A jig-free epoxy resin-based carbon fiber sheet forming method

Abstract

The present invention relates to a jig-free epoxy resin-based carbon fiber sheet forming method, comprising the following steps: preparing a forming device, the forming device comprising an upper template and a lower template, the lower surface of the upper template and the upper surface of the lower template forming a working surface; cutting the epoxy resin-based carbon fiber prepreg according to a set size, and laying it in a set manner, and after the laying is completed, setting an isolation film on its surface to obtain a preformed body; preheating the lower surface of the upper template and the upper surface of the lower template to a set preheating temperature, placing the preformed body directly on the upper surface of the lower template, and moving the upper template downward to a set position; curing the preformed body under set conditions to form an epoxy resin-based carbon fiber sheet. The present invention eliminates the need for a mold or a jig in the forming process of the epoxy resin-based carbon fiber sheet, greatly reduces the production cost, and can prevent defects such as pinholes from appearing on the surface of the formed sheet, improves the yield rate of the sheet, and has a simple process and improved production efficiency.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon fiber material molding, and in particular relates to a jig-free epoxy resin-based carbon fiber plate molding method. Background Art

[0002] Carbon fiber is a microcrystalline graphite material obtained by carbonizing and graphitizing organic fibers, and its microstructure is similar to artificial graphite. Epoxy resin-based carbon fiber sheet is one of the most important materials in the aerospace industry. Among them, carbon fiber plays a reinforcing role and bears most of the load, making the material show higher tensile strength and stiffness. The epoxy resin matrix and carbon fiber are connected together through the interface, and the matrix transfers the load to the fiber through the interface, which can not only give play to the excellent tensile properties of carbon fiber, but also play a role in evenly distributing the load and protecting the carbon fiber from external damage, which can better highlight the excellent properties of high modulus, high strength and low density of carbon fiber.

[0003] At present, in the process of epoxy resin-based carbon fiber sheet molding, it is necessary to set up molds or limit fixtures on the molding equipment for molding. However, high-precision molds and limit fixtures are not only extremely expensive, but also not conducive to the volatilization of small molecules of the material during the molding process, which may cause pinhole defects on the surface of the molded carbon fiber sheet, which is particularly obvious for thinner carbon fiber sheets. Therefore, the yield rate of carbon fiber sheets cannot be guaranteed during the production process, production efficiency is reduced, and production costs are increased. Summary of the invention

[0004] An object of the present invention is to provide a jig-free epoxy resin-based carbon fiber sheet forming method for solving the problems of high production cost and easy occurrence of pinhole defects in existing forming technologies.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A jig-free epoxy resin-based carbon fiber sheet forming method comprises the following steps:

[0007] S1: preparing a molding device, wherein the molding device comprises an upper template and a lower template, wherein the upper template is located above the lower template, and the lower surface of the upper template and the upper surface of the lower template form a working surface, and the working surface is a plane;

[0008] S2: cutting the epoxy resin-based carbon fiber prepreg according to a set size, laying it in a set manner, and setting an isolation film on its surface after laying to obtain a preform;

[0009] S3: preheating the lower surface of the upper template and the upper surface of the lower template to a set preheating temperature, placing the preform directly on the upper surface of the lower template, and moving the upper template downward to a set position;

[0010] S4: curing the preform under set conditions to form an epoxy resin-based carbon fiber sheet, and after the forming is completed, moving the upper template upward to take out the epoxy resin-based carbon fiber sheet.

[0011] Preferably, in S3, the set preheating temperature is 20%-80% of the glass transition temperature of the epoxy resin.

[0012] Preferably, in S3, the set position is a position where the lower surface of the upper template contacts the upper surface of the preform, and the upper template does not apply any pressure to the preform.

[0013] Preferably, in S4, the set conditions include a set time and a set temperature, the set time is 45 min-90 min, and the set temperature is 80°C-170°C.

[0014] Further preferably, in S2, the isolation film can withstand a temperature greater than or equal to 180°C.

[0015] Preferably, in S2, the setting method is to lay the layers in sequence according to the 0° / 90° directions.

[0016] Preferably, in S2, after the epoxy resin-based carbon fiber prepreg is laid in a set manner, an isolation film is laid on both the upper surface and the lower surface thereof.

[0017] Preferably, in S2, the set size is the size of the carbon fiber sheet to be formed.

[0018] Preferably, in S2, the components of the epoxy resin-based carbon fiber prepreg include epoxy resin and carbon fiber, and the content of the epoxy resin is 27-45wt%; the thickness of the epoxy resin-based carbon fiber prepreg is 0.1-0.6mm, and the thickness of the preform is 5-10mm.

[0019] Another object of the present invention is to provide an epoxy resin-based carbon fiber plate. To achieve the above object, the technical solution adopted by the present invention is:

[0020] An epoxy resin-based carbon fiber plate is prepared by the jig-free epoxy resin-based carbon fiber plate forming method.

[0021] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0022] The present invention preheats the molding equipment and moves the upper template of the molding equipment to a set position for molding, so that the epoxy resin-based carbon fiber board does not need to use a mold or a fixture during the molding process, which greatly reduces the production cost and can prevent defects such as pinholes from appearing on the surface of the board after molding, thereby improving the yield rate of the board. The process is simple, the operation is convenient, and the production efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Attached Figure 1 This is a schematic diagram of the appearance of the epoxy resin-based carbon fiber plate of the first embodiment;

[0024] Attached Figure 2 This is a schematic diagram of the appearance of the epoxy resin-based carbon fiber plate of the second embodiment;

[0025] Attached Figure 3 This is a schematic diagram of the appearance of the epoxy resin-based carbon fiber plate of this comparative example 1;

[0026] Attached Figure 4 This is a schematic diagram of the appearance of the epoxy resin-based carbon fiber plate of this comparative example 3;

[0027] Attached Figure 5 This is a schematic diagram of the appearance of the epoxy resin-based carbon fiber plate of Comparative Example 4;

[0028] Attached Figure 6 It is a structural schematic diagram of the molding equipment of the first embodiment;

[0029] Attached Figure 7 This is a schematic diagram of the structure of the molding equipment of comparative example 1.

[0030] In the above drawings: 1. upper template; 2. lower template; 3. preform; 4. fixture. DETAILED DESCRIPTION

[0031] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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.

[0032] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0033] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] An epoxy resin-based carbon fiber sheet is prepared by a jig-free epoxy resin-based carbon fiber sheet forming method. The jig-free epoxy resin-based carbon fiber sheet forming method specifically comprises the following steps:

[0035] S1:

[0036] Prepare a molding device, the molding device includes an upper template 1 and a lower template 2, such as Figure 6 As shown, the upper template 1 is located above the lower template 2, and the lower surface of the upper template 1 and the upper surface of the lower template 2 form a working surface, and the working surface is a plane.

[0037] S2:

[0038] Prepare epoxy resin-based carbon fiber prepreg, the epoxy resin-based carbon fiber prepreg comprises epoxy resin and carbon fiber, the content of epoxy resin is 27-45wt%, and the thickness of epoxy resin-based carbon fiber prepreg is 0.1-0.6mm;

[0039] Cutting the epoxy resin-based carbon fiber prepreg according to a set size, the set size being the size of the carbon fiber sheet to be formed;

[0040] Lay the epoxy resin-based carbon fiber prepreg in a set manner, and the set manner is to lay the layers in sequence in the 0° / 90° direction;

[0041] After the epoxy resin-based carbon fiber prepreg is laid, an isolation film is laid on its upper and lower surfaces. The isolation film must be able to withstand a temperature greater than or equal to 180° C. After the laying is completed, a preform 3 is obtained, and the thickness of the preform 3 is 5-10 mm.

[0042] S3:

[0043] Preheat the lower surface of the upper template 1 and the upper surface of the lower template 2 to a set preheating temperature, wherein the set preheating temperature is 20%-80% of the glass transition temperature of the epoxy resin;

[0044] The preform 3 is placed directly on the upper surface of the lower template 2 without using a mold or a fixture, and the upper template 1 is moved downward to a set position, where the set position is the position where the lower surface of the upper template 1 contacts the upper surface of the preform 3, and the upper template 1 does not apply any pressure to the preform 3.

[0045] S4:

[0046] The preform 3 is cured and formed into an epoxy resin-based carbon fiber plate under set conditions, wherein the set conditions include a set time and a set temperature, wherein the set time is 45 min-90 min and the set temperature is 80° C.-170° C.;

[0047] After the molding is completed, the upper mold plate 1 is moved upward to take out the epoxy resin-based carbon fiber sheet.

[0048] Embodiment 1:

[0049] The size of the epoxy resin-based carbon fiber sheet to be formed is 560 mm×560 mm and the thickness is 8 mm. A jig-free epoxy resin-based carbon fiber sheet forming method is used for forming the sheet, which specifically includes the following steps:

[0050] S1: Prepare the molding equipment, which includes an upper mold plate 1 and a lower mold plate 2, such as Figure 6 As shown, the upper template 1 is located above the lower template 2, and the lower surface of the upper template 1 and the upper surface of the lower template 2 form a working surface, and the working surface is a plane;

[0051] S2: preparing epoxy resin-based carbon fiber prepreg, the epoxy resin-based carbon fiber prepreg adopts 200 grams of prepreg; cutting the epoxy resin-based carbon fiber prepreg according to the size of the epoxy resin-based carbon fiber sheet to be formed, and laying the layers in 0° / 90° direction, laying 40 layers in total, laying isolation films on the upper and lower surfaces thereof after laying, and obtaining a preform 3 after completion;

[0052] S3: preheating the lower surface of the upper template 1 and the upper surface of the lower template 2 to 150° C., placing the preform 3 directly on the upper surface of the lower template 2 without using a mold or a fixture, and moving the upper template 1 downward to a position where the lower surface of the upper template 1 contacts the upper surface of the preform 3, and the upper template 1 does not apply any pressure to the preform 3;

[0053] S4: Under the conditions of a set time of 40 minutes and a set temperature of 150° C., the preform 3 is cured to form an epoxy resin-based carbon fiber sheet. After the forming is completed, the upper template 1 is moved upward to take out the epoxy resin-based carbon fiber sheet. Figure 1 As shown, the surface quality of the carbon fiber sheet is high, and there are no defects such as pinholes.

[0054] Embodiment 2:

[0055] The size of the epoxy resin-based carbon fiber sheet to be formed is 560 mm×600 mm and the thickness is 10 mm. A jig-free epoxy resin-based carbon fiber sheet forming method is used for forming the sheet, which specifically includes the following steps:

[0056] S1: Prepare the molding equipment, which includes an upper mold plate 1 and a lower mold plate 2, such as Figure 6 As shown, the upper template 1 is located above the lower template 2, and the lower surface of the upper template 1 and the upper surface of the lower template 2 form a working surface, and the working surface is a plane;

[0057] S2: preparing epoxy resin-based carbon fiber prepreg, the epoxy resin-based carbon fiber prepreg adopts 200 grams of prepreg; cutting the epoxy resin-based carbon fiber prepreg according to the size of the epoxy resin-based carbon fiber sheet to be formed, and laying the layers in sequence in the 0° / 90° direction, laying 50 layers in total, laying isolation films on the upper and lower surfaces thereof after the laying is completed, and obtaining a preform 3 after the completion;

[0058] S3: preheating the lower surface of the upper template 1 and the upper surface of the lower template 2 to 150° C., placing the preform 3 directly on the upper surface of the lower template 2 without using a mold or a fixture, and moving the upper template 1 downward to a position where the lower surface of the upper template 1 contacts the upper surface of the preform 3, and the upper template 1 does not apply any pressure to the preform 3;

[0059] S4: Under the conditions of a set time of 45 minutes and a set temperature of 150° C., the preform 3 is cured to form an epoxy resin-based carbon fiber sheet. After the forming is completed, the upper template 1 is moved upward to take out the epoxy resin-based carbon fiber sheet. Figure 2 As shown, the surface quality of the carbon fiber sheet is high, and there are no defects such as pinholes.

[0060] Comparative Example 1:

[0061] The size of the epoxy resin-based carbon fiber sheet to be formed is 560 mm × 560 mm, and the thickness is 8 mm. The conventional epoxy resin-based carbon fiber sheet forming method is used for forming, that is, a jig is used in the forming process, which specifically includes the following steps:

[0062] S1: Prepare the molding equipment, which includes an upper mold plate 1, a lower mold plate 2 and a fixture 4, such as Figure 7 As shown, the upper template 1 is located above the lower template 2, and the fixture 4 is arranged on the lower template 2;

[0063] S2: preparing epoxy resin-based carbon fiber prepreg, the epoxy resin-based carbon fiber prepreg adopts 200 grams of prepreg; cutting the epoxy resin-based carbon fiber prepreg according to the size of the epoxy resin-based carbon fiber sheet to be formed, and laying the layers in 0° / 90° direction, laying 40 layers in total, laying isolation films on the upper and lower surfaces thereof after laying, and obtaining a preform 3 after completion;

[0064] S3: The preform 3 is placed in the fixture 4, and the upper template 1 is moved downward to press the preform 3. Under the conditions of a set pressure of 100 kgf, a set time of 40 min, and a set temperature of 150 ° C, the preform 3 is cured to form an epoxy resin-based carbon fiber sheet. After the molding is completed, the upper template 1 is moved upward to take out the epoxy resin-based carbon fiber sheet. Figure 3 As shown, pinhole defects appear on the surface of the carbon fiber sheet.

[0065] Comparative Example 2:

[0066] The size of the epoxy resin-based carbon fiber sheet to be formed is 560 mm×560 mm and the thickness is 8 mm. A jig-free epoxy resin-based carbon fiber sheet forming method is used for forming. However, during the forming process, the preheating temperature is set to be lower than 20% of the glass transition temperature of the epoxy resin. Specifically, the following steps are included:

[0067] S1: Prepare the molding equipment, which includes an upper mold plate 1 and a lower mold plate 2, such as Figure 6 As shown, the upper template 1 is located above the lower template 2, and the lower surface of the upper template 1 and the upper surface of the lower template 2 form a working surface, and the working surface is a plane;

[0068] S2: preparing epoxy resin-based carbon fiber prepreg, the epoxy resin-based carbon fiber prepreg adopts 200 grams of prepreg; cutting the epoxy resin-based carbon fiber prepreg according to the size of the epoxy resin-based carbon fiber sheet to be formed, and laying the layers in 0° / 90° direction, laying 40 layers in total, laying isolation films on the upper and lower surfaces thereof after laying, and obtaining a preform 3 after completion;

[0069] S3: preheating the lower surface of the upper template 1 and the upper surface of the lower template 2 to 90° C., placing the preform 3 directly on the upper surface of the lower template 2 without using a mold or a fixture, and moving the upper template 1 downward to a position where the lower surface of the upper template 1 contacts the upper surface of the preform 3, and the upper template 1 does not apply any pressure to the preform 3;

[0070] S4: Waiting for the preform 3 to solidify under the conditions of a set time of 45 minutes and a set temperature of 90° C., and moving the upper template 1 upward after the set conditions are met. However, due to the low temperature, the preform 3 cannot be formed into a plate.

[0071] Comparative Example 3:

[0072] The size of the epoxy resin-based carbon fiber sheet to be formed is 560 mm×560 mm and the thickness is 8 mm. A jig-free epoxy resin-based carbon fiber sheet forming method is used for forming. However, during the forming process, the preheating temperature is set to be higher than 80% of the glass transition temperature of the epoxy resin. Specifically, the following steps are included:

[0073] S1: Prepare the molding equipment, which includes an upper mold plate 1 and a lower mold plate 2, such as Figure 6 As shown, the upper template 1 is located above the lower template 2, and the lower surface of the upper template 1 and the upper surface of the lower template 2 form a working surface, and the working surface is a plane;

[0074] S2: preparing epoxy resin-based carbon fiber prepreg, the epoxy resin-based carbon fiber prepreg adopts 200 grams of prepreg; cutting the epoxy resin-based carbon fiber prepreg according to the size of the epoxy resin-based carbon fiber sheet to be formed, and laying the layers in 0° / 90° direction, laying 40 layers in total, laying isolation films on the upper and lower surfaces thereof after laying, and obtaining a preform 3 after completion;

[0075] S3: preheating the lower surface of the upper template 1 and the upper surface of the lower template 2 to 170° C., placing the preform 3 directly on the upper surface of the lower template 2 without using a mold or a fixture, and moving the upper template 1 downward to a position where the lower surface of the upper template 1 contacts the upper surface of the preform 3, and the upper template 1 does not apply any pressure to the preform 3;

[0076] S4: Under the conditions of a set time of 45 minutes and a set temperature of 170° C., the preform 3 is cured to form an epoxy resin-based carbon fiber sheet. After the forming is completed, the upper template 1 is moved upward to take out the epoxy resin-based carbon fiber sheet. Figure 4 As shown, defects appeared on the surface of the carbon fiber sheet.

[0077] Comparative Example 4:

[0078] The size of the epoxy resin-based carbon fiber sheet to be formed is 560 mm×560 mm and the thickness is 8 mm. A jig-free epoxy resin-based carbon fiber sheet forming method is used for forming. However, during the forming process, the upper template 1 does not move to the set position. Specifically, the following steps are included:

[0079] S1: Prepare the molding equipment, which includes an upper mold plate 1 and a lower mold plate 2, such as Figure 6As shown, the upper template 1 is located above the lower template 2, and the lower surface of the upper template 1 and the upper surface of the lower template 2 form a working surface, and the working surface is a plane;

[0080] S2: preparing epoxy resin-based carbon fiber prepreg, the epoxy resin-based carbon fiber prepreg adopts 200 grams of prepreg; cutting the epoxy resin-based carbon fiber prepreg according to the size of the epoxy resin-based carbon fiber sheet to be formed, and laying the layers in 0° / 90° direction, laying 40 layers in total, laying isolation films on the upper and lower surfaces thereof after laying, and obtaining a preform 3 after completion;

[0081] S3: preheat the lower surface of the upper template 1 and the upper surface of the lower template 2 to 150°C, place the preform 3 directly on the upper surface of the lower template 2 without using a mold or a fixture, and move the upper template 1 downward, and the lower surface of the upper template 1 presses the upper surface of the preform 3, that is, the pressure is 50kgf;

[0082] S4: Under the conditions of a set time of 45 minutes and a set temperature of 150° C., the preform 3 is cured to form an epoxy resin-based carbon fiber sheet. After the forming is completed, the upper template 1 is moved upward to take out the epoxy resin-based carbon fiber sheet. Figure 5 As shown, there are random grain defects on the surface of the carbon fiber sheet.

[0083] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A jig-free epoxy resin-based carbon fiber sheet forming method, characterized in that: It consists of the following steps: S1: preparing a molding device, wherein the molding device comprises an upper template and a lower template, wherein the upper template is located above the lower template, and the lower surface of the upper template and the upper surface of the lower template form a working surface, and the working surface is a plane; S2: cutting the epoxy resin-based carbon fiber prepreg according to the set size, the set size is the size of the carbon fiber plate to be formed, the components of the epoxy resin-based carbon fiber prepreg include epoxy resin and carbon fiber, the content of the epoxy resin is 27-45wt%; the thickness of the epoxy resin-based carbon fiber prepreg is 0.1-0.6mm, and it is laid according to the set method, the set method is to lay the layers in the 0° / 90° direction in sequence, and after the laying is completed, an isolation film is set on the upper and lower surfaces thereof, the isolation film can withstand a temperature greater than or equal to 180°C, and a preform is obtained, and the thickness of the preform is 5-10mm; S3: preheating the lower surface of the upper template and the upper surface of the lower template to a set preheating temperature, wherein the set preheating temperature is 20%-80% of the glass transition temperature of the epoxy resin, placing the preform directly on the upper surface of the lower template, and moving the upper template downward to a set position, wherein the set position is a position where the lower surface of the upper template contacts the upper surface of the preform, and the upper template does not apply any pressure to the preform; S4: Curing the preform into an epoxy resin-based carbon fiber sheet under set conditions, wherein the set conditions include a set time and a set temperature, wherein the set time is 45 min-90 min, and the set temperature is 80°C-170°C. After the molding is completed, the upper mold plate is moved upward and the epoxy resin-based carbon fiber sheet is taken out.

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