Anti-deformation vertical quenching method for ultra-long thin-wall aluminum alloy profile

Abstract

The invention relates to the technical field of aluminum alloy profile processing, and particularly discloses a super-long thin-wall aluminum alloy profile anti-deformation vertical quenching method which comprises the following steps: S1, determining mechanical parameters, and obtaining the maximum equivalent buckling axial pressure P of a to-be-quenched aluminum alloy profile; s2, determining the maximum constraint length of a single section: further calculating the maximum allowable length of the single constraint section of the to-be-quenched aluminum alloy section; S3, determining a minimum constraint section; S4, carrying out solid solution quenching: equally dividing the to-be-quenched aluminum alloy section according to the minimum constraint section N, and carrying out section marking in the radial direction from the bottom to the top, the adjacent segment marking positions and the top of the sectional material are restrained and fixed; and after fixation, solid solution quenching is carried out, and after solid solution quenching is completed, the profile is taken out. The vertical quenching device is suitable for vertical quenching requirements of various ultra-long thin-wall aluminum alloy profiles with complex sections, and the profiles are effectively prevented from being deformed in the vertical quenching process.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy profile processing technology, specifically to a vertical quenching method for preventing deformation of ultra-long, thin-walled aluminum alloy profiles. Background Technology

[0002] High-strength, thin-walled aluminum alloy profiles are core load-bearing components for aircraft and other aerospace vehicles, characterized by high strength, complex cross-sectional shapes, thin walls, and extremely long lengths. During heat treatment strengthening, these profiles typically undergo vertical quenching to achieve supersaturated solid solution fixation. However, during this process, uneven cooling due to the complex cross-section of the profile generates enormous asymmetric thermal stresses. When these thermal stresses exceed the material's yield strength or critical buckling stress at high temperatures, the profile will undergo unstable deformation, manifesting as overall S-shaped bending, localized warping, or multi-wave undulating deformation. This buckling problem is particularly pronounced for ultra-long profiles exceeding 8 meters in length, where the length-to-diameter ratio is extremely high.

[0003] Currently, the industry's commonly used anti-deformation measures largely rely on accumulated experience, such as performing process reinforcement on localized areas of the profile, or using a rigid bottom-fixing method during quenching. (For example, the publication number is...) Chinese patent CN218989308U discloses a special fixing ring for solution quenching of aluminum alloy profiles. This fixing ring structure consists of four concentric rings (ring 1, ring 2, ring 3, and ring 4). This ring structure is used to fix the aluminum alloy profile before it is fed into the quenching furnace for quenching, thus preventing severe bending or twisting of the aluminum alloy profile after quenching. Similarly, Chinese patent CN108441793B discloses a heat treatment method for strengthening and shaping aluminum alloys and aluminum alloy profiles for aerospace applications. This method uses an aluminum alloy forced forming device to fix the extruded profile into a linear shape before quenching. However, these methods lack quantitative analysis of the transient temperature field, stress field evolution, and instability mechanism of the profile during quenching. They cannot scientifically determine the optimal number and spatial layout of constraint points, nor can they optimize the stiffness and form of the constraints. As a result, insufficient constraints can lead to profile instability and distortion, while excessive constraints may introduce new restraint stresses, worsening the internal stress distribution of the profile, or making the tooling overly complex and severely reducing operational efficiency. Therefore, improvements are urgently needed. Summary of the Invention

[0004] One of the technical problems solved by this invention is to provide a vertical quenching method for preventing deformation of ultra-long thin-walled aluminum alloy profiles, so as to solve the deformation problem of vertical quenching of ultra-long thin-walled high-strength aluminum alloy profiles.

[0005] The technical problem solved by this invention is achieved by the following technical solution: The application discloses a vertical quenching method for preventing deformation of an ultra-long thin-walled aluminum alloy profile, and comprises the following steps. S1, determining mechanical parameters: obtaining the maximum equivalent buckling axial pressure P of the aluminum alloy profile to be quenched, and the calculation formula is as follows:

[0006] Wherein, k is a comprehensive correction coefficient, ranging from 1 to 1.5; alpha is the thermal expansion coefficient of the aluminum alloy profile to be quenched; delta T is the maximum instantaneous temperature difference before and after quenching of the profile to be quenched; E is the material elastic modulus of the aluminum alloy profile to be quenched at a high quenching temperature. S2, determining the maximum allowable length of a single segment: further calculating the maximum allowable length of a single constraint segment of the aluminum alloy profile to be quenched , and the calculation formula is as follows:

[0007] Wherein, A is the cross-sectional area of the aluminum alloy profile to be quenched, n is a safety factor, and n ranges from 1 to 1.2; I is the minimum moment of inertia of the cross section of the aluminum alloy profile to be quenched. S3, determining the minimum constraint segmentation: according to the total length L of the aluminum alloy profile to be quenched, the minimum constraint segmentation N required is calculated, N is an integer obtained by rounding up the calculation result, and the calculation formula is as follows:

[0008] S4, solution quenching: the aluminum alloy profile to be quenched is evenly divided according to the minimum constraint segmentation N, and is segmented and marked along the radial direction from the bottom upwards; the adjacent segment marks and the top of the profile are fixedly constrained; after being fixedly constrained, solution quenching is performed, and after the solution quenching is completed, the profile can be taken out.

[0009] Further, the length of the aluminum alloy profile to be quenched is greater than or equal to 8 meters, and the aluminum alloy profile to be quenched is fixedly constrained by the constraint device.

[0010] Further, the assembly gap between the constraint device and the profile to be quenched is 0.1-1mm.

[0011] Further, the constraint device comprises a main frame and a plurality of constraint units arranged on the main frame; the constraint unit comprises a supporting plate, a constraint pipe arranged vertically on the supporting plate, and an inner lining sleeve arranged in the constraint pipe; the outer wall of the inner lining sleeve is matched with the constraint pipe, and the inner lining sleeve is provided with a constraint hole allowing the aluminum alloy profile to be quenched to pass through and matched with the outer contour of the aluminum alloy profile to be quenched.

[0012] In the application, the inner lining sleeve with the constraint hole matched with the aluminum alloy profile with different cross sections can be selected according to the needs of different profiles, so that targeted constraint of different aluminum alloy profiles can be realized.

[0013] Further, a limiting step is arranged at the bottom of the constraint tube, and the inner lining is arranged on the limiting step to realize quick assembly and supporting positioning.

[0014] Further, the inner lining comprises two independent and symmetrically arranged inner lining blocks, so that the inner lining blocks can be quickly assembled and clamped with the profile, and the disassembly is also very convenient.

[0015] Further, the inner lining blocks are aluminum alloy inner lining blocks, and the inner lining blocks are replaceable to adapt to different cross-sectional shapes of aluminum alloy profiles with similar overall dimensions.

[0016] In the present application, an assembly gap is provided between the constraint device and the profile to be quenched, so that the inner lining can be smoothly assembled into the constraint tube in a cold state, and an interference fit is formed between the inner lining and the aluminum alloy profile in a hot state, thereby playing a role of constraining the profile. Preferably, the assembly gap between the inner lining and the profile to be quenched is 0.1-1 mm.

[0017] Further, a boron nitride coating is arranged on the surface of the inner lining block, and the arrangement of the coating can better facilitate the taking out of the profile.

[0018] Further, the mounting height of the constraint unit on the main frame is adjustable.

[0019] Further, the main frame comprises a stand column, and the supporting plate is connected with the stand column through a clamp.

[0020] Further, a hanger and a limiting strip are arranged at the top of the main frame.

[0021] Beneficial effects: the ultra-long thin-walled aluminum alloy profile anti-deformation vertical quenching method can estimate and determine the constraint distribution through a complete and quantitative design, scientifically determine the number and position of the constraints by calculating the maximum allowable constraint distance, avoid the errors caused by the traditional simple reliance on experience, and can meet the needs of vertical quenching of various cross-section complex ultra-long thin-walled aluminum alloy profiles, ensure that the critical buckling load of each section of the profile is greater than the maximum thermal stress that can be borne at that place, thereby eliminating deformation from the design source.

[0022] In the vertical quenching process, the profile is segmented by the constraint device, and the mounting position of the constraint module on the main frame is adjustable, which has universality and flexibility, can be adjusted to adapt to profiles with different lengths, different cross sections and different thermal stress distributions, and can better meet the needs of the vertical quenching of the ultra-long thin-walled aluminum alloy profile, and further prevent deformation during quenching. BRIEF DESCRIPTION OF DRAWINGS

[0023] Fig. 1 It is a structural schematic view of the constraint device in the present application.

[0024] Fig. 2 A schematic diagram of the structure of the restraint unit in the present application.

[0025] Fig. 3 A schematic diagram of the structure of the restraint unit without a lining in the present application.

[0026] Wherein: 1, hanger; 2, limiting strip; 3, top frame; 4, stand column; 5, restraint unit; 6, bottom frame; 7, support plate; 8, restraint tube; 9, limiting step; 10, clamp; 11, bolt assembly; 12, lining. DETAILED DESCRIPTION

[0027] In order to make the technical means, creative features, purposes and effects of the present application easy to understand, the present application will be further described below in combination with specific embodiments. EMBODIMENT

[0028] A vertical quenching method for preventing deformation of an ultra-long thin-walled 7075 aluminum alloy profile, the profile length is 10 meters, the profile cross-sectional area is 4.7*10 -4 ㎡, the embodiment comprises the following steps: S1, determining the mechanical parameters: obtaining the maximum equivalent buckling axial pressure P of the aluminum alloy profile to be quenched, the calculation formula is:

[0029] Wherein: k is a comprehensive correction coefficient, the value of k is 1-1.5 according to the complexity of the cross section; the value of k is 1-1.3 for low-complexity cross-sectional profiles such as I-shaped profiles and groove-shaped profiles, and the value of k is 1.3-1.5 for complex profiles such as multi-cavity special-shaped profiles; in this embodiment, the value of k is 1.2. Alpha is the thermal expansion coefficient of the aluminum alloy profile to be quenched, and the value of alpha of the 7075 aluminum alloy profile in this embodiment is 26*10⁻ 6 / °C; ΔT is the maximum instantaneous temperature difference of the profile to be quenched before and after quenching, which is 200℃; E is the material elastic modulus of the aluminum alloy profile to be quenched at high quenching temperature, which is 40 GPa; wherein the thermal expansion coefficient alpha of the aluminum alloy profile to be quenched and the material elastic modulus E of the aluminum alloy profile to be quenched at high quenching temperature are both detected according to the national standard, in this embodiment, the thermal expansion coefficient alpha of the aluminum alloy profile to be quenched is measured according to GBIT 4339-2008 Determination of Thermal Expansion Characteristics Parameters of Metallic Materials, the material elastic modulus E of the aluminum alloy profile to be quenched at high quenching temperature is measured according to GBIT22315-2008 Determination of Tensile Elasticity of Metallic Materials (Static Method), and the maximum instantaneous temperature difference ΔT of the cross section of the target aluminum alloy profile is measured by using a contact or infrared temperature measuring instrument to measure the temperature difference before and after quenching. In this embodiment, the maximum equivalent buckling axial pressure P of the aluminum alloy profile to be quenched is calculated to be 249.6 MPa; S2. Determine the maximum constraint length of a single segment: Further calculate the maximum allowable length of a single constraint segment of the aluminum alloy profile to be quenched. The calculation formula is:

[0030] Where: A is the cross-sectional area of ​​the quenched aluminum alloy profile; in this embodiment, the cross-sectional area of ​​the profile is 4.7 × 10⁻ 4 m 2 ; n is the safety factor, taken as 1.1; I is the minimum moment of inertia of the cross-section of the aluminum alloy profile to be quenched, which is 1.4 × 10⁻ 6 m 4 The minimum pipe properties can be directly obtained from the section property analysis module in SolidWorks; E is the elastic modulus of the aluminum alloy profile to be quenched at the quenching high temperature, which is 40 GPa; the maximum allowable length of a single constrained segment of the aluminum alloy profile to be quenched is calculated. It is 2.07m.

[0031] S3. Determine the minimum constraint segments: Based on the total length L of the aluminum alloy profile to be quenched being 10m, calculate the minimum number of constraint segments required. N is the integer rounded up from the calculated result, and the result is 5 segments. The calculation formula is:

[0032] S4. Solution quenching: Divide the aluminum alloy profile to be quenched into 5 equal segments according to the minimum constraint, and mark the segments radially from the bottom up. Fix the adjacent segment marks and the top of the profile by constraint. After fixing, perform vertical solution quenching. After solution quenching is completed, the profile can be taken out.

[0033] refer to Figs. 1-3 As shown, in this invention, the aluminum alloy profile to be quenched is constrained and fixed using a constraint device. For example... Fig. 1 As shown, the constraint device includes a main frame and a multi-layer constraint unit 5 disposed on the main frame; wherein, the main frame includes a column 4, a top frame 3 and a bottom frame, and the top frame 3 is provided with a hanger 1 and multiple limiting strips 2, wherein the hanger 1 is used to suspend the main frame, and the limiting strips 2 are movably inserted into the top frame 3 to limit and initially fix the top of the profile.

[0034] In this invention, the main frame includes columns 4, and the installation height of the constraint unit 5 on the main frame is adjustable to adapt to constraint requirements at different heights. Specifically, the four corners of the constraint unit 5 are connected to the columns 4 via clamps 10 and fixed by bolt assemblies 11.

[0035] like Fig. 2As shown, the constraint unit 5 comprises a support plate 7, constraint tubes 8 vertically arranged on the support plate 7, and an inner lining 12 sleeved in the constraint tubes 8. In a preferred embodiment, a plurality of constraint tubes 8 pass through the support plate 7 and are uniformly distributed in a matrix on the support plate 7. The inner lining 12 is movably sleeved in the constraint tubes 8, the outer wall of the inner lining 12 is adapted to the constraint tubes 8, and the inner lining 12 is provided with constraint holes allowing the to-be-quenched aluminum alloy profile to pass through and being adapted to the outer contour of the to-be-quenched aluminum alloy profile. In the present application, an assembly gap is provided between the inner lining 12 and the to-be-quenched profile. The gap requires that the inner lining 12 can be smoothly assembled into the constraint tube 8 in a cold state, and in a hot state, the inner lining 12 expands to form an interference fit with the aluminum alloy profile, thereby playing a role in constraining the profile. Preferably, the assembly gap between the inner lining 12 and the to-be-quenched profile is 0.5 mm.

[0036] As shown in Fig. 3 , a limiting step 9 is arranged at the bottom of the constraint tube 8, and the inner lining block is arranged on the limiting step 9, thereby achieving quick assembly and support positioning. Fig. 2 As shown in , the inner lining 12 comprises two independent and symmetrically arranged aluminum alloy lining blocks, thereby enabling quick assembly and clamping with the profile, and the disassembly is also extremely convenient. The lining blocks are replaceable to adapt to aluminum alloy profiles of different cross-sectional shapes with similar outer contours. The aluminum alloy inner lining 12 of the present application can reduce friction and scratches with the body profile, and at the same time, by utilizing the thermal expansion and cold shrinkage characteristics, the interference fit required in a hot state is met to constrain the profile, and the profile is easy to assemble and disassemble in a cold state, thereby solving the side effects that may be caused by the constraint itself.

[0037] In some preferred embodiments, a boron nitride coating is arranged on the surface of the lining block, which can better facilitate the profile to be taken out.

[0038] Embodiment 2 A vertical quenching method for preventing deformation of an ultra-long thin-walled 7075 aluminum alloy profile, the profile length is 13 meters, the profile cross-sectional area is 6.4 x 10 -4 ㎡, the cross section is relatively complex, the K value is 1.4, and the minimum moment of inertia is 1.8 x 10 6 m 4， The rest is the same as in Embodiment 1.

[0039] The embodiment described includes the following steps: S1, determining the mechanical parameters: obtaining the maximum equivalent buckling axial pressure P of the to-be-quenched aluminum alloy profile as 291.2 MPa; S2, determining the maximum constraint length of a single section: further calculating the maximum allowable length of a single constraint section of the to-be-quenched aluminum alloy profile as 1.89 m; S3, determining the minimum constraint segment: according to the total length L of the aluminum alloy profile to be quenched being 13 m, the minimum constraint segment required is calculated, N is an integer obtained by rounding up the calculation result, and the calculation result is 7 segments.

[0040] S4, solution quenching: the aluminum alloy profile to be quenched is evenly divided into 7 segments according to the minimum constraint segment, and is marked along the radial direction from the bottom to the top. The adjacent segment marks and the top of the profile are fixedly constrained. After being fixed, vertical solution quenching is carried out, and the profile is taken out after the solution quenching is completed.

[0041] Comparative Example 1 In this comparative example, the length of the profile is 10 meters, and the cross-sectional area of the super-long thin-walled 7075 aluminum alloy profile is 4.7*10 -4 ㎡. When the profile is vertically quenched, the traditional method is used, that is, the top of the profile to be quenched is fixed on the lifting tool, and the other parts of the profile to be quenched are in a free and unconstrained state. After the solution quenching is completed, the profile is taken out.

[0042] Comparative Example 2 The difference between this comparative example and Example 1 is that the profile to be quenched is not calculated scientifically, but is evenly divided into 3 segments from the bottom to the top along the radial direction, and each segment has a length of 3.33 m. The segments are marked along the radial direction from the bottom to the top. The adjacent segment marks and the top of the profile are fixedly constrained. After being fixed, vertical solution quenching is carried out, and the profile is taken out after the solution quenching is completed.

[0043] Comparative Example 3 The difference between this comparative example and Example 1 is that the assembly gap between the lining and the profile is 3 mm, and the rest is the same as Example 1.

[0044] The profiles quenched in each example and comparative example are detected, and the results are shown in Table 1.

[0045]

[0046] As shown in Table 1, the profile quenched by the method described in the application has good straightness and low plane gap. However, the profile quenched by the method in which the top of the profile is fixed in Comparative Example 1 is completely twisted and contaminated, which makes accurate measurement impossible. As shown in Comparative Example 2, when the constraint points are not calculated scientifically and are not properly controlled, the profile after quenching is prone to large deformation. As shown in Comparative Example 3, when the constraint is improper, the profile after quenching is also prone to deformation.

[0047] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A method of vertical quenching of an ultra-long thin-walled aluminum alloy profile without deformation, characterized in that, It comprises the following steps: S1, determining the mechanical parameters: obtaining the maximum equivalent buckling axial pressure P of the aluminum alloy profile to be quenched, and the calculation formula is: Wherein: k is the comprehensive correction coefficient, the range is 1~1.5; Alpha is the thermal expansion coefficient of the aluminum alloy profile to be quenched; Delta T is the maximum instantaneous temperature difference before and after quenching of the quenched profile; E is the material elastic modulus of the aluminum alloy profile to be quenched at high quenching temperature; S2, determining the maximum constraint length of a single section: further calculating the maximum allowable length of a single constraint section of the aluminum alloy profile to be quenched The calculation formula is: Wherein: A is the cross-sectional area of the aluminum alloy profile to be quenched, n is the safety factor, n is 1~1.2; I is the minimum moment of inertia of the cross section of the aluminum alloy profile to be quenched; S3, determine the minimum constraint section: according to the total length L of the aluminum alloy profile to be quenched, calculate the minimum constraint section required, N is the integer of the calculation result, the calculation formula is: ； S4, solution quenching: the aluminum alloy profile to be quenched is evenly divided according to the minimum constraint section N, and is marked along the radial direction from the bottom to the top. The adjacent section mark and the top of the profile are fixed. After fixing, solution quenching is carried out, and the profile is taken out after solution quenching is completed.

2. The ultra-long thin-walled aluminum alloy profile anti-deformation vertical quenching method according to claim 1, characterized in that, The length of the aluminum alloy profile to be quenched is greater than or equal to 8 meters, and the aluminum alloy profile to be quenched is fixed by the constraint device, and the assembly gap between the constraint device and the quenched profile is 0.1~1mm.

3. The ultra-long thin-walled aluminum alloy profile anti-deformation vertical quenching method according to claim 2, characterized in that, The constraint device comprises a main frame and a plurality of constraint units arranged on the main frame; the constraint unit comprises a supporting plate, a constraint pipe arranged vertically on the supporting plate, and an inner lining sleeve arranged in the constraint pipe, the outer wall of the inner lining sleeve is matched with the constraint pipe, and the inner lining sleeve is provided with a constraint hole which allows the aluminum alloy profile to be quenched to pass through and is matched with the outer contour of the aluminum alloy profile to be quenched.

4. The ultra-long thin-walled aluminum alloy profile anti-deformation vertical quenching method according to claim 3, characterized in that, The inner lining sleeve is arranged on the limiting step.

5. The ultra-long thin-walled aluminum alloy profile anti-deformation vertical quenching method according to claim 3, characterized in that, The inner lining sleeve comprises two independent and symmetrical inner lining blocks.

6. The ultra-long thin-walled aluminum alloy profile anti-deformation vertical quenching method according to claim 5, characterized in that, The inner lining block is an aluminum alloy inner lining block.

7. The ultra-long thin-walled aluminum alloy profile anti-deformation vertical quenching method according to claim 6, characterized in that, The surface of the inner lining block is provided with a boron nitride coating.

8. The ultra-long thin-walled aluminum alloy profile anti-deformation vertical quenching method according to claim 3, characterized in that, The mounting height of the constraint unit on the main frame is adjustable.

9. The ultra-long thin-walled aluminum alloy profile anti-deformation vertical quenching method according to claim 3, characterized in that, The main frame comprises a stand column, and the supporting plate is connected with the stand column through a clamp.

10. The ultra-long thin-walled aluminum alloy profile anti-deformation vertical quenching method according to claim 3, characterized in that, The main frame is provided with a hanging bracket and a limiting strip at the top.

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