A process for forming a cone section of a tail skirt honeycomb sandwich structure

Abstract

A tail skirt honeycomb sandwich structure cone section forming process method includes the following steps: 1. Designing an inner skin forming tool as a positive mold tool, an outer skin forming tool as a negative mold tool, and a tail skirt honeycomb sandwich structure forming tool as a "zero expansion" mold; 2. Preparing an inner skin and an outer skin, and cutting a honeycomb core to a splicing size; 3. Fitting the inner surface of the inner skin to the tail skirt honeycomb sandwich structure forming tool, and fitting the outer surface to the honeycomb core; 4. Fitting the inner surface of the outer skin to the honeycomb core for trial assembly, and determining the position of the outer skin positioning embedded parts; Positioning The embedded parts are bonded and cured to the inner skin; retaining bars are installed on the upper and lower sides of the inner skin; 5. The outer skin is used to position the embedded parts to achieve bonding between the outer skin and the honeycomb; 6. The product is packaged and transferred to the autoclave; 7. The product is cured, unloaded and demoulded; The cone section radius of the honeycomb sandwich structure of the tail skirt formed by this method is in the range of 1000mm to 5000mm, the total height is not more than 2000mm, and the wall thickness is in the range of 10 to 100mm, which solves the problem of overall forming of the composite material structure of the optical cabin docking section.

Description

Technical Field

[0001] The invention relates to a process for forming an ultra-large-size, high-precision, and high-stability honeycomb sandwich cone segment, and belongs to the field of structural systems for manned spaceflight. Background Art

[0002] The "Optical Cabin," or "Surveyor Space Telescope," is China's largest space astronomical infrastructure to date. Co-orbiting with the space station, it will provide Chinese scientists with a powerful tool for observing the heavens. The honeycomb sandwich structure of the Optical Cabin's tail skirt is the largest composite cabin currently under development at the Fifth Academy. This cabin provides the interface for rocket docking and requires static testing to withstand a maximum payload of 160 tons.

[0003] At present, the diameter of the commonly used rocket docking compartment in China is 1215mm, and the diameter of the docking section required by the honeycomb sandwich structure of the tail skirt is 4126mm, which is 3.4 times the diameter of the conventional interface and has a load-bearing capacity 4 times that of the conventional interface. The product and the docking frame still adopt the docking form, and the taper (roundness) requirements of the product are consistent with those of conventional products, both of which are not greater than 3mm. Large-size molding adopts the conventional female mold molding method, and the tooling size is huge. There is no hot press equipment that meets the requirements for curing in the Beijing area. The conventional molding method currently divides the inner and outer skins into petals, and the load-bearing capacity cannot meet the design index requirements. The load-bearing capacity is large and the precision requirements are high. Due to the size limitations of the equipment, it is impossible to form using traditional methods. It is urgent to develop a new method with small tooling size, high product mechanical strength and high surface accuracy. Summary of the Invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the existing technology, and to provide a tail skirt honeycomb sandwich structure cone section forming process method with inner skin positive mold forming and "zero expansion" forming tooling, which meets the forming requirements of the tail skirt honeycomb sandwich structure product with a cone section radius in the range of 1000mm to 5000mm, a total height not exceeding 2000mm, and a wall thickness in the range of 10 to 100mm.

[0005] The technical solution of the present invention is:

[0006] A tail skirt honeycomb sandwich structure cone section forming process method, the steps are as follows:

[0007] 1. According to the product profile of the tail skirt honeycomb sandwich structure, the inner skin forming tooling is prepared as a positive mold tooling, the outer skin forming tooling is prepared as a negative mold tooling, and the tail skirt honeycomb sandwich structure forming tooling is prepared as a "zero expansion" mold;

[0008] 2. Use the inner skin forming tool to prepare the inner skin, use the outer skin forming tool to prepare the outer skin and paste the release paper, place the positioning embedded parts in the preset processing areas on the upper and lower sides of the center of the outer skin, and determine the splicing size of the honeycomb core and cut it according to the profile and curvature of the honeycomb sandwich structure of the tail skirt;

[0009] 3. The inner surface of the inner skin is attached to the outer side of the tail skirt honeycomb sandwich structure forming tooling, and the inner skin is polished, cleaned and dried; the outer surface of the inner skin is brushed with primer, and the adhesive film is applied to fit the cut honeycomb core;

[0010] Fourth, apply primer to the inner surface of the outer skin, apply adhesive film, and do not remove the release paper. Perform a trial assembly with the honeycomb core in step 3 to ensure that the outer skin is evenly distributed and determine the position of the outer skin positioning embedded parts. The outer skin positioning embedded parts are bonded to the inner skin and cured. Install the blocking strips on the upper and lower sides of the inner skin.

[0011] 5. Remove the outer skin release paper and use the outer skin positioning embedded parts to achieve the outer skin and honeycomb bonding;

[0012] 6. Lay the insulation material, air guide material and vacuum bag film on the outer surface of the outer skin from the inside to the outside, arrange the vacuum nozzle and thermocouple, and package the product; then transfer it to the autoclave and place the product in the designated position;

[0013] 7. The product is cured, unpacked, demoulded, and product indicators are tested.

[0014] Furthermore, the inner skin forming tooling is designed and prepared by the following method:

[0015] S1. Use Python thermodynamic dynamic simulation to simulate the actual position of the inner skin male mold tooling in the autoclave. According to the distribution of the temperature field in the autoclave, set the theoretical required surface of the inner skin male mold tooling during the preset high-temperature molding;

[0016] S2. The theoretical required surface achieved during high-temperature forming is cooled to room temperature using Python thermodynamic dynamic simulation to obtain the final required theoretical surface, which is then used to process and form the inner skin.

[0017] Furthermore, 4 to 8 air guide channels are evenly and staggeredly reserved on the upper and lower sides of the inner skin forming tooling in step one.

[0018] Furthermore, the tail skirt honeycomb sandwich structure forming tooling of step 1 adopts a conical segment split dimensional profile in combination with a carbon fiber honeycomb sandwich structure bottom plate to achieve "zero expansion"; it includes a connecting ring, M upper baffles, N tail skirt assembly forming dies, M lower baffles, 2P bottom plate connecting plates, P bottom plates, and 2P bottom plate connecting strips; M>1, N>1, P>1; the assembly method of the tail skirt honeycomb sandwich structure forming tooling is:

[0019] The upper sides of the S1 and N tail skirt assembly forming dies are connected by a connecting ring, and the lower sides are connected by a bottom plate, providing a dimensional surface for forming the honeycomb sandwich structure of the tail skirt;

[0020] The S2 and P bottom plates are connected by 2P bottom plate connecting plates and 2P bottom plate connecting strips, wherein: 2 bottom plate connecting plates are used to connect the upper sides of the joints of every two bottom plates. Each bottom plate connecting plate is connected to the bottom plate by screw fastening and at least 4 pins for positioning. Each bottom plate connecting strip is connected to the bottom plate by screw fastening to prevent the bottom plate from being stretched in an "eight" shape under force.

[0021] S3. The upper and lower baffles use conical baffles to fix the upper and lower sides of the honeycomb sandwich structure of the tail skirt; the upper baffle is installed on the upper edge of the inner skin, corresponding to the top of the outer skin, and the lower baffle is installed on the lower edge of the inner skin, corresponding to the bottom of the outer skin. The baffles are fixed by physical adhesive materials.

[0022] Furthermore, the connecting ring is made of steel, the tail skirt assembly forming mold is made of cast steel, the bottom plate connecting plate, bottom plate, and bottom plate connecting strip are made of carbon skin honeycomb sandwich structure plates, and the upper and lower baffles are both made of aluminum.

[0023] Furthermore, in step 2, the inner skin is prepared by integral molding, and the outer skin is prepared by flap molding.

[0024] Furthermore, the 0° ply orientation is defined as the busbar direction of the cone section of the tail skirt honeycomb sandwich structure. The ply order in the step 2 for preparing the inner skin is: 0°, 45°, -45°, 90°; the 0°, 45°, and -45° plies are performed using prepregs with a width of 40mm to 60mm, with gaps filled with material, and the 90° plies are performed using narrow strips with a width of 10mm to 30mm.

[0025] Furthermore, the preset processing area of ​​the outer skin in step 2 is located in the middle of the upper and lower edges of the inner side of each outer skin.

[0026] Furthermore, the step of trial-fitting the outer skin and the honeycomb core in step 4 includes:

[0027] S1. Lay insulating material, air guide material and vacuum bag film on the outer surface of the outer skin in order from the inside to the outside to form a vacuum device, and fasten the outer skin and the honeycomb core by vacuuming at room temperature;

[0028] S2. Turn on the vacuum device set in step S1, remove the outer skin, check the honeycomb bonding status, straighten the unevenly bonded areas of the honeycomb and the partially collapsed edges of the honeycomb core, and complete the trial assembly and bonding of the outer skin.

[0029] Furthermore, during the curing process of the product in step seven, the temperature rise curve is monitored to ensure that the temperature difference at each location of the product is no more than 5°C.

[0030] The beneficial effects of the present invention compared with the prior art are:

[0031] (1) The present invention realizes the integral forming of a large-sized tail skirt honeycomb sandwich structure by forming the tail skirt honeycomb sandwich structure with a positive mold. Compared with the method of forming the tail skirt with a negative mold, the mold size is greatly reduced. The prepared tail skirt honeycomb sandwich structure has a taper of 1.6 mm, which is better than the design index of 3 mm. The product taper is controllable and can be applied to a taper section radius in the range of R1000 mm to R5000 mm, a total height not exceeding 2000 mm, and a wall thickness in the range of 10 to 100 mm.

[0032] (2) The "zero expansion" mold used in the present invention solves the problem that the product fits the mold surface at room temperature, but the surface size cannot be guaranteed after the surface expands at high temperature.

[0033] (3) The present invention innovatively uses the inner skin as the molding surface providing surface and packaging surface for product molding, solving the difficult problem that the mold must be sealed as a whole or as a whole by splicing.

[0034] (4) In the design of the inner skin male mold tooling, the taper angle of the male mold is compensated by mechanical simulation, and the expansion of the mold and the situation in the hot pressure field are scientifically considered. Based on this, the process design is reasonably optimized to improve the accuracy of composite material molding. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Honeycomb sandwich structure diagram of the tail skirt

[0036] Figure 2 Forming process of honeycomb sandwich structure for tail skirt

[0037] Figure 3 Schematic diagram of the inner skin forming tooling of the honeycomb sandwich structure of the tail skirt of the present invention

[0038] Figure 4 Schematic diagram of the outer skin forming tooling for the honeycomb sandwich structure of the tail skirt of the present invention

[0039] Figure 5 Schematic diagram of the tail skirt honeycomb sandwich structure forming tooling of the present invention

[0040] Figure 6 This is the front view of the tail skirt honeycomb sandwich structure forming tooling of the present invention

[0041] Figure 7 This is a cross-sectional view of the tooling for forming the honeycomb sandwich structure of the tail skirt of the present invention.

[0042] Figure 8Bottom view of the tail skirt honeycomb sandwich structure forming tooling of the present invention DETAILED DESCRIPTION

[0043] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings.

[0044] like Figure 1 As shown, the honeycomb sandwich structure of the optical cabin tail skirt formed by the method of the present invention has a taper better than 2mm; the structural dimensions of the formable cone segment rotation body include: the cone segment radius is in the range of 1000mm to 5000mm, the total height is not more than 2000mm, and the wall thickness is in the range of 10 to 100mm.

[0045] Figure 2 The present invention provides a tail skirt honeycomb sandwich structure cone segment forming process method, comprising the following steps:

[0046] Step 1: Determine the product molding process plan based on the configuration of the tail skirt honeycomb sandwich structure. The inner skin is formed by an integral male mold, the outer skin is formed by a female mold, and the honeycomb sandwich structure uses a "zero expansion" male mold;

[0047] Step 2: Based on the product profile of the honeycomb sandwich structure of the tail skirt, perform mechanical simulation to determine the taper angle of the inner skin mold and design the inner skin molding tooling;

[0048] The specific method is as follows: the taper angle of the male mold is simulated by python thermodynamic dynamic simulation, the actual position of the inner skin male mold tooling in the autoclave is simulated by mechanical simulation, and according to the distribution of the temperature field in the autoclave, the theoretical required surface achieved by the inner skin male mold tooling during high-temperature molding is set, and the theoretical required surface achieved during high-temperature molding is determined as the required theoretical surface when cooled to room temperature through mechanical simulation, and the inner skin is processed and formed using this surface.

[0049] Step 3: The inner skin is formed according to the formulated process plan and the designed inner skin tooling. The 0° ply orientation is defined as the direction of the cone section busbar of the tail skirt honeycomb sandwich structure. The ply order when preparing the inner skin is: 0°, 45°, -45°, 90°. The 0°, 45°, and -45° plies are laid using 50mm wide prepreg, with gaps filled. The 90° ply is laid using 20mm wide narrow strips.

[0050] Step 4: Design the outer skin forming tooling based on the product profile of the honeycomb sandwich structure of the tail skirt;

[0051] Step 5: Form the outer skin according to the formulated process plan and the designed outer skin tooling. The outer skin is laid out in the same way as the inner skin.

[0052] Step 6: Based on the product profile of the honeycomb sandwich structure of the tail skirt, a "zero expansion" molding tooling is designed. The "zero expansion" is achieved by using a conical segment split dimensional profile in conjunction with a carbon fiber honeycomb sandwich structure bottom plate. The tooling includes a connecting ring 1, 36 upper baffles 2, 16 tail skirt assembly molding dies 3, 36 lower baffles 4, 8 bottom plate connecting plates 5, 4 bottom plates 6, and 8 bottom plate connecting strips 7.

[0053] Step 7: Complete the assembly and surface treatment of the tail skirt honeycomb sandwich structure forming tooling. The specific assembly process of the tooling is as follows:

[0054] The upper sides of the 16 tail skirt assembly forming dies are connected by connecting rings, and the connecting ring 1 is connected to the tail skirt assembly forming die 3 by pins and screws; the lower sides are connected by the bottom plate 6, and the bottom plate 6 is connected to each tail skirt assembly forming die 3 by pins and screws; the four bottom plates 6 are connected by 8 bottom plate connecting plates 5 and 8 bottom plate connecting strips 7; wherein: the upper sides of the joints of every two bottom plates 6 are connected by 2 bottom plate connecting plates 5, and each bottom plate connecting plate 5 is connected to the bottom plate 6 by screw fastening and at least 4 pins for positioning, and each bottom plate connecting strip 7 is connected to the bottom plate 6 by screw fastening to avoid the situation where the bottom plate is forced to open in an "eight" shape; the bottom plate 6 is in small-area contact with the 16 tail skirt assembly forming dies 3 through reserved bosses on both sides;

[0055] The materials of the tooling are as follows:

[0056] The connecting ring 1 is made of steel, the tail skirt assembly forming mold 3 is made of cast steel, the bottom plate connecting plate 5, the bottom plate 6, and the bottom plate connecting strip 7 are made of carbon-skinned honeycomb sandwich structure plates, and the upper baffle 2 and the lower baffle 4 are both made of aluminum.

[0057] The use principle of tooling:

[0058] The outer sides of the 16 tail skirt assembly forming dies 3 provide the dimensional surface for forming the tail skirt honeycomb sandwich structure. The upper and lower baffles 2 and 4 are used to fix the upper and lower sides of the tail skirt honeycomb sandwich structure.

[0059] Surface treatment of tooling:

[0060] The 16-piece tail skirt assembly forming die 3 needs to be degreased and cleaned with solvents at high temperature before use;

[0061] Step 8: Match and install the inner skin of the product formed in step 2 with the tail skirt honeycomb sandwich structure forming tooling;

[0062] Step 9: Grind the inner skin of the product formed in step 2, wipe it with solvent and let it dry;

[0063] Step 10: Determine the splicing size of the honeycomb core according to the product's profile and curvature, and cut the honeycomb core to the required size. Cut the honeycomb into a trapezoid that fits the mold well.

[0064] Step 11: Apply primer to the inner surface of the product processed in step 9 and apply adhesive film;

[0065] Step 12: Lay the honeycomb core cut in step 10 on the inner skin according to the process design;

[0066] Step 13: Brush the surface of the outer skin formed in step 4 with primer, apply the adhesive film, and do not remove the release paper;

[0067] Step 14: Test-fit the outer skin processed in step 13 and the honeycomb core that has been attached in step 12 to ensure that the outer skin is evenly distributed and determine the position of the outer skin positioning embedded parts;

[0068] Step 15: Use room temperature adhesive to bond and fix the outer skin positioning embedded parts to the inner skin;

[0069] Step 16: Use the method of step 15 to paste the outer skin positioning embedded parts in the upper and lower center positions of the outer skin to fully ensure the extension of the outer skin and the fit with the honeycomb;

[0070] Step 17: Lay the isolation material, air guide material and vacuum bag film in sequence on the outer surface of the product that has been processed in step 16, and use vacuum extraction at room temperature to achieve a good fit between the outer skin and the product.

[0071] Step 18: Open the vacuum device made in step 17, remove the auxiliary materials and take down the outer skin, check the honeycomb bonding status, and straighten the poorly bonded honeycomb areas and the partially collapsed honeycomb areas;

[0072] Step 19: Install the baffles on the upper and lower sides of the inner skin according to the size and position of the outer skin. The baffles are designed conical baffles and are fixed by physical bonding materials.

[0073] Step 20: Remove the outer skin isolation material removed in step 18, and then use the outer skin positioning block to achieve a good fit between the outer skin and the honeycomb;

[0074] Step 21: Lay the outer surface of the product prepared in step 20 with isolation material, air guide material, and vacuum bag film in sequence, and arrange the vacuum nozzles and thermocouples according to the process design. Place four vacuum nozzles on the product side of the upper baffle and four on the product side of the lower baffle, with the nozzles evenly distributed and staggered up and down.

[0075] Step 22: Transfer the product from step 21 to the autoclave and place the product in the designated location according to the process design requirements;

[0076] Step 23: The product of step 22 is cured according to the set curing system. The temperature rise curve is monitored during the process to ensure that the temperature difference of the product is no more than 5°C. A thermocouple is placed on the upper and lower sides of the product tank door, one on the upper edge of the side, and one on the upper and lower sides opposite the tank door.

[0077] Step 24: Take the product cured in step 23 out of the can, demould, and make corrections, and then conduct physical index testing, non-destructive testing, and mechanical testing of the product.

[0078] Example 1:

[0079] In development Figure 1 When the honeycomb sandwich structure of the tail skirt is shown, the product molding plan is first determined. The inner skin is formed by an integral positive mold, and the outer skin flaps are formed by a negative mold. The honeycomb sandwich structure uses a "zero expansion" mold. The mold process is simulated according to the product size, and the final size of the mold is determined based on the simulation results and engineering experience.

[0080] like Figure 3 、 Figure 4 、 Figure 5 As shown, the inner skin forming tooling, outer skin forming tooling, and tail skirt sandwich structure forming tooling are processed respectively. After the mold processing is completed, the casting mold or part of the casting mold parts are degreased and solvent wiped, and the non-casting parts are only wiped. According to the established process plan and the designed skin tooling, the inner and outer skins are formed respectively. The 0° ply orientation is defined as the direction of the cone section busbar of the tail skirt honeycomb sandwich structure. The ply order when preparing the inner and outer skins is: 0°, 45°, -45°, 90°; 0°, 45°, -45° plies use 50mm wide prepreg, and the gaps are filled with material. The 90° plies are laid using 20mm wide narrow strips.

[0081] During the curing process, ventilation channels are designed to seal and solidify the product. The mold is assembled according to the tooling drawings for the honeycomb sandwich structure of the tail skirt.

[0082] like Figures 6 to 8 As shown: the upper sides of the 16 tail skirt assembly 3 forming dies are connected by a connecting ring 1, and the connecting ring 1 and the tail skirt assembly forming dies 3 are connected by pins and screws; the lower sides are connected by a base plate 6, and the base plate 6 and each tail skirt assembly forming die 3 are connected by pins and screws; the four base plates 6 are connected by eight base plate connecting plates 5 and eight base plate connecting strips 7; the base plate 6 achieves small-area contact with the 16 tail skirt assembly forming dies 3 through reserved bosses on both sides.

[0083] After mold assembly is complete, the inner skin is matched and installed with the tail skirt honeycomb sandwich structure forming tooling. After the test assembly, the inner skin is polished, wiped with solvent, and air-dried. The honeycomb core splicing dimensions are determined based on the product's profile and curvature, and the honeycomb core is cut to the required size. The honeycomb is cut into a trapezoidal shape that fits the mold well. The formed outer skin is coated with primer and film, leaving the release paper on. The outer skin and honeycomb core are test-assembled and fitted to ensure uniform distribution of the outer skin. The position of the outer skin positioning embedded parts is also determined.

[0084] The outer skin positioning inserts are bonded and fixed to the inner skin using room-temperature adhesive. By attaching the outer skin positioning inserts to the center of the upper and lower outer skin, the outer skin's extension and fit within the honeycomb are fully guaranteed. Isolation material, air-conducting material, and vacuum bagging are sequentially applied to the treated product's outer surface. A vacuum is then applied at room temperature to ensure a perfect fit between the outer skin and the product.

[0085] After removing the auxiliary materials, remove the outer skin and check the honeycomb bonding status. Straighten the honeycomb bonding areas and local honeycomb collapse areas. Install the retaining bars on the upper and lower sides of the inner skin according to the size and position of the outer skin. The retaining bars are designed with conical surfaces and are fixed by physical bonding materials.

[0086] The removed outer skin insulation material is removed, and the outer skin positioning blocks are then used to ensure a good fit between the outer skin and the honeycomb. Insulation material, air guide material, and vacuum bagging film are sequentially laid on the product's outer surface. Vacuum nozzles and thermocouples are arranged according to the process design. Four vacuum nozzles are placed on the product side of the upper baffle and four on the product side of the lower baffle, with the nozzles evenly spaced and staggered vertically. The product is transferred to the autoclave and positioned in the designated location according to the process design.

[0087] The product is cured according to the set curing system. The temperature rise curve is monitored during the process to ensure that the temperature difference of the product is no more than 5°C. A thermocouple is placed on the upper and lower sides of the product tank door, one on the upper and lower sides opposite the tank door, and one on the upper edge of the side between the product tank door and the opposite side of the tank door. The cured product is taken out of the tank, demoulded, and corrected. The physical index detection, non-destructive testing and mechanical test piece testing of the product are carried out.

[0088] The tail skirt honeycomb sandwich structure forming tooling proposed in the present invention has the following advantages:

[0089] (a) The tail skirt honeycomb sandwich structure forming tool of the present invention can directly form the tail skirt honeycomb sandwich structure. The inner skin of the structure is integrally formed, and the structure has high strength and can withstand a 160-ton static test assessment.

[0090] (b) The "zero expansion" mold used in the present invention solves the problem that the product fits the mold surface at room temperature, but the surface size cannot be guaranteed after the high-temperature expansion surface expands.

[0091] (c) This invention uses ordinary steel as the mold body to achieve "zero expansion" of the mold. A clever design enlarges the inner skin, where the product is solidified and encapsulated. This cleverly resolves the difficult problem of achieving "zero expansion" while still meeting airtightness requirements.

[0092] (d) The tooling design process of the present invention is fully simulated and calculated, and the expansion of the mold and the conditions in the hot pressing field are scientifically considered. Based on this, the process design is rationally optimized to improve the accuracy of composite material molding.

[0093] (e) The inner skin of the present invention adopts a positive mold design. In order to reduce the workload of mold machining, no glue guide groove is machined. Based on the research on resin properties, a perforated aluminum liner is designed to solve the air conduction problem during the curing of the inner skin.

[0094] Any matters not described in detail in the present specification are well-known to those skilled in the art. Although the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Any person skilled in the art may utilize the methods and techniques disclosed above to make possible changes and modifications to the technical solutions of the present invention without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent variations, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention are within the scope of protection of the technical solutions of the present invention.

Claims

1. A process for forming a tail skirt honeycomb sandwich structure cone section, the product is a tail skirt honeycomb sandwich structure, including an inner skin, an outer skin and a honeycomb core, the honeycomb core is attached to the outer surface of the inner skin, and the outer skin is placed outside the honeycomb core; characterized in that: The steps are as follows:

1. According to the product profile of the tail skirt honeycomb sandwich structure, the inner skin forming tooling is prepared as a positive mold tooling, the outer skin forming tooling is prepared as a negative mold tooling, and the tail skirt honeycomb sandwich structure forming tooling is prepared as a "zero expansion" mold; the tail skirt honeycomb sandwich structure forming tooling adopts a cone-segment split dimensional profile in combination with a carbon fiber honeycomb sandwich structure bottom plate to achieve "zero expansion"; it comprises a connecting ring (1), M upper baffles (2), N tail skirt assembly forming dies (3), M lower baffles (4), 2P bottom plate connecting plates (5), P bottom plates (6) and 2P bottom plate connecting strips (7); M>1, N>1, P>1; 2. Use the inner skin forming tool to prepare the inner skin, use the outer skin forming tool to prepare the outer skin and stick the release paper, place the outer skin positioning embedded parts in the preset processing areas on the upper and lower sides of the center of the outer skin, and determine the splicing size of the honeycomb core and cut it according to the surface and curvature of the honeycomb sandwich structure of the tail skirt; 3. The inner surface of the inner skin is attached to the outer side of the tail skirt honeycomb sandwich structure forming tooling, and the inner skin is polished, cleaned and dried; the outer surface of the inner skin is brushed with primer, and the adhesive film is applied to fit the cut honeycomb core; Fourth, apply primer to the inner surface of the outer skin, apply adhesive film, and do not remove the release paper. Perform a trial assembly with the honeycomb core in step 3 to ensure that the outer skin is evenly distributed and determine the position of the outer skin positioning embedded parts. The outer skin positioning embedded parts are bonded to the inner skin and cured. Install the blocking strips on the upper and lower sides of the inner skin.

5. Remove the outer skin release paper and use the outer skin positioning embedded parts to achieve the outer skin and honeycomb bonding; 6. Lay the insulation material, air guide material and vacuum bag film on the outer surface of the outer skin from the inside to the outside, arrange the vacuum nozzle and thermocouple, and package the product; then transfer it to the autoclave and place the product in the designated position; 7. The product is cured, unpacked, demoulded, and product indicators are tested.

2. The method for forming a cone section of a tail skirt honeycomb sandwich structure according to claim 1, characterized in that: The inner skin forming tool is designed and prepared by the following method: S1. Use Python thermodynamic dynamic simulation to simulate the actual position of the inner skin male mold tooling in the autoclave. According to the distribution of the temperature field in the autoclave, set the theoretical required surface of the inner skin male mold tooling during the preset high-temperature molding; S2. The theoretical required surface achieved during high-temperature forming is cooled to room temperature using Python thermodynamic dynamic simulation to obtain the final required theoretical surface, which is then used to process and form the inner skin.

3. The method for forming a cone section of a tail skirt honeycomb sandwich structure according to claim 1, characterized in that: In the step 1, 4 to 8 air guide channels are evenly and staggeredly reserved on the upper and lower sides of the inner skin forming tooling.

4. The method for forming a cone section of a tail skirt honeycomb sandwich structure according to claim 1, characterized in that: The assembly method of the tail skirt honeycomb sandwich structure forming tooling is: The upper sides of the S1 and N tail skirt assembly forming dies (3) are connected by a connecting ring (1), and the lower sides are connected by a bottom plate (6), providing a dimensional surface for forming the tail skirt honeycomb sandwich structure; The S2 and P bottom plates (6) are connected by 2P bottom plate connecting plates (5) and 2P bottom plate connecting strips (7), wherein: the upper side of each two bottom plates (6) is connected by 2 bottom plate connecting plates (5), each bottom plate connecting plate (5) is connected to the bottom plate (6) by screw fastening and at least 4 pins for positioning, and each bottom plate connecting strip (7) is connected to the bottom plate (6) by screw fastening, so as to avoid the bottom plate from being opened in an "eight" shape under stress; S3, the upper baffle (2) and the lower baffle (4) adopt conical baffles to fix the upper and lower sides of the honeycomb sandwich structure of the tail skirt; the upper baffle (2) is installed on the upper edge of the inner skin, corresponding to the top of the outer skin, and the lower baffle (4) is installed on the lower edge of the inner skin, corresponding to the bottom of the outer skin, and the baffles are fixed by physical bonding materials.

5. The method for forming a cone section of a tail skirt honeycomb sandwich structure according to claim 4, characterized in that: The connecting ring (1) is made of steel, the tail skirt assembly forming die (3) is made of cast steel, the bottom plate connecting plate (5), the bottom plate (6), and the bottom plate connecting strip (7) are made of carbon-skinned honeycomb sandwich structure plates, and the upper baffle (2) and the lower baffle (4) are both made of aluminum.

6. The method for forming a cone section of a tail skirt honeycomb sandwich structure according to claim 1, characterized in that: The second step is to prepare the inner skin by integral molding and prepare the outer skin by flap molding.

7. The method for forming a cone section of a tail skirt honeycomb sandwich structure according to claim 1, characterized in that: The 0° ply orientation is defined as the busbar direction of the cone section of the tail skirt honeycomb sandwich structure. The ply order in preparing the inner skin in step 2 is: 0°, 45°, -45°, 90°; the 0°, 45°, and -45° plies are laid using prepregs with a width of 40mm to 60mm, with gaps filled with material. The 90° ply is laid using narrow strips with a width of 10mm to 30mm.

8. The method for forming a cone section of a tail skirt honeycomb sandwich structure according to claim 1, characterized in that: In the second step, the preset processing area of ​​the outer skin is located in the middle of the upper and lower edges of the inner side of each outer skin.

9. The method for forming a cone section of a tail skirt honeycomb sandwich structure according to claim 1, characterized in that: The step of trial-fitting the outer skin and the honeycomb core in step 4 includes: S1. Lay insulating material, air guide material and vacuum bag film on the outer surface of the outer skin in order from the inside to the outside to form a vacuum device, and fasten the outer skin and the honeycomb core by vacuuming at room temperature; S2. Turn on the vacuum device set in step S1, remove the outer skin, check the honeycomb bonding status, straighten the unevenly bonded areas of the honeycomb and the partially collapsed edges of the honeycomb core, and complete the trial assembly and bonding of the outer skin.

10. The method for forming a cone section of a tail skirt honeycomb sandwich structure according to claim 1, characterized in that: During the curing process of the product in step 7, the temperature rise curve is monitored to ensure that the temperature difference at each location of the product is no more than 5°C.

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