Research On High Speed Transverse Flux Induction Heating Device And Heater Structure Design

With the continuous improvement of the requirements of heat treatment process,induction heating technology has been developed rapidly.In the current heat treatment industry,for the heat treatment of metal strips such as steel has become a trend.Compared with longitudinal flux induction heating(LFIH),transverse flux induction heating(TFIH)is more suitable for heating thin metal strips,so it has been widely used.Although TFIH technology has been greatly developed,it still has the disadvantage of uneven temperature distribution on the surface of the strip in the width direction of the strip at heater outlet.This disadvantage has seriously restricted its application and promotion in the heat treatment industry.The material parameters and the moving speed of the strip,the coil structure,the exciting current parameters and the structure of heater all can affect the uniformity of the temperature distribution on the strip surface at heater outlet.In conclusion,in this paper,according to the characteristics and shortcomings of TFIH technology,the following contents are studied and analyzed by using the finite element calculation software.(1)The mathematical models of the magnetic and thermal field of TFIH are established.The finite element simulation software is used to establish the induction heating model,and a improved magnetic-thermal coupling simulation method which can consider the movement of the strip and the change of material parameters of the strip with temperature is adopted.At the same time,the heating efficiency of TFIH device is studied and analyzed,and the calculation formula of the heating efficiency is put forward.(2)Based on the induction heating model of the double hexagon coil structure,the eddy current,heat source and temperature distribution on the surface of the strip under the induction heater and the heating efficiency of TFIH device are analyzed when the material parameters are affected by temperature changes or not.Meanwhile,in view of the shortage of the strip material is single in the theoretical analysis of TFIH technology,the distribution of eddy current,heat source,temperature on the strip surface and the heating efficiency of TFIH device between high-quality carbon structural steel 45# steel and low-alloy high-strength steel 15 Mn V under the same heating conditions are compared by using the improved magnetic-thermal coupling simulation method.(3)When the strip moves at high speed,firstly,the eddy current,heat source and temperature distribution on the strip surface and the heating efficiency of TFIH device under different moving speeds of the strip are calculated and analyzed.Secondly,the influence of the change of the structure of heater coil,effective value and frequency of the exciting current on the heating results and heating efficiency are analyzed.(4)The Morris method of qualitative global sensitivity analysis is used to rank the individual sensitivities among four design parameters and three objective functions of TFIH device.The sensitivity values ranking provides an optimal priority for the optimization or change of the design parameters of TFIH device.Moreover,the correlations among multiple design parameters are analyzed by comparing the relationships among the individual sensitivities and the combined sensitivities.(5)A new TFIH device is proposed and designed since the original TFIH device has the disadvantages of high magnetic flux leakage and high magnetic resistance in the magnetic circuit.In addition,based on the new TFIH device,the excitation parameters are optimized,and a set of excitation parameters combination is given to make the temperature distribution uniformity of the strip surface at heater outlet the best.