磁気ひずみ効果型トルクセンサのための鋼軸の特性評価

抄録

Nickel chromium molybdenum steel shafts (SNCM) for a magnetostrictive torque sensor were evaluated for such items as sensitivity, hysteresis and zero-level-fluctuation. Magnetic inhomogeneities of the steel shafts were also evaluated in terms of magnetic anisotropy at the surface of the shaft. It was found that the lowest hysteresis was obtained with a carburized SNCM420 shaft. The linearity measured with this shaft was as good as 0.8%/(full scale) (full scale=1000Nm for a shaft of 25mm in diameter). Zero-level-fluctuations of the torque sensor using SNCM420 carburized shafts were not so large compared with those using as-ground shafts despite of reduction of the sensitivity. This was because a peculiar magnetic anisotropy pattern at the surface of the shaft without heat treatment was erased and uniformed by carburizing.