Method for forming heat-insulating layer of diffusion section of solid rocket engine nozzle

Abstract

The present application relates to the field of aerospace solid rocket engine manufacturing, and discloses a forming method of a solid rocket engine nozzle diffuser section heat insulation layer, comprising the following steps: winding mold installation, carbon layer winding, machining, high-silicon oxygen heat insulation layer winding, vacuum bag sealing, curing, vacuum bag cleaning, and demolding and then machining to the size of the diffuser section heat insulation layer blank. The forming method of the solid rocket engine nozzle diffuser section heat insulation layer can avoid frequent replacement of different width pre-impregnated fiber cloth strips during pre-impregnated carbon fiber cloth strip winding, effectively improves the production efficiency of the diffuser section heat insulation layer, and meets the size and performance requirements of the product.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aerospace solid rocket engine manufacturing technology, in particular to a kind of solid rocket engine nozzle diffusion section heat insulation layer forming method. BACKGROUND

[0002] The diffusion section heat insulation layer is an important component of the nozzle of the solid rocket engine. During the operation of the engine, the diffusion section heat insulation layer of the nozzle needs to provide a stable aerodynamic interface under the scouring action of high-temperature and high-condensed-phase component gas flow to ensure the thrust conversion efficiency of the engine. At the same time, the diffusion section heat insulation layer of the nozzle also needs to have good heat insulation performance to ensure that the surface temperature is lower than 160℃ under the action of high-temperature combustion gas for a long time, thereby ensuring the reliability of the engine operation.

[0003] With the rapid development of the market for advanced functional composite materials, more and more composite material preparation technologies have emerged. For reinforced fiber type composite materials, the quality and performance indicators of the finished product are greatly affected by the forming process technology.

[0004] The diffusion section heat insulation layer of a certain type of solid rocket engine nozzle is formed by using a prepreg fiber cloth tape winding process. A carbon cloth / high-silica cloth reinforced phenolic resin composite winding product is formed by using carbon cloth / phenolic as an ablation layer and high-silica cloth / phenolic as a heat insulation layer. Figure 2 As shown in the figure, the inner and outer surface cone angles of the ablation-resistant carbon layer are α and β, respectively. Thickness size requirements are proposed for the carbon layer at the small end face, 65mm, 125mm, and 205mm away from the small end face, and the large end face. Due to the large width variation span of the prepreg fiber cloth tape, the process is complex and inefficient. Moreover, the smaller the width of the prepreg fiber cloth tape, the more likely it is to slip during winding, making it difficult to ensure the thickness of the carbon layer, and the product yield is low. SUMMARY

[0005] The purpose of the present application is to overcome the above technical deficiencies and provide a solid rocket engine nozzle diffusion section heat insulation layer forming method that eliminates the need to frequently replace prepreg fiber cloth tapes of different widths during winding, effectively improves the production efficiency of the diffusion section heat insulation layer, and meets the product size and performance requirements.

[0006] To achieve the above purpose, the solid rocket engine nozzle diffusion section heat insulation layer forming method designed by the present application includes the following steps:

[0007] A) winding mold installation: clamp the winding mold to the numerical control prepreg fiber cloth tape winding machine, and evenly apply release agent on the working surface after clamping is completed;

[0008] B) carbon layer winding: winding the carbon fiber prepreg tape to form the carbon layer from the small end of the winding mold, the carbon fiber prepreg tape is wound into the winding mold with a width of b1 before the middle position of the winding mold, and then b2, b1 > b2;

[0009] C) machining: machining the outer surface of the carbon layer to leave a compression allowance of 1-2 mm in the thickness direction of the carbon layer;

[0010] D) high-silicon oxygen insulation layer winding: winding the high-silicon oxygen fiber prepreg tape from the small end of the carbon layer to form a high-silicon oxygen insulation layer;

[0011] E) vacuum bag sealing: placing the winding mold with the carbon layer and high-silicon oxygen insulation layer into a vacuum bag for sealing;

[0012] F) curing;

[0013] G) cleaning the vacuum bag and demolding to machine to the size of the diffusion section insulation layer blank.

[0014] Preferably, in step A), the impurities on the surface of the winding mold are removed, and the radial roundness runout of the winding mold is detected to be not more than 0.2 mm, and the detection positions include three cross sections of the small end, the middle and the large end of the winding mold.

[0015] Preferably, in step B), when winding the carbon layer, the winding mold is preheated to 30-40°C, the winding tension is 3-5 N / mm, the hot roller temperature is room temperature-70°C, and the pressure roller pressure is 6-8 N / mm.

[0016] Preferably, in step B), the thickness of the carbon layer from the small end to the middle position of the winding mold is h1, and then h2, h1 > h2, and the thickness of the carbon layer at each point is greater than the thickness of the corresponding position of the carbon layer in the finished product of the diffusion section insulation layer, and the inner surface taper of the carbon layer is α, b1 = h1 / sinα, b2 = h2 / sinα.

[0017] Preferably, in step C), according to the thickness requirement of the finished product of the diffusion section insulation layer, the outer contour line of the carbon layer in the finished product of the diffusion section insulation layer is formed, and after machining, the thickness of the carbon layer has an outward extension of 1-2 mm relative to the outer contour line

[0018] Preferably, in step C), when machining, the first tool rotates at a speed of S150 rpm, and the feed amount is F15 mm / min, the second tool starts to rotate at a speed of S100 rpm, and the initial feed amount is F10 mm / min, and then uniformly decreases, and when machining to the large end, the speed is S70 rpm, and the feed amount is F7 mm / min.

[0019] Preferably, in the step D), the winding tension is 1-2 N / mm, the hot roller temperature is room temperature-70°C, the pressure roller pressure is 3-4 N / mm, the width of the prepreg carbon fiber cloth tape is b3, the thickness of the high-silica thermal insulation layer is h3, the outer surface taper of the carbon layer in the finished product of the diffusion section thermal insulation layer is β, and b3 = h3 / sin β.

[0020] Preferably, in the step D), a release ring with a thickness of 20-30 mm is wound around the tail of the large end of the winding mold after the winding is completed.

[0021] Preferably, in the step E), the hot press tank vacuum connection nozzle is embedded into the vacuum bag, the vacuum pipe is connected to the hot press tank vacuum connection nozzle embedded in the vacuum bag, the vacuum pump is opened for vacuumizing treatment, the vacuum degree is extracted to ≤-0.09 MPa, the vacuum pump is closed, the vacuum degree is checked after 15 minutes, and if it is greater than -0.09 MPa, the vacuum bag is checked to find the air leakage point, sealed, and then the vacuum pump is opened again for vacuumizing, and the vacuum bag is checked to see if it is completely sealed, and the checking and sealing are repeated until the vacuum degree is ≤-0.09 MPa and stable without decline after the vacuum pump is closed for 15 minutes.

[0022] Preferably, in the step F), the vacuum degree of the vacuum bag is kept ≤-0.09 MPa during the whole curing temperature rising and holding stage, the vacuum is stopped after the 165°C holding is completed, the initial pressure of 0.8-1 MPa is added at the beginning of the curing, the full pressure of 2.3-2.5 MPa is added after the 80°C holding for 60 min is completed, the natural pressure reduction is performed after the 165°C holding is completed, and the temperature control is as follows:

[0023] Room temperature-60°C, 60°C holding for 60 min;

[0024] 60°C-80°C, 80°C holding for 60 min;

[0025] 80°C-100°C, 100°C holding for 120 min;

[0026] 100°C-120°C, 120°C holding for 120 min;

[0027] 120°C-165°C, 165°C holding for 120 min;

[0028] The temperature rising rate is 0.2°C / min, the curing holding is completed, the temperature decreasing rate is 0.3°C / min to ≤60°C, and the furnace is discharged.

[0029] Compared with the prior art, the present application has the following advantages: a machining process is added after the carbon layer winding is completed, so that the prepreg carbon fiber cloth tape does not need to be frequently replaced during the winding, and the carbon layer thickness size after curing can be effectively guaranteed, thereby improving the product qualification rate and production efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 Fig. 1 is a schematic view of the forming structure of the diffusion section thermal insulation layer in the present application;

[0031] Figure 2 Fig. 2 is a schematic view of the forming structure of the diffusion section thermal insulation layer in the prior art.

[0032] The reference signs of the components in the figures are as follows:

[0033] Winding mold 1, carbon layer 2, high-silica thermal insulation layer 3. DETAILED DESCRIPTION

[0034] The present application will be further described in detail below in combination with the drawings and specific examples.

[0035] Example 1

[0036] A forming method of the diffusion section thermal insulation layer of a solid rocket engine nozzle, comprising the following steps:

[0037] A) Winding mold 1 installation: as shown in the figure, the winding mold 1 is clamped to the numerical control pre-impregnated fiber cloth winding machine, and after the clamping is completed, the release agent is evenly applied on the working surface; Figure 1

[0038] B) Carbon layer 2 winding: the pre-impregnated carbon fiber cloth tape is wound from the small end of the winding mold 1 to form the carbon layer 2, the pre-impregnated carbon fiber cloth tape is wound along the axial direction to the width b1 before the middle position of the winding mold 1, and then to b2, b1 > b2;

[0039] C) Machining: the outer surface of the carbon layer 2 is machined to leave a compression allowance of 1-2 mm in the thickness direction of the carbon layer 2;

[0040] D) High-silica thermal insulation layer 3 winding: the pre-impregnated high-silica fiber cloth tape is wound from the small end outside the carbon layer 2 to form the high-silica thermal insulation layer 3;

[0041] E) Vacuum bag sealing: the winding mold 1 with the wound carbon layer 2 and high-silica thermal insulation layer 3 is placed into a vacuum bag for sealing;

[0042] F) Curing;

[0043] G) Cleaning the vacuum bag, and machining after demolding to the size of the diffusion section thermal insulation layer blank.

[0044] Example 2

[0045] A forming method of the diffusion section thermal insulation layer of a solid rocket engine nozzle, comprising the following steps:

[0046] ​A) winding mold 1 installation: the winding mold 1 is clamped to the numerical control pre-impregnated fiber cloth tape winding machine, the surface impurities of the winding mold 1 are removed, the radial round runout of the winding mold 1 is detected to be not more than 0.2 mm, the detection positions include three cross sections of the small end, the middle and the large end of the winding mold 1, and the release agent is evenly applied on the working surface after the clamping is completed;

[0047] B) carbon layer 2 winding: the pre-impregnated carbon fiber cloth tape is wound from the small end of the winding mold 1 to form the carbon layer 2, when the carbon layer 2 is wound, the winding mold 1 is first preheated to 30 DEG C, the winding tension is 3 N / mm, the hot roller temperature is 70 DEG C, the pressure roller pressure is 6 N / mm, the width of the pre-impregnated carbon fiber cloth tape is b1 before being wound into the middle position of the winding mold 1 along the axial direction, and is b2 thereafter, b1 > b2, the thickness of the carbon layer 2 between the small end and the middle position of the winding mold 1 is h1, and the thickness thereafter is h2, h1 > h2, and the thickness of the carbon layer 2 at each point is greater than the thickness of the corresponding position of the carbon layer 2 in the finished product of the diffusion section thermal insulation layer, the inner profile taper of the carbon layer 2 is alpha, b1 = h1 / sin alpha, and b2 = h2 / sin alpha;

[0048] C) machining: the carbon layer 2 is machined to have a 1 mm compression allowance in the thickness direction, specifically, according to the requirement of the thickness of the finished product of the diffusion section thermal insulation layer, the outer contour line of the carbon layer 2 in the finished product of the diffusion section thermal insulation layer is formed, and after the machining, the thickness of the carbon layer 2 has a 1 mm outward extension relative to the outer contour line;

[0049] D) high-silica thermal insulation layer 3 winding: the pre-impregnated high-silica fiber cloth tape is wound from the small end outside the carbon layer 2 to form the high-silica thermal insulation layer 3, the winding tension is 1 N / mm, the hot roller temperature is about 70 DEG C, the pressure roller pressure is 3 N / mm, the width of the pre-impregnated high-silica fiber cloth tape is b3, the thickness of the high-silica thermal insulation layer 3 is h3, the outer profile taper of the carbon layer 2 in the finished product of the diffusion section thermal insulation layer is beta, and b3 = h3 / sin beta;

[0050] E) vacuum bag sealing: the winding mold 1 with the wound carbon layer 2 and high-silica thermal insulation layer 3 is placed into a vacuum bag for sealing, a hot press tank is connected to the vacuum bag, a vacuum pump is connected to the hot press tank, and the vacuum pump is started to perform vacuumizing treatment, the vacuum degree is less than or equal to -0.09 MPa, the vacuum pump is stopped, and after 15 minutes, the vacuum degree is checked to be less than or equal to -0.09 MPa, if the vacuum degree is greater than -0.09 MPa, the vacuum bag is checked to find the air leakage point, the air leakage point is sealed, the vacuum pump is started again to perform vacuumizing treatment, and the vacuum bag is checked to see whether it is completely sealed, the checking and sealing are repeated until the vacuum degree is less than or equal to -0.09 MPa and stable without decline after the vacuum pump is stopped for 15 minutes;

[0051] F) curing, curing temperature and holding phase throughout the vacuum bag to maintain the vacuum degree of ≤-0.09MPa, 165℃ holding end stop vacuum, curing starts to add initial pressure 0.8MPa, 80℃ holding 60min end to add full pressure 2.3MPa, 165℃ holding end natural pressure drop, temperature control as follows:

[0052] Room temperature ~ 60℃, 60℃ holding 60min;

[0053] 60℃ ~ 80℃, 80℃ holding 60min;

[0054] 80℃ ~ 100℃, 100℃ holding 120min;

[0055] 100℃ ~ 120℃, 120℃ holding 120min;

[0056] 120℃ ~ 165℃, 165℃ holding 120min;

[0057] Ramp rate 0.2℃ / min, curing holding end, cooling rate 0.3℃ / min to ≤60℃ out of the furnace;

[0058] G) clean the vacuum bag, demoulding machine to the diffusion section of the insulation layer of the blank size.

[0059] Example 3

[0060] A method for forming a diffusion section of the insulation layer of a solid rocket engine nozzle, comprising the following steps:

[0061] A) winding mold 1 installation: the winding mold 1 is clamped to the numerical control pre-impregnated fiber cloth winding machine, the impurities on the surface of the winding mold 1 are removed, the radial roundness runout of the winding mold 1 is detected to be not more than 0.2mm, the detection position includes three cross sections of the small end, the middle and the large end of the winding mold 1, and the release agent is uniformly applied on the working surface after the clamping is completed;

[0062] B) carbon layer 2 winding: the pre-impregnated carbon fiber cloth tape is wound from the small end of the winding mold 1 to form the carbon layer 2, when the carbon layer 2 is wound, the winding mold 1 is preheated to 40℃, the winding tension is 5N / mm, the hot roller temperature is room temperature ℃, the pressure roller pressure is 8N / mm, the pre-impregnated carbon fiber cloth tape is wound along the axial direction to the width b1 before the middle position of the winding mold 1, and then to b2, b1 > b2, the thickness of the carbon layer 2 from the small end to the middle position of the winding mold 1 is h1, and the thickness after that is h2, h1 > h2, and the thickness of the carbon layer 2 at each point is greater than the thickness of the corresponding position of the carbon layer 2 in the finished product of the diffusion section of the insulation layer, the inner taper of the carbon layer 2 is α, b1 = h1 / sinα, b2 = h2 / sinα;

[0063] C) Machining: machining the outer surface of the carbon layer 2 to leave a 2mm compression allowance in the thickness direction of the carbon layer 2, specifically, forming the outer contour line of the carbon layer 2 in the finished product of the diffusion section thermal insulation layer according to the requirement of the thickness of the finished product of the diffusion section thermal insulation layer, after machining, the thickness of the carbon layer 2 has a 2mm outward extension relative to the outer contour line;

[0064] D) High-silica insulation layer 3 winding: winding the pre-impregnated high-silica fiber cloth tape from the small end of the carbon layer 2 to form the high-silica insulation layer 3, the winding tension is 2N / mm, the hot roller temperature is room temperature, the pressure roller pressure is 4N / mm, the width of the pre-impregnated high-silica fiber cloth tape is b3, the thickness of the high-silica insulation layer 3 is h3, the taper of the outer surface of the carbon layer 2 in the finished product of the diffusion section thermal insulation layer is β, b3 = h3 / sinβ, after winding, a release ring with a thickness of 20mm is wound around the tail of the large end of the winding mold 1;

[0065] E) Vacuum bag sealing: place the winding mold 1 with the carbon layer 2 and the high-silica insulation layer 3 wound thereon into a vacuum bag, embed the hot press tank vacuum connection nozzle into the vacuum bag, connect the vacuum pump to the hot press tank vacuum connection nozzle embedded in the vacuum bag, open the vacuum pump for vacuumizing, vacuumize to a vacuum degree of ≤-0.09MPa, close the vacuum pump, check the vacuum degree after 15 minutes, if it is greater than -0.09MPa, check the vacuum bag, find the air leakage point, seal it, open the vacuum pump again after sealing to check if the vacuum bag is completely sealed, repeat the checking and sealing until the vacuum degree is ≤-0.09MPa and stable without decline after closing the vacuum pump for 15 minutes;

[0066] F) Curing, the vacuum degree of the vacuum bag is maintained at ≤-0.09MPa during the whole process of curing temperature rising and holding, stop vacuumizing after 165℃ holding is finished, start curing with an initial pressure of 1MPa, hold at 80℃ for 60min, then add a full pressure of 2.5MPa, naturally reduce the pressure after 165℃ holding is finished, the temperature control is as follows:

[0067] Room temperature ~ 60℃, hold at 60℃ for 60min;

[0068] 60℃ ~ 80℃, hold at 80℃ for 60min;

[0069] 80℃ ~ 100℃, hold at 100℃ for 120min;

[0070] 100℃ ~ 120℃, hold at 120℃ for 120min;

[0071] 120℃ ~ 165℃, hold at 165℃ for 120min;

[0072] Rising rate 0.2℃ / min, cooling rate 0.3℃ / min to ≤60℃ and discharge;

[0073] G) Clean the vacuum bag, and machine the diffusion section insulation layer blank to the size of the product after demolding.

[0074] Example 4

[0075] A solid rocket engine nozzle diffusion section insulation layer forming method, comprising the following steps:

[0076] A) winding mold 1 installation: the winding mold 1 is clamped to the numerical control pre-impregnated fiber cloth winding machine, the surface impurities of the winding mold 1 are removed, the radial roundness runout of the winding mold 1 is detected to be not more than 0.2mm, the detection positions include three cross sections of the small end, the middle and the large end of the winding mold 1, and the release agent is evenly applied on the working surface after the clamping is completed;

[0077] B) carbon layer 2 winding: the pre-impregnated carbon fiber cloth tape is wound from the small end of the winding mold 1 to form the carbon layer 2, when the carbon layer 2 is wound, the winding mold 1 is preheated to 35℃, the winding tension is 4N / mm, the hot roller temperature is 55℃, the pressure roller pressure is 7N / mm, the pre-impregnated carbon fiber cloth tape is axially wound to the width b1 before the middle position of the winding mold 1, and then to b2, b1>b2, the thickness of the carbon layer 2 from the small end to the middle position of the winding mold 1 is h1, and the thickness after that is h2, h1>h2, and the thickness of the carbon layer 2 at each point is greater than the thickness of the corresponding position of the carbon layer 2 in the diffusion section insulation layer product, the inner profile taper of the carbon layer 2 is α, b1=h1 / sinα, b2=h2 / sinα;

[0078] C) machining: the outer profile of the carbon layer 2 is machined to leave a 1mm compression allowance in the thickness direction of the carbon layer 2, specifically, according to the thickness requirement of the diffusion section insulation layer product, the outer contour line of the carbon layer 2 in the diffusion section insulation layer product is formed, and after the machining, the thickness of the carbon layer 2 has a 1mm outward extension relative to the outer contour line;

[0079] D) high-silicon oxygen insulation layer 3 winding: the pre-impregnated high-silicon oxygen fiber cloth tape is wound from the small end outside the carbon layer 2 to form the high-silicon oxygen insulation layer 3, the winding tension is 2N / mm, the hot roller temperature is 55℃, the pressure roller pressure is 3N / mm, the width of the pre-impregnated high-silicon oxygen fiber cloth tape is b3, the thickness of the high-silicon oxygen insulation layer 3 is h3, the outer profile taper of the carbon layer 2 in the diffusion section insulation layer product is β, b3=h3 / sinβ, and a 30mm demolding ring is ring-wound at the tail of the large end of the winding mold 1 after the winding is completed;

[0080] E) Vacuum bag sealing: Place the winding mold 1 wrapped with the carbon layer 2 and the high-silicon oxide thermal insulation layer 3 into a vacuum bag for sealing. Pre-embed the autoclave vacuum nozzle in the vacuum bag. Connect the vacuum pipe to the pre-embedded autoclave vacuum nozzle in the vacuum bag. Turn on the vacuum pump to evacuate until the vacuum degree is ≤-0.09 MPa. Turn off the vacuum pump. After 15 minutes, check that the vacuum degree is ≤-0.09 MPa. If it is greater than -0.09 MPa, check the vacuum bag to find the leak point and seal it. After sealing, turn on the vacuum pump again to evacuate and check whether the vacuum bag is completely sealed. Repeat the inspection and sealing until the vacuum degree is ≤-0.09 MPa 15 minutes after turning off the vacuum pump and is stable without decreasing.

[0081] F) Curing: During the whole process of curing temperature rise and heat preservation, the vacuum degree of the vacuum bag should be kept ≤-0.09MPa. After the end of 165℃ heat preservation, stop vacuuming. At the beginning of curing, add initial pressure of 0.9MPa. After the end of 60min heat preservation at 80℃, add full pressure of 2.4MPa. After the end of 165℃ heat preservation, the pressure will be naturally reduced. The temperature control is as follows:

[0082] Room temperature ~ 60℃, keep warm at 60℃ for 60min;

[0083] 60℃~80℃, keep warm at 80℃ for 60min;

[0084] 80℃~100℃, keep warm at 100℃ for 120min;

[0085] 100℃~120℃, keep warm at 120℃ for 120min;

[0086] 120℃~165℃, keep warm at 165℃ for 120min;

[0087] The heating rate is 0.2℃ / min, and after the curing and heat preservation is completed, the cooling rate is 0.3℃ / min to ≤60℃ and then the oven is opened;

[0088] G) Clean the vacuum bag, clamp and align the outer diameters of the large and small ends of the winding mold 1, machine the large and small end faces and outer diameter of the diffusion section insulation layer to see the light, retain the demoulding step, and after demoulding, machine it to the size of the diffusion section insulation layer blank.

Claims

1. A method for forming a thermal insulation layer of a solid rocket engine nozzle diffuser, characterized by: The steps include: A) Installation of the winding mold (1): Clamp the winding mold (1) to the CNC prepreg fiber tape winding machine, and evenly apply a release agent on the working surface after clamping; B) Winding of the carbon layer (2): Starting from the small end of the winding mold (1), the pre-impregnated carbon fiber tape is wound to form the carbon layer (2), the width of the pre-impregnated carbon fiber tape before being wound axially to the middle position of the winding mold (1) is b1, and the width thereafter is b2, b1>b2, the thickness of the carbon layer (2) between the small end and the middle position of the winding mold (1) is h1, and the thickness thereafter is h2, h1>h2, and the thickness of the carbon layer (2) at each point is greater than the thickness of the carbon layer (2) at the corresponding position in the finished product of the diffusion section insulation layer, the inner surface taper of the carbon layer (2) is α, b1=h1 / sinα, b2=h2 / sinα; C) Machining: machining the outer surface of the carbon layer (2) so that the carbon layer (2) has a compression margin of 1 to 2 mm in the thickness direction. When machining, starting from the small end of the winding mold (1), the first knife speed is S150 rpm, the feed rate is F15 mm / min, the second knife starts with a speed of S100 rpm, the start feed rate is F10 mm / min, and then the speed is gradually reduced. When machining to the large end, the speed is S70 rpm, and the feed rate is F7 mm / min. D) Winding the high silica thermal insulation layer (3): Winding a pre-impregnated high silica fiber cloth tape outside the carbon layer (2) from the small end to form the high silica thermal insulation layer (3); E) Vacuum bag sealing: Place the winding mold (1) wrapped with the carbon layer (2) and the high silicon oxide thermal insulation layer (3) into a vacuum bag for sealing, embed the autoclave vacuum nozzle into the vacuum bag, connect the vacuum pipe to the autoclave vacuum nozzle embedded in the vacuum bag, turn on the vacuum pump for vacuuming, and evacuate to a vacuum degree of ≤-0.09 MPa. Turn off the vacuum pump, check the vacuum degree after 15 minutes to ≤-0.09 MPa. If it is greater than -0.09 MPa, check the vacuum bag to find the leak point and seal it. After sealing, turn on the vacuum pump again to evacuate and check whether the vacuum bag is completely sealed. Repeat the inspection and sealing until the vacuum degree is ≤-0.09 MPa 15 minutes after turning off the vacuum pump and is stable without decreasing. F) curing; G) Clean the vacuum bag, demould and machine to the size of the diffusion section insulation layer blank.

2. The method for forming the thermal insulation layer of the nozzle diffuser section of a solid rocket motor according to claim 1, characterized in that: In the step A), impurities on the surface of the winding mold (1) are removed, and the radial runout of the winding mold (1) is detected to be no greater than 0.2 mm. The detection positions include three sections of the winding mold (1), namely, the small end, the middle part, and the large end.

3. The method for forming the thermal insulation layer of the nozzle diffuser section of a solid rocket motor according to claim 1, characterized in that: In the step B), when winding the carbon layer (2), the winding mold (1) is first preheated to 30-40°C, the winding tension is 3-5N / mm, the hot roller temperature is room temperature to 70°C, and the pressure roller pressure is 6-8N / mm.

4. The method for forming the thermal insulation layer of the nozzle diffuser of a solid rocket motor according to claim 1, wherein: In the step C), the outer contour line of the carbon layer (2) in the finished product of the diffusion section insulation layer is formed according to the requirements for the thickness of the finished product of the diffusion section insulation layer. After machining, the thickness of the carbon layer (2) extends outward from the outer contour line by 1 to 2 mm.

5. The method for forming the thermal insulation layer of the nozzle diffuser of a solid rocket motor according to claim 1, characterized in that: In the step D), the winding tension is 1-2 N / mm, the temperature of the hot roller is room temperature to 70°C, the pressure of the pressing roller is 3-4 N / mm, the width of the pre-impregnated high-silica fiber cloth is b3, the thickness of the high-silica thermal insulation layer (3) is h3, the outer surface taper of the carbon layer (2) in the finished product of the diffusion section thermal insulation layer is β, and b3=h3 / sinβ.

6. The method for forming the thermal insulation layer of the nozzle diffuser of a solid rocket motor according to claim 1, characterized in that: In the step D), after the winding is completed, a demoulding ring with a thickness of 20 to 30 mm is wound around the tail of the large end of the winding mold (1).

7. The method for forming the thermal insulation layer of the nozzle diffuser of a solid rocket motor according to claim 1, characterized in that: In the step F), the vacuum degree of the vacuum bag is maintained at ≤-0.09 MPa during the entire curing temperature rise and insulation stage. After the insulation at 165°C is completed, the vacuum is stopped. An initial pressure of 0.8-1 MPa is applied at the beginning of curing. After the insulation at 80°C for 60 minutes, a full pressure of 2.3-2.5 MPa is applied. After the insulation at 165°C is completed, the pressure is naturally reduced. The temperature is controlled as follows: Room temperature ~ 60℃, keep warm at 60℃ for 60min; 60℃~80℃, keep warm at 80℃ for 60min; 80℃~100℃, keep warm at 100℃ for 120min; 100℃~120℃, keep warm at 120℃ for 120min; 120℃~165℃, keep warm at 165℃ for 120min; The heating rate is 0.2℃ / min. After the curing and heat preservation is completed, the cooling rate is 0.3℃ / min to ≤60℃ and then the product is taken out of the oven.

Images