A method for forming a composite material component with a hollow structure

Abstract

The present invention discloses a method for forming a composite material component of a hollow structure, comprising the following process steps: S1, placing a carbon fiber layer (2) into a mold (3); S2, placing an air blowing bag (1) into the carbon fiber layer (2); S3, closing the mold (3), and using a press to heat and pressurize the upper and lower surfaces of the mold (3); S4, injecting heat transfer oil (4) into the air blowing bag (1); S5, taking the product out of the mold (3); S6, removing the air blowing bag (1) inside the product; S7, grinding, spraying paint, and polishing the product. The present invention has the characteristics of low equipment cost, good product appearance, high product mechanical strength and rigidity, and can be used in industries such as aviation and military industry.

Description

Technical Field

[0001] The invention relates to a method for forming a composite material component with a hollow structure, belonging to the technical field of polymer materials. Background Art

[0002] Composite parts with hollow structures, such as aircraft wings, bicycle frames, carbon fiber battery boxes, etc., are generally hollow structures inside. They are generally formed by prepreg, SMC sheets, carbon fiber braids or any combination of the three. Its traditional molding methods include HP-RTM molding method using soluble aluminum and air blowing molding method. Since these two methods can well guarantee the external dimensions and appearance of the product, they are currently the best molding methods for composite materials with hollow structures. HP-RTM molding method using soluble aluminum: irregular shaped aluminum alloy is used as the core material, with one or more layers of carbon fiber braid on the outside, and then put into the mold together, close the mold, inject resin under high pressure (pressure up to 20MPA), heat (generally 90℃) and harden the product after demolding. After the demolded product is heated at about 90℃, the aluminum alloy core material melts, and the melted aluminum alloy is removed to obtain a composite part with a hollow structure. Blow molding method: a closed plastic bag (usually made of PA, commonly known as nylon, which can withstand a high temperature of 240°C without deformation) is used, with one or more layers of prepreg, SMC sheet or any combination of the two on the outside, and then put into the mold together, close the mold, pressurize the air inside the plastic bag (usually 0.6MPA, because of the adverse safety factors to people and the environment, the gas cannot use a higher pressure), heat (usually 150°C) and harden the product after demoulding. After demoulding, the plastic bag inside the product is removed to obtain a composite material component with a hollow structure. This is the general practice of carbon fiber bicycle frames at present. Prepreg: Prepreg is a composite material made of resin matrix and reinforcement by impregnating continuous fibers or fabrics with a resin matrix under strictly controlled conditions. SMC sheet: The main raw materials are composed of glass fiber chopped yarn or carbon fiber chopped yarn, fillers and various additives.

[0003] Of the above two methods, the HP-RTM molding method using soluble aluminum has a good product appearance, and the product has high mechanical strength and rigidity. However, since the cost of its equipment and production lines is often more than 10 million, it is currently difficult to popularize and apply on a large scale. The air blowing molding method, on the other hand, has a poor product appearance, often accompanied by defects such as pinholes, dry yarn, and lack of glue, and often requires repairs, which consumes manpower and pollutes the environment. And because the air blowing molding method uses compressed air as the expansion medium, because gas is unsafe to people and the environment under high pressure, when using the air blowing molding method, the compressed air pressure is low, and the mechanical strength and rigidity are low, and its products are often not used in aviation, military and other fields. Therefore, there is an urgent need for a low-cost, high-quality, environmentally friendly molding method for hollow structure composite parts. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a method for forming a composite material component with a hollow structure, which has the characteristics of low cost and high mechanical strength and rigidity of the product, thereby overcoming the shortcomings of the above-mentioned prior art.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0006] A method for forming a composite material component with a hollow structure, the method comprising the following process steps:

[0007] S1. Place the carbon fiber layer into the mold;

[0008] S2, placing the inflatable bag into the carbon fiber layer;

[0009] S3. Close the mold and use a press to heat and pressurize the upper and lower surfaces of the mold at a temperature of 150°C and a pressure of ≥3MPA;

[0010] S4, inject the heat transfer oil into the blowing bag, and control the heat transfer oil pressure to 1MPA-3MPA;

[0011] S5. After the product is formed, take the product out of the mold;

[0012] S6. Remove the air bag inside the product;

[0013] S7. Grind, paint and polish the products.

[0014] As a preferred solution, the inflatable bag is made of PA material.

[0015] As a preferred solution, the carbon fiber layer is composed of prepreg or SMC sheet, or is composed of both prepreg and SMC sheet.

[0016] As a preferred solution, the mold is made of metal materials including 45#, P20, and 718H steel.

[0017] Beneficial effects of the present invention: Compared with the prior art, the present invention has the following advantages:

[0018] 1. Compared with the HP-RTM molding method using soluble aluminum, the equipment and production line of the present invention have lower cost and better economic benefits;

[0019] 2. Compared with the blowing molding method, the blowing bag of the present invention uses heat transfer oil instead of air as the expansion medium for pressurized molding. Since the liquid can use a higher pressure, it is more in line with the safety requirements for people and the environment. Therefore, the molding pressure inside the mold is higher, and the pressure can reach 20MPA. Not only does it have a better product appearance, it reduces the rework process, greatly reduces the dust and environmental pollution caused by repairs, and the product has higher mechanical strength and rigidity, making the product more applicable to aviation, military and other industries. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural principle diagram of the present invention.

[0021] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0022] Example 1: Figure 1 As shown, a method for forming a composite material component with a hollow structure includes the following process steps:

[0023] S1, placing the carbon fiber layer 2 into the mold 3;

[0024] S2, placing the blowing bag 1 into the carbon fiber layer 2;

[0025] S3, close the mold 3, and use a press to heat and pressurize the upper and lower surfaces of the mold 3, the temperature is 150°C, and the pressure is ≥3MPA;

[0026] S4, inject the heat transfer oil 4 (heat transfer oil temperature ≥ 150 ° C, pressure up to 20MPA) into the blowing bag 1, and control the heat transfer oil pressure to 1MPA-3MPA;

[0027] S5. Depending on the types of prepreg and SMC sheet in the carbon fiber layer 2, the molding time can be completed in 2 minutes at the fastest. After the product is molded, the product is taken out from the mold 3.

[0028] S6. Remove the air-blowing bag 1 inside the product;

[0029] S7. Grind, paint and polish the products.

[0030] The above-mentioned blowing bag 1 is made of PA material, commonly known as nylon, which can withstand temperatures of 240°C without deformation. The carbon fiber layer 2 is made of prepreg or SMC sheet, or both prepreg and SMC sheet. The mold 3 is made of metal materials including 45#, P20, and 718H steel. The heat transfer oil 4 is a special oil with good thermal stability used for indirect heat transfer. It is used as an expansion medium in this patent. It has the characteristics of uniform heating, accurate temperature control, and the ability to generate high temperature under low steam pressure. It also has good heat transfer effect, energy saving, and convenient transportation and operation.

[0031] The implementation manner of the present invention is not limited to the above-mentioned embodiments, and various changes made without departing from the spirit of the present invention are within the protection scope of the present invention.

Claims

1. A method for forming a composite material component with a hollow structure, characterized in that: The process includes the following steps: S1. placing a carbon fiber layer (2) into a mold (3); the carbon fiber layer (2) is composed of prepreg or SMC sheet, or both prepreg and SMC sheet; S2, placing the blowing bag (1) into the carbon fiber layer (2); the blowing bag (1) is made of PA material; S3, closing the mold (3), and using a press to heat and pressurize the upper and lower surfaces of the mold (3), the temperature being 150° C. and the pressure being ≥ 3 MPa; S4, injecting the heat transfer oil (4) into the blowing bag (1), and controlling the pressure of the heat transfer oil to be 1MPA-3MPA; S5, after the product is formed, the product is taken out from the mold (3); S6. Remove the air bag (1) inside the product; S7. Grind, paint and polish the products.

2. The method for forming a hollow structure composite material component according to claim 1, characterized in that: The mold (3) is made of metal materials including 45#, P20, and 718H steel.

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