On-site maintenance method of blade coated iron based on graphene heating film

Abstract

The invention relates to the technical field of helicopter blade repair, in particular to a blade clad iron field maintenance method based on a graphene heating film, which comprises the following steps: preparing non-damage clad iron, and carrying out surface treatment on the inner surface of the clad iron; pre-mounting the clad iron on the surface of the blade for fitting and shaping, and then taking down the clad iron; pasting a glue film on the inner surface of the iron coating, laying glue dipping glass cloth on the surface of the paddle, and installing and fixing the iron coating; a non-porous isolating membrane is laid, the isolating membrane wraps the paddle, the position, wrapped with iron, of the isolating membrane is covered with a graphene electric heating membrane, the outer surface of the graphene electric heating membrane is covered with a shape-preserving cover, and the inner molded surface of the shape-preserving cover is consistent with the front edge of the paddle. According to the method, repeated furnace entering is avoided, local heating is conducted on the fault position, and the heating temperature and the heating rate can meet the product curing requirement. Precise repair can be carried out on the use site, the repair efficiency is improved, compared with original repair modes such as high-efficiency furnace entering and tank entering, the repair cost is reduced, and repair can be provided in real time.

Description

Technical Field

[0001] This invention relates to the field of helicopter rotor blade repair technology, specifically providing a method for on-site repair of rotor blades using a graphene heating film-based iron-clad method. Background Technology The rotor system is a key moving component unique to helicopters and a core technology in helicopter development; its quality and stability directly determine helicopter safety. Composite material rotor blades are extremely important components of the rotor system, consisting of slender, flexible, low-natural-frequency elastic bodies with complex aerodynamic shapes and geometries. These include the main rotor blades and tail rotor blades. They are primarily molded from components such as skin, spars, foam, and metal cladding. After molding, bushings and grounding wires are added during assembly. The overall structure consists of composite material skin bonded to the leading-edge protective cladding. The main rotor blade cladding is mostly a segmented structure, composed of 0.55mm thick nickel-clad iron at the tip, 0.6mm thick No. 2 stainless steel cladding, 0.4mm thick No. 3 stainless steel cladding, and 0.4mm thick No. 4 stainless steel cladding. The tail rotor blade cladding is mostly a monolithic structure, consisting of a 0.5mm thick integral nickel-clad iron leading edge.

[0002] When a helicopter is in operation, the high-speed rotating blades are subjected to complex forces, including lift, centrifugal force, aerodynamic drag, gravity, inertial force, gyroscopic torque, vibration, and fatigue load. The interaction of these forces makes the protective cladding on the leading edge of the blade prone to debonding. In order to ensure the flight safety of the helicopter, it is necessary to repair the debonded blade cladding.

[0003] For the repair of blade cladding debonding, small-area debonding requires adhesive injection, while areas with debonding exceeding a certain size necessitate complete blade peeling and replacement. Existing repair techniques typically utilize metal molds combined with curing ovens and autoclaves. However, these methods are limited by the capacity of the curing equipment, restricting the number of blades that can be repaired at one time. Furthermore, the high curing temperature during the second curing process can easily trigger other malfunctions due to variations in material properties. Bladding debonding of composite material blades is a common problem during blade use. Safe, efficient, and flexible new repair processes are crucial for the repair of composite material blades and for ensuring their long-term effectiveness.

[0004] Graphene is a two-dimensional material composed of a single layer of carbon atoms arranged in a hexagonal honeycomb lattice. It possesses advantages such as excellent electrical conductivity, high mechanical strength, strong flexibility, and excellent thermal conductivity. Due to graphene's unique properties, graphene electric heating films also exhibit high electrothermal conversion efficiency, resulting in advantages such as rapid heating, rapid heat dissipation, and good stability. Furthermore, due to its highly flexible structural design, diverse application scenarios, simple operation, and low energy consumption, using graphene electric heating films for blade cladding repair is a novel, efficient, and safe repair process. It allows for flexible overall and partial repairs of blade cladding, enabling rapid emergency repairs of in-service products and significantly improving the overall repair capability of composite material blades.

[0005] In the traditional composite material blade debonding repair process, the blade needs to be repeatedly heated and cured in the furnace after debonding, which inevitably causes damage to the product. After repair, it is prone to cascading failures, which may lead to the product needing to be repaired again or scrapped. Summary of the Invention

[0006] The purpose of this invention is: This provides a repair solution that causes less damage to the blades, avoiding thermal damage caused by repeated furnace exposure of non-repairable parts. Furthermore, it offers a repair method that provides comparable repair quality while being more convenient, faster, and more efficient, thereby reducing maintenance costs and streamlining the repair process.

[0007] The technical solution of this invention is: A field repair method for blade iron cladding based on graphene heating film is provided, including the following steps: Step 1: Weigh the blades after the paint has been removed and record the weight of the blades after the paint has been removed. This weight will be used for static balancing of the blades after repair. Step 2: Fix the blade to the blade fixture, pry up the edge or corner of the cladding and peel the cladding off the blade; Step 3: Clean and polish the surface of the blade corresponding to the iron sheath after peeling. Step 4: Prepare an undamaged metal plate and grind the inner surface of the metal plate. Step 5: After pre-installing the cladding iron on the blade surface for bonding and shaping, remove the cladding iron. Step 6: Apply adhesive film to the inner surface of the cladding, lay resin-impregnated glass cloth on the blade surface, lay carbon rope, install and fix the cladding; Step 7: Lay out the isolation film, cover the iron sheath with the isolation film, cover the graphene electric heating film with the isolation film, and cover the outer surface of the graphene electric heating film with a conformal cover, the inner surface of the conformal cover being consistent with the leading edge of the blade; vacuum the entire blade, and lead the power cord of the graphene electric heating film out from the opening of the vacuum bag, and seal the opening. Step 8: After the graphene electric heating film is heated to complete the thermal curing, the vacuum bag, molded cover, graphene electric heating film and isolation film are removed to complete the iron-clad replacement and repair.

[0008] Furthermore, in step 6, dry glass cloth is first laid on the surface of the blade and then glue is applied to form glue-impregnated glass cloth.

[0009] Furthermore, in step 6, the impregnated glass cloth is a glass cloth prepreg.

[0010] Furthermore, in step 6, the impregnated glass cloth is impregnated with resin at a ratio of 40-45%.

[0011] Furthermore, in step 7, the vacuum pressure is not less than 0.08 MPa.

[0012] Furthermore, in step 8, the curing parameters are: heating rate ≤ 1.5℃ / min, constant temperature 100℃±5℃, constant temperature time 5.0-6.0 hours, and pressure relief and mold opening when the temperature drops below 60℃.

[0013] Furthermore, in step 1, the blades are cleaned with a neutral cleaning agent before paint stripping.

[0014] Furthermore, the conformal cover has a U-shaped cross-section and is made of composite material.

[0015] The advantages of this invention are: This invention avoids repeated furnace loading, allowing for localized heating of the fault location, and the heating temperature and rate can meet the product curing requirements. This invention enables precise on-site repairs, improving maintenance efficiency and reducing maintenance costs compared to traditional high-efficiency furnace or canister loading repair methods, while providing real-time maintenance. Attached Figure Description

[0016] Figure 1 A schematic diagram of the composite material main blade; Figure 2 Schematic diagram of cross-section of the iron-clad blade repair using in-situ curing of graphene electric heating film; Among them: 1-, 2-, 3-, 4-, 5-, 6-. Detailed Implementation

[0017] The disclosed examples will be described more fully with reference to the accompanying drawings, in which some (but not all) of the disclosed examples are shown. In fact, many different examples may be described, and these examples should not be construed as limited to those set forth herein. Rather, these examples are described so that this disclosure will be thorough and complete, and will fully convey the scope of this disclosure to those skilled in the art.

[0018] An example provides a method for on-site maintenance of propeller blades wrapped with iron based on a graphene heating film, including the following steps: Step 1: Weigh the blades after the paint has been removed and record the weight of the blades after the paint has been removed. This weight will be used for static balancing of the blades after repair. Step 2: Fix the blade to the blade fixture, pry up the edge or corner of the cladding and peel the cladding off the blade; Step 3: Clean and polish the surface of the blade corresponding to the iron sheath after peeling. Step 4: Prepare an undamaged metal plate and grind the inner surface of the metal plate. Step 5: After pre-installing the cladding iron on the blade surface for bonding and shaping, remove the cladding iron. Step 6: Apply adhesive film to the inner surface of the cladding, lay resin-impregnated glass cloth on the blade surface, lay carbon rope, install and fix the cladding; Step 7: Lay out the isolation film, cover the iron sheath with the isolation film, cover the graphene electric heating film with the isolation film, and cover the outer surface of the graphene electric heating film with a conformal cover, the inner surface of the conformal cover being consistent with the leading edge of the blade; vacuum the entire blade, and lead the power cord of the graphene electric heating film out from the opening of the vacuum bag, and seal the opening. Step 8: After the graphene electric heating film is heated to complete the thermal curing, the vacuum bag, molded cover, graphene electric heating film and isolation film are removed to complete the iron-clad replacement and repair.

[0019] In step 6, dry glass cloth is first laid on the surface of the blade and then glue is applied to form glue-impregnated glass cloth.

[0020] In step 6, the impregnated glass cloth is impregnated with resin at a ratio of 40-45%.

[0021] In step 7, the vacuum pressure shall not be less than 0.08 MPa.

[0022] In step 8, the curing parameters are: heating rate ≤ 1.5℃ / min, constant temperature 100℃±5℃, constant temperature time 5.0-6.0 hours, and pressure relief and mold opening when the temperature drops below 60℃.

[0023] In step 1, the blades are cleaned with a neutral cleaning agent before the paint is removed.

[0024] The conformal cover has a U-shaped cross-section and is made of composite material.

[0025] Descriptions of various advantageous arrangements have been shown for illustrative and descriptive purposes, but such descriptions are not intended to be exclusive or limited to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. Furthermore, different advantageous examples may describe different advantages compared to other advantageous examples. One or more examples have been selected and described in order to best illustrate the principles and practical application of the examples, and to enable those skilled in the art to understand that this disclosure contains various examples with various modifications suitable for the particular intended use.

Claims

1. A method for on-site maintenance of propeller blades wrapped with iron based on graphene heating film, characterized in that, Includes the following steps: Step 1: Weigh the blades after the paint has been removed and record the weight of the blades after the paint has been removed. This weight will be used for static balancing of the blades after repair. Step 2: Fix the blade to the blade fixture, pry up the edge or corner of the cladding and peel the cladding off the blade; Step 3: Clean and polish the surface of the blade corresponding to the iron sheath after peeling. Step 4: Prepare an undamaged metal plate and grind the inner surface of the metal plate. Step 5: After pre-installing the cladding iron on the blade surface for bonding and shaping, remove the cladding iron. Step 6: Apply adhesive film to the inner surface of the cladding, lay resin-impregnated glass cloth on the blade surface, lay carbon rope, install and fix the cladding; Step 7: Lay out the isolation film, cover the iron sheath with the isolation film, cover the graphene electric heating film with the isolation film, and cover the outer surface of the graphene electric heating film with a conformal cover, the inner surface of the conformal cover being consistent with the leading edge of the blade; vacuum the entire blade, and lead the power cord of the graphene electric heating film out from the opening of the vacuum bag, and seal the opening. Step 8: After the graphene electric heating film is heated to complete the thermal curing, the vacuum bag, molded cover, graphene electric heating film and isolation film are removed to complete the iron-clad replacement and repair.

2. The on-site maintenance method for propeller blades with iron coating based on graphene heating film according to claim 1, characterized in that: In step 6, dry glass cloth is first laid on the surface of the blade and then glue is applied to form glue-impregnated glass cloth.

3. The on-site maintenance method for propeller blades with iron coating based on graphene heating film according to claim 1, characterized in that: In step 6, the impregnated glass cloth is a glass cloth prepreg.

4. The on-site maintenance method for propeller blades with iron coating based on graphene heating film according to claim 1, characterized in that: In step 6, the impregnated glass cloth is impregnated with resin at a ratio of 40-45%.

5. The on-site maintenance method for propeller blades with iron coating based on graphene heating film according to claim 1, characterized in that: In step 7, the vacuum pressure shall not be less than 0.08 MPa.

6. The on-site maintenance method for propeller blades with iron coating based on graphene heating film according to claim 1, characterized in that: In step 8, the curing parameters are: heating rate ≤ 1.5℃ / min, constant temperature 100℃±5℃, constant temperature time 5.0-6.0 hours, and pressure relief and mold opening when the temperature drops below 60℃.

7. The on-site maintenance method for propeller blades with iron coating based on graphene heating film according to claim 1, characterized in that: In step 1, the blades are cleaned with a neutral cleaning agent before the paint is removed.

8. The on-site maintenance method for propeller blades with iron coating based on graphene heating film according to claim 1, characterized in that: The conformal cover has a U-shaped cross-section and is made of composite material.

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