CN113894187A

CN113894187A - Aluminum alloy high-rib wallboard prestress laser bending forming method

Info

Publication number: CN113894187A
Application number: CN202111153572.XA
Authority: CN
Inventors: 徐琅; 候正全; 杨学勤; 孟佳杰; 冯苏乐; 李宝辉; 罗志强
Original assignee: Shanghai Space Precision Machinery Research Institute
Current assignee: Shanghai Space Precision Machinery Research Institute
Priority date: 2021-09-29
Filing date: 2021-09-29
Publication date: 2022-01-07
Anticipated expiration: 2041-09-29
Also published as: CN113894187B

Abstract

The invention provides a prestress laser bending forming method of an aluminum alloy high-rib wallboard, which comprises the following steps of S1, dividing a plurality of areas to be formed on the breadth of the aluminum alloy high-rib wallboard; s2, selecting any region to be formed to carry out pre-bending loading so that the region to be formed enters slight plasticity; s3, scanning the ribs with concentrated elastic stress in the region to be formed by using laser beams; s4, after the aluminum alloy high-rib wallboard is cooled to room temperature, unloading is carried out, and the forming of the area to be formed, which is subjected to pre-bending loading, is completed; s5, repeating the steps S2, S3 and S4 for the rest of areas to be formed in sequence, and obtaining the aluminum alloy high-rib wall plate bending forming piece. The pre-bending loading is carried out on the area to be formed, so that the area to be formed enters slight plasticity, and then the rib part with concentrated elastic stress is scanned by the laser beam, so that the bending forming of the aluminum alloy high-rib wallboard is realized, the overload damage and the damage of the high-rib wallboard are avoided, and the forming precision of the high-rib wallboard is improved.

Description

Aluminum alloy high-rib wallboard prestress laser bending forming method

Technical Field

The invention relates to the technical field of metal plastic forming, in particular to a prestress laser bending forming method for an aluminum alloy high-rib wallboard.

Background

The aluminum alloy wall plate is a main bearing component widely used on large aircrafts such as carrier rockets, space stations, military aircrafts, civil aircrafts and the like, and is also an important component of the aerodynamic appearance of the aircrafts, and the interior of the aluminum alloy wall plate comprises structural elements such as skins, ribs, bosses and the like.

In recent years, in order to meet the requirements of improvement of carrying capacity and development of light weight of the structure of an aircraft, the design height of ribs of aluminum alloy wall plates is continuously increased, and aluminum alloy high-rib wall plates with ribs higher than 30mm are increasingly applied. The aluminum alloy high-rib wallboard is usually formed by adopting a roll bending or press bending method, and the forming process of the aluminum alloy high-rib wallboard has the following problems that firstly, the rib of the wallboard has instability and cracking phenomena due to overlarge mechanical load; secondly, the wallboard generates obvious resilience in the unloading process, and the precision requirement is difficult to achieve.

The prior Chinese patent with publication number CN105033004B discloses a light-weight wallboard laser-induced flexible forming system and a method, and the system comprises a photogrammetric unit, a laser, an infrared thermometer, an intelligent cooling unit, a machine tool workbench, a machine tool scanning driving mechanism, a data analysis control unit and a machine tool control unit; irradiating the lightweight wall plate planar piece to be formed with a laser beam at each scanning line, measuring the temperature of the lightweight wall plate, and performing cooling control according to the measured temperature to cause the lightweight wall plate planar piece to be formed to generate bending deformation toward the direction of the laser beam; measuring the deformation of the light-weight wallboard plane piece, judging whether the deformation of the light-weight wallboard plane piece reaches a set value, and if so, carrying out laser irradiation on the next scanning line; if the set value is not reached, the laser irradiation of the scanning line is performed again.

The inventors believe that there is a need for an improved laser-induced flexible forming system and method for bending aluminum alloy high-rib panels that rely on thermal stress induced by laser heating to bend the panels and that have limited forming capability and are difficult to bend with large deformation resistance.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a prestress laser bending forming method for an aluminum alloy high-rib wallboard.

The invention provides an aluminum alloy high-rib wallboard prestress laser bending forming method, which comprises the following steps of: s1, dividing a plurality of areas to be formed on the breadth of the aluminum alloy high-rib wallboard; s2, selecting any one to-be-formed area to carry out pre-bending loading, and enabling the to-be-formed area to enter slight plasticity; s3, scanning the rib part with elastic stress concentration in the slightly plastic region to be formed by using a laser beam; s4, cooling the aluminum alloy high-rib wallboard to room temperature after laser scanning is finished, and unloading to finish forming the area to be formed, which is subjected to pre-bending loading; and S5, repeating the steps S2, S3 and S4 for the rest of the area to be formed in sequence, and obtaining the aluminum alloy high-rib wall plate bending forming piece.

Preferably, for step S1, an overlap region is formed between any one of the regions to be formed and the adjacent region to be formed.

Preferably, the area of the overlapping zone is 10% to 25% of the area to be shaped.

Preferably, for step S2, a three-point bending method is adopted to pre-bend the region to be formed; the three-point bending method adopts two lower pressure heads and an upper pressure head, wherein the two lower pressure heads act on the skin surface of the aluminum alloy high-rib wallboard, the two lower pressure heads are respectively positioned at the edge positions of two sides of a region to be formed for pre-bending loading, the upper pressure head acts on the rib surface of the aluminum alloy high-rib wallboard, and the upper pressure head is positioned in the middle of the region to be formed for pre-bending loading; the upper pressure head and the two lower pressure heads are matched to enable the area to be formed, which is subjected to pre-bending loading, to be subjected to bending deformation.

Preferably, the magnitude of the bending load applied to the aluminum alloy high-rib wallboard is determined by a finite element simulation method, the maximum plastic strain in the loaded aluminum alloy high-rib wallboard is not more than 2%, and the surface of the aluminum alloy high-rib wallboard is not damaged by indentation, scratch, microcrack and the like.

Preferably, the locations of the ribs where elastic stress is concentrated in the region to be formed in step S3 are determined by theoretical analysis or finite element simulation.

Preferably, for step S4, the laser beam comprises a laser beam emitted by a continuous wave laser.

Preferably, for step S4, when the laser beam scans the aluminum alloy high-rib panel, it is ensured that the surface of the aluminum alloy high-rib panel does not melt, ablate, or significantly oxidize.

Preferably, for step S4, the laser beam is generally required to scan the aluminum alloy high-strength wallboard, and the temperature of the surface of the aluminum alloy high-strength wallboard is within 400 ℃.

Compared with the prior art, the invention has the following beneficial effects:

1. according to the invention, the pre-bending loading is carried out on the area to be formed by using a three-point bending method of two lower pressing heads and one upper pressing head, so that the area to be formed enters slight plasticity, and then the rib part with concentrated elastic stress is scanned by laser beams, so that the bending forming of the aluminum alloy high-rib wallboard is realized, the mechanical load applied to the aluminum alloy high-rib wallboard in the whole forming process is smaller, the overload damage and damage of the aluminum alloy high-rib wallboard are avoided, and the rebound of the wallboard is very small when the wallboard is unloaded after the laser action, so that the forming precision is improved;

2. the loading method has the advantages that the two lower pressure heads and the upper pressure head are matched to load the aluminum alloy high-rib wallboard, so that on one hand, a region to be formed can enter slight plasticity, on the other hand, the loading method has high flexibility, and the loading method is suitable for the aluminum alloy high-rib wallboards with different shapes and different rib structures;

3. the forming device is beneficial to improving the smoothness of deformation transition of the two adjacent areas to be formed by arranging the overlapping area between the two adjacent areas to be formed.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is a schematic view showing the distribution of the areas to be formed on the aluminum alloy high-rib panel according to the present invention;

fig. 2 is a schematic view of the laser beam scanning of the area to be shaped according to the present invention.

Shown in the figure:

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

As shown in fig. 1 and fig. 2, the aluminum alloy high-rib wall plate 1 provided by the invention is a prestressed laser bending forming method, which comprises the following steps:

s1, dividing five regions to be formed 5 on the breadth of the aluminum alloy high-rib wallboard 1, wherein the shapes and the areas of the five regions to be formed 5 are equal. The aluminum alloy high-rib wallboard 1 is a main bearing component widely used on large aircrafts such as carrier rockets, space stations, military aircrafts, civil aircrafts and the like. An overlapping area 6 is formed between any one area 5 to be formed and the adjacent area 5 to be formed in a matched mode, the area of the overlapping area 6 accounts for 10% -25% of the area 5 to be formed, and the overlapping area 6 has the function of enabling deformation between the two adjacent areas 5 to be formed to be smoothly transited.

And S2, selecting any region 5 to be formed for pre-bending loading, wherein the region 5 to be formed is pre-bent and loaded by adopting a three-point bending method. The three-point bending method adopts two lower pressing heads 3 and one upper pressing head 2, wherein the two lower pressing heads 3 act on the skin surface of the aluminum alloy high-rib wallboard 1, and the two lower pressing heads 3 are respectively positioned at the edge positions of two sides of a to-be-formed area 5 for pre-bending loading. The upper pressure head 2 acts on the surface of the rib of the aluminum alloy high-rib wallboard 1, and the upper pressure head 2 is positioned in the middle of the pre-bending loaded area 5 to be formed. The region to be formed 5 subjected to the pre-bending loading is subjected to bending deformation by the cooperation of the upper ram 2 and the two lower rams 3.

The method comprises the steps of pre-bending and loading a to-be-formed area 5 through a three-point bending method, and enabling the to-be-formed area 5 to enter slight plasticity, wherein the slight plasticity means that the maximum plastic strain in the loaded aluminum alloy high-rib wallboard 1 is not more than 2%, and no damage such as indentation, scratch, microcrack and the like is generated on the surface of the aluminum alloy high-rib wallboard 1. In actual operation, the magnitude of the bending load applied to the aluminum alloy high-rib wall plate 1 can be determined by a finite element simulation method.

The three-point bending method for pre-bending loading has the advantages that: the short plate of the high-strength wallboard with large deformation resistance, which has limited forming capability and is difficult to bend when the wallboard is bent and formed by only depending on laser, can be overcome. By applying a pre-bending load to the region to be formed 5, the forming ability of laser bending can be improved. And the bending direction of the area 5 to be formed can be better controlled by matching the two lower pressing heads 3 and the upper pressing head 2, so that the bending efficiency and the bending precision are improved.

S3, scanning the elastic stress concentration rib parts entering the slightly plastic region to be formed 5 by using laser beams, wherein the elastic stress concentration rib parts in the region to be formed 5 can be determined by theoretical analysis or finite element simulation, and the finite element simulation is preferably used in the application. For the selection of the laser beam, the laser beam with high energy density uniformity and high absorption rate of the aluminum alloy material should be selected as much as possible, and the laser beam with the wavelength of 808nm emitted by the continuous wave semiconductor laser 4 is selected in the application. When the laser beam is used for scanning the aluminum alloy high-rib wallboard 1, the phenomena of melting, ablation and obvious oxidation do not occur on the surface of the aluminum alloy high-rib wallboard 1, and the temperature of the surface of the aluminum alloy high-rib wallboard 1 is preferably ensured to be within 400 ℃.

And S4, cooling the aluminum alloy high-rib wallboard 1 subjected to laser scanning to room temperature, unloading, and taking the aluminum alloy high-rib wallboard 1 out of the space between the two lower pressing heads 3 and the upper pressing head 2, so that the forming of the pre-bending loaded area 5 to be formed is completed.

S5, repeating the steps S2, S3 and S4 for the rest of the areas to be formed 5 in sequence, and obtaining the aluminum alloy high-rib wall plate 1 bending forming piece.

Preferred embodiment(s) of the invention

The invention provides a prestress laser bending forming method of an aluminum alloy high-rib wallboard 1, which comprises the following steps:

as shown in fig. 1, S1, five regions to be formed 5 are divided on the breadth of the aluminum alloy high-rib panel 1, the overall length and width of the aluminum alloy high-rib panel 1 is 1000mm × 950mm, the skin thickness is 3mm, the rib height is 30mm, and the rib width is 3 mm. The target profile is circular arc with a radius of curvature of 1675 mm. The wall panel is divided into 5 rectangular areas 5 to be formed, each area having a width of 240mm and an overlap 6 between adjacent areas having a width of 50 mm.

S2, selecting a region to be formed 5 in the middle of the aluminum alloy high-rib wallboard 1 for pre-bending loading, and setting the width of the span between the two lower pressing heads 3 to be 240mm as the width of the single region to be formed 5 during three-point bending. According to the three-point bending finite element simulation result of the aluminum alloy high-rib wallboard 1, the bending load is set to be 800kN, the maximum plastic strain of the bent aluminum alloy high-rib wallboard 1 is about 1%, and no damage such as indentation, scratch, microcrack and the like occurs on the surface.

As shown in fig. 2, S3, according to the finite element simulation, the elastic stress of the aluminum alloy high rib panel 1 is mainly concentrated on the upper surface of the rib and the root of the rib in the region 5 to be formed. The upper surface of the rib and the root of the rib are scanned by using a laser beam emitted by the continuous wave semiconductor laser 4, and the practically used main laser parameters take the following values: laser power 4000W, spot diameter 3mm, scanning speed 8 mm/s.

And S4, cooling the aluminum alloy high-rib wallboard 1 to be scanned to room temperature, and unloading the aluminum alloy high-rib wallboard to finish forming the area. In this embodiment, after the laser scanning is performed on the area 5 to be formed of the aluminum alloy high-strength panel 1, the aluminum alloy high-strength panel 1 is naturally cooled to room temperature of 25 ℃, and then is unloaded.

And S5, sequentially forming the rest areas to be formed 5 of the aluminum alloy high-rib panel 1, and thus obtaining the bent formed part of the aluminum alloy high-rib panel 1. In the embodiment, the areas to be formed 5 on two sides of the area to be formed 5 in the middle of the aluminum alloy high-rib wallboard 1 are alternately bent, and after all five areas to be formed 5 are bent and formed from the area to be formed 5 close to the middle to the area to be formed 5 far away from the middle, the aluminum alloy high-rib wallboard 1 with the outer profile curvature radius of 1675mm is obtained.

Principle of operation

Dividing a plurality of areas to be formed 5 on the breadth of the aluminum alloy high-rib wallboard 1; selecting any area 5 to be formed for pre-bending loading, so that the area 5 to be formed is slightly plastic; then, scanning the rib part with concentrated elastic stress in the slightly plastic region to be formed 5 by using laser beams; then cooling the aluminum alloy high-rib wallboard 1 to be subjected to laser scanning to room temperature, and unloading the aluminum alloy high-rib wallboard to finish forming the area to be formed 5 subjected to pre-bending loading; and then, repeating the steps S2, S3 and S4 for the rest of the area to be formed 5 in sequence, thus obtaining the aluminum alloy high-rib wall plate 1 bending forming piece.

In the description of the present application, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience in describing the present application and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present application.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.

Claims

1. The aluminum alloy high-rib wallboard prestress laser bending forming method is characterized by comprising the following steps of:

s1, dividing a plurality of areas (5) to be formed on the breadth of the aluminum alloy high-rib wallboard (1);

s2, selecting any one of the areas (5) to be formed for pre-bending loading, and enabling the area (5) to be formed to enter slight plasticity;

s3, scanning the positions of the ribs with elastic stress concentrated in the slightly plastic region (5) to be formed by using laser beams;

s4, after the laser scanning is finished, cooling the aluminum alloy high-rib wallboard (1) to room temperature, and then unloading to finish the forming of the pre-bending loaded area (5) to be formed;

s5, repeating the steps S2, S3 and S4 for the rest of the areas (5) to be formed in sequence, and obtaining the aluminum alloy high-rib wall panel (1) bending forming piece.

2. The aluminum alloy high rib wallboard prestress laser bending forming method of claim 1, wherein for step S1, an overlapping area (6) is formed between any one of the areas to be formed (5) and the adjacent area to be formed (5).

3. The aluminum alloy high rib wallboard prestress laser bending forming method of claim 2, wherein the area of the overlapping area (6) accounts for 10% -25% of the area (5) to be formed.

4. The aluminum alloy high-rib wallboard prestress laser bending forming method of claim 1, wherein aiming at the step S2, a three-point bending method is adopted to carry out pre-bending loading on the area (5) to be formed;

the three-point bending method adopts two lower pressing heads (3) and one upper pressing head (2), wherein the two lower pressing heads (3) act on the skin surface of the aluminum alloy high-rib wallboard (1), the two lower pressing heads (3) are respectively positioned at the edge positions of two sides of a to-be-formed area (5) for pre-bending loading, the upper pressing head (2) acts on the rib surface of the aluminum alloy high-rib wallboard (1), and the upper pressing head (2) is positioned in the middle of the to-be-formed area (5) for pre-bending loading; the upper pressing head (2) and the two lower pressing heads (3) are matched to enable a region (5) to be formed, which is subjected to pre-bending loading, to be subjected to bending deformation.

5. The aluminum alloy high-rib wallboard prestress laser bending forming method according to claim 4, wherein the magnitude of the bending load applied to the aluminum alloy high-rib wallboard (1) is determined through a finite element simulation method, the maximum plastic strain in the loaded aluminum alloy high-rib wallboard (1) is not more than 2%, and no damage such as indentation, scratch, microcrack and the like is generated on the surface of the aluminum alloy high-rib wallboard (1).

6. The aluminum alloy high rib wallboard prestress laser bending forming method of claim 1, wherein in step S3, the rib portion of the to-be-formed area (5) where the elastic stress is concentrated is determined by theoretical analysis or finite element simulation.

7. The aluminum alloy high rib wallboard prestress laser bending forming method of claim 1, wherein for step S4, the laser beam comprises a laser beam emitted by a continuous wave laser (4).

8. The aluminum alloy high rib wallboard prestress laser bending forming method of claim 1, wherein aiming at step S4, when the laser beam scans the aluminum alloy high rib wallboard (1), the melting, ablation and obvious oxidation phenomena are avoided on the surface of the aluminum alloy high rib wallboard (1).

9. The aluminum alloy high rib wallboard prestress laser bending forming method of claim 8, wherein for step S4, the laser beam scanning the aluminum alloy high rib wallboard (1) generally requires that the temperature of the surface of the aluminum alloy high rib wallboard (1) is within 400 ℃.