Composite material T-shaped beam forming method

Abstract

The invention discloses a composite material T-shaped beam forming method in the technical field of aviation, a forming die, a laying die and a bottom face forming die which are arranged in a split mode and can be combined are adopted, forming is conducted through a secondary hot-pressing curing process, and the method comprises the following steps that S1, preforming and R corner prefabricating are conducted, the independently-prefabricated prepreg core material is positioned in a T-shaped beam R-angle area formed after the prepreg core material and the T-shaped beam R-angle area are oppositely combined; and S2, first-time mold closing and pre-curing are carried out, specifically, the laying mold and the forming mold are oppositely closed, lateral auxiliary positioning is carried out through the bottom face forming mold, locking and fixing are carried out through a positioning pin and a clamping piece, and first-time hot-pressing curing is carried out on a combined body obtained after mold closing. According to the method, the independently prefabricated core material which is subjected to heat-sealing, pressing and pre-curing is filled in the R-angle area, and a secondary hot-pressing process of pre-curing and final curing is matched, so that sufficient pressure transmission and tight laying of the R-angle area are ensured, the defects of layering, bridging and the like are effectively avoided, and the percent of pass of nondestructive testing of products is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of aerospace technology, and more specifically, to a method for forming composite material T-beams. Background Technology

[0002] In aerospace, high-end equipment manufacturing, and other fields, T-beams, as core load-bearing structural components, are widely used in critical parts such as the leading / trailing edge ribs of aircraft wings, longitudinal frames of fuselages, and spacecraft cabin supports. Their performance directly determines the overall structural strength, rigidity, and lightweight level of the aircraft. These structural components must simultaneously meet the stringent requirements of "high strength, high modulus, and low weight." They must withstand aerodynamic loads and vibration impacts during flight while controlling their own weight to improve the equipment's endurance and maneuverability. Therefore, extremely high standards are placed on the precision, stability, and product consistency of the molding process.

[0003] Currently, the molding of these parts mainly employs an integrated mold-closing and single-stage curing process. Specifically, prepreg is first laid on each surface of the mold to form a blank, which is then assembled, molded, and placed in an autoclave for single-stage curing. To improve the molding quality of the T-beam's radius (R-angle, i.e., the transition zone between the flange and the web), some processes attempt to manually fill this area with resin filler or place a simple foam core material. Furthermore, to ensure mold rigidity, the molding die is often made of high-strength steel.

[0004] However, existing processes have certain problems in practical applications, affecting product quality and production efficiency: On the one hand, the R-angle area of ​​the T-beam, as the transition area between the flange and the web, has concentrated curvature changes. During prepreg application, wrinkles and uneven tension easily occur. Furthermore, the resin softens and flows during curing, leading to attenuation of pressure transmission in this area, making it impossible to form a uniform and effective compaction effect. This results in frequent delamination, porosity, and bridging problems. These issues not only reduce the pass rate of non-destructive testing but also significantly decrease the structural load-bearing capacity, posing flight safety hazards. On the other hand, traditional integrated molds are mostly steel structures, heavy, and inconvenient to assemble and disassemble. The positioning accuracy during molding is difficult to control, which easily leads to cavity gaps and further aggravates resin loss and uneven pressure. At the same time, the filler used by hand has poor compatibility with the prepreg resin, which easily leads to interface separation. The simple core material lacks targeted pre-curing treatment and is prone to deformation and collapse during subsequent curing, making it impossible to maintain the molding contour of the R-corner area for a long time. In addition, in the single curing process, the curing shrinkage of the blanks in different parts is not synchronized, which easily leads to internal stress concentration, resulting in warping and dimensional deviations after demolding. Subsequent correction is difficult and further increases manufacturing costs and production cycle. Therefore, we urgently need a composite material T-beam molding method to solve the above problems. Summary of the Invention

[0005] One objective of this invention is to provide a new technical solution for the molding method of composite material T-beams. By independently prefabricating and pre-curing the core material to fill the R-corner, secondary hot pressing and curing, and the coordinated use of separate molds, the problem of incomplete R-corner laying in traditional processes is solved, thereby improving the pass rate of non-destructive testing and the molding quality of the product.

[0006] The objective of this invention is achieved as follows: a method for forming composite material T-beams, employing a modular and combinable forming mold, a layup mold, and a bottom forming mold, and forming the beam through a secondary hot-pressing curing process, comprising the following steps:

[0007] S1: Preforming and R-corner preforming: Prepreg is laid on the surfaces of the forming mold and the stacking mold respectively, and the independently preformed prepreg core material is positioned in the R-corner area of ​​the T-beam formed after the two are joined together;

[0008] S2: First mold closing and pre-curing: The stacking mold and the forming mold are aligned, the bottom forming mold is used for lateral auxiliary positioning, and the assembly is locked and fixed by positioning pins and clamping parts. The assembly after mold closing is then subjected to the first hot pressing curing.

[0009] S3: Mold conversion and bottom surface lay-up: Remove the lay-up mold and lay the prepreg on the surface of the bottom surface forming mold;

[0010] S4; Second mold closing and final curing: The bottom mold that has been laid up is joined with the mold that has been processed in step S2. An elastic soft mold is applied to the outer surface of the blank after mold closing and sealed. Final hot pressing curing is then performed.

[0011] S5: Demolding and post-processing.

[0012] Optionally, in step S1, the prepreg core material is formed by rolling unidirectional prepreg into shape, covering its surface with an adhesive film, and pre-curing it through an independent heat sealing process.

[0013] Optionally, in step S2, the first hot-press curing is a heat-sealing pressure, and its curing pressure is lower than the curing pressure of the final hot-press curing in step S4.

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

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

[0016] Optionally, between step S2 and step S3, a step of trimming the cured surface of the core material is also included. When the height of the depression or protrusion in the core material area exceeds 0.2 mm, it is filled or scraped off.

[0017] Optionally, in step S4, a baffle strip made of fabric prepreg laid along the 0° direction is embedded at the edge of the mating surfaces of the forming mold and the bottom forming mold. The baffle strip is used to fill the gap formed when the two are mated.

[0018] Optionally, in step S4, the elastic soft mold is made of silicone with a hardness of 20-60.

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

[0020] Optionally, the specific parameters for the final hot-press curing are as follows: vacuum degree not less than 0.09MPa, temperature increased to 125℃±5℃ at a rate of 1-2℃ / min and held at that temperature for 150-210 minutes, pressure increased to 0.6MPa±0.05MPa in the range of 40-60℃ and held at constant pressure throughout, and after curing, temperature decreased to below 60℃ at a rate not exceeding 2℃ / min.

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

[0022] 1. According to one embodiment of the present disclosure, the composite material T-beam forming method fills the R-corner area with independently prefabricated and heat-sealed pre-cured core material, combined with a secondary hot-pressing process of "pre-curing + final curing", to ensure sufficient pressure transmission and tight bonding in the R-corner area, effectively avoiding defects such as delamination and bridging, and significantly improving the product non-destructive testing pass rate.

[0023] 2. According to one embodiment of the present disclosure, the composite material T-beam forming method reduces the mold manufacturing cost and significantly reduces the mold weight by using 6061 aluminum material instead of traditional Q345 steel for the layup mold. At the same time, the combination of split mold design and locking method with G-clamps and positioning pins improves the convenience of mold transportation, disassembly and positioning.

[0024] 3. According to one embodiment of the present disclosure, the composite material T-beam forming method uses a silicone soft mold with a hardness of 20-60 for flexible pressure application during the final curing stage, combined with fabric baffles to fill the gaps between the molds and an inflatable buffer pad to assist in sealing, to ensure that the pressure is evenly transmitted to all parts of the blank, effectively compensate for minor deviations in the mold surface, and improve the product surface accuracy and surface smoothness.

[0025] 4. According to one embodiment of this disclosure, the composite material T-beam forming method forms a full-process quality control chain by controlling details such as vacuum compaction for 15 minutes every 4 layers after standardized prepreg laying, precise trimming when the core material surface deviation exceeds 0.2mm, and synchronous laying of furnace-made parts and finished parts, thereby reducing production uncertainty and improving product molding consistency and process stability. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0027] Figure 1 This is a flow chart of the core material forming process of the present invention.

[0028] Figure 2 This is a flowchart of the T-beam forming process of the present invention.

[0029] Figure 3 This is a schematic diagram of the core material of the present invention.

[0030] Figure 4 This is a schematic diagram of the heat-sealing compression mold of the present invention.

[0031] Figure 5 This is a schematic diagram of the placement of the fabric strips according to the present invention.

[0032] Figure 6 This is a schematic diagram of the packaging of the present invention.

[0033] The diagram shows the following: 1. Molding mold; 2. Laying-up mold; 3. Bottom molding mold; 4. Core material; 5. Adhesive film; 6. Unidirectional prepreg; 7. G-clamp; 8. Inflatable cushioning pad; 9. Fabric strip; 10. Peelable fabric; 11. Perforated release film; 12. Non-perforated release film; 13. Soft mold; 14. Breathable felt; 15. Vacuum bag; 16. Flat plate. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] like Figure 1-6As shown, a method for forming a composite material T-beam uses a separate and combinable forming mold 1, a layup mold 2, and a bottom forming mold 3, and forms the beam through a secondary hot-pressing curing process, including the following steps;

[0036] S1: Preforming and R-corner preforming: Prepreg is laid on the surfaces of forming mold 1 and laying mold 2 respectively, and the independently preformed prepreg core material 4 is positioned in the R-corner area of ​​the T-beam formed after the two are joined together.

[0037] Here, first clean the surfaces of the forming mold 1, the stacking mold 2, and the flat plate 16 to ensure that the surfaces are free of impurities and scratches. Apply the release agent evenly and let it dry at room temperature for at least 30 minutes. Retrieve the electronic blanking drawing and cut the prepreg. Arrange the materials according to the layup order. Lay and prepare the furnace part sheet and the part sheet simultaneously, and the layup order and laying pressure of the two are completely consistent. Lay the prepreg on the surfaces of the forming mold 1 and the stacking mold 2 according to the sheet markings. After the first layer is laid, vacuum compact for 15 minutes. After that, vacuum compact for 15 minutes after every 4 layers are laid. At the same time, independently prefabricate the prepreg core material 4 to ensure accurate filling of the R-corner area.

[0038] Furthermore, when prefabricating the core material 4, a unidirectional prepreg 6 with a width of 63mm is rolled into a round rod and placed into a core material 4 forming fixture that has been cleaned in advance and is free of impurities. It is then rolled and pressed with an electric iron (temperature not exceeding 60℃) to ensure that the core material 4 is completely fitted to the fixture, thus ensuring that the shape of the core material 4 matches the R-angle contour.

[0039] Furthermore, after the core material 4 is prefabricated, it can be adapted to the mating gap between the molding mold 1 and the stacking mold 2 in advance, so as to avoid displacement during subsequent mold closing and lay the foundation for the compaction quality of the R-corner area.

[0040] In step S1, the prepreg core material 4 is formed by rolling unidirectional prepreg 6, then covering its surface with adhesive film 5, and pre-curing it through an independent heat sealing process.

[0041] Here, a layer of JE1301-B adhesive film 5 is laid flat on both the top and bottom of the core material 4 and ironed flat with an electric iron. Then, a non-porous release film, a breathable felt 14, and a vacuum bag 15 are laid on the surface of the core material 4 in sequence. After strictly implementing the leak test procedure (ensuring no air leaks), it is sent into the autoclave for heat sealing to ensure the pre-curing effect of the core material 4.

[0042] Furthermore, during heat sealing, the process strictly follows the procedure of "evacuating to -0.090~-0.10MPa → pressurizing to 0.62MPa in 20 minutes → heating to 58℃ at 1.3℃ / min → holding the temperature at 55℃ for 10~11 minutes." Vacuum data is monitored in real time during the evacuation process. If the vacuum level drops, the machine must be stopped immediately to check for leaks, ensuring uniform curing of the core material 4.

[0043] Furthermore, the independently pre-cured core material 4 has higher strength, which can prevent deformation and collapse during subsequent mold closing and curing processes, effectively solving the problem of incomplete tiling in the R-corner area in traditional processes.

[0044] S2: First mold closing and pre-curing: The stacking mold 2 and the forming mold 1 are aligned, and the bottom forming mold 3 is used for lateral auxiliary positioning. The mold is locked and fixed by positioning pins and clamping parts, and the assembly after mold closing is subjected to the first hot pressing curing.

[0045] Here, the stacking mold 2 is placed above the forming mold 1 for precise alignment, and the pre-made core material 4 is embedded. The bottom forming mold 3 fits against the sides of both to achieve lateral positioning. Positioning is achieved by inserting positioning pins through pin holes. After the positioning pins are inserted, the verticality needs to be checked to avoid uneven mold closing gap caused by mold tilting. Then, G-type clamps 7 are used to lock symmetrically to prevent mold misalignment.

[0046] Furthermore, when locking, control the force of the G-clamp 7 to be uniform to avoid deformation of the mold under stress. After the mold is closed, check the fitting gap of the forming mold 1, the stacking mold 2 and the bottom forming mold 3 to ensure that there are no obvious gaps before sealing.

[0047] Furthermore, this mold-closing method offers precise positioning and convenient assembly and disassembly. Additionally, the stacking mold 2 is made of 6061 aluminum (compared to traditional Q345 steel), which reduces mold manufacturing costs and weight, facilitates transportation, and significantly improves operational efficiency.

[0048] In step S2, the first hot-press curing is a heat-sealing pressure, and its curing pressure is lower than the curing pressure of the final hot-press curing in step S4. The curing pressure of the first hot-press curing is 0.3MPa to 0.8MPa, and the curing temperature is 50℃ to 80℃. The specific parameters of the first hot-press curing are: the vacuum degree is maintained at -0.10MPa to -0.08MPa, the temperature is raised to 60℃±3℃ and held for 10-15 minutes, and then the pressure is increased to 0.6MPa±0.05MPa within 15-25 minutes and held for 10-15 minutes.

[0049] Here, the first heat sealing is performed using low-pressure and low-temperature parameters, which achieves the initial bonding between the core material 4 and the prepreg blank, while avoiding premature resin flow and loss due to high temperature and high pressure.

[0050] Furthermore, the heating rate is controlled at 1.8℃ / min. Based on the hysteresis thermocouple temperature, the temperature is raised to 63℃. When the hysteresis thermocouple reaches 55℃, the temperature is held for 10-11 minutes. Then, the pressure is increased to 0.62MPa within 20 minutes and held for 10-11 minutes to ensure uniform temperature in all areas of the forming mold 1, the stacking mold 2, and the bottom forming mold 3.

[0051] Furthermore, low-pressure pre-curing can initially fix the position of the core material 4, preventing the core material 4 from shifting during subsequent mold conversion, while reserving sufficient resin flow space for the R-corner area, thus improving the final curing quality.

[0052] Between step S2 and step S3, there is also a step of trimming the cured surface of the core material 4. When the height of the depression or protrusion in the core material 4 exceeds 0.2mm, it is filled or scraped off.

[0053] Here, after removing the vacuum bag 15 and auxiliary materials, first check the surface condition of the core material 4. Ideally, the core material 4 area should be slightly higher than the plane by 0.2mm. If a depression appears, gently scrape off a layer of JE1301-B adhesive film 5 on the surface, fill it with a layer of SYT49S-J / E1301 unidirectional prepreg 6, iron it flat, and then re-apply the adhesive film 5. If the protrusion height exceeds 0.2mm, scrape off the protruding part with a blade, add adhesive film 5, and iron it flat with an absorbent cloth.

[0054] Furthermore, special tools are used during the trimming process, and the absorbent cloth must be kept dry and clean to avoid contaminating the surface of the core material 4 and to avoid damaging the surrounding prepreg blanks, so as to ensure that the surface contour of the core material 4 matches the theoretical profile after trimming.

[0055] Furthermore, precise trimming can eliminate shape deviations after the core material 4 is pre-cured, ensuring that the core material 4 is tightly bonded to the prepreg laid on the bottom surface, avoiding the formation of gaps that could lead to delamination and bridging defects.

[0056] S3: Mold conversion and bottom surface lay-up: Remove the lay-up mold 2 and lay the prepreg on the surface of the bottom surface forming mold 3.

[0057] Here, when removing the stacking mold 2, handle it gently to avoid collision with the blank on the forming mold 1; lay the prepreg on the surface of the bottom forming mold 3 according to the material sheet markings. After the first layer is laid, vacuum compact for 15 minutes, and then vacuum compact for 15 minutes every 4 layers to ensure that the bottom blank is laid tightly.

[0058] Furthermore, the prepreg on the bottom surface is aligned with the blank on the forming mold 1 during the laying process to avoid misalignment that could lead to product size deviation. The prepreg is laid synchronously with the furnace part sheet and the part sheet, and the number of layers and the compaction time are recorded simultaneously during the laying process to ensure the accuracy of performance testing.

[0059] Furthermore, after mold conversion, the bottom surface can be laid out separately, which allows for targeted control of the laying quality of the bottom surface blank and avoids the problem of limited bottom surface laying when using traditional integrated molds. The flat plate 16 provides ample operating space for this process.

[0060] S4; Second mold closing and final curing: The bottom mold 3 that has been laid up is joined with the mold 1 that has been processed in step S2. An elastic soft mold 13 is applied to the outer surface of the blank after mold closing and sealed, and then the final hot pressing curing is performed.

[0061] Here, the bottom forming mold 3 is precisely aligned with the forming mold 1, and after being symmetrically clamped with G-clamps 7, a release cloth is wrapped around it. The G-clamps 7 are then removed to avoid indentations. On the outer surface of the blank, a flat peelable cloth 10, a perforated release film 11, a non-perforated release film 12, a soft mold 13, a breathable felt 14, and a vacuum bag 15 are laid in sequence. The soft mold 13 must completely cover the outer surface of the blank, without any omissions or wrinkles, to ensure a tight seal without air leakage.

[0062] Furthermore, before closing the mold, check the gap between the forming mold 1 and the bottom forming mold 3 to ensure that the fabric baffle 9 and the inflatable buffer pad 8 are installed in place. When sealing, the vacuum bag 15 is tightly attached to the breathable felt 14 to avoid wrinkles that may affect the vacuum effect.

[0063] Furthermore, the secondary mold closing adopts a precise mold docking design, which, combined with subsequent high-pressure curing, can achieve uniform pressure transmission in all parts of the blank, greatly improving the overall molding quality of the product.

[0064] In step S4, a baffle strip made of fabric prepreg laid along the 0° direction is embedded at the edge of the mating surfaces of the forming mold 1 and the bottom forming mold 3. The baffle strip is used to fill the gap formed when the two are mated.

[0065] Here, the baffle is a fabric baffle 9, made of HF20-3K / E1301 prepreg fabric, laid along the 0° direction, with a thickness equal to or slightly lower than the rib strip, and a width that just fills the gap between the mating parts to achieve seamless filling; after placement, press it gently by hand to fix it in place to prevent displacement during subsequent operations.

[0066] Furthermore, inflatable buffer pads 8 are provided on the other two mating surfaces of the molding mold 1 and the bottom molding mold 3, which, together with the fabric baffle strips 9, form an all-round seal to prevent resin from overflowing during curing.

[0067] Furthermore, the combined design of the fabric baffle 9 and the inflatable buffer pad 8 not only fills the mold closing gap, but also adapts to changes in pressure, ensuring that the pressure is evenly transmitted to the edge of the blank and avoiding insufficient local pressure.

[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 material with a hardness controlled between 20 and 60, which has good flexibility and compressive strength and can completely conform to the surface contour of the blank.

[0070] Furthermore, the soft mold 13 is laid out to ensure that there are no air bubbles or wrinkles, and that it fits tightly with the non-porous isolation membrane 12 to ensure the continuity of pressure transmission.

[0071] Furthermore, the flexible pressure characteristics of the silicone soft mold 13 can effectively compensate for minor deviations in the surface of the molding mold 1 and the bottom molding mold 3, avoiding local pressure damage caused by rigid pressure and improving the surface smoothness and surface accuracy of the product.

[0072] In step S4, the final hot-press 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 process employs a high-pressure, high-temperature parameter range to meet the curing requirements of composite materials, ensuring that the resin is fully cross-linked and cured, thereby improving the mechanical properties of the product.

[0074] Furthermore, the matching design of curing pressure and temperature avoids damage to the fibers of the unidirectional prepreg 6 due to excessive pressure, or degradation of the resin in the film 5 due to excessive temperature, thus balancing product strength and durability.

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

[0076] The specific parameters for the final hot-press curing are as follows: vacuum degree not less than 0.09MPa, temperature rise to 125℃±5℃ at a rate of 1-2℃ / min and then hold at that temperature for 150-210 minutes, pressurize to 0.6MPa±0.05MPa in the 40-60℃ range and maintain constant pressure throughout, and after curing, cool down to below 60℃ at a rate not exceeding 2℃ / min.

[0077] Here, the vacuum is drawn to a level of not less than 0.092 MPa at room temperature. The vacuum bag 15 is sealed tightly by cold pressure test. The heating rate is controlled at 1-2℃ / min to avoid internal stress caused by sudden temperature rise. The vacuum level is maintained for 30 minutes during the cold pressure test. If there is no drop, it is considered qualified.

[0078] Furthermore, the temperature is raised and held in two stages (90℃±5℃ for 30 min and 125℃±5℃ for 150-210 min), with a preferred constant temperature duration of 180 min to ensure that the resin flows gradually and cures fully. Pressurization in the 40-60℃ range can reduce resin loss.

[0079] Furthermore, the precise curing parameter design can balance curing efficiency and product quality, and the slow cooling effectively releases internal stress, preventing warping and dimensional deviations after product demolding.

[0080] S5: Demolding and post-processing.

[0081] Here, after the forming mold 1 and the bottom forming mold 3 have cooled to room temperature, the vacuum bag 15, breathable felt 14, soft mold 13, non-porous isolation film 12, porous isolation film 11, peelable cloth 10 and other auxiliary materials are removed in sequence. Polytetrafluoroethylene sheet is used to help the parts detach from the mold. For complex splicing molds, the bolts must be removed first and then the molds are disassembled in an orderly manner. The disassembly sequence follows the principle of "auxiliary materials first, then main body, and both sides first, then middle".

[0082] Furthermore, after demolding, mark the parts with a marker according to the mold markings, use an ultrasonic flaw detector to perform non-destructive testing according to relevant standards, and judge the acceptance level according to the process documents. If it is unqualified, a non-conforming product review form shall be issued. After passing the test, perform manual cutting and grinding or machine cutting as required, remove the edge excess and clean the surface excess, and seal the edges with the design-permitted adhesive.

[0083] Furthermore, a standardized demolding process avoids damage to the parts, and strict non-destructive testing and edge sealing can effectively screen qualified products, improve the environmental resistance of the parts, and extend their service life. During the final inspection, the shape, size, weight of the parts and the performance test results of the parts in the furnace must be checked simultaneously. After passing the inspection, a certificate of conformity is issued, indicating the part number, production date, and information of the inspector. The parts are then coded, marked, and packaged with bubble wrap before being put into storage.

[0084] In this invention, the problem of insufficient pressure and incomplete bonding in the R-corner area due to resin softening under heat in traditional T-beam molding is addressed by the coordinated design of a split, combinable molding mold 1, a layup mold 2, a bottom molding mold 3, and a flat plate 16. Combined with a process route of "independent core material 4 prefabrication + secondary hot-pressing curing," precise molding is achieved. First, a 63mm wide unidirectional prepreg 6 is rolled into a round rod, which is then rolled and bonded by the core material 4 molding tooling. Finally, JE1301-B is applied to its surface. The adhesive film 5, encapsulated by the breathable felt 14 and vacuum bag 15, and independently heat-sealed to form the core material 4, is precisely filled into the R-corner area formed by the mating of the molding mold 1 and the layup mold 2. The molding mold 1, layup mold 2, and bottom molding mold 3 are then locked and fixed with positioning pins and G-clamps 7. After the first heat-sealing and pre-curing, the shape and position of the core material 4 are initially fixed to prevent subsequent displacement. After pre-curing, the vacuum bag 15 and auxiliary materials are removed, and the surface of the core material 4 is trimmed (depressions are filled with unidirectional prepreg 6, protrusions are filled with unidirectional prepreg 6). After scraping, add adhesive film 5), ensuring it is slightly higher than the plane by 0.2mm; then remove the stacking mold 2, lay prepreg on the bottom forming mold 3, embed fabric baffles 9 at the edge of the mating surface of the forming mold 1 and the bottom forming mold 3, and set inflatable buffer pads 8 at the other two mating surfaces to fill gaps and seal against overflow; finally, align the bottom forming mold 3 with the forming mold 1, and lay peelable fabric 10, porous isolation film 11, non-porous isolation film 12, soft mold 13, breathable felt 14, and vacuum bag 15 in sequence to complete the sealing. After a second high-pressure and high-temperature curing, the pressure is evenly transmitted to all areas of the blank (especially the R corner) by the flexible pressurizing characteristics of the soft mold 13, effectively eliminating delamination and bridging defects. At the same time, the stacking mold 2 is made of 6061 aluminum to reduce weight and cost, and the flat plate 16 provides operating space for vacuum sealing. Throughout the process, through the coordination of various components and precise parameter control, the traditional process problems are effectively solved from three aspects: mold adaptation, core material 4 support, and pressure transmission, ensuring the forming quality and stability of the T-beam.

[0085] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method of forming a composite T-beam, the method comprising: The forming die, the lay-up die and the bottom 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 preparation: pre-impregnated materials are laid on the surfaces of the forming die and the lay-up die, and an independently prepared 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, the bottom forming die is used for lateral auxiliary positioning, the positioning pin and the clamping part are locked and fixed, and the combined body after the mold is closed is subjected to first hot pressing and curing; S3: mold conversion and bottom lay-up: the lay-up die is removed, and pre-impregnated materials are laid on the surface of the bottom forming die; S4: second mold closing and final curing: the bottom forming die after the completion of the lay-up is closed with the forming die after the S2 step, an elastic soft mold is applied to the outer surface of the blank after the mold is closed, and is packaged, and is subjected to final hot pressing and curing; 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 is independently subjected to a heat sealing and pressing process for pre-curing.

3. A method of forming a composite T-beam according to claim 1 or 2, wherein: In 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 step S4.

4. The method of claim 3, wherein: 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.

5. The method of claim 4, wherein: The specific parameters of the first hot pressing and curing are that the vacuum degree is maintained at -0.10 MPa to -0.08 MPa, the temperature is raised to 60°C±3°C, and then kept constant for 10-15 minutes, then pressurized to 0.6 MPa±0.05 MPa within 15-25 minutes and kept constant for 10-15 minutes.

6. 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, and when the core material area is recessed or protruded with a height exceeding 0.2 mm, it is subjected to filling or scraping treatment.

7. 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 forming die, and the blocking strip is used to fill the gap formed by the closing of the two.

8. The method of claim 1, wherein: In step S4, the elastic soft mold is made of silica gel material, and the hardness is 20-60.

9. The method of claim 1, wherein: In step S4, the curing pressure of the final hot pressing and curing is 0.5 MPa to 1.0 MPa, and the curing temperature is 100°C to 140°C.

10. The method of claim 9, wherein: The specific parameters of the final hot pressing and curing are that 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 kept constant for 150-210 minutes, the pressure is started to be increased to 0.6 MPa±0.05 MPa in the temperature range of 40-60°C and kept constant throughout the process, and after the curing is completed, the temperature is lowered to below 60°C at a rate not higher than 2°C / min.

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