Heat shield forming tooling, systems, and methods

Abstract

The application provides a heat shield forming tool, system and method, the heat shield forming tool comprises a coaxial inner core mold and an outer mold, the outer mold is sleeved on the inner core mold and detachably connected with the inner core mold, a gap is arranged between the inner core mold and the outer mold, the gap is used as a resin flow channel, a resin inlet is arranged at the lower end of the inner core mold, the resin inlet is communicated with the gap, and a resin outlet is arranged at the top end of the outer mold, the resin outlet is communicated with the gap. Through the detachable inner core mold and the outer mold, the fabric can be sleeved on the inner core mold first, and then the outer mold is connected with the inner core mold, so that the fabric is sleeved on the mold, the resin inlet is arranged at the lower end of the inner core mold, the resin outlet is arranged at the top end of the outer mold, the resin flows from the bottom to the top of the heat shield forming tool, the resin can permeate the whole fabric, and the product qualified rate of the heat shield is improved.

Description

Technical Field

[0001] This invention relates to the field of heat shield molding technology for aerospace applications, and specifically to a heat shield molding tooling, system, and method. Background Technology

[0002] The radome is an important component that protects the radar seeker and antenna, playing a key role in heat insulation, wave transmission and load bearing. Currently, the main material for radome manufacturing is quartz fiber reinforced composite material, and the long-term operating temperature does not exceed 1400℃.

[0003] In recent years, with the development of hypersonic weapons, the temperature that radomes must withstand has been continuously increasing. Existing materials are no longer sufficient to meet the requirements for guidance heads or antennas in high-Mach, ultra-high-temperature, and high-mobility environments. Currently, the design of radomes for usability mainly focuses on several aspects. The first is a passive approach, adding heat shields or insulation covers to the inner or outer surfaces of the radome to reduce the ambient temperature and increase its applicability. Another approach is an active approach, using high-temperature resistant materials such as nitrides and oxides, or equipping the radome with automatic cooling capabilities to improve environmental adaptability. However, challenges remain, including the difficulty in molding irregularly shaped heat shields, the inconvenience of fabric molding, high operating temperatures, and the potential health hazards of resin volatilization for workers. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a heat insulation cover molding tooling, system, and method.

[0005] To solve the above-mentioned technical problems, in a first aspect, the present invention provides a heat insulation cover molding fixture, including an inner core mold and an outer mold arranged coaxially. The outer mold is sleeved on the inner core mold and detachably connected to the inner core mold. A gap is provided between the inner core mold and the outer mold, and the gap is used as a resin flow channel. A glue inlet is opened at the lower end of the inner core mold, and the glue inlet communicates with the gap. A glue outlet is opened at the top end of the outer mold, and the glue outlet communicates with the gap.

[0006] This invention, by setting up a detachable inner core mold and an outer mold, allows the fabric to be first fitted over the inner core mold, and then the outer mold to be connected to the inner core mold, which facilitates the fabric fitting. By opening a glue inlet at the lower end of the inner core mold and a glue outlet at the top of the outer mold, the resin flows from the bottom to the top of the heat insulation cover molding fixture, ensuring that the resin permeates the entire fabric and improving the product qualification rate of the heat insulation cover.

[0007] Furthermore, the outer mold includes an upper mold, a middle mold, and a lower mold, which are arranged sequentially from the top of the inner core mold downwards. The upper mold and the middle mold are detachably connected, and the middle mold and the lower mold are detachably connected. The glue outlet is located at the top of the upper mold.

[0008] This invention facilitates disassembly and installation by setting the outer mold into an upper mold, a middle mold, and a lower mold that are detachably connected to each other.

[0009] Furthermore, the middle mold is a cylindrical structure with open ends, and the inner core mold and the upper mold are both cylindrical structures with open ends. The lower end of the upper mold is provided with a first outer edge along the outer wall. The upper and lower ends of the middle mold are provided with a second outer edge and a third outer edge along the outer wall, respectively. The lower end of the inner core mold is provided with a fourth outer edge along the outer wall. The first outer edge is connected to the second outer edge, and the third outer edge is connected to the lower mold and the fourth outer edge.

[0010] Furthermore, rubber rings for sealing are provided between the first outer edge and the second outer edge, between the third outer edge and the lower mold, and between the lower mold and the inner core mold.

[0011] This invention, by setting a rubber ring, can prevent resin from flowing out and prevent resin volatilization from causing harm to workers' health.

[0012] Furthermore, the lower mold is an annular plate structure with a feed port. One end of the feed port is connected to the gap, and the other end of the feed port is connected to the glue inlet. The inner wall of the lower mold is in close contact with the outer wall of the inner core mold. The gap extends from the upper end face of the lower mold to the top end face of the inner core mold. The cross-sectional area of ​​the feed port is smaller than the cross-sectional area of ​​the glue inlet. The lower mold is used as a demolding ejection device.

[0013] The gap of the present invention extends from the upper end face of the lower mold to the top end face of the inner core mold. After the heat insulation cover is formed, its bottom end corresponds to the upper end face of the lower mold. During the disassembly of the lower mold, the formed heat insulation cover can be ejected. It has the advantage of easy demolding for heat insulation cover products with small taper and thin product wall thickness, which helps to reduce the problem of demolding difficulties caused by the tight fit between the product and the inner core mold.

[0014] Secondly, the present invention provides a heat insulation cover molding system, comprising a pressure vessel, a glue injection tank, a heat insulation cover molding fixture, a glue storage tank, and a vacuum pump connected in sequence. The pressure vessel is used to inject resin from the glue injection tank through the glue inlet of the heat insulation cover molding fixture. The glue storage tank is connected to the glue outlet of the heat insulation cover molding fixture. The vacuum pump is used to evacuate the glue storage tank, so that the resin flows from the heat insulation cover molding fixture into the glue storage tank.

[0015] The heat shield molding system of this invention features stable and simple connection processes. By connecting multiple heat shield molding fixtures in parallel, batch molding of heat shields can be achieved. The heat shield molding system is semi-automatic, which reduces operator contact with resin and improves the working environment for workers.

[0016] Furthermore, the injection tank and heat insulation cover molding fixture are set in a drying oven, which is used to heat the resin to ensure smooth resin impregnation.

[0017] For high-temperature resistant resins such as phthalonitrile and bismaleimide resin, which have short window periods and high melting points, the present invention allows the heat insulation cover molding fixture and the glue injection tank to be set in the drying room to ensure smooth resin impregnation and ensure the impregnation process proceeds smoothly.

[0018] Furthermore, the pipes connecting the glue injection tank to the heat insulation cover molding tooling and the pipes connecting the glue storage tank to the heat insulation cover molding tooling are made of metal hoses or high-temperature resistant plastic pipes.

[0019] The glue injection tank and heat insulation cover molding fixture of the present invention are set in the drying room, and the corresponding pipelines also need to be heat resistant to prevent pipeline damage.

[0020] Thirdly, the present invention provides a method for forming a heat insulation cover, comprising:

[0021] S1. Insert the fabric into the inner core mold and install the outer mold;

[0022] S2. Heat the resin in the dispensing tank to change the resin from a solid state to a liquid state;

[0023] S3. Measure the resin viscosity. After the injection requirements are met, open the pressure vessel to pressurize the injection tank, open the valve between the injection tank and the heat insulation cover molding fixture, and the valve between the heat insulation cover molding fixture and the storage tank, and open the vacuum equipment to evacuate the storage tank, so that the resin is gradually injected from the storage tank into the heat insulation cover molding fixture containing the fabric until the resin flows out from the heat insulation cover molding fixture.

[0024] S4. After the resin in the heat insulation cover molding fixture cures, a heat insulation cover is formed. The upper mold and middle mold are removed, and the heat insulation cover is ejected using the lower mold.

[0025] The heat insulation cover molding method of the present invention is simple to operate, and the products produced by the above molding method have a high qualification rate.

[0026] Further, step S5 is included: dissolving the resin with acetone at a mass fraction of 15% to 35% and adding short-cut fibers to form a paste-like repair liquid; applying the repair liquid to the pits of the heat insulation cover for scraping and repair, followed by gradient curing.

[0027] The present invention addresses issues such as pits in the layout of the heat insulation cover by employing the above-mentioned solution to improve the product qualification rate.

[0028] The beneficial effects of the present invention are as follows: By setting a detachable inner core mold and an outer mold, the fabric can be first put on the outer core mold and then the outer mold can be connected to the inner core mold, which facilitates the fabric to be molded. By opening a glue inlet at the lower end of the inner core mold and a glue outlet at the top of the outer mold, the resin flows from the bottom to the top of the heat insulation cover molding tooling, which can ensure that the resin permeates the entire fabric and improve the product qualification rate of the heat insulation cover. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the heat insulation cover molding tooling of the present invention;

[0030] Figure 2 This is a schematic diagram of the heat insulation cover molding system of the present invention.

[0031] Reference numerals: Inner core mold 1; Gap 2; Inlet 3; Outlet 4; Upper mold 5; Middle mold 6; Lower mold 7; First outer edge 8; Second outer edge 9; Third outer edge 10; Rubber ring 11; Pressure vessel 12; Injection tank 13; Heat insulation cover molding fixture 14; Glue storage tank 15; Vacuum pump 16; Drying oven 17; Fourth outer edge 18; First gap 19; Second gap 20. Detailed Implementation

[0032] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0033] like Figure 1 As shown, this embodiment provides a heat insulation cover forming tooling 14, including an inner core mold 1 and an outer mold.

[0034] The inner core mold 1 is a cylindrical structure with an open bottom. The lower end of the inner core mold 1 is integrally formed with a fourth outer edge 18. The fourth outer edge 18 is a ring-shaped plate structure. A ring of bolt holes and two glue inlets 3 are opened on the fourth outer edge 18. The two glue inlets 3 are perpendicular to the fourth outer edge 18 and are arranged symmetrically. The two glue inlets 3 are located inside the ring of bolt holes.

[0035] The outer mold is fitted onto the inner core mold 1. The outer mold includes an upper mold 5, a middle mold 6, and a lower mold 7, arranged sequentially from the top of the inner core mold 1 downwards. The upper mold 5 is a cylindrical structure with an open lower end. The upper mold 5 fits onto the top of the inner core mold 1, and the lower end of the upper mold 5 is integrally formed with a first outer edge 8 along the outer wall. The lower mold 7 is a ring-shaped plate structure. The lower mold 7 has bolt holes corresponding to the bolt holes of the fourth outer edge 18. The lower mold 7 fits onto the inner core mold 1 near the lower end and is placed on the fourth outer edge 18. A rubber ring 11 is provided between the lower mold 7 and the fourth outer edge 18. The middle mold 6 is a cylindrical structure with open ends. The middle mold 6 fits onto the middle of the inner core mold 1. The upper and lower ends of the middle mold 6 are integrally formed with a second outer edge 9 and a third outer edge 10 along their outer walls, respectively. The second outer edge 9 is detachably connected to the first outer edge 8 by bolts, and a rubber ring 11 is provided between the second outer edge 9 and the first outer edge 8. The third outer edge 10 has bolt holes corresponding to the bolt holes of the fourth outer edge 18, thereby allowing the third outer edge 10, the lower mold 7, and the fourth outer edge 18 to be detachably connected by bolts. The rubber ring 11 is provided between the third outer edge 10 and the lower mold 7. The first outer edge 8, the second outer edge 9, and the third outer edge 10 are all annular plate structures.

[0036] The inner diameters of the upper mold 5 and the middle mold 6 are both larger than the outer diameter of the corresponding position of the inner core mold 1, thus forming a first gap 19 between the upper mold 5 and the inner core mold 1, and between the middle mold 6 and the inner core mold 1; the inner diameter of the lower mold 7 is equal to the outer diameter of the corresponding position of the inner core mold 1, so that the inner wall of the lower mold 7 fits tightly with the outer wall of the inner core mold 1; a step is provided on the lower end face of the third outer edge 10, so that a second gap 20 is formed between the middle mold 6 and the lower mold 7, and the second gap 20 and the first gap 19 together form gap 2.

[0037] The lower mold 7 has two feed ports corresponding to the glue inlet 3. The feed ports are connected to the second gap 20. The upper mold 5 has a glue outlet 4 vertically. The resin can enter the gap 2 through the glue inlet 3 and the feed port, and then flow out of the gap 2 through the glue outlet 4.

[0038] In this embodiment, the cross-sectional area of ​​the feed port is smaller than that of the glue inlet 3. The lower mold 7 can be ejected using a cylindrical pin with the same cross-section as the glue inlet 3. During the ejection of the lower mold 7, the formed heat insulation cover will also detach from the inner core mold 1. This has the advantage of easy demolding for heat insulation cover products with small taper and thin wall thickness, which helps to reduce the problem of demolding difficulties caused by the tight fit between the product and the inner core mold 1.

[0039] The upper end face of the upper mold 5 is threaded with two lifting rings, which facilitates the hoisting of the entire heat insulation cover forming fixture 14.

[0040] like Figure 2As shown, this embodiment also provides a heat insulation cover molding system, including a pressure vessel 12, a glue injection tank 13, a heat insulation cover molding fixture 14, a glue storage tank 15, and a vacuum pump 16 connected in sequence. The pressure vessel 12 is used to inject resin from the glue injection tank 13 into the glue inlet 3 of the heat insulation cover molding fixture 14. The glue storage tank 15 is connected to the glue outlet 4 of the heat insulation cover molding fixture 14. The vacuum pump 16 is used to evacuate the glue storage tank 15, so that the resin flows from the heat insulation cover molding fixture 14 into the glue storage tank 15. In this embodiment, multiple heat insulation cover molding fixtures 14 are arranged in parallel. For high-temperature resistant resins such as phthalonitrile and bismaleimide resin, which have short window periods and high melting points, the glue injection tank 13 and the heat insulation cover molding fixture 14 are arranged in a drying oven 17 to ensure smooth resin impregnation. The drying oven 17 is used to heat the resin to ensure smooth resin impregnation.

[0041] The pressure vessel 12, glue injection tank 13, heat insulation cover molding fixture 14, glue storage tank 15, and vacuum pump 16 are all connected by pipelines. Among them, the pipelines located in the drying room 17 are made of metal flexible hoses or high-temperature resistant plastic pipes. After the pipelines are connected, the air tightness needs to be tested. It is required that the pressure should not drop to 0.45 kPa within 10 minutes when the air pressure is 0.5 kPa.

[0042] Using the above-mentioned heat shield molding system, the heat shield molding method includes:

[0043] S1. Insert the fabric into the inner core mold 1, then insert the lower mold 7, middle mold 6, and upper mold 5 in sequence, and use bolts to fix and connect the lower mold 7, middle mold 6, upper mold 5, and inner core mold 1. The selected inner shape of the fabric should fully fit the shape of the inner core mold 1, and the circumference of the fabric should be 3 to 10 mm smaller than the shape of the inner core mold 1. The materials of the inner core mold 1 and bolts and other tooling can be selected from stainless steel, high-temperature alloy steel, etc., according to the resin curing temperature.

[0044] S2. The resin in the dispensing tank 13 is heated by the drying oven 17, so that the resin changes from solid to liquid.

[0045] S3. Measure the resin viscosity. After the injection requirements are met, open the pressure vessel 12 to pressurize the injection tank 13, open the valve between the injection tank 13 and the heat insulation cover molding fixture 14, and the valve between the heat insulation cover molding fixture 14 and the storage tank 15, and open the vacuum equipment to evacuate the storage tank 15, so that the resin is gradually injected from the storage tank 15 into the heat insulation cover molding fixture 14 containing the fabric, until the resin flows out from the heat insulation cover molding fixture 14.

[0046] S4. After the resin in the heat insulation cover molding fixture 14 is cured, a heat insulation cover is formed. Remove the upper mold 5 and the middle mold 6, insert the cylindrical pin into the glue inlet 3 to push out the lower mold 7 and eject the heat insulation cover.

[0047] S5. Dissolve the resin in acetone with a mass fraction of 15% to 35% and add short chopped fibers with a length of 1 to 2 mm with a mass fraction of 10% to 50% to form a paste-like repair liquid. Apply the repair liquid to the pits of the heat insulation cover 3 to 5 times and allow it to cure gradually.

[0048] It should be noted that liquid resin at room temperature can be directly mixed with reinforcing chopped fibers. In this embodiment, the resin is a high-temperature resistant solid resin such as phthalonitrile, which can be dissolved first with ethanol, acetone, or esters, and then the chopped fibers are added and mixed. Gradient curing requires a slow temperature increase in the medium and low temperature stages, not exceeding 1°C / min. The curing temperature rise regime is 180°C / 1h → 210°C / 3h → 250°C / 3h → 300°C / 3h → 380°C / 5h. If the temperature conditions permit, the repaired area is sealed with a plastic bag and then pressure cured.

[0049] The structure of the heat insulation cover molding fixture 14 of this invention ensures simple fabric molding and convenient demolding. The heat insulation cover molding system has stable and simple connection processes, enabling batch molding of heat insulation covers. The heat insulation cover molding system can reduce operator contact with resin, improving the working environment for workers. For problems such as pits in the heat insulation cover layout, the solution in S5 above can be used for repair, improving the product qualification rate.

[0050] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A heat insulation cover forming fixture, characterized in that: The device includes an inner core mold (1) and an outer mold arranged coaxially. The outer mold is fitted onto the inner core mold (1) and is detachably connected to the inner core mold (1). A gap (2) is provided between the inner core mold (1) and the outer mold. The gap (2) is used as a resin flow channel. A glue inlet (3) is opened at the lower end of the inner core mold (1). The glue inlet (3) is connected to the gap (2). A glue outlet (4) is opened at the top of the outer mold. The glue outlet (4) is connected to the gap (2). The outer mold includes an upper mold (5), a middle mold (6), and a lower mold (7). The upper mold (5), the middle mold (6), and the lower mold (7) are arranged sequentially from the top of the inner core mold (1) downwards. The upper mold (5) and the middle mold (6) are detachably connected, and the middle mold (6) and the lower mold (7) are detachably connected. The glue outlet (4) is located on the top of the upper mold (5). The middle mold (6) is a cylindrical structure with open ends. The inner core mold (1) and the upper mold (5) are both cylindrical structures with open ends. The lower end of the upper mold (5) is provided with a first outer edge (8) along the outer wall. The upper and lower ends of the middle mold (6) are provided with a second outer edge (9) and a third outer edge (10) along the outer wall, respectively. The lower end of the inner core mold (1) is provided with a fourth outer edge (18) along the outer wall. The first outer edge (8) is connected to the second outer edge (9). The third outer edge (10) is connected to the lower mold (7) and the fourth outer edge (18). The inner diameters of the upper mold (5) and the middle mold (6) are both larger than the outer diameter of the inner core mold (1) at the corresponding position, thus forming a first gap (19) between the upper mold (5) and the inner core mold (1) and between the middle mold (6) and the inner core mold (1); the inner diameter of the lower mold (7) is equal to the outer diameter of the inner core mold (1) at the corresponding position, so that the inner wall of the lower mold (7) fits tightly with the outer wall of the inner core mold (1), and a step is provided on the lower end face of the third outer edge (10), so that a second gap (20) is formed between the middle mold (6) and the lower mold (7), and the second gap (20) and the first gap (19) together form a gap (2); The lower mold (7) is an annular plate structure. The lower mold (7) has a feed port. One end of the feed port is connected to the gap (2), and the other end of the feed port is connected to the glue inlet (3). The inner wall of the lower mold (7) is tightly fitted to the outer wall of the inner core mold (1). The gap (2) extends from the upper end face of the lower mold (7) to the top end face of the inner core mold (1). The cross-sectional area of ​​the feed port is smaller than that of the glue inlet (3). The lower mold (7) is used as a demolding ejection device. The lower mold (7) can be ejected by using a cylindrical pin with the same cross-section as the glue inlet (3). During the ejection of the lower mold (7), the heat insulation cover formed will also detach from the inner core mold (1).

2. The heat insulation cover forming fixture according to claim 1, characterized in that: Rubber rings (11) for sealing are provided between the first outer edge (8) and the second outer edge (9), between the third outer edge (10) and the lower mold (7), and between the lower mold (7) and the inner core mold (1).

3. A heat insulation cover molding system, characterized in that: The apparatus includes a pressure vessel (12), a glue injection tank (13), a heat insulation cover molding fixture (14) as described in any one of claims 1 or 2, a glue storage tank (15), and a vacuum pump (16) connected in sequence. The pressure vessel (12) is used to inject resin from the glue injection tank (13) into the glue inlet (3) of the heat insulation cover molding fixture (14). The glue storage tank (15) is connected to the glue outlet (4) of the heat insulation cover molding fixture (14). The vacuum pump (16) is used to evacuate the glue storage tank (15) so that the resin flows from the heat insulation cover molding fixture (14) into the glue storage tank (15).

4. The heat insulation cover molding system according to claim 3, characterized in that: The glue injection tank (13) and the heat insulation cover molding fixture (14) are set in the drying room (17), which is used to heat the resin to ensure smooth resin impregnation.

5. The heat insulation cover molding system according to claim 4, characterized in that: The pipes connecting the glue injection tank (13) to the heat insulation cover molding tool (14) and the pipes connecting the glue storage tank (15) to the heat insulation cover molding tool (14) are made of metal hoses or high-temperature resistant plastic pipes.

6. A method for forming a heat shield using the heat shield forming system according to any one of claims 3 to 5, characterized in that: include: S1. Insert the fabric into the inner core mold (1) and install the outer mold; S2. Heat the resin in the dispensing tank (13) to change the resin from solid to liquid; S3. Measure the resin viscosity. After the injection requirements are met, open the pressure vessel (12) to pressurize the injection tank (13), open the valve between the injection tank (13) and the heat insulation cover molding fixture (14), open the valve between the heat insulation cover molding fixture (14) and the storage tank (15), and open the vacuum equipment to evacuate the storage tank (15). This allows the resin to be gradually injected from the injection tank (13) into the heat insulation cover molding fixture (14) containing the fabric until the resin flows out from the heat insulation cover molding fixture (14). S4. After the resin in the heat insulation cover molding tool (14) is cured, a heat insulation cover is formed. The upper mold (5) and the middle mold (6) are removed, and the heat insulation cover is ejected using the lower mold (7).

7. The heat insulation cover molding method according to claim 6, characterized in that: Step S5: If there are pits in the heat insulation cover, dissolve the resin with acetone of 15% to 35% by mass and add short-cut fibers to form a paste-like repair liquid. Use the repair liquid to scrape and repair the pits in the heat insulation cover and allow it to cure in a gradient.

Images