High-speed impedance measurement for inline process control of hot-rolled rods
ABSTRACT: For the rod shape measurement of hot rolled round steel bars (rods) the high frequency eddy current method is especially well suited as it requires no contact point and is not limited to bellow the Curie Temperature. Defects of the rod’s shape can be detected by measuring the impedance spectrum of the RLC-oscillator. In the first laboratory setup ( Weidenmüller, Knopf, Sehestedt, and Himmel 2008) an Agilent Impedance Analyser was used for initial tests. Nevertheless, this setup cannot be applied in a steel plant due to the difficult environmental conditions and low data acquisition rate. Hence, a Vector Network Analyser for passive impedance measurement that is applicable in these surroundings was developed, (Weidenmüller, Sehestedt, Kanoun, and Himmel 2009).