A method for predicting springback during roll-bending of aluminum profiles with special cross-sections

Abstract

The present invention belongs to the technical field of aluminum profile rolling and bending, and particularly relates to a method for predicting the amount of springback in the rolling and bending process of aluminum profiles with special sections. A method for predicting the amount of springback in the rolling and bending process of aluminum profiles with special sections, comprising the following steps: collecting material property parameters of aluminum profiles with special sections; processing the special sections of aluminum profiles with special sections into rectangular blocks; determining the equivalent section coefficient of the aluminum profiles with special sections; determining the external rolling moment and the forces of the upper roller, the lower left roller, and the lower right roller; determining the stress in the overall thickness direction of the aluminum profiles with special sections; and determining the bending radius and the amount of springback after the aluminum profiles with special sections are unloaded and rebounded. The present invention analyzes the characteristics of aluminum profiles with special sections, reveals the mechanical behavior, and establishes a springback prediction model for the rolling and bending process of profiles, thereby realizing the accurate prediction and control of the springback amount in the rolling and bending process of aluminum profiles with special sections, and providing important technical support for improving production efficiency and product quality.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum profile rolling and bending processing, and in particular relates to a method for predicting the springback amount in a rolling and bending forming process of aluminum profiles with special cross-sections. Background Art

[0002] Special-section aluminum profiles are usually formed by physical deformation and extrusion through diverter holes using aluminum alloy extruder equipment and corresponding shaped dies. They have the characteristics of complex cross-sections, diverse walls, and full-length hollowing. With their light weight, high strength, and corrosion resistance, special-section aluminum profiles are widely used as large structural parts in the locomotives of EMU trains. With the development trend of EMU trains being fast, safe, and energy-saving, the locomotives of trains have put forward increasingly stringent requirements on the structural strength, dimensional accuracy, and product quality of materials.

[0003] Since the interface shape of the train head side beam is complex, the bending modulus is large, the control accuracy requirement is high, and the springback phenomenon is inevitable in the rolling process, how to predict the springback amount in the rolling forming process of special-section aluminum profiles plays a vital role in the high-quality preparation of special-section aluminum profiles. However, the existing technology lacks a means to predict the springback amount in the rolling forming process of special-section aluminum profiles. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a method for predicting the springback amount in the roll bending process of special-section aluminum profiles. The method combines the intrinsic relationship between the neutral layer radius of the special-section aluminum profile and the material properties and internal stress, and establishes a springback prediction model for the roll bending process of special-section aluminum profiles based on the equivalent section coefficient and the force and moment numerical model characterization, so as to achieve quantitative prediction of the rolling springback radius and springback amount, and provide theoretical support for process control and high-quality forming preparation of the rolling process.

[0005] The technical solution of the present invention is: a method for predicting the springback amount in the rolling forming process of special-shaped cross-section aluminum profiles, comprising the following steps:

[0006] S1: Collect material property parameters of special-shaped aluminum profiles;

[0007] S2: Divide the special-shaped cross-section of the special-shaped cross-section aluminum profile into rectangular blocks;

[0008] S3: Determine the equivalent section coefficient W of special-shaped aluminum profiles dx ;

[0009] S4: Determine the rolling bending external moment M and the forces F1, F2, and F3 of the upper roller, the lower left roller, and the lower right roller;

[0010] S5: Determine the stress σ in the overall thickness direction of the special-shaped aluminum profile w,n ;

[0011] S6: Determine the bending radius R2 and rebound amount T of the special-shaped aluminum profile after unloading and rebound c .

[0012] In the step S1, the material property parameters of the special-shaped cross-section aluminum profile include: the relative strengthening coefficient K1 of the aluminum profile, the cross-sectional shape coefficient K0 of the aluminum profile, and the strain rigidity modulus G of the aluminum profile.

[0013] In the step S2, the special-shaped cross-section of the aluminum profile is divided into rectangular blocks according to the structural truss, and each rectangular block includes a rectangular block length l i , rectangular block width h i , the angle between the length direction of the rectangular block and the horizontal direction β i Three characteristic elements, among which i is the structural truss code.

[0014] The equivalent section coefficient W of the special-shaped cross-section aluminum profile in step S3 dx The calculation method is Among them, N is the total number of rectangular block divisions, and γ is the structural strengthening coefficient.

[0015] In step S4, the calculation method of the rolling bending external moment M is: The calculation method of the forces F1, F2, and F3 of the upper roller, lower left roller, and lower right roller is as follows: Among them, h is the thickness of the aluminum profile rolling section, R1 is the inner radius of the aluminum profile rolling process, σ s is the yield strength of the aluminum profile, and α is the angle between the left and right lower rollers and the tangent vertical line of the aluminum profile.

[0016] In step S5, the stress σ in the thickness direction of the special-shaped cross-section aluminum profile is w,n The determination process is as follows:

[0017] S51: Setting the neutral layer radius R3=R1+kΔ, where k is the radius increment step coefficient and Δ is the radius increment step;

[0018] S52: let k=0;

[0019] S53: The stress in the thickness direction of the special-shaped aluminum profile is related to the rolling radius R1 and the equivalent section coefficient W dx The function of the neutral layer radius R3, that is, σ w,n =f(R1,W dx , R3), thereby determining the stress σ in the overall thickness direction of the special-shaped cross-section aluminum profile under the current neutral layer radius R3 condition w,n ;

[0020] S54: Calculate the stress σ in the overall thickness direction of the aluminum profile with special-shaped cross-section based on the relationship between the neutral layer radius R3 and the material properties and internal stress w,n ',Right now Among them, ε s is the yield strain;

[0021] S55: Judgment |σ w,n -σ w,n '|<ε is established, if established, go to step S56; if not established, set k=k+1 and go to step S53;

[0022] S56: Get the stress σ in the overall thickness direction of the special-shaped aluminum profile w,n .

[0023] In step S6, the method for determining the bending radius and the springback amount of the special-shaped cross-section aluminum profile after unloading and springback is as follows: The bending radius after unloading and springback: Rebound:

[0024] The technical effect of the present invention is that: the present invention fully combines the equipment and process characteristics of the rolling equipment, proposes a method for determining the equivalent section coefficient of the special-section aluminum profile, combines the intrinsic relationship between the neutral layer radius and the material properties and internal stress, establishes a solution path for the springback of the rolling process of the special-section aluminum profile, and realizes the quantitative prediction of the rolling springback radius and the springback amount, which can effectively improve the stability of the rolling process of the special-section aluminum profile and the product quality accuracy, and provides theoretical support for the process control and high-quality forming preparation of the rolling process.

[0025] The following is a further description with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a flowchart of a method for predicting springback during the roll bending process of aluminum profiles with special cross-sections according to an embodiment of the present invention.

[0027] Figure 2 This is a cross-sectional characteristic parameter diagram of the special-shaped cross-section aluminum profile according to an embodiment of the present invention.

[0028] Figure 3 Schematic diagram of the rolling bending process of the special-shaped cross-section aluminum profile according to an embodiment of the present invention.

[0029] Figure 4 This is a flow chart for determining stress in the overall thickness direction of a special-shaped cross-section aluminum profile according to an embodiment of the present invention.

[0030] Figure 5 It is a schematic diagram of the springback of the aluminum profile with a special-shaped cross-section after rolling and unloading according to an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Example 1

[0033] like Figure 1 As shown, a method for predicting the springback amount in the rolling bending process of aluminum profiles with special cross-sections comprises the following steps:

[0034] S1: Collect material property parameters of special-shaped aluminum profiles;

[0035] S2: Divide the special-shaped cross-section of the special-shaped cross-section aluminum profile into rectangular blocks;

[0036] S3: Determine the equivalent section coefficient W of special-shaped aluminum profiles dx ;

[0037] S4: Determine the rolling bending external moment M and the forces F1, F2, and F3 of the upper roller, the lower left roller, and the lower right roller;

[0038] S5: Determine the stress σ in the overall thickness direction of the special-shaped aluminum profile w,n ;

[0039] S6: Determine the bending radius R2 and rebound amount T of the special-shaped aluminum profile after unloading and rebound c .

[0040] In the step S1, the material property parameters of the special-shaped cross-section aluminum profile include: the relative strengthening coefficient K1 of the aluminum profile, the cross-sectional shape coefficient K0 of the aluminum profile, and the strain rigidity modulus G of the aluminum profile.

[0041] In the step S2, the special-shaped cross-section of the aluminum profile is divided into rectangular blocks according to the structural truss, and each rectangular block includes a rectangular block length l i , rectangular block width h i , the angle between the length direction of the rectangular block and the horizontal direction β i Three characteristic elements, among which i is the structural truss code.

[0042] The equivalent section coefficient W of the special-shaped cross-section aluminum profile in step S3 dx The calculation method is Among them, N is the total number of rectangular block divisions, and γ is the structural strengthening coefficient.

[0043] In step S4, the calculation method of the rolling bending external moment M is: The calculation method of the forces F1, F2, and F3 of the upper roller, lower left roller, and lower right roller is as follows: Among them, h is the thickness of the aluminum profile rolling section, R1 is the inner radius of the aluminum profile rolling process, σ s is the yield strength of the aluminum profile, and α is the angle between the left and right lower rollers and the tangent vertical line of the aluminum profile.

[0044] In step S5, the stress σ in the thickness direction of the special-shaped cross-section aluminum profile is w,n The determination process is as follows:

[0045] S51: Setting the neutral layer radius R3=R1+kΔ, where k is the radius increment step coefficient and Δ is the radius increment step;

[0046] S52: let k=0;

[0047] S53: The stress in the thickness direction of the special-shaped aluminum profile is related to the rolling radius R1 and the equivalent section coefficient W dx The function of the neutral layer radius R3, that is, σ w,n =f(R1,W dx , R3), thereby determining the stress σ in the overall thickness direction of the special-shaped cross-section aluminum profile under the current neutral layer radius R3 condition w,n ;

[0048] S54: Calculate the stress σ in the overall thickness direction of the aluminum profile with special-shaped cross-section based on the relationship between the neutral layer radius R3 and the material properties and internal stress w,n ',Right now Among them, ε s is the yield strain;

[0049] S55: Judgment |σ w,n -σ w,n '|<ε is established, if established, go to step S56; if not established, set k=k+1 and go to step S53;

[0050] S56: Get the stress σ in the overall thickness direction of the special-shaped aluminum profile w,n .

[0051] In step S6, the method for determining the bending radius and the springback amount of the special-shaped cross-section aluminum profile after unloading and springback is as follows: The bending radius after unloading and springback: Rebound:

[0052] Example 2

[0053] The method for predicting the springback amount during the rolling forming process of the aluminum profile with a special cross-section as described in Example 1 is used to predict the springback amount during the rolling forming process of the aluminum profile with a special cross-section of XX. The specific process is as follows:

[0054] S1: Collect material property parameters of XX special-shaped cross-section aluminum profiles;

[0055] The relative strengthening coefficient K1 of the XX special-shaped aluminum profile is 2.5, the cross-sectional shape coefficient K0 of the aluminum profile is 1.2, and the strain modulus G of the aluminum profile is 6.5×10 10 Mpa;

[0056] S2: Divide the special-shaped cross-section of XX aluminum profile into rectangular blocks;

[0057] XX aluminum profiles with special cross-sections, such as Figure 2 As shown, the structural trusses are divided into rectangular blocks, each of which includes a rectangular block length l i , rectangular block width h i , the angle between the length direction of the rectangular block and the horizontal direction β i Three characteristic elements, the specific parameters are shown in Table 1;

[0058] Table 1 Characteristic parameters of the special-shaped cross-section of XX aluminum profiles after processing into rectangular blocks

[0059]

[0060]

[0061] S3: Calculate the equivalent section coefficient W of XX special-shaped aluminum profiles dx ;

[0062] The structural reinforcement coefficient γ is taken as 1.5, and the equivalent section coefficient of XX special-shaped aluminum profile is calculated according to the data in Table 1 to obtain W dx =275887;

[0063] S4: Calculate the external rolling moment M and the forces F1, F2, and F3 of the upper roller, the lower left roller, and the lower right roller;

[0064] like Figure 3 As shown, the external rolling moment M = 874010N·m, the upper roller force F1 = 1120kN, and the left lower roller and right lower roller force F2 = F3 = 871kN are obtained by calculation;

[0065] S5: Calculate the stress σ in the thickness direction of the special-shaped aluminum profile w,n ;

[0066] like Figure 4 As shown, the stress σ in the overall thickness direction of the special-shaped aluminum profile is calculated w,n , a) Set the neutral layer radius R3 = 1004 + kΔ, and the radius increment step Δ is 0.1mm; b) Set k = 0; c) The stress in the thickness direction of the special-shaped aluminum profile is about the rolling radius R1 and the equivalent section coefficient W dx The function of the neutral layer radius R3, that is, σw,n =f(R1,W dx ,R3), it is concluded that when k=0, σ w,n =126MPa; d) According to the relationship between the neutral layer radius R3 and the material properties and internal stress, calculate the stress σ in the overall thickness direction of the special-shaped cross-section aluminum profile w,n '=187MPa; e) Determine |σ w,n -σ w,n '|<ε is established, if established, go to step f); if not established, let k=k+1, go to step c), and it is found that the inequality is established when k=1265; f) Calculate the stress σ in the overall thickness direction of the special-shaped cross-section aluminum profile w,n =153MPa;

[0067] S6: Determine the bending radius and springback amount of the special-shaped aluminum profile after unloading and springback;

[0068] like Figure 5 As shown in the figure, according to the calculation method of the bending radius and springback amount of the special-shaped cross-section aluminum profile after unloading and rebound, the output bending radius after unloading and rebound is R2 = 1385mm, and the springback amount is: T c =138.6mm.

[0069] The method of the present invention can predict the springback amount of the rolling bending process of XX special-shaped cross-section aluminum profiles, effectively improving the stability of the rolling bending process and the quality accuracy of the product.

[0070] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for predicting the springback amount during the roll-bending process of aluminum profiles with special cross-sections, characterized in that: Includes the following step: S1: Collect material property parameters of special-shaped aluminum profiles; In the step S1, the material property parameters of the special-shaped cross-section aluminum profile include: the relative strengthening coefficient K1 of the aluminum profile, the cross-sectional shape coefficient K0 of the aluminum profile, and the strain rigidity modulus G of the aluminum profile; S2: Divide the special-shaped cross-section of the special-shaped cross-section aluminum profile into rectangular blocks; In the step S2, the special-shaped cross-section of the aluminum profile is divided into rectangular blocks according to the structural truss, and each rectangular block includes a rectangular block length l i , rectangular block width h i , the angle between the length direction of the rectangular block and the horizontal direction β i Three characteristic elements, where i is the structural truss code; S3: Determine the equivalent section coefficient W of special-shaped aluminum profiles dx ; The equivalent section coefficient W of the special-shaped cross-section aluminum profile in step S3 dx The calculation method is Where N is the total number of rectangular blocks divided, and γ is the structural strengthening coefficient; S4: Determine the rolling bending external moment M and the forces F1, F2, and F3 of the upper roller, the lower left roller, and the lower right roller; In step S4, the calculation method of the rolling bending external moment M is: The calculation method of the forces F1, F2, and F3 of the upper roller, lower left roller, and lower right roller is as follows: Among them, h is the thickness of the aluminum profile rolling section, R1 is the inner radius of the aluminum profile rolling process, σ s is the yield strength of the aluminum profile, α is the angle between the left and right lower rollers and the vertical line tangent to the aluminum profile; S5: Determine the stress σ in the overall thickness direction of the special-shaped aluminum profile w,n ; In step S5, the stress σ in the thickness direction of the special-shaped cross-section aluminum profile is w,n The determination process is as follows: S51: Setting the neutral layer radius R3=R1+kΔ, where k is the radius increment step coefficient and Δ is the radius increment step; S52: let k=0; S53: The stress in the thickness direction of the special-shaped aluminum profile is related to the rolling radius R1 and the equivalent section coefficient W dx The function of the neutral layer radius R3, that is, σ w,n =f(R1,W dx , R3), thereby determining the stress σ in the overall thickness direction of the special-shaped cross-section aluminum profile under the current neutral layer radius R3 condition w,n ; S54: Calculate the stress σ in the overall thickness direction of the aluminum profile with special-shaped cross-section based on the relationship between the neutral layer radius R3 and the material properties and internal stress w,n ',Right now Among them, ε s is the yield strain; S55: Judgment |σ w,n -σ w,n '|<ε is established, if established, go to step S56; if not established, set k=k+1 and go to step S53; S56: Get the stress σ in the overall thickness direction of the special-shaped aluminum profile w,n ; S6: Determine the bending radius R2 and rebound amount T of the special-shaped aluminum profile after unloading and rebound c ; In step S6, the method for determining the bending radius and the springback amount of the special-shaped cross-section aluminum profile after unloading and springback is as follows: The bending radius after unloading and springback: Rebound:

Images