RU2808014C2 - Method for manufacturing curved pipe from composite materials, mandrel and slipway for implementing this method and curved pipe from composite materials - Google Patents

Abstract

FIELD: pipes from composite materials.

SUBSTANCE: group of inventions relates to the production of curved pipes from composite materials. A method for manufacturing a curved pipe from composite materials, a mandrel for forming the pipe shell, a slipway for implementing the method, and a curved pipe from composite materials are described. The method includes laying a sealing layer on a mandrel consisting of a shaft and external bars located on it. Then, spiral layers of binder-impregnated unidirectional reinforcing material of the pipe's load-bearing shell are wound. The external bars of the mandrel are made removable from the shaft with side surfaces or edges tightly adjacent to each other to form an outer surface for winding. After winding the power shell, the external bars, all together as a single whole, with the shell located on them, are removed from the mandrel shaft, the bars are removed from the shell one by one, the ends of the shell are plugged, excess internal pressure is created in it, the ends of the shell are forced into the attachment points of the slipway, the shell is fixed using power rods and/or stops and sent for heat treatment.

EFFECT: increase in the reliability, manufacturability and performance of curved pipes.

16 cl, 11 dwg

Description

The group of inventions relates to the field of mechanical engineering, to a method for manufacturing curved pipes from composite materials, necessary for the implementation of this method, a mandrel and a slipway and curved pipes from composite materials made by the specified method, and can be used to create pipelines for all industries and the national economy: food, chemical, oil and gas, automotive, shipbuilding, aviation, rocket and space industries for the production of pipes from composite pipes of complex, spatially oriented shape.

Pipes made from composite materials are currently used in many fields. But wide distribution, in accordance with their high performance qualities, is hampered, including due to the complexity of manufacturing curved pipes, which is most necessary for limited spaces in production facilities and compartments of various equipment.

The manufacturing process of any structure made of composite materials comes down to laying a reinforcing material based on filaments impregnated with a binder on a form that reproduces the required geometry of the structure, and heat treatment, as a result of which the binder hardens and a monolithic, strong and rigid structure is obtained.

The standard procedure for manufacturing products from composite materials in the form of shells of rotation, including pipes, comes down to:

- creating a shell blank by winding reinforcing material impregnated with a binder onto a straight mandrel using standard winding machines;

- heat treatment until complete polymerization and hardening of the binder;

- removing the cured shell from the mandrel by pulling the mandrel out of the shell, as a rule, on special capstan machines.

In accordance with the specified process, for the manufacture of curved pipes it is necessary:

- creation of a curved mandrel, which is difficult to create and manufacture;

- automated (mechanized) application of reinforcing material to a curved mandrel, which requires the creation and use of special machines;

- removal of the cured pipe from a curved mandrel, which is difficult and possible in a limited number of special cases.

The impossibility of manufacturing a relatively long pipe with several bends (turns) using standard winding equipment leads to the option of a prefabricated structure, which requires the manufacture of individual bends (bends), which, as can be seen from the technical solutions given below, is quite complex in itself.

In addition, any pipe connection, for example, with seals and an external coupling according to patent RU 2154767 C1 IPC F16L 47/06 (2000/01) publ. 08/20/2000 Bulletin. No. 23, or with embedded connecting elements according to patent RU 2338950 C1 MPK F16L 9/12 (2006/01) publ. November 20, 2008 Bulletin. 32, or adhesive with additional winding according to patent RU 2197675 C21 F16L 43/00 publ. 01/27/2003 Bulletin. 3 is a complication of the design, an increase in geometry (in diameter and length), an increase in weight and cost, and a decrease in reliability.

Analogues and prototypes of the manufacturing method

There is a known technical solution for the production of curved pipes, for which a machine for winding curved pipes from composite materials is used according to RF patent No. 2336168, class. В29С 53/56 (2006.01), publ. 10.20.2008, in which a mandrel curved along the circumference is used, and the reinforcing material is wound onto it by rotating coils with reinforcing material around the mandrel.

The limitation of using such a solution and, accordingly, the disadvantage is the possibility of manufacturing only a pipe of constant curvature and, therefore, only short parts of the pipe - elbows, bends. Otherwise, the cured pipe cannot be removed from the mandrel, for example, from a mandrel in the form of an ellipse or a straight part.

There is a known method for manufacturing a pipe from composite materials and a pipe with an outlet made of composite materials (options) according to RF patent No. 2396169, class. В29С 53/82 (2006.01), publ. 08/10/2010 Bulletin. No. 22. This method uses a flexible mandrel on which reinforcing material can be wound on standard winding machines and which can be removed from the curved shell.

The disadvantage of this technical solution is the possibility of producing a pipe of only a rather short length - practically one bend (bend), since as the relative length of the mandrel increases, firstly, the force of resistance to pulling increases, especially in a curved shell, and secondly, because Due to low bending rigidity, the flexible mandrel bends on the winding machine from its own weight and transverse forces from the reinforcing material wound with tension. And the longer the mandrel, the greater the deflection.

Analogs and prototypes of mandrels

To implement the proposed method, as with all pipe manufacturing methods, a mandrel is required.

Standard designs of mandrels are known in the form of a cylindrical shaft with trunnions at the ends for mounting on winding equipment (see I.M. Bulanov, V.V. Vorobey, “Technology of rocket and aerospace structures made of composite materials.” - M.: MSTU Publishing House. N.E. Bauman, 1998).

Standard mandrel designs can only be used for the manufacture of straight pipes.

The disadvantages of using a flexible mandrel or a rigid curved mandrel are discussed above.

Known technical solution RU 2323826 C2 MPK V29S 53/82 (2006.01) publ. 05/10/2008 Bulletin. No. 13, according to which the mandrel contains a shaft with external slats, some of which are fixedly fixed to the shaft, and some are located between the slats of the first group with the possibility of reciprocating movement.

Known technical solution RU 2397868 C2 MPK V29S 53/82 (2006.01) publ. 08/27/2010 Bulletin. No. 24, according to which, for continuous winding of the pipe, a mandrel is used in the form of a central shaft with external strips located on its end (output) part, which, due to a separate drive, carrying out reciprocating axial movements relative to the end, ensure the movement of the cured pipe from the mandrel.

In the last two technical solutions, the outer strips on the mandrel shaft are the executive parts of the mechanism for advancing the wound and cured pipe from the mandrel by applying tangential forces to the inner surface of the hardened shell, similar to the mechanism pulling (moving) fabric in sewing machines.

The known manufacturing method according to RF patent No. 2396169 and the mandrel according to patent RU 2397868, as the closest in technical essence and achieved result, were chosen as the closest analogues (prototypes).

The technical problem that the group of inventions is aimed at solving is the development of a relatively simple and most technologically advanced method for manufacturing a curved pipe with increased performance characteristics.

The technical result from the use of a group of inventions, related so much that they form a single inventive concept, is to obtain spatially oriented high-pressure pipes from composite materials with sections of constant and/or varying curvature along the length while maintaining high levels of reliability, manufacturability and performance, reducing weight, installation complexity, cost and using standard winding equipment.

The technical problem is solved, and the technical result is achieved by:

- in a method for manufacturing a curved pipe from composite materials, according to which a sealing layer of an elastic rubber-like material or a thin-walled metal corrugated shell is placed on a mandrel consisting of a shaft and external strips located on it, spiral layers of a unidirectional reinforcing material of the pipe’s load-bearing shell impregnated with a binder are wound and heat-treated, according to the invention, the outer strips of the mandrel are made removable from the shaft, with side surfaces or edges tightly adjacent to each other to form an outer surface for winding; after winding the power shell, the outer strips, all together as a whole, with the shell located on them, the mandrels are removed from the shaft, the strips are removed from the shell one by one, the ends of the shell are plugged, excess internal pressure is created in it until the shell is inflated into a cylindrical shape, the ends of the shell are forced into the fastening points of the slipway, and with force rods and/or stops the shell is fixed in the required spatially oriented configurations with areas of constant and/or changing axis curvature and sent for heat treatment, and in particular cases of the invention, the reinforcing material in the spiral layers is positioned at an angle of 45° to the generatrix of the pipe shell, the reinforcing material is additionally wound in annular turns in the form of separate belts, the reinforcing material a metal sealing layer is wound into the hollows of the corrugations to their entire depth, the strips on the mandrel shaft are secured at the ends with clamps, after removing the strips from the pipe shell, connecting ends are installed on its ends, before winding the pipe shell, connecting ends are installed on the mandrel, which are wrapped with the end parts of the shell;

- in a mandrel for forming a pipe shell containing a shaft and outer strips located on it, according to the invention, the outer strips are made removable from the shaft, with side surfaces or edges tightly adjacent to each other and together forming the outer surface required for winding the shell, while being longitudinal the side surfaces or edges of at least one strip are made in such a way that, in the absence of a shaft, it can be moved inward towards the axis of the mandrel, before being removed from contact with the surface of the sealing layer and adjacent strips, and in particular cases of the invention, at least one strip made with parallel longitudinal side surfaces, the slats at one end have thickenings, which together form an annular collar, the slats are made of a polymer composite material;

- a slipway for use when implementing the method according to one of paragraphs. 1-7, according to the invention, is made in the form of a spatial rigid load-bearing frame with attachment points for the ends of the pipe and with a set of power rods and/or stops, one end attached through the corresponding nodes to the load-bearing frame, and at the other end having ends with curved supporting surfaces, corresponding to the required surfaces of pipe bends and allowing to reproduce the spatially oriented influence of local and/or forces distributed over the surface, and in particular cases of the invention, the curved supporting surfaces of the ends are made in the form of curved gutters, the inner surface of which is curved in cross section along the radius of the outer surface of the pipe , rods and/or stops are made with devices for reproducing forces, the attachment points of the ends of pipes and rods and/or stops to the load-bearing frame are made removable, with the possibility of rearrangement to various points of the load-bearing frame.

- a curved pipe made of composite materials containing an internal sealing layer made of an elastic rubber-like material or a thin-walled metal corrugated shell and a strength shell made of composite materials, according to the invention, made by a method according to one of claims. 1-7.

The features of the claimed group of inventions that are distinctive from prototypes and known technical solutions are the following:

a) features that ensure the achievement of a technical result in all cases covered by the requested scope of legal protection:

For the way

- the outer bars of the mandrel are made removable from the shaft, with side surfaces or edges tightly adjacent to each other to form an outer surface for winding,

- the outer strips, all together as a single whole, with the shell located on them, are removed from the mandrel shaft,

- strips are removed from the shell one by one,

- the ends of the shell are plugged, excessive internal pressure is created in it until the shell is inflated into a cylindrical shape,

- the ends of the shell are forced into the fastening points of the slipway, and with power rods and/or stops the shell is fixed in the required spatially oriented configuration with areas of constant and/or changing axis curvature.

For mandrel

- the outer strips are made removable from the shaft, with side surfaces or edges tightly adjacent to each other and together forming the outer surface required for winding the shell,

- the longitudinal side surfaces or edges of at least one strip are made in such a way that, in the absence of a shaft, it can be moved inward towards the axis of the mandrel, before being removed from contact with the surface of the sealing layer and adjacent strips.

For the slipway

- contains a spatial rigid load-bearing frame with attachment points for the ends of the pipe,

- and with a set of power rods and/or stops, one end attached through the corresponding nodes to the load-bearing frame, and at the other end having ends with curved support surfaces corresponding to the required surfaces of the pipe bends

- and allowing to reproduce the spatially oriented impact of local and/or surface-distributed forces.

For pipe

- a pipe of a spatially oriented configuration with sections of constant and/or changing axis curvature.

b) features that ensure the achievement of a technical result in particular cases that are covered by the requested scope of legal protection:

For the way

- the reinforcing material in the spiral layers is placed at an angle of 45° to the generatrix of the pipe shell,

- the reinforcing material is additionally wound in annular turns, in the form of separate belts,

- the reinforcing material is wound into the depressions of the corrugations of the metal sealing layer to their entire depth,

- the strips on the mandrel shaft are secured at the ends with clamps,

- after removing the strips from the pipe shell, connecting ends are installed at its ends,

- before winding the pipe shell, connecting ends are installed on the mandrel, which are wound with the end parts of the shell,

For mandrel

- at least one strip is made with parallel longitudinal side surfaces,

- the planks at one end have thickenings, which together form an annular collar,

- the strips are made of polymer composite material,

For the slipway

- curved supporting surfaces of the ends are made in the form of curved gutters, the inner surface of which is curved in cross section along the radius of the outer surface of the pipe,

- rods and/or stops are made with force reproduction devices,

- the attachment points of pipe ends and rods and/or stops to the load-bearing frame are removable, with the possibility of rearrangement to various points of the load-bearing frame,

For pipe

- the reinforcing material in the spiral layers is located at an angle of 45° to the generatrix of the pipe shell,

- the reinforcing material is additionally arranged in annular coils, in the form of separate belts,

- the reinforcing material is located in the depressions of the corrugations of the metal sealing layer to their entire depth.

These distinctive features, each individually and collectively, are aimed at achieving the stated result and are essential. In the prior art, the set of known and distinctive features presented in the claims of a group of inventions is unknown, and, therefore, the invention meets the “novelty” criterion.

The essence of the proposed method is that a soft, uncured shell is removed from the mandrel, which is inflated (straightened) into a cylindrical shell by internal pressure and then positioned (bent) into the required spatial configuration.

In the proposed method, a curved pipe blank made of composite materials is formed using standard winding machines on a straight mandrel by winding a unidirectional reinforcing material impregnated with a binder - threads or strands.

To ensure integrity in the area of large deformations - at a larger bending radius, the sealing layer is made of an elastic rubber-like material (rubber) or a thin-walled metal corrugated shell.

According to standard manufacturing technology, the wound casing is heat treated (cured) on a mandrel in an oven, and then removed from the mandrel.

Since the winding of the reinforcing material to obtain high-quality installation is carried out with tension, the polymerized (cured) shell is located on the mandrel quite tightly and considerable effort is required to remove the shell from the mandrel. For this operation, special capstan machines are usually used, in which the end of the shell is rested against a special support plate with a hole, and the mandrel is pulled out of the shell through the hole. In this case, the shell is subject to quite significant shearing (tangential) forces along the contact surface with the mandrel and compressive forces along the entire cross-section of the shell.

To implement the proposed method, it is necessary to remove the soft, uncured shell from the mandrel. In this case, the use of the standard method is impossible, since the shell, when the mandrel is pulled out, will gather into an accordion (lump) due to the action of tangential forces, damaging the sealing layer and violating the required arrangement of the reinforcing material. In this case, it is necessary to remove the raw (soft) shell from the mandrel without applying anything to it, incl. and tangential forces so as not to damage or distort the location of the sealing layer and reinforcing material (threads).

To solve this problem - removing the soft shell from the mandrel, when implementing the proposed method on a straight mandrel, the strips are made removable, with the side surfaces tightly adjacent to each other to form a surface for winding, which, after winding the shell on the same capstan with the shell located on them, all together, as a single whole, the mandrels are removed from the shaft, but only with emphasis on the base plate, not with the end of the shell, but with the ends of all the strips together. The result is the required soft shell of the pipe on a composite shell of strips.

It is unacceptable to remove the strips from the shell by pulling for the reason stated above - tangential forces from the strips will lead to damage to the sealing layer and the location of the reinforcing material. Therefore, in the proposed method, which is ensured by a technical solution for the design of the mandrel, one strip, followed by the rest in turn, is first shifted to the center of the shell, separated from the inner surface of the sealing layer and adjacent strips, and then, without contacting the shell, is removed from it . The possibility of moving the first strip to the center of the shell is provided by the geometry of the side edges, for example their parallelism.

After removing all the mandrel bars, the ends of the shell are plugged and internal pressure is created in it, for example, air is pumped in until the shell is inflated into a cylindrical shape - like a fire hose under water pressure.

In the inflated state, the pipe blank is located in a stock pile, where it is secured at its ends, and the required spatial configuration is provided by applying transverse forces using power rods and/or stops.

In such a constrained position, the pipe blank undergoes heat treatment.

In a particular case of execution, depending on the operational requirements, the reinforcing material can be located at an angle of 45° to the generatrix of the pipe shell, can be additionally wound in annular turns in the form of separate belts and/or into the depressions of the corrugations of the metal sealing layer to their entire depth.

The strips at the ends can be secured with clamps for stronger pressing against the shaft.

Depending on the design option, endings can be installed at the ends of the pipe, for example, wound-in or installed after removing the shell from the mandrel (the design diagram of such endings is shown in Fig. 4).

At least one strip can be made with parallel longitudinal side surfaces to enable its displacement to the center of the mandrel.

The strips can be made with thickening at one end to increase the strength and rigidity of the ends of the strips when they rest against the plate when removed from the mandrel shaft.

To increase the reliability of contact between the ends of the stack and the pipe shell and/or to reproduce the required geometry of the latter in the bending zone, the ends can be made in the form of curved gutters, the inner surface of which is curved in cross section along the radius of the outer surface of the pipe.

The application of transverse forces to the shell in the slipway through rods and/or stops can be ensured in the attachment points of the latter due to, for example, a threaded connection. But the creation of the necessary forces can be ensured by a separate mechanism, possibly also a threaded one, provided in the design of the rod.

To increase the efficiency and versatility of the slipway, in terms of using its load-bearing frame, the attachment points of the ends of the pipes and rods and/or stops to the load-bearing frame are made removable, with the possibility of rearrangement to various points of the load-bearing frame.

The slipway according to the proposed technical solution is quite universal, since by changing the location of the attachment points of the pipe ends and power rods and/or stops, as well as changing the configuration of the ends, you can change the configuration of the resulting pipe in an almost unlimited range.

The proposed method is universal in terms of producing curved pipes from the simplest with one bend to pipes with several bends and arbitrary spatial configuration. The pipe may contain sections of constant curvature, including those equal to zero, and sections of variable curvature, randomly alternating along the length of the pipe. A straight pipe, or its straight section, is a special case of a pipe with constant curvature equal to zero.

The proposed technical solution requires standard winding equipment and straight mandrels, which significantly simplifies the manufacturing process of curved pipes and makes it possible to increase the technical and/or economic efficiency of curved pipes while maintaining the required levels of reliability.

The group of inventions is illustrated by a description of a specific, but not limiting, example of implementation and the accompanying drawings.

In fig. Figure 1 shows a curved pipe made of composite materials obtained by the claimed method.

In fig. Figure 2 shows a cross-sectional view of a pipe with sealing shell corrugations filled with reinforcing material.

In fig. Figure 3 shows a cross-section of a pipe bend with a thin-walled corrugated shell as a sealing layer, with an annular belt, reinforcing material in the depressions of the corrugations and smooth and corrugated sections of the sealing shell.

In fig. Figure 4 shows the design diagram of the end installed on the pipe blank after removing it from the mandrel and removing the strips.

In fig. Figure 5 shows a mandrel consisting of a shaft and outer strips.

In fig. 6, 7 shows an end view of two versions of the outer mandrel strips.

In fig. Figure 8 shows a view of the end part of the mandrel strips with end thickenings forming an annular collar.

In fig. Figure 9 shows a slipway with a pipe located in it.

In fig. 10 shows a view of the end of the rod and/or the stop of the slipway.

In fig. 11 shows a cross-sectional view of the rod and/or stop.

Curved pipe 1 made of composite materials, consisting of a sealing layer 2 of a thin-walled metal corrugated shell and a load-bearing shell 3 of a unidirectional reinforcing material impregnated with a binder, arranged in spiral layers with the direction of turns 4 at an angle of 45°. A separate belt 5, formed by winding reinforcing material in annular turns.

The shell is made with a connecting end 6, which is installed on the uncured shell. The ending consists of a central part 7 and a union nut 8, which is used to tighten the end of the shell on the conical section of the central part 7.

A mandrel for forming a pipe shell, containing a shaft 9 and outer strips 10 located on it.

The outer strips are made removable from the shaft, with side surfaces or edges tightly adjacent to each other and together forming the outer surface required for winding the shell, while the longitudinal side surfaces or edges of at least one strip, or with the surfaces of adjacent strips adjacent to it, are made in such a way in such a way that, in the absence of a shaft, it can be moved inward towards the axis of the mandrel, until it is removed from contact with the surface of the sealing layer and adjacent strips (Fig. 6, 7).

Figures 6 and 7 show end views of planks 10. In these figures, the dash-dotted line shows the location of the pipe shell 3. The displacement of the first strip to the center of the mandrel is shown by an arrow and its intermediate position after being removed from contact with the sealing layer and adjacent strips. In fig. 7 shows a variant with parallel side surfaces 11 of at least one strip.

The planks at one end have thickenings 12, which together form an annular collar.

The slipway contains a spatial rigid load-bearing frame 13 with attachment points for the ends of the pipe 14 and with a set of power rods and/or stops 15, one end attached through the corresponding nodes to the load-bearing frame, and at the other end having ends 16 with curved supporting surfaces 17 corresponding to the required surfaces pipe bends and allowing to reproduce the spatially oriented influence of local and/or forces distributed over the surface.

The curved supporting surfaces of the ends are made in the form of curved gutters, the inner surface of which is curved in cross section 18 along the radius of the outer surface of the pipe.

The endings can be made in the form of one to two or more rods/or stops.

The rods and/or stops are made with devices for reproducing the forces 19 (shown conditionally) necessary to position the pipe in a given position. Such a force can also be created in the rod attachment unit on the frame using, for example, a threaded connection.

An experimental test carried out at a serial enterprise using industrial equipment confirmed the high efficiency of the proposed method for producing curved pipes and the quality and reliability obtained using the proposed method, a mandrel and a stack of curved pipes made of composite materials.

Claims (16)

1. A method for manufacturing a curved pipe from composite materials, according to which a sealing layer of an elastic rubber-like material or a thin-walled metal corrugated shell is placed on a mandrel consisting of a shaft and external strips located on it, spiral layers of a unidirectional reinforcing material of the pipe’s load-bearing shell impregnated with a binder are wound, and heat treatment, characterized in that the outer strips of the mandrel are made removable from the shaft, with side surfaces or edges tightly adjacent to each other to form an outer surface for winding; after winding the power shell, the outer strips, all together as a whole, with the shell located on them, the mandrels are removed from the shaft, the strips are removed from the shell one by one, the ends of the shell are plugged, excess internal pressure is created in it until the shell is inflated into a cylindrical shape, the ends of the shell are forced into the fastening points of the slipway, and with force rods and/or stops the shell is fixed in the required spatially oriented configurations with areas of constant and/or changing axis curvature and are sent for heat treatment. 2. The method according to claim 1, characterized in that the reinforcing material in the spiral layers is placed at an angle of 45° to the forming shell of the pipe. 3. The method according to claim 1, characterized in that the reinforcing material is additionally wound in annular turns in the form of separate belts. 4. The method according to claim 1, characterized in that the reinforcing material is wound into the depressions of the corrugations of the metal sealing layer to their entire depth. 5. The method according to claim 1, characterized in that the strips on the mandrel shaft are secured at the ends with clamps. 6. The method according to claim 1, characterized in that after removing the strips from the pipe shell, connecting ends are installed at its ends. 7. The method according to claim 1, characterized in that before winding the pipe shell, connecting ends are installed on the mandrel, which are wound with the end parts of the shell. 8. A mandrel for forming a pipe shell for implementing the method according to claim 1, containing a shaft and outer strips located on it, characterized in that the outer strips are made removable from the shaft, with side surfaces or edges tightly adjacent to each other and together forming the required for winding the shell onto the outer surface, wherein the longitudinal side surfaces or edges of at least one strip are made in such a way that, in the absence of a shaft, it can be moved inward towards the axis of the mandrel, before being removed from contact with the surface of the sealing layer and adjacent strips. 9. The mandrel according to claim 8, characterized in that at least one strip is made with parallel longitudinal side surfaces. 10. The mandrel according to claim 8, characterized in that the strips at one end have thickenings, which together form an annular collar. 11. The mandrel according to claim 8, characterized in that the strips are made of a polymer composite material. 12. Slipway for implementing the method according to one of paragraphs. 1-7, characterized in that it is made in the form of a spatial rigid load-bearing frame with attachment points for the ends of the pipe and with a set of power rods and/or stops, one end attached through the corresponding nodes to the load-bearing frame, and at the other end having ends with curved supporting surfaces , corresponding to the required pipe bending surfaces and allowing to reproduce the spatially oriented impact of local and/or surface-distributed forces. 13. The slipway according to claim 12, characterized in that the curved supporting surfaces of the ends are made in the form of curved gutters, the inner surface of which is curved in cross section along the radius of the outer surface of the pipe. 14. The slipway according to claim 12, characterized in that the rods and/or stops are made with force reproduction devices. 15. The slipway according to claim 12, characterized in that the attachment points for the ends of the pipes and rods and/or stops to the load-bearing frame are made removable, with the possibility of rearrangement to various points of the load-bearing frame. 16. A curved pipe made of composite materials, containing an internal sealing layer made of an elastic rubber-like material or a thin-walled metal corrugated shell and a strength shell made of composite materials, characterized in that it is made by the method according to one of paragraphs. 1-7 solidly wound with at least two bends located in different planes.

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