Thick composite flange forming process technical method

Abstract

The invention discloses a thicker composite flange forming process technical method in the technical field of low-temperature wind tunnel compressors, which comprises the following steps of: (1) designing, cutting and blanking carbon fiber reinforced epoxy prepreg according to the requirements of a design drawing; (2) paving prepreg in the flange forming mold according to the designed paving requirements; (3) a vacuum device is arranged on the flange forming mold, and the flange forming mold is put into an autoclave to be pre-pressed; (4) arranging a final curing vacuum device on the flange forming mold, and putting the flange forming mold into an autoclave for final curing; the thicker area of the thicker composite flange prepared by using the method does not have layering and air holes.

Description

Technical Field

[0001] The invention belongs to the technical field of composite material forming, and in particular relates to a process technology method for forming a thicker composite flange. Background Art

[0002] In the prior art, prepreg layers are used, and after the paving is completed, a molding and full curing method is used to form the composite flange. This method has certain curing stratification defects when used for joint flanges with a thickness of more than 50 mm. During the curing process of the molding process, the mold relies on the upper and lower heating modules for heat transfer. When the thickness of the joint flange is thicker, it takes a certain amount of time for the joint to transfer heat to the middle part. During this period, the prepreg close to the heating module remains in a high temperature state for a long time, and the temperature difference between the middle and the upper and lower parts of the product is large, resulting in premature cross-linking reaction near the heating module and late reaction in the middle part, resulting in stratification, porosity and other defects at the junction of the front and rear reaction areas inside the product. Summary of the invention

[0003] In view of the defects in the prior art, the purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art, solve the technical problems existing in the molding of composite flanges in the prior art, and provide a thicker composite flange molding process technology method. The thicker area of ​​the thicker composite flange prepared by the present invention will not have delamination and pores.

[0004] The object of the present invention is achieved by: a thick composite flange forming process technology method, comprising the following steps: (1) Use carbon fiber reinforced epoxy prepreg to design and cut materials according to the requirements of the design drawings; (2) Laying the prepreg in the flange forming mold according to the designed laying requirements to achieve laying of the molded preform; (3) Arrange a vacuum device on the flange forming mold and put it into the autoclave for pre-pressing; (4) Arrange a final curing vacuum device on the flange forming mold and place it in an autoclave for final curing.

[0005] As a preferred solution of the thicker composite flange forming process technology method in the present invention, wherein: the flange forming mold includes a first annular paving support mold body, the upper side of the first paving support mold body is a plane, the upper side of the first paving support mold body is fixedly connected to the second paving support mold body, the lower part of the second paving support mold body is provided with a circular through hole, the center of the first paving support mold body is connected to the middle mold body, the circular through hole and the outer periphery of the middle mold body form a first annular paving hole, the second paving support mold body on the upper side of the first paving hole is provided with a second paving hole, the outer diameter of the second paving hole gradually increases from bottom to top, the upper sides of the first lower mold body and the middle mold body are flush, and the upper sides of the second paving support mold body and the middle mold body are detachably connected to the upper mold body.

[0006] As a preferred solution of the thicker composite flange forming process technology method of the present invention, wherein: in the step (2), the specific steps of paving are: (201) Laying a layer of prepreg on the first paving support mold body at the first paving hole, flanging to the outer periphery of the middle mold body, arranging a vacuum bag, and vacuuming the first layer of prepreg to compact the corners of the first paving support mold body and the second lower mold body; (202) According to the first laying design, prepreg is laid on the first laying support mold body at the first laying hole, and the flange is turned to the outer periphery of the intermediate mold body. The bottom after laying is the first bottom layer, and the flanged part is the first side cladding layer; (203) Laying a layer of prepreg on the upper side of the bottom layer, turning the edge to the inner edge of the second paving support mold body, arranging a vacuum bag, and applying vacuum to compact the prepreg layer and the corner of the second paving support mold body; (204) According to the second layer design, the prepreg is laid at the first laying hole, and the edge is turned to the inner edge of the second laying support mold body. The laid bottom is the second bottom layer, and the laid side is the first side cladding layer; (205) According to the layer design three, the prepreg is laid on the bottom layer two, and the edge is turned to the side cladding layer one. The bottom after laying is the bottom layer three, and the side after laying is the side cladding layer two; (206) According to the ply design four, prepreg is laid on the bottom layer three, and the edge is turned to the first side cladding layer. The bottom after laying is the bottom layer four, and the side after laying is the second side cladding layer. (207) placing the preformed preformed flat layer into the product; (208) Folding the second side cladding layer to the upper side of the flat layer, and flanging the second side cladding layer to the upper side of the flat layer, and lap the layers one by one on the flat layer during the flanging process; (209) Folding the side cover layer 1 to the upper side of the side cover layer 2 and the second side cover layer on the flat layer, and laying a layer of material sheet on the flanging each time a layer is turned over; In each of the above ply designs, after laying four layers, vacuum bags are arranged and vacuum compacted for a set time.

[0007] As a preferred scheme of the thicker composite flange forming process technology method in the present invention, in which: in the layup design one, the layup angles are [45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°].

[0008] As a preferred scheme of the thicker composite flange forming process technology method in the present invention, wherein: in the layup design two, cyclic symmetrical layup is carried out, and the layup angles are [0, 45, 0, 0, -45, 90, -45, 0, 0, 45, 0, 0, 90, 0, 0, 90, 0, 0, 45, 0, -45] s, where s is the stacking multiple.

[0009] As a preferred solution of the thicker composite flange forming process technology method in the present invention, in which: in step S309, a total of 8 layers of material are laid during flanging, and the laying angles are [45, 0, 45, 0, 0, 45, 0, 45] respectively. Before laying the first layer of material, a 1 mm thick aluminum sheet is wrapped at the tip of the prepreg.

[0010] As a preferred solution of the thick composite flange forming process technology method of the present invention, wherein: in step (3), the curing process is specifically as follows: (301) Make the heating plate on the press fit the mold and set the heating temperature to 80±5°C, and record the curing start time; (302) Normal temperature -100±5℃, heating rate 20℃ / h, pressurize to 5 tons when the temperature reaches 70±5℃, continue to heat up after pressurization, pressurize to 10 tons 75 minutes after the temperature reaches 100±5℃, check the mold clearance after pressurization, and check the mold clearance every 15 minutes; After 105 minutes, pressurize to 20 tons, check the mold clearance after pressurization, and check the mold clearance every 15 minutes; Keep at 100±5℃ for 120min and then pressurize to 30 tons. Check the mold clearance after pressurization and check the mold clearance every 15min. Keep at 100±5℃ for 135min and then pressurize to 30 tons. Check the mold clearance after pressurization and check the mold clearance every 15min. Keep at 100±5℃ for 135min and then pressurize to 40 tons. Check the mold clearance after pressurization and check the mold clearance every 15min. Keep at 100±5℃ for 135min, then pressurize to 50 tons. Check the mold clearance after pressurization. Check the mold clearance every 15min. Keep at 100±5℃ for 6h in total. (303) 100±5℃-120±5℃, heating rate 20℃ / h, 120±5℃ for 3h, holding pressure 50 tons; (304) 120±5℃-50±5℃, set temperature to cool down, set temperature to decrease by 5℃ every hour, when the thermocouple temperature is lower than 50±5℃, the press pressure can be released.

[0011] As a preferred solution of the thicker composite flange forming process technology method in the present invention, wherein: after the pre-formed flat layer is laid, it is pre-pressed. The pre-pressing process of the pre-formed flat layer is specifically as follows: pressurizing at room temperature, pressurizing to 0.5MPa at a rate of 0.02MPa / min, heating at room temperature, and the heating rate is 1℃ / min; the medium temperature is set to 95℃, and when the slowest heating thermocouple is heated to 90℃, it is kept warm for 3h; after keeping warm for 3h, it is cooled at a rate of no more than 1℃ / min, and when the temperature of the slowest cooling thermocouple drops below 50℃, the pressure is released, and after the pressure release is completed, the can is opened.

[0012] As a preferred solution of the thicker composite flange forming process technology method of the present invention, wherein: in the step (4), the process of arranging the final vacuum device is specifically as follows: Place a non-porous isolation film, a round plate, a breathable felt, and a vacuum bag film on the upper surface of the flange forming mold in sequence, and place vacuum nozzles at the four corners of the flat mold. There are 6 to 8 vacuum nozzles, and the vacuum nozzles must not leak. Package the vacuum bag, perform a vacuum leak check, turn off the vacuum source for 10 minutes, and manually detect that the vacuum degree does not drop by more than 0.005MPa; place the thermocouple, and use a medium-temperature sealing strip to seal the thermocouple along the edge of the sealing strip of the packaging bag, and cover it with excess packaging vacuum bag film to fix the position of the sealing strip to prevent the sealing strip from being heated and the thermocouple from shifting; then lay 2 layers of breathable felt on the high-temperature bag film above the thermocouple and fix it with a demoulding cloth strip; connect to the vacuum system, apply a vacuum pressure below -0.092MPa, and apply an air pressure of 0.5MPa, and maintain it for at least 15 minutes without leakage.

[0013] As a preferred solution of the thick composite flange forming process technology method of the present invention, wherein: in step (4), the final curing process is specifically as follows: (401) Pressurize at room temperature at a rate of 0.02 MPa / min to 0.5 MPa, and heat at room temperature at a rate of 0.2 °C / min; (402) The medium temperature is set to 95°C. When the slowest heating thermocouple reaches 90°C, keep it warm for 3 hours. (403) The medium temperature is set to 125°C. When the slowest heating thermocouple is heated to 125°C, it is kept warm for 3 hours. (404) The medium temperature is set to 165°C. When the slowest heating thermocouple is heated to 165°C, it is kept warm for 3 hours. (405) The medium temperature is set to 190℃. When the slowest heating thermocouple is heated to 180℃, it is kept warm for 3 hours and then cooled at a rate of no more than 0.1℃ / min. When the slowest cooling thermocouple temperature drops below 50℃, the pressure is released. After the pressure is released, the tank can be opened.

[0014] Compared with the prior art, the use of the present invention solves the problem of stratification and air holes in the thickest area of ​​the flange in the prior art. The higher the pressure resistance requirement of the pressure container, the higher the lossless quality requirement of the joint flange. Due to the improvement of the pressure resistance level, the flange thickness also needs to be increased. The thicker the thickness, the more difficult the process forming is, and the more difficult it is to solve the problem of temperature uniformity in the traditional molding process. The present invention utilizes the combination of the molding process and the hot pressing process, and prepares a flange that will not be stratified through the combination of special curing parameters, the hemming process and the aluminum hemming process. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The three-dimensional structure after the upper mold body is hidden in the present invention Figure 1 .

[0016] Figure 2 The three-dimensional structure after the upper mold body is hidden in the present invention Figure 2 .

[0017] Figure 3 This is a top view after the upper mold body is hidden in the present invention.

[0018] Figure 4 for Figure 3 The view from AA in the middle.

[0019] Figure 5 It is a three-dimensional structural diagram of the flange forming mold in the present invention.

[0020] Figure 6 It is a schematic diagram of the paving structure of the flange joint of the present invention.

[0021] Figure 7 This is a directional view of a flange prepared using the present invention.

[0022] Figure 8 This is the curing system of the preformed ply in the present invention.

[0023] Fig. 9 It is a top view of the preforming mold in the present invention.

[0024] Fig.10 for Figure 8 The view from the center BB.

[0025] Among them, 100 flange forming mold, 101 middle mold body, 102 upper mold body, 103 second paving support mold body, 104 first paving support mold body, 200 flange, 300 bottom layer three, 400 bottom layer one, 500 bottom layer two, 600 first side cladding, 700 second side cladding, 800 side cladding two, 900 side cladding one, 1000 bottom layer four, 2000 preforming mold, 2001 lower preforming mold body, 2001a preforming sink, 2002 upper preforming mold body, X first paving hole, S second paving hole. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Example 1 Reference Figure 1 to Figure 5 , Figure 8 and Fig. 9 , which is the first embodiment of the present invention, and this embodiment provides a relatively thick composite flange forming process technology method, comprising the following steps: (1) Use carbon fiber reinforced epoxy prepreg to cut and cut materials according to the design drawings and prepare 1 mm thick aluminum sheets; (2) Laying the prepreg in the flange forming mold according to the designed laying requirements to achieve laying of the molded preform; (3) Place the flange forming mold into a press for molding and curing. After curing, remove the flange forming mold; (4) Use 80-grit sandpaper to roughen the surface, clean it with ethyl acetate after polishing, check it and put it into the oven, and dry it at 60°C for 6 hours; (5) Lay the prepreg layers according to the designed layup angle; (6) Arrange a vacuum device on the flange forming mold, cover and fix the upper mold body, and put it into the autoclave for pre-pressing; (7) Arrange a final curing vacuum device on the flange forming mold and place it in an autoclave for final curing.

[0028] Specifically, the flange forming mold includes a first annular paving support mold body, the upper side of the first paving support mold body is a plane, the upper side of the first paving support mold body is fixedly connected to the second paving support mold body, the lower part of the second paving support mold body is provided with a circular through hole, the center of the first paving support mold body is connected to the middle mold body, the circular through hole and the outer periphery of the middle mold body form a first annular paving hole, the second paving support mold body on the upper side of the first paving hole is provided with a second paving hole, the outer diameter of the second paving hole gradually increases from bottom to top, the upper sides of the first lower mold body and the middle mold body are flush, and the upper sides of the second paving support mold body and the middle mold body are detachably connected with the upper mold body.

[0029] In step (3), the specific steps of paving are: (301) Laying a layer of prepreg on the first paving support mold body at the first paving hole, flanging to the outer periphery of the middle mold body, arranging a vacuum bag, and vacuuming the first layer of prepreg so that the corners of the first paving support mold body and the second lower mold body are compacted; (302) According to the first laying design, prepreg is laid on the first laying support mold body at the first laying hole, and the flange is turned to the outer periphery of the intermediate mold body. The bottom after laying is the first bottom layer, and the flanged part is the first side cladding layer; (303) Laying a layer of prepreg on the upper side of the bottom layer, turning the edge to the inner edge of the second paving support mold body, arranging a vacuum bag, and evacuating the vacuum bag to compact the prepreg layer and the corner of the second paving support mold body; (304) According to the second layer design, the prepreg is laid at the first laying hole, and the edge is turned to the inner edge of the second laying support mold body. The laid bottom is the second bottom layer, and the laid side is the first side cladding layer; (305) According to the layer design three, the prepreg is laid on the bottom layer two, and the edge is turned to the side cladding layer one. The bottom after laying is the bottom layer three, and the side after laying is the side cladding layer two; (306) According to the layup design four, the prepreg is laid on the bottom layer three, and the edge is turned to the first side cladding layer. The bottom after laying is the bottom layer four, and the side after laying is the second side cladding layer. (307) The surface of the preformed flat layer is polished and cleaned with anhydrous ethanol, and then dried in an oven at 70°C for 2h. After drying, a layer of adhesive film with the same resin system is laid on the polished area, and the preformed flat layer is bagged and compacted. The preformed flat layer is placed in the product, and the bottom of the preformed flat layer contacts the four upper sides of the bottom layer, and is placed based on the inner ring. After placement, the surface gap area is filled with carbon wire, and then bagged and compacted; (308) Folding the second side cladding layer to the upper side of the flat layer, and flanging the second side cladding layer to the upper side of the flat layer, and lap the layers one by one on the flat layer during flanging; (309) Folding the side cover layer 1 to the upper side of the side cover layer 2 and the second side cover layer on the flat layer, and laying a layer of material sheet on the flanging each time a layer is turned over; In the above layer designs, every four layers are laid, vacuum bags are arranged, and vacuum compaction is carried out for 15 minutes. The preformed flat layer is preformed, and the forming process of the preformed flat layer is: a) Prepreg laying According to the marking order of the prepreg sheets, combined with the sheet laying order in the process flow card and process specification, and the direction of the mold coordinate system, the sheets are laid in the preforming sink of the preforming mold (the preforming mold includes a lower preforming mold body, and the upper end of the lower preforming mold body has a preforming sink). Except for the vacuum compaction for 15 minutes after the first layer is laid, the vacuum compaction is carried out for 15 minutes every 4 layers. When the laying is 1 / 3, stop laying, pack and compact; b) Encapsulation Place the peeling cloth, non-porous isolation film, breathable felt, vacuum nozzle, vacuum bag film on the laid blank in sequence, and seal the vacuum bag. After passing the air tightness test, proceed to the next process; c) Cold press pre-curing The mold is transferred to the autoclave. After the leak test is qualified, the autoclave operation parameters are set according to the curing parameters specified in the process documents to complete the curing of the parts. The autoclave curing parameters are: Pressurize at room temperature, pressurize to 0.5MPa at a rate of 0.02MPa / min, heat at room temperature at a rate of 1℃ / min; set the medium temperature to 95℃, and keep warm for 3h after the slowest thermocouple is heated to 90℃. After keeping warm for 3h, cool at a rate of no more than 1℃ / min, and release the pressure when the slowest thermocouple drops below 50℃. After the pressure release is completed, open the can.

[0030] d) Prepreg laying According to the marking order of the prepreg sheets, combined with the sheet laying order in the process flow card and process specifications, and the direction of the mold coordinate system, the sheets are laid. In addition to vacuuming and compacting for 15 minutes after the first layer is laid, vacuuming and compacting for 15 minutes every 4 layers are laid. When 2 / 3 of the sheets are laid, stop laying, pack and compact; e) Packaging Place the peeling cloth, non-porous isolation film, breathable felt, vacuum nozzle, vacuum bag film on the laid blank in sequence, seal the vacuum bag, and after passing the air tightness test, proceed to the next process; f) Cold press pre-curing The mold is transferred to the autoclave. After the leak test is qualified, the autoclave operation parameters are set according to the curing parameters specified in the process documents to complete the curing of the parts. The autoclave curing parameters are: Pressurize at room temperature, pressurize to 0.5MPa at a rate of 0.02MPa / min, heat at room temperature at a rate of 1℃ / min; set the medium temperature to 95℃, and keep warm for 3h after the slowest thermocouple is heated to 90℃. After keeping warm for 3h, cool at a rate of no more than 1℃ / min, and release the pressure when the slowest thermocouple drops below 50℃. After the pressure release is completed, open the can.

[0031] g) Prepreg laying Lay the prepreg sheets in the order of sheet marking, combined with the process flow card, sheet laying order in the process regulations, and the direction of the mold coordinate system. After the first layer is laid, vacuum and compact for 15 minutes. After that, vacuum and compact for 15 minutes every 4 layers. After laying to the last layer, bag it and compact it. After laying is completed, place the upper preformed mold body on the paving surface.

[0032] h) Curing The product was cured on a hot press at 70°C for 2 h, 130°C for 1 h, 160°C for 3 h, and 180°C for 1.5 h. The curing system was as follows: Figure 8 As shown; i) After cooling to room temperature, open the upper mold and take out the preformed laminate.

[0033] In layup design one, the layup angles are [45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°]; in layup design two, cyclic symmetrical layup is carried out and the layup angles are [0, 45, 0, 0, -45, 90, -45, 0, 0, 45, 0, 0, 90, 0, 0, 90, 0, 0, 45, 0, -45]s, where s is the stacking multiple.

[0034] Locate the ply origin at the first ply sheet and establish a coordinate system through the origin, with 90° toward the inner circle of the joint and 0° in the right-hand vertical direction.

[0035] In step S309, a total of 8 layers of material are laid during flanging, and the laying angles are [45, 0, 45, 0, 0, 45, 0, 45] respectively. Before laying the first layer of material, a 1 mm thick aluminum sheet is wrapped at the tip of the prepreg.

[0036] This design can offset the stress of the joint's heating, curing, cooling and shrinkage. Because carbon fiber has a smaller thermal expansion coefficient than mold steel and the thermal expansion is mismatched, the mold steel is prone to exert extrusion pressure on the joint's tip during the cooling process, causing the joint to delaminate. Aluminum sheets of appropriate thickness can offset a certain amount of stress and prevent delamination at the tip.

[0037] Example 2 This is the second embodiment of the present invention, which is different from the first embodiment in that it discloses a specific curing process, and the curing method of this embodiment can further prepare a joint flange with high strength.

[0038] In step (3), the curing process is specifically as follows: (301) Make the heating plate on the press fit the mold and set the heating temperature to 80±5°C, and record the curing start time; (302) Normal temperature -100±5℃, heating rate 20℃ / h, pressurize to 5 tons when the temperature reaches 70±5℃, continue to heat up after pressurization, pressurize to 10 tons 75 minutes after the temperature reaches 100±5℃, check the mold clearance after pressurization, and check the mold clearance every 15 minutes; After 105 minutes, pressurize to 20 tons, check the mold clearance after pressurization, and check the mold clearance every 15 minutes; Keep at 100±5℃ for 120min and then pressurize to 30 tons. Check the mold clearance after pressurization and check the mold clearance every 15min. Keep at 100±5℃ for 135min and then pressurize to 30 tons. Check the mold clearance after pressurization and check the mold clearance every 15min. Keep at 100±5℃ for 135min and then pressurize to 40 tons. Check the mold clearance after pressurization and check the mold clearance every 15min. Keep at 100±5℃ for 135min, then pressurize to 50 tons. Check the mold clearance after pressurization. Check the mold clearance every 15min. Keep at 100±5℃ for 6h in total. (303) 100±5℃-120±5℃, heating rate 20℃ / h, 120±5℃ for 3h, holding pressure 50 tons; (304) 120±5℃-50±5℃, set temperature to cool down, set temperature to decrease by 5℃ every hour, when the thermocouple temperature is lower than 50±5℃, the press pressure can be released.

[0039] In step (4), the process of arranging the final vacuum device is specifically as follows: Place a non-porous isolation film, a round plate, a breathable felt, and a vacuum bag film on the upper surface of the flange forming mold in sequence, and place vacuum nozzles at the four corners of the flat mold. There are 6 to 8 vacuum nozzles, and the vacuum nozzles must not leak. Package the vacuum bag, perform a vacuum leak check, turn off the vacuum source for 10 minutes, and manually detect that the vacuum degree does not drop by more than 0.005MPa; place the thermocouple, and use a medium-temperature sealing strip to seal the thermocouple along the edge of the sealing strip of the packaging bag, and cover it with excess packaging vacuum bag film to fix the position of the sealing strip to prevent the sealing strip from being heated and the thermocouple from shifting; then lay 2 layers of breathable felt on the high-temperature bag film above the thermocouple and fix it with a demoulding cloth strip; connect to the vacuum system, apply a vacuum pressure below -0.092MPa, and apply an air pressure of 0.5MPa, and maintain it for at least 15 minutes without leakage.

[0040] In step (4), the final curing process is specifically as follows: (401) Pressurize at room temperature at a rate of 0.02 MPa / min to 0.5 MPa, and heat at room temperature at a rate of 0.2 °C / min; (402) The medium temperature is set to 95°C. When the slowest heating thermocouple reaches 90°C, keep it warm for 3 hours. (403) The medium temperature is set to 125°C. When the slowest heating thermocouple is heated to 125°C, it is kept warm for 3 hours. (404) The medium temperature is set to 165°C. When the slowest heating thermocouple is heated to 165°C, it is kept warm for 3 hours. (405) The medium temperature is set to 190℃. When the slowest heating thermocouple is heated to 180℃, it is kept warm for 3 hours and then cooled at a rate of no more than 0.1℃ / min. When the slowest cooling thermocouple temperature drops below 50℃, the pressure is released. After the pressure is released, the tank can be opened.

[0041] The joint flange prepared by combining Example 2 and Example 1 can provide greater axial connection strength and shoulder compressive strength under working conditions.

[0042] Example 3 The following experiments are used to verify the technical effect of this application.

[0043] For the process design ply, water pressure burst test was carried out on the joint test pieces with the same appearance. The results are shown in the table below. The joint test pieces under the process design are obviously better than the previous two test pieces.

[0044] After the molded preform is laid, the process is tested according to the resin characteristics to confirm the appropriate preforming curing parameters and perform mold curing. The molded preform curing parameters are shown in the following table.

[0045] The test piece research shows that the resin system we selected has a low viscosity at 100~110℃, and the step pressure has a significant improvement in joint non-destructiveness. Two comparative tests were conducted on the curing process, and the comparison results are shown in the table above. The results show that the shape of the single layer of prepreg is relatively flat under the process step pressure, and there is no damage or abnormality, which can ensure that the carbon fiber strength is high and the product performance is more stable.

[0046] The present invention is not limited to the above-mentioned embodiments. On the basis of the technical solution disclosed in the present invention, technicians in this field can make some substitutions and deformations to some technical features therein according to the disclosed technical content without creative labor, and these substitutions and deformations are all within the protection scope of the present invention.

Claims

1. A thick composite flange forming process technology method, characterized in that: The following steps are included: (1) Use carbon fiber reinforced epoxy prepreg to design and cut materials according to the requirements of the design drawings; (2) Laying the prepreg in the flange forming mold according to the designed laying requirements to achieve the laying of the molded preform; (3) Arrange a vacuum device on the flange forming mold and put it into the autoclave for pre-pressing; (4) Arrange a final curing vacuum device on the flange forming mold and place it in an autoclave for final curing.

2. A thick composite flange forming process according to claim 1, characterized in that: The flange forming mold includes a first annular paving support mold body, the upper side of the first paving support mold body is a plane, the upper side of the first paving support mold body is fixedly connected to the second paving support mold body, the lower part of the second paving support mold body is provided with a circular through hole, the center of the first paving support mold body is connected to the middle mold body, the circular through hole and the outer periphery of the middle mold body form a first annular paving hole, the second paving support mold body on the upper side of the first paving hole is provided with a second paving hole, the outer diameter of the second paving hole gradually increases from bottom to top, the upper sides of the first lower mold body and the middle mold body are flush, and the upper sides of the second paving support mold body and the middle mold body are detachably connected to the upper mold body.

3. A thick composite flange forming process according to claim 2, characterized in that: In step (2), the specific steps of paving are: (201) Laying a layer of prepreg on the first paving support mold body at the first paving hole, flanging to the outer periphery of the middle mold body, arranging a vacuum bag, and vacuuming the first layer of prepreg to compact the corners of the first paving support mold body and the second lower mold body; (202) According to the first laying design, prepreg is laid on the first laying support mold body at the first laying hole, and the flange is turned to the outer periphery of the intermediate mold body. The bottom after laying is the first bottom layer, and the flanged part is the first side cladding layer; (203) Laying a layer of prepreg on the upper side of the bottom layer, turning the edge to the inner edge of the second paving support mold body, arranging a vacuum bag, and applying vacuum to compact the prepreg layer and the corner of the second paving support mold body; (204) According to the second layer design, the prepreg is laid at the first laying hole, and the edge is turned to the inner edge of the second laying support mold body. The laid bottom is the second bottom layer, and the laid side is the first side cladding layer; (205) According to the layer design three, the prepreg is laid on the bottom layer two, and the edge is turned to the side cladding layer one. The bottom after laying is the bottom layer three, and the side after laying is the side cladding layer two; (206) According to the ply design four, prepreg is laid on the bottom layer three, and the edge is turned to the first side cladding layer. The bottom after laying is the bottom layer four, and the side after laying is the second side cladding layer. (207) placing the preformed preformed flat layer into the product; (208) Folding the second side cladding layer to the upper side of the flat layer, and flanging the second side cladding layer to the upper side of the flat layer, and lap the layers one by one on the flat layer during the flanging process; (209) Folding the side cover layer 1 to the upper side of the side cover layer 2 and the second side cover layer on the flat layer, and laying a layer of material sheet on the flanging each time a layer is turned over; In each of the above ply designs, after laying four layers, vacuum bags are arranged and vacuum compacted for a set time.

4. A thick composite flange forming process according to claim 3, characterized in that: In ply design one, the ply angles are [45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°, 0°, 45°, 0°, 45°].

5. The thick composite flange forming process according to claim 3 is characterized in that: In the second layup design, cyclic symmetrical layup is carried out and the layup angles are [0, 45, 0, 0, -45, 90, -45, 0, 0, 45, 0, 0, 90, 0, 0, 90, 0, 0, 45, 0, -45] s, where s is the stacking multiple.

6. The thick composite flange forming process according to claim 3 is characterized in that: In step S309, a total of 8 layers of material are laid during flanging, and the laying angles are [45, 0, 45, 0, 0, 45, 0, 45] respectively. Before laying the first layer of material, a 1 mm thick aluminum sheet is wrapped at the tip of the prepreg.

7. The thick composite flange forming process according to claim 1 is characterized in that: In step (3), the curing process is specifically as follows: (301) Make the heating plate on the press fit the mold and set the heating temperature to 80±5°C, and record the curing start time; (302) Normal temperature -100±5℃, heating rate 20℃ / h, pressurize to 5 tons when the temperature reaches 70±5℃, continue to heat up after pressurization, pressurize to 10 tons 75 minutes after the temperature reaches 100±5℃, check the mold clearance after pressurization, and check the mold clearance every 15 minutes; After 105 minutes, pressurize to 20 tons, check the mold clearance after pressurization, and check the mold clearance every 15 minutes; Keep at 100±5℃ for 120min and then pressurize to 30 tons. Check the mold clearance after pressurization and check the mold clearance every 15min. Keep at 100±5℃ for 135min and then pressurize to 30 tons. Check the mold clearance after pressurization and check the mold clearance every 15min. Keep at 100±5℃ for 135min and then pressurize to 40 tons. Check the mold clearance after pressurization and check the mold clearance every 15min. Keep at 100±5℃ for 135min, then pressurize to 50 tons. Check the mold clearance after pressurization. Check the mold clearance every 15min. Keep at 100±5℃ for 6h in total. (303) 100±5℃-120±5℃, heating rate 20℃ / h, 120±5℃ for 3h, holding pressure 50 tons; (304) 120±5℃-50±5℃, set temperature to cool down, set temperature to decrease by 5℃ every hour, when the thermocouple temperature is lower than 50±5℃, the press pressure can be released.

8. A thick composite flange forming process according to any one of claims 1 to 6, characterized in that: After the preformed flat layer is laid, it is pre-pressed. The pre-pressing process of the preformed flat layer is as follows: pressurize at room temperature, pressurize to 0.5MPa at a rate of 0.02MPa / min, heat up at room temperature, and the heating rate is 1℃ / min; the medium temperature is set to 95℃, and when the slowest heating thermocouple is heated to 90℃, keep it warm for 3h; after keeping warm for 3h, cool it at a rate of no more than 1℃ / min, and when the temperature of the slowest thermocouple drops below 50℃, release the pressure. After the pressure release is completed, open the can.

9. A thick composite flange forming process according to any one of claims 1 to 6, characterized in that: In step (4), the process of arranging the final vacuum device is specifically as follows: Place a non-porous isolation film, a round plate, a breathable felt, and a vacuum bag film on the upper surface of the flange forming mold in sequence, and place vacuum nozzles at the four corners of the flat mold. There are 6 to 8 vacuum nozzles, and the vacuum nozzles must not leak. Package the vacuum bag, perform a vacuum leak check, turn off the vacuum source for 10 minutes, and manually detect that the vacuum degree does not drop by more than 0.005MPa; place the thermocouple, and use a medium-temperature sealing strip to seal the thermocouple along the edge of the sealing strip of the packaging bag, and cover it with excess packaging vacuum bag film to fix the position of the sealing strip to prevent the sealing strip from being heated and the thermocouple from shifting; then lay 2 layers of breathable felt on the high-temperature bag film above the thermocouple and fix it with a demoulding cloth strip; connect to the vacuum system, apply a vacuum pressure below -0.092MPa, and apply an air pressure of 0.5MPa, and maintain it for at least 15 minutes without leakage.

10. A thick composite flange forming process according to any one of claims 1 to 6, characterized in that: In step (4), the final curing process is specifically as follows: (801) Pressurize at room temperature at a rate of 0.02 MPa / min to 0.5 MPa, and heat at room temperature at a rate of 0.2 °C / min; (802) The medium temperature is set to 95°C. When the slowest heating thermocouple is heated to 90°C, keep it warm for 3 hours. (803) The medium temperature is set to 125°C. When the slowest heating thermocouple is heated to 125°C, it is kept warm for 3 hours. (804) The medium temperature is set to 165°C. When the slowest heating thermocouple is heated to 165°C, it is kept warm for 3 hours. (805) The medium temperature is set to 190℃. When the slowest heating thermocouple is heated to 180℃, it is kept warm for 3 hours and then cooled at a rate of no more than 0.1℃ / min. When the slowest cooling thermocouple temperature drops below 50℃, the pressure is released. After the pressure is released, the tank can be opened.

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