Lossless connection method for composite material correcting and pressing frame

Abstract

The invention provides a nondestructive connection method for a composite material straightening and pressing frame, which enables the straightening and pressing frame made of a composite material to be stably and reliably connected with an external connecting piece, does not damage the surface integrity of the composite material, and meets the connection requirement of a designed load working condition. The method is characterized in that metal embedded parts are manufactured in advance according to external connecting positions of a composite material right-pushing-down frame, then the metal embedded parts are embedded in areas among multiple layers of composite materials in the composite material forming stage, and avoiding holes are formed in the positions, corresponding to connecting holes of the metal embedded parts, of the composite materials when the composite materials are stacked and laid. And then the metal embedded part and the multi-layer composite material are manufactured into the composite material correcting and pressing frame through a composite material autoclave forming process.

Description

Technical Field

[0001] The invention relates to the technical field of composite material production, in particular to a lossless connection method for composite material alignment and pressing frames. Background Art

[0002] With the widespread application of composite materials in high-end equipment such as aerospace, new energy vehicles, and rail transportation, their connection technology has become a key link affecting the overall structural performance and reliability. Traditional composite material connection methods, such as punching and riveting, bolting, etc. in mechanical connections. These connection methods will inevitably cut long fibers on the composite material frame, causing local damage and leading to stress concentration in the connection area, resulting in cracking and breakage. Although conventional bonding technology can maintain surface integrity, under complex working conditions such as high and low temperature cycles and humidity changes, the bonding interface is prone to debonding, aging, and other problems, leading to connection failure. At the same time, the connection strength of bonding technology is difficult to meet the needs of larger load conditions.

[0003] Therefore, an innovative lossless connection design method for composite frames is urgently needed to solve the above technical difficulties. Summary of the Invention

[0004] In response to the above problems, the present invention provides a lossless connection method for a composite material straightening and pressing frame, which makes the connection between the straightening and pressing frame made of composite materials and external connecting parts stable and reliable, and will not destroy the surface integrity of the composite materials, thereby meeting the connection requirements of the designed load conditions.

[0005] A lossless connection method for composite material straightening and pressing frames, characterized by:

[0006] According to the connection positions of the peripherals of the composite material straightening and pressing down frame, metal embedded parts are pre-made, and then the metal embedded parts are embedded in the area between the multiple layers of composite materials in the composite material forming stage. When the composite materials are stacked and laid, avoidance holes are provided at the positions of the connection holes of the metal embedded parts. Then, the metal embedded parts and the multiple layers of composite materials are made into a composite material straightening and pressing down frame through a composite material autoclave forming process.

[0007] It is further characterized by:

[0008] The metal embedded part is further provided with a protruding connecting rod, one end of which is inserted into a positioning hole of the metal embedded part, and the other end of which penetrates the composite material of the stacked part. A corresponding positioning position of the protruding end of the connecting rod is provided on the mold for forming the composite material in an autoclave, so that an avoidance hole for docking with the metal embedded part is formed during the autoclave forming of the composite material.

[0009] After the composite material is formed in the autoclave, the corresponding connecting rod is taken out;

[0010] The connection between the connecting rod and the metal embedded part is a threaded connection, which makes the connecting rod quick and convenient to remove and facilitates the rapid connection of the composite material alignment and downward pressing frame with the rest of the structure;

[0011] The metal embedded parts are titanium alloy embedded parts, which makes the weight of the entire embedded parts relatively small, reducing the weight while ensuring the strength;

[0012] The metal embedded parts are formed by an additive manufacturing process. During the design phase, the maximum load position is confirmed through finite element calculation, and topological optimization and lightweight design are carried out simultaneously. The structural design adopts cavity reinforcement beams and cavity lattice methods, which not only ensures the reliability of the connection parts, but also improves the strength of the entire composite material structure.

[0013] After adopting the above technical solution, metal embedded parts are set and manufactured in advance according to the situation at the positions where connecting screw holes need to be set in the composite material straightening and pressing frame. The metal embedded parts are provided with corresponding connecting screw holes. Then the metal embedded parts are embedded in the stacked composite material, and the composite material is provided with avoidance holes corresponding to the screw hole positions of the metal embedded parts. Then the metal embedded parts and the multi-layer composite material are made into a composite material straightening and pressing frame through a composite material autoclave molding process. Finally, the external connecting parts are connected to the corresponding connecting screw holes of the metal embedded parts after passing through the avoidance holes through connecting bolts, etc., which makes the connection between the straightening and pressing frame made of the composite material and the external connecting parts stable and reliable, and will not destroy the surface integrity of the composite material, thereby meeting the connection requirements of the design load conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic diagram of the partial assembly of the composite material alignment and downward pressing frame and the external connecting parts after the composite material alignment and downward pressing frame is completed according to a specific embodiment of the present invention;

[0015] Figure 2 for Figure 1 A perspective view of the assembly of the composite material adjustment and pressure frame and external connecting parts;

[0016] Figure 3 A top view of a metal embedded part applicable to a specific embodiment;

[0017] The names corresponding to the serial numbers in the figure are as follows:

[0018] The composite material is adjusted to press down the frame 10 , the metal embedded parts 20 , and the external connecting parts 30 . DETAILED DESCRIPTION

[0019] A lossless connection method for composite material straightening and pressing frame, see Figure 1-Figure 3: According to the connection position of the peripherals of the composite material straightening and pressing frame 10, the metal embedded parts 20 are pre-made, and then the metal embedded parts 20 are embedded in the area between the multiple layers of composite materials in the composite material forming stage. When the composite materials are stacked and paved, avoidance holes are provided at the positions of the connection holes of the metal embedded parts 20. Then, the metal embedded parts 20 and the multiple layers of composite materials are made into a composite material straightening and pressing frame through a composite material autoclave forming process.

[0020] The composite material autoclave molding process is a method of sealing the composite material blank on a mold with a vacuum bag, placing it in an autoclave, and molding it into the required advanced composite materials and their components under vacuum (or non-vacuum) conditions. The principle is to use the high-temperature compressed gas inside the autoclave to generate pressure to heat and pressurize the composite material blank to complete the curing molding. It is an existing mature composite material processing technology.

[0021] The forming process of the avoidance hole during the composite material stacking is as follows: the metal embedded part 20 is also provided with a protruding connecting rod, one end of the connecting rod is inserted into the positioning hole of the metal embedded part 20, and the other end of the connecting rod passes through the composite material of the stacked part. The corresponding composite material autoclave molding mold is provided with a positioning position of the protruding end of the connecting rod, which enables the composite material to be squeezed by pressure during the composite material autoclave molding operation so that the composite material is squeezed around the outer periphery of the connecting rod to form an avoidance hole docking with the metal embedded part 20; the corresponding connecting rod is taken out after the composite material autoclave molding.

[0022] In specific implementation, the connection between the connecting rod and the metal embedded part 20 is a threaded connection, which makes the removal of the connecting rod quick and convenient, and facilitates the rapid connection of the composite material adjustment and pressing frame with the rest of the structure;

[0023] The metal embedded part 20 is a titanium alloy embedded part, which makes the weight of the entire embedded part relatively small, reducing the weight while ensuring strength;

[0024] The metal embedded parts 20 are formed by additive manufacturing technology. During the design phase, the maximum load position is confirmed through finite element calculation, and topological optimization lightweight design is carried out simultaneously. The structure is designed using cavity rib beams and cavity lattices, which not only ensures the reliability of the connection parts, but also improves the strength of the entire composite material structure.

[0025] During specific implementation, the composite material straightening and pressing frame 10 is provided with metal embedded parts 20 at different positions according to needs, so as to be assembled and docked with the external connecting parts 30 at corresponding positions, and the positions of the metal embedded parts 20 can be on the inner surface, outside, and corresponding side positions of the composite material straightening and pressing frame 10. After the metal embedded parts 20 at corresponding positions are pre-made according to actual needs, they are embedded between the stacked composite materials, and corresponding avoidance holes are formed through connecting rods when the composite material is hot-pressed in a hot-pressing tank.

[0026] The principle is as follows: where the composite material straightening and pressing frame needs to have connecting screw holes, metal embedded parts are set up in advance according to the situation and made. The metal embedded parts are provided with corresponding connecting screw holes. The metal embedded parts are then embedded in the stacked composite material, and the composite material is provided with avoidance holes corresponding to the screw hole positions of the metal embedded parts. The metal embedded parts and the multi-layer composite material are then made into a composite material straightening and pressing frame through a composite material autoclave molding process. Finally, the external connecting parts are connected to the corresponding connecting screw holes of the metal embedded parts after passing through the avoidance holes through connecting bolts.

[0027] The intended effects are as follows:

[0028] 1. High-strength connection: The main load-bearing structure of the connection part is titanium alloy embedded parts, which has high structural strength and is suitable for various complex working conditions such as tension, compression, bending and shearing. It has high connection strength and stable reliability.

[0029] 2. Lossless Connection: This invention uses a metal additive manufacturing process to pre-print titanium alloy connectors for connection locations. These pre-embedded titanium alloy connectors ensure continuity during the composite material forming phase. The use of titanium alloy pre-embedded components also eliminates the need for machining the composite material structure for subsequent connection solutions, ensuring the continuity of the composite material fibers and improving the strength and durability of the composite material structure.

[0030] 3. Process compatibility: This method is compatible with the existing composite autoclave molding process, does not require additional complex equipment, and can achieve industrial mass production.

[0031] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0032] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A lossless connection method for composite material straightening and pressing frames, characterized by: According to the connection positions of the peripherals of the composite material straightening and pressing down frame, metal embedded parts are pre-made, and then the metal embedded parts are embedded in the area between the multiple layers of composite materials in the composite material forming stage. When the composite materials are stacked and laid, avoidance holes are provided at the positions of the connection holes of the metal embedded parts. Then, the metal embedded parts and the multiple layers of composite materials are made into a composite material straightening and pressing down frame through a composite material autoclave forming process.

2. The method for non-destructive connection of composite material alignment and pressing frames according to claim 1, characterized in that: The metal embedded part is also equipped with an outward-convex connecting rod, one end of which is inserted into the positioning hole of the metal embedded part, and the other end of the connecting rod passes through the composite material of the stacked part. The corresponding composite material autoclave molding mold is provided with a positioning position of the outward-convex end of the connecting rod, which enables an avoidance hole for docking with the metal embedded part to be formed during the composite material autoclave molding.

3. The method for non-destructive connection of composite material alignment and pressing frames according to claim 2, characterized in that: After the composite material is formed in the autoclave, the corresponding connecting rod is taken out.

4. The method for non-destructive connection of composite material alignment and pressing frames according to claim 2, characterized in that: The connection between the connecting rod and the metal embedded part is a threaded connection.

5. The method for non-destructive connection of composite material alignment and pressing frames according to claim 1, characterized in that: The metal embedded parts are titanium alloy embedded parts.

6. The method for non-destructive connection of composite material alignment and pressing frames according to claim 1, characterized in that: The metal embedded parts are formed by an additive manufacturing process. During the design phase, the maximum load position is confirmed through finite element calculation, and topological optimization and lightweight design are carried out simultaneously. The structural design adopts cavity reinforcement beams and cavity lattice methods, which not only ensures the reliability of the connection parts, but also improves the strength of the entire composite material structure.

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