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

• Main Authors: MATSUFUJI YASUHIRO, YOTSUTSUJI JUNICHI, SHIBASAKI YUKO
• Format: Patent
• Language: English; Japanese
• Published: 07.06.2018
• Subjects: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIRCHEMICAL OR PHYSICAL PROPERTIES; MEASURING; PHYSICS; TESTING

PROBLEM TO BE SOLVED: To provide a magnetic leakage flux flaw detection device of a thin steel strip and a flaw detection method capable of removing a disturbance noise due to vibrations even in a relatively large scale.SOLUTION: A magnetic leakage flux flaw detection device includes: a differential type magnetic sensor having a bar-shaped magnetic core in which a search coil with the same number of windings is wound around each of a part close to and a part far from a thin steel strip and an U-shaped magnetic core that nips and surrounds a gap on the front and rear surfaces and upside of the bar-shaped magnetic core; an amplifier for amplifying an output connected in series so that the search coil is differentially moved; a band pass filter set to a predetermined pass frequency band; and a signal processing part having an all-wave rectifier for all-wave rectifying a waveform after going through band pass filtering.SELECTED DRAWING: Figure 1 【課題】振動による外乱ノイズが比較的大きい場合であっても、極めて低いレベルまで除去可能な、薄鋼帯の漏洩磁束探傷装置および探傷方法を提供することを目的とする。【解決手段】薄鋼帯に近い方と遠い方のそれぞれに同一巻き数のサーチコイルが巻回された棒状の強磁性体コアと、該棒状の強磁性体コアの前後面及び上方にギャップを挟んで囲うコの字型形状の強磁性体コアとを備えた差分式磁気センサと、前記サーチコイルを差動となるよう直列に接続した出力を増幅する増幅器と、所定の通過周波数帯域に設定されるバンドパスフィルタと、バンドパスフィルタ後の波形を全波整流する全波整流器とを備えた信号処理部と、を具備する。【選択図】図１