] Step S301: Comparing the fitting degree of the forming limit curve and each candidate theoretical model.

[0048] Step S302: Selecting a target theoretical model from at least one candidate theoretical model according to the fitting degree.

[0049] In the present embodiment, the finite element software AutoForm can be used as the simulation software, and at least one candidate theoretical model has been loaded in the finite element software AutoForm, which can represent the strain of the sheet metal during the forming process.

[0050] For example, refer to Figure 4 , Figure 4 A plurality of candidate theoretical model diagrams of a method for predicting sheet forming performance according to an embodiment of the present application are shown, which are respectively Keeler model, Arcelor model, and Tata model.

[0051] In the present application, the target theoretical model can be selected from at least one of the candidate theoretical models according to the fitting degree of the forming limit curve and each candidate theoretical model.

[0052] For example, refer to Figure 5 , Figure 5 The forming limit curve and the fitting diagram of the plurality of candidate theoretical models of the prediction method of the sheet forming performance according to one embodiment of the present application are shown, and it is not difficult to conclude that the fitting degree of the Tata model is relatively highest, and therefore the Tata model can be selected as the target theoretical model.

[0053] In the present application, the method of performing finite element simulation on the forming process of the target part to determine the simulation strain when the target part is simulated to crack can include: performing finite element simulation on the forming process of the target part to determine the simulation main strain and the simulation secondary strain when the target part is simulated to crack.

[0054] For example, refer to Figure 6 , Figure 6 The main and secondary strain diagram of the cracking risk area of the prediction method of the sheet forming performance according to one embodiment of the present application is shown.

[0055] In the present application, the method of generating the lowest forming limit curve can include: drawing an initial forming limit curve according to the simulation main strain and the simulation secondary strain; obtaining a safety margin, and drawing a lowest forming curve according to the safety margin and the initial forming limit curve, the safety margin being used to ensure that the lowest forming curve meets the forming process of the target part.

[0056] For example, refer to Figure 7 , Figure 7 The comparison diagram of the initial forming limit curve and the lowest forming curve of the prediction method of the sheet forming performance according to one embodiment of the present application is shown. As Figure 7 shown, the initial forming limit curve 701 can be drawn according to the main and secondary strain of the cracking risk area, and then the initial forming limit curve 701 is adjusted according to the safety margin of 10% to draw the lowest forming curve 702. In addition, in Figure 7 , it is not difficult to obtain the plane strain point 703 of 0.218.

[0057] For example, refer to Figure 8 .

[0058] Figure 8 The flowchart of the prediction method of the sheet forming performance according to one embodiment of the present application is shown, and as Figure 8 shown, the method of completing the prediction of the forming performance of the candidate sheet according to the plane strain point and the target theoretical model can include steps S801-S802:

[0059] Step S801, substituting the plane strain point into the target theoretical model, calculating the mechanical properties of the plate corresponding to the plane strain point.

[0060] Step S802, comparing the mechanical property parameters of the selected plate with the mechanical properties of the plate corresponding to the plane strain point, predicting the suitability of the selected plate for manufacturing the target part.

[0061] In the finite element software AutoForm, the plane strain point can be input into the theoretical model to calculate the mechanical properties of the plate, so as to determine whether the selected plate meets the forming requirements of the target part.

[0062] For example, please refer to Figure 9 , Figure 9 The finite element software interface for predicting the forming performance of the plate is shown in Figure 9 , the plane strain point 0.218 of the forming limit curve is substituted into the target theoretical model Tata model, and the elongation (A80) of the material is inversely calculated to be about 30.5%, and the R values of the three directions are r0=1.75, r 45 =1.67, and r 90 =1.5.

[0063] In this application, the method of comparing the mechanical property parameters of the selected plate with the mechanical properties of the plate corresponding to the plane strain point to predict the suitability of the selected plate for manufacturing the target part can include: comparing the mechanical property parameters of the selected plate with the mechanical properties of the plate corresponding to the plane strain point:

[0064] If the mechanical property parameters of the selected plate are better than the mechanical properties of the plate corresponding to the plane strain point, it is predicted that the selected plate is suitable for manufacturing the target part.

[0065] If the mechanical property parameters of the selected plate are worse than the mechanical properties of the plate corresponding to the plane strain point, it is predicted that the selected plate is not suitable for manufacturing the target part.

[0066] For example, in the mechanical properties of the plate corresponding to the plane strain point, the elongation (A80) is about 30.5%, if the elongation of the selected plate is lower than 30.5%, it is indicated that the selected plate cannot guarantee that no fracture occurs during the forming process of the target part, and therefore it can be predicted that the current selected plate is not suitable for manufacturing the target part; if the elongation of the selected plate is higher than 30.5%, it is indicated that the selected plate can guarantee to a certain extent that no fracture occurs during the forming process of the target part, and therefore it can be predicted that the current selected plate is suitable for manufacturing the target part.

[0067] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the features disclosed herein. It is intended that the application embrace any and all variations of the present application that fall within the scope of the general inventive concept as defined by the appended claims and their equivalents. It is intended that the application encompass all such variations as fall within the scope of the appended claims and their equivalents.

[0068] It is to be understood that the application is not limited to the precise construction herein described and as shown in the drawings, and that various modifications and changes can be made by those skilled in the art without departing from the scope of the application. The scope of the application should only be limited by the claims appended hereto.

Claims

1. A method for predicting the forming properties of sheet metal, characterized in that, The method includes: Obtain the mechanical property parameters and forming limit curves of the candidate sheet materials; Based on the forming limit curve, select the target theoretical model from at least one candidate theoretical model; Based on the mechanical property parameters of the selected sheet metal and the target theoretical model, finite element simulation is performed on the forming process of the target part to determine the simulated strain when the target part cracks and generate the minimum forming limit curve. Obtain the plane strain point in the minimum forming limit curve, and based on the plane strain point and the target theoretical model, complete the prediction of the forming performance of the candidate sheet material; The step of selecting a target theoretical model from at least one candidate theoretical model based on the forming limit curve includes: Compare the fitting degree between the forming limit curve and each candidate theoretical model; Based on the degree of fit, a target theoretical model is selected from at least one candidate theoretical model; The candidate theoretical models include: Keeler model, Arcelor model, and Tata model.

2. The method according to claim 1, characterized in that, The process of obtaining the mechanical property parameters of the candidate plate material includes: A uniaxial tensile test was conducted on the selected plate material to obtain its mechanical property parameters.

3. The method according to claim 1, characterized in that, The process of obtaining the forming limit curve of the candidate sheet material includes: A forming performance test is conducted on the selected sheet material to obtain the forming limit curve of the selected sheet material.

4. The method according to claim 1, characterized in that, The mechanical properties parameters include: sheet yield strength, tensile strength, elongation, strain hardening index, and plastic strain ratio.

5. The method according to claim 1, characterized in that, The step of performing finite element simulation on the forming process of the target part to determine the simulated strain when the target part cracks includes: Finite element simulation was performed on the forming process of the target part to determine the simulated principal strain and simulated secondary strain when the target part cracked.

6. The method according to claim 5, characterized in that, The generation of the minimum forming limit curve includes: Based on the simulated principal strain and the simulated secondary strain, the initial forming limit curve is plotted. Obtain a safety margin, and based on the safety margin and the initial forming limit curve, draw a minimum forming curve. The safety margin is used to ensure that the minimum forming curve meets the forming process of the target part.

7. The method according to claim 6, characterized in that, The step of plotting the minimum forming curve based on the safety margin and the initial forming limit curve includes: Based on the safety margin, the initial forming limit curve is adjusted to plot the minimum forming curve.

8. The method according to claim 1, characterized in that, The step of predicting the forming performance of the candidate sheet metal based on the plane strain point and the target theoretical model includes: Substitute the plane strain point into the target theoretical model to calculate the mechanical properties of the plate corresponding to the plane strain point; By comparing the mechanical property parameters of the candidate plate material with the mechanical properties of the plate material corresponding to the plane strain point, the suitability of the candidate plate material for manufacturing the target part is predicted.

9. The method according to claim 8, characterized in that, The comparison of the mechanical property parameters of the candidate sheet metal and the mechanical properties of the sheet metal corresponding to the plane strain point, and the prediction of the suitability of the candidate sheet metal for manufacturing the target part, includes: Compare the mechanical property parameters of the candidate plate with the mechanical properties of the plate corresponding to the plane strain point; If the mechanical property parameters of the candidate plate are better than the mechanical properties of the plate corresponding to the plane strain point, then it is predicted that the candidate plate is suitable for manufacturing the target part. If the mechanical properties of the candidate material are inferior to those of the material corresponding to the plane strain point, then it is predicted that the candidate material is not suitable for manufacturing the target part.

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