Superplastic forming / diffusion bonding method for multi-runner curved surface structure

Abstract

The invention discloses a superplastic forming / diffusion bonding method for a multi-runner curved surface structure, and belongs to the field of superplastic forming and diffusion bonding. The invention designs a multi-runner curved surface structural member, and provides a method for diffusion bonding by adopting an interlayer method in order to solve the problem of runner closing caused by excessive deformation of a multi-runner curved surface structure in a superplastic forming / diffusion bonding process. And the multi-runner curved surface structure superplastic forming / diffusion bonding technology is used for providing air pressure for the runner in the superplastic forming process. The method is suitable for the heat dissipation type structural part which is provided with an internal flow channel and is complex in geometrical shape, and the complex heat dissipation type structural part which is good in flow channel shape, uniform in wall thickness and good in mechanical property of a connection interface can be prepared at a time by adopting the superplastic forming technology of middle layer diffusion connection and pressurization assistance in the flow channel.

Description

Technical Field

[0001] The present invention belongs to the field of superplastic forming and diffusion bonding, and particularly relates to a method for superplastic forming / diffusion bonding of a multi-channel curved surface structure. Background Art

[0002] Superplastic forming / diffusion bonding (SPF / DB) is an advanced near-net shaping process that combines the advantages of diffusion bonding and superplastic forming. It can achieve high-precision forming of complex metal shapes and large-area seamless bonding through plastic deformation and solid-state diffusion reactions. The required forming pressure is small, and the residual stress of the prepared components is small. It has been widely used in the fields of aerospace, rail transit, electronics, etc. Especially for lightweight and high-performance structural components in the aerospace field, the SPF / DB combined process has unique technical advantages.

[0003] The SPF / DB technology is often used in the aerospace field to prepare multi-layer hollow structures, which can minimize the weight of the components to reduce energy consumption while ensuring the high performance of the components. With the in-depth application research of the SPF / DB technology, the development of multi-layer hollow structures has evolved from double-layer structures to three-layer, four-layer, and sandwich structures. However, the SPF / DB technology is less applied in the preparation of structural-functional integrated components. And with the rapid development of various industrial fields, the demand for such functional structural components is gradually increasing, and the heat dissipation structural components with channels inside are one of the most widely used functional structural components.

[0004] At present, there are many types of heat dissipation structural components. According to the structural form, they are mainly divided into tube type, fin type, plate type, etc. Among them, the tube type heat dissipation component combines multiple heat dissipation tubes and passes coolant through the tubes to achieve heat dissipation. The fin type heat dissipation component adds fins on the base material to increase the heat dissipation area to achieve heat dissipation. The plate type heat dissipation component consists of parallel metal plates to form narrow channels to increase the heat exchange area to achieve heat dissipation. And the heat dissipation effect is the most significant for the liquid cooling type heat dissipation component, such as the liquid cooling plate, whose internal flow channels are mostly welded by a bottom plate with water channels and a flat cover plate. However, the above heat dissipation components have simple shapes, and their structures generally only play a heat dissipation effect and are difficult to have other uses, so the application scenarios are limited. In the multi-channel curved surface structural component, the flow channels for heat dissipation are inside the component with a complex curved surface shape, which can be used for heat dissipation in the aerospace field. For example, as the missile shell, its structure acts as a shell while achieving a heat dissipation effect to reduce the phenomenon of excessive surface temperature of the shell caused by aerodynamic heating, reduce the thermal deformation and thermal stress generated by the shell structure, and improve the safety and reliability of the structure. If lightweight materials such as aluminum alloy are used to prepare this component, the weight of the aerospace vehicle can also be reduced, energy can be saved, and it has great competitive advantages in the aerospace field, further enriching the application scenarios. In addition, since the components manufactured by the SPF / DB technology generally do not rebound, the quality of the formed parts is relatively high, the forming stability is good, and the design freedom is large, so there are certain advantages when preparing the multi-channel curved surface heat dissipation structural component.

[0005] In the preparation of the multi-channel curved surface structure, due to the existence of internal flow channels, it is very difficult to directly form by traditional processing methods. When using the SPF / DB process for forming, due to the weak bearing capacity of the flow channel area, if the process specification parameters are too large, it is easy to cause the deformation and collapse of the internal flow channels of the component, reducing the heat dissipation effect of the component. If the process specification parameters are too small, it is easy to cause problems such as insufficient diffusion connection and incomplete sheet metal die fitting. Moreover, during the superplastic forming process of the multi-channel curved surface structure, the deformation degree of the sheet metal is relatively large, and the flow channels may be closed due to the large deformation of the sheet metal, which also affects the wall thickness uniformity. Therefore, solving the problem of flow channel closure caused by excessive deformation of the internal flow channels of the multi-channel curved surface structure during the superplastic forming / diffusion connection process is the key to the superplastic forming / diffusion connection technology of the multi-channel curved surface structure. Summary of the Invention

[0006] In order to solve the above technical problems, the present invention provides a method for superplastic forming / diffusion connection of a multi-channel curved surface structure.

[0007] The present invention designs a multi-channel curved surface structural component, and in order to solve the problem of flow channel closure caused by excessive deformation of the multi-channel curved surface structure during the superplastic forming / diffusion connection process, a method for superplastic forming / diffusion connection of the multi-channel curved surface structure is provided, which uses an intermediate layer method for diffusion connection and provides air pressure to the flow channels during the superplastic forming process.

[0008] A method for superplastic forming / diffusion bonding of a multi-channel curved surface structure is specifically completed in the following steps:

[0009] 1. Mill out a plate with multiple grooves, make a mask plate according to the shape of the grooves on the plate, and use the mask plate to cut off the middle layer of the groove area on the plate to obtain the milled grooved plate and the cut middle layer;

[0010] 2. Take two milled grooved plates, grind their surfaces to make them smooth, remove surface oil stains, and then ultrasonically clean them and the cut middle layer, and dry them with cold air to obtain the grooved plates and the middle layer to be used;

[0011] 3. Place the middle layer to be used between two grooved plates to be used, align the grooves on the two plates to form a flow channel; connect an air pipe to the flow channel opening, and then weld the two plates, the middle layer and the air pipe to obtain a welded plate;

[0012] Fourth, spraying an isolation agent on the outer surface of the welded plate to obtain an isolation agent-sprayed welded plate;

[0013] 5. placing the forming die in a superplastic forming / diffusion bonding device, and heating the superplastic forming / diffusion bonding device to a diffusion bonding process section temperature;

[0014] 6. Placing the welded plate sprayed with the isolation agent in a forming mold in a superplastic forming / diffusion bonding equipment that has reached the temperature of the diffusion bonding process section;

[0015] 7. Heat up the superplastic forming / diffusion bonding equipment again and evacuate through the upper die external air pipe. After the forming die reaches the temperature of the diffusion bonding process section, keep it warm for a period of time, then ventilate through the exhaust hole of the lower die to pressurize the lower surface of the sheet for diffusion bonding. After reaching the set air pressure value, keep it warm and pressurized for a period of time.

[0016] 8. After the diffusion connection is completed, stop ventilation, heating, and vacuuming;

[0017] 9. After the temperature of the forming mold drops to the temperature of the superplastic forming process section, it is kept warm for a period of time, and then the plate is superplasticly formed through the air pipe connected to the upper mold and the air pipe at the runner port. After reaching the set air pressure value, the temperature and pressure are kept for a period of time;

[0018] 10. After superplastic forming and die pasting, ventilation and heating are stopped, and the parts are cooled with the furnace, and the parts are taken out after cooling to obtain multi-channel curved surface structural parts.

[0019] The beneficial effects of the present invention are:

[0020] The present invention provides a method for superplastic forming / diffusion bonding of a multi-channel curved surface structure. Compared with the prior art, the present invention has the following advantages:

[0021] (1) The first stage of the method provided by the present invention is the diffusion bonding stage of the multi-channel structure. The dissimilar metal foil (copper foil) in the channel area is used as the intermediate layer, and an element concentration gradient is constructed at the interface, which can react with the substrate to form a transition phase to promote the diffusion stage, reduce the process parameters, and reduce the degree of channel deformation and collapse.

[0022] (2) The second stage of the method provided by the present invention is the superplastic forming stage of the multi-channel curved surface structure. During the superplastic forming process of the sheet, internal air pressure is applied to the channels, which can offset the channel deformation caused by the large deformation of the sheet, maintain the basic shape of the channels, and thus ensure the heat dissipation effect of the component.

[0023] (3) In the diffusion bonding stage of the multi-channel structure of the present invention, the shape of the intermediate layer matching the grooved sheet is used to eliminate the influence of the intermediate layer on the channel area. While reducing the process parameters, the quality of the diffusion bonding interface is improved, the mechanical properties of the joint are enhanced, which is helpful for the subsequent superplastic forming stage, and the safety of the multi-channel curved surface heat dissipation component is improved, thereby improving the overall quality of the forming.

[0024] (4) During the superplastic forming process of the multi-channel curved surface structure of the present invention, internal air pressure is applied to the channels, which ensures the basic shape of the channels. While improving the heat dissipation effect of the component, it avoids the reduction of the wall thickness caused by the channel collapse, greatly improves the wall thickness uniformity of the component, and is conducive to the preparation of high-quality multi-channel curved surface heat dissipation structural parts.

[0025] (5) The present invention is suitable for heat dissipation structural parts with internal channels and complex geometric shapes. By adopting the superplastic forming technology assisted by intermediate layer diffusion bonding and internal pressurization of the channels, complex heat dissipation structural parts with good channel shape, uniform wall thickness, and good mechanical properties of the bonding interface can be prepared at one time. Brief Description of the Drawings

[0026] Figure 1 Schematic diagram of the diffusion bonding stage and the superplastic forming stage of Example 1;

[0027] Figure 2 Schematic diagram of the spraying situation of the release agent on the upper and lower outer surfaces of the sheet after welding in Example 1;

[0028] Figure 3 Three-dimensional wireframe diagram of the forming effect of Example 1;

[0029] Figure 4 Three-dimensional model diagram of the forming effect of Example 1;

[0030] Figure 5 Three-dimensional model sectional view of the forming effect of Example 1;

[0031] Figure 6This is a digital photo of a multi-channel curved surface structure including a process section in Example 1;

[0032] Figure 7 This is a digital photo of the reverse side of the multi-channel curved surface structural component of Example 1;

[0033] Figure 8 This is a digital photo of the front side (channel side) of the multi-channel curved surface structural component of Example 1;

[0034] Figure 9 This is a graph showing the thickness variation of the cross section of Example 1;

[0035] Figure 10 This is a comparison chart of the tensile properties of the formed part of Example 1 and the original base material;

[0036] In the figure, 1 is the grooved plate, 2 is the middle layer, 3 is the upper die of the forming die, and 4 is the lower die of the forming die. DETAILED DESCRIPTION

[0037] Specific implementation method 1: This implementation method is a method for superplastic forming / diffusion bonding of a multi-channel curved surface structure, which is specifically completed according to the following steps:

[0038] 1. Mill out a plate with multiple grooves, make a mask plate according to the shape of the grooves on the plate, and use the mask plate to cut off the middle layer of the groove area on the plate to obtain the milled grooved plate and the cut middle layer;

[0039] 2. Take two milled grooved plates, grind their surfaces to make them smooth, remove surface oil stains, and then ultrasonically clean them and the cut middle layer, and dry them with cold air to obtain the grooved plates and the middle layer to be used;

[0040] 3. Place the middle layer to be used between two grooved plates to be used, align the grooves on the two plates to form a flow channel; connect an air pipe to the flow channel opening, and then weld the two plates, the middle layer and the air pipe to obtain a welded plate;

[0041] Fourth, spraying an isolation agent on the outer surface of the welded plate to obtain an isolation agent-sprayed welded plate;

[0042] 5. placing the forming die in a superplastic forming / diffusion bonding device, and heating the superplastic forming / diffusion bonding device to a diffusion bonding process section temperature;

[0043] 6. Placing the welded plate sprayed with the isolation agent in a forming mold in a superplastic forming / diffusion bonding equipment that has reached the temperature of the diffusion bonding process section;

[0044] VII. Heat up the superplastic forming / diffusion bonding equipment again and evacuate the air through the external air pipe of the upper die. After the forming die reaches the temperature of the diffusion bonding process section, keep it warm for a period of time, and then pressurize the lower surface of the sheet by ventilating through the exhaust holes of the lower die to perform diffusion bonding. After reaching the set air pressure value, keep it warm and pressurized for a period of time;

[0045] VIII. After the diffusion bonding is completed, stop ventilating and heating, and stop evacuating the air;

[0046] IX. After the temperature of the forming die drops to the temperature of the superplastic forming process section, keep it warm for a period of time, and then ventilate the sheet through the external air pipe of the upper die and the air pipe at the runner opening to perform superplastic forming. After reaching the set air pressure value respectively, keep it warm and pressurized for a period of time;

[0047] X. After the superplastic forming conforms to the die, stop ventilating and heating, cool down with the furnace, and take out the parts after cooling to obtain a multi-channel curved surface structure part.

[0048] Specific Embodiment 2: The difference between this embodiment and Specific Embodiment 1 is that: the material of the sheet in Step 1 is aluminum alloy; the material of the intermediate layer in Step 1 is copper foil; the material of the mask plate in Step 1 is stainless steel; the shape of the opening area of the mask plate in Step 1 is the same as the shape of the groove on the sheet. Other steps are the same as those in Specific Embodiment 1.

[0049] Specific Embodiment 3: The difference between this embodiment and either Specific Embodiment 1 or 2 is that: the grinding in Step 2 is carried out using 180# - 400# SiC sandpaper; the solvent for ultrasonic cleaning in Step 2 is anhydrous ethanol, and the ultrasonic cleaning time is 2 min - 3 min. Other steps are the same as those in Specific Embodiment 1 or 2.

[0050] Specific Embodiment 4: The difference between this embodiment and any one of Specific Embodiments 1 to 3 is that: the material of the air pipe in Step 3 is aluminum alloy; the outer diameter of the air pipe in Step 3 is 2 - 3 mm larger than the runner size, and the wall thickness is 1 mm. Other steps are the same as those in Specific Embodiments 1 to 3.

[0051] Specific Embodiment 5: The difference between this embodiment and any one of Specific Embodiments 1 to 4 is that: the release agent in Step 4 is boron nitride release agent; the temperature of the diffusion bonding process section in Step 5 is 410°C - 540°C. Other steps are the same as those in Specific Embodiments 1 to 4.

[0052] Specific Embodiment 6: The difference between this embodiment and any one of Specific Embodiments 1 to 5 is that: in Step 7, heat up the superplastic forming / diffusion bonding equipment and evacuate the air through the external air pipe of the upper die to a vacuum degree of 0.01 MPa - 0.1 MPa; the temperature of the diffusion bonding process section in Step 7 is 410°C - 540°C. Other steps are the same as those in Specific Embodiments 1 to 5.

[0053] Embodiment 7: The difference between this embodiment and any one of Embodiments 1 to 6 is as follows: in Step 7, the heat preservation time is 5 min to 10 min; in Step 7, the air pressure is gradually increased at a speed of 0.1 MPa / min, and after reaching the set air pressure value of 1 MPa to 3 MPa, heat preservation and pressure holding are carried out for 20 min to 40 min. Other steps are the same as those in Embodiments 1 to 6.

[0054] Embodiment 8: The difference between this embodiment and any one of Embodiments 1 to 7 is as follows: in Step 9, after the temperature of the to-be-formed mold drops to the superplastic forming process section temperature, heat preservation is carried out for 5 min to 10 min; in Step 9, the superplastic forming process section temperature is 370 °C to 460 °C. Other steps are the same as those in Embodiments 1 to 7.

[0055] Embodiment 9: The difference between this embodiment and any one of Embodiments 1 to 8 is as follows: in Step 9, superplastic forming of the sheet is carried out through an external air pipe connected to the upper mold, the air pressure is gradually increased at a speed of 0.1 MPa / min, and after reaching the set value of 2 MPa to 5 MPa, heat preservation and pressure holding are carried out for 20 min to 40 min, and the superplastic forming stage ends; in Step 9, air is passed through the air pipe at the runner opening to maintain the runner shape during the forming process, the air pressure is gradually increased at a speed of 0.1 MPa / min, and after reaching the set value of 1 MPa to 3 MPa, heat preservation and pressure holding are carried out until the superplastic forming stage ends. Other steps are the same as those in Embodiments 1 to 8.

[0056] Embodiment 10: The difference between this embodiment and any one of Embodiments 1 to 9 is as follows: in Step 10, the upper and lower surfaces of the multi-channel curved surface structure part are curved surfaces with the same width, the depth-width ratio is 0.25 to 0.3, the runner runs through the inside of the multi-channel curved surface structure part, the runner width is 3 mm to 5 mm, the runner height is 1 mm to 1.2 mm, and the runner pitch is 4 mm to 8 mm. Other steps are the same as those in Embodiments 1 to 9.

[0057] The following examples are used to verify the beneficial effects of the present invention:

[0058] The experimental methods used in the following examples are all conventional methods unless otherwise specified. The materials and methods used, unless otherwise specified, are all conventional materials and methods in this field, and those skilled in the art can obtain them through commercial channels.

[0059] Example 1: A method for superplastic forming / diffusion bonding of a multi-channel curved surface structure is specifically completed according to the following steps:

[0060] 1. Mill out a plate with multiple grooves (the width of the grooves is 3mm and the depth is 0.5mm), make a mask plate according to the shape of the grooves on the plate, and use the mask plate to cut off the middle layer of the groove area on the plate to obtain the milled grooved plate and the cut middle layer;

[0061] The material of the plate described in step 1 is 5A06 aluminum alloy with a thickness of 2 mm;

[0062] The material of the middle layer described in step 1 is high-purity copper foil with a thickness of 10 μm;

[0063] The mask described in step 1 is made of stainless steel with a thickness of 1 mm;

[0064] The opening area of ​​the mask described in step 1 is the same shape as the groove on the plate;

[0065] 2. Take two milled grooved plates, grind their surfaces to make them smooth, remove surface oil stains, and then use anhydrous ethanol to ultrasonically clean them and the cut middle layer for 3 minutes, and blow dry them with cold air to obtain the grooved plates and the middle layer to be used;

[0066] The grinding described in step 2 is performed using 400# SiC sandpaper;

[0067] 3. Place the middle layer to be used between two grooved plates to be used, align the grooves on the two plates to form a flow channel; take an air pipe (with an outer diameter of 6mm and a wall thickness of 1mm) and connect it to the flow channel opening, then weld the two plates, the middle layer and the air pipe together, and the current during welding is 90A to obtain a welded plate;

[0068] The material of the air pipe described in step 3 is 5A06 aluminum alloy;

[0069] Fourth, spray the outer surface of the welded plate with an isolating agent to obtain a welded plate sprayed with an isolating agent, such as Figure 2 As shown;

[0070] The isolation agent described in step 4 is a boron nitride isolation agent;

[0071] 5. placing the forming die in a superplastic forming / diffusion bonding device, and heating the superplastic forming / diffusion bonding device to a diffusion bonding process section temperature;

[0072] The temperature of the diffusion bonding process section described in step 5 is 520°C;

[0073] 6. Place the welded plate sprayed with the isolation agent in a forming mold in a superplastic forming / diffusion bonding equipment that has reached the temperature of the diffusion bonding process section, such as Figure 1 As shown;

[0074] VII. Since the welded sheets sprayed with the release agent are placed in the superplastic forming / diffusion bonding equipment, the furnace door is opened and the temperature drops. Then, the superplastic forming / diffusion bonding equipment is heated up again and vacuum is pumped through the external air pipe of the upper die. After the forming die reaches the set temperature (520 °C), it is kept warm for 10 min. Then, air is introduced through the exhaust holes of the lower die to pressurize the lower surface of the sheet for diffusion bonding. After reaching the set air pressure value, it is kept warm and under pressure for 30 min;

[0075] In step VII, the superplastic forming / diffusion bonding equipment is heated up and vacuum is pumped through the external air pipe of the upper die until the vacuum degree reaches 0.1 MPa;

[0076] In step VII, the air pressure is gradually increased at a speed of 0.1 MPa / min. After reaching the set air pressure value of 1 MPa, it is kept warm and under pressure for 30 min;

[0077] The temperature of the diffusion bonding process section in step VII is 520 °C;

[0078] VIII. After the diffusion bonding is completed, stop the air supply and heating, and stop pumping vacuum;

[0079] IX. After the temperature of the forming die drops to the temperature of the superplastic forming process section, keep it warm for a period of time, and then superplastic form the sheet by introducing air through the external air pipe of the upper die and the air pipe at the runner outlet. After reaching the set air pressure value respectively, keep it warm and under pressure for a period of time;

[0080] In step IX, after the temperature of the forming die drops to the temperature of the superplastic forming process section, keep it warm for 5 min;

[0081] The temperature of the superplastic forming process section described in step IX is 430 °C;

[0082] In the process of superplastic forming the sheet by introducing air through the external air pipe of the upper die and the air pipe at the runner outlet in step IX, the air pressure is gradually increased at a speed of 0.1 MPa / min. After reaching the set value of 3 MPa, keep it warm and under pressure for 30 min, and the superplastic forming stage ends;

[0083] In step IX, air is introduced through the air pipe at the runner outlet to provide the internal air pressure of the runner and ensure that the runner does not deform and collapse during the superplastic forming process. The internal air pressure of the runner is set to 1 MPa, and the air pressure is gradually increased at a speed of 0.1 MPa / min. After reaching the set value of 1 MPa, keep it warm and under pressure until the superplastic forming stage ends;

[0084] X. After the superplastic forming is in conformity with the die, stop the air supply and heating, cool down with the furnace, and take out the parts after cooling to obtain a multi-channel curved surface structural part.

[0085] The process schematic diagrams of steps VI to X are as Figure 1 shown.

[0086] The effect diagram of the finally formed multi-channel curved surface heat dissipation component in this embodiment is asFigures 3 to 5 As shown, the upper and lower surfaces are curved, and the width a 1 = a 2 = a 3 = a 4 , and the depth-width ratio h / a 1 is 0.25. The flow channel runs through the inside of the curved member, with a width of 3 mm, a height of 1 mm, and a flow channel spacing of 4 mm. The physical object of the multi-channel curved surface structural member including the process section is formed as shown in Figure 6 . The process section is cut off by wire cutting to obtain a multi-channel curved surface heat dissipation structural member as shown in Figure 7 and 8 . In the presence of internal air pressure, the appearance of the curved member and the shape of the flow channel are good.

[0087] The vertical flow channel is cut open, and the thickness of the characteristic points of the member is measured. The cross-sectional thickness change curve of Example 1 is as shown in Figure 6 . The degree of thickness reduction of the member is small, and the member is safe and reliable.

[0088] It can be seen from Figure 10 that compared with the base material, the tensile strength of the formed part in Example 1 increases, and the elongation decreases. The load-bearing capacity of the formed part under tensile load is improved, and the safety of the member is improved.

[0089] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.

Claims

1. A method for superplastic forming / diffusion bonding of a multi-channel curved surface structure, characterized in that The method is specifically completed according to the following steps:

1. Mill out a plate with multiple grooves, make a mask plate according to the shape of the grooves on the plate, and use the mask plate to cut off the middle layer of the groove area on the plate to obtain the milled grooved plate and the cut middle layer; 2. Take two milled grooved plates, grind their surfaces to make them smooth, remove surface oil stains, and then ultrasonically clean them and the cut middle layer, and dry them with cold air to obtain the grooved plates and the middle layer to be used; 3. Place the middle layer to be used between two grooved plates to be used, align the grooves on the two plates to form a flow channel; connect an air pipe to the flow channel opening, and then weld the two plates, the middle layer and the air pipe to obtain a welded plate; Fourth, spraying an isolation agent on the outer surface of the welded plate to obtain an isolation agent-sprayed welded plate; 5. placing the forming die in a superplastic forming / diffusion bonding device, and heating the superplastic forming / diffusion bonding device to a diffusion bonding process section temperature; 6. Placing the welded plate sprayed with the isolation agent in a forming mold in a superplastic forming / diffusion bonding equipment that has reached the temperature of the diffusion bonding process section; 7. Heat up the superplastic forming / diffusion bonding equipment again and evacuate through the upper die external air pipe. After the forming die reaches the temperature of the diffusion bonding process section, keep it warm for a period of time, then ventilate through the exhaust hole of the lower die to pressurize the lower surface of the sheet for diffusion bonding. After reaching the set air pressure value, keep it warm and pressurized for a period of time.

8. After the diffusion connection is completed, stop ventilation, heating, and vacuuming; 9. After the temperature of the forming mold drops to the temperature of the superplastic forming process section, it is kept warm for a period of time, and then the plate is superplasticly formed through the air pipe connected to the upper mold and the air pipe at the runner port. After reaching the set air pressure value, the temperature and pressure are kept for a period of time; 10. After superplastic forming and die pasting, ventilation and heating are stopped, and the parts are cooled with the furnace, and the parts are taken out after cooling to obtain multi-channel curved surface structural parts.

2. The method for superplastic forming / diffusion bonding of a multi-channel curved surface structure according to claim 1, characterized in that The material of the plate described in step one is aluminum alloy; the material of the intermediate layer described in step one is copper foil; the material of the mask described in step one is stainless steel; the opening area of ​​the mask described in step one has the same shape as the groove on the plate.

3. The method for superplastic forming / diffusion bonding of a multi-channel curved surface structure according to claim 1, characterized in that The polishing described in step 2 is performed using 180#~400# SiC sandpaper; the solvent for ultrasonic cleaning described in step 2 is anhydrous ethanol, and the time for ultrasonic cleaning is 2min~3min.

4. The method for superplastic forming / diffusion bonding of a multi-channel curved surface structure according to claim 1, characterized in that The material of the air pipe described in step 3 is aluminum alloy; the outer diameter of the air pipe described in step 3 is 2 to 3 mm larger than the flow channel size, and the wall thickness is 1 mm.

5. The method for superplastic forming / diffusion bonding of a multi-channel curved surface structure according to claim 1, characterized in that The isolating agent described in step 4 is a boron nitride isolating agent; the temperature of the diffusion bonding process section described in step 5 is 410°C to 540°C.

6. The method for superplastic forming / diffusion bonding of a multi-channel curved surface structure according to claim 1, characterized in that In step seven, the superplastic forming / diffusion bonding equipment is heated and evacuated to a vacuum degree of 0.01 MPa to 0.1 MPa through an external air pipe connected to the upper mold; the temperature of the diffusion bonding process section in step seven is 410° C. to 540° C.

7. The method for superplastic forming / diffusion bonding of a multi-channel curved surface structure according to claim 1, characterized in that The heat preservation time described in step seven is 5min to 10min; in step seven, the air pressure is gradually increased at a speed of 0.1MPa / min, and after reaching the air pressure setting value of 1MPa to 3MPa, the heat preservation and pressure maintenance are carried out for 20min to 40min.

8. The method for superplastic forming / diffusion bonding of a multi-channel curved surface structure according to claim 1, characterized in that After the temperature of the mold to be formed in step nine drops to the temperature of the superplastic forming process section, it is kept warm for 5 minutes to 10 minutes; the temperature of the superplastic forming process section in step nine is 370°C to 460°C.

9. The method for superplastic forming / diffusion bonding of a multi-channel curved surface structure according to claim 1, characterized in that In step nine, the sheet is superplastically formed through an external air pipe connected to the upper die, and the air pressure is gradually increased at a speed of 0.1 MPa / min. After reaching the set value of 2MPa~5MPa, the heat and pressure are maintained for 20min~40min, and the superplastic forming stage is ended; in step nine, ventilation is performed through the air pipe at the flow channel outlet to maintain the flow channel shape during the forming process, and the air pressure is gradually increased at a speed of 0.1 MPa / min. After reaching the set value of 1MPa~3MPa, the heat and pressure are maintained until the superplastic forming stage is ended.

10. The method for superplastic forming / diffusion bonding of a multi-channel curved surface structure according to claim 1, characterized in that The upper and lower surfaces of the multi-channel curved surface structure described in step ten are curved, with the same width and a depth-to-width ratio of 0.25 to 0.

3. The channels run across the interior of the multi-channel curved surface structure, with a channel width of 3 mm to 5 mm, a channel height of 1 mm to 1.2 mm, and a channel spacing of 4 mm to 8 mm.

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