Carbon fiber tube with shear-resistant flange and preparation method thereof

Abstract

The present invention discloses a carbon fiber tube with a shear-resistant flange, comprising an inner tube and a radial disc integrally connected to both ends of the inner tube, wherein annular radial carbon fiber fabric layers and folded carbon fiber fabric layers are alternately bonded on the inner surface of the radial disc; the two ends of the folded carbon fiber fabric layer are radial ring parts, and an axial tube part is integrally connected between the radial ring parts at both ends; a winding layer is wound between the axial tube part of the radially innermost folded carbon fiber fabric layer and the inner tube, and a winding layer is wound between the axial tube parts of two adjacent layers of folded carbon fiber fabric layers; each layer structure is bonded by liquid resin to form an integral structure. The present invention also discloses a corresponding preparation method. The present invention greatly increases the shear resistance of the flange structure under tension, so that the carbon fiber tube with a flange structure can effectively resist the shear stress between the flange and the axial tube part of the tube body when the flange is subjected to tension or pressure.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon fiber tubes. Background Art

[0002] Carbon fiber tube is a high-strength, lightweight and corrosion-resistant tube. Due to its excellent properties, it is widely used in aviation, aerospace, military, automobile, sports equipment, construction and machinery.

[0003] Flanges are commonly used to connect pipes to each other and to other interfaces. Currently, carbon fiber tube flanges are metal structures. Because the end faces of the carbon fiber tubes act as a barrier to the flanges, the flanges offer excellent resistance to axial pressure. However, due to the low bonding strength between the metal flange and the carbon fiber tube, the flanges' resistance to axial outward shear stress is poor. Therefore, current carbon fiber tube metal flange structures are unsuitable for environments requiring resistance to high shear stresses generated by axial tension (this can be continuous, occasional, or intermittent, and these shear stresses can damage the connection between the flange and the carbon fiber tube, or even cause the connection between the flange and the carbon fiber tube to loosen and fall off).

[0004] The inner layer of a carbon fiber tube typically consists of a thin metal tube that serves as a winding support. A long carbon fiber (of course, this carbon fiber can also be wound into a carbon fiber tube by breaking it into several sections) is wound around the outer surface of the metal tube in various designed patterns to form the final carbon fiber tube structure. If the flange is also wound with carbon fiber, the manufacturing process is more complex than that of a carbon fiber tube with a metal flange structure. Furthermore, the carbon fiber winding plane can only be perpendicular or approximately perpendicular to the axis of the carbon fiber tube. As a result, when subjected to axial shear stress, the wound flange will displace axially and lacks sufficient shear stress resistance. Since these flanges lack sufficient shear stress resistance, the existing technology still uses metal flanges, which have simpler manufacturing processes, for carbon fiber tubes. In short, existing carbon fiber tube flange structures lack sufficient resistance to shear stress generated by tension, limiting their application and making them unsuitable for applications where the flange is subject to high shear stress generated by tension. Summary of the Invention

[0005] The object of the present invention is to provide a carbon fiber tube with a shear-resistant flange, wherein the flange structure has good performance in resisting shear stress.

[0006] To achieve the above-mentioned purpose, the carbon fiber tube with shear flange of the present invention comprises a titanium alloy inner layer structure, which comprises an inner tube and radial discs integrally connected to both ends of the inner tube, with the axis direction pointing to the center of the carbon fiber tube as the inward axis and the axis direction pointing to the outside of the carbon fiber tube as the outward axis.

[0007] Annular radial carbon fiber fabric layers and folded carbon fiber fabric layers are alternately bonded to the inner surface of the radial disc;

[0008] The two ends of the folded carbon fiber fabric layer are radial ring parts parallel to the radial disc, and the axial cylinder part of the folded carbon fiber fabric layer is integrally connected between the radial inner ends of the radial ring parts at both ends of the folded carbon fiber fabric layer;

[0009] A winding layer is wound between the axial cylinder portion of the radially innermost folded carbon fiber fabric layer and the inner cylinder, and a winding layer is wound between the axial cylinder portions of two adjacent folded carbon fiber fabric layers;

[0010] The radial carbon fiber fabric layer, the folded carbon fiber fabric layer and the winding layer are all bonded by liquid resin to form an integral structure.

[0011] The present invention also discloses a method for preparing the carbon fiber tube with shear-resistant flange, which is carried out according to the following steps:

[0012] The first step is soaking, soaking the production materials in a liquid resin container so that the outer surface of each production material is covered with liquid resin;

[0013] The second step is to bond the innermost layer;

[0014] First, a radial carbon fiber fabric layer soaked in resin is attached to the axial inner surfaces of the radial discs at both ends of the inner cylinder. The outer diameter of the radial carbon fiber fabric layer is the same as the outer diameter of the radial discs, and the inner diameter of the radial carbon fiber fabric layer is the same as the outer diameter of the inner cylinder.

[0015] Next, a layer of carbon fiber layer soaked in resin is wound around the inner cylinder between the radial carbon fiber fabric layers at both ends of the inner cylinder to complete the bonding step of the innermost layer;

[0016] The third step is to bond the two middle layers;

[0017] The first step is to bond the middle inner layer, that is, the folded carbon fiber fabric layer; the middle portion of the planar folded carbon fiber fabric layer soaked in resin is wrapped around the circumferential outer surface of the carbon fiber tube outside the completed flange structure to form the axial cylindrical portion of the folded carbon fiber fabric layer; a plurality of shear slits are axially cut in the portion of the folded carbon fiber fabric layer outside the axial cylindrical portion, and the folded carbon fiber fabric layer between adjacent shear slits forms carbon fiber fabric strips; each carbon fiber fabric strip is bent in the radial direction of the carbon fiber tube and bonded to the axial inner surface of the completed flange structure;

[0018] The second step is to bond the middle outer layer;

[0019] The middle outer layer includes a radial carbon fiber fabric layer as the flange structure and a winding layer as the axial part of the carbon fiber tube. The radial carbon fiber fabric layer is first attached to the axial inner surface of the flange structure at both ends of the carbon fiber tube. Then, the winding layer is formed by winding carbon fibers between the two radial carbon fiber fabric layers just attached at both ends of the carbon fiber tube.

[0020] Repeat the third step until the thickness of the flange structure and the axial portion of the carbon fiber tube reaches a predetermined thickness, and then perform the fourth step;

[0021] The fourth step is to paste the outermost layer;

[0022] The outermost layer is bonded using the same process as the middle inner layer to complete the carbon fiber tube with shear-resistant flange.

[0023] After each pasting operation is completed, an infrared radiation heater is used to bake the pasted area to solidify the liquid resin and harden the pasted structure.

[0024] The axial thickness of the flange can be adjusted by adjusting the thickness of the radial carbon fiber fabric layer.

[0025] The present invention has the following advantages:

[0026] The flange structure in the present invention is formed by bonding a radial carbon fiber fabric layer and a radial ring part of a folded carbon fiber fabric layer through liquid resin, wherein the radial ring part of the folded carbon fiber fabric layer and the axial tube part are an integral structure, and play the role of a skeleton in the overall structure formed by bonding; the direction of the shear generated by the axial tension is perpendicular to the radial carbon fiber fabric layer and the radial ring part of the folded carbon fiber fabric layer, and the shear generated by the tension needs to destroy the radial carbon fiber fabric layer and the radial ring part of the folded carbon fiber fabric layer to damage the flange structure, so that the flange structure in the present invention has a strong resistance to the shear effect caused by the tension, so that the carbon fiber tube with a flange structure can effectively resist the shear stress between the flange and the axial tube part of the tube body when the flange is subjected to tension or pressure.

[0027] In contrast, if the flange structure is formed by winding carbon fiber, the multiple turns of carbon fiber layers are prone to staggered displacement on the one hand, and on the other hand, there is no integrated structure between the carbon fiber layers and the main part of the carbon fiber tube. There is no structural skeleton, and the shear tension will not be transmitted to the main part of the carbon fiber tube (the axial cylindrical part of each folded carbon fiber fabric layer) through the skeleton structure (folded carbon fiber fabric layer) as in the present invention, and the shear tension will not be shared by the main part. Therefore, the performance of resisting shear tension is significantly poor.

[0028] If the metal flange and the carbon fiber tube are bonded together by resin, the metal flange and the carbon fiber tube do not have an integrated structure, the bonding force is weak, and the performance of resisting shear tension is significantly worse than that of the present invention.

[0029] The preparation method of the present invention is simple and efficient. It breaks the traditional process of making carbon fiber tubes simply by winding carbon fibers, and breaks the traditional structural form of the separate structure of the flange structure and the carbon fiber tube. The new process and new structure of winding carbon fibers and pasting carbon fiber fabrics make the flange structure and the carbon fiber tube more structurally integrated, so that the main cylindrical structure of the carbon fiber tube can share the axial outward tension exerted on the flange structure (the main cylindrical structure of the carbon fiber tube in the prior art can bear the axial inward pressure, but cannot effectively share the axial tension), and also enables the flange structure to also adopt carbon fiber materials, which reduces the overall weight of the carbon fiber tube and the flange structure as a whole. The flange structure and the carbon fiber tube structure are more integrated, and can more effectively resist the shear stress between the flange structure and the axial cylindrical part of the tube body.

[0030] By adopting the preparation method of the present invention, the axial thickness of the flange can be conveniently adjusted to meet the requirements of flange thickness and structural strength in different usage scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of the present invention;

[0032] Figure 2 yes Figure 1 Enlarged view of point A in the middle;

[0033] Figure 3 It is a force diagram of the flange structure when it is subjected to shear tension. DETAILED DESCRIPTION

[0034] like Figures 1 to 3 As shown, the present invention provides a carbon fiber tube with a shear flange including a titanium alloy inner layer structure, wherein the titanium alloy inner layer structure includes an inner tube 1 and radial discs 2 integrally connected to both ends of the inner tube 1 (the plane where the radial discs 2 are located is in the radial direction of the carbon fiber tube), with the axis direction pointing to the center of the carbon fiber tube being the inward axis direction, and the axis direction pointing to the outside of the carbon fiber tube being the outward axis direction.

[0035] The inner surface of the radial disc 2 is alternately bonded with annular radial carbon fiber fabric layers 3 and folded carbon fiber fabric layers;

[0036] The two ends of the folded carbon fiber fabric layer are radial ring parts 4 parallel to the radial disc 2, and the radial inner ends of the radial ring parts 4 at both ends of the folded carbon fiber fabric layer are integrally connected with the axial cylindrical part 5 of the folded carbon fiber fabric layer;

[0037] A winding layer 6 is wound between the axial cylinder portion 5 of the radially innermost folded carbon fiber fabric layer and the inner cylinder 1, and a winding layer 6 is wound between the axial cylinder portions 5 of two adjacent folded carbon fiber fabric layers;

[0038] The bonding involved in the present invention is all done by liquid resin (e.g., epoxy resin). The radial carbon fiber fabric layer 3, the folded carbon fiber fabric layer (including its axial cylindrical portion 5), and the winding layer 6 are all bonded by liquid resin to form an integral structure.

[0039] The flange structure in the present invention is formed by bonding a radial carbon fiber fabric layer 3 and a radial ring part 4 of a folded carbon fiber fabric layer through liquid resin, wherein the radial ring part 4 of the folded carbon fiber fabric layer and the axial tube part 5 are an integral structure, and play the role of a skeleton in the overall structure formed by bonding; the direction of the shear generated by the axial tension is perpendicular to the radial carbon fiber fabric layer 3 and the radial ring part 4 of the folded carbon fiber fabric layer, and the shear generated by the tension needs to destroy the radial carbon fiber fabric layer 3 and the radial ring part 4 of the folded carbon fiber fabric layer to damage the flange structure, so that the flange structure in the present invention has a strong ability to resist the shear effect caused by the tension of the flange, so that the carbon fiber tube with a flange structure can effectively resist the shear stress between the flange and the axial tube part 5 of the tube body when the flange is subjected to tension or pressure.

[0040] In contrast, if the flange structure is formed by winding carbon fiber, the multiple turns of carbon fiber layers are prone to staggered displacement on the one hand, and on the other hand, there is no integrated structure between the carbon fiber layers and the main part of the carbon fiber tube. There is no structural skeleton, and the shear tension will not be transmitted to the main part of the carbon fiber tube (the axial cylindrical part 5 of each folded carbon fiber fabric layer) through the skeleton structure (folded carbon fiber fabric layer) as in the present invention, and the shear caused by the tension will be shared by the main part. Therefore, the shear performance of resisting the tension is significantly poor.

[0041] In contrast, if the metal flange and the carbon fiber tube are bonded together by resin, the metal flange and the carbon fiber tube do not have an integrated structure, the bonding force is weak, and the shear performance against tension is significantly worse than that of the present invention.

[0042] The present invention also discloses a method for preparing the carbon fiber tube with shear-resistant flange, which is carried out according to the following steps:

[0043] The first step is soaking, soaking the manufacturing materials in a liquid resin (e.g., epoxy resin) container so that the outer surface of each manufacturing material is covered with liquid resin; each manufacturing material includes a radial carbon fiber fabric layer material, a folded carbon fiber fabric layer material, and a carbon fiber material;

[0044] The second step is to bond the innermost layer;

[0045] First, a ring-shaped radial carbon fiber fabric layer 3 soaked in resin is attached to the axial inner surface of the radial discs 2 at both ends of the inner cylinder 1. The outer diameter of the ring-shaped radial carbon fiber fabric layer 3 at these locations (at both ends of the inner cylinder 1) is the same as the outer diameter of the radial discs 2, and the inner diameter of the ring-shaped radial carbon fiber fabric layer 3 at these locations is the same as the outer diameter of the inner cylinder 1.

[0046] Next, a carbon fiber layer soaked in resin is wound around the inner cylinder 1 between the radial carbon fiber fabric layers 3 at both ends of the inner cylinder 1 to form a carbon fiber layer, completing the step of bonding the innermost layer;

[0047] The third step is to bond the two middle layers;

[0048] First, the middle inner layer, i.e., the folded carbon fiber fabric layer, is bonded. The middle portion of the planar folded carbon fiber fabric layer, which has been soaked in resin, is wrapped around the circumferential outer surface of the carbon fiber tube outside the completed flange structure to form an axial barrel portion 5 of the folded carbon fiber fabric layer. Several shear slits are cut axially in the portion of the folded carbon fiber fabric layer outside the axial barrel portion 5, and the folded carbon fiber fabric layer between adjacent shear slits forms carbon fiber fabric strips. Each carbon fiber fabric strip is bent in the radial direction of the carbon fiber tube and bonded to the axial inner surface of the completed flange structure.

[0049] The second step is to bond the middle outer layer;

[0050] The middle outer layer includes a radial carbon fiber fabric layer 3, which serves as the flange structure, and a winding layer 6, which serves as the axial portion of the carbon fiber tube. The radial carbon fiber fabric layer 3 is first attached to the axial inner surface of the flange structure at both ends of the carbon fiber tube. Then, the winding layer 6 is formed by winding carbon fibers between the two newly attached radial carbon fiber fabric layers 3 at both ends of the carbon fiber tube.

[0051] Repeat the third step until the thickness of the flange structure and the axial portion of the carbon fiber tube reaches a predetermined thickness, and then perform the fourth step;

[0052] The fourth step is to paste the outermost layer;

[0053] The outermost layer is bonded using the same process as the middle inner layer to complete the carbon fiber tube with shear-resistant flange.

[0054] The preparation method of the present invention is simple and efficient. It breaks the traditional process of making carbon fiber tubes simply by winding carbon fibers, and breaks the traditional structural form of the separate structure of the flange structure and the carbon fiber tube. The new process and new structure of winding carbon fibers and pasting carbon fiber fabrics make the flange structure and the carbon fiber tube more structurally integrated, so that the main cylindrical structure of the carbon fiber tube can share the axial outward tension exerted on the flange structure (the main cylindrical structure of the carbon fiber tube in the prior art can bear the axial inward pressure, but cannot effectively share the axial tension), and also enables the flange structure that bears tension to adopt carbon fiber material, thereby reducing the overall weight of the carbon fiber tube and the flange structure as a whole. The flange structure and the carbon fiber tube structure are more integrated, and can more effectively resist the shear stress caused by tension or pressure on the flange structure.

[0055] After each bonding step, an infrared heater is used to bake the bonded area, causing the liquid resin to solidify rapidly at high temperature, thereby hardening the bonded structure. The optimal baking temperature for epoxy resin is around 80°C (80±20°C), and the optimal baking time per layer is around 8 minutes (8±5 minutes).

[0056] The axial thickness of the flange is adjusted by adjusting the thickness of the radial carbon fiber fabric layer 3 (a thicker carbon fiber can be used to produce a thicker carbon fiber fabric, or a composite structure of two layers of carbon fiber fabric bonded together can also produce a thicker carbon fiber fabric).

[0057] By adopting the preparation method of the present invention, the axial thickness of the flange can be conveniently adjusted to meet the requirements of flange thickness and structural strength in different usage scenarios.

[0058] Figure 3 The "P" and arrow in the flange represent the direction in which the flange bears tension. Figure 3 The thick solid line shown in the middle reference numeral 19 is the annular surface where the shear stress is concentrated between the flange and the axial barrel portion 5 of the tube body when the flange is subjected to tension. The allowable shear stress value of the flange here should be greater than the maximum shear stress actually experienced by the flange structure in actual application scenarios. In the prior art, it is often difficult to achieve an allowable stress value greater than the maximum shear stress actually experienced by the flange structure in actual application scenarios for the flange structure of carbon fiber tubes. Compared with the past, the present invention increases the degree of integration between the flange structure and the main structure (cylindrical) of the carbon fiber tube, and has a structure that strengthens the skeleton (the radial ring portion 4 of the folded carbon fiber fabric layer is an integral structure with the axial barrel portion 5, so that the radial ring portion 4 has the function of strengthening the skeleton). In the direction of shear force, it is the fabric that resists rather than the carbon fiber winding layer 6. These factors all enhance the shear resistance of the flange structure in the present invention, making it easier than before to design a carbon fiber tube and its flange structure with an allowable stress value that meets the requirements of specific usage scenarios.

[0059] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A carbon fiber tube with a shear flange, comprising a titanium alloy inner layer structure, wherein the titanium alloy inner layer structure comprises an inner tube and radial discs integrally connected to both ends of the inner tube, with the axis direction pointing to the center of the carbon fiber tube being the inward axis direction and the axis direction pointing to the outside of the carbon fiber tube being the outward axis direction. Its characteristics are: Annular radial carbon fiber fabric layers and folded carbon fiber fabric layers are alternately bonded to the inner surface of the radial disc; The two ends of the folded carbon fiber fabric layer are radial ring parts parallel to the radial disc, and the axial cylinder part of the folded carbon fiber fabric layer is integrally connected between the radial inner ends of the radial ring parts at both ends of the folded carbon fiber fabric layer; A winding layer is wound between the axial cylinder portion of the radially innermost folded carbon fiber fabric layer and the inner cylinder, and a winding layer is wound between the axial cylinder portions of two adjacent folded carbon fiber fabric layers; The radial carbon fiber fabric layer, the folded carbon fiber fabric layer and the winding layer are all bonded by liquid resin to form an integral structure.

2. The method for preparing a carbon fiber tube with a shear-resistant flange according to claim 1, characterized in that Follow these steps: The first step is soaking, soaking the production materials in a liquid resin container so that the outer surface of each production material is covered with liquid resin; The second step is to bond the innermost layer; First, a radial carbon fiber fabric layer soaked in resin is attached to the axial inner surfaces of the radial discs at both ends of the inner cylinder. The outer diameter of the radial carbon fiber fabric layer is the same as the outer diameter of the radial discs, and the inner diameter of the radial carbon fiber fabric layer is the same as the outer diameter of the inner cylinder. Next, a layer of carbon fiber layer soaked in resin is wound around the inner cylinder between the radial carbon fiber fabric layers at both ends of the inner cylinder to complete the bonding step of the innermost layer; The third step is to bond the two middle layers; The first step is to bond the middle inner layer, that is, the folded carbon fiber fabric layer: the middle portion of the flat folded carbon fiber fabric layer soaked in resin is wrapped around the circumferential outer surface of the carbon fiber tube outside the completed flange structure to form the axial cylindrical portion of the folded carbon fiber fabric layer; a plurality of shear slits are cut axially in the portion of the folded carbon fiber fabric layer outside the axial cylindrical portion, and the folded carbon fiber fabric layer between adjacent shear slits forms carbon fiber fabric strips; each carbon fiber fabric strip is bent in the radial direction of the carbon fiber tube and bonded to the axial inner surface of the completed flange structure; The second step is to bond the middle outer layer; The middle outer layer includes a radial carbon fiber fabric layer as the flange structure and a winding layer as the axial part of the carbon fiber tube. The radial carbon fiber fabric layer is first attached to the axial inner surface of the flange structure at both ends of the carbon fiber tube. Then, the winding layer is formed by winding carbon fibers between the two radial carbon fiber fabric layers just attached at both ends of the carbon fiber tube. Repeat the third step until the thickness of the flange structure and the axial portion of the carbon fiber tube reaches a predetermined thickness, and then perform the fourth step; The fourth step is to paste the outermost layer; The outermost layer is bonded using the same process as the middle inner layer to complete the carbon fiber tube with shear-resistant flange.

3. The preparation method according to claim 2, wherein: After each pasting operation is completed, an infrared radiation heater is used to bake the pasted area to solidify the liquid resin and harden the pasted structure.

4. The preparation method according to claim 2 or 3, characterized in that: The axial thickness of the flange can be adjusted by adjusting the thickness of the radial carbon fiber fabric layer.

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