A flexible connection structure of a composite material thin-walled circular tube and a forming method thereof

Abstract

The present invention discloses a flexible connection structure of a composite material thin-walled circular tube, comprising a plurality of circular tubes and a metal ring for connecting adjacent circular tubes; the outer edge of the metal ring extends outward to form a shoulder, the wall thickness of the shoulder is greater than the wall thickness of the metal ring; a stopper is provided on the circular tube, the metal ring is fitted on the stopper of the circular tube by gluing the shoulder, and a composite material layer is wound around the connection between the circular tube and the metal ring. The present invention solves the problems of low connection strength and poor structural sealing of the traditional connection structure, and at the same time has good assembly processability, and can avoid damage to the metal ring during the assembly process.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical structures, in particular to a flexible connection structure of composite material thin-walled circular tubes. Background Art

[0002] In the current advanced mechanical structure design, in order to obtain better structural strength, high specific strength composite materials are often used in the main structure of the machine. Compared with traditional metal structures, it can meet the use requirements under more severe load environments. However, due to the limitations of materials and process levels, the connections between the components in this type of mechanical structure still mostly use metal parts, and there are problems with the connection and coordination between the two different materials of composite materials and metals, also known as the flexible connection problem. As a typical mechanical component, composite circular tubes are often connected by multi-section circular tubes in order to achieve the expected functional requirements; in order to make the whole composed of multi-section composite circular tubes have good strength, stiffness and deformation coordination performance, the design of flexible connection structure between composite circular tubes is particularly important.

[0003] The difficulty in solving the above technical problems lies in:

[0004] Metal rings are often used to connect composite material round tubes. This connection design needs to solve three key technical problems. First, it must have sufficient connection strength. Traditional connection solutions usually use a simple docking structure with fiber winding on the outside. Its connection strength is low, and it is easy to cause structural instability or even loosening during service. Second, it must have good structural sealing to ensure that the multi-section composite material round tube does not leak during use. Third, it must have good assembly processability. Traditional connection structures can only meet small interference fit of less than 0.5 mm. In the manufacture and use of advanced composite material round tube connection components, it is required to achieve large interference fit of more than 0.5 mm between the ring and the composite material round tube without damaging the relatively weak metal ring.

[0005] The significance of solving the above technical problems is:

[0006] In order to achieve the above technical requirements, a new type of flexible connection structure between multi-section composite material circular tubes is invented and designed, which can solve the problems of low connection strength and poor structural sealing of traditional connection structures. At the same time, it has good assembly processability and can avoid damage to metal rings during the assembly process. Summary of the invention

[0007] In view of the above problems, the present invention provides a flexible connection structure of a composite material thin-walled circular tube and a forming method thereof.

[0008] The technical solution of the present invention is:

[0009] A flexible connection structure of composite thin-walled circular tubes, comprising a plurality of circular tubes and a metal ring for connecting adjacent circular tubes;

[0010] The outer edge of the metal ring extends outward to form a shoulder, and the wall thickness of the shoulder is greater than the wall thickness of the metal ring;

[0011] The circular tube is provided with a stopper, and the metal ring is interference fitted on the stopper of the circular tube through the shoulder and gluing, and a composite material layer is wound around the connection between the circular tube and the metal ring.

[0012] Preferably, the length of the stop is 400-600 mm, and the wall thickness is 5-6 mm.

[0013] Preferably, the length of the shoulder is 20% to 30% of the total length of the round tube, and the wall thickness of the shoulder is 1 to 3 mm thicker than the stop of the round tube.

[0014] Preferably, the metal ring body is made of high-strength aluminum alloy, titanium alloy or structural steel.

[0015] Preferably, the composite material layer comprises a glass fiber hoop layer, a glass fiber angle layer and a carbon fiber hoop layer which are sequentially wound around the connection between the metal ring and the circular tube.

[0016] Further preferably, the thickness of the glass fiber annular layer is 2 to 4 mm, and it is wound annularly at 90° to cover the connection between the metal ring and the circular tube. The winding tension is 50 to 100 N, and the tension decreases layer by layer in a certain proportion to achieve the same residual tension in each layer.

[0017] Further preferably, the glass fiber angle layer has a thickness of 1 to 3 mm and is wound at a certain angle and covers the outer side of the glass fiber hoop layer.

[0018] Further preferably, the winding angle of the glass fiber angle layer is 50° to 80°.

[0019] Further preferably, the carbon fiber hoop layer has a thickness of 5 to 10 mm, is hoop-wound at 90° to cover the outside of the glass fiber angle layer, has a winding tension of 40 to 180 N, and decreases layer by layer in a certain proportion to achieve the same residual tension in each layer.

[0020] The second purpose of the present invention is:

[0021] A method for forming a flexible connection structure of a composite material thin-walled circular tube comprises the following steps:

[0022] S101: applying glue on the stopper of the round tube, putting a section of the round tube on the core mold, pushing the shoulder of the metal ring through an auxiliary fixture, fitting the metal ring with glue on the stopper of the round tube, and then pushing another section of the round tube on the core mold;

[0023] S102: Waiting for the glue to solidify;

[0024] S103: Winding a glass fiber circumferential layer, a glass fiber angle layer and a carbon fiber circumferential layer in sequence at a connection point between the metal ring and the circular tube, and forming a flexible connection structure connecting the metal ring and the circular tube after curing.

[0025] The advantages and beneficial effects of the present invention are:

[0026] 1. High connection strength.

[0027] The glass fiber hoop layer is used to apply prestress to the relatively weak internal circular tubes and metal rings to reduce the structural stress of the circular tubes and metal rings during service and improve the strength safety margin of the connection parts. The glass fiber angle layer is used to enhance the axial stiffness of the connection between the metal ring and the circular tube stop, which can effectively reduce the structural damage caused by the middle bending of the composite circular tube during service. The carbon fiber hoop layer has a large thickness and appropriate winding tension, which can effectively protect the internal circular tubes, metal rings, glass fiber composite material layers and other components, and improve the overall strength reliability of the connection components.

[0028] 2. Good sealing performance. In the present invention, the outer side of the composite material round tube stopper and the inner side of the metal ring form a sealing surface. Under the action of the high tension winding of the glass fiber, the sealing surface has a sufficiently high contact pressure to achieve a good sealing effect. The shoulder of the metal ring can limit the axial displacement of the metal ring of the composite material round tube under a complex load environment, prevent the structure from loosening, and at the same time extend the length of the potential leakage channel and further improve the sealing performance of the connection part.

[0029] 3. Good assembly processability. In the present invention, the shoulder of the metal ring is used to bear the axial assembly force during the assembly process, avoiding the relatively weak annular corrugation of the metal ring from being stressed, and ensuring the assembly effect. The long stop of the round tube can effectively increase the matching area between the metal ring and the round tube, and help axial guidance during plug-in assembly, further improving the overall straightness and coaxiality of the connected parts after assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The technical solution of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments, but it should be understood that these drawings are designed only for explanation purposes and are not intended to limit the scope of the present invention. In addition, unless otherwise specified, these drawings are intended only to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

[0031] Figure 1 It is a schematic diagram of the planar structure of the present invention.

[0032] In the figure:

[0033] 1-metal ring; 2-round tube; 3-shoulder; 4-glass fiber circumferential layer; 5-glass fiber angle layer; 6-carbon fiber circumferential layer. DETAILED DESCRIPTION

[0034] First of all, it should be noted that the specific structure, features and advantages of the present invention will be specifically described below by way of example, but all descriptions are only for illustration and should not be understood as limiting the present invention in any way. In addition, any single technical feature described or implied in the embodiments mentioned herein, or any single technical feature displayed or implied in the drawings, can still be combined or deleted between these technical features (or their equivalents) to obtain more other embodiments of the present invention that may not be directly mentioned in this document. In addition, in order to simplify the drawings, the same or similar technical features may be marked only in one place in the same drawing.

[0035] In the present invention, unless otherwise clearly stipulated and limited, the terms such as "installation", "setting", "connection", "fixation" and "screw-on" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. Unless otherwise clearly defined, ordinary technicians in this field can understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0036] The following is combined with Figure 1 The present invention will be described in detail.

[0037] Embodiment 1:

[0038] A flexible connection structure of composite thin-walled circular tubes, comprising a plurality of circular tubes 2 and a metal ring 1 for connecting adjacent circular tubes 2;

[0039] The outer edge of the metal ring 1 extends outward to form a shoulder 3, and the wall thickness of the shoulder 3 is greater than the wall thickness of the metal ring 1;

[0040] The circular tube 2 is provided with a stopper, and the metal ring 1 is interference fitted on the stopper of the circular tube 2 through the shoulder 3 . A composite material layer is wrapped around the connection between the circular tube 2 and the metal ring 1 .

[0041] Working process:

[0042] In this embodiment, Figure 1 As shown, the flexible connection structure includes two sections of round tubes 2, the round tubes 2 are made of composite materials, and the two sections of round tubes 2 are connected by metal rings 1. During operation, one section of the round tube 2 is first put on the core mold, and the shoulder 3 of the metal ring 1 is pushed by an auxiliary clamp, and the metal ring 1 is fitted on the stopper of the round tube 2 with glue, and then another section of the round tube 2 is pushed on the core mold. Among them, if you want the metal ring 1 to be more firmly connected and have better assembly lubricity, you can apply glue on the stopper of the round tube 2, and then perform the above process. After the glue is cured, a double-layer composite material layer of glass fiber and carbon fiber is wrapped around the connection between the round tube 2 and the metal ring 1, and a connector between the metal ring and the round tube is formed after the curing is completed. The composite material layer has the characteristics of high strength and wear resistance, which can effectively protect the interior and reduce the structural stress of various components such as the metal ring 1 and the round tube 2 during service.

[0043] Furthermore, in the embodiment, it can be considered that the length of the stopper is 400-600 mm and the wall thickness is 5-6 mm. The long stopper of the round tube 2 can effectively increase the matching area between the metal ring 1 and the round tube 2 and is used for axial guidance of plug-in assembly.

[0044] Furthermore, in the embodiment, it can be considered that the length of the shoulder 3 is 20% to 30% of the total length of the circular tube 2, and the wall thickness of the shoulder 3 is 1 to 3 mm thicker than the stop of the circular tube 2. The shoulder 3 of the metal ring 1 is used to withstand the axial assembly force during the assembly process, avoid the circumferential corrugation of the metal ring 1 from being stressed, and can limit the axial displacement of the metal ring 1 under the complex load environment of the circular tube 2, prevent the structure from loosening, and at the same time extend the length of the potential leakage channel and improve the sealing of the connection structure.

[0045] Furthermore, in the embodiments, it can also be considered that the main body of the metal ring 1 is made of high-strength aluminum alloy, titanium alloy or structural steel to improve the structural strength of the metal ring 1.

[0046] Furthermore, it can also be considered in the embodiment that the composite material layer includes a glass fiber circumferential layer 4, a glass fiber angle layer 5 and a carbon fiber circumferential layer 6 which are sequentially wound at the connection between the metal ring 1 and the circular tube 2. In this embodiment, the composite material layer is a double-layer composite material layer of glass fiber and carbon fiber, wherein the glass fiber composite material layer includes a glass fiber circumferential layer 4 and a glass fiber angle layer 5, and the carbon fiber composite material layer includes a carbon fiber circumferential layer 6.

[0047] Furthermore, in the embodiments, it can be considered that the thickness of the glass fiber annular layer 4 is 2 to 4 mm, and it is annularly wound at 90° to cover the connection between the metal ring 1 and the circular tube 2. The winding tension is 50 to 100 N, and the tension decreases layer by layer in a certain proportion to achieve the same residual tension in each layer.

[0048] Furthermore, in the embodiment, it can also be considered that the glass fiber angle layer has a thickness of 1 to 3 mm and is wound and covered on the outside of the glass fiber hoop layer 4 at a certain angle.

[0049] Furthermore, in the embodiments, it can also be considered that the winding angle of the glass fiber angle layer is 50° to 80°.

[0050] Furthermore, in the embodiment, it can also be considered that the thickness of the carbon fiber hoop layer 6 is 5 to 10 mm, and the hoop layer 6 is wound at 90° to cover the outside of the glass fiber angle layer, and the winding tension is 40 to 180 N. The tension decreases layer by layer in a certain proportion to achieve the same residual tension in each layer.

[0051] In this embodiment, the glass fiber annular layer 4 adopts a high tension winding process to apply a certain prestress to the metal ring 1, effectively enhance the connection strength between the metal ring 1 and the stopper mating surface of the round tube 2, and obtain good structural sealing. The glass fiber angle layer 5 is used to enhance the axial stiffness of the connection part of the metal ring 1, and effectively reduce the structural damage caused by the bending of the middle part of the round tube 2 during service. The carbon fiber annular layer 6 has a large thickness and a suitable winding tension, which can effectively protect the internal components and reduce the structural stress of the metal ring 1, round tube 2 and other components during service.

[0052] Embodiment 2:

[0053] A method for forming a flexible connection structure of a composite material thin-walled circular tube comprises the following steps:

[0054] S101: applying glue on the stopper of the round tube 2, putting a section of the round tube 2 on the core mold, pushing the shoulder 3 of the metal ring 1 through an auxiliary fixture, fitting the metal ring 1 on the stopper of the round tube 2 with glue, and then pushing another section of the round tube 2 on the core mold;

[0055] S102: Waiting for the glue to solidify;

[0056] S103: Winding a glass fiber annular layer 4, a glass fiber angle layer 5 and a carbon fiber annular layer 6 in sequence at the connection between the metal ring 1 and the circular tube 2, and forming a flexible connection structure connecting the metal ring 1 and the circular tube 2 after curing.

[0057] Application Example 1:

[0058] The flexible connection structure is prepared by the flexible connection structure forming method of the composite material thin-walled circular tube in Example 2, wherein:

[0059] The size parameters of round tube 2 are: stop length 400mm, wall thickness 5mm;

[0060] The dimension parameters of shoulder 3 are: length 80mm, wall thickness 8mm;

[0061] Parameters of the glass fiber hoop layer 4: thickness 2mm, 10 layers, winding tension of each layer is 86N / 85N / 84N / 82N / 81N / 80N / 79N / 78N / 77N / 76N;

[0062] Parameters of glass fiber angle layer 5: thickness 1mm, angle 70°, winding tension 60N;

[0063] Parameters of carbon fiber hoop layer 6: thickness 5mm, 20 layers wound, winding tension of each layer is 172N / 172N / 164N / 156N / 148N / 140N / 133N / 125N / 118N / 111N / 104N / 97N / 84N / 77N / 71N / 65N / 58N / 52N / 46N.

[0064] According to the above example, under normal use conditions of composite thin-walled circular tubes, the flexible connection structure is used, and its advantages are:

[0065] (1) Higher connection strength. Compared with the traditional butt joint structure, shoulder-free structure or connection structure without high-tension fiber winding, the torsional failure load limit of the above example can be increased by about 20%, and the tensile failure load limit can be increased by about 40%. The metal ring 1 and the round tube 2 can obtain an additional prestress of about 250MPa. At the same time, the residual tension of each layer of the glass fiber composite material is equal, about 50N, and the residual tension of each layer of the carbon fiber composite material is equal, about 40N. Equal residual tension can effectively increase the load of the first layer failure under the working state of the connection part. Compared with the traditional connection structure, the above example has higher connection strength.

[0066] (2) Better sealing performance. Compared with the traditional docking structure, the structure without shoulder or the connection structure without fiber high tension winding, the vacuum single point leak rate of the above example can be reduced from 10 -4 Pa·m 3 / s level increased to 10 - 6 Pa·m 3 / s level and above, which can meet the needs of using in more stringent vacuum sealing environments.

[0067] (3) Better assembly processability. Compared with the traditional butt joint structure, the structure without shoulder or the connection structure without fiber high tension winding, the above example can meet the assembly with a larger interference of more than 0.5 mm, ensuring that the relatively weak annular corrugation of the metal tube will not be greatly deformed or even damaged during the assembly process.

[0068] In summary, the present invention provides a flexible connection structure of a composite material thin-walled circular tube and a forming method thereof.

[0069] The above embodiments describe the present invention in detail, but the contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the present invention.

Claims

1. A flexible connection structure of a composite thin-walled circular tube, characterized in that: It includes multiple sections of round tubes and metal rings for connecting adjacent round tubes; The outer edge of the metal ring extends outward to form a shoulder, and the wall thickness of the shoulder is greater than the wall thickness of the metal ring; The circular tube is provided with a stopper, the metal ring is interference fitted on the stopper of the circular tube by gluing the shoulder, and a composite material layer is wound around the connection between the circular tube and the metal ring; The composite material layer comprises a glass fiber hoop layer, a glass fiber angle layer and a carbon fiber hoop layer which are sequentially wound at the connection between the metal ring and the round tube; The thickness of the glass fiber circumferential layer is 2-4 mm, and the circumferential winding is 90° to cover the connection between the metal ring and the round tube. The winding tension is 50-100N, and the tension decreases layer by layer according to a certain ratio to achieve the same residual tension in each layer. The glass fiber angle layer has a thickness of 1 to 3 mm and is wound at a certain angle to cover the outer side of the glass fiber hoop layer; The winding angle of the glass fiber angle layer is 50° to 80°; The carbon fiber hoop layer has a thickness of 5 to 10 mm, and is wound hoop-wise at 90° to cover the outside of the glass fiber angle layer. The winding tension is 40 to 180 N, and the tension decreases layer by layer in a certain proportion to achieve the same residual tension in each layer.

2. A flexible connection structure of a composite material thin-walled circular tube as claimed in claim 1, characterized in that: The length of the shoulder is 20% to 30% of the total length of the round tube, and the wall thickness of the shoulder is 1 to 3 mm thicker than the stop of the round tube.

3. A flexible connection structure of a composite material thin-walled circular tube as claimed in claim 2, characterized in that: The metal ring body is made of high-strength aluminum alloy, titanium alloy or structural steel.

4. A method for forming a flexible connection structure of a composite material thin-walled circular tube according to claim 3, characterized in that: The following steps are involved: S101: applying glue on the stopper of the round tube, putting a section of the round tube on the core mold, pushing the shoulder of the metal ring through an auxiliary fixture, fitting the metal ring with glue on the stopper of the round tube, and then pushing another section of the round tube on the core mold; S102: Waiting for the glue to solidify; S103: Winding a glass fiber circumferential layer, a glass fiber angle layer and a carbon fiber circumferential layer in sequence at a connection point between the metal ring and the circular tube, and forming a flexible connection structure connecting the metal ring and the circular tube after curing.

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