Method for inhibiting springback of aluminum profile during bending and aluminum profile

Abstract

The present application relates to a kind of inhibiting aluminum profile bending springback method and aluminum profile.The present application aluminum profile bending forming springback control method includes the following steps: according to the mechanical properties of the profile to be bent, pre-aging is carried out to aluminum profile before bending forming;According to the hardness of the profile after pre-aging, pre-stretching is carried out to aluminum profile;Bending forming is carried out to aluminum profile after pre-aging and pre-stretching.The material characteristics of aluminum alloy is different from steel material, and the springback amount after bending forming unloading is much larger than steel material, so the bending springback law of steel material is not applicable to aluminum alloy.The present application can effectively reduce the influence of springback by suitable pre-aging and pre-stretching to aluminum profile before bending forming, realize the high-precision control of bending forming, and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to the field of bending forming technology, and in particular to a method for suppressing the springback of aluminum profiles and an aluminum profile. Background Technology

[0002] Bending workpieces made of aluminum alloy profiles possess a series of excellent properties such as light weight, high rigidity, and structural stability, and are widely used in construction, automotive, aerospace, and other fields. However, bending is an elasto-plastic forming process; after the load is removed, the elastic deformation recovers while the plastic deformation is retained. This causes a significant deviation between the actual dimensions of the formed workpiece and the predetermined values, a phenomenon known as springback. Springback significantly reduces product yield and production efficiency, while also increasing production costs.

[0003] Aluminum alloys exhibit different material properties from steel, displaying significant anisotropy and having an elastic modulus only one-third that of steel. Therefore, the springback after bending and unloading is far greater than that of steel, rendering the well-established springback rules for steel inapplicable to aluminum alloys. Currently, conventional control methods for aluminum alloy springback include over-bending, multiple bending, core-reinforced bending, and hot bending. However, over-bending requires extensive repetitive experiments to accumulate experience, while methods like multiple bending, core-reinforced bending, and hot bending are complex and involve numerous steps, resulting in low efficiency. Chinese patent CN 116689568 A, "Method for Controlling Springback of Aluminum Alloy Tubes During Bending," proposes a method for controlling springback during bending of aluminum alloys. However, this method is only applicable to aluminum profiles subjected to long-term natural aging and requires fitting compensation angle data using complex formulas, lacking universality and convenience.

[0004] In recent years, with the advancement of science and technology, many new bending forming processes and equipment have emerged, such as flexible bending, three-dimensional multi-point bending, arc pretreatment bending, and laser-assisted bending. These new processes, due to their unique structure and principles, can effectively control springback and improve product precision. However, most of these new processes involve numerous operating steps and complex production processes, requiring a high level of expertise from the user. Furthermore, the equipment required for these new bending processes is precise, complex, expensive, has a single application, and consumes a lot of energy. These factors mean that most new bending processes can only be used in laboratories for research and cannot be applied to actual production.

[0005] Therefore, it is necessary to propose a rebound control method that can accurately control rebound and has the characteristics of being simple, efficient, and widely applicable. Summary of the Invention

[0006] The technical problem this invention aims to solve is the accurate and efficient control of springback. Due to the complexity of springback, conventional methods such as over-bending and multiple bending are not accurate enough in controlling springback, and many new bending processes cannot yet be applied to actual production. Therefore, the primary challenge in this field is to achieve high-precision control of aluminum alloy bending forming.

[0007] This invention is achieved through the following technical solution:

[0008] The first objective of this invention is to provide a method for suppressing the bending springback of aluminum profiles, comprising the following steps:

[0009] S1. Based on the mechanical property parameters of the aluminum profile to be bent, perform pre-aging treatment;

[0010] S2. Pre-stretch the aluminum profile according to the mechanical property parameters of the pre-aged aluminum profile;

[0011] S3. The aluminum profiles that have undergone pre-aging and pre-stretching are bent into shape.

[0012] In one embodiment of the present invention, in step S1, the pre-aging temperature is 80℃-150℃; the pre-aging time is 0.5h-4h.

[0013] In one embodiment of the present invention, in step S1, the mechanical property is microhardness; the pre-aging temperature is determined according to the formula T = 0.007S. 2 The result is calculated as -2S+230 and rounded to the nearest integer.

[0014] Where T is the pre-aging temperature and S is the microhardness of the aluminum profile; when the pre-aging temperature calculated according to the formula is <80℃, take 80℃; when the pre-aging temperature calculated according to the formula is >150℃, take 150℃.

[0015] In one embodiment of the present invention, in step S1, the mechanical property is microhardness; the pre-aging time is calculated according to the formula t = 1.8 × 10⁻⁶. -4 S 2 The result is calculated as -0.07S+7.2, and rounded to one decimal place.

[0016] Where S is the microhardness of the aluminum profile and t is the pre-aging time; when the pre-aging time calculated according to the formula is <0.5h, take 0.5h; when the pre-aging time calculated according to the formula is >0.5h, take 4h.

[0017] The microhardness can be expressed by other performance parameters (such as yield strength, macrohardness, etc.), and must be converted to the corresponding microhardness value before use.

[0018] In one embodiment of the present invention, in step S2, the pre-stretching specifically involves pre-stretching the aluminum profile by 0.2%-1% deformation along the extrusion direction.

[0019] In one embodiment of the present invention, the deformation amount is the theoretical loading strain of the aluminum profile before pre-stretching and unloading.

[0020] In one embodiment of the present invention, in step S2, the mechanical property is the microhardness of the aluminum profile after pre-stretching.

[0021] The microhardness can be expressed by other performance parameters (such as yield strength, macrohardness, etc.), and must be converted to the corresponding microhardness value before use.

[0022] In one embodiment of the present invention, in step S2, the pre-stretching is performed according to the formula

[0023] Δ=(1.8×10 -7 S 2 -9×10 -5 The result is calculated as S + 0.013) × 100%.

[0024] Where Δ is the pre-stretch amount, S is the microhardness of the aluminum profile after pre-aging, and the calculation result is rounded to one decimal place. When the pre-stretch amount calculated according to the formula is <0.2%, it is taken as 0.2%; when the pre-stretch amount calculated according to the formula is >1%, it is taken as 1%.

[0025] In one embodiment of the present invention, in step S3, the bending forming method is selected from one or more of roll bending, stretch bending, pressure bending and push bending.

[0026] The second objective of this invention is to provide an aluminum profile manufactured using the method for suppressing bending springback of aluminum profiles as described in any one of claims 1-8.

[0027] A third objective of this invention is to provide the application of the aforementioned aluminum profiles in the fields of construction, automotive, or aerospace.

[0028] The technical solution of the present invention has the following advantages compared with the prior art:

[0029] 1. This invention provides a method for suppressing the springback of aluminum profiles during bending and an aluminum profile itself. The main factors affecting the springback of aluminum profiles include mechanical properties and residual stress. During the production process, aluminum profiles are affected by factors such as extrusion processes, cooling methods, and straightening amounts, resulting in uneven mechanical properties and unavoidable residual stress. This makes the springback behavior of aluminum profiles during subsequent bending and forming processes more difficult to predict and control, significantly reducing product precision and yield. Extruded aluminum profiles typically remain in a supersaturated solid solution state after hot extrusion, with strengthening phase atoms continuously precipitating. During subsequent natural placement, mechanical properties and residual stress continue to change, which is detrimental to the control of springback during subsequent bending. The springback control method for aluminum profile bending of this invention involves pre-aging the profile at a lower temperature and for a shorter time before bending. After low-temperature short-time pre-aging, the mechanical properties of the material do not change significantly and subsequently remain stable. Furthermore, residual stress is effectively released during pre-aging. All of this is beneficial for the subsequent control of bending springback.

[0030] 2. The aluminum profile bending springback control method of the present invention involves pre-stretching the profile to be bent after pre-aging with a small deformation. Pre-stretching with a small deformation makes the overall performance of the aluminum profile more uniform, avoiding uncontrollable springback caused by uneven performance in different sections of the profile. Furthermore, pre-stretching with a small deformation can effectively regulate residual stress, thereby reducing springback. For residual compressive stress, the tensile stress applied by pre-stretching can effectively release residual compressive stress. Residual compressive stress is generally considered detrimental to springback. During bending, the upper surface of the profile is subjected to compressive stress, which superimposes with the existing residual compressive stress, increasing the displacement of the profile in that direction and ultimately leading to increased springback. Therefore, pre-stretching with a small deformation can effectively reduce springback. Regarding residual tensile stress, a small amount of residual tensile stress will partially offset the compressive stress during the profile's downward pressing process, reducing the displacement of the profile in that direction and reducing the occurrence of springback. However, excessive residual tensile stress can severely reduce the formability and bendability of the material. Therefore, the aluminum profile was pre-aged before pre-stretching to greatly reduce the residual stress of the material, which also avoids the generation of excessive residual tensile stress in the future.

[0031] 3. The bending process springback control method provided by this invention is simple and has a reasonable process compared with the prior art. It can effectively reduce the springback amount, improve the forming accuracy and yield of aluminum profiles, and is suitable for industrial production. Detailed Implementation

[0032] The present invention will be further described below with reference to specific embodiments, so that those skilled in the art can better understand and implement the present invention, but the embodiments are not intended to limit the present invention.

[0033] Example 1

[0034] This embodiment provides a method for suppressing the bending springback of aluminum profiles, and the specific steps are as follows:

[0035] (1) An aluminum alloy "U"-shaped tube with a cross-sectional size of 45mm x 45mm and a wall thickness of 2.5mm was selected as the experimental material. Its mechanical properties were measured. Taking microhardness (HV) as an example, the average microhardness of the profile was 66HV and the standard deviation was 0.8.

[0036] (2) According to the formula T = 0.007S 2 The pre-aging temperature is calculated using the formula t = 1.8 × 10⁻²S + 230°C. -4 S 2 -0.07S+7.2 Calculate the pre-aging time. Based on the calculation results, the aluminum profile is subjected to pre-aging treatment at a temperature of 128℃ for 3.4 hours.

[0037] (3) The microhardness of the aluminum profile after pre-aging was measured to be 78 HV. According to the formula Δ=(1.8×10⁻⁶), the microhardness is... -7 S 2 -9×10 - 5 Calculate the pre-stretch amount using (S+0.013)×100%, and pre-stretch the aluminum profile by 0.7% deformation based on the calculation results.

[0038] (4) Perform three-roll bending on the pre-stretched aluminum profile. The target bending outer radius is 300mm and the target bending center angle is 45°. The upper roller radius of the die is 67.5mm, the two lower roller radii are both 80mm, and the distance between the two lower roller shafts is 330mm.

[0039] (5) The springback of the curvature radius and the springback of the angle of the aluminum profile after bending by three rollers were measured to be 93.38 mm and 1.75°, respectively.

[0040] Example 2

[0041] This embodiment provides a method for suppressing the bending springback of aluminum profiles, and the specific steps are as follows:

[0042] (1) An aluminum alloy "U"-shaped tube with a cross-sectional size of 45mm x 45mm and a wall thickness of 2.5mm was selected as the experimental material. Its mechanical properties were measured. Taking microhardness (HV) as an example, the average microhardness of the profile was 106HV and the standard deviation was 1.8.

[0043] (2) According to the formula T = 0.007S 2 The pre-aging temperature is calculated using the formula t = 1.8 × 10⁻²S + 230°C. -4 S 2The pre-aging time was calculated using -0.07S+7.2. Based on the calculation results, the aluminum profile underwent a pre-aging treatment at 97℃ for 1.8 hours.

[0044] (3) The microhardness of the aluminum profile after pre-aging was measured to be 118 HV. According to the formula Δ=(1.8×10⁻⁶), the microhardness is... -7 S 2 -9×10 -5 Calculate the pre-stretch amount using (S+0.013)×100%, and pre-stretch the aluminum profile by 0.48% of the deformation based on the calculation results.

[0045] (4) Perform three-roll bending on the pre-stretched aluminum profile. The target bending outer radius is 300mm and the target bending center angle is 45°. The upper roller radius of the die is 67.5mm, the two lower roller radii are both 80mm, and the distance between the two lower roller shafts is 330mm.

[0046] (5) The springback of the radius of curvature and the springback of the angle of the aluminum profile after bending by three rollers were measured to be 102.25 mm and 2.92°, respectively.

[0047] Example 3

[0048] This embodiment provides a method for suppressing the bending springback of aluminum profiles, and the specific steps are as follows:

[0049] (1) An aluminum alloy "U"-shaped tube with a cross-sectional size of 45mm x 45mm and a wall thickness of 2.5mm was selected as the experimental material. Its mechanical properties were measured. Taking microhardness (HV) as an example, the average microhardness of the profile was 124HV and the standard deviation was 1.6.

[0050] (2) According to the formula T = 0.007S 2 The pre-aging temperature is calculated using the formula t = 1.8 × 10⁻²S + 230°C. -4 S 2 The pre-aging time was calculated using -0.07S+7.2. Based on the calculation results, the aluminum profile underwent a pre-aging treatment at 90℃ for 1.3 hours.

[0051] (3) The microhardness of the aluminum profile after pre-aging was measured to be 139 HV. According to the formula Δ=(1.8×10⁻⁶), the microhardness is... -7 S 2 -9×10 -5 Calculate the pre-stretch amount using (S+0.013)×100%, and pre-stretch the aluminum profile by 0.40% of the deformation amount based on the calculation results.

[0052] (4) Perform three-roll bending on the pre-stretched aluminum profile. The target bending outer radius is 300mm and the target bending center angle is 45°. The upper roller radius of the die is 67.5mm, the two lower roller radii are both 80mm, and the distance between the two lower roller shafts is 330mm.

[0053] (5) The actual outer radius of curvature and the bending center angle of the aluminum profile after three-roll bending were measured to be 119.87 mm and 4.67°, respectively.

[0054] Comparative Example 1

[0055] This comparative example uses the same aluminum profile, bending process, and target bending parameters as described in Example 2, except that it does not undergo pre-aging and pre-stretching treatment.

[0056] Comparative Example 2

[0057] This comparative example uses the same aluminum profile, bending process, and target bending parameters as Example 2, except that it undergoes only the same pre-aging treatment and no pre-stretching treatment.

[0058] Comparative Example 3

[0059] This comparative example uses the same aluminum profile, bending process, and target bending parameters as Example 2, except that it undergoes only the same pre-stretching treatment and does not undergo pre-aging treatment.

[0060] Comparative Example 4

[0061] This comparative example uses the same aluminum profile, bending process, and target bending parameters as in Example 2, except that it undergoes an 8-hour pre-aging treatment followed by a 2% pre-stretching treatment.

[0062] The comparison results between Examples 1-3 and Comparative Examples 1-4 are shown in Table 1:

[0063] Table 1 Comparison Results

[0064]

[0065]

[0066] As shown in Table 1, Comparative Example 1, which involves direct bending without pre-aging and pre-stretching, exhibits a large springback radius. Examples 1, 2, and 3, using three pipes with different microhardnesses, all showed a significant reduction in springback radius after adopting the pre-aging and pre-stretching regimes within the scope of this invention. Comparative Examples 2, 3, and 4, employing only the pre-aging regime of this invention, only the pre-stretching regime, and aging and pre-stretching regimes beyond those of this invention, respectively, also showed a reduction in springback radius to some extent, but the effect was not as good as that in the examples.

[0067] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for suppressing the springback of aluminum profiles during bending, characterized in that, Includes the following steps: S1. Based on the mechanical property parameters of the aluminum profile to be bent, perform pre-aging treatment; S2. Pre-stretch the aluminum profile according to the mechanical property parameters of the pre-aged aluminum profile; S3. Bend and shape the aluminum profile after pre-aging and pre-stretching; In step S1, the mechanical property is microhardness; the pre-aging temperature is determined according to the formula... The calculated result is rounded to the nearest integer. Where T is the pre-aging temperature, and S is the microhardness HV of the aluminum profile; when the pre-aging temperature calculated according to the formula is <80℃, take 80℃; when the pre-aging temperature calculated according to the formula is >150℃, take 150℃. In step S1, the mechanical property is microhardness; the pre-aging time is based on the formula... The calculation is performed, and the result is rounded to one decimal place. Where S is the microhardness of the aluminum profile and t is the pre-aging time; when the pre-aging time calculated according to the formula is <0.5h, take 0.5h; when the pre-aging time calculated according to the formula is >4h, take 4h. In step S2, the pre-stretching specifically involves pre-stretching the aluminum profile along the extrusion direction by 0.2%-1% of the deformation. In step S2, the pre-stretch amount is determined according to the formula... Calculated; Where Δ is the pre-stretch amount, S is the microhardness of the aluminum profile after pre-aging, and the calculation result is rounded to one decimal place. When the pre-stretch amount calculated according to the formula is <0.2%, it is taken as 0.2%; when the pre-stretch amount calculated according to the formula is >1%, it is taken as 1%.

2. The method for suppressing the bending springback of aluminum profiles according to claim 1, characterized in that, The deformation amount is the theoretical loading strain of the aluminum profile before pre-stretching and unloading.

3. The method for suppressing the bending springback of aluminum profiles according to claim 1, characterized in that, In step S3, the bending forming method is selected from one or more of roll bending, stretch bending, pressure bending, and push bending.

4. An aluminum profile, characterized in that, It is manufactured using the method for suppressing the bending springback of aluminum profiles as described in any one of claims 1-3.

5. The application of the aluminum profile according to claim 4 in the fields of construction, automobile or aerospace.

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