LEAKAGE MAGNETIC FLUX METHOD AND LEAKAGE MAGNETIC FLUX DEVICE FOR FLAW DETECTION OF THIN STEEL STRIP

• Main Author: MATSUFUJI YASUHIRO
• Format: Patent
• Language: English; Japanese
• Published: 27.07.2015
• Subjects: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; PHYSICS; TESTING

PROBLEM TO BE SOLVED: To provide a leakage magnetic flux device and a leakage magnetic flux method, for flaw detection of a thin steel strip, which enable online flaw detection with a constant detection sensitivity regardless of lift-off variations due to thin steel strip tension.SOLUTION: A plurality of laser distance meters are arranged in a width direction of a thin steel strip, a distance from a magnetic pole gap of a magnetizer to a nonmagnetic hollow roll inner surface is measured and output correction is performed by fluctuation components in lift off of a magnetic sensor with respect to output after a signal processing, based on: previously measured and stored relative output characteristics for the lift off, of the magnetic sensor; and fluctuation components in lift off of the magnetic sensor when tension is generated during thin steel strip running operation under no tension to the thin steel strip, calculated from the measured distance. 【課題】薄鋼帯張力によるリフトオフ変動にかかわらず同一の検出感度でオンライン探傷ができる、薄鋼帯の漏洩磁束探傷装置および方法を提供することを目的とする。【解決手段】薄鋼帯の幅方向に複数個のレーザ距離計を配置し、磁化器の磁極間隙より非磁性中空ロール内面までの距離を計測し、あらかじめ測定され格納された磁気センサのリフトオフに対する相対出力特性と、計測した前記距離から演算した、薄鋼帯に張力が無いときに対する薄鋼帯走行時に張力が生じたときの磁気センサのリフトオフの変動分に基づいて、前記信号処理後の出力に対して、磁気センサのリフトオフの変動分による出力補正を行う。【選択図】図１