Anti-deformation fixing method for aluminum alloy plate

Abstract

This invention discloses a method for preventing deformation and fixing aluminum alloy sheets. The aluminum alloy sheet includes an outer plate and an inner plate. The method includes a positioning step, a folding step, a welding step, and a secondary welding step. In the positioning step, the outer plate and the inner plate are placed, with the edge of the outer plate extending beyond the inner plate. Folding adhesive is applied between the outer and inner plates, ensuring they are adhered and the space between them is filled with folding adhesive. The adhesive application extends beyond the edge of the inner plate. In the folding step, the outer plate is rolled along its edge, folding it towards the inner plate until a U-shaped wrapping portion is formed around the edge of the inner plate. The end edge of the U-shaped wrapping portion forms an overlap edge, and the surface of the outer plate that is not folded and adheres to the inner plate is the contact surface. In the welding step, several weld points are welded at intervals on the inner plate near the outer side of the overlap edge. In the secondary welding step, the weld points and the overlap edge of the outer plate are welded a second time to fix the outer and inner plates.

Description

Technical Field

[0001] This invention relates to the field of automobile manufacturing technology, and more specifically, to the field of welding machine technology for automobile body materials. Background Technology

[0002] In automobile manufacturing, lightweighting of the vehicle body is an inevitable trend in order to improve drivability, handling, and energy efficiency. Therefore, various vehicle body parts extensively utilize lightweight materials such as aluminum alloys, and structurally, hollow structures are gradually replacing solid structures. For example, sheet metal parts such as the hood, doors, and trunk use hollow structures composed of outer and inner panels. Aluminum alloys are chosen as the material for these sheet metal parts. While using aluminum alloys offers many advantages, such as lightweighting, its low melting point and susceptibility to deformation under heat affect the body forming process. Particularly for door hood parts, after the hemming process in the body shop and before the electrophoresis and baking processes in the paint shop, the lack of a strong connection between the inner and outer panels can easily cause relative movement, making the door hood parts susceptible to dimensional deformation under external forces, thus affecting the overall vehicle fit.

[0003] In existing technologies, the folding process used for aluminum alloy door covers is as follows:

[0004] Step 1: Apply adhesive and assemble. First, apply edge-folding adhesive to the edge of the outer or inner panel, then place the outer panel on the outside of the inner panel so that the outer panel and the inner panel are attached together and the edge of the outer panel extends outward relative to the edge of the inner panel.

[0005] Step Two: Use rollers or a folding mechanism to fold the edge of the outer panel towards the inner panel until the outer panel edge forms a contour that wraps around the inner panel edge. At this point, the folding adhesive is not yet cured, and positional movement can easily occur between the inner and outer panels. This can cause localized deformation of the door cover during subsequent painting, electrophoresis, and baking processes, resulting in vehicle-wide compatibility issues that are difficult to resolve.

[0006] To address these issues, during actual vehicle manufacturing, after the door hood is rolled and folded in the welding workshop, physical and chemical methods are used to connect the inner and outer panels of the door hood, increasing the strength of the parts and preventing deformation of the door hood dimensions during subsequent body adjustments and painting processes.

[0007] For steel door covers, there are many processing methods: single-sided welding, cold metal transfer arc welding (CMT), gel bonding (similar to a drying oven), and drying ovens. However, for aluminum door covers, due to the low melting point of aluminum, welding can easily cause the base material to melt, leading to adhesive explosion and connection failure. Therefore, the available connection and fixing methods are relatively limited. Currently, the most commonly used methods are drying ovens and mechanical pressure connections.

[0008] The drying oven process involves heating the parts in a drying oven to allow the adhesive in the folded area to cure in advance.

[0009] The main processes of the drying oven process are as follows:

[0010] Step 1: Use a special robotic arm to place the aluminum alloy door cover onto a high-precision material rack (within 2mm precision), and then manually push the material rack and the parts it carries to the door of the drying room.

[0011] Step 2: Preheat the drying room to approximately 160 degrees Celsius.

[0012] Step 3: The entire box of parts is transported to the drying oven via a special conveyor and heated for 20 minutes to complete the curing of the adhesive.

[0013] The drying oven process has many disadvantages: the equipment occupies a large area, and the investment and operating costs are extremely high. Moreover, the drying oven requires a large amount of fuel, mostly fossil fuels, resulting in significant emissions of VOCs and carbon dioxide. Additionally, it requires high precision (within 2mm) for the material racks holding the parts, and the optimization and debugging of the material bins takes a very long time.

[0014] The main process of mechanical pressure connection is as follows: a punch is pushed by a pneumatic pressure device to physically press the outer plate's rolled edge area towards the outer surface of the part, so that the rolled edge flange of the outer plate is embedded into the inner plate, thereby completing the connection and strengthening of the inner and outer plates. Figure 5 The metallographic structure diagrams of the inner and outer plates connected by a mechanical pressure connection process in the prior art are revealed. Figure 5 The image shown is a metallographic structure, so a photograph of the metallographic structure is used directly.

[0015] The disadvantages of mechanical pressure connection are: mechanical pressure can cause warping of the rolled flange and surface depressions. Furthermore, connections formed by stamping are not strong and have limited fixing effect. When the sheet metal area is large, relative movement can still occur, making it unsuitable for connecting large flat parts such as front covers. It is also currently not suitable for connecting and fixing aluminum alloy front covers. Summary of the Invention

[0016] The present invention aims to propose a welding technology that can reduce the problem of heat deformation of aluminum alloy sheets, thereby solving the problem of fixing large-area aluminum alloy sheets such as front covers through welding.

[0017] According to an embodiment of the present invention, a method for preventing deformation and fixing an aluminum alloy sheet is provided. The aluminum alloy sheet includes an outer plate and an inner plate. The method for preventing deformation and fixing includes:

[0018] Positioning steps: Place the outer panel and inner panel, with the edge of the outer panel extending beyond the inner panel. Apply folding adhesive between the outer panel and inner panel, ensuring the outer panel and inner panel are bonded together and the space between them is filled with folding adhesive. The folding adhesive application extends beyond the edge of the inner panel.

[0019] The folding step involves rolling the outer panel along its edge to fold it toward the inner panel until the edge of the outer panel forms a U-shaped wrapping part to wrap around the edge of the inner panel. The end edge of the U-shaped wrapping part forms an overlapping edge, and the surface of the outer panel that is not folded and is in contact with the inner panel is the contact surface.

[0020] The welding process involves welding several weld points at intervals on the outer side of the inner plate near the lap edge.

[0021] The secondary welding step involves welding the weld points and the overlapping edges of the outer panel a second time to secure the outer and inner panels.

[0022] In one embodiment, the cavities between the outer panel and the inner panel, and between the U-shaped wrapping part and the inner panel, are filled with edge-folding adhesive, and a glue-free area is reserved between the overlapping edge of the outer panel and the inner panel.

[0023] In one embodiment, the glue-free area between the overlapping edge of the outer panel and the inner panel is: an area between the overlapping edge of the outer panel and the inner panel that is at least 5mm away from the welding point and does not exceed the edge of the inner panel.

[0024] In one embodiment, the application range of the folding adhesive is: an area 10mm to the left and right of the welding point along the outer contour of the part.

[0025] In one embodiment, the weld points are located using machine vision technology and formed by welding equipment carried by a robot, with the weld points evenly distributed along the outer contour of the part.

[0026] In one embodiment, the distance between the solder joint and the overlapping edge of the outer panel is 0 to 2 mm.

[0027] In one embodiment, during the welding step, the wire feed speed is 2.9–3.3 m / min and the welding current is 49–51 A.

[0028] In one embodiment, during the secondary welding step, the wire feed speed is 5.0–5.6 m / min and the welding current is 62–64 A.

[0029] In one embodiment, the welding method used in the weld point welding step and the secondary welding step is cold metal transfer welding technology.

[0030] In one embodiment, during the welding process, the welding wire is perpendicular to the surface of the welding position in both the welding point welding step and the secondary welding step.

[0031] The anti-deformation fixing method for aluminum alloy sheets of this invention solves the problem of high operating costs while meeting the needs of large flat parts such as front covers. This method optimizes the control of heat input and distribution during welding, and utilizes cold metal transfer arc welding (CMT) equipment and visual guidance technology to successfully solve the problem of glue explosion caused by the melting of the base material due to the low melting point of aluminum alloy. The anti-deformation fixing method for aluminum alloy sheets of this invention ensures that there is no glue at a certain distance from the overlap edge of the outer plate between the inner and outer plates by setting an appropriate glue application amount. Then, through precise position guidance, the welding process is divided into two steps. Through repeated experiments and theoretical calculations, the first welding uses low current and low wire feed speed to thicken the inner plate of the part without melting. The second welding uses normal current and wire feed speed to complete the connection between the first point and the outer plate of the part. This ensures connection strength without causing glue explosion due to the melting of the base material, achieving stable quality. This method effectively solves the shortcomings of commonly used drying ovens or mechanical pressure connection methods, with low initial investment and operating costs, small footprint, and minimal pollution. Emissions are only a fraction of the VOCs and carbon dioxide pollutants of conventional methods. It also overcomes the problem of insufficient connection strength, which prevents its application to large flat parts such as front covers. Attached Figure Description

[0032] Figure 1 A flowchart of a method for preventing deformation and fixing aluminum alloy plates according to an embodiment of the present invention is disclosed.

[0033] Figure 2 and Figure 3 The implementation process of a method for preventing deformation and fixing aluminum alloy plates according to an embodiment of the present invention is disclosed.

[0034] Figure 4 The metallographic structure diagram of the inner and outer plates connected by the anti-deformation fixing method of aluminum alloy sheet according to an embodiment of the present invention is disclosed.

[0035] Figure 5 The metallographic structure diagrams of the inner and outer plates connected by mechanical pressure connection process in the prior art are revealed. Detailed Implementation

[0036] This invention proposes a method for preventing deformation and fixing aluminum alloy sheets. Figure 1 A flowchart of a method for preventing deformation and fixing aluminum alloy plates according to an embodiment of the present invention is disclosed. Figure 2 and Figure 3 The implementation process of a method for preventing deformation and fixing aluminum alloy sheets according to an embodiment of the present invention is disclosed. Combined with... Figure 1 , Figure 2 and Figure 3 The aluminum alloy sheet to which the anti-deformation fixing method of the present invention is applicable includes an outer plate 1 and an inner plate 2, as shown in the reference. Figure 1As shown, the anti-deformation fixing method includes:

[0037] S101. Positioning Step. Place the outer panel 1 and the inner panel 2, with the edge of the outer panel 1 extending beyond the inner panel 2. Apply folding adhesive 3 between the outer panel 1 and the inner panel 2. The outer panel 1 and the inner panel 2 are attached together, and the space between the outer panel and the inner panel is filled with folding adhesive 3. The application range of folding adhesive 3 extends beyond the edge of the inner panel 2.

[0038] S102, Folding Step. Roll the outer panel 1 along its edge, folding it towards the inner panel 2 until a U-shaped wrapping portion 4 is formed around the edge of the inner panel 2. The end edge of the U-shaped wrapping portion 4 forms an overlapping edge 5. The surface of the outer panel 1 that is not folded and is in contact with the inner panel is the contact surface. The structure of the outer and inner panels after the folding step is shown in the reference diagram. Figure 2 As shown. The cavities between the outer panel 1 and the inner panel 2, and between the U-shaped wrapping part 4 and the inner panel 2, are filled with edge-folding adhesive 3. A glue-free area is maintained between the overlapping edge 5 of the outer panel and the inner panel. In one embodiment, the glue-free area between the overlapping edge 5 of the outer panel and the inner panel is: an area between the overlapping edge 5 of the outer panel and the inner panel, at a distance of not less than 5mm from the welding point 6, and not exceeding the edge of the inner panel 2. Figure 2 In the example shown, the welding point is 6. In the space between the overlapping edge 5 and the inner panel 2, starting from the welding point 6 and moving towards the edge of the inner panel 2, there is an area of ​​at least 5 mm that is free of glue.

[0039] S103, Welding steps. Weld several weld points 6 at intervals on the outer side of the inner plate 2, near the lap edge 5, as follows: Figure 2 As shown. In one embodiment, the position of the weld point 6 is pre-designed and positioned. The weld points 6 are evenly distributed along the outer contour of the part, and are usually distributed at fixed intervals, which can be appropriately adjusted according to the specific shape of the outer contour of the part. In one embodiment, the weld points 6 are located by machine vision technology and formed by welding on the inner plate 2 by a robot carrying welding equipment. In one embodiment, the distance between the weld point 6 and the overlap edge 5 of the outer plate is 0-2mm. In the weld point welding step, cold metal transfer welding technology (CMT) is used, and the welding wire is perpendicular to the surface of the welding position. In one embodiment, the wire feed speed is 2.9-3.3m / min and the welding current is 49-51A. In one implementation, since the inner plate and the outer plate are welded and fixed by the present invention, the use of some edge-folding adhesive can be reduced. Usually, edge-folding adhesive is applied to the entire area of ​​the inner plate and the outer plate. In one embodiment of the present invention, edge-folding adhesive can be applied at intervals based on the weld point position. For example, the application range of edge-folding adhesive is: along the outer contour of the part, within an area 10mm to the left and right of the weld point.

[0040] S104, Secondary Welding Step. The weld point 6 and the lap edge 5 of the outer plate 1 are secondary welded to form a welded portion 7, which fixes the outer plate 1 and the inner plate 2. In the secondary welding step, cold metal transfer welding (CMT) technology is used, with the welding wire perpendicular to the surface of the welding position. In one embodiment, the wire feed speed during secondary welding is 5.0–5.6 m / min, and the welding current is 62–64 A. The structure of the outer and inner plates after secondary welding is shown in the reference diagram. Figure 3 As shown.

[0041] Figure 4 A metallographic structure diagram of the inner and outer plates connected by an anti-deformation fixing method for aluminum alloy sheets according to an embodiment of the present invention is shown. Figure 4 The image shown is a metallographic structure, so a photograph of the metallographic structure is used directly. Figure 4 A total of 20 cross-sectional metallographic images were revealed at the weld locations. Figure 4 The 20 welding points are numbered 1-20 to represent their locations. (Reference) Figure 4 As shown, when the aluminum alloy sheet is welded and fixed using the anti-deformation fixing method of the present invention, no explosion points or deformation of the aluminum alloy sheet occur.

[0042] The following are four specific implementation examples of the process:

[0043] First process implementation example:

[0044] Methods for preventing deformation and fixing aluminum alloy door covers. The aluminum alloy door cover includes an outer panel and an inner panel. The fixing steps are as follows:

[0045] 1) First apply edge-folding adhesive 3 to the outer panel 1 or the inner panel 2, then place the outer panel 1 on the outside of the inner panel 2 so that the outer panel 1 and the inner panel 2 are attached together and the edge of the outer panel extends out relative to the edge of the inner panel.

[0046] 2) Roll the outer panel 1 along the edge of the outer panel to fold it toward the inner panel until the edge of the outer panel forms a U-shaped wrapping part 4 to wrap the edge of the inner panel; the end edge of the U-shaped wrapping part 4 is called the overlapping edge 5; the surface of the outer panel that is not folded and is in contact with the inner panel is called the contact surface.

[0047] The cavities between the outer panel 1 and the inner panel 2, and between the U-shaped wrapping part 4 and the inner panel 2, are filled with folding adhesive 3. There is no adhesive between the overlapping edge 5 and the inner panel 2, or the adhesive is more than 5mm away from the welding point.

[0048] 3) Accurately locate the overlapping edge using vision technology, guide the robot to carry welding equipment to weld the first weld point 6 at multiple positions along the edge of the inner plate 2 outside the overlapping edge 5 and 0.5mm away from the overlapping edge, thereby increasing the thickness of the inner plate 2.

[0049] 4) Weld the first weld point 6 and the overlapping edge 5 of the outer panel to form the welded part 7, thereby fixing the alloy door cover.

[0050] The welding method used in steps 3) and 4) is cold metal transfer welding (CMT), and the welding wire is perpendicular to the surface of the welding position during the welding process.

[0051] The welding parameters for step 3) are as follows: the wire feed speed during welding is 2.9–3.3 m / min, and in this embodiment it is set to 3.0 m / min. The welding current is approximately 49–51 A, and in this embodiment it is set to 50 A.

[0052] The welding parameters for step 4) are as follows: the wire feed speed during welding is 5.0–5.6 m / min, and in this embodiment it is set to 5.2 m / min. The welding current is approximately 62–64 A, and in this embodiment it is set to 63 A.

[0053] Example of second process implementation:

[0054] Methods for preventing deformation and fixing aluminum alloy door covers. The aluminum alloy door cover includes an outer panel and an inner panel. The fixing steps are as follows:

[0055] 1) First apply edge-folding adhesive 3 to the outer panel 1 or the inner panel 2, then place the outer panel 1 on the outside of the inner panel 2 so that the outer panel 1 and the inner panel 2 are attached together and the edge of the outer panel extends out relative to the edge of the inner panel.

[0056] 2) Roll the outer panel 1 along the edge of the outer panel to fold it toward the inner panel until the edge of the outer panel forms a U-shaped wrapping part 4 to wrap the edge of the inner panel; the end edge of the U-shaped wrapping part 4 is called the overlapping edge 5; the surface of the outer panel that is not folded and is in contact with the inner panel is called the contact surface.

[0057] The cavities between the outer panel 1 and the inner panel 2, and between the U-shaped wrapping part 4 and the inner panel 2, are filled with folding adhesive 3. There is no adhesive between the overlapping edge 5 and the inner panel 2, or the adhesive is more than 5mm away from the welding point.

[0058] 3) Accurately locate the overlapping edge using vision technology, guide the robot to carry welding equipment to weld the first weld point 6 at multiple positions along the edge of the inner plate 2, 2mm away from the overlapping edge 5, on the outer side of the overlapping edge 5, thereby increasing the thickness of the inner plate 2.

[0059] 4) Weld the first weld point 6 and the overlapping edge 5 of the outer panel to form the welded part 7, thereby fixing the alloy door cover.

[0060] The welding method used in steps 3) and 4) is cold metal transfer welding (CMT), and the welding wire is perpendicular to the surface of the welding position during the welding process.

[0061] The welding parameters for step 3) are as follows: the wire feed speed during welding is 2.9–3.3 m / min, and in this embodiment it is set to 3.0 m / min. The welding current is approximately 49–51 A, and in this embodiment it is set to 51 A.

[0062] The welding parameters for step 4) are as follows: the wire feed speed during welding is 5.2–5.6 m / min, which is set to 5.6 m / min in this embodiment. The welding current is approximately 62–64 A, which is set to 64 A in this embodiment.

[0063] Third process implementation example:

[0064] Methods for preventing deformation and fixing aluminum alloy door covers. The aluminum alloy door cover includes an outer panel and an inner panel. The fixing steps are as follows:

[0065] 1) First apply edge-folding adhesive 3 to the outer panel 1 or the inner panel 2, then place the outer panel 1 on the outside of the inner panel 2 so that the outer panel 1 and the inner panel 2 are attached together and the edge of the outer panel extends out relative to the edge of the inner panel.

[0066] 2) Roll the outer panel 1 along the edge of the outer panel to fold it toward the inner panel until the edge of the outer panel forms a U-shaped wrapping part 4 to wrap the edge of the inner panel; the end edge of the U-shaped wrapping part 4 is called the overlapping edge 5; the surface of the outer panel that is not folded and is in contact with the inner panel is called the contact surface.

[0067] The cavities between the outer panel 1 and the inner panel 2, and between the U-shaped wrapping part 4 and the inner panel 2, are filled with folding adhesive 3. There is no adhesive between the overlapping edge 5 and the inner panel 2, or the adhesive is more than 5mm away from the welding point.

[0068] 3) Accurately locate the overlapping edge using vision technology, guide the robot to carry welding equipment to weld the first weld point 6 at multiple positions along the edge of the inner plate 2 outside the overlapping edge 5 and 1mm away from the overlapping edge, thereby increasing the thickness of the inner plate 2.

[0069] 4) Weld the first weld point 6 and the overlapping edge 5 of the outer panel to form the welded part 7, thereby fixing the alloy door cover.

[0070] The welding method used in steps 3) and 4) is cold metal transfer welding (CMT), and the welding wire is perpendicular to the surface of the welding position during the welding process.

[0071] The welding parameters for step 3) are as follows: the wire feed speed during welding is 2.9–3.3 m / min, and in this embodiment it is set to 3.0 m / min. The welding current is approximately 49–51 A, and in this embodiment it is set to 50 A.

[0072] The welding parameters for step 4) are as follows: the wire feed speed during welding is 5.2–5.6 m / min, and in this embodiment it is set to 5.2 m / min. The welding current is approximately 62–64 A, and in this embodiment it is set to 63 A.

[0073] Fourth process implementation example:

[0074] Methods for preventing deformation and fixing aluminum alloy door covers. The aluminum alloy door cover includes an outer panel and an inner panel. The fixing steps are as follows:

[0075] 1) First apply edge-folding adhesive 3 to the outer panel 1 or the inner panel 2, then place the outer panel 1 on the outside of the inner panel 2 so that the outer panel 1 and the inner panel 2 are attached together and the edge of the outer panel extends out relative to the edge of the inner panel.

[0076] 2) Roll the outer panel 1 along the edge of the outer panel to fold it toward the inner panel until the edge of the outer panel forms a U-shaped wrapping part 4 to wrap the edge of the inner panel; the end edge of the U-shaped wrapping part 4 is called the overlapping edge 5; the surface of the outer panel that is not folded and is in contact with the inner panel is called the contact surface.

[0077] The cavities between the outer panel 1 and the inner panel 2, and between the U-shaped wrapping part 4 and the inner panel 2, are filled with folding adhesive 3. There is no adhesive between the overlapping edge 5 and the inner panel 2, or the adhesive is more than 5mm away from the welding point.

[0078] 3) Accurately locate the overlapping edge using vision technology, guide the robot to carry welding equipment to weld the first weld point 6 at multiple positions along the edge of the inner plate 2 outside the overlapping edge 5 and 1.3mm away from the overlapping edge, thereby increasing the thickness of the inner plate 2.

[0079] 4) Weld the first weld point 6 and the overlapping edge 5 of the outer panel to form the welded part 7, thereby fixing the alloy door cover.

[0080] The welding method used in steps 3) and 4) is cold metal transfer welding (CMT), and the welding wire is perpendicular to the surface of the welding position during the welding process.

[0081] The welding parameters for step 3) are as follows: the wire feed speed during welding is 2.9–3.3 m / min, and in this embodiment it is set to 3.0 m / min. The welding current is approximately 49–51 A, and in this embodiment it is set to 50 A.

[0082] The welding parameters for step 4) are as follows: the wire feed speed during welding is 5.2–5.6 m / min, and in this embodiment it is set to 5.2 m / min. The welding current is approximately 62–64 A, and in this embodiment it is set to 63 A.

[0083] The anti-deformation fixing method for aluminum alloy sheets of this invention solves the problem of high operating costs while meeting the needs of large flat parts such as front covers. This method optimizes the control of heat input and distribution during welding, and utilizes cold metal transfer arc welding (CMT) equipment and visual guidance technology to successfully solve the problem of glue explosion caused by the melting of the base material due to the low melting point of aluminum alloy. The anti-deformation fixing method for aluminum alloy sheets of this invention ensures that there is no glue at a certain distance from the overlap edge of the outer plate between the inner and outer plates by setting an appropriate glue application amount. Then, through precise position guidance, the welding process is divided into two steps. Through repeated experiments and theoretical calculations, the first welding uses low current and low wire feed speed to thicken the inner plate of the part without melting. The second welding uses normal current and wire feed speed to complete the connection between the first point and the outer plate of the part. This ensures connection strength without causing glue explosion due to the melting of the base material, achieving stable quality. This method effectively solves the shortcomings of commonly used drying ovens or mechanical pressure connection methods, with low initial investment and operating costs, small footprint, and minimal pollution. Emissions are only a fraction of the VOCs and carbon dioxide pollutants of conventional methods. It also overcomes the problem of insufficient connection strength, which prevents its application to large flat parts such as front covers.

[0084] It should also be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention. The above embodiments are provided for those skilled in the art to implement or use the present invention. Those skilled in the art can make various modifications or changes to the above embodiments without departing from the inventive concept of the present invention. Therefore, the protection scope of the present invention is not limited to the above embodiments, but should be the maximum scope conforming to the innovative features mentioned in the claims.

Claims

1. A method for preventing deformation and fixing an aluminum alloy sheet, the aluminum alloy sheet comprising an outer plate and an inner plate, characterized in that, Methods for preventing deformation and fixing include: Positioning steps: Place the outer panel and inner panel, with the edge of the outer panel extending beyond the inner panel. Apply folding adhesive between the outer panel and inner panel, ensuring the outer panel and inner panel are bonded together and the space between them is filled with folding adhesive. The folding adhesive application extends beyond the edge of the inner panel. The folding step involves rolling the outer panel along its edge to fold it toward the inner panel until the edge of the outer panel forms a U-shaped wrapping part to wrap around the edge of the inner panel. The end edge of the U-shaped wrapping part forms an overlapping edge, and the surface of the outer panel that is not folded and is in contact with the inner panel is the contact surface. The welding process involves welding several weld points at intervals on the outer side of the inner plate near the lap edge. The secondary welding step involves welding the weld points and the overlapping edge of the outer plate a second time to fix the outer plate and the inner plate. The overlap edge and the inner plate have a glue-free area, and the distance between this glue-free area and the weld point is not less than 5mm and does not exceed the edge of the inner plate. In the weld point welding step, the welding parameters are a wire feed speed of 2.9~3.3m / min and a welding current of 49~51A. The first weld uses low current and low wire feed speed to thicken the inner plate without melting. In the second weld step, the welding parameters are a wire feed speed of 5.0~5.6m / min and a welding current of 62~64A. The second weld uses normal current and wire feed speed to connect the weld point and the outer plate of the part, ensuring connection strength and preventing the base material from melting and causing glue explosion, thus achieving quality stability. Both the weld point welding step and the second weld step use cold metal transfer welding technology, and the welding wire is perpendicular to the surface of the welding position during the welding process. The weld points are located using machine vision technology and welded by a robot carrying welding equipment. The weld points are evenly distributed along the outer contour of the part, and the distance between the weld point and the overlap edge is 0~2mm.

2. The method for preventing deformation and fixing aluminum alloy plates as described in claim 1, characterized in that, The cavities between the outer panel and the inner panel, and between the U-shaped wrapping part and the inner panel, are filled with edge-folding adhesive, and a glue-free area is left between the overlapping edge of the outer panel and the inner panel.

3. The method for preventing deformation and fixing aluminum alloy plates as described in claim 2, characterized in that, The area without glue between the overlapping edge of the outer panel and the inner panel is: the area between the overlapping edge of the outer panel and the inner panel, which is at least 5mm away from the welding point and does not exceed the edge of the inner panel.

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