Thin-wall and ultra-large length-diameter ratio carbon fiber tubular beam forming die and process

Abstract

The invention provides a thin-wall ultra-large-length-diameter-ratio carbon fiber tubular beam forming die and technology in the field of carbon fiber composite material tubular beam forming, the thin-wall ultra-large-length-diameter-ratio carbon fiber tubular beam forming die comprises an upper die, a lower die and core dies, the core dies are located in the upper die and the lower die, the core dies are connected with the two ends of the upper die and the two ends of the lower die respectively, and the upper die and the lower die are connected through bolts; the upper mold and the lower mold provide mold locking force through bolts, adjusting bolts are arranged at the bottom of the lower mold, the height of the lower mold is adjusted through the adjusting bolts, and exhaust holes are formed in the upper mold and the lower mold. The manufacturing of the thin-wall ultra-large-length-diameter-ratio carbon fiber tubular beam is realized by utilizing a combined die technology and an expansion bag forming process, and the defects that the whole die is difficult to process, the precision is difficult to guarantee and the whole die is easy to deform in the processing process are overcome; and an electric blanket is adopted to heat the mold, so that low-energy-consumption, low-cost and high-efficiency manufacturing is realized.

Description

Technical Field

[0001] The invention relates to the field of carbon fiber composite material tubular beam forming, and in particular to a thin-walled ultra-large aspect ratio carbon fiber tubular beam forming die and process. Background Art

[0002] In the manufacturing process of carbon fiber composite pipe fittings, the commonly used molding process is the winding process. The winding molding process is a process in which continuous fibers or cloth tapes soaked in resin glue are wound onto a mandrel according to a certain pattern, and then cured and demolded to form a composite product. Since the mandrel needs to be pulled out, the length of the pipe fitting is limited, and it is impossible to manufacture thin-walled fiber composite pipe beams with a large aspect ratio. Summary of the invention

[0003] In view of the defects in the prior art, the purpose of the present invention is to provide a thin-walled ultra-large aspect ratio carbon fiber tube beam forming die and process.

[0004] According to the present invention, a thin-walled carbon fiber tubular beam forming mold with a large aspect ratio comprises an upper mold, a lower mold and a core mold. The core mold is located in the upper mold and the lower mold, and the core mold is respectively connected to the upper mold and the lower mold at both ends. The upper mold and the lower mold are connected by bolts. The upper mold and the lower mold provide a locking force through the bolts. An adjusting bolt is provided at the bottom of the lower mold. The height of the lower mold is adjusted by the adjusting bolt. Exhaust holes are provided on the upper mold and the lower mold.

[0005] Preferably, the upper die and the lower die are respectively provided with L-shaped grooves;

[0006] When the upper die and the lower die are connected, the grooves form a molding cavity, and the molding cavity has rounded corners on four sides.

[0007] Preferably, the rounded corners include a first rounded corner, a second rounded corner, a third rounded corner and a fourth rounded corner, the first rounded corner and the fourth rounded corner are respectively located on the upper mold and the lower mold, and the second rounded corner and the third rounded corner are located on the parting line of the upper mold and the lower mold.

[0008] Preferably, the first fillet and the fourth fillet are respectively provided with exhaust grooves, and the exhaust grooves are connected to the exhaust holes;

[0009] And the exhaust holes are evenly distributed on the upper die and the lower die.

[0010] Preferably, the upper mold includes a first upper mold, a second upper mold and a third upper mold, both ends of the first upper mold are connected to the second upper mold, the second upper mold is connected to the third upper mold, and the mold core is respectively connected to the second upper mold and the third upper mold.

[0011] Preferably, the lower mold is formed by connecting a plurality of lower modules, and adjusting bolts are respectively connected to both ends of the bottom of the lower modules.

[0012] A thin-walled carbon fiber tube beam forming process with a large aspect ratio, the specific steps are as follows:

[0013] S1. Under room temperature, the prepreg is introduced into a blanking machine for cutting;

[0014] S2, laying the prepreg cut in S1 on the workbench, and cleaning and preheating the mold. After the preheating is completed, laying the material in the mold;

[0015] S3. When the mold is preheated, cut the inner air bag and the outer air bag into appropriate lengths, wrap the two ends of the inner air bag around the air nozzle and seal it, while keeping the air nozzle unobstructed, and put the outer air bag on the inner air bag;

[0016] S4, placing the layer in the molding cavity, then placing the air bag in the mold, and finally fitting the air bag from one direction to wrap and close the mold, and tightening the bolts;

[0017] S5, heating and pressurizing the mold for curing;

[0018] S6, demoulding and post-processing to obtain the finished product.

[0019] Preferably, in the above step S2, the preheating method adopts electric blanket heating, the electric blanket wraps the lower modules one by one, and the temperature of the electric blanket is set to 150°C for heating. When the mold temperature rises to about 60°C, the power is turned off. After heat dissipation, the temperature of each lower module drops to 50°C-55°C and the material laying operation is carried out in the mold.

[0020] Preferably, in the above step S4, the release paper on the bottom layer of the ply is torn off, the ply is placed in the center of the molding cavity, the upper blue film is torn off after ensuring that the ply is flat, and then the air bag is placed in the mold, and finally the air bag is attached from one direction for wrapping, and the mold is closed section by section according to the mold closing sequence, and then the bolts are tightened to make the bolts reach the maximum tightening force.

[0021] Preferably, in the above step S5, the whole mold is wrapped with an electric blanket, and then the vacuum bag is filled with 0.1 MPa for leakage test. After no abnormality is found, heating is started, and the temperature of the electric blanket is set to 200°C;

[0022] When the mold temperature rises to 60℃, increase the pressure to 0.3MPa; when it rises to 75℃, increase the pressure to 0.6MPa; when it rises to 85℃, reduce the pressure to 0.3MPa; when the mold temperature reaches 105℃, increase the pressure to 0.9MPa; when the mold temperature reaches 120℃, turn off the power and air compressor; when the mold temperature drops to 50℃, cut off the air supply.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention utilizes the combined mold technology and the expansion bag forming process to realize the manufacture of thin-walled carbon fiber tubular beams with ultra-large aspect ratio, overcomes the shortcomings of the overall mold processing difficulty, difficulty in ensuring accuracy, and easy deformation during the processing, improves the quality of the product, and simplifies demoulding; an electric blanket is used to heat the mold to achieve low energy consumption, low cost and high efficiency manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0026] Figure 1 This is a schematic diagram of the structure of Example 1 of the present invention;

[0027] Figure 2 It is an exploded view of Example 1 of the present invention;

[0028] Figure 3 is a cross-sectional view of Example 1 of the present invention;

[0029] Figure 4 This is a process flow chart of Example 2 of the present invention.

[0030] Reference numerals in the figure: first upper die 1 , second upper die 2 , third upper die 3 , lower die block 4 , first fillet 11 , second fillet 12 , third fillet 13 , fourth fillet 14 , exhaust groove 15 , exhaust hole 16 . DETAILED DESCRIPTION

[0031] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several changes and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0032] Example 1

[0033] The present invention provides a thin-walled carbon fiber tube beam forming die with a large aspect ratio, such as Figure 1 As shown, it includes an upper mold, a lower mold and a core mold. The core mold is located in the upper mold and the lower mold, and the core mold is respectively connected to the upper mold and the lower mold at both ends. The upper mold and the lower mold are connected by bolts, and the upper mold and the lower mold provide locking force through the bolts.

[0034] like Figure 3As shown, an L-shaped groove is provided on the upper mold and the lower mold respectively. When the upper mold and the lower mold are connected, the groove forms a molding cavity, and the molding cavity is provided with fillets on the four sides. The fillets include a first fillet 11, a second fillet 12, a third fillet 13 and a fourth fillet 14. The first fillet 11 and the fourth fillet 14 are respectively located on the upper mold and the lower mold, and the second fillet 12 and the third fillet 13 are located on the parting line of the upper mold and the lower mold. An exhaust groove 15 is provided on the first fillet 11 and the fourth fillet 14 respectively, and the exhaust groove 15 is connected to the exhaust hole 16; and the exhaust holes 16 are evenly distributed on the upper mold and the lower mold.

[0035] like Figure 2 As shown, the upper mold is composed of three first upper molds 1, two second upper molds 2 and two third upper molds 3. After the three first upper molds 1 are connected, the second upper molds 2 are respectively connected to the two ends of the first upper molds 1, and the third upper molds 3 are respectively connected to the outside of the second upper molds 2. The mold core is made of metal material to ensure the internal and external dimensional accuracy of the end, which is convenient for sleeve. The mold core is respectively connected to the second upper mold 2 and the third upper mold 3, and the mold core is also composed of a block mold. The lower mold is composed of four lower modules 4 connected by sheet metal blocks and bolts, and the two ends of the bottom of the lower module 4 are respectively connected with adjustment bolts. The adjustment bolts are used to adjust the height of the mold from the table or the ground, which is convenient for moving and hoisting the mold. The first upper mold 1, the second upper mold 2, the third upper mold 3 and the lower module 4 are provided with exhaust holes 16.

[0036] More specifically, the aspect ratio of the manufactured thin-walled carbon tube is 50 (for square tube beams, the diameter is the diameter of the circumscribed circle of the cross-sectional rectangle). The cross-sectional shape of the carbon fiber tube beam manufactured by the present invention can be rectangular, circular or other shapes. The mold adopts a combined mold structure to overcome the shortcomings of the difficulty of integral mold processing, the difficulty in ensuring mold accuracy and easy deformation. The mold molding cavity adopts a special placement method, such as Figure 3 As shown in the figure, this placement method is easy to demold, and the parting line is on the fillet, which is conducive to exhaust, no glue accumulation, no glue deficiency, and ensures that the fillet is fully formed. Venting grooves are opened at the upper and lower fillets, and vent holes are opened at a certain distance, which is conducive to full exhaust.

[0037] According to the length and outer diameter of the carbon tube beam, the combined mold structure provided by the present invention can be modified or expanded to meet the outer diameter and length requirements of the carbon tube beam. The modification or expansion includes but is not limited to changes in length and outer diameter, changes in the cross-sectional shape of the carbon tube, and changes in thickness.

[0038] Example 2

[0039] A thin-walled carbon fiber tube beam forming process using the first embodiment, such as Figure 4 As shown, the specific steps are as follows:

[0040] S1. After taking the prepreg out of the cold storage, it should be placed at room temperature (21±3℃) for full thawing until there is no condensed water on the packaging bag and the material temperature is close to room temperature. Then it should be introduced into the blanking machine and cut according to the designed blanking drawing;

[0041] S2. Adjust the level of the working platform to ensure that the gap between each platform does not exceed 1mm. The indoor working temperature is controlled at 21±3℃, and the humidity is controlled at 42±10%. Then use a right-angle steel ruler to locate the reference as the starting point for laying the layers, and lay the layers according to the designed order. While laying the layers, the mold is cleaned and preheated. The mold is heated by an electric blanket. The specific operation method is: wrap the lower modules one by one with the electric blanket, set the temperature of the electric blanket to 150℃ for heating, and turn off the power when the mold temperature rises to about 60℃. After the heat is dissipated, the temperature of each section of the mold drops to 50℃-55℃ (use a thermometer to detect the outside and inner cavity of the mold), and then lay the material in the mold (this material is the material that has been laid on the aforementioned workbench);

[0042] S3. While the mold is preheating, start preparing the air bag. Cut an air bag 800mm longer than the pipe beam to be manufactured (specification 180mm*60mm), wrap the air nozzles at both ends and seal them, and check whether the air nozzles are unobstructed (make sure the air nozzles are unobstructed). Then cut another air bag 300mm shorter than the previous air bag and put it on the previous air bag for protection. When putting on the outer bag, prevent the inner bag from turning over or getting tangled;

[0043] S4. Tear off the release paper on the bottom layer of the laminate, place the laminate in the center of the mold cavity, make sure the laminate is flat, tear off the upper blue film, then put the air bag into the mold, and finally wrap it from one direction (from top to bottom, from left to right at the same time); close the mold section by section according to the mold closing sequence, and then tighten the bolts to achieve the maximum tightening force;

[0044] S5. Wrap the whole mold with an electric blanket, then fill the vacuum bag with 0.1MPa for leakage test. Start heating after no abnormality is found. The temperature of the electric blanket is set to 200℃.

[0045] When the mold temperature rises to 60℃, increase the pressure to 0.3MPa; when it rises to 75℃, increase the pressure to 0.6MPa; when it rises to 85℃, reduce the pressure to 0.3MPa; when the mold temperature reaches 105℃, increase the pressure to 0.9MPa; when the mold temperature reaches 120℃, turn off the power supply and air compressor; when the mold temperature drops to 50℃, cut off the air supply;

[0046] S6. After curing is completed, the mold is opened to remove auxiliary materials such as the vacuum bag and breathable felt to obtain a blank. Then, after grinding the flash and cleaning the overflowed resin, the finished product is obtained.

[0047] More specifically, the present invention provides a clamping force through metal bolts and an internal expansion bag, which is beneficial to the formation of an inner cavity. The inner cavity pressure is large and can reach the pressure level of the autoclave, thereby improving the quality of the product; the layer design of the tube beam can be realized through the combined mold internal pressure expansion bag molding process, and the layer angle can be arbitrarily combined, which is more convenient than winding molding and overcomes the difficulty of core pulling in winding molding; the use of internal pressure expansion bag molding does not have the difficulty of demolding the inner mold, and the molding process can achieve the optimal combination design of process parameters. In addition, during the manufacturing process, the heating scheme of wrapping the mold with an electric blanket has the following significant advantages: ① No large dedicated oven is required; ② Low energy consumption; ③ Low equipment cost; ④ High heating efficiency. In short, a breakthrough in the manufacturing of thin-walled carbon tube beams with ultra-large aspect ratio can be achieved, and the required manufacturing accuracy can be achieved.

[0048] In the description of the present application, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0049] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various changes or modifications within the scope of the claims, which does not affect the essence of the present invention. In the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other arbitrarily.

Claims

1. A thin-walled carbon fiber tube beam forming die with a large aspect ratio, characterized in that: The invention comprises an upper mould, a lower mould and a core mould, wherein the core mould is located inside the upper mould and the lower mould, and the core mould is respectively connected to the two ends of the upper mould and the lower mould, the upper mould and the lower mould are connected by bolts, the upper mould and the lower mould provide a clamping force by the bolts, an adjusting bolt is arranged at the bottom of the lower mould, the height of the lower mould is adjusted by the adjusting bolt, and exhaust holes (16) are arranged on the upper mould and the lower mould.

2. The thin-walled ultra-large aspect ratio carbon fiber tube beam forming die according to claim 1, characterized in that: The upper die and the lower die are respectively provided with L-shaped grooves; When the upper die and the lower die are connected, the grooves form a molding cavity, and the molding cavity has rounded corners on four sides.

3. The thin-walled ultra-large aspect ratio carbon fiber tube beam forming die according to claim 2, characterized in that: The fillets include a first fillet (11), a second fillet (12), a third fillet (13) and a fourth fillet (14); the first fillet (11) and the fourth fillet (14) are located on the upper mold and the lower mold, respectively; the second fillet (12) and the third fillet (13) are located on the parting line of the upper mold and the lower mold.

4. The thin-walled carbon fiber tube beam forming die with a large aspect ratio according to claim 3 is characterized in that: An exhaust groove (15) is provided on the first fillet (11) and the fourth fillet (14), respectively, and the exhaust groove (15) is connected to the exhaust hole (16); Furthermore, the exhaust holes (16) are evenly distributed on the upper mold and the lower mold.

5. The thin-walled carbon fiber tube beam forming die with a large aspect ratio according to claim 1, characterized in that: The upper mold comprises a first upper mold (1), a second upper mold (2) and a third upper mold (3); both ends of the first upper mold (1) are connected to the second upper mold (2); the second upper mold (2) is connected to the third upper mold (3); and the mold core is respectively connected to the second upper mold (2) and the third upper mold (3).

6. The thin-walled carbon fiber tube beam forming die with a large aspect ratio according to claim 1, characterized in that: The lower die is formed by connecting a plurality of lower die blocks (4), and the two ends of the bottom of the lower die block (4) are respectively connected with the adjusting bolts.

7. A forming process using the thin-walled ultra-large aspect ratio carbon fiber tube beam forming mold according to any one of claims 1 to 6, characterized in that: The specific steps are as follows: S1. Under room temperature, the prepreg is introduced into a blanking machine for cutting; S2, laying the prepreg cut in S1 on the workbench, and cleaning and preheating the mold. After the preheating is completed, laying the material in the mold; S3. When the mold is preheated, cut the inner air bag and the outer air bag into appropriate lengths, wrap the two ends of the inner air bag around the air nozzle and seal it, while keeping the air nozzle unobstructed, and put the outer air bag on the inner air bag; S4, placing the layer in the molding cavity, then placing the air bag in the mold, and finally fitting the air bag from one direction to wrap and close the mold, and tightening the bolts; S5, heating and pressurizing the mold for curing; S6, demoulding and post-processing to obtain the finished product.

8. The thin-walled carbon fiber tube beam forming process of claim 7, characterized in that: In the above step S2, the preheating method adopts electric blanket heating, and the electric blanket wraps the lower modules (4) one by one, and the temperature of the electric blanket is set to 150°C for heating. When the mold temperature rises to about 60°C, the power is turned off. After the heat is dissipated, the temperature of each section of the lower module (4) drops to 50°C-55°C and the material laying operation is carried out in the mold.

9. The thin-walled carbon fiber tube beam forming process of claim 7, characterized in that: In the above step S4, tear off the release paper on the bottom layer of the ply, place the ply in the center of the molding cavity, ensure that the ply is flat, tear off the upper blue film, then put the air bag into the mold, and finally wrap the air bag from one direction, close the mold section by section according to the mold closing sequence, and then tighten the bolts to make the bolts reach the maximum tightening force.

10. The thin-walled carbon fiber tube beam forming process of claim 7, characterized in that: In the above step S5, the whole mold section is wrapped with an electric blanket, and then the vacuum bag is filled with 0.1 MPa for leakage test. After no abnormality is found, heating is started, and the temperature of the electric blanket is set to 200°C; When the mold temperature rises to 60℃, increase the pressure to 0.3MPa; when it rises to 75℃, increase the pressure to 0.6MPa; when it rises to 85℃, reduce the pressure to 0.3MPa; when the mold temperature reaches 105℃, increase the pressure to 0.9MPa; when the mold temperature reaches 120℃, turn off the power and air compressor; when the mold temperature drops to 50℃, cut off the air supply.

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