A method for automated fiber placement in honeycomb processing

Abstract

This invention discloses a honeycomb processing method for automatic fiber placement. S1. A first structural adhesive film (4) is applied around the outer edge of the honeycomb (3); S2. An expanded adhesive film (2) is applied around the entire chamfered area of ​​the honeycomb (3); S3. A second structural adhesive film (1) is applied around the entire inner surface of the honeycomb (3); S4. The honeycomb (3) with the adhesive films applied is vacuum pre-formed. This invention is characterized by its simplicity, versatility, and ease of implementation.

Description

Technical Field

[0001] This invention belongs to the field of honeycomb structure design technology, specifically relating to a honeycomb processing method for automatic fiber placement. Background Technology

[0002] Automated fiber placement technology, as a novel, low-cost, and high-efficiency automated manufacturing technology for composite materials, boasts outstanding advantages such as high forming accuracy, stable quality, and wide applicability. It can achieve layer opening and reinforcement during the placement process, improving production efficiency and material utilization. Automated fiber placement technology is one of the fastest-growing and most effective automated forming and manufacturing technologies for composite materials in recent years.

[0003] Currently, automated fiber placement technology is widely used in laminated structure manufacturing, but its application in composite honeycomb sandwich structure manufacturing is relatively limited. In the aerospace field, composite honeycomb sandwich structures account for a high proportion of composite parts. Applying automated fiber placement technology to the manufacturing of composite honeycomb sandwich structure parts will greatly improve the overall manufacturing efficiency and quality of composite parts.

[0004] Chinese patent application CN112644100A discloses a large-curvature honeycomb sandwich composite material structure and its integrated molding method. This method uses an automated fiber placement method to lay down the lower panel, then uses 3D printing to print a honeycomb structure on the upper panel, and finally uses an automated fiber placement method to lay down the upper panel on the honeycomb. While this method utilizes 3D printing to achieve integrated molding of the large-curvature honeycomb sandwich structure, it does not explain how to solve the problems of honeycomb cell crushing and poor laying effect that are easily encountered when laying fibers on the honeycomb.

[0005] Chinese patent application CN109177436A discloses an automated fiber placement method for honeycomb sandwich composite parts. This method involves creating a concave molding mold based on the shape of the composite part and adjusting the placement order of the honeycomb panels to prevent the automated fiber placement machine from placing layers at the honeycomb corners, thus solving the problem of easy slippage of the honeycomb core at these corners. However, this method cannot solve the problem of easy crushing of the honeycomb core.

[0006] Chinese patent application CN105269830A discloses a method for preforming high-thickness, low-density honeycomb cells. This method utilizes adhesive film and glass cloth prepreg applied around the honeycomb perimeter, combined with anti-slip strips to address the issue of honeycomb slippage during preforming. In this method, the prepreg and adhesive film used in the honeycomb preforming are already cured, and the cured areas are co-bonded during the formation of the honeycomb sandwich structure. The main purpose of this method in honeycomb preforming is to prevent honeycomb slippage during the formation of the honeycomb sandwich structure; however, it does not prevent the problem of easy crushing of the honeycomb lattice during automatic fiber placement. Summary of the Invention

[0007] The purpose of this invention is to provide a method for automated fiber placement in honeycomb processing. This invention is characterized by its simplicity, versatility, and ease of implementation.

[0008] The technical solution of the present invention is: a honeycomb processing method for automatic fiber placement, comprising the following steps:

[0009] S1. Lay a ring of the first structural adhesive film around the edge of the outer surface of the honeycomb;

[0010] S2. Lay an expansion film around the entire cut corner area of ​​the honeycomb;

[0011] S3. Lay a second structural adhesive film over the entire inner surface of the honeycomb;

[0012] S4. Vacuum pre-form the honeycomb with the adhesive film applied.

[0013] In the aforementioned honeycomb processing method for automatic fiber placement, the laying width of the first structural adhesive film is 10-15 mm.

[0014] In the aforementioned honeycomb processing method for automatic fiber placement, both the first and second structural adhesive films are high-temperature curing carrier films with a thickness of 0.25 mm.

[0015] In the aforementioned honeycomb processing method for automatic fiber placement, the expanding adhesive film is a medium-temperature curing adhesive film.

[0016] In the aforementioned honeycomb processing method for automatic fiber placement, step S4 is as follows: the honeycomb with the adhesive film laid on it is placed in a preforming mold, vacuum-sealed and put into an oven for preforming.

[0017] In the aforementioned honeycomb processing method for automatic fiber placement, during preforming, the expanded adhesive film is cured, while the structural adhesive film melts but does not cure.

[0018] In the aforementioned honeycomb processing method for automatic fiber placement, the pre-forming temperature is 120℃±5℃.

[0019] In the aforementioned honeycomb processing method for automatic fiber placement, the cut corner area of ​​the honeycomb is set at a right angle or oblique angle relative to the outer surface of the honeycomb.

[0020] The advantages of this invention are:

[0021] 1. The honeycomb processing method for automatic fiber placement of the present invention has the advantages of being simple, versatile and easy to implement. It can solve the problems of easy crushing of honeycomb and poor laying effect on the honeycomb surface when the automatic fiber placement method is used to manufacture honeycomb sandwich structures, and various failures are prone to occur. It facilitates the use of automatic fiber placement technology in the manufacturing of honeycomb sandwich structures and can improve product quality and production efficiency.

[0022] 2. Compared with traditional honeycomb, the pre-formed honeycomb of this invention has the following advantages: the adhesive film and the honeycomb core cell as a whole bear the load of the fiber placement head pressure roller, which can prevent the honeycomb core cell from being crushed; the adhesive film increases the contact area when the fiber bundles are laid, and the viscosity of the uncured adhesive film can be increased by heating during the laying, which facilitates the laying and bonding of the fiber bundles; the expanded adhesive film in the corner area around the honeycomb can achieve good bonding in the area where the vacuum bag is not pressurized, thereby improving the rigidity of the honeycomb edge and ensuring the quality of automatic fiber placement at the honeycomb boundary; the structural adhesive film is not cured during the pre-forming process, which does not affect the mechanical properties of the structural component after it is formed.

[0023] 3. The structural adhesive film and expanding adhesive film used in the honeycomb preforming are all conventionally used materials; the preforming process is similar to the process of medium-temperature curing composite parts. This method is applicable to both right-angle honeycombs and oblique-angle honeycombs, and is highly versatile and easy to implement. Attached Figure Description

[0024] Figure 1 This is a diagram illustrating the film laying process during the preforming of right-angled honeycomb structures.

[0025] Figure 2 This is a diagram illustrating the film laying process during the preforming of beveled honeycomb. Detailed Implementation

[0026] 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 clearly and completely described below with reference to the accompanying drawings. Obviously, 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 creative effort are within the scope of protection of the present invention.

[0027] The features and illustrative embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific setups and methods set forth below, but covers any improvements, substitutions, and modifications to structures, methods, and devices without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description to avoid unnecessarily obscuring the invention.

[0028] It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other, and the various embodiments can be referenced and cited in each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] Example 1. A method for automated fiber placement in honeycomb processing, see [link to example]. Figures 1-2 It includes the following steps:

[0030] S1. Complete the cutting of honeycomb 3 according to the model or unfolded template; lay a ring of first structural adhesive film 4 around the outer edge of the honeycomb 3;

[0031] S2. Lay an expansion film 2 around the entire chamfered area of ​​honeycomb 3;

[0032] S3. Lay the second structural adhesive film 1 on the entire inner surface of the honeycomb 3;

[0033] S4. Vacuum pre-form the honeycomb 3 with the adhesive film applied; the pre-formed honeycomb can then be used for the manufacture of automated wire-lay honeycomb sandwich structure components.

[0034] The first structural adhesive film 4 has a laying width of 10-15mm. This size reduces the structural weight while meeting the requirements of honeycomb preforming.

[0035] Both the first and second structural films are high-temperature curing carrier films with a thickness of 0.25 mm.

[0036] Expanding adhesive film 2 is a medium-temperature curing adhesive film.

[0037] The structural adhesive film is a high-temperature curing carrier film with a thickness of 0.25mm. This thickness of film can better bond with the honeycomb, meet the needs of subsequent automatic fiber placement, and balance the molding weight requirements of composite parts. The expansion adhesive film is a medium-temperature curing film.

[0038] Step S4 is as follows: Place the honeycomb 3 with the adhesive film applied into the pre-forming mold, vacuum bag it and put it into the oven for pre-forming.

[0039] During preforming, the expanding adhesive film cures, while the structural adhesive film melts but does not cure.

[0040] The preforming temperature is 120℃±5℃. The honeycomb structure with the adhesive film applied is placed in a preforming mold, vacuum-sealed, and then preformed in an oven. The preforming temperature is set at a temperature where the expanding adhesive film cures at a medium temperature and the structural adhesive film melts but does not solidify (e.g., 120℃±5℃). After honeycomb preforming, the adhesive film melts, the expanding adhesive film solidifies, and it bonds with the honeycomb to form a unified structure with good rigidity on the inner surface and at the chamfered corners.

[0041] The chamfered area of ​​the honeycomb 3 is set at a right angle or an oblique angle relative to the outer surface of the honeycomb 3.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should be covered within the protection scope of the present invention.

Claims

1. A method for automated fiber placement in honeycomb processing, characterized in that, Includes the following steps: S1. A ring of first structural adhesive film (4) is laid around the edge of the outer surface of the honeycomb (3); S2. Lay an expansion film (2) around the entire chamfered area of ​​the honeycomb (3); S3. Lay a second structural adhesive film (1) over the entire inner surface of the honeycomb (3); S4. Vacuum preforming is performed on the honeycomb (3) with the adhesive film laid on it; during preforming, the expanding adhesive film is cured, and the structural adhesive film melts but does not cure; Both the first and second structural adhesive films are high-temperature curing carrier films with a thickness of 0.25 mm; The expanding adhesive film (2) is a medium-temperature curing adhesive film.

2. The honeycomb processing method for automatic fiber placement according to claim 1, characterized in that, The width of the first structural adhesive film (4) is 10-15 mm.

3. The honeycomb processing method for automatic fiber placement according to claim 1, characterized in that, Step S4 is as follows: Place the honeycomb (3) with the adhesive film laid on it into the pre-forming mold, vacuum bag it and put it into the oven for pre-forming.

4. The honeycomb processing method for automatic fiber placement according to claim 1, characterized in that, The preforming temperature is 120℃±5℃.

5. The honeycomb processing method for automatic fiber placement according to claim 1, characterized in that, The chamfered area of ​​the honeycomb (3) is set at a right angle or oblique angle relative to the outer surface of the honeycomb (3).

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