A preparation method for a large main load-bearing composite material structure and a molding die used therefor

Abstract

A preparation method for a large main load-bearing composite material structure and a molding die used therefor belong to the field of preparation of composite material structures. In order to solve the problem that the prior art lacks appropriate molding dies and relatively complex processes in the preparation of composite material structural parts, which greatly affects the preparation efficiency and also increases the probability of defects in the product during the molding process and in the later stage of molding, the upper pressure plate, the split mold assembly and the lower pressure plate in the molding die of the present invention are arranged in sequence from top to bottom, and the upper pressure plate and the split mold assembly are detachably connected by a connecting piece, the split mold assembly and the lower pressure plate are detachably connected by a connecting piece, the circumferential reinforcement assembly is sleeved on the outer circumferential surface of the upper pressure plate and the lower pressure plate, and the circumferential reinforcement assembly is tightly fitted with the upper pressure plate and the lower pressure plate, and a new preparation method is proposed using the above-mentioned mold. The present invention is mainly used for the preparation of large main load-bearing composite material structures.

Description

Technical Field

[0001] The invention belongs to the field of preparation of composite material structures, and in particular relates to a preparation method of a large-scale main load-bearing composite material structure and a forming mold used therefor. Background Art

[0002] Carbon fiber reinforced resin-based composite structural parts have been widely used in production and life, especially in the fields of aviation and aerospace. How to meet the predetermined design indicators and ensure that the fiber effectively transfers loads and effectively carries loads during the production of composite materials is the focus of process research. This invention describes a process optimization method for composite structural parts used in space stations.

[0003] The use conditions of composite components in space stations are harsh. In space, composite components will face weightlessness, radiation, and various unexpected challenges. At the same time, they need to withstand large loads. Each docking cabin weighs more than 20 tons (docking manned spacecraft, cargo spacecraft, etc.). Complex configuration is the characteristic of composite structural parts used in space stations.

[0004] As a composite structural part with an interface, the challenges it faces are self-evident. During the design, it is necessary to check the load-bearing capacity of the interface countless times, and at the same time, reduce its mass to a minimum and control costs while ensuring necessary conditions such as stiffness and strength. Therefore, how to effectively meet the design indicators has become the top priority of the process.

[0005] After the composite material main load-bearing structural parts are formed, the overall flatness of individual positions must be less than 0.12mm, and the flatness of a specified single surface must be less than 0.03mm.

[0006] Composite material main load-bearing structural parts need to be compacted and if there are internal defects, they must meet the corresponding flaw detection standards. This is because the internal stratification defects of composite materials have a direct impact on the stiffness and strength of the product, affecting the mechanical properties.

[0007] At the same time, the surface must be clean, pollution-free, without visible scratches, indentations, no broken fibers, and a flat surface.

[0008] The existing technology in the preparation of composite material structural parts has a great impact on the preparation efficiency due to the lack of appropriate molding molds and relatively complex processes. It also increases the probability of defects in the product during the molding process and the later stage of molding. Therefore, through reasonable process configuration, the main load-bearing structural parts of composite materials can be effectively molded to meet all design requirements. It is of great significance to the actual production process. Summary of the invention

[0009] The present invention aims to solve the problem that the existing technology lacks appropriate molding dies and relatively complicated processes in the preparation of composite material structural parts, which greatly affects the preparation efficiency and increases the probability of defects in the product during the molding process and the later stage of molding, and thus provides a preparation method for a large main load-bearing composite material structure and a molding die used therefor;

[0010] A forming mold for a large main load-bearing composite material structure, the forming mold comprising an upper pressing plate, a lower pressing plate, a circumferential reinforcement assembly and a flap mold assembly, the upper pressing plate, the flap mold assembly and the lower pressing plate are arranged in sequence from top to bottom, and the upper pressing plate and the flap mold assembly are detachably connected by a connecting piece, the flap mold assembly and the lower pressing plate are detachably connected by a connecting piece, the circumferential reinforcement assembly is sleeved on the outer circumferential surfaces of the upper pressing plate and the lower pressing plate, and the circumferential reinforcement assembly is tightly fitted with the upper pressing plate and the lower pressing plate.

[0011] Further, the circumferential reinforcement assembly includes a circumferential inner pressure plate, an annular mold-matching force plate and a circumferential outer pressure plate, the circumferential inner pressure plate is sleeved on the outer circumferential surfaces of the upper pressure plate and the lower pressure plate, and the circumferential inner pressure plate is tightly fitted with the upper pressure plate and the lower pressure plate, the circumferential outer pressure plate is sleeved on the outer circumferential surface of the circumferential inner pressure plate, the annular mold-matching force plate is arranged between the circumferential outer pressure plate and the circumferential inner pressure plate, and the circumferential outer pressure plate is tightly fitted with the circumferential inner pressure plate through the annular mold-matching force plate;

[0012] Furthermore, the split-flap mold assembly comprises eight groups of split-flap molds, each of which is detachably connected to the upper pressing plate and the lower pressing plate via a connecting piece;

[0013] Further, the connecting member is a bolt and nut mechanism;

[0014] Furthermore, the split mold includes a positioning core, a plurality of side pressure blocks and a plurality of rubber sheets, the top of the positioning core is processed with N No. 1 connecting through holes, N is a positive integer, the side pressure blocks are sleeved on the side walls of the positioning core, and the side pressure blocks are detachably connected to the positioning core, and the rubber sheets are sleeved on the outer walls of the side pressure blocks;

[0015] Furthermore, a plurality of No. 2 connecting through holes are processed on the end surfaces of the upper pressing plate and the lower pressing plate, and each No. 2 connecting through hole is arranged corresponding to a No. 1 connecting through hole in the split-flap mold.

[0016] A method for forming a large-scale main load-bearing composite material structure is achieved by the following steps:

[0017] Step 1: First, fix the lower pressing plate, and lay the carbon fiber composite material prepreg layer by layer on the lower pressing plate. According to the size of the composite material load-bearing structure to be formed, lay 12 to 20 layers in total;

[0018] Step 2: each split mold in the laid-out split mold assembly is fixed to the upper surface of the lower pressing plate by fastening bolts according to the corresponding position on the lower pressing plate, so as to form a complete split mold assembly;

[0019] Step 3: On the upper surface of the split mold assembly, lay the carbon fiber composite material prepreg layer by layer, and lay 12 to 20 layers in total according to the size of the main load-bearing structure of the composite material to be formed;

[0020] Step 4: An upper pressing plate is arranged on the carbon fiber composite material on the split mold assembly, ensuring that the No. 2 connecting through hole on each upper pressing plate is sleeved on the fastening bolts used to connect the split mold and the lower pressing plate, and a nut is sleeved on each fastening bolt extending from the top of the upper pressing plate;

[0021] Step 5: Close the mold by rotating the nut on the top of the upper pressing plate to make the upper pressing plate move linearly downward, and at the same time, compress the composite material prepreg between the upper pressing plate and the split mold assembly until the mold clearance between the upper pressing plate 2 and the split mold assembly is less than 0.1, and then cure for 9 hours;

[0022] Step 6: After curing and molding, demould, loosen the nuts on the top of the upper pressing plate one by one, and separate the upper pressing plate from the split mold assembly;

[0023] Step 7: Clean the overflowed composite material around each split mold, and cut it before demoulding according to the position reserved for process cutting allowance in the design;

[0024] Step 8: Demold the split molds in the bite state in sequence according to the design requirements. The demolding order is the positioning core, several side pressure blocks and rubber sheets.

[0025] Further, in the step 4, the height of the positioning core is designed to be 5 mm to 10 mm higher than the theoretical height of the product;

[0026] Furthermore, in the step 4, the plurality of rubber sheets in each petal mold are all silicone rubber sheets with a thickness of 1 mm to 5 mm.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] Compared with the prior art, the present invention provides a preparation method for a large-scale main load-bearing composite material structure and a molding mold used therefor. The molding mold adopts the design concept of a split mold, which avoids the inconvenience of installing and demolding the entire mold, improves the demolding efficiency, and greatly improves the success rate of demolding, thereby avoiding defects in the product during demolding. Secondly, the present invention provides a preparation method in which, during the mold closing process, force is applied to the upper pressure plate so that the upper pressure plate is gradually pressed against the lower pressure plate, thereby effectively eliminating bubbles generated in the product during the molding process and improving the quality of product molding. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A top view of the molding fixture of the present invention;

[0030] Figure 2 It is a main sectional partial view of the forming fixture in the present invention;

[0031] Figure 3 is a schematic diagram of a circumferential reinforcement assembly in the present invention;

[0032] Figure 4 It is a schematic diagram of the split-petal mold in the present invention;

[0033] Figure 5 It is a schematic front view of the central split-petal mold in the present invention;

[0034] Figure 6 Schematic diagram of the positioning core of the central split mold in the present invention;

[0035] Figure 7 It is a schematic diagram of the side pressing block of the center split mold in the present invention;

[0036] Figure 8 Schematic diagram of the rubber sheet of the center split mold in the present invention;

[0037] Fig. 9 It is a schematic diagram of the fan-shaped composite structure after forming in the present invention;

[0038] Fig.10 The figure is a schematic diagram of the distribution of 8 petal molds in the present invention;

[0039] In the figure, 1 is an upper pressure plate, 2 is a lower pressure plate, 3 is a circumferential reinforcement assembly, 31 is a circumferential inner pressure plate, 32 is an annular mold clamping force plate, 33 is a circumferential outer pressure plate, 4 is a split mold, 41 is a positioning core, 42 is a side pressure block, 43 is a rubber sheet and 5 is a composite material component. DETAILED DESCRIPTION

[0040] Specific implementation method 1: refer to Figures 1 to 5 The present embodiment is described. The present embodiment provides a preparation method of a large main load-bearing composite material structure and a molding die used therefor. The molding die comprises an upper pressing plate 1, a lower pressing plate 2, a circumferential reinforcement assembly 3 and a flap mold assembly. The upper pressing plate 1, the flap mold assembly and the lower pressing plate 2 are arranged in sequence from top to bottom, and the upper pressing plate 1 and the flap mold assembly are detachably connected by a connecting piece, the flap mold assembly and the lower pressing plate 2 are detachably connected by a connecting piece, the circumferential reinforcement assembly 3 is sleeved on the outer circumferential surfaces of the upper pressing plate 1 and the lower pressing plate 2, and the circumferential reinforcement assembly 3 is tightly fitted with the upper pressing plate 1 and the lower pressing plate 2.

[0041] In this embodiment, the molding mold is a metal combination mold. When designing the mold, the wall thickness and molding quality of the composite material component are fully considered. A split-split mold and a covering expansion rubber are used to facilitate demolding after molding and curing and pressurization during molding. In the mold, a glue overflow hole is added in the lower pressure plate 2, and 8 to 16 glue overflow holes are added to the outer edge of the mold flange. Improve the mold closed cavity structure, and facilitate the flow of resin and the removal of interlayer air during mold closing and curing. During the molding, define the center of the layer, establish a Cartesian coordinate system, divide the overall mold into quadrants, and lay the whole, split mold, assemble, and lay the whole according to the quadrants. During the laying process, the fiber is continuous and there is no interface at the corner to perform molding.

[0042] Specific implementation method 2: refer to Figure 4 This embodiment is described. This embodiment further limits the circumferential reinforcement assembly 3 described in the specific embodiment 1. In this embodiment, the circumferential reinforcement assembly 3 includes a circumferential inner pressure plate 31, an annular mold clamping force plate 32 and a circumferential outer pressure plate 33. The circumferential inner pressure plate 31 is sleeved on the outer circumferential surface of the upper pressure plate 1 and the lower pressure plate 2, and the circumferential inner pressure plate 31 is tightly fitted with the upper pressure plate 1 and the lower pressure plate 2. The circumferential outer pressure plate 33 is sleeved on the outer circumferential surface of the circumferential inner pressure plate 31. The annular mold clamping force plate 32 is arranged between the circumferential outer pressure plate 33 and the circumferential inner pressure plate 31. The circumferential outer pressure plate 33 is tightly fitted with the circumferential inner pressure plate 31 through the annular mold clamping force plate 32. Other components and connection methods are the same as those in the specific embodiment 1.

[0043] In this embodiment, the circumferential reinforcement component 3 mainly plays the role of circumferential fixing, limiting and sealing, so as to prevent a large amount of overflow of the composite material after being stressed during the mold closing process.

[0044] Specific implementation method three: refer to Figure 1 This embodiment is described. This embodiment further limits the split mold assembly described in the first embodiment. In this embodiment, the split mold assembly includes eight split molds 4, each of which is detachably connected to the upper pressing plate 1 and the lower pressing plate 2 through a connecting piece. Other components and connection methods are the same as those in the first embodiment.

[0045] In this embodiment, the eight petal molds 4 are planned according to the composite material structure to be manufactured. Fig. 9 and Fig.10 As shown, each through hole in each composite material structure is provided with a split mold, so the eight split molds 4 specifically include two triangular split molds and six circumferential split molds. The triangular split molds are located at both ends of the fan; the six circumferential split molds are arranged between the two triangular split molds, and the six circumferential split molds are arranged along one side of the circumference. (Modify the product appearance description)

[0046] Specific implementation method 4: This implementation method further limits the connection member described in specific implementation method 1. In this implementation method, the connection member is a bolt and nut mechanism. Other components and connection methods are the same as those in specific implementation method 1.

[0047] Specific implementation method five: refer to Figures 5 to 9 This embodiment is described. This embodiment further limits the split mold 4 described in the specific embodiment 1. In this embodiment, the split mold 4 includes a positioning core 41, a side pressure block 42 and a rubber sheet 43. The top of the positioning core 41 is processed with N No. 1 connecting through holes, N is a positive integer, the side pressure block 42 is sleeved on the side wall of the positioning core 41, and the side pressure block 42 is detachably connected to the positioning core 41, and the rubber sheet 43 is sleeved on the outer wall of the side pressure block 42. Other components and connection methods are the same as those in the specific embodiment 1.

[0048] In this embodiment, the positioning core 41 is used to fix the upper pressure plate 1 and the lower pressure plate 2. The side pressure block 42 is used to fit the composite material structure. The contact surface between the petal mold 4 and the composite material structure is a rubber sheet 43. The rubber sheet 43 is a silicone rubber sheet with a thickness of 1mm-5mm. A release agent is coated on the outer surface of the rubber sheet 43, so that the surface of the composite material structure will not be damaged during demolding.

[0049] Specific implementation method six: refer to Figure 1 This embodiment is described. This embodiment further defines the upper pressing plate 1 and the lower pressing plate 2 described in the first embodiment. In this embodiment, a plurality of No. 2 connecting through holes are processed on the end faces of the upper pressing plate 1 and the lower pressing plate 2, and each No. 2 connecting through hole is arranged correspondingly to a No. 1 connecting through hole in the split mold 4. Other components and connection methods are the same as those in the first embodiment.

[0050] Specific embodiment 7: This embodiment provides a method for preparing a large-scale main load-bearing composite material structure, which is achieved by the following steps:

[0051] Step 1: First, fix the lower pressing plate 2, sleeve the circumferential reinforcement assembly 3 on the lower pressing plate 2, and lay the carbon fiber composite material prepreg layer by layer on the lower pressing plate 2. According to the size of the composite fan-shaped main load-bearing structure to be formed, lay 12-20 layers in total;

[0052] Step 2: each split mold 4 in the split mold assembly is fixed to the upper surface of the lower pressing plate 2 by fastening bolts according to the corresponding position on the lower pressing plate 2, so as to form a complete split mold assembly;

[0053] Step 3: On the upper surface of the split mold assembly, lay the carbon fiber composite material prepreg layer by layer, and lay 12-20 layers in total according to the size of the composite fan-shaped main load-bearing structure to be formed;

[0054] Step 4: An upper pressing plate 1 is arranged on the resin composite material on the split mold assembly, ensuring that the No. 2 connecting through hole on each upper pressing plate 1 is sleeved on the fastening bolts used to connect the split mold 4 and the lower pressing plate 2, and a nut is sleeved on each fastening bolt extending from the top of the upper pressing plate 1;

[0055] Step 5: Close the mold by rotating the nut on the top of the upper pressing plate 1 to make the upper pressing plate 2 move linearly downward, and at the same time, compress the resin composite material between the upper pressing plate 2 and the split mold assembly until the mold clearance between the upper pressing plate 2 and the split mold assembly is less than 0.1, and then cure for 9 hours;

[0056] Step 6: After curing and molding, demould, loosen the nuts on the top of the upper pressing plate 1 one by one, and separate the upper pressing plate 1 from the split mold assembly;

[0057] Step 7: Clean the overflowed composite material around each split mold, and cut it before demoulding according to the position reserved for process cutting allowance in the design;

[0058] Step 8: demoulding the split mold 4 in the bite state in sequence according to the design requirements, and the demoulding order is the positioning core 41, a plurality of side pressure blocks 42 and the rubber sheet 43.

[0059] In this embodiment, a pre-pressing mechanism is added when laying the carbon fiber composite material prepreg in step 1 and step 3. During the main body laying and molding process, a putty knife is used to press hard after each layer is laid to drive out bubbles; during the block mold laying process, vacuum pre-pressing is added in the middle process to eliminate bubbles in the molding process and prevent the generation of delamination between prepreg layers;

[0060] When the product is demoulded, the positioning core 41 is first lifted upward, and then the petal side pressure blocks 42 are taken out in turn, and finally the expansion rubber sheet 43 is taken out. This process reduces the impact of the mold release on the internal quality of the product contact surface during the mold demoulding process;

[0061] The integral molds are all detachable outer molds, and the overflow space between the outer mold and the product is increased to prevent the outer flange clamping material from being unable to be compacted and interlayer delamination caused by the relative movement of the product and the mold.

[0062] Specific implementation eight: This implementation further limits step four described in specific implementation seven. In this implementation, the positioning core 41 in each split mold 4 in step four is designed to be 5mm to 10mm higher than the product. Other components and connection methods are the same as those in specific implementation one.

[0063] Specific embodiment 9: This embodiment further limits step 4 described in specific embodiment 7. In this embodiment, the rubber sheets 43 in each split mold 4 in step 4 are all silicone rubber sheets with a thickness of 1 mm to 5 mm. Other components and connection methods are the same as those in specific embodiment 1.

[0064] In this embodiment, the mold reserve is inferred based on the maximum expansion of the rubber itself at 165°C to 175°C and the compression defined by the prepreg design. The expansion of the rubber sheet is used to apply pressure to compensate for the positions where the metal clamping force cannot be transmitted or is not directly applied, especially for the I-beam structure (the form of the composite material structure after molding) vertical ribs and the bottom surface of the upper pressure plate 1.

[0065] Embodiment 1:

[0066] This embodiment takes the forming process of an I-beam structure in which one part of the split mold has a height of 6 mm as an example.

[0067] First, disassemble all the detachable parts of the mold to avoid scratching the mold surface; clean the resin and other substances remaining on the mold surface; and clean the mold surface twice with acetone / cotton yarn;

[0068] Secondly, a 4.5mm thick expanded rubber sheet 43 is glued on the molding surface of the side pressure block 42 in the mold. The size of the rubber sheet 43 is 205mm×62mm, 315mm×59mm, etc. The mold release agent is evenly coated on the contact surface between the mold and the composite material for 2 to 3 times, and it is used after standing for 0.5h;

[0069] The circumferential fixing assembly 3 is sleeved on the lower pressing plate 2, and the prepreg is pasted on the upper surface of the lower pressing plate 2. The molding surface is required to be fully and evenly covered; according to the laying layer (0 / 90 / +45 / -45) ns Lay out and make records. Where n is the design value and s is the mirror image. After laying out each layer, compact it with a putty knife to remove bubbles. Trim the prepreg at the closed edge to ensure that the edges are neat so that the mold can be closed smoothly;

[0070] Attach prepreg to the surface of the installed split mold assembly, requiring the molding surface to be fully and evenly covered; lay up according to the layer (0 / 90 / +45 / -45) ns Lay out and make records. Where n is the design value and s is the mirror image. After laying out each layer, compact it with a putty knife to remove bubbles. Trim the prepreg at the closed edge to ensure that the edges are neat so that the mold can be closed smoothly;

[0071] Assemble the split mold assembly, and install each split mold 4 on the lower pressing plate 2 through a bolt and nut mechanism;

[0072] Set the upper pressing plate 1 on the split mold assembly, ensure that the No. 2 connecting through hole on each upper pressing plate 1 is sleeved on the fastening bolts used to connect the split mold 4 and the lower pressing plate 2, and a nut is sleeved on each fastening bolt extending from the top of the upper pressing plate 1; use bolts to pressurize the mold, and ensure that the front and rear positions of the molds are aligned when closing the mold. When closing the mold, tighten the pressure bolts symmetrically to close the upper and lower molds, pay attention to the alignment marks of the upper and lower molds, and ensure that the state of the top of the product is uniform and the fibers are flat;

[0073] After closing the mold, put the mold into the curing oven for heat sealing. Strictly follow the curing system.

[0074] After heat sealing and curing, take out the mold and cool it naturally to room temperature before demoulding. Remove all bolts, remove the upper pressure plate 1, remove the split mold 4 one by one (the demoulding order of the split mold 4 is the positioning core, several side pressure blocks, and rubber sheets), and take out the product. Be careful not to scratch the molding surface of the mold when demoulding.

[0075] After non-destructive testing, the composite material structural parts meet the design requirements, with the overall flatness of the specified part being 0.10mm and the flatness of the specified single surface being 0.01mm to 0.03mm.

Claims

1. A molding die for a large main load-bearing composite material structure, characterized in that: The molding die comprises an upper pressing plate (1), a lower pressing plate (2), a circumferential reinforcement component (3) and a split-flap mold component, wherein the upper pressing plate (1), the split-flap mold component and the lower pressing plate (2) are arranged in sequence from top to bottom, and the upper pressing plate (1) is detachably connected to the split-flap mold component via a connecting piece, and the split-flap mold component is detachably connected to the lower pressing plate (2) via a connecting piece, and the circumferential reinforcement component (3) is sleeved on the outer circumferential surfaces of the upper pressing plate (1) and the lower pressing plate (2), and the circumferential reinforcement component (3) is tightly fitted to the upper pressing plate (1) and the lower pressing plate (2); The circumferential reinforcement component (3) comprises a circumferential inner pressure plate (31), an annular mold-clamping force plate (32) and a circumferential outer pressure plate (33); the circumferential inner pressure plate (31) is sleeved on the outer circumferential surfaces of the upper pressure plate (1) and the lower pressure plate (2), and the circumferential inner pressure plate (31) is tightly fitted with the upper pressure plate (1) and the lower pressure plate (2); the circumferential outer pressure plate (33) is sleeved on the outer circumferential surface of the circumferential inner pressure plate (31), the annular mold-clamping force plate (32) is arranged between the circumferential outer pressure plate (33) and the circumferential inner pressure plate (31), and the circumferential outer pressure plate (33) is tightly fitted with the circumferential inner pressure plate (31) through the annular mold-clamping force plate (32); The split-flap mold assembly comprises eight split-flap molds (4), each of which is detachably connected to an upper pressing plate (1) and a lower pressing plate (2) via a connecting piece; The connecting piece is a bolt and nut mechanism; The split mold (4) comprises a positioning core (41), a side pressure block (42) and a rubber sheet (43); the top of the positioning core (41) is processed with N No. 1 connecting through holes, N being a positive integer; the side pressure block (42) is sleeved on the side wall of the positioning core (41), and the side pressure block (42) is detachably connected to the positioning core (41); and the rubber sheet (43) is sleeved on the outer wall of the side pressure block (42); A plurality of No. 2 connecting through holes are processed on the end surfaces of the upper pressing plate (1) and the lower pressing plate (2), and each No. 2 connecting through hole is arranged corresponding to a No. 1 connecting through hole in the petal mold (4).

2. Provide a method for preparing a large-scale main load-bearing composite material structure by using a molding die of a large-scale main load-bearing composite material structure in claim 1, characterized in that: The method is achieved by the following steps: Step 1: first, fix the lower pressing plate (2), and lay carbon fiber composite material prepreg on the lower pressing plate (2) layer by layer, laying 12 to 20 layers in total according to the size of the large composite material main load-bearing structure to be formed; Step 2: each of the split molds (4) in the split mold assembly is fixed to the upper surface of the lower pressing plate (2) one by one by means of fastening bolts according to the corresponding position on the lower pressing plate (2), so as to form a complete split mold assembly; Step 3: On the upper surface of the split mold assembly, lay carbon fiber composite material prepreg layer by layer, and lay 12-20 layers in total according to the size of the large main load-bearing structure of the composite material to be formed; Step 4: An upper pressing plate (1) is arranged on the resin composite material on the split mold assembly, ensuring that the No. 2 connecting through hole on each upper pressing plate (1) is sleeved on the fastening bolt used to connect the split mold (4) and the lower pressing plate (2), and a nut is sleeved on each fastening bolt extending from the top of the upper pressing plate (1); Step 5: close the mold by rotating the nut on the top of the upper pressing plate (1) to make the upper pressing plate (1) move linearly downward, and at the same time, compress the resin composite material between the upper pressing plate (1) and the split mold assembly until the mold clearance between the upper pressing plate (1) and the split mold assembly is less than 0.1, and then cure for 9 hours; Step 6: After curing and molding, demoulding is performed, and the nuts on the top of the upper pressing plate (1) are loosened one by one, and the upper pressing plate (1) is separated from the split mold assembly; Step 7: Clean the overflowed composite material around each split mold, and cut it before demoulding according to the position reserved for process cutting allowance in the design; Step 8: demoulding the split mold (4) in the engaged state in sequence according to the design requirements, wherein the demoulding order is the positioning core (41), the plurality of side pressure blocks (42) and the rubber sheet (43).

3. A method for preparing a large-scale main load-bearing composite material structure according to claim 2, characterized in that: In the step 4, the height of the plurality of positioning cores (41) in each petal mold (4) is designed to be 5 mm to 10 mm higher than the product.

4. A method for preparing a large-scale main load-bearing composite material structure according to claim 3, characterized in that: In the fourth step, the plurality of rubber sheets (43) in each petal mold (4) are all silicone rubber sheets with a thickness of 1 mm to 5 mm.

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