A method for forming a shell with an ablative layer on the inner surface and an asymmetric head

Abstract

The present invention discloses a method for forming a shell with an ablation layer on the inner surface and an asymmetric head, which relates to the technical field of composite material forming. The method includes assembling a mold with an asymmetric head, manufacturing an ablation-resistant layer, winding and molding, curing, and demolding to obtain a shell with an ablation layer on the inner surface and an asymmetric head. The forming process is simple, with high forming efficiency, low cost, and high material mechanical properties, and is suitable for mass production. The ablation-resistant layer of the rocket engine shell is formed by using boron phenolic resin and high-silica glass fiber cloth. The ablation-resistant layer is uniform, has a high carbonization rate, high strength, and good ablation resistance, avoiding the problems of poor erosion resistance, bubbling of traditional ablation-resistant coatings, uneven thickness of ethylene propylene diene monomer (EPDM) rubber ply, poor inner surface finish, and bubbling.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material molding, and specifically to a method for molding a shell with an ablative layer on the inner surface and an asymmetric head. Background Art

[0002] Ablation-resistant shells are generally used in rocket engine. In the past, the rocket shell was provided with a metal lining, and then an anti-ablative coating was applied on the inner surface or formed by laying ternary ethylene propylene rubber. Due to the large weight of the engine shell, this combination has limited structure, low dimensional accuracy, and cannot fully exert its performance, reducing the range and mobility of the rocket. In addition, the traditional anti-ablative coating has problems such as poor erosion resistance and bubbling, while ternary ethylene propylene rubber has problems such as uneven laying thickness, poor inner surface finish, and bubbling. Therefore, the existing ablation-resistant shells have low mechanical properties, poor high-temperature resistance, low molding efficiency, and high labor intensity, and cannot meet the requirements of rocket engines. Summary of the Invention

[0003] To solve the above problems, the purpose of the present invention is to provide a method for molding a shell with an ablative layer on the inner surface and an asymmetric head.

[0004] To achieve the above purpose, the present invention is realized through the following technical solutions:

[0005] A method for molding a shell with an ablative layer on the inner surface and an asymmetric head includes the following steps:

[0006] ① Assembling a mold with an asymmetric head;

[0007] ② Manufacturing an ablation-resistant layer: applying a release agent to the mold, then winding a layer of PTFE tape on the mold, applying a release agent on the PTFE tape, then uniformly brushing boron phenolic resin on the mold in sequence, laying a layer of high silica glass fiber cloth, brushing the boron phenolic resin glue on the high silica glass fiber cloth with a brush, winding a layer of high silica glass fiber yarn infiltrated with boron phenolic resin on it, and putting it into a curing furnace. First, cure it at 75-85°C for 0.5-1 hour, then raise the temperature to 155-165°C and cure it for 1-2 hours to obtain the ablation-resistant layer;

[0008] ③Winding forming and curing: Install the mold on the winding machine, pour medium-temperature curing resin glue into the glue tank, lead out the high-strength glass fiber yarn from the tensioner, pass it through the dipping tank, and wind it around the mold mandrel through the winding carriage to divide the filament bundles. Adjust the tension, wind the high-strength glass fiber yarn to the expected thickness of 5 mm, put it into the curing furnace, connect the mold with the rotating device in the curing furnace through the connection structure in the curing furnace, close the furnace lid, start the winding machine, and rotate and cure to obtain a shell with an ablation layer on the inner surface and an asymmetric head; the curing parameters are that the rotation speed during the rotation curing process is 30 - 50 revolutions per minute. First, cure at 75 - 85 °C for 1 - 1.5 hours, and then raise the temperature to 115 - 125 °C and cure for 1 - 2 hours;

[0009] ④Demold to obtain a shell with an ablation layer on the inner surface and an asymmetric head.

[0010] Preferably, the mold with an asymmetric head includes a support mandrel and a mandrel. A positioning hole is opened at one end of the support mandrel, and a positioning post is arranged at one end of the mandrel. The diameter of the positioning post is smaller than that of the mandrel, and the positioning post is inserted and matched with the positioning hole;

[0011] A first positioning ring and a first retaining ring are installed on the support mandrel. The first retaining ring is located on the side of the first positioning ring close to the positioning hole, and a first positioning setscrew is arranged on the first positioning ring;

[0012] A first shell head is arranged between the support mandrel and the mandrel. A through hole matching the positioning post at the end of the mandrel is opened on the first shell head, and the positioning post passes through the through hole;

[0013] A split inner mold, a second shell head, a second retaining ring, and a second positioning ring are installed on the mandrel. The split inner mold is located between the first shell head and the second shell head. The split inner mold is composed of a plurality of modules arranged around the mandrel in a splicing manner. The second retaining ring is located between the second shell head and the second positioning ring, and a second positioning setscrew is arranged on the second positioning ring.

[0014] Preferably, at least 3 adjusting bolts are arranged on both the first positioning ring and the second positioning ring. The adjusting bolts axially pass through the positioning ring and are threadedly matched with the positioning ring. Each adjusting bolt is evenly distributed along the circumference of its corresponding positioning ring.

[0015] Preferably, the process of assembling the mold with an asymmetric head is as follows:

[0016] Install the first positioning ring on the support mandrel, connect the first retaining ring, and tighten the first positioning setscrew to fix the first positioning ring on the support mandrel;

[0017] Install the first shell head on the positioning post at the end of the mandrel, install the positioning post in the positioning hole, and then assemble the split inner mold onto the mandrel;

[0018] Install the second shell head, the second retaining ring and the second positioning ring on the mandrel, tighten the second positioning set screw, and fix the second positioning ring on the mandrel;

[0019] The further demolding process is as follows:

[0020] Loosen the second positioning set screw, remove the second retaining ring and the second positioning ring from the mandrel, and then remove the mandrel; Loosen the first positioning set screw, remove the first positioning ring, the first retaining ring, and the support mandrel; Disassemble and remove the split internal mold from the inner hole formed after being withdrawn from the mandrel to obtain a shell with an ablation layer on the inner surface and an asymmetric head.

[0021] Preferably, the mold release agent is obtained by mixing dimethyl silicone oil, liquid paraffin and toluene in a mass ratio of 5:1-3:2-4.

[0022] Preferably, the boron phenolic resin adhesive solution is obtained by mixing boron phenolic resin, mica, KH550 coupling agent and industrial alcohol in a mass ratio of 7-8:2-3:0.1-0.3:10.

[0023] Preferably, the medium-temperature curing resin adhesive solution is obtained by mixing AG-80 epoxy resin, E-51 epoxy resin, 701 flame retardant, antimony trioxide and diaminodiphenylmethane modified dicyandiamide in a mass ratio of 6-8:5:1-2:1-2:5-7;

[0024] The diaminodiphenylmethane modified dicyandiamide is composed of diaminodiphenylmethane and dicyandiamide in a mass ratio of 200:180-270.

[0025] The present invention has the following advantages compared with the prior art:

[0026] The forming method of the shell with an ablation layer on the inner surface and an asymmetric head of the present invention has a simple forming process, high forming efficiency, low cost, high material mechanical properties, is suitable for automated operation and mass production, and is suitable for the forming of shells that are not easily demolded by conventional methods; Among them, a boron phenolic resin and a high-silica glass fiber cloth are used to form the ablation-resistant layer of the rocket engine shell. The ablation-resistant layer is uniform, has a high carbonization rate, high strength, and good ablation resistance, avoiding problems such as poor erosion resistance and bubbling of traditional ablation-resistant coatings, uneven thickness of the ethylene propylene diene monomer (EPDM) rubber layer, poor inner surface finish, and bubbling. A medium-temperature curing epoxy resin is used for high-temperature-resistant epoxy resin, which reduces energy consumption, improves production efficiency, avoids the performance loss of various materials in the shell under high-temperature curing, and the winding layer has high mechanical properties, and the fiber strength utilization rate reaches more than 97%.

[0027] The mold adopted by the present invention is a combined structure of metal flap molds. An ablation-resistant layer is made on the metal flap molds. After winding, forming and curing, the metal flap molds are drawn out from both ends of the shell, and then the molds are combined and reused, which can effectively control the dimensional deformation of the shell. The inner surface quality of the shell is high, the coaxiality and roundness are good, the quality consistency is good, the forming efficiency is high, and the problems of low dimensional accuracy, low production efficiency and high labor intensity after forming of traditional sand molds are avoided. Description of the Drawings

[0028] Figure 1 It is a cross-sectional view of the mold for a shell with an ablation layer on the inner surface and an asymmetric head;

[0029] Figure 2 It is a left view of the spliced inner mold;

[0030] Figure 3 It is a cross-sectional view of the spliced inner mold;

[0031] Figure 4 It is a cross-sectional view of the first positioning ring;

[0032] Figure 5 It is a left view of the first positioning ring;

[0033] Figure 6 It is a schematic structural diagram of a shell with an ablation-resistant layer on the inner surface and an asymmetric head after winding, forming and curing;

[0034] Figure 7 It is a schematic structural diagram of a shell with an ablation-resistant layer on the inner surface and an asymmetric head after demolding.

[0035] Reference Signs:

[0036] 1 Support mandrel, 2 First positioning ring, 3 First retaining ring, 4 First shell head, 5 Positioning hole, 6 Spliced inner mold, 7 Mandrel, 8 Second shell head, 9 Second retaining ring, 10 Second positioning set screw, 11 Adjusting bolt, 12 First metal flap mold, 13 Second metal flap mold, 14 Ablation-resistant layer, 15 Molded shell, 16 Demolded shell, 17 Through hole, 18 Second positioning ring, 19 First positioning set screw, 20 Positioning post. Detailed Embodiment

[0037] The purpose of the present invention is to provide a forming method for a shell with an ablation layer on the inner surface and an asymmetric head, which is realized through the following technical solutions:

[0038] The following further describes the present invention with specific embodiments.

[0039] The high-silica glass fiber yarn of the present invention can select products produced by the following manufacturers: Nanjing Yuanzheng Glass Fiber Co., Ltd., Luoyang Senhui Glass Fiber Co., Ltd. or Gaoshi Mingxiang High-Silica Glass Fiber Products Co., Ltd.

[0040] The high-strength glass fiber yarn of the present invention can be selected from products produced by the following manufacturers: Nanjing Fiberglass Research and Design Institute Co., Ltd., Jiangsu Zhengwei New Materials, or Chongqing International Composite Materials Co., Ltd. Example 1

[0041] A method for forming a shell with an ablative layer on the inner surface and an asymmetric head includes the following steps:

[0042] ① Assemble the mold with an asymmetric head;

[0043] ② Make the ablative-resistant layer: Apply a release agent to the mold, then wrap a layer of PTFE tape on the mold, apply a release agent on the PTFE tape, and then evenly brush boron phenolic resin on the mold in sequence, lay a layer of high silica glass fiber cloth, brush the boron phenolic resin sizing on the high silica glass fiber cloth with a brush, wind a layer of high silica glass fiber yarn impregnated with boron phenolic resin on it, put it into a curing furnace, cure at 75°C for 0.5 hour first, and then raise the temperature to 155°C and cure for 1 hour to obtain the ablative-resistant layer;

[0044] ③ Winding forming and curing: Install the mold on a winding machine, pour medium-temperature curing resin sizing into the glue tank, lead out the high-strength glass fiber yarn from the tensioner, pass it through the dipping tank, and wind it around the mold mandrel in a split filament bundle through the winding carriage, adjust the tension, wind the high-strength glass fiber yarn to the expected thickness of 5 mm, put it into the curing furnace, connect the mold to the rotating device in the curing furnace through the connection structure in the curing furnace, close the furnace cover, start the winding machine, and rotate and cure to obtain a shell with an ablative layer on the inner surface and an asymmetric head; the curing parameters are that the rotation speed during the rotation curing process is 50 revolutions per minute, and cure at 85°C for 1 hour first during curing, and then raise the temperature to 115°C and cure for 1 hour;

[0045] ④ Demold to obtain a shell with an ablative layer on the inner surface and an asymmetric head. Example 2

[0046] A method for forming a shell with an ablative layer on the inner surface and an asymmetric head includes the following steps:

[0047] ① Assemble the mold with an asymmetric head:

[0048] As Figure 1 shown, the mold with an asymmetric head includes a support mandrel 1 and a mandrel 7. A positioning hole 5 is opened at one end of the support mandrel 1, and a positioning post 20 is provided at one end of the mandrel 7. The diameter of the positioning post 20 is smaller than the diameter of the mandrel 7, and the positioning post is inserted and matched with the positioning hole 5;

[0049] The first positioning ring 2 and the first retaining ring 3 are installed on the support mandrel 1. The first retaining ring 3 is located on the side of the first positioning ring 2 close to the positioning hole 5. The first positioning ring 2 is provided with a first positioning setscrew 19;

[0050] A first shell head 4 is arranged between the support mandrel 1 and the mandrel 7. A through hole 17 is opened on the first shell head 4 and is matched with the positioning post 20 at the end of the mandrel 7. The positioning post passes through the through hole;

[0051] A split inner mold 6, a second shell head 8, a second retaining ring 9 and a second positioning ring 18 are installed on the mandrel 7. The split inner mold 6 is located between the first shell head 4 and the second shell head 8. The split inner mold 6 is composed of a plurality of modules arranged around the mandrel 7 in a splicing manner. The second retaining ring 9 is located between the second shell head 8 and the second positioning ring 18. The second positioning ring 18 is provided with a second positioning setscrew 10;

[0052] As Figure 2 and Figure 3 shown, the split inner mold 6 is obtained by arranging the first metal petal mold 12 and the second metal petal mold 13 in an alternating manner. Such a design facilitates installation and disassembly and saves labor;

[0053] The specific process of assembling the mold with an asymmetric head is as follows:

[0054] Install the first positioning ring 2 on the support mandrel 1, connect the first retaining ring 3, and tighten the first positioning setscrew 19 to fix the first positioning ring 2 on the support mandrel 1;

[0055] Install the first shell head 4 on the positioning post at the end of the mandrel 7, install the positioning post in the positioning hole 5, and then assemble the split inner mold 6 onto the mandrel 7;

[0056] Install the second shell head 8, the second retaining ring 9 and the second positioning ring 18 on the mandrel 7, tighten the second positioning setscrew 10, and fix the second positioning ring 18 on the mandrel 7;

[0057] ② Fabricate the ablation-resistant layer: Apply a release agent to the split inner mold 6, then wrap a layer of PTFE tape on the split inner mold 6, apply a layer of release agent on the PTFE tape, and then uniformly brush boron phenolic resin on the mold in sequence, lay a layer of high silica glass fiber cloth with a thickness of 0.2 mm, brush the boron phenolic resin sizing agent onto the high silica glass fiber cloth with a brush, wind a layer of high silica glass fiber yarn impregnated with boron phenolic resin on it, put it into a curing furnace, cure it at 75 °C for 0.5 hours first, and then raise the temperature to 155 °C and cure it for 1 hour to obtain the ablation-resistant layer;

[0058] The high silica glass fiber yarn is 1200 tex, the tension is controlled at 120 N, and the thickness is about 0.4 mm;

[0059] The mold release agent is obtained by mixing dimethyl silicone oil, liquid paraffin, and toluene in a mass ratio of 5:1:2;

[0060] The boron phenolic resin glue is obtained by mixing boron phenolic resin, mica, KH550 coupling agent, and industrial alcohol in a mass ratio of 7:2:0.1:10;

[0061] ③ Winding molding and curing: Install the mold on the winding machine, pour the medium-temperature curing resin glue into the glue tank, lead the high-strength glass fiber yarn out from the tensioner, pass it through the dipping tank, and wind it around the mold mandrel through the winding trolley after splitting the yarn bundle. Adjust the tension, wind the high-strength glass fiber yarn to the expected thickness of 5 mm, put it into the curing furnace, connect the mold to the rotating device in the curing furnace through the connection structure in the curing furnace, close the furnace lid, start the winding machine, and rotate and cure to obtain a shell with an ablation layer on the inner surface and an asymmetric head, as Figure 6 shown; the curing parameters are that the rotation speed during the rotation curing process is 30 - 50 revolutions per minute, and during curing, it is first cured at 75 °C for 1 hour and then heated to 115 °C for 1 hour;

[0062] The medium-temperature curing resin glue is obtained by mixing AG-80 epoxy resin, E-51 epoxy resin, 701 flame retardant, antimony trioxide, and diaminodiphenylmethane-modified dicyandiamide in a mass ratio of 6:5:1:1:5;

[0063] The diaminodiphenylmethane-modified dicyandiamide is obtained by reacting diaminodiphenylmethane and dicyandiamide in a mass ratio of 20:18 at 115 °C for 4 hours;

[0064] ④ Demold to obtain a shell with an ablation layer on the inner surface and an asymmetric head, as Figure 7 shown, and the specific demolding process is as follows:

[0065] Loosen the second positioning set screw 10, remove the second retaining ring 9 and the second positioning ring 18 from the mandrel 7, and then remove the mandrel 7; loosen the first positioning set screw 19, remove the first positioning ring 2, the first retaining ring 3, and the support mandrel 1; disassemble and remove the split-type inner mold 6 from the inner hole formed after being withdrawn from the mandrel 7 to obtain a shell with an ablation layer on the inner surface and an asymmetric head. Example 3

[0066] A method for forming a shell with an ablation layer on the inner surface and an asymmetric head, comprising the following steps:

[0067] ① Assemble the mold with an asymmetric head:

[0068] As Figure 1As shown, the mold with an asymmetric head includes a support mandrel 1 and a mandrel 7. A positioning hole 5 is provided at one end of the support mandrel 1. A positioning post 20 is provided at one end of the mandrel 7. The diameter of the positioning post 20 is smaller than that of the mandrel 7. The positioning post is inserted and fitted with the positioning hole 5.

[0069] A first positioning ring 2 and a first retaining ring 3 are installed on the support mandrel 1. The first retaining ring 3 is located on the side of the first positioning ring 2 close to the positioning hole 5. A first positioning setscrew 19 is provided on the first positioning ring 2.

[0070] A first shell head 4 is arranged between the support mandrel 1 and the mandrel 7. A through hole 17 matching with the positioning post 20 at the end of the mandrel 7 is provided on the first shell head 4. The positioning post passes through the through hole.

[0071] A split inner mold 6, a second shell head 8, a second retaining ring 9 and a second positioning ring 18 are installed on the mandrel 7. The split inner mold 6 is located between the first shell head 4 and the second shell head 8. The split inner mold 6 is composed of a plurality of modules arranged around the mandrel 7. The second retaining ring 9 is located between the second shell head 8 and the second positioning ring 18. A second positioning setscrew 10 is provided on the second positioning ring 18. As Figure 4 and 5 shown, at least three adjusting bolts 11 are provided on both the first positioning ring 2 and the second positioning ring 18. The adjusting bolts 11 axially pass through the positioning ring and are in threaded cooperation with the positioning ring. Each adjusting bolt is evenly distributed along the circumference of its corresponding positioning ring.

[0072] The specific process of assembling the mold with an asymmetric head is as follows:

[0073] Install the first positioning ring 2 on the support mandrel 1, connect the first retaining ring 3, and tighten the first positioning setscrew 19 to fix the first positioning ring 2 on the support mandrel 1.

[0074] Install the first shell head 4 on the positioning post at the end of the mandrel 7, install the positioning post in the positioning hole 5, and then assemble the split inner mold 6 onto the mandrel 7.

[0075] Install the second shell head 8, the second retaining ring 9 and the second positioning ring 18 on the mandrel 7, tighten the second positioning setscrew 10, and fix the second positioning ring 18 on the mandrel 7.

[0076] At least three adjusting bolts 11 are provided on both the first positioning ring 2 and the second positioning ring 18. The adjusting bolts 11 axially pass through the positioning ring and are in threaded cooperation with the positioning ring. Each adjusting bolt is evenly distributed along the circumference of its corresponding positioning ring.

[0077] ② Fabricate the ablation-resistant layer: Apply the mold release agent to the mold, then wrap a layer of PTFE tape around the mold, apply a layer of mold release agent on the PTFE tape, and then evenly brush boron phenolic resin on the mold in sequence, lay a layer of high silica glass fiber cloth, and then brush the boron phenolic resin adhesive on the high silica glass fiber cloth with a brush. Wind a layer of high silica glass fiber yarn impregnated with boron phenolic resin on it, put it into a curing furnace, cure it at 85 °C for 1 hour first, and then raise the temperature to 165 °C and cure it for 2 hours to obtain the ablation-resistant layer;

[0078] The mold release agent is obtained by mixing dimethyl silicone oil, liquid paraffin and toluene in a mass ratio of 5:3:4;

[0079] The boron phenolic resin adhesive is obtained by mixing boron phenolic resin, mica, KH550 coupling agent and industrial alcohol in a mass ratio of 8:3:0.3:10;

[0080] ③ Filament winding forming and curing: Install the mold on the filament winding machine, pour the medium-temperature curing resin adhesive into the glue tank, lead the high-strength glass fiber yarn out of the tensioner, pass through the dipping tank, and wind it around the mold mandrel through the filament winding carriage in a split filament bundle. When winding around the mold mandrel through the filament winding carriage in a split filament bundle, start the winding program to start winding. The width of the yarn sheet is 10 mm, the tension is 150 N, the longitudinal winding angle is 650, 3 tangent points; after the winding thickness reaches 1.5 mm; adjust the process parameters to the yarn sheet width of 10 mm, the tension of 120 N, circumferential winding, after the winding thickness reaches 1.5 mm; adjust the process parameters to the yarn sheet width of 12 mm, the tension of 100 N, the longitudinal winding angle of 550, 5 tangent points, after the winding thickness reaches 1.5 mm; adjust the process parameters to the yarn sheet width of 12 mm, the tension of 80 N, circumferential winding until the winding reaches the expected thickness of 5 mm;

[0081] The medium-temperature curing resin adhesive is obtained by mixing AG-80 epoxy resin, E-51 epoxy resin, 701 flame retardant, antimony trioxide and diaminodiphenylmethane modified dicyandiamide in a mass ratio of 8:5:2:2:7;

[0082] The diaminodiphenylmethane modified dicyandiamide is obtained by reacting diaminodiphenylmethane and dicyandiamide with a mass ratio of 20:27 at 125 °C for 5 hours;

[0083] Put the wound shell into the curing furnace, connect the mold to the rotating device in the curing furnace through the connecting structure in the curing furnace, close the furnace cover, start the filament winding machine, and rotate and cure to obtain a shell with an ablation layer on the inner surface and an asymmetric head; the curing parameters are that the rotation speed during the rotation curing process is 50 revolutions per minute. During curing, cure it at 85 °C for 1.5 hours first, and then raise the temperature to 125 °C and cure it for 2 hours;

[0084] ④ Demold to obtain a shell with an ablation layer on the inner surface and an asymmetric head. The specific demolding process includes the following steps: Loosen the second positioning set screw 10, remove the second retaining ring 9 and the second positioning ring 18 from the mandrel 7, and then remove the mandrel 7; Loosen the first positioning set screw 19, remove the first positioning ring 2, the first retaining ring 3, and the support mandrel 1; Disassemble and remove the split inner mold 6 from the inner hole formed after being withdrawn from the mandrel 7 to obtain a shell with an ablation layer on the inner surface and an asymmetric head. Example 4

[0085] A method for forming a shell with an ablation layer on the inner surface and an asymmetric head includes the following steps:

[0086] ① Assemble the mold with an asymmetric head:

[0087] As Figure 1 shown, the mold with an asymmetric head includes a support mandrel 1 and a mandrel 7. A positioning hole 5 is opened at one end of the support mandrel 1. A positioning post 20 is provided at one end of the mandrel 7. The diameter of the positioning post 20 is smaller than the diameter of the mandrel 7. The positioning post is inserted and fitted with the positioning hole 5; A first positioning ring 2 and a first retaining ring 3 are installed on the support mandrel 1. The first retaining ring 3 is located on the side of the first positioning ring 2 close to the positioning hole 5. A first positioning set screw 19 is provided on the first positioning ring 2; A first shell head 4 is arranged between the support mandrel 1 and the mandrel 7. A through hole 17 is opened on the first shell head 4 and is matched with the positioning post 20 at the end of the mandrel 7. The positioning post passes through the through hole; A split inner mold 6, a second shell head 8, a second retaining ring 9, and a second positioning ring 18 are installed on the mandrel 7. The split inner mold 6 is located between the first shell head 4 and the second shell head 8. The split inner mold 6 is composed of a plurality of modules arranged around the mandrel 7. The second retaining ring 9 is located between the second shell head 8 and the second positioning ring 18. A second positioning set screw 10 is provided on the second positioning ring 18;

[0088] The specific process of assembling the mold with an asymmetric head is as follows:

[0089] Install the first positioning ring 2 on the support mandrel 1, connect the first retaining ring 3, and tighten the first positioning set screw 19 to fix the first positioning ring 2 on the support mandrel 1; Install the first shell head 4 on the positioning post at the end of the mandrel 7, install the positioning post in the positioning hole 5, and then assemble the split inner mold 6 onto the mandrel 7; Install the second shell head 8, the second retaining ring 9, and the second positioning ring 18 on the mandrel 7, and tighten the second positioning set screw 10 to fix the second positioning ring 18 on the mandrel 7;

[0090] At least three adjusting bolts 11 are provided on both the first positioning ring 2 and the second positioning ring 18. The adjusting bolts 11 axially pass through the positioning ring and are threadedly engaged with the positioning ring. Each adjusting bolt is evenly distributed along the circumference of its corresponding positioning ring;

[0091] ② Fabricate the ablation-resistant layer: Apply a release agent to the mold, then wrap a layer of PTFE tape around the mold, apply a release agent on the PTFE tape, and then evenly brush boron phenolic resin on the mold in sequence, lay a layer of high silica glass fiber cloth, and then brush the boron phenolic resin sizing onto the high silica glass fiber cloth with a brush. Wind a layer of high silica glass fiber yarn impregnated with boron phenolic resin on it, and place it in a curing furnace. First cure at 85 °C for 1 hour, then raise the temperature to 165 °C and cure for 2 hours to obtain the ablation-resistant layer;

[0092] The release agent is obtained by mixing dimethyl silicone oil, liquid paraffin and toluene in a mass ratio of 5:2:3;

[0093] The boron phenolic resin sizing is obtained by mixing boron phenolic resin, mica, KH550 coupling agent and industrial alcohol in a mass ratio of 8:2:0.2:10;

[0094] ③ Winding forming and curing: Install the mold on the winding machine, pour medium-temperature curing resin sizing into the glue tank, lead out the high-strength glass fiber yarn from the tensioner, pass it through the dipping tank, and wind it around the mold core through the winding trolley in a split yarn bundle. When winding around the mold core through the winding trolley in a split yarn bundle, start the winding program to start winding. The width of the yarn sheet is 10 mm, the tension is 150 N, the longitudinal winding angle is 650, 3 tangent points; after winding to a thickness of 1.5 mm; adjust the process parameters to a yarn sheet width of 10 mm, a tension of 120 N, circumferential winding, after winding to a thickness of 1.5 mm; adjust the process parameters to a yarn sheet width of 12 mm, a tension of 100 N, a longitudinal winding angle of 550, 5 tangent points, after winding to a thickness of 1.5 mm; adjust the process parameters to a yarn sheet width of 12 mm, a tension of 80 N, circumferential winding until winding to the expected thickness of 5 mm;

[0095] The medium-temperature curing resin sizing is obtained by mixing AG-80 epoxy resin, E-51 epoxy resin, 701 flame retardant, antimony trioxide and diaminodiphenylmethane modified dicyandiamide in a mass ratio of 7:5:1.5:1.5:6;

[0096] The diaminodiphenylmethane modified dicyandiamide is obtained by reacting diaminodiphenylmethane and dicyandiamide with a mass ratio of 1:1 at 120 °C for 4.5 hours;

[0097] Place the wound shell into the curing furnace, connect the mold to the rotating device in the curing furnace through the connection structure in the curing furnace, close the furnace lid, start the winding machine, and rotate and cure to obtain a shell with an ablation layer on the inner surface and an asymmetric head; the curing parameters are that the rotation speed during the rotation curing process is 50 revolutions per minute. First cure at 85 °C for 1.5 hours, then raise the temperature to 125 °C and cure for 2 hours;

[0098] ④ Demold to obtain a shell with an ablation layer on the inner surface and an asymmetric head. The specific demolding process includes the following steps: Loosen the second positioning setscrew 10, remove the second retaining ring 9 and the second positioning ring 18 from the mandrel 7, and then remove the mandrel 7; Loosen the first positioning setscrew 19, remove the first positioning ring 2, the first retaining ring 3, and the support mandrel 1; Disassemble and remove the split inner mold 6 from the inner hole formed after being withdrawn from the mandrel 7 to obtain a shell with an ablation layer on the inner surface and an asymmetric head.

[0099] Examples 1 to 4 were prepared using the same mold. The shell parameters are as follows: The inner diameter of the shell is Ø130 mm, the wall thickness is 5 mm, the head is made of high-strength aluminum alloy, one end head is 80 mm high, the polar hole radius is 30 mm, the other end head is 100 mm high, the polar hole radius is 45 mm, and at 300 mm from the end of the barrel body, there is an ablation-resistant layer formed by 0.7 mm of boron phenolic and high-silica glass fiber on the inner surface.

[0100] The shells with an ablation layer on the inner surface and an asymmetric head obtained in Examples 1 to 4 were tested for pressure-bearing strength, etc. The comparative example was an ablation-resistant shell with a high-strength aluminum metal inner liner and an anti-ablation coating on the inner surface. The results are shown in Table 2.

[0101] The performance of the boron phenolic resin adhesive in Examples 2 to 4 is shown in Table 1. The ablation test was carried out with reference to GJB323A-96.

[0102] Table 1 Performance results of boron phenolic resin adhesive in Examples 2 to 4

[0103]

[0104] It can be seen that the boron phenolic resin adhesive in Examples 2 to 4 has excellent performance and can meet the technical requirements.

[0105] Table 2 Test results of the shells with an ablation layer on the inner surface and an asymmetric head obtained in Examples 1 to 4

[0106]

[0107] The shell with an ablation-resistant layer on the inner surface and an asymmetric head obtained by the present invention has a uniform thickness, good surface finish on the inner surface, no bubbling phenomenon, is easy to demold with a specific demolding agent, and is especially suitable for demolding of molds with an asymmetric structure. From the results in Table 2, it can be seen that the shell with an ablation layer on the inner surface and an asymmetric head obtained by the present invention is light in weight, high in pressure-bearing strength, and excellent in ablation-resistant performance.

Claims

1. A method for forming a shell with an ablative layer on the inner surface and an asymmetric head, characterized in that: It includes the following steps: ① Assemble the mold with an asymmetric head; ② Fabricate the ablation-resistant layer: Apply the release agent to the mold, then wrap a layer of PTFE tape on the mold, apply a layer of release agent on the PTFE tape, then evenly brush boron phenolic resin on the mold in sequence, lay a layer of high silica glass fiber cloth, brush the boron phenolic resin sizing on the high silica glass fiber cloth with a brush, wind a layer of high silica glass fiber yarn impregnated with boron phenolic resin on it, put it into the curing furnace, first cure at 75 - 85 °C for 0.5 - 1 hour, then raise the temperature to 155 - 165 °C and cure for 1 - 2 hours to obtain the ablation-resistant layer; ③ Winding forming and curing: Install the mold on the winding machine, pour the medium-temperature curing resin sizing into the sizing tank, lead out the high-strength glass fiber yarn from the tensioner, pass it through the sizing tank, and wind it around the mold mandrel in split yarn bundles through the winding carriage, adjust the tension, wind the high-strength glass fiber yarn to the expected thickness of 5 mm, put it into the curing furnace, connect the mold with the rotating device in the curing furnace through the connection structure in the curing furnace, close the furnace lid, start the winding machine, and rotate and cure to obtain a shell with an ablation layer on the inner surface and an asymmetric head; The curing parameters are that the rotation speed during the rotation curing process is 30 - 50 revolutions per minute, and during curing, first cure at 75 - 85 °C for 1 - 1.5 hours, then raise the temperature to 115 - 125 °C and cure for 1 - 2 hours; ④ Demold to obtain a shell with an ablation layer on the inner surface and an asymmetric head; The boron phenolic resin sizing is obtained by mixing boron phenolic resin, mica, KH550 coupling agent and industrial alcohol according to the mass ratio of 7 - 8:2 - 3:0.1 - 0.3:10; The medium-temperature curing resin sizing is obtained by mixing AG-80 epoxy resin, E-51 epoxy resin, 701 flame retardant, antimony trioxide and dicyandiamide modified by diaminodiphenylmethane according to the mass ratio of 6 - 8:5:1 - 2:1 - 2:5 - 7; The dicyandiamide modified by diaminodiphenylmethane is obtained by reacting diaminodiphenylmethane and dicyandiamide with a mass ratio of 200:180 - 270 at 115 - 125 °C for 4 - 5 hours; 2. A method for forming a housing with an ablative layer on the inner surface and an asymmetric head, according to claim 1, characterized in that: The mold with an asymmetric head includes a support mandrel (1) and a mandrel (7). A positioning hole (5) is opened at one end of the support mandrel (1), and a positioning post (20) is provided at one end of the mandrel (7). The diameter of the positioning post (20) is smaller than the diameter of the mandrel (7), and the positioning post is in plug-in fit with the positioning hole (5); A first positioning ring (2) and a first retaining ring (3) are installed on the support mandrel (1). The first retaining ring (3) is located on the side of the first positioning ring (2) close to the positioning hole (5), and a first positioning set screw (19) is provided on the first positioning ring (2); A first shell head (4) is arranged between the support mandrel (1) and the mandrel (7). A through hole (17) matching with the positioning post (20) at the end of the mandrel (7) is opened on the first shell head (4), and the positioning post passes through the through hole; A split-type internal mold (6), a second shell head (8), a second retaining ring (9) and a second positioning ring (18) are installed on a mandrel (7). The split-type internal mold (6) is located between the first shell head (4) and the second shell head (8). The split-type internal mold (6) is composed of a plurality of modules arranged around the mandrel (7). The second retaining ring (9) is located between the second shell head (8) and the second positioning ring (18). A second positioning setscrew (10) is provided on the second positioning ring (18).

3. A method for forming a housing with an ablation layer on the inner surface and an asymmetric head, according to claim 2, characterized in that: At least 3 adjusting bolts (11) are provided on both the first positioning ring (2) and the second positioning ring (18). The adjusting bolts (11) axially pass through the positioning ring and are in threaded cooperation with the positioning ring. Each adjusting bolt is evenly distributed along the circumference of its corresponding positioning ring.

4. A method for forming a housing with an ablation layer on the inner surface and an asymmetric head, according to claim 2, characterized in that: The process of assembling the mold with asymmetric heads is as follows: Install the first positioning ring (2) on the support mandrel (1), connect the first retaining ring (3), and tighten the first positioning setscrew (19) to fix the first positioning ring (2) on the support mandrel (1). Install the first shell head (4) on the positioning post at the end of the mandrel (7), install the positioning post in the positioning hole (5), and then assemble the split-type internal mold (6) onto the mandrel (7). Install the second shell head (8), the second retaining ring (9) and the second positioning ring (18) on the mandrel (7), and tighten the second positioning setscrew (10) to fix the second positioning ring (18) on the mandrel (7).

5. A method for forming a housing with an ablative layer on the inner surface and an asymmetric head, according to claim 4, characterized in that: The demolding process is as follows: Loosen the second positioning setscrew (10), remove the second retaining ring (9) and the second positioning ring (18) from the mandrel (7), and then remove the mandrel (7). Loosen the first positioning setscrew (19), remove the first positioning ring (2), the first retaining ring (3), and the support mandrel (1). Disassemble and remove the split-type internal mold (6) from the inner hole formed after being withdrawn from the mandrel (7) to obtain a shell with an ablated layer on the inner surface and asymmetric heads.

6. A method for forming a housing with an ablative layer on the inner surface and an asymmetric head, according to claim 1, characterized in that: The mold release agent is obtained by mixing dimethyl silicone oil, liquid paraffin and toluene in a mass ratio of 5:1~3:2~4.

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