A large flat panel antenna radome anti-warping forming method

Abstract

The application provides a large flat antenna cover anti-warping deformation forming method, comprising a mold which is a rectangular frame, and the specific steps are as follows: step one, laying a front skin in the mold, then bonding the horizontal lower end surface of an L-shaped reinforcing part to the front skin, aligning the vertical end outer wall of the L-shaped reinforcing part with the surrounding frame of the mold, and laying a paper honeycomb with steps around the front skin; step two, filling the filling glue in the paper honeycomb around the skin turn-up area; step three, after the filling is completed, covering a dustproof sheet, standing still at room temperature for at least 4 hours, taking out the dustproof sheet, and scraping off the excess filling glue; step four, putting the honeycomb product with the excess filling glue scraped off in step three into an oven for heating at 55 DEG C under vacuum for at least 2 hours, and cooling to room temperature after the filling glue in the honeycomb product is completely solidified; the application greatly improves the forming efficiency of the product under the condition of ensuring that the product is not warped and deformed, and the structure of the application is relatively simple, and the forming mode is relatively simple.

Description

Technical Field

[0001] The invention belongs to the field of composite materials, and in particular relates to a method for forming a large flat antenna cover to prevent warping and deformation. Background Art

[0002] Usually, large flat antenna covers usually adopt A sandwich structure (a layer of honeycomb is sandwiched between the front and rear skins) or C sandwich structure (two layers of honeycomb are sandwiched between the front, middle and rear skins). For the convenience of explanation, the A sandwich structure is used for explanation. Figure 1 As shown in the figure, this structure is a typical flat antenna cover honeycomb sandwich reinforced structure. The usual molding method is to first lay the front skin and rear skin with reinforced flanges on the mold, and then lay the machine-added stepped aramid honeycomb in the front skin after molding, and fill the honeycomb filling glue in a certain area around the honeycomb in line with the skin flange to strengthen the overall stiffness and flange strength of the product. When the honeycomb filling glue is basically cured, the rear skin with adhesive film is laid on the paper honeycomb filled with honeycomb filling glue, and the vacuum bag is sealed and evacuated, and then the product is put into the autoclave for heating and pressurization to complete the molding process. The products produced by this process are often prone to warping and deformation, especially for large flat antenna covers with C sandwich.

[0003] Anything larger than 1m*1m, or with a single side exceeding 1 meter, is considered a large flat-panel antenna cover, including 2m*0.5m. As long as the single-side span is too large, and the honeycomb sandwich structure and honeycomb filling glue-reinforced products are not properly handled, warping will basically occur. The larger the size, the more serious the warping.

[0004] In order to ensure sufficient strength and rigidity, large flat antenna covers often need to be reinforced with local skin and honeycomb filling glue around the flat antenna covers. Figure 1 As shown, the product molding process requires step-by-step heating and pressure molding in an autoclave. This often results in internal stresses caused by the heat, leading to warping in the final product. This is particularly noticeable in large flat-panel radomes, resulting in product scrap and significant cost waste. To address this issue, the inventor's organization, through technical research and experimental verification, has developed an effective method for preventing warping in large flat-panel radomes. This method has been widely adopted within the organization. Summary of the Invention

[0005] In order to overcome the problem that existing honeycomb products need to be heated and pressurized in steps in an autoclave during the molding process, which often causes internal stress to be generated due to internal heat, the present invention provides a large flat antenna cover anti-warping deformation molding method. The present invention prevents the product from suffering obvious warping deformation during the autoclave molding process by controlling the curing process of the honeycomb filling glue and the skin reinforcement structure.

[0006] The technical solution adopted in the present invention is:

[0007] A large flat antenna radome anti-warping forming method, comprising a mold, the mold is a rectangular frame, the specific steps are:

[0008] Step one, the front skin is laid in the mold, then the L-shaped reinforcing part is adhered to the lower horizontal end surface of the front skin, and the outer wall of the vertical end of the L-shaped reinforcing part is aligned with the surrounding frame of the mold, and then the paper honeycomb with steps around the front skin is laid;

[0009] Step two, fill the filling glue in the paper honeycomb around the skin turn-up area;

[0010] Step three, after filling, cover the dustproof sheet and stand still at room temperature for at least 4 hours, then take out the dustproof sheet and scrape off the excess filling glue;

[0011] Step four, the honeycomb product scraped of the excess filling glue in step three is put into the oven at 55℃ under vacuum state for at least 2 hours, and after the filling glue in the honeycomb product is completely solidified, it is cooled to room temperature;

[0012] Step five, lay the prepreg on the step surface of the paper honeycomb, so that the upper step surface of the paper honeycomb with steps is flush with the upper edge of the L-shaped reinforcing part;

[0013] Step six, lay the back skin on the paper honeycomb filled with filling glue, seal the vacuum bag, then vacuumize, and then put into the hot press tank for heating and pressurizing, after the honeycomb product is completely solidified, take out the hot press tank and demold, and complete the forming process.

[0014] The front skin and the L-shaped reinforcing part are two parts, and the specific manufacturing process is that the front skin and the L-shaped reinforcing part are simultaneously laid and formed in the same mold, and the two are separated by a separation fabric, and when the molding is completed and demolded, the separation fabric is removed and the two are directly separated into two parts.

[0015] The separation fabric is a separation cloth or a nylon cloth.

[0016] The paper honeycomb is an aramid honeycomb.

[0017] The L-shaped reinforcing part is an L-shaped four-edge frame, and the L-shaped reinforcing part comprises a horizontal end and a vertical end, the upper surface of the horizontal end is in contact with the lower surface of the step of the paper honeycomb; and the lower surface of the horizontal end is adhered to the front skin.

[0018] In step two, the volume of the filling glue filled is 80-90% of the theoretical volume of the pores in the paper honeycomb.

[0019] The filling glue contains glass bead powder with a mass ratio of 3-10%.

[0020] The filling glue is TY303 honeycomb filling glue.

[0021] The dustproof sheet is glass paper.

[0022] The isolation fabric is resistant to temperature of at least 150 DEG C

[0023] The present application has the following advantages:

[0024] In the present application, the original reinforced flanged front skin is split into a separate front skin and an L-shaped reinforcing member, then the L-shaped reinforcing member is pre-bonded to the front skin after the lower end surface is pasted with a film, and the other side is aligned with the mold frame, so that the entire bottom structure is completed, and the connection between the front skin and the L-shaped reinforcing member will not be warped after heating and pressing.

[0025] The present application adds glass bead powder in the filling glue, so that the filling glue filled with glass bead powder will expand by 10-20% after heating, which ensures that the filled filling glue reduces the weight under the conditions of the overall stiffness of the reinforced honeycomb product and the flange strength. The present application prevents the product from being significantly warped and deformed during the heat pressing tank forming process by controlling the curing process of the honeycomb filling glue and the split of the skin and the L-shaped reinforcing structure.

[0026] After the filling glue is filled, the dustproof sheet is covered, effectively isolating dust and ensuring that the honeycomb product will not accumulate dust.

[0027] The present application solves the problem of warping deformation of large flat antenna covers; the present application greatly improves the forming efficiency of the product under the condition of ensuring that the product is not warped and deformed; the structure of the present application is relatively simple, and the forming method is relatively simple.

[0028] The following will be further described with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a typical flat antenna cover honeycomb sandwich reinforcing structure.

[0030] Figure 2 is a large flat antenna cover anti-warping deformation structure schematic diagram provided by the present application.

[0031] Figure 3 is a large flat antenna cover anti-warping deformation honeycomb product structure schematic diagram of the present application.

[0032] Figure 4 is Figure 3 is a cross-sectional view of a right angle of a medium-sized flat antenna cover anti-warping deformation honeycomb product.

[0033] Figure 5 is a local enlarged view of A in the figure.

[0034] In the figure, the reference signs are: 1-paper honeycomb, 2-filling glue, 3-back skin, 4-film, 5-prepreg, 6-front skin, 7-L-shaped reinforcement. DETAILED DESCRIPTION

[0035] Example 1:

[0036] The application will be described in detail below in combination with the drawings and specific embodiments.

[0037] In order to overcome the problem that the existing honeycomb product needs to be heated and pressurized in steps in a hot press tank during the forming process, and the internal stress generated by internal heating often causes the final product to warp and deform, the application provides a large flat antenna cover anti-warping forming method as shown in Figure 2 The application prevents the product from being significantly warped and deformed during the hot press tank forming process by controlling the honeycomb filling glue solidification process and the skin reinforcement structure.

[0038] A large flat antenna cover anti-warping forming method, comprising a mold, the mold is a rectangular frame, the specific steps are:

[0039] Step one, lay the front skin 6 in the mold, then bond the horizontal lower end face of the L-shaped reinforcement 7 to the front skin 6, align the vertical end outer wall of the L-shaped reinforcement 7 with the surrounding frame of the mold, and then lay the paper honeycomb 1 with a stepped periphery in the front skin 6;

[0040] Step two, fill the filling glue 2 in the skin turn-up area around the paper honeycomb 1;

[0041] Step three, after filling, cover the dustproof sheet and stand still at room temperature for at least 4 hours, then remove the dustproof sheet and scrape off the excess filling glue 2;

[0042] Step four, put the honeycomb product with the excess filling glue scraped off in step three into an oven at 55°C under vacuum for at least 2 hours, and then cool to room temperature after the filling glue 2 in the honeycomb product is completely solidified;

[0043] Step five, lay the prepreg 5 on the stepped surface of the paper honeycomb 1, so that the upper stepped surface of the paper honeycomb 1 with a stepped surface is flush with the upper edge of the L-shaped reinforcement 7;

[0044] Step six, lay the back skin 3 on the paper honeycomb 1 filled with the filling glue 2, seal the vacuum bag, then vacuumize, and then put it into a hot press tank for heating and pressurizing, and then take it out of the hot press tank and demold after the honeycomb product is completely solidified, to complete the forming process.

[0045] In the application, the transmission length and the expected thickness of the prepreg 5 are set according to design requirements, such as Figure 2 and Figure 5As shown, the laying range of the prepreg 5 is symmetrical to the horizontal end of the L-shaped reinforcement 7.

[0046] The present invention has obtained the anti-warping deformation method after repeated experiments. In the design, the front skin 6 with the original reinforced flange is split into a separate front skin 6 and an L-shaped reinforcement 7. Figure 2 In the present invention, the front skin 6 is laid in a treated mold, and then the lower end surface of the L-shaped reinforcement 7 is adhered with a film 4 and pre-bonded to the front skin 6, and the other side is aligned with the mold frame. Then, a paper honeycomb 1 with a step added in advance is laid in the front skin 6; 3-10% by mass of glass bead powder is added to the filling glue 2 and thoroughly mixed with the filling glue 2. After mixing, the mixed filling glue 2 is filled in a certain area around the paper honeycomb 1 that is in contact with the skin flange; after filling, a dustproof sheet is covered and the product is left to stand at room temperature for 4 hours, and then the excess filling glue 2 is scraped off; the honeycomb product with the excess filling glue scraped off is placed in an oven under vacuum and heated at 55°C for 2 hours. After the filling glue of the honeycomb product is completely cured, it is cooled to room temperature; the rear skin 3 with the adhesive film 4 is laid and bonded to the paper honeycomb 1 filled with the honeycomb filling glue, and the product is sealed in a vacuum bag and vacuumed, and then placed in an autoclave for heating and pressurization. After the product is completely cured, it is removed from the autoclave and demolded, completing the molding process. The final product will not warp or deform because the stress is released after the structure is split and fully solidified in advance.

[0047] The filler in the present invention is required to be able to withstand medium-temperature curing conditions without failure and have a low expansion coefficient within 60°C. The present invention prevents significant warping and deformation of the product during the autoclave molding process by controlling the curing process of the honeycomb filler and the skin reinforcement structure.

[0048] Example 2:

[0049] Based on Example 1, in this embodiment, preferably, the front skin 6 and the L-shaped reinforcement 7 are two parts, and the specific production process is: the front skin 6 and the L-shaped reinforcement 7 are laid and formed at the same time in the same mold, and the two are separated by an isolation fabric. When the molding is completed and the mold is demolded, the isolation fabric is removed and the two are directly separated into two parts.

[0050] The method provided by the present invention first forms the front skin 6 and the L-shaped reinforcement 7 during molding. The front skin 6 and the L-shaped reinforcement 7 can be laid and molded at the same time in the same mold, and the two are separated by an isolation fabric. When the molding is completed and the mold is released, the two can be directly separated into two parts; then subsequent laying operations are carried out.

[0051] Preferably, the isolation fabric is isolation cloth or nylon cloth.

[0052] Preferably, the insulation fabric is temperature-resistant to at least 150°C.

[0053] In the present application, the isolation fabric needs to meet the conditions of high temperature resistance and not to be bonded or not to be easily separated from the front skin 6 and the L-shaped reinforcing member 7. In the present application, the isolation fabric is resistant to temperature of at least 150 DEG C, so as to ensure that the front skin 6 and the L-shaped reinforcing member 7 cannot be separated into two independent parts due to the temperature problem when the front skin 6 and the L-shaped reinforcing member 7 are formed.

[0054] Preferably, the paper honeycomb 1 is aramid honeycomb.

[0055] In the present application, the paper honeycomb 1 is preferably aramid honeycomb, and the aramid honeycomb core can be combined with carbon fiber prepreg, glass fiber prepreg, metal plate and the like to form composite materials of various thicknesses and shapes. The main uses include aerospace, ships, high-speed rail, sports goods and military fields, and the application fields are wide and the applicability is strong.

[0056] Preferably, the L-shaped reinforcing member 7 is an L-shaped four-side frame, and the L-shaped reinforcing member 7 comprises a horizontal end and a vertical end, the upper surface of the horizontal end is in contact with the lower surface of the step of the paper honeycomb 1, and the lower surface of the horizontal end is bonded to the front skin 6.

[0057] In the present application, the horizontal end of the L-shaped reinforcing member 7 is a four-side frame, and the height of the vertical end matches the height of the corresponding placed paper honeycomb 1, so as to ensure that the final honeycomb product is flat and does not have edge curling.

[0058] Preferably, in step two, the volume of the filling glue 2 is 80-90% of the theoretical volume of the pores in the paper honeycomb 1.

[0059] In the present application, the filling glue 2 mixed with the glass bead powder has a filling volume of 80-90% of the theoretical volume of the pores of the paper honeycomb 1. This ensures that after expansion, the paper honeycomb 1 will not be damaged, and the material is saved, and the cost is reduced. After expansion, it can fill the pores of the paper honeycomb 1 as required, and ensure the strength of the paper honeycomb 1.

[0060] Preferably, the filling glue 2 contains glass bead powder in a mass ratio of 3-10%.

[0061] In the present application, the amount of glass bead powder is determined according to the requirements, and in the present application, the mass ratio of the filling glue 2 is preferably 4%, 5%, 6%, 7%, 8%, 9%.

[0062] In the present application, the mixing of the glass bead powder can reduce the overall weight of the filling glue 2, and the filling glue 2 containing the glass bead powder can be expanded in the pores of the paper honeycomb 1, and the volume can be increased by 10-20% after expansion, so as to ensure that the filling amount of the paper honeycomb 1 is sufficient. In the present application, the filling glue 2 is preferably TY303 honeycomb filling glue. The filling glue 2 is a mature technology and can be directly purchased in the market, and the present application will not be further described.

[0063] Preferably, the dustproof sheet in step three is glass paper.

[0064] In the present application, the dustproof sheet ensures that the paper honeycomb 1 after filling will not fall dust, and the material used is easy to remove, which can ensure that it can prevent dust and dirt.

[0065] As shown in Figure 3 and Figure 4 , the anti-warping method verified by repeated experiments in the present application splits the original front skin 6 with reinforced flange into separate front skin 6 and L-shaped reinforcement 7 during design, as shown in Figure 2 ; the method provided by the present application first forms the front skin 6 and the reinforcement 7 during molding, and the front skin 6 and the L-shaped reinforcement 7 can be simultaneously laid and molded in the same mold, separated by a separation fabric in the middle, and separated into two parts when demolded after molding; then subsequent laying operations are performed. In the present application, the front skin 6 is laid in the treated mold, the L-shaped reinforcement 7 is pre-bonded to the front skin 6 after the lower end surface is pasted with the adhesive film 4, and the other side is aligned with the mold frame, and the paper honeycomb 1 with a stepped structure is laid in the front skin 6; 3-10% of glass bead powder by mass is added to the filling glue 2, and the filling glue 2 is fully mixed, and after mixing, the mixed filling glue 2 is filled in the area of the skin flange around the paper honeycomb 1; in the present application, mixing the glass bead powder can reduce the overall weight of the filling glue 2, and the glass bead powder filled in the filling glue 2 can expand in the pores of the paper honeycomb 1, and the expansion volume can be increased by 10-20%, which ensures that the filling amount of the paper honeycomb 1 is sufficient. In the present application, the filling volume of the filling glue 2 mixed with the glass bead powder is 80-90% of the theoretical pore volume of the paper honeycomb 1. In this way, after expansion, it will not cause damage to the paper honeycomb 1, and it also saves materials and reduces costs. After filling, cover the dustproof sheet and stand at room temperature for 4 hours, then scrape off the excess filling glue 2; the honeycomb product after scraping off the excess filling glue is put into an oven at 55°C under vacuum state for 2 hours, and after the filling glue of the honeycomb product is completely cured, it is cooled to room temperature; the rear skin 3 with adhesive film 4 is laid on the paper honeycomb 1 filled with filling glue, and after vacuumizing, it is put into a hot press for heating and pressing, and after the product is completely cured, it is taken out of the hot press and demolded, and the molding process is completed. The final product releases stress after the structure is split and completely cured in advance, and the final product will not appear warp deformation.

[0066] In the present application, the front skin 6 and the L-shaped reinforcement 7 are bonded by the adhesive film 4, and the rear skin 3 with adhesive film 4 is laid on the paper honeycomb 1 filled with filling glue. In this way, separate bonding ensures that the honeycomb product will not warp after heating and pressing. In this way, under the condition of heating and pressing, the overall honeycomb product will not deform and collapse. It ensures the integrity and pressure resistance of the honeycomb product.

[0067] The above examples are only illustrative of the present application and do not constitute a limitation to the scope of protection of the present application. Any design identical or similar to the present application falls within the scope of protection of the present application. The device structure and method steps not described in detail in the present application are prior art and will not be further described in the present application.

Claims

1. A method for forming a large flat antenna cover to prevent warping and deformation, comprising a mold, wherein the mold is in the shape of a rectangular frame and is characterized by: The specific steps are: Step 1: Lay the front skin (6) in the mold, then bond the horizontal lower end surface of the L-shaped reinforcement (7) to the front skin (6), and align the vertical end outer wall of the L-shaped reinforcement (7) with the mold frame, and then lay a paper honeycomb (1) with steps on all sides in the front skin (6); the front skin (6) and the L-shaped reinforcement (7) are two parts, and the specific manufacturing process is: lay the front skin (6) and the L-shaped reinforcement (7) in the same mold at the same time, separate the two with isolation fabric, and when demolding is completed, remove the isolation fabric and separate the two directly into two parts; Step 2: Filling the paper honeycomb (1) with a filling glue (2) in the area adjacent to the skin flange. The volume of the filling glue (2) is 80-90% of the theoretical volume of the pores in the paper honeycomb (1). Step 3: After filling, cover with a dustproof sheet and let it stand at room temperature for at least 4 hours, then remove the dustproof sheet and scrape off the excess filling glue (2); Step 4: The honeycomb product from which the excess filling glue was scraped off in step 3 is placed in a vacuum oven and heated at 55°C for at least 2 hours. After the filling glue (2) in the honeycomb product is completely solidified, it is cooled to room temperature. Step 5: laying the prepreg (5) on the stepped surface of the paper honeycomb (1) so that the upper stepped surface of the stepped paper honeycomb (1) is flush with the upper edge of the L-shaped reinforcement (7); Step six, the rear skin (3) is laid and glued on the paper honeycomb (1) filled with the filling glue (2), the vacuum bag is sealed and vacuumed, and then the honeycomb product is put into the autoclave for heating and pressurization. After the honeycomb product is completely cured, it is taken out of the autoclave and demoulded to complete the molding process; The front skin (6) and the L-shaped reinforcement (7) are bonded together by means of an adhesive film (4), and the rear skin (3) bonded with the adhesive film (4) is laid on the paper honeycomb (1) filled with honeycomb filling glue.

2. The method for preventing warping and deformation of a large flat antenna cover according to claim 1, characterized in that: The isolation fabric is isolation cloth or nylon cloth.

3. The method for preventing warping and deformation of a large flat antenna cover according to claim 1, characterized in that: The paper honeycomb (1) is an aramid honeycomb.

4. The method for preventing warping and deformation of a large flat antenna cover according to claim 1, characterized in that: The L-shaped reinforcement (7) is an L-shaped four-side frame, and the L-shaped reinforcement (7) includes a horizontal end and a vertical end, the upper surface of the horizontal end is in contact with the lower surface of the step of the paper honeycomb (1); and the lower surface of the horizontal end is bonded to the front skin (6).

5. The method for preventing warping and deformation of a large flat antenna cover according to claim 1, characterized in that: The filling glue (2) is mixed with glass microbead powder in a mass ratio of 3-10%.

6. The method for preventing warping and deformation of a large flat antenna cover according to claim 1, characterized in that: The filling glue (2) is TY303 honeycomb filling glue.

7. The method for preventing warping and deformation of a large flat antenna cover according to claim 1, characterized in that: In the step 3, the dustproof sheet is cellophane.

8. The method for preventing warping and deformation of a large flat antenna cover according to claim 2, characterized in that: The isolation fabric is temperature-resistant to at least 150°C.

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