CARBURIZING DEPTH MEASURING DEVICE

摘要

PROBLEM TO BE SOLVED: To perform precise measurement by removing permeability and resistivity of a carburizing layer and a measuring error such as lift-off as much as possible in carburizing depth measurement using an eddy current sensor. SOLUTION: Impedance measurement in total six frequencies adding three kinds of high frequencies and three kinds of low frequencies is performed on an object to be measured (S1). Subsequently, the resistivity of a surface layer and the lift-off are calculated on the basis of an impedance measured value in a high frequency area obtained in Step S1 (S2), and the impedance measured value in a low frequency area obtained in Step S1 is corrected on the basis thereof (S3). The direction of a straight line (phase angle) connecting the impedance measured value of 2 kHz-500, and the resistivity factor and permeability factor of a base material are calculated by using the impedance measured value in the low frequency area corrected Step S3 (S5), and carburizing depth is calculated on basis of the resistivity of the surface layer obtained in Step S2, the phase angle and the resistivity factor and permeability factor of the base material layer obtained in Step S4.