Square light shield and preparation method thereof

Abstract

The invention discloses a square light shield and a preparation method thereof, and belongs to the technical field of satellite light shields. The problems that all parts of an existing light shield are troublesome to assemble and low in assembling reliability are solved. The light shield specifically comprises a light shield body, a heat insulation piece and an inner frame. A square shading cylinder is arranged in the middle of the shading cover body, the bottom of the square shading cylinder is accommodated in the inner frame, the top of the square shading cylinder is connected with a mounting flange, and the square shading cylinder is mounted on the inner frame through the mounting flange; and a heat insulation piece is arranged between the mounting flange and the inner frame. According to the light shield, the light shield body is made of the ceramic matrix composite material, the inner frame is made of the titanium alloy material, the temperature requirement and the strength requirement of the light shield in use can be met, and meanwhile the weight of the light shield body can be reduced; the light shield body is manufactured in an integral forming mode, assembly errors caused by part assembly are avoided, the high-precision requirement is met, the integral connection reliability of the light shield body is guaranteed, the assembly technological process is simplified, and the manufacturing period is shortened.

Description

Technical Field

[0001] The invention relates to the technical field of satellite sunshades, and in particular to a square sunshade and a preparation method thereof. Background Art

[0002] Satellite sunshade components are an important part of space optical remote sensors. Their main function is to suppress stray light to ensure the imaging quality of the optical system. With the development of science and technology, ceramic matrix composites (CMC) have shown great potential and application value in the preparation of satellite sunshade components due to their high temperature resistance, high strength, and low density.

[0003] The application of ceramic matrix composites in satellite sunshades is mainly due to their excellent thermal stability and mechanical properties, which can maintain stable performance in extreme space environments. The preparation processes of ceramic matrix composites include chemical vapor deposition, chemical vapor infiltration, solid reaction infiltration, polymer conversion method, etc. The development of these processes is crucial to improving the performance of ceramic matrix composites and reducing costs.

[0004] A Chinese invention patent with publication number CN113911401A discloses a lightweight / high-temperature resistant integrated composite satellite sunshade and a method for preparing the same. The patent divides the sunshade product into two parts, a base and a hoop, and then molds the two parts separately. Finally, the base and the hoop are combined through a set bonding process to obtain the sunshade. This technology splits the sunshade into two parts and assembles them by gluing, which results in problems such as component assembly gap error, assembly connection strength reliability, and a long preparation cycle. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a square light shield and a preparation method thereof, which solves the problems of difficult assembly of various components of the prior light shield and low assembly reliability.

[0006] In the first aspect, in order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is:

[0007] A square sunshade comprises a sunshade body, a heat insulating member and an inner frame; a square sunshade tube is provided in the middle of the sunshade body, the bottom of the square sunshade tube is accommodated in the inner frame, a mounting flange is connected to the top of the square sunshade tube, and the square sunshade tube is mounted on the inner frame via the mounting flange; a heat insulating member is provided between the mounting flange and the inner frame.

[0008] In this solution, the inner frame provides support for the sunshade body so that the overall strength requirement of the device is met; the sunshade body is integrally formed to avoid assembly errors caused by component assembly, thereby improving the overall reliability of the sunshade body, simplifying the assembly process, and shortening the preparation cycle.

[0009] Furthermore, the square light-shielding cylinder is a tapered structure with a reduced diameter, and a plurality of light-shielding sheets are arranged inside the tapered structure, and the diameters of the plurality of light-shielding sheets are reduced along with the diameter of the tapered structure;

[0010] The light shielding sheet comprises a vertical frame, the outer wall of which is closely connected to the inner wall of the square light shielding tube; and the interior of the vertical frame is connected with a horizontal frame.

[0011] In this solution, the horizontal frame on the light blocking sheet is mainly used to suppress stray light; a vertical frame is set on the light blocking sheet to increase its contact area with the square light-shielding tube, facilitate the connection between the light blocking sheet and the inner wall of the square light-shielding tube, and improve the connection strength of the two after integral molding.

[0012] Furthermore, the light shielding sheet is provided with 4-6 layers; the thickness of the light shielding sheet is 1 mm; and the width of the horizontal frame in the light shielding sheet is 10-15 mm.

[0013] Furthermore, the material of the sunshade body is a ceramic-based composite material; the material of the inner frame is a titanium alloy material; and the material of the heat insulation component is a quartz / quartz composite material.

[0014] In this solution, the inner frame of the titanium alloy material can make the square sunshade as a whole meet the strength requirements; the thermal insulation is used to isolate the heat transfer between the sunshade body of the ceramic-based composite material and the inner frame of the titanium alloy material, avoiding the thermal adaptation problem caused by the difference in thermal physical properties of the two different materials.

[0015] Furthermore, through holes are provided on the mounting flange, the thermal insulation member and the inner frame, and screws pass through the through holes of the mounting flange, the thermal insulation member and the inner frame in sequence and are connected with nuts; a gasket is provided between the screws and the mounting flange.

[0016] In this solution, the mounting flange, the heat insulating member and the inner frame are connected by screws, which makes assembly simple and disassembly convenient.

[0017] In a second aspect, the present invention provides a method for preparing a shading cover body based on the square shading cover provided in the first aspect, comprising the following steps:

[0018] S1: preparing an L-shaped light blocking sheet preform and an external integral preform;

[0019] S2: Assembling the L-shaped light shielding sheet preform and the external integral preform into a graphite mold, and sewing and fixing the L-shaped light shielding sheet preform and the external integral preform to obtain a light shield body preform;

[0020] S3: preparing an interface layer on the sunshade body preform by using a CVI process;

[0021] S4: using the CVI process to prepare a silicon carbide matrix for the sunshade body preform to obtain a sunshade body product.

[0022] In this solution, after the L-shaped light shielding plate preform and the external integral preform are prepared, they are placed in a graphite mold for vapor deposition, so that the two are formed in one piece, the subsequent assembly or bonding process is omitted, and the connection reliability of the light shield body is guaranteed.

[0023] Furthermore, S1 includes:

[0024] S101: using carbon fiber as a raw material, weaving a vertical frame preform and a horizontal frame preform by a weaving process; and sewing the horizontal frame preform inside the vertical frame preform to obtain an L-shaped light shielding sheet preform;

[0025] S102: Using carbon fiber as raw material, a square light-shielding tube preform and a mounting flange preform are weaved by a weaving process, and the mounting flange preform is sewn to the edge of the square light-shielding tube preform to obtain an external integral preform.

[0026] Furthermore, S2 includes:

[0027] S201: placing an L-shaped light shielding sheet preform on an inner mold of a graphite mold, and sewing and fixing the L-shaped light shielding sheet preform on the inner mold using carbon fiber;

[0028] S202: placing the outer integral preform on the L-shaped light shielding sheet preform, and sewing and fixing the outer integral preform and the L-shaped light shielding sheet preform with carbon fiber to obtain a light shield body preform;

[0029] S203: installing an outer mold of a graphite mold outside the light shield body prefabricated body;

[0030] S3 includes:

[0031] S301: placing the light shield body preform together with the inner mold and the outer mold into a CVI deposition furnace, and introducing a carbon source gas to prepare an interface layer on the light shield body preform;

[0032] S302: removing the outer mold; placing the light shield body preform and the inner mold into the CVI deposition furnace, and preparing the interface layer of the light shield body preform again;

[0033] S4 includes:

[0034] S401: placing the light shield body preform and the inner mold into a CVI deposition furnace, and introducing a SiC gas source to prepare a silicon carbide matrix for the light shield body preform;

[0035] S402: reinstalling the outer mold, and after installation, placing the light shield body preform into a CVI deposition furnace for high temperature treatment at 1700-2000°C;

[0036] S403: After the high temperature treatment, a CVI vapor deposition process is used again to prepare a silicon carbide substrate for the light shield body preform;

[0037] S404: removing the inner mold and the outer mold, and machining the sunshade body preform;

[0038] S405: After processing, the shading hood body preform is placed in the CVI deposition furnace again, and a silicon carbide matrix is ​​prepared on the shading hood body preform by using a CVI vapor deposition process to obtain a shading hood body product.

[0039] In this scheme, when preparing the interface layer, the interface layer is prepared for the sunshade body preform with the outer mold installed and the sunshade body preform with the outer mold removed, respectively, to ensure that a pyrolytic carbon interface layer is deposited on the surface of the sunshade body preform; then SiC is introduced into the interior of the sunshade body preform through a vapor deposition process to obtain a dense SiC matrix; finally, a sunshade body product of a ceramic-based composite material is obtained.

[0040] In the third aspect, the present invention provides a graphite mold based on a method for preparing a sunshade body provided in the second aspect, which specifically includes an inner mold and an outer mold; a conical inner cavity is provided inside the outer mold, and an inner mold is provided inside the conical inner cavity; the inner mold is a conical structure with the same shape as a square sunshade tube; a plurality of steps are provided on the outer surface of the inner mold, and each layer of the L-shaped light-blocking sheet preform is fixed on each layer of the steps.

[0041] Furthermore, the outer mold includes a bottom mold and two side molds, and the two side molds are fixed to the bottom mold by bolts; the conical inner cavity is arranged at the connection of the two side molds.

[0042] The beneficial effects of the present invention are:

[0043] The square sunshade provided by the present invention is composed of a sunshade body made of a ceramic-based composite material, a heat insulating member, and an inner frame made of a titanium alloy; the ceramic-based composite material can meet the temperature requirements for the use of the sunshade body, and at the same time can reduce the weight of the sunshade body; the metal inner frame can meet the overall strength requirements of the square sunshade. The sunshade body is prepared by integral molding in the molding method, which avoids assembly errors caused by parts assembly, meets high-precision requirements, ensures the overall connection reliability of the sunshade body, simplifies the assembly process, and shortens the preparation cycle. A quartz / quartz composite material is used as a heat insulating member between the sunshade body made of a ceramic-based composite material and the metal inner frame, which effectively prevents the problem of thermal deformation and incompatibility caused by differences in thermal physical properties of the two different materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a schematic diagram of a square light shield structure in Example 1 of the present invention;

[0045] Figure 2 This is an exploded view of a square light shield in Example 1 of the present invention;

[0046] Figure 3 This is a schematic diagram of the structure of a square light-shielding tube in Example 1 of the present invention;

[0047] Figure 4 This is a schematic diagram of the structure of the L-shaped light blocking sheet preform in Embodiment 2 of the present invention;

[0048] Figure 5 This is a schematic diagram of the external integral preform structure in Example 2 of the present invention;

[0049] Figure 6 This is a schematic diagram of the structure of the light shield body preform in Example 2 of the present invention;

[0050] Figure 7 This is a schematic diagram of the graphite mold structure in Example 3 of the present invention;

[0051] Figure 8 This is a schematic diagram of the inner mold structure in Example 3 of the present invention;

[0052] Fig. 9 This is a schematic diagram of the outer mold structure in Example 3 of the present invention.

[0053] Reference numerals:

[0054] 1. Sunshade body; 11. Square sunshade tube; 12. Mounting flange; 13. Sunshade sheet; 131. Vertical frame; 132. Horizontal frame; 2. Heat insulation; 3. Inner frame; 4. Screws; 5. Nuts; 6. Gasket; 7. L-shaped sunshade sheet preform; 71. Vertical frame preform; 72. Horizontal frame preform; 8. External integral preform; 81. Square sunshade tube preform; 82. Mounting flange preform; 9. Graphite mold; 91. Inner mold; 92. Outer mold; 921. Bottom mold; 922. Side mold; 10. Bow clip; DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. The specific implementation of the present invention is described below to facilitate the understanding of the present invention by those skilled in the art, but it should be clear that the present invention is not limited to the scope of the specific implementation. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention defined and determined by the attached claims, these changes are obvious, and all inventions and creations using the concept of the present invention are protected.

[0056] Example 1

[0057] like Figure 1-Figure 3As shown, this embodiment provides a square sunshade, which uses ceramic-based composite materials and metal materials to meet the temperature requirements and strength requirements of use; avoids assembly errors caused by parts assembly and meets high precision requirements; specifically includes:

[0058] Sunshade body 1, heat insulation 2 and inner frame 3;

[0059] Among them, there is a square light-shielding tube 11 in the middle of the sunshade body 1, the bottom of the square light-shielding tube 11 is accommodated in the inner frame 3, and the top of the square light-shielding tube 11 is connected with a mounting flange 12, and the square light-shielding tube 11 is installed on the inner frame 3 through the mounting flange 12; a heat insulating member 2 is provided between the mounting flange 12 and the inner frame 3; the sunshade body 1 is integrally formed, which improves the overall reliability of the sunshade body 1, simplifies the assembly process, and shortens the preparation cycle.

[0060] The square light-shielding tube 11 is a conical structure with a reduced diameter, and a plurality of layers of light-blocking sheets 13 are arranged inside the conical structure, and the diameters of the plurality of layers of light-blocking sheets 13 are reduced along with the diameter of the conical structure; the light-blocking sheets 13 include a vertical frame 131, and the outer wall of the vertical frame 131 is fitted and connected to the inner wall of the square light-shielding tube 11, and the vertical frame 131 can increase the contact area between the light-blocking sheet 13 and the square light-shielding tube 11, thereby improving the connection strength after the two are integrally formed; the interior of the vertical frame 131 is connected to a horizontal frame 132, and the horizontal frame 132 is mainly used to suppress stray light.

[0061] The light shielding sheet 13 is provided with 4-6 layers; the thickness of the light shielding sheet 13 is 1 mm; the width of the horizontal frame 132 in the light shielding sheet 13 is 10-15 mm.

[0062] The material of the sunshade body 1 is a ceramic-based composite material; the material of the inner frame 3 is a titanium alloy material; the material of the thermal insulation 2 is a quartz / quartz composite material; the inner frame 3 of the titanium alloy material can make the square sunshade as a whole meet the strength requirements; the thermal insulation 2 is used to isolate the heat transfer between the sunshade body 1 of the ceramic-based composite material and the inner frame 3 of the titanium alloy material, avoiding the thermal adaptation problem caused by the difference in thermal physical properties of the two different materials.

[0063] Through holes are provided on the mounting flange 12, the thermal insulation member 2 and the inner frame 3, and the screws 4 pass through the through holes of the mounting flange 12, the thermal insulation member 2 and the inner frame 3 in sequence and are connected with the nuts 5; a gasket 6 is provided between the screw 4 and the mounting flange 12; this connection method is simple to assemble and easy to disassemble.

[0064] Example 2

[0065] like Figure 4-Figure 9 As shown, this embodiment provides a method for preparing a light shield body 1 in a square light shield based on a square light shield provided in Embodiment 1, comprising the following steps:

[0066] S1: preparing an L-shaped light-blocking sheet preform 7 and an external integral preform 8; specifically comprising:

[0067] S101: Using carbon fiber as raw material, weaving a vertical frame preform 71 and a horizontal frame preform 72 by a weaving process; and sewing the horizontal frame preform 72 inside the vertical frame preform 71 to obtain an L-shaped light shielding sheet preform 7, such as Figure 4 As shown;

[0068] S102: Using carbon fiber as raw material, weaving a square shading tube preform 81 and a mounting flange preform 82 by a weaving process, and sewing the mounting flange preform 82 to the edge of the square shading tube preform 81 to obtain an external integral preform 8, such as Figure 5 shown.

[0069] S2: Assembling the L-shaped light shielding sheet preform 7 and the external integral preform 8 into a graphite mold 9, and sewing and fixing the L-shaped light shielding sheet preform 7 and the external integral preform 8 to obtain a light shield body preform; specifically comprising:

[0070] S201: placing the L-shaped light shielding sheet preform 7 on the inner mold 91 of the graphite mold 9, and sewing and fixing the L-shaped light shielding sheet preform 7 on the inner mold 91 using carbon fiber;

[0071] S202: placing the outer integral preform 8 on the L-shaped light shielding sheet preform 7, sewing and fixing the outer integral preform 8 and the L-shaped light shielding sheet preform 7 with carbon fiber to obtain a light shield body preform. Figure 6 As shown;

[0072] S203: Install the outer mold 92 of the graphite mold 9 outside the shading hood body preform; during the installation process, ensure that the shading hood body preform has no defects such as damage, wrinkles, deformation, etc., improve the mold fixing quality of the shading hood body preform, and meet the mold fixing technical requirements.

[0073] S3: Using CVI process to prepare the interface layer of the sunshade body preform; specifically including:

[0074] S301: placing the light shield body preform together with the inner mold 91 and the outer mold 92 into a CVI deposition furnace, and introducing carbon source gas to prepare an interface layer on the light shield body preform;

[0075] S302: Remove the outer mold 92, and the light shield body preform must not be damaged during the removal process; put the light shield body preform and the inner mold 91 into the CVI deposition furnace, and prepare the interface layer of the light shield body preform again; ensure that a pyrolytic carbon interface layer is deposited on the surface of the light shield body preform, and the thickness of the interface layer is required to meet 120-250nm.

[0076] S4: Using the CVI process to prepare a silicon carbide matrix on the sunshade body preform to obtain a sunshade body 1 product, specifically including:

[0077] S401: placing the light shield body preform and the inner mold 91 into a CVI deposition furnace, and introducing a SiC gas source to prepare a silicon carbide matrix for the light shield body preform;

[0078] S402: reinstall the outer mold 92, and after installation, place the light shield body preform into a CVI deposition furnace for high temperature treatment at 1700-2000°C;

[0079] S403: After the high temperature treatment, the CVI vapor deposition process is used again to prepare a silicon carbide matrix on the light shield body preform. In this step, the light shield body preform can also be subjected to multiple furnaces of silicon carbide deposition, and the specific number of times can be determined according to the density of the silicon carbide matrix;

[0080] S404: dismantle the inner mold 91 and the outer mold 92, and perform mechanical processing on the light shield body preform to ensure that its dimensional accuracy meets the tolerance requirements and does not have defects such as burrs, delamination, cracks, and tearing.

[0081] S405: After processing, the shading shield body preform is put into the CVI deposition furnace again, and the silicon carbide matrix is ​​prepared on the shading shield body preform by continuing to use the CVI vapor deposition process to ensure that there is no fiber leakage on the surface of the obtained shading shield body 1 product.

[0082] Example 3

[0083] like Figure 7 As shown; this embodiment is based on a method for preparing a sunshade body 1 provided in Example 2, and provides a graphite mold 9 for fixing the L-shaped light-blocking plate preform 7 and the external integral preform 8 when preparing the sunshade body 1, and making the two integrally formed in the graphite mold 9; it specifically includes an inner mold 91 and an outer mold 92; a conical inner cavity is provided inside the outer mold 92, and an inner mold 91 is provided inside the conical inner cavity.

[0084] like Figure 8 As shown, the inner mold 91 is a conical structure with the same shape as the square light-shielding tube 11; the outer surface of the inner mold 91 is provided with a plurality of steps, and each layer of the L-shaped light-shielding sheet preform 7 is correspondingly fixed on each layer of the steps.

[0085] like Fig. 9 As shown, the outer mold 92 includes a bottom mold 921 and two side molds 922, and the two side molds 922 are fixed to the bottom mold 921 by bolts; a conical inner cavity is arranged at the connection of the two side molds 922; a flange edge is also arranged at the connection of the two side molds 922, and the two side molds 922 are connected by bolts passing through the flange edge.

[0086] When the graphite mold 9 is used, the inner mold 91 is first placed on the bottom mold 921; each layer of the L-shaped light shielding sheet preform 7 is then placed on the steps on the outer surface of the inner mold 91; the outer integral preform 8 is then placed on the L-shaped light shielding sheet preform 7, and the outer integral preform 8 and the L-shaped light shielding sheet preform 7 are sewn and fixed with carbon fiber to obtain the light shield body preform. Finally, the two side molds 922 are buckled on the light shield body preform, and the side molds 922 and the bottom mold 921 are clamped and fixed by the bow clamp 10; after fixing, the side molds 922 and the bottom mold 921 are connected by bolts.

[0087] Those skilled in the art will appreciate that the embodiments herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the invention.

Claims

1. A square sunshade, characterized in that: The invention comprises a sunshade body (1), a heat insulating member (2) and an inner frame (3); a square sunshade tube (11) is disposed in the middle of the sunshade body (1); the bottom of the square sunshade tube (11) is accommodated in the inner frame (3); a mounting flange (12) is connected to the top of the square sunshade tube (11); the square sunshade tube (11) is mounted on the inner frame (3) via the mounting flange (12); and the heat insulating member (2) is disposed between the mounting flange (12) and the inner frame (3).

2. The square sunshade according to claim 1, characterized in that: The square light-shielding cylinder (11) is a conical structure with a reduced caliber, and a plurality of layers of light-shielding sheets (13) are arranged inside the conical structure, and the calibers of the plurality of layers of light-shielding sheets (13) are reduced along with the caliber of the conical structure; The light shielding sheet (13) comprises a vertical frame (131), the outer wall of the vertical frame (131) being fitted and connected to the inner wall of the square light shielding tube (11); and the interior of the vertical frame (131) is connected to a horizontal frame (132).

3. The square sunshade according to claim 2, characterized in that: The light shielding sheet (13) is provided with 4-6 layers; the thickness of the light shielding sheet (13) is 1 mm; and the width of the horizontal frame (132) in the light shielding sheet (13) is 10-15 mm.

4. The square sunshade according to claim 3, characterized in that: The material of the sunshade body (1) is a ceramic-based composite material; the material of the inner frame (3) is a titanium alloy material; and the material of the heat insulating component (2) is a quartz / quartz composite material.

5. The square sunshade according to claim 4, characterized in that: Through holes are provided on the mounting flange (12), the thermal insulation member (2) and the inner frame (3); screws (4) pass through the through holes of the mounting flange (12), the thermal insulation member (2) and the inner frame (3) in sequence and are connected to nuts (5); a gasket (6) is provided between the screws (4) and the mounting flange (12).

6. A method for preparing a sunshade body according to claim 4, characterized in that: The following steps are involved: S1: preparing an L-shaped light blocking sheet preform (7) and an external integral preform (8); S2: Assembling the L-shaped light shielding sheet preform (7) and the external integral preform (8) into a graphite mold (9), and sewing and fixing the L-shaped light shielding sheet preform (7) and the external integral preform (8) to obtain a light shield body preform; S3: preparing an interface layer on the sunshade body preform by using a CVI process; S4: using the CVI process to prepare a silicon carbide matrix for the sunshade body preform to obtain a sunshade body product.

7. The method for preparing the sunshade body according to claim 6, characterized in that: The S1 includes: S101: using carbon fiber as raw material, weaving a vertical frame preform (71) and a horizontal frame preform (72) by a weaving process; and sewing the horizontal frame preform (72) inside the vertical frame preform (71) to obtain the L-shaped light shielding sheet preform (7); S102: Using carbon fiber as raw material, a square light-shielding tube preform (81) and a mounting flange preform (82) are weaved using a weaving process, and the mounting flange preform (82) is sewn to the edge of the square light-shielding tube preform (81) to obtain the external integral preform (8).

8. The method for preparing the sunshade body according to claim 6, characterized in that: The S2 includes: S201: placing the L-shaped light shielding sheet preform (7) on the inner mold (91) of the graphite mold, and sewing and fixing the L-shaped light shielding sheet preform (7) on the inner mold (91) using carbon fibers; S202: placing the external integral preform (8) on the L-shaped light shielding sheet preform (7), and sewing and fixing the external integral preform (8) and the L-shaped light shielding sheet preform (7) by using carbon fiber to obtain a light shield body preform; S203: installing the outer mold (92) of the graphite mold outside the light shield body prefabricated body; The S3 includes: S301: placing the light shield body preform together with the inner mold (91) and the outer mold (92) into a CVI deposition furnace, and introducing a carbon source gas to prepare an interface layer on the light shield body preform; S302: removing the outer mold (92); placing the light shield body preform and the inner mold (91) into a CVI deposition furnace, and preparing an interface layer on the light shield body preform again; The S4 includes: S401: placing the light shield body preform and the inner mold (91) into a CVI deposition furnace, and introducing a SiC gas source to prepare a silicon carbide matrix for the light shield body preform; S402: reinstalling the outer mold (92), and after installation, placing the light shield body preform into a CVI deposition furnace for high temperature treatment at 1700-2000°C; S403: After the high temperature treatment, a CVI vapor deposition process is used again to prepare a silicon carbide substrate for the light shield body preform; S404: removing the inner mold (91) and the outer mold (92), and performing mechanical processing on the light shield body preform; S405: After processing, the shading shield body preform is placed in the CVI deposition furnace again, and a silicon carbide matrix is ​​prepared on the shading shield body preform by using a CVI vapor deposition process to obtain a shading shield body product.

9. A graphite mold according to claim 8, characterized in that: It comprises an inner mold (91) and an outer mold (92); a conical inner cavity is provided inside the outer mold (92), and the inner mold (91) is provided inside the conical inner cavity; The inner mold (91) is a conical structure with the same shape as the square light-shielding tube (11); the outer surface of the inner mold (91) is provided with a plurality of steps, and each layer of the L-shaped light-shielding sheet preform (7) is correspondingly fixed on each layer of the steps.

10. The graphite mold according to claim 9, characterized in that: The outer mold (92) comprises a bottom mold (921) and two side molds (922), and the two side molds (922) are fixed to the bottom mold (921) by bolts; the conical inner cavity is arranged at the connection between the two side molds (922).

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