At present, in the field of material science, the energy-saving technology of induction heating is mainly used in the processing industry of plastic and rubber products, such as extruder, injection molding machine, granulator, etc., it can melt, mix and plasticize the plastic raw materials, and can replace the traditional resistance heating method. It can effectively improve the thermal efficiency and power saving rate of the equipment with it, and the operation is flexible and convenient, and the control accuracy and stability are improved. But it is less used in chemical fiber industry.
Due to the low accuracy of resistance heating air drying method, it has been unable to meet the requirements of the current process development of carbon fiber preparation. The energy-saving technology of induction heating roller is applied in the field of carbon fiber preparation. Taking the drying process of carbon fiber surface treatment as an example, here introduces the implementation and effect of this technology, so as to further expand the application of energy-saving technology.
Electromagnetic induction is the phenomenon of induced electromotive force caused by the change of magnetic flux. Electromagnetic induction heating is under the action of a certain frequency of AC current, the induction eddy current is formed, so as to generate heat, so that the roller body itself is heated, and the temperature rises rapidly.
The surface treatment process of carbon fiber mainly includes electrolysis, water washing, water washing and drying, sizing, sizing and drying. The purpose is to avoid the adsorption of moisture and dust in the air on the surface of carbon fiber, improve the wettability with the matrix resin, and reduce the occurrence of wool phenomenon. In the experiment, the induction heating roller is applied to the drying roller device after carbon fiber sizing, so that the induction heating roller can achieve rapid response when the heating speed is controlled. The induction heating roller device is shown in the figure below.
The device adopts horizontal frame, and the hot rollers are arranged up and down. It is driven by direct motor or gear. It can be adjusted by frequency conversion. The heating roller runs at the same speed. After installation, the radial runout of the far end of the heating roller is ≤ 0.03mm, and the parallelism is ≤ 0.02mm. The pressure range of the two rollers is from 370 kg to 120 kg, and the pressure of the two rollers can be adjusted.
The temperature of heating roller device is controlled by multi-stage electromagnetic induction, with the medium frequency current. Each roller can control temperature independently.
The induction heating roller device for carbon fiber surface treatment is made of carbon steel, and the surface is chrome plated. The main specification parameters are: the diameter of the roller body is 500mm, the width of the roller body is 1000mm, the effective working temperature zone is 800mm, the design maximum temperature is 200 ℃, the surface temperature uniformity of the roller is less than ± 1 ℃, the gear transmission has grade 6 precision and no noise.
Using the energy-saving technology of induction heating roller to dry the carbon fiber after surface treatment and sizing has the advantages of accurate temperature control, high efficiency and energy saving, simple operation, safety and environmental protection, and can effectively protect the surface structure of the fiber, reduce the moisture content, facilitate the expansion of the tows, and contribute to the interface composite of the carbon fiber tows and the matrix.
In the process of carbon fiber preparation, after the raw materials are polymerized into fibers, they have to go through the processes of pre oxidation, carbonization and surface treatment. The process is long and involves many sections of drying treatment, such as pre drying of precursor and drying after oiling. The energy-saving technology of induction heating can improve the accuracy and effect of drying temperature, and has little influence on the structure and performance of the fiber. It has practical value and economic significance, and can be applied to the drying treatment of the whole process of carbon fiber preparation.