A process for forming a thick composite flange

Abstract

The application discloses a kind of relatively thick composite flange forming process technical method in the technical field of cryogenic wind tunnel compressor, comprising the following steps, (1) using carbon fiber reinforced epoxy prepreg according to design drawing requirement design cutting blanking;(2) according to the design of the layering requirement in flange forming mould pastes prepreg;(3) on flange forming mould arrangement vacuum device, it is placed into autoclave and is pre-pressed;(4) on flange forming mould arrangement final curing vacuum device, it is placed into autoclave and is finally cured;The relatively thick area of the relatively thick composite flange prepared using the application will not have delamination and porosity.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of composite material forming, and particularly relates to a thick composite flange forming process technical method. BACKGROUND

[0002] In the prior art, a pre-impregnated material is used for laying, and after laying is completed, a mold pressing full curing method is used for forming and processing the composite flange. This method has certain solidification layering defects for joint flanges with a thickness exceeding 50 mm. In the mold pressing process, the mold relies on upper and lower heating modules for heat transfer. When the joint flange is thick, it takes a certain time for the joint to transfer heat to the middle part. The pre-impregnated material close to the heating module is kept at a high temperature for a long time in this period of time. The middle part of the product has a large temperature difference with the upper and lower parts, which causes the cross-linking reaction to occur in advance in the part close to the heating module, and the reaction occurs later in the middle part, resulting in layering and porosity defects at the junction of the front and rear reaction areas in the product. SUMMARY

[0003] In view of the defects in the prior art, the purpose of the present application is to overcome the deficiencies in the prior art, solve the technical problems in the prior art of composite flange forming, and provide a thick composite flange forming process technical method. The thick area of the thick composite flange prepared by the present application will not have layering and porosity.

[0004] The purpose of the present application is achieved by a thick composite flange forming process technical method, comprising the following steps,

[0005] (1) Carbon fiber reinforced epoxy pre-impregnated material is cut according to the design drawing requirements;

[0006] (2) The pre-impregnated material is laid in the flange forming mold according to the design layering requirements, and the laying of the mold pressing preform is realized;

[0007] (3) A vacuum device is arranged on the flange forming mold, and it is put into a hot press tank for pre-pressing;

[0008] (4) An ultimate curing vacuum device is arranged on the flange forming mold, and it is put into a hot press tank for ultimate curing.

[0009] As a preferred scheme of the flange forming process technical method of the thick composite material in the application, wherein: the flange forming die comprises a circular ring-shaped first laying support die body, the upper side of the first laying support die body is a plane, the upper side of the first laying support die body is fixedly connected with a second laying support die body, the lower part of the second laying support die body is provided with a circular through hole, the center of the first laying support die body is connected with a middle die body, the circular through hole and the outer periphery of the middle die body form a circular ring-shaped first laying hole, the second laying support die body on the upper side of the first laying hole is provided with a second laying hole, the outer diameter of the second laying hole gradually increases from bottom to top, the upper side of the first lower die body and the middle die body are flush, and the upper side of the second laying support die body and the middle die body is detachably connected with an upper die body.

[0010] As a preferred scheme of the flange forming process technical method of the thick composite material in the application, wherein: in step (2), the specific steps of laying are as follows:

[0011] (201) A layer of prepreg is laid on the first laying support die body at the first laying hole, and is turned up to the outer periphery of the middle die body, a vacuum bag is arranged, vacuum is drawn on the first layer of prepreg, and the corner parts of the outer periphery of the first laying support die body and the second lower die body are compacted;

[0012] (202) According to the first laying design, a layer of prepreg is laid on the first laying support die body at the first laying hole, and is turned up to the outer periphery of the middle die body, the bottom part after laying is a bottom layer one, and the turned-up part is a side cladding one;

[0013] (203) A layer of prepreg is laid on the upper side of the bottom layer one, and is turned up to the inner edge of the second laying support die body, a vacuum bag is arranged, vacuum is drawn, and the layer of prepreg and the corner parts of the second laying support die body are compacted;

[0014] (204) According to the second laying design, a layer of prepreg is laid at the first laying hole, and is turned up to the inner edge of the second laying support die body, the bottom part after laying is a bottom layer two, and the side part after laying is a first side cladding;

[0015] (205) According to the third laying design, a layer of prepreg is laid on the bottom layer two, and is turned up to the side cladding one, the bottom part after laying is a bottom layer three, and the side part after laying is a side cladding two;

[0016] (206) According to the fourth laying design, a layer of prepreg is laid on the bottom layer three, and is turned up to the first side cladding, the bottom part after laying is a bottom layer four, and the side part after laying is a second side cladding;

[0017] (207) The preformed flat layer after preforming is put into the product;

[0018] (208) Side package layer two turn to the side of the flat layer, the second side of the package layer turn to the side of the flat layer, when turn to the side of the flat layer, need to be one layer by one layer to the side of the flat layer;

[0019] (209) Side package layer one turn to the side of the flat layer, the second side of the package layer turn to the side of the flat layer, every turn to the side of the flat layer, lay a layer of material piece on the turn to the side of the flat layer;

[0020] In each of the above layer designs, four layers are laid and arranged, a vacuum bag is arranged, and vacuum compression is performed for a set time.

[0021] As a preferred scheme of the thicker composite flange forming process technical method in the application, in the layer design one, the layer angles are [45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°] in turn.

[0022] As a preferred scheme of the thicker composite flange forming process technical method in the application, in the layer design two, the cyclically symmetrical layering is performed, and the layer angles are [0, 45, 0, 0, -45, 90, -45, 0, 0, 45, 0, 0, 90, 0, 0, 90, 0, 0, 45, 0, -45]s in turn, s is the number of stacking.

[0023] As a preferred scheme of the thicker composite flange forming process technical method in the application, in the step S309, a total of 8 layers of material pieces are laid when turn to the side of the flat layer, and the layer angles are [45, 0, 45, 0, 0, 45, 0, 45] respectively, before laying the first layer of material piece, 1mm thick aluminum sheet edge covering is performed at the sharp point of the prepreg.

[0024] As a preferred scheme of the thicker composite flange forming process technical method in the application, in the step (3), the curing process is specifically,

[0025] (301) The heating plate on the press is combined with the mold to set the heating temperature to 80±5℃, and the curing start time is recorded;

[0026] (302) The temperature is increased from room temperature to 100±5℃ at a rate of 20℃ / h, and when the temperature reaches 70±5℃, the pressure is increased to 5 tons; after the pressure is increased, the temperature continues to increase, and when the temperature reaches 100±5℃, the pressure is increased to 10 tons after 75min; after the pressure is increased, the mold gap is checked, and the mold gap is detected every 15min;

[0027] After 105min, the pressure is increased to 20 tons, and after the pressure is increased, the mold gap is checked, and the mold gap is detected every 15min;

[0028] After 100±5℃ for 120min, the pressure is increased to 30 tons, and after the pressure is increased, the mold gap is checked, and the mold gap is detected every 15min;

[0029] After holding at 100±5℃ for 135 minutes, pressurize to 30 tons. After pressurization, check the mold closing gap every 15 minutes.

[0030] After holding at 100±5℃ for 135 minutes, pressurize to 40 tons. After pressurization, check the mold closing gap every 15 minutes.

[0031] After holding at 100±5℃ for 135 minutes, pressurize to 50 tons. After pressurization, check the mold closing gap every 15 minutes. Hold at 100±5℃ for a total of 6 hours.

[0032] (303) 100±5℃-120±5℃, heating rate 20℃ / h, heat preservation at 120±5℃ for 3h, pressure preservation of 50 tons;

[0033] (304) 120±5℃-50±5℃, set temperature decreases, set temperature decreases by 5℃ every 1 hour, when the thermocouple temperature is below 50±5℃, the press pressure can be released.

[0034] As a preferred embodiment of the thicker composite flange forming process in this invention, the pre-formed flat layer is pre-pressed after its laying. The pre-pressing process of the pre-formed flat layer specifically involves pressurizing at room temperature at a rate of 0.02 MPa / min to 0.5 MPa, heating at room temperature at a rate of 1℃ / min, setting the medium temperature to 95℃, and holding the thermocouple at 90℃ for 3 hours after it reaches the slowest temperature. After holding for 3 hours, cooling is performed at a rate not exceeding 1℃ / min. When the slowest temperature thermocouple drops below 50℃, the pressure is released, and the can is opened after the pressure is released.

[0035] As a preferred embodiment of the thicker composite flange forming process in this invention, in step (4), the process of arranging the final vacuum device specifically involves:

[0036] Place a non-porous isolation membrane, a circular plate, a breathable felt, and a vacuum bag film sequentially on the upper surface of the flange forming mold. Place 6-8 vacuum nozzles at the four corners of the flat mold. The vacuum nozzles must be airtight. Seal the vacuum bag, perform a vacuum leak test, turn off the vacuum source for 10 minutes, and manually check that the vacuum level decreases by no more than 0.005 MPa. Place the thermocouple and seal it along the edge of the sealing strip of the sealing bag with a medium-temperature sealing strip. Cover it with excess sealing vacuum bag film to fix the position of the sealing strip and prevent the thermocouple from shifting due to heat. Then, lay two layers of breathable felt on the high-temperature bag film above the thermocouple and fix it with a release cloth strip. Connect to the vacuum system, apply a vacuum pressure below -0.092 MPa, and apply an air pressure of 0.5 MPa, maintaining this pressure for at least 15 minutes without leakage.

[0037] As a preferred scheme of the thick composite flange forming process technical method in the application, in the step (4), the final curing process is specifically,

[0038] (401) Pressurize at room temperature, pressurize to 0.5 MPa at a rate of 0.02 MPa / min, and heat at room temperature, with a heating rate of 0.2 ℃ / min;

[0039] (402) The medium temperature is set to 95 ℃, and when the slowest heating thermocouple is heated to 90 ℃, heat preservation is performed for 3 h;

[0040] (403) The medium temperature is set to 125 ℃, and when the slowest heating thermocouple is heated to 125 ℃, heat preservation is performed for 3 h;

[0041] (404) The medium temperature is set to 165 ℃, and when the slowest heating thermocouple is heated to 165 ℃, heat preservation is performed for 3 h;

[0042] (405) The medium temperature is set to 190 ℃, and when the slowest heating thermocouple is heated to 180 ℃, heat preservation is performed for 3 h, and then cooling is performed at a rate of not greater than 0.1 ℃ / min; when the slowest heating thermocouple is cooled to below 50 ℃, pressure is released, and after the pressure release is completed, the tank can be opened.

[0043] Compared with the prior art, the application solves the problems of delamination and porosity in the thickest area of the flange in the prior art, and the higher the pressure resistance requirement of the pressure-resistant container is, the higher the non-destructive quality requirement of the joint flange is. Due to the improvement of the pressure resistance grade, the thickness of the flange also needs to be increased. The thicker the thickness is, the more difficult the process forming is, and the more difficult the uniformity problem of the traditional molding process forming temperature is to solve. The application combines the molding process and the hot pressing process, and through the combination of special curing parameters, edge covering process and aluminum edge covering process, a flange without delamination is prepared. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 It is a perspective view of the upper die body hidden in the application Figure 1 .

[0045] Figure 2 It is a perspective view of the upper die body hidden in the application Figure 2 .

[0046] Figure 3 It is a plan view of the upper die body hidden in the application.

[0047] Figure 4 It is Figure 3 A-A view.

[0048] Figure 5 It is a perspective view of the flange forming die in the application.

[0049] Figure 6 A schematic view of the flange joint laying structure of the present application.

[0050] Figure 7 A perspective view of the flange prepared using the present application.

[0051] Figure 8 A curing schedule for the preform layup in the present application.

[0052] Figure 9 A top view of the preform mold in the present application.

[0053] Figure 10 A Figure 8 perspective view at B-B.

[0054] Wherein, 100 flange forming mold, 101 intermediate mold body, 102 upper mold body, 103 second laying support mold body, 104 first laying support mold body, 200 flange, 300 bottom layer three, 400 bottom layer one, 500 bottom layer two, 600 first side cladding layer, 700 second side cladding layer, 800 side cladding layer two, 900 side cladding layer one, 1000 bottom layer four, 2000 preform mold, 2001 lower preform mold body, 2001a preform sink, 2002 upper preform mold body, X first laying hole, S second laying hole. DETAILED DESCRIPTION

[0055] The present application will be further described below in conjunction with the drawings.

[0056] Example 1

[0057] Referring to Figures 1-5 , Figure 8 and Figure 9 , the first embodiment of the present application provides a thicker composite flange forming process technical method, which comprises the following steps,

[0058] (1) carbon fiber reinforced epoxy prepreg is cut according to the design drawing requirements, and an aluminum sheet with a thickness of 1 mm is prepared;

[0059] (2) the prepreg is laid in the flange forming mold according to the designed layup requirements, and the laying of the mold pressing preform is realized;

[0060] (3) the flange forming mold is placed into the press, and the mold pressing curing is carried out. After the curing is completed, the flange forming mold is removed;

[0061] (4) the surface is polished rough using 80 mesh sandpaper, and after the polishing is completed, ethyl acetate is used for cleaning. After the cleaning is checked, the oven is entered, and the drying is carried out at 60℃ for 6h;

[0062] (5) the prepreg layup is carried out according to the designed layup angle;

[0063] (6) arranging a vacuum device on the flange forming die, covering and fixing the upper die body, and placing it into a hot press tank for pre-pressing;

[0064] (7) arranging a final curing vacuum device on the flange forming die, and placing it into a hot press tank for final curing.

[0065] Specifically, the flange forming die comprises a circular annular first laying support die body, the upper side of the first laying support die body is a plane, the upper side of the first laying support die body is fixedly connected with a second laying support die body, the lower part of the second laying support die body is provided with a circular through hole, the center of the first laying support die body is connected with an intermediate die body, the circular through hole and the outer periphery of the intermediate die body form a circular annular first laying hole, the second laying support die body on the upper side of the first laying hole is provided with a second laying hole, the outer diameter of the second laying hole gradually increases from bottom to top, the upper side of the first lower die body is flush with the intermediate die body, and the upper side of the second laying support die body and the intermediate die body is detachably connected with an upper die body.

[0066] In step (3), the specific steps of laying are as follows:

[0067] (301) laying a layer of prepreg on the first laying support die body at the first laying hole, turning up to the outer periphery of the intermediate die body, arranging a vacuum bag, and vacuumizing the first layer of prepreg to compact the corner part of the outer periphery of the first laying support die body and the second lower die body;

[0068] (302) laying prepreg on the first laying support die body at the first laying hole according to the first laying design, turning up to the outer periphery of the intermediate die body, the bottom part of the laid prepreg is a bottom layer one, and the turned-up part is a side package layer one;

[0069] (303) laying a layer of prepreg on the upper side of the bottom layer one, turning up to the inner edge of the second laying support die body, arranging a vacuum bag, and vacuumizing the layer of prepreg to compact the corner part of the second laying support die body;

[0070] (304) laying prepreg on the first laying hole according to the second laying design, turning up to the inner edge of the second laying support die body, the bottom part of the laid prepreg is a bottom layer two, and the side part of the laid prepreg is a first side package layer;

[0071] (305) laying prepreg on the bottom layer two according to the third laying design, turning up to the side package layer one, the bottom part of the laid prepreg is a bottom layer three, and the side part of the laid prepreg is a side package layer two;

[0072] (306) laying prepreg on the bottom layer three according to the fourth laying design, turning up to the first side package layer, the bottom part of the laid prepreg is a bottom layer four, and the side part of the laid prepreg is a second side package layer;

[0073] (307) The surface of the preformed flat layer is roughened as a whole and cleaned with anhydrous ethanol, and is dried in an oven at 70°C for 2h. After drying, a layer of the same resin system adhesive film is attached to the polished area, and the preformed flat layer is placed in the product. The preformed flat layer is placed on the bottom layer with the four upper sides in contact, and is placed on the inner ring as the reference. After placement, the surface gap area is filled with carbon wire. After filling, the bag is extracted;

[0074] (308) The second side package layer is folded onto the upper side of the flat layer. When folding, the layers are stacked one by one on the flat layer;

[0075] (309) The second side package layer is folded onto the upper side of the flat layer. When folding, the layers are stacked one by one on the flat layer;

[0076] In each of the above layer designs, four layers are laid and a vacuum bag is arranged, and vacuum extraction and compaction are performed for 15min. The preformed flat layer is preformed and processed. The forming process of the preformed flat layer is as follows:

[0077] a) Prepreg laying

[0078] According to the order of the prepreg sheet marks, combined with the process flow card and the order of the sheet laying in the process specification, the sheet is laid in the preforming sink of the preforming mold (the preforming mold includes a lower preforming mold body, and the end of the lower preforming mold body facing upwards has a preforming sink). Except for the first layer of laying, which is extracted and compacted for 15min, after that, every four layers are laid, vacuum extraction and compaction are performed for 15min. When laying to 1 / 3, stop laying, extract and compact the bag;

[0079] b) Packaging

[0080] The peel-off cloth, non-porous isolation film, air-permeable felt, vacuum nozzle and vacuum bag film are sequentially placed on the laid blank, and the vacuum bag is packaged. After passing the air tightness test, it is transferred to the next process;

[0081] c) Cold pressing and pre-curing

[0082] The mold is transferred to the hot press tank, and after passing the leak detection, the operating parameters of the hot press tank are set according to the curing parameters specified in the process file, and the curing of the part is completed. The curing parameters of the hot press tank are as follows:

[0083] Pressurize at room temperature, pressurize to 0.5MPa at a rate of 0.02MPa / min, heat at room temperature, and heat at a rate of 1℃ / min; the medium temperature is set to 95℃, and when the slowest heating thermocouple reaches 90℃, it is kept for 3h. After 3h of heat preservation, cool down at a speed not greater than 1℃ / min, and when the temperature of the slowest cooling thermocouple drops below 50℃, release the pressure, and after the pressure release is completed, open the tank.

[0084] d) Prepreg lay-up

[0085] The prepreg plies are laid up according to the ply marking sequence of the prepreg, combined with the ply lay-up sequence in the process flow card and process procedure, and the direction of the mold coordinate system. Except for the first layer of lay-up, which is vacuumized and compacted for 15 minutes, after that, every 4 layers are laid up, vacuumized and compacted for 15 minutes. When laid up to 2 / 3, stop laying up, bag and vacuumize.

[0086] e) Encapsulation

[0087] The peel ply, non-porous release film, air-permeable felt, vacuum nozzle and vacuum bag film are sequentially placed on the laid-up blank, and the vacuum bag is encapsulated. After passing the air tightness test, it is transferred to the next process.

[0088] f) Cold pressing and pre-curing

[0089] The mold is transferred to the autoclave, and after passing the leak detection, the autoclave operating parameters are set according to the curing parameters specified in the process document, and the curing of the part is completed. The autoclave curing parameters are:

[0090] Pressurize at room temperature, pressurize to 0.5 MPa at a rate of 0.02 MPa / min, heat at room temperature, and heat at a rate of 1 °C / min; the medium temperature is set to 95 °C, and when the slowest heating thermocouple reaches 90 °C, it is kept for 3 h. After 3 h of heat preservation, cool down at a rate not greater than 1 °C / min, and when the slowest cooling thermocouple temperature drops below 50 °C, release the pressure, and after the pressure release is completed, open the tank.

[0091] g) Prepreg lay-up

[0092] The prepreg plies are laid up according to the ply marking sequence of the prepreg, combined with the ply lay-up sequence in the process flow card and process procedure, and the direction of the mold coordinate system. Except for the first layer of lay-up, which is vacuumized and compacted for 15 minutes, after that, every 4 layers are laid up, vacuumized and compacted for 15 minutes. When laid up to 2 / 3, stop laying up, bag and vacuumize.

[0093] h) Curing

[0094] The product is cured on the 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, as shown in the curing schedule Figure 8 .

[0095] i) After cooling to room temperature, open the upper mold and take out the preform lay-up.

[0096] In the first ply design, the ply angles are [45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°] in sequence; in the second ply design, the ply angles are [0, 45, 0, 0, -45, 90, -45, 0, 0, 45, 0, 0, 90, 0, 0, 90, 0, 0, 45, 0, -45] s in sequence, s being the stacking multiple.

[0097] The ply origin is positioned at the first ply sheet, a coordinate system is established through the origin, the direction to the inner circle of the joint is 90°, and the vertical direction of the right hand is 0°.

[0098] In step S309, a total of 8 ply sheets are laid during the flanging, and the ply angles are [45, 0, 45, 0, 0, 45, 0, 45] respectively; before laying the first ply sheet, an aluminum sheet with a thickness of 1 mm is wrapped around the tip of the prepreg.

[0099] The design can offset the stress caused by the joint heating, curing and cooling shrinkage. Since the thermal expansion coefficient of carbon fiber is smaller than that of mold steel, the mold steel is easy to generate extrusion force on the joint tip during the cooling process, which causes the joint to delaminate. The aluminum sheet with a suitable thickness can offset a certain stress to prevent the tip from delaminating under stress.

[0100] Embodiment 2

[0101] It is the second embodiment of the present application, which is different from embodiment 1 in that it discloses a specific curing process. The use of the curing method of the present embodiment can further prepare a joint flange with high strength.

[0102] In step (3), the curing process is specifically,

[0103] (301) set the heating temperature of the upper heating plate of the press to 80±5℃ and record the start time of the curing;

[0104] (302) normal temperature-100±5℃, the temperature reaches 70±5℃, and the pressure is increased to 5 tons, and after the pressure is increased, the temperature continues to increase, and when the temperature reaches 100±5℃, the pressure is increased to 10 tons after 75 minutes, and after the pressure is increased, the die gap is checked, and the die gap is checked every 15 minutes;

[0105] 105min after pressure to 20 tons, after pressure check die gap, every 15min detection once die gap;

[0106] 100±5℃, 120min after pressure to 30 tons, after pressure check die gap, every 15min detection once die gap;

[0107] 100±5℃ for 135 min, then pressurized to 30 tons, check the mold gap after pressurization, every 15 min to detect the mold gap;

[0108] 100±5℃ for 135 min, then pressurized to 40 tons, check the mold gap after pressurization, every 15 min to detect the mold gap;

[0109] 100±5℃ for 135 min, then pressurized to 50 tons, check the mold gap after pressurization, every 15 min to detect the mold gap; 100±5℃ for a total of 6h;

[0110] (303) 100±5℃-120±5℃, the heating rate is 20℃ / h, 120±5℃ for 3h, and the pressure is 50 tons;

[0111] (304) 120±5℃-50±5℃, set the temperature to decrease, every 1h the temperature decreases by 5℃, and when the thermocouple temperature is lower than 50±5℃, the pressurization can be removed.

[0112] In step (4), the process of arranging the final vacuum device is specifically,

[0113] Place the non-porous isolation film, round plate, air-permeable felt, and vacuum bag film on the upper surface of the flange forming mold in sequence, place the vacuum nozzle at the four corners of the flat plate mold, the number of vacuum nozzles is 6-8, the vacuum nozzle cannot leak, package the vacuum bag, vacuum leak detection, close the vacuum source for 10 min, manually detect that the vacuum degree is reduced by not more than 0.005 MPa; place the thermocouple, use the medium-temperature sealing rubber strip to seal and paste the thermocouple along the edge of the sealing rubber strip of the packaging bag, cover the excess packaging vacuum bag film to fix the position of the sealing rubber strip, avoid the sealing rubber strip moving due to heat; then lay 2 layers of air-permeable felt on the high-temperature bag film above the thermocouple, and fix it with a release cloth; connect to the vacuum system, apply a vacuum pressure of-0.092 MPa or lower, and apply an air pressure of 0.5 MPa, keep for at least 15 min without leakage.

[0114] In step (4), the process of final curing is specifically,

[0115] (401) pressurize at room temperature, pressurize to 0.5 MPa at a rate of 0.02 MPa / min, and heat at room temperature, the heating rate is 0.2℃ / min;

[0116] (402) set the medium temperature to 95℃, when the slowest heating thermocouple is heated to 90℃, keep for 3h;

[0117] (403) set the medium temperature to 125℃, when the slowest heating thermocouple is heated to 125℃, keep for 3h;

[0118] (404) The medium temperature is set to 165℃, and after the slowest heating thermocouple is heated to 165℃, the temperature is kept for 3h;

[0119] (405) The medium temperature is set to 190℃, and after the slowest heating thermocouple is heated to 180℃, the temperature is kept for 3h, and then the temperature is cooled at a speed of not more than 0.1℃ / min, and when the temperature of the slowest heating thermocouple is reduced to below 50℃, the pressure is released, and after the pressure is released, the tank can be opened.

[0120] The joint flange prepared by combining the joint flange of Example 2 and Example 1 can provide greater axial connection strength and shoulder pressure resistance strength under working conditions.

[0121] Example 3

[0122] The following experimental verification proves the technical effects of the present application.

[0123] For the process design layer, water pressure blasting tests are performed on the joint test pieces under the same shape, and the results are shown in the following table. The joint test piece under the process design is obviously better than the first two test pieces.

[0124]

[0125] After the mold preform is laid and pasted, the process is investigated according to the resin characteristics, the appropriate preforming curing parameters are confirmed, the mold curing is performed, and the mold preform curing parameters are shown in the following table.

[0126]

[0127] Through the test piece research, it is shown that the selected resin system of this type has a lower resin viscosity at 100-110℃, and the stepwise pressure connection has a great improvement without damage, and for the curing process, two comparative tests are performed, and the comparison results are shown in the above table. The results show that the pre-preg single layer shape is relatively flat under the process stepwise pressure, and there is no damage and no abnormality, which can ensure that the carbon fiber strength development rate is higher, and the product performance is more stable.

[0128] The present application is not limited to the above examples, and based on the technical solutions disclosed in the present application, those skilled in the art can make some substitutions and modifications to some technical features without creative labor, and these substitutions and modifications are within the protection scope of the present application.

Claims

1. A process for forming a thick composite flange, comprising: The method comprises the following steps, (1) cutting the carbon fiber reinforced epoxy prepreg according to the design drawing; (2) laying the prepreg in the flange forming die according to the design to realize the laying of the molded prepreg; The flange forming die comprises a circular annular first laying support die body, the upper side of the first laying support die body is a plane, the upper side of the first laying support die body is fixedly connected with a second laying support die body, the lower part of the second laying support die body is provided with a circular through hole, the center of the first laying support die body is connected with a middle die body, the circular through hole and the outer periphery of the middle die body form a circular annular first laying hole, the second laying support die body on the upper side of the first laying hole is provided with a second laying hole, the outer diameter of the second laying hole gradually increases from bottom to top, the upper side of the first lower die body and the middle die body are flush, and the upper side of the second laying support die body and the middle die body is detachably connected with an upper die body; the specific laying steps are as follows: (201) laying a layer of prepreg on the first laying support die body at the first laying hole, turning up to the outer periphery of the middle die body, arranging a vacuum bag, and vacuumizing the first layer of prepreg to compact the corners of the outer periphery of the first laying support die body and the second lower die body; (202) laying the prepreg on the first laying support die body at the first laying hole according to the first laying design, turning up to the outer periphery of the middle die body, and arranging a vacuum bag to compact the corners of the outer periphery of the first laying support die body and the second lower die body; (203) laying a layer of prepreg on the upper side of the first layer, turning up to the inner edge of the second laying support die body, arranging a vacuum bag, and vacuumizing the layer of prepreg to compact the corners of the second laying support die body; (204) laying the prepreg at the first laying hole according to the second laying design, turning up to the inner edge of the second laying support die body, and arranging a vacuum bag to compact the corners of the second laying support die body; (205) laying the prepreg on the first layer according to the third laying design, turning up to the first side package layer, and arranging a vacuum bag to compact the corners of the second laying support die body; (206) laying the prepreg on the first layer according to the fourth laying design, turning up to the first side package layer, and arranging a vacuum bag to compact the corners of the second laying support die body; (207) placing the preformed flat layer into the product; (208) turning up the second side package layer to the upper side of the flat layer, and turning up the second side package layer to the upper side of the flat layer, and the layers are arranged on the flat layer one by one during the turning up; (209) turning up the first side package layer to the upper side of the second side package layer and the second side package layer on the flat layer, and laying a layer of prepreg on the turning up layer every time; In each of the above laying designs, a vacuum bag is arranged every four layers, and the vacuum is extracted and compacted for a set time; (3) arranging a vacuum device on the flange forming die, and placing it into a hot press tank for pre-pressing; (4) arranging a final curing vacuum device on the flange forming die, and placing it into a hot press tank for final curing.

2. A process technology method for forming a thick composite flange as claimed in claim 1, wherein In the first ply design, the ply angles are [45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°, 45°, 0°, 0°, 45°] in sequence.

3. A process technology method for forming a thick composite flange as claimed in claim 1, wherein, In the second ply design, the ply angles are [0, 45, 0, 0, -45, 90, -45, 0, 0, 45, 0, 0, 90, 0, 0, 90, 0, 0, 45, 0, -45]s in sequence, where s is the stacking number.

4. A process technology method for forming a thick composite flange as claimed in claim 1, wherein, In step S309, a total of 8 plies are laid during the flanging, and the ply angles are [45, 0, 45, 0, 0, 45, 0, 45] respectively. Before laying the first ply, an aluminum sheet with a thickness of 1 mm is wrapped around the pre-preg at the tip point.

5. A process technology method for forming a thick composite flange as claimed in claim 1, wherein, In step (3), the curing process is specifically as follows: (301) set the heating temperature of the upper heating plate of the press to 80±5℃ and record the start time of the curing; (302) from room temperature to 100±5℃, the temperature rising rate is 20℃ / h, when the temperature reaches 70±5℃, press to 5 tons, and continue to increase the temperature after the pressure is released, when the temperature reaches 100±5℃, start to press to 10 tons after 75 min, check the die gap after the pressure is released, and check the die gap every 15 min; 105 min later, press to 20 tons, check the die gap after the pressure is released, and check the die gap every 15 min; 100±5℃ for 120 min, press to 30 tons, check the die gap after the pressure is released, and check the die gap every 15 min; 100±5℃ for 135 min, press to 30 tons, check the die gap after the pressure is released, and check the die gap every 15 min; 100±5℃ for 135 min, press to 40 tons, check the die gap after the pressure is released, and check the die gap every 15 min; 100±5℃ for 135 min, press to 50 tons, check the die gap after the pressure is released, and check the die gap every 15 min; 100±5℃ for a total of 6h; (303) from 100±5℃ to 120±5℃, the temperature rising rate is 20℃ / h, 120±5℃ for 3h, and the pressure is kept at 50 tons; (304) from 120±5℃ to 50±5℃, set the temperature to decrease by 5℃ every 1h, and the press can be released when the thermocouple temperature is lower than 50±5℃.

6. A process technology method for forming a thicker composite flange according to any one of claims 1 to 4, characterized by, After the pre-forming flat ply laying is completed, pre-pressing is performed, and the pre-pressing process of the pre-forming flat ply is specifically as follows: press at room temperature, press to 0.5MPa at a rate of 0.02MPa / min, heat 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℃, the temperature is kept for 3h; after 3h of temperature keeping, cool down at a speed of not more than 1℃ / min, and when the temperature of the slowest cooling thermocouple is lower than 50℃, release the pressure, and after the pressure is released, open the tank.

7. A process technology method for forming a thicker composite flange according to any one of claims 1 to 4, characterized by, In the step (4), the process of arranging the final vacuum device is specifically as follows: Place non-porous isolation film, round plate, air-permeable felt and vacuum bag film on the upper surface of the flange forming mold in sequence, place vacuum nozzles at the four corners of the flat mold, the number of vacuum nozzles is 6-8, the vacuum nozzles cannot leak, package the vacuum bag, vacuum leak detection, close the vacuum source for 10 min, manually detect that the vacuum degree is reduced by not more than 0.005 MPa; place the thermocouple, seal and paste the thermocouple along the edge of the sealing adhesive tape of the packaging bag with the medium-temperature sealing adhesive tape, cover the excess packaging vacuum bag film to fix the position of the sealing adhesive tape, so as to avoid that the sealing adhesive tape is displaced due to heat; then lay 2 layers of air-permeable felt on the high-temperature bag film on the upper part of the thermocouple, and fix them with release cloth; connect to the vacuum system, apply a vacuum pressure of-0.092 MPa or below, and apply an air pressure of 0.5 MPa, keep for at least 15 min without leakage.

8. A process technology method for forming a thicker composite flange according to any one of claims 1 to 4, characterized by, In step (4), the final curing process is specifically, (801) pressurize at room temperature, pressurize to 0.5 MPa at a rate of 0.02 MPa / min, heat at room temperature, and the heating rate is 0.2 ℃ / min; (802) the medium temperature is set to 95 ℃, and when the slowest heating thermocouple is heated to 90 ℃, heat preservation for 3 h; (803) the medium temperature is set to 125 ℃, and when the slowest heating thermocouple is heated to 125 ℃, heat preservation for 3 h; (804) the medium temperature is set to 165 ℃, and when the slowest heating thermocouple is heated to 165 ℃, heat preservation for 3 h; (805) the medium temperature is set to 190 ℃, and when the slowest heating thermocouple is heated to 180 ℃, heat preservation for 3 h, and then cool at a speed of not more than 0.1 ℃ / min, when the temperature of the slowest cooling thermocouple is reduced to below 50 ℃, depressurize, and after depressurization is completed, the tank can be opened.

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