Core material treatment method suitable for large-thickness special-shaped sandwich composite material

Abstract

The invention relates to the technical field of composite materials, in particular to a core material treatment method suitable for a large-thickness special-shaped sandwich composite material, and the core material treatment method specifically comprises the following steps that S1, a mold is machined according to a needed core material line; s2, processing the flat plate core material of the original plate into a thin sheet with a set thickness; s3, multiple layers of core materials are laid on the mold; s4, packaging the core material on a mold and applying pressure; s5, after the adhesive is cured; s6, trimming is conducted; s7, the lower surface of the special-shaped curved surface core material is an inner arc surface, back covering fibers are pasted on the lower surface of the core material, and shallow grooves are formed in the upper surface in a criss-cross mode. The core material structure is determined according to the mold line type, the thick plate core material is processed into the sheets and laid layer by layer, so that the core material can be tightly attached to the complex curved surface of the mold, and the problem that a gap between the core material and the mold is too large in a traditional method is solved.

Description

Technical Field

[0001] The invention relates to the technical field of composite materials, and in particular to a core material processing method suitable for thick and special-shaped sandwich composite materials. Background Art

[0002] In recent years, my country's composite materials industry has developed rapidly, especially sandwich composite materials, which are widely used in various fields such as ships, aviation, rail transportation, etc. due to their light weight and high strength. In order to meet the requirements of multiple performances, the product structure has gradually diversified, and the structure usually contains various complex special-shaped structures. In order to meet the laying requirements of special-shaped core materials, the core materials need to be processed.

[0003] Regarding the laying of core materials of special-shaped sandwich composite materials, related studies have proposed different core material processing methods.

[0004] Publication number: CN102350752B A self-guiding core material and a processing method thereof, discloses a self-guiding core material and a processing method thereof, the core material is double-sided grooved, the upper surface is transversely grooved and shallowly grooved longitudinally according to the thickness of the core material, and the lower surface is transversely grooved and shallowly grooved longitudinally according to the thickness of the core material. The core material processed by this processing method can be suitable for some curved surface mold cavities with smaller curvatures, but for large-curvature and large-thickness anisotropic curved surface structures, the core material has poor conforming effect, resulting in excessive gap between the core material and the mold cavity, more glue content, increased weight of the product, and serious impact on product performance; in addition, the core material obtained by this core material processing method has an uneven surface after laying, which is very likely to cause linear accuracy deviation, and it takes a lot of time and effort to polish the surface after molding.

[0005] Publication number: CN112476576A A design and cutting method for blunt-end core material of wind turbine blades, a foam processing method suitable for blunt-end edge of large-angle and thick blades is proposed, that is, the flat raw material is cut into trapezoidal unit blocks, and then several trapezoidal unit blocks are spliced ​​into blunt-end core material of wind turbine blades. This processing method can effectively reduce the problem of too large gaps in blunt-end core materials, but the design process of this method is complicated, the processing steps and splicing operation process are cumbersome, it is difficult to meet a wide range of applications, and the scope of application is too narrow, and the universality is low.

[0006] Publication number: CN112537050A A method for manufacturing a main beam of a wind turbine blade, by machining a V-shaped groove at the bottom of the core material to make the core material follow the shape in a curved mold, and filling the bottom gap with core material of the same material to reduce the gap. This method can make the core material follow the shape appropriately and avoid related resin-rich defects, but the core material utilization rate is not high, the core material filling in the bottom gap is difficult to operate, and glue deficiency is prone to occur during the pouring process.

[0007] Publication number: CN204140290U The core material of the wind turbine blade includes an upper and lower core material, each of which includes a core material body, a mesh glass fiber cloth adhered to the upper surface of the core material body, and a core material body with a mesh glass fiber cloth attached to the upper part, with through holes punched at intervals on one side and grooves on the bottom surface. However, the focus is on improving the core material structure design to optimize the glue flow path and improve the infusion effect and quality of the blade, and the curved surface conforming effect is not good. There are still a large number of gaps between the core materials, and there are a large number of glue-rich areas in the core material area.

[0008] Based on the current core material processing methods, most of them are suitable for the processing of certain special small-curvature and small-thickness curved core materials, and the core material utilization rate is not high, which easily leads to waste of resources. In addition, the price of core materials remains high, making it difficult to control costs. Therefore, it is necessary to develop suitable core material processing methods to meet the requirements for laying core materials of large-curvature and large-thickness heterogeneous curved structures, and to solve the problems of difficult core material laying, large gaps, and uneven surfaces caused by excessive curvature of the mold cavity during the laying process of core materials of sandwich composite materials in thick and special-shaped structures. Summary of the invention

[0009] In view of this, the present invention aims to propose a method for processing core materials of large-thickness special-shaped sandwich composite materials, so as to solve the problems of difficulty in laying core materials, excessive gaps and uneven surfaces caused by excessive curvature of the mold cavity during laying of core materials of sandwich composite materials in large-thickness special-shaped structures.

[0010] In the processing of the existing technology, the surface of the core material is uneven after laying, which can easily cause linear accuracy deviation, and it takes a lot of time and effort to polish the surface after molding. For thick and special-shaped sandwich composite materials, if too thick core material is used for direct processing, it is difficult to achieve complex curved surface modeling; conversely, if it is too thin, it may lead to insufficient structural strength. The thickness of 3mm to 5mm can provide sufficient flexibility to adapt to complex-shaped molds while ensuring a certain mechanical strength. Thinner plates are easier to cut with high precision by CNC equipment, ensuring that each piece of core material meets the design requirements, which helps to improve the consistency and accuracy of the entire product. The bonding between multi-layer thin core materials is more uniform and easier to control than a single large piece of core material. Using a thin sheet thickness of 3mm to 5mm can better disperse stress, reduce gaps and defects, and enhance the stability of the overall structure.

[0011] The present invention processes thick plate core material into thin sheets and lays them layer by layer so that the core material can fit closely to the complex curved surface of the mold, thereby solving the problem of excessive gap between the core material and the mold in the traditional method. By opening a straight groove or a cross groove on the upper surface of the core material, the resin flow can be effectively guided, and resin-rich defects caused by uneven resin distribution can be avoided, thereby reducing material waste, improving the overall utilization rate of the core material, and effectively reducing production costs. It can adapt to special-shaped hyperbolic mold cavities of various structures, has strong versatility and flexibility, and the method is simple and reasonable in design, easy to operate, greatly shortens the production cycle, and improves work efficiency.

[0012] The technical solution of the present invention is achieved in this way: The present invention discloses a method for processing core materials of thick and special-shaped sandwich composite materials, which specifically comprises the following steps: S1: Process the mold according to the required core material line shape; S2: Processing the original flat core material into thin sheets of set thickness; S3: Laying multiple layers of core material on the mold, and bonding the multiple layers of core material with adhesive; S4: Encapsulate the core material on the mold and apply uniform pressure to ensure that the core material and the mold line are consistent; S5: After the adhesive is cured, demoulding is performed to obtain a special-shaped curved surface core material; S6: trimming, processing the core material according to the actual required size to obtain a curved core material with set size and line shape; S7: The lower surface of the special-shaped curved core material is an inner arc surface, the back covering fiber is pasted on the lower surface of the core material, and a straight groove or a cross groove is opened on the upper surface, and the guide groove is a shallow groove structure.

[0013] Furthermore, in step S1, the mold is a metal mold or a fiberglass mold.

[0014] Furthermore, in step S2, the thickness of the sheet is 3 mm to 5 mm.

[0015] Furthermore, in step S3, after laying the multiple layers of core material, the total thickness is ensured to be consistent with the requirement, and the number of layers is: total thickness / sheet thickness.

[0016] Furthermore, in step S4, the vacuum pressure value reaches -0.01 MPa, and the pressure remains unchanged during the curing process of the adhesive.

[0017] Furthermore, in step S5, the adhesive is one of epoxy resin or vinyl resin, and the adhesive coating thickness does not exceed 1 mm.

[0018] Furthermore, in step S7, the back covering fibers are in a grid shape, and the back covering fibers are bonded to the core material by an adhesive.

[0019] Furthermore, in step S7, the shallow groove is formed by: the groove depth is 1.5-3 mm, and the groove width is 1-3 mm.

[0020] Furthermore, in step S4, a moldable press is used to apply pressure to the surface of the core material until the thickness of the adhesive is 0.1-0.2 mm.

[0021] Compared with the prior art, the core material processing method of the present invention, which is applicable to thick and special-shaped sandwich composite materials, has the following advantages: 1. The present invention determines the core material structure according to the mold line shape, and processes the thick core material into thin sheets and lays them layer by layer, so that the core material can fit closely to the complex curved surface of the mold, thus solving the problem of too large gap between the core material and the mold in the traditional method.

[0022] 2. The present invention can effectively guide the resin flow by opening a straight groove or a cross groove on the upper surface of the core material, avoiding the resin-rich defect caused by uneven resin distribution, reducing material waste, improving the overall utilization rate of the core material, and effectively reducing production costs.

[0023] 3. The present invention can adapt to various structures of special-shaped hyperbolic mold cavities, has strong versatility and flexibility, and the method design is simple and reasonable, easy to operate, greatly shortens the production cycle, and improves work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings: Figure 1 It is a schematic diagram of the core material structure; Figure 2 It is a schematic diagram of the core material packaging; Figure 3 This is a schematic diagram of core material grooving.

[0025] Reference numerals: 101. mold; 102. core material; 103. demolding cloth; 104. vacuum bag film; 105. sealant; 106. exhaust system; 201. shallow groove. DETAILED DESCRIPTION

[0026] In order to make the technical means, objectives and effects of the present invention easy to understand, the embodiments of the present invention are described in detail below with reference to specific drawings.

[0027] It should be noted that all the terms used in the present invention to indicate directionality and position, such as "upper", "lower", "left", "right", "front", "back", "vertical", "horizontal", "inside", "outside", "top", "lower", "lateral", "longitudinal", "center", etc., are only used to explain the relative positional relationship and connection status between the components in a certain state, and are only for the convenience of describing the present invention, rather than requiring the present invention to be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the descriptions of "first", "second", etc. in the present invention are only used for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.

[0028] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0030] The present invention discloses a method for processing core materials of thick and special-shaped sandwich composite materials, which specifically comprises the following steps: S1: Process the mold according to the required core material line shape; Use computer-aided design (CATIA) software to create three-dimensional models of the products to be manufactured, extract the linear data of the mold based on the product model, including parameters such as curvature, angle and size, and use these data to process the mold.

[0031] S2: Processing the original flat foam into a sheet of a certain thickness; Prepare the required original flat foam material, check its surface flatness and defects, use CNC cutting machine or similar precision equipment to set a certain thickness, accurately cut the flat foam according to the set parameters to obtain the required thickness of the slice, and perform quality inspection on the cut slice to ensure the size consistency and surface smoothness. This setting can reduce the rigidity of the core material, making it easier to lay it on a complex curved surface.

[0032] S3: Lay multiple layers of core material on the mold and bond the core materials with adhesive; Calculate the number of layers to be laid based on the total thickness requirement, which is calculated by dividing the total thickness by the single layer thickness. Paste a layer of release cloth on the mold, apply a layer of adhesive, such as epoxy resin or vinyl resin, evenly on the bottom core material and the surface of the release cloth, and lay the first layer of thin core material on the mold, ensuring that it fits the mold contour completely. Repeat the above steps, laying layer by layer until the predetermined number of layers is reached. Note that each layer must be evenly applied with adhesive and ensure that the layers fit tightly together. This setting can build a core material structure with an overall thickness and strength that meets the design requirements.

[0033] S4: Use vacuum bag film to encapsulate the core material on the mold, and draw a vacuum to ensure that the core material and the mold line are consistent; Cover the laid core material with a release cloth, then place the vacuum bag film and seal the edges, connect the vacuum system and apply negative pressure to the packaged core material until the vacuum pressure value is reached, and ensure that the vacuum pressure remains unchanged throughout the adhesive curing process so that the core material fits the mold contour closely. This setting ensures that the core material fits the mold surface closely to avoid gaps and deformation.

[0034] S5: After the adhesive is cured, demoulding is performed to obtain a special-shaped curved surface core material; Wait for the appropriate curing time according to the type of adhesive used, usually about 24 hours. After curing, release the vacuum system and remove the vacuum bag film and other auxiliary materials, and remove the formed special-shaped curved core material from the mold to avoid damaging its surface. Complete the initial molding and prepare for subsequent processing.

[0035] S6: trimming, processing the core material according to the actual required size to obtain a curved core material with a certain size and line shape; Use a saw, grinding wheel or other suitable tools to perform preliminary trimming of the core material edge, finely grind the trimmed edge to make it meet the size requirements on the design drawing, and finally check whether the overall shape and size of the core material meet the design specifications, and make fine adjustments if necessary. This setting can remove excess parts to ensure the dimensional accuracy of the final product.

[0036] S7: The lower surface of the special-shaped curved core material is an inner arc surface, the backing fiber is pasted on the lower surface of the core material, and a straight groove or a cross groove is opened on the upper surface. The guide groove is a shallow groove structure; A layer of adhesive is evenly applied on the lower surface of the core material, and a grid-shaped backing fiber is pasted on it to contact the mold as a flexible surface. A straight groove or a cross groove is opened on the upper surface of the core material at a specific interval as a guide groove to further optimize the resin distribution and reduce defects. This setting helps to enhance the fit between the core material and the mold, while optimizing the resin flow path and reducing defects.

[0037] This setting determines the core material structure according to the mold line shape, and by processing the thick plate core material into thin sheets and laying them layer by layer, the core material can fit closely to the complex curved surface of the mold, solving the problem of excessive gap between the core material and the mold in the traditional method. By opening a straight groove or a cross groove on the upper surface of the core material, the resin flow can be effectively guided, and the resin-rich defect caused by uneven resin distribution can be avoided, which reduces material waste, improves the overall utilization rate of the core material, and effectively reduces production costs. It can adapt to special-shaped hyperbolic mold cavities of various structures, has strong versatility and flexibility, and the method is simple and reasonable in design, easy to operate, greatly shortens the production cycle, and improves work efficiency.

[0038] Specifically, in step S1, the mold may be a metal mold or a fiberglass mold.

[0039] The metal mold first uses CATIA software to design the required mold shape, and then uses a CNC machining center or similar equipment to process the metal into a mold with a high-precision surface finish. The metal material can be aluminum, steel, etc. In order to improve demoulding performance and extend service life, the surface of the metal mold can also be specially treated, such as chrome plating or Teflon coating. This setting helps to accelerate heat transfer during the curing process, can adapt to harsh working environments, has good dimensional stability and precision, and ensures that the geometry of the final product is accurate.

[0040] The FRP mold first makes a master mold according to the product design requirements, and then uses hand lay-up, injection molding or other molding techniques to combine the reinforcement material with the matrix resin to form a mold. After that, grinding and polishing are performed to ensure the smoothness and flatness of the mold surface, so as to obtain high-quality products. The reinforcement material can be glass fiber cloth, and the matrix resin can be unsaturated polyester resin, epoxy resin, etc. This setting can be customized according to specific needs. Various complex geometric shapes, with strong adaptability, light weight, easy to carry and operate, suitable for large and complex shape mold production, and lower cost.

[0041] Specifically, in step S2, the thickness of the sheet is 3 mm to 5 mm.

[0042] The flexibility between the sheets allows them to follow the curves and angles of the mold more closely, ensuring that the final product has a high degree of consistency and accuracy. For thick and special-shaped sandwich composite materials, if too thick core materials are used for direct processing, it is difficult to achieve complex curved surface modeling; on the contrary, if it is too thin, it may lead to insufficient structural strength. The thickness of 3mm to 5mm can provide sufficient flexibility to adapt to complex-shaped molds while ensuring a certain mechanical strength. After the thick plate is divided into several thin sheets, the bending ability of the material can be significantly increased, so that it can fit more closely to the mold surface with complex geometric shapes, thereby improving the molding quality of the final product.

[0043] Compared with directly processing thick core materials, this setting makes the thin sheets after layered processing easier to operate and adjust, and is suitable for processing large-sized parts with complex curvatures.

[0044] Specifically, in step S3, after laying the multiple layers of core material, the total thickness is ensured to be consistent with the requirement, and the number of layers is: total thickness / sheet thickness.

[0045] Place the laid multi-layer core material on the mold, ensure that the adhesive is evenly applied between each layer and aligned correctly. Applying adhesive between each layer can form a stronger bond between the layers, reduce gaps and defects, and enhance the stability of the entire structure. By properly arranging the number and position of thin sheets, the distribution of resin inside the composite material can be optimized, avoiding the appearance of rich or poor areas, and improving the overall quality of the product.

[0046] This setting avoids unnecessary material waste and improves material utilization by precisely controlling the thickness and number of each layer, helping to reduce overall production costs.

[0047] Specifically, in step S4, the vacuum pressure value reaches -0.01 MPa, and the pressure remains unchanged during the adhesive curing process until the thickness of the adhesive is 0.1-0.2 mm.

[0048] Covering the core material with a layer of release cloth will help prevent the resin from penetrating into the vacuum bag film and facilitate the subsequent demoulding process. Cover the vacuum bag film on the release cloth and ensure that it is completely sealed. Use sealing tape to seal tightly along the edges to avoid any possible leaks. Connect the vacuum bag film to the exhaust system and start extracting air until the internal vacuum reaches -0.01MPa. This process requires continuous monitoring of the vacuum gauge reading to ensure that the predetermined pressure value is reached, so that the core material can fit the contour of the mold more closely, reduce gaps and unevenness, thereby improving the shape accuracy of the final product, helping to remove interlayer air, promote uniform resin penetration, reduce bubbles and other defects, and improve the quality of the product. Once the required vacuum degree is reached, the pressure must be maintained until the adhesive is fully cured. Usually, this process takes about 24 hours, depending on the type of adhesive used and its recommended curing conditions.

[0049] This setting can ensure a perfect fit between the core material and the mold, reduce linear deviations caused by gaps, and effectively prevent the appearance of resin-rich or resin-poor areas, thereby improving product consistency and reliability, reducing the workload of subsequent grinding and finishing, and improving production efficiency.

[0050] Preferably, the thickness of the adhesive is 0.1 mm.

[0051] Specifically, in step S5, the adhesive is a room temperature curing resin such as epoxy resin, vinyl resin, etc., and the coating thickness does not exceed 1 mm. The specific curing time is determined by the type of adhesive.

[0052] Determine the curing time according to the type of adhesive selected. Different types of resins have different curing temperatures and time requirements. Under normal temperature conditions, it generally takes about 24 hours to reach a fully cured state. If you need to speed up the curing speed, you can consider accelerating the curing at an appropriate temperature. Controlling the thickness of the adhesive to no more than 1mm can ensure sufficient bonding effect, minimize unnecessary material consumption, and thus reduce costs. Since the adhesive layer is thin, the curing time is relatively short, which helps to speed up the entire production process and shorten the production cycle.

[0053] Preferably, the final thickness of the adhesive is 0.1-0.2 mm.

[0054] Specifically, in step S6, the back covering fibers are in a grid shape and are bonded to the foam by an adhesive.

[0055] Lay the grid-like backing fiber flat on the surface of the core material coated with adhesive, use a roller or brush to gently press the backing fiber to make it in close contact with the surface of the core material, and remove bubbles and excess adhesive.

[0056] This setting can significantly increase the fit of the core material to the mold during use. The use of a grid-like rather than solid structure of back covering fibers can minimize the additional weight while ensuring sufficient strength, which is conducive to achieving the goal of lightweight composite materials. By pre-laying grid-like back covering fibers, the risk of deformation or damage caused by local stress concentration can be reduced in subsequent processing, simplifying the manufacturing process.

[0057] Specifically, in step S7, the shallow groove is formed by: the groove depth is 1.5-3 mm, and the groove width is 1-3 mm.

[0058] Shallow groove opening method: Considering the shallow depth of shallow grooves (1.5~3mm), you can choose a more sophisticated tool to ensure accuracy. Cutting operation: According to the design drawings, open a straight groove or a cross groove as a guide groove. When cutting, control the groove depth to 1.5~3mm and the groove width to 1~3mm, ensuring that the grooves are evenly distributed and have no burrs or irregular edges.

[0059] This setting can effectively guide the resin flow during the composite material molding process by reasonably arranging shallow grooves, avoid the appearance of rich or poor areas, reduce bubbles and other defects, thereby improving the quality of the product, reducing the workload of later grinding and finishing, and improving production efficiency.

[0060] Specifically, in step S4, a moldable press may be used to apply pressure to the surface of the core material, and uniform pressure may be applied until the thickness of the adhesive is 0.1-0.2 mm.

[0061] According to the required pressure and uniformity requirements, select the appropriate hydraulic system or pneumatic system. In order to accurately control the pressure applied to the core material, install a pressure sensor between the conformal die and the pressure system, which helps to monitor and adjust the pressure value in real time. Carefully place the conformal die above the mold with the core material laid, and ensure that it can cover the entire core area and keep an appropriate distance from the edge of the mold. Slowly increase the pressure on the conformal die through the pressure system to avoid displacement or damage of the core material due to too fast pressure changes. In the initial stage, a lower pressure value (such as 0.05MPa) can be set, and then gradually increased to the target value (usually an appropriate pressure value corresponding to a 0.1~0.2mm adhesive layer thickness). When the pressure stabilizes within the predetermined range, keep it for a period of time (determined by the curing time of the adhesive) to ensure that the core material fully adapts to the mold shape and the adhesive is evenly distributed, and to ensure that the final adhesive thickness is within the range of 0.1~0.2mm.

[0062] This setting applies uniform pressure to enable the core material to completely fit the mold surface, reducing the gap inside the core material and between the core material and the mold, thereby improving the flatness and linear accuracy of the final product. Compared with the vacuum bag method, it reduces the steps of packaging and vacuuming, reducing the difficulty and cost of operation.

[0063] By applying pressure to the core surface, excess adhesive is pressed out and removed after the core is formed. Example 1

[0064] Core material laying in sandwich composite area of ​​hull structure.

[0065] The present invention is specifically described in conjunction with the accompanying drawings. The required thickness of the sandwich composite material is 50 mm, and the thickness of the provided flat core material is 40 mm.

[0066] The foam processing steps are as follows: The first step is to determine the special-shaped core material structure according to the mold cavity line shape. Figure 1 Schematic diagram of the core material structure.

[0067] The second step is to process the flat core material into thin plates with a thickness of 5 mm.

[0068] In the third step, 10 layers of core material are laid on the mold and vinyl resin is used as adhesive to bond the core materials.

[0069] The fourth step is to use vacuum bag film to package the core material on the mold, and then evacuate the vacuum bag to ensure that the core material and the mold line are consistent. Figure 2 The entire packaging system is composed of a mold 101 , a core material 102 , a demolding cloth 103 , a vacuum bag film 104 , a sealant 105 and an exhaust system 106 .

[0070] Step 5: After 24 hours, the adhesive is cured and demolded to obtain a special-shaped curved core material.

[0071] The sixth step is trimming and processing the core material according to the actual required size to obtain Figure 1 Curved core material shown.

[0072] Step 7. Figure 3 The present invention describes a method for grooving the core material 102. Shallow grooves 201 are cut on the upper surface of the core material 102 at a certain interval. The depth of the shallow grooves is 1.5-3 mm, and the width of the shallow grooves is 1-3 mm.

[0073] Compared with the existing core material processing method, the present invention has the following advantages: (1) The present invention has a significant improvement effect on the laying of special-shaped sandwich composite materials, especially thick special-shaped structural core materials. By adopting the above core material processing method, the gap between core materials and between core materials and mold cavities can be effectively reduced, while improving the linear accuracy of the sandwich composite material structure.

[0074] (2) By reducing the gap between the core materials, the phenomenon of fiber suspension during layering is avoided, thereby eliminating the resin-rich defect, increasing the core material content in the sandwich composite structure, reducing the amount of resin, maintaining the lightweight characteristics of the composite material, effectively reducing the weight of the product, and ensuring the quality of the product.

[0075] (3) Through this core material processing method, the core material utilization rate is greatly improved, effectively saving material costs.

[0076] (4) The core material processing method of the present invention can ensure that the core material can be deformed and bent arbitrarily on a variety of special-shaped hyperbolic mold cavities, and has strong applicability.

[0077] (5) By prefabricating special-shaped core materials at large corners, the time for filling the gaps with fiber filaments and foam fragments, as well as the subsequent grinding and finishing time, is reduced, greatly shortening the production period of the product.

[0078] (6) This method has simple and reasonable design, easy operation and high production efficiency.

[0079] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for processing core materials of thick and special-shaped sandwich composite materials, characterized in that: The specific steps include: S1: Process the mold according to the required core material line shape; S2: Processing the original flat core material into thin sheets of set thickness; S3: Laying multiple layers of core material on the mold, and bonding the multiple layers of core material with adhesive; S4: Encapsulate the core material on the mold and apply uniform pressure to ensure that the core material and the mold line are consistent; S5: After the adhesive is cured, demoulding is performed to obtain a special-shaped curved surface core material; S6: trimming, processing the core material according to the actual required size to obtain a curved core material with set size and line shape; S7: The lower surface of the special-shaped curved core material is an inner arc surface, the back covering fiber is pasted on the lower surface of the core material, and a straight groove or a cross groove is opened on the upper surface of the core material as a guide groove, and the guide groove is a shallow groove structure.

2. The method for processing core materials of thick and special-shaped sandwich composite materials according to claim 1, characterized in that: In step S1, the mold is a metal mold or a fiberglass mold.

3. The method for processing core materials of thick and special-shaped sandwich composite materials according to claim 1, characterized in that: In step S2, the thickness of the sheet is 3 mm to 5 mm.

4. The method for processing core materials of thick and special-shaped sandwich composite materials according to claim 1, characterized in that: In step S3, after laying the multiple layers of core material, the total thickness is ensured to be consistent with the requirement, and the number of layers is: total thickness / sheet thickness.

5. The method for processing core materials of thick and special-shaped sandwich composite materials according to claim 1, characterized in that: In step S4, the vacuum pressure value reaches -0.01 MPa, and the pressure remains unchanged during the curing process of the adhesive.

6. The method for processing core materials of thick and special-shaped sandwich composite materials according to claim 1, characterized in that: In step S5, the adhesive is one of epoxy resin and vinyl resin, and the adhesive coating thickness does not exceed 1 mm.

7. The method for processing core materials of thick and special-shaped sandwich composite materials according to claim 1, characterized in that: In step S7, the back covering fibers are in a grid shape, and the back covering fibers are bonded to the core material by an adhesive.

8. The method for processing core materials of thick and special-shaped sandwich composite materials according to claim 1, characterized in that: In step S7, the shallow groove is formed by: the groove depth is 1.5-3 mm, and the groove width is 1-3 mm.

9. The method for processing core materials of thick and special-shaped sandwich composite materials according to claim 1, characterized in that: In step S4, a press machine is used to apply pressure to the surface of the core material until the thickness of the adhesive is 0.1-0.2 mm.

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