Control device for parallel induction heating coils

摘要

A device for controlling the heat generated by induction coils in a multiple induction heating coil furnace. Multiple induction coils provide parallel cylindrical passages having axial lengths and fixed diameters through which elongated workpieces are movable in the axial direction. The axial length of one induction coil is fixed while the other coils have variable lengths as a result of an arrangement for altering the distance between first and second ends of the induction coils. Sensors detect the temperatures of workpieces within each induction coil and a comparison of the detected temperature reveals the difference between the variable and fixed axial length induction coils. The axial length of the coils are shortened in the event that the detected temperature is greater than that of the workpiece in the fixed axial length coil, and conversely, lengthened in the event that the detected temperature is less than that of a workpiece in the fixed axial length coil. Altering of the axial length of the induction coil may be accomplished either manually or by a motor-drive arrangement automatically responsive to the comparison of the temperature sensors and comprises moving a first end of the variable axial length induction coil relative to a fixed second end.