Preparation method of louver-type fiber-reinforced resin-based light-blocking products

Abstract

This invention discloses a method for preparing a louver-type fiber-reinforced resin-based light-blocking product, belonging to the field of composite material manufacturing technology. The method includes: 1) using polymethacrylamide (PMI) foam as an auxiliary mold, utilizing the high-temperature setting properties of PMI foam for mold prefabrication; 2) performing surface sealing and hardening treatment on the set foam; 3) laying out fiber prepreg according to the designed layering; 4) hot-pressing to confirm dimensions; and 5) placing it in the integral mold for assembly and curing. This invention overcomes the limitations of preparing narrow-space metal molds for gratings and solves the problems of difficult molding and demolding of thin-walled grating products.

Description

Technical Field

[0001] This invention belongs to the field of composite material manufacturing technology. Specifically, it relates to a method for preparing louver-type fiber-reinforced resin-based light-blocking products, and more particularly to a method for preparing curved, thin-walled, non-load-bearing structures and mold forms. Background Technology

[0002] The core function of a light shield is to block all light from directions other than the target, allowing only light within the observation field of view to enter the optical system. Satellite secondary mirror light shields are key components of space optical systems, primarily used to suppress stray light, block non-imaging stray light from the space environment from entering the optical system, and prevent halos, flares, and other phenomena from affecting image quality; simultaneously, they reduce the impact of heat sources such as solar radiation on the optical system, maintaining system temperature stability; and protect optical components from direct exposure and contamination from the external environment to delicate optical elements such as secondary mirrors.

[0003] Meanwhile, the sunshade needs to withstand the mechanical environment of impacts and vibrations during satellite launch. Since it is mounted on the secondary mirror assembly, its weight must be as low as possible to avoid excessive load causing deformation of the secondary mirror assembly. Maintaining the thin-walled shape of a metal sunshade is difficult, stress concentration is prone to occur at sharp corners, and its large coefficient of thermal expansion means that temperature changes can lead to dimensional changes, resulting in a long molding cycle. Due to their superior specific strength and specific stiffness, composite materials have become the mainstream choice. However, considering the application requirements of sunshades, fabricating complex grating structures using composite materials remains challenging. Summary of the Invention

[0004] The present invention aims to provide a method for preparing louver-type fiber-reinforced resin-based light-blocking products, thereby enabling the preparation of louver-type resin-based light-blocking products and producing composite material light-blocking products with ultra-thin walls and curved surfaces.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a louver-type fiber-reinforced resin-based light-blocking product, wherein the light-blocking product is composed of several sets of staggered gratings, and the preparation method includes the following steps: S10. Based on the type of grating, prepare the corresponding PMI foam sheet and shaping core mold; S20, PMI mold prefabrication: PMI foam sheets are pressed and shaped at high temperature using a shaping core mold to obtain a PMI shaping mold; S30, Sealing and hardening: The curved surface of the PMI shaping mold is subjected to sealing and hardening treatment, and vacuum curing is performed to form a hardened shell sealing layer; S40. Wrapping release cloth: After the hardened shell sealing layer is prepared, wrap the entire area with release cloth; S50, Laying: Classify PMI molding molds of different thicknesses, wrap the product surface with fiber prepreg or carbon cloth, and add layers according to the required thickness of the product. S60, Shaping: The completed PMI shaping mold is placed in the corresponding central corner mold according to the category, and then cold-pressed, hot-pressed, and semi-cured to form a grating combination structure; S70. Assembly: Assemble several groups of grating structures that have been cured on the integral molding mold. According to product requirements, add layers and make loops at the grating splicing surface, inner concentric circle, and outer concentric circle to ensure that the grouped grating structures are connected, so that the inner and outer layers of the product are a whole and continuous. S80. Mold Closure: After all the tiling processes are completed, the mold is closed using an integral molding mold. S90 Demolding: After the product has cured, remove the overall molding mold, cut open the upper and lower hardened shell layers, tap the foam gently, and remove all PMI mold core layers. S100. After the product is demolded, the shape is adjusted through post-processing control.

[0006] Furthermore, in step S10, the central angle of each grating is set according to the light-shielding requirements, the thickness of the grating is 0.3mm to 0.5mm, and the thickness at the mounting interface position is 1.0mm to 2.0mm.

[0007] Furthermore, in step S10, the grating central angle is any angle that can be combined.

[0008] Further, in step S20, PMI foams of different thicknesses are placed in corresponding shaping core molds and pre-compressed at 170℃~180℃ for 4h~8h to obtain PMI shaping molds of different thicknesses.

[0009] Furthermore, in step S20, the shaping core mold includes: an inner arc mold, an outer arc mold, a left baffle and a right baffle, and each component is positioned and fixed through multiple pin holes and threaded connection holes.

[0010] Furthermore, in step S30, the sealing and hardening shell is made of glass cloth or carbon cloth / resin material.

[0011] Furthermore, in step S60, the hot pressing and shaping state of the central corner mold is divided into two states: cured and uncured.

[0012] Furthermore, in step S80, cold pressing and hot pressing are performed until the mold gap is no more than 0.1 mm, and the product is cured at a temperature of 90℃ / 2h~120℃ / 2h~170℃ / 4h.

[0013] Further, in step S80, the integral forming mold includes: a bottom support mold, a side wall pressure fixture and an upper cover plate, wherein the bottom support mold and the upper cover plate are interlocked and positioned with each other.

[0014] Furthermore, in step S100, after demolding, the product's external dimensions, flatness, and hole positions are adjusted by machining, and the product surface is guaranteed to be free of defects such as pressure marks, burrs, rust, and cracks.

[0015] The beneficial effects of this invention are: (1) It overcomes the limitations of fabricating narrow-space metal molds for gratings; (2) It solved the problems of difficult molding and demolding of thin-walled grating products; (3) It can utilize the high-temperature shaping properties of PMI molds to prepare composite material products with different curve shapes. Attached Figure Description

[0016] Figure 1 A schematic diagram of a typical product type for an invention; Figure 2 This is a schematic diagram of the integral molding mold of the present invention; Figure 3 This is a cross-sectional view of the integral molding mold of the present invention; Figure 4 This is a schematic diagram of a typical core mold for the present invention. Figure 1 ; Figure 5 This is a schematic diagram of a typical core mold for the present invention. Figure 2 ; Figure 6 This is a schematic diagram of a typical central angle mold of the present invention; Figure 7 This is a schematic diagram of the overall structure of the present invention. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0019] In the description of this invention, it should be understood that the orientation descriptions, such as up, down, front, back, left, right, etc., are based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention 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 limiting this invention.

[0020] In the description of this invention, "several" means one or more, "more than" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0021] In the description of this invention, unless otherwise explicitly defined, terms such as "set up," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in this invention in conjunction with the specific content of the technical solution.

[0022] Example 1

[0023] refer to Figures 1 to 7 A method for preparing a louver-type fiber-reinforced resin-based light-blocking product, wherein the light-blocking product is composed of several sets of staggered gratings, and the preparation method includes the following steps: S10. Based on the type of grating, prepare the corresponding PMI foam sheet and shaping core mold; In this embodiment, in step S10, the central angle of each grating is set according to the light-shielding requirements, the grating thickness is 0.3mm to 0.5mm, and the thickness at the mounting interface position is 1.0mm to 2.0mm.

[0024] In this embodiment, in step S10, the grating central angle is any angle that can be combined.

[0025] Specifically, the product type being manufactured is a curved louver-style resin-based light-blocking product. The typical product structure consists of six sets of staggered gratings. The gratings can be divided into two types, with central angles of 50° and 80° respectively. The grating thickness is 0.3mm~0.5mm, and the thickness at the mounting interface is 1.0mm~2.0mm. Thin-walled products are made of fiber-reinforced resin-based composite materials.

[0026] Preferably, the thin-walled product has a reinforcing material of carbon fiber or aramid fiber and a resin matrix of epoxy resin or cyanate ester system.

[0027] In practice, the product type can be extended to multiple sets of staggered grating structures. The central angle of the group of gratings can be defined according to the light-shielding requirements, with common groups being 55°-70°, 45°-90°, and 60°-60°.

[0028] S20, PMI mold prefabrication: PMI foam sheets are pressed and shaped at high temperature using a shaping core mold to obtain a PMI shaping mold; Specifically, the shaping core mold is designed and manufactured according to the grating classification and the product grating classification. Typical shaping core molds include: 45°, 50°, 55°, 60°, 70°, 80°, and 90° shaping molds.

[0029] In this embodiment, in step S20, the shaping core mold includes: an inner arc mold, an outer arc mold, a left baffle and a right baffle, and each component is positioned and fixed through multiple pin holes and threaded connection holes.

[0030] In practice, the left and right baffles of the core mold can be used interchangeably, and the long inner and outer arc molds can replace the short inner and outer arc molds, thus achieving mold sharing.

[0031] In practice, the PMI shaping mold is a sheet-like mold body of PMI pressed by high temperature using a shaping core mold, and the arc length and design deviation must be guaranteed to be ±0.2mm.

[0032] In this embodiment, in step S20, PMI foams of different thicknesses are placed in corresponding shaping core molds and pre-compressed at 170℃~180℃ for 4h~8h to obtain PMI shaping molds of different thicknesses.

[0033] S30, Sealing and Hardening: The curved surface of the PMI molding die is sealed and hardened by vacuum curing to form a hardened shell. Specifically, the hardened shell seal only includes the curved portion and does not include the thickness portion; In this embodiment, in step S30, the sealing and hardening shell is made of glass cloth or carbon cloth / resin material.

[0034] Preferably, the thin-walled product body resin is used for preparation.

[0035] S40. Wrapping release cloth: After the hardened shell sealing layer is prepared, wrap the entire area with release cloth to prevent the PMI molding mold and the product from sticking together. S50, First stage of molding, laying: Classify PMI molding molds of different thicknesses, wrap the product contact surface with fiber prepreg or carbon cloth, and add layers according to the required thickness of the product. Specifically, PMI molding dies of different thicknesses are classified, and single-component prepreg or carbon cloth is used to cover the PMI molding dies up to the designed number of layers; S60, Second stage of molding, shaping: The completed PMI shaping mold is placed in the corresponding central corner mold according to the category, and then cold-pressed, hot-pressed and semi-cured to form a grating combination structure. In this embodiment, in step S60, the hot pressing and shaping state of the central corner mold is divided into two states: cured and uncured.

[0036] S70, the third stage of molding, assembly: several groups of grating combination structures that have been cured are assembled on the overall molding mold. According to product requirements, additional layers are added and wrapped around the grating splicing surface, the inner concentric circle and the outer concentric circle to ensure that the grouped grating structures are connected, so that the inner and outer layers of the product are a whole and continuous. S80, Fourth stage of molding, mold closing: After all the laying processes are completed, the mold is closed using an integral molding mold; In this embodiment, in step S80, the product is cold-pressed and hot-pressed until the mold gap is no more than 0.1 mm, and then cured at a temperature of 90℃ / 2h~120℃ / 2h~170℃ / 4h.

[0037] In this embodiment, in step S80, the integral forming mold includes: a bottom support mold, a side wall pressure fixture and an upper cover plate, wherein the bottom support mold and the upper cover plate are interlocked and positioned with each other.

[0038] S90, the fifth stage of molding, demolding: After the product has cured, remove the overall molding mold, cut open the upper and lower hardened shell layers, tap the foam, and remove all PMI mold core layers. S100. After the product is demolded, the shape is adjusted through post-processing control.

[0039] In this embodiment, in step S100, after demolding, the product's external dimensions, flatness, and hole positions are adjusted by machining, and the product surface is guaranteed to be free of defects such as pressure marks, burrs, rust, and cracks.

[0040] Example 2

[0041] This embodiment adopts the method of embodiment 1 to provide a typical venetian blind structure. The typical product structure consists of six sets of staggered gratings. The gratings can be divided into two types, with central angles of 50° and 80° respectively. The central angle molds correspond to the 50° central angle mold and the 80° central angle mold.

[0042] Includes the following steps: S10, Reference Figure 1A typical louver structure, based on usage requirements, has an outer contour dimension not exceeding 350mm, an inner contour not exceeding 200mm, a height not exceeding 50mm, a weight not exceeding 500g, and a fundamental frequency not less than 70Hz. Calculations show that it is fabricated using T300 carbon cloth / epoxy prepreg, with a circumferential grating thickness of 0.6mm, a middle partition thickness of 0.6mm, an inner circumferential skin thickness of 1.0mm, and a bottom mounting interface thickness of 2.0mm. Under these conditions, the fundamental frequency and weight requirements are met. S11, Reference Figure 1 The product structure can be divided into two parts, with central angles of 50° and 80° respectively. There are four 50° central angle gratings and two 80° central angle gratings. Each grating has 16 groups, and the thickness is available in two specifications: 1.5mm and 3.5mm. S12. Based on the above product analysis, prepare PMI foam of 1.2 (0 -0.1) mm and 3.2 (0 -0.1) mm, cut according to the theoretical arc length, ensure that the arc length and design deviation are within ±0.2 mm, and trim the edges. S20, using 50° and 80° shaping core molds ( Figures 4-5 PMI foam is molded and pressed by using screws to press the inner arc mold, outer arc mold, left baffle and right baffle in sequence, and then hot-pressed at 175℃ for 6 hours. S30. After all PMIs are shaped, wrap the curved surfaces of all PMI shaping molds with one layer of T300 / epoxy carbon cloth (1k) and then vacuum cure. S40. After the PMI mold outer sealing layer hardening shell is prepared, wrap the entire area with release cloth to prevent the PMI mold and product from sticking together. S50. Classify PMI shaping molds of different thicknesses and wrap all PMI shaping molds with 3 layers of customized T300 carbon cloth / epoxy prepreg. S60. Place the completed PMI shaped mold gratings, grouped and laid out, into 50° and 80° central angle molds according to their categories. Figure 6 Cold pressing, hot pressing, and semi-curing are all methods of curing, with a curing temperature of 90℃ / 2h~120℃ / 2h. S70. Assemble the several groups of cured gratings on the integral molding mold. Add 7 layers of T300 carbon cloth / epoxy prepreg to the inner concentric circle and add 3 layers of T300 carbon cloth / epoxy prepreg to the outer concentric circle. The fibers of the inner concentric circle and the bottom mounting position are continuous. At the same time, 13 layers of T300 carbon cloth / epoxy prepreg are separately laid at the bottom mounting position to ensure that the grouped grating structures are connected, so that the inner and outer layers of the product are a whole and continuous. S80. After completing all the laying processes, use an integral molding mold to close the mold, cold press and hot press until the gap between the molds is no more than 0.1mm, and then cure the product. The curing temperature is 90℃ / 2h~120℃ / 2h~170℃ / 4h. S90. After the product has cured, remove the overall molding mold, cut open the upper and lower hardened shell layers, tap the foam gently, and remove all PMI mold core layers. S100 After the product is demolded, the flatness, hole position, height and other dimensions are controlled through post-processing, and the shape is trimmed to ensure that the product is beautiful and flat, and the surface is free of defects such as pressure marks, burrs, rust, and cracks.

[0043] The louver-type resin-based light-blocking product prepared by this method has a bottom flatness of 0.04mm after machining and finishing, weighs 439g, and has no defects such as dents, burrs, rust, or cracks on the surface, nor any bubbles or wrinkles.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A method for preparing a louver-type fiber-reinforced resin-based light-blocking product, wherein the light-blocking product is composed of several sets of staggered gratings, characterized in that... The preparation method includes the following steps: S10. Based on the type of grating, prepare the corresponding PMI foam sheet and shaping core mold; S20, PMI mold prefabrication: PMI foam sheets are pressed and shaped at high temperature using a shaping core mold to obtain a PMI shaping mold; S30, Sealing and hardening: The curved surface of the PMI shaping mold is subjected to sealing and hardening treatment, and vacuum curing is performed to form a hardened shell sealing layer; S40. Wrapping release cloth: After the hardened shell sealing layer is prepared, wrap the entire area with release cloth; S50, Laying: Classify PMI molding molds of different thicknesses, wrap the product surface with fiber prepreg or carbon cloth, and add layers according to the required thickness of the product. S60, Shaping: The completed PMI shaping mold is placed in the corresponding central corner mold according to the category, and then cold-pressed, hot-pressed and semi-cured to form a grating combination structure; S70. Assembly: Assemble several groups of grating structures that have been cured on the integral molding mold. According to product requirements, add layers and make loops at the grating splicing surface, inner concentric circle, and outer concentric circle to ensure that the grouped grating structures are connected, so that the inner and outer layers of the product are a whole and continuous. S80. Mold Closure: After all the tiling processes are completed, the mold is closed using an integral molding mold. S90 Demolding: After the product has cured, remove the overall molding mold, cut open the upper and lower hardened shell layers, tap the foam gently, and remove all PMI mold core layers. S100. After the product is demolded, the shape is adjusted through post-processing control.

2. The method for preparing the louver-type fiber-reinforced resin-based light-blocking product according to claim 1, characterized in that, In step S10, the central angle of each grating is set according to the light-shielding requirements, the thickness of the grating is 0.3mm to 0.5mm, and the thickness at the mounting interface position is 1.0mm to 2.0mm.

3. The method for preparing the louver-type fiber-reinforced resin-based light-blocking product according to claim 2, characterized in that, In step S10, the central angle of the grating can be any angle that can be combined.

4. The method for preparing the louver-type fiber-reinforced resin-based light-blocking product according to claim 1, characterized in that, In step S20, PMI foams of different thicknesses are placed in the corresponding shaping core molds and pre-compressed at 170℃~180℃ for 4h~8h to obtain PMI shaping molds of different thicknesses.

5. The method for preparing the louver-type fiber-reinforced resin-based light-blocking product according to claim 1, characterized in that, In step S20, the shaping core mold includes: an inner arc mold, an outer arc mold, a left baffle and a right baffle, and each component is positioned and fixed through multiple pin holes and threaded connection holes.

6. The method for preparing the louver-type fiber-reinforced resin-based light-blocking product according to claim 1, characterized in that, In step S30, the sealing and hardening shell is made of glass cloth or carbon cloth / resin material.

7. The method for preparing the louver-type fiber-reinforced resin-based light-blocking product according to claim 1, characterized in that, In step S60, the hot pressing and shaping state of the central corner mold is divided into two states: cured and uncured.

8. The method for preparing the louver-type fiber-reinforced resin-based light-blocking product according to claim 1, characterized in that, In step S80, cold pressing and hot pressing are performed until the mold gap is no more than 0.1mm, and the product is cured at a temperature of 90℃ / 2h~120℃ / 2h~170℃ / 4h.

9. The method for preparing the louver-type fiber-reinforced resin-based light-blocking product according to claim 1, characterized in that, In step S80, the integral forming mold includes: a bottom support mold, a side wall pressure fixture and an upper cover plate, wherein the bottom support mold and the upper cover plate are interlocked and positioned with each other.

10. The method for preparing the louver-type fiber-reinforced resin-based light-blocking product according to claim 1, characterized in that, In step S100, after demolding, the product's external dimensions, flatness, and hole positions are adjusted by machining, and the product surface is guaranteed to be free of defects such as pressure marks, burrs, rust, and cracks.

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