A method of forming a composite t-beam

Abstract

The application discloses a composite T-shaped beam forming method in the field of aviation technology, adopts split setting and combinable forming dies, laying-up dies and bottom surface forming dies, is formed through secondary hot pressing curing process, and comprises the following steps: S1: preforming and R angle precasting: laying-up prepreg on the profile of the forming die and the laying-up die respectively, and positioning the independently precast prepreg core material in the T-shaped beam R angle area formed after the two are closed; S2: first mold closing and pre-curing: the laying-up die and the forming die are closed, lateral auxiliary positioning is carried out by using the bottom surface forming die, locking and fixing are carried out through positioning pins and clamping parts, and the combined body after mold closing is subjected to first hot pressing curing. The application fills the core material which is independently precast and pre-cured through heat sealing and pressing, cooperates with the secondary hot pressing process of "pre-curing + final curing", ensures sufficient pressure transmission and tight laying in the R angle area, effectively avoids defects such as delamination and bridging, and significantly improves the product nondestructive testing qualification rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aviation, more particularly, to a composite T-beam forming method. BACKGROUND

[0002] In the fields of aerospace, high-end equipment manufacturing, etc., T-beams, as the core load-bearing structural components, are widely used in key positions such as the front / rear edge ribs of aircraft wings, the longitudinal frames of fuselages, and the support of spacecraft cabins, and their performance directly determines the structural strength, rigidity and lightweight level of the whole machine. Such structural components need to meet the stringent requirements of "high strength, high modulus and low weight", and not only need to withstand the aerodynamic load and vibration impact during flight, but also need to control their own weight to improve the endurance and maneuverability of the equipment, so high standards are put forward for the precision, stability and product consistency of the forming process.

[0003] Currently, the forming of such parts mainly adopts integrated die and single curing process. Specifically, first, pre-impregnated materials are laid on each surface of the mold to form a blank, then the blank is assembled and molded, and placed in a heat press tank for one-time curing forming. In order to improve the forming quality of the R angle (i.e. the transition area of the flange and the web) of the T-beam, some processes will try to manually fill resin fillers or place simple foam cores in this area. In addition, in order to ensure the rigidity of the mold, the forming die is mostly made of high-strength steel material.

[0004] However, the existing process has certain problems in actual application, which affects the product quality and production efficiency: on the one hand, the R angle area of the T-beam, as the transition part of the flange and the web, has concentrated curvature changes, and when the pre-impregnated material is laid, wrinkles and uneven tension are prone to occur, and during the curing process, the resin softens and flows under heat, resulting in attenuation of pressure transmission in this area, and unable to form uniform and effective compaction effect, and further frequent problems such as delamination, porosity and bridging, which not only makes the product non-destructive testing qualified rate low, but also greatly reduces the structural load capacity, and there is a flight safety hazard; on the other hand, the traditional integrated mold is mostly made of steel structure, which is heavy and inconvenient to disassemble and assemble, and the positioning accuracy is difficult to control when the mold is closed, which is easy to produce inter-cavity gaps, further aggravating the problems of resin loss and uneven pressure; at the same time, the manually filled filler has poor compatibility with the pre-impregnated material resin, and is prone to interface separation, while the simple core material lacks targeted pre-curing treatment and is prone to deformation and collapse during subsequent curing, and cannot maintain the forming profile of the R angle area for a long time; in addition, in the one-time curing process, the curing shrinkage of each part of the blank is not synchronized, which is easy to produce internal stress concentration, resulting in warping and size out-of-tolerance of the product after demolding, and the subsequent correction is difficult, further increasing the manufacturing cost and production cycle, so we urgently need a composite T-beam forming method to solve the above problems. SUMMARY

[0005] The application aims to provide a novel technical scheme of a composite T-beam forming method.

[0006] The application is achieved in the following manner: a composite T-beam forming method, which adopts a split forming die, a lay-up die and a bottom surface forming die, is formed by a secondary hot pressing and curing process, and comprises the following steps:

[0007] S1: preforming and R-angle preforming: pre-impregnated materials are laid up on the surfaces of the forming die and the lay-up die, and an independently preformed pre-impregnated material core is positioned in the T-beam R-angle region formed after the two dies are closed;

[0008] S2: first die closing and pre-curing: the lay-up die and the forming die are closed, lateral auxiliary positioning is performed by using the bottom surface forming die, the combined body after the die closing is locked and fixed by using positioning pins and clamping members, and the first hot pressing and curing is performed on the combined body;

[0009] S3: die conversion and bottom surface lay-up: the lay-up die is removed, and pre-impregnated materials are laid up on the surface of the bottom surface forming die;

[0010] S4: second die closing and final curing: the bottom surface forming die after the lay-up is closed with the forming die after the S2 step, an elastic soft die is applied to the outer surface of the blank after the die closing and is encapsulated, and the final hot pressing and curing is performed;

[0011] S5: die releasing and post-processing.

[0012] Optionally, in the step S1, the pre-impregnated material core is formed after being rolled from a unidirectional pre-impregnated material, a glue film is arranged on the surface thereof, and the pre-impregnated material core is pre-cured by an independent heat sealing and pressing process.

[0013] Optionally, in the step S2, the first hot pressing and curing is heat sealing and pressing, and the curing pressure is lower than that of the final hot pressing and curing in the step S4.

[0014] Optionally, the curing pressure of the first hot pressing and curing is 0.3 MPa to 0.8 MPa, and the curing temperature is 50°C to 80°C.

[0015] Optionally, the specific parameters of the first hot pressing and curing are as follows: the vacuum degree is maintained at -0.10 MPa to -0.08 MPa, the temperature is raised to 60°C±3°C, the temperature is kept constant for 10-15 minutes, then the pressure is increased to 0.6 MPa±0.05 MPa within 15-25 minutes and the pressure is kept constant for 10-15 minutes.

[0016] Optionally, between step S2 and step S3, a step of trimming the cured surface of the core material is further included, and when the core material area is recessed or protruded by a height exceeding 0.2mm, the area is filled or shaved.

[0017] Optionally, in step S4, a blocking strip made of a fabric prepreg laid in a 0° direction is embedded on the edge of the mating surface of the forming die and the bottom surface forming die, and the blocking strip is used to fill the gap formed by the mating of the two.

[0018] Optionally, in step S4, the elastic soft die is made of silica gel material, and the hardness is 20-60.

[0019] Optionally, in step S4, the curing pressure of the final hot-pressing curing is 0.5MPa to 1.0MPa, and the curing temperature is 100℃ to 140℃.

[0020] Optionally, the specific parameters of the final hot-pressing curing are as follows: the vacuum degree is not less than 0.09MPa, the temperature is raised to 125℃±5℃ at a rate of 1-2℃ / min, and then the temperature is kept constant for 150-210 minutes, the pressure is increased to 0.6MPa±0.05MPa in the temperature range of 40-60℃, and the pressure is kept constant throughout the process, and after the curing is completed, the temperature is lowered to below 60℃ at a rate of not higher than 2℃ / min.

[0021] Compared with the prior art, the beneficial effects of the present application are as follows:

[0022] 1. According to one embodiment of the present disclosure, the composite T-shaped beam forming method fills the core material independently preformed and pre-cured by heat sealing and pressing in the R-angle area, and cooperates with the secondary hot-pressing process of "pre-curing + final curing", to ensure sufficient pressure transmission and tight laying in the R-angle area, effectively avoid defects such as delamination and bridging, and significantly improve the product non-destructive testing qualification rate.

[0023] 2. According to one embodiment of the present disclosure, the composite T-shaped beam forming method replaces the traditional Q345 steel material with 6061 aluminum material for the laying-up die, which not only reduces the mold manufacturing cost, but also greatly reduces the mold weight, and at the same time, combines the split die design and the locking mode of G-shaped clamps and positioning pins, to improve the convenience of mold transportation, disassembly and positioning.

[0024] 3. According to one embodiment of the present disclosure, the composite T-shaped beam forming method uses a silica gel soft die with a hardness of 20-60 for flexible pressing in the final curing stage, and cooperates with the fabric blocking strip to fill the gap of the die mating, and the air cushion pad to assist sealing, to ensure uniform pressure transmission of each part of the blank, effectively compensate for the small deviation of the die surface, and improve the product surface precision and surface smoothness.

[0025] 4. According to one embodiment of the present disclosure, the composite T-beam forming method forms a full-process quality control chain by specifying that the pre-impregnated material is vacuumized and compacted for 15 minutes after every 4 layers of laying, precisely trimming when the deviation of the core material surface is more than 0.2 mm, synchronously laying the parts in the oven with the products, and other details, reduces the production uncertainty, and improves the product forming consistency and process stability. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only a part of the embodiments of the present application, and for those skilled in the art, other drawings can be obtained without creative labor based on the provided drawings.

[0027] Figure 1 The core material forming process flowchart of the present application.

[0028] Figure 2 The T-beam forming process flowchart of the present application.

[0029] Figure 3 The core material schematic diagram of the present application.

[0030] Figure 4 The heat-sealing and pressing mold schematic diagram of the present application.

[0031] Figure 5 The fabric baffle placement schematic diagram of the present application.

[0032] Figure 6 The packaging schematic diagram of the present application.

[0033] The symbols in the drawings are as follows: 1, forming mold; 2, lay-up mold; 3, bottom surface forming mold; 4, core material; 5, adhesive film; 6, unidirectional pre-impregnated material; 7, G-type clamp; 8, inflatable cushion pad; 9, fabric baffle; 10, peelable cloth; 11, porous release film; 12, non-porous release film; 13, soft mold; 14, air-permeable felt; 15, vacuum bag; 16, flat plate. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0035] As Figures 1-6As shown, a composite T-beam forming method adopts split setting and combinable forming mold 1, laying-up mold 2 and bottom surface forming mold 3, and is formed by secondary hot-pressing curing process, including the following steps:

[0036] S1: Preforming and R-angle pre-preparation: Prepregs are laid on the surfaces of forming mold 1 and laying-up mold 2 respectively, and an independently pre-prepared prepreg core material 4 is positioned in the R-angle area of the T-beam formed after the two molds are closed.

[0037] Here, the surfaces of forming mold 1, laying-up mold 2 and flat plate 16 are cleaned to ensure that the surfaces are free of impurities and scratches, uniformly coated with release agent and dried at room temperature for at least 30 minutes; the electronic blanking diagram is called to cut the prepreg, the prepreg is sorted according to the layering order, the workpiece and the part are laid and prepared synchronously, and the layering order and laying pressure of the two are completely consistent; the prepreg is laid on the surfaces of forming mold 1 and laying-up mold 2 according to the label, and after the first layer is laid, vacuum compression is performed for 15 minutes, and then vacuum compression is performed for 15 minutes every 4 layers; at the same time, the prepreg core material 4 is independently pre-prepared to ensure accurate filling in the R-angle area.

[0038] Further, when pre-preparing the core material 4, a unidirectional prepreg 6 with a width of 63 mm is rolled into a round bar shape, placed into a core material 4 forming tool that has been cleaned in advance and free of impurities, and rolled with an electric iron (temperature not exceeding 60°C) to ensure that it completely adheres to the tool, ensuring that the shape of the core material 4 matches the R-angle profile.

[0039] Further, after the core material 4 is pre-prepared, it can be adapted to the closing gap of forming mold 1 and laying-up mold 2 in advance to avoid displacement during subsequent mold closing, laying a foundation for the compaction quality of the R-angle area.

[0040] In step S1, after the prepreg core material 4 is formed by rolling the unidirectional prepreg 6, a film 5 is placed on its surface, and it is pre-cured by an independent heat sealing and pressing process.

[0041] Here, one layer of JE1301-B film 5 is laid on the top and bottom of the surface of the core material 4, and is ironed flat with an electric iron, and then the core material 4 is sequentially laid with a non-porous release film, a breather mat 14 and a vacuum bag 15, and after strictly performing the leak detection process (to ensure no air leakage points), it is sent to a hot press tank for heat sealing and pressing to ensure the pre-curing effect of the core material 4.

[0042] Further, during heat sealing and pressing, the process of "vacuuming to -0.090~-0.10 MPa→20 min, pressurizing to 0.62 MPa→1.3°C / min, heating to 58°C→when the thermocouple reaches 55°C, constant temperature for 10-11 min" is strictly followed, and the vacuum degree data is monitored in real time during the vacuuming process. If the vacuum degree drops, stop immediately to check for leaks to ensure uniform curing of the core material 4.

[0043] Further, the independently pre-cured core material 4 has higher strength, and can avoid deformation and collapse in subsequent mold closing and curing process, effectively solving the problem of poor laying in the R corner area in the traditional process.

[0044] S2: First mold closing and pre-curing: the lay-up mold 2 is closed with the forming mold 1, the lateral auxiliary positioning is performed by using the bottom forming mold 3, the combined body after mold closing is locked and fixed by positioning pins and clamping members, and the first hot pressing curing is performed.

[0045] Here, the lay-up mold 2 is precisely closed above the forming mold 1, the core material 4 is embedded, the lateral positioning is realized by the bottom forming mold 3 adhered to the sides of the two, the positioning is performed by the positioning pins inserted into the pin holes, the perpendicularity is checked after the positioning pins are inserted to avoid the inclination of the mold leading to uneven gaps between the molds, the G-shaped clamps 7 are symmetrically locked to prevent the misalignment of the molds.

[0046] Further, the force of the G-shaped clamps 7 is uniformly controlled during locking to avoid the deformation of the mold due to stress, and the gaps between the forming mold 1, the lay-up mold 2 and the bottom forming mold 3 are checked after the mold closing to ensure that there is no obvious gap before packaging.

[0047] Further, the mold closing method is precise in positioning and convenient in disassembly, the lay-up mold 2 is made of 6061 aluminum material (compared with the traditional Q345 steel material), the mold manufacturing cost and weight are reduced, the transportation is facilitated, and the operation efficiency is greatly improved.

[0048] In step S2, the first hot pressing curing is hot sealing pressing, the curing pressure is lower than that of the final hot pressing curing in step S4, the curing pressure of the first hot pressing curing is 0.3 MPa to 0.8 MPa, the curing temperature is 50°C to 80°C, and the specific parameters of the first hot pressing curing are as follows: the vacuum degree is maintained at -0.10 MPa to -0.08 MPa, the temperature is raised to 60°C±3°C, and then the temperature is kept constant for 10-15 minutes, then the pressure is increased to 0.6 MPa±0.05 MPa within 15-25 minutes and kept constant for 10-15 minutes.

[0049] Here, the first hot sealing pressing adopts low pressure and low temperature parameters, which can realize the initial adhesion of the core material 4 and the pre-impregnated material, and avoid the premature flow and loss of resin caused by high temperature and high pressure.

[0050] Further, the temperature rise rate is controlled at 1.8°C / min, the temperature is raised to 63°C based on the lagging thermocouple temperature, the lagging thermocouple reaches 55°C, and the temperature is kept constant for 10-11 minutes, then the pressure is increased to 0.62 MPa within 20 minutes and kept constant for 10-11 minutes, to ensure that the temperature of each area of the forming mold 1, the lay-up mold 2 and the bottom forming mold 3 is uniform.

[0051] Further, low-pressure pre-curing can preliminarily fix the position of the core material 4, prevent the core material 4 from shifting during the subsequent mold conversion process, and reserve sufficient resin flow space for the R-angle area, thereby improving the final curing quality.

[0052] Between step S2 and step S3, a step of trimming the cured surface of the core material 4 is further included. When the core material 4 area is recessed or protruded by a height exceeding 0.2 mm, the area is filled or scraped.

[0053] Here, after the vacuum bag 15 and the auxiliary material are removed, the surface state of the core material 4 is first reviewed. The ideal state is that the core material 4 area is slightly higher than the plane by 0.2 mm. If recessed, a layer of SYT49S-J / E1301 unidirectional prepreg 6 is filled to fill a layer of JE1301-B film 5 on the surface, and the film 5 is ironed and flattened after pressing. If the protrusion height exceeds 0.2 mm, the protruding part is scraped with a blade, the film 5 is supplemented and the glue absorbing cloth is ironed and flattened.

[0054] Further, special tools are used during the trimming process, and the glue absorbing cloth needs to be kept dry and clean to avoid contaminating the surface of the core material 4 and damaging the surrounding prepreg blank, and to ensure that the surface profile of the core material 4 after trimming matches the theoretical profile.

[0055] Further, precise trimming can eliminate the shape deviation of the core material 4 after pre-curing, ensure that the core material 4 is closely attached to the bottom surface prepreg, and avoid forming gaps to cause delamination and bridging defects.

[0056] S3: mold conversion and bottom surface lamination: remove the lamination mold 2 and laminate the prepreg on the profile of the bottom surface forming mold 3.

[0057] Here, the lamination mold 2 is removed gently to avoid colliding with the blank on the forming mold 1. The prepreg is laminated on the profile of the bottom surface forming mold 3 according to the material sheet label. After the first layer of lamination is completed, vacuum pressing is performed for 15 minutes. After that, vacuum pressing is performed for 15 minutes every 4 layers of lamination to ensure that the bottom surface blank is laminated tightly.

[0058] Further, the bottom surface prepreg is aligned with the blank on the forming mold 1 during lamination to avoid misalignment and cause product size deviation. The furnace piece material sheet and the product material sheet are laminated synchronously, and the number of laminated layers and the pressing time are recorded synchronously during the lamination process to ensure the accuracy of performance detection.

[0059] Further, after the mold conversion, the bottom surface lamination is performed separately, which can control the lamination quality of the bottom surface blank, avoid the problem that the bottom surface lamination is limited in the traditional integrated mold, and the flat plate 16 provides sufficient operation space for this process.

[0060] S4; Second time of closing mold and final curing: the bottom forming mold 3 and the forming mold 1 after S2 are closed, the elastic soft mold 13 is applied to the outer surface of the blank after closing, and the blank is packaged and finally cured by hot pressing.

[0061] Here, the bottom forming mold 3 and the forming mold 1 are precisely closed, wrapped with a release cloth after being clamped symmetrically by the G-shaped clamp 7, and the G-shaped clamp 7 is removed to avoid indentation; the peelable cloth 10, the porous release film 11, the non-porous release film 12, the soft mold 13, the air-permeable felt 14, and the vacuum bag 15 are sequentially laid on the outer surface of the blank, and the soft mold 13 needs to completely cover the outer surface of the blank without missing or wrinkled areas to ensure that the packaging is airtight.

[0062] Further, the closing gap of the forming mold 1 and the bottom forming mold 3 is checked before closing to ensure that the fabric baffle 9 and the inflatable cushion 8 are installed in place, and the vacuum bag 15 is tightly attached to the air-permeable felt 14 during packaging to avoid wrinkles that affect the vacuum effect.

[0063] Further, the second time of closing mold adopts a precise docking design of the mold, which can realize uniform transmission of pressure to each part of the blank during subsequent high-pressure curing, and greatly improves the overall forming quality of the product.

[0064] In step S4, a baffle made of fabric prepreg is embedded along the 0° direction on the edge of the closing surface of the forming mold 1 and the bottom forming mold 3, and the baffle is used to fill the gap formed by the closing of the two.

[0065] Here, the baffle is a fabric baffle 9 made of HF20-3K / E1301 fabric prepreg, which is laid along the 0° direction, and the thickness is equal to or slightly lower than that of the rib, and the width is just enough to fill the closing gap to achieve seamless filling; after placing, gently press it with your hand to fix it to avoid displacement during subsequent operations.

[0066] Further, inflatable cushions 8 are arranged on the remaining two closing surfaces of the forming mold 1 and the bottom forming mold 3 to form a full-range seal in cooperation with the fabric baffle 9 to prevent resin overflow during curing.

[0067] Further, the combination of the fabric baffle 9 and the inflatable cushion 8 not only fills the closing gap, but also self-adapts to changes in pressure to ensure uniform transmission of pressure to the edge of the blank and avoid local pressure deficiency.

[0068] In step S4, the elastic soft mold 13 is made of silicone with a hardness of 20-60.

[0069] Here, the elastic soft mold 13 is made of silicone with a hardness of 20-60, which has good flexibility and pressure resistance and can completely fit the surface profile of the blank.

[0070] Further, the soft mold 13 is laid to ensure no bubbles, no wrinkles, and close contact with the non-porous isolation film 12, ensuring the continuity of pressure transmission.

[0071] Further, the flexible pressing characteristics of the soft mold 13 made of silica gel can effectively compensate for the slight deviation of the molding mold 1 and the bottom molding mold 3, avoid local pressure injury caused by rigid pressing, and improve the smoothness of the product surface and the profile accuracy.

[0072] In step S4, the final hot-pressing curing pressure is 0.5 MPa to 1.0 MPa, and the curing temperature is 100°C to 140°C.

[0073] Here, the final curing adopts a high-pressure high-temperature parameter range to adapt to the curing needs of the composite material, ensure sufficient cross-linking and curing of the resin, and improve the mechanical properties of the product.

[0074] Further, the matching design of curing pressure and temperature avoids fiber damage of the unidirectional prepreg 6 due to excessive pressure or resin degradation of the film 5 due to excessive temperature, and takes into account the strength and durability of the product.

[0075] Further, high-pressure high-temperature curing can eliminate internal pores in the blank, promote the interface bonding of the resin and the fiber, greatly reduce the risk of delamination defects, and improve the load-bearing capacity of the product.

[0076] The specific parameters of the final hot-pressing curing are: the vacuum degree is not less than 0.09 MPa, the temperature is raised to 125°C±5°C at a rate of 1-2°C / min, and then held at 150-210 minutes, the pressure is increased to 0.6 MPa±0.05 MPa in the temperature range of 40-60°C and held constant throughout, and the temperature is lowered to below 60°C at a rate of not higher than 2°C / min after curing.

[0077] Here, the vacuum degree is not less than 0.092 MPa at room temperature, the vacuum bag 15 is tightly sealed through cold pressing test, the temperature rise rate is controlled at 1-2°C / min to avoid internal stress caused by sudden temperature rise; the vacuum degree is maintained for 30 minutes during the cold pressing test, and no decrease is qualified.

[0078] Further, the temperature is raised and held in two stages (90°C±5°C for 30 minutes, 125°C±5°C for 150-210 minutes), and the holding time of 180 minutes is preferred to ensure that the resin flows gradually and is fully cured, and the pressure in the temperature range of 40-60°C can reduce resin loss.

[0079] Further, the precise curing parameter design can balance the curing efficiency and product quality, slowly release internal stress to avoid warping and size out-of-tolerance after demolding.

[0080] S5: demolding and post-processing.

[0081] Here, the to-be-molded mold 1 and the bottom surface molding mold 3 are cooled to room temperature, and then the auxiliary materials such as the vacuum bag 15, the air-permeable felt 14, the soft mold 13, the non-porous isolation film 12, the porous isolation film 11, and the strippable cloth 10 are removed in sequence, the polytetrafluoroethylene plate is used to assist the separation of the product from the mold, and the complex splicing mold needs to be disassembled in order after the bolts are removed, and the disassembly sequence follows the principle of "first auxiliary and then main body, first two sides and then middle".

[0082] Further, after demolding, the product is marked with a marker according to the mold identification, non-destructive testing is performed using an ultrasonic flaw detector according to relevant standards, and the product is judged according to the acceptance level specified in the process document. If it is unqualified, an unqualified product review sheet needs to be issued; if it is qualified, manual cutting and polishing or machine cutting are performed according to the requirements, the edge allowance is cut off, the surface excess is cleaned, and the edge is treated with a designed adhesive.

[0083] Further, the standardized demolding process avoids damage to the product, strict non-destructive testing and edge sealing treatment can effectively screen qualified products, improve the environmental performance of the product, and prolong the service life; during final inspection, the shape, size, weight, and performance test results of the product in the furnace need to be checked simultaneously, and after the product is qualified, a qualified certificate is issued, which indicates the product number, production date, and tester information. Coding marking, bubble pad packaging, and warehousing.

[0084] In the present application, in order to solve the problem of insufficient pressure and poor laying in the R angle area of the traditional T beam forming due to the softening of the resin caused by heating, through the collaborative design of the split type combinable forming mold 1, the laying mold 2, the bottom surface forming mold 3 and the flat plate 16, and the process route of "independent core material 4 prefabrication + secondary hot pressing curing", precise forming is realized. First, a unidirectional prepreg 6 with a width of 63mm is rolled into a round rod shape, and after being rolled and pressed by the core material 4 forming tool, a JE1301-B adhesive film 5 is coated on the surface of the core material 4. Through the air permeable felt 14, vacuum bag 15 packaging and independent hot sealing and pressing, the core material 4 is precisely filled in the R angle area formed by the closure of the forming mold 1 and the laying mold 2; then the positioning pin and G type clamp 7 are used to lock and fix the forming mold 1, laying mold 2 and bottom surface forming mold 3, and after the first hot sealing and pressing and pre-curing, the shape and position of the core material 4 are preliminarily fixed to avoid subsequent displacement; after pre-curing, the vacuum bag 15 and auxiliary materials are removed, and the surface of the core material 4 is trimmed (the recessed unidirectional prepreg 6 is filled, and the protruding part is scraped and supplemented with adhesive film 5), to ensure that it is slightly higher than the plane by 0.2mm; then the laying mold 2 is removed, and the prepreg is laid on the bottom surface forming mold 3, and the fabric baffle 9 is embedded on the edge of the closure surface of the forming mold 1 and the bottom surface forming mold 3, and the remaining two closure surfaces are provided with inflatable cushion pads 8 to fill the gap and seal to prevent overflow; finally, the bottom surface forming mold 3 and the forming mold 1 are closed, and the peelable cloth 10, the perforated release film 11, the non-perforated release film 12, the soft mold 13, the air permeable felt 14 and the vacuum bag 15 are sequentially laid to complete the packaging, and after the second high pressure and high temperature curing, the flexible pressing characteristics of the soft mold 13 are used to uniformly transmit the pressure to each area of the blank (especially the R angle), effectively eliminating the delamination and bridging defects, and at the same time, the laying mold 2 is made of 6061 aluminum material to reduce the weight and cost, and the flat plate 16 provides operation space for vacuum packaging. Through the cooperation and precise parameter control of all components throughout the process, the problems of traditional process are effectively solved from the aspects of mold adaptation, core material 4 support and pressure transmission, to ensure the forming quality and stability of the T beam.

[0085] The above description of the embodiments is only used to help understand the method of the present application and its core idea. It should be noted that for ordinary skilled persons in the art, without departing from the principles of the present application, some improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

Claims

1. A method of forming a composite T-beam, the method comprising: The forming die, the lay-up die and the bottom surface forming die are separately arranged and can be combined, and are formed by a two-step hot pressing and curing process, including the following steps: ​ S1: preforming and R angle preforming: pre-impregnated materials are laid on the surfaces of the forming die and the lay-up die, and an independently preformed pre-impregnated material core is positioned in the R angle area of the T-shaped beam formed after the two are closed; S2: first mold closing and pre-curing: the lay-up die and the forming die are closed, lateral auxiliary positioning is performed by the bottom surface forming die, the combined body after the mold closing is locked and fixed by positioning pins and clamping members, and first hot pressing and curing is performed; the first hot pressing and curing is hot sealing and pressing, the curing pressure is lower than that in step S4, the curing pressure of the first hot pressing and curing is 0.3-0.8 MPa, and the curing temperature is 50-80℃; S3: mold conversion and bottom surface lay-up: the lay-up die is removed, and pre-impregnated materials are laid on the surface of the bottom surface forming die; S4: second mold closing and final curing: the bottom surface forming die after the lay-up is completed is closed with the forming die after step S2, an elastic soft die is applied to the outer surface of the blank after the mold closing and is packaged, and final hot pressing and curing is performed, the curing pressure of the final hot pressing and curing is 0.5-1.0 MPa, and the curing temperature is 100-140℃; S5: demolding and post-processing.

2. The method of claim 1, wherein: In step S1, the pre-impregnated material core is formed by winding a unidirectional pre-impregnated material, a glue film is arranged on the surface thereof, and the pre-impregnated material core is pre-cured by an independent hot sealing and pressing process.

3. The method of claim 1, wherein: The specific parameters of the first hot pressing and curing are as follows: the vacuum degree is maintained at -0.10 to -0.08 MPa, the temperature is raised to 60℃±3℃ and kept constant for 10-15 minutes, then the pressure is increased to 0.6 MPa±0.05 MPa within 15-25 minutes and kept constant for 10-15 minutes.

4. The method of claim 1, wherein: Between step S2 and step S3, a step of trimming the cured surface of the core material is further included, when the core material area is recessed or protruded with a height exceeding 0.2 mm, the area is filled or scraped.

5. The method of claim 1, wherein: In step S4, a blocking strip made of a fabric pre-impregnated material laid in the 0° direction is embedded at the edge of the closing surface of the forming die and the bottom surface forming die, and the blocking strip is used to fill the gap formed by the closing of the two.

6. The method of claim 1, wherein: In step S4, the elastic soft die is made of silica gel and has a hardness of 20-60.

7. The method of claim 1, wherein: The specific parameters of the final hot pressing and curing are as follows: the vacuum degree is not less than 0.09 MPa, the temperature is raised to 125℃±5℃ at a rate of 1-2℃ / min and kept constant for 150-210 minutes, the pressure is increased to 0.6 MPa±0.05 MPa in the temperature range of 40-60℃ and kept constant throughout the process, and the temperature is lowered to below 60℃ at a rate not higher than 2℃ / min after the curing is completed.

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