Polystyrene foam filling method for composite material honeycomb sandwich structure and honeycomb sandwich structure

Abstract

The invention discloses a polystyrene foam filling method for a composite material honeycomb sandwich structure. The method comprises the following steps: pasting adhesive isolation cloth on the surface of a process plate, and then placing a honeycomb core; the honeycomb core grids are filled with polystyrene foam; the honeycomb core grids are evenly filled with the light filler; repeating the steps until the whole honeycomb core grids are filled with the polystyrene foam and the light filler; an isolation material is placed at the upper end of the pre-filled honeycomb core, the honeycomb core is placed in a drying oven for hot pre-pressing, and pre-foaming is achieved; adhering polystyrene foam around the pre-foamed honeycomb core, and connecting the pre-foamed honeycomb core with the main body honeycomb core in an embedded manner; mounting an upper panel and a lower panel on the honeycomb core, packaging by using a vacuum bag, and putting into an autoclave for co-curing; and after curing is completed, taking out the honeycomb core from the autoclave, and demolding. The honeycomb sandwich structure prepared through the method is light in weight, the plane compression plane shear strength of the honeycomb sandwich structure is equivalent, the forming quality is good, the production efficiency is high, and the product weight control is stable.

Description

Technical Field

[0001] This invention relates to a method for filling a composite honeycomb sandwich structure with foam and the honeycomb sandwich structure itself, belonging to the field of aerospace materials technology. Background Technology

[0002] The aerospace manufacturing industry is entering a phase of rapid development. The construction of large-scale commercial satellites, exemplified by a certain internet constellation, is accelerating. Simultaneously, the construction of next-generation global satellite navigation systems, globally covered satellite mobile communication systems, and integrated element observation systems is gradually unfolding, significantly increasing the demand for the development of various spacecraft products. Faced with the rapidly increasing production capacity demands and the requirement for high-quality, high-strength, and stable large-scale satellite structures, the need for lightweight composite material components for satellites is becoming increasingly urgent. As a crucial component of satellites, honeycomb sandwich panels are particularly affected by the surge in demand, shortened development time, increased overall satellite structural load-bearing ratio, and increasingly prominent contradictions regarding structural strength requirements. By employing a low-density, lightweight filler hybrid filling process, the weight of the foam filling in honeycomb sandwich panels can be controlled. This not only reduces the weight of the satellite structure but also improves the efficiency of foam filling, providing technical support for the commercialization and large-scale production of honeycomb sandwich structures.

[0003] Currently, the commonly used method for filling honeycomb sandwich panels with expanding foam mainly involves manually cutting expanding foam strips to match the height of the honeycomb core cells. These strips are then manually filled one by one into the honeycomb core cells to achieve localized reinforcement of the honeycomb sandwich panel. Controlling the cutting dimensions of the expanding foam is difficult, resulting in poor product weight consistency. The efficiency of filling each foam strip individually is low, leading to long manufacturing cycles and high labor costs. Summary of the Invention

[0004] The purpose of this invention is to overcome the above-mentioned defects and provide a method for filling honeycomb sandwich structures with foam in composite materials, as well as the honeycomb sandwich structure itself. This solves the technical problems of existing foam filling methods, such as difficulty in controlling weight stability, large weight gain due to foam filling, and low production efficiency. The honeycomb sandwich structure prepared by the method of this invention is lightweight, and the planar compression and shear strength of the honeycomb sandwich structure are comparable, resulting in good molding quality, high production efficiency, and stable product weight control.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A method for filling a composite honeycomb sandwich structure with foam adhesive includes: S1 After attaching adhesive-coated isolation cloth to the surface of the process board, place the honeycomb core; S2 fills the honeycomb core with expanding foam; S3 fills the honeycomb core cell with lightweight filler evenly, with the lightweight filler positioned above the foam. S4 Repeat steps S2 and S3 until the foam and lightweight filler fill the entire honeycomb cell, completing the pre-filling of the honeycomb core; S5 places the insulating material on the top of the pre-filled honeycomb core and puts it in an oven for hot pre-pressing to achieve pre-foaming of the foaming adhesive; S6 cuts the pre-foamed honeycomb core to the required size, attaches foaming adhesive around the pre-foamed honeycomb core, and then embeds the pre-foamed honeycomb core with the main honeycomb core. After installing the top and bottom panels on the interlocked honeycomb core, S7 seals it in a vacuum bag and places it in an autoclave for co-curing. After S8 curing is complete, the honeycomb core with the top and bottom panels installed is removed from the autoclave and demolded.

[0006] Furthermore, in step S2, the expanding foam is expanding foam granules or cut expanding foam film.

[0007] Furthermore, in step S2, the foaming adhesive is J47 or J-78 foaming adhesive produced by the Petrochemical Research Institute of the Heilongjiang Academy of Sciences.

[0008] Furthermore, in step S2, when the foaming adhesive is a foaming film, the cutting dimensions of the foaming film are determined according to the external dimensions of the honeycomb core. The specific method is as follows: Lay the foam film flat on the surface of the process board, place the honeycomb core on the surface of the foam film, and ensure that the honeycomb core wall penetrates the foam film.

[0009] Furthermore, in step S2, when the expanding foam is in granular form, the particle size of the expanding foam granules is determined according to the specifications and dimensions of the honeycomb core. The specific method is as follows:

[0010] in, The diameter of the expanding foam particles, L For the length of the honeycomb core wall, =0.5~2.

[0011] proportionality coefficient The preferred ratio is 2 / 3, but this can be adjusted according to the actual situation.

[0012] Furthermore, in step S3, the external dimensions D2 of the lightweight filler are related to the length of the honeycomb core wall. L The relationship is as follows: .

[0013] Furthermore, in step S3, the lightweight filler includes one or more of glass beads or fibers.

[0014] Furthermore, in step S6, cutting the pre-foamed honeycomb core to the required dimensions includes: Depending on the application requirements, localized or full-board reinforcement with foam can be applied.

[0015] A honeycomb sandwich structure is obtained by the above-mentioned composite honeycomb sandwich structure foam filling method.

[0016] Compared with the prior art, the present invention has at least one of the following advantages: (1) This invention provides a novel form of foam filling, which fills the technical gap in the mass filling of foam. It can meet the requirements of its structural performance indicators, greatly improve production efficiency and reduce manufacturing costs, and can be used in the aerospace field. (2) The foam filling method of the present invention uses lightweight filler, which not only provides support for the foam after foaming, but also further reduces the foam density. The overall strength of the structural board is consistent with the traditional filling method, providing an effective solution for overall weight reduction. (3) The method of the present invention has achieved a breakthrough in the pre-foaming technology of foamed adhesive, ensuring that the foamed adhesive can effectively climb and achieve effective filling of the foamed adhesive, and can realize the productization of foamed adhesive pre-filled blanks to strengthen the honeycomb core. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the lightweight filling foam of the honeycomb sandwich structure of the composite material of the present invention; Figure 2 This is a schematic diagram of the pre-foaming encapsulation of the composite honeycomb sandwich structure filled with expanding foam according to the present invention. Detailed Implementation

[0018] The features and advantages of the present invention will become clearer and more explicit from the following detailed description.

[0019] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments. Although various aspects of embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless specifically indicated otherwise.

[0020] With a deeper understanding of the properties of composite materials, structural design schemes tailored to the characteristics of composite materials are now widely adopted. A lightweight foam filling method has been developed for the foam filling process of honeycomb sandwich structural panels, significantly reducing production costs and development cycles. This facilitates the commercialization and large-scale production of composite honeycomb sandwich structural products, resulting in products with low foam density, high structural strength, good weight consistency, and short production cycles. This offers unparalleled advantages for lightweight and economical satellite products.

[0021] The lightweight filling process of expanded polystyrene foam refers to the alternating filling of expanded polystyrene foam granules and lightweight fillers into the inner cavity of a honeycomb core. Through a high-temperature curing process, the expanded polystyrene foam foams and bonds with the honeycomb core and lightweight fillers, achieving rapid lightweight filling. Since the size and configuration of the lightweight filler are related to the specifications of the aluminum honeycomb core (mainly the length of the core wall), and the number of alternating layers is related to the height of the honeycomb core, the uniformity of the expanded polystyrene foam granules and lightweight fillers, as well as the dimensional matching between the lightweight fillers and the honeycomb core, are the key and challenging aspects of weight and quality control for expanded polystyrene foam products in structural panels.

[0022] In one specific embodiment, the lightweight filling method of composite honeycomb sandwich structure foam of the present invention is implemented according to the following steps.

[0023] Step 1: After attaching adhesive-coated isolation cloth to the surface of the process board, place the honeycomb core.

[0024] Step 2: Cut the honeycomb core film to the appropriate size according to its shape, or select the specified size of expanding foam granules according to the specifications of the honeycomb core, and fill them evenly into the honeycomb core cells.

[0025] Step 3: After cleaning and drying the surface of the lightweight filler, weigh it as needed and fill it evenly into the honeycomb core cells, ensuring that each honeycomb core cell contains lightweight filler.

[0026] Step 4: Repeat steps 2 and 3 above until the entire honeycomb cell is filled. Step 5: Place the insulating material (used to separate the foam from the sealing bag and prevent the foam from overflowing out of the honeycomb core) on the top of the pre-filled honeycomb core and place it in the oven for hot pre-pressing to achieve pre-foaming of the foam. Step Six: After removing the insulating material, cut the pre-foamed honeycomb core to the required size. Apply an appropriate amount of expanding foam around the honeycomb core and then embed the pre-foamed honeycomb core to the main honeycomb core. The purpose of this step is to modularize the pre-foamed honeycomb core. Depending on actual needs, the pre-foamed honeycomb core can be cut to the required size and embedded into a specific area of ​​the main honeycomb core that requires reinforcement. Alternatively, Step Seven can be performed on the entire pre-foamed honeycomb core. Step 7: After installing the honeycomb core onto the top and bottom panels, seal it in a vacuum bag and place it in an autoclave for co-curing.

[0027] Step 8: After curing, remove the structural panel from the autoclave and demold it.

[0028] Step 9: Inspect the appearance of the honeycomb sandwich structure panel after demolding, weigh it, and perform non-destructive testing.

[0029] The foaming adhesive in step one refers to the J47 and J-78 brands of foaming adhesive produced by the Petrochemical Research Institute of the Heilongjiang Academy of Sciences, but is not limited to the J47 and J-78 brands of foaming adhesive produced by the Petrochemical Research Institute of the Heilongjiang Academy of Sciences.

[0030] The foam filling method in step one is not limited by the size of the foam film, the form of the foam, or the grade of the foam.

[0031] The expanded polyurethane foam granules obtained in step two can be obtained by cutting or preforming expanded polyurethane foam film, and the specific filling size must match the specifications of the honeycomb core. The uniform filling method in step two requires that there be no excess material, and that the honeycomb core is not damaged or unstable during the filling process. A single-sided adhesive release cloth should be pasted on the contact surface between the honeycomb core and the curing board.

[0032] In step three, the lightweight filler must be matched with the honeycomb lattice specifications, and the filler size must be smaller than the inner cavity size of the honeycomb lattice; during the filling process, the filler should be prevented from squeezing the honeycomb lattice.

[0033] The lightweight filler in step three includes, but is not limited to, materials such as glass beads and fibers.

[0034] Step five involves heating and pre-foaming, which is then sealed in a vacuum bag. Once the insulation is complete, the pre-foaming is finished.

[0035] Step six, cutting the honeycomb core, refers to flexibly adjusting the foam reinforcement method according to usage requirements, either by locally reinforcing with foam or by reinforcing the entire board with foam.

[0036] Step 6: Seal the honeycomb sandwich structure panel in a vacuum bag, pressurize and cure it in an autoclave, and begin to pressurize in stages until curing is complete.

[0037] The demolding of the honeycomb sandwich structure panel in step seven is carried out after the mold has cooled down.

[0038] Example: Figure 1 This is a schematic diagram of a composite material honeycomb sandwich structure with lightweight foam filling and foam particles filling according to the present invention. Adhesive-backed release fabric 8 is adhered to the surface of process board 9, and the honeycomb structure is placed on the surface of the process board.

[0039] According to the specifications of the honeycomb core 1, foam granules 2 of a specified size are made and evenly filled into the honeycomb core cells.

[0040] After cleaning and drying the surface of the lightweight filler 3, weigh it as needed and fill it evenly into the honeycomb core cell, ensuring that each honeycomb core cell contains the filler.

[0041] Repeat the above steps until the entire honeycomb cell is filled.

[0042] Place the insulating material on the top of the pre-filled honeycomb core and put it in an oven for hot pre-pressing to achieve pre-foaming of the foaming adhesive.

[0043] Figure 2 The lightweight filler shown is uniformly filled into the honeycomb core. To ensure uniform filling, lightweight filler that meets the dimensional requirements must be used according to the length of the honeycomb core wall. Lightweight filling is achieved through layer-by-layer filling, with different numbers of filling layers matched to the height of the honeycomb core. After the foam filling is completed, panels 4 are placed on the upper and lower surfaces of the honeycomb core. Each layer of insulating material is placed as shown in the figure, and the core is sealed using breathable fluoropolymer cloth 7, breathable felt 6, and a vacuum bag 5. A sealing strip 10 is used to bond the vacuum bag 5 to the curing platform 11, and the entire structure is cured and formed.

[0044] After curing, the structural panel is removed from the autoclave and demolded.

[0045] Inspect the appearance of the honeycomb sandwich structure panel after demolding, weigh it, and perform non-destructive testing.

[0046] Figure 1 This is a schematic diagram of lightweight foam filling for a composite honeycomb sandwich structure. The diagram shows how, after curing, the foam is ensured to completely fill the honeycomb core, enhancing the structural strength of the composite honeycomb sandwich structure.

[0047] Example 1: The foamed film used in this embodiment is J-47D 1mm thick foamed film developed by the Petrochemical Research Institute of Heilongjiang Academy of Sciences; the lightweight filler is made of glass fiber reinforced PP material, which is resistant to 160℃ and meets the curing temperature requirement of 120℃ for J47.

[0048] This embodiment uses J-47D expanding foam as an example. After full foaming, its density is approximately 0.8-1.2 g / cm³. 3 By using shell-type low-density lightweight fillers (such as polypropylene (PP), with a density of 0.89-0.91 g / cm³), 3 By designing the configuration as a shell, the density of lightweight fillers can be reduced to 0.3-0.5 g / cm³. 3 It can not only effectively reduce the density of the foam filling area, but also achieve the stability of the foam filling, thus achieving efficient and high-quality filling.

[0049] The lightweight filler used in this embodiment adopts a hollow porous shell structure, and lightweight fillers of different diameters are used to match the honeycomb core specifications of different sizes.

[0050] The lightweight filler used in this embodiment adopts a hollow porous shell structure, and the number of alternating layers of foamed rubber particles and lightweight filler is calculated according to the height of the honeycomb core.

[0051] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0052] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A method for filling a composite honeycomb sandwich structure with expanding foam, characterized in that, include: S1 After attaching adhesive-coated isolation cloth to the surface of the process board, place the honeycomb core; S2 fills the honeycomb core with expanding foam; S3 fills the honeycomb core cell with lightweight filler evenly, with the lightweight filler positioned above the foam. S4 Repeat steps S2 and S3 until the foam and lightweight filler fill the entire honeycomb cell, completing the pre-filling of the honeycomb core; S5 places the insulating material on the top of the pre-filled honeycomb core and puts it in an oven for hot pre-pressing to achieve pre-foaming of the foaming adhesive; S6 cuts the pre-foamed honeycomb core to the required size, attaches foaming adhesive around the pre-foamed honeycomb core, and then embeds the pre-foamed honeycomb core with the main honeycomb core. After installing the top and bottom panels on the interlocked honeycomb core, S7 seals it in a vacuum bag and places it in an autoclave for co-curing. After S8 curing is complete, the honeycomb core with the top and bottom panels installed is removed from the autoclave and demolded.

2. The method for filling foamed adhesive in a composite honeycomb sandwich structure according to claim 1, characterized in that, In step S2, the expanding foam is either expanding foam granules or cut expanding foam film.

3. The method for filling foamed adhesive in a composite honeycomb sandwich structure according to claim 1, characterized in that, In step S2, the foaming adhesive is J47 or J-78 foaming adhesive produced by the Petrochemical Research Institute of Heilongjiang Academy of Sciences.

4. The method for filling foamed adhesive in a composite honeycomb sandwich structure according to claim 2, characterized in that, In step S2, when the expanding foam is a foam film, the cutting dimensions of the foam film are determined according to the external dimensions of the honeycomb core. The specific method is as follows: Lay the foam film flat on the surface of the process board, place the honeycomb core on the surface of the foam film, and ensure that the honeycomb core wall penetrates the foam film.

5. The method for filling foamed adhesive in a composite honeycomb sandwich structure according to claim 2, characterized in that, In step S2, when the expanding foam is in granular form, the particle size of the expanding foam granules is determined according to the specifications and dimensions of the honeycomb core. The specific method is as follows: in, The diameter of the expanding foam particles, L For the length of the honeycomb core wall, =0.5~2.

6. The method for filling foamed adhesive in a composite honeycomb sandwich structure according to claim 1, characterized in that, In step S3, the external dimensions D2 of the lightweight filler and the length of the honeycomb core wall are... L The relationship is as follows: 。 7. The method for filling foamed adhesive in a composite honeycomb sandwich structure according to claim 1, characterized in that, In step S3, the lightweight filler includes one or more of glass beads or fibers.

8. The method for filling foam in a composite honeycomb sandwich structure according to claim 1, characterized in that, In step S6, cutting the pre-foamed honeycomb core to the required dimensions includes: Depending on the application requirements, localized or full-board reinforcement with foam can be applied.

9. A honeycomb sandwich structure, characterized in that, The composite honeycomb sandwich structure is obtained by the foam filling method according to any one of claims 1-8.

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