Configuration of Spatial Iron-Free Inductors for High-Frequency Induction Heating of Metal Strips

The chapter focuses on finding the geometric configuration of iron-free electromagnetic field inductors in the form of current contours intended for heat treatment of metal strips, the induction heating of which is carried out when they move in transverse high-frequency field. Inverse field theory problems are solved using approximate methods in a given class of contour configurations, as parametric optimization problems. It is substantiated the expediency of using inductors in the form of current spatial contours with edges raised above the surface, for which the significantly lower heating temperature non-uniformity across the width of the strip is achieved compared to the traditional approach, when using the flat contours with current. The optimal configurations of spatial inductors are found for the following important practical heating conditions: the linear density of the electromagnetic energy flux does not exceed the specified maximum value; does not fall below the specified minimum value; has minimum deviation from the average value at a certain width. Methods for achieving uniform heating of non-ferrous and ferrous metal strips over the entire width and in the local area are analyzed. It is shown that with uniform heating over the entire width of the tapes, the edges of the contours of the optimal configuration should be raised from the surface to greater distance with lower slope, compared with the optimal geometry of the contours for heating the local area of the strip.