Titanium alloy large-thickness multi-layer mixed grid structure and forming method

Abstract

The invention discloses a titanium alloy large-thickness multi-layer mixed grid structure and a forming method, and relates to the field of lightweight structures, the titanium alloy large-thickness multi-layer mixed grid structure comprises at least one layer of grid structure unit, each layer of grid structure unit comprises an upper panel, a lower panel and a mixed grid structure between the two panels, the mixed grid structure is composed of a channel structure and a lattice structure, the channel structure is in an X shape, and the lattice structure is arranged between the upper panel and the lower panel. Openings in two ends of the X-shaped channel structure are respectively fixed with the upper panel and the lower panel; when the number of the grid structure units is not smaller than two, in every two adjacent layers of grid structure units, the upper face plate of one layer of grid structure unit is fixedly connected with the lower face plate of the other layer of grid structure unit. The non-uniform bearing characteristic is achieved, and the bearing performance and rigidity of the grid structure are improved.

Description

Technical Field

[0001] The present application belongs to the technical field of lightweight structures, and in particular relates to a titanium alloy thick multi-layer hybrid grid structure and a forming method. Background Art

[0002] With the continuous development of aerospace technology, related equipment has put forward higher requirements for structural lightweighting, and it is necessary to achieve maximum weight reduction under the premise of meeting service requirements. At present, most aerospace load-bearing structures use hollow structures to reduce weight.

[0003] Hollow structures often use a single quadrilateral rib grid with strong bearing capacity to meet the bearing requirements. However, for thick hollow parts, when the deformation capacity of the material is certain, the grid size needs to be increased to meet the formability, which reduces the grid density and thus reduces the bearing capacity of the structure. A single grid type has a large strength redundancy under non-uniform load conditions. A single quadrilateral rib grid structure can only achieve lightweight requirements, but cannot achieve functional settings, such as laying cables or pipes. Summary of the invention

[0004] The technical problem solved by the present application is: to overcome the shortcomings of the prior art, to provide a titanium alloy thick multi-layer hybrid grid structure and forming method, the thickness of the designed multi-layer hybrid grid structure far exceeds the thickness of the current common multi-layer structure. The structure is formed using superplastic forming diffusion bonding technology, and the material deformation is small, within the superplastic deformation capacity of most superplastic alloy materials. Different grid types are used in different areas of the structure, which has non-uniform load-bearing characteristics, which can maximize the material performance under non-uniform load conditions and achieve maximum weight reduction. The hybrid design of the lattice hollow structure and the X-shaped channel structure in the structure can realize the multifunctionality of the structure, such as fuel storage, cable laying, etc.

[0005] The technical solutions provided by this application are as follows:

[0006] A titanium alloy thick multi-layer hybrid grid structure includes grid structure units. Each grid structure unit includes an upper panel, a lower panel and a hybrid grid structure between the two panels. The hybrid grid structure consists of a channel structure and a lattice structure. The channel structure is X-shaped. The openings at both ends of the X-shaped channel structure are respectively fixed to the upper panel and the lower panel.

[0007] The lattice structure is a symmetrical double-layer pyramid structure, which includes a connection point between an upper panel and a lower panel, a plurality of upper fixing points on the upper panel, and a plurality of lower fixing points on the lower panel; an upper support foot is arranged between the upper fixing point and the connection point, a lower support foot is arranged between the lower fixing point and the connection point, one end of the upper support foot is fixedly connected to the upper fixing plate, and the other end is fixedly connected to the lower support foot at the connection point and other upper support feet, and one end of the lower support foot is fixedly connected to the lower fixing plate, and the other end is fixedly connected to the upper support foot at the connection point and other lower support feet.

[0008] An upper connecting plate and a lower connecting plate are provided at the connection point position, one end of the upper supporting leg is connected to the upper connecting plate, one end of the lower supporting leg is connected to the lower connecting plate, and the upper connecting plate and the lower connecting plate are fixedly connected.

[0009] The grid structure units are provided with at least one layer. When the grid structure units are provided with no less than two layers, in two adjacent layers of grid structure units, the upper panel of one layer of grid structure units and the lower panel of one layer of grid structure units are fixedly connected.

[0010] A method for forming a titanium alloy thick multi-layer hybrid grid structure, comprising:

[0011] S1: preparing blanks for an upper panel, a lower panel, a channel structure and a lattice structure; the blanks for the channel structure and the lattice structure include a first core plate and a second core plate;

[0012] S2: According to the channel structure and the lattice structure, solder resist is applied to the lower panel, the first core panel, the second core panel and the upper panel;

[0013] S3: assembling the blanks in the order of the lower panel, the first core panel, the second core panel and the upper panel, sealing the edges between the upper panel and the lower panel, and welding the air pipe between the upper panel and the lower panel to obtain the sealed welded parts;

[0014] S4: placing the sealed welding part into a forming mold, evacuating the space between the upper panel and the lower panel, pressurizing the outer sides of the upper panel and the lower panel, and performing gas pressure diffusion connection to obtain a diffusion part;

[0015] S5: In the forming mold of the diffusion part, the outer space of the upper panel and the lower panel is evacuated, and at the same time, high-pressure inert gas is filled into the space between the upper panel and the lower panel to perform superplastic forming to obtain a superplastic part.

[0016] In step S1, hollow areas and blank areas are alternately arranged on the first core board and the second core board, the hollow areas are provided with a plurality of hollow holes arranged in a dot matrix, a support leg is provided between two adjacent hollow holes, and the intersection of the plurality of support legs is a connecting plate.

[0017] In step S2, for the surface of the first core board facing the lower panel, its blank area is the solder resist coating area, and the leg positions of its hollow area are all solder resist coating areas. Among the connecting boards at both ends of each leg, one connecting board is the solder resist coating area, and the other connecting board is not coated with solder resist; for the surface of the first core board facing the second core board, the middle part of its blank area is not coated with solder resist, and in its hollow area, the leg positions are all solder resist coating areas. For the connecting board area, if the connecting board on the surface of the first core board facing the lower panel is the solder resist coating area, then the connecting board on the surface of the first core board facing the second core board is not coated with solder resist. If The surface of the connecting board on the first core board facing the lower panel is not coated with solder resist, then the surface of the connecting board on the first core board facing the second core board is the solder resist coating area; the surface of the second core board facing the upper panel is consistent with the solder resist coating area of ​​the surface of the first core board facing the lower panel, and the surface of the second core board facing the first core board is consistent with the solder resist coating area of ​​the surface of the first core board facing the second core board; the uncoated solder resist area on the surface of the lower panel facing the first core board is consistent with the uncoated solder resist area on the side of the first core board facing the lower panel; the surface of the upper panel facing the second core board is consistent with the solder resist coating area on the surface of the lower panel facing the first core board.

[0018] In step S4, the sealing parts are placed in the forming mold, the upper panel and the lower panel are evacuated, the outer sides of the upper panel and the lower panel are pressurized, and gas pressure diffusion connection is performed to obtain the diffusion parts. When there are n sealing parts, n>1, it includes: the forming mold includes an upper mold, n-1 pads and a lower mold arranged in sequence, and the n sealing parts are placed in sequence between the upper mold and the upper pad, between the lower mold and the lower pad, and between two adjacent pads. The upper panel of the upper sealing part and the inner wall of the upper mold form a cavity, the lower panel of the lower sealing part and the inner wall of the lower mold form a cavity, and a cavity is formed between two adjacent sealing parts. After the diffusion connection temperature is reached, high-pressure inert gas is filled into the cavity, and the internal cavity of the sealing parts is evacuated, so that the sealing parts are diffused and connected to obtain multiple diffusion parts.

[0019] In step S5, the diffusion part is in a forming mold, the outer space of the upper panel and the lower panel is evacuated, and high-pressure inert gas is filled between the upper panel and the lower panel to perform superplastic forming to obtain a superplastic part. When there are n sealing parts, n>1, it includes: evacuating the cavity and filling the internal cavity of the diffusion part with high-pressure inert gas to achieve superplastic forming to obtain a superplastic part.

[0020] After step S5, when there are n sealed parts and n>1, diffusion connection is performed between the grid structure units, and pressure is maintained to achieve diffusion connection between the upper and lower panels of superplastic parts of different layers.

[0021] In step S4, the sealing welding part is placed in a forming mold, and a vacuum is drawn between the upper panel and the lower panel, and the outer sides of the upper panel and the lower panel are pressurized to perform gas pressure diffusion connection to obtain a diffusion part. When there is only one sealing welding part, there are two methods:

[0022] Method 1: The forming mold includes two flat molds. A sealing welding part and a steel air bag are placed between the two flat molds. The steel air bag is located on one side of the sealing welding part. After the furnace is heated to the diffusion bonding temperature, high-pressure inert gas is filled into the steel air bag, and the internal cavity of the sealing welding part is evacuated, so that diffusion bonding occurs between the lower panel, the first core plate, the second core plate and the upper panel of the sealing welding part, and a single diffusion part is obtained;

[0023] Method 2: The forming mold includes an upper mold and a lower mold. The sealed welding part is placed between the upper mold and the lower mold. The upper panel of the sealed welding part and the inner wall of the upper mold form a cavity, and the lower panel of the sealed welding part and the inner wall of the lower mold form a cavity. After the temperature reaches the diffusion bonding temperature, high-pressure inert gas is filled into the cavity, and the internal cavity of the sealed welding part is evacuated, so that the sealed welding part undergoes diffusion bonding to obtain a single diffusion part.

[0024] In step S5, the diffusion part is in a forming mold, the outer space of the upper panel and the lower panel is evacuated, and the space between the upper panel and the lower panel is filled with high-pressure inert gas to perform superplastic forming to obtain a superplastic part. When there is one sealing welding part, it includes:

[0025] The diffusion part is placed between the upper die and the lower die, the upper panel of the sealed part and the inner wall of the upper die form a cavity, the lower panel of the sealed part and the inner wall of the lower die form a cavity, the cavity is evacuated, and high-pressure inert gas is filled between the upper and lower panels to perform superplastic forming to obtain a superplastic part.

[0026] In summary, this application at least includes the following beneficial technical effects:

[0027] The thickness of the multi-layer hybrid grid structure designed by the present invention far exceeds the thickness of the currently common multi-layer structure. The multi-layer hybrid grid structure of this patent has realized a two-layer grid structure with a thickness of 150mm.

[0028] The structure designed by the present invention is formed by adopting superplastic forming diffusion bonding technology, and the material deformation amount is small, which is within the superplastic deformation capacity range of most alloy materials with superplasticity.

[0029] The structure designed by the present invention adopts different grid types in different areas and has non-uniform load-bearing characteristics, which can maximize the material performance under non-uniform load conditions and achieve maximum weight reduction.

[0030] The hybrid design of the lattice hollow structure and the X-shaped channel structure in the structure designed by the present invention can realize the multifunctionality of the structure, such as fuel storage, cable laying, etc.

[0031] The hybrid design of the lattice hollow structure and the X-shaped channel structure in the structure designed by the present invention further improves the bearing performance and rigidity of the grid structure and has better formability, that is, the forming method is simple and easier to form. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of a thick multi-layer hybrid grid structure;

[0033] Figure 2 It is a schematic diagram of a thick multi-layer hybrid grid structure process part;

[0034] Figure 3 This is a schematic diagram of a thick multi-layer hybrid grid structure blank;

[0035] Figure 4 Schematic diagram of solder resist coating on core board and panel, where a is the lower surface of the first core board, b is the upper surface of the first core board, and c is the upper surface of the lower panel;

[0036] Figure 5 It is a schematic diagram of the diffusion of the blank plate;

[0037] Figure 6 It is a schematic diagram of the blank, cushion block and die assembly;

[0038] Figure 7 Schematic diagram of the forming mold.

[0039] Description of the accompanying drawings: 11, lower panel; 12, first core board; 121, hollow hole; 122, support foot; 123, connecting plate; 13, second core board; 14, upper panel;

[0040] 3. Channel structure; 4. Lattice structure;

[0041] 21. upper die; 211. air pipe groove; 22. cushion block; 23. lower die;

[0042] 5. Sealing parts; 6. Diffusion parts; 7. Steel air bags. DETAILED DESCRIPTION

[0043] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments disclosed in the present invention will be further described in detail below with reference to the accompanying drawings.

[0044] The present application discloses a titanium alloy thick multi-layer hybrid grid structure and a forming method. The titanium alloy multi-layer hybrid grid structure designed by the present invention is as follows: Figure 1 As shown in FIG. (a), it is composed of an upper panel 14, a lower panel 11, a channel structure 3, and a lattice structure 4. The lattice structure is a symmetrical double-layer pyramid shape, and the channel structure is an X-shape. The hybrid grid structure can be stacked multiple times to form an ultra-large thickness structure, such as Figure 1As shown in Figure (b).

[0045] Specifically, the titanium alloy multilayer hybrid grid structure includes at least one layer of grid structure units, each layer of grid structure units includes an upper panel 14 and a lower panel 11 parallel to each other, and an alternating V-shaped structure and a plurality of pyramid structures are arranged between the upper panel 14 and the lower panel 11, and the open end of the V-shaped structure is fixedly connected to the panel, and each pyramid structure includes a connecting plate 123 and a plurality of legs 122, one end of the legs 122 is fixedly connected to the panel, and the other end is close to each other in a direction away from the panel and connected to the edge of the connecting plate 123. The end positions of the V-shaped structures between two adjacent layers of panels are opposite and fixedly connected to form an X-shaped channel structure, and one end of the connecting plates 123 of the pyramid structures between two adjacent layers of panels are opposite, and the opposite connecting plates 123 are fixedly connected to form a double-layer pyramid shape.

[0046] The hybrid grid structure is integrally formed using diffusion bonding / superplastic forming technology. The process flow is as follows:

[0047] (1) Design the process part. Design the process allowance area on the part model to obtain the process part model. If only one layer of mixed grid structure is formed, it is only necessary to add a transition draft angle around the part model, such as Figure 2 If multiple layers of mixed grids are used, a spacer 22 can be added between each two layers of edge pressing areas to separate each layer of mixed grid structure, as shown in FIG. Figure 2 (b) as shown.

[0048] (2) Mould design and manufacturing. Design and manufacture the forming mould according to the designed process parts.

[0049] (3) Blank cutting. The blank is designed and prepared according to the structure to be prepared. The blanks of each layer of the mixed grid structure are as follows: Figure 3 As shown. The blank includes a lower panel 11, a first core plate 12, a second core plate 13 and an upper panel 14 arranged in sequence. Along the direction in which the V-shaped structure and the multiple pyramid structures are alternately arranged, the first core plate 12 and the second core plate 13 are alternately provided with hollow areas and blank areas. The hollow areas are provided with multiple hollow holes 121 arranged in a lattice. Between two adjacent hollow holes 121 are legs 122, and the intersection of the multiple legs 122 is a connecting plate 123; since the hollow holes 121 are distributed in a lattice, the connecting plates 123 are also distributed in a lattice. In this embodiment, the lattice arrangement of the hollow holes 121 is horizontally and vertically distributed, forming multiple columns of connecting plates 123. The blank needs to be surface treated after unloading to ensure that the surface is clean and free of oxidation.

[0050] (4) Solder resist coating. In order to form a hybrid grid structure, the non-diffusion connection area of ​​the sheet needs to be coated with solder resist. Figure 4As shown in a, b and c of the figure, the shaded area is the solder resist coating area. Specifically, taking the first core board 12 as an example, the side of the first core board 12 facing the lower panel 11 is the lower surface, and the side of the first core board 12 facing the second core board 13 is the upper surface. The blank area on the lower surface of the first core board 12 is the solder resist coating area, and the hollow area on the lower surface of the first core board 12, in every two adjacent columns of connecting boards 123, one column of connecting boards 123 is the solder resist coating area, and all the positions of the legs 122 are the solder resist coating areas; the blank area on the upper surface of the first core board 12 is not coated with solder resist only in the middle part, and in the hollow area on the upper surface of the first core board 12, all the positions of the legs 122 are the solder resist coating areas. For the connecting board 123 area, if the connecting board 1 23 is a solder resist coating area on one side of the lower surface of the first core board 12, then the connecting board 123 is not coated with solder resist on one side of the upper surface of the first core board 12. If the connecting board 123 is not coated with solder resist on one side of the lower surface of the first core board 12, then the connecting board 123 is a solder resist coating area on one side of the upper surface of the first core board 12; the uncoated solder resist area on the surface of the lower panel 11 facing the first core board 12 is consistent with the uncoated solder resist area on the side of the first core board 12 facing the lower panel 11. The side of the second core board 13 facing the upper panel 14 is the upper surface, and the side of the second core board 13 facing the first core board 12 is the lower surface; the upper surface of the second core board 13 is consistent with the coated area of ​​the lower surface of the first core board 12, the lower surface of the second core board 13 is consistent with the coated area of ​​the upper surface of the first core board 12, the lower surface of the upper panel 14 is consistent with the coated area of ​​the upper surface of the lower panel 11, and all surfaces of the pad 22 are coated with solder resist.

[0051] (5) Sealing. Sealing the periphery of the mixed grid structure blank, connecting the air pipe, and conducting an air tightness inspection. That is, the lower panel 11, the first core panel 12, the second core panel 13, and the upper panel 14 that constitute a layer of grid structure units are arranged in sequence, and their peripheries are sealed and welded. An air pipe is connected between the lower panel 11 and the upper panel 14, so that one end of the air pipe is connected to the area between the upper panel 14 and the lower panel 11, and the other end of the air pipe is connected to the outside world, to obtain the sealed welded part 5, and conduct an air tightness inspection.

[0052] (6) Diffusion bonding of blanks. There are two methods to achieve diffusion bonding of the various layers of blanks. One is to place a sealing part 5 and a steel air bag 7 between two flat molds. The steel air bag 7 is located on one side of the sealing part 5. Figure 5 As shown, after the furnace is heated to the diffusion connection temperature, high-pressure inert gas is filled into the steel air bag 7, and the internal cavity of the sealing welding part 5 is evacuated, so that the lower panel 11, the first core plate 12, the second core plate 13 and the upper panel 14 of the sealing welding part 5 are diffusely connected to obtain the diffusion part 6; secondly, a plurality of sealing welding parts 5, the cushion block 22 and the mold are pressed Figure 6As shown in the figure, the mold is loaded into the furnace, that is, the mold includes an upper mold 21 and a lower mold 23, and an annular spacer 22 can be optionally arranged between the upper mold 21 and the lower mold 23. The upper mold 21 and the lower mold 23 are provided with an air pipe groove for the air pipe to pass through, as shown in FIG. Figure 7 As shown, n diffusion parts 6 are loaded into the mold, and the mold includes an upper mold 21, n-1 gaskets 22 and a lower mold 23 arranged in sequence. In this embodiment, there are three sealing parts 5, and two gaskets 22 are provided. The edges of the three sealing parts 5 are placed in sequence between the upper mold 21 and the upper gasket 22, between the lower mold 23 and the lower gasket 22, and between two adjacent gaskets 22. The first cavity is formed between the upper mold 21 and the upper sealing part 5, and the second cavity and the third cavity are formed in sequence between the two adjacent sealing parts 5. The fourth cavity is formed between the lower mold 23 and the lower sealing part 5. After the temperature of diffusion connection is raised, the first cavity, the second cavity, the third cavity and the fourth cavity are filled with high-pressure inert gas, and the internal cavity of the sealing part 5 is evacuated, so that multiple sealing parts 5 are diffusely connected at the same time, and multiple diffusion parts 6 are obtained at the same time.

[0053] (7) Superplastic forming of diffusion component 6. If the method 1 described in (6) is used for diffusion bonding of the blank, if the diffusion component 6 has only one layer, the diffusion component 6 is placed between the upper mold 21 and the lower mold 23, and after reaching the superplastic forming temperature, a high-pressure inert gas is filled into the internal cavity of the diffusion component 6 to obtain a superplastic component. If the method 2 described in (6) is used for diffusion bonding of the blank, and the diffusion component 6 has multiple layers, then the method Figure 6 As shown, the first cavity, the second cavity, the third cavity and the fourth cavity are directly evacuated, and at the same time, the internal cavity of the diffusion part 6 is filled with high-pressure inert gas to realize superplastic forming of each layer of the blank to obtain a superplastic part.

[0054] (8) Mixed grid structure diffusion connection. After each layer of superplastic parts completes superplastic forming, it is necessary to maintain pressure to carry out the diffusion connection process between the upper panel 14 and the lower panel 11 of different layers of superplastic parts, and finally achieve the following Figure 1 (b) The formation of a thick grid structure as shown.

[0055] (9) Residue removal: The margin at the edge is removed by mechanical processing, and the spacer 22 is taken out and can be reused.

[0056] Specific implementation plan

[0057] This example provides a design and forming method for a titanium alloy thick hybrid grid structure. The material is TC4 titanium alloy, the diffusion bonding and superplastic forming temperature is 920℃, and the formed part is a box-shaped part (such as Figure 1 (b), the length is 400mm, the width is 300mm, and the thickness is 150mm. The specific steps are as follows:

[0058] First, design the process part. Design the process allowance area on the part model to obtain the process part model, such as Figure 1 As shown in FIG. (a), a multi-layer hybrid grid superposition structure is adopted, and a spacer 22 is added between the edge pressing areas of each two layers of the hybrid grid structure to separate each layer of the hybrid grid structure, such as Figure 1 As shown in Figure (b). The superplastic forming process of the structure is simulated, the size parameters are optimized, and the pressure-time curve is obtained.

[0059] Second, mold design and manufacturing. Design and manufacture the forming mold according to the designed process parts, such as Figure 5 , Figure 6 or Figure 7 shown.

[0060] Third, blank cutting. Blanks are designed and prepared according to the structure to be prepared. The blanks of each layer of the mixed grid structure are Figure 3 After the blank is cut, it needs to be surface treated to ensure that the surface is clean and free of oxidation.

[0061] Fourth, solder resist coating. In order to form a hybrid grid structure, the non-diffusion connection area of ​​the sheet needs to be coated with solder resist. Figure 4 As shown, the shaded area is the solder resist coating area. The upper surface of the second core board 13 is consistent with the lower surface coating area of ​​the first core board 12, the lower surface of the second core board 13 is consistent with the upper surface coating area of ​​the first core board 12, the lower surface of the upper panel 14 is consistent with the upper surface coating area of ​​the lower panel 11, and all surfaces of the pad 22 are coated with solder resist.

[0062] Fifth, seal welding. Seal welding is performed around the mixed grid structure blank, the air pipe is connected, and the air tightness is checked.

[0063] Sixth, the blank is diffused and connected. The sealed blank, the pad 22 and the mold are pressed Figure 6 As shown, the mold is loaded into the furnace, and the mold is closed when the temperature reaches 700℃, and the pressure is 10t. After the temperature continues to rise to the diffusion bonding temperature of 920℃, high-pressure inert gas is filled into the four cavities 1, 2, 3 and 4, and the gas pressure rises to 2MPa. The tonnage of the equipment increases with the increase of gas pressure, and the pressure is maintained for 2h. At the same time, the cavity inside the blank is evacuated, so that the blank undergoes diffusion bonding.

[0064] Seventh, superplastic forming of the blank. After the pressure holding is completed, the four cavities 1, 2, 3 and 4 are evacuated, and at the same time, high-pressure inert gas is filled into the internal cavity of the blank. According to the pressure-time loading curve obtained by simulation, the gas pressure is loaded to achieve superplastic forming of each layer of the blank.

[0065] Eighth, diffusion connection of mixed grid structure. After each layer of the blank is superplasticly formed, the pressure inside the blank is raised to 2MPa and maintained for 2h to carry out the diffusion connection process between the panels of different layers of the blank, and finally achieve the following Figure 1 (b) The formation of a thick grid structure as shown.

[0066] Ninth, cool down and take out of the oven. Cool down to below 400℃ and take out the parts.

[0067] Tenth, remove the excess. Use mechanical processing to remove the excess and take out the cushion block, which can be reused.

[0068] The contents not described in detail in this application specification belong to the common knowledge of those skilled in the art.

[0069] The present application is described in detail above in conjunction with specific implementation methods and exemplary examples, but these descriptions cannot be understood as limiting the present application. Those skilled in the art understand that, without departing from the spirit and scope of the present application, a variety of equivalent replacements, modifications or improvements can be made to the technical solution of the present application and its implementation methods, all of which fall within the scope of the present application. The scope of protection of the present application shall be subject to the attached claims.

Claims

1. A titanium alloy thick multi-layer hybrid grid structure, characterized in that: The invention comprises a grid structure unit, wherein each layer of the grid structure unit comprises an upper panel (14), a lower panel (11), and a mixed grid structure between the upper panel (14) and the lower panel (11), wherein the mixed grid structure is composed of a channel structure and a lattice structure, wherein the channel structure is X-shaped, and openings at both ends of the X-shaped channel structure are respectively fixed to the upper panel (14) and the lower panel (11).

2. The titanium alloy thick multi-layer hybrid grid structure according to claim 1, characterized in that: The lattice structure is a symmetrical double-layer pyramid structure, which comprises a connection point between an upper panel (14) and a lower panel (11), a plurality of upper fixing points on the upper panel (14), and a plurality of lower fixing points on the lower panel (11); an upper support foot (122) is arranged between the upper fixing point and the connection point, and a lower support foot (122) is arranged between the lower fixing point and the connection point; one end of the upper support foot (122) is fixedly connected to the upper fixing plate, and the other end is fixedly connected to the lower support foot (122) at the connection point and other upper support feet (122); one end of the lower support foot (122) is fixedly connected to the lower fixing plate, and the other end is fixedly connected to the upper support foot (122) at the connection point and other lower support feet (122).

3. The titanium alloy thick multi-layer hybrid grid structure according to claim 2, characterized in that: An upper connecting plate (123) and a lower connecting plate (123) are provided at the connection point, one end of the upper supporting leg (122) is connected to the upper connecting plate (123), one end of the lower supporting leg (122) is connected to the lower connecting plate (123), and the upper connecting plate (123) and the lower connecting plate (123) are fixedly connected.

4. The titanium alloy thick multi-layer hybrid grid structure according to claim 1, characterized in that: The grid structure units are provided with at least one layer. When the grid structure units are provided with no less than two layers, in two adjacent layers of grid structure units, the upper panel (14) of one layer of grid structure units and the lower panel (11) of one layer of grid structure units are fixedly connected.

5. A method for forming a titanium alloy thick multilayer hybrid grid structure according to any one of claims 1 to 4, characterized in that: include: S1: preparing the blanks of the upper panel (14), the lower panel (11), the channel structure and the lattice structure; The blank of the channel structure and the lattice structure comprises a first core plate (12) and a second core plate (13); S2: coating solder resist on the lower panel (11), the first core panel (12), the second core panel (13) and the upper panel (14) according to the channel structure and the lattice structure; S3: assembling the blanks in the order of the lower panel (11), the first core panel (12), the second core panel (13) and the upper panel (14), sealing the edges between the upper panel (14) and the lower panel (11), and welding the air pipe between the upper panel (14) and the lower panel (11) to obtain sealed welded parts; S4: placing the sealing welding part into a forming mold, evacuating the space between the upper panel (14) and the lower panel (11), pressurizing the outer sides of the upper panel (14) and the lower panel (11), and performing gas pressure diffusion connection to obtain a diffusion part; S5: In the forming mold of the diffusion part, the outer space of the upper panel (14) and the lower panel (11) is evacuated, and high-pressure inert gas is filled between the upper panel (14) and the lower panel (11), and superplastic forming is performed to obtain a superplastic part.

6. The method for forming a titanium alloy thick multi-layer hybrid grid structure according to claim 5, characterized in that: In step S1, hollow areas and blank areas are alternately arranged on the first core plate (12) and the second core plate (13), the hollow areas are provided with a plurality of hollow holes (121) arranged in a dot matrix, a support leg (122) is provided between two adjacent hollow holes (121), and the intersection of the plurality of support legs (122) is a connecting plate (123).

7. The method for forming a titanium alloy thick multi-layer hybrid grid structure according to claim 6, characterized in that: In the step S2, for the surface of the first core board (12) facing the lower panel (11), its blank area is a solder resist coating area, and the positions of the legs (122) in the hollow area are all solder resist coating areas. Among the connecting plates (123) at both ends of each leg (122), one connecting plate (123) is a solder resist coating area, and the other connecting plate (123) is not coated with solder resist; for the surface of the first core board (12) facing the second core board (13), the middle part of its blank area is not coated with solder resist, and in its hollow area, the positions of the legs (122) are All of them are solder resist coating areas. For the connecting plate (123) area, if the surface of the connecting plate (123) on the first core plate (12) facing the lower panel (11) is a solder resist coating area, then the surface of the connecting plate (123) on the first core plate (12) facing the second core plate (13) is not coated with solder resist; if the surface of the connecting plate (123) on the first core plate (12) facing the lower panel (11) is not coated with solder resist, then the surface of the connecting plate (123) on the first core plate (12) facing the second core plate (13) is a solder resist coating area; The surface of the second core board (13) facing the upper panel (14) is consistent with the solder resist coating area of ​​the surface of the first core board (12) facing the lower panel (11), and the surface of the second core board (13) facing the first core board (12) is consistent with the solder resist coating area of ​​the surface of the first core board (12) facing the second core board (13); The un-solder resist coated area on the surface of the lower panel (11) facing the first core board (12) is consistent with the un-solder resist coated area on the side of the first core board (12) facing the lower panel (11); and the surface of the upper panel (14) facing the second core board (13) is consistent with the solder resist coated area on the surface of the lower panel (11) facing the first core board (12).

8. The method for forming a titanium alloy thick multi-layer hybrid grid structure according to claim 5, characterized in that: In step S4, the sealing parts are placed in a forming mold, and a vacuum is drawn between the upper panel (14) and the lower panel (11). The outer sides of the upper panel (14) and the lower panel (11) are pressurized to perform gas pressure diffusion connection to obtain diffusion parts. When there are n sealing parts, and n>1, the forming mold includes an upper mold (21), n-1 pads (22) and a lower mold (23) arranged in sequence, and the n sealing parts are placed in sequence between the upper mold (21) and the upper pad (22), and the lower mold (23). A cavity is formed between the mold (23) and the pad (22) below and between two adjacent pads (22), the upper panel (14) of the upper sealing component and the inner wall of the upper mold (21), the lower panel (11) of the lower sealing component and the inner wall of the lower mold (23), and a cavity is formed between two adjacent sealing components. After the temperature reaches the diffusion bonding temperature, high-pressure inert gas is filled into the cavity, and the cavity inside the sealing component is evacuated, so that the sealing component is diffusion bonded to obtain a plurality of diffusion components.

9. The method for forming a titanium alloy thick multi-layer hybrid grid structure according to claim 8, characterized in that: In step S5, the diffusion part is placed in a forming mold, the outer space of the upper panel (14) and the lower panel (11) is evacuated, and a high-pressure inert gas is filled between the upper panel (14) and the lower panel (11), and superplastic forming is performed to obtain a superplastic part. When there are n sealed parts, and n>1, the method includes: The cavity is evacuated and high-pressure inert gas is simultaneously filled into the cavity inside the diffusion part to achieve superplastic forming to obtain a superplastic part.

10. The method for forming a titanium alloy thick multi-layer hybrid grid structure according to claim 9, characterized in that: After step S5, when there are n sealed parts and n>1, diffusion connection is performed between the grid structure units, and pressure is maintained to achieve diffusion connection between the upper panel (14) and the lower panel (11) of different layers of superplastic parts.

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