Pre-pressing tool and forming method for structural part boss and variable thickness area

Abstract

The present disclosure relates to the technical field of composite material load-bearing structure forming, and particularly relates to a structure boss and variable-thickness area pre-pressing tool and a forming method. The present disclosure provides a structure boss and variable-thickness area pre-pressing tool, which comprises a tool body and a plurality of pre-pressing parts, the plurality of pre-pressing parts are arranged at intervals along the circumference of the tool body, wherein the pre-pressing part comprises a mounting part and a pre-pressing part, the mounting part is connected with the tool body, and the pre-pressing part is in sliding connection with the mounting part. Through the technical scheme of the present disclosure, the shape size accuracy is ensured, the butt joint strength requirement of the boss and the variable-thickness area is improved, and the problem that the mechanical processing is difficult to ensure the shape size and internal quality of the carbon fiber special-shaped structure is solved.

Description

Technical Field

[0001] This disclosure relates to the field of composite material load-bearing structural component molding technology, and in particular to a pre-compression tooling and molding method for a structural component boss and variable thickness zone. Background Technology

[0002] Resin-based structural composite materials possess characteristics such as high strength, high modulus, corrosion resistance, and fatigue resistance, and are currently widely used in aerospace structural composite materials. To adapt to the research and production of different product models, diverse product structures have emerged. For one product model, to accommodate the assembly requirements of the large and small ends, the design incorporates variable thickness areas and irregularly shaped internal bosses. The molding process employs a layup-autoclave process. The small end of the product has multiple bosses, and the large end frame has multiple variable thickness areas. The bosses and variable thickness areas are relatively thick, while the boss dimensions are small, making it difficult to control the layup process along with the product, and thus impossible to precisely control the final dimensions after layup.

[0003] Therefore, ensuring the dimensional requirements of the boss and the variable thickness area is an urgent problem to be solved. Summary of the Invention

[0004] This disclosure aims to address at least one of the technical problems existing in the prior art or related technologies.

[0005] To this end, this disclosure provides a pre-compression fixture for a structural boss and a variable thickness region in a first aspect, comprising a fixture body and a plurality of pre-compression portions, wherein the plurality of pre-compression portions are arranged circumferentially spaced along the fixture body, wherein each pre-compression portion includes a mounting member and a pre-compression member, the mounting member being connected to the fixture body, and the pre-compression member being slidably connected to the mounting member.

[0006] In one feasible implementation, the system further includes a driving member connected to the pre-compression member, the driving member being used to apply a force from the pre-compression member to compact the structural member to be formed.

[0007] In one feasible implementation, the tooling body is configured as an annular shape, and the compaction direction of the pre-compression component is toward the center of the tooling body.

[0008] In one feasible implementation, the pre-compression component includes an adjusting component, a first pre-compression component, a second pre-compression component, and a positioning pre-compression component. The adjusting component is connected to the mounting component, and the first pre-compression component, the second pre-compression component, and the positioning pre-compression component are connected to the adjusting component. The adjusting component is used to adjust the pressure surface of one of the first pre-compression component, the second pre-compression component, and the positioning pre-compression component to face the structural component to be formed.

[0009] In one feasible implementation, a positioning element is also included, wherein the pre-compression part is slidably connected to the tooling body, and the positioning element is used to fix the relative position of the pre-compression part on the tooling body.

[0010] In one feasible implementation, the pre-compression component includes an adjusting rod and a pressure head, the adjusting rod being movably connected to the mounting component, and the pressure head being detachably connected to the adjusting rod.

[0011] A second aspect of this disclosure provides a method for forming an inner boss and a variable thickness region of a housing, applied to the aforementioned pre-stressing fixture for the structural boss and variable thickness region, comprising:

[0012] The machined surfaces of the bosses are laid up alternately, and the layout direction of each layer is staggered. The small end machined surfaces are pre-pressed by pre-pressing components.

[0013] The variable thickness zone and the boss layer are laid up, with the boss layer being laid up alternately with decreasing thickness, and the variable thickness zone layer being laid up alternately. The layout direction of each layer in the variable thickness zone is staggered. After the variable thickness zone and the boss layer are laid up to half of the preset size, they are pre-pressed in the oven. After exiting the oven, the variable thickness zone and the boss layer are pre-pressed a second time by the pre-pressing component. After the second pre-pressing, the layer is laid up to the preset size and pre-pressed in the oven. After exiting the oven, it is pre-pressed a third time by the pre-pressing component.

[0014] Curing and molding: The structural components, after three pre-pressing processes, are vacuum hot-pressed and molded.

[0015] In one feasible implementation, the layers are staggered in the order of 0 degrees, 90 degrees, +45 degrees, and -45 degrees, and are pre-compressed once every 4 layers by the pre-compressing member.

[0016] In one feasible implementation, the alternating decreasing ply sequence of the bosses is 0 degrees, 90 degrees; the staggered ply sequence of the variable thickness zones is 0 degrees, 90 degrees, +45 degrees, -45 degrees.

[0017] In one feasible implementation, in the curing and molding step, the vacuum pressure of the vacuum hot pressing is less than or equal to -0.09 MPa, the hot pressing pressure is 0.3 MPa, the curing temperature is 200°C, and the post-treatment temperature is 240°C.

[0018] The above description is merely an overview of the technical solution provided in this disclosure. In order to better understand the technical means of this disclosure and to implement it in accordance with the contents of the specification, and to make the above and other features and effects of this disclosure more obvious and understandable, the following are specific examples of implementation methods of this disclosure. Attached Figure Description

[0019] The accompanying drawings, which are incorporated in and form a part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0020] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0021] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of exemplary embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0022] Figure 1 This is one of the structural schematic diagrams of the preloading section and tooling body disclosed in this invention;

[0023] Figure 2 This is the second structural schematic diagram of the preloading section and tooling body disclosed in this publication;

[0024] Figure 3 This is the third schematic diagram of the preloading section and tooling body disclosed in this publication;

[0025] Figure 4 This is a schematic diagram of the structure of the boss in this disclosure;

[0026] Figure 5 This is a front view structural diagram of the variable thickness region of this disclosure;

[0027] Figure 6 This is one of the structural schematic diagrams of the preloading section in the variable thickness region of this disclosure;

[0028] Figure 7 This is the second schematic diagram of the preloading section in the variable thickness region of this disclosure.

[0029] in, Figures 1 to 7 The correspondence between the reference numerals and component names in the attached drawings is as follows:

[0030] 100 - Variable thickness zone; 200 - Boss;

[0031] 1-Tooling body; 2-Pre-compression part; 21-Installation part; 22-Pre-compression part; 221-First pre-compression part; 222-Second pre-compression part; 223-Positioning pre-compression part; 224-Adjusting rod; 225-Pressure head. Detailed Implementation

[0032] To better understand the above-mentioned objectives, features, and advantages of this disclosure, the solutions disclosed herein will be further described below. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other.

[0033] Numerous specific details are set forth in the following description in order to provide a full understanding of this disclosure, but this disclosure may also be implemented in other ways different from those described herein; obviously, the embodiments in the specification are only some, and not all, of the embodiments of this disclosure.

[0034] Currently, to accommodate the assembly requirements of both large and small ends, a certain product model features variable thickness areas and irregularly shaped internal bosses. The molding process employs a lay-up-autoclave process. The small end of the product has multiple bosses, while the large end frame has multiple variable thickness areas. The bosses and variable thickness areas are quite thick, while the boss dimensions are relatively small. This makes controlling the lay-up process along with the product itself challenging, as it's impossible to precisely control the final dimensions after lay-up. Therefore, ensuring the dimensional requirements of the bosses and variable thickness areas is a problem that urgently needs to be solved.

[0035] Based on this, embodiments of this disclosure provide a tooling body and a plurality of pre-compression parts, wherein the plurality of pre-compression parts are arranged at circumferential intervals along the tooling body, wherein each pre-compression part includes a mounting component and a pre-compression component, the mounting component being connected to the tooling body, and the pre-compression component being slidably connected to the mounting component. By implementing the technical solution of this disclosure, the accuracy of the external dimensions is ensured, the connection strength requirements between the boss and the variable thickness area are improved, and the problem that machining is difficult to guarantee the external dimensions and internal quality of carbon fiber irregular structures is solved.

[0036] The following detailed embodiments illustrate the pre-compression fixture and forming method for the boss and variable thickness area of ​​this structural component:

[0037] Reference Figures 1 to 7 As shown, in the first aspect of this disclosure, a pre-compression fixture for a structural boss and a variable thickness region is provided, including a fixture body 1 and a plurality of pre-compression parts 2. The plurality of pre-compression parts 2 are arranged at intervals along the circumference of the fixture body 1. The pre-compression part 2 includes a mounting part 21 and a pre-compression part 22. The mounting part 21 is connected to the fixture body 1, and the pre-compression part 22 is slidably connected to the mounting part 21.

[0038] The tooling body 1 disclosed herein serves as the mounting and connecting part that mates with the convex mold of the structural component. It is equipped with multiple pre-compression parts 2, which are spaced apart circumferentially on the tooling body 1. Their positions and spacing are adjusted to adapt to the boss configuration and shape of the structural component to be processed. Each pre-compression part 2 includes a mounting part 21 and a pre-compression part 22. The mounting part 21 is connected to the tooling body 1, and the pre-compression part 22 is slidably connected to the mounting part 21. The pre-compression part 22 pre-compresses the boss and the variable thickness area during each stage of layup, thus better ensuring dimensional accuracy and improving the bonding strength between the large and small ends. This process solves the problem that machining cannot guarantee the dimensional accuracy and internal quality of carbon fiber irregular structures. Specifically, the pre-compression part 22 can be configured as a pressure block, pressure plate, etc., and its structural form and quantity are selected according to the shape of the structural component. The compressive strength can be achieved through manual compaction or by setting a drive element for CNC automatic compaction. For example, the boss pre-compression components are set in three groups. The first group has 12 pieces for positioning the boss shape, the second group has 12 pieces for pre-compression during the layup process, and the third group has eight pieces for pre-compression of smaller bosses after the layup is completed. The variable thickness zone pre-compression components are set in two groups, with four pieces in each group, for pre-compression during the layup process and after the layup is completed. Furthermore, the tooling body 1 can be a separate main body with boss-specific pre-compression components and variable thickness zone-specific pre-compression components on opposite sides. Alternatively, the end pressure heads of the pre-compression components can be changed to adjust whether they pre-compress bosses or variable thickness zones. Or, the tooling body 1 can be set as a variable thickness zone tooling body and a boss tooling body, with boss pre-compression components and variable thickness zone pre-compression components respectively. The variable thickness zone tooling body and the boss tooling body are connected by connectors.

[0039] In some embodiments, a driving member is also included, which is connected to the pre-compression member 22 and is used to apply a force by which the pre-compression member 22 compacts the structural member to be formed.

[0040] In this embodiment, the driving component applies a compacting force from the pre-compressing component 22 onto the structural part to be formed, replacing manual compaction to improve operational efficiency and avoid contact between manual compaction and the structural part itself. Specifically, the driving component can be a drive motor, a telescopic cylinder, a telescopic hydraulic cylinder, etc. This disclosure specifically uses a drive motor to ensure precise compaction force.

[0041] In some embodiments, the tooling body 1 is configured as an annular ring, and the compaction direction of the pre-compression member 22 is directed toward the center of the tooling body 1. In this embodiment, the tooling body 1 is configured as an annular ring to better accommodate the annular shape of the tooling body 1 and the compaction direction of the pre-compression member 22 is directed toward the center of the tooling body 1.

[0042] In some embodiments, the pre-compression member 22 includes an adjusting member, a first pre-compression member 221, a second pre-compression member 222, and a positioning pre-compression member 223. The adjusting member is connected to the mounting member 21. The first pre-compression member 221, the second pre-compression member 222, and the positioning pre-compression member 223 are connected to the adjusting member. The adjusting member is used to adjust the pressure surface of one of the first pre-compression member 221, the second pre-compression member 222, and the positioning pre-compression member 223 toward the structural member to be formed.

[0043] In this embodiment, the first pre-pressing component 221, the second pre-pressing component 222, and the positioning pre-pressing component 223 are connected to an adjusting component. The adjusting component is used to adjust the pressing surface of one of the first pre-pressing component 221, the second pre-pressing component 222, and the positioning pre-pressing component 223 to face the structural part to be formed, so that the first pre-pressing component 221, the second pre-pressing component 222, and the positioning pre-pressing component 223 do not need to be manually replaced. The shape of the three sets of pre-pressing components is adapted to the process flow. Specifically, the adjusting component can be a turntable, electric bearing, etc., to evenly distribute the first pre-pressing component 221, the second pre-pressing component 222, and the positioning pre-pressing component 223 along the circumference of the adjusting component, and the pressing surface is aligned by rotating the adjusting component. It is understood that a certain amount of rotation space is required when adjusting the first pre-pressing component 221, the second pre-pressing component 222, and the positioning pre-pressing component 223.

[0044] In some embodiments, a positioning element is also included, wherein the pre-compression part 2 is slidably connected to the tooling body 1, and the positioning element is used to fix the relative position of the pre-compression part 2 on the tooling body 1.

[0045] In this embodiment, the entire pre-compression section 2 is slidably connected to the fixture body 1. For example, the mounting part 21 is slidably connected to the fixture body 1, so that the position of the pre-compression section 2 can be adjusted to adapt to pre-compression bosses and thickened areas of various shapes and types of structural parts. The fastener can be selected to be fixed by snap-fitting to the fixture body 1, or it can be fixed by bolts.

[0046] In some embodiments, the pre-compression member 22 includes an adjusting rod 224 and a pressure head 225. The adjusting rod 224 is movably connected to the mounting member 21, and the pressure head 225 is detachably connected to the adjusting rod 224. In this embodiment, the pressure head 225 is detachably connected to the adjusting rod 224 to facilitate replacement of the pressure head.

[0047] A second aspect of this disclosure provides a method for forming an inner boss and a variable thickness region of a housing, applied to the aforementioned pre-stressing fixture for the structural boss and variable thickness region, comprising:

[0048] The boss machining surface is laid up in alternating layers, and the layout direction of each layer is staggered. The small end machining surface is pre-pressed by the pre-pressing component 22.

[0049] The variable thickness zone and boss layers are laid up, with the boss layers decreasing alternately and the variable thickness zone layers alternating. The layout direction of each layer in the variable thickness zone is staggered. After the variable thickness zone and boss layers are laid up to half of the preset size, they are pre-pressed in the oven. After exiting the oven, the variable thickness zone and boss layers are pre-pressed a second time through a pre-pressing device. After the second pre-pressing, the layers are laid up to the preset size and pre-pressed in the oven. After exiting the oven, they are pre-pressed a third time through a pre-pressing device.

[0050] Curing and molding: The structural components, after three pre-pressing processes, are vacuum hot-pressed and molded.

[0051] In some embodiments, the ply layup is arranged in an alternating sequence of 0 degrees, 90 degrees, +45 degrees, and -45 degrees, with each four layers pre-compressed once by the pre-compressor 22.

[0052] In some embodiments, the alternating decreasing ply sequence of the bosses is 0 degrees, 90 degrees; the staggered ply sequence of the variable thickness regions is 0 degrees, 90 degrees, +45 degrees, -45 degrees.

[0053] In some embodiments, during the curing and molding step, the vacuum pressure of the vacuum hot pressing is less than or equal to -0.09 MPa, the hot pressing pressure is 0.3 MPa, the curing temperature is 200°C, and the post-treatment temperature is 240°C.

[0054] The present invention discloses a method for forming the internal boss and variable thickness region of the housing. Based on the product's structural characteristics and stress characteristics, a forming mold is used in conjunction with the pre-pressing fixture for the structural boss and variable thickness region provided in the first aspect of the present invention. The main body of the mold consists of a punch positioning cylinder, a steel segmented punch, and a die. The punch positioning cylinder serves as internal support and ply-lay rotation clamping, preventing structural instability and deformation of the mold due to external pressure during the forming process. The segmented punch is the ply-lay layer and is installed on the punch positioning cylinder. The die serves to ensure the external dimensions and pre-press the mold closing.

[0055] Specifically, due to the large thickness of the bosses and the variable thickness area, and the small size of the bosses, the process of laying them together with the product is difficult to control, and the overall dimensions after laying cannot be precisely controlled. Therefore, the above-mentioned areas are laid in the punch, and after the reinforcing ribs and end frames in the shell are laid, they are then completely covered in the skin. To ensure the overall continuity of the fibers, this disclosure can use a unidirectional fabric lay-up method for molding, which also serves to support the connection between the compartments. During the molding process, due to the large thickness of the bosses, multiple pre-pressing in the oven is required to ensure the density of the intermediate layer. First, the punch and die are closed and pre-pressed in the oven. Then, the boss and variable thickness area pre-pressing fixture is assembled with the mold after exiting the oven and pre-pressed. To ensure the pressure transmission effect during the pre-pressing process, the pre-pressing component 22 needs to be mechanically pressurized immediately after exiting the oven to ensure that the pressure is transmitted in place.

[0056] The carbon fiber skin is obtained through die layup and curing. After assembling the molds for the rear cover plate, large end filler ring, front cover plate, and small end filler ring, the product is cured by vacuum-assisted autoclaving. During curing, after the carbon fiber composite shell is laid up, to ensure that the product's dimensions meet design requirements, a carbon fiber skin with good rigidity is required. Simultaneously, to ensure the vacuum pressure is transmitted to the product, a semi-vacuum operation is performed after assembly, with the vacuum pressure below -0.092 MPa. This pressure range effectively removes air and volatiles between the prepreg layers, allowing the prepreg to adhere tightly.

[0057] After the product has cured, the vacuum-coated material on the mold surface is removed. Finally, the outer dimensional process skin, the large and small end molds, and the internal punch blocks are removed to obtain a carbon fiber composite material compartment with variable thickness zones and irregularly shaped bosses. Allowances are left on the shell end frame face, inner circle, bosses, etc., to ensure this through machining. Process control pins and process connection holes are drilled, and openings are made in the skin. Subsequent ultrasonic and 3D scanning inspections are then performed.

[0058] For a specific example, a structural section contains four variable thickness zones and twelve bosses at the large and small end frames. The skin thickness is 1 mm. Four annular ribs are distributed on the internal shell surface: one at each of the large and small end frames, each rib 20 mm wide and 2 mm thick. Two ribs are located in the middle of the shell, each 20 mm wide, with a gradually decreasing thickness near quadrants I and III: 2 mm → 1.17 mm → 1.5 mm. Six longitudinal ribs are distributed on the internal shell surface: one each in quadrants I and III, extending to the lower end frame on the lower end face and ending at the opening on the upper end face; both are 30 mm wide and 1.16 mm thick. Two ribs each in quadrants II and IV are 20 mm wide and 2 mm high, extending to the end faces at both the top and bottom. The bosses are 12 mm and 13.8 mm thick, respectively, with the variable thickness zone transitioning from 5.33 mm to 0 mm. The materials selected are T700 carbon fiber and bismaleimide resin system, with a prepreg thickness of 0.1 mm, 3K carbon cloth thickness of 0.2 mm, and a curing temperature of 200℃.

[0059] The prepreg has a 2mm thick layer on the boss surface, with a layup sequence of [0 / 90 / +45 / -45]5, where the unit is degrees (°), representing the direction of the carbon fibers in the prepreg. The number 5 indicates that the layup sequence is repeated 5 times. Simulation analysis shows that this layup sequence ensures the mechanical strength of the structure under load and reduces deformation after curing. Pre-compression is performed every 4 layers. After pre-compression, the boss surface is pre-compressed using pre-compression component 22, followed by a 3K sheet of carbon fiber as a base layer, and then pre-compression is performed again. The 2mm layup of the circumferential ribs, longitudinal ribs, and end frames requires folding towards the variable thickness area and bosses, with a layup sequence of [0 / 90 / +45 / -45]5. Pre-compression is performed every 4 layers. Vacuum pre-compression removes air, ensuring initial adhesion of each prepreg layer, which is beneficial for subsequent curing and avoids defects such as delamination. It also makes the fiber distribution in the prepreg more uniform, reduces porosity, and improves the mechanical properties of the material, such as interlaminar shear strength.

[0060] The variable thickness zone and the boss are laid up, with the boss being laid up alternately at 0° / 90° and the variable thickness zone being laid up alternately at [0 / 90 / +45 / -45]. After the layer is half the thickness, it is put into the oven for pre-pressing. After it comes out of the oven, the pre-pressing component 22 is used to pre-press the variable thickness zone and the boss respectively. After the layer is completely laid up, the pre-pressing component 22 is used again for compaction.

[0061] After pre-pressing, repair any missing material in the bosses and areas with varying thickness.

[0062] After the pre-pressing repair of the bosses and variable thickness areas is completed, the skin is laid in 1.5 mm layers in the following sequence: [90 / 0 / 90 / 45 / -45 / 90 / 0 / 90 / 0 / 90 / -45 / 45 / 90 / 0 / 90]. Four layers are pre-pressed at a time, and the last four layers are pre-pressed in an oven. Subsequently, the large and small end frames are laid, completely enclosing the bosses and variable thickness areas within the layup structure. After all layups are completed, the die and punch are closed, and a vacuum is applied before the material is placed in an autoclave for pre-pressing. Final curing uses carbon fiber skin instead of a die for shape curing. The vacuum pressure is no greater than -0.09 MPa, the autoclave pressure is 0.3 MPa, the curing temperature is 200℃, and the post-treatment temperature is 240℃. According to the composite material autoclave molding process standard, the autoclave pressure is guaranteed to be below 1 MPa. The specific curing temperature and pressure are determined by the physical properties of the resin and carbon fiber filaments in the prepreg. Excessive temperature will cause the resin to cure too quickly, generating significant internal stress and leading to defects such as cracks and deformation in the product. Furthermore, high temperatures may damage the carbon fiber. Insufficient temperature will result in incomplete resin curing, causing the product to become soft and lack strength. Insufficient pressure will lead to poor interlayer bonding, increased porosity, and deterioration of the product's mechanical properties. Excessive pressure will cause excessive resin loss, affecting the product's strength and stiffness, and may also damage the mold. After curing, demolding is performed to remove the covering material sequentially, and the mold is disassembled to obtain a one-piece molded carbon fiber composite material section with irregularly shaped bosses and variable thickness zones. The external dimensions and shell openings are then machined.

[0063] In this disclosure, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance; the term "multiple" refers to two or more unless otherwise expressly defined. The terms "install," "connect," "link," and "fix" should be interpreted broadly. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "link" can be a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this disclosure according to the specific circumstances.

[0064] In the description of this disclosure, it should be understood that the terms "upper," "lower," "left," "right," "front," "rear," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this disclosure and simplifying the description, and do not indicate or imply that the device or unit referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this disclosure.

[0065] In the description of this specification, the terms "one embodiment," "some embodiments," "specific embodiment," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of this disclosure. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0066] The above are merely preferred embodiments of this disclosure and are not intended to limit this disclosure. Various modifications and variations can be made to this disclosure by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A pre-stressing fixture for a structural component boss and a variable thickness zone, characterized in that, The tooling includes a tooling body and multiple pre-compression sections, wherein the multiple pre-compression sections are arranged at circumferential intervals along the tooling body. The pre-compression part includes an installation component and a pre-compression component. The installation component is connected to the tooling body, and the pre-compression component is slidably connected to the installation component. The pre-compression component includes a boss pre-compression component and a variable thickness region pre-compression component; The boss pre-compression component includes a first set of pre-compression components, a second set of pre-compression components, and a third set of pre-compression components. The first set of pre-compression components is used to pre-compress the boss shape and position it. The second set of pre-compression components is used to pre-compress the boss during the layup process. The third set of pre-compression components is used to pre-compress smaller bosses at various locations after the layup is completed. The variable thickness region preloading component includes a fourth group of preloading components and a fifth group of preloading components. The fourth group of preloading components is used to preload the variable thickness region during the layup process, and the fifth group of preloading components is used to preload the variable thickness region after the layup is completed.

2. The pre-stressing fixture for the structural boss and variable thickness zone according to claim 1, characterized in that, It also includes a driving component, which is connected to the pre-compression component and is used to apply a force from the pre-compression component to the structural component to be formed.

3. The pre-stressing fixture for the structural boss and variable thickness zone according to claim 1, characterized in that, The tooling body is configured as a ring, and the compaction direction of the pre-compression component is toward the center of the tooling body.

4. The pre-stressing fixture for the structural boss and variable thickness zone according to claim 1, characterized in that, The pre-compression component includes an adjusting component, a first pre-compression component, a second pre-compression component, and a positioning pre-compression component. The adjusting component is connected to the mounting component. The first pre-compression component, the second pre-compression component, and the positioning pre-compression component are connected to the adjusting component. The adjusting component is used to adjust the pressure surface of one of the first pre-compression component, the second pre-compression component, and the positioning pre-compression component to face the structural component to be formed.

5. The pre-stressing fixture for the structural boss and variable thickness zone according to claim 1, characterized in that, It also includes a positioning element, wherein the pre-compression part is slidably connected to the tooling body, and the positioning element is used to fix the relative position of the pre-compression part on the tooling body.

6. The pre-stressing fixture for the structural boss and variable thickness zone according to claim 1, characterized in that, The pre-compression component includes an adjusting rod and a pressure head. The adjusting rod is movably connected to the mounting component, and the pressure head is detachably connected to the adjusting rod.

7. A method for forming an inner boss and a variable thickness region of a housing, applied to a pre-pressing fixture for the structural boss and variable thickness region as described in any one of claims 1 to 6, characterized in that, include: The machined surfaces of the bosses are laid up alternately, and the layout direction of each layer is staggered. The small end machined surfaces are pre-pressed by pre-pressing components. The variable thickness zone and the boss layer are laid up, with the boss layer being laid up alternately with decreasing thickness, and the variable thickness zone layer being laid up alternately. The layout direction of each layer in the variable thickness zone is staggered. After the variable thickness zone and the boss layer are laid up to half of the preset size, they are pre-pressed in the oven. After exiting the oven, the variable thickness zone and the boss layer are pre-pressed a second time by the pre-pressing component. After the second pre-pressing, the layer is laid up to the preset size and pre-pressed in the oven. After exiting the oven, it is pre-pressed a third time by the pre-pressing component. Curing and molding: The structural components, after three pre-pressing processes, are vacuum hot-pressed and molded.

8. The method for forming the inner boss and variable thickness region of the shell according to claim 7, characterized in that, The layers are staggered in the order of 0 degrees, 90 degrees, +45 degrees, and -45 degrees, and are pre-compressed once every 4 layers by the pre-compressing component.

9. The method for forming the inner boss and variable thickness region of the housing according to claim 7, characterized in that, The alternating decreasing ply sequence of the bosses is 0 degrees, 90 degrees; the staggered ply sequence of the variable thickness zone is 0 degrees, 90 degrees, +45 degrees, -45 degrees.

10. The method for forming the inner boss and variable thickness region of the housing according to claim 7, characterized in that, In the curing and molding step, the vacuum pressure of the vacuum hot pressing is less than or equal to -0.09 MPa, the hot pressing pressure is 0.3 MPa, the curing temperature is 200°C, and the post-treatment temperature is 240°C.

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