High-pressure casting molding method for composite material net frame

Abstract

The invention belongs to the technical field of mold pressing casting molding, and particularly relates to a composite material net frame high-pressure casting foaming molding method which comprises the steps of material preparation and mixing, mold arrangement, mold closing, casting, mold pressing reaction, curing demolding and the like. By specifically setting a raw material preparation mode, specific steps and parameters, the composite material net frame which is integrally formed, light in weight, high in strength, environment-friendly, flame-retardant, insulated, heat-insulated, corrosion-resistant, non-magnetic, long in service life, high in plasticity and the like and has a sandwich-like composite structure can be obtained.

Description

Technical Field

[0001] This invention relates to the field of injection molding technology, and in particular to a high-pressure casting molding method for composite material mesh frames. Background Technology

[0002] Existing safety barriers, including anti-throw nets, anti-glare nets, and explosion-proof barriers, are mostly made of reinforced concrete or metal. These types of barriers generally suffer from problems such as rust and corrosion, short service life, excessive weight, low construction efficiency, poor strength, and susceptibility to theft. Therefore, researchers have gradually developed polyurethane composite material nets to address these issues. Chinese invention patent publication CN121024408A discloses a polyurethane composite material safety barrier, which uses a novel polyurethane material to create a composite material safety barrier with sufficient strength, long lifespan, and recyclability. However, the frames of these composite material safety barriers are generally metal frames, which are fastened to the edges of the composite material safety barrier with bolts or other fasteners. These frames are relatively heavy and require specialized manpower and resources for installation, consuming significant amounts of manpower and resources.

[0003] Compression molding, as a highly efficient material forming method, is widely used in industrial manufacturing, especially in composite material processing. Traditional compression molding involves placing prepreg or premixed materials in a mold, then heating and pressurizing them to cure. It is suitable for producing structural components, automotive parts, and optical elements. However, directly applying existing compression molding to the installation of composite mesh frames presents the following technical problems: 1. Surface quality issues: During compression molding, the resin substrate shrinks, resulting in an uneven surface. Glass fibers or carbon fibers are easily exposed on the surface, forming twisted or wrinkled textures, severely affecting product appearance and yield. 2. Efficiency and cost limitations: Traditional single-cavity compression molding systems have low production efficiency, making it difficult to meet the needs of mass production. 3. Insufficient material adaptability: Existing processes cannot simultaneously accommodate the processing requirements of thermosetting and thermoplastic composite materials. 4. Defective protective performance: In applications such as rubber molding foam materials, products produced by traditional processes are susceptible to heat and UV aging, resulting in insufficient tensile strength and wear resistance, affecting service life.

[0004] US Patent Publication US005676894A discloses a panel frame system for heat-shrink tensioned panels. Specifically, it discloses a method and process for producing mesh panel frames by molding, which is used to mold an outer frame around a sheet or mesh of thermoplastic material to produce a frame panel. However, this technical solution does not address the issue of bonding the molded frame to the mesh, and the molding material is not suitable for the frame of composite material mesh.

[0005] Therefore, there is an urgent need to develop a frame forming process technology that can combine high efficiency with composite material mesh, meet strength requirements, and enable rapid installation. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention provides a high-pressure casting molding method for composite material mesh frames.

[0007] The present invention adopts the following technical solution: A method for high-pressure casting of composite material mesh frames, characterized by the following steps: (1) Preparation and mixing: Prepare the following components by weight: 70-85 parts of base polyol, 15-30 parts of auxiliary polyol, 5-15 parts of chemical foaming agent, 1-3 parts of catalyst, 1.5-3 parts of surfactant, 10-20 parts of physical foaming agent, 5-20 parts of short fiber and 0-30 parts of other fillers, and mix them to obtain resin paste.

[0008] (2) Mold arrangement: Apply release agent to the cavity of the upper mold and the lower mold, and preheat the upper mold and the lower mold to 45~65℃. Lay fiber mesh in the cavity of the lower mold and the upper mold respectively, then place the lower mold, place the edge of the composite material mesh between the lower mold and the upper mold, and then fasten the upper mold to close the mold.

[0009] (3) Casting: Take 105~130 parts by weight of isocyanate and mix it with the resin paste prepared in step (1) and stir at high speed to obtain a mixture. While stirring, inject the mixture into the cavity of the upper mold and the lower mold after the mold is closed.

[0010] (4) Molding and reaction: While injecting, seal the upper and lower molds, apply a pressure of 1~10MPa to the mold, and keep the mold at a temperature of 45~65℃. The mixture and fiber web undergo a polymerization reaction to form polyurethane macromolecules in the cavity and a foaming reaction is carried out at the same time. The gas generated by the foaming reaction forms a fine and uniform closed-cell structure in the pressurized space. The laid fiber web is uniformly wrapped and fixedly grown by the foam matrix generated by the reaction.

[0011] (5) Curing and demolding: After maintaining the mold pressure of 1~10MPa for 5~20min, open the mold and demold the frame to obtain the composite material mesh frame product.

[0012] Preferably, the following steps are performed after step (5): (6) Post-processing: After demolding in step (5), the composite material mesh frame is placed in an oven at 45~65℃ for post-vulcanization treatment for 8~10 hours or cured at room temperature for 24~48 hours. After removing the flash, surface treatment and / or machining, the composite material mesh frame product is obtained.

[0013] Preferably, the fiber web is one or both of polyester felt or fiberglass mesh.

[0014] Preferably, the isocyanate in step (3) is one or a mixture of diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), toluene diisocyanate (TDI) or terephthalic diisocyanate (PPDI).

[0015] Preferably, the composite material mesh has threaded ribs in the transverse direction and braided ribs in the longitudinal direction. The braided ribs are a structure woven from two or more reinforcing fiber composite resin filaments. The threaded ribs in the transverse direction are formed by winding and compositely bonding multiple reinforcing fiber monofilaments that are fully impregnated with resin and then twisted together. The reinforcing fiber composite resin is a composite structure formed by fully mixing reinforcing fibers and resin.

[0016] Preferably, annular grooves are provided on the molding planes of the upper mold and the lower mold, and polyurethane elastomer is poured or embedded in the annular grooves to form a sealing ring. The sealing in step (4) is to close the upper mold and the lower mold, with the annular grooves of the upper mold and the lower mold facing each other, and the composite material mesh is provided at intervals between at least one side of the opposing annular grooves.

[0017] Preferably, the basic polyol in step (1) is a polyol with 4 to 8 functional groups and a hydroxyl value of 350 to 500 (more specifically, polytetrahydrofuran ether diol (PTMG) or polycaprolactone (PCL)).

[0018] Preferably, the auxiliary polyol is one or more of the following: amine-initiated polyether, polyether triol, polytetramethylene ether glycol (PTMEG), hyperbranched polyol, or polyether polyol (PPG).

[0019] Preferably, the chemical foaming agent is water and glycerin or hexanediol.

[0020] Preferably, the physical blowing agent used to ensure the final density and insulation properties includes one or more of cyclopentane, hydrofluorocarbons (HFCs), 1-chloro-3,3,3-trifluoropropene (LBA), n-pentane, or dichlorofluoroethane. Preferably, the short fiber is one or more of glass fiber, basalt fiber, carbon fiber or natural fiber.

[0021] Preferably, the short fibers are fibers chopped to a length of 12-50 mm.

[0022] Preferably, the catalyst described in step (1) is used to strongly promote gel solidification and includes one or more of triethylenediamine (TEDA), bis(2-dimethylaminoethyl) ether (BDMAEE), N,N-dimethylcyclohexylamine (DMCHA), dimethylethanolamine (DMEA), N-methylmorpholine (NMM), dibutyltin dilaurate (DBTL), stannous octoate (SnOct2), or dibutyltin maleate (DBTM).

[0023] Preferably, the surfactant is used to stabilize the foam cells and make the foam cells fine and uniform, including one or more of silicone oil, polyether-modified silicone oil or polyether alkyl co-modified silicone oil.

[0024] Preferably, the other fillers are one or more of the following: tri(2-chloropropyl) phosphate (TCPP), trichloroethyl phosphate (TCEP), carbon black (the first three being flame retardants), calcium carbonate, talc, kaolin, wollastonite, barium sulfate, silica, or titanate.

[0025] Preferably, the stirring speed of the high-speed stirring in step (3) is 2000~3000 rpm and the stirring time is 3-7s; the injection pressure during injection (industrial mass production high pressure foaming machine) is 120~180 bar; the higher the pressure, the more intense the reaction and the more uniform the mixing.

[0026] A composite material mesh frame is prepared by the above-mentioned high-pressure casting molding method.

[0027] The beneficial effects of this invention are: 1. This invention improves the strength of the final frame product by specifically setting the foaming raw materials for molding, particularly by adding chopped fibers (reinforcing fibers) to a polyurethane composite material and by lining the mold with polyester felt or mesh fabric. Through heating and pressurizing in a single molding process, a lightweight, high-strength, and corrosion-resistant composite material product is produced. With the specific molding process settings, during the reaction foaming process, the molten polyurethane penetrates the mesh or felt fabric and bonds tightly, forming a strong composite material whole upon cooling. This invention achieves a product with uniform structure, high strength, and no cracking by uniformly incorporating chopped fibers into a specific polyurethane blend, ensuring good wetting, dispersion, and adhesion of the fibers while maintaining appropriate foaming speed and mixture flowability. The process involves first mixing the fibers into a resin paste, then adding isocyanate while simultaneously stirring and injecting, ensuring uniform distribution and significantly improving strength, stiffness, and impact resistance. Furthermore, by laying a fiber web (polyester felt and / or mesh fabric) on top of the chopped fibers to form a functional lining and reinforcing layer, it not only facilitates subsequent spraying or coating and absorbs impact energy but also significantly improves impact and tear resistance. These effects are not solely due to the fiber web itself but are achieved through specific laying, high-speed stirring and injection, the specific foaming setup, and the specific raw material combination. In short, this invention, based on traditional rigid polyurethane foam, significantly improves the mechanical properties and dimensional stability of the material by introducing a fiber web (polyester felt and / or mesh fabric) and a short fiber reinforcing phase, and employing a specific molding process.

[0028] 2. This invention, through a specific molding process, yields a composite material mesh frame product with a specific structure, forming a "sandwich-like composite structure." The core / skeleton of this composite material frame is a molded short-fiber reinforced polyurethane rigid foam frame, which is the main load-bearing structure. On this basis, there is an inner lining / surface layer, namely a fiber mesh (polyester felt or fiberglass mesh), which is a reinforcing layer. This reinforcing layer is mainly attached to the surface of the frame, but not entirely to the outer surface; rather, it forms an integral structure with the polyurethane rigid foam. This achieves functional integration. The interior of the frame is made of high-density, microporous, closed-cell foam with a molding or casting structure, possessing excellent structural strength and certain thermal insulation and sound insulation performance.

[0029] 3. Existing molding seals only need to seal the edges. However, since the composite material mesh processed in this invention is a specific type of rigid composite material mesh, and its edges are molded to form a frame, a portion of the composite material mesh's edge must extend into the mold, while another portion needs to be outside the mold. Therefore, the sealing requires specific design. If existing sealing methods are used, defects such as leakage will occur. This invention achieves a more efficient seal by setting a specific sealing structure. By first setting an annular groove and filling the groove with a specific soft elastic material (polyurethane elastomer (PU)), the groove is used for positioning. The soft elastic material enables efficient sealing of the specific frame of the composite material mesh used in this invention through molding.

[0030] 4. The limitation of the main components in this invention forms the basis of the preparation process. Isocyanates are selected based on their moderate reactivity, making them suitable for molding processes. Specific polyols are used to form the "soft segments" of the foam. The specific functional groups and hydroxyl values ​​ensure the product's toughness and heat resistance. Auxiliary polyols are used to adjust flowability and toughness. Chain extenders / crosslinking agents (water, glycerol, hexanediol, etc.) in the chemical foaming agent are used to improve crosslinking density and hardness. Water is the key chemical foaming agent (approximately 10 parts MDI / NDI are consumed per part of water). Physical foaming agents (cyclopentane, HFCS, etc.) determine the final density and heat insulation, forming a closed-cell foam structure. Specific catalysts are used to strongly promote gel solidification, achieving precise control of reaction rate, cell structure, and final performance. Specific short fibers are used (glass fiber is the most commonly used, cost-effective, and significantly improves strength and stiffness). It offers excellent impact resistance and can be uniformly distributed in the blend. Carbon fiber is used in cutting-edge applications requiring extremely high specific strength, specific modulus, or electrical / thermal conductivity. Natural fibers, such as flax and sisal, are used in sustainable or low-density applications and can also be blended to significantly improve strength, stiffness, and impact resistance. Optional fillers can be added to achieve flame retardancy or enhance flowability. Specific lining materials (fiber mesh) such as polyester felt can be added to improve surface smoothness, facilitate subsequent spraying or coating, and absorb a small amount of impact energy while providing some breathability and filtration. Fiberglass mesh is used as a key reinforcing layer to significantly improve impact and tear resistance. The mesh can distribute localized impact loads across the entire frame, effectively preventing breakage or penetration caused by hard object impacts, while greatly improving the overall toughness of the material, preventing crack propagation, and providing higher surface hardness and abrasion resistance to enhance its surface reinforcement. By coordinating the overall design and combining it with specific process settings, the effects of each component are enhanced and synergistic, ultimately resulting in a high-strength, lightweight, impact-resistant composite material mesh frame product with excellent structural strength and certain thermal insulation and sound insulation properties. Attached Figure Description

[0031] Figure 1 This is a bottom view of the annular groove of the upper mold according to one embodiment of the present invention.

[0032] Figure 2 This is a schematic diagram of the structure of a composite material mesh according to one embodiment of the present invention.

[0033] Figure 3 This is a top view schematic diagram of the material arrangement during the molding process according to one embodiment of the present invention.

[0034] Figure 4 This is an exploded view of the upper and lower mold structures according to one embodiment of the present invention.

[0035] Figure 5 for Figure 4 A magnified structural diagram of a portion of the structure.

[0036] Wherein: 110 - upper mold; 120 - lower mold; 101 - cavity; 102 - annular groove; 103 - injection hole; 200 - Composite material mesh; 201 - Threaded rib; 202 - Braided rib. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0038] Example 1 like Figures 1 to 5 The illustrated embodiment demonstrates a high-pressure casting molding method for a composite material mesh frame according to the present invention, comprising the following steps: (1) Preparation and mixing: Prepare the following components by weight: 78 parts of base polyol (tetrahydrofuran ether diol (PTMG)), 20 parts of auxiliary polyol (polyether triol), 10 parts of chemical foaming agent (water and ethylene glycol), 2 parts of catalyst (triethylenediamine (TEDA, amine A-33)), 15 parts of short fiber (short-cut glass fiber with an average length of 35 mm), and 15 parts of filler (flame retardant TCPP) (filler is optional). Mix them to obtain resin paste.

[0039] (2) Arrange the mold: such as Figure 4 and Figure 5(The sealing structure is not shown.) An upper mold 110 and a lower mold 120 with corresponding structural shapes and cavities are arranged as shown. A release agent is applied to the cavities 101 of the upper and lower molds, and the upper and lower molds are preheated to 55°C. Polyester felt is laid into the cavities of the lower and upper molds respectively. Then, the lower mold is placed, and the edge of the composite material mesh 200 is placed between the lower and upper molds. The upper mold is then fastened. Because annular grooves 102 are provided on the opposing planes of the upper and lower molds, the annular grooves of the upper and lower molds align during fastening. The specific sealing structure is as follows: Figure 1 As shown ( Figure 1 Only showed Figure 4 (A portion of the cavity structure is used for illustration), namely the annular groove of the upper mold sealing structure, as shown in the diagram. Figure 1 As shown, the structure of the lower mold is set opposite to the upper mold and has the same shape, thereby ensuring that the polyurethane elastomer (PU) in the annular groove can be embedded in the upper and lower annular grooves.

[0040] The fiber web described in this embodiment is polyester felt. In other embodiments, it can be fiberglass mesh.

[0041] (3) Injection: Take 108 parts by weight of isocyanate and mix it with the resin paste prepared in step (1) (i.e., the ratio of the two by weight is 1:1.3) and stir at high speed (the stirring speed in this embodiment is 2500 rpm) to obtain a mixture. The stirring time is 5s, and while stirring, the mixture is injected into the cavities of the upper and lower molds through the main inlet 103. The injection pressure is 160 bar. The isocyanate mentioned in this embodiment is diphenylmethane diisocyanate (MDI).

[0042] (4) Molding and reaction: such as Figure 3 As shown (for clearer display), Figure 3 (Only the mold closing state of one side is illustrated.) During injection, the upper and lower molds are sealed. The sealing involves closing the upper and lower molds, with the annular grooves of the upper and lower molds facing each other. Each annular groove is filled with polyurethane elastomer, and the composite material mesh is spaced apart between at least one side of each opposing annular groove. A pressure of 1-10 MPa is applied to the mold, and the mold is maintained at a temperature of 50-80°C. The mixture and polyester felt undergo a polymerization reaction within the cavity to form polyurethane macromolecules, simultaneously undergoing a foaming reaction. The gas generated by the foaming reaction forms a dense and uniform closed-cell structure within the pressurized space. The laid polyester felt is uniformly wrapped and fixedly grown by the foam matrix generated by the reaction.

[0043] (5) Curing and demolding: After maintaining a pressure of 1~10MPa for 15 minutes, open the mold and demold the frame to obtain the composite material mesh frame product.

[0044] (6) Post-processing: The composite material mesh frame obtained after demolding in step (5) is placed in an oven at 55°C for post-vulcanization for 9 hours, and then subjected to flash removal, surface treatment and / or machining to obtain the composite material mesh frame product.

[0045] like Figure 2 As shown, the composite material mesh in this embodiment has transverse threaded ribs 201 and longitudinal braided ribs 2020 (both are made of materials and structures that are not easily flattened). The braided ribs are formed by weaving polyurethane composite material into long filaments. The transverse threaded ribs are woven together with the longitudinal braided ribs to form a mesh structure. During sealing operations, this structure, due to its specific sealing structure, uses pressure to tightly press the polyurethane elastomer, which is uniformly filled in the annular groove, onto the specific, non-deformable threaded and braided ribs. This achieves efficient sealing under the specific conditions of this invention. If conventional sealing methods are used, an effective seal cannot be formed for this specific composite material mesh.

[0046] By testing the frame prepared in this embodiment, the tensile strength is found to be 20 MPa, the elastic modulus is 100 MPa, the flame retardant rating is HB, and the impact strength is 10 kJ / ㎡.

[0047] Comparative Example 1 This comparative example illustrates a comparative test using a conventional steel frame. During installation, the pre-formed steel frame is bolted to the composite mesh. This installation process takes 35 minutes, and the frame weighs 6 kg. In contrast, the frame prepared in Example 1, which has the exact same dimensions as this comparative example, weighs only 1.3 kg, less than 22% of the weight of Example 1, representing a weight reduction of at least 78%. Furthermore, Example 1 is integrally formed, requiring no installation time. This demonstrates that the composite mesh frame specifically designed in this invention, compared to existing metal frames, shortens the installation process while maintaining strength, and significantly reduces weight.

[0048] Comparative Example 2 This comparative example is used to show comparative test data without the addition of short fibers. The other settings of this comparative example are the same as those of Example 1, except that short fibers are not set in step (1). The other settings are the same as those of Example 1. The product obtained by this comparative example was tested for strength and it was found that its tensile strength was 12 MPa. That is, even if the fiber web is set in this comparative example, its strength is only 12 MPa, while the tensile strength of Example 1 is 20 MPa. That is, adjusting the addition of short fibers under the condition that other materials remain unchanged can increase the strength by more than 50%. It is generally believed that the compressive strength of pure polyurethane rigid foam mainly depends on the cell structure and the rigidity of the matrix resin. The addition of short fibers can increase the strength by 20% to 50% (depending on the fiber type, content and dispersibility, etc.). Simply adding short fibers to conventional rigid polyurethane foam materials can increase tensile strength by less than 50%, while the present invention, through comparison of Example 1 and Comparative Example 1, found that it exceeded 50%. This proves that the short fibers and fiber web in the raw materials of the present invention have a synergistic effect. The short fibers do not play an independent technical role on their own, as an independent technical role would not have such high strength. Rather, the synergistic effect is achieved through the combination of short fibers, step-by-step homogenization, and fiber web, thus achieving a synergistic technical effect greater than 2.

[0049] Comparative Example 3 This comparative example is used to show comparative test data without the addition of fiber mesh (mesh cloth or polyester felt). The other settings of this comparative example are the same as those of Example 1, except that in step (2), fiber mesh is not laid in the cavities of the lower and upper molds. The other settings are the same as those of Example 1. Strength testing of the product obtained in this comparative example revealed that its tensile strength is only 3~5MPa. This is because the fully embedded mesh cloth or polyester felt of the polyurethane rigid foam material can better withstand tensile and compressive loads through the skin effect and interface reinforcement. It also greatly improves the bending stiffness and strength of the entire composite material frame, which is at least tens of times higher than that of bare foam. At the same time, the fiber mesh, as an energy dissipation layer, can absorb and disperse external impact energy, protect the internal rigid foam, and improve crack resistance, impact resistance and penetration resistance.

[0050] Comparative Example 4 This comparative example is used to demonstrate a comparative test without employing the two-step mixing method of the present invention. In this comparative example, steps (1) and (3) are not separated. Instead, after setting up the mold, all raw materials (including isocyanate) are directly mixed in the same proportion as in Example 1 and injected while being stirred at high speed. Other settings are the same as in Example 1. The product obtained in this comparative example is subjected to strength testing, and the tensile strength of the product is 16 MPa, which is much lower than that of Example 1. This is because premixing the short fibers in advance can achieve uniform dispersion and stable suspension of the fibers, avoiding agglomeration; it helps to fully impregnate the resin and fibers, improves the interfacial bonding between the fibers and the matrix, reduces the damage of dry yarn to the cell structure, and results in better and more stable mechanical properties; thereby improving the working environment and increasing the degree of automation and stability of production. This proves that the two-step mixing method with different settings of the present invention can achieve the technical effect of improving mechanical properties, and that this setting method and the raw material configuration have a synergistic effect.

[0051] Comparative Example 5 This comparative example illustrates a comparative test using a sealing method not specific to this invention. Instead of the sealing method described in Example 1, this comparative example uses the sealing method from the US005676894A patent, with a rubber sealing strip. Other configurations are the same as in Example 1. During injection and molding, leakage was observed. This is because the mesh in the US005676894A patent is made of the same material and is non-rigid, while this invention applies to rigid threaded and braided ribs. If the existing sealing method were used, sealing quality issues would arise. This demonstrates that the sealing method specifically designed in this invention is suitable for the intended application of this invention, and also for other similar applications.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for high-pressure casting of composite material mesh frames, characterized in that, Includes the following steps: (1) Preparation and mixing: Prepare the following materials by weight: 70-85 parts of base polyol, 15-30 parts of auxiliary polyol, 5-15 parts of chemical foaming agent, 1-3 parts of catalyst, 1.5-3 parts of surfactant, 10-20 parts of physical foaming agent, 5-20 parts of short fiber and 0-30 parts of other fillers. Mix and stir evenly to obtain resin paste. (2) Mold arrangement: Apply release agent to the cavity of the upper mold and the lower mold, and preheat the upper mold and the lower mold to 45~65℃. Lay fiber mesh in the cavity of the lower mold and the upper mold respectively, then place the lower mold, place the edge of the composite material mesh between the lower mold and the upper mold, and then fasten the upper mold to close the mold. (3) Casting: Take 105~130 parts by weight of isocyanate and mix it with the resin paste prepared in step (1) and stir at high speed to obtain a mixture. While stirring, inject the mixture into the cavity of the upper mold and the lower mold after the mold is closed. (4) Molding and reaction: While injecting, seal the upper and lower molds, apply a pressure of 1~10MPa to the mold, and keep the mold at a temperature of 45~65℃. The mixture and fiber web undergo a polymerization reaction to form polyurethane macromolecules in the cavity and a foaming reaction is carried out at the same time. The gas generated by the foaming reaction forms a fine and uniform closed-cell structure in the pressurized space. The laid fiber web is uniformly wrapped and fixedly grown by the foam matrix generated by the reaction. (5) Curing and demolding: After maintaining the mold pressure of 1~10MPa for 5~20min, open the mold and demold the frame to obtain the composite material mesh frame product.

2. The high-pressure casting molding method for composite material mesh frames according to claim 1, characterized in that, Following step (5), the following steps are also performed: (6) Post-processing: After demolding in step (5), the composite material mesh frame is placed in an oven at 45~65℃ for post-vulcanization treatment for 8~10 hours or cured at room temperature for 24~48 hours. After removing the flash, surface treatment and / or machining, the composite material mesh frame product is obtained.

3. The high-pressure casting molding method for composite material mesh frames according to claim 1 or 2, characterized in that, The fiber mesh is one or both of polyester felt or fiberglass mesh.

4. The high-pressure casting molding method for composite material mesh frames according to claim 1 or 2, characterized in that, The isocyanate in step (3) is one or a mixture of diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), toluene diisocyanate (TDI) or terephthalic diisocyanate (PPDI).

5. The high-pressure casting molding method for composite material mesh frames according to claim 1 or 2, characterized in that, The composite material mesh has threaded ribs in the transverse direction and braided ribs in the longitudinal direction. The braided ribs are a structure woven from two or more reinforcing fiber composite resin filaments. The threaded ribs in the transverse direction are formed by winding and compositely bonding multiple reinforcing fiber monofilaments that are fully impregnated with resin and then twisted together. The reinforcing fiber composite resin is a composite structure formed by fully mixing reinforcing fibers and resin.

6. The high-pressure casting molding method for composite material mesh frames according to claim 5, characterized in that, Annular grooves are provided on the molding planes of the upper mold and the lower mold respectively. Polyurethane elastomer is poured or embedded in the annular grooves to form a sealing ring. The sealing in step (4) is to close the upper mold and the lower mold, and the annular grooves of the upper mold and the lower mold are arranged opposite to each other. The composite material mesh is provided between at least one side of the opposite annular grooves.

7. The high-pressure casting molding method for composite material mesh frames according to claim 1 or 2, characterized in that, The basic polyol mentioned in step (1) is a polyol with 4 to 8 functional groups and a hydroxyl value of 350 to 500; The auxiliary polyol is one or more of the following: amine-initiated polyether, polyether triol, polytetramethylene ether glycol (PTMEG), hyperbranched polyol, or polyether polyol (PPG). The chemical foaming agent is water and glycerin or hexanediol; The physical blowing agent used to ensure the final density and insulation properties includes one or more of cyclopentane, hydrofluorocarbons (HFCs), 1-chloro-3,3,3-trifluoropropene (LBA), n-pentane, or dichlorofluoroethane. The short fibers are one or more of glass fibers, basalt fibers, carbon fibers, or natural fibers.

8. The high-pressure casting molding method for composite material mesh frames according to claim 1 or 2, characterized in that, The catalyst described in step (1) is used to strongly promote gel solidification and includes one or more of triethylenediamine (TEDA), bis(2-dimethylaminoethyl) ether (BDMAEE), N,N-dimethylcyclohexylamine (DMCHA), dimethylethanolamine (DMEA), N-methylmorpholine (NMM), dibutyltin dilaurate (DBTL), stannous octoate (SnOct2), or dibutyltin maleate (DBTM); The surfactant is used to stabilize the foam cells and make the foam cells fine and uniform, including one or more of silicone oil, polyether modified silicone oil or polyether alkyl co-modified silicone oil. The other fillers are one or more of the following: tri(2-chloropropyl) phosphate (TCPP), trichloroethyl phosphate (TCEP), carbon black, calcium carbonate, talc, kaolin, wollastonite, barium sulfate, silica, or titanate.

9. The high-pressure casting molding method for composite material mesh frames according to claim 1 or 2, characterized in that, The stirring speed of the high-speed stirring in step (3) is 2000~3000 rpm, the stirring time is 3-7s, and the injection pressure during injection is 120~180 bar.

10. A composite material mesh frame, characterized in that, The composite material mesh frame is prepared by the high-pressure casting molding method according to any one of claims 1 to 9.

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