Pressure tank and impregnation method of three-dimensional woven preform

Abstract

The invention discloses a pressure tank body and a gum dipping method of a three-dimensional woven preform. The pressure tank body comprises a cover, a tank body, gum dipping holes, an air exhaust hole, an air exhaust gum dipping pipe, an air exhaust hole, a liquid injection hole, a sealing layer and an air injection hole, the cover is arranged on the tank body in a sealing manner; the gum dipping hole, the air suction hole, the exhaust hole, the liquid injection hole and the air injection hole are all formed in the cover; the air exhaust gum dipping pipe is arranged in the tank body and used for winding the three-dimensional woven prefabricated body, the sealing layer covers the outer sides of the air exhaust gum dipping pipe and the three-dimensional woven prefabricated body, one end of the air exhaust gum dipping pipe is connected with the gum dipping hole, and the other end of the air exhaust gum dipping pipe is connected with the air exhaust hole. According to the characteristic that the boiling point of water is reduced along with pressure, water in the preform can be rapidly and thoroughly removed through heating, vacuumizing and drying, the preform is properly pressed in advance during gum dipping by pressurizing the exterior of the preform so as to reduce the filling power of the preform, the excessive gum content is avoided, and wrinkles after curing can be remarkably reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials, and in particular relates to a method for dipping a pressure tank body and a three-dimensional braided preform. Background Art

[0002] The anti-ablation lining of the solid rocket engine nozzle and the outer insulation layer of the hypersonic vehicle were originally wrapped with pre-impregnated carbon fiber tape and high-silica tape. In order to adapt to the higher temperature of modern propellants, the anti-ablation lining is increasingly changed to carbon fiber and quartz fiber three-dimensional woven preforms. Due to the high elasticity and low fiber volume density of carbon fiber and quartz fiber three-dimensional woven preforms, the glue content is too high after conventional vacuum dipping. After the subsequent pre-impregnated high-silica tape winding and pressure tank curing, the preform and the high-silica tape winding layer of the subsequent process will have serious wrinkles, which seriously affects the product quality and qualified rate. In addition, in the three-dimensional weaving process of the fiber preform, in order to soften the fiber bundle, it is necessary to spray the fiber with water. Because the sizing agent of the fiber pre-impregnation cannot be cured, the heating temperature generally does not exceed 90°C, so the drying method often cannot be completely dried, resulting in insufficient dipping. Summary of the invention

[0003] The object of the present invention is to provide a method for dipping a pressure tank and a three-dimensional braided preform to solve the above problems.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A pressure tank body comprises a cover, a tank body, a glue dipping hole, an air extraction hole, a glue dipping tube, an exhaust hole, a liquid injection hole, a sealing layer and an air injection hole; the cover is sealingly arranged on the tank body, and the glue dipping hole, the air extraction hole, the exhaust hole, the liquid injection hole and the air injection hole are all arranged on the cover; the glue dipping tube is arranged inside the tank body, and a side hole section with the glue dipping hole is wound from bottom to top on the outside of a three-dimensional woven preform, and is airtightly coated with a vacuum film and a vacuum tape and the glue dipping tube wound on the outside thereof, and one end of the glue dipping tube from the bottom of the preform is connected to the glue dipping hole, and the other end is connected to the air extraction hole.

[0005] Furthermore, the vacuum impregnation tube includes a glue impregnation port section, a side hole section and an air exhaust port section, which are connected in sequence. The side hole section is used for winding the three-dimensional woven preform, and a glue impregnation hole is opened on the side hole section; the glue impregnation port of the glue impregnation port section is connected to the glue impregnation hole, and the air exhaust port of the air exhaust port section is connected to the air exhaust hole.

[0006] Furthermore, the sealing layer includes a vacuum film and a vacuum tape, and the vacuum film is sealed and adhered to the core mold of the three-dimensional braided preform by the vacuum tape.

[0007] Furthermore, the injection hole is connected to a high-pressure water pump through a pipeline, and a water injection valve, a water pressure gauge and a temperature gauge are arranged on the pipeline.

[0008] Furthermore, the air injection hole is connected to an air compressor through a pipeline, and a pressure gauge and an air injection valve are arranged on the pipeline.

[0009] Furthermore, the glue dipping hole is connected to a glue injection pump, and the air extraction hole is connected to a vacuum pump through a pipeline and an air extraction valve.

[0010] Furthermore, a sealing ring is provided between the cover and the tank body, and the cover and the tank body are locked by a locking fastener.

[0011] Furthermore, a drainage hole and a heater with temperature control are provided at the bottom of the tank.

[0012] A method for dipping a three-dimensional braided preform comprises the following steps: Cut the vacuum film and make the vacuum impregnation tube according to the shape of the three-dimensional woven preform and the position to be placed in the tank; Firstly, a vacuum impregnation tube with prefabricated impregnation holes is wound around the outside of the three-dimensional braided preform, and then the outside is airtightly covered with a vacuum film and a vacuum tape; Put the three-dimensional braided preform together with the core mold into the tank body, connect the dipping port and the air extraction port of the vacuum dipping tube to the dipping air extraction hole and the dipping hole on the inner side of the lid respectively, and combine the lid with the barrel body through the fasteners on the outer side thereof; Vacuum injection; Stop injecting glue after the glue liquid fills the entire three-dimensional woven preform. Stop heating the heater after 3 minutes. Spray cold water outside the tank to cool it down. Observe the changes in the water pressure gauge and open the exhaust valve to reduce the water pressure in the tank to atmospheric pressure. After the water temperature in the tank drops below 35°C, open the cover and take out the workpiece. Peel off the vacuum film, tape and vacuum dipping hose and proceed to the subsequent process.

[0013] Furthermore, the vacuum injection includes three modes: Mode 1: Water pressure mode Close the drain hole at the bottom of the tank, open the exhaust hole on the outside of the lid, close the dipping valve, open the injection hole, start injecting high-pressure water, close the exhaust hole on the lid after it is basically filled, and after the water pressure is maintained at 1MPa, open the exhaust hole and the vacuum pump to continuously exhaust the three-dimensional woven preform in the vacuum membrane, turn on the heater and keep the bottom of the barrel at a constant temperature of 70°C; When the water temperature reaches above 60℃ and the pressure of the vacuum gauge is lower than 0.01MPa for 15min, open the glue dipping hole and the external glue injection pump to inject glue at 0.5MPa; Mode 2: Air pressure mode Turn on the heater power supply to keep the temperature at 70℃; open the air injection valve outside the air injection hole, start the air compressor to pressurize the tank to 2MPa and maintain it; The glue dipping valve outside the glue dipping hole is closed, the outer valve of the air extraction hole is opened, and the vacuum pump is started to continuously extract air from the three-dimensional braided preform in the vacuum film through the air extraction port, so that the water in the three-dimensional braided preform is quickly evaporated and extracted; After the pressure inside the vacuum membrane of the tank body is continuously lower than 0.01MPa for ten minutes, open the glue dipping hole and the external glue injection pump to inject glue at a pressure of 1.5MPa; Mode 3: Half water and half air pressure mode Fill the tank with water or heat transfer oil and make the liquid level exceed the top of the preform, then put the lid of the pressure tank on the barrel mouth and tightly combine it with the barrel body with the fasteners on the outside; Close the exhaust valve on the outside of the hydraulic tank cover, close the dipping hole valve, close the exhaust valve, open the air injection valve, start the air compressor to raise the air pressure above the liquid in the tank to 1MPa, open the air extraction hole valve, start the vacuum pump, make the heater work and keep the bottom of the barrel at a constant temperature of 70℃; After the liquid temperature in the tank reaches above 60°C and the pressure on the vacuum gauge remains below 0.01MPa for ten minutes, open the injection hole valve and start the external injection pump to inject glue at a pressure of 0.5MPa.

[0014] Compared with the prior art, the present invention has the following technical effects: The present invention firstly wraps a semi-rigid vacuum impregnation tube with side wall through holes around the outside of the preform, and then air-tightly covers the outside with a vacuum film and vacuum tape, puts it into a special pressure tank for heating, and vacuum-dries the preform through the vacuum holes, then increases the pressure in the pressure tank to compact the preform, and then high-pressure vacuum impregnates the preform with resin through the impregnation tube mouth. The glue always infiltrates from the bottom to the top first, and the impregnation holes that the glue has not yet reached serve as the exhaust channel. After the preform is completely impregnated, the pressure tank is depressurized to atmospheric pressure, the tank is opened to take out the impregnated preform, and the vacuum film, semi-rigid vacuum pipe, and impregnation tube are removed. According to the characteristic that the boiling point of water decreases with pressure, the present invention adopts heating vacuum drying to quickly and thoroughly remove moisture from the preform. By pressurizing the outside of the preform, it is appropriately compressed in advance during the impregnation to reduce its fluffiness, thereby avoiding excessive glue content and significantly reducing wrinkles after curing. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of a tank body of a preform dipping method of the present invention; Figure 2 A schematic diagram of a pressure tank for a preform dipping method according to the present invention; Figure 3 A schematic diagram of a semi-gas and semi-liquid pressure tank for a preform dipping method of the present invention; Among them: 1 - tank body, 2 - lid, 3 - locking fastener, 4 - sealing ring, 5 - glue dipping hole, 6 - exhaust hole, 7 - pressure gauge detection hole, 8 - exhaust hole, 9 - liquid injection hole, 10 - core mold, 11 - preform, 12 - vacuum film, 13 - vacuum tape, 14 - glue dipping port section, 15 - exhaust port section, 16 - bottom support, 17 - heater, 18 - drainage hole, 19 - air injection hole. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings: Example 1, please refer to Figure 1 A method for dipping a three-dimensional woven preform using a tank body for dipping glue, wherein the tank body is a tank body 1 with a lid 2, and the lid 2 is provided with: a liquid injection hole 9, a pipeline, a liquid injection hole 9, a water pressure gauge and a temperature gauge and connected to a high-pressure water pump, a dipping hole 5, a pipeline and a dipping valve, an exhaust hole 8 is connected to the atmosphere through a pipeline and a valve, the dipping hole 5 is connected to the injection pump through a joint, and the exhaust hole 6 is connected to a vacuum pump through a pipeline and an exhaust valve, the outer edge of the lid 2 is provided with a locking fastener 3 with the top of the barrel, the exhaust port is connected to the atmosphere through the exhaust hole 8, a sealing ring 4 is provided on the inner side of the outer edge of the lid, a drainage hole 18 is provided at the bottom of the barrel and enters a sewer pipe through the pipeline and the drainage hole, and a heater 17 with temperature control is provided on the outside of the bottom of the barrel.

[0017] The operation process is: 1. Prepare first. Cut the vacuum film 12 and make the vacuum dipping hose according to the shape of the preform 11 and the placement position in the tank. The vacuum dipping hose is made on site with a semi-hard transparent hose with an outer diameter of 8mm and a wall thickness of 1.5mm. The hose with a length of one end greater than the depth of the pressure tank without a side hole is the dipping port 14, and the hose with a length of the other end greater than the length of the hose with a length of the side hole from the top of the preform to the pressure tank cover is the vacuum port 15. In the middle section, a 2mm diameter dipping hole is punched on the side of the pipe at a spacing of 50mm.

[0018] 2. First, a semi-rigid vacuum impregnated hose with side wall through holes is wrapped around the outside of the preform 11, and then the outside is airtightly covered with a vacuum film 12 and a vacuum tape 13.

[0019] 3. Place the preform 11 together with the core mold 10 into the tank body 1, connect the glue dipping port 14 and the vacuum port 15 of the vacuum dipping tube to the glue dipping vacuum hole 6 and the glue dipping hole 5 on the inner side of the cover respectively, and tightly combine the cover 2 of the tank body with the fastener 3 on its outer side.

[0020] 4. Close the drain hole at the bottom of the tank, close the dipping valve, and open the exhaust hole 8.

[0021] 5. Open the liquid injection hole 9 and inject water into the tank. After filling, close the exhaust hole 8 on the lid, open the exhaust valve and the vacuum pump, operate the heater 17 at the bottom of the barrel and keep the bottom of the barrel at a constant temperature of 70°C.

[0022] 6. After the water temperature in the tank reaches above 60℃ and the pressure of the vacuum gauge is lower than 0.01MPa for 15 minutes, open the glue dipping hole 5 and the external glue injection pump to inject glue at a low pressure of 0.1MPa. (The boiling point of water at a pressure of 0.01MPa is only 45.8℃) 7. When the injection volume reaches 70% of the planned volume, adjust the water injection pressure to 1MPa and increase the injection pump pressure to 0.5MPa to continue injecting glue.

[0023] 8. After the glue liquid fills the entire preform, close the glue inlet valve and the water injection valve. After 3 minutes, the heater at the bottom of the barrel stops heating, spray cold water outside the tank to cool it down, observe the changes in the water pressure gauge and slowly open the exhaust hole 8 to reduce the water pressure in the tank to atmospheric pressure.

[0024] 9. After the water temperature in the tank drops below 35°C, open the lid and take out the workpiece.

[0025] 10. Peel off the vacuum film, tape and vacuum soaked hose and transfer to the subsequent cloth tape winding process.

[0026] The pressure tank is heated and vacuum dried through the exhaust hole, and then the pressure in the pressure tank is increased to compress the preform, and the preform is impregnated with resin under high pressure through the impregnation pipe. After the preform is completely impregnated and maintained for a period of time, it is cooled first, and then the exhaust hole 8 is opened to release the pressure of the pressure tank to atmospheric pressure. The impregnated preform is taken out of the tank, and the vacuum film and the semi-rigid exhaust pipe and the impregnation pipe are removed. Compared with the prior art, the heating vacuum drying adopted in the present invention can quickly and thoroughly remove the moisture in the preform, and the external pressurized vacuum impregnation can control the amount of impregnation, which can significantly reduce the wrinkles after curing. Since the process of accelerating the evaporation of water by exhausting air, the evaporated water will take away a large amount of heat, which will cause the temperature of the preform to be too low or even freeze, thereby reducing the drying efficiency. Therefore, heat is added to the preform in time, and it is best to make the moisture in the preform in a vaporized state, so that the extraction can be very fast and thorough.

[0027] Example 2, please refer to Figure 2A method for vacuum dipping of a three-dimensional woven preform using a pressure tank for pressurized dipping, wherein the pressure tank is a tank body 1 with a lid 2, and the lid 2 is provided with: a pipe joint of an air injection hole 19 is provided with a pressure gauge and is fixedly connected to an air compressor, a dipping hole 5, a pipeline and a dipping valve are connected to a glue injection pump, an exhaust hole 8 is connected to the atmosphere through a pipeline and a valve, an exhaust hole 6 is connected to a vacuum pump through a pipeline and an exhaust valve, and an exhaust port 8 is connected to the atmosphere through the exhaust hole 8, an outer edge of the lid 2 is provided with a locking fastener 3 with the top of the barrel, a sealing ring 4 is provided on the inner side of the outer edge of the lid, a drainage hole 18 is provided at the bottom of the barrel, and enters a sewer pipe through the pipeline and the drainage hole, and a heater 17 with temperature control is provided on the outside of the bottom of the barrel.

[0028] The operation process is: 1. Prepare first. Cut the vacuum film and make the vacuum dipping tube according to the shape of the preform and the placement in the pressure tank. The vacuum dipping tube is made on site with a semi-rigid tube with an outer diameter of 8mm and a wall thickness of 1.5mm. The tube mouth of the section without side holes at one end whose length is greater than the depth of the pressure tank is the dipping port, and the tube mouth of the section without side holes at the other end whose length is greater than the section from the top of the preform to the cover of the pressure tank is the vacuum hole. A 2mm diameter dipping hole is punched on the side of the tube at a distance of 30mm in the middle section.

[0029] 2. First, wrap the semi-rigid vacuum impregnated hose with side wall through holes around the outside of the preform, and then use vacuum film and vacuum tape to airtightly cover the outside.

[0030] 3. Place the preform together with the core mold into the tank body, connect the dipping port 14 and the air extraction port 15 of the vacuum dipping tube to the dipping and air extraction hole 6 joint and the dipping hole 5 joint on the inner side of the cover respectively, and then tightly combine the cover 2 of the pressure tank with the tank body through the fastener 3 on its outer side. 4. Turn on the power of the heater 17 to keep the temperature of the barrel bottom at 70°C; open the gas injection valve outside the gas injection hole 19, start the air compressor to pressurize the tank body 1 to 2MPa and maintain it.

[0031] 6. Close the dipping valve outside the dipping hole 5, open the outer valve of the exhaust hole 6 and start the vacuum pump to exhaust the preform 11 in the vacuum film 12 through the exhaust pipe 15, so that the moisture in the preform evaporates quickly and is extracted.

[0032] 7. After the pressure inside the vacuum membrane 12 in the tank body is continuously lower than 0.01 MPa for ten minutes, open the glue dipping hole 5 and the external glue injection pump to inject glue at a pressure of 1.5 MPa.

[0033] 8. When the glue liquid fills the entire preform, close the dipping valve, turn off the power of the heater 17 after 3 minutes to stop heating, and start spraying cold water outside the tank to cool it down.

[0034] 9. After the temperature inside the tank drops below 35°C, turn off the vacuum pump and the air extraction valve, and slowly open the exhaust hole 8 on the outer pipeline of the air injection hole to reduce the air pressure inside the tank to atmospheric pressure.

[0035] 10. Open the cover and take out the workpiece, peel off the vacuum film, tape and vacuum dipped hose and transfer to the subsequent tape winding process.

[0036] Using a pressure tank and vacuum drying the preform by heating and exhausting can significantly improve the drying speed and drying quality. Then, increasing the pressure in the pressure tank to compress the preform, and then high-pressure vacuum impregnating the preform with resin through the impregnation nozzle can accurately control the amount of impregnation and significantly reduce wrinkles after curing. Using a pressure tank is cleaner and more convenient to operate, but the heat transfer and temperature control are not as fast and uniform as using water.

[0037] Example 3: Please refer to Figure 1 , Figure 3 A vacuum dipping method for a three-dimensional woven preform using a pressure tank for half-air and half-water pressurized dipping, wherein the tank body is a tank body 1 with a lid, and the lid 2 is provided with: an air injection hole 19 and its pipeline and air injection valve, a pressure gauge and a temperature gauge connected to an air compressor through a pipeline, an air extraction hole 6 and its external pipeline, an air extraction valve and a vacuum gauge and connected to a vacuum pump, a dipping hole 5 and its external pipeline and a dipping valve, an exhaust hole 8 and connected to a dipping pump, an outer edge of the lid 2 is provided with a locking fastener 3 with the top of the barrel, a sealing ring 4 is provided on the inner side of the outer edge of the lid, a heater 17 with temperature control is provided on the outside of the barrel bottom, a drainage hole 18 and a drainage valve are provided at the barrel bottom and connected to a sewer pipe through a pipeline.

[0038] The operation process is: 1. Prepare first. Cut the vacuum film and make the vacuum dipping hose according to the shape of the preform and the placement in the tank. The vacuum dipping hose is made on-site with a semi-hard transparent hose with an outer diameter of 8mm and a wall thickness of 1.5mm. The nozzle of the section without side holes at one end that is longer than the depth of the pressure tank is the dipping port, and the nozzle of the section without side holes at the other end that is longer than the section from the top of the preform to the lid of the pressure tank is the vacuum hole. A row of 2.5mm diameter dipping holes is punched on the side of the pipe at a spacing of 30mm in the middle section.

[0039] 2. First, wrap the semi-rigid vacuum impregnated hose with side wall through holes around the outside of the preform, and then use vacuum film and vacuum tape to airtightly cover the outside.

[0040] 3. Place the preform together with the core mold into the tank, connect the dipping port and the air extraction port of the vacuum dipping tube to the dipping air extraction hole and the dipping hole on the inside of the lid respectively, and close the drain valve at the bottom of the barrel.

[0041] 4. Fill the tank with water or heat transfer oil and make the liquid level exceed the top of the prefabricated body. Then put the lid of the pressure tank on the barrel mouth and tightly combine it with the tank body with the fasteners on the outside.

[0042] 5. Close the exhaust hole 8 on the outside of the tank cover, close the dipping valve, close the exhaust hole 8, open the exhaust valve and the vacuum pump, make the heater at the bottom of the barrel work and keep the bottom of the barrel at a constant temperature of 70℃.

[0043] 6. After the liquid temperature in the tank reaches above 60°C and the pressure on the vacuum gauge remains below 0.01MPa for ten minutes, open the glue immersion hole 5 and the external glue injection pump to inject glue at a low pressure of 0.2MPa.

[0044] 7. When the injection volume reaches 60% of the planned volume, adjust the gas injection pressure to 1MPa and the injection pump pressure to 0.5MPa to continue injecting glue.

[0045] 8. After the glue liquid fills the entire preform, close the glue inlet valve and the air injection valve. After 10 minutes, turn off the power of the heater at the bottom of the barrel to stop heating and spray cold water outside the tank to cool it down. After the water temperature in the tank drops below 35°C, observe the changes in the barometer and slowly open the exhaust hole 8 to reduce the air pressure in the tank to atmospheric pressure.

[0046] 9. Open the cover and take out the workpiece.

[0047] 10. Peel off the vacuum film, tape and vacuum soaked hose and transfer to the subsequent cloth tape winding process.

[0048] This embodiment uses a pressure tank and only immerses the preform in liquid, and vacuum-dries the preform by heating and exhausting. Since the heat transfer capacity of liquid in convection state is much higher than that of air, the drying speed and drying quality can be significantly improved. Then, the pressure in the pressure tank is increased to compress the preform, and then the preform is vacuum-impregnated with resin through the impregnation nozzle. The amount of impregnation can be accurately controlled and wrinkles after curing can be significantly reduced. The use of a pressure tank is relatively cheap and convenient to operate. Half air and half water is a good operation that takes into account the contradiction between quality and equipment cost.

[0049] Example 4: Please refer to Figure 3 , semi-air and semi-water dipping of the winding and stitching preform.

[0050] The traditional pre-impregnated carbon fiber tape wrapped with ablation-resistant lining lacks Z-direction fibers, which will cause delamination during use, and even large pieces will fall off and block the throat lining. The dry tape wrapping and sewing technology can effectively solve the delamination risk of bag wrapping, but the preform wrapped and sewn with dry tape is relatively fluffy, and the glue content after dipping is relatively high, especially the preform wrapped with multi-layer composite tape with felt sandwiched. The glue content is higher, and the wrinkles are very serious after curing! The method described in this embodiment can solve this problem well.

[0051] A vacuum dipping method for a carbon fiber dry cloth tape wrapped seam preform using a pressure tank for half-air and half-water pressure dipping, wherein the water pressure dipping tank is a barrel with a lid, and the lid is provided with an air injection pipe and an air injection valve, a barometer and a thermometer, an air extraction hole and an air extraction valve and a vacuum gauge, a dipping hole and a dipping valve, an exhaust port and a valve, a locking fastener with the top of the barrel is provided on the outer edge of the lid, a sealing ring is provided on the inner side of the outer edge of the lid, a heater with temperature control is provided on the outside of the barrel bottom, an air injection pipe on the outside of the lid is connected to an air compressor, an air extraction hole is connected to a vacuum pump, a dipping hole is connected to a vacuum degassing glue tank, and an exhaust port is connected to the atmosphere through an exhaust port 8. A drain pipe and a valve are provided at the bottom of the barrel and connected to a sewer pipe through a pipeline.

[0052] The operation process is: 1. Prepare first. Cut the vacuum film and make the vacuum dipping hose according to the shape of the wrapped seam preform and the placement in the tank. The vacuum dipping hose is made on-site with a semi-hard transparent hose with an outer diameter of 8mm and a wall thickness of 1.5mm. The nozzle of the section without side holes at one end that is longer than the depth of the pressure tank is the dipping port, and the nozzle of the section without side holes at the other end that is longer than the section from the top of the preform to the lid of the pressure tank is the vacuum hole. In the middle section, a row of 2.5mm diameter dipping holes is punched on the side of the pipe at a spacing of 30mm.

[0053] 2. First, wrap the semi-rigid vacuum impregnated hose with side wall through holes around the outside of the preform, and then use vacuum film and vacuum tape to airtightly cover the outside.

[0054] 3. Place the preform together with the core mold into the tank, connect the dipping port and the air extraction port of the vacuum dipping tube to the dipping air extraction hole and the dipping hole on the inside of the lid respectively, and close the drain valve at the bottom of the barrel.

[0055] 4. Fill the tank with water or heat transfer oil and make the liquid level exceed the top of the prefabricated body. Then put the lid of the pressure tank on the barrel mouth and tightly combine it with the tank body with the fasteners on the outside.

[0056] 5. Close the exhaust hole 8 on the outside of the tank cover, close the dipping valve, close the exhaust hole 8, open the exhaust valve and the vacuum pump, make the heater at the bottom of the barrel work and keep the bottom of the barrel at a constant temperature of 70℃.

[0057] 6. After the liquid temperature in the tank reaches above 60°C and the pressure on the vacuum gauge remains below 0.01MPa for ten minutes, adjust the gas injection pressure to 1.5MPa, then open the glue immersion hole 5 and the external glue injection pump to inject glue at a pressure of 2MPa.

[0058] 7. When the glue liquid fills the entire preform, close the glue inlet valve and the air injection valve. After 10 minutes, turn off the power of the heater at the bottom of the barrel to stop heating and spray cold water outside the tank to cool it down.

[0059] 8. After the water temperature in the tank drops below 35°C, observe the changes in the barometer and slowly open the exhaust hole 8 to reduce the pressure in the tank to atmospheric pressure. When the injection volume reaches 60% of the planned volume, open the cover and take out the workpiece.

[0060] 9. Peel off the vacuum film, tape and vacuum soaked hose and transfer to the subsequent cloth tape winding process.

[0061] This embodiment uses a pressure tank and only immerses the preform in liquid, and vacuum-dries the preform by heating and exhausting air. Since the heat transfer capacity of liquid in convection state is much higher than that of air, the glue liquid can be well heated and insulated. High pressure is pre-applied in the tank and the fluffy entangled preform in the vacuum bag is compacted by liquid, and then high-pressure glue is dipped; after dipping, the fibers of the preform are bonded by the glue and can no longer bounce open at will. In this way, the amount of glue dipped preforms produced will not be too much, and no excess glue will be discharged during curing. The volume of the preform will not be significantly reduced, which can significantly reduce the wrinkles of the entangled preform and the wrinkles of the insulation layer cloth tape.

[0062] The above is only the most typical specific implementation of the present invention, but the protection scope of the present invention is not limited to this. Due to space limitations, the production steps of the traditional process used are not described in detail, but it does not mean that the omitted process steps do not exist. The listed data are only for describing the working principle of the present invention and do not represent necessary values. Any technicians familiar with rocket manufacturing and related fields can easily think of equivalent changes within the technical scope disclosed by the present invention, which should be covered within the scope of the claims of the present invention.

Claims

1. A pressure tank, characterized in that: The invention comprises a cover (2), a tank body (1), a glue dipping hole (5), an air extraction hole (6), a glue dipping tube, an exhaust hole (8), a liquid injection hole (9), a sealing layer and a gas injection hole (19); the cover (2) is sealingly arranged on the tank body (1); the glue dipping hole (5), the air extraction hole (6), the exhaust hole (8), the liquid injection hole (9) and the gas injection hole (19) are all arranged on the cover (2); the glue dipping tube is arranged inside the tank body (1) and is used for winding around a three-dimensional braided preform; the sealing layer is coated on the glue dipping tube and the outside of the three-dimensional braided preform; one end of the glue dipping tube is connected to the glue dipping hole (5), and the other end is connected to the air extraction hole (6).

2. A pressure tank according to claim 1, characterized in that: The vacuum impregnation tube comprises a glue impregnation port section (14), a side hole section and a vacuum port section (15), wherein the glue impregnation port section (14), the side hole section and the vacuum port section (15) are connected in sequence, the side hole section is used for winding a three-dimensional braided preform, and a glue impregnation hole is provided on the side hole section; the glue impregnation port section (14) is connected to the glue impregnation hole (5), and the vacuum port section (15) is connected to the vacuum hole (6).

3. A pressure tank according to claim 1, characterized in that: The sealing layer comprises a vacuum film (12) and a vacuum tape (13), and the vacuum film (12) is sealed and adhered to the core mold of the three-dimensional braided preform via the vacuum tape (13).

4. A pressure tank according to claim 1, characterized in that: The liquid injection hole (9) is connected to a high-pressure water pump via a pipeline, and a water injection valve, a water pressure gauge and a temperature gauge are arranged on the pipeline.

5. A pressure tank according to claim 1, characterized in that: The air injection hole (19) is connected to an air compressor via a pipeline, and a pressure gauge and an air injection valve are provided on the pipeline.

6. A pressure tank according to claim 1, characterized in that: The glue dipping hole (5) is connected to a glue injection pump, and the air extraction hole (6) is connected to a vacuum pump via a pipeline and an air extraction valve.

7. A pressure tank according to claim 1, characterized in that: A sealing ring (4) is provided between the cover (2) and the tank body (1), and the cover (2) and the tank body (1) are locked by means of a locking fastener (3).

8. A pressure tank according to claim 1, characterized in that: The bottom of the tank body (1) is provided with a drainage hole (18) and a heater (17) with temperature control.

9. A method for dipping a three-dimensional braided preform, characterized in that: The pressure tank according to any one of claims 1 to 8 comprises the following steps: Cut the vacuum film and make the vacuum impregnation tube according to the shape of the three-dimensional woven preform and the position to be placed in the tank; Firstly, a vacuum impregnation tube with prefabricated impregnation holes is wound around the outside of the three-dimensional braided preform, and then the outside is airtightly covered with a vacuum film and a vacuum tape; Put the three-dimensional braided preform together with the core mold into the tank body, connect the dipping port and the air extraction port of the vacuum dipping tube to the dipping air extraction hole and the dipping hole on the inner side of the lid respectively, and combine the lid with the barrel body through the fasteners on the outer side thereof; Vacuum injection; After the glue liquid fills the entire three-dimensional woven preform, stop injecting glue and water. After 3 minutes, stop heating the heater, spray cold water outside the tank to cool it down, observe the changes in the water pressure gauge and open the exhaust valve to reduce the water pressure in the tank to atmospheric pressure. After the water temperature in the tank drops below 35°C, open the cover and take out the workpiece, peel off the vacuum film, tape and vacuum dipping hose and proceed to the subsequent process.

10. The method for impregnating a three-dimensional braided preform according to claim 9, characterized in that: The vacuum injection includes three modes: Mode 1: Water pressure mode Close the drain hole at the bottom of the tank, open the exhaust hole on the outside of the lid, close the dipping valve, open the injection hole, start injecting high-pressure water, close the exhaust hole on the lid after it is basically filled, and after the water pressure is maintained at 1MPa, open the exhaust hole and the vacuum pump to continuously exhaust the three-dimensional woven preform in the vacuum membrane, turn on the heater and keep the bottom of the barrel at a constant temperature of 70°C; When the water temperature reaches above 60℃ and the pressure of the vacuum gauge is lower than 0.01MPa for 15min, open the glue dipping hole and the external glue injection pump to inject glue at 0.5MPa; Mode 2: Air pressure mode Turn on the heater power supply to keep the temperature at 70℃; open the air injection valve outside the air injection hole, start the air compressor to pressurize the tank to 2MPa and maintain it; The glue dipping valve outside the glue dipping hole is closed, the outer valve of the air extraction hole is opened, and the vacuum pump is started to continuously extract air from the three-dimensional braided preform in the vacuum film through the air extraction port, so that the water in the three-dimensional braided preform is quickly evaporated and extracted; After the pressure inside the vacuum membrane of the tank body is continuously lower than 0.01MPa for ten minutes, open the glue dipping hole and the external glue injection pump to inject glue at a pressure of 1.5MPa; Mode 3: Half water and half air pressure mode Fill the tank with water or heat transfer oil and make the liquid level exceed the top of the preform, then put the lid of the pressure tank on the barrel mouth and tightly combine it with the barrel body with the fasteners on the outside; Close the exhaust valve on the outside of the hydraulic tank cover, close the dipping hole valve, close the exhaust valve, open the air injection valve, start the air compressor to raise the air pressure above the liquid in the tank to 1MPa, open the air extraction hole valve, start the vacuum pump, make the heater work and keep the bottom of the barrel at a constant temperature of 70℃; After the liquid temperature in the tank reaches above 60°C and the pressure on the vacuum gauge remains below 0.01MPa for ten minutes, open the injection hole valve and start the external injection pump to inject glue at a pressure of 0.5MPa.

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