A buckling suppression method for the forming of complex curvature thin-walled components

Abstract

A buckling suppression method for forming complex curvature thin-walled components, comprising the following steps: Step 1, first cut out the sheet metal for creep age forming, and then continue to cut the sheet metal for creep age forming into a sheet metal workpiece area and a sheet metal allowance area. Punch a circle of small holes in the sheet metal allowance area. Use a metal plate to cut out an upper pressing plate and a lower pressing plate with the same shape as the sheet metal for creep age forming. The middle part of the upper pressing plate is hollow, and the upper pressing plate is provided with small holes corresponding to the small holes for bolts to pass through in the sheet metal allowance area. The lower pressing plate is provided with internal threaded holes corresponding to the small holes; Step 2, place the lower pressing plate on the mold, place the sheet metal workpiece area and the sheet metal allowance area together in a plate shape on the lower pressing plate, and then place the upper pressing plate above it. Tighten and connect the upper pressing plate, the sheet metal allowance area and the lower pressing plate together with bolts to form a connection body; Step 3, after subjecting the connection body to vacuum creep age forming, take out the sheet metal workpiece area.

Description

Technical Field

[0001] The present invention belongs to the technical field of thin-walled component manufacturing, and particularly relates to a buckling suppression method for forming complex-curvature thin-walled components. Background Technique

[0002] The aerospace industry often involves the application of complex-curvature thin-walled components. However, in the creep age forming process of complex-curvature thin-walled components, problems such as the workpiece being prone to instability buckling during the loading process and the surface accuracy of the formed workpiece being prone to fluctuations after the surplus is removed often occur.

[0003] To address the above problems, a stiffness compensation method is usually adopted at present, that is, connecting metal plates to increase the stiffness of the workpiece, thereby suppressing the problem of instability buckling of the workpiece during the creep age forming process. However, the current method still has the following problems:

[0004] 1. Since the compensated stiffness is fixed, but for different parts of the workpiece, the required stiffness compensation amount is inconsistent. Therefore, overcompensation may lead to an under-bent state or undercompensation may lead to a buckling state;

[0005] 2. After creep age forming, a surplus removal process is required. The formed workpiece has a complex curvature shape, which is difficult to operate during the cutting process, and the edge contour line after cutting is not smooth;

[0006] 3. After the surplus of the workpiece is removed, the surface accuracy of the workpiece has a certain fluctuation compared with that before the surplus is removed, affecting the stability of the process.

[0007] Therefore, it is necessary to design a new buckling suppression method for forming complex-curvature thin-walled components. Summary of the Invention

[0008] The purpose of the present invention is to provide a buckling suppression method for forming complex-curvature thin-walled components to solve the problems existing in the current method of using stiffness compensation to suppress buckling in the background technique.

[0009] To achieve the above purpose, the present invention provides a buckling suppression method for forming complex-curvature thin-walled components, including the following steps:

[0010] Step 1: First, cut the sheet metal that meets the requirements into the sheet metal for creep age forming. Then, according to the design requirements of the complex curvature thin-walled component, continue to cut the sheet metal for creep age forming into the sheet metal workpiece area for forming the complex curvature thin-walled component and the sheet metal margin area located outside the sheet metal workpiece area. Drill a circle of small holes for bolts to pass through in the sheet metal margin area. After cutting, still embed the sheet metal workpiece area in the sheet metal margin area to form a plate shape. Cut the upper pressing plate and the lower pressing plate with the same shape as the sheet metal for creep age forming using metal plates. The middle part of the upper pressing plate is hollow, and the outer edge is parallel to the inner edge. Small holes corresponding to the small holes for bolts to pass through in the sheet metal margin area are provided on the upper pressing plate, and internal threaded holes corresponding to the small holes for bolts to pass through in the sheet metal margin area are provided on the lower pressing plate;

[0011] Step 2: Place the lower pressing plate in the contact direction of the mold. Place the sheet metal workpiece area and the sheet metal margin area that are formed into a plate shape on the lower pressing plate. Then place the upper pressing plate above the sheet metal workpiece area and the sheet metal margin area. Tighten and connect the upper pressing plate, the sheet metal margin area, and the lower pressing plate together with bolts that match the internal threaded holes, so that the sheet metal workpiece area is embedded between the upper pressing plate, the sheet metal margin area, and the lower pressing plate to form a connection body;

[0012] Step 3: After the connection body is subjected to vacuum creep age forming, take out the sheet metal workpiece area.

[0013] In a specific embodiment, the small holes on the sheet metal margin area are evenly distributed along the outer edge of the sheet metal margin area.

[0014] In a specific embodiment, Step 3 specifically includes: completely wrapping the connection body with a breather felt, placing it on the mold after wrapping, using high-temperature glue and a vacuum bag to seal the connection body in the closed space formed by the vacuum bag and the mold and evacuating the air, then putting the combination of the connection body and the mold into a autoclave for vacuum creep age forming. After the vacuum creep age forming is completed, remove the bolts of the connection body and take out the sheet metal workpiece area.

[0015] In a specific embodiment, in the connection body, the lower end of the bolt is not lower than the lower surface of the lower pressing plate.

[0016] In a specific embodiment, when continuing to cut the sheet metal for creep age forming into the sheet metal workpiece area for forming the complex curvature thin-walled component and the sheet metal margin area located outside the sheet metal workpiece area, laser cutting or water cutting is used.

[0017] In a specific embodiment, the materials and thicknesses of the upper pressing plate and the lower pressing plate are the same.

[0018] In a specific embodiment, the nominal diameter of the bolt is 6 - 10 mm.

[0019] In a specific embodiment, the distance between two adjacent small holes for the bolt to pass through is 15 - 40 mm.

[0020] In a specific embodiment, the gap between the cut sheet metal workpiece area and the sheet metal allowance area is 0.5 - 2 mm.

[0021] In a specific embodiment, the qualified sheet metal is an aluminum - lithium alloy sheet, and the metal sheet is an aluminum - magnesium alloy sheet.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention increases the stiffness of the sheet metal workpiece area, preventing the occurrence of instability buckling during loading.

[0024] The present invention can flexibly adjust the opening size of the hollow in the middle of the upper pressure plate according to the shape characteristics of the complex - curvature thin - walled component and the process parameters of the test, breaking through the limitation of the whole plate and realizing variable - stiffness compensation for the workpiece.

[0025] The present invention can cut the sheet metal allowance area when the sheet metal workpiece area is in a flat state. After the vacuum creep aging test, the edge contour line of the complex - curvature thin - walled component is smoother, which is beneficial to improving the subsequent welding quality.

[0026] The present invention can avoid the problem of surface accuracy fluctuation caused by cutting the allowance after the forming of the sheet metal workpiece area.

[0027] At the end of creep aging, the present invention can complete the production of the complex - curvature thin - walled component, which is more convenient and fast.

[0028] When instability occurs, the gap area generated by cutting between the sheet metal workpiece area and the sheet metal allowance area of the present invention can serve as a buffer zone, thus preventing the sheet metal workpiece area from being damaged by greater external forces.

[0029] In addition to the purposes, features and advantages described above, the present invention has other purposes, features and advantages. The following will refer to the drawings for a further detailed description of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0031] Figure 1 It is a schematic cross - sectional view of an embodiment of the present invention after assembly and placed on a mold.

[0032] Figure 2It is a schematic structural view of the sheet metal workpiece area of an embodiment of the present invention;

[0033] Figure 3 It is a schematic structural view of the sheet metal allowance area of an embodiment of the present invention;

[0034] Figure 4 It is a schematic structural view of the upper pressing plate of an embodiment of the present invention;

[0035] Figure 5 It is a schematic structural view of the lower pressing plate of an embodiment of the present invention;

[0036] Figure 6 It is a schematic view of the sheet metal workpiece area and the sheet metal allowance area nested together in an embodiment of the present invention.

[0037] Among them, 1. Sheet metal workpiece area; 2. Sheet metal allowance area; 3. Upper pressing plate; 4. Lower pressing plate; 5. Bolt; 6. Mold. Specific embodiments

[0038] The following will describe the embodiments of the present invention in detail with reference to the accompanying drawings. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] Embodiment 1

[0040] A buckling suppression method for forming a complex curvature thin-walled member includes the following steps:

[0041] Step 1: First, cut the sheet metal that meets the requirements into the sheet metal for creep age forming, and then, according to the design requirements of the complex curvature thin-walled member, continue to cut the sheet metal for creep age forming into the sheet metal workpiece area 1 for forming the complex curvature thin-walled member and the sheet metal allowance area 2 located outside the sheet metal workpiece area 1. Drill a circle of small holes for the bolt 5 to pass through in the sheet metal allowance area 2. After cutting, still embed the sheet metal workpiece area 1 in the sheet metal allowance area 2 to form a plate shape. Cut the upper pressing plate 3 and the lower pressing plate 4 with the same shape as the sheet metal for creep age forming from a metal plate. The middle part of the upper pressing plate 3 is hollow, and the outer edge is parallel to the inner edge. The upper pressing plate 3 is provided with small holes corresponding to the small holes for the bolt to pass through in the sheet metal allowance area 2, and the lower pressing plate 4 is provided with internal threaded holes corresponding to the small holes for the bolt to pass through in the sheet metal allowance area 2;

[0042] Step 2: Place the lower pressing plate 4 in the contact direction of the mold 6, place the sheet metal workpiece area 1 and the sheet metal allowance area 2 in a plate shape on the lower pressing plate 4, then place the upper pressing plate 3 above the sheet metal workpiece area 1 and the sheet metal allowance area 2, and tighten and connect the upper pressing plate 3, the sheet metal allowance area 2 and the lower pressing plate 4 together through the bolt 5 matching the internal threaded hole, so that the sheet metal workpiece area 1 is embedded between the upper pressing plate 3, the sheet metal allowance area 2 and the lower pressing plate 4 to form a connection body;

[0043] Step 3: After the connector is subjected to vacuum creep aging forming, take out the sheet metal workpiece area 1.

[0044] The small holes on the sheet metal margin area 2 are evenly distributed along the outer edge of the sheet metal margin area 2. Being close to the outer edge can minimize the influence on the accuracy of the inner sheet metal workpiece area 1.

[0045] The specific content of Step 3 includes: completely wrapping the connector with a breather felt, placing it on the mold 6 after wrapping, using a high-temperature adhesive and a vacuum bag to seal the connector in the closed space formed by the vacuum bag and the mold 6 and evacuating, then putting the combination of the connector and the mold 6 into a autoclave for vacuum creep aging forming, and after the vacuum creep aging forming is completed, removing the bolt 5 of the connector and taking out the sheet metal workpiece area 1.

[0046] In the connector, the lower end of the bolt 5 is not lower than the lower surface of the lower pressing plate 4. Thus, it is convenient for the lower surface of the lower pressing plate to closely fit the mold surface during the creep aging process.

[0047] When the sheet metal used for creep aging forming is continuously cut into the sheet metal workpiece area 1 for forming a complex curvature thin-walled member and the sheet metal margin area 2 located outside the sheet metal workpiece area, laser cutting or water cutting is adopted. Although the cost is higher, it is more accurate and convenient for later welding.

[0048] The upper pressing plate 3 and the lower pressing plate 4 are made of the same material and have the same thickness. It is preferably to cut the upper pressing plate 3 and the lower pressing plate 4 with the same metal sheet, which saves costs.

[0049] The nominal diameter of the bolt 5 is 6 - 10 mm. The preferably adopted bolt specifications are M6 bolts, M8 bolts and M10 bolts, which have the advantages of being of appropriate size, better fastening effect, and more convenient disassembly.

[0050] The distance between two adjacent small holes for the bolt to pass through is 15 - 40 mm. If the distance between the small holes is too small, it is not convenient for installation. If the distance between the small holes is too large, it may affect the state of the connector and there is a risk of buckling.

[0051] The gap between the cut sheet metal workpiece area 1 and the sheet metal margin area 2 is 0.5 - 2 mm. If the gap is too small, it is not convenient to disassemble and take out. If the gap is too large, it may shift during the creep aging process and affect the accuracy of the workpiece.

[0052] The qualified sheet metal is an aluminum-lithium alloy sheet, and the metal sheet is an aluminum-magnesium alloy sheet. The aluminum-lithium alloy sheet has the characteristics of high specific strength, high elastic modulus and low density. The aluminum-magnesium alloy sheet has a relatively lower cost and can assist in meeting the stiffness requirements.

[0053] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions and substitutions can still be made, and all should be regarded as falling within the protection scope of the present invention.

Claims

1. A buckling suppression method for forming complex curvature thin-walled components, characterized in that, it includes the following steps: Step 1: First, cut out the sheet metal for creep age forming from the qualified sheet metal. Then, according to the design requirements of the complex curvature thin-walled component, continue to cut the sheet metal for creep age forming into the sheet metal workpiece area (1) for forming the complex curvature thin-walled component and the sheet metal surplus area (2) located outside the sheet metal workpiece area (1). Punch a circle of small holes for the bolts (5) to pass through in the sheet metal surplus area (2). After cutting, still embed the sheet metal workpiece area (1) in the sheet metal surplus area (2) and piece them together into a plate shape. Cut out the upper pressing plate (3) and the lower pressing plate (4) with the same shape as the sheet metal for creep age forming from metal. The middle of the upper pressing plate (3) is hollow, and the outer edge is parallel to the inner edge. The upper pressing plate (3) is provided with small holes corresponding to the small holes for the bolts to pass through in the sheet metal surplus area (2), and the lower pressing plate (4) is provided with internal threaded holes corresponding to the small holes for the bolts to pass through in the sheet metal surplus area (2); Step 2: Place the lower pressing plate (4) in the contact direction of the mold (6), place the sheet metal workpiece area (1) and the sheet metal surplus area (2) pieced together into a plate shape on the lower pressing plate (4), and then place the upper pressing plate (3) above the sheet metal workpiece area (1) and the sheet metal surplus area (2). Tighten and connect the upper pressing plate (3), the sheet metal surplus area (2), and the lower pressing plate (4) together through the bolts (5) matching the internal threaded holes, so that the sheet metal workpiece area (1) is embedded between the upper pressing plate (3), the sheet metal surplus area (2), and the lower pressing plate (4) to form a connection body; Step 3: After the connection body is subjected to vacuum creep age forming, take out the sheet metal workpiece area (1).

2. The buckling suppression method for forming complex curvature thin-walled components according to claim 1, characterized in that, the small holes on the sheet metal surplus area (2) are evenly distributed along the outer edge of the sheet metal surplus area (2).

3. The buckling suppression method for forming complex curvature thin-walled components according to claim 1, characterized in that, Step 3 specifically includes: completely wrap the connection body with a breather felt, place it on the mold (6) after wrapping, use high-temperature glue and a vacuum bag to seal the connection body in the closed space formed by the vacuum bag and the mold (6) and evacuate it, then put the combination of the connection body and the mold (6) into a hot press can for vacuum creep age forming. After the vacuum creep age forming is completed, remove the bolts (5) of the connection body and take out the sheet metal workpiece area (1).

4. The buckling suppression method for forming complex curvature thin-walled components according to claim 1, characterized in that, in the connection body, the lower end of the bolt (5) is not lower than the lower surface of the lower pressing plate (4).

5. The buckling suppression method for forming complex curvature thin-walled components according to claim 1, characterized in that, when continuing to cut the sheet metal for creep age forming into the sheet metal workpiece area (1) for forming the complex curvature thin-walled component and the sheet metal surplus area (2) located outside the sheet metal workpiece area, laser cutting or water cutting is adopted.

6. The buckling suppression method for forming complex curvature thin-walled components according to claim 1, It is characterized in that the upper pressing plate (3) and the lower pressing plate (4) are made of the same material and have the same thickness.

7. The buckling suppression method for forming a thin-walled member with complex curvature according to claim 1, It is characterized in that the nominal diameter of the bolt (5) is 6-10 mm.

8. The buckling suppression method for forming a thin-walled member with complex curvature according to claim 1, It is characterized in that the distance between two adjacent small holes for the bolt to pass through is 15-40 mm.

9. The buckling suppression method for forming a thin-walled member with complex curvature according to claim 1, It is characterized in that the gap between the cut sheet metal workpiece area (1) and the sheet metal allowance area (2) is 0.5-2 mm.

10. The buckling suppression method for forming a thin-walled member with complex curvature according to claim 1, It is characterized in that the qualified sheet metal is an aluminum-lithium alloy sheet, and the metal sheet is an aluminum-magnesium alloy sheet.

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