A method for manufacturing a composite cylindrical skin

Abstract

This invention provides a method for manufacturing a composite material tubular skin, comprising: fabricating a mold according to the shape of the tubular skin, and adjusting the angle of the end frame of the mold according to the end frame of the tubular skin; using the mold to lay the end frame of the tubular skin, and compacting the layup at the end frame of the tubular skin; sequentially laying the inner layer, compacting, and laying the outer layer of the tubular skin to obtain a finished tubular skin; wherein, during the inner and outer layer laying, the end of the tubular skin needs to be flipped to the end frame, and the skin at the end frame needs to be trimmed so that the skin can cover the layup at the end frame of the tubular skin; and curing the finished tubular skin to obtain a cured tubular skin. The composite material tubular skin manufacturing method of this invention has the advantages of simple operation and high efficiency.

Description

Technical Field

[0001] This invention belongs to the field of composite material skin manufacturing, and in particular relates to a method for manufacturing composite material cylindrical skin. Background Technology

[0002] With the vigorous development of my country's aviation industry, in order to further cope with the complex load conditions in outer space, it is the main direction of my country's current development to achieve lightweighting of products with large size and irregular structure, such as launch vehicle fairings, strategic missile domes, and transition sections and compartments of various aircraft, while meeting the overall structural strength requirements. Metallic materials are inherently sensitive to internal and processing defects. If various minute defects occur during production and manufacturing and are not detected in time, they can easily cause catastrophic damage to the overall structure. This has led to a greater preference for advanced composite materials with lightweight, high strength, corrosion resistance, and easy molding characteristics. However, when composite cylindrical skins are connected to other sections, they are generally designed with inward or outward flanged end frame structures. But after curing, the end frame structure deforms and has poor flatness due to the release of thermal stress. This may lead to a gradient in the radial thickness of the processed end frame, fiber breakage, and reduced continuity, affecting the structural strength and dimensional accuracy of the cylindrical skin, which is detrimental to the subsequent assembly and use of the cylindrical skin. Summary of the Invention

[0003] In view of this, the present invention aims to propose a method for manufacturing composite cylindrical skin to solve the problem that deformation of the front and rear end frames of the cylindrical skin during the existing cylindrical skin manufacturing process leads to poor structural strength and dimensional accuracy after processing.

[0004] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0005] A method for manufacturing a composite cylindrical skin includes:

[0006] A mold is made according to the shape of the tubular skin, and the angle of the corresponding end frame of the mold is adjusted according to the end frame of the tubular skin.

[0007] The mold is used to lay the end frame of the tubular skin and the layer at the end frame of the tubular skin is compacted; wherein, when laying the end frame of the tubular skin, it is necessary to flip from the end frame to the thickened area of ​​the skin, with the end frame as the reference.

[0008] The inner layer of the tubular skin is laid, compacted, and then the outer layer is laid in sequence to obtain the finished tubular skin. During the laying of the inner and outer layers, both ends of each layer of tubular skin must be flipped over to the ply at the end frame of the tubular skin. During the flipping process, the ends of each layer of tubular skin must be opened and staggered so that the ends of each layer of tubular skin can cover the ply at the end frame of the tubular skin after being flipped over.

[0009] The tubular skin after being laid is cured to obtain a cured tubular skin;

[0010] Remove the cured cylindrical skin from the mold.

[0011] Furthermore, the step of fabricating a mold according to the shape of the tubular skin, and adjusting the angle of the corresponding end frame of the mold according to the end frame of the tubular skin, includes:

[0012] A mold is made according to the shape of the tubular skin;

[0013] The angle of the inner flange structure end frame on the mold is set to an elevation angle so that the angle of the inner flange structure end frame on the mold is smaller than the design angle of the inner flange structure end frame of the cylindrical skin.

[0014] The angle of the outer flange structure end frame of the mold is set to a negative angle so that the angle of the outer flange structure end frame of the mold is greater than the design angle of the outer flange structure end frame of the cylindrical skin.

[0015] Furthermore, the step of using the mold to lay the end frame of the cylindrical skin and compacting the layup at the end frame of the cylindrical skin includes:

[0016] The layers are laid in a cyclical pattern according to the (45 / -45 / 0 / 90) layup sequence, from the starting point of the end frame towards the thickened area of ​​the skin, with each layer gradually changing; wherein, the layup angle of the cylindrical skin end frame is specified as 0° in the radial direction and 90° in the circumferential direction.

[0017] The ply at the end frame of the cylindrical skin is compacted using an autoclave.

[0018] Furthermore, the process of sequentially laying and compacting the inner layer of the tubular skin, followed by laying the outer layer, to obtain the completed tubular skin includes:

[0019] Perform inner layer laying of the tubular skin, and during the inner layer laying process, flip the two ends of each completed tubular skin layer onto the layup at the end frame of the tubular skin respectively;

[0020] The skin layer obtained by the inner layer is compacted using an autoclave;

[0021] Perform the outer layer laying of the tubular skin, and during the outer layer laying process, flip the two ends of each completed tubular skin layer onto the layer at the end frame of the tubular skin respectively;

[0022] In the process of flipping the two ends of each layer of tubular skin to the end frame of the tubular skin after it has been laid, it is necessary to open the end of each layer of tubular skin and make the openings on the ends of each layer of tubular skin staggered so that the ends of each layer of tubular skin can cover the layup at the end frame of the tubular skin after being flipped.

[0023] Furthermore, after sequentially performing the inner layer laying, compaction, and outer layer laying of the tubular skin to obtain the completed tubular skin, the method further includes:

[0024] When the cylindrical skin is conical, a reinforcing plate is laid on the cylindrical skin after it is laid, facing one end of the large-diameter end frame of the mold; wherein, at least four reinforcing plates are evenly arranged along the circumference of the skin after it is laid.

[0025] When the tubular skin is cylindrical, anti-rotation grooves are applied to the end frame of the tubular skin after the inner layer is laid; wherein, at least four anti-rotation grooves are evenly arranged along the circumference of the end frame of the tubular skin after the inner layer is laid.

[0026] Furthermore, when the cylindrical skin is conical, the reinforcement plate is applied to the cylindrical skin after it has been laid, facing the end of the mold's large-diameter end frame, including:

[0027] A positioning block for positioning the reinforcing plate is provided on the mold; wherein the positioning block is detachably mounted on the mold;

[0028] Using the positioning block, a reinforcing plate is laid on the cylindrical skin after the laying is completed, at a position facing one end of the large-diameter end frame of the mold.

[0029] Furthermore, after curing the laid skin to obtain a cured skin, the method further includes:

[0030] The cured tubular skin is machined to obtain the finished tubular skin.

[0031] Compared with existing technologies, the method for manufacturing a composite cylindrical skin according to the present invention has the following advantages:

[0032] (1) The composite material cylindrical skin manufacturing method of the present invention has the advantages of simple operation and high efficiency. By adjusting the angle of the mold end frame according to the cylindrical skin end frame, it is beneficial to prevent the deformation of the end frame flange structure of the skin after demolding, thereby eliminating the stress of the ply at the end frame of the finished skin, reducing the possibility of deformation of the skin end frame, and improving the stability and reliability of the skin end frame.

[0033] (2) The composite material cylindrical skin manufacturing method of the present invention improves the 90° continuity of the end frame by changing the layup method of the cylindrical skin end frame from the start of the thickened area of ​​the skin to the start of the end frame to the thickened area of ​​the skin. This reduces the asymmetry and unevenness of the fiber caused by the layup cutting at the end frame position, thereby helping to further reduce the deformation of the end frame.

[0034] (3) The composite material tubular skin manufacturing method of the present invention uses a mold to first lay and compact the tubular skin end frame, which can strengthen the structural strength of the skin end frame before the overall tubular skin is laid. After the inner layer is laid, compacted and the outer layer is laid, the overall structural strength of the skin and the end frame is improved, which is conducive to further improving the stability and reliability of the skin in the subsequent assembly and use process. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0036] Figure 1 This is a schematic diagram of a method for manufacturing a composite cylindrical skin according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the conical cylindrical skin mold in a composite material cylindrical skin manufacturing method according to an embodiment of the present invention;

[0038] Figure 3 This is a side view of the conical cylindrical skin mold in a composite material cylindrical skin manufacturing method according to an embodiment of the present invention;

[0039] Figure 4 for Figure 3 A magnified view of a section at point A in the middle;

[0040] Figure 5 for Figure 3 A local method diagram at point B;

[0041] Figure 6 This is a schematic diagram of the cylindrical skin structure in a composite material cylindrical skin manufacturing method according to an embodiment of the present invention;

[0042] Figure 7 This is a schematic diagram of the anti-rotation groove in the cylindrical skin of a composite material cylindrical skin manufacturing method according to an embodiment of the present invention.

[0043] Explanation of reference numerals in the attached figures:

[0044] 1. Mold; 2. Grille engraving; 3. Positioning block; 4. Front frame pressure plate; 5. Anti-rotation groove. Detailed Implementation

[0045] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0046] This invention provides a method for manufacturing a composite material cylindrical skin, which can be used in the manufacture of composite material cylindrical skins, such as... Figures 1 to 7 As shown, the specific steps of the above method are as follows:

[0047] Step 101: Make a mold according to the shape of the cylindrical skin, and adjust the angle of the corresponding end frame of the mold according to the end frame of the cylindrical skin.

[0048] Specifically, a mold can be made first according to the designed shape of the cylindrical skin, and then the angles of the front and rear end frames of the mold can be adjusted according to the dimensions of the front and rear end frames of the designed cylindrical skin, the coefficient of thermal expansion of the material, and the operating temperature.

[0049] For example, after the mold is made according to the shape of the tubular skin, the angle of the inner flange end frame of the mold can be set to an elevation angle so that the angle of the inner flange end frame of the mold is less than the design angle of the inner flange end frame of the tubular skin. At the same time, the angle of the outer flange end frame of the mold can also be set to a negative angle so that the angle of the outer flange end frame of the mold is greater than the design angle of the outer flange end frame of the tubular skin.

[0050] By setting the angle of the inward-flanged end frame of the mold to an upward angle, the inward buckling deformation of the front end frame of the skin can be eliminated. Conversely, by setting the angle of the outward-flanged end frame of the mold to a negative angle, the outward warping deformation of the rear end frame of the skin can be prevented. This design avoids a gradient in the radial thickness of the end frame after processing, thus preventing fiber breakage and reducing continuity. This not only improves the structural strength and dimensional accuracy of the cylindrical skin but also facilitates subsequent skin layup, enhancing the skin's stability and structural strength.

[0051] In practical applications, the tubular skin can be conical or cylindrical. When the tubular skin is conical, those skilled in the art can create a mold based on its shape, setting the angle of the small-diameter front frame (i.e., the inner flange structure end frame) on the mold to an upward angle so that the angle of the mold's front frame is smaller than the design angle of the tubular skin's front frame (i.e., the angle of the mold's inner flange structure end frame is smaller than the design angle of the tubular skin's inner flange structure end frame). Simultaneously, the angle of the large-diameter end frame (i.e., the outer flange structure end frame) on the mold is set to a negative angle so that the angle of the mold's rear frame is greater than the design angle of the tubular skin's rear frame. By setting the angle of the small-diameter front frame on the mold to an upward angle, the inward buckling deformation of the conical tubular skin's front frame can be eliminated, while by setting the angle of the large-diameter end frame on the mold to a downward angle, the outward warping deformation of the conical skin's rear frame can be avoided.

[0052] For example, such as Figures 2 to 5 As shown, taking a conical cylindrical skin as an example, when the mold 1 is made of steel and the product is made of carbon fiber, the curing temperature is in the range of 120-250℃, the width of the inner flange of the front frame of the cylindrical skin is 40-70mm and the thickness is 4-8mm, the width of the outer flange of the rear frame is also 40-70mm and the thickness is 4-8mm, the angle can be adjusted by about 0.5°, so that the angle of the front frame on the mold 1 is less than the design angle of the front frame of the cylindrical skin by about 0.5°, and the angle of the rear frame of the mold 1 is greater than the design angle of the rear frame of the cylindrical skin by about 0.5°.

[0053] Specifically, when adjusting the mold angle, those skilled in the art can consider multiple coupling factors and, through simulation calculations, obtain the approximate deformation of the cylindrical skin end frame. Then, they can adjust the mold angle based on the specific skin laying method. For example, if the laying method results in a more uniform layering of the end frame, allowing for flipping and laying from the end frame towards the thickened skin area, the corresponding deformation will be reduced, and the mold angle can be appropriately reduced. Conversely, if the actual laying method results in uneven layering of the end frame, the mold angle should be appropriately increased. Therefore, those skilled in the art need to adjust the mold angle based on the actual situation, ensuring that the angle of the inner flanged end frame of the mold is smaller than the design angle of the inner flanged end frame of the cylindrical skin, and that the angle of the outer flanged end frame of the mold is larger than the design angle of the outer flanged end frame of the cylindrical skin. This adjustment of the mold angle helps to eliminate end frame deformation.

[0054] When the tubular skin is cylindrical, those skilled in the art can also create a mold based on the shape of the tubular skin, setting the angles of both the front and rear frames of the mold to an elevation angle, so that the angles of the front and rear frames of the mold are smaller than the design angles of the front and rear frames of the tubular skin. By setting the angles of both the front and rear frames of the mold to an elevation angle, the inward deformation of the front and rear frames of the skin can be eliminated, which is beneficial for subsequent skin layering and improves the stability and structural strength of the skin.

[0055] In practical use, after making a mold according to the shape of the tubular skin and adjusting the angles of the front and rear frames of the mold according to the shape of the tubular skin, the method further includes: setting stringers and middle frame engravings on the surface of the mold according to assembly requirements.

[0056] For example, stringer lines or intermediate frame lines can be engraved on the mold surface according to actual assembly requirements to facilitate subsequent assembly. For instance, when the cylindrical skin is conical, stringer lines can be provided on the side surface of the mold; when the cylindrical skin is cylindrical, stringer lines and intermediate frame lines can be provided on the side surface of the mold. The length direction of the stringer lines is the same as the length direction of the generatrix of the cylindrical skin, and the intermediate frame lines are annular structures and coaxially arranged with the cylindrical skin. Those skilled in the art can also provide stringer lines or intermediate frame lines on the surface of the mold according to actual assembly requirements, which will not be elaborated here.

[0057] Step 102: Use the mold to lay the end frame of the tubular skin and compact the layer at the end frame of the tubular skin; wherein, when laying the end frame of the tubular skin, it is necessary to flip from the end frame to the thickened area of ​​the skin based on the end frame.

[0058] First, the layers can be laid in a cyclical pattern according to the (45 / -45 / 0 / 90) layup sequence, from the starting point of the end frame to the thickened area of ​​the skin, with each layer gradually changing; among them, the layup angle of the cylindrical skin end frame is specified as 0° in the radial direction and 90° in the circumferential direction.

[0059] Secondly, an autoclave can be used to compact the ply at the end frame of the cylindrical skin. Using an autoclave to compact composite ply is a common technique used by those skilled in the art, and will not be elaborated upon here. Those skilled in the art can choose an appropriate compaction method according to actual needs to achieve compaction of the ply at the front and rear frames of the cylindrical skin.

[0060] For example, this embodiment describes the front and rear frame layup using carbon fiber composite materials, as detailed below:

[0061] The front frame layup can use carbon fiber unidirectional epoxy prepreg (UD700-12K / IS1801-165 / 34-1000, single layer thickness 0.15mm), laid in a (45 / -45 / 0 / 90) cyclical sequence, from the starting point of the front frame towards the thickened skin area, with each layer gradually changing thickness. For example, each layer can gradually change thickness by (2±0.5)mm. Those skilled in the art can also adjust the thickness of each layer according to actual needs, which will not be elaborated here.

[0062] The rear frame ply can also use carbon fiber unidirectional epoxy prepreg (UD700-12K / IS1801-165 / 34-1000, single layer thickness 0.15mm), laid in a (45 / -45 / 0 / 90) ply sequence, from the starting point of the rear frame towards the thickened skin area, with each layer gradually changing. For example, each layer can gradually change by (1±0.3)mm. Those skilled in the art can also adjust the thickness of each layer according to actual needs, which will not be elaborated here.

[0063] Step 103: Sequentially lay, compact, and lay the inner and outer layers of the tubular skin to obtain the completed tubular skin. During the laying of the inner and outer layers, both ends of each layer of tubular skin must be flipped over to the layup at the end frame of the tubular skin. During the flipping process, an opening must be made at the end of each layer of tubular skin, and the openings on the ends of each layer of tubular skin must be staggered so that the flipped ends of each layer of tubular skin can cover the layup at the end frame of the tubular skin.

[0064] Specifically, the inner layer of the tubular skin can be laid first, and during the inner layer laying process, the two ends of each completed tubular skin layer are flipped over to the layup at the end frame of the tubular skin. Then, the skin layup obtained from the inner layer laying is compacted using an autoclave. Finally, the outer layer of the tubular skin is laid, and during the outer layer laying process, the two ends of each completed tubular skin layer are flipped over to the layup at the end frame of the tubular skin. During the process of flipping the two ends of each completed tubular skin layer to the layup at the end frame of the tubular skin, an opening needs to be made at the end of each tubular skin layer, and the openings on the ends of each tubular skin layer should be staggered so that the flipped ends of each tubular skin layer can cover the layup at the end frame of the tubular skin.

[0065] In practical applications, to achieve the flipping of the cylindrical skin end and avoid multiple uncontrollable cracks during the outward flipping process or multiple uncontrollable wrinkles during the inward flipping process, those skilled in the art can trim the skin end before flipping to create multiple uniform openings, facilitating subsequent flipping. The specific number of openings can be adjusted according to actual needs, but to ensure the flatness of the layup after flipping, it is best to have no fewer than three openings.

[0066] By using a controlled method to cut the openings, bulges or cracks in the end frame can be avoided during subsequent ply layups, which helps to improve the structural strength of the end frame. In addition, by staggering the openings on the ends of each layer of cylindrical skin, the openings can be prevented from concentrating in one place. After multiple ply layups, the gaps at the openings can also be covered by subsequent ply layups, which is less likely to affect the overall structural strength of the end frame.

[0067] For example, this embodiment illustrates the application of carbon fiber composite materials to a conical cylindrical skin, as detailed below:

[0068] First, lay the inner layer of the tubular skin, i.e., lay layers 1 to 8. Use carbon fiber unidirectional epoxy prepreg (UD700-12K / IS1801-165 / 34-1000), laying layers 1 to 8 in the order [-45 / 0 / 45 / 0 / 90 / 90 / 0 / 45]. Then, fold the front and rear ends of each layer of the tubular skin to the front and rear end frames. During the laying of layers 1 to 8, for each layer, evenly cut four openings at the end of the skin and fold the end of the skin to the end frame. Furthermore, when laying layers 1 to 8, rotate the four openings 8° to 10° around the center of the end frame for each layer, so that after the 8th layer is laid, the four openings of each layer are staggered.

[0069] Then, it is compacted using an autoclave.

[0070] Finally, the outer skin layer, i.e., the 9th and 10th layers, is laid using carbon fiber unidirectional epoxy prepreg (UD700-12K / IS1801-165 / 34-1000). The tubular skin layers 9 and 10 are laid in a [0 / -45] layup sequence, with both ends of the tubular skin folded over to the front and rear end frames. During the laying of the 9th and 10th layers, four openings are evenly cut at the end of each layer, and the end of the skin is folded over to the end frame. Furthermore, when laying the 9th to 10th layers, the four openings are rotated 8° to 40° around the center of the end frame with each layer, so that after the 10th layer is laid, the four openings of each layer are staggered.

[0071] Furthermore, those skilled in the art can adjust the rotation angle of the opening in each layer according to the number of plies, so that the openings on the ends of each layer of cylindrical skin are staggered. By opening and flipping each ply during the laying process, not only is the difficulty of flipping the plies reduced, but also the openings on multiple plies are not easily concentrated due to the staggered arrangement. After subsequent processing, the integrity and structural strength of the end frame are improved.

[0072] In practical applications, when flipping the skin necessitates creating notches, the skin is cut to form these notches, and the openings of each layer are staggered. For openings that cannot be staggered or those that are too large, those skilled in the art can use triangular pieces to join the layers at the skin opening. Conversely, when flipping the skin after creating an opening results in a thick layer, those skilled in the art can also cut the layers to form joints, staggering the joints of each layer before joining the layers at these joints. Specifically, the joints of each layer also need to be staggered. By staggering the openings and joints, breakage can be avoided at the joints between the skin and the triangular pieces, as well as between skin layers, thus improving the structural strength of the rear frame before the skin.

[0073] Those skilled in the art can adjust the number of inner and outer layers as needed in practical applications, which will not be elaborated here. By first laying the inner layer and flipping the skin to the front and rear end frames, and then compacting and laying the outer layer, the structural strength and stability of the skin at the front and rear end frames can be further improved through multiple laying and compaction processes.

[0074] In practical applications, when the tubular skin is cylindrical, such as... Figure 6 and Figure 7 As shown, anti-rotation groove 5 is applied to the rear end frame of the skin after the inner layer is laid. Due to the large diameter of the cylinder and the high curing temperature, the difference in the coefficients of linear expansion between the material and the mold results in a gap between the product and the skin after curing, which can cause the product to separate from the skin. To prevent the product from rotating and affecting the subsequent machining accuracy, anti-rotation groove 5 can be set on the rear end frame of the skin. The anti-rotation groove 5 can be obtained by applying the material.

[0075] Specifically, at least four anti-rotation grooves 5 are evenly distributed along the circumference of the rear end frame of the skin after the inner layer is laid. The anti-rotation grooves 5 can be located below or on the outside of the end frame and are integrally laid with it, thus forming several anti-rotation grooves 5 (feature points) with a certain depth (e.g., 5-10mm) and width (e.g., 10-20mm) on the end frame, so that the anti-rotation grooves are enclosed by the mold. After curing and cooling, the shrinkage of the mold is greater than the shrinkage of the product, and the mold locks the anti-rotation grooves in place, preventing them from rotating, thereby achieving the effect of preventing product rotation.

[0076] Furthermore, when the cylindrical skin is conical, reinforcing plates are applied to the skin after it has been laid, facing the end of the mold's large-diameter end frame; wherein, at least four reinforcing plates are evenly distributed along the circumference of the skin after it has been laid. By placing multiple reinforcing plates on the skin near the end of the large-diameter end frame and integrally molding the reinforcing plates with the skin, it is beneficial to further enhance the structural strength and stability of the rear end frame of the conical cylindrical skin.

[0077] For example, when the tubular skin is conical, such as Figure 2 and Figure 3 As shown, a reinforcing plate is laid on the skin after the laying is completed, facing one end of the large-diameter end frame of the mold 1. The reinforcing plate can be positioned using a positioning block 3, specifically in the following manner:

[0078] First, a positioning block 3 for positioning the reinforcing plate can be set on the mold 1. The positioning block 3 is detachably mounted on the mold 1, which has mounting holes that mate with the positioning block 3. The positioning block 3 and the mounting holes can be engaged via a snap-fit ​​mechanism. Alternatively, those skilled in the art can use other methods to install the positioning block to achieve detachability from the mold; these will not be elaborated upon here. Then, the reinforcing plate can be laid on the completed skin facing the large-diameter end frame of the mold 1 using the positioning block 3. By setting the positioning block 3 on the mold 1, the position of the reinforcing plate can be positioned, which helps improve the laying accuracy and effect of the reinforcing plate.

[0079] Step 104: Curing the tubular skin after it has been laid to obtain the cured tubular skin.

[0080] Specifically, those skilled in the art can use existing autoclave curing technology to cure the skin after it has been laid, thereby obtaining the cured skin, which will not be elaborated here.

[0081] This embodiment first lays up and compacts the end frame to obtain the initial end frame structure of the tubular skin, which helps to improve the structural stability of the end frame in the subsequent laying process, thereby ensuring the flatness and structural strength of the tubular skin end frame.

[0082] After inner layer application, compaction, and outer layer application, the entire tubular skin is obtained. The inner layer application also provides a preliminary understanding of the overall structure of the tubular skin. After compaction, the flatness and structural strength of the tubular skin are significantly improved. The outer layer application requires fewer layers, which not only provides shielding and protection for the inner skin but also further improves the flatness of the tubular skin surface, facilitating subsequent assembly and use.

[0083] Finally, the plywood, inner skin, and outer skin at the end frame are cured in one step to obtain a cylindrical skin with good flatness and high structural strength. Compared with existing manufacturing methods, this method optimizes the process flow and helps to improve the product quality of the cylindrical skin.

[0084] In practical applications, after curing the laid skin to obtain a cured skin, the method further includes: machining the cured skin to obtain a machined cylindrical skin.

[0085] This embodiment uses a cylindrical skin as an example for illustration, such as... Figure 6 As shown, the specific implementation method is as follows:

[0086] The skin is not demolded initially; it is directly processed using machine tools or other machining equipment, such as cutting and drilling, to obtain the finished cylindrical skin. Those skilled in the art can also use other processing methods to process the skin according to actual needs. Processing the skin using a mold can improve the processing accuracy of the skin.

[0087] Step 105: Remove the cured cylindrical skin from the mold.

[0088] Specifically, such as Figure 2 and Figure 3 As shown, the positioning block 3 can be removed first using a pin puller, and the front frame pressure plate 4 required on the mold 1 can be removed as well. At this time, due to the difference in the coefficient of thermal expansion between the steel mold 1 and the carbon fiber composite material, and because the mold 1 has stringer engraving lines 2, the skin is already in the demolding state and can be directly demolded. Removing the cured skin from the mold 1 is a conventional technique for those skilled in the art. Those skilled in the art can also choose a suitable demolding method according to actual needs to achieve skin demolding, which will not be elaborated here.

[0089] The composite material cylindrical skin manufacturing method described in this embodiment, by adjusting the angles of the front and rear frames of the mold according to the shape of the cylindrical skin, helps prevent the front and rear frames of the skin from deforming after demolding, thereby eliminating stress at the front and rear frames of the finished skin, reducing the possibility of deformation, and improving the stability and reliability of the front and rear frames. Furthermore, by using a mold to first lay and compact the front and rear frames, the structural strength of the skin at the front and rear frames can be strengthened before the overall skin is laid. After the inner layer is laid, compacted, and the outer layer is laid, the overall structural strength of the skin and the front and rear frames is improved, which further enhances the stability and reliability of the skin during assembly and use.

[0090] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of manufacturing a composite material cylindrical skin, characterized by, include: A mold is made according to the shape of the tubular skin, and the angle of the corresponding end frame of the mold is adjusted according to the end frame of the tubular skin. The mold is used to lay the end frame of the tubular skin and the layer at the end frame of the tubular skin is compacted; wherein, when laying the end frame of the tubular skin, it is necessary to flip from the end frame to the thickened area of ​​the skin, with the end frame as the reference. The inner layer of the tubular skin is laid, compacted, and then the outer layer is laid sequentially to obtain the completed tubular skin. During both the inner and outer layer laying processes, the two ends of each completed tubular skin layer are flipped onto the layers at the end frame of the tubular skin. During this flipping process, an opening is made at the end of each tubular skin layer, and the openings on the ends of each layer are staggered so that the flipped ends of each tubular skin layer can cover the layers at the end frame. The staggered openings are configured such that, in subsequent layers, the opening on each layer is rotated circumferentially around the end frame by a preset angle relative to the opening at the corresponding position of the previous layer, with the preset angle being 8°-40°. The tubular skin after being laid is cured to obtain a cured tubular skin; Remove the cured cylindrical skin from the mold; The step of fabricating a mold according to the shape of the tubular skin, and adjusting the angle of the corresponding end frame of the mold according to the end frame of the tubular skin, includes: A mold is made according to the shape of the tubular skin; The angle of the inner flange structure end frame on the mold is set to an elevation angle so that the angle of the inner flange structure end frame on the mold is smaller than the design angle of the inner flange structure end frame on the cylindrical skin. The angle of the outer flange structure end frame of the mold is set to a downward angle so that the angle of the outer flange structure end frame of the mold is greater than the design angle of the outer flange structure end frame of the cylindrical skin.

2. The method of claim 1, wherein, The process of using the mold to lay the end frame of the cylindrical skin and compacting the layup at the end frame of the cylindrical skin includes: The layers are laid in a cyclical pattern according to the (45 / -45 / 0 / 90) layup sequence, from the starting point of the end frame towards the thickened area of ​​the skin, with each layer gradually changing; wherein, the layup angle of the cylindrical skin end frame is specified as 0° in the radial direction and 90° in the circumferential direction. The ply at the end frame of the cylindrical skin is compacted using an autoclave.

3. The method according to claim 1, characterized in that, After sequentially performing the inner layer laying, compaction, and outer layer laying of the tubular skin to obtain the completed tubular skin, the method further includes: When the cylindrical skin is conical, a reinforcing plate is laid on the cylindrical skin after it is laid, facing one end of the large-diameter end frame of the mold; wherein, at least four reinforcing plates are evenly arranged along the circumference of the skin after it is laid. When the tubular skin is cylindrical, anti-rotation grooves are applied to the end frame of the tubular skin after the inner layer is laid; wherein, at least four anti-rotation grooves are evenly arranged along the circumference of the end frame of the tubular skin after the inner layer is laid.

4. The method according to claim 3, characterized in that, When the cylindrical skin is conical, the reinforcement plate is applied to the cylindrical skin after it has been laid, facing the end of the mold's large-diameter end frame, including: A positioning block for positioning the reinforcing plate is provided on the mold; wherein the positioning block is detachably mounted on the mold; Using the positioning block, a reinforcing plate is laid on the cylindrical skin after the laying is completed, at a position facing one end of the large-diameter end frame of the mold.

5. The method according to claim 1, characterized in that, After curing the laid tubular skin to obtain the cured tubular skin, the method further includes: The cured tubular skin is machined to obtain the finished tubular skin.

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