Pre-embedded metal beam honeycomb sandwich structure, forming method and fairing

Abstract

This invention provides a pre-embedded metal beam honeycomb sandwich structure, a molding method, and a fairing, comprising: a metal beam, a lower skin, an upper skin, and a honeycomb; the metal beam and the honeycomb are installed between the upper skin and the lower skin, and the metal beam is disposed on the periphery of the honeycomb. This application achieves overall co-curing of materials with large differential expansion coefficients, avoiding the repeated use and production of large molding dies, greatly improving production cycle time and reducing die manufacturing costs.

Description

Technical Field

[0001] This invention relates to the field of composite material sandwich structure molding methods, specifically to a pre-embedded metal beam honeycomb sandwich structure, molding method, and fairing. Background Technology

[0002] During the storage, transfer, and launch of launch vehicles, fairings are required to protect satellites and other payloads from harmful factors such as harsh environments, aerodynamic heating, and resonance. Furthermore, with changes in communication frequency bands, higher demands are placed on the fairing's wave transmission performance, as well as on the overall strength, stiffness, and weight reduction of its components. Therefore, rocket fairings typically employ large envelope dimensions, sandwich structures with communication windows, and pre-embedded large metal beams to meet overall requirements.

[0003] A search of patent and non-patent literature revealed relevant patent documents, such as Chinese Patent CN108045002A, published on May 18, 2018, entitled "A Honeycomb Sandwich Structure and Its Preparation Method," which discloses a honeycomb sandwich structure and its preparation method. The honeycomb sandwich structure described in this patent requires first laying an adhesive layer and a prepreg layer on the upper and lower surfaces of the honeycomb core material, respectively, followed by pretreatment. After pretreatment, prepregs of different sequences and angles are then laid on top. This honeycomb sandwich structure and its preparation method do not involve pre-embedded large metal beams or other components, and its molding method consists of two cycles: pretreatment and post-curing. This lengthy molding cycle is detrimental to controlling production costs.

[0004] For example, Chinese patent CN108372693A, published on August 7, 2018, entitled "An Ultra-Large Single-Curved Reflective Surface Composite Honeycomb Sandwich Structure and Its Forming Method," discloses an ultra-large single-curved reflective surface composite honeycomb sandwich structure and its preparation method. The ultra-large single-curved reflective surface composite honeycomb sandwich structure described in this patent consists of three layers of hard aluminum plates, two layers of aluminum honeycomb cores, and a profile skeleton for connection and support. All materials described in this patent are aluminum alloys. During curing, the thermal expansion deformation of each component is the same, and aluminum alloy materials have poor wave transmission communication capabilities. The honeycomb sandwich structure forming method described in this patent is not suitable for forming sandwich structures containing materials with large differential expansion coefficients (such as metal and paper honeycomb).

[0005] Based on this, it is desirable to obtain a molding method for pre-embedded large metal beam honeycomb sandwich structures, which can meet the requirements of overall co-curing of materials with large differential expansion coefficients. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a pre-embedded metal beam honeycomb sandwich structure, a forming method, and a fairing.

[0007] According to the present invention, a pre-embedded metal beam honeycomb sandwich structure for a rocket fairing includes: a metal beam, a lower skin, an upper skin, and a honeycomb.

[0008] The metal beam and the honeycomb are installed between the upper skin and the lower skin, with the metal beam positioned around the periphery of the honeycomb.

[0009] Preferably, the metal beam comprises: a frame beam and a truss beam;

[0010] Both the lower skin and the upper skin are configured as arc-shaped surface structures with the arc extending in a straight line in a direction perpendicular to the plane where the arc is located;

[0011] The U-shaped frame beam is installed at the arc-shaped ends of the lower skin and the upper skin and is adapted to the shape of the arc-shaped ends of the lower skin and the upper skin;

[0012] The straight truss is installed on the straight sides of both the lower skin and the upper skin.

[0013] Preferably, a method for forming the pre-embedded metal beam honeycomb sandwich structure includes the following steps:

[0014] Step S1: The lower skin is laid up in a gradient according to a set order and angle, and the adhesive is applied as a whole.

[0015] Step S2: Install the truss beam and the frame beam to the peripheral boundary of the lower skin, with one side surface of the truss beam and the frame beam in contact with the surface of the lower skin, and the gap between the truss beam and the frame beam at the intersection is 1.5-3mm;

[0016] Step S3: Lay the honeycomb within the area enclosed by the truss and the frame beam, and apply adhesive to the honeycomb;

[0017] Step S4: After completing the gradient layup of the upper skin according to the set order and angle, prepare a vacuum bag and cure it in one step through an autoclave and curing oven.

[0018] Step S5: After hot demolding, a honeycomb sandwich structure with embedded metal beams is obtained.

[0019] Preferably, the lower skin and the upper skin are made of glass fiber reinforced resin matrix composite material with a thickness of 1-3 mm.

[0020] Preferably, the length of the truss is greater than 3m and the width is 20-50mm, and the arc circumference of the frame beam is greater than 5m and the width is 20-50mm.

[0021] Preferably, the honeycomb is an aramid paper honeycomb, the honeycomb paper thickness is 0.05-0.08 mm, the honeycomb thickness is 20-40 mm, and the density is 48-76 kg / m³. 3 .

[0022] Preferably, in step S4, the curing and molding process includes an initial heating and pressing stage, a stepped segmented heating and pressing stage, and a heat preservation and pressure holding stage.

[0023] Preferably, during the initial heating and pressurization stage, the heating temperature is 30-50°C, and the pressure inside the autoclave is increased and the auxiliary pressure inside the vacuum bag is removed during the initial heating stage.

[0024] In the stepped heating and pressurization stage, the temperature is first raised to 110-120℃ and pressurized to 0.1MPa. Then, during the process of raising the temperature to 120-150℃, the pressurization is increased to 0.5MPa in stages.

[0025] During the heat preservation and pressure holding stage, after holding the temperature for 1 hour, the temperature is further increased to 170-180℃, while maintaining a pressure of 0.5MPa. After holding the temperature for 4-6 hours, the temperature is lowered to 120℃ for hot demolding.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. This application achieves overall co-curing of materials with large differential expansion coefficients, avoiding the repeated use and production of large molding molds, greatly improving production cycle and reducing mold manufacturing costs;

[0028] 2. This application reduces the risk of product deformation caused by the multiple curing stages of large-size, multi-part products through a multi-stage heating and graded pressure insulation scheme;

[0029] 3. The sandwich structure of this application not only meets the overall strength and stiffness requirements of the rocket fairing, but also achieves omnidirectional and full wave-transparency functions. Attached Figure Description

[0030] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0031] Figure 1 A schematic diagram of the overall structure of the pre-embedded metal beam honeycomb sandwich structure;

[0032] Figure 2 This is a schematic diagram showing the relative positions of the truss, honeycomb, and skin.

[0033] Figure 3 A schematic diagram showing the location of the skin covering the truss surface;

[0034] Figure 4A schematic diagram showing the relative positions of the frame beam, honeycomb structure, and skin.

[0035] Figure 5 A schematic diagram of the overall skin and its interlacing layers;

[0036] As shown in the figure:

[0037] Detailed Implementation

[0038] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0039] Example 1

[0040] like Figures 1 to 5 As shown, this embodiment includes: a frame beam 1, a truss beam 2, a lower skin 3, an upper skin 4, and a honeycomb 5; the frame beam 1, the truss beam 2, and the honeycomb 5 are installed between the upper skin 4 and the lower skin 3, with the frame beam 1 and the truss beam 2 positioned around the periphery of the honeycomb 5. Both the lower skin 3 and the upper skin 4 are configured as arc-shaped surface structures with the arc extending in a straight line perpendicular to the plane containing the arc. The U-shaped frame beam 1 is installed at the arc-shaped ends of the lower skin 3 and the upper skin 4 and is adapted to the shape of the arc-shaped ends of the lower skin 3 and the upper skin 4. The straight truss beam 2 is installed on the straight sides of both sides of the lower skin 3 and the upper skin 4.

[0041] The truss beam 2 is longer than 3m and has a width of 20-50mm. The arc circumference of the frame beam 1 is greater than 5m and its width is 20-50mm. The lower skin 3 and upper skin 4 are made of glass fiber reinforced resin matrix composite material with a thickness of 1-3mm. The honeycomb 5 is made of aramid paper honeycomb with a honeycomb paper thickness of 0.05-0.08mm, a honeycomb 5 thickness of 20-40mm, and a density of 48-76kg / m³. 3 .

[0042] This embodiment also provides a method for forming a pre-embedded metal beam honeycomb sandwich structure, including the following steps:

[0043] Step S1: The lower skin 3 completes the gradient lay-up in the set order and angle, and the adhesive is laid out as a whole;

[0044] Step S2: Install the truss beam 2 and the frame beam 1 to the perimeter of the lower skin 3, with one side surface of the truss beam 2 and the frame beam 1 in contact with the surface of the lower skin 3, and the gap between the intersection of the truss beam 2 and the frame beam 1 is 1.5-3mm.

[0045] Step S3: Lay honeycomb 5 within the area enclosed by truss 2 and frame beam 1, and apply adhesive to honeycomb 5;

[0046] Step S4: After completing the gradient layup of the upper skin 4 according to the set order and angle, prepare a vacuum bag and cure it in one step through an autoclave and curing oven.

[0047] The curing and molding process includes an initial heating and pressing stage, a stepped heating and pressing stage, and a heat preservation and pressure holding stage. In the initial heating and pressing stage, the temperature is raised to 30-50℃, and the pressure inside the autoclave is increased while the auxiliary pressure inside the vacuum bag is removed. In the stepped heating and pressing stage, the temperature is first raised to 110-120℃ and pressure is applied at 0.1MPa. Then, as the temperature rises to 120-150℃, the pressure is applied in stages to 0.5MPa. In the heat preservation and pressure holding stage, after holding the temperature for 1 hour, the temperature is raised to 170-180℃, maintaining a pressure of 0.5MPa throughout. The temperature is then held for 4-6 hours before cooling to 120℃ for hot demolding.

[0048] Step S5: After hot demolding, a honeycomb sandwich structure with embedded metal beams is obtained.

[0049] Example 2

[0050] Example 2 is a preferred example of Example 1.

[0051] like Figures 1 to 5 As shown, the honeycomb sandwich structure is an integrally molded component, including: pre-embedded frame beam 1 and truss beam 2, honeycomb 5, upper skin 4 and lower skin 3. Frame beam 1, truss beam 2, honeycomb 5, upper skin 4 and lower skin 3 are cured simultaneously. Truss beam 2 is straight, frame beam 1 is U-shaped, honeycomb 5 is a variable cross-section and variable thickness honeycomb, and upper skin 4 and lower skin 3 are glass fiber reinforced resin matrix composite materials.

[0052] Truss beam 2 is longer than 3m and has a width of 20-50mm; frame beam 1 has an arc perimeter greater than 5m and a width of 20-50mm; honeycomb 5 is made of aramid paper, with a honeycomb paper thickness of 0.05-0.08mm, a honeycomb 5 thickness of 20-40mm, and a density of 48-76kg / m³. 3 The upper skin 4 and the lower skin 3 are fiber-reinforced resin-based composite materials with a thickness of 1-3 mm, laid up at a symmetrical (or quasi-symmetrical) angle.

[0053] Frame beam 1 and truss beam 2 are distributed around honeycomb 5. Honeycomb 5 is a variable cross-section and variable thickness structure. The upper skin 4 and lower skin 3 completely cover the upper and lower surfaces of frame beam 1, truss beam 2 and honeycomb 5, respectively.

[0054] The forming method of the embedded metal beam honeycomb sandwich structure includes the following steps:

[0055] Step 1: Complete the gradient lay-up of the lower skin 3 according to the set order and angle, and then apply the adhesive.

[0056] Step 2: Install frame beam 1 and truss beam 2 to the four boundary positions of the lower skin 3 completed in Step 1, with the lower surface of frame beam 1 and truss beam 2 in contact with the surface of the lower skin 3, and control the gap at the intersection of frame beam 1 and truss beam 2 to be 1.5-3mm.

[0057] Step 3: Within the concave area enclosed by the frame beam 1 and truss beam 2 completed in Step 2, lay honeycomb 5 in sequence, and apply adhesive to the upper surface of honeycomb 5;

[0058] Step 4: Based on the completion of Step 3, complete the gradient layup of the upper skin 4 according to a specific order and angle to prepare a vacuum bag. Then, it is formed in one step in equipment such as a thermostatic precipitator and curing oven. The one-time curing process includes the initial heating and pressing stage, the stepped segmented heating and pressing stage, and the heat preservation and pressure holding stage.

[0059] Step 5: After hot demolding, a honeycomb sandwich structure with embedded large metal beams is obtained.

[0060] During the initial heating and pressurization stage, the heating temperature is 30-50℃. During the initial heating stage, the pressure inside the autoclave can be increased. During this process, the auxiliary pressure inside the vacuum bag is removed.

[0061] In the stepped, segmented heating and pressing and heat preservation and pressure holding stages, the temperature is first raised to 110-120℃ and pressure is applied at 0.1MPa. Then, the temperature is raised to 120-150℃ and pressure is applied in stages to 0.5MPa. After holding at this temperature for 1 hour, the temperature is raised to 170-180℃, and the pressure is maintained at 0.5MPa. After holding at this temperature for 4-6 hours, the temperature is lowered to 120℃ and the product is hot-demolded.

[0062] In the above scheme, it should be noted that the specific order and angle refer to the fact that when using prepreg for layup, the layup angle and the order of the gradient position can be adjusted according to the specific circumstances of the implementation method and actual needs.

[0063] It is particularly noteworthy that in this embodiment, the lower skin 3 is first laid up as a whole, then the lower skin 3 is thickened and laid up according to a specific sequence, angle, and gradual position. Next, the frame beams 1 and truss beams 2 are installed, and a honeycomb structure 5 of varying thickness and cross-section is laid up within the concave area formed by the frame beams 1 and truss beams 2. Subsequently, the upper skin 4 is laid up. Finally, using equipment such as autoclaves and curing ovens, and vacuum bag-assisted molding technology, the entire structure is cured and molded. This allows the preparation method of this invention to achieve true integral curing and molding.

[0064] Example 3

[0065] This embodiment includes: the outer envelope size of the honeycomb sandwich structure is φ4200mm×5038mm in diameter; two truss beams 2 are distributed on the left and right sides of the sandwich structure along the length of 5038mm; two U-shaped frame beams 1 are distributed at the upper and lower ends of the sandwich structure along the arc direction of φ4200mm in diameter; honeycomb 5 with a thickness in the range of 24.02mm-28.02mm is distributed in the "concave" shaped area enclosed by four metal beams (two truss beams 2 and two frame beams 1).

[0066] Step 1: The lower skin 3 completes the prepreg gradient layup in a certain order and angle, and then the adhesive is laid out as a whole. The overall layup order and angle of the prepreg are as follows: [+45° / 0° / -45° / 0° / 90° / 0° / -45° / 0° / +45°]. In the middle of the overall layup, the lower skin 3 completes the thickness gradient layup, and the adhesive layup angle is 0°.

[0067] Step 2: Install frame beam 1 and truss beam 2 to the four boundary positions of the lower skin 3 completed in Step 1, with the lower surface of frame beam 1 and truss beam 2 in contact with the surface of the lower skin 3, and control the gap at the intersection of frame beam 1 and truss beam 2 to be 2.5mm;

[0068] Step 3: Within the concave area enclosed by the frame beam 1 and truss beam 2 completed in Step 2, lay honeycomb 5 in sequence, and apply adhesive to the upper surface of honeycomb 5;

[0069] Step 4: Based on the completion of Step 3, complete the gradient layup of the upper skin 4 according to the set sequence and angle to prepare a vacuum bag. It is then formed in one step in equipment such as a hot autoclave and curing oven. The overall layup sequence and angle of the upper skin 4 are as follows: [+45° / 0° / -45° / 0° / 90° / 0° / -45° / 0° / +45°]. In the middle of the overall layup, the lower skin thickness gradient layup is interspersed.

[0070] Step 5: After hot demolding, a honeycomb sandwich structure with embedded large metal beams is obtained.

[0071] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0072] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A method for forming a pre-embedded metal beam honeycomb sandwich structure, characterized in that, The embedded metal beam honeycomb sandwich structure includes: a metal beam, a lower skin (3), an upper skin (4), and a honeycomb (5). The metal beam and the honeycomb (5) are installed between the upper skin (4) and the lower skin (3), and the metal beam is located on the periphery of the honeycomb (5); The metal beams include: frame beams (1) and truss beams (2); Both the lower skin (3) and the upper skin (4) are configured as arc-shaped surface structures with the arc extending in a straight line in a direction perpendicular to the plane where the arc is located; The U-shaped frame beam (1) is installed at the arc-shaped ends of the lower skin (3) and the upper skin (4) and is adapted to the shape of the arc-shaped ends of the lower skin (3) and the upper skin (4); The straight truss (2) is installed on the straight sides of the lower skin (3) and the upper skin (4); The method includes the following steps: Step S1, the lower skin (3) completes the gradient lay-up in the set order and angle, and the adhesive is laid out as a whole; Step S2: Install the truss (2) and the frame beam (1) to the periphery of the lower skin (3) respectively. One side surface of the truss (2) and the frame beam (1) is in contact with the surface of the lower skin (3). The gap between the intersection of the truss (2) and the frame beam (1) is 1.5-3mm. Step S3: The honeycomb (5) is laid within the area enclosed by the truss (2) and the frame beam (1), and adhesive is laid on the honeycomb (5); Step S4: After completing the gradient layup of the upper skin (4) according to the set order and angle, prepare a vacuum bag and cure it in one step through a hot autoclave and curing oven; Step S5: After hot demolding, a honeycomb sandwich structure with embedded metal beams is obtained.

2. The forming method of the pre-embedded metal beam honeycomb sandwich structure according to claim 1, characterized in that: The lower skin (3) and the upper skin (4) are made of glass fiber reinforced resin matrix composite material with a thickness of 1-3 mm.

3. The forming method of the pre-embedded metal beam honeycomb sandwich structure according to claim 1, characterized in that: The truss (2) has a length greater than 3m and a width of 20-50mm, and the frame beam (1) has an arc circumference greater than 5m and a width of 20-50mm.

4. The forming method of the pre-embedded metal beam honeycomb sandwich structure according to claim 1, characterized in that: The honeycomb (5) is an aramid paper honeycomb with a paper thickness of 0.05-0.08 mm, a honeycomb (5) thickness of 20-40 mm, and a density of 48-76 kg / m³. 3 .

5. The forming method of the pre-embedded metal beam honeycomb sandwich structure according to claim 1, characterized in that: In step S4, the curing process includes an initial heating and pressing stage, a stepped segmented heating and pressing stage, and a heat preservation and pressure holding stage.

6. The forming method of the pre-embedded metal beam honeycomb sandwich structure according to claim 5, characterized in that: During the initial heating and pressurization stage, the heating temperature is 30-50℃. During the initial heating stage, the pressure inside the autoclave is increased and the auxiliary pressure inside the vacuum bag is removed. In the stepped heating and pressurization stage, the temperature is first raised to 110-120℃ and pressurized to 0.1MPa. Then, during the process of raising the temperature to 120-150℃, the pressurization is increased to 0.5MPa in stages. During the heat preservation and pressure holding stage, after holding the temperature for 1 hour, the temperature is further increased to 170-180℃, while maintaining a pressure of 0.5MPa. After holding the temperature for 4-6 hours, the temperature is lowered to 120℃ for hot demolding.

7. A fairing, characterized in that: It is prepared using the molding method of the pre-embedded metal beam honeycomb sandwich structure described in claim 1.

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