A magnesium alloy double-walled panel forming method and a magnesium alloy double-walled panel

Abstract

The present application relates to a magnesium alloy double-wall plate forming method and a magnesium alloy double-wall plate, and belongs to the technical field of magnesium alloy processing, solving the problems of low connection quality and local thickness of products not meeting the standards and being prone to breaking in the existing forming process. The forming method comprises: preparing a magnesium alloy double-wall plate with an arc-shaped protruding portion on the side wall based on twice superplastic forming. Through the process strategy of two-stage superplastic forming, the present application effectively maintains the uniform distribution of the thickness at the vertex, avoids the local breaking problem caused by the excessively thin thickness at the vertex, and improves the strength and stability of the product. Through the accurate layout of the diffusion connection area and the reinforcing rib area, combined with the optimization design of the reinforcing rib structure, the present application further ensures the structural integrity of the wall plate and its stability during long-term use.

Description

Technical Field

[0001] This invention relates to the field of magnesium alloy processing technology, and in particular to a method for forming a magnesium alloy double-layer wall panel and a magnesium alloy double-layer wall panel. Background Technology

[0002] Rare earth magnesium alloys, as lightweight and high-strength materials, possess excellent high strength and lightweight properties, and have great potential in aerospace, military, and engineering structures. However, due to the close-packed hexagonal structure of magnesium alloys, the material itself has relatively low plasticity, and as an active metal, exposed surfaces are prone to oxide film formation. Furthermore, magnesium alloys react violently with nitrogen in the air at high temperatures, making them difficult to weld, thus posing a series of technical challenges during the forming process.

[0003] In practical applications, magnesium alloys can be used to manufacture lightweight wall panels. However, the inner and outer sides of these panels often have different shape and functional requirements. For example, a wall panel with a hollow, sealed cavity on the inner wall can be used to run cables or liquid pipelines. Current technology primarily uses traditional spot welding to manufacture rare-earth magnesium alloy double-layer wall panels. This process has met the requirements of lightweight and high strength to some extent, but it has some limitations. For instance, spot welding requires the panel and stiffening ribs to be formed separately before being joined and reinforced. Post-weld deformation leads to unstable manufacturing quality, especially noticeable in large-size and hollow structures. Furthermore, magnesium alloys are highly reactive and prone to oxidation, making welding difficult and further affecting the connection quality.

[0004] The combined diffusion bonding and superplastic forming process is a lightweight forming technology with advantages such as low cost and high efficiency. However, its application in the preparation of magnesium alloy double-layer wall panels also has drawbacks. On the one hand, during superplastic forming, the deformation thickness of the sheet material is uneven due to the influence of mold shape, process parameters, and sheet quality, especially in areas with large superplastic forming displacement, such as the apex of the superplastic structure, where the thickness is lower. When the forming thickness is thin, this area may even crack, which will seriously affect the overall strength and stability of the magnesium alloy double-layer wall panel. On the other hand, existing technologies often add rare earth elements to improve the mechanical properties of magnesium alloys, which increases the processing temperature. Due to thermal expansion, the apex of the superplastic structure is more prone to cracking after cooling, increasing the processing difficulty.

[0005] Therefore, in view of the problems and shortcomings of existing technologies, it is necessary to develop a new method for forming magnesium alloy double-layer panels to meet the ever-increasing requirements for product quality and performance. Summary of the Invention

[0006] Based on the above analysis, the present invention aims to provide a method for forming a magnesium alloy double-layer wall panel and a magnesium alloy double-layer wall panel, in order to solve at least one of the problems in the existing forming process, namely, low connection quality and easy breakage due to substandard local thickness of the product.

[0007] This invention discloses a method for forming a magnesium alloy double-layer wall panel, which includes preparing a magnesium alloy double-layer wall panel with arc-shaped protrusions on the sidewalls based on two superplastic forming processes.

[0008] Preferably, the molding method includes:

[0009] The stiffening plate and the diffused connection area of ​​the panel are fixedly connected to form a connection part based on the diffusion connection;

[0010] The non-diffusion-connected area of ​​the blank after diffusion connection is completed is subjected to the first superplastic forming to form a protrusion, so that the central area of ​​the protrusion protrudes and deforms relative to the plane where the connection is located to the target depth;

[0011] The blank that has completed the first superplastic forming is subjected to a second superplastic forming, so that the protrusions in each area are on the same arc surface, forming the arc-shaped protrusions of the ribs of the magnesium alloy double-layer wall panel.

[0012] Preferably, the protrusions in each region are located on the same arc surface, including:

[0013] The protrusions in each region are located in the central region of the protrusion and on the arc surface where the two ends of the protrusion are located.

[0014] Preferably, the molding method includes:

[0015] Step 1, billet pretreatment steps:

[0016] Divide the panel blank into diffusion connection area and reinforcing rib area;

[0017] Step 2, Diffusion Connection:

[0018] The diffusion connection area of ​​the panel and the diffusion connection of the stiffener plate are formed to form a connection part;

[0019] Step 3, First stage of superplastic molding:

[0020] Based on the pressure difference between the two sides of the stiffener plate area corresponding to the reinforcing rib area, the stiffener plate in the corresponding area before the connection part is formed is subjected to superplastic forming for the first time. This causes the central area of ​​the protrusion to deform relative to the plane where the connection part is located to the first target depth and be in the first position O. The two ends of the corresponding area of ​​the protrusion before the forming are denoted as the left end point P and the right end point P. ’ ;

[0021] Step 4, Second stage superplastic molding:

[0022] Based on the pressure difference between the two sides of the stiffener plate area corresponding to the reinforcing rib area, the stiffener plate in the protruding part area is subjected to a second superplastic forming, so that the central part of the protruding part protrudes and deforms relative to the plane where the connecting part is located to the second target depth, and is in the second position O. ’ And O ’ The stiffeners between P and O ’ With P ’ Deformation of the stiffeners between them, and with O ’ P, P ’ The curved surface is fitted and connected.

[0023] Preferably, the pretreatment step of the billet in step 1 includes:

[0024] S101: Use solder resist to delineate the diffusion bonding area and the reinforcing rib area;

[0025] S102: Match and seal one side of the panel blank and the stiffener blank.

[0026] Preferably, S102 further includes providing a ventilation groove in the reinforcing rib area of ​​the panel blank plate.

[0027] Preferably, step 1 further includes providing a copper-reinforced connection layer between the diffusion connection region and the blank plate of the stiffener.

[0028] Preferably, the provision of the copper reinforcement connection layer includes: applying copper powder solder paste to the diffusion connection area, or adding a copper intermediate layer between the blank plate of the panel and the blank plate of the stiffener.

[0029] Preferably, the diffusion connection in step 2 includes:

[0030] S201: After matching and closing the blank plates of the panel and the stiffener plate, vacuum treatment is applied to the joint surface of the two.

[0031] S202: Heat the blank plate of the panel and the blank plate of the stiffening plate to the target temperature;

[0032] S203: Apply pressure to the blank plates of the panel and the blank plates of the stiffening plate to complete the diffusion connection.

[0033] A magnesium alloy double-layer wall panel, prepared by the above-described forming method, includes a face panel and stiffening plates;

[0034] The panel and the stiffener are connected by a connecting part, and the unconnected areas of the panel and the stiffener form arc-shaped protrusions;

[0035] The arc-shaped protrusions and the connecting parts are provided in multiple ways; the arc-shaped protrusions are distributed on the surface of the stiffener plate and are spaced apart from the connecting parts.

[0036] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0037] 1. This invention utilizes a two-stage superplastic molding process to prepare arc-shaped protrusions, which, compared to existing technologies that use a single-stage superplastic molding process, effectively maintains a uniform thickness distribution at the apex. This significantly increases the material density and thickness at the arc-shaped apex, improving the uneven material thickness distribution during superplastic expansion and addressing density defects caused by excessively thin material at the apex. When the material encounters various loads and pressures during its use, the uniform thickness helps to disperse these stresses, thereby extending the material's service life and reducing the risk of accidental damage, providing a more controllable and precise method.

[0038] 2. The present invention adopts a triangular shape for the stiffening plate corresponding to the reinforcing rib area, which can reduce the expansion in the direction parallel to the stiffening plate compared with other shapes. It has the highest raw material density at the upper vertex (the highest point of protrusion), thereby improving the structural defects that are easily caused by the thin material at the highest point of the stiffening plate. In the final product, the arc-shaped protrusion of the stiffening plate has a more balanced stress distribution and higher strength.

[0039] 3. This invention addresses the structural design of magnesium alloy double-layer wall panels. By dividing the reinforcing rib area and the transition connection area, a precise layout is achieved. Combined with the optimized design of the reinforcing rib structure, the structural integrity of the wall panel and its stability during long-term use are further ensured.

[0040] 4. By introducing a copper interlayer, this invention solves the problem of oxide layer formation in magnesium alloys during diffusion bonding, thereby improving the bonding quality and strength of the diffusion bonding area and ensuring the overall quality of magnesium alloy parts.

[0041] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0042] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0043] Figure 1 This is a schematic diagram of the rare earth magnesium alloy double-layer wall panel of Embodiment 1 of the present invention;

[0044] Figure 2 This is a cross-sectional view of the rare earth magnesium alloy double-layer wall panel of Embodiment 1 of the present invention, AA side.

[0045] Figure 3 This is a process flow diagram of the method of the present invention;

[0046] Figure 4 This is a schematic diagram illustrating the division of the diffusion connection region and the reinforcing rib region in step 1 of the method of the present invention;

[0047] Figure 5a This is a top view of the blank plate for the panel of the present invention;

[0048] Figure 5b This is a side view of the blank plate of the panel of the present invention;

[0049] Figure 6 This is a schematic diagram of the blank plate for the stiffening plate of the present invention;

[0050] Figure 7a This is a schematic diagram of the overall structure of the diffusion connection mold of the present invention;

[0051] Figure 7b This is a top view of the lower mold of the diffusion connection mold of the present invention;

[0052] Figure 8 This is a front view of the lower mold of the diffusion connection mold of the present invention;

[0053] Figure 9a This is a schematic diagram of the first superplastic molding die structure of the present invention;

[0054] Figure 9b This is a bottom view of the upper mold of the first superplastic molding die of the present invention;

[0055] Figure 9c This is a schematic diagram of the superplastic cavity structure of the first segment of the superplastic molding die of the present invention;

[0056] Figure 10a This is a schematic diagram of the second superplastic molding die structure of the present invention;

[0057] Figure 10b This is a bottom view of the upper mold of the second superplastic molding die of the present invention;

[0058] Figure 10c This is a schematic diagram of the superplastic cavity structure of the second superplastic molding die of the present invention;

[0059] Figure 11a This is a schematic diagram of the rare earth magnesium alloy double-layer wall panel of Embodiment 2 of the present invention;

[0060] Figure 11b This is a cross-sectional view of the rare earth magnesium alloy double-layer wall panel AA side of Embodiment 2 of the present invention.

[0061] Figure label:

[0062] 001 - Magnesium alloy double-layer wall panel;

[0063] 1-Panel; 2-Stiffener; 201-Arched protrusion; 202-Connecting part; 3-Diffusion connection area; 4-Strengthening rib area; 5-First-level reinforcing rib structure; 6-Cavity;

[0064] 7-First stage superplastic molding die; 701-First stage superplastic upper die; 7011-First stage superplastic mold cavity; 702-First stage superplastic lower die;

[0065] 8-Secondary stiffener structure;

[0066] 9-Second stage superplastic molding die; 901-Second stage superplastic upper die; 9011-Second stage superplastic mold cavity; 902-Second stage superplastic lower die;

[0067] 10-Diffusion connection mold; 10a-Lower mold of diffusion connection mold; 10b-Upper mold of diffusion connection mold; 1001-High pressure air chamber; 1002-Annular sealing groove; 1003-Positioning terminal; 1004-Air guide pipe;

[0068] 12-Ventilation tube;

[0069] 13-Ventilation slot;

[0070] O - First position; O' - Second position; P - Left end point; P' - Right end point; H - Depth of high-pressure air chamber; l - Length of venting groove; h1 - Depth of venting groove; t1 - Width of venting groove; t - Width of annular sealing groove; h - Depth of annular sealing groove; W1 - Width of panel blank; L1 - Length of panel blank and lower mold of diffusion mold; L2 - Length of rib blank; W2 - Width of rib blank. Detailed Implementation

[0071] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0072] On the one hand, the present invention provides a magnesium alloy double-layer wall panel, such as Figure 1 and Figure 2 The magnesium alloy double-layer wall panel 001 includes

[0073] Panel 1, stiffener 2 and connecting part 202; panel 1 and stiffener 2 are connected by connecting part 202, and the unconnected area of ​​panel 1 and stiffener 2 forms an arc-shaped protrusion 201;

[0074] Multiple arc-shaped protrusions 201 and connecting portions 202 are provided; the arc-shaped protrusions 201 are distributed on the surface of the stiffener 2 and are spaced apart from the connecting portions 202;

[0075] A cavity 6 is formed between the arc-shaped protrusion 201 and the panel 1.

[0076] Specifically, the materials of panel 1 and stiffener 2 can be magnesium alloy, and they can be the same or different.

[0077] Understandably, the arc-shaped protrusion 201 and the connecting part 202 give one side wall of the double-layer wall panel a more complex curved surface structure, making it suitable for more scenarios and application fields.

[0078] On the other hand, the present invention provides a method for forming a magnesium alloy double-layer wall panel, comprising preparing a magnesium alloy double-layer wall panel with arc-shaped protrusions on the sidewalls based on two superplastic forming processes.

[0079] Specifically, the method for forming a magnesium alloy double-layer wall panel structure includes:

[0080] The rib plate 2 and the diffuse connection area of ​​the panel 1 are fixedly connected to form a connection part 202 based on the diffusion connection;

[0081] The non-diffusion-connected area of ​​the blank after diffusion connection is completed is subjected to the first superplastic forming to form a protrusion, so that the central area of ​​the protrusion protrudes and deforms relative to the plane where the connection part 202 is located to the target depth;

[0082] The blank that has completed the first superplastic forming is subjected to a second superplastic forming, so that the protrusions in each region are on the same arc surface, forming the arc-shaped protrusions 201 of the rib plate 2 of the magnesium alloy double-layer wall panel 001.

[0083] Compared with existing technologies, this invention uses a two-stage superplastic molding process strategy to prepare arc-shaped protrusions through a single superplastic molding process. This effectively maintains a uniform thickness distribution at the apex. When the material encounters various loads and pressures during its use, the uniform thickness helps to disperse these stresses, thereby extending the service life of the material and reducing the risk of accidental damage. This provides a more controllable and precise method.

[0084] Specifically, the protrusions in each region are located on the same arc surface, including:

[0085] The protrusions in each region are located in the central region of the protrusion and on the arc surface where the two ends of the protrusion are located.

[0086] Specifically, the forming method of magnesium alloy double-layer wall panel structure, such as Figures 3-11b As shown, it includes:

[0087] Step 1, billet pretreatment steps:

[0088] Divide the blank plate of panel 1 into a diffusion connection area 3 and a reinforcing rib area 4.

[0089] Step 2, Diffusion Connection:

[0090] The diffusion connection area 3 of the panel and the corresponding area of ​​the stiffener 2 before molding are diffusely connected to form a connection part.

[0091] Step 3, First stage of superplastic molding:

[0092] Based on the pressure difference between the two sides of the stiffener plate 2 corresponding to the stiffener region 4, the stiffener plate 2 in the region corresponding to the connection part 202 before molding is subjected to superplastic molding for the first time. This causes the central region of the protrusion to protrude and deform relative to the plane where the connection part 202 is located to the first target depth, and to be in the first position O. The two ends of the region corresponding to the protrusion before molding are denoted as the left end point P and the right end point P. ’ .

[0093] Step 4, Second stage superplastic molding:

[0094] Based on the pressure difference between the two sides of the stiffener plate 2 corresponding to the stiffener region 4, the stiffener plate 2 in the protruding region is superplastically formed a second time, so that the central region of the protruding part protrudes and deforms relative to the plane where the connecting part 202 is located to the second target depth and is in the second position O. ’ And O ’ Ribs 2 and O between P ’ With P ’ The stiffener 2 deforms and interacts with O. ’ P, P ’ The curved surface is fitted and connected.

[0095] Specifically, the depth of the second target is greater than or equal to the depth of the first target.

[0096] Specifically, the pretreatment steps for the billet in step 1 include:

[0097] S101: Use solder resist to divide the diffusion connection area 3 and the reinforcing rib area 4;

[0098] S102: Match and seal one side of the blank plate of panel 1 and the blank plate of stiffening plate 2.

[0099] Specifically, S101 includes applying a solder resist to the reinforcing rib region 4 to prevent subsequent diffusion connection between the reinforcing rib region 4 and the stiffening plate 2.

[0100] Specifically, such as Figure 5a , Figure 5b As shown, S102 includes setting a ventilation groove 13 in the reinforcing rib area 4 on the blank plate of panel 1; stacking the blank plate of panel 1 and the blank plate of reinforcing rib 2, sealing and welding the perimeter of the stacked blank plate of panel 1 and the blank plate of reinforcing rib 2, and welding a ventilation pipe 12 at the ventilation groove 13 position.

[0101] Specifically, the vent pipe 12 is located on the side of the billet assembly.

[0102] Preferably, multiple vent pipes 12 and vent slots 13 are provided and are arranged symmetrically along the center of panel 1.

[0103] During implementation, the vent pipe 12 is the only channel connecting the inside and outside of the billet assembly. If the vent pipe 12 is closed, the inside of the billet assembly will be sealed.

[0104] The ventilation groove 13 allows air to circulate between the blank plate of the panel 1 and the blank plate of the stiffening plate 2 inside the blank assembly; after the ventilation groove 13 and the ventilation pipe 12 are connected to an external air source, they can provide air pressure to the side where the blank plate of the panel 1 and the blank plate of the stiffening plate 2 are connected.

[0105] Specifically, in step 1, the diffusion connection area 3 and the reinforcing rib area 4 are first divided on the template, and then the diffusion connection area 3 and the reinforcing rib area 4 are divided on the blank plate of panel 1 using the template.

[0106] Specifically, in step 1, the solder resist can be hexagonal boron nitride ceramic (BN ceramic).

[0107] It should be noted that hexagonal boron nitride ceramic can hinder the diffusion of magnesium alloy in panel 1 and stiffener 2, thus acting as a solder resist.

[0108] Preferably, step 1 further includes providing a copper-reinforced connecting layer between the diffusion connection region 3 and the blank plate of the stiffener 2.

[0109] Specifically, setting a copper reinforcement connection layer includes: applying copper powder solder paste to the diffusion connection area 3, or adding a copper intermediate layer between the blank plate of panel 1 and the blank plate of stiffener 2.

[0110] It is understandable that during the diffusion bonding process, the copper-reinforced bonding layer can undergo a solid-state reaction with the magnesium alloy to generate a new phase, thereby completing the solid-state bonding, solving the oxide film problem, and improving the diffusion bonding strength.

[0111] Preferably, the pretreatment step in step 1 further includes pickling the blank plate of panel 1 and the blank plate of stiffening plate 2 to remove the oxide layer.

[0112] Specifically, the diffusion connection step in step 2 includes:

[0113] S201: After matching and closing the blank plates of panel 1 and stiffener 2, vacuum treatment is applied to the connecting surfaces of the two.

[0114] S202: Heat the blank plate of panel 1 and the blank plate of stiffening plate 2 to the target temperature;

[0115] S203: Apply pressure to the blank plate of panel 1 and the blank plate of stiffening plate 2 to complete the diffusion connection.

[0116] Understandably, the vacuum treatment in S201 can prevent oxidation, and the temperature can ensure a high atomic diffusion rate to achieve diffusion bonding.

[0117] Specifically, the vacuum level in S201 is less than 10. -2 Pa.

[0118] Specifically, the diffusion connection is carried out in the diffusion connection mold 10, which includes an upper diffusion connection mold 10b, a lower diffusion connection mold 10a, and a high-pressure air chamber 1001. When the upper diffusion connection mold 10b or the lower diffusion connection mold 10a is connected to the magnesium alloy double-layer wall panel 001, the high-pressure air chamber 1001 can adjust the air pressure to change the pressure applied to the magnesium alloy double-layer wall panel 001, so that the connecting part 202 of the stiffener 2 and the panel 1 diffusely connect to form a diffusion connection area.

[0119] Specifically, the high-pressure air chamber 1001 is provided with an air guide pipe 1004 at the top or bottom, and is connected to an external air pressure regulating device through the air guide pipe 1004.

[0120] Preferably, the upper mold 10b or lower mold 10a of the diffusion connection mold with high pressure chamber 1001 has an annular sealing groove 1002 surrounding the high pressure chamber 1001.

[0121] During implementation, the area of ​​the annular sealing groove 1002 is set to be smaller than that of the blank plate of panel 1, so that the blank plate of panel 1 is laid both inside and outside the annular area of ​​the annular sealing groove 1002. After the target temperature is reached, the blank plate of panel 1 flows to the annular sealing groove 1002, so that the high-pressure air chamber 1001 can only be connected to the outside through the air guide pipe 1004.

[0122] Specifically, the diffusion connection mold 10 has positioning terminals 1003 at both ends of the upper mold 10b and the lower mold 10a of the diffusion connection mold; the positioning terminals 1003 in the upper mold 10b of the diffusion connection mold have positioning through holes, and the positioning terminals 1003 in the lower mold 10a of the diffusion connection mold have positioning recesses on the same side, and the two can be matched and connected by positioning guide posts.

[0123] Specifically, the target temperature in S202 can be 400℃~450℃.

[0124] Specifically, the target temperature in S202 can be 400℃, 405℃, 410℃, 415℃, 420℃, 425℃, 430℃, 435℃, 440℃, 445℃, or 450℃.

[0125] Specifically, in S203, applying pressure to the blank plate of panel 1 and the blank plate of stiffener 2 includes: increasing the pressure of high-pressure air chamber 1001 to compress panel 1 towards stiffener 2, thereby causing diffusion connection region 3 to diffusely connect with stiffener 2.

[0126] Specifically, in S203, the pressure of the high-pressure gas used for diffusion connection is 5.0 MPa to 5.5 MPa, and the diffusion connection time is 180 min to 210 min.

[0127] Specifically, the pressure of the high-pressure gas in the diffusion connection of S203 can be 5.0MPa, 5.1MPa, 5.2MPa, 5.3MPa, 5.4MPa or 5.5MPa.

[0128] Specifically, the diffusion connection time in S203 can be 180 min, 185 min, 190 min, 195 min, 200 min, 205 min or 210 min.

[0129] It should be noted that the pressure of the high-pressure gas causes the two plates to fit together precisely and produce a certain amount of plastic deformation; the diffusion connection time ensures that the atoms diffuse sufficiently.

[0130] Specifically, in step 2, the amplification factor of the diffusion bonding mold is 13‰ to 16‰.

[0131] It should be noted that the advantage of this range of mold magnification factor is that the forming accuracy of the parts can be guaranteed within this range.

[0132] Preferably, the diffusion bonding mold can be made of ductile iron.

[0133] More preferably, the diffusion bonding mold can be made of medium silicon molybdenum ductile iron.

[0134] Specifically, the first superplastic forming in step 3 includes: adjusting the pressure inside the vent pipe 12 so that the air pressure between the reinforcing rib area 4 and the blank plate of the rib plate 2 is greater than the air pressure on the other side of the blank plate of the rib plate 2, and the first superplastic forming is achieved under the action of the pressure difference between the two sides.

[0135] It should be noted that after the diffusion connection is completed, only the area between the reinforcing rib area 4 and the blank plate of the rib plate 2 in the blank plate of panel 1 is connected to the vent pipe 12 and the vent groove 13. Therefore, only the blank plate area of ​​the rib plate 2 corresponding to the reinforcing rib area 4 can undergo the first superplastic forming under the action of air pressure difference. At this time, the diffusion connection area 3 and its corresponding blank plate area of ​​the rib plate 2 have achieved a tight diffusion connection.

[0136] Specifically, the first superplastic forming in step 3 includes: the blank plate of the rib plate 2 corresponding to the reinforcing rib area 4 undergoes plastic deformation under the action of the air pressure difference on its upper and lower sides.

[0137] Specifically, plastic deformation is achieved in the first superplastic forming mold 7; the first superplastic forming mold 7 includes: a superplastic upper mold 701 and a superplastic lower mold 702; the superplastic upper mold 701 and the superplastic lower mold 702 are matched and connected to form a superplastic forming mold cavity, and the blank plate of the rib plate 2 is superplastic formed for the first time in the superplastic forming mold cavity.

[0138] During implementation, when the blank plate at the non-diffusion connection area of ​​the stiffener 2 undergoes plastic deformation under the action of the air pressure difference on both sides, it can be formed along the inner wall of the superplastic forming mold cavity to obtain the target shape, such as forming the arc-shaped protrusion 201 of the stiffener 2.

[0139] In one feasible implementation, a superplastic upper mold 701 can be a concave mold, and correspondingly, a superplastic lower mold 702 is a convex mold, and the superplastic upper mold 701 is provided with a mold cavity for the first superplastic molding.

[0140] In another feasible implementation, a superplastic upper mold 701 can be a punch, and correspondingly, a superplastic lower mold 702 is a die, with the superplastic lower mold 702 having a cavity for the first superplastic molding.

[0141] In one feasible implementation, a superplastic lower mold 702 is a common flat mold; a superplastic upper mold 701 and a superplastic lower mold 702 are connected on the side with a recessed superplastic cavity 7011.

[0142] Preferably, the width of a superplastic mold cavity 7011 gradually decreases from the opening to the bottom.

[0143] Preferably, the cross-section of a superplastic mold cavity 7011 is triangular.

[0144] During implementation, when the blank plate of the rib plate 2 undergoes plastic deformation under the action of the air pressure difference on both sides, it can be formed by following the shape of the inner side wall of a superplastic mold cavity 7011 to obtain a rib plate protrusion with a triangular shape.

[0145] Compared with existing technologies, the triangular shape can reduce the expansion in the direction of parallel stiffener 2 compared with other shapes, and has the highest raw material density at the upper vertex (the highest point of protrusion), thereby improving the structural defects that are easily caused by the thin material at the highest point of the stiffener 2.

[0146] It is understandable that the expansion rate of a bladder-like object is different at different points during expansion. The expansion rate of the protruding apex, which is farthest from the air inlet, is the largest, and therefore the weakest. In actual expansion, when expanding in a rectangular cavity with a constant width, the expansion of the protruding apex requires expansion in both the direction parallel to rib 2 (lateral) and the direction perpendicular to rib 2 (longitudinal). However, when it is formed into a triangle, only expansion in the direction perpendicular to rib 2 (longitudinal) is required. The lateral distance between the protruding apex and the two ends of the air inlet remains unchanged, and expansion in the direction parallel to rib 2 (lateral) is not required. Therefore, in a triangular cross-section cavity, the expansion of the protruding apex results in the highest material density and thickness, which helps to improve the uniformity of material density distribution during thermoplastic expansion.

[0147] Specifically, a superplastic lower mold 702 is a punch, and a superplastic upper mold 701 is a die. Before mold closing, the blank assembly, punch and die are placed in a heating furnace to achieve temperature control.

[0148] Specifically, the first superplastic molding in step 3 includes:

[0149] S301: Place the diffusion-bonded magnesium alloy double-layer wall panel 001 into the first superplastic forming mold 7;

[0150] S302: Adjust the first superplastic molding die 7 to the target temperature;

[0151] S303: Adjust the pressure difference on both sides of the stiffener plate 2 corresponding to the reinforcing rib area 4 in the magnesium alloy double-layer wall panel 001 to achieve the first superplastic forming of the stiffener plate 2.

[0152] Specifically, placing the magnesium alloy double-layer wall panel 001 in the first superplastic molding mold 7 in S301 includes: setting the reinforcing rib area 4 in the magnesium alloy double-layer wall panel 001 to correspond with the first superplastic mold cavity 7011.

[0153] When implementing, such as Figure 9c As shown, the reinforcing rib area 4 and its corresponding rib plate 2 area are correspondingly set with a superplastic mold cavity 7011 in the direction of the rib plate 2 protrusion deformation, so that after the corresponding area of ​​the rib plate 2 is deformed, it can enter the superplastic mold cavity 7011 to complete the conformal shaping.

[0154] Specifically, the target furnace temperature in S302 is 280℃~300℃, which can be 280℃, 285℃, 287℃, 290℃, 293℃, 295℃, 298℃ or 300℃.

[0155] Specifically, adjusting the pressure difference between the two sides of the stiffening plate 2 corresponding to the reinforcing rib area 4 in the magnesium alloy double-layer wall panel 001 in S303 includes adjusting the air pressure between the reinforcing rib area 4 and the stiffening plate 2 through the vent pipe 12.

[0156] Specifically, the air pressure between the reinforcing rib area 4 and the stiffening plate 2 is 2.0MPa to 2.5MPa, and the pressure holding time is 30min to 40min.

[0157] It should be noted that the first stage of superplastic molding holding pressure of 2.0MPa to 2.5MPa can better utilize the pressure difference on both sides to deform it, and the holding time within the above range can achieve better mold adhesion and shaping of the rib plate 2.

[0158] In another feasible implementation, a superplastic upper mold 701 and a superplastic lower mold 702 are matching arc-shaped molds; before the second superplastic forming in step 3, the process also includes hot pressing the blank assembly to obtain an arc-shaped double-layer wall panel structure blank.

[0159] Specifically, the blank of the double-layer wall panel structure, the punch and the die are placed in the heating furnace and heated to 280℃~300℃. During the heating process, the blank assembly is placed on the punch. After the target temperature is reached, the die is closed to hot press the double-layer wall panel structure blank.

[0160] Specifically, the second superplastic forming in step 4 includes:

[0161] Adjust the pressure inside the vent pipe 12 so that the air pressure between the reinforcing rib area 4 and the blank plate of the rib plate 2 is greater than the air pressure on the other side of the blank plate of the rib plate 2, and achieve the second superplastic forming under the action of the pressure difference between the two sides.

[0162] It should be noted that after the second superplastic molding is completed, a cavity 6 is formed between the reinforcing rib area 4 and the blank plate of the corresponding rib plate 2. The cavity 6 can undergo a second superplastic molding under the action of air pressure difference.

[0163] Specifically, the second superplastic forming in step 4 includes: the blank plate of the rib plate 2 corresponding to the reinforcing rib area 4 undergoes a second plastic deformation under the action of the air pressure difference on its upper and lower sides.

[0164] Specifically, the second superplastic forming is achieved in the second superplastic forming mold 9; the second superplastic forming mold 9 includes: a second superplastic upper mold 901 and a second superplastic lower mold 902; the second superplastic upper mold 901 and the second superplastic lower mold 902 are matched and connected to form a superplastic forming mold cavity, and the protrusion of the rib plate 2 after the first superplastic forming is superplastic formed in the superplastic forming mold cavity.

[0165] During implementation, when the protrusion of the non-diffusion connection area of ​​the stiffener 2 undergoes plastic deformation under the action of the air pressure difference on both sides, it can be formed along the inner wall of the mold cavity of the second superplastic molding mold 9 to obtain the target shape, such as forming the arc-shaped protrusion 201 of the stiffener 2.

[0166] In one feasible implementation, the two-stage superplastic upper mold 901 can be a concave mold, and correspondingly, the two-stage superplastic lower mold 902 is a convex mold, and the two-stage superplastic upper mold 901 is provided with a mold cavity for the second superplastic forming.

[0167] In another feasible implementation, the two-stage superplastic upper mold 901 can be a punch, and correspondingly, the two-stage superplastic lower mold 902 is a die, and the two-stage superplastic lower mold 902 is provided with a mold cavity for the second superplastic forming.

[0168] For example, the second-stage superplastic lower mold 902 can be the same as the first-stage superplastic lower mold 702, which is a common flat mold; the second-stage superplastic upper mold 901 and the second-stage superplastic lower mold 902 are connected by a recessed second-stage superplastic cavity 9011.

[0169] Preferably, the cross-section of the two-section superplastic mold cavity 9011 is arc-shaped.

[0170] During implementation, when the blank plate of stiffener 2 undergoes plastic deformation under the action of air pressure difference on both sides, it can be formed a second time on the inner side wall of the second-stage superplastic mold cavity 9011, and the cross section changes from a triangular shape to an arc shape.

[0171] Compared with existing technologies, the arc-shaped protrusions of the stiffener plate 2 have a more balanced stress distribution and higher strength.

[0172] Compared with the prior art, the present invention adopts a method in which the stiffening plate 2 corresponding to the reinforcing rib region 4 undergoes a first superplastic forming into a triangular cross-section, and then undergoes a second superplastic forming into an arc cross-section. This method can greatly improve the material density and thickness at the arc vertex, improve the uneven material thickness distribution during the superplastic expansion process, and reduce the density defects caused by the material being too thin at the vertex.

[0173] It is understandable that when superplastic molding a cross-section triangle for the second time, the triangle apex and the two ends of the air inlet only need to conform to the inner wall of the arc mold for conformal molding. The triangle apex area does not need to be expanded or only needs to be expanded slightly. Therefore, it can avoid the material thinning and strength reduction caused by excessive expansion at the apex.

[0174] Specifically, the blank assembly, punch, and die are placed in a heating furnace to achieve temperature control.

[0175] To match the shape of the magnesium alloy double-layer wall panel preform after the first superplastic forming, the second-stage superplastic upper mold 901 and the second-stage superplastic lower mold 902 can be matching arc-shaped molds or flat molds.

[0176] Specifically, the second superplastic forming in step 4 includes:

[0177] S401: Place the magnesium alloy double-layer wall panel 001 after the second superplastic forming into the second superplastic forming mold 9;

[0178] S402: Adjust the second superplastic molding die 9 to the target temperature;

[0179] S403: Adjust the pressure difference on both sides of the stiffener plate 2 corresponding to the reinforcing rib area 4 in the magnesium alloy double-layer wall panel 001 to achieve the second superplastic forming of the stiffener plate 2.

[0180] Specifically, placing the magnesium alloy double-layer wall panel 001 in the second superplastic molding mold 9 includes: setting the reinforcing rib area 4 in the magnesium alloy double-layer wall panel 001 to correspond with the second superplastic mold cavity 9011.

[0181] When implementing, such as Figure 10c As shown, the reinforcing rib area 4 and its corresponding rib plate 2 area are set in the same direction as the two-stage superplastic mold cavity 9011 in the direction of the rib plate 2 protrusion deformation, so that the rib plate 2 in the corresponding area can enter the two-stage superplastic mold cavity 9011 to complete the conformal shaping after deformation.

[0182] Specifically, the target furnace temperature in S402 is 280℃~300℃, which can be 280℃, 285℃, 287℃, 290℃, 293℃, 295℃, 298℃ or 300℃.

[0183] Specifically, adjusting the pressure difference between the two sides of the stiffening plate 2 corresponding to the reinforcing rib area 4 in the magnesium alloy double-layer wall panel 001 in S403 includes adjusting the air pressure between the reinforcing rib area 4 and the stiffening plate 2 through the vent pipe 12.

[0184] Specifically, the air pressure between the reinforcing rib area 4 and the stiffening plate 2 is 2.0MPa to 2.5MPa, and the pressure holding time is 30min to 40min.

[0185] It should be noted that the holding pressure of the second stage superplastic molding is between 2.0MPa and 2.5MPa, which can better utilize the pressure difference between the two sides to deform it. The holding time is within the above range, which can make the rib plate 2 fit the mold and shape better.

[0186] Specifically, the cavity volume of the second-stage superplastic mold cavity 9011 is greater than the cavity volume of the first-stage superplastic mold cavity 7011, and the cavity height of the second-stage superplastic mold cavity 9011 is greater than or equal to the cavity height of the first-stage superplastic mold cavity 7011.

[0187] Preferably, the cavity height of the two-stage superplastic mold cavity 9011 is equal to the cavity height of the one-stage superplastic mold cavity 7011.

[0188] To better illustrate the present invention, the following embodiments are further provided:

[0189] Example 1

[0190] This embodiment provides a method for forming a magnesium alloy double-layer wall panel and a magnesium alloy double-layer wall panel.

[0191] The target part is as follows Figures 1-2 The rare earth magnesium alloy double-layer wall panel shown is flat and includes a panel 1 and a stiffener 2. The panel 1 and the stiffener 2 are partially fixedly connected and partially separated. The part of the stiffener 2 that is separated from the panel 1 forms a cavity 6, which is a reinforcing rib structure. In this embodiment, there are a total of 7 reinforcing rib structures arranged parallel to each other along the length direction on the target part. The reinforcing rib structures are arc-shaped from the side. The material of the panel 1 and the stiffener 2 is Mg-Gd-Y-Zn-Mn rare earth magnesium alloy.

[0192] like Figures 3-10c As shown, the molding method includes the following steps:

[0193] Step 1, billet pretreatment:

[0194] Processing of the blank plate for panel 1: The blank plate for panel 1 has dimensions of 1000mm × 600mm (L1 × W1) and a thickness of 1.5mm; Ventilation grooves 13 are machined on the surface that is in contact with the stiffener plate 2. The ventilation grooves 13 have a width t1 = 5mm, a depth h1 = 0.6mm, and a length l = 60mm; The surface of the blank plate for panel 1 is pickled; According to the design of the stiffener graphic, the blank plate for panel 1 is divided into a diffusion connection area 3 and a stiffener area 4;

[0195] Processing of the blank plate for stiffener 2: The blank plate size of stiffener 2 is 1000mm×600mm (L2×W2), and the thickness is 1.0mm; the surface of the blank plate of stiffener 2 is pickled.

[0196] Intermediate plate fabrication: The intermediate plate is made of copper. Based on the division of diffusion connection area 3 and reinforcing rib area 4, the intermediate plate is laser-cut to remove the parts that do not belong to diffusion connection area 3.

[0197] Apply solder resist: Apply BN solder resist to the surface of the blank plate of panel 1 to be bonded to the intermediate plate and stiffening plate 2.

[0198] Panel 1 blank plate diffusion connection area 3 welding assembly: The blank plate of panel 1, the middle plate and the blank plate of stiffening plate 2 are stacked in sequence, sealed and welded around the perimeter, and the ventilation pipe 12 is welded at the ventilation groove 13 position to obtain the blank assembly.

[0199] Step 2, Diffusion Connection:

[0200] Vacuum heating: The blank assembly is placed in the diffusion bonding mold 10, and the diffusion bonding mold 10 is heated. During the heating process, a vacuum is simultaneously drawn on both the diffusion bonding mold and the blank assembly, with a vacuum degree of less than 10. -2 Pa, heated to 400℃ and held at that temperature;

[0201] Diffusion connection: Under heat preservation conditions, high-pressure gas is applied to the high-pressure gas chamber 1001 at a pressure of 5.0 MPa. A vacuum is then created inside the billet assembly using the vent pipe 12, with a vacuum level less than 10. -2 Pa causes the blank plates of panel 1, intermediate plate, and stiffener plate 2 to diffuse and connect in the first diffusion connection area 3. The high-pressure air chamber depth H = 5 mm, the width of the annular sealing groove t = 2 mm, and the depth of the annular sealing groove h = 1 mm. The diffusion connection time is 200 min.

[0202] Step 3, First stage of superplastic molding:

[0203] The first superplastic molding die 7 is a flat die, including a superplastic upper die 701 and a superplastic lower die 702. The surface of the superplastic upper die 701 has a superplastic mold cavity 7011. The superplastic mold cavity 7011 has the same position and area as the reinforcing rib area 4 on the blank plate of the rib plate 2. The cross section of the superplastic mold cavity 7011 is triangular.

[0204] The blank assembly is placed into the first superplastic molding mold 7; during mold assembly, the rib plate 2 of the blank assembly is fitted with the first superplastic upper mold 701; after mold closing, high-pressure gas is loaded into the blank assembly, the gas pressure is 2.0MPa, and the pressure holding time is 30min, so that the reinforcing rib area 4 of the blank plate of the rib plate 2 that fits with the first superplastic mold cavity 7011 is superplastically molded into the first superplastic mold cavity 7011 by the gas expansion, forming the first-level reinforcing rib structure 5, and obtaining the first double-layer wall panel structure with panel 1 and rib plate 2;

[0205] Step 4, Second stage superplastic molding:

[0206] The second superplastic molding die 9 is a flat die, including a two-stage superplastic upper die 901 and a two-stage superplastic lower die 902, with shapes identical to the first-stage superplastic upper die 701 and the first-stage superplastic lower die 702, respectively. The lower die surface of the second superplastic molding die 9 has a two-stage superplastic cavity 9011, which has the same position and area as the reinforcing rib area 4 on the blank plate of the rib plate 2. The volume of the two-stage superplastic cavity 9011 is larger than that of the first-stage superplastic cavity 7011, and the cavity height of the two-stage superplastic cavity 9011 is the same as that of the first-stage superplastic cavity 7011. The interior of the two-stage superplastic cavity 9011 is semi-circular.

[0207] The first superplastic molding double-layer wall panel structure is placed into the second superplastic molding mold 9; during mold installation, the stiffener plate 2 corresponding to the stiffener area 4 cooperates with the two-stage superplastic mold cavity 9011, the first-level stiffener structure 5 enters the two-stage superplastic mold cavity 9011, and the vertex of the first-level stiffener structure 5 contacts the inner surface of the two-stage superplastic mold cavity 9011.

[0208] After mold closing, high-pressure gas is applied to the 12-vent pipe at a pressure of 2.0 MPa for 30 minutes. This causes the first-level reinforcing rib structure 5 to be superplastically molded into the second-stage superplastic mold cavity 9011 under the action of gas expansion, forming the second-level reinforcing rib structure 8. This results in a second-stage double-layer wall panel structure with a panel 1 and a rib plate 2, which is the target product.

[0209] Example 2

[0210] This embodiment provides a method for forming a magnesium alloy double-layer wall panel and a magnesium alloy double-layer wall panel.

[0211] The target part is as follows Figures 11a-11b The Mg-Li magnesium alloy double-layer wall panel shown is arc-shaped and includes a panel 1 and a stiffener 2. The panels 1 and 2 are partially fixedly connected and partially separated. The part of the stiffener 2 that is separated from the panel 1 forms a cavity 6, which is a reinforcing rib structure. In this embodiment, the target part has 6 reinforcing rib structures arranged parallel to each other along the length direction. The reinforcing rib structures are arc-shaped from the side. The materials of the panel 1 and the stiffener 2 are Mg-Li alloy.

[0212] like Figures 3-10c As shown, the molding method includes the following steps:

[0213] Step 1, billet pretreatment:

[0214] Processing of blank plate for panel 1: Figure 5a As shown, the blank plate of panel 1 has dimensions of L1 = 1000, W1 = 600, and thickness of 2mm; ventilation groove 13 is machined on the surface that is in contact with the stiffener 2, the ventilation groove 13 has a width of t1 = 5mm, a depth of h1 = 0.6mm, and a length of l = 60mm; the surface of the blank plate of panel 1 is pickled, and the surface that is in contact with the stiffener 2 is polished;

[0215] Treatment of the blank plate for stiffener 2: such as Figure 6 As shown, the blank size of stiffener 2 is L2=1000, W2=600, and thickness is 1mm; the surface of the blank of stiffener 2 is pickled and the surface that is in contact with the panel 1 is polished.

[0216] Sample making: The sample is made of ordinary aluminum alloy plate; according to the design of the reinforcing rib graphic, the sample is divided into diffusion connection area 3 and reinforcing rib area 4, and then the sample is laser-cut according to diffusion connection area 3;

[0217] Coating with copper solder paste: Copper solder paste is applied to the first diffusion connection area 3 on the blank plate of panel 1;

[0218] Welding assembly: Stack the blank plates of panel 1 and stiffener 2, seal and weld them around the perimeter, and weld the vent pipe 12 at the vent groove position to obtain the blank assembly.

[0219] Step 2, Diffusion Connection:

[0220] Vacuum heating: The billet assembly is placed into the diffusion bonding mold 10, which is made of ductile iron (medium silicon molybdenum) with a mold magnification factor of 13‰. The lower mold of the diffusion bonding mold 10 is as follows: Figures 7a-8 As shown, the mold edge has an annular sealing groove 1002, the high-pressure air chamber depth H = 3mm, the annular sealing groove width t = 1.5mm, and the annular sealing groove depth h = 1.5mm; the diffusion connection mold 10 is heated, and during the heating process, the diffusion connection mold and the blank assembly are simultaneously evacuated, with a vacuum degree less than 10. -2 Pa, heat to 400℃ and hold.

[0221] Diffusion connection: Under heat preservation conditions, high-pressure gas is applied to the high-pressure gas chamber 1001 at a pressure of 5.0 MPa. A vacuum is then created inside the billet assembly using the vent pipe 12, with a vacuum level less than 10. -2 Pa causes the blank plates of panel 1 and rib plate 2 to diffuse and connect in the first diffusion connection area 3, with a diffusion connection time of 180 min; the diffusion connection mold is as follows. Figures 7a-8 As shown.

[0222] Step 3, First stage of superplastic molding:

[0223] Hot pressing: The first superplastic molding mold 7 is an arc-shaped mold, with a lower mold being a punch and an upper mold being a die. Before closing the mold, the blank assembly, punch, and die are placed in a heating furnace and heated to 280°C. During the heating process, the blank assembly is placed on the punch. After reaching the target temperature, the mold is closed to hot press the blank assembly to obtain an arc-shaped blank assembly.

[0224] Superplastic forming: The surface of a superplastic upper mold 701 has a superplastic cavity 7011. The interior of the superplastic cavity 7011 is an isosceles triangle with a 90° apex and a radius of 5mm. After the mold is closed, high-pressure gas is applied to the interior of the blank assembly. The gas pressure is 1.0MPa and the holding time is 30min. The reinforcing rib area 4 of the blank plate of the rib plate 2 that matches the superplastic cavity 7011 is superplastically formed into the cavity of the superplastic cavity 7011 by the gas expansion, forming the first-level reinforcing rib structure 5, and obtaining the first double-layer wall panel structure with the panel 1 and the rib plate 2.

[0225] Step 4, Second stage superplastic molding:

[0226] The second superplastic molding die 9 is an arc-shaped die, including an upper die and a lower die, with shapes identical to the upper and lower dies of the first superplastic molding die 7. The surface of the second superplastic upper die 901 has a second superplastic mold cavity 9011, which has the same position and area as the reinforcing rib area 4 on the blank plate of the rib plate 2. The cavity volume of the second superplastic mold cavity 9011 is larger than that of the first superplastic mold cavity 7011, and the cavity height of the second superplastic mold cavity 9011 is slightly greater than that of the first superplastic mold cavity 7011. The interior of the second superplastic mold cavity 9011 is semi-circular with a dimension of r10.

[0227] The first double-layer wall panel structure is placed into the second superplastic molding mold 9; during mold assembly, the stiffener 2 of the first double-layer wall panel structure mates with the mold surface with the two superplastic mold cavities 9011, the first-level reinforcing rib structure 5 enters the cavity of the second superplastic mold cavity 9011, and the apex of the first-level reinforcing rib structure 5 contacts the inner surface of the cavity of the second superplastic mold cavity 9011.

[0228] After mold closing, high-pressure gas is applied inside the first double-layer wall panel structure. The gas pressure is 5MPa and the holding time is 200min. The first-level reinforcing rib structure 5 is superplastically formed into the second-level superplastic forming groove cavity under the action of gas expansion, forming the second-level reinforcing rib structure 8. The second double-layer wall panel structure with panel 1 and rib plate 2 is obtained, which is the target product.

[0229] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for forming a magnesium alloy double-layer wall panel, characterized in that, This includes the preparation of magnesium alloy double-layer wall panels with arc-shaped protrusions on the sidewalls based on two superplastic forming processes; The method for forming the magnesium alloy double-layer wall panel includes: Step 1, billet pretreatment steps: Divide the panel blank into diffusion connection area and reinforcing rib area; Step 2, Diffusion Connection: The diffusion connection area of ​​the panel and the diffusion connection of the stiffener plate are formed to form a connection part; Step 3, First stage of superplastic molding: Based on the pressure difference between the two sides of the stiffener plate area corresponding to the stiffener area, the stiffener plate in the corresponding area before the connection part is formed is superplastically formed for the first time, so that the central area of ​​the protrusion before the forming is deformed relative to the plane where the connection part is located to the first target depth and is in the first position. The two ends of the corresponding area before the forming of the protrusion are recorded as the left end point and the right end point. Step 4, Second stage superplastic molding: Based on the pressure difference between the two sides of the rib plate area corresponding to the reinforcing rib area, the rib plate of the protruding part area is superplastically formed for the second time, so that the central part of the protruding part protrudes and deforms relative to the plane where the connecting part is located to the second target depth and is in the second position. The rib plate between the second position and the left end point and the rib plate between the second position and the right end point are deformed and fit and connect with the arc surface where the second position, the left end point and the right end point are located. The first superplastic molding in step 3 includes: S301: Place the diffusion-bonded magnesium alloy double-layer wall panel into the first superplastic forming mold; S302: Adjust the temperature of the first superplastic molding die to 280℃~300℃; S303: Adjust the pressure difference on both sides of the stiffener plate corresponding to the stiffener area in the magnesium alloy double-layer wall panel to achieve the first superplastic forming of the stiffener plate; The second superplastic molding in step 4 includes: S401: Place the magnesium alloy double-layer wall panel after the second superplastic forming into the second superplastic forming mold; S402: Adjust the temperature of the second superplastic molding die to 280℃~300℃; S403: Adjust the pressure difference on both sides of the reinforcing rib in the reinforcing rib area of ​​the magnesium alloy double-layer wall panel to achieve the second superplastic forming of the rib.

2. The molding method according to claim 1, characterized in that, Step 1, the pretreatment steps for the billet, include: S101: Use solder resist to delineate the diffusion bonding area and the reinforcing rib area; S102: Match and seal one side of the panel blank and the stiffener blank.

3. The molding method according to claim 2, characterized in that, S102 also includes providing ventilation grooves in the reinforcing rib area of ​​the panel blank.

4. The molding method according to claim 2, characterized in that, Step 1 also includes setting a copper-reinforced connection layer between the diffusion connection region and the blank plate of the stiffener.

5. The molding method according to claim 4, characterized in that, The provision of the copper reinforcement connection layer includes: applying copper powder solder paste to the diffusion connection area, or adding a copper intermediate layer between the blank plate of the panel and the blank plate of the stiffener.

6. The molding method according to claim 1, characterized in that, The diffusion connections in step 2 include: S201: After matching and closing the blank plates of the panel and the stiffener plate, vacuum treatment is applied to the joint surface of the two. S202: Heat the blank plate of the panel and the blank plate of the stiffening plate to the target temperature; S203: Apply pressure to the blank plates of the panel and the blank plates of the stiffening plate to complete the diffusion connection.

7. A magnesium alloy double-layer wall panel, characterized in that, Prepared by the molding method according to any one of claims 1-6, comprising a panel and ribs; The panel and the stiffener are connected by a connecting part, and the unconnected areas of the panel and the stiffener form arc-shaped protrusions; The arc-shaped protrusions and the connecting parts are provided in multiple ways; the arc-shaped protrusions are distributed on the surface of the stiffener plate and are spaced apart from the connecting parts.

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