Carbon fiber reinforced resin-based composite corrugated sandwich pipe structure and forming process

Abstract

The invention relates to a carbon fiber reinforced resin-based composite corrugated sandwich pipe structure and a forming process, and relates to the field of composites.The carbon fiber reinforced resin-based composite corrugated sandwich pipe structure comprises an inner pipe, a corrugated pipe, a filling layer, an outer pipe and reinforcing rings, the corrugated pipe with the corrugated cross section is bonded outside the inner pipe, the outer pipe is bonded outside the corrugated pipe, the filling layer is injected into the space between the corrugated pipe and the outer pipe, and the reinforcing rings are arranged on the outer pipe. The corrugated pipe is divided into multiple sections in the length direction of the pipeline, and the reinforcing rings are bonded between every two adjacent corrugated pipe sections and fixedly connected with the inner pipe and the outer pipe. The high-rigidity corrugated sandwich pipe has the advantage that the high-rigidity corrugated sandwich pipe is low in forming difficulty.

Description

Technical Field

[0001] The invention relates to the technical field of composite materials, and in particular to a carbon fiber reinforced resin-based composite corrugated sandwich tube structure and a molding process. Background Art

[0002] With the rapid development of the aerospace field, composite materials are increasingly widely used in the aerospace field. Composite materials have the characteristics of high specific strength, high specific modulus, and corrosion resistance, and have a significant weight reduction effect compared to metal materials. In order to achieve extreme lightweight, composite materials use thin-walled structures.

[0003] Since a single thin-walled tube has poor rigidity and is very prone to deformation, a corrugated core structure is currently used to improve the rigidity of the tube structure. However, under the thin-wall structure, the bonding of the corrugated core to the pipe wall is one of the technical difficulties, and the thickness of the adhesive layer in the bonding section is difficult to control, making it difficult to ensure the bonding quality.

[0004] Therefore, in view of the above shortcomings, it is necessary to provide a carbon fiber reinforced resin-based composite corrugated sandwich tube structure and a molding process. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] The technical problem to be solved by the present invention is to solve the problem that the bonding between the existing corrugated sandwich and the pipe wall is difficult and the bonding effect is poor, resulting in poor forming effect of the corrugated sandwich pipe structure.

[0007] (II) Technical solution

[0008] In order to solve the above technical problems, the present invention provides a carbon fiber reinforced resin-based composite corrugated sandwich tube structure, including an inner tube, a bellows, a filling layer, an outer tube and a reinforcement ring, the bellows with a corrugated cross-section is bonded to the outside of the inner tube, the outer tube is bonded to the outside of the bellows, and the filling layer is injected into the space between the bellows and the outer tube; the bellows is divided into multiple sections along the length direction of the pipeline, and the reinforcement ring is bonded between two adjacent sections of the bellows and is fixedly connected to the inner tube and the outer tube.

[0009] As a further illustration of the present invention, preferably, the filling layer is made of PMI foam.

[0010] As a further illustration of the present invention, preferably, the inner tube and the corrugated tube, and the corrugated tube and the outer tube are bonded with medium-temperature epoxy adhesive film.

[0011] As a further illustration of the present invention, preferably, the reinforcement ring is a solid circular ring structure.

[0012] The present invention also provides a molding process of a carbon fiber reinforced resin-based composite corrugated sandwich tube structure, comprising the following steps:

[0013] Ⅰ. Form the inner tube, the reinforcement ring and the bellows through molds respectively;

[0014] Ⅱ. Design a new bonding tool, lay a medium-temperature epoxy film on the outer end surface of the inner tube, then put the bellows and reinforcement rings on the outer side of the inner tube one by one, and finally use them in the bonding tool to position and pressurize each bellows;

[0015] III. Heat the bonding tool. When the temperature reaches the pressure point, rotate the screw on the bonding tool to move the pressure block toward the axis of the inner tube until the pressure block abuts against the concave part of the bellows and presses the concave part of the bellows toward the inner tube. Cool the bonding tool to cure the medium-temperature epoxy film to complete the connection between the inner tube, the bellows and the reinforcement ring.

[0016] IV. Remove the bonding tools and apply medium-temperature epoxy film on the concave part and outer wall of the bellows;

[0017] Ⅴ. Lay the filling layer on the concave part of the corrugated pipe, lay the medium-temperature epoxy film on the outer wall of the filling layer, and then use the winding machine to wrap the outer tube around the corrugated pipe and the filling layer, and use the vacuum bag or autoclave process for the final curing and molding.

[0018] As a further illustration of the present invention, preferably, the reinforcement ring is integrally formed with the inner tube.

[0019] As a further illustration of the present invention, preferably, the inner tube, the outer tube and the reinforcement ring are all wound and formed by a carbon fiber winding machine.

[0020] As a further illustration of the present invention, preferably, the bellows is formed by vacuum bag pressing or autoclave process.

[0021] As a further illustration of the present invention, preferably, when laying the filling layer, the filling layer is partially trimmed so that the outer arc surface of the filling layer follows the outer arc surface of the corrugated pipe.

[0022] As a further illustration of the present invention, preferably, the gap is filled with a medium-temperature epoxy film.

[0023] (III) Beneficial effects

[0024] The above technical solution of the present invention has the following advantages:

[0025] 1. The inner tube, bellows, reinforcement ring and outer tube of the present invention all have thin-wall features, which not only achieves extreme lightweight, but also has the characteristic of high rigidity after being combined.

[0026] 2. The corrugated sandwich tube of the present invention can be optimized according to different needs. For example, the diameters of the inner tube and the outer tube and the winding angle can be changed to change the size and stiffness of the inner and outer tubes; the cross-sectional shape of the reinforcing ring can be changed from a rectangle to an I-shape; the thickness of the corrugated tube, the shape and number of the sandwich features can be changed; or all of the above factors can be changed at the same time to improve the adaptability of the corrugated sandwich tube.

[0027] 3. The corrugated sandwich tube of the present invention adopts a segmented molding process, and combined with a matching bonding tool, it can control the pressure of all bonding interfaces between the corrugated tube and the inner tube at 360°, which can not only strengthen the bonding strength of each part, but also improve the bonding quality, greatly reducing the manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a cross-sectional view of the present invention;

[0029] Figure 2 is a diagram of the installation position of the reinforcement ring of the present invention;

[0030] Figure 3 is a cross-sectional view of a bonding tool of the present invention;

[0031] Figure 4 yes Figure 3 A is an enlarged view of the middle image.

[0032] In the figure: 1, inner tube; 2, bellows; 3, filling layer; 4, outer tube; 5, reinforcement ring; 6, bonding tool; 61, screw; 62, pressure block. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] A carbon fiber reinforced resin-based composite corrugated sandwich tube structure and molding process, combined with Figure 1 , Figure 2 , including an inner tube 1, a corrugated tube 2, a filling layer 3, an outer tube 4 and a reinforcement ring 5. The inner tube 1, the corrugated tube 2, the outer tube 4 and the reinforcement ring 5 are preferably made of carbon fiber composite materials, and are all thin-walled structures to achieve extreme lightness. The filling layer 3 is preferably PMI foam, multiple sections of corrugated tubes 2 with corrugated cross sections are bonded to the outside of the inner tube 1, and reinforcement rings 5 ​​are bonded between each section of the corrugated tube 2. The outer tube 4 is bonded to the outside of the corrugated tube 2, and the filling layer 3 is injected into the space between the corrugated tube 2 and the outer tube.

[0035] Combination Figure 1 , Figure 2 , the inner tube 1 and the outer tube 4 are both standard tubular structures, and the length of the inner tube 1 and the outer tube 4 is determined by the maximum working length of the winding machine and the maximum size of the vacuum bag, oven or autoclave. In addition to the wavy shape, the cross-section of the corrugated tube 2 can also be U-shaped, C-shaped or trapezoidal, preferably a trapezoidal structure. The reinforcement ring 5 is a solid circular ring structure. The corrugated tube 2 is divided into multiple sections along the length direction of the pipeline. The reinforcement ring 5 is arranged between two adjacent sections of the corrugated tube 2, and the reinforcement ring 5 is respectively fixedly connected to the inner tube 1 and the outer tube 4. Among them, the inner tube 1 and the corrugated tube 2, the corrugated tube 2 and the outer tube 4, and the reinforcement ring 5 and the inner tube 1 and the outer tube 4 are all bonded and fixedly connected with medium-temperature epoxy film.

[0036] The present invention provides two samples for comparison to verify the high rigidity characteristics of the sandwich composite material tube. Sample 1 is a structure with a filling layer 3 and a reinforcement ring 5, and each part is bonded and fixed by medium-temperature epoxy film. Sample 2 only has a structure of an inner tube 1, a corrugated tube 2 and an outer tube 4, and is bonded and fixed by traditional hot pressing. Samples 1 and 2 are both made of carbon fiber material, and the inner diameter of the inner tube 1 is 90mm and the thickness is 1mm. The thickness of the corrugated tube 2 is 2mm. The inner diameter of the outer tube 4 is 100mm and the thickness is 1mm. The total length of the two samples is 1m. The reinforcement rings 5 ​​in sample 1 are distributed at the front and rear ends and the middle of the pipe.

[0037] After measurement, the weight of sample 1 is 2.85kg and the ring stiffness is 155.62kN / m 2 The weight of sample 2 is 2.52kg and the ring stiffness is 102.83kN / m 2 According to the manual, the weight of a 7075 aluminum alloy hollow tube with an outer diameter of 100 mm, an inner diameter of 90 mm, and a length of 1 m is 4.4 kg, and the ring stiffness is 118.2 kN / m. 2 Based on the above data, it can be clearly seen that the structure of the corrugated sandwich tube designed by the present invention, combined with the properties of the carbon fiber composite material itself, can achieve extreme lightweight while ensuring that the composite tube has high rigidity. Compared with traditional aluminum alloy tubes, the rigidity and weight reduction effect can be improved by more than 35%, which is highly practical.

[0038] The present invention also provides a molding process of a carbon fiber reinforced resin-based composite corrugated sandwich tube structure, comprising the following steps:

[0039] Ⅰ. According to the designed thickness and winding angle of the inner tube 1, as well as the parameters and actual number of the reinforcement rings 5, the inner tube 1 is wound on a forming mold, and the inner tube 1 and the reinforcement rings 5 ​​are respectively wound on a carbon fiber winding machine using the forming mold, and then the inner tube 1 and the reinforcement rings 5 ​​are integrally cured and formed through a vacuum bag or autoclave process.

[0040] According to the three-dimensional model of the bellows 2, a molding die corresponding to the bellows 2 is designed and manufactured. The mold is preferably a single-sided mold, and the mold profile is the inner surface of the bellows 2 to be molded. The bellows 2 raw material is layered using the molding die, and then cured and molded by vacuum bag or autoclave process.

[0041] Ⅱ. Combination Figure 3 , Figure 4 A new bonding tool 6 is designed. The bonding tool 6 is also a tubular structure. A plurality of screws 61 are radially threadedly connected to the bonding tool 6. One end of the screw 61 extends into the bonding tool 6 and is rotatably connected to a pressure block 62. The profile of the pressure block 62 is the same as the concave profile of the bellows 2.

[0042] A medium-temperature epoxy film is laid on the outer end surface of the inner tube 1, and then the bellows 2 and the reinforcement ring 5 are put on the outer side of the inner tube 1 one by one, and finally extended into the bonding tool 6, and each bellows 2 is positioned by the guidance of the pressure block 62.

[0043] III. Heat the bonding tool 6, and when the temperature reaches the pressure point, rotate the screw 61 to move the pressure block 62 toward the axis of the inner tube 1 until the pressure block 62 abuts against the concave part of the bellows 2 and presses the concave part of the bellows 2 toward the inner tube 1, so that the bellows 2 fits tightly with the inner tube 1. Cool the bonding tool 6 to cure the medium-temperature epoxy film, and then complete the connection between the inner tube 1, the bellows 2 and the reinforcement ring 5.

[0044] Ⅳ. Remove the bonding tool 6 and lay a medium-temperature epoxy film on the concave portion and outer wall of the bellows 2;

[0045] V. Lay the filling layer 3 on the concave part of the corrugated pipe 2. When laying the filling layer 3, it should be trimmed locally to make the outer arc surface of the filling layer 3 follow the outer arc surface of the corrugated pipe 2. The gap is filled with medium-temperature epoxy film to avoid too large gaps. Lay the medium-temperature epoxy film on the outer wall of the filling layer 3, and then use the winding machine to wrap the outer tube 4 around the corrugated pipe 2 and the filling layer 3, and use the vacuum bag or autoclave process for the final curing and molding.

[0046] Based on the above method, 15 sample tubes were trial-produced, and the molding time for each sample tube was only 4 days. Compared with the traditional molding time of 5-6 days, it is shorter. And through CT detection, more than 90% of the bonding areas of the 15 sample tubes meet the requirements of good bonding quality without debonding, and only about 3% of the remaining 10% of the areas have tiny pore defects. The traditional method uses a full circle of corrugated tubes and inner and outer tube sleeves for bonding, and there is no PMI foam filling. Only visual inspection shows that resin overflow occurs in the hollow part of the corrugated tube; and about 50% of the areas of the 15 trial-produced sample tubes are debonded, and there are also a large number of defects such as poor glue areas and pores on the bonding interface.

[0047] In summary, the corrugated sandwich tube molding process designed by the present invention can not only make the various parts bonded and fit, but also ensure the bonding is firm, effectively improve the bonding quality, and thus improve the overall structural strength of the corrugated sandwich tube after compounding. The mold structure required for this process is also simple, the operation difficulty is low, and the manufacturing threshold is effectively lowered, thereby reducing the manufacturing cost, achieving multiple goals at one stroke.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A carbon fiber reinforced resin-based composite corrugated sandwich tube structure, characterized in that: The invention comprises an inner tube (1), a corrugated tube (2), a filling layer (3), an outer tube (4) and a reinforcing ring (5); the corrugated tube (2) having a corrugated cross section is bonded to the outside of the inner tube (1); the outer tube (4) is bonded to the outside of the corrugated tube (2); the filling layer (3) is injected into the space between the corrugated tube (2) and the outer tube (4); the corrugated tube (2) is divided into multiple sections along the length direction of the pipeline; the reinforcing ring (5) is bonded between two adjacent sections of the corrugated tube (2) and is fixedly connected to the inner tube (1) and the outer tube (4).

2. The carbon fiber reinforced resin-based composite corrugated sandwich tube structure according to claim 1, characterized in that: The filling layer (3) is made of PMI foam.

3. The carbon fiber reinforced resin-based composite corrugated sandwich tube structure according to claim 2, characterized in that: The inner tube (1) and the corrugated tube (2), and the corrugated tube (2) and the outer tube (4) are bonded by medium-temperature epoxy adhesive film.

4. The carbon fiber reinforced resin-based composite corrugated sandwich tube structure according to claim 3, characterized in that: The reinforcing ring (5) is a solid circular ring structure.

5. The molding process of a carbon fiber reinforced resin-based composite corrugated sandwich tube structure according to claim 4, characterized in that: The following steps are included: Ⅰ. The inner tube (1), the reinforcement ring (5) and the bellows (2) are respectively formed by a mold; II. Design a new bonding tool (6), lay a medium-temperature epoxy film on the outer end surface of the inner tube (1), then put the bellows (2) and the reinforcement ring (5) one by one on the outer side of the inner tube (1), and finally use the bonding tool (6) to position and pressurize each bellows (2); III. The bonding tool (6) is heated, and when the temperature reaches the pressure point, the screw (61) on the bonding tool (6) is rotated to move the pressure block (62) toward the axis of the inner tube (1) until the pressure block (62) abuts against the concave portion of the bellows (2) and presses the concave portion of the bellows (2) toward the inner tube (1), and the bonding tool (6) is cooled to allow the medium-temperature epoxy film to solidify, thereby completing the connection between the inner tube (1), the bellows (2) and the reinforcing ring (5); Ⅳ. Remove the bonding tool (6) and apply a medium temperature epoxy film on the concave portion and the outer wall of the bellows (2); V. Lay a filling layer (3) on the concave part of the corrugated pipe (2), lay a medium-temperature epoxy film on the outer wall of the filling layer (3), and then use a winding machine to wrap the outer tube (4) around the corrugated pipe (2) and the filling layer (3), and use a vacuum bag or autoclave process for final curing and molding.

6. The molding process of a carbon fiber reinforced resin-based composite corrugated sandwich tube structure according to claim 5, characterized in that: The reinforcement ring (5) and the inner tube (1) are integrally formed.

7. The molding process of a carbon fiber reinforced resin-based composite corrugated sandwich tube structure according to claim 5, characterized in that: The inner tube (1), the outer tube (4) and the reinforcement ring (5) are all formed by winding using a carbon fiber winding machine.

8. The molding process of a carbon fiber reinforced resin-based composite corrugated sandwich tube structure according to claim 5, characterized in that: The bellows (2) is formed by vacuum bag pressing or autoclave process.

9. The carbon fiber reinforced resin-based composite corrugated sandwich tube structure and molding process according to claim 5, characterized in that: When laying the filling layer (3), local trimming is performed so that the outer arc surface of the filling layer (3) is in line with the outer arc surface of the corrugated pipe (2).

10. The carbon fiber reinforced resin-based composite corrugated sandwich tube structure and molding process according to claim 5, characterized in that: Gaps are filled with medium-temperature epoxy film.

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