Small-size light machine light shield prefabricated body forming method, forming tool and mold

Abstract

The invention relates to a small-size light machine light shield preform forming method, a forming tool and a mold, belongs to the technical field of ceramic matrix composite component preparation, and solves the technical problems of long preform forming period and high operation difficulty. The method comprises the steps of preform division, anti-dazzling screen area cutting and flanging, lower-layer pipe fitting area forming, outer-layer overall area forming, assembling and sewing and mold closing. The tool comprises a metal sewing piece, an external prefabricated body paving piece and an outer layer sewing piece. The mold comprises an inner mold, an outer mold, a limiting block and a fastener. The inner mold is used for forming a shading sheet area and a lower-layer pipe fitting area, and the outer mold is used for forming an outer-layer overall area. The method is used for forming the C / SiC composite material small-size light machine light shield prefabricated body.

Description

Technical Field

[0001] The invention belongs to the technical field of ceramic-based composite material component preparation, and in particular relates to a small-size optical machine light shield preform molding method and a molding tool and mold. Background Art

[0002] The sunshade is used to block sunlight and outflow heat for space cameras. When a satellite is flying in orbit, sunlight will directly penetrate the camera's optical system, which will cause the temperature of the camera structure to rise, the accuracy of the optical system to change, and affect the image quality. On the other hand, it will also form stray light and interfere with target information. The traditional material of the sunshade of a space camera is metal, which is heavy and has a large thermal expansion coefficient.

[0003] Ceramic-based composites are a new type of thermal structural / functional integrated material that combines the performance advantages of metal materials, ceramic materials and carbon materials. They have the characteristics of high temperature resistance, low density, high specific strength, high specific modulus, oxidation resistance, ablation resistance, insensitivity to cracks, and no catastrophic damage. They are widely used in aviation, aerospace, nuclear energy, photovoltaics and other fields.

[0004] Ceramic-based composite rudder surfaces can not only meet the requirements of low expansion coefficient, ablation resistance and strength under temperature changes, but also have the advantages of lightweight.

[0005] Ceramic-based composite materials are still rarely used in optical machine visors. The visors prepared by traditional preparation methods are assembled by split structures. Traditional preparation methods have long preparation cycles, small space dimensions, high difficulty in operation, and scattered mechanical properties. Summary of the invention

[0006] In order to overcome the shortcomings of long preparation cycle and great operation difficulty in the molding of small-sized optical machine light shield preforms, the present invention proposes a small-sized optical machine light shield preform molding method and molding tooling and mold.

[0007] The technical solution adopted by the present invention to solve the technical problem is:

[0008] A method for forming a small-sized optical machine light shield preform comprises the following steps:

[0009] Step 1: Prefab division

[0010] The C / SiC composite material small-size optical machine shading cover preform structure is divided into a shading sheet area, a lower pipe area, and an outer layer overall area; the shading sheet area is connected to the lower pipe area, and the outer side of the shading sheet area and the outer side of the lower pipe area are connected to the outer layer overall area;

[0011] Step 2: Cut and flanging the shading area

[0012] The shading sheet area is in the shape of a square platform, with a square platform hole in the center; the shading sheet area is divided into N layers connected in sequence, namely the first layer, the second layer, ..., the Nth layer; the first layer is connected to one end of the lower pipe area; the cross section of each layer is L-shaped, with an open top and a rectangular hole in the center of the bottom surface;

[0013] Each layer of the shading sheet area includes several layers of carbon cloth, which are divided into an inner layer of carbon cloth, a middle layer of carbon cloth, and an outer layer of carbon cloth. The carbon cloth is provided with cutting openings, which are located at the side corners, and the cutting openings of two adjacent layers of carbon cloth are staggered;

[0014] Using the corresponding inner mold, each layer of flange is used to prepare the 1st layer to the Nth layer of the light shielding sheet area, N ≥ 2;

[0015] Step 3: Forming the lower pipe area

[0016] The carbon cloth is wound on the inner mold of the lower tube by using a winding method, and the outermost carbon cloth interface is bonded to obtain a cylindrical lower tube area;

[0017] Step 4: Forming the outer layer area

[0018] Using the lower layer pipe fitting area (including the inner mold) and the outer layer preform paving parts obtained in step 3, the carbon cloth is paved layer by layer until the outer layer overall area is formed, the outer layer sewing parts are installed, and the outer layer preform paving parts are separated;

[0019] Step 5: Assemble and sew

[0020] The corresponding inner mold of each layer of the shading sheet area is removed, and the working surface of the layer of the shading sheet area is double-sided sewn using a metal sewing piece, a steel needle and carbon fiber filaments;

[0021] Using a steel needle and carbon fiber filaments, sew the lower tube area and the outer overall area of ​​step 4 through the sewing holes of the inner mold;

[0022] Assemble the first layer preform of the shading sheet area and its metal sewing parts to step 4, use the sewing grooves of the metal sewing parts and the outer layer sewing parts to complete the sewing of the side of the shading sheet area and the outer layer overall area, remove the metal sewing parts inside this layer of preforms, and replace the inner mold;

[0023] Complete the assembly and sewing of the first layer, the second layer, ..., the Nth layer in sequence.

[0024] The flat area of ​​the preform is double-sided sewn using the outer sewing piece.

[0025] Step 6: Mold Closing

[0026] Remove the outer sewing parts, and sew several rows of stitches in the first outer mold area until the first outer mold 1 and the outer layer integral area form a whole;

[0027] The second outer mold, the third outer mold, the limit block and the fastener are molded together to obtain a C / SiC composite material small-size optical machine light shield preform preparation part.

[0028] The above preform molding method, step 1, further comprises:

[0029] According to the different thicknesses of small-sized optical machine hoods, it is divided into an L-shaped structure; the bottom edge, side edges and the overall area of ​​the outer carbon cloth in the narrow space of the preform shading area are double-sided sewn.

[0030] In the above molding method, in step 2, using a corresponding inner mold, each layer of flange is used to prepare the first to Nth layers of the light shielding sheet area, specifically:

[0031] Using the first inner mold, preparing the first layer of the light shielding sheet area;

[0032] Using the second inner mold, preparing the second layer of the light shielding sheet area;

[0033] Until the Nth inner mold is used to prepare the Nth layer of the light shielding plate area.

[0034] In the above molding method, in step 2, the forming process of each layer of flange paving is as follows: apply polyvinyl alcohol PVA solid glue on the inner mold. Lay the cut carbon cloth along the bottom or side of the mold as a reference, cut the excess carbon cloth, and after laying one layer, apply polyvinyl alcohol PVA solid glue or polyethylene sizing agent with a concentration of 20% to 50% on the carbon cloth, and lay it layer by layer until the number of carbon cloth layers with the required thickness is reached; after the molding is completed, cure at room temperature for 2 to 5 hours.

[0035] The above molding method, step 2, further comprises:

[0036] The thickness of each layer of the shading film area is 1mm, the carbon cloth is 1K carbon cloth, and the specification of the carbon cloth is 150g / m 2 The thickness of a single carbon cloth layer is 0.15mm to 0.17mm. The number of carbon cloth layers in each layer of the light shielding film area is 6, and the number of layers of the inner carbon cloth, the middle carbon cloth, and the outer carbon cloth are all 2;

[0037] The cutting openings of the inner carbon cloth and the outer carbon cloth of each layer in the shading sheet area are at the sides, the cutting opening of the middle layer is at the bottom, the adjacent cutting openings of each layer are staggered, and the number of cutting openings at the corners of each layer is no more than 4.

[0038] In the above-mentioned forming method, in step 5, the sewing float length of the shading plate area is ≤3mm, the sewing width is the sewing groove spacing, and the spacing is ≤3mm.

[0039] In the above-mentioned forming method, in step 6, three rows of stitches are sewn between the first outer mold area and both sides of the preform in the width direction.

[0040] A forming tooling, comprising a metal sewing piece, an external prefabricated body paving piece, and an outer sewing piece;

[0041] Metal sewing parts are used for sewing the shading area and the outer layer overall area;

[0042] The external prefabricated paving pieces are used for the flange paving and forming of the overall outer layer area;

[0043] The outer layer sewing piece is used for sewing the outer layer overall area and the shading sheet area.

[0044] A forming mold, comprising an inner mold and an outer mold;

[0045] The inner mold includes a first inner mold, a second inner mold, ..., an Nth inner mold, and a lower layer pipe inner mold, which are respectively used for forming the first layer, the second layer, ..., the Nth layer, and the lower layer pipe region of the light shielding sheet area;

[0046] The outer mold includes a first outer mold, a second outer mold, and a third outer mold, which are used for molding the entire outer layer area;

[0047] The second outer mold and the third outer mold are symmetrical to each other and are located outside the junction of the light shielding area, the lower layer pipe area and the outer layer overall area; the first outer mold is a flat plate with a rectangular hole in the center and is located on the end surface of the outer layer overall area away from the lower layer pipe area;

[0048] The inner mold material and the outer mold material are both high-purity graphite, or both are high-strength graphite.

[0049] The beneficial effects of the present invention are:

[0050] A method for forming a small-sized optical machine shading cover preform reduces assembly steps, solves the problem that the shading cover cannot be assembled due to the small space size, and is formed as a whole to improve mechanical properties.

[0051] A method for forming a preform of a small-sized optical machine shading cover adopts L-shaped division to achieve double-sided sewing of a small-sized shading plate area, reduce the risk of delamination, and improve mechanical properties.

[0052] A method for forming a small-sized optical machine light shield preform realizes double-sided sewing of the entire preform (each working surface) and improves the mechanical properties of the preform. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 is an isometric view of a cross-sectional view of a preform according to an embodiment of the present invention;

[0054] Figure 2 This is a schematic diagram of the preform splitting structure of an embodiment of the present invention;

[0055] Figure 3 is an isometric view of a mold in the area of ​​the light shielding sheet according to an embodiment of the present invention;

[0056] Figure 4 It is a top view of a certain layer of the inner mold in the light shielding sheet area of ​​an embodiment of the present invention;

[0057] Figure 5 It is a three-dimensional diagram of a preform including an inner mold in a certain layer of the light shielding sheet area of ​​an embodiment of the present invention;

[0058] Figure 6 This is a schematic diagram of the paving and assembly of the entire outer layer area of ​​an embodiment of the present invention;

[0059] Figure 7 This is a schematic diagram of the placement of the flange in the area of ​​a single-layer shading sheet;

[0060] Figure 8 It is a schematic diagram of sewing the outer layer overall area and the shading sheet area in an embodiment of the present invention;

[0061] Fig. 9 It is an overall schematic diagram of the mold clamping embodiment of the present invention.

[0062] Figure numerals: 1. Shading plate area, 2. Lower layer pipe area, 3. Outer layer overall area. DETAILED DESCRIPTION

[0063] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0064] Embodiment 1

[0065] With regard to the small-size optical machine sunshade preform molding tooling and molding method, the preform is split and the molding tooling is now designed.

[0066] 1. Small-size prefabricated structure, due to the small wall thickness and the small space for the shading sheet, in order to meet the process technology requirements, the prefabricated shading sheet thickness is divided into L-shaped structures. The overall division method is as follows: Figure 1 , 2 After splitting and division, the prefabricated body can realize double-sided sewing of the bottom edge and side edge of the narrow space in the horizontal area of ​​shading and the overall area of ​​the exterior.

[0067] 2. The process of cutting and flanging the preform in the shading sheet area is as follows;

[0068] 2.1 The thickness of each layer of L-shaped preform is 1mm, using 1K carbon cloth, the specification of carbon cloth is 150g / m 2 The thickness of a single layer is 0.15 to 0.17, and the number of carbon cloth layers of each shading sheet is 6.

[0069] 2.2 The preform is flanging on the inner mold. During the flanging process, the cutting openings of the inner and outer 2 layers of the preform are on the side of the L-shaped mold, and the number of cutting openings is not more than 4. The cutting openings of the 2 layers of carbon cloth in the middle sandwich are on the L-shaped shading sheet. The cutting openings are at the corners of the preform cloth layer. The cutting openings of the adjacent two layers of cloth are appropriately staggered, such as Figure 3 , 4 , 5. This method of flanging ensures that the preform will not be delaminated due to the cutting edge during the later demolding and preform processing of the shading sheet working area. Each layer of flanging in the L-shaped shading sheet area is treated with PVA (polyvinyl alcohol) solid glue or 20% to 50% concentration of polyethylene sizing agent to brush the carbon cloth surface. After the flanging is completed, it is cured at room temperature for 2 to 5 hours until the surface of the preform fiber cloth is bonded and cured, and then it is ready for use; the mold design ensures that the preform meets the surface requirements, and the destruction grooves and air holes are processed on the inside and outside to facilitate the later preform vapor deposition and demolding. The material of the mold is high-purity graphite or high-strength graphite.

[0070] 3. The lower pipe area will be formed by winding on the surface of the inner mold. After forming, the last layer of carbon cloth will be bonded with transparent tape.

[0071] 4. Forming of the outer layer overall area

[0072] The lower pipe area (including the inner mold) is assembled with the outer preform paving parts, and the outer preform is flanging. During the flanging process, each layer of the preform is evenly coated with PVA solid glue or 20% to 50% concentration of polyvinyl alcohol. The paving tooling is as follows: Figure 6 After the outer preform is flanged, it is cured at room temperature for 2 to 5 hours until the surface of the preform fiber cloth is bonded and cured. Then, the outer preform paving parts are removed, and the lower pipe area is sewn through with the help of the sewing holes of the inner mold to complete the sewing of area 2 and area 3. Install the outer sewing parts

[0073] 5. Prefabricated body assembly and sewing process

[0074] 5.1 Each layer of the shading sheet L-shaped preform is removed from the graphite mold and transferred to the metal sewing mold to sew the shading sheet working surface. The sewing density is sewn according to the sewing groove, and the sewing float length is ≤3mm to ensure that the preform is sewn in the part area and the shading sheet is sewn on both sides. The schematic diagram is as follows Figure 7 As shown;

[0075] 5.2 Special metal sewing parts are installed on the outside of the outer integral prefabricated body;

[0076] 5.3 After the sewing is completed, the L-shaped preform and the metal sewing parts are placed into the outer integrally formed preform in order from bottom to top, and the outer metal sewing parts are installed on the outside of the integrally formed preform. The side wall of the shading sheet is sewn, and a steel curved needle is used for sewing to achieve double-sided sewing of the preform in the shading sheet area and the external integral area. After the preform is sewn, the graphite mold is replaced. The process is as follows Figure 8 As shown;

[0077] 5.4 Complete the sewing of each layer of L-shaped shading sheet from bottom to top, and replace the metal tooling with the graphite tooling after each layer is sewn;

[0078] 6. Preform mold closing process

[0079] The outer sewing piece is removed, and three rows of stitches are sewn in the local area of ​​the first outer mold to ensure that the first outer mold of the preform forms an integral whole with the preform.

[0080] The second outer mold and the third outer mold are closed. Fig. 9 shown.

Claims

1. A method for forming a small-sized optical machine shade preform, characterized in that: The following steps are involved: Step 1, prefab division: The C / SiC composite material small-size optical machine shading cover preform structure is divided into a shading sheet area, a lower pipe area, and an outer layer overall area; the shading sheet area is connected to the lower pipe area, and the outer side of the shading sheet area and the outer side of the lower pipe area are connected to the outer layer overall area; Step 2: Cut and chamfer the shading area: The shading sheet area is in the shape of a square platform, with a square platform hole in the center; the shading sheet area is divided into N layers connected in sequence, namely the first layer, the second layer, ..., the Nth layer; the first layer is connected to one end of the lower pipe area; the cross section of each layer is L-shaped, with an open top and a rectangular hole in the center of the bottom surface; Each layer of the shading sheet area includes several layers of carbon cloth, which are divided into an inner layer of carbon cloth, a middle layer of carbon cloth, and an outer layer of carbon cloth. The carbon cloth is provided with cutting openings, which are located at the side corners, and the cutting openings of two adjacent layers of carbon cloth are staggered; Using the corresponding inner mold, each layer of flange is used to prepare the 1st layer to the Nth layer of the light shielding sheet area, N ≥ 2; Step 3: Forming the lower pipe area: The carbon cloth is wound on the inner mold of the lower tube by a winding method to reach the required thickness, and the outermost carbon cloth interface is bonded to obtain a cylindrical lower tube area; Step 4: Forming the outer layer area: Using the lower layer pipe fitting area (including the inner mold) and the outer layer preform paving parts obtained in step 3, the carbon cloth is paved layer by layer until the outer layer overall area is formed, the outer layer sewing parts are installed, and the outer layer preform paving parts are removed; Step 5, assemble and sew: The corresponding inner mold of each layer of the shading sheet area is removed, and the working surface of the layer of the shading sheet area is double-sided sewn using metal sewing parts, steel needles and carbon fiber filaments; Using a steel needle and carbon fiber filaments, through the sewing holes of the mold in the lower pipe fitting area in step 4, using a steel needle and carbon fiber filaments, pierce and sew the lower pipe fitting area and the outer layer overall area; Assemble the first layer preform of the shading sheet area and its metal sewing parts to the assembly parts in the previous step, use the sewing grooves of the metal sewing parts and the outer layer sewing parts to complete the sewing of the side of the shading sheet area and the outer layer overall area, detach the metal sewing parts inside this layer of preforms, and replace the inner mold; Complete the assembly and sewing of the first layer, the second layer, ..., the Nth layer in sequence; Using the outer sewing piece, the plane area of ​​the preform is double-sided sewn; Step 6, mold closing: Remove the outer sewing parts, and sew several rows of stitches in the first outer mold area until the first outer mold 1 and the outer layer integral area form a whole; The second outer mold, the third outer mold, the limit block and the fastener are molded together to obtain a C / SiC composite material small-size optical machine light shield preform preparation part.

2. The molding method according to claim 1, characterized in that: The step 1 further comprises: According to the different thicknesses of small-sized optical machine hoods, it is divided into an L-shaped structure; the bottom edge, side edges and the overall area of ​​the outer carbon cloth in the narrow space of the preform shading area are double-sided sewn.

3. The molding method according to claim 1, characterized in that: In step 2, using the corresponding inner mold, each layer of flange is used to prepare the first layer to the Nth layer of the light shielding sheet area, specifically: Using the first inner mold, preparing the first layer of the light shielding sheet area; Using the second inner mold, preparing the second layer of the light shielding sheet area; Until the Nth inner mold is used to prepare the Nth layer of the light shielding plate area.

4. The molding method according to claim 1, characterized in that: In the step 2, the forming process of each layer of flange paving is as follows: applying polyvinyl alcohol (PVA) solid glue on the inner mold; paving the cut carbon cloth along the bottom or side of the mold as a reference surface, cutting the excess carbon cloth, and after paving one layer, applying polyvinyl alcohol (PVA) solid glue or a polyethylene sizing agent with a concentration of 20% to 50% on the carbon cloth, paving layer by layer until the number of carbon cloth layers with the required thickness is reached; and curing at room temperature for 2 to 5 hours after the forming is completed.

5. The molding method according to claim 1, characterized in that: The step 2 further comprises: The thickness of each layer of the shading film area is 1mm, the carbon cloth is 1K carbon cloth, and the specification of the carbon cloth is 150g / m 2 The thickness of a single carbon cloth layer is 0.15mm to 0.17mm. The number of carbon cloth layers in each layer of the light shielding film area is 6, and the number of layers of the inner carbon cloth, the middle carbon cloth, and the outer carbon cloth are all 2; The cutting openings of the inner carbon cloth and the outer carbon cloth of each layer in the shading sheet area are at the sides, the cutting opening of the middle layer is at the bottom, the adjacent cutting openings of each layer are staggered, and the number of cutting openings at the corners of each layer is no more than 4.

6. The molding method according to claim 1, characterized in that: In step 5, the sewing float length of the shading plate area is ≤3mm, and the sewing width is the sewing groove spacing, which is ≤3mm.

7. The molding method according to claim 1, characterized in that: In step 6, three rows of stitches are sewn between the first outer mold area and both sides of the preform in the width direction.

8. A tool for implementing the integral forming method according to any one of claims 1 to 7, characterized in that: Including metal sewing parts, external prefabricated body paving parts, and outer sewing parts; The metal sewing parts are used for sewing the shading sheet area and the outer layer overall area. The sewing parts are made of A3 steel or aluminum alloy LY12, and the thickness of the metal sewing parts is 1.5 to 3 mm. The external prefabricated paving parts are used for the flange paving and forming of the overall outer layer area, and the material is high-strength or high-purity graphite; The outer layer sewing piece is used for sewing the sides of the outer layer overall area and the shading sheet area, and is made of A3 steel or aluminum alloy LY12. The thickness of the metal sewing piece is 1.5 to 3 mm.

9. A mold for implementing the integral molding method according to any one of claims 1 to 7, characterized in that: Including inner mold and outer mold; The inner mold includes a first inner mold, a second inner mold, ..., an Nth inner mold, and a lower layer pipe inner mold, which are respectively used for forming the first layer, the second layer, ..., the Nth layer, and the lower layer pipe region of the light shielding sheet area; The outer mold includes a first outer mold, a second outer mold, and a third outer mold, which are used for CVI-SiC process molding of the overall outer surface of the preform; The second outer mold and the third outer mold are symmetrical to each other and are located at the outer surface of the light shielding area, the lower layer pipe area and the outer layer overall area; the first outer mold is a flat plate with a rectangular hole in the center; The inner mold material and the outer mold material are both high-purity graphite, or both are high-strength graphite.

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