In-situ heating and pressurizing device and method for forming helicopter blade

Abstract

An in-situ heating and pressurizing device and method for forming a helicopter blade, which belong to the technical field of graphene-thin-film electric heating and are used for forming a hollow spar (1-3) blade. The device comprises an in-situ electric heating thin film, a silicone rubber pressurizing air pouch (2-2), an upper forming mold and a lower forming mold, wherein the in-situ electric heating thin film is arranged on the surface of the silicone rubber pressurizing air pouch (2-2) to form an in-situ heating and pressurizing assembly, and a hollow spar (1-3) blade to be formed or repaired is arranged between the upper forming mold and the lower forming mold; and the in-situ heating and pressurizing assembly is arranged on the outer surface of said hollow spar (1-3) blade, or is arranged on the inner surface of the hollow spar (1-3) blade. By means of the device and method, a local area of a helicopter blade member can be heated and pressurized according to requirements, and there is no need to make the whole blade enter a heating apparatus, such that energy consumption is reduced, and other parts of the blade can also be prevented from structural damage and performance degradation caused by heating. The device and method have high flexibility, and are suitable for scenarios such as local maintenance and forming of blades.

Description

In-situ heating and pressurizing helicopter blade forming device and method Technical Field

[0001] The invention belongs to the technical field of graphene film electric heating, and relates to an in-situ heating and pressurizing helicopter blade forming device and method. Background Art

[0002] Helicopter blades are one of the most critical components in a helicopter rotor system, and the spar is the foundation of their manufacturing. Helicopter blades are directly connected to the rotor hub via a mechanical structure on the spar. The spar carries the blade's centrifugal loads and exhibits a certain degree of torsional, flapping, and shimmy stiffness. Wing spars are generally constructed of metal or composite materials. Metal structures are isotropic and require complex molding processes, while composite structures allow for specific design optimization of fiber orientation and thickness to meet specific mechanical performance requirements. Furthermore, at the same weight, composite wing spars offer higher corrosion resistance and fatigue performance than metal spars. Currently, helicopter blades are typically co-cured using all-composite materials. A glass prepreg spar, foam core, and carbon fiber fabric prepreg are laid out in the cavity of the lower mold of a molding tool for positioning and alignment. The blade is then compacted and cured using heat and pressure in a hot press.

[0003] Another method for manufacturing propeller blades is the co-bonding process. First, the main load-bearing composite components, such as the hollow spar of the blade, are pre-cured and formed. Then, the cured parts are placed in the mold according to the designed position. Adhesive bonding materials, such as adhesive film, are applied between the parts. The adhesive cures and bonds the parts together in a heating device, completing the curing process.

[0004] In summary, regardless of the molding method used for composite helicopter blades, the molding die must be placed inside a large heating device, such as an autoclave. The autoclave, a primary production facility for composite parts, is a large pressure vessel with an integrated heating system. A typical autoclave molding system consists of a tank, cooling system, vacuum system, pressure system, heating system, sealing system, and control system. The autoclave molding process utilizes the pressure generated by high-temperature, compressed gas within the autoclave to heat and pressurize the composite blank, completing the curing process. Autoclave molding technology can produce composite parts of varying shapes, and due to this advantage, autoclaves are widely used in the production of aerospace parts. However, due to the strict requirements for size, temperature, and pressure, the manufacturing cost of the autoclave is quite high. Furthermore, auxiliary equipment, such as air or ammonia piping, cooling ducts, heating furnaces, and monitoring equipment, also adds to the cost. The total cost of a large industrial autoclave and its auxiliary equipment is approximately 1 million yuan. The high manufacturing costs associated with the autoclave molding process have drawn significant attention, particularly due to its high energy consumption, large gas consumption, large floor space requirements, and long curing cycles. Another drawback of the autoclave's large size and heating and pressurizing method is its slow temperature and pressure response, coupled with poor temperature control accuracy. Furthermore, due to the increasing complexity and size of composite components used in modern large aircraft, traditional autoclave molding technology can no longer meet the demands of practical manufacturing applications. Therefore, there is an urgent need to develop a novel non-autoclave molding process that achieves uniform heating and pressurization, is energy-efficient, environmentally friendly, safe, reliable, and easy to operate.

[0005] Graphene, a novel material consisting of only a single layer of carbon atoms (0.335 nm) thick, is the world's thinnest two-dimensional material. Graphene boasts stable, ultra-high mechanical properties, exceptional electrical and thermal conductivity, and a large specific surface area. The electron mobility of single-layer graphene is 200,000 cm2V-1s-1, its Young's modulus and tensile strength are as high as 1TPa and 130GPa, respectively, and its specific surface area is as high as 2600m2g-1. Pure, defect-free single-layer graphene has a thermal conductivity of 5300W / m·K, making it the highest thermal conductivity of any carbon material to date, despite its density of only 2.2gcm-3. It holds significant potential for application in materials science, micro-nanofabrication, aviation, and aerospace, and is considered a revolutionary material of the future.

[0006] Silicone rubber is a commonly used polymer material with stable chemical properties and high mechanical strength. As an auxiliary material for composite molding, silicone rubber offers excellent processability, strong plasticity, excellent heat resistance, and reusability. The stable and easy-to-use pressurization process of silicone rubber can improve part quality. A series of studies have been conducted domestically and internationally on the design and pressure control of silicone rubber pressurization processes. Silicone rubber is widely used as an important auxiliary pressurization material in traditional autoclave and compression molding processes.

[0007] Summary of the Invention

[0008] Purpose of the invention: The present invention proposes an in-situ heating and pressurizing helicopter blade forming device and method. According to the characteristics of graphene's good electrical and thermal conductivity, a graphene heating film is used as the basic electric heating element, which is tightly attached to the component to be heated, and then a silicone rubber airbag is tightly attached to the graphene film to provide pressure. The purpose is to develop a low-cost, in-situ heating, pressurization, simple process and non-autoclave blade forming process method.

[0009] Technical solution of the present invention: To achieve the above-mentioned purpose, according to the first aspect of the present invention, an in-situ heating and pressurizing helicopter blade forming device is proposed for forming hollow spar blades; the device comprises an in-situ electric heating film, a silicone rubber pressurized airbag, an upper forming die, and a lower forming die;

[0010] The in-situ electric heating film is arranged on the surface of the silicone rubber pressurized airbag to form an in-situ heating and pressurizing component, between the upper forming mold and the lower forming mold of the hollow wing spar blade to be formed or repaired; the in-situ heating and pressurizing component is arranged on the outer surface of the hollow wing spar blade to be formed or repaired, or on the inner surface of the hollow wing spar blade.

[0011] In a possible embodiment, the in-situ electric heating film and the silicone rubber pressurized airbag are physically connected and adhered to each other.

[0012] In a possible embodiment, the in-situ electric heating film is embedded in the inner surface of the silicone rubber pressurized airbag, forming an integrated heating and pressurizing in-situ heating and pressurizing component with the silicone rubber pressurized airbag.

[0013] In a possible embodiment, the in-situ electric heating film is a graphene electric heating film.

[0014] In a possible embodiment, the external insulating material of the graphene electric heating film is made of high-temperature resistant insulating materials such as polyethylene terephthalate (PET) plastic, nylon, thermoplastic polyurethane (TPU), polyimide, or silicone rubber.

[0015] In a possible embodiment, the temperature uniformity of the graphene electric heating film is ±5°C.

[0016] According to a second aspect of the present invention, a method for forming a helicopter blade by in-situ heating and pressurizing is provided, which uses the above-mentioned in-situ heating and pressurizing helicopter blade forming device, comprising the following steps:

[0017] Step 1: Grind and clean the leading edge of the solidified hollow spar blade, apply adhesive film or liquid glue evenly on the leading edge of the blade, and then install the iron clad on the leading edge of the blade;

[0018] Step 2: placing the in-situ heating and pressurizing assembly close to the outer side of the clad iron in the upper forming die and the lower forming die;

[0019] Step 3: Inflate the silicone airbag to a pressure of 0.1 MPa, and power on the in-situ electric heating film of the in-situ heating and pressurizing assembly for heating; after heating is completed, cut off the power supply of the in-situ electric heating film, wait for the temperature to drop, release the gas in the silicone rubber airbag, open the upper molding die and the lower molding die, and take out the iron-clad and glued paddle.

[0020] According to a third aspect of the present invention, a method for forming a helicopter blade by in-situ heating and pressurizing is provided, which uses the above-mentioned in-situ heating and pressurizing helicopter blade forming device, comprising the following steps:

[0021] Step 1: placing the hollow spar blade to be formed between the upper forming die and the lower forming die;

[0022] Step 2: Install the in-situ heating and pressurizing assembly close to the inner surface of the hollow spar blade, with the silicone rubber pressurized airbag and the in-situ electric heating film from the inside out.

[0023] Step 3: Inflate the silicone airbag to a pressure of 20 MPa, and power on the in-situ electric heating film of the in-situ heating and pressurizing component for heating; after heating is completed, cut off the power supply of the graphene electric heating film, wait for the temperature to drop, release the gas in the silicone rubber airbag, and take out the formed hollow wing beam.

[0024] According to a fourth aspect of the present invention, a method for repairing a helicopter blade by in-situ heating and pressurizing is provided, which uses the above-mentioned in-situ heating and pressurizing helicopter blade forming device, comprising the following steps:

[0025] Step 1: Clean the damaged part of the hollow spar blade to be repaired, lay the composite material layer and the isolation film after cleaning;

[0026] Step 2: placing the in-situ heating and pressurizing assembly in close contact with the outer side of the damaged portion of the leading edge of the blade in the upper molding die and the lower molding die;

[0027] Step 3: Inflate the silicone airbag to a pressure of 5 MPa and power on the graphene electric heating film for heating. After heating is completed, cut off the power supply of the graphene electric heating film, wait for the temperature to drop, release the gas in the silicone rubber airbag, and remove the repaired blade.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The present invention is a process for heating and pressurizing graphene film to form helicopter blades. Compared with traditional autoclave molding technology, it is a new blade molding solution;

[0030] (2) The graphene electric heating film process adopted by the present invention belongs to "surface heating", and the heated helicopter blade components can be heated evenly, reducing the occurrence of defects;

[0031] (3) The heating process adopted by the present invention directly heats the helicopter blade components, without the need for heating the equipment itself and the air medium inside it, and thus has high energy utilization efficiency;

[0032] (4) The present invention can heat and pressurize local areas of helicopter blade components as needed, without requiring the entire blade to enter the heating device, thus reducing energy consumption and preventing other parts from being heated, causing tissue damage and performance degradation. It has high flexibility and is suitable for scenarios such as local repair and molding of blades.

[0033] (5) For the hollow spar forming of helicopter blades, the present invention can achieve heating and pressurizing from the inside of the cavity to the outside, which is conducive to the smooth removal of air during the composite material forming process and reduces the defects of the hollow spar of the blade after forming. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram of a hollow spar blade;

[0035] Of which: 1 main blade

[0036] 1-1 blade skin

[0037] 1-2 blades iron-clad

[0038] 1-3 hollow wing spars

[0039] Figure 2 Schematic diagram of a cross section of the blade in-situ heating and pressurizing equipment

[0040] Among them: 2 graphene membrane in-situ heating and pressurization for blade wrapping and gluing molding

[0041] 2-1 Graphene electric heating film

[0042] 2-2 Silicone rubber pressurized airbag

[0043] 2-3 tooling

[0044] Figure 3 Schematic diagram of the hollow spar of the blade

[0045] Among them: 3-1 A section of the hollow spar of the blade

[0046] Figure 4 Schematic diagram of the hollow spar forming process of the blade

[0047] Among them: 4 graphene membranes are heated and pressed in situ for forming the hollow spar of the blade

[0048] 4-1 Silicone rubber airbag

[0049] 4-2 Graphene electric heating film

[0050] 4-3 Fixed tooling

[0051] Figure 5 Schematic diagram of damaged blade to be repaired

[0052] Among them: 5-1 blade damage

[0053] Figure 6 Schematic diagram of blade repair and curing molding

[0054] Among them: 6-1 composite material layer; 6-2 graphene electric heating film; 6-3 silicone rubber airbag; 6-4 tooling. DETAILED DESCRIPTION

[0055] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention rather than limiting the patent claims of the present invention.

[0056] According to a first aspect of the present invention, an in-situ heating and pressurizing helicopter blade forming device is provided for forming hollow spar blades; the device comprises an in-situ electric heating film, a silicone rubber pressurized airbag, an upper forming die, and a lower forming die;

[0057] The in-situ electric heating film is arranged on the surface of the silicone rubber pressurized airbag to form an in-situ heating and pressurizing component, between the upper forming mold and the lower forming mold of the hollow wing spar blade to be formed or repaired; the in-situ heating and pressurizing component is arranged on the outer surface of the hollow wing spar blade to be formed or repaired, or on the inner surface of the hollow wing spar blade.

[0058] In a possible embodiment, the in-situ electric heating film and the silicone rubber pressurized airbag are physically connected and adhered to each other.

[0059] In a possible embodiment, the in-situ electric heating film is embedded in the inner surface of the silicone rubber pressurized airbag, forming an integrated heating and pressurizing in-situ heating and pressurizing component with the silicone rubber pressurized airbag.

[0060] In a possible embodiment, the in-situ electric heating film is a graphene electric heating film.

[0061] In a possible embodiment, the external insulating material of the graphene electric heating film is made of high-temperature resistant insulating materials such as polyethylene terephthalate (PET) plastic, nylon, thermoplastic polyurethane (TPU), polyimide, or silicone rubber.

[0062] In a possible embodiment, the temperature uniformity of the graphene electric heating film is ±5°C.

[0063] According to a second aspect of the present invention, a method for forming a helicopter blade by in-situ heating and pressurizing is provided, which uses the above-mentioned in-situ heating and pressurizing helicopter blade forming device, comprising the following steps:

[0064] Step 1: Grind and clean the leading edge of the solidified hollow spar blade, apply adhesive film or liquid glue evenly on the leading edge of the blade, and then install the iron clad on the leading edge of the blade;

[0065] Step 2: placing the in-situ heating and pressurizing assembly close to the outer side of the clad iron in the upper forming die and the lower forming die;

[0066] Step 3: Inflate the silicone airbag to a pressure of 0.1 MPa, and power on the in-situ electric heating film of the in-situ heating and pressurizing assembly for heating; after heating is completed, cut off the power supply of the in-situ electric heating film, wait for the temperature to drop, release the gas in the silicone rubber airbag, open the upper molding die and the lower molding die, and take out the iron-clad and glued paddle.

[0067] Example 1:

[0068] Blade iron clad bonding molding:

[0069] (1) As shown in Figure 1, the blade iron is located at the leading edge of the blade. After the solidified blade leading edge is polished and cleaned, a film or liquid glue is evenly applied to the leading edge of the blade, and then the iron is installed on the leading edge of the blade.

[0070] (2) As shown in Figure 2, the graphene electric heating film is tightly attached to the leading edge of the blade and iron is wrapped around it. The pressurized silicone airbag is tightly attached to the graphene electric heating film, and the outermost layer is a fixed tooling.

[0071] (3) First, inflate the silicone airbag to a pressure of 0.1 MPa, and then heat the graphene electric heating film with a heating rate of 5°C / min to 70°C. Keep warm for 2 hours, then cut off the power supply of the graphene electric heating film. When the temperature drops below 40°C, release the gas in the silicone rubber airbag and take out the iron-coated and bonded blade.

[0072] According to a third aspect of the present invention, a method for forming a helicopter blade by in-situ heating and pressurizing is provided, which uses the above-mentioned in-situ heating and pressurizing helicopter blade forming device, comprising the following steps:

[0073] Step 1: placing the hollow spar blade to be formed between the upper forming die and the lower forming die;

[0074] Step 2: Install the in-situ heating and pressurizing assembly close to the inner surface of the hollow spar blade, with the silicone rubber pressurized airbag and the in-situ electric heating film from the inside out.

[0075] Step 3: Inflate the silicone airbag to a pressure of 20 MPa, and power on the in-situ electric heating film of the in-situ heating and pressurizing component for heating; after heating is completed, cut off the power supply of the graphene electric heating film, wait for the temperature to drop, release the gas in the silicone rubber airbag, and take out the formed hollow wing beam.

[0076] Example 2:

[0077] Hollow spar curing molding of blades:

[0078] (1) Figure 3 is a schematic diagram of the hollow spar of the blade. For the molding of the hollow spar composite material, as shown in Figure 4, from the inside of the hollow to the outside, there are pressurized silicone airbags, graphene membranes, composite materials, and the outermost layer is the fixed tooling.

[0079] (2) First, inflate the silicone airbag to a pressure of 20 MPa, and then heat the graphene electric heating film with a heating rate of 5°C / min to 130°C. Keep the temperature for 4 hours, then cut off the power supply of the graphene electric heating film. When the temperature drops below 40°C, release the gas in the silicone rubber airbag and take out the formed hollow wing beam.

[0080] According to a fourth aspect of the present invention, a method for repairing a helicopter blade by in-situ heating and pressurizing is provided, which uses the above-mentioned in-situ heating and pressurizing helicopter blade forming device, comprising the following steps:

[0081] Step 1: Clean the damaged part of the hollow spar blade to be repaired, lay the composite material layer and the isolation film after cleaning;

[0082] Step 2: placing the in-situ heating and pressurizing assembly in close contact with the outer side of the damaged portion of the leading edge of the blade in the upper molding die and the lower molding die;

[0083] Step 3: Inflate the silicone airbag to a pressure of 5 MPa and power on the graphene electric heating film for heating. After heating is completed, cut off the power supply of the graphene electric heating film, wait for the temperature to drop, release the gas in the silicone rubber airbag, and remove the repaired blade.

[0084] Example 3:

[0085] Blade damage repair molding:

[0086] (1) As shown in FIG5 , the blade is partially damaged during use or transportation. The damaged portion is cleaned, and after cleaning, the composite material layer is laid and the isolation film is laid.

[0087] (2) As shown in FIG6 , the graphene electric heating film is placed close to the damaged portion of the leading edge of the blade, the pressurized silicone airbag is placed close to the graphene electric heating film, and the outermost layer is a fixed tooling.

[0088] (3) First, inflate the silicone airbag to a pressure of 5 MPa, and then heat the graphene electric heating film with a heating rate of 5 °C / min to 130 °C. Keep the temperature for 5 hours, then cut off the power supply of the graphene electric heating film. When the temperature drops below 40 °C, release the gas in the silicone rubber airbag and take out the repaired blade.

Claims

1. An in-situ heating and pressurizing helicopter blade forming device, characterized in that, For the forming of hollow spar blades; including in-situ electric heating film, silicone rubber pressurized airbag, upper forming die, and lower forming die; The in-situ electric heating film is disposed on the surface of the silicone rubber pressurized airbag to form an in-situ heating and pressurizing assembly, between the upper forming die and the lower forming die of the hollow spar blade to be formed or repaired; the in-situ heating and pressurizing assembly is disposed on the outer surface of the hollow spar blade to be formed or repaired, or on the inner surface of the hollow spar blade.

2. The in-situ heating and pressurizing helicopter blade forming device according to claim 1, wherein The in-situ electric heating film and the silicone rubber pressurized airbag are physically connected and adhered to each other.

3. An in-situ heating and pressurizing helicopter blade forming device according to claim 1, characterized in that, The in-situ electric heating film is embedded in the inner surface of the silicone rubber pressurized airbag, forming an in-situ heating and pressurizing assembly that heats and pressurizes integrally with the silicone rubber pressurized airbag.

4. The in-situ heating and pressurizing helicopter blade forming device according to claim 1, characterized in that, The in-situ electric heating film uses a graphene electric heating film.

5. An in-situ heating and pressurizing helicopter blade forming device according to claim 4, characterized in that, The external insulating material of the graphene electric heating film is a high-temperature resistant insulating material.

6. An in-situ heating and pressurizing helicopter blade forming device according to claim 5, characterized in that, The high-temperature resistant insulating material uses polyethylene terephthalate plastic or nylon or thermoplastic polyurethane or polyimide or silicone rubber.

7. An in-situ heating and pressurizing helicopter blade forming device according to any one of claims 4 or 5, characterized in that, The temperature uniformity of the graphene electric heating film is ±5°C.

8. An in-situ heating and pressurizing method for forming a helicopter blade, characterized in that, Using an in-situ heating and pressurizing helicopter blade forming device according to any one of claims 1-7, including the following steps: Step 1: Grind and clean the leading edge of the cured and formed hollow spar blade, evenly apply a glue film or liquid glue on the leading edge of the blade, and then install the iron wrap on the leading edge of the blade; Step 2: In the upper forming die and the lower forming die, closely attach the in-situ heating and pressurizing assembly to the outside of the iron wrap; Step 3: Inflate the silicone airbag to a pressure of 0.1 MPa, and energize the in-situ electric heating film of the in-situ heating and pressurizing assembly for heating; After heating is completed, cut off the power supply of the in-situ electric heating film. Wait for the temperature to drop, release the gas in the silicone rubber airbag, open the upper forming die and the lower forming die, and take out the blade with the iron wrap adhesively formed.

9. An in-situ heating and pressurizing method for helicopter blade forming, using an in-situ heating and pressurizing helicopter blade forming device according to any one of claims 1-7, characterized in that, Including the following steps: Step 1: Place the hollow spar blade to be formed between the upper forming die and the lower forming die; Step 2: Closely attach the in-situ heating and pressurizing assembly to the inner surface of the hollow spar blade, with the silicone rubber pressurized airbag and the in-situ electric heating film from the inside to the outside in sequence; Step 3: Inflate the silicone airbag to a pressure of 20 MPa, and energize the in-situ electric heating film of the in-situ heating and pressurizing assembly for heating; after heating is completed, cut off the power supply of the graphene electric heating film. Wait for the temperature to drop, release the gas in the silicone rubber airbag, and take out the formed hollow spar.

10. A method for repairing a helicopter blade by in-situ heating and pressurization, which uses an in-situ heating and pressurization helicopter blade forming device according to any one of claims 1-7, characterized in that, Including the following steps: Step 1: Clean the damaged part of the hollow spar blade to be repaired. After cleaning, perform composite material layering and lay an isolation film; Step 2: In the upper forming die and the lower forming die, closely attach the in-situ heating and pressurizing assembly to the outside of the damaged part of the leading edge of the blade; Step 3: Inflate the silicone airbag to a pressure of 5 MPa, and energize the graphene electric heating film for heating; after heating is completed, cut off the power supply of the graphene electric heating film. Wait for the temperature to drop, release the gas in the silicone rubber airbag, and take out the repaired and formed blade.

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