Composite hose and method of manufacture and use thereof

Abstract

The application relates to the technical field of fluid conveying pipes, in particular to a composite hose and a preparation method and application thereof. The preparation method comprises the following steps: cleaning a core rod and pipe manufacturing equipment and coating silicon oil, and pre-winding woven cloth; cleaning an inner steel wire and winding to form a skeleton with outward tension; winding a first film, a woven fabric and a second film to form a contact structure layer, a tensile structure layer and a sealing structure layer; winding an outer steel wire to provide inward constraint; dismounting the pipe and performing endoscopic detection and cleaning; performing passivation treatment on the inside of the pipe body; vertically connecting the pipe and vertically placing the pipe; and finally cleaning to reach a predetermined standard. Through systematic cleanliness control, passivation treatment and vertical pipe connecting process, the cleanliness, sealing reliability and anti-corrosion performance of the composite hose are improved, so that the high cleanliness, high sealing reliability and anti-corrosion requirements of spaceflight fuel filling are met, and the safety and reliability of the hose in spaceflight application are remarkably improved.

Description

Technical Field

[0001] This application relates to the field of fluid transport pipe technology, specifically to a composite hose, its preparation method, and its application. Background Technology

[0002] Space fuel loading is a core pre-launch safety procedure for rockets, and the safety and reliability of its delivery system directly impact the success or failure of the mission. With the development of new-generation high-thrust launch vehicles, the requirements for propellant flow rate and purity (such as liquid oxygen, liquid methane, and high-energy aviation kerosene) are becoming increasingly stringent. This places extremely high demands on the performance of delivery hoses: they must not only withstand extreme cryogenic conditions but also simultaneously meet comprehensive performance requirements including cryogenic tolerance, resistance to thermal stress deformation, and good flexibility. Space fuel loading typically employs metal corrugated pipes, composite hoses, and rubber hoses. However, metal corrugated pipes suffer from drawbacks such as heavy weight, poor flexibility, and unsatisfactory performance at low temperatures, while rubber hoses are prone to embrittlement at low temperatures, leading to leakage of the transported medium.

[0003] Currently, there are composite hoses developed in the industry for transporting cryogenic media, whose mechanical structural properties meet the requirements for pipelines transporting cryogenic liquids. For example, a known disclosed solution (shown in the invention patent application CN202410211337.0) typically uses inner and outer steel wire skeletons to clamp tensile and sealing structural layers to meet basic mechanical performance requirements such as pressure resistance and tensile strength. While this type of solution solves the problem of transporting general cryogenic media to some extent, hoses used in the aerospace fuel refueling field, in addition to meeting the basic mechanical performance requirements such as pressure resistance and tensile strength for transporting cryogenic media, must also possess extremely high internal cleanliness, sealing reliability, and corrosion resistance. The aforementioned existing composite hoses for transporting cryogenic media do not take into account the special characteristics of aerospace fuel refueling in their design and process settings, and have the following shortcomings:

[0004] Lack of Cleanliness Control: The existing manufacturing process lacks systematic cleanliness control. Key steps such as mandrel and equipment cleaning, steel wire cleaning, and final purification of the finished tube are not addressed, resulting in the easy retention of processing oil, metal shavings, fiber dust, and other foreign matter inside the hose. These foreign matter may enter the rocket fuel system with the fluid during aerospace fuel delivery, causing blockage of precision valves, sensor malfunctions, or engine ignition failures, leading to catastrophic consequences.

[0005] Insufficient rust resistance: The metal wire skeleton inside the hose is prone to rust in humid environments, and current technology does not incorporate any effective rust prevention treatment (such as passivation). Rust products not only contaminate high-purity fuels but also weaken the mechanical properties of the wire, posing a safety hazard for long-term use.

[0006] Sealing reliability is questionable: During joint installation, traditional pipe-connecting methods can easily lead to uneven distribution or even overflow of the sealing colloid inside the joint due to gravity, resulting in weak local seals. Under complex alternating loads, this can easily lead to cryogenic media leakage. Aerospace fuels are typically flammable, explosive, or highly oxidizing; even minor leaks can potentially cause safety accidents.

[0007] Therefore, there is an urgent need in this field to develop a composite hose and its preparation method to improve the cleanliness, corrosion resistance and sealing reliability of the composite hose, making the composite hose suitable for aerospace fuel refueling. Summary of the Invention

[0008] In view of the problems of the prior art mentioned in the background, this application provides a method for preparing a composite hose for aerospace fuel refueling.

[0009] The method for preparing this composite hose includes the following steps:

[0010] S1: Clean the mandrel and tube-making equipment with ethanol and cloth, coat the mandrel with water-soluble silicone oil, and then wrap it with a layer of ultra-high molecular weight polyethylene woven cloth.

[0011] S2: Clean the inner steel wire by wrapping it with a cloth soaked in ethanol, and then wind the inner steel wire around the mandrel at equal intervals with the first pitch. After locking and constraining, it provides outward elastic pretension.

[0012] S3: The first thin film material is wound around the inner steel wire at a first angle to form a contact structure layer based on a preset width and a specified overlap rate;

[0013] S4: The woven fabric is wound around the contact structure layer at a second angle to form a tensile structure layer based on a preset width and a specified overlap ratio;

[0014] S5: The second film material is wound around the tensile structural layer at a third angle, and after being wound to an even number of layers, it overlaps to form a sealed structural layer;

[0015] S6: The outer steel wire is wound around the sealing structure layer at equal intervals with the second pitch, and is staggered with the inner steel wire to provide inward plastic constraint force, thus obtaining the tube body of the composite hose;

[0016] S7: Remove the tube from the mandrel and perform endoscopic inspection. After passing the inspection, clean the inside of the tube to remove water-soluble silicone oil.

[0017] S8: Passivation treatment is performed on the inside of the tube body;

[0018] S9: Place the pipe body vertically, install the connector to both ends of the pipe body, keep the pipe body vertical during installation, and keep it vertical after clamping;

[0019] S10: Perform a final cleaning of the hose used for installing the connector to bring the hose to the predetermined standard.

[0020] In some embodiments, in step S1, the mandrel and tube-making equipment are cleaned with ethanol and cotton cloth, water-soluble silicone oil is coated on the mandrel, and then a layer of ultra-high molecular weight polyethylene woven fabric is wound around it; wherein the consistency of the water-soluble silicone oil is 2500 centipoise.

[0021] In some embodiments, in step S2, the inner steel wire is cleaned by wrapping it with a lint-free cloth soaked in ethanol; the inner steel wire has a wire diameter of 2 mm to 6 mm, a first pitch of 12 mm to 24 mm, a tensile strength of 900 MPa to 950 MPa, and a radial outward pretension of more than 15% after locking and restraint.

[0022] In some embodiments, in step S3, the first film material is a PTFE film material.

[0023] In some embodiments, in step S4, the woven fabric is made of aramid or ultra-high molecular weight polyethylene, and the second angle is greater than 40°.

[0024] In some embodiments, in step S5, the second film material is polyimide or ultra-high molecular weight polyethylene, and the third angle is greater than 40°.

[0025] In some embodiments, in step S4, by setting a second angle greater than 40° and a preset width and a specified overlap rate, the braid is wound on the mandrel to form a tensile structural layer, so that the tensile structural layer has the same cross-sectional size at any length of the tube, and the starting position of the even-numbered layers is half of the overlap rate.

[0026] In some embodiments, in step S5, by setting a third angle greater than 40° and a preset width and specified overlap rate, the film material is wound and formed on the mandrel to form a sealing structure layer, so that the sealing structure layer has the same cross-sectional size at any length of the tube, and the starting position of the even-numbered layers is half of the overlap rate.

[0027] In some embodiments, the tensile structural layer is wound at a large angle with a second angle greater than 40° only when the pipe diameter is DN100 or above.

[0028] In some embodiments, the sealing structure layers are all wound at a large angle with a third angle greater than 40°.

[0029] In some embodiments, in step S6, the outer wire diameter is 2mm to 6mm, and the second pitch is 12mm to 24mm.

[0030] In some embodiments, in step S8, the tube body is immersed in a passivation soaking solution for passivation treatment.

[0031] In some embodiments, in step S10, the final cleaning process includes degreasing, ethanol rinsing, pure water rinsing, air drying, and endoscopic examination; the predetermined criteria include:

[0032] The diameter of non-metallic particles in the inner wall of the tube is ≤50μm;

[0033] No excess metal objects are allowed on the inner wall of the tube.

[0034] No material should be missing or damaged in the inner wall of the pipe where it comes into contact with the transmission medium.

[0035] No fibrous material with a length of ≥2mm is allowed in the inner wall of the tube;

[0036] Oil or rust are not allowed on the inner wall of the pipe.

[0037] This application also provides a composite hose for aerospace fuel refueling, which is manufactured by the method described above, and includes a hose body and a connector disposed at the end of the hose body; the hose body includes an inner steel wire, a contact structure layer, a tensile structure layer, a sealing structure layer and an outer steel wire arranged from the inside to the outside; wherein, the connector includes an inner spiral tube, an outer steel ring welded to the outside of the inner spiral tube and a flange disposed at the end of the inner spiral tube; the outer ring of the inner spiral tube is in contact with the contact structure layer and the inner steel wire, the inner ring of the outer steel ring is in contact with the outer surface of the sealing structure layer and the outer steel wire, and a sealing ring is disposed inside the outer ring layer.

[0038] This application also provides an application of the composite hose described above in an aerospace fuel refueling system, which is used as a composite hose for aerospace fuel refueling.

[0039] Based on the above, compared with the prior art, this application has the following beneficial effects:

[0040] This application improves the cleanliness, sealing reliability, and corrosion resistance of composite hoses through systematic cleanliness control, passivation and rust prevention treatment, and vertical pipe connection process. This meets the high cleanliness, high sealing reliability, and corrosion resistance requirements of aerospace fuel refueling, and significantly enhances the safety and reliability of hoses in aerospace applications.

[0041] Other features and beneficial effects of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The purpose and other beneficial effects of this application can be realized and obtained from the description and claims. Attached Figure Description

[0042] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0043] Figure 1 This is a schematic diagram of the overall structure of the composite hose of this application.

[0044] Figure 2 yes Figure 1 A partial cross-sectional view of the composite hose.

[0045] Figure label:

[0046] 1. Connector; 2. Pipe body; 3. Flange; 4. Internal threaded tube; 5. Outer steel ring; 6. Inner steel wire; 7. Contact structural layer; 8. Tensile structural layer; 9. Sealing structural layer; 10. Outer steel wire. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. The technical features designed in the different implementations of this application described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0048] In the description of this application, it should be noted that all terms used in this application (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains, and should not be construed as limiting this application; it should be further understood that the terms used in this application should be understood to have the same meaning as those in the context of this specification and the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this application.

[0049] like Figure 1-2 As shown, this application provides an example of a composite hose for aerospace fuel refueling and its preparation method:

[0050] The method includes the following steps:

[0051] Step 1: Clean the mandrel and tube-making equipment with ethanol and cotton cloth, coat the mandrel with water-soluble silicone oil, and then wrap it with a layer of ultra-high molecular weight polyethylene woven fabric; wherein the consistency of the water-soluble silicone oil is 2500 centipoise.

[0052] The purpose of this step is to prevent the inner steel wire 6 from being damaged due to friction between the inner steel wire 6 and the mandrel during the unloading process. The silicone oil helps to remove the final product from the mandrel (which can be understood as demolding). Furthermore, the pre-wrapping of the mandrel with ultra-high molecular weight polyethylene woven fabric can prevent some foreign matter from entering the tube body 2.

[0053] Step 2: Clean the inner steel wire 6 by wrapping it with a lint-free cloth soaked in ethanol. Wrap the inner steel wire 6 around the mandrel at equal intervals with the first pitch, and provide outward elastic pretension after locking and constraining. The inner steel wire 6 has a wire diameter of 2mm to 6mm, a first pitch of 12mm to 24mm, a tensile strength of 900MPa to 950MPa, and a radial outward pretension of more than 15% after locking and constraining.

[0054] The purpose of this cleaning step is to clean the steel wire by wrapping it with a lint-free cloth soaked in ethanol, in order to ensure the cleanliness of the steel wire.

[0055] Step 3: The first film material is wound around the inner steel wire 6 at a first angle to form a contact structure layer 7 based on a preset width and a specified overlap rate; wherein, the first film material is a PTFE film material. Preferably, a large-angle winding with a first angle greater than 40° is used, and the thickness after winding and overlapping is 0.45mm to 0.9mm.

[0056] The purpose of using a PTFE film material separately from the tensile structure layer 8 in the contact structure layer 7 is that the PTFE-formed contact layer has an extremely low coefficient of friction, a smooth surface, and extremely low material adhesion, making it easy to clean. This results in very little residue on the inside of the composite hose when transporting oil, preventing the release of chemical substances and ensuring the cleanliness of the composite hose, thereby guaranteeing the cleanliness of the transported oil.

[0057] Step 4: The braided material is wound around the contact structure layer 7 at a second angle to form a tensile structure layer 8 based on a preset width and specified overlap rate; wherein, the braided material is aramid or ultra-high molecular weight polyethylene. Preferably, when the pipe diameter is DN100 or above, the tensile structure layer 8 is wound at a large angle with a second angle greater than 40°, and the thickness after the overlap is 0.3mm to 0.75mm.

[0058] Step 5: The second film material is wound around the tensile structural layer 8 at a third angle, and after winding to an even number of layers, it is overlapped to form a sealing structural layer 9; wherein, the second film material is polyimide or ultra-high molecular weight polyethylene. Preferably, the third angle is greater than 40°, and the thickness after winding and overlapping is 0.03mm to 0.1mm.

[0059] Note: For the tensile structural layer 8 and the sealing structural layer 9, the mandrel is wound around the mandrel at a large angle (winding angle between the mandrel and the structural layer greater than 40°) and with a predetermined width and overlap rate. This ensures that the cross-sectional dimensions are equal along any length of the tube, and the starting position of even-numbered layers is half the overlap rate. This allows the overall structure to exhibit a mechanical property distribution close to that of a continuous tube, as well as better sealing performance.

[0060] Step 6: The outer steel wire 10 is wound around the sealing structure layer 9 at equal intervals with the second pitch, and is staggered with the inner steel wire 6 to provide inward plastic constraint force, thus obtaining the tube body 2 of the composite hose; wherein, the outer steel wire 10 has a wire diameter of 2mm to 6mm, a second pitch of 12mm to 24mm, and a tensile strength of 800MPa to 850MPa.

[0061] Step 7: Remove tube 2 from the mandrel and perform endoscopic inspection. After passing the inspection, clean the inside of tube 2 to remove water-soluble silicone oil.

[0062] The purpose of endoscopic inspection after tube removal is to preliminarily confirm whether the internal steel wires of tube body 2 are damaged and the integrity of the contact layer. Aerospace tubes are not allowed to have any material detachment or damage in the parts of the tube body that come into contact with the transmission medium. If this inspection fails, the produced hose cannot proceed to the next connection process. The purpose of endoscopic inspection is to check for damage to the steel wires and contact layer, and for the presence of foreign objects inside the tube. After passing the inspection, tube body 2 will be cleaned to remove water-soluble silicone oil and prepare for the next passivation step.

[0063] Step 8: Passivate the inside of tube body 2 by immersing it in a passivation solution for 30 minutes. The passivation solution is an acid-based passivation solution, whose components include inorganic acid, organic acid, oxidant, complexing agent, and corrosion inhibitor. The passivation process is as follows:

[0064] 1) Fix the hose in a U-shape (with both ends of the hose at the same horizontal level);

[0065] 2) Pour in the passivation soaking solution, ensuring the liquid level is ≤120mm from both ends of the pipe;

[0066] 3) Soak for 30 minutes;

[0067] 4) The passivation soaking solution is discharged through an ethanol pump and collected in a special container.

[0068] The purpose of passivation is to further enhance the rust and corrosion resistance of the inner steel wire 6 in the pipe body 2. The steel wire itself may have minor damage before pipe making, and passivation helps to reduce damage and improve its rust and corrosion resistance.

[0069] Step 9: Place the tube body 2 vertically and install the connector 1 to both ends of the tube body 2. Keep the tube body 2 vertical during installation and keep it upright after clamping.

[0070] The purpose of vertical placement: Traditional pipe connection methods involve placing the pipe body 2 horizontally and then screwing the connector 1 in along the direction of the wire. The connector 1 is screwed into the pipe body 2 to the specified length and then crimped. The advantage of vertical placement is that, because the connector 1 is coated with a sealant, horizontal pipe connection and placement cause the sealant inside the connector 1 to overflow and slowly flow to the bottom. This uneven distribution of the sealant inside the connector 1 may lead to seal failure. In a vertical position, the sealant only flows towards the inside of the connector 1 and does not accumulate in any one location.

[0071] Step 10: Perform a final cleaning of the hose connecting connector 1. The final cleaning process includes degreasing, ethanol rinsing, pure water rinsing, air drying, and endoscopic inspection to bring the hose to a predetermined standard, which includes:

[0072] The diameter of non-metallic particles in the inner wall of tube 2 is ≤50μm;

[0073] No excess metal objects are allowed on the inner wall of tube body 2;

[0074] Material must not be detached or damaged in the inner wall of the tube body 2 where the inside of the tube body is in contact with the transmission medium;

[0075] No fibrous material with a length of ≥2mm is allowed in the inner wall of tube body 2;

[0076] Oil or rust is not allowed on the inner wall of the tube body 2.

[0077] The final cleaning purpose is to further clean and flush away grease and excess material inside pipe body 2 to ensure the hose meets the final requirements. The air-drying process is to remove moisture from inside pipe body 2 after cleaning, preventing the internal steel wires from rusting.

[0078] like Figure 1-2 As shown, the composite hose structure for aerospace fuel refueling prepared by the above method is as follows:

[0079] The composite hose includes a hose body 2 (also known as the hose main body) and a connector 1 disposed at the end of the hose body 2; the hose body 2 includes an inner steel wire 6, a contact structure layer 7, a tensile structure layer 8, a sealing structure layer 9 and an outer steel wire 10 arranged from the inside to the outside;

[0080] The connector 1 includes an inner threaded tube 4, an outer steel ring 5 welded to the outside of the inner threaded tube 4, and a flange 3 disposed at the end of the inner threaded tube 4; the outer ring of the inner threaded tube 4 is in contact with the contact structure layer 7 and the inner steel wire 6, the inner ring of the outer steel ring 5 is in contact with the outer surface of the sealing structure layer 9 and the outer steel wire 10, and a sealing ring is provided inside the outer ring layer.

[0081] To verify the effectiveness of this application, the following embodiments and comparative examples are also provided:

[0082] Example 1

[0083] Pipe type: ASCL-10.5-150 (DN=150)

[0084] The method for preparing composite hoses includes the following steps:

[0085] Step 1: Clean the mandrel and tube-making equipment with ethanol and cotton cloth, coat the mandrel with water-soluble silicone oil, and then wrap it with a layer of ultra-high molecular weight polyethylene woven fabric; wherein the consistency of the water-soluble silicone oil is 2500 centipoise.

[0086] Step 2: Clean the inner steel wire by wrapping it with a lint-free cloth soaked in ethanol. Wrap the inner steel wire around the mandrel at equal intervals with the first pitch and lock it in place to provide outward elastic pretension. The inner steel wire has a diameter of 6 mm, a first pitch of 20 mm, a tensile strength of 900 MPa, and a radial outward pretension of more than 15% after locking.

[0087] Step 3: The first film material is wound around the inner steel wire at a first angle to form a contact structure layer based on a preset width and specified overlap rate; wherein, the first film material is PTFE film material. A large-angle winding of 46° is used, and the thickness after winding and overlap is 0.9mm;

[0088] Note: When winding the contact structure layer, the mandrel is wound and shaped according to the angle and the set width and overlap rate (overlap rate) so that the cross-sectional dimensions are equal in any cross-section along the effective length of the tube, and the starting position of even-numbered layers is half of the overlap rate (overlap rate).

[0089] Step 4: The woven fabric is wound around the contact structure layer at a second angle to form a tensile structural layer based on a preset width and specified overlap rate; wherein, the woven fabric is made of aramid or ultra-high molecular weight polyethylene, and the tensile structural layer is wound at a large angle of 60.1° when the pipe diameter is DN100 or above, and the thickness after the overlap is 1.1mm;

[0090] Step 5: Wrap the second film material around the tensile structural layer at a third angle, and overlap to form a sealed structural layer after wrapping to an even number of layers; wherein, the second film material is polyimide or ultra-high molecular weight polyethylene, the third angle is 60.1°, and the thickness after wrapping and overlapping is 0.06mm.

[0091] Note: When winding the tensile structural layer and sealing structural layer, the mandrel is wound on the mandrel at a large angle (winding angle between the mandrel and the structural layer is greater than 40°) and with a set width and overlap rate (overlap rate) to make the cross-sectional dimensions of any section in the effective length of the tube equal, and the starting position of even-numbered layers is half of the overlap rate (overlap rate).

[0092] Step 6: The outer steel wire is wound around the sealing structure layer at equal intervals with the second pitch, and is staggered with the inner steel wire to provide inward plastic constraint force, thus obtaining the tube body of the composite hose; wherein, the outer steel wire has a wire diameter of 6mm, a second pitch of 20mm, and a tensile strength of 850MPa.

[0093] Step 7: Remove the tube from the mandrel and perform an endoscopic inspection to preliminarily confirm whether the internal steel wires of the tube are damaged and the integrity of the contact layer. Aerospace tubes are not allowed to have any material falling off or broken in the part of the tube that is in contact with the transmission medium. If this process fails the inspection, the produced hose cannot enter the next connection process.

[0094] After passing the inspection, the inside of the tube is cleaned to remove water-soluble silicone oil. The specific cleaning process is as follows: After passing the inspection, pure water is used to rinse the inner wall of the hose back and forth once through a high-pressure nozzle (commonly known as "water rat") to remove water-soluble silicone oil.

[0095] Step 8: Passivate the inside of the tube body. Immerse tube body 2 in the passivation solution for 30 minutes. The passivation solution used is an acid-based passivation solution, specifically Chuangjiexuan CJX1-21. The passivation process is as follows:

[0096] 1) Fix the hose in a U-shape (with both ends of the hose at the same horizontal level);

[0097] 2) Pour in the passivation soaking solution, ensuring the liquid level is ≤120mm from both ends of the pipe;

[0098] 3) Soak for 30 minutes;

[0099] 4) The passivation soaking solution is discharged through an ethanol pump and collected in a special container.

[0100] Step 9: Place the pipe vertically and install the connectors to both ends of the pipe. Keep the pipe vertical during installation and keep it upright after clamping.

[0101] Step 10: Perform a final cleaning of the hose for the installation connector. The final cleaning process includes degreasing, ethanol rinsing, pure water rinsing, air drying, and endoscopic inspection to bring the hose to a predetermined standard.

[0102] Example 2

[0103] Pipe type: ASCL-10.5-100 (DN=100)

[0104] The method for preparing composite hoses includes the following steps:

[0105] Step 1: Clean the mandrel and tube-making equipment with ethanol and cotton cloth, coat the mandrel with water-soluble silicone oil, and then wrap it with a layer of ultra-high molecular weight polyethylene woven fabric; wherein the consistency of the water-soluble silicone oil is 2500 centipoise.

[0106] Step 2: Clean the inner steel wire by wrapping it with a lint-free cloth soaked in ethanol. Wrap the inner steel wire around the mandrel at equal intervals with the first pitch and lock it in place to provide outward elastic pretension. The inner steel wire has a diameter of 4 mm, a first pitch of 16 mm, a tensile strength of 900 MPa, and a radial outward pretension of more than 15% after locking.

[0107] Step 3: The first film material is wound around the inner steel wire at a first angle to form a contact structure layer based on a preset width and specified overlap rate; wherein, the first film material is PTFE film material. A large-angle winding of 49° is used, and the thickness after winding and overlap is 0.9mm;

[0108] Note: When winding the contact structure layer, the mandrel is wound and shaped according to the angle and the set width and overlap rate (overlap rate) so that the cross-sectional dimensions are equal in any cross-section along the effective length of the tube, and the starting position of even-numbered layers is half of the overlap rate (overlap rate).

[0109] Step 4: The braided material is wound around the contact structure layer at a second angle to form a tensile structural layer based on a preset width and specified overlap rate; wherein, the braided material is aramid or ultra-high molecular weight polyethylene, and the tensile structural layer is wound at a large angle of 43.5° when the pipe diameter is DN100 or above, and the thickness after the wrapping overlap is 1.1mm;

[0110] Step 5: Wrap the second film material around the tensile structural layer at a third angle, and overlap it after wrapping to an even number of layers to form a sealed structural layer; wherein, the second film material is polyimide or ultra-high molecular weight polyethylene, the third angle is 43.5°, and the thickness after wrapping and overlapping is 0.06mm.

[0111] Note: When winding the tensile structural layer and sealing structural layer, the mandrel is wound on the mandrel at a large angle (winding angle between the mandrel and the structural layer is greater than 40°) and with a set width and overlap rate (overlap rate) to make the cross-sectional dimensions of any section in the effective length of the tube equal, and the starting position of even-numbered layers is half of the overlap rate (overlap rate).

[0112] Step 6: The outer steel wire is wound around the sealing structure layer at equal intervals with the second pitch, and is staggered with the inner steel wire to provide inward plastic constraint force, thus obtaining the tube body of the composite hose; wherein, the outer steel wire has a wire diameter of 4mm, a second pitch of 16mm, and a tensile strength of 850MPa.

[0113] Step 7: Remove the tube from the mandrel and perform an endoscopic inspection to preliminarily confirm whether the internal steel wires of the tube are damaged and the integrity of the contact layer. Aerospace tubes are not allowed to have any material falling off or broken in the part of the tube that is in contact with the transmission medium. If this process fails the inspection, the produced hose cannot enter the next connection process.

[0114] After passing the inspection, the inside of the tube is cleaned to remove water-soluble silicone oil. The specific cleaning process is as follows: After passing the inspection, pure water is used to rinse the inner wall of the hose back and forth once through a high-pressure nozzle (commonly known as "water rat") to remove water-soluble silicone oil.

[0115] Step 8: Passivate the inside of the tube body. Immerse tube body 2 in the passivation solution for 30 minutes. The passivation solution used is an acid-based passivation solution, specifically Chuangjiexuan CJX1-21. The passivation process is as follows:

[0116] 1) Fix the hose in a U-shape (with both ends of the hose at the same horizontal level);

[0117] 2) Pour in the passivation soaking solution, ensuring the liquid level is ≤120mm from both ends of the pipe;

[0118] 3) Soak for 30 minutes;

[0119] 4) The passivation soaking solution is discharged through an ethanol pump and collected in a special container.

[0120] Step 9: Place the pipe vertically and install the connectors to both ends of the pipe. Keep the pipe vertical during installation and keep it upright after clamping.

[0121] Step 10: Perform a final cleaning of the hose for the installation connector. The final cleaning process includes degreasing, ethanol rinsing, pure water rinsing, air drying, and endoscopic inspection to bring the hose to a predetermined standard.

[0122] Comparative Example 1

[0123] This comparative example adopts the scheme of Embodiment 1 disclosed in the invention patent application number CN202410211337.0. Specifically, the difference between this comparative example and Embodiment 1 of this application is that the comparative example method does not include the following steps of Embodiment 1: S1 cleaning and applying silicone oil, S2 cleaning of the inner steel wire, S7 endoscope inspection, S8 passivation, S9 vertical connection (instead using the traditional horizontal connection method), and S10 final cleaning step. Furthermore, the contact structure layer is made of non-PTFE material (hydrophobic tensile-resistant cotton cloth).

[0124] Comparative Example 2 (lacking cleanliness control steps)

[0125] Based on Example 1, the cleaning and silicone oil application steps S1, the wire cleaning step S2, and the final cleaning step S10 are omitted.

[0126] Comparative Example 3 (Missing passivation step)

[0127] Based on Example 1, only the S8 passivation process is omitted, while the other steps remain unchanged.

[0128] Comparative Example 4 (Horizontal Takeover Comparison)

[0129] Based on Example 1, only the vertical direct pipe of S9 is changed to a traditional horizontal direct pipe and placement.

[0130] Performance tests were conducted on the products of the embodiments and comparative examples.

[0131] The test results of the cleanliness, corrosion, and joint sealing effect of the composite hoses prepared in the specific embodiments and comparative examples are shown in Table 1:

[0132] Table 1

[0133]

[0134] In Table 1, all items were obtained by direct detection and evaluation after processing in step 10.

[0135] The performance test results of the composite hose prepared in Specific Embodiment 1 are shown in Table 2:

[0136] Table 2

[0137]

[0138] The test methods or standards for each test item are as follows:

[0139] Table 1 shows the internal condition of the tube body inspected and recorded using an endoscope for each item.

[0140] The methods or standards for the testing items in Table 2 are GB / T 39248-2020.

[0141] The test results show that:

[0142] The composite hoses in Examples 1-2 showed the best cleanliness, corrosion, and joint sealing performance.

[0143] Compared to the embodiments, the composite hose of Comparative Example 1 failed to meet the standards in terms of cleanliness and corrosion, and the joint sealing effect was poor.

[0144] Compared to the example, the cleanliness and corrosion of the composite hose in Comparative Example 2 did not meet the standards.

[0145] Compared to the examples, the corrosion in Comparative Example 3 did not meet the standards.

[0146] Compared to the embodiments, the joint sealing effect of Comparative Example 4 is not good.

[0147] In summary, the proposed solution has at least the following design concepts and beneficial effects:

[0148] Key design points, control points, and design concepts of this application:

[0149] I. Conception of Key Design Points and Control Points

[0150] The core design concept of this application is to upgrade composite hoses into aerospace fuel refueling hoses capable of meeting the extreme operating conditions of aerospace through a systematic "preparation-testing-post-processing" process. Its key design and control points are as follows:

[0151] Cleanliness control at the source and throughout the process

[0152] Design point: Introduce multiple cleaning and rinsing processes at the beginning of tube manufacturing (step 1, step 2) and before final completion (step 10).

[0153] Control points: Use water-soluble silicone oil of a specific consistency (2500 centipoise) to assist in demolding and protect the steel wire; use ethanol to clean the steel wire, mandrel, and equipment; finally, purify through a standardized process of "degreasing - ethanol rinsing - pure water rinsing - air drying".

[0154] Objective: To ensure that the inside of the hose meets aerospace-grade cleanliness standards, such as "no excess metal and non-metal particles ≤50μm", through dual protection at both the source and end.

[0155] Active long-lasting rust prevention design

[0156] Design point: Introduce passivation treatment (step 8) as a key step after the hose is formed and before the connector is installed.

[0157] Control point: Passivate the metal wire skeleton inside the pipe body to form a dense oxide film on its surface, thereby improving its anti-corrosion performance.

[0158] Objective: To transform passive protection into active protection, significantly improve the corrosion resistance of steel wire in harsh environments such as humidity and salt spray, ensure the long-term storage safety and service life of hoses, and prevent rust products from contaminating fuel.

[0159] Reliability sealing design based on physical principles

[0160] Design highlights: Subverting the traditional horizontal operation, adopting a process of vertical pipe and vertical placement (step 9).

[0161] Control point: Throughout the entire process of pipe connection and colloid curing, strictly maintain the vertical position of the pipe body.

[0162] Objective: To utilize gravity to allow the sealing colloid inside the joint to distribute naturally and evenly and flow into the joint, fundamentally avoiding colloid deviation, damage, or overflow, thereby eliminating the risk of leakage caused by uneven sealing and achieving an absolutely reliable seal.

[0163] Function-oriented inner contact layer material selection

[0164] Design point: It is explicitly specified that the contact structure layer (step 6) must be made of PTFE (polytetrafluoroethylene) film.

[0165] Control points: Utilizing PTFE's inherent extremely low coefficient of friction, chemical inertness, non-stick properties, and low-temperature resistance.

[0166] Objective: To ensure that the inner wall of the pipe is smooth, does not adhere to contaminants, does not react with fuel, and is easy to clean, which is the material basis for achieving high cleanliness and chemical compatibility.

[0167] Closed-loop quality verification system

[0168] Design point: Set up endoscopic inspection after key processes (step 7, step 10).

[0169] Control points: Visual inspections of the inside of the pipe are conducted twice, once after unloading and once after final cleaning.

[0170] Objective: To form a closed loop of "manufacturing-inspection" to ensure that every hose is qualified before flowing into the next process, thereby achieving process quality control rather than relying solely on final inspection.

[0171] II. Novelty of this application:

[0172] This application solves a long-standing technical problem: For the first time, it systematically addresses the three core deficiencies of general composite hoses in aerospace fuel refueling scenarios: cleanliness, rust prevention, and sealing reliability.

[0173] This application combines "water-soluble silicone oil demolding" with "final cleaning" and links "vertical direct pipe" with design and control points such as "aerospace sealing requirements". The combination of these steps produces a synergistic effect, bringing about a qualitative leap in overall performance and achieving significant technical results: the final hose not only meets the mechanical properties, but also meets the requirements for aerospace fuel refueling hoses in terms of cleanliness, durability and sealing reliability.

[0174] Beneficial effects of this application

[0175] Enhancing cleanliness: Through pre-pipe cleaning of the mandrel and equipment, ethanol cleaning of the steel wire, and a final cleaning process for the finished pipe (including degreasing, ethanol rinsing, pure water rinsing, and air drying), oil, particulate matter, and fibers are thoroughly eliminated from both the source and the final state. Combined with endoscopic inspection after pipe removal, a closed-loop quality inspection system is formed, ensuring that the hose interior meets stringent requirements such as "non-metallic particles ≤50μm, no metallic residue, and no fibrous material ≥2mm in length." This meets the requirements for aerospace fuel refueling hoses and can, to a certain extent, reduce the risk of spacecraft system failures due to pipe contamination.

[0176] Significantly improved hose durability and corrosion resistance: A passivation treatment step was introduced for the inside of the hose. This step forms a dense oxide film on the surface of the steel wire skeleton, greatly enhancing its resistance to environmental corrosion. This allows the composite hose of this application to maintain the integrity of the internal steel wires for a long time, even when stored and used in harsh environments such as humidity and salt spray, preventing rust products from contaminating fuel and ensuring the service life and long-term reliability of the hose.

[0177] This ensures absolutely reliable joint sealing: A unique installation process utilizes a vertically aligned pipe, maintaining its vertical position during installation and continuing this vertical orientation after crimping. Gravity allows the sealing adhesive inside the joint to flow naturally and evenly, maintaining a stable distribution. This effectively avoids the adhesive deviation, defects, or overflows that can occur with traditional horizontal pipe connections. This improvement results in uniform sealing pressure in all directions, significantly reducing the risk of leakage under pressure fluctuations and mechanical vibrations, providing crucial protection for the safe refueling of flammable and explosive aerospace fuels.

[0178] This application presents a synergistic technical solution: multiple steps constitute an organic whole. For example, coating with water-soluble silicone oil and pre-wrapping with braided fabric not only assists in demolding and protects the steel wires but also lays the foundation for subsequent cleaning; the final cleaning removes the silicone oil while completing the final purification. These steps are interconnected and work synergistically to jointly construct a complete technical system capable of stably producing composite hoses that meet the requirements of extreme aerospace operating conditions.

[0179] In summary, the beneficial effects of this application are comprehensive and multi-layered:

[0180] In terms of safety: the reliable sealing design and clean internal environment reduce the risk of space launch accidents caused by leaks and contamination.

[0181] In terms of performance: the hose has both mechanical properties suitable for aerospace fuel refueling scenarios and passivation and rust prevention properties, making its performance comprehensive and balanced.

[0182] Regarding quality and reliability: Through endoscopic inspection and standardized cleaning processes, a repeatable and verifiable quality assurance system has been established to ensure product consistency and high reliability.

[0183] In terms of economics: Although the initial process is more complicated, it greatly reduces the risk and loss of system failure due to hose contamination or leakage, and improves the cost-effectiveness of the entire life cycle.

[0184] It should be noted that:

[0185] In this article, the inner wall of the tube specifically refers to the inner area of ​​the inner steel wire and the contact structure layer.

[0186] In this application, the steel wire is made of 316L or other low-temperature resistant metal material that has undergone special treatment.

[0187] The description of radial outward pretension in this article is as follows: The quantitative index of radial outward pretension is usually expressed as a percentage of strain. For example, "radial outward pretension greater than 15%" means that the material has stored elastic potential energy equivalent to 15% of its yield strength in the initial state. For 316L stainless steel (yield strength ≥ 205 MPa), this pretension can achieve an equivalent radial pressure of 30-35 MPa.

[0188] In this article, “~” is used to represent the range of values, and the range of values ​​represented by this expression includes two endpoint values.

[0189] The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments under the concept of this application, and are not intended to limit them; those skilled in the art can make adaptive adjustments within the concept and protection scope of this application.

[0190] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for preparing a composite flexible tube, characterized in that, Includes the following steps: S1: Clean the mandrel and tube-making equipment with ethanol and cloth, coat the mandrel with water-soluble silicone oil, and then wrap it with a layer of ultra-high molecular weight polyethylene woven cloth. S2: Clean the inner steel wire by wrapping it with a cloth soaked in ethanol, and then wind the inner steel wire around the mandrel at equal intervals with the first pitch. After locking and constraining, it provides outward elastic pretension. S3: The first thin film material is wound around the inner steel wire at a first angle to form a contact structure layer based on a preset width and a specified overlap rate; S4: The woven fabric is wound around the contact structure layer at a second angle to form a tensile structure layer based on a preset width and a specified overlap ratio; S5: The second film material is wound around the tensile structural layer at a third angle, and after being wound to an even number of layers, it overlaps to form a sealed structural layer; S6: The outer steel wire is wound around the sealing structure layer at equal intervals with the second pitch, and is staggered with the inner steel wire to provide inward plastic constraint force, thus obtaining the tube body of the composite hose; S7: Remove the tube from the mandrel and perform endoscopic inspection. After passing the inspection, clean the inside of the tube to remove water-soluble silicone oil. S8: Passivation treatment is performed on the inside of the tube body; S9: Place the pipe body vertically, install the connector to both ends of the pipe body, keep the pipe body vertical during installation, and keep it vertical after clamping; S10: Perform a final cleaning of the hose used for installing the connector to ensure it meets the predetermined standards; In step S1, the mandrel and tube-making equipment are cleaned with ethanol and cotton cloth, water-soluble silicone oil is coated on the mandrel, and then a layer of ultra-high molecular weight polyethylene woven fabric is wrapped around it; wherein the consistency of the water-soluble silicone oil is 2500 centipoise. In step S2, the inner steel wire is cleaned by wrapping it with a lint-free cloth soaked in ethanol; In step S3, the first film material is a PTFE film material; In step S4, by setting a second angle greater than 40° and a preset width and specified overlap rate, the woven fabric is wound on the mandrel to form a tensile structural layer, so that the tensile structural layer has the same cross-sectional size at any length of the tube, and the starting position of the even-numbered layers is half of the overlap rate. In step S5, by setting a third angle greater than 40° and a preset width and specified overlap rate, the film material is wound and formed on the mandrel to form a sealing structure layer, so that the sealing structure layer has the same cross-sectional size at any length of the tube, and the starting position of the even-numbered layers is half of the overlap rate. In step S8, the tube body is immersed in a passivation soaking solution for passivation treatment; In step S10, the final cleaning process includes degreasing, ethanol rinsing, pure water rinsing, air drying, and endoscopic examination; the predetermined standards include: The diameter of non-metallic particles in the inner wall of the tube is ≤50μm; No excess metal objects are allowed on the inner wall of the tube. No material should be missing or damaged in the inner wall of the pipe where it comes into contact with the transmission medium. No fibrous material with a length of ≥2mm is allowed in the inner wall of the tube; Oil or rust are not allowed on the inner wall of the pipe.

2. The preparation method according to claim 1, characterized in that, In step S2, the inner steel wire has a diameter of 2 mm to 6 mm, a first pitch of 12 mm to 24 mm, a tensile strength of 900 MPa to 950 MPa, and a radial outward pretension of more than 15% after locking and constraint.

3. The preparation method according to claim 1, characterized in that, In step S4, the woven fabric is made of aramid or ultra-high molecular weight polyethylene, and the second angle is greater than 40°; In step S5, the second film material is polyimide or ultra-high molecular weight polyethylene, and the third angle is greater than 40°.

4. The preparation method according to claim 1, characterized in that, The tensile structural layer is wound at a large angle with a second angle greater than 40° only when the pipe diameter is DN100 or above. All sealing structure layers are wound at a large angle with a third angle greater than 40°.

5. The preparation method according to claim 1, characterized in that, In step S6, the outer steel wire has a diameter of 2mm to 6mm and a second pitch of 12mm to 24mm.

6. A composite hose for aerospace fuel refueling, characterized in that, The tube is prepared by the method according to any one of claims 1 to 5, and includes a tube body and a connector disposed at the end of the tube body; The tube body includes, from the inside out, an inner steel wire, a contact structure layer, a tensile structure layer, a sealing structure layer, and an outer steel wire; The joint includes an inner spiral tube, an outer steel ring welded to the outside of the inner spiral tube, and a flange disposed at the end of the inner spiral tube; the outer ring of the inner spiral tube is in contact with the contact structure layer and the inner steel wire, the inner ring of the outer steel ring is in contact with the outer surface of the sealing structure layer and the outer steel wire, and a sealing ring is provided inside the outer ring layer.

7. The application of the composite hose as described in claim 6 in an aerospace fuel refueling system, characterized in that, It is used as a composite hose for aerospace fuel refueling.

Images