Method for integrally molding a honeycomb sandwich structure rotary body fairing

Abstract

The application provides a honeycomb sandwich structure rotary body fairing integrated forming method, comprising the following steps: S1, designing and manufacturing a forming male die; S2, laying an inner skin on the forming male die by using a prepreg and extending to both side end frames for first curing; S3, polishing the rough inner skin with sandpaper for standby; S4, laying a honeycomb core material on the rough inner skin and filling the joint and the honeycomb with foaming glue, and grinding the thickened area of the honeycomb core material; S5, cutting the prepreg tape, laying the prepreg tape, laying an isolation film and a flexible silicone rubber pressure equalizing plate in sequence, and placing them in a hot press tank for second curing; and S6, laying an outer skin on the prepreg tape and extending to the end frames of both side end faces, and placing them in the hot press tank for third curing. The application reduces the curing times, reduces the connecting parts in integrated forming, further reduces the weight of the overall structure, reduces the manufacturing cost, and shortens the forming period.

Description

Technical Field

[0001] This invention relates to the field of composite materials and processing technology, and in particular to a method for integrally molding a honeycomb sandwich structure rotating fairing. Background Technology

[0002] High-strength carbon fiber / cyanate ester resin composites possess advantages such as high strength and low density, and have been widely used in the aerospace field. Simultaneously, the demand for weight reduction in composite material structures is constantly increasing. Composite material skin aluminum honeycomb sandwich structures exhibit outstanding advantages such as high specific strength, high specific stiffness, and high bending stiffness. Variable cross-section rotating honeycomb sandwich structures containing column and conical segments, as a commonly used fairing structure for spacecraft, increase payload, improve structural efficiency, and reduce structural weight. Existing methods for fabricating honeycomb sandwich fairing structures typically involve first molding two half-fairings and then assembling them into a complete fairing. In contrast, honeycomb sandwich half-fairing structures are first fabricated separately using inner and outer skins, then assembled and bonded to the skins and aluminum honeycomb core using an adhesive film, and finally cured in an autoclave.

[0003] Existing honeycomb sandwich fairing fabrication processes require a large number of molding molds and multiple curing cycles, and the assembly process for each half of the fairing is quite complex, resulting in high manufacturing costs and long lead times. Furthermore, the process of molding and assembling the two half-fairings separately necessitates the use of metal connectors, standard parts, and adhesives, inevitably increasing the structural weight. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and propose an integrated molding method for a honeycomb sandwich structure rotating fairing. This method can use only one set of molding male molds to solidify in three stages to obtain a honeycomb sandwich structure fairing in one piece. Because the integrated molding reduces the number of connecting parts, it further reduces the weight of the overall structure, lowers the manufacturing cost, and shortens the molding period.

[0005] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0006] The present invention provides a method for integral molding of a honeycomb sandwich structure rotating fairing, comprising the following steps:

[0007] S1. Design and manufacture the positive mold;

[0008] S2. The inner skin of the molding male mold is laid with prepreg and extended to the end frame of both sides of the molding male mold. After laying it with a thickness gradient, it is placed in a hot autoclave for the first curing.

[0009] S3. Use sandpaper to roughen the resin layer on the outer surface of the inner skin after the first curing to form a rough inner skin.

[0010] S4. After evenly applying a layer of primer to the outer surface of the rough inner skin, apply a layer of adhesive film and divide the rough inner skin into areas. Cut the honeycomb core material to the area corresponding to the rough inner skin, lay the honeycomb core material on the inner skin, and fill the joints and nearby honeycomb cells with expanding foam. After installation, grind the thickened areas of the honeycomb core material.

[0011] S5. Apply a layer of primer to the outer surface of the ground honeycomb core material, cut the prepreg tape, attach a layer of adhesive film, wrap the cut prepreg tape around the adhesive film, and place it in a thermostatic jar for a second curing.

[0012] S6. Lay the outer skin on the prepreg tape and extend it to the end frame. After laying it with a thickness gradient, place it in a hot autoclave for a third curing. Finally, an integral honeycomb sandwich structure rotating fairing is obtained.

[0013] Preferably, the honeycomb core material is a perforated aluminum honeycomb.

[0014] Preferably, a high-strength carbon fiber / cyanate ester resin prepreg is selected.

[0015] Preferably, the prepreg tape is made of carbon cloth / cyanate ester resin prepreg tape.

[0016] Preferably, the base adhesive is J47-B, the film is J47-C, and the foaming adhesive is J47-D.

[0017] Preferably, the width of the prepreg tape after cutting is 250–350 mm.

[0018] Preferably, the thickness of the flexible silicone rubber equalizing plate is in the range of 3 to 5 mm.

[0019] Preferably, the curing parameters are set as follows: temperature 130±5℃ / h, pressure 0.2~0.3Mpa.

[0020] Preferably, the prepreg tape is laid in two layers of spiral winding in opposite directions.

[0021] Preferably, after the prepreg tape is cut and a layer of adhesive film is pasted on, the release film and the flexible pressure plate are laid in sequence.

[0022] The present invention can achieve the following technical effects: using only one set of molding positive molds to cure in three stages, a honeycomb sandwich structure fairing is obtained in one piece. By reducing the number of curing times and reducing the number of connecting parts by one-piece molding, the weight of the overall structure is further reduced, the manufacturing cost is reduced and the molding period is shortened. Attached Figure Description

[0023] Figure 1 This is a flowchart of a method for integrally molding a honeycomb sandwich structure rotating fairing according to an embodiment of the present invention.

[0024] Figure 2 This is a schematic diagram of the structure of the molding male mold provided according to an embodiment of the present invention.

[0025] Figure 3 This is a schematic diagram of the laying of the inner skin according to an embodiment of the present invention.

[0026] Figure 4 This is a schematic diagram of the honeycomb layout provided in an embodiment of the present invention.

[0027] Figure 5 This is a schematic diagram of the winding and laying of prepreg tape according to an embodiment of the present invention.

[0028] Figure 6 This is a schematic diagram of the laying of the outer skin according to an embodiment of the present invention.

[0029] Figure 7 This is a schematic diagram of the structure of the rotating fairing provided in an embodiment of the present invention.

[0030] Figure 8 This is a cross-sectional structural diagram of a conventional fairing provided according to an embodiment of the present invention.

[0031] The reference numerals in the attached drawings include: 1. Molding male mold, 11. Mold segment, 12. End frame, 13. Central shaft, 2. Inner skin, 3. Honeycomb core material, 4. Prepreg tape, 5. Outer skin, 6. Honeycomb sandwich structure fairing. Detailed Implementation

[0032] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0034] Figure 1 The flowchart of the method for integral molding of the honeycomb sandwich structure rotating fairing provided in the embodiment of the present invention is shown.

[0035] like Figure 1 As shown in the figure, an embodiment of the present invention provides a method for integrally molding a honeycomb sandwich structure rotating fairing, which includes the following steps:

[0036] Step S1: Simultaneously prepare the molding male mold 1, honeycomb core material 3, prepreg and adhesive film.

[0037] Figure 2 The structure of the molding male mold provided in an embodiment of the present invention is shown.

[0038] like Figure 2 As shown, the process includes: designing and preparing a rotating fairing forming male mold 1 consisting of mold segments 11, end frames 12, and a central shaft 13, and the mold being machined and assembled from steel; preparing a honeycomb core material 3 with a specification of 5*0.03*25.7 mm; preparing prepreg and cutting the prepreg tape; and preparing the base adhesive, adhesive film, and foaming adhesive.

[0039] Step S2: Lay the inner skin 2 on the molding male mold 1 using prepreg and extend the inner skin 2 to the end frames 12 on both sides; when half of the layer is laid, make a low-temperature vacuum bag and pre-compact it at room temperature for 15 minutes, then lay the other half of the layer. After the layer is laid, make a high-temperature vacuum bag for the molding male mold 1 and place it in an autoclave. Set the curing parameters as follows: temperature 130±5℃ / 5h, pressure 0.2Mpa. After molding, the inner skin 2 is obtained.

[0040] Figure 3 The illustration shows the laying of the inner skin according to an embodiment of the present invention.

[0041] like Figure 3 As shown, the inner skin 2 has a thickness of 2 mm at the sidewall, and the ply thickness is represented as: [0 / +45 / 90 / -45 / 0]. 2S The inner skin 2 has a thickness of 6 mm at the end frames 12 on both sides, and the ply thickness is represented as: [0 / +45 / 90 / -45 / 0]. 6S ;

[0042] Step S3: Use sandpaper to roughen the resin layer on the outer surface of the cured inner skin 2 to facilitate the bonding of the new surface. After sanding, clean the rough outer surface of the inner skin 2 with a cleaning agent and let it dry for later use.

[0043] Step S4: After evenly applying a layer of primer to the outer surface of the rough inner skin 2, attach a layer of adhesive film and divide the rough inner skin 2 into areas. After cutting the honeycomb core material 3 to the corresponding area of ​​the rough inner skin, apply a layer of primer to the outer surface of the rough inner skin 2, lay the honeycomb core material 3 on the primer, and fill the joints and nearby honeycomb cells with expanding foam. After installation, grind the thickened parts of the honeycomb core material 3.

[0044] Figure 4 The illustration shows the placement of a honeycomb structure according to an embodiment of the present invention.

[0045] A layer of J47-B primer is evenly applied to the outer surface of the rough inner skin 2. After drying at room temperature for 15 minutes, a layer of J47-C adhesive film is applied. The inner skin 2 is divided into 3 sections along the axial direction and 4 sections along the circumference, for a total of 12 areas. The honeycomb core material 3 is then cut according to the 12 areas. A layer of J47-B primer is applied to the outer surface of the rough inner skin 2 to be bonded. After drying at room temperature for 15 minutes, the honeycomb core material 3 is laid on the outer surface of the rough inner skin 2, and J47-D expanding foam is used to fill the joints of the honeycomb core material 3 and the honeycomb cells near the joints. Because the curvature of the 12 areas is small, the honeycomb core material 3 only requires small deformation to bond with the J47-C adhesive film on the outer surface of the inner skin 2. Preliminary calculations show that the total thickness of the inner skin 2 and outer skin 5 increases by 8 mm. Therefore, in order to maintain the total thickness of the honeycomb sandwich structure at 25.7 mm, the thickened part of the honeycomb core material 3 needs to be ground down to 17.7 mm using an angle grinder to maintain the total thickness.

[0046] Step S5: Apply a layer of primer to the outer surface of the ground honeycomb core material 3, cut the prepreg tape, attach a layer of adhesive film, wrap the prepreg tape 4 around the adhesive film, and place it in a thermostatic jar for a second curing.

[0047] Figure 5 A schematic diagram of the winding and laying of the prepreg tape provided in an embodiment of the present invention is shown.

[0048] like Figure 5As shown, a layer of J47-B primer is applied to the outer surface of the honeycomb core material 3 and left to dry at room temperature for 15 minutes. The prepreg tape 4 is cut into narrow strips with a width of 300 mm, and J47-B primer is applied to it. After drying at room temperature for 15 minutes, a layer of J47-C adhesive film is pasted on. The prepreg tape 4 is laid in a spiral winding manner from top to bottom. The first layer is laid counterclockwise, and the second layer is laid clockwise. Two layers are laid in total, and the two layers of prepreg tape are laid at symmetrical angles (two layers of carbon cloth prepreg tape are laid in total, one clockwise and one counterclockwise, without any order. However, the winding direction of the two layers needs to be opposite because it is a rotating structure. If both layers are wound in the same direction, the product may have a slight tendency to deform after curing). During the winding process, a certain tension needs to be applied to the prepreg tape 4. The purpose is twofold: firstly, to ensure a tight fit between the honeycomb core material 3 and the inner skin 2, resulting in excellent shaping of the cured honeycomb core material 3; secondly, to effectively reduce the depth of the prepreg tape 4's indentation into the honeycomb core material 3 under the curing pressure of the autoclave, allowing the prepreg tape 4 to form a wrapping with a certain strength while preventing pits from appearing on the surface of the carbon cloth after curing. After the prepreg tape 4 is laid, a high-temperature non-porous release film is laid on top, followed by a 3 mm thick flexible silicone rubber equalizing plate. Then, a high-temperature vacuum bag is made and placed in an autoclave. The curing parameters are set as follows: temperature 130±5℃ / 5h, pressure 0.2Mpa. The flexible silicone rubber equalizing plate laid on the prepreg tape 4 is intended to further reduce the depth of the carbon cloth's indentation into the honeycomb core material 3 under the pressure of the autoclave, resulting in a smooth and flat surface of the cured prepreg tape 4, which is beneficial for the subsequent laying of the outer skin 5.

[0049] Step S6: The outer skin 5 is laid on the prepreg tape 4 and extended to the end frame 12 on both sides. After laying it with a thickness gradient, it is placed in a hot autoclave for a third curing, and finally the one-piece honeycomb sandwich structure rotating fairing 6 is obtained.

[0050] Figure 6 The illustration shows the laying of the outer skin provided in an embodiment of the present invention.

[0051] like Figure 6 As shown, the outer skin 5 is laid on the prepreg tape 4 and extends to the end frame 12. The outer skin 5 has a thickness of 2 mm at the sidewall, and the layup is represented as: [0 / +45 / 90 / -45 / 0]. 2S The outer skin 5 has a thickness of 6 mm at the end frame 12, and the ply count is represented as: [0 / +45 / 90 / -45 / 0]. 6S .

[0052] Figure 7 The structure of the rotating fairing provided in an embodiment of the present invention is shown.

[0053] like Figure 7As shown, the thickness of the outer skin 5 transitions from the sidewall to the end frame 12, and is laid out with a gradual thickness change. When half of the layer is laid out, a low-temperature vacuum bag is made and pre-compacted at room temperature for 15 minutes. Then the other half of the layer is laid out. After the layer is laid out, a high-temperature vacuum bag is made and placed in an autoclave. The curing parameters are set as follows: temperature 130±5℃ / 5h, pressure 0.2Mpa. Finally, after three curing processes, an integral honeycomb sandwich structure rotating fairing 6 is obtained.

[0054] Figure 8 The cross-sectional structure of the rotating fairing provided in an embodiment of the present invention is shown.

[0055] like Figure 8 As shown, the honeycomb sandwich structure rotating fairing 6 consists of an inner skin 2, a honeycomb core material 3, a prepreg tape 4, and an outer skin 5, from the inside out.

[0056] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0057] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

[0058] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for integrally molding a honeycomb sandwich structure rotating fairing, characterized in that, Includes the following steps: S1. Design and manufacture the positive mold (1); S2. The inner skin (2) is laid on the molding male mold (1) using prepreg and extends to the end frame (12) on both sides of the molding male mold (1). When half of the layer is laid, a low-temperature vacuum bag is made and pre-compacted at room temperature. Then the other half of the layer is laid. After laying the layer in a thickness gradient manner, a high-temperature vacuum bag is made for the molding male mold (1) and placed in a hot autoclave for the first curing. S3. Use sandpaper to roughen the resin layer on the outer surface of the inner skin (2) after the first curing to form a rough inner skin (2). S4. After uniformly applying a layer of primer to the outer surface of the rough inner skin (2), a layer of adhesive film is pasted and the rough inner skin (2) is divided into areas. The inner skin (2) is divided into 3 sections along the axial direction and 4 sections along the circumference, for a total of 12 areas. The honeycomb core material (3) is then cut according to the 12 areas. After the honeycomb core material (3) is cut to correspond to the area of ​​the rough inner skin (2), the honeycomb core material (3) is laid on the inner skin (2) and the joints and nearby honeycomb cells are filled with foam. After the installation is completed, the thickened area of ​​the honeycomb core material (3) is ground. S5. Apply a layer of the base adhesive to the outer surface of the ground honeycomb core material (3), cut the prepreg tape (4), paste a layer of the adhesive film, wrap the cut prepreg tape (4) around the adhesive film, and lay the prepreg tape (4) in a spiral winding manner from top to bottom. The first layer is laid counterclockwise, and the second layer is laid clockwise. A total of two layers are laid and the two layers of prepreg tape (4) are laid at symmetrical angles. Tension needs to be applied to the prepreg tape (4) during the winding process. After the prepreg tape (4) is laid, a high-temperature non-porous isolation film is laid on top of it, and then a flexible silicone rubber equalizing plate is laid. Then a high-temperature vacuum bag is made and placed in the autoclave for a second curing. S6. Lay the outer skin (5) on the prepreg tape (4) and extend it to the end frame (12). Lay it with a thickness gradient. When half of it is laid, make a low temperature vacuum bag and pre-compact it at room temperature. Then lay the other half of the layer. After the layer is laid, make a high temperature vacuum bag and place it in a thermostatic jar for a third curing. Finally, the integrated honeycomb sandwich structure rotating fairing (6) is obtained.

2. The method for integrally molding a honeycomb sandwich structure rotating fairing as described in claim 1, characterized in that, The honeycomb core material (3) is a perforated aluminum honeycomb.

3. The method for integrally molding a honeycomb sandwich structure rotating fairing as described in claim 1, characterized in that, High-strength carbon fiber / cyanate ester resin prepreg is selected.

4. The method for integrally molding a honeycomb sandwich structure rotating fairing as described in claim 1, characterized in that, The prepreg tape is made of carbon cloth / cyanate ester resin prepreg tape.

5. The method for integrally molding a honeycomb sandwich structure rotating fairing as described in claim 1, characterized in that, The base adhesive is J47-B, the film is J47-C, and the foaming adhesive is J47-D.

6. The method for integrally molding a honeycomb sandwich structure rotating fairing as described in claim 1, characterized in that, The width of the prepreg tape (4) after cutting is 250~350 mm.

7. The method for integrally molding a honeycomb sandwich structure rotating fairing as described in claim 1, characterized in that, The thickness of the flexible silicone rubber equalizing plate ranges from 3 to 5 millimeters.

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