Carbon fiber composite annular joint with thickness exceeding 60 mm and manufacturing method

Abstract

The invention discloses a manufacturing method of a carbon fiber composite material annular joint with the thickness exceeding 60mm. A forming process of forming a matrix in a split manner and then integrally coating and bonding is adopted, so that the problem of layering easily caused by single curing forming of a large-thickness composite material joint is effectively solved; and the structural integrity of the composite material joint is remarkably improved through overall coating and bonding of the outer layer. According to the technical scheme, internal defects in the forming process of the large-thickness composite material joint can be effectively eliminated, so that the bearing performance of a product is greatly improved; meanwhile, the invention provides the carbon fiber composite material annular joint which is manufactured according to the method and is more than 60mm in thickness. The invention further provides a non-transient readable recording medium storing the program of the method and a system comprising the medium, the program can be called through a processing circuit, the method is executed, and the non-transient readable recording medium is suitable for being popularized and used in the high-end manufacturing fields of aerospace, new energy equipment and the like.

Description

Technical Field

[0001] This invention belongs to the field of composite material molding technology and discloses a method, recording medium and system for manufacturing a carbon fiber composite ring joint with a thickness of more than 60 mm. Background Technology

[0002] In high-end manufacturing fields such as aerospace and new energy equipment, thick carbon fiber composite ring joints are widely used as key load-bearing components in the connection and force transmission of large components, such as the connecting ring between rocket bodies and engines, and the transition joint between wind turbine main shafts and hubs. These components not only need to withstand complex loads such as axial tension, radial shear, and circumferential torque, but also need to meet stringent requirements for lightweight, high specific strength, fatigue resistance, and structural compactness. Their performance directly determines the reliability and service life of the overall equipment.

[0003] Currently, the manufacturing of thick carbon fiber composite ring joints faces multiple technical challenges: On the one hand, due to the closed nature and large thickness (over 60mm) of the annular structure, traditional molding processes struggle to balance material density with fiber layup continuity. For example, when using filament winding, thick-walled areas are prone to pores and dry spots due to poor resin flow; when using compression molding, the mold closing pressure is unevenly distributed in the thick section, resulting in insufficient interlayer bonding strength, and fiber accumulation or wrinkles are prone to occur at the inner corners of the annulus, significantly reducing the mechanical properties of the joint.

[0004] On the other hand, the connection function of a joint usually requires it to have a complex interface structure (such as flange face, stepped groove, connection hole, etc.), and the integral molding of these structures with a thick body is extremely difficult. Existing technologies mostly adopt the method of "first molding the thick-walled ring body, and then machining the interface structure", but carbon fiber composites have low interlaminar strength and high fiber brittleness. During machining, defects such as delamination, fiber tearing, and burrs are very easy to occur, which not only weaken the joint strength, but may also cause stress concentration, leading to premature failure during service.

[0005] Furthermore, controlling the material uniformity of thick-section ring joints is another core challenge. The significant temperature gradient and resin curing shrinkage differences during the curing process of thick sections easily generate internal stress, leading to ring deformation (such as excessive ellipticity) or internal microcracks, severely affecting dimensional accuracy and structural stability. Simultaneously, in scenarios requiring connection with dissimilar materials such as metals, insufficient bonding strength between the composite material and the metal interface, and mismatched coefficients of thermal expansion, further exacerbate the risk of joint failure.

[0006] Therefore, developing a manufacturing method that can achieve integrated dense molding, ensure fiber layup continuity, reduce processing defects, and improve dimensional accuracy and mechanical properties for the structural characteristics and performance requirements of thick carbon fiber composite ring joints has become a key technological bottleneck to promote its large-scale application in high-end equipment and has important engineering value. Summary of the Invention

[0007] To address the above problems, this invention provides a method for manufacturing a carbon fiber composite ring joint with a thickness exceeding 60 mm, comprising the following steps: S1. The computer divides the carbon fiber composite ring joint model into multiple matrix models with a thickness of 20-40mm along the thickness direction. A mold is set for each matrix model. Carbon fiber composite ring matrix sheets are stacked in the mold, heated and pressurized to cure and demold. The matrix is ​​then processed to the specified matrix size according to the process document requirements to complete the fabrication of all the matrix. S2. Stack all the substrates into a preform according to the shape of the carbon fiber composite ring joint. When stacking, place a layer of adhesive film between adjacent substrates to separate them. Cover the outer surface of the preform with a covering layer of the same material as the preform. The side of the covering layer that is in contact with the preform is covered with adhesive film. S3. Place the preform with the coating layer into the mold and close the mold. Pressurize and cure to the designed thickness according to the temperature / pressure-time curing curve required by the process document. After curing, release the pressure and demold. S4. Multiple stepped holes are machined in a ring-shaped pattern relative to the center of the joint body of the carbon fiber composite material after demolding. An internal thread blind hole bushing is inserted, wherein the opening of the embedded internal thread blind hole faces the mating end face, the stepped surface is on the opposite side of the mating end face, and a base for fitting the internal thread blind hole bushing is used. The center of gravity of the base is located outside the cylindrical surface where the central axis of all internal thread blind holes is located. S5. The internal thread blind hole bushing is a metal product that fits with the stepped hole with a clearance. Adhesive is applied to the clearance and cured to achieve a firm embedding.

[0008] Preferably, the heating and pressurization in step S1 is performed using a press or a vacuum autoclave.

[0009] Preferably, in step S1, the matrix model is divided into multiple base models with a thickness of 20-40 mm by equal division.

[0010] Another aspect of the present invention is to provide a non-transient readable recording medium for storing one or more programs containing multiple instructions, which, when executed, cause the processing circuit to perform the above-described method for manufacturing a carbon fiber composite ring joint with a thickness exceeding 60 mm.

[0011] Another aspect of the present invention provides a manufacturing system for a carbon fiber composite ring joint with a thickness exceeding 60 mm, comprising a processing circuit and a memory electrically coupled thereto, the memory being configured to store at least one program, the program containing multiple instructions, the processing circuit running the program being able to execute the aforementioned method for manufacturing a carbon fiber composite ring joint with a thickness exceeding 60 mm.

[0012] The present invention also provides a carbon fiber composite annular joint with a thickness of more than 60 mm manufactured using the above method, comprising: a joint body and an internal thread blind hole bushing, the joint body comprising an inner preform, a middle layer of adhesive film and an outer covering layer, wherein the preform and the covering layer are both made of the same carbon fiber composite material; the preform is formed by stacking multiple substrates with a thickness of 20-40 mm, adjacent substrates are separated by adhesive film, and each substrate is a stacked clamping member of multiple layers of annular substrate sheets; The internal thread blind hole bushing includes a blind hole liner with a base connected to one end. The connector body has multiple stepped holes evenly distributed in a ring relative to the center of the connector for embedding the internal thread blind hole bushing. The opening of the internal thread blind hole faces the mating end face, and the stepped surface is on the opposite side of the mating end face for fitting the base of the internal thread blind hole bushing. The center of gravity of the base is located outside the cylindrical surface where the central axis of all internal thread blind holes is located. The internal thread blind hole bushing and the stepped hole are clearance fitted.

[0013] Preferably, all the substrates stacked into a preform have the same thickness.

[0014] Compared with existing technologies, the present invention provides a method, recording medium, and system for manufacturing a carbon fiber composite ring joint with a thickness exceeding 60 mm, which have the following advantages: This invention employs a molding process that first separately molds the substrate and then integrally coats and bonds it. This effectively solves the delamination problem that easily occurs in single-curing molding of thick composite material joints, and significantly improves the structural integrity of the composite material joint by integrally coating and bonding it with the same material as the substrate. This technical solution can effectively eliminate internal defects during the molding process of thick composite material joints, thereby greatly improving the load-bearing performance of the product. Attached Figure Description

[0015] Figure 1 This refers to the carbon fiber composite annular joint structure in Embodiment 1 of the present invention; Figure 2 This is a cross-sectional view of the carbon fiber composite annular joint in Embodiment 1 of the present invention; Figure 3 This is a schematic diagram of the metal insert in Embodiment 1 of the present invention; Figure 4 This is a schematic cross-sectional view of the carbon fiber composite annular joint body layup and structure in Embodiment 1 of the present invention; Figure 5This is a schematic diagram showing no internal abnormalities after non-destructive testing of a thick carbon fiber composite joint provided in Embodiment 1 of the present invention. Figure 6 This is a cross-sectional view of the carbon fiber composite joint structure in Embodiment 2 of the present invention.

[0016] In the figure: 1. Composite material connector body; 2. Metal insert; 3. Matrix; 4. Coating layer; 5. Adhesive film. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be described below with reference to the accompanying drawings. The described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without innovative effort are within the scope of protection of the present invention.

[0018] Example 1 like Figure 1-5 As shown, a carbon fiber composite annular joint with a thickness of 64mm has a basic shape of a flange with an annular boss. It includes: a composite joint body 1 (i.e., the preform in the invention description), comprising a matrix 3, a coating layer 4 laid on the surface of the matrix 3, an adhesive film 5 between the matrix 3 and the coating layer 4, and between the matrix 3 and the coating layer 4; and a metal insert 2, which is a T-shaped platform with a planar symmetrical structure. Its small end has a threaded hole for connection to an external mechanism, and its large end has a flat cut surface to prevent circumferential rotation of the metal insert. The composite joint body 1 has a maximum thickness of 64mm, and the flange face has 40 connection holes for installing metal inserts 2 of corresponding size and quantity.

[0019] In this embodiment, there are two substrates, each approximately 24mm thick. They are formed by unidirectional prepreg layup and hot pressing. The molding process design divides the large-thickness composite joint (maximum thickness 64mm) into single-cured 24mm thick components, ensuring the quality of substrate curing and guaranteeing its axial load-bearing capacity under tensile stress. HY528 adhesive film is used between substrates and between the substrate and the covering layer to improve adhesion. The covering layer uses woven prepreg layup (prepreg material is the same as the substrate material), simultaneously covering both substrates and co-curing them with the adhesive film to improve the integrity of the composite joint and ensure its shear resistance.

[0020] The specific implementation method of the 64mm thick carbon fiber composite ring joint manufacturing method in this embodiment includes the following steps: (1) Substrate preparation: In the assembled female mold, the first layer of substrate material is laid according to the process document requirements. The mold and the male mold are installed in sequence, and the mold is heated and pressed by a press for curing and demolding. The mold is placed in the assembled female mold, and the second layer of substrate material is laid according to the process document requirements. The mold and the male mold are installed in sequence, and the mold is heated and pressed by a press for curing and demolding.

[0021] (2) Machining of the substrate: After the substrate is demolded, it is machined to the specified substrate size according to the process document requirements.

[0022] (3) Covering layer laying: In the assembled female mold, the covering layer sheet is laid according to the process document requirements.

[0023] (4) Fabrication of composite material joints: A layer of adhesive film is pasted on the surface of the coating layer. The substrate layers are placed in sequence according to the process documents. A layer of adhesive film is pasted after each substrate layer is placed. After the top substrate layer is placed and the adhesive film is pasted, the outermost coating layer is flipped over layer by layer to cover the adhesive film. The total thickness after coating is completed exceeds 64mm.

[0024] (5) Curing: The male mold and female mold are joined together and hoisted onto the press platform. Thermocouples are arranged around the mold. The mold is pressurized and cured to a thickness of 64mm according to the temperature / pressure-time curing curve required by the process document. After curing, the pressure is released and the mold is demolded.

[0025] (6) Machining: Machining the metal insert mounting holes on the composite material joint body after demolding.

[0026] (7) Metal insert installation: After applying adhesive to the outer surface of the metal insert and the inner surface of the mounting hole, install it into the mounting hole and cure it.

[0027] Figure 5 The internal quality of the thick composite material joint sample prepared in this embodiment was demonstrated by DR nondestructive testing. The test results showed no internal defects such as delamination, cracks, or pores. After the composite material joint was formed, a load-bearing test was conducted. The ultimate bearing pressure was 15.3 MPa. The failure site was local fracture along the root of the boss, accompanied by the breakage and pull-out of some metal inserts. The load-bearing capacity of the composite material joint met the usage requirements, and the failure mode was normal.

[0028] Example 2 like Figure 2 As shown, the composite joint material in this embodiment has a body thickness of 90mm, and the number of substrates is 3, with each substrate having a thickness of approximately 25mm. The materials used and the molding process are the same as in Embodiment 1. By designing the molding process scheme, the large-thickness composite material joint with a maximum thickness of 90mm is divided into components that are cured in a single step and are 25mm thick, ensuring the molding quality of the large-thickness composite material joint.

[0029] Assembling the above methods and steps into a program and storing it on a hard disk or other non-transitory storage medium constitutes an embodiment of the present invention's "a non-transitory readable recording medium"; while electrically connecting the storage medium to a computer processor and using data processing to complete the manufacturing of carbon fiber composite ring joints with a thickness exceeding 60mm constitutes an embodiment of the present invention's "a carbon fiber composite ring joint manufacturing system with a thickness exceeding 60mm".

[0030] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computers or available storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0031] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0032] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0033] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0034] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for manufacturing a carbon fiber composite ring joint with a thickness exceeding 60 mm, characterized in that, Includes the following steps: S1. The computer divides the carbon fiber composite ring joint model into multiple matrix models with a thickness of 20-40mm along the thickness direction. A mold is set for each matrix model. Carbon fiber composite ring matrix sheets are stacked in the mold, heated and pressurized to cure and demold. The matrix is ​​then processed to the specified matrix size according to the process document requirements to complete the fabrication of all the matrix. S2. Stack all the substrates into a preform according to the shape of the carbon fiber composite ring joint. When stacking, place a layer of adhesive film between adjacent substrates to separate them. Cover the outer surface of the preform with a covering layer of the same material as the preform. The side of the covering layer that is in contact with the preform is covered with adhesive film. S3. Place the preform with the coating layer into the mold and close the mold. Pressurize and cure to the designed thickness according to the temperature / pressure-time curing curve required by the process document. After curing, release the pressure and demold. S4. Multiple stepped holes are machined in a ring-shaped pattern relative to the center of the joint body of the carbon fiber composite material after demolding. An internal thread blind hole bushing is inserted, wherein the opening of the embedded internal thread blind hole faces the mating end face, the stepped surface is on the opposite side of the mating end face, and a base for fitting the internal thread blind hole bushing is used. The center of gravity of the base is located outside the cylindrical surface where the central axis of all internal thread blind holes is located. S5. The internal thread blind hole bushing is a metal product that fits with the stepped hole with a clearance. Adhesive is applied to the clearance and cured to achieve a firm embedding.

2. The method for manufacturing a carbon fiber composite ring joint with a thickness exceeding 60 mm according to claim 1, characterized in that, The heating and pressurization in step S1 can be achieved using either a press or a vacuum autoclave.

3. The method for manufacturing a carbon fiber composite ring joint with a thickness exceeding 60 mm according to claim 2, characterized in that, In step S1, the matrix model is divided into multiple base models with a thickness of 20-40mm in equal parts.

4. A non-transitory readable recording medium for storing one or more programs containing multiple instructions, characterized in that, When the instruction is executed, the processing circuit will perform the method for manufacturing a carbon fiber composite ring joint with a thickness exceeding 60 mm as described in any one of claims 1-3.

5. A manufacturing system for a carbon fiber composite ring joint with a thickness exceeding 60 mm, comprising a processing circuit and a memory electrically coupled thereto, characterized in that, The memory is configured to store at least one program, the program containing multiple instructions, and the processing circuit runs the program to perform the method for manufacturing a carbon fiber composite ring joint with a thickness exceeding 60 mm as described in any one of claims 1-3.

6. A carbon fiber composite ring joint with a thickness exceeding 60 mm, characterized in that, Manufactured by the method described in any one of claims 1-2, comprising a connector body and an internally threaded blind hole bushing, wherein the connector body comprises an inner preform, a middle layer of adhesive film and an outer covering layer, wherein the preform and the covering layer are both made of the same carbon fiber composite material; the preform is composed of multiple substrates with a thickness of 20-40 mm stacked together, adjacent substrates are separated by adhesive film, and each substrate is a stacked and clamped component of multiple layers of annular substrate sheets; The internal thread blind hole bushing includes a blind hole liner with a base connected to one end. The connector body has multiple stepped holes evenly distributed in a ring relative to the center of the connector for embedding the internal thread blind hole bushing. The opening of the internal thread blind hole faces the mating end face, and the stepped surface is on the opposite side of the mating end face for fitting the base of the internal thread blind hole bushing. The center of gravity of the base is located outside the cylindrical surface where the central axis of all internal thread blind holes is located. The internal thread blind hole bushing and the stepped hole are clearance fitted.

7. The carbon fiber composite ring joint with a thickness exceeding 60 mm according to claim 6, characterized in that, All the matrix layers stacked to form the embryo have the same thickness.

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