Free bending forming distortion correction method and system for non-closed profile difficult to deform

Abstract

The invention relates to a distortion correction method and system for free bending forming of a non-closed profile difficult to deform. The method comprises the steps that the elasticity modulus, the yield strength and the thermal expansion coefficient of a profile, the wall thickness of the section of the profile, the bending radius, the distance from a bending force acting shaft to the farthest point on the section, the inertia moment of the section of the profile and the distance from the moment acting position to the shearing center are obtained; calculating to obtain a torque generated by torsion of the profile due to the shearing force; obtaining the heating area of the section of the profile; establishing a matching relationship between the heating temperature required for correcting the distortion and the distance from the center of the heating area to the centroid; based on the matching relation, according to the sectional dimension and the centroid position of the profile, a heating parameter combination of the needed heating temperature and distance is determined; and according to the heating parameter combination, a differential temperature assisted free bending forming process is implemented, and real-time correction of profile distortion is achieved. The method can effectively solve the problem of distortion of the non-closed profile difficult to deform in the free bending forming process.

Description

Technical Field

[0001] The present invention relates to the technical field of advanced manufacturing of complex profile bent components, and in particular to a method and system for correcting distortion of free bending forming of difficult-to-deform non-closed profiles. Background Art

[0002] Free bending and twisting technology is one of the key methods for achieving the integral forming of components with complex geometric features. This technology actively controls the translational and rotational motion of the forming mechanism to adjust its position in three-dimensional space. Combined with the continuous feeding of the blank, it simultaneously applies bending moments and torques of varying magnitudes and directions to the component. This allows for continuous changes in the component's bending radius, bending angle, and cross-sectional torsion angle without changing the mold, offering significant advantages in wide process adaptability and high flexibility.

[0003] However, non-closed profiles made of difficult-to-deform materials have poor plasticity at room temperature and significant springback after forming. Moreover, due to their diverse distribution positions and functions, they usually need to be bent along an asymmetric axis, causing their shear center and centroid to not coincide. This easily generates additional shear stress on the profile cross section and forms additional torque during the bending process, leading to severe twisting deformation of the component. This increases the difficulty of controlling the torsion angle of the profile cross section and limits the application of this process.

[0004] At present, the method to solve the distortion problem of non-closed profiles during bending forming mainly adopts mechanical correction method, which corrects the distortion defects by adding a special correction process after forming. However, this method is inefficient and easily causes damage to the profile surface. Moreover, it is a post-correction rather than process control, and cannot fundamentally solve the distortion problem of non-closed profiles during free bending forming. Summary of the Invention

[0005] To this end, the present invention provides a method and system for correcting distortion in the free bending forming of difficult-to-deform non-closed profiles. The method realizes real-time correction of distortion during the bending process of non-closed profiles through differential temperature auxiliary technology. The method is simple and feasible, has high forming quality, and strong adaptability, and can effectively solve the distortion problem of difficult-to-deform non-closed profiles during the free bending forming process.

[0006] In order to solve the above technical problems, the present invention provides a method for correcting distortion of a non-closed profile that is difficult to deform by free bending forming, comprising: Get the elastic modulus of the profile E , yield strength σ y , thermal expansion coefficient α , wall thickness of profile section t , bending radius R , Distance from the bending force axis to the farthest point on the cross section y max , profile section moment of inertiaI , the distance between the moment action position and the shear center e ; According to the elastic modulus E , the yield strength σ y , the thermal expansion coefficient α , the wall thickness of the profile section t , the bending radius R , the distance from the bending force axis to the farthest point on the cross section y max , the section moment of inertia of the profile I , the distance between the moment action position and the shear center e , and the torque generated by the shear force causing the profile to twist is obtained M T ; Get the heating area of ​​the profile cross section A ; Based on the thermal torque caused by the local heating area, and according to the torque M T , the elastic modulus E , the thermal expansion coefficient α and the heating area A , establish the heating temperature required to correct the distortion T The distance from the center of the heating area to the centroid d matching relationship; Based on the matching relationship, and according to the cross-sectional dimensions and centroid position of the profile, the required heating temperature is determined. T and distance d Heating parameter combination; According to the heating parameter combination, a differential temperature assisted free bending forming process is implemented to achieve real-time correction of profile distortion.

[0007] In one embodiment of the present invention, the shear force causes the profile to twist and generate a torque. M T The calculation formula is: .

[0008] In one embodiment of the present invention, the thermal torque caused by the local heating area M th The calculation formula is: , where △ T It is the local heating temperature.

[0009] In one embodiment of the present invention, the heating temperature required to correct the distortion is established T The distance from the center of the heating area to the centroidd The matching relationship is: .

[0010] In one embodiment of the present invention, the required heating temperature is determined based on the cross-sectional dimensions and centroid position of the profile. T and distance d The heating parameter combination includes: Determine the distance based on the profile cross-section size and centroid position d When the value range of d The minimum value is 0, the distance d The maximum value is the distance from the edge of the profile section to the centroid.

[0011] In one embodiment of the present invention, the temperature differential assisted free bending forming process is implemented on a six-axis free bending and torsion device.

[0012] In one embodiment of the present invention, it further comprises: An open induction coil is installed between the bending die and the guide roller of the six-axis free bending and torsion equipment. The open induction coil is set near the shear center of the profile section and the distance between the open induction coil and the different surfaces of the profile is consistent after installation.

[0013] The present invention also provides a system for free bending, forming and distortion correction of non-closed profiles that are difficult to deform, comprising: Profile thermodynamic parameter acquisition module, used to obtain the elastic modulus of the profile E , yield strength σ y , thermal expansion coefficient α , wall thickness of profile section t , bending radius R , Distance from the bending force axis to the farthest point on the cross section y max , profile section moment of inertia I , the distance between the moment action position and the shear center e ; The torque acquisition module is used to obtain the torque generated by the distortion of the profile due to the shear force according to the elastic modulus. E , the yield strength σ y , the thermal expansion coefficient α , the wall thickness of the profile section t , the bending radius R , the distance from the bending force axis to the farthest point on the cross section y max , the section moment of inertia of the profile I , the distance between the moment action position and the shear center e , and the torque generated by the shear force causing the profile to twist is obtainedM T ; Heating area acquisition module, used to obtain the heating area of ​​the profile section A ; A matching relationship establishment module is used for thermal torque caused by local heating area and according to the torque M T , the elastic modulus E , the thermal expansion coefficient α and the heating area A , establish the heating temperature required to correct the distortion T The distance from the center of the heating area to the centroid d matching relationship; The heating parameter combination determination module is used to determine the required heating temperature based on the matching relationship and the cross-sectional size and centroid position of the profile. T and distance d Heating parameter combination; The real-time correction module implements a differential temperature assisted free bending forming process according to the combination of heating parameters to achieve real-time correction of profile distortion.

[0014] The above technical solution of the present invention has the following advantages over the prior art: The present invention describes a method and system for correcting distortion during the free-bending forming of difficult-to-deform, non-enclosed profiles. This method, through differential temperature-assisted control, effectively suppresses distortion during the free-bending forming process, improving forming quality. Utilizing localized induction heating technology, a specific temperature distribution is created across the profile's cross-section, softening localized regions and reducing the flow stress required for deformation. By utilizing the differences in stress distribution between these regions, the shear center is shifted toward the force axis, thereby offsetting the additional shear force generated by the non-enclosed nature of the profile's cross-section. This achieves a balanced bending state for the non-enclosed profile and suppresses distortion defects.

[0015] The present invention realizes real-time correction of distortion by precisely controlling the temperature and position of local heating, thus avoiding the problems of low efficiency and surface damage caused by the traditional post-correction process.

[0016] The present invention realizes real-time correction of distortion by precisely controlling the temperature and position of local heating, thus avoiding the problems of low efficiency and surface damage caused by the traditional post-correction process.

[0017] The present invention is particularly suitable for the precision forming of high-strength steel non-closed profile components in the fields of aerospace, new energy vehicles, etc., and has important engineering application value and significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0019] Figure 1 It is a schematic diagram of a temperature difference assisted free bending forming device for non-closed profiles.

[0020] Figure 2 It is a schematic diagram of a U-shaped non-closed profile curved member.

[0021] Figure 3 It is a schematic diagram of the shear center and centroid position of the profile section.

[0022] Figure 4 It is a schematic diagram of the temperature distribution of the profile cross section under the auxiliary effect of differential temperature.

[0023] Figure 5 It is a schematic diagram of the distortion of the profile during the bending process.

[0024] Figure 6 This is a schematic diagram of the distortion correction effect assisted by differential temperature. DETAILED DESCRIPTION

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0026] In the present invention, if directions (up, down, left, right, front and back) are described, it is only for the convenience of describing the technical solution of the present invention, and does not indicate or imply that the technical features referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, it cannot be understood as a limitation of the present invention.

[0027] In the present invention, "several" means one or more, "multiple" means more than two, "greater than," "less than," "exceeds," etc. are understood to exclude the number itself; "above," "below," "within," etc. are understood to include the number itself. In the description of the present invention, the use of "first" or "second" is solely for the purpose of distinguishing technical features and is not to be construed as indicating or implying relative importance, implicitly specifying the number of the indicated technical features, or implicitly specifying the order of the indicated technical features.

[0028] In the present invention, unless otherwise expressly defined, terms such as "disposed," "installed," and "connected" should be interpreted broadly. For example, they may refer to direct connection or indirect connection through an intermediate medium; fixed connection or detachable connection or integral molding; mechanical connection or electrical connection or mutual communication; and internal connection between two components or interaction between two components. Those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0029] Example 1 Reference Figure 1 As shown, a method for correcting distortion of a non-enclosed profile that is difficult to deform by free bending in this embodiment includes: Step 1: Measure the elastic modulus of the profile through mechanical properties test E , yield strength σ y , thermal expansion coefficient α ; Step 2: Get the wall thickness of the profile section t , bending radius R , centroid position coordinates, distance from the bending force axis to the farthest point on the cross section y max ; Step 3: Calculate the moment of inertia of the profile section I and shear center position; Step 4: Calculate the distance between the moment action position and the shear center e ; Step 5: According to the elastic modulus E , the yield strength σ y , the thermal expansion coefficient α , the wall thickness of the profile section t , the bending radius R , the distance from the bending force axis to the farthest point on the cross section y max , the section moment of inertia of the profile I , the distance between the moment action position and the shear center e , calculate the torque caused by the shear force causing the profile to twist M T : , Step 6: Install an open induction coil between the bending die and the guide roller of the six-axis free bending and torsion equipment. The induction coil is set near the shear center of the profile section. After installation, the distance between the induction coil and the different surfaces of the profile must be consistent to ensure that the heating position is evenly heated. The heating area of ​​the profile section is A ; Step 7: Calculate the thermal torque caused by the local heating area M th : , Where ΔT is the local heating temperature.

[0030] Step 8: Thermal torque caused by local heating area M th The relationship can be based on the torque M T , the elastic modulus E , the thermal expansion coefficient α and the heating area A , establish the heating temperature required to correct the distortion T The distance from the center of the heating area to the centroid d The matching relationship: , Step 9: Based on the matching relationship, and according to the cross-sectional dimensions and centroid position of the profile, determine the required heating temperature T and distance d Heating parameter combination, where the distance d The minimum value is 0, the distance d The maximum value is the distance from the edge of the profile section to the centroid; Step 10: Based on the determined heating parameter combination, a differential temperature assisted free bending forming process is implemented to achieve real-time correction of profile distortion.

[0031] like Figure 1 As shown, this embodiment of the differential temperature-assisted distortion correction method for free bending of difficult-to-deform, non-enclosed profiles utilizes an existing six-axis free bending and torsion system, combined with an open-type induction heating coil, to construct a differential temperature-assisted free bending and torsion experimental device. An external control cabinet and temperature controller allow precise adjustment of parameters such as local heating power, voltage, and frequency during the forming process. Furthermore, inputting the displacements of the X / Y / Z axes and the rotation angles of the A / B / C axes into the software control system allows for free bending and torsion experiments on non-enclosed profiles under differential temperature conditions.

[0032] The above method overcomes the serious distortion problem caused by the misalignment of the shear center and the centroid during the free bending forming of non-closed profiles made of difficult-to-deform materials at room temperature. By utilizing local induction heating technology, a specific temperature distribution is formed on the profile cross section, causing the local area of ​​the cross section to soften and reducing the flow stress required for deformation there. By varying the stress distribution between different regions, the shear center position is shifted toward the force axis, thereby offsetting the additional shear force generated by the non-closed nature of the profile cross section, achieving a balanced bending state for the non-closed profile, and suppressing the occurrence of distortion defects. This method is simple and feasible, with high forming quality, and can effectively correct distortion defects during the bending process of non-closed profiles that are difficult to deform. It has important engineering application value and significant economic benefits in high-end manufacturing fields such as aerospace and new energy vehicles.

[0033] Example 2 This embodiment provides a method for correcting distortion of a non-enclosed profile by free bending. Figure 2 Taking the high-strength steel U-shaped non-closed profile shown above as an example, the specific implementation steps are as follows: Step 1: Measure the elastic modulus of the profile through mechanical properties test E =210GPa, yield strength σ y =780MPa, thermal expansion coefficient α =1.2×10 -5 / ℃; Step 2: Get the wall thickness of the profile section t =3mm, bending radius R =300mm, centroid position coordinates ( x 0, y 0)=(13.27mm, 12.5mm), the distance from the bending force axis to the farthest point on the cross section y max =10mm; Step 3: Calculate the moment of inertia of the profile section using 3D modeling software I =5072.8mm 4 , and determine the coordinates of the shear center position ( x s , y s )=(22.5mm, 12.5mm), such as Figure 3 As shown; Step 4: The bending equipment applies force at the center of the profile section, and calculates the distance between the moment action position and the shear center. e =12.5mm; Step 5: Based on a bending radius of 300mm, calculate the torque generated by the shear force causing the profile to twist: , Step 6: If Figure 4 As shown, an open induction coil is installed in the deformation zone of the six-axis free bending and torsion equipment. The induction coil is set near the shear center of the profile section; the covered profile section area A is the U-shaped closed side, the covering length is 8mm, and the area A is 105mm 2 ; Step 7: Determine the distance between the center and the centroid of the heating area based on the cross-sectional dimensions and centroid position of the profile d =2.73mm; Step 8: Establish a matching relationship based on the thermal torque balance principle caused by torque and local heating: , Step 9: Install an open induction heating coil on the six-axis free bending and twisting equipment, set the heating power and corresponding frequency to meet the heating temperature requirement of T=679.78℃, and set the X / Y / Z axis displacement and A / B / C axis rotation angle of the six-axis free bending and twisting equipment according to the conventional bending process parameters.

[0034] The results show that compared with the traditional bending method without the differential temperature assistance technology, the method of the present invention effectively suppresses the distortion, such as Figure 5 and 6 shown.

[0035] It can be seen from the above embodiments that the differential temperature assisted free bending distortion correction method for difficult-to-deform non-closed profiles proposed in the present invention can effectively suppress the distortion deformation of high-strength steel non-closed profiles during the bending forming process, is suitable for non-closed profiles of various cross-sectional shapes, and has strong process adaptability and good correction effect.

[0036] Example 3 Based on the same inventive concept, this embodiment provides a system for correcting the distortion of a non-closed profile that is difficult to deform by free bending. The principle of solving the problem is similar to the method for correcting the distortion of a non-closed profile that is difficult to deform by free bending, and the repeated parts will not be repeated.

[0037] This embodiment provides a system for free bending, forming and distortion correction of non-enclosed profiles that are difficult to deform, including: Profile thermodynamic parameter acquisition module, used to obtain the elastic modulus of the profile E , yield strength σ y , thermal expansion coefficient α , wall thickness of profile section t , bending radius R , Distance from the bending force axis to the farthest point on the cross section y max , profile section moment of inertia I, the distance between the moment action position and the shear center e ; The torque acquisition module is used to obtain the torque generated by the distortion of the profile due to the shear force according to the elastic modulus. E , the yield strength σ y , the thermal expansion coefficient α , the wall thickness of the profile section t , the bending radius R , the distance from the bending force axis to the farthest point on the cross section y max , the section moment of inertia of the profile I , the distance between the moment action position and the shear center e , and the torque generated by the shear force causing the profile to twist is obtained M T ; Heating area acquisition module, used to obtain the heating area of ​​the profile section A ; A matching relationship establishment module is used for thermal torque caused by local heating area and according to the torque M T , the elastic modulus E , the thermal expansion coefficient α and the heating area A , establish the heating temperature required to correct the distortion T The distance from the center of the heating area to the centroid d matching relationship; The heating parameter combination determination module is used to determine the required heating temperature based on the matching relationship and the cross-sectional size and centroid position of the profile. T and distance d Heating parameter combination; The real-time correction module implements a differential temperature assisted free bending forming process according to the combination of heating parameters to achieve real-time correction of profile distortion.

[0038] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0039] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0040] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0041] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0042] Finally, it should be noted that the above specific implementation methods are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the present invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for correcting distortion of a non-closed profile that is difficult to deform by free bending, characterized in that: include: Get the elastic modulus of the profile E , yield strength σ y , thermal expansion coefficient α , wall thickness of profile section t , bending radius R , Distance from the bending force axis to the farthest point on the cross section y max , profile section moment of inertia I , the distance between the moment action position and the shear center e ; According to the elastic modulus E , the yield strength σ y , the thermal expansion coefficient α , the wall thickness of the profile section t , the bending radius R , the distance from the bending force axis to the farthest point on the cross section y max , the section moment of inertia of the profile I , the distance between the moment action position and the shear center e , and the torque generated by the shear force causing the profile to twist is obtained M T ; Get the heating area of ​​the profile cross section A ; Based on the thermal torque caused by the local heating area, and according to the torque M T , the elastic modulus E , the thermal expansion coefficient α and the heating area A , establish the heating temperature required to correct the distortion T The distance from the center of the heating area to the centroid d matching relationship; Based on the matching relationship, and according to the cross-sectional dimensions and centroid position of the profile, the required heating temperature is determined. T and distance d Heating parameter combination; According to the heating parameter combination, a differential temperature assisted free bending forming process is implemented to achieve real-time correction of profile distortion.

2. A method for correcting distortion of a non-closed profile that is difficult to deform by free bending according to claim 1, characterized in that: Torque caused by shear force causing profile distortion M T The calculation formula is: 。 3. The method for correcting distortion of a non-closed profile that is difficult to deform by free bending according to claim 1, characterized in that: Thermal torque caused by local heating area M th The calculation formula is: ， Where ΔT is the local heating temperature.

4. The method for correcting distortion of a non-closed profile that is difficult to deform by free bending according to claim 1, characterized in that: Establish the heating temperature required to correct distortion T The distance from the center of the heating area to the centroid d The matching relationship is: 。 5. The method for correcting distortion of a non-closed profile that is difficult to deform by free bending according to claim 1, characterized in that: Determine the required heating temperature based on the profile cross-section size and centroid position T and distance d The heating parameter combination includes: Determine the distance based on the profile cross-section size and centroid position d When the value range of d The minimum value is 0, the distance d The maximum value is the distance from the edge of the profile section to the centroid.

6. The method for correcting distortion of a non-closed profile that is difficult to deform by free bending according to claim 1, characterized in that: The temperature difference assisted free bending forming process is implemented on a six-axis free bending and torsion equipment.

7. The method for correcting distortion of a non-closed profile that is difficult to deform by free bending according to claim 1, characterized in that: Also includes: An open induction coil is installed between the bending die and the guide roller of the six-axis free bending and torsion equipment. The open induction coil is set near the shear center of the profile section and the distance between the open induction coil and the different surfaces of the profile is consistent after installation.

8. A system for free bending and twist correction of non-closed profiles that are difficult to deform, characterized by: include: Profile thermodynamic parameter acquisition module, used to obtain the elastic modulus of the profile E , yield strength σ y , thermal expansion coefficient α , wall thickness of profile section t , bending radius R , Distance from the bending force axis to the farthest point on the cross section y max , profile section moment of inertia I , the distance between the moment action position and the shear center e ; The torque acquisition module is used to obtain the torque generated by the distortion of the profile due to the shear force according to the elastic modulus. E , the yield strength σ y , the thermal expansion coefficient α , the wall thickness of the profile section t , the bending radius R , the distance from the bending force axis to the farthest point on the cross section y max , the section moment of inertia of the profile I , the distance between the moment action position and the shear center e , and the torque generated by the shear force causing the profile to twist is obtained M T ; Heating area acquisition module, used to obtain the heating area of ​​the profile section A ; A matching relationship establishment module is used for thermal torque caused by local heating area and according to the torque M T , the elastic modulus E , the thermal expansion coefficient α and the heating area A , establish the heating temperature required to correct the distortion T The distance from the center of the heating area to the centroid d matching relationship; The heating parameter combination determination module is used to determine the required heating temperature based on the matching relationship and the cross-sectional size and centroid position of the profile. T and distance d Heating parameter combination; The real-time correction module implements a differential temperature assisted free bending forming process according to the combination of heating parameters to achieve real-time correction of profile distortion.

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