Method and device for forming ultra-deep aluminum-lithium alloy complex thin-wall curved surface part

Abstract

The invention belongs to the technical field of plate forming, and particularly relates to a forming method and device for an ultra-deep aluminum-lithium alloy complex thin-wall bent part. Comprising the following steps: determining the position of an easy-to-crack part of the ultra-deep aluminum-lithium alloy complex thin-wall curved part through analogue simulation in a forming process; the method comprises the following steps: pretreating an aluminum-lithium alloy plate, and then carrying out solid solution quenching treatment on the plate; arranging a liquid nitrogen cooling pipeline in the forming device according to the position of an easy-to-crack part of the ultra-deep aluminum-lithium alloy complex thin-wall curved part; the aluminum-lithium alloy plate subjected to solid solution quenching treatment is placed in a forming device, liquid nitrogen is sprayed to the easy-to-crack portion of the aluminum-lithium alloy plate through a liquid nitrogen cooling pipeline for liquid nitrogen cooling, blank holder force is kept to be applied to the aluminum-lithium alloy plate in the liquid nitrogen cooling process, and a thin-wall bent part preformed blank is obtained after forming; and aging heat treatment is conducted on the thin-wall curved part preformed blank, and the ultra-deep aluminum-lithium alloy complex thin-wall curved part is obtained. By means of the method and device, high-efficiency, low-cost and high-precision forming can be achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of sheet metal forming, and specifically relates to a method and device for forming a complex thin-walled curved surface part of an ultra-deep aluminum-lithium alloy. Background Art

[0002] Thin-walled components account for more than 50% of the weight of aircraft structures, and new forming and manufacturing technologies have always been the focus of research on aircraft structural parts. Lightweight and high-precision manufacturing of thin-walled components is the key to reducing the weight and improving the efficiency of aircraft structures, which can achieve lower fuel consumption and longer range, bringing significant economic benefits. Aircraft thin-walled components are subject to complex aerodynamic loads during flight, and their shapes tend to be integrated, complex, and large-scale. Characteristics such as non-uniform wall thickness and variable curvature are more prominent, which puts forward high requirements on forming accuracy, reliability, and service life, and poses severe challenges to forming and manufacturing.

[0003] The use of lightweight, high-strength, high-toughness aluminum-lithium alloys to manufacture aircraft thin-walled curved surface components is an important development direction for aircraft structural weight reduction. According to literature reports, the use of aluminum-lithium alloys to replace traditional aluminum alloys can achieve a 10-15% structural weight reduction benefit and reduce aircraft operating costs. However, the room temperature formability of aluminum-lithium alloys is worse than that of traditional aluminum alloys, and the anisotropy is more significant. At present, it is only used in simple structures such as aircraft fuselage barrel sections. The forming and manufacturing of ultra-deep aluminum-lithium alloy complex thin-walled curved surface components and their application are still blank.

[0004] In the previous research and development process, the applicant invented a low-temperature forming device and method for complex curved thin-walled components of aluminum-lithium alloy (CN110722043A), in which the forming device includes a cryogenic box, a control cabinet, a liquid nitrogen tank, a solenoid valve group, a punch, a die, a temperature detector and a pressure device. The punch, die, temperature detector and pressure device are arranged in the cryogenic box, and the pipeline connecting the liquid nitrogen tank and the cryogenic box is provided with a solenoid valve group. The solenoid valve group and the temperature detector are electrically connected to the control cabinet. The pressure device is set to press the plate between the punch and the die, and the cryogenic box is provided with a box door. However, during the heat treatment process, due to the low stiffness of thin-walled parts, large warping deformation is easily generated, which has become a problem that needs to be solved urgently to restrict the high-precision forming and manufacturing of aluminum-lithium alloy thin-walled parts. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a method and device for forming complex thin-walled curved parts of ultra-deep aluminum-lithium alloys that can achieve high efficiency, low cost and high precision forming.

[0006] In order to solve the above technical problems, the technical solution proposed by the present invention is: a method for forming a complex thin-walled curved part of an ultra-deep aluminum-lithium alloy, comprising the steps of: Through forming process simulation, the locations of crack-prone parts of ultra-deep aluminum-lithium alloy complex thin-walled curved parts are determined; After pre-treating the aluminum-lithium alloy plate, the plate is subjected to solid solution quenching treatment; Arrange liquid nitrogen cooling pipelines in the forming device according to the location of the crack-prone parts of ultra-deep aluminum-lithium alloy complex thin-walled curved parts; The aluminum-lithium alloy plate after the solution quenching treatment is placed in a forming device, and liquid nitrogen is sprayed on the crack-prone parts of the aluminum-lithium alloy plate through a liquid nitrogen cooling pipeline for liquid nitrogen cooling. The cooling temperature is lower than -180°C. During the liquid nitrogen cooling process, the aluminum-lithium alloy plate is kept subjected to a blank holding force, and a thin-walled curved part preform is obtained after forming; The thin-walled curved part preform is subjected to aging heat treatment to obtain ultra-deep aluminum-lithium alloy complex thin-walled curved parts.

[0007] In one embodiment, the aluminum-lithium alloy plate material is 2060 aluminum-lithium alloy with a thickness of 1-2 mm.

[0008] In one embodiment, during the solution quenching treatment, the solution temperature of the aluminum-lithium alloy plate is 515±2° C., and water quenching is performed after being kept at the solution temperature for more than 1 hour.

[0009] In one embodiment, a nozzle is installed at the front end of the liquid nitrogen cooling pipeline of the forming device. The installation position, quantity and size of the nozzle are determined according to the motion trajectory of the position of the crack-prone part simulated by the forming process. The liquid nitrogen spray cooling range covers the crack-prone parts of the complex thin-walled curved parts of ultra-deep aluminum-lithium alloy.

[0010] In one embodiment, during liquid nitrogen cooling, the liquid nitrogen cooling temperature is preset through the deep cold control system of the forming device, and a temperature measuring thermocouple is connected to the position above the location where the ultra-deep aluminum-lithium alloy complex thin-walled curved parts are prone to cracking for temperature measurement, and the liquid nitrogen tank valve and the deep cold control system are opened to perform liquid nitrogen cooling; when the temperature of the aluminum-lithium alloy plate reaches the preset liquid nitrogen cooling temperature, the temperature measuring thermocouple is removed.

[0011] In one embodiment, the aging heat treatment temperature is 165°C±2°C, and the aging heat treatment time is not less than 25h.

[0012] In one embodiment, during the process of applying the blank holding force, the pressure is 0.5-2.0 MPa.

[0013] In one embodiment, the liquid nitrogen cooling time is 5 to 8 seconds.

[0014] In one embodiment, the aging heat treatment is an under-aging heat treatment.

[0015] Based on the same inventive concept, a forming device for the method for forming a complex thin-walled curved part of an ultra-deep aluminum-lithium alloy as described above is also provided, the forming device comprising: An upper die base, a punch, a blank holder, a die and a lower die base are arranged in sequence from top to bottom; the punch and the die cooperate with each other through a guide column, and liquid nitrogen cooling pipelines are arranged inside the die and the lower die base, and the liquid nitrogen cooling pipelines are connected to a deep-cold control system for spraying liquid nitrogen, and a nozzle with an adjustable spray range is arranged on the liquid nitrogen cooling pipeline.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: in the ultra-deep aluminum-lithium alloy complex thin-wall curved component forming method and forming device of the present application, before the product is processed and formed, the location of the ultra-deep aluminum-lithium alloy complex thin-wall curved surface component is determined by forming process simulation, and in the edge forming process, liquid nitrogen is used to spray and cool the location of the easy-to-crack part, forming an ultra-low temperature environment in the easy-to-crack part so that the local plasticity is improved, and the remaining parts are still kept as difficult deformation areas, forming a plastic gradient, greatly improving the plastic deformation ability of the local material, suppressing the risk of microcracks formed by internal damage, achieving one-time deep drawing and improving the forming accuracy; using this method and device, there is no need to place the mold or even the equipment in a cooling box for cooling, the cooling efficiency is high, the cooling time is short, the forming efficiency is high, and it is easy to realize the technology under industrial production conditions, and reduce the manufacturing cost. The present invention adopts liquid nitrogen cooling, which is green and environmentally friendly, easy to obtain, and easy to use. At the same time, liquid nitrogen plays a role in cooling during the forming process, and can also form a smooth white frost on the mold surface, lubricate the component forming process, reduce the strain during the component forming process, and improve the forming quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 It is a schematic structural diagram of a forming device according to one embodiment; Figure 2 It is a schematic structural diagram of a forming device according to one embodiment; Figure 3a It is a schematic diagram of simulation results of crack-prone parts of an aircraft basin-shaped component according to one embodiment; Figure 3b for Figure 3a Schematic diagram of the nozzle installation position structure during the aircraft basin-shaped part forming process. DETAILED DESCRIPTION

[0019] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0020] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0021] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0022] See also Figure 1-3b , a forming device for forming a complex thin-walled curved part of an ultra-deep aluminum-lithium alloy, mainly comprising a liquid nitrogen tank, a cryogenic control system, a double-acting press and a forming mold. The forming mold includes an upper die base 11, a punch 12, a blank holder 13, a die 16, and a lower die base 17. The double-acting press and the forming mold are connected by screws 17. The punch 12 and the die 16 cooperate with each other through guide pillars 18. A plurality of process bosses 15 are arranged on the die 16 to adjust the gap between the die 16 and the aluminum-lithium alloy sheet 14 to be formed; a liquid nitrogen cooling pipeline 20 is arranged inside the die 16 and the lower die base 17, and the liquid nitrogen cooling pipeline 20 is connected to the cryogenic control system, and the spraying of liquid nitrogen is controlled by the cryogenic control system. The forming mold can change the geometric shapes of the punch 12 and the die 16 according to the shape of the target component.

[0023] A method for forming a complex thin-walled curved part of an ultra-deep aluminum-lithium alloy comprises the following steps: S10. Determine the location of the crack-prone parts of ultra-deep aluminum-lithium alloy complex thin-walled curved parts through forming process simulation.

[0024] Specifically, ABAQUS simulation software is used to carry out simulation.

[0025] S20, after pre-treating the aluminum-lithium alloy plate, perform solid solution quenching treatment on the plate.

[0026] Specifically, step S20 includes the steps of: Provide aluminum-lithium alloy plates, and process them according to size requirements. The aluminum-lithium alloy plates are preferably 2060 aluminum-lithium alloy with a thickness of 1~2mm. According to the simulation optimization results, cut the materials by laser cutting, heat them in a heating furnace to a solid solution temperature of 515±2℃, keep them warm for 1h, and then immediately quench them with water. The quenching medium is room temperature water.

[0027] S30. Arrange liquid nitrogen cooling pipelines in the forming device according to the locations of the crack-prone parts of the ultra-deep aluminum-lithium alloy complex thin-walled curved parts.

[0028] Different formed parts have different cracking locations. Therefore, it is necessary to determine the cracking-prone locations based on the forming process simulation, and then lay out the liquid nitrogen pipeline. Specifically, a nozzle 21 is installed at the front end of the liquid nitrogen pipeline. The installation position, quantity and size of the nozzle 21 are selected based on the movement trajectory of the cracking-prone locations during the forming simulation process to ensure that the liquid nitrogen spray cooling range during the forming process covers the cracking-prone locations.

[0029] The order of S20 and S30 is in no particular order.

[0030] S40, placing the aluminum-lithium alloy plate after solution quenching treatment in a forming device, spraying liquid nitrogen on the crack-prone parts of the aluminum-lithium alloy plate through a liquid nitrogen cooling pipeline for liquid nitrogen cooling, the cooling temperature is lower than -180°C, and the aluminum-lithium alloy plate is kept subjected to a blanking force during the liquid nitrogen cooling process, and a thin-walled curved part preform is obtained after forming. Preferably, the liquid nitrogen cooling time is 5 to 8 seconds. By adopting the method of the present application, only the crack-prone parts of the ultra-deep aluminum-lithium alloy complex thin-walled curved parts need to be liquid nitrogen cooled, and the cooling time is greatly reduced. More importantly, an ultra-low temperature environment is formed in the crack-prone parts to improve the local plasticity, and the remaining parts are still kept as difficult-to-deform areas, forming a plastic gradient, greatly improving the local material plastic deformation ability, suppressing the risk of internal damage to form microcracks, achieving one-time deep drawing and improving the forming accuracy.

[0031] Specifically, the cryogenic control system of the forming device presets the liquid nitrogen cooling temperature (below -180°C) and connects the temperature measuring thermocouple to the crack-prone part of the aluminum-lithium alloy plate for temperature measurement. The liquid nitrogen tank valve and the cryogenic control system are opened to control the liquid nitrogen pressure and flow rate, and spray cooling is performed through the nozzle connected to the liquid nitrogen cooling pipeline. When the temperature of the crack-prone part of the aluminum-lithium alloy plate reaches the preset liquid nitrogen cooling temperature, the temperature measuring thermocouple is removed to avoid interference. At the same time, a suitable blank holding force is provided, with a pressure of 0.5~2.0MPa. Finely adjust the height of the process boss 15 on the working plane of the die to control the blank holding gap during the blank holding process, control the blank holding slider to descend, and lower the blank holding ring 14 to the working position and apply the preset blank holding force, and keep the pressure unchanged.

[0032] During the pressing process, the punch 12 is pressed down to perform ultra-low temperature deep drawing. The preferred pressing speed is 5-10 mm / s. After the forming is completed, the liquid nitrogen is turned off, the blank holder 14 and the drawing slide are lifted, and the formed thin-walled curved preform is taken out.

[0033] S50: Perform aging heat treatment on the thin-walled curved part preform to obtain a complex thin-walled curved part of ultra-deep aluminum-lithium alloy.

[0034] Specifically, the aging temperature is 165±2°C and the aging time is 25h. In a preferred embodiment, considering the high dislocation density of ultra-low temperature forming, the easy formation of precipitation phases, and the high fatigue performance requirements of aircraft thin-walled parts, the preferred aging heat treatment system is aging heat treatment.

[0035] Example 1 The aircraft tip skin is used as the implementation object. It is 75mm wide, about 320mm long, 2mm thick, and 100mm deep. It is formed by "one mold, two pieces". Through the simulation using ABAQUS simulation software, the hyperboloid at the bottom of the tip skin is very likely to deform, thin, or even crack at two symmetrical locations on the top. According to the local cooling requirements of the two symmetrical locations, a 1-to-2 liquid nitrogen pipeline is set up, and a fan-shaped nozzle is used at the terminal of the pipeline. Its cooling range is an area with a diameter of 120mm. Liquid nitrogen spray cooling is performed locally on the parts of the plate that are prone to cracking, which can achieve local plasticity improvement of the parts that are prone to cracking.

[0036] Specifically, according to the requirements of the parts, annealed 2060 aluminum-lithium alloy plates with a thickness of 1 mm are selected for tip skin forming, and the shape and size of the plates are elliptical billets with a long axis of 520 mm and a short axis of 250 mm; laser cutting is used to prepare the elliptical aluminum-lithium alloy plates; solution heat treatment is carried out in a resistance furnace at a solution temperature of 515±2°C. After keeping warm for 1 hour, water quenching is immediately carried out, and the transfer time is less than 10 seconds; after solution quenching, the plates are placed at the marked position specified by the die to ensure that the plates are placed in the center and symmetrically, and a double-acting press is used to apply a blanking force, and the height of the small boss on the working plane of the die is slightly adjusted to control the blanking gap during the blanking process, and the blanking slider is controlled to descend so that the blanking ring is lowered to the working position and a preset blanking force of 1.2 MPa is applied; the target forming temperature of -180°C is preset in the deep cold control system, and Select two points on the crack-prone position on the upper surface of the plate and the center of the plate to attach temperature measuring thermocouples, open the valve of the liquid nitrogen tank and the cryogenic control system, control the liquid nitrogen pressure and flow, inject liquid nitrogen into the cooling passage and start spraying cooling. When the plate temperature reaches the target forming temperature below -180℃, remove the temperature measuring thermocouple to avoid interference; continue cooling until the blank holder force is 1.2MPa, the cooling time is 5s, carry out tip skin forming, control the drawing slide to drive the punch to press down, and carry out ultra-low temperature drawing forming. The die closing depth is 100mm. After the forming is completed, hold the pressure for 10s and then unload, turn off the liquid nitrogen, lift the blank holder and drawing slide, and take out the formed component; carry out under-aging heat treatment in the aging heat treatment furnace: the aging temperature is 165±2℃, the aging time is 25h, and then the forming accuracy and mechanical properties are tested. The results are shown in Table 1.

[0037] Example 2 The aircraft basin-shaped parts are used as the implementation object. They are 410mm wide, about 600mm long, 2mm thick, and 96mm deep. Through simulation analysis, the basin-shaped parts are prone to cracking at the bottom fillet, and the liquid nitrogen pipeline is distributed along the bottom of the basin-shaped parts. According to the local cooling requirements of the entire circle of the bottom fillet, a 1-to-7 liquid nitrogen pipeline is set, and an umbrella-shaped nozzle is used at the end of the pipeline. Its cooling range is an area of ​​90mm in diameter. The local cooling of the prone-to-crack parts of the plate is directly reduced to achieve local plasticity improvement of the prone-to-crack parts.

[0038] Specifically, according to the requirements of the parts, 2mm thick annealed 2060 aluminum-lithium alloy sheet is selected for basin-shaped part forming, which has a hollow structure with an external length of 750mm and a width of 570mm, and an internal length of 350mm and a width of 220mm; the mold is composed of an upper die seat, a punch, a blank holder, a die, and a lower die seat, and the sheet is positioned at the marked position set by the die; the aluminum-lithium alloy sheet is prepared by laser cutting; the solid solution heat treatment is carried out in a resistance furnace at a solid solution temperature of 515±2℃. After keeping warm for 1h, it is immediately water quenched, and the transfer time is less than 10s; after solution quenching, the sheet is placed at the marked position set by the die to ensure that the sheet is placed in the center and symmetrically, and the blank holder force is applied with a double-acting press, and the height of the small boss on the working plane of the die is slightly adjusted to control the blank holder gap during the blank holder process, and the blank holder slider is controlled to descend so that the blank holder ring is lowered to the working position and a preset blank holder force of 1.5 is applied. MPa; preset the target forming temperature of -180℃ in the cryogenic control system, and select 3 points around the cracking position on the upper surface of the plate to paste the temperature measuring thermocouples, open the liquid nitrogen tank valve and the cryogenic control system, control the liquid nitrogen pressure and flow, inject liquid nitrogen into the cooling passage and start spraying cooling. When the plate temperature reaches below the target forming temperature of -180℃, remove the temperature measuring thermocouple to avoid interference; continue cooling until the blank holder force is 1.5MPa, the cooling time is 8s, and the basin-shaped part is formed. The drawing slide is controlled to drive the punch to press down, and ultra-low temperature drawing is carried out. The die closing depth is 96mm. After the forming is completed, the pressure is maintained for 10s and then unloaded. The liquid nitrogen is turned off, the blank holder and the drawing slide are lifted, and the formed component is taken out; under-aging heat treatment is carried out in the aging heat treatment furnace: the aging temperature is 165±2℃, the aging time is 25h, and then the forming accuracy and mechanical properties are tested. The results are shown in Table 1.

[0039] Comparative Example 1 The aircraft tip skin is used as the implementation object, which is 75mm wide, about 320mm long, 2mm thick, and 100mm deep. It is formed by the "one mold two pieces" method. According to the requirements of the parts, annealed 2060 aluminum-lithium alloy plates with a thickness of 1mm are selected for tip skin forming. The shape and size of the plate are elliptical blanks with a long axis of 520mm and a short axis of 250mm; the forming mold consists of an upper die seat, a punch, a blank holder, a die, and a lower die seat. The die is positioned at the marked position specified by the die to position the plate; the aluminum-lithium alloy plate is prepared by laser cutting; the plate is placed at the marked position specified by the die to ensure that the plate is placed in the center and symmetrically, and a double-acting press is used to apply the blank holder force and finely adjust the die. The height of the small boss on the working plane is adjusted to control the blanking gap during the blanking process, and the blanking slider is controlled to descend so that the blanking ring is lowered to the working position and a preset blanking force of 1.2 MPa is applied; the tip skin forming is carried out, the drawing slider is controlled to drive the punch to press down, and ultra-low temperature drawing is carried out. The blanking and drawing slider are lifted to take out the formed component; under-aging heat treatment is carried out in an aging heat treatment furnace: the aging temperature is 165±2℃, and the aging time is 25h. Then the forming accuracy and mechanical properties are tested. The results are shown in Table 1.

[0040] From the results in Table 1, the top of the tip skin of Comparative Example 1 has cracks on both sides when the drawing depth is 32mm, which cannot meet the precise forming and manufacturing requirements of ultra-deep aluminum-lithium alloy complex thin-walled parts. However, the product obtained by the method and device of the present application can be formed in one step, with a thinning rate of 11.7% and a drawing depth of 100mm.

[0041] Table 1 Comparison of forming quality between the embodiment and the comparative example

Claims

1. A method for forming complex thin-walled curved parts of ultra-deep aluminum-lithium alloy, characterized in that: Includes steps: Through forming process simulation, the locations of crack-prone parts of ultra-deep aluminum-lithium alloy complex thin-walled curved parts are determined; After pre-treating the aluminum-lithium alloy plate, the plate is subjected to solid solution quenching treatment; Arrange liquid nitrogen cooling pipelines in the forming device according to the location of the crack-prone parts of ultra-deep aluminum-lithium alloy complex thin-walled curved parts; The aluminum-lithium alloy plate after the solution quenching treatment is placed in a forming device, and liquid nitrogen is sprayed on the crack-prone parts of the aluminum-lithium alloy plate through a liquid nitrogen cooling pipeline for liquid nitrogen cooling. The cooling temperature is lower than -180°C. During the liquid nitrogen cooling process, the aluminum-lithium alloy plate is kept subjected to a blank holding force, and a thin-walled curved part preform is obtained after forming; The thin-walled curved part preform is subjected to aging heat treatment to obtain ultra-deep aluminum-lithium alloy complex thin-walled curved parts.

2. The method for forming ultra-deep aluminum-lithium alloy complex thin-walled curved parts according to claim 1, characterized in that: The aluminum-lithium alloy plate is made of 2060 aluminum-lithium alloy and has a thickness of 1-2 mm.

3. The method for forming complex thin-walled curved parts of ultra-deep aluminum-lithium alloy according to claim 1, characterized in that: During the solution quenching treatment, the solution temperature of the aluminum-lithium alloy plate is 515±2°C, and water quenching is performed after being kept at the solution temperature for more than 1 hour.

4. The method for forming ultra-deep aluminum-lithium alloy complex thin-walled curved parts according to claim 1, characterized in that: A nozzle is installed at the front end of the liquid nitrogen cooling pipeline of the forming device. The movement trajectory of the location of the prone to cracking parts is simulated according to the forming process to determine the installation position, quantity and size of the nozzle. The liquid nitrogen spray cooling range covers the prone to cracking parts of complex thin-walled curved parts of ultra-deep aluminum-lithium alloy.

5. The method for forming ultra-deep aluminum-lithium alloy complex thin-walled curved parts according to claim 4, characterized in that: During liquid nitrogen cooling, the liquid nitrogen cooling temperature is preset through the deep freezing control system of the forming device, and the temperature measuring thermocouple is connected to the position above the prone to cracking part of the ultra-deep aluminum-lithium alloy complex thin-walled curved parts for temperature measurement. The liquid nitrogen tank valve and the deep freezing control system are opened to carry out liquid nitrogen cooling; when the temperature of the aluminum-lithium alloy plate reaches the preset liquid nitrogen cooling temperature, the temperature measuring thermocouple is removed.

6. The method for forming ultra-deep aluminum-lithium alloy complex thin-walled curved parts according to claim 1, characterized in that: The aging heat treatment temperature is 165°C±2°C, and the aging heat treatment time is not less than 25h.

7. The method for forming ultra-deep aluminum-lithium alloy complex thin-walled curved parts according to claim 1, characterized in that: During the process of applying the blank holding force, the pressure is 0.5~2.0MPa.

8. The method for forming complex thin-walled curved parts of ultra-deep aluminum-lithium alloy according to claim 1, characterized in that: Liquid nitrogen cooling time is 5~8s.

9. The method for forming ultra-deep aluminum-lithium alloy complex thin-walled curved parts according to claim 1, characterized in that: The aging heat treatment is an under-aging heat treatment.

10. A forming device for the method for forming ultra-deep aluminum-lithium alloy complex thin-walled curved parts according to any one of claims 1 to 9, characterized in that: The forming device comprises: An upper die base, a punch, a blank holder, a die and a lower die base are arranged in sequence from top to bottom; the punch and the die cooperate with each other through a guide column, and liquid nitrogen cooling pipelines are arranged inside the die and the lower die base, and the liquid nitrogen cooling pipelines are connected to a deep-cold control system for spraying liquid nitrogen, and a nozzle with an adjustable spray range is arranged on the liquid nitrogen cooling pipeline.

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