RU2436688C1 - Method of producing flexible shock-proof fuel tank - Google Patents

Abstract

FIELD: transport.

SUBSTANCE: invention relates to production of fuel systems, particularly, to production of flexible shock-proof fuel tank. Proposed method consists in spraying polymer layers on fixture prefilled with gas and made from polymer oil-and-gasoline resistant film by cutting the latter to tank sizes and shape, and connecting pattern ends to make fuel fill-and-drain openings. First sprayed layer is an antiadhesion composition based on wax, or fluoroplastic, or silicon, which is then dried in air at 18°C to 30°C for 2-8 h. Second layer is oil-and-gasoline resistant polyurea or polyurethane reinforced in spraying by 10-50 layers of polyaramide fabric and 1-5 layers of kapron fabric. After curing polyurethane or polyurea in air for at least 24 h at 18°C to 30°C, third antiadhesion layer based on wax, or fluoroplastic, or silicon is sprayed and, cured in air for at least 2-8-4 h at 18°C to 30°C. Fourth layer of oil-and-gasoline resistant polyurea or polyurethane with rupture elongation making at least 450% on said third layer. After curing said fourth layer in air for at least 24 h, gas ir removed from fixture.

EFFECT: higher strength, possibility to produce complex shape fuel tanks.

5 cl

Description

The invention relates to fuel tanks, in particular to methods for manufacturing flexible impact-resistant fuel tanks having a complex configuration and made of polymer composite materials, and may find application in the aerospace industry, helicopter engineering, as well as in other areas of technology where fuel tanks are used.

A known method of manufacturing a fuel tank from composite materials, including the formation of the inner composite layers of the tank in the form of two half-blanks on a monolithic mandrel, removing the half-finished products from the mandrel and their installation on the intermediate support ring, forming the outer composite layers of the tank and removing the intermediate support ring (see RU patent No. 2233744, class D22D 22/00, publ. 10.08.2004).

The disadvantages of the known tank include the high cost and complexity, the impossibility of manufacturing tanks of complex non-symmetrical configuration, the need for special equipment and the individuality of mandrels, and in addition, the tank manufactured by this method has insufficiently tight sealing when exposed to shock-compressive and high-speed point loads (shell, fragments) and insufficient useful capacity.

The technical result is a reduction in the complexity and cost of manufacturing the tank, increasing the tightness after breaking through the tank with a high-speed point projectile, obtaining a more developed complex configuration, increasing the useful capacity of the tank, increasing reliability when the fuel tank is hit by a fire during fuel spillage in the event of a fuel tank being destroyed.

The specified technical result is achieved by the fact that the method of manufacturing a fuel tank involves spraying polymer layers onto a tool, pre-filled with gas and made of a polymer oil and petrol resistant film by cutting the film in size and shape of the tank and then connecting the ends of the pattern to each other with the formation of cream filling holes for fuel, while the first is sprayed with a layer of release compound on a wax or fluoroplastic, or silicone base, which is then dried in air at at a temperature of 18 to 30 ° C for 2-8 hours, an oil-petrol-resistant polyurea or polyurethane is sprayed with a second layer and, during the spraying process, reinforce with 10-50 layers of polyaramide fabric and 1-5 layers of nylon fabric, after curing the polyurethane or polyurea in air for at least 24 hours at a temperature of 18 to 30 ° C, a third layer of wax and fluoroplastic or silicone-based release agent is sprayed, which is then dried in air at a temperature of 18 to 30 ° C for 2-8 hours, a fourth layer is sprayed on the third layer from maslobe zostoykoy polyurea or polyurethane having an elongation at break of not less than 450%, which after curing in air for at least 24 hours gas is removed from the tooling.

Spraying the first layer of the release compound on a wax, fluoroplastic, or silicone base is an essential feature, since it is this base that allows you to separate the equipment from a polymer oil-and-oil film and the polyurea (polyurethane) third layer, which is necessary for easy removal of equipment from the tank.

The indicated temperature range at which the release agent is dried in air is an essential feature, since at a temperature below 18 ° C the release agent retains solvent residues, which can negatively affect the sprayed second layer of polyurethane or polyurea, at a temperature above 30 ° C the composition acquires excessive plasticity. For less than two hours, the composition is impractical to dry, since the entire solvent does not have time to evaporate, and drying the composition for more than eight hours is also impractical, since when the temperature range is maintained, the solvent has time to completely evaporate within the indicated time interval.

The choice as the second layer of oil-resistant polyurea or polyurethane makes it possible to obtain a flexible elastic tank and operate it in contact with aviation fuel without changing its chemical composition, which confirms the significance of this feature.

Reinforcing with 10-50 layers of polyaramide fabric and 1-5 layers of nylon fabric allows you to get high impact resistance and resistance to high-speed point loads. When the number of layers of polyaramide fabric is less than 10, the flexible tank has insufficient anti-fragmentation and bulletproof protection, with the number of layers of polyaramide fabric more than 50, the tank has a very high cost and high weight, which does not compensate for high armor resistance.

When the number of layers of nylon fabric is less than one, the flexible tank has insufficient anti-fragmentation and bulletproof protection, with the number of layers of nylon fabric more than 5, the tank has a very high cost and heavy weight, which does not compensate for high armor resistance.

Spraying the third layer from the release compound on a wax, fluoroplastic, or silicone base is an essential feature, since it is this base that allows you to separate the second reinforced layer from oil-resistant polyurea or polyurethane and the fourth layer from oil-resistant polyurea or polyurethane with a relative elongation of at least 450% to break .

The indicated temperature range at which the release agent is dried in air is an essential feature, since at a temperature below 18 ° C the release agent retains solvent residues, which can negatively affect the sprayed second layer of polyurethane or polyurea, at a temperature above 30 ° C the composition acquires excessive plasticity. For less than two hours, the composition is impractical to dry, since the entire solvent does not have time to evaporate, it is impractical to dry the composition for more than eight hours, since when the temperature range is maintained, the solvent completely evaporates in the specified time interval.

The choice as the fourth layer of oil-resistant polyurea or polyurethane with a relative elongation to break of at least 450% allows you to get a flexible elastic layer that can significantly stretch upon impact and not tear, self-tighten when breaking through and operate it, respectively, in contact with aviation fuel without changing it chemical composition, which confirms the significance of this feature.

If the fourth layer is cured in less than 24 hours, the necessary technological polymerization of the components of polyurethane or polyurea with a relative elongation to break of at least 450% will not occur. The maximum cure time is selected based on 100% cure of polyurethane or polyurea in air.

The choice of a polymer film as a tooling material is due to the low cost, ease of manufacturing of volumetric configurations by cutting and gluing, low laboriousness, the ability to obtain shapes, almost any volumetric shapes.

To remove gas from the equipment, the tank can be evacuated with a discharge of 0.05-0.01 MPa. If the tank is evacuated at other values, then an irreversible “folding” of the tank may occur.

Deflated equipment can be removed by pulling the filler hole through the neck, which simplifies the process of removing equipment.

Deflated accessories can be left in the tank. As a rule, the equipment is left when it is impossible to reuse it, for example, when the tank has a large number of internal undercuts, especially since the equipment left does not adversely affect the performance of the tank.

After removing gas from the equipment, the tank can first be washed with gasoline, and then with fuel, which allows you to remove the remnants of the release agent and glue.

The method is as follows.

An example of implementation is considered on the example of a fuel tank for a transport helicopter.

The disadvantages of the known fuel tanks are the significant weight and the inability to use the internal fuselage space between the stringer partitions due to the complexity of the tank design and the lack of appropriate equipment and technology.

A tank made by this method avoids the indicated drawbacks and places it in the helicopter fuselage space, which is free from structures, taking into account the center of gravity of the entire machine, as it is flexible and repeats a complex configuration between partitions, stringers, spars, frames, etc.

First, make the snap. To do this, they cut out an elastic film made of polymeric materials, for example, polyvinyl chloride (PVC), then glue or weld the edges of the pattern according to the desired configuration of the future fuel tank and install a pump nipple with a check valve and an element that forms cream filling holes with necks (fuel filling holes and remove it). After that, the equipment is pumped with any suitable gas, for example air, until the desired configuration and elasticity are obtained using a nipple.

Then the gas-filled equipment is suspended by the neck or nipple, and a spray gun is sprayed onto its surface, including the neck of the fuel injection hole, for example, silicone-based release compound. After application, the composition is dried, for example, 20 hours at a temperature of 18 ° C.

After that, on top of the first layer, including the neck of the fuel injection hole, a second layer, for example, polyurethane, is sprayed and reinforced, for example, with 20 layers of polyaramide fabric and 2 layers of nylon fabric. After that, this layer is cured in air at a temperature of 20 ° C for 25 hours.

Then a third layer is sprayed onto the surface of the second layer, including the neck of the hole for filling fuel, with a spray, for example, a silicone-based release compound. After application, the composition is dried, for example, 20 hours at a temperature of 18 ° C.

After that, on top of the third layer, including the neck of the fuel injection hole, a fourth layer, for example, polyurea, is sprayed with a relative elongation to break of at least 550%. After that, this layer is cured in air at a temperature of 20 ° C for 48 hours.

Then, through the pumping nipple, the gas is removed from the equipment, while the tank on the equipment is evacuated with a discharge of 0.02 MPa. The deflated snap is left in the tank as the inner layer. Then the resulting tank is first washed with gasoline, and then the fuel control and intake devices are installed with the fuel that will be in it during operation. The tank is placed in the body of the aircraft and for its tight installation with a slight crumple is installed in the place of constant location. For its tight installation and alignment, excess gas pressure is supplied to it. The tank finds "its place" and is ready for operation.

Claims (5)

1. A method of manufacturing a fuel tank, comprising spraying polymer layers onto a tool, pre-filled with gas and made of a polymer oil and oil resistant film by cutting the film in size and shape of the tank and then connecting the ends of the pattern to each other with the formation of cream filling holes for fuel, the first is sprayed with a wax-based or fluoroplastic or silicone-based release layer, which is then dried in air at a temperature of 18 to 30 ° C for 2-8 hours, the second layer is n oil-petrol-resistant polyurea or polyurethane is sprayed and reinforced with 10-50 layers of polyaramide fabric and 1-5 layers of nylon fabric during the spraying process; after curing polyurethane or polyurea in air for at least 24 hours at a temperature of 18 to 30 ° C, a third layer of anti-adhesive composition is sprayed on a wax, or fluoroplastic, or silicone base, which is then dried in air at a temperature of 18 to 30 ° C for 2-8 hours, a fourth layer of oil-resistant polyurea or polyurethane with a relative elongation is sprayed onto the third layer HAND at break of not less than 450%, which after curing in air for at least 24 h gas is removed from the tooling. 2. A method of manufacturing a fuel tank according to claim 1, characterized in that in order to remove air from the equipment, the tank is evacuated at a discharge of 0.05-0.01 MPa. 3. A method of manufacturing a fuel tank according to any one of claims 1 and 2, characterized in that the deflated snap is removed by pulling through the neck of the filling hole. 4. A method of manufacturing a fuel tank according to any one of claims 1 and 2, characterized in that the deflated snap is left in the tank. 5. A method of manufacturing a fuel tank according to any one of claims 1 and 2, characterized in that after removing gas from the tool, the tank is first washed with gasoline and then with fuel.