The heating and cooling of the RTM molding mold can adopt the step constant temperature method. There are three stages. First, the heating process. The mold is heated with high-temperature heat-conducting oil. The resin is melted and stabilized for a period of time. The gas in the lower prepreg is fully driven and led out, and then sucked away by the vacuum system. This stage is also an important stage for ensuring the porosity of the product. Therefore, the temperature setting and duration of the first stage are very important. It is necessary to fully grasp the design of the process parameters of the molding and the operation and control of the high-temperature thermal oil heater .
The use of high temperature for RTM molding, the role of the second stage of carbon fiber molding is to continue to rise to the curing temperature, it is necessary to maintain the temperature at about 130-180 degrees for nearly an hour. The curing reaction occurs during this period. The temperature control requirements at this stage are very high, so that the material fully reacts without causing the resin's exothermic peak temperature to be too high. Excessive exothermic peaks will cause large internal stresses in the product, will cause large shrinkage and wrinkles, and will also damage the life of the mold.
The PLC's high temperature PLC automatically controls the temperature and time, which effectively improves the product performance and gives you peace of mind. Product calls for environmental protection. At present, the market share of electric heating accounts for 90%, and the use of heat transfer oil to reduce temperature is used as a heating medium to control the temperature of heating equipment. Carbon fiber products need to control the temperature of the mold. Most customers will choose the oil temperature machine or water temperature machine according to the temperature requirements. Xiaobian mainly introduces the role of oil temperature machine in carbon fiber compression molding.
Since the composite material lamination molding technology is to laminate the dipped sheets layer by layer and put them into a mold or a flat plate to heat and press / consolidate, the product quality and performance stability are significantly improved, and Production has a high degree of mechanization and automation, but there are also some disadvantages. For example, product size and specifications are limited by equipment, which is not suitable for producing products with complex shapes and structures. High one-time investment, mostly indirect production, and low efficiency. In addition, the lamination molding process is relatively simple, but the quality control of its products is indeed a complex issue, so its process operation requirements are also very strict.
Therefore, in order to solve the problem of low efficiency of thermoplastic composite laminate pressing equipment, many domestic manufacturers independently developed the key equipment with the ability to continuously prepare thermoplastic composite laminates --- double steel belt press. The temperature can be as high as 350 ° C, and it can process composite honeycomb sandwich panels with a width of 1.6m and a thickness of 35mm. The running speed is continuously adjusted from 0 to 4m / min, which can adapt to common general and high-performance thermoplastic resin-based composite laminates. Of molding.
For the hot plate heating of the press, heat transfer oil heaters and steam heating can be used. However, electric heating is gradually phased out due to the cold end and certain safety risks. Steam is a saturated gas and the heating rate is relatively fast. However, due to the diversification of composite materials, which involves cooling and some processes There are some limitations to the curve of the steam heating process.