The design of carbon fiber composite materials is the foundation, and molding is the key. Molding technology and equipment are the key points of molding composite materials. With the widespread use of composite materials on aircraft, various corresponding advanced molding technologies have also developed rapidly. Advanced prepregs Preparation technology, automatic tape laying (silk) technology and equipment, laser projection, laser tracker, tooling design and processing, etc. all provide a solid foundation for the molding of composite materials.
Wing panel forming process
At present, there are 4 common processes for forming large-size stiffened wall panels:
1. Secondary bonding (the long stringer and the skin are cured separately, and then the secondary bonding is assembled);
2. Co-curing (the skin and the long stringer are separately laid and pre-formed, and then assembled and glued together to be cured);
3. Gluing and co-curing (the long stringer is cured first, and then co-cured with the preformed skin);
4. Gluing and co-curing (the skin is cured first, and then co-cured with the preformed long stringer).
These three molding processes have their own advantages and disadvantages. When choosing a molding method, it is necessary to determine a suitable molding method based on the product's structure, shape, and design requirements.
The molding of large-size wing carbon fiber composite wall panel structure is currently commonly used in the bonding and co-curing process. Compared with the secondary bonding, the bonding and co-curing has better bonding quality, saving the use of one-time autoclave. Higher efficiency. Compared with co-curing, the structure of the adhesive co-curing mold is relatively simple, and the tooling design and processing cost is low.
Airbus also adopts the bonding and co-curing molding method on the wing panel structure. The A400M and A350XWB carbon fiber composite wing adopts the long stringer to be cured first, and then glued and co-cured with the skin. Adopting the bonding and co-curing molding method can ensure the molding quality and processing accuracy of the long truss. When the long truss is glued and co-cured with the pre-formed skin, the bonding quality is easier to ensure, the positioning of the long truss is convenient, and the tooling cost is low.
Automatic wing belt forming technology
With the gradual increase in the proportion of carbon fiber composite materials used in aircraft, the size of carbon fiber composite components has also increased, and traditional methods such as manual layup are far from meeting the needs of the development and production of large-size structural parts. When the size of composite material parts is large, the difficulty of manual layup increases correspondingly, the molding efficiency is low, and the product quality is difficult to guarantee. Therefore, the corresponding automatic tape laying technology and automatic fiber laying technology and other automated manufacturing technologies have emerged.
At present, the more advanced tape laying machine is the French company's "Hercules" double-head automatic tape laying machine. The feature of this machine is that it has two heads for belt laying, one is laid with a weftless belt wound on a spool, and the other is laid with pre-cut materials, which can quickly lay complex shapes.
Spar forming
Due to the large structural size, variable cross-section, and complex layup of the spar, the traditional manual lay-up and molding efficiency is low. In view of this, hot diaphragm forming technology (Hot Drape Forming, HDF) with higher forming efficiency has been developed abroad. Because the hot diaphragm forming technology has special requirements for the material system, which limits the application of the new material system to the spar structure, the A350 spar discards the hot diaphragm forming technology and adopts automatic wire laying technology.
Intelligent control technology of autoclave
Autoclave forming is currently the main forming method of large-scale composite material components. In view of the uneven temperature field and large temperature difference during the curing process of large-size components, foreign countries have developed super-large autoclave systems and advanced autoclave air circulation systems. , The system can effectively reduce the temperature difference in the molding process of large-size composite material components, reduce the energy consumption per unit weight of composite material components, and help ensure the molding quality of composite material components.
Through long-term research on carbon fiber composite materials, the application ratio of carbon fiber composite materials on various models has gradually increased, and relatively mature design concepts and methods have been formed. Actively learn from and research, and strive to develop various advanced molding processes. , Equipment, testing methods and efficient assembly processes, etc., in order to meet customer needs for carbon fiber parts.