Vertical quenching method for preventing deformation of ultra-long thin-walled aluminum alloy profiles

Abstract

This invention relates to the field of aluminum alloy profile processing technology, specifically disclosing a vertical quenching method for preventing deformation of ultra-long, thin-walled aluminum alloy profiles, comprising the following steps: S1, determining mechanical parameters and obtaining the maximum equivalent buckling axial pressure P of the aluminum alloy profile to be quenched; S2, determining the maximum constraint length of a single segment: further calculating the maximum allowable length of a single constraint segment of the aluminum alloy profile to be quenched; S3, determining the minimum constraint segments; S4, solution quenching: dividing the aluminum alloy profile to be quenched into equal parts according to the minimum constraint segments N, and marking the segments radially from the bottom up, constraining and fixing adjacent segment markings and the top of the profile; after fixing, solution quenching is performed, and the profile can be removed after solution quenching is completed. This invention is suitable for the vertical quenching needs of ultra-long, thin-walled aluminum alloy profiles with various complex cross-sections, effectively preventing deformation of the profile during vertical quenching.

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 process reinforcement at localized locations of the profile or using a rigid bottom fixing method for quenching. For example, Chinese patent CN218989308U proposes a special fixing ring for solution quenching of aluminum alloy profiles. This fixing ring structure consists of four concentric rings (number one, two, three, and four). 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. Another example is Chinese patent CN108441793B, which proposes a heat treatment method for rigidly shaping aluminum alloys and aluminum alloy profiles for aerospace applications. This method uses a rigidly shaping device to fix the extruded profile into a linear shape before quenching. However, these methods lack quantitative analysis of the transient temperature and stress field evolution and instability mechanism of the profile during quenching. They cannot scientifically determine the optimal number and spatial layout of the required constraint points, nor can they optimize the stiffness and form of the constraints. As a result, the profile still becomes unstable and twists when the constraints are insufficient, while excessive constraints may introduce new restraint stresses, leading to a deterioration of the internal stress distribution of the profile, or making the tooling too 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:

[0006] A vertical quenching method for preventing deformation of ultra-long, thin-walled aluminum alloy profiles includes the following steps:

[0007] S1. Determine mechanical parameters: Obtain the maximum equivalent buckling axial pressure P of the aluminum alloy profile to be quenched. The calculation formula is: Where: k is the comprehensive correction coefficient, ranging from 1 to 1.5; α is the coefficient of thermal expansion of the aluminum alloy profile to be quenched, in °C. -1 ΔT is the maximum instantaneous temperature difference between the profile to be quenched before and after quenching, in °C; E is the elastic modulus of the aluminum alloy profile to be quenched at the quenching high temperature, in MPa.

[0008] 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: Where: A is the cross-sectional area of ​​the aluminum alloy profile to be quenched, in m². 2 ; n is the safety factor, with a value ranging from 1 to 1.2; I is the minimum moment of inertia of the cross-section of the aluminum alloy profile to be quenched, in meters. 4 ;

[0009] S3. Determine the minimum constraint segments: Based on the total length L of the aluminum alloy profile to be quenched, calculate the minimum constraint segments required, where N is the integer rounded up from the calculated result. The calculation formula is: S4. Solution quenching: Divide the aluminum alloy profile to be quenched into equal sections N according to the minimum constraint segment, and mark the sections radially from the bottom up. Constrain and fix the adjacent section marks and the top of the profile. After fixing, perform solution quenching. After solution quenching is completed, the profile can be taken out.

[0010] Furthermore, 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 constrained and fixed by a constraint device.

[0011] Furthermore, the assembly gap between the constraint device and the profile to be quenched is 0.1 to 1 mm.

[0012] Furthermore, the constraint device includes a main frame and a multi-layer constraint unit disposed on the main frame; the constraint unit includes a support plate, a constraint tube arranged vertically on the support plate, and an inner liner sleeved inside the constraint tube. The outer wall of the inner liner is adapted to the constraint tube, and the inner liner is provided with constraint holes that allow the aluminum alloy profile to be quenched to pass through and are adapted to the outer contour of the aluminum alloy profile to be quenched.

[0013] In this invention, an inner liner with constraint holes adapted to aluminum alloy profiles of different cross sections can be selected according to the needs of different profiles, thereby achieving targeted constraint with different aluminum alloy profiles.

[0014] Furthermore, a limiting step is provided at the bottom of the constraint tube, and the inner liner is placed on the limiting step to achieve rapid assembly and support positioning.

[0015] Furthermore, the inner liner includes two independent and symmetrically arranged inner liner blocks, which can be quickly assembled and engaged with the profile, and disassembly is also extremely convenient.

[0016] Furthermore, the inner liner is an aluminum alloy inner liner, which is replaceable to accommodate aluminum alloy profiles with different cross-sectional shapes and similar outer dimensions.

[0017] In this invention, the assembly gap between the restraining device and the profile to be quenched allows the inner liner to be smoothly assembled into the restraining tube in the cold state. In the hot state, the inner liner expands and forms an interference fit with the aluminum alloy profile, thereby restraining the profile. Preferably, the assembly gap between the inner liner and the profile to be quenched is 0.1–1 mm.

[0018] Furthermore, the surface of the inner liner block is coated with boron nitride, which facilitates the removal of the profile.

[0019] Furthermore, the mounting height of the constraint unit on the main frame is adjustable.

[0020] Furthermore, the main frame includes columns, and the support plate is connected to the columns by clamps.

[0021] Furthermore, a hanger and a limiting strip are provided at the top of the main frame.

[0022] Beneficial effects: The vertical quenching method for preventing deformation of ultra-long thin-walled aluminum alloy profiles described in this invention predicts and determines the constraint distribution through a universal, complete, and quantitative design, and scientifically determines the number and location of constraints by calculating the maximum allowable constraint spacing. This avoids the errors caused by relying solely on experience in the traditional method. This invention is suitable for the vertical quenching needs of ultra-long thin-walled aluminum alloy profiles with various complex cross-sections, ensuring that the critical buckling load of each section of the profile is greater than the maximum thermal stress that it may bear at that location, thereby eliminating deformation from the design source.

[0023] In the vertical quenching process of this invention, a constraint device is used to constrain the profile in sections. The installation position of the constraint module on the main frame is adjustable, which has versatility and flexibility. It can be adjusted to adapt to profiles of different lengths, cross sections and thermal stress distributions, which can better meet the needs of vertical quenching of ultra-long thin-walled aluminum alloy profiles as described in this invention, and further prevent deformation during the quenching process. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the constraint device in this invention.

[0025] Figure 2 This is a schematic diagram of the constraint unit in this invention.

[0026] Figure 3 This is a schematic diagram of the constraint unit without an inner liner in this invention.

[0027] The components include: 1. Hanger; 2. Limiting strip; 3. Top layer frame; 4. Column; 5. Restraint unit; 6. Bottom layer frame; 7. Support plate; 8. Restraint tube; 9. Limiting step; 10. Clamp; 11. Bolt assembly; 12. Liner. Detailed Implementation

[0028] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific embodiments.

[0029]

[0030] As shown in Table 1, vertical quenching using the method described in this invention results in profiles with good straightness and low planar gaps. However, vertical quenching using the method of fixing the top of the profile as in Comparative Example 1 results in profiles that are completely distorted and contaminated with inaccurate measurements. As shown in Comparative Example 2, when the constraint points are not scientifically calculated and are not properly controlled, the quenched profiles are prone to large deformations. As shown in Comparative Example 3, when the constraints are improper, the quenched profiles are also prone to deformation.

[0031] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method of preventing deformation of an ultra-long thin-walled aluminum alloy profile during vertical quenching, characterized by, It comprises the following steps: S1, determining the mechanical parameter: obtaining the maximum equivalent buckling axial pressure P of the aluminum alloy profile to be quenched, and the calculation formula is: 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, with the unit of °C -1 ; Delta T is the maximum instantaneous temperature difference before and after quenching of the quenched profile, with the unit of °C; E is the material elastic modulus of the aluminum alloy profile to be quenched at the quenching high temperature, with the unit of Mpa; 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, with a unit of m 2 ; n is a 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, with a unit of m 4 ; S3, determining the minimum constraint segment: according to the total length L of the aluminum alloy profile to be quenched, the minimum constraint segment required is calculated, N is the integer obtained by rounding up the calculation result, and the calculation formula is: S4, solution quenching: the aluminum alloy profile to be quenched is evenly divided according to the minimum constraint segment N, 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 fixing, solution quenching is carried out, and after the solution quenching is completed, the profile can be taken out.

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, the aluminum alloy profile to be quenched is fixed by a restraint device, and the assembly gap between the restraint device and the profile to be quenched is 0.1-1 mm.

3. The ultra-long thin-walled aluminum alloy profile anti-deformation vertical quenching method according to claim 2, characterized in that, The restraint device comprises a main frame and a plurality of restraint units arranged on the main frame; the restraint unit comprises a support plate, a restraint tube arranged vertically on the support plate, and an inner lining sleeved in the restraint tube, the outer wall of the inner lining is matched with the restraint tube, and the inner lining is provided with a restraint 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.

4. The ultra-long thin-walled aluminum alloy profile anti-deformation vertical quenching method according to claim 3, characterized in that, The inner bottom of the restraint tube is provided with a limiting step, and the inner lining 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 comprises two independent and symmetrically arranged 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 restraint 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 support 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 top of the main frame is provided with a hanging bracket and a limiting strip.

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