Composite material interlayer connection method and corresponding composite material

Abstract

The invention relates to the technical field of composite material connection, and discloses a composite material interlayer connection method and a corresponding composite.The composite material interlayer connection method comprises the three procedures of manufacturing an inlay, manufacturing a bottom layer and manufacturing a surface layer, the inlay comprises a bottom layer insert and a surface layer insert, the bottom layer insert is embedded into the bottom layer, and the surface layer insert is embedded into the surface layer. The surface layer insert is embedded in the surface layer, the surface layer insert is fixedly connected with the bottom layer insert, and the insert is used for realizing fixed connection of the enhanced surface layer and the bottom layer. The composite material produced by the composite material interlayer connection method has the characteristics of high connection strength, low process risk, designable connection strength, low manufacturing cost and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material connection, and in particular to a composite material interlayer connection method and a corresponding composite material. Background Art

[0002] Composite multilayer connection materials have many advantages such as enhanced structural strength and stiffness, optimized material utilization, improved fatigue resistance, improved environmental resistance, flexible design, reduced weight, improved manufacturing precision and multifunctional integration. These advantages have made composite multilayer connection processes widely used in aerospace, automobile manufacturing, construction and other fields.

[0003] At present, the main ways to connect composite materials between layers include mechanical connection, bonding, Z-Pin connection, suture connection, fusion welding and hybrid connection. Mechanical connection, such as bolt connection, requires drilling holes on the surface of the composite web, which destroys the structural integrity of the composite material and causes local stress concentration, reducing the connection efficiency; under special environments, metal connectors are prone to electrochemical corrosion, and the connecting bolts need to be treated with corresponding anti-corrosion technology. The bonding method often cannot effectively guarantee the structural safety of composite components under fatigue due to the bonding strength of the adhesive. Suture connection has high requirements for suture materials, equipment, and processes. Fusion welding is a connection method unique to thermoplastic composites. Hybrid connection is a comprehensive use of multiple connection methods.

[0004] The Z-Pin connection technology draws on the method of stitching discontinuous seams in composite materials. A rigid short rod is directly embedded in the thickness direction of the prepreg or foam interlayer before curing. This short rod is called a Z-Pin. Z-Pin materials can be made of metal (such as stainless steel, aluminum alloy and titanium alloy, etc.) or non-metal (such as carbon fiber, glass fiber and Kevlar, etc.). Metal Z-Pins are often used in composite materials with high requirements for interlaminar shear performance, while non-metal Z-Pins are mainly used for conventional toughening of materials.

[0005] Z-Pin connection technology between composite layers is of great significance in fields such as aerospace, automobiles, ships, construction, sports equipment, etc. that require high-strength and lightweight materials, and provides a new and effective solution for the connection of composite materials. With the widespread application of composite materials in various fields, the performance requirements for composite materials are also getting higher and higher. As an effective interlayer reinforcement method, Z-Pin technology has broad development prospects. However, in practical applications, Z-Pin technology also faces some challenges, such as how to further improve the bonding strength between Z-Pin and the composite matrix.

[0006] At present, the connection between the surface layer and the web of the composite material is generally achieved through bolt connection. In this structure, the web is a metal frame structure, and the bolts are fixed by drilling and tapping on the surface of the metal frame structure. However, with the improvement of composite material application technology and the urgent need for composite material weight reduction, the web is gradually transformed from a metal structure to a composite material. After the composite material frame web is formed, the core material is filled and processed to complete the composite material bottom layer, and then the surface layer is formed on the bottom layer surface. In this structure, the connection between the composite material frame web and the surface layer is only through resin bonding. The low connection strength can easily lead to delamination and debonding between the composite material surface and the web, resulting in connection failure.

[0007] Chinese patent CN111452395A discloses a curved composite material connection structure, molding method and rail vehicle. The invention provides a plurality of thickening sheets on the bonding surface of the composite curved surface skin, and makes these thickening sheets contact the outer surface of the connecting beam, and fills the bonding layer between the two, thereby improving the firmness and sealing of the bonding and reducing the difficulty of processing. The invention belongs to the composite material connection by bonding, and although it does not destroy the structural integrity of the composite material, it is restricted by the bonding strength of the adhesive and cannot effectively guarantee the structural safety of the composite material components under fatigue.

[0008] Chinese patent CN104847595A discloses a Z-pin reinforced composite wind turbine blade structure and its manufacturing method. This structure improves the connection strength and fatigue resistance by implanting Z-pins at the joints between the main beam and the upper and lower blade shells. The invention solves the problem of low joint surface strength in traditional bonding methods, and significantly improves the overall performance of wind turbine blades. However, the invention is a unique process and method for the manufacture of wind turbine blades, and uses a nail gun to shoot Z-pins point by point at high speed, which is more suitable for curved structures. The present invention is applicable to various composite material plate structures, and has obvious differences from them in terms of the preparation of Z-pins, the combination with the composite material matrix, and the process flow. Summary of the invention

[0009] In view of this, the present invention aims to propose a composite material interlayer connection method and a corresponding composite material to further improve the bonding strength between the inlay and the composite material matrix, which has the advantages of high connection reliability, low process risk, designable connection strength, freely controllable insert spacing, and low manufacturing cost.

[0010] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0011] A composite material interlayer connection method includes three steps of making an inlay, making a bottom layer, and making a surface layer. The inlay includes a bottom layer insert and a surface layer insert. The bottom layer insert is embedded in the bottom layer, and the surface layer insert is embedded in the surface layer. The surface layer insert and the bottom layer insert are fixedly connected. The inlay is used to achieve a fixed connection between the enhanced surface layer and the bottom layer. Since the bottom layer insert and the surface layer insert are fixedly connected as one body, the inlay actually forms a new Z-pin. This method innovates the Z-pin structure and significantly improves the overall load-bearing capacity and durability. At the same time, the split design can flexibly select the appropriate insert shape according to the material and thickness of the surface layer and the bottom layer, which provides convenience for actual production. At the same time, this also provides a variety of bottom layer and surface layer combinations to meet various specific needs.

[0012] Furthermore, the surface of the bottom layer insert extending in the length direction is taken as the side surface, and at least one of the side surfaces is recessed inwards in the middle section. This arrangement provides a larger connection area and enhances the bonding strength with the base material.

[0013] Furthermore, when making the inlay, the surface of the inlay is treated to improve the bonding strength, including: knurling, sandblasting, grooving and other treatments on the surface, making regular raised or recessed patterns on the surface of the connector to increase friction and contact area; optimizing the surface geometry such as threaded and barbed designs to further enhance the mechanical interlocking effect between the inlay and the base material.

[0014] Furthermore, the surface of the inlay is processed by providing a groove perpendicular to the side surface of the bottom inlay. The groove can be in various shapes, and a square groove is preferred for the convenience of processing.

[0015] Furthermore, the bottom layer includes a web, and the manufacturing of the bottom layer includes: the first step of connecting the bottom layer insert with the web to form a web frame; the second step of filling the web frame with core material to form a core mold; the third step of performing injection molding of the core mold to complete the manufacturing of the bottom layer. The constructed web frame is the main force-bearing component, and the core material plays a structural filling role.

[0016] Furthermore, the bottom layer insert is connected to the web by integrated molding or step-by-step molding. These are two solutions for connecting the bottom layer insert to the web, and either one can be used.

[0017] Furthermore, the web and the bottom layer insert are connected by integrated molding, including the following steps:

[0018] Step 1: Wind glass fiber yarn or prepreg in the direction of vertical height on the surface of the bottom insert, fill the groove on the surface of the bottom insert, and continue to wind the surface of the bottom insert with glass fiber cloth or prepreg of different widths in the same direction until the depression of the bottom insert is filled;

[0019] Step 2: implanting the bottom layer insert into the web preform;

[0020] Step 3: Orthogonally lay the fiber fabric, then lay the release cloth and guide net in sequence, and complete the web forming through molding.

[0021] By integrating the web and the bottom insert, the surface connection between the composite material and the bottom insert is consistent in all directions. This design makes the stress distribution uniform when loaded, thus ensuring excellent connection strength.

[0022] Furthermore, the connection between the web and the bottom layer insert is formed in steps, including the following steps:

[0023] Step 1: Use sandpaper to roughen the fixing surface between the belly plate and the bottom insert, and remove dust from the belly plate surface;

[0024] Step 2: Sandblast the connection area between the bottom insert and the web and fix them with adhesive;

[0025] Step 3: Orthogonally lay the fiber fabric in the bonding area between the bottom insert and the web, with the bottom insert located between the fiber fabric and the web, then lay the release cloth and guide net, and finally perform bag film sealing and vacuum assisted molding to form a bottom insert fixed composite material, thereby completing the bottom insert fixation.

[0026] The step-by-step molding of the web and the bottom insert is another alternative for connecting the two, which can provide a suitable option according to specific needs.

[0027] Furthermore, the manufacturing of the surface layer comprises the following steps:

[0028] Step 1: The surface insert is fixedly connected to the bottom insert;

[0029] Step 2: Laying the surface fiber fabric on the bottom surface;

[0030] Step 3: The composite material surface layer is infused and molded to complete the connection between the bottom layer and the surface layer of the composite material.

[0031] By connecting the surface layer to the bottom layer, many advantages of multi-layer connection of composite materials can be achieved.

[0032] Furthermore, when performing step 2 to lay the surface fiber fabric on the bottom surface, the fiber fabric is opened at the bottom layer insert and passes through the surface insert until the fabric and the upper surface of the surface insert are at the same height; the fiber fabric laid subsequently is not opened. This operation makes the inlay and the fiber fabric layup closely combined, achieving the effect of optimizing the internal stress distribution and improving the overall strength.

[0033] Furthermore, the opening shape is a straight hole, and the opening directions of two adjacent layers of fabric are perpendicular. The opening direction is refined, so that the fabric and the inlay fit more closely, and the bonding strength between the inlay and the composite material matrix is ​​improved.

[0034] Furthermore, a composite material is produced by the composite material interlayer connection method as described above. The product produced by this method has various advantages of composite material multilayer connection and has outstanding advantages in structural strength and rigidity.

[0035] Compared with the prior art, the composite material interlayer connection method and the corresponding composite material described in the present invention have the following advantages:

[0036] 1. Significantly improve interlaminar strength: The present invention can significantly improve the interlaminar fracture toughness and interlaminar shear strength of the laminate, overcoming the disadvantage of low interlaminar shear strength of the traditional pressure-bearing plate.

[0037] 2. Avoid stress concentration: The present invention does not destroy the integrity of the composite material, can avoid the reduction in strength of the mechanical connection caused by stress concentration caused by drilling, reduce fatigue damage, and extend the service life.

[0038] 3. Improve reliability: The bonding strength between the inlay and the composite material matrix is ​​further improved, the inlay spacing can be freely controlled, and the connection reliability is high.

[0039] 4. Reduce costs: Select appropriate materials according to the needs of different layers to achieve the best configuration of materials, which is lower in cost than other methods; at the same time, a more precise manufacturing process can be achieved to ensure good bonding between layers and improve product quality.

[0040] 5. Wide range of applications: Different layers can integrate multiple functions, such as conductivity, heat insulation, sound absorption, etc.; the number of layers and material combinations can be flexibly adjusted according to specific application requirements, and the insert spacing can also be freely controlled to meet diverse design requirements; the appropriate insert form can be flexibly selected according to the material and thickness of the surface and bottom layers, providing convenience for actual production.

[0041] 6. Strong environmental adaptability: Different material layers can provide different protection functions, and the product has no problems such as electrochemical corrosion and moisture absorption.

[0042] The present invention optimizes the shape and material of the inlay without destroying the integrity of the composite material, and innovates the processing steps. It is an application innovation and practical expansion of the Z-Pin connection technology between composite layers, and can be applied to the production of all-composite frame + surface structure products. Its products can be used to connect the surface layer of large composite materials with the composite skeleton, such as wind turbine blades, cruise ships, etc.

[0043] BRIEF DESCRIPTION OF THE DRAWINGS The 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 drawings:

[0044] Figure 1 A connection diagram of the bottom layer and the surface layer described in Example 1 of the present invention;

[0045] Figure 2 This is a structural diagram of the bottom layer insert after being implanted into the belly plate according to Embodiment 1 of the present invention;

[0046] Figure 3 This is a structural diagram of the bottom layer insert according to Embodiment 2 of the present invention after being implanted into the belly plate;

[0047] Figure 4 This is a diagram showing the relationship between the bottom layer structure after the core material is filled as described in Example 2 of the present invention;

[0048] Figure 5 This is a directional diagram of adjacent fabric openings of the surface layer insert described in Example 1 of the present invention;

[0049] Figure 6 Five views of the bottom layer insert described in Example 2 of the present invention.

[0050] Description of reference numerals:

[0051] 1. Bottom layer insert; 2. Bottom layer insert fixing composite material; 3. Web; 4. Surface layer; 5. Surface layer insert; 6. Core material. DETAILED DESCRIPTION

[0052] 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.

[0053] It should be noted that all the terms used in the present invention for directional and positional indications, 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 (as shown in the accompanying drawings), 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.

[0054] 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.

[0055] 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.

[0056] Example 1

[0057] A composite material interlayer connection method comprises the following steps:

[0058] Step 1: Making the inlay.

[0059] The inlay can be one-piece or split, and the material can be metal or non-metal.

[0060] The inlay of the present invention is columnar or stick-shaped, and the cross-sectional shape can be circular, polygonal, etc.; the inlay adopts a split design, and is composed of a bottom layer insert 1 and a surface layer insert 5, and the surface layer insert 5 is installed on the bottom layer insert 1. Since the bottom layer insert 1 and the surface layer insert 5 are fixedly connected, the inlay actually forms a new Z-pin. This method innovates the Z-pin structure and significantly improves the overall load-bearing capacity and durability. At the same time, the split design can flexibly select a suitable insert shape according to the material and thickness of the surface layer 4 and the bottom layer, which provides convenience for actual production. In addition, this also provides a variety of combinations of the bottom layer and the surface layer 4 to meet various specific needs.

[0061] The cross-sectional shape of the inlay affects the interfacial bonding strength between it and the composite matrix. Good interfacial bonding is the key to ensure that the inlay can effectively transfer loads and enhance the performance of the composite material. A circular or nearly circular cross-sectional shape may be more conducive to forming a uniform and dense interfacial bonding layer, thereby improving the bonding strength between the inlay and the composite matrix. Compared with a circular cross-section, a polygonal cross-section can better engage with the matrix material, increase the contact area, and improve the pull-out resistance.

[0062] Preferably, the inlay material is metal; the surface inlay 5 is an M12 countersunk bolt; Figure 1 As shown, the bottom insert 1 has a size of 30mm×30mm×100mm (length×width×height), and a waist size of 20×20mm. The bottom insert 1 is slotted perpendicular to the surface with a spacing of 30mm and a slotted section of 2mm×2mm. The bottom insert 1 has a square cross section with a side length of 3 times the diameter of the connecting bolt. The bottom insert 1 is machined to complete the outer shape.

[0063] Longer inlays can provide a larger connection area, thereby enhancing the connection strength between composite laminates. As the length increases, when subjected to external forces, the inlay can better transfer the load to more matrix materials and reduce interface stress concentration. The setting of the bottom layer insert 1, which is thick at both ends and thin in the middle, is also to provide a larger connection area and enhance the bonding strength with the matrix material. The bottom layer insert 1 is selected to have a square cross-section. On the one hand, it takes into account the convenience of insert processing; on the other hand, the subsequent steps involve wrapping glass fiber yarn prepreg around its waist until the waist depression of the bottom layer insert 1 is filled and leveled, which actually adjusts the interface bonding layer to a nearly circular shape, thereby enhancing the connection strength.

[0064] The surface of the inlay is treated to improve the connection strength, fixing effect, stress distribution, etc. This includes: knurling, sandblasting, grooving, etc. on the surface to create regular raised or recessed patterns on the surface of the connector to increase friction and contact area; surface geometry optimization such as threaded and barbed designs to further enhance the mechanical interlocking effect between the inlay and the base material. The groove shape can be of various shapes, and the square groove is preferred for ease of processing.

[0065] Step 2: Making the bottom layer. The bottom layer includes a web 3, which includes: the first step of connecting the bottom layer insert 1 with the web 3 to form a web frame; the second step of filling the web frame with core material 6; the third step of core mold injection molding to complete the bottom layer. The web frame is the main load-bearing component, and the core material 6 plays a structural filling role;

[0066] The first step is to connect the bottom insert 1 with the web 3 to form a web frame:

[0067] The web 3 is a composite material. The bottom layer insert 1 is connected to the web 3 by integrated molding or step-by-step molding. In Example 1, the web 3 is connected to the bottom layer insert 1 by integrated molding, and in Example 2, the web 3 is connected to the bottom layer insert 1 by step-by-step molding.

[0068] Preferably, the integrated molding of the bottom layer insert 1 and the web 3 comprises the following steps:

[0069] Step 1: Processing of bottom insert 1. Wrap glass fiber yarn with a width of 2mm in the vertical height direction of the surface of bottom insert 1 to fill the 2×2mm groove on the surface of bottom insert 1, and then continue to wrap the surface of bottom insert 1 with glass fiber cloth with a width of 5mm in the same direction until the waist concave part of bottom insert 1 is filled. Wrapping with fiber fabrics or prepregs of different widths to fill the waist grooves and concave parts of bottom insert 1 is to achieve the purpose of increasing the connection strength between the composite material and bottom insert 1.

[0070] Step 2: implant the bottom layer insert 1 into the web 3 preform. The bottom layer insert 1 is implanted into the web 3 preform. The implant structure is as follows: Figure 2 As shown, the web 3 preform is used to set the bottom layer insert 1 at a predetermined position and facilitate fixation.

[0071] Step 3: orthogonally lay the fiber fabric, lay the release cloth and the guide net in sequence, and complete the forming of the web 3 through a forming process. The forming process includes at least one of the three processes of vacuum assisted forming, liquid forming or hot pressing injection forming.

[0072] Preferably, a 15 mm thick glass fiber fabric is orthogonally laid on the mold surface, and then the bottom layer insert 1 wrapped with the fiber fabric is placed in the specified position, and the 15 mm thick glass fiber fabric is continued to be orthogonally laid, and the release cloth and the guide net are laid in turn, and finally the web 3 is formed by vacuum assisted molding, liquid molding or hot pressing molding.

[0073] Through integrated molding, the surface connection between the composite material and the bottom insert 1 is consistent in all directions. This arrangement makes the stress distribution uniform when the material is subjected to force, thereby ensuring good connection strength.

[0074] The second step is to fill the core material 6 in the web frame to form a core mold:

[0075] To provide support for the surface layer 4, the core material 6 processed into a specific shape is filled into the web frame according to the size of the web frame 3, and the surface of the core material 6 is kept at the same height as the surface of the web 3. The specific shape refers to a contour shape that matches the web frame, including but not limited to a rectangle, a diamond and an irregular shape.

[0076] The third step is to pour the core mold into the mold to complete the bottom layer production:

[0077] Adhesive is used to bond the core material 6 and the web 3, and then resin is poured into the bonding gap between the core material 6 and the web 3 through vacuum assisted molding. Finally, the surface of the web 3 and the core material 6 is machined into a specified shape through machining to complete the molding of the composite material bottom layer.

[0078] Step 3: making surface layer 4.

[0079] Step 1: fix and connect the bottom layer insert 1 and the surface layer insert 5. The length, shape, connection method, etc. of the surface layer insert 5 can be flexibly selected as needed, taking into account both performance and cost.

[0080] Preferably, a hole is punched on the upper surface of the bottom layer insert 1. The hole diameter is smaller than the bolt diameter. The bolt hole is tapped with a tap that matches the bolt, and the bolt and the bolt hole are checked for interference, and iron filings in the bolt hole are cleaned. Thread glue is evenly applied on the surface of the bolt stud, and embedded bolts are implanted, and the embedded bolts extend out of the bottom layer insert 1 to a certain height. After the thread glue is cured, the bolt fixing effect is checked to determine whether the bolt is firmly bonded and fixed. The height of the bolt is 2 / 3 of the thickness of the surface layer 4.

[0081] Preferably, the embedded bolt is an M12 countersunk bolt, and the height of the embedded bolt protruding from the bottom layer insert 1 is 12 mm.

[0082] The combination of bottom layer insert 1 + bolt is adopted in consideration of the general availability of the surface layer insert 5 and the economic cost. The height of the bolt can be flexibly adjusted according to the thickness of the surface layer 4.

[0083] Step 2, laying the surface fiber fabric on the bottom surface. The fiber fabric is opened at the bottom layer insert 1 and passes through the surface layer insert 5 until the fabric is at the same height as the upper surface of the surface layer insert 5. After the fabric opening and laying is completed, the raised fabric is trimmed flat at the embedded bolts, and the fiber fabric is continued to be laid. No holes are made in the subsequent fiber fabric. This operation makes the inlay and the fiber fabric layer closely combined, achieving the effect of optimizing the internal stress distribution and improving the overall strength.

[0084] Preferably, the opening is in the form of a straight hole, the opening directions of the two adjacent layers of fabric are perpendicular, and the bolt extends through the straight hole. Figure 5 The opening direction is refined to make the fabric and the inlay fit more closely, thus improving the bonding strength between the inlay and the composite material matrix.

[0085] Preferably, the web 3 is 30 mm thick and is made of glass fiber reinforced vinyl resin composite material; the surface layer 4 is 18 mm thick and is made of carbon fiber reinforced vinyl resin composite material, and the two are orthogonally laid.

[0086] Step 3, the composite material surface layer 4 is poured and molded to complete the connection between the composite material bottom layer and the surface layer 4. The composite material surface layer 4 is molded by liquid molding or hot pressing and pouring molding. The release cloth and the guide net are laid, and the bag film is sealed and the resin is poured to complete the connection between the composite material bottom layer and the surface layer 4.

[0087] The composite material multilayer connection material produced by the method of the present invention has the following advantages: significantly improving the structural strength and stiffness of the composite material, thereby enhancing the overall performance; selecting suitable materials according to the requirements of different layers to achieve the best configuration of materials, reduce waste and reduce costs; effectively dispersing stress concentration, reducing fatigue damage and extending service life; different material layers can provide different protection functions, such as corrosion protection, UV protection, etc., to enhance environmental resistance; the number of layers and material combinations can be flexibly adjusted according to specific application requirements to meet diverse design requirements; while ensuring structural strength, the overall weight can be effectively reduced by reasonably designing a multilayer structure; a more precise manufacturing process can be achieved to ensure good bonding between layers and improve product quality; different layers can integrate multiple functions, such as conductivity, heat insulation, sound absorption, etc., so that a single structure has multiple functions.

[0088] Example 2

[0089] A composite material interlayer connection method comprises the following steps:

[0090] Step 1: Making the inlay.

[0091] Preferably, the bottom layer insert 1 has a size of 30 mm × 30 mm × 300 mm (length × width × height), and the four side surfaces along the height direction include three inwardly concave surfaces and one plane, and the waist section of the bottom layer insert 1 is an isosceles trapezoid, such as Figure 6 There are square grooves on the three inwardly concave surfaces, and the flat side surfaces are used for bonding with the three sides of the web.

[0092] Step 2: Making the bottom layer. The bottom layer includes a web, which includes: first, connecting the bottom layer insert 1 with the web 3 to form a web frame; second, filling the web frame with core material 6; third, performing core mold injection molding to complete the bottom layer production. Figure 4 shown.

[0093] The bottom layer insert 1 is connected to the web 3 by step-by-step forming. The step-by-step forming of the web 3 and the bottom layer insert 1 includes the following steps:

[0094] Step 1: Surface treatment of the web 3. Use sandpaper to roughen the fixed surface of the web 3 and the bottom insert 1, and use anhydrous ethanol to remove dust on the surface of the web 3. The above treatment improves the surface adhesion and enhances the bonding strength.

[0095] Step 2: Bonding and fixing the bottom insert 1 to the web 3. First, sandblast the connection area between the bottom insert 1 and the web 3 to improve the surface roughness, then apply vinyl adhesive to the flat side area of ​​the bottom insert 1, and apply vinyl adhesive to the specified position of the web 3, then bond the adhesive-coated surface of the bottom insert 1 to the adhesive-coated area of ​​the web 3, squeeze out the excess adhesive, and use a scraper to scrape the extruded adhesive flat.

[0096] Step 3: Fabric forming of the connection between the bottom insert 1 and the web 3. First, the fiber fabric is orthogonally laid in the bonding area between the bottom insert 1 and the web 3. The laying thickness is preferably 5mm, the length of the laid fiber fabric is preferably greater than 200mm, the width is the same as the height of the bottom insert 1, and the center in the length direction is aligned with the center of the bottom insert 1. The bottom insert 1 is located between the fiber fabric and the web 3; then lay the demoulding cloth and the guide net; finally, perform bag film sealing and vacuum assisted molding to form the bottom insert fixed composite material 2, and complete the fixation of the bottom insert 1. Implant structure such as Figure 3 shown.

[0097] The step-by-step molding of the web 3 and the bottom insert 1 is an alternative solution for connecting the two, which can provide a more suitable option according to specific needs.

[0098] Step 3: Same as Step 3 of Example 1.

[0099] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for connecting composite material layers, characterized in that: The method comprises three steps of making an inlay, making a bottom layer, and making a surface layer (4); the inlay comprises a bottom layer inlay (1) and a surface layer inlay (5); the bottom layer inlay (1) is embedded in the bottom layer, the surface layer inlay (5) is embedded in the surface layer (4), the surface layer inlay (5) and the bottom layer inlay (1) are fixedly connected, and the inlay is used to realize the fixed connection between the enhanced surface layer (4) and the bottom layer.

2. The composite material interlayer connection method according to claim 1, characterized in that: The surfaces of the bottom layer insert (1) extending in the length direction are taken as side surfaces, and at least one of the side surfaces is concave inwardly in the middle section.

3. The composite material interlayer connection method according to claim 1, characterized in that: When making the inlay, the surface of the inlay is treated to improve the bonding strength.

4. The composite material interlayer connection method according to claim 3, characterized in that: The surface of the inlay is processed by providing a groove perpendicular to the side surface of the bottom inlay (1).

5. The composite material interlayer connection method according to claim 4, characterized in that: The bottom layer comprises a web (3), and the manufacturing of the bottom layer comprises: a first step of connecting the bottom layer insert (1) to the web (3) to form a web frame; a second step of filling the web frame with a core material (6) to form a core mold; and a third step of performing injection molding of the core mold to complete the manufacturing of the bottom layer.

6. The composite material interlayer connection method according to claim 5, characterized in that: The bottom layer insert (1) and the web (3) are connected by integrated molding or step-by-step molding.

7. The composite material interlayer connection method according to claim 6, characterized in that: The web (3) and the bottom layer insert (1) are connected by integrated molding, comprising the following steps: Step 1: Winding glass fiber yarn or prepreg in a direction perpendicular to the surface of the bottom insert (1) to fill the groove on the surface of the bottom insert (1), and then continuing to wind glass fiber cloth or prepreg of different widths along the same direction on the surface of the bottom insert (1) until the depression of the bottom insert (1) is filled; Step 2: implanting the bottom insert (1) into the web preform; Step 3: orthogonally lay the fiber fabric, lay the release cloth and the guide net in sequence, and complete the molding of the web (3) through a molding process.

8. The composite material interlayer connection method according to claim 6, characterized in that: The connection between the web (3) and the bottom layer insert (1) is formed in steps, including the following steps: Step 1: Use sandpaper to roughen the fixing surface between the web (3) and the bottom insert (1), and remove dust from the surface of the web (3); Step 2: sandblasting the connection area between the bottom insert (1) and the web (3), and bonding and fixing them with adhesive; Step 3: The fiber fabric is orthogonally laid in the bonding area between the bottom insert (1) and the web (3), with the bottom insert (1) being located between the fiber fabric and the web (3), and then a release cloth and a guide net are laid, and finally the bag film is sealed and vacuum-assisted molding is performed to form a bottom insert fixed composite material (2), thereby completing the fixation of the bottom insert (1).

9. The composite material interlayer connection method according to claim 1, characterized in that: The manufacturing of the surface layer (4) comprises the following steps: Step 1: The surface insert (5) is fixedly connected to the bottom insert (1); Step 2: Laying the surface fiber fabric on the bottom surface; Step 3: The composite material surface layer (4) is injection molded to complete the connection between the composite material bottom layer and the surface layer (4).

10. The composite material interlayer connection method according to claim 9, characterized in that: When performing step 2 to lay the surface fiber fabric on the bottom surface, a hole is opened in the surface fiber fabric at the bottom layer insert (1), and the surface insert (5) passes through the hole until the stacking height of the surface fiber fabric is consistent with the height of the surface insert (5) protruding from the bottom layer; the surface fiber fabric laid subsequently is no longer opened.

11. The composite material interlayer connection method according to claim 10, characterized in that: The opening shape is a straight hole, and the opening directions of two adjacent layers of fabric are perpendicular.

12. A composite material, characterized in that: The composite material is manufactured by the composite material interlayer connection method described in any one of claims 1-11.

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