Experimental Research of Induction Heating in Inner Hollow of Cylindrical Solenoid

Abstract

Purpose. Experimental determination of the dependence of the magnetic field strength distributions and the density of induced currents in the metal of the tubular blank from its position in the cylindrical inductor internal hallow. Methodology. The electrodynamic problem solution using mathematical apparatus for analytical calculations. To describe the processes that arise in the material under processing, expressions for fields and currents flowing in non-magnetic metals under the action of a multi-turn cylindrical solenoid that derived from the system of Maxwell's equations. Accepted mathematical assumptions and simplifications do not affect the correctness of the results. Carrying out an experiment to determine the intensity of the magnetic field in the solenoid inner hollow and the induced currents density on the surface of the nonmagnetic blank. Results. The obtained experimental distributions of the magnetic field strength and induced currents with the full blank placement in the cylindrical inductor hollow correspond to the analytical relations derived earlier and coincide with the fundamental physical concepts of the processes taking place in the system. When the billet is partially placed in the inner hollow of the inductor, there is a sudden increase in the tangential magnetic field strength component. In this case, an extremum is observed in the end zone of the billet. This is explained by the concentration of induced currents in this region, as well as on the cylindrical surface of the billet. Originality. The average induction heating speeds correspond to the calculated values for the materials of the processed samples used in the experiment, which indicates the effectiveness of using this processing technology in equal measure, both non-magnetic metals and magnetic. The practical value of the results consists in the possibility of estimating the qualitative indices of the concentration of induced currents and heat release in the end part of nonmagnetic cylindrical preforms with their partial overlapping by an inductor to perform heating operations.