Application and development of advanced manufacturing technology for vacuum bag Composites
As we all know, vacuum bag is very common in daily life and industrial production. Naturally, whether the commodity is defined as low-end industrial production or more general industrial production. Considering the necessity of contemporary military construction and the trend of social and economic development, the key products of aviation technology industry have been upgraded to the new trend of long life and low cost with excellent performance, excellent capacity, high reliability, high comfort and low cost. Therefore, in order to meet the needs of the development of modern aviation industry.
The main composite materials are epoxy resin matrix composites and excellent polymer matrix composites. It has the characteristics of high strength, specific strain rate, fatigue resistance, corrosion resistance, excellent forming process and design scheme. It has become one of the four structural raw materials of aircraft structure. Composite materials will become one of the main development trends of new materials in the 21st century. With the continuous development and improvement of the preparation process of polymer materials, the key points of the process include: working pressure of vacuum packaging bag, Blister molding machine, compression molding process, compression molding process, cold extrusion molding process, injection molding process, winding process, extrusion processing process and compound liquid.
（1） Application of stitching / (RTM, RFI) composite technology
The polymer material used to improve the stitched fabric is composed of two-layer two-dimensional fiber fabric with excellent fiber stitches, and is formed by composite dry fixation. By stitching the composite, the physical properties of the composite can be improved, the structural efficiency of the composite can be further improved, and the net weight of the composite can be reduced. Stitching technology can also lift two or more components (such as long truss structure and skin) together to make the overall structure of large and medium-sized prefabricated components, so as to consider the requirements of new components. At present, the technology has been widely used in aviation and other fields. It is widely used in the development and production of F22, JSF and A380.
（2） Application of autoclave manufacturing technology in order to meet the needs of the expanding application of composite materials in aircraft, aircraft manufacturers are constantly improving the manufacturing technology of composite laminate vacuum bag autoclave. This technology is widely used in the production of composite parts. The new autoclave / VARTM combination molding process is a new development of resin matrix composites molding process, especially suitable for the liquid injection molding of planar and three-dimensional fabric reinforced high viscosity resin matrix composites and aerospace and other advanced composite manufacturing fields. At present, many aircraft manufacturers have adopted computer-controlled automatic blanking equipment, multi coordinate NC automatic laminating equipment, laser assisted laminating positioning system, to monitor autoclave assimilation equipment, multi coordinate NC machining and high-pressure water cutting equipment, computer-controlled nondestructive testing equipment, etc. The optimization and Simulation of composite process parameters are realized to ensure the stability of composite component production quality.
（3） Application of bonding structure manufacturing technology
Bonding technology can be used to connect two or more layers of different materials and different thicknesses. It mainly includes metal bonding structure manufacturing technology, honeycomb sandwich bonding structure technology and metal composite laminate bonding technology.
Metal bonded structure can realize large area connection and reduce (or cancel) fasteners. It has a series of advantages, such as higher specific strength, higher specific stiffness, lighter weight and longer service life. It has been widely used in aircraft structure, especially in secondary bearing structure. So far, adhesive structure has become an important structural form of aircraft fuselage. With the continuous progress of science and technology, vacuum bag is widely used in high-tech products.