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The molding process is a certain amount of prepreg into the metal mold cavity of the mold, the use of presses with a heat source to produce a certain temperature and pressure so that the prepreg in the mold cavity is softened by heat, pressure flow, full of flow, filled with the mold cavity molding and curing products of a process method.
The molding process is characterized by the need for heating in the molding process, the purpose of heating is to make the prepreg resin softening flow, full of mold cavity, and accelerate the curing reaction of the resin matrix material. During the process of filling the mold cavity with prepreg, not only the resin matrix flows, but also the reinforcing material, and the resin matrix and reinforcing fibers fill all parts of the mold cavity simultaneously.
Only the resin matrix viscosity is very large, and the bond is very strong enough to flow with the reinforcing fibers, so the molding process requires a greater molding pressure. This requires metal molds with high strength, high precision, and corrosion resistance, and it requires the use of special hot presses to control the temperature of the curing molding, pressure, holding time, and other process parameters.
The molding method of high production efficiency, product size accuracy, and surface finish, especially for the complex structure of the composite material products can generally be molded once, and will not damage the performance of the composite material products. Its main shortcoming is that the mold design and manufacturing are more complex, and the initial investment is larger. Although the molding process has the above shortcomings, the mold molding process still occupies an important position in the composite material molding process.
1. Preparation
Do a good job of prepreg, molding tooling molds, with the furnace test piece of supporting work, and clean up the mold in the last use of residual resin, and debris, to keep the mold clean and smooth.
2. Cutting and laying of prepregs
Will be made into a product of carbon fiber raw materials ready, prepreg after passing the review, calculate the area of raw materials, materials, the number of sheets, the raw material layer by layer of incense added up, at the same time on the superposition of the material for the pre-pressure, pressed into the shape of a regular, the quality of a certain number of dense entities.
3. Molding and curing
Place the stacked raw materials into the mold, and at the same time in the internal plastic airbags, close the mold, the whole into the molding machine, the internal plastic airbags plus a certain constant pressure, constant temperature, set a constant time so that it’s curing.
4. Cooling and demolding
After a period of time of pressure outside the mold first cold know for a period of time, and then open the mold, demolding outside the eye to clean up the tooling mold.
5. Processing molding
After demolding the product needs to be cleaned up, with a steel brush or copper brush to scrape off the residual plastic, and blowing with compressed air, the molded product is polished, so that the surface is smooth and clean.
6. Nondestructive testing and final inspection
Non-destructive testing and final inspection of the products are carried out according to the requirements of the design documents.
Since the birth of carbon fiber composites, always limited by the manufacturing cost and production beat, has not been applied in large quantities. The decision of carbon fiber production cost and beat is the molding process, carbon fiber composite material molding process there are many, such as RTM, VARI, hot press tank, oven curing prepreg (OOA), etc., but there are two bottlenecks: 1, the molding cycle time is long; 2, the price is expensive (compared to metal and plastic). Prepreg molding process, as a kind of molding process, can realize batch production and reduce production cost, which is more and more widely used.