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Article

Микроволновые устройства для термообработки листовых материалов с малыми диэлектрическими потерями

Мамонтов А. В., Нефедов В. Н., Симонов В. П.

Theoretical and experimental research results in the field of highperformance microwave technologies of sheet materials' with small dielectric losses thermal treatment are presented. To increase the electric field decay constant amplitude in the material with small dielectric losses sections of twodimensional periodic slowwave systems are used as heating elements. The microwave construction is based on a module, which consists of two identical in design and parameters microwave heating sections, positioned one above the other, and the electromagnetic field energy propagates along these sections in opposite directions.
Processed material is positioned between two sections. Each heating section consists of the twodimensional periodic slowwave system, which on the one hand conditions with the microwave energy source, and on the other hand conditions with the water load, in which there is a sensor of passing power for the control of technological process. The long line with given boundary conditions was used as a model of microwave devices with the processed material. Special design of filters that impede microwave radiation from a working setup were used to reduce the level of a side radiation at the input and output of the processed material. Divergence of theoretical and experimental temperature distribution characteristics in the sheet material (ebonite) with small dielectric losses does not exceed 4%, and the temperature deviation in the material from the nominal temperature value does not exceed 7%. To materials with low dielectric losses in particular, relate: polystyrene, polypropylene and polyethylene with different fillings, for example, in the form of 10% carbon black or other dyes, plexiglass, ebonite and other plastics. Heat treatment of such materials by gas or by other known methods does not lead to the whole volume uniformity of heating due to the low plastics' heat conductivity and in subsequent operations, such as pressing or stamping, cracking or other unwanted defects arise.