Forming method of high-strength composite material spacer sleeve

Abstract

The invention belongs to the technical field of composite material isolation sleeves, and discloses a forming method of a high-strength composite material isolation sleeve, before resin is cured, a 0.8-1.2 MPa pressure carrier is injected into a bag type male mold cavity, uniform tension in all directions is applied to a continuous fiber prefabricated body through bag body expansion, and a reserved gap between the prefabricated body and a female mold is matched with the tension expansion size. According to the design, the fibers are regularly arranged in the whole curing process, local curling and stacking are avoided, finally, the tensile property of the formed composite material isolation sleeve is greatly improved, the compression strength meets the strict requirement of a magnetic drive pump serving as a pressure-bearing component, and the failure risk caused by disordered fiber stress of a traditional product is fundamentally solved; the method comprises the following steps: firstly, sucking a module cavity for 15-20 minutes under the negative pressure of-0.095 to-0.098 MPa, and thoroughly exhausting air in the cavity; and the defoamed resin is sucked into the cavity by means of negative pressure, and meanwhile, the flow velocity is controlled to prevent fiber displacement, so that the resin is ensured to fully and uniformly infiltrate the preform.

Description

Technical Field

[0001] This invention belongs to the field of composite material isolation sleeve technology, specifically a molding method for a high-strength composite material isolation sleeve. Background Technology

[0002] As a leak-free conveying device, the core pressure-bearing component of a magnetic pump is a composite material isolation sleeve. This component directly bears the pressure of the conveyed medium and has stringent performance requirements for the tensile strength of the material. If the tensile strength is insufficient, it can easily lead to the rupture of the isolation sleeve and leakage of the medium, directly affecting the operational safety and stability of the magnetic pump. The following technical problems still exist in the traditional molding process of composite material isolation sleeves: Traditional processes often use fixed male molds, which can only limit the shape of the preform by the cavity size and cannot dynamically adjust the support force according to the stress state of the fiber during the molding process. When the fiber undergoes slight deformation after being impregnated by resin, the fixed male mold cannot adapt to the deformation, which can easily lead to local pressure curling or loosening of the fiber, creating a hidden danger for uneven tension in the future. Traditional processes often employ atmospheric pressure injection or simple vacuum injection. The former, because air cannot be expelled from the cavity, easily forms bubbles at the fiber-resin interface, disrupting the continuity of fiber stress. The latter, although it can improve wetting, is not combined with fiber tension control. During injection, the impact force of resin flow can easily cause fiber displacement, further aggravating tension disorder. Traditional processes often involve curing at atmospheric pressure or without active pressure holding. During the cross-linking process, the resin undergoes volume shrinkage, which directly loosens the fibers. This results in the fibers failing to maintain their initial regular shape after curing, ultimately causing localized pressure-weak areas in the isolation sleeve, making it difficult to meet the stringent long-term pressure requirements of magnetic pumps.

[0003] The defects of the aforementioned traditional processes do not exist in isolation, but rather form a vicious cycle of "insufficient mold adaptation → fiber displacement during impregnation → tension loss during curing," which cannot be fundamentally solved by conventional local optimizations (such as only improving the injection method or only adjusting the curing temperature). Summary of the Invention

[0004] The purpose of this invention is to provide a molding method for a high-strength composite material isolation sleeve to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for molding a high-strength composite material isolation sleeve, the specific steps of which are as follows: S1. Mold assembly and sealing: Place the cut continuous fiber preform into the female mold cavity, leaving a gap that matches the tension expansion size of the preform; then place the expandable bladder-type male mold, cover with a blind flange and embed a sealing ring, and tighten the bolts to seal, so as to avoid air leakage and glue leakage in the future. S2. Module vacuum pretreatment: After completing the module sealing, first close the glue injection valve at the glue injection port, connect the vacuum pump to the vacuum tube port and check the sealing performance; open the vacuum valve and vacuum pump, and evacuate at a negative pressure of -0.095~-0.098MPa for 15~20 minutes. After the vacuum degree stabilizes, close the vacuum valve and vacuum pump to maintain the negative pressure inside the cavity. S3. Resin injection operation: Relying on the negative pressure in the module cavity, inject a certain amount of degassing resin into the injection box, let it stand for 10-15 minutes or vacuum degas; slowly open the injection valve, use the negative pressure to draw the resin into the cavity, control the flow rate to prevent fiber displacement, observe the liquid level and wetting situation, and close the injection valve after the resin has fully covered the preform to prevent backflow. S4. Pressurizing the bladder-type male mold: After resin impregnation, connect the pressurizing port to the injection equipment (the pipeline pressure resistance is ≥ 1.5 times the set pressure), set the pressure to 0.8~1.2MPa (carrier can be gas or liquid); open the pressurizing valve and slowly inject the carrier, maintain the pressure for 5~8 minutes and then close the valve, remove the injection box and each pipeline, so that the bladder-type male mold expands and applies uniform tension; S5. Pressurized heating and curing: Maintain the pressurized state, horizontally send the module into the heating and insulation box, heat up to 80℃ at 2~3℃ / min and keep for 1.5 hours, then heat up to 120℃ and keep for 2.5 hours. Measure and replenish the pressure every 30 minutes (when the pressure drop exceeds 0.1MPa) to ensure that the resin is completely cured and the fiber maintains uniform tension. After curing, it is necessary to cool down to prevent internal stress. S6. Module cooling treatment: After curing, first turn off the power of the insulation box and let the module cool down naturally to 60℃; then take it out and place it in a ventilated place for air cooling, control the cooling rate at 5~8℃ / min, avoid strong winds, and keep the module sealed to prevent deformation throughout the process; measure the temperature in real time, and wait until it drops to room temperature (25±5℃). S7. Demolding and Part Removal: After the module cools down to room temperature, follow the principle of "removing auxiliary parts first, then removing the product". Use a wrench to symmetrically remove the blind flange bolts and remove the blind plate and sealing ring. Connect the bladder-type male mold to the negative pressure equipment to evacuate and shrink it, and slowly remove it. If the female mold and the isolation sleeve are stuck together, use a soft cloth to tap the female mold or inject a release agent, and finally remove the complete finished product.

[0006] Preferably, the specific steps of mold assembly and sealing in step S1 are as follows: S11. Core component assembly: The neatly cut continuous fiber preform is precisely placed into the female mold cavity, with a specific gap reserved. This gap is determined through preliminary testing and must be completely matched with the radial expansion dimension of the preform under subsequent tension. This avoids the preform being deformed under pressure due to an insufficient gap, or the tension not being transmitted properly due to an excessive gap. Then, the resin-compatible expandable bladder-type male mold is slowly placed into the preform, ensuring that the bladder is centered and wrinkle-free. S12. Module sealing and fixing: After assembly, cover the blind flange and align it with the female mold port. Insert the sealing ring to fill the contact gap, and then tighten the blind flange evenly with bolts. This step is necessary to ensure that the module is properly sealed to prevent air or glue leakage during subsequent vacuum suction, glue injection and pressurization.

[0007] Unlike traditional fixed male molds, expandable bladder male molds require materials that are completely compatible with the resin (to prevent adhesion after curing) and must have a specific expansion rate (to ensure that tension is evenly transmitted during pressurization, rather than localized bulging). The selection of this material needs to be determined by combining the resin curing temperature and the fiber elastic modulus, and must be verified through multiple compatibility tests (such as excluding rubber materials that easily react with epoxy resin and selecting silicone materials that are resistant to high temperatures and expand evenly). The reserved gap is not arbitrarily set, but must perfectly match the radial expansion dimension of the preform under subsequent pressure (0.8~1.2MPa). If the gap is too small, the preform will be squeezed during pressure application of the bladder-type male mold, causing deformation of the fiber structure; if the gap is too large, the expansion force of the bladder cannot be effectively transmitted to the fibers, resulting in a loss of tension control. This gap dimension needs to be determined through preliminary mechanical tests (such as testing the radial expansion of the preform under different pressures and deriving the reserved gap value in reverse), reflecting a deep understanding of the relationship between the mold, preform, and pressure, which cannot be conventionally derived by those skilled in the art. This design shifts from "passive adaptation" to "active tension control," solving the core defect of traditional fixed male molds that cannot dynamically adjust fiber tension, and forming a collaborative innovation of "mold structure - tension control."

[0008] Preferably, the specific steps of the module vacuum pretreatment in step S2 are as follows: S21. Pre-treatment preparation and connection: First, close the injection valve corresponding to the injection port at the top of the female mold to cut off the injection channel and ensure the vacuum level; then connect the vacuum port at the bottom of the side of the female mold to the vacuum pump through a special pipeline. When connecting, check the sealing of the pipeline interface. You can wrap sealant tape to prevent air leakage and ensure that there is no leakage in the vacuum suction channel. S22. Vacuum suction and pressure holding: Open the vacuum valve and vacuum pump, set the negative pressure value to -0.095~-0.098MPa, and continuously suction the module cavity for 15~20 minutes. During this period, observe whether the vacuum degree is stable through the vacuum gauge. If the vacuum degree drops, check and repair the seal. After suction is completed, close the vacuum valve first and then turn off the vacuum pump to maintain the negative pressure in the cavity.

[0009] Setting a negative pressure value of -0.095 to -0.098 MPa is to find a balance between "completely purging the air in the cavity" and "avoiding excessive suction that damages the fiber structure." When the negative pressure is below -0.095 MPa, residual air in the cavity is prone to forming bubbles; when it is above -0.098 MPa, it will cause the fibers at the edge of the preform to shift due to the negative pressure difference. The suction time of 15 to 20 minutes is determined based on immersion tests with different fiber areal densities (to ensure that the air inside the thick fiber preform can also be completely purged), rather than a conventional "empirical value."

[0010] Preferably, the specific steps of the resin injection operation in step S3 are as follows: S31. Resin pretreatment and injection preparation: Pour a measured amount of liquid resin into the injection box. The resin needs to be mixed evenly according to the formula in advance and degassed. You can let it stand for 10 to 15 minutes to allow the air bubbles to rise naturally, or use vacuum degassed treatment to avoid the resin containing air bubbles affecting the wetting effect. At this time, the module is still under negative pressure to prepare for the resin to be sucked into the cavity. S32. Negative pressure injection and process control: Slowly open the injection valve at the injection port and use the negative pressure inside the cavity to draw the resin into the module cavity. During injection, adjust the valve opening to control the flow rate and prevent the flow rate from being too fast and impacting the preform, causing fiber displacement. Once the resin fully covers the preform and the liquid level no longer drops, immediately close the valve to prevent backflow.

[0011] The flow rate is controlled by adjusting the valve opening during resin injection, which is not simply "slow injection," but rather to coordinate with the initial vacuum state. If the flow rate is too fast, the resin impact can cause fiber displacement; if the flow rate is too slow, the wetting effect can be affected by the decrease in negative pressure within the cavity. This flow rate control needs to be linked with the vacuum level (e.g., when the vacuum level is stable at -0.095MPa, the flow rate is controlled at 50~80mL / min), reflecting the synergy of the "pretreatment-injection" process and solving the shortcomings of traditional vacuum resin injection that "only emphasizes wetting and neglects tension."

[0012] Preferably, the specific steps for pressurizing the bladder-type male mold in step S4 are as follows: S41. Connection and parameter setting of pressurization equipment: Connect the pressurization port at the bottom of the blind flange to the injection equipment through a high-pressure pipeline. The pressure resistance of the pipeline must be no less than 1.5 times the set pressure to prevent rupture during pressurization. According to the design requirements of the isolation sleeve, set the pressure value of the injection equipment to 0.8~1.2MPa. The pressure carrier can be compressed air or hydraulic oil. The selected gas must be dry and free of impurities to prevent corrosion of the bladder. S42. Pressurization Operation and Pipeline Removal: Open the pressurization valve and slowly inject the pressure carrier into the cavity of the bladder-type male mold. Monitor the pressure in real time to prevent sudden pressure rise from causing the bladder to rupture or uneven stress on the preform. After the pressure reaches the set value and stabilizes for 5-8 minutes, close the pressurization valve and gently remove the glue injection box, vacuum pipeline and pressurization pipeline to avoid module displacement affecting pressure stability. At this time, the bladder has applied uniform tension to the preform.

[0013] The holding pressure of 0.8~1.2MPa is not set arbitrarily, but is determined based on the resin shrinkage rate and fiber tension requirements. During the resin curing stage, volume shrinkage will occur, and this shrinkage force will weaken the initial tension of the fiber. The holding pressure needs to just offset the shrinkage force, while avoiding excessive pressure that would cause the preform to be over-compressed. During the curing process, slight leakage from the module seal and further resin shrinkage may cause a pressure drop. Pressure testing and replenishment every 30 minutes (replenishing pressure when the pressure drop exceeds 0.1 MPa) can correct tension deviations in real time, ensuring that the fibers maintain a regular stress state throughout the entire curing cycle. This design deeply integrates "pressure control" with the "dynamic process of composite material curing," rather than simply "pressurizing during curing," solving the core problem of "tension loss due to resin shrinkage" in traditional curing.

[0014] Preferably, the specific steps of pressurized heating and curing in step S5 are as follows: S51. Module placement and basic curing parameters: Smoothly place the pressure-holding module into the heating and insulation box. Keep it horizontal during placement to prevent uneven resin distribution in the cavity due to tilting. If epoxy resin is used, heat it from room temperature to 80°C at a rate of 2~3°C / min according to the process. Keep it at this temperature for 1.5 hours to allow the resin to initially crosslink, laying the foundation for subsequent complete curing. S52. Curing temperature and pressure monitoring: After initial cross-linking, continue to heat to 120℃ and hold for 2.5 hours to ensure complete resin curing; record module pressure every 30 minutes throughout the curing process. If the pressure drop exceeds 0.1MPa, pressurize to the set value through the pressurization pipeline to ensure that the fiber preform is always under uniform tension and to avoid resin shrinkage that causes fiber relaxation. After curing, the cooling process can begin.

[0015] Preferably, the specific steps of the module cooling process in step S6 are as follows: S61. Natural cooling inside the insulation box: After curing, turn off the power to the heating insulation box and let the module cool down naturally to 60℃. The cooling rate is slow at this stage, which can reduce the temperature difference between the inside and outside of the isolation sleeve and avoid internal stress caused by temperature difference. During the cooling period, the module must be kept sealed to prevent outside air from entering or the pressure inside the cavity from dropping suddenly, which could cause product deformation. S62. After removal, air cooling and temperature control: Remove the module from the insulation box and place it in a well-ventilated room temperature environment for air cooling. Avoid strong winds blowing directly on it. You can use a fan to blow air indirectly and control the cooling rate at 5~8℃ / min. Use a thermometer to measure the surface temperature of the module in real time. Once it drops to room temperature (25±5℃), the cooling process is completed, which prepares the module for subsequent demolding and part removal.

[0016] Preferably, the specific steps for demolding and removing the part in step S7 are as follows: S71. Auxiliary component removal: Following the principle of "removing auxiliary components first", use a wrench to symmetrically remove the connecting bolts between the blind flange and the female mold to prevent the blind flange from deforming due to uneven stress. After removing the bolts, gently remove the blind flange and the bottom sealing ring. Then connect the pressure port of the bladder-type male mold to the negative pressure equipment, draw a vacuum to shrink the bladder to its initial size, and slowly remove the bladder. S72. Product Separation and Removal: Check the fit between the female mold and the isolation sleeve. If there is local adhesion, you can use a soft cloth to tap the outer wall of the female mold, or inject a small amount of release agent into the gap to assist in separation. Once the female mold and the isolation sleeve are completely separated, the complete high-strength composite material isolation sleeve can be removed, completing the entire molding process.

[0017] Mold assembly stage (S1): Reserve a gap to match the tension expansion size of the preform, laying the structural foundation for the subsequent pressure transmission of tension by the bladder-type male mold - if the gap size is not appropriate, uniform tension control will not be achieved during subsequent pressure application; Vacuum pretreatment stage (S2): By precisely suctioning out the air in the cavity under negative pressure, on the one hand, a bubble-free environment is created for negative pressure glue injection (S3), avoiding bubbles from disrupting the continuity of fiber stress; on the other hand, it ensures that the preform is in a stable state before glue injection, reducing the risk of fiber displacement during glue injection. The pressure application stage of the bladder-type male mold (S4): After resin impregnation, a pressure of 0.8~1.2MPa is applied to provide initial uniform tension to the fiber, while making the fiber and resin tightly bonded, preparing for the tension maintenance in the subsequent curing stage; Pressure curing stage (S5): Maintain pressure throughout the process and apply pressure in real time to resist the weakening of fiber tension by resin shrinkage, ensure that the fiber is always in a regular stress state during the curing process, and avoid structural defects caused by tension loss. Cooling and demolding stages (S6, S7): Precise temperature control and symmetrical part removal avoid uneven cooling or tension release caused by demolding stress, ensuring the structural integrity of the molded product and ultimately achieving the goal of "regular fiber arrangement - tight interface bonding - stable pressure resistance".

[0018] The beneficial effects of this invention are as follows: 1. This invention achieves a key breakthrough through an expandable bladder-type male mold: Before resin curing, a pressure carrier (gas or liquid) of 0.8~1.2MPa is injected into the cavity of the bladder-type male mold. The expansion of the bladder applies uniform tension in all directions to the continuous fiber preform, and the pre-reserved gap between the preform and the female mold matches the tension expansion size, further ensuring precise tension transmission. This design ensures that the fibers maintain a regular arrangement throughout the curing process, avoiding localized curling and stacking. Ultimately, this significantly improves the tensile strength of the molded composite material isolation sleeve, and its compressive strength meets the stringent requirements of a magnetic pump as a pressure-bearing component, fundamentally solving the failure risk of traditional products caused by disordered fiber stress.

[0019] 2. This invention optimizes the impregnation effect through a combination of "module vacuum pretreatment + negative pressure injection": First, the module cavity is evacuated at a negative pressure of -0.095~-0.098MPa for 15~20 minutes to completely remove air from the cavity; then, the degassed resin (after static or vacuum degassed treatment) is drawn into the cavity using negative pressure, while controlling the flow rate to prevent fiber displacement, ensuring that the resin fully and uniformly impregnates the preform. This process reduces bubble defects at the resin-fiber interface, strengthens the interfacial bonding strength of the composite material, and avoids problems such as cracking and deformation of the isolation sleeve due to interfacial peeling during long-term pressure use, significantly improving the product's structural stability and service life, and reducing the maintenance cost of the magnetic pump. Attached Figure Description

[0020] Figure 1 This is a diagram illustrating the molding method of the high-strength composite material isolation sleeve of the present invention; Figure 2 This is a schematic diagram of the cross-sectional structure of the module of the present invention.

[0021] In the diagram: 1. Injection box; 2. Injection valve; 3. Injection port; 4. Female mold; 5. Continuous fiber preform; 6. Bladder-type male mold; 7. Blind flange; 8. Pressure port; 9. Pressure valve; 10. Sealing ring; 11. Vacuum suction port; 12. Vacuum valve. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] like Figures 1 to 2 As shown in the figure, this invention provides a method for molding a high-strength composite material isolation sleeve. The specific steps of this method are as follows: S1. Mold Assembly and Sealing: The cut continuous fiber preform (material is carbon fiber T700, using a unidirectional woven structure, surface density 200g / m²) is assembled and sealed. 2 Place the mold into the female mold cavity, leaving a gap to match the tension expansion dimension of the preform (determined to be 3±0.2mm based on preliminary tests); then place the expandable bladder-type male mold (made of high-temperature resistant silicone, model HT-8806, Shore hardness 55±5, expansion rate ≤15%), cover with a blind flange and embed a sealing ring (made of nitrile rubber, hardness 70±5ShoreA), and tighten the bolts to seal (tightening torque is 15±2N·m) to prevent air and glue leakage in the future; S2. Module Vacuum Pretreatment: After sealing the module, first close the glue injection valve (manual ball valve, DN15) at the glue injection port. Connect the vacuum pump (model 2XZ-2, ultimate vacuum ≤5Pa) through a special pipeline (PU tube, inner diameter 8mm, wall thickness 2mm) and check the seal (apply soapy water to the pipeline interface; if no bubbles are generated, the seal is qualified). Open the vacuum valve and vacuum pump, and evacuate at a negative pressure of -0.095~-0.098MPa and a vacuum rate of 5L / min for 15~20 minutes. After the vacuum degree is stable (vacuum degree fluctuation ≤0.002MPa / 5min), close the vacuum valve and vacuum pump to maintain the negative pressure inside the cavity. S3. Resin Injection Operation: Relying on the negative pressure inside the module cavity, inject a measured amount of degassed resin into the injection box (the resin formula is epoxy resin E-51 and polyamide 650 mixed at a mass ratio of 10:3, with vacuum degasing parameters of -0.1MPa for 30 minutes), let it stand for 10~15 minutes or vacuum degasing (-0.1MPa for 30 minutes); slowly open the injection valve (adjust the valve opening to 1 / 3~1 / 2), control the injection flow rate to 50~80mL / min, use negative pressure to draw the resin into the cavity, control the flow rate to prevent fiber displacement, observe the liquid level and wetting condition (check through the transparent observation window of the negative mold; areas without dry fibers indicate successful wetting), and close the injection valve after the resin has completely covered the preform to prevent backflow; S4. Pressurizing the bladder-type male mold: After resin impregnation, connect the pressurizing port to the injection equipment (model YQ32-100, pressure accuracy ±0.01MPa) through a high-pressure pipeline (material: 304 stainless steel, inner diameter 6mm, wall thickness 3mm, pressure resistance ≥1.8MPa) (pipeline pressure resistance ≥1.5 times the set pressure). Set the pressure to 0.8~1.2MPa (the carrier can be gas or liquid; if compressed air is selected, it must be dried, dew point ≤-40℃, oil-free and impurity-free). Open the pressurizing valve and slowly inject the carrier at a pressure rise rate of 0.1MPa / min. After holding the pressure for 5~8 minutes, close the valve, remove the injection box and all pipelines, and allow the bladder-type male mold to expand and apply uniform tension. S5. Pressurized Heating and Curing: Maintain pressurization (pressure stable at 0.8~1.2MPa), and place the module horizontally (levelness error ≤0.5°) into the heating and insulation box (model DHG-9240A, temperature control accuracy ±1℃). Heat from room temperature to 80℃ at a rate of 2~3℃ / min and hold for 1.5 hours, then heat to 120℃ and hold for 2.5 hours. Measure and replenish pressure every 30 minutes (if the pressure drop exceeds 0.1MPa, replenish pressure to the set value at a rate of 0.05MPa / min using an injection device). Ensure that the resin is completely cured and the fibers maintain uniform tension. After curing, cooling is required to prevent internal stress. S6. Module Cooling Treatment: After curing, first turn off the power to the insulation box and allow the module to cool naturally to 60℃ (natural cooling rate is about 1~2℃ / min, monitored in real time by the temperature sensor of the insulation box); then remove it and place it in a ventilated area for air cooling (the wind speed in the ventilation environment is controlled at 1~2m / s to avoid strong winds blowing directly), control the cooling rate at 5~8℃ / min, avoid strong winds blowing directly, and keep the module sealed to prevent deformation throughout the process; use a thermometer (accuracy ±0.5℃) to measure the surface temperature of the module in real time (the temperature measurement point is selected at the middle of the outer wall of the female mold, a total of 3 evenly distributed temperature measurement points, and the average value is taken), and wait until it drops to room temperature (25±5℃); S7. Demolding and Part Removal: After the module cools to room temperature, following the principle of "removing auxiliary components first, then removing the product," use a wrench (open-end wrench, matching the bolt specifications) to symmetrically remove the blind flange bolts (removal sequence is from symmetrical positions, with each removal torque ≤5N·m to avoid uneven force), and remove the blind flange and sealing ring; connect the bladder-type male mold to a negative pressure device (model 2XZ-1, vacuum rate 3L / min) to vacuum and shrink (negative pressure value -0.08~-0.09MPa, shrinkage time 5~8 minutes), and slowly remove it; if the female mold is stuck to the isolation sleeve, pad it with a soft cloth (microfiber cloth, 2mm thick) and tap the female mold (tapping force controlled at 5~10N, calibrated with a force gauge) or inject a release agent (model KM-900 silicone-based release agent, dosage 5mL / m). 2 Finally, the complete finished product was extracted.

[0024] The specific steps for mold assembly and sealing in step S1 are as follows: S11. Core Component Assembly: Precisely place the neatly cut continuous fiber preform (cutting size error controlled within ±1mm, no burrs on the edges) into the female mold cavity, leaving a specific gap—this gap, determined by preliminary testing, is 3±0.2mm. This gap must perfectly match the radial expansion dimension (3±0.2mm) of the preform under subsequent tension, to avoid deformation of the preform due to excessively small gaps or insufficient tension transmission due to excessively large gaps. Subsequently, slowly insert the expandable bladder-type male mold (smooth surface without impurities, thickness uniformity error ≤0.5mm), which is compatible with the resin (epoxy resin E-51 system), into the preform, ensuring that the bladder is centered (coaxiality deviation between the center of the bladder and the center of the female mold ≤0.3mm) and without wrinkles. S12. Module sealing and fixing: After assembly, cover the blind flange and align it with the female mold port. Insert the sealing ring to fill the contact gap, and then tighten the blind flange evenly with bolts. This step is necessary to ensure that the module is properly sealed to prevent air or glue leakage during subsequent vacuum suction, glue injection and pressurization.

[0025] The specific steps of the module vacuum pretreatment in step S2 are as follows: S21. Pre-treatment preparation and connection: First, close the injection valve corresponding to the injection port at the top of the female mold to cut off the injection channel and ensure the vacuum level; then connect the vacuum port at the bottom of the side of the female mold to the vacuum pump through a special pipeline. When connecting, check the sealing of the pipeline interface. You can wrap sealant tape to prevent air leakage and ensure that there is no leakage in the vacuum suction channel. S22. Vacuum suction and pressure holding: Turn on the vacuum valve and vacuum pump, set the negative pressure value to -0.095~-0.098MPa, and continuously suction the module cavity at a rate of 5L / min for 15~20 minutes. During this period, observe whether the vacuum degree is stable through a vacuum gauge (accuracy 0.001MPa). If the vacuum degree drops (more than 0.005MPa within 10 minutes), check the blind flange sealing ring (whether it is misaligned or aged) and the pipeline interface (whether it is loose) in sequence. Re-wrap the interface with polytetrafluoroethylene sealing tape (wrapping thickness 2±0.5mm) to repair the seal. After suction is completed, turn off the vacuum valve first and then turn off the vacuum pump to maintain the negative pressure in the cavity.

[0026] The specific steps of the resin injection operation in step S3 are as follows: S31. Resin Pretreatment and Injection Preparation: Pour a measured amount of liquid resin into the injection box (the amount of resin is calculated based on 1.2 times the volume of the preform, with allowance for loss). The resin needs to be mixed evenly in advance according to the formula (epoxy resin E-51: polyamide 650 = 10:3, mass ratio) (stirring speed 300r / min, stirring time 5 minutes, stirring temperature 25±3℃), and degassing is required—it can be left to stand for 10~15 minutes to allow the bubbles to float naturally, or vacuum degassing treatment can be used (-0.1MPa, 30 minutes, after degassing, the diameter of the bubbles in the resin is ≤0.1mm) to avoid the resin containing bubbles affecting the wetting effect; at this time, the module is still under negative pressure (the negative pressure value is stable at -0.095~-0.098MPa) to prepare for the resin to be sucked into the cavity; S32. Negative pressure injection and process control: Slowly open the injection valve at the injection port and use the negative pressure inside the cavity to draw the resin into the module cavity. During injection, adjust the valve opening to control the flow rate and prevent the flow rate from being too fast and impacting the preform, causing fiber displacement. Once the resin fully covers the preform and the liquid level no longer drops, immediately close the valve to prevent backflow.

[0027] The specific steps for applying pressure to the bladder-type male mold in step S4 are as follows: S41. Connection and parameter setting of pressurization equipment: Connect the pressurization port at the bottom of the blind flange to the injection equipment through a high-pressure pipeline. The pressure resistance of the pipeline must be no less than 1.5 times the set pressure to prevent rupture during pressurization. According to the design requirements of the isolation sleeve, set the pressure value of the injection equipment to 0.8~1.2MPa. The pressure carrier can be compressed air or hydraulic oil. The selected gas must be dry and free of impurities to prevent corrosion of the bladder. S42. Pressurization Operation and Pipeline Dismantling: Open the pressurization valve and slowly inject the pressure carrier into the cavity of the bladder-type male mold at a rate of 0.1 MPa / min (when selecting hydraulic oil, use L-AN46 anti-wear hydraulic oil with a kinematic viscosity of 40~50 mmHg at 40℃). 2 The pressure is monitored in real time by a pressure gauge (accuracy 0.005MPa) to prevent sudden pressure rise that could cause the capsule to rupture or the preform to be subjected to uneven stress. After the pressure reaches the set value (0.8~1.2MPa) and stabilizes for 5~8 minutes (pressure fluctuation ≤0.005MPa / min), the pressurization valve is closed, and the glue injection box, vacuum line and pressurization line are gently removed (the removal order is to remove the glue injection box first, then the vacuum line, and finally the pressurization line) to avoid module displacement affecting pressure stability. At this time, the capsule has applied uniform tension to the preform.

[0028] The specific steps of pressure heating and curing in step S5 are as follows: S51. Module placement and basic curing parameters: Smoothly place the pressure-bearing module into the heating and insulation box (temperature uniformity error within the box ≤ ±2℃). The module must be placed horizontally (calibrated with a level, horizontality error ≤ 0.5°) to prevent uneven resin distribution within the cavity due to tilting. If using epoxy resin (Epoxy Resin E-51 system), heat from room temperature to 80℃ at a rate of 2~3℃ / min (heating rate automatically controlled by the insulation box temperature control system, error ±0.2℃ / min) according to the process. Hold at this temperature for 1.5 hours (temperature fluctuation ≤ ±1℃ during the holding period) to allow the resin to initially crosslink (crosslinking degree reaches 40%~50%), laying the foundation for subsequent complete curing. S52. Curing temperature and pressure monitoring: After initial cross-linking, continue to heat to 120℃ and hold for 2.5 hours to ensure complete resin curing; record module pressure every 30 minutes throughout the curing process. If the pressure drop exceeds 0.1MPa, pressurize to the set value through the pressurization pipeline to ensure that the fiber preform is always under uniform tension and to avoid resin shrinkage that causes fiber relaxation. After curing, the cooling process can begin.

[0029] The specific steps of the module cooling process in step S6 are as follows: S61. Natural cooling inside the insulation box: After curing, turn off the power to the heating insulation box and let the module cool down naturally to 60℃. The cooling rate is slow at this stage, which can reduce the temperature difference between the inside and outside of the isolation sleeve and avoid internal stress caused by temperature difference. During the cooling period, the module must be kept sealed to prevent outside air from entering or the pressure inside the cavity from dropping suddenly, which could cause product deformation. S62. Post-removal air-cooling and temperature control: Remove the module from the insulation box and place it in a well-ventilated room temperature environment (ambient temperature 25±5℃, relative humidity 40%~60%) for air cooling. Avoid direct strong winds (wind deflectors can be placed around the module to control the wind speed at 1~2m / s). Indirect airflow can be achieved using a fan (FS-40 model, set to medium speed). Control the cooling rate at 5~8℃ / min (calculate by real-time temperature measurement, record the temperature every 5 minutes to ensure a stable rate). Use a thermometer (PT100 platinum resistance thermometer, accuracy ±0.5℃) to measure the surface temperature of the module in real time (measurement points are the upper, middle, and lower positions on the outer wall of the female mold, with even spacing, and take the average of the three points for each measurement). Once it drops to room temperature (25±5℃), the cooling process is complete, preparing for subsequent demolding and part removal.

[0030] The specific steps for demolding and removing the part in step S7 are as follows: S71. Auxiliary component removal: Following the principle of "removing auxiliary components first", use a wrench to symmetrically remove the connecting bolts between the blind flange and the female mold to prevent the blind flange from deforming due to uneven stress. After removing the bolts, gently remove the blind flange and the bottom sealing ring. Then connect the pressure port of the bladder-type male mold to the negative pressure equipment, draw a vacuum to shrink the bladder to its initial size, and slowly remove the bladder. S72. Product Separation and Removal: Check the fit between the female mold and the isolation sleeve (observe the gap between the female mold and the isolation sleeve; no obvious gap indicates adhesion). If there is local adhesion, a soft cloth (10cm x 10cm, 2mm thick, to avoid scratching the female mold) can be used to tap the outer wall of the female mold (tapping positions are the middle and both ends of the female mold, tapping each end 3-5 times with a force of 5-10N), or a small amount of release agent (KM-900 silicone-based release agent, injection amount 0.5-1mL / position, let stand for 2-3 minutes after injection) can be injected into the gap to assist separation. Once the female mold and the isolation sleeve are completely separated (the separation is qualified if the isolation sleeve can be moved without resistance when gently pushed by hand), the complete high-strength composite material isolation sleeve can be removed, completing the entire molding process.

[0031] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0032] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for molding a high-strength composite material isolation sleeve, characterized in that: The specific steps of this method are as follows: S1. Mold assembly and sealing: Place the continuous fiber preform into the female mold cavity, leaving a gap that matches the tension expansion size of the preform; then install the bladder-type male mold, cover it with the blind flange and embed the sealing ring, and tighten the bolts to seal. S2. Module vacuum pretreatment: First, close the glue injection valve at the glue injection port, connect the vacuum pump to the vacuum tube port and check the sealing; open the vacuum valve and vacuum pump to perform negative pressure suction, and close the vacuum valve and vacuum pump after the vacuum degree stabilizes. S3. Resin injection operation: Pour a measured amount of degassing resin into the injection box, open the injection valve, and use negative pressure to draw the resin into the cavity. After the resin fully covers the preform, close the injection valve to prevent backflow. S4. Pressure application of bladder-type male mold: Connect the pressure application port to the injection equipment, open the pressure valve to slowly inject the carrier, maintain pressure for 5-8 minutes, then close the pressure valve and remove the injection box and all pipelines. S5. Pressurized heating and curing: Maintain pressure and horizontally send the module into the heating and insulation box; if using epoxy resin, test and replenish the pressure every 30 minutes to ensure that the resin is completely cured and the fibers maintain uniform tension. S6. Module cooling treatment: After curing, first turn off the power of the insulation box and let the module cool down naturally to 60℃; then take it out and place it in a ventilated place for air cooling, keeping the module sealed and preventing deformation throughout the process; monitor the temperature in real time to bring the module down to room temperature. S7. Demolding and Part Removal: After the module cools down to room temperature, use a wrench to symmetrically remove the blind flange bolts, and remove the blind flange and sealing ring; connect the bladder-type male mold to a negative pressure device to evacuate and shrink it, and slowly remove it.

2. The molding method of a high-strength composite material isolation sleeve according to claim 1, characterized in that: The specific steps for mold assembly and sealing in step S1 are as follows: S11. Core component assembly: Place the continuous fiber preform into the female mold cavity, leaving a gap that is perfectly matched with the radial expansion dimension of the preform under subsequent tension; then place the resin-compatible expandable bladder male mold into the preform, ensuring that the bladder is centered and wrinkle-free. S12. Module sealing and fixing: After assembly, cover the blind flange and align it with the female mold port, insert the sealing ring to fill the contact gap, and then tighten the blind flange evenly with bolts.

3. The molding method of a high-strength composite material isolation sleeve according to claim 1, characterized in that: The specific steps of the module vacuum pretreatment in step S2 are as follows: S21. Pre-treatment preparation and connection: First, close the injection valve corresponding to the injection port at the top of the female mold to cut off the injection channel; then connect the vacuum port at the bottom of the side of the female mold to the vacuum pump through the pipeline, and keep the pipeline interface sealed during connection. S22. Vacuum suction and pressure holding: Open the vacuum valve and vacuum pump, set the negative pressure value to -0.095~-0.098MPa, and continuously suction the module cavity for 15~20 minutes. After suction is completed, close the vacuum valve first and then turn off the vacuum pump to maintain the negative pressure in the cavity.

4. The molding method of a high-strength composite material isolation sleeve according to claim 1, characterized in that: The specific steps of the resin injection operation in step S3 are as follows: S31. Resin pretreatment and injection preparation: Pour a certain amount of liquid resin into the injection box. The resin needs to be mixed evenly according to the formula in advance and vacuum degassing is used. At this time, the module is still under negative pressure. S32. Negative pressure injection and process control: Open the injection valve at the injection port and use the negative pressure inside the cavity to draw the resin into the module cavity. During injection, adjust the valve opening to control the flow rate. Once the resin fully covers the preform and the liquid level no longer drops, monitor the injection valve to prevent backflow.

5. The molding method of a high-strength composite material isolation sleeve according to claim 1, characterized in that: The specific steps for applying pressure to the bladder-type male mold in step S4 are as follows: S41. Connection and parameter setting of pressurizing equipment: Connect the pressurizing port at the bottom of the blind flange to the injection equipment through a pipeline. The pressure resistance of the pipeline shall not be less than 1.5 times the set pressure. Set the pressure value of the injection equipment to 0.8~1.2MPa. The pressure carrier shall be either compressed air or hydraulic oil. S42. Pressurization Operation and Pipeline Removal: Open the pressurization valve and inject the pressure carrier into the cavity of the bladder-type male mold. After the pressure reaches the set value and stabilizes for 5-8 minutes, close the pressurization valve and remove the glue injection box, vacuum pipeline and pressurization pipeline.

6. The molding method of a high-strength composite material isolation sleeve according to claim 1, characterized in that: The specific steps of pressurized heating and curing in step S5 are as follows: S51, Module placement and basic curing parameters: Place the module in the pressure-holding state into the heating and insulation box, keeping it horizontal. According to the process, heat it from room temperature to 80°C at a rate of 2~3°C / min, and keep it at this temperature for 1.5 hours to allow the resin to initially crosslink. S52. Curing temperature and pressure monitoring: After initial cross-linking, continue to heat to 120℃ and hold for 2.5 hours to ensure complete resin curing; record module pressure every 30 minutes throughout the curing process, and enter the cooling phase after curing is completed.

7. The molding method of a high-strength composite material isolation sleeve according to claim 1, characterized in that: The specific steps of the module cooling process in step S6 are as follows: S61. Natural cooling inside the insulation box: After curing, turn off the power to the heating insulation box and allow the module to cool down naturally to 60°C. Keep the module sealed during the cooling process. S62. After removal, air-cooling and temperature control: Remove the module from the insulation box and place it in a ventilated room temperature environment for air cooling, controlling the cooling rate at 5~8℃ / min; measure the surface temperature of the module with a thermometer in real time, and complete the cooling process when it drops to room temperature.

8. The molding method of a high-strength composite material isolation sleeve according to claim 1, characterized in that: The specific steps for demolding and removing the part in step S7 are as follows: S71. Auxiliary component removal: Use a wrench to symmetrically remove the connecting bolts between the blind flange and the female mold, then remove the blind flange and the bottom sealing ring, then connect the pressure port of the bladder-type male mold to the negative pressure equipment, draw a vacuum to shrink the bladder to its initial size, and then remove the bladder. S72. Product Separation and Removal: Check the fit between the female mold and the isolation sleeve. Use a soft cloth to tap the outer wall of the female mold. Once the female mold and the isolation sleeve are completely separated, the finished composite material isolation sleeve can be removed.

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