Integral forming method of U-shaped stiffened wall plate

Abstract

The invention provides an integral forming method of a U-shaped stiffened wallboard, which comprises the following steps: respectively laying a skin laying layer group and each stringer laying layer group, and pre-pressing and shaping to obtain a skin pre-formed body, a plurality of first stringer pre-formed bodies and a plurality of second stringer pre-formed bodies; the first stringer preformed body and the U-shaped rib forming die are positioned and mounted at a first position through the positioning device, and a first U-shaped rib wallboard assembly is obtained; packaging the first U-shaped rib wall plate assembly, and carrying out heating, pressurizing and hot compacting shaping in an autoclave to obtain a U-shaped rib wall plate prefabricated body; a second stringer pre-forming body is positioned and installed at a second position, an auxiliary mold is arranged in the second stringer pre-forming body, and a second U-shaped rib wall plate assembly is obtained; and auxiliary materials are laid on the second U-shaped rib wall plate assembly and packaged, the second U-shaped rib wall plate assembly enters an autoclave to be cured and formed, and the U-shaped stiffened wall plate is obtained. According to the U-shaped stiffened wallboard forming device, integral forming of the U-shaped stiffened wallboard can be achieved, the forming quality is good, and the positioning precision is high.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material manufacturing, and more specifically, to an integral forming method for a U-shaped stiffened panel. Background Art

[0002] Composite stiffened panels are typical structural forms of aerospace composites and have been widely used in aircraft structures such as fuselages and wing surfaces. By strengthening the thin-walled skin with stiffeners, the weight reduction efficiency of the structure is improved while meeting the requirements of structural strength and stiffness. According to different stiffener cross-sectional forms, conventional stiffened panels can be divided into various stiffened panel structures such as "L"-type, "J"-type, "T"-type, and "I"-type. The stiffeners and the skin are usually relatively independent. The forming methods mainly include: ① The ribs and the skin are cured separately and then adhesively bonded for the second time; ② One of the ribs or the skin is cured first, and adhesively bonded with the uncured rib or skin while curing, that is, co-bonding; ③ The skin and the ribs are laid up separately, and the laid-up skin and ribs are combined and co-cured.

[0003] A U-shaped stiffened panel refers to a stiffened panel with a "U"-shaped cross-section. The adjacent two "U"-shaped web surfaces form a stiffening vertical edge, and the bottom surface is integrated with the skin and becomes a part of the skin ply, as Figure 1 shown. There are also three forming schemes for the U-shaped stiffened panel: secondary bonding, co-bonding, and co-curing. Compared with the relatively independent conventional "L"-type, "J"-type, "T"-type, and "I"-type stiffened panels, since the bottom surface of the "U"-shaped stiffener has been a part of the skin ply, the wall panel structure of the "U"-shaped stiffener + skin has better integrity, higher structural efficiency, and more obvious weight reduction effect. However, the "U"-shaped stiffeners in this structural form restrict each other. If the forming method of secondary bonding or co-bonding the cured "U"-shaped stiffeners with the skin is adopted, the forming mold for a single "U"-shaped stiffener unit is relatively simple, the pressing is relatively easy, and the flatness is easy to ensure. Because each "U"-shaped stiffener unit is cured and shaped, and the thickness has also been pressed and compacted, when adhesively bonding and assembling with the skin, the "U"-shaped stiffeners can be assembled in place, and there is no problem of pressing each surface of the "U"-shaped stiffeners during adhesive bonding. At this time, it is relatively easy to realize the secondary bonding and co-bonding of the U-shaped stiffened panel.

[0004] With the increasing use of composite materials, higher requirements are put forward for the weight reduction efficiency and cost of composite material structures. Integral forming of stiffened panels can further reduce the number of equipment uses and shorten the manufacturing cycle. Achieving integral forming of composite material structures has become a trend in the development of composite materials. In a certain project, the fuselage, wing and other panels widely adopt the U-shaped stiffened panel structure, and it is required to integrally form multiple "U"-shaped ribs and skins to reduce the manufacturing cost of composite materials. However, for the "U"-shaped stiffened panel, when the "U"-shaped ribs are not cured, since each "U"-shaped rib unit has not been pressurized and compacted, its thickness is still greater than the theoretical thickness. When co-bonding with the cured skin or co-curing and assembling with the uncured skin, there will be cumulative deviations when the "U"-shaped ribs are combined together. The more ribs there are, the greater the cumulative error, resulting in the inability to assemble the "U"-shaped ribs with each other and between the "U"-shaped ribs and the mold in place. Even if a rib positioning device is designed, due to the misalignment of the assembly, the preform and the positioning device are not in the correct position and the positioning measures cannot be implemented. At the same time, during the curing process, the pressure problem on each surface of the "U"-shaped rib and the surface flatness problem also need to be considered. Therefore, the co-bonding and co-curing forming of the uncured "U"-shaped rib and the skin is difficult, which is prominently manifested in the difficulty of combining the "U"-shaped ribs, the problem that the positioning device cannot be normally assembled due to misalignment, the difficulty in ensuring the position accuracy of the "U"-shaped stringers, and the surface unevenness caused by the misalignment of each structural unit. The integral forming tooling design and forming process plan formulation of the U-shaped stiffened panel are the keys to the forming quality of the panel. Summary of the Invention

[0005] (1) Technical Problems to be Solved

[0006] The technical problem to be solved by the present invention is the difficulty in combining each structural unit of the integral forming of the U-shaped stiffened panel, the inability to assemble it in place with the positioning tooling, and the problem of fiber wrinkles caused by interference between each unit during assembly.

[0007] (2) Technical Solutions

[0008] To achieve the above object, the technical solution adopted by the present invention is:

[0009] Provide an integral forming method for a U-shaped stiffened panel, including the following steps:

[0010] S1. According to the structure of the U-shaped stiffened panel, decompose the structural units of the U-shaped stiffened panel according to the ply group boundary. The U-shaped stiffened panel includes a skin ply group and a plurality of stringer ply groups arranged side by side on the skin ply group;

[0011] S2. Lay the skin ply group and each stringer ply group respectively, and pre-press and shape them to obtain a skin preform, a plurality of first stringer preforms and a plurality of second stringer preforms. Among them, the first stringer preform is used to be positioned and installed at the first position of the skin preform, the second stringer preform is used to be positioned and installed at the second position of the skin preform, and the first position and the second position are arranged alternately.

[0012] S3. The positioning device positions and installs the first stringer preform and the U-shaped rib forming die at the first position to obtain a first U-shaped rib panel assembly.

[0013] S4. Package the first U-shaped rib panel assembly, and heat and pressurize it in an autoclave. After hot compaction and shaping, obtain a U-shaped rib panel preform.

[0014] S5. Position and install the second stringer preform at the second position, and set an auxiliary mold in the second stringer preform to obtain a second U-shaped rib panel assembly.

[0015] S6. Lay auxiliary materials on the second U-shaped rib panel assembly and package it, then cure and shape it in an autoclave to obtain a U-shaped stiffened panel.

[0016] Preferably, the first stringer preform includes a U-shaped component and / or an L-shaped component, a flat plate component and an R-corner filling component, and the second stringer preform is a U-shaped component and / or an L-shaped component.

[0017] Preferably, the forming process of the first stringer preform includes the following steps:

[0018] When the first stringer preform is a U-shaped component, the U-shaped component is laid on a U-shaped forming die. When the thickness does not exceed 1 mm, after laying, vacuum pre-compaction or hot compaction is carried out at room temperature. When the thickness exceeds 1 mm, hot compaction is carried out after laying;

[0019] When the first stringer preform is an L-shaped component, the L-shaped component is laid on a laying die. When the thickness does not exceed 1 mm, after laying, vacuum pre-compaction or hot compaction is carried out at room temperature. When the thickness exceeds 1 mm, hot compaction is carried out after laying;

[0020] The flat plate component is laid on a platform. When the thickness does not exceed 1 mm, after laying, vacuum pre-compaction or hot compaction is carried out at room temperature. When the thickness exceeds 1 mm, hot compaction is carried out after laying;

[0021] The R - corner filling component calculates the theoretical width of the unidirectional prepreg tape according to the cross - sectional area of the R - corner filling component and the thickness of a single layer of prepreg. Multiply the calculated theoretical width of the unidirectional prepreg tape by a coefficient of 1.05 - 1.15 to obtain the width of the unidirectional prepreg tape. Cut the unidirectional prepreg tape into the width of the unidirectional prepreg tape, and after laying it up, perform hot compaction and shaping through a pre - compaction mold.

[0022] Preferably, the forming process of the second longeron preform includes the following steps:

[0023] When the second longeron preform is a U - shaped component, the U - shaped component is laid up on a U - shaped forming mold. When the thickness does not exceed 1 mm, after laying up, perform vacuum pre - compaction or hot compaction at room temperature. When the thickness exceeds 1 mm, perform hot compaction after laying up;

[0024] When the second longeron preform is an L - shaped component, the L - shaped component is laid up on a laying - up mold. When the thickness does not exceed 1 mm, after laying up, perform vacuum pre - compaction or hot compaction at room temperature. When the thickness exceeds 1 mm, perform hot compaction after laying up.

[0025] Preferably, during the hot compaction and shaping process: the temperature does not exceed 70 °C, the pressure does not exceed 6 MPa, and the heat - preservation time is 5 - 30 min.

[0026] Preferably, the forming process of the skin preform includes the following steps:

[0027] Lay up the skin ply group on the panel outer - shape mold. When the thickness of the skin ply group does not exceed 3 mm, after laying up, it can be subjected to vacuum pre - compaction or hot compaction at room temperature. When the thickness of the skin component exceeds 3 mm, perform hot compaction after laying up.

[0028] Preferably, the positioning device includes a limit block, and step S3 includes the following steps:

[0029] Place the first longeron preform and the U - rib forming mold at the first position, place the U - rib forming mold on the first longeron preform, and connect the limit block to the U - rib forming mold in a limiting manner to obtain the first U - rib panel component.

[0030] Preferably, the U - rib forming mold is made of a rigid material, and the U - rib forming mold is provided with a limiting groove with a trapezoidal cross - section, and the limit block is clamped in the limiting groove.

[0031] Preferably, step S5 includes the following steps:

[0032] Place the second longeron preform at the second position, and set an auxiliary forming mold on the second longeron preform. The auxiliary forming mold is made of a non - rigid material.

[0033] Preferably, step S6 includes the following steps:

[0034] Lay a release material and a breather felt on the second U-shaped rib panel assembly to completely cover the second U-shaped rib panel assembly. Paste a sealing putty around the second U-shaped rib panel assembly and encapsulate it with a vacuum film.

[0035] Place the encapsulated second U-shaped rib panel assembly in an autoclave and cure it according to the preset process parameters.

[0036] (III) Beneficial effects

[0037] The above technical solutions of the present invention have at least the following advantages:

[0038] 1. In the present invention, a plurality of first stringer preforms and second stringer preforms are alternately arranged on the skin preform. The first stringer preforms are positioned and installed on the skin preform through a positioning device. During the combination, it is not affected by adjacent U-shaped components, which is not only convenient for assembly, but also ensures the accurate positioning of the first stringer preforms on the skin preform. After the first stringer preforms are accurately positioned and hot-compacted on the skin preform, the second stringer preforms are combined. The second stringer preforms are distributed between two adjacent first stringer preforms and are positioned by the adjacent positioned and shaped first stringer preforms, so the position is controllable, avoiding the problems of fiber slippage and surface wrinkles during the forming process caused by position deviation.

[0039] 2. In the present invention, the first stringer preform includes a U-shaped component, a flat plate component, and an R-corner filling component. Based on the premise that the U-shaped component is accurately positioned on the skin preform, the flat plate component and the R-corner filling component are combined. The positions of these components are controllable during the combination. After being combined into the first stringer preform, the first stringer preform is subjected to hot pressing and shaping, so that the preform realizes the accurate positioning of the U-shaped component, the flat plate component, and the R-corner filling component on the skin preform under the action of temperature and pressure, and makes the components reach a tight state. Description of the drawings

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required to be used in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0041] Figure 1 It is a flow chart of the overall forming method of the U-shaped stiffened panel provided by the embodiment of the present invention.

[0042] Figure 2 It is a structural diagram of the U-shaped stiffened panel provided by Embodiment 1 of the present invention.

[0043] Figure 3 It is a schematic diagram of the structural unit composition of the U-shaped stiffened panel provided in Embodiment 1 of the present invention.

[0044] Figure 4 It is a schematic diagram of the arrangement of the first stringer preform and the second stringer preform provided in Embodiment 1 of the present invention.

[0045] Figure 5 It is a schematic diagram of the structural composition of the first U-shaped rib panel assembly provided in Embodiment 1 of the present invention.

[0046] Figure 6 It is a schematic diagram of the U-shaped stiffened panel provided in Embodiment 2 of the present invention.

[0047] Figure 7 It is a schematic diagram of the structural unit composition of the U-shaped stiffened panel provided in Embodiment 2 of the present invention.

[0048] Figure 8 It is a schematic diagram of the arrangement of the first stringer preform and the second stringer preform provided in Embodiment 2 of the present invention.

[0049] Figure 9 It is a schematic diagram of the structural composition of the first U-shaped rib panel assembly provided in Embodiment 2 of the present invention.

[0050] Each reference numeral in the figure is as follows:

[0051] 1, skin preform; 2, U-shaped component; 3, R-corner filling component; 4, flat plate component; 5, L-shaped component; 6, panel outer shape die; 7, U-shaped rib forming die; 8, limit block; 2-1, the first group of U-shaped components; 2-2, the second group of U-shaped components. Detailed implementation manners

[0052] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0053] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected or indirectly connected to the other element.

[0054] It should be understood that the orientation or positional relationship indicated by terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and does not indicate that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0055] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating relative importance or indicating the quantity of technical features. In the description of the present invention, the meaning of "a plurality of" is two or more unless otherwise specifically defined. The following describes the specific implementation of the present invention in more detail with reference to specific embodiments:

[0056] As Figures 1 to 5 shown, an overall forming method for a U-shaped stiffened panel according to an embodiment of the present invention includes the following steps:

[0057] S1. According to the structure of the U-shaped stiffened panel, decompose the U-shaped stiffened panel into structural units according to the ply group boundary. The U-shaped stiffened panel includes a skin ply group and a plurality of stringer ply groups arranged side by side on the skin ply group;

[0058] S2. Lay the skin ply group and each stringer ply group respectively, and pre-press and shape them to obtain a skin preform, a plurality of first stringer preforms, and a plurality of second stringer preforms. Among them, the first stringer preform is used to be positioned and installed at a first position of the skin preform, and the second stringer preform is used to be positioned and installed at a second position of the skin preform 1. The first position and the second position are arranged alternately;

[0059] S3. The positioning device positions and installs the first stringer preform and the U-shaped rib forming die 7 at the first position to obtain a first U-shaped rib panel assembly;

[0060] S4. Package the first U-shaped rib panel assembly, and heat and pressurize it in a autoclave. After hot compaction and shaping, a U-shaped rib panel preform is obtained;

[0061] S5. Position and install the second stringer preform at the second position, and set an auxiliary mold in the second stringer preform to obtain a second U-shaped rib panel assembly;

[0062] S6. Lay auxiliary materials on the second U-shaped rib panel assembly and package it, and cure and shape it in a autoclave to obtain a U-shaped stiffened panel.

[0063] In one embodiment, the first stringer preform includes a U-shaped component and / or an L-shaped component, a flat plate component, and an R-corner filling component, and the second stringer preform is a U-shaped component and / or an L-shaped component.

[0064] In one embodiment, the forming process of the first stringer preform includes the following steps:

[0065] When the first stringer preform is the U-shaped component 2, the U-shaped component 2 is laid on a U-shaped forming die (which can preferably directly use the U-shaped rib forming die 7 for laying). When the thickness does not exceed 1 mm, after laying, it is pre-compacted by vacuum at room temperature or hot-compacted. When the thickness exceeds 1 mm, it is hot-compacted after laying;

[0066] When the first stringer preform is the L-shaped component 5, the L-shaped component 5 is laid on a laying die. When the thickness does not exceed 1 mm, after laying, it is pre-compacted by vacuum at room temperature or hot-compacted. When the thickness exceeds 1 mm, it is hot-compacted after laying;

[0067] The flat plate component 4 is laid on a platform. When the thickness does not exceed 1 mm, after laying, it is pre-compacted by vacuum at room temperature or hot-compacted. When the thickness exceeds 1 mm, it is hot-compacted after laying;

[0068] The R-angle filling component 3 calculates the theoretical width of the prepreg unidirectional tape according to the cross-sectional area of the R-angle filling component 3 and the thickness of a single layer of prepreg. Multiply the theoretical width of the prepreg unidirectional tape by a coefficient of 1.05 - 1.15 to obtain the width of the prepreg unidirectional tape. Cut the prepreg unidirectional tape into the width of the prepreg unidirectional tape, and after laying, it is hot-compacted and shaped through a pre-compaction die.

[0069] In one embodiment, the forming process of the second stringer preform includes the following steps:

[0070] When the second stringer preform is the U-shaped component 2, the U-shaped component 2 is laid on a U-shaped forming die (which can preferably directly use the U-shaped rib forming die 7 for laying). When the thickness does not exceed 1 mm, after laying, it is pre-compacted by vacuum at room temperature or hot-compacted. When the thickness exceeds 1 mm, it is hot-compacted after laying;

[0071] When the second stringer preform is the L-shaped component 5, the L-shaped component 5 is laid on a laying die. When the thickness does not exceed 1 mm, after laying, it is pre-compacted by vacuum at room temperature or hot-compacted. When the thickness exceeds 1 mm, it is hot-compacted after laying.

[0072] In one embodiment, during the hot-compaction and shaping process: the temperature does not exceed 70 °C, the pressure does not exceed 6 MPa, and the heat preservation time is 5 - 30 min.

[0073] In one embodiment, the forming process of the skin preform includes the following steps:

[0074] Lay up the skin ply group on the outer skin mold. When the thickness of the skin ply group does not exceed 3 mm, it can be pre-compacted by vacuum at room temperature or thermally compacted after laying up. When the thickness of the skin assembly exceeds 3 mm, it is thermally compacted after laying up.

[0075] In one embodiment, the positioning device includes a limiting block, and step S3 includes the following steps:

[0076] Place the first stringer preform and the U-shaped rib forming mold at the first position, and limit and connect the limiting block to the U-shaped rib forming mold to obtain the first U-shaped rib panel assembly. It should be noted that the U-shaped rib forming mold is preferably used as the laying-up mold for the U-shaped component. After the prepreg is laid up on the U-shaped rib forming mold, the U-shaped component is obtained, and then the U-shaped component and the U-shaped rib forming mold are placed at the first position together, reducing the component assembly error caused by re-assembly after mold removal, further improving the assembly accuracy of each component, and improving the forming quality of the U-shaped stiffened panel.

[0077] In one embodiment, the U-shaped rib forming mold is made of a rigid material, and the U-shaped rib forming mold is provided with a limiting groove having a trapezoidal cross-section, and the limiting block is clamped in the limiting groove. Specifically, the rigid material includes but is not limited to steel, aluminum, etc. Specifically, the limiting groove is connected to the outer skin mold 6 through a positioning cross beam, and the limiting groove is designed on one side of the positioning cross beam and is encapsulated in the vacuum bag together during the curing process. During the forming process, it can move together with the U-shaped rib forming mold under the action of vacuum and external pressure. The movement in the normal direction of the skin can make the U-shaped rib forming mold reach the theoretical position, ensuring the positioning and limiting effect of the limiting block on the U-shaped rib forming mold, and the movement in the longitudinal direction can eliminate the deviation caused by the inconsistent thermal expansion between the molds during the heating and cooling process, thereby improving the forming quality of the U-shaped stiffened panel.

[0078] In one embodiment, step S5 includes the following steps:

[0079] Place the second stringer preform at the second position, and set an auxiliary forming mold on the second stringer preform. The auxiliary forming mold is made of a non-rigid material. Specifically, the non-rigid material includes but is not limited to materials such as rubber, fiber cloth + rubber, and fiberglass. When the flatness requirement of the inner surface of the part is relatively low, the auxiliary forming mold can directly use release cloth, PTFE cloth and other isolation materials, or isolation materials + polyester film. By arranging multiple U-shaped rib forming molds and multiple auxiliary forming molds in an alternating and staggered manner, and using limiting blocks to restrict the U-shaped rib forming molds, while ensuring the flatness of the stringer profile, the problem of uniform pressure in each area of the large-size U-shaped stiffened panel is solved.

[0080] In one embodiment, step S6 includes the following steps:

[0081] Lay the release material and breather felt on the second U-shaped rib panel assembly, covering the second U-shaped rib panel assembly completely. Paste the sealing putty around the second U-shaped rib panel assembly and encapsulate the vacuum film.

[0082] Place the encapsulated second U-shaped rib panel assembly in an autoclave and cure it according to the preset process parameters.

[0083] The following specific embodiments further illustrate the present invention in detail:

[0084] Embodiment 1

[0085] Figure 2 The shown U-shaped stiffened panel test piece 100 has a size of 3200mm * 720mm and is provided with 5 continuous "U" - shaped ribs. On both sides are 2 half "U" - shaped ribs, namely "L" - shaped ribs. The bottom surfaces of all rib strips are part of the skin and are integrated with the skin layup. It is laminated with prepreg having a single - layer thickness of 0.125mm and is integrally formed by the autoclave process. This test piece adopts the process scheme provided by the present invention, and the specific operation method is as follows:

[0086] This U-shaped stiffened panel test piece is divided into 1 skin preform 1, 5 U-shaped components 2 located in the middle of the panel, 2 L-shaped components 5 located on both sides of the panel, 12 R - corner filling components 3 ("◢" - shaped filling core materials) located between the U-shaped components 2 and the L-shaped components 5, and 6 flat components 4 ("‖" - shaped components) according to the interface of the skin and rib layup groups, as Figure 3 shown. Among them, the skin preform 1 has 22 layers and a thickness of 2.75mm. The U-shaped components 2 and the L-shaped components 5 have 6 layers and a thickness of 0.75mm. The cross - sectional area of the R - corner filling component 3 is 9.08mm 2 .

[0087] Figure 2 The bottom surfaces of the skin and the U-shaped components 2 of the shown U-shaped stiffened panel are flat. The first stringer preform includes multiple Group Ⅰ U-shaped components 2-1. The first Group Ⅰ U-shaped components 2-1 select the 1st, 3rd, and 5th ones from the left side of the panel. The second stringer preform includes multiple Group Ⅱ U-shaped components 2-2, and the second Group Ⅱ U-shaped components 2-2 select the adjacent 2nd and 4th ones. As Figure 4 shown, the Group Ⅰ U-shaped components and the Group Ⅱ U-shaped components are arranged alternately.

[0088] Specifically, when the bottom surfaces of all U-shaped components 2 are relatively simple, such as all being flat or single - curvature surfaces, the first Group Ⅰ U-shaped components 2-1 can select the 1st, 3rd,... and so on from one side of the panel, and the second Group Ⅱ U-shaped components 2-2 select the adjacent 2nd, 4th,... and so on.

[0089] When some of the bottom surfaces in the U-shaped component 2 are relatively complex, such as large-curvature surfaces or composite surfaces, first select the more complex U-shaped component as the second group of U-shaped components 2-2, and the adjacent U-shaped components as the first group of U-shaped components 2-1, and so on.

[0090] The first group of U-shaped components 2-1 is positioned and installed using a U-shaped rib forming die. The U-shaped rib forming die uses a rigid material die and is positioned by a limit block 8. The second group of U-shaped components 2-2 is positioned and installed using an auxiliary forming die. The auxiliary forming die preferably uses a non-rigid material die.

[0091] The number of plies of the skin preform 1 is 22, with a thickness of 2.75 mm. The number of plies of the 5 U-shaped components 2 and 2 L-shaped components 5 is 6, with a thickness of 0.75 mm. The number of plies of the flat plate component 4 is 8, with a thickness of 1 mm. The area of the R-corner filling component 3 is 9.08 mm 2 .

[0092] Lay up the skin preform 1, U-shaped component 2, R-corner filling component 3, flat plate component 4, and L-shaped component 5 respectively according to the laying sequence of the corresponding laying units.

[0093] The skin preform 1 is laid up on the panel outer shape die 6. The number of plies is 22, with a thickness of 2.75 mm. After laying up, it is pre-compacted by vacuum pumping at room temperature.

[0094] The U-shaped component 2 has 6 plies with a thickness of 0.75 mm. It is laid up on the U-shaped rib forming die 7 in the form of a male die according to the laying sequence of the corresponding U-shaped component 2. After laying up, it is pre-compacted by vacuum pumping at room temperature.

[0095] The flat plate component 4 is laid up on the platform. The number of plies is 8, with a thickness of 1 mm. After laying up, it is pre-compacted by vacuum pumping at room temperature.

[0096] Design and prepare a pre-compaction die for the R-corner filling component 3 with a cavity having the same cross-sectional dimensions and shape as the "◢" cross-section. Calculation of material usage: Calculate the required width of the prepreg unidirectional tape according to the cross-sectional area of the filling core material "◢". The cross-sectional area of the "◢" filling core material is 9.08 mm 2 , the thickness of a single layer of prepreg is 0.125 mm. Calculate the required theoretical width of the prepreg unidirectional tape to be 72.64 mm. Multiply the calculated theoretical width of the prepreg unidirectional tape by a coefficient of 1.15 to obtain the required width of the prepreg unidirectional tape of 84 mm. Cut the prepreg unidirectional tape into the required width, and the prepreg unidirectional tape is thermally compacted and shaped through the "◢" pre-compaction die.

[0097] The L-shaped component 5 has 6 plies with a thickness of 0.75 mm. It is laid up on the laying die in the form of a male die. After laying up, it can be pre-compacted by vacuum pumping at room temperature.

[0098] Select 3 U-shaped components 2-1 of Group I and their U-shaped rib forming dies 7, and place them at the first position of the skin preform 1 on the panel outer shape die 6. Install a positioning crossbeam on the panel outer shape die 6, and a limit block 8 is connected to the positioning crossbeam. Position the U-shaped components 2-1 of Group I and their U-shaped rib forming dies 7 one by one on the skin preform 1 through the limit block 8.

[0099] After that, sequentially combine all the R-corner filling components (the "◢" filling core material and the "◣" filling core material) and flat components 4 adjacent to the U-shaped components 2-1 of Group I to form the first U-shaped rib panel component, as Figure 4 shown.

[0100] Place Figure 4 All the U-shaped components 2-1 of Group I, all the flat components 4, R-corner filling components, L-shaped components 5 and the entire positioning device that have been positioned and assembled with the positioning device as shown are covered with auxiliary materials and encapsulated within a vacuum film, and then put into a hot press autoclave for heating, pressurizing and hot compaction. The hot compaction temperature is 65°C ± 5°C, the pressure is 5 MPa ± 0.5 MPa, and the heat preservation time is 20 min ± 5 min.

[0101] The U-shaped components of Group II are combined and positioned between the first stringer preforms of the first U-shaped rib panel component to form the second U-shaped rib panel component. Assemble the auxiliary forming die. Specifically, select 2 U-shaped components 2-2 of Group II and assemble them one by one at the second position between the 3 U-shaped components 2-1 of Group I of the first U-shaped rib panel component that has been compacted to obtain the second U-shaped rib panel component.

[0102] The U-shaped components 2 adjacent to the L-shaped components 5 on both sides of the panel are the U-shaped components 2-1 of Group I. After assembling the U-shaped components 2-2 of Group II, assemble 2 L-shaped components 5 on both sides of the panel respectively.

[0103] After that, assemble 2 auxiliary forming dies in the inner cavities of the U-shaped components 2-2 of Group II and the dies corresponding to the L-shaped components 5.

[0104] Enclose the second U-shaped rib panel component, the die and the positioning device on the panel outer shape die to form a vacuum system, and then put it into a hot press autoclave for curing and forming.

[0105] Lay polytetrafluoroethylene cloth and breathable felt to completely cover the assembled second U-shaped rib panel component, the U-shaped rib forming die 7, the auxiliary forming die, the limit block 8, the L-shaped components 5 on both sides of the panel and their corresponding dies. Paste sealing putty around the panel outer shape die 6 and encapsulate it with a vacuum film. In the hot press autoclave, cure and form according to the material process parameters.

[0106] Example 2

[0107] Figure 6The U-shaped stiffened panel 200 shown has a length of 3200 mm, a span of 806 mm, an unfolded width of 1008 mm, and is provided with 9 continuous U-shaped ribs. There are 2 L-shaped ribs on both sides. The bottom surfaces of the U-shaped ribs and the L-shaped ribs are part of the skin and are integrated with the skin ply. It is laminated with prepreg having a single-layer thickness of 0.125 mm and integrally formed by the autoclave process. This panel adopts the process solution provided by the present invention, and the specific operation method is as follows:

[0108] According to the interface of the skin and rib ply groups, this panel can be divided into as Figure 7 shown, 1 skin preform 1, 9 U-shaped components 2, 2 L-shaped components 5 located on both sides of the panel, and 20 R-corner filling components 3 located between the U-shaped components 2 and the L-shaped components 5. There is no flat component 4 ("‖"-shaped component) between the U-shaped components 2 and the L-shaped components 5 of this panel. Among them, the skin preform 1 has 28 plies with a thickness of 3.5 mm, the U-shaped components 2 and the L-shaped components 5 have 12 plies with a thickness of 1.5 mm, and the cross-sectional area of the R-corner filling component 3 ("◢"-shaped filling core) is 18.17 mm 2 .

[0109] Figure 6 The skin profile of the shown U-shaped stiffened panel is composed of 3 planes, resulting in a more complex bottom surface for 2 U-shaped components located at the lower parts on both sides. When grouping, first select these two U-shaped components as the second group of U-shaped components 2-2, and the adjacent U-shaped components are used as the first group of U-shaped components 2-1, and so on, so that the first group of U-shaped components and the second group of U-shaped components are arranged alternately, as Figure 8 shown.

[0110] The first group of U-shaped components 2-1 is positioned and installed using a U-shaped rib forming die. The U-shaped rib forming die uses a rigid material die and is positioned by a limit block 8. The second group of U-shaped components 2-2 is positioned and installed using an auxiliary forming die. The auxiliary forming die preferably uses a non-rigid material die.

[0111] The skin preform 1 is laminated on the panel outer shape die 6, and 28 plies are laminated in the order of the skin ply table, with a theoretical thickness of 3.5 mm. After lamination, vacuum is sealed and it is put into the autoclave for hot compaction.

[0112] The U-shaped components 2 are laminated on the U-shaped rib forming die 7 in the form of a male die according to the ply order of the corresponding U-shaped components 2. The number of plies is 12, with a thickness of 1.5 mm. After lamination, vacuum is sealed and it is put into the autoclave for hot compaction.

[0113] The L-shaped components 5 are laminated on the lamination die in the form of a male die. The number of plies is 12, with a thickness of 1.5 mm. After lamination, vacuum is sealed and it is put into the autoclave for hot compaction.

[0114] For the R - corner filling component 3, a pre - compaction mold with a cavity having the same cross - section size and shape as the "◢" cross - section was designed and prepared. Calculation of material usage: Calculate the width of the unidirectional prepreg tape required according to the cross - sectional area of the filling core material "◢". The cross - sectional area of the "◢" filling core material is 18.17 mm 2 , the thickness of a single layer of prepreg is 0.125 mm. The calculated theoretical width of the unidirectional prepreg tape is 145.34 mm. Multiply the calculated theoretical width of the unidirectional prepreg tape by a coefficient of 1.15 to obtain the required width of the unidirectional prepreg tape, which is 167 mm. Cut the unidirectional prepreg tape into the required width, and the unidirectional prepreg tape is subjected to hot compaction and shaping through the "◢" pre - compaction mold.

[0115] Hot compaction process parameters: temperature 60°C ± 5°C, pressure 4 MPa ± 0.5 MPa, heat - preservation time 10 min ± 5 min.

[0116] Select 5 U - shaped components 2 - 1 of the first group and their U - shaped rib forming molds 7, and place them at the first position of the skin preform 1 on the panel outer - shape mold 6. Install a positioning cross - beam on the panel outer - shape mold 6, and a limit block 8 is connected to the positioning cross - beam. Position the U - shaped components 2 - 1 of the first group and their U - shaped rib forming molds 7 one by one on the skin preform 1 through the limit block 8.

[0117] After that, successively combine all the R - corner filling components ( "◢" filling core material, "◣" filling core material) adjacent to the U - shaped components 2 - 1 of the first group to form the first U - shaped rib panel component, as Figure 9 shown.

[0118] Place Figure 9 All the U - shaped components 2 - 1 of the first group, all the flat components 4, the R - corner filling components, the L - shaped components 5 that have been positioned and assembled with the positioning device, and the entire positioning device as shown, are all covered with auxiliary materials and encapsulated in a vacuum film, and then heated and pressure - compacted in a hot - press autoclave. The hot - compaction temperature is 65°C ± 5°C, the pressure is 5 MPa ± 0.5 MPa, and the heat - preservation time is 20 min ± 5 min.

[0119] The U - shaped components of the second group are combined and positioned between the first stringer preforms of the first U - shaped rib panel component to form the second U - shaped rib panel component. Assemble the auxiliary forming mold. Specifically, select 4 U - shaped components 2 - 2 of the second group and assemble them one by one at the second position between the 5 U - shaped components 2 - 1 of the first group of the first U - shaped rib panel component that has been compacted to obtain the second U - shaped rib panel component.

[0120] The U - shaped components 2 adjacent to the L - shaped components 5 on both sides of the panel are the U - shaped components 2 - 1 of the first group. After assembling the U - shaped components 2 - 2 of the second group, assemble 2 L - shaped components 5 on both sides of the panel respectively.

[0121] Thereafter, assemble two auxiliary forming dies located in the inner cavity of the U-shaped component 2-2 of Group II and the corresponding dies for the L-shaped component 5.

[0122] Encapsulate the second U-shaped rib wallboard component, the die, and the positioning device on the wallboard contour die to form a vacuum system, and then perform hot press autoclave curing and forming.

[0123] Lay the polytetrafluoroethylene cloth and the breather felt to completely cover the assembled second U-shaped rib wallboard component, the U-shaped rib forming die 7, the auxiliary forming die, the limit block 8, the L-shaped components 5 on both sides of the wallboard and their corresponding dies. Paste sealing putty around the wallboard contour die 6 and encapsulate the vacuum film. In the hot press autoclave, perform curing and forming according to the material process parameters.

[0124] The above are only the preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for integrally forming a U-shaped reinforced wall panel, characterized in that: The following steps are involved: S1. According to the structure of the U-shaped stiffened wall panel, the U-shaped stiffened wall panel is decomposed into structural units according to the interface of the ply group, wherein the U-shaped stiffened wall panel comprises a skin ply group and a plurality of long stringer ply groups arranged in parallel on the skin ply group; S2, respectively stacking the skin ply group and each stringer ply group, and pre-pressing and shaping, to obtain a skin preform, a plurality of first stringer preforms, and a plurality of second stringer preforms, wherein the first stringer preform is used to be positioned and installed at a first position of the skin preform, and the second stringer preform is used to be positioned and installed at a second position of the skin preform, and the first position and the second position are arranged alternately; S3, a positioning device positions and installs the first long stringer preform and the U-shaped rib forming die at the first position to obtain a first U-shaped rib wall panel assembly; S4, encapsulating the first U-shaped rib wall panel assembly, and putting it into an autoclave for heating and pressurization, and obtaining a U-shaped rib wall panel preform after hot compaction and shaping; S5, positioning and installing the second long stringer preform at the second position, and setting an auxiliary mold in the second long stringer preform to obtain a second U-shaped rib wall panel assembly; S6. Lay auxiliary materials on the second U-shaped reinforced wall panel assembly and package it, and put it into an autoclave for curing and forming to obtain a U-shaped reinforced wall panel.

2. The integral forming method of the U-shaped reinforced wall panel according to claim 1, characterized in that: The first stringer preform includes a U-shaped component and / or an L-shaped component, a flat plate component and an R-corner filling component, and the second stringer preform is a U-shaped component and / or an L-shaped component.

3. The integral forming method of the U-shaped reinforced wall panel according to claim 2, characterized in that: The forming process of the first long stringer preform comprises the following steps: When the first long stringer preform is a U-shaped component, the U-shaped component is stacked on the U-shaped forming mold. When the thickness does not exceed 1 mm, vacuum pre-compacting or hot compacting is performed at room temperature after stacking. When the thickness exceeds 1 mm, hot compacting is performed after stacking; When the first long stringer preform is an L-shaped component, the L-shaped component is laid on the layup mold. When the thickness does not exceed 1 mm, vacuum pre-compacting or hot compacting is performed at room temperature after the layup is completed. When the thickness exceeds 1 mm, hot compacting is performed after the layup; When the flat plate components are stacked on the platform, if the thickness does not exceed 1mm, they are pre-compacted or hot compacted at room temperature after stacking. If the thickness exceeds 1mm, hot compaction is performed after stacking; The theoretical width of the prepreg unidirectional tape is calculated according to the cross-sectional area of ​​the R-corner filling component and the single-layer thickness of the prepreg. The theoretical width of the prepreg unidirectional tape is multiplied by a coefficient of 1.05 to 1.15 to obtain the width of the prepreg unidirectional tape. The prepreg unidirectional tape is cut to the width of the prepreg unidirectional tape, and after stacking, it is hot-compacted and shaped through a pre-compacting mold.

4. The integral forming method of the U-shaped reinforced wall panel according to claim 1, characterized in that: The forming process of the second long stringer preform comprises the following steps: When the second long stringer preform is a U-shaped component, the U-shaped component is stacked on the U-shaped forming mold. When the thickness does not exceed 1 mm, vacuum pre-compacting or hot compacting is performed at room temperature after stacking. When the thickness exceeds 1 mm, hot compacting is performed after stacking; When the second long stringer preform is an L-shaped component, the L-shaped component is laid on the layup mold. When the thickness does not exceed 1 mm, vacuum pre-compacting or hot compacting is performed at room temperature after the layup is completed. When the thickness exceeds 1 mm, hot compacting is performed after the layup.

5. The integral forming method of the U-shaped reinforced wall panel according to claim 1, characterized in that: During the hot compaction and shaping process: the temperature does not exceed 70°C, the pressure does not exceed 6MPa, and the insulation time is 5 to 30 minutes.

6. The integral forming method of the U-shaped reinforced wall panel according to claim 1, characterized in that: The forming process of the skin preform comprises the following steps: The skin layer group is stacked on the panel outer shape mold. When the thickness of the skin layer group does not exceed 3mm, it can be pre-compacted by vacuuming at room temperature or hot compacted after stacking. When the thickness of the skin component exceeds 3mm, hot compaction is performed after stacking.

7. The integral forming method of the U-shaped reinforced wall panel according to claim 1, characterized in that: The positioning device includes a limit block, and step S3 includes the following steps: The first long stringer preform and the U-shaped rib forming mold are placed at a first position, and the limiting block is limitedly connected to the U-shaped rib forming mold to obtain a first U-shaped rib wall panel assembly.

8. The integral forming method of the U-shaped reinforced wall panel according to claim 7, characterized in that: The U-shaped rib forming die is made of a rigid material, and is provided with a limiting groove with a trapezoidal cross section, and the limiting block is clamped in the limiting groove.

9. The integral forming method of the U-shaped reinforced wall panel according to claim 1, characterized in that: Step S5 includes the following steps: The second stringer preform is placed at the second position, and an auxiliary molding die is arranged on the second stringer preform, wherein the auxiliary molding die is made of a non-rigid material.

10. The integral forming method of the U-shaped reinforced wall panel according to claim 1, characterized in that: Step S6 includes the following steps: Laying demoulding material and breathable felt on the second U-shaped rib wall panel assembly to fully cover the second U-shaped rib wall panel assembly, pasting sealing putty around the second U-shaped rib wall panel assembly to encapsulate the vacuum film; The packaged second U-shaped rib wall panel assembly is placed in an autoclave and cured and formed according to preset process parameters.

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