Carbon fiber composite material elliptical tube forming die and forming method

Abstract

The present application relates to the technical field of unmanned aerial vehicle equipment, and discloses a carbon fiber composite material elliptical tube forming die and a forming method, which comprise a core die for manufacturing a tubular preform formed by carbon fiber unidirectional prepreg, and an upper die and a lower die for forming a forming cavity, one end of the forming cavity is communicated with a ventilation channel for placing an inflation nozzle, and the opposite end faces of the upper die and the lower die are both used for laying carbon fiber fabric prepreg to form a carbon fiber fabric prepreg layer; when the upper die and the lower die are closed, the tubular preform is located between the two carbon fiber fabric prepreg layers, and the inner cavity of the tubular preform is provided with an inflation bag communicated with the inflation nozzle; the present application can guarantee batch stability of products, make the product structure compact, and reduce the porosity of the product.

Description

Technical Field

[0001] This invention relates to the field of unmanned aerial vehicle (UAV) equipment technology, and in particular to a carbon fiber composite elliptical tube forming mold and forming method. Background Technology

[0002] Currently, most load-bearing pipes used in drones are round pipes. Round pipes have advantages such as simple molding and low cost, but their load-bearing capacity is limited. Due to their asymmetrical shape, elliptical pipes, with the same cross-section as round pipes, can more effectively disperse stress when external forces are applied, and withstand greater bending or compressive forces. They can better adapt to complex installation environments in compact spaces.

[0003] Therefore, there is an urgent need for a carbon fiber composite elliptical tube molding die and molding method that can improve the production efficiency and product quality of elliptical tubes. Summary of the Invention

[0004] The purpose of this invention is to provide a carbon fiber composite material elliptical tube molding die and molding method, which aims to solve or improve at least one of the above-mentioned technical problems.

[0005] To achieve the above objectives, the present invention provides the following solution: The present invention provides a carbon fiber composite elliptical tube molding die, including a core mold for making a tubular preform formed from carbon fiber unidirectional prepreg, and an upper mold and a lower mold for forming a molding cavity;

[0006] One end of the molding cavity is connected to a ventilation channel for placing an inflation nozzle;

[0007] The opposite end faces of the upper mold and the lower mold are both used to lay carbon fiber prepreg to form a carbon fiber prepreg layer.

[0008] When the upper mold and the lower mold are closed, the tubular preform is located between the two carbon fiber fabric prepreg layers, and the inner cavity of the tubular preform is provided with an air bag that communicates with the air inlet.

[0009] Optionally, the lower mold and the lower mold are connected by a plurality of locating pins and locating holes.

[0010] Optionally, the lower mold is provided with overflow grooves on both sides of its end face facing the upper mold.

[0011] Optionally, an explosion-proof bag transition zone is provided at one end of the molding cavity near the ventilation channel.

[0012] The present invention also provides a method for forming elliptical tubes of carbon fiber composite materials, comprising the following steps:

[0013] The carbon fiber unidirectional prepreg is wound and attached to the mandrel using an overlap lay-up technique to form the tubular preform.

[0014] Carbon fiber fabric prepreg is laid on the opposite end faces of the upper mold and the lower mold to form the carbon fiber fabric prepreg layer;

[0015] Remove the tubular preform from the core mold and place an air bag with an air inflator inside the tubular preform.

[0016] The tubular preform is placed inside the lower mold;

[0017] The upper mold and the lower mold are closed and heated and pressurized, while the air inflator is inflated.

[0018] Optionally, the tubular prefabricated body has no fewer than two layers.

[0019] Optionally, the first layer of the tubular precast body overlaps by 5-10mm at both ends.

[0020] Optionally, it also includes the area where the first and last layers of the tubular preform overlap and the joint of the upper and lower molds correspond to the joint of the upper and lower molds.

[0021] Optionally, the tubular preform may be pressed at both ends to make it elliptical.

[0022] Optionally, the carbon fiber fabric prepreg on the side of the lower mold is pressed onto the tubular preform.

[0023] The present invention discloses the following technical effects:

[0024] 1. By using a core mold to create a tubular preform of carbon fiber unidirectional prepreg, and laying carbon fiber fabric prepreg on the opposite end faces of the upper and lower molds, a composite tube structure combining carbon fiber unidirectional prepreg and carbon fiber fabric prepreg is formed. This allows for precise control of the resin content of the product, strict control of the product weight, and ensures batch stability.

[0025] 2. By setting an inflatable bag connected to the air inlet in the inner cavity of the preform, the outer dimensions of the elliptical tube can be precisely controlled by combining the air bag compression molding process during molding, making the product structure dense and reducing the porosity of the product. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0027] Figure 1 This is a schematic diagram of the upper and lower mold structures of the present invention;

[0028] Figure 2 This is a schematic diagram of the core mold and tubular preform structure of the present invention;

[0029] Figure 3 This is a schematic diagram of the composite material elliptical tube structure of the present invention.

[0030] In the diagram: 1. Upper mold; 2. Lower mold; 3. Positioning pin; 4. Glue overflow groove; 5. Ventilation channel; 6. Transition area for explosion-proof bag; 7. Core mold. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Reference Figures 1-3 The present invention provides a carbon fiber composite elliptical tube forming mold, including a core mold 7 for making a tubular preform formed from carbon fiber unidirectional prepreg, and an upper mold 1 and a lower mold 2 for forming a forming cavity.

[0034] One end of the molding cavity is connected to a ventilation channel 5 for placing the inflation nozzle;

[0035] The opposite end faces of the upper mold 1 and the lower mold 2 are used to lay carbon fiber fabric prepreg to form a carbon fiber fabric prepreg layer.

[0036] When the upper mold 1 and the lower mold 2 are closed, the tubular preform is located between the two carbon fiber fabric prepreg layers, and the inner cavity of the tubular preform is provided with an air bag connected to the air inlet.

[0037] By using the core mold 7 to create a tubular preform of carbon fiber unidirectional prepreg, and laying carbon fiber fabric prepreg on the opposite end faces of the upper mold 1 and the lower mold 2, a composite tube structure combining carbon fiber unidirectional prepreg and carbon fiber fabric prepreg is formed. This allows for precise control of the resin content of the product, strict control of the product weight, and ensures batch stability of the product.

[0038] By incorporating an inflatable bag connected to an inflation nozzle into the cavity of the preform, the external dimensions of the elliptical tube can be precisely controlled during the molding process, resulting in a denser product structure and reduced porosity.

[0039] Furthermore, the core mold 7 is cylindrical, with a circumference equal to 98% (1-0.007t) of the theoretical arc length of the inner diameter of the elliptical tube, where t is the thickness of the tube.

[0040] Furthermore, the circumference of the inflatable bag = the theoretical arc length of the inner diameter of the elliptical tube + (15-20) mm.

[0041] In one embodiment of the present invention, the lower mold 2 is connected to the lower mold 2 by a plurality of positioning pins 3 and positioning holes.

[0042] The combination of multiple locating pins 3 and locating holes can improve the positioning accuracy of the lower mold 2.

[0043] In one embodiment of the present invention, the lower mold 2 is provided with overflow grooves 4 on both sides of the end face facing the upper mold 1.

[0044] During the curing process, excess material and gas inside the product will flow into the overflow grooves 4 on the left and right sides of the lower mold 2 along with the resin.

[0045] In one embodiment of the present invention, an explosion-proof bag transition zone 6 is provided at one end of the molding cavity near the ventilation channel 5.

[0046] The present invention also provides a method for forming elliptical tubes of carbon fiber composite materials, comprising the following steps:

[0047] The carbon fiber unidirectional prepreg is wound and attached to the core mold 7 using an overlap lay-up technique to form a tubular preform.

[0048] Carbon fiber fabric prepreg is laid on the opposite end faces of the upper mold 1 and the lower mold 2 to form a carbon fiber fabric prepreg layer.

[0049] Remove the tubular preform from the core mold 7 and place an air bag with an air inflator inside the tubular preform.

[0050] Place the tubular preform into the lower mold 2;

[0051] The upper mold 1 and lower mold 2 are closed and heated and pressurized. Simultaneously, the inflation device is activated via the inflation nozzle connector. Specifically, the mold temperature controller is set to 140℃. After mold closure, the upper and lower panels are pressurized. Once pressurization is complete, the inflation device is activated. When the temperature of the upper mold 1 and lower mold 2 reaches (60±5)℃, intermittent inflation begins at a pressure of 0.2~0.25MPa. When the temperature of the upper mold 1 and lower mold 2 reaches (90±5)℃, the pressure increases to 0.8~0.9MPa and is maintained. After the product has cured, the molds can only be opened and the product removed once the temperature of the upper mold 1 and lower mold 2 drops below 60℃.

[0052] In one embodiment of the present invention, the tubular preform has no fewer than two layers.

[0053] Furthermore, the thickness of the tubular precast body is within 10 mm.

[0054] In one embodiment of the present invention, the first layer of the tubular precast body overlaps by 5-10 mm at both ends.

[0055] In one embodiment of the invention, the area where the first and last layers of the tubular preform overlap corresponds to the joint between the upper mold 1 and the lower mold 2.

[0056] In one embodiment of the invention, the method further includes pressing both ends of the tubular preform to make the tubular preform elliptical.

[0057] In one embodiment of the present invention, the carbon fiber fabric prepreg on the side of the lower mold 2 is pressed onto the tubular preform.

[0058] The composite material elliptical tube formed by this invention has advantages such as light weight and corrosion resistance, and a long service life. The molding process is simple and easy to operate, the product's dimensions are precisely controllable, the surface is smooth and flat, and it is easy to perform subsequent surface treatment, making it suitable for mass production.

[0059] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0060] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for forming an elliptical tube from carbon fiber composite material, comprising the following steps: The carbon fiber unidirectional prepreg is wound and attached to the core mold (7) using the overlapping lay-up technique to form a tubular preform; Carbon fiber fabric prepreg is laid on the opposite end faces of the upper mold (1) and the lower mold (2) to form a carbon fiber fabric prepreg layer; Remove the tubular preform from the core mold (7) and place an air bag with an air inflator inside the tubular preform; The tubular preform is placed inside the lower mold (2); The upper mold (1) and the lower mold (2) are closed and heated and pressurized, while the air inflator is inflated.

2. The method for forming an elliptical tube from carbon fiber composite material according to claim 1, characterized in that, The tubular prefabricated body has no fewer than two layers.

3. The method for forming an elliptical tube from carbon fiber composite material according to claim 1, characterized in that, The first layer of the tubular precast structure overlaps by 5-10mm at both ends.

4. The method for forming an elliptical tube from carbon fiber composite material according to claim 1, characterized in that, It also includes the area where the first and last layers of the tubular preform overlap and the joint of the upper mold (1) and the lower mold (2).

5. The method for forming an elliptical tube from carbon fiber composite material according to claim 4, characterized in that, It also includes pressing both ends of the tubular preform to make the tubular preform elliptical.

6. The method for forming an elliptical tube from carbon fiber composite material according to claim 5, characterized in that, It also includes pressing the carbon fiber fabric prepreg on the side of the lower mold (2) onto the tubular preform.

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