Infiltration connection structure and method for fiber composite material plates

Abstract

The invention discloses an infiltration connection structure and method for fiber composite material plates, and relates to the technical field of carbon fiber composite materials. The structure comprises a concave side plate and a convex side plate, the concave side plate and the convex side plate are mutually embedded, the contact surface of the concave side plate and the convex side plate is an embedded surface, a connection reinforcing sheet is arranged on the embedded surface, the connection reinforcing sheet comprises a carbon fiber net-shaped electric heating framework, and the carbon fiber net-shaped electric heating framework is wrapped in a hot melt adhesive film; thermoplastic resin is uniformly distributed in the concave side plate and the convex side plate, and the thermoplastic resin of the hot melt adhesive film has the same matrix type as the thermoplastic resin of the concave side plate and the convex side plate. The connection reinforcing sheet is attached to the range of all the embedding surfaces, the infiltration direction is basically perpendicular to the embedding surfaces, and the connection effect in different stress directions can be achieved along with bending of the embedding surfaces; the carbon fiber net-shaped electric heating framework is used as a heating part to be evenly distributed on the connection reinforcing piece, and the effect of evenly heating the thermoplastic resin on the embedded face can be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon fiber composite materials, and particularly to an infiltration connection structure and method for fiber composite material plates. Background Art

[0002] Disclosing the information of this background art section is only intended to enhance the overall understanding of the present invention, and it is not necessarily regarded as an admission or an implication in any form that this information constitutes the prior art already known to those of ordinary skill in the art.

[0003] Due to its excellent mechanical properties, high-performance thermoplastic carbon fiber composites are widely used in important equipment structural components such as civil aviation, military aviation, deep-sea exploration, and oilfield industry. Due to the size characteristics of large composite material plates, it is often necessary to carry out the splicing and assembly processing of multiple plates, and the joint interface performance is the key and bottleneck problem for giving full play to the performance advantages of the overall plate, which is directly related to the structural integrity and safety of the structural components.

[0004] Thermoplastic resins only undergo physical changes of heating and melting and cooling and solidifying during the process. Its composites can be welded, and have the comprehensive advantages of rapid prototyping and structural weight reduction. For the processing and assembly process of large carbon fiber composite material plate parts, it has relatively large performance advantages. Regarding the structural treatment methods and welding process technologies for the splicing interfaces of carbon fiber thermoplastic composite material plates, many ideas have been proposed by researchers. In order to facilitate continuous production and processing, reduce the process difficulty of plate interface connection, improve its operability, and at the same time ensure the mechanical strength of the joint interface, higher requirements are put forward for the structural design of the joint. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide an infiltration connection structure and method for fiber composite material plates, improve its operability, and at the same time ensure the mechanical strength of the joint interface.

[0006] In order to achieve the above purpose, the present invention is realized through the following technical solutions:

[0007] The first aspect of the present invention provides an infiltration connection structure for fiber composite material plates, including a concave-side plate and a convex-side plate. The concave-side plate and the convex-side plate are mutually fitted. The contact surfaces of the concave-side plate and the convex-side plate are fitting surfaces. A connection reinforcement sheet is arranged on the fitting surface. The connection reinforcement sheet includes a carbon fiber mesh-shaped electric heating skeleton, and the carbon fiber mesh-shaped electric heating skeleton is wrapped in a hot melt adhesive film. Thermoplastic resins are evenly distributed in the concave-side plate and the convex-side plate, and the thermoplastic resin of the hot melt adhesive film has the same matrix type as the thermoplastic resin matrix of the concave-side plate and the convex-side plate.

[0008] Second aspect, a preparation method for the infiltration connection structure of the fiber composite material board described above includes the following steps:

[0009] S1. Process to obtain a concave-side board and a convex-side board whose shapes are mutually fitted;

[0010] S2. After applying a connection reinforcement sheet on one side of the fitting surface, fit the concave-side board and the convex-side board together;

[0011] S3. Press the fitting surface and energize the carbon fiber mesh-shaped electric heating skeleton, so that the hot melt adhesive film, the thermoplastic resin of the concave-side board and the convex-side board are heated and infiltrated and combined into one body, obtaining the infiltration connection structure of the fiber composite material board.

[0012] The beneficial effects of the present invention are as follows:

[0013] 1. In the infiltration connection structure of the fiber composite material board provided by the present invention, the connection reinforcement sheet is attached to the entire fitting surface range, and the infiltration direction is basically perpendicular to the fitting surface, and it can achieve the connection effect in different stress directions along with the bending of the fitting surface; the carbon fiber mesh-shaped electric heating skeleton is evenly distributed on the connection reinforcement sheet as a heating component, and can uniformly heat the thermoplastic resin on the fitting surface, adapting to the processing and assembly process of large-sized carbon fiber composite material board parts.

[0014] 2. The preparation method provided by the present invention has strong practicability and is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings forming a part of this specification are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof of the present invention are used to explain the present invention and do not constitute an improper limitation to the present invention.

[0016] The distances or sizes between each part are exaggerated in the drawings for showing the positions of each part, and the schematic diagrams are only for illustration.

[0017] Figure 1 It is a schematic structural diagram of the concave-side board and the convex-side board in Embodiment 1.

[0018] Figure 2 It is a schematic structural diagram of the connection reinforcement sheet in Embodiment 1.

[0019] Figure 3 It is a schematic structural diagram of the infiltration connection structure of the fiber composite material board after infiltration in Embodiment 1.

[0020] Among them, 1. Concave-side board; 2. Convex-side board; 3. Connection reinforcement sheet; 4. Carbon fiber mesh-shaped skeleton; 5. Hot melt adhesive film; 6. Electrode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] It should be noted that the following detailed description is exemplary and is intended to provide further illustration of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0022] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] One or more embodiments of the present invention provide a penetration connection structure for a fiber composite material plate, including a concave-side plate and a convex-side plate. The concave-side plate and the convex-side plate are mutually fitted. The contact surface between the concave-side plate and the convex-side plate is a fitting surface. A connection reinforcing sheet is provided on the fitting surface. The connection reinforcing sheet includes a carbon fiber mesh-shaped electric heating skeleton, and the carbon fiber mesh-shaped electric heating skeleton is wrapped in a hot-melt adhesive film. Thermoplastic resins are uniformly distributed in the concave-side plate and the convex-side plate, and the thermoplastic resin of the hot-melt adhesive film has the same matrix type as the thermoplastic resin of the concave-side plate and the convex-side plate.

[0024] In the above structure, the connection reinforcing sheet has a relatively thin thickness and is a flexible structure, which fits on the entire fitting surface, and the penetration direction is basically perpendicular to the fitting surface. It can firmly connect the plates on both sides of the fitting surface and achieve the connection effect in different stress directions as the fitting surface bends. The carbon fiber mesh-shaped electric heating skeleton, as a heating component, is uniformly distributed in the connection reinforcing sheet, which can uniformly heat the thermoplastic resin on the fitting surface and can adapt to the processing and assembly process of large carbon fiber composite material plate parts.

[0025] Optionally, the concave-side plate includes a concave structure, and the convex-side plate includes a convex structure, and the convex structure is inserted into the concave structure.

[0026] Optionally, the concave structure of the concave-side plate is located at the middle position in the thickness direction of the concave-side plate. The thickness of the concave structure accounts for 5-20% of the thickness of the concave-side plate. The distance from the bottom of the concave structure to the cross-section of the concave-side plate is the depth of the concave structure, and its depth is 10-20% of the size of the concave-side plate in the same direction. Correspondingly, the convex structure of the convex-side plate is located at the middle position in the thickness direction of the convex-side plate, and the thickness / extension length of the convex structure matches the thickness / depth of the concave structure. The distribution pattern of the concave structure is: continuously distributed on the cross-section of the concave-side plate, or distributed at intervals of a set distance, and the interval distance can be flexibly adjusted according to design requirements. The distribution pattern of the convex structure matches the distribution pattern of the concave structure, forming a final fitting structure with the concave structure for realizing the fitting connection of the two-side plates and being able to withstand stress forms such as tension, compression, and bending moment.

[0027] Optionally, the thickness of the connection reinforcement sheet is within the range of 0.2-0.5 mm, which can be flexibly adjusted according to design requirements, has a certain flexibility, and can fit with the zigzag fitting surface. The thickness of the hot-melt adhesive film is controlled within the range of 0.01-0.1 mm.

[0028] Optionally, the hot-melt adhesive film includes a continuous medium film material or a non-woven fabric material, which can be flexibly selected according to design requirements. Both the continuous medium film material and the non-woven fabric material can play a bonding role under the action of heat.

[0029] Optionally, the carbon fiber mesh-shaped electrothermal skeleton is connected to the electrodes. The electrodes are exposed at the fitting position and are located at the edge of the electrothermal skeleton, and can be located on one side or both sides. When the carbon fiber mesh-shaped electrothermal skeleton is in an energized state, it can dissipate heat and heat the connection reinforcement sheet from the inside to realize the mutual penetration between the hot-melt adhesive film on the connection reinforcement sheet and the thermoplastic resin matrix of the two-side plates.

[0030] Optionally, the carbon fiber mesh-shaped electrothermal skeleton is woven by single bundles of carbon fiber tapes. The weaving structure includes plain weave, twill weave, or satin weave. The width of the single bundle of carbon fiber tapes is controlled within the range of 5-10 mm, which matches the size of the fitting surface and can cover the fitting surface.

[0031] One or more embodiments of the present invention provide a preparation method for the penetration connection structure of the above fiber composite material plate, including the following steps:

[0032] S1. Prepare a connection reinforcement sheet with a carbon fiber mesh-shaped electrothermal skeleton and hot-melt adhesive films on both sides as raw materials;

[0033] S2. Process to obtain a concave-side plate and a convex-side plate with mutually fitting shapes;

[0034] S3. After pasting the connection reinforcement sheet on the fitting surface, fit the concave-side plate and the convex-side plate together;

[0035] S4. Pressurize the fitting surface and energize the carbon fiber mesh electric heating framework, so that the thermoplastic resin of the hot melt adhesive film, the concave-side plate and the convex-side plate is heated, melted and infiltrated and combined into one body, obtaining a penetration connection structure of the fiber composite material plate.

[0036] Optionally, in S1, sandwich the carbon fiber mesh electric heating framework between the hot melt adhesive films on both sides, heat and melt them into one body, obtaining a connection reinforcement sheet with a three-layer laminated structure having a carbon fiber mesh electric heating framework in the middle and hot melt film-like adhesives on the upper and lower surfaces.

[0037] Optionally, in S1, the carbon fiber mesh electric heating framework is connected to an electrode, and in S3, the electrode is exposed at the fitting position.

[0038] Optionally, in S2, the concave-side plate and the convex-side plate are respectively processed by mechanical processing or water jet cutting.

[0039] Optionally, in S4, the pressure range is 0.1 - 2 MPa, and the pressure direction is perpendicular to the fitting surface. When the fitting surface includes two directions of vertical and horizontal, the pressure direction also includes two directions of horizontal and vertical.

[0040] Optionally, in S4, the pressure penetration time is 5 - 30 min.

[0041] Example 1

[0042] According to the design and operation method of the present invention, the penetration connection treatment of two PP resin-based carbon fiber composite material plates with a length of 100 cm, a width of 20 cm, and a thickness of 6 mm at the length interface part is completed. The specific implementation method and steps include:

[0043] S1. Adopt two PP hot melt adhesive films 5 with a thickness of 0.01 mm, and respectively apply them on the surface of the carbon fiber mesh framework 4 woven in a plain weave structure in the up and down directions to form a laminated material as shown in Figure 2 wherein the width of a single bundle of carbon fibers in the mesh framework is 5 mm, and finally a connection reinforcement sheet with a thickness of 0.2 mm is formed. Electrodes 6 are arranged at specific positions of the connection reinforcement sheet to connect to a power source.

[0044] S2. Adopt mechanical processing or water jet processing methods to respectively process a concave structure and a convex structure that are mutually fitted at the length / thickness surface position of the composite material, so that it becomes a concave-side plate 1 and a convex-side plate 2 as shown in Figure 1 wherein the length of the concave structure is 100 cm, the depth is 2 cm, and the width is 1 mm; the convex structure is processed by mechanical processing or water jet starting from the upper and lower surfaces of the composite material plate towards the center, so that the remaining material becomes a convex structure. The processing width of the groove structure is 2.5 mm, the length of the groove structure is 100 cm, and finally the length of the convex structure is 100 cm. The above dimensions finally form a concave-convex fitting structure.

[0045] S3. As shown in Figure 1 , attach the connection reinforcement sheet 3 to the fitting surfaces of the concave-side plate 1 and the convex-side plate 2 respectively. Then, preliminarily combine and connect the concave-convex fitting structure to form a structure as shown in Figure 3 . The electrodes 6 are exposed on the upper and lower sides of the fitting position, that is, the opposite sides.

[0046] S4. Place the interface part of the fitting structure in a vulcanizing machine or a press, and apply a pressure of 0.1 MPa perpendicular to the fitting surface (including two directions perpendicular and parallel to the plate surface) to fix it. Then, connect the electrodes of the connection reinforcement sheet to a power supply and energize. Adjust the infiltration temperature to 230 °C and control the infiltration time within 5 min. Then, cut off the power supply and cool down. Finally, form the infiltration connection of the carbon fiber composite material plate. The obtained structure is as shown in Figure 3 . The entire connection reinforcement sheet 3 infiltrates to both sides and merges with the concave-side plate 1 and the convex-side plate 2 into one body.

[0047] In this embodiment, the shape of the electrode 6 is a strip-shaped electrode, which extends out at the joint position between the concave-side plate 1 and the convex-side plate 2. Since the fitting surface perpendicular to the electrode surface is included, the pressing direction includes the direction perpendicular to the electrode 6. Then, the joint at the position of the electrode 6 is closed under the action of pressure.

[0048] Embodiment 2

[0049] According to the design and operation method of the present invention, complete the infiltration connection treatment at the length interface part of two PP resin-based carbon fiber composite material plates with a length of 150 cm, a width of 18 cm, and a thickness of 4 mm. The specific implementation method and steps include:

[0050] S1. Adopt two PP hot-melt adhesive films with a thickness of 0.05 mm and attach them to the surface of the carbon fiber mesh framework woven with a twill structure in the up and down directions respectively to form a laminated material. The width of a single bundle of carbon fibers in the mesh framework is 6 mm, and finally form a connection reinforcement sheet with a thickness of 0.5 mm. Set electrodes at specific positions of the reinforcement sheet to connect to the power supply.

[0051] S2. Adopt mechanical processing or water jet processing methods to process a concave structure and a convex structure that fit with each other at the length / thickness surface position of the composite material respectively. The length of the concave structure is 150 cm, the depth is 3.6 cm, and the width is 0.2 mm; the convex structure is processed by mechanical processing or water jet starting from the upper and lower surfaces of the composite material plate towards the center, so that the remaining material becomes a convex structure. The processing width of the groove structure is 2.9 mm, and the length of the groove structure is 150 cm. Finally, the length of the convex structure is 150 cm. The above dimensions finally form a concave-convex fitting structure.

[0052] S3. Apply the connection reinforcement sheets to the contact surfaces of the concave or convex fitting structures respectively, and then preliminarily combine and connect the concave-convex fitting structures.

[0053] S4. Place the interface part of the fitting structure in a vulcanizer or a press, apply a pressure of 0.5 MPa perpendicular to the fitting surface to fix it, then connect the electrodes of the connection reinforcement sheets to a power source to energize, adjust the infiltration temperature to 250 °C, control the infiltration time within 15 min, and then cut off the power supply and cool down. Finally, the infiltration connection of the carbon fiber composite material plate is formed.

[0054] Example 3

[0055] According to the design and operation method of the present invention, the infiltration connection treatment of two PP resin-based carbon fiber composite material plates with a length of 120 cm, a width of 16 cm, and a thickness of 6 mm at the length interface part is completed. The specific implementation methods and steps include:

[0056] S1. Adopt two PA hot-melt adhesive films with a thickness of 0.08 mm, and apply them to the surface of the carbon fiber mesh skeleton woven in a satin structure in the up and down directions respectively to form a laminated material. The width of a single bundle of carbon fibers in the mesh skeleton is 8 mm, and finally a connection reinforcement sheet with a thickness of 0.4 mm is formed. Electrodes are set at specific positions on the reinforcement sheet to connect to the power source.

[0057] S2. Adopt mechanical processing or water jet processing methods to process a concave structure and a convex structure that fit each other at the length / thickness surface positions of the composite material respectively. The concave structure is set in sections, with a single section length of 10 cm, a spacing of 2 cm between adjacent sections, a depth of 1.6 cm, and a width of 0.6 mm; the convex structure is processed by mechanical processing or water jet starting from the upper and lower surfaces of the composite material plate towards the center, so that the remaining material becomes a convex structure. The processing width of the groove-shaped structure is 2.7 mm, the single section length is 5 cm, the distance between single sections is 2 cm, and finally the protruding length of the convex structure is 1.6 cm. The above dimensions finally form a concave-convex fitting structure.

[0058] S3. Apply the connection reinforcement sheets to the contact surfaces of the concave or convex fitting structures respectively, and then preliminarily combine and connect the concave-convex fitting structures.

[0059] S4. Place the interface part of the fitting structure in a vulcanizer or a press, apply a pressure of 0.15 MPa perpendicular to the fitting surface to fix it, then connect the electrodes of the connection reinforcement sheets to a power source to energize, adjust the infiltration temperature to 285 °C, control the infiltration time within 15 min, and then cut off the power supply and cool down. Finally, the infiltration connection of the carbon fiber composite material plate is formed.

[0060] Example 4

[0061] According to the design and operation mode of the present invention, infiltration connection treatment is completed at the length interface of two TPU resin-based carbon fiber composite material plates with a length of 180 cm, a width of 14 cm, and a thickness of 6 mm. The specific implementation methods and steps include:

[0062] S1. Two PA hot melt adhesive films with a thickness of 0.09 mm are respectively applied on the surface of the carbon fiber mesh skeleton woven in a plain weave structure in the up and down directions to form a laminated material. The width of a single bundle of carbon fibers in the mesh skeleton is 8 mm, and finally a connection reinforcement sheet with a thickness of 0.45 mm is formed. Electrodes are set at specific positions of the reinforcement sheet to connect to the power supply.

[0063] S2. A concave structure and a convex structure that are mutually engaged are respectively machined on the length / thickness surface positions of the composite material by mechanical machining or water jet machining. The concave structure is set in sections, with a single-section length of 43.5 cm, a 2-cm interval between adjacent sections, a depth of 2.8 cm, and a width of 1.2 mm. The convex structure is machined from the upper and lower surfaces of the composite material plate towards the center by mechanical machining or water jet, so that the remaining material becomes a convex structure. The machining width of the groove structure is 2.4 mm, the single-section length is 43.5 cm, the distance between single sections is 2 cm, and finally the protruding length of the convex structure is 2.8 cm. The above dimensions finally form a concave-convex engagement structure.

[0064] S3. The connection reinforcement sheets are respectively applied on the contact surfaces of the concave or convex engagement structures, and then the concave-convex engagement structures are preliminarily combined and connected.

[0065] S4. The interface part of the engagement structure is placed in a vulcanizer or a press, and a pressure of 0.2 MPa is applied perpendicular to the engagement surface to fix it. Then, the electrodes of the connection reinforcement sheet are connected to the power supply to conduct electricity, the infiltration temperature is adjusted to 245 °C, the infiltration time is controlled within 25 min, and then the power is cut off for cooling. Finally, the infiltration connection of the carbon fiber composite material plate is formed.

[0066] The above are only the preferred embodiments of the present application and are not used to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A melt infiltration connection structure of a fiber composite material plate, characterized in that: It includes a concave side plate and a convex side plate, the concave side plate and the convex side plate are embedded with each other, the contact surface of the concave side plate and the convex side plate is an embedding surface, a connection reinforcement sheet is arranged on the embedding surface, the connection reinforcement sheet includes a carbon fiber mesh electric heating skeleton, and the carbon fiber mesh electric heating skeleton is wrapped in a hot melt adhesive film; thermoplastic resin is evenly distributed in the concave side plate and the convex side plate, and the thermoplastic resin of the hot melt adhesive film is the same as the thermoplastic resin matrix type of the concave side plate and the convex side plate.

2. The infiltration connection structure of the fiber composite material sheet material according to claim 1, characterized in that: The concave structure of the concave side plate is located in the middle of the thickness direction of the concave side plate, and the thickness of the concave structure accounts for 5-20% of the thickness of the concave side plate. The distance between the bottom of the concave structure and the cross section of the concave side plate is the depth of the concave structure, and the depth is 10-20% of the size of the concave side plate in the same direction; the convex structure of the convex side plate is located in the middle of the thickness direction of the convex side plate, and the thickness / extending length of the convex structure matches the thickness / depth of the concave structure; The distribution mode of the concave structures is: continuously distributed on the cross section of the concave side plate, or distributed at a set interval; the distribution mode of the convex structures matches the distribution mode of the concave structures.

3. The infiltration connection structure of the fiber composite material sheet material according to claim 1, characterized in that: The thickness of the connection reinforcement sheet is within the range of 0.2-0.5 mm; the thickness of the hot melt adhesive film is controlled within the range of 0.01-0.1 mm.

4. The infiltration connection structure of the fiber composite material sheet material according to claim 1, characterized in that: The hot melt adhesive film includes a continuous medium film material or a non-woven fabric material.

5. The infiltration connection structure of fiber composite material sheet material according to claim 1, characterized in that: The carbon fiber mesh electric heating skeleton is connected to an electrode, the electrode is exposed at the fitting position, and the electrode is located at the edge of the electric heating skeleton, on one side or on the opposite side; Alternatively, the carbon fiber mesh electric heating skeleton is formed by weaving a single bundle of carbon fiber tapes, the weaving structure includes plain weave, twill weave or satin weave, and the width of the single bundle of carbon fiber tapes is controlled within the range of 5-10 mm.

6. A method for preparing a melt-infiltration connection structure of a fiber composite material plate according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, using a carbon fiber mesh electric heating skeleton and hot melt adhesive films on both sides as raw materials to prepare a connection reinforcement sheet; S2, processing to obtain a concave side plate and a convex side plate whose shapes fit each other; S3, after applying the connection reinforcement sheet on the fitting surface, fit the concave side plate and the convex side plate together; S4, pressurizing the mating surfaces and energizing the carbon fiber mesh electric heating skeleton, so that the hot melt adhesive film, the thermoplastic resin of the concave side plate and the convex side plate are melted and integrated into one, thereby obtaining a melt-infiltration connection structure of the fiber composite material plate.

7. The method for preparing the infiltration connection structure of the fiber composite material plate material according to claim 6, characterized in that: The carbon fiber mesh electric heating skeleton is sandwiched between the hot melt adhesive films on both sides, heated and melted into one, so as to obtain a three-layer laminated structure connection reinforcement sheet with the carbon fiber mesh electric heating skeleton in the middle and the upper and lower surface hot melt film adhesives.

8. The method for preparing the infiltration connection structure of the fiber composite material plate material according to claim 6, characterized in that: In S1, the carbon fiber mesh electric heating skeleton is connected to the electrode, and in S3, the electrode is exposed at the fitting position.

9. The method for preparing the infiltration connection structure of the fiber composite material plate material according to claim 6, characterized in that: In S2, the concave side plate and the convex side plate are processed by mechanical processing or water jet cutting, respectively.

10. The method for crushing and screening carbon-carbon composite materials according to claim 9, characterized in that: In S4, the pressure range is 0.1-2MPa, and the pressure direction is perpendicular to the fitting surface; Alternatively, the pressure infiltration time is 5-30 minutes.

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