Nkk Corporation

Jfe Steel Corporation

Yasuhiro Matsufuji

Hiroshi Maki

Yukinori Iizuka

Seigo Ando

Takahiro Koshihara

Kenichi Iwanaga

Masaki Takenaka

Mamoru Inaba

Atsuhisa Takeoshi

Tatsuya Hashimoto

Takeo Shimizu

An inspection device includes multiple magnetic sensors, wiring for calibration and a controller. The wiring for calibration is arranged at the same relative position with respect to a magnetically sensitive portion of each of the multiple magnetic sensors. The controller obtains a first output value of each of the multiple magnetic sensors in advance. Before a predetermined portion of an electrical steel sheet passes the position of the magnetic sensors, the controller retracts the multiple magnetic sensors. The controller starts applying a current to the wiring for calibration. The controller obtains a second output value of each of the multiple magnetic sensors. After the predetermined position passes, the controller displaces the multiple magnetic sensors to the detection position. The controller corrects a measurement value measured by each of the multiple magnetic sensors based on the first output value and the second output value.

Sensitivity calibration method, inspection device, and magnetic sensor group

A leakage-flux flaw detection device includes a plurality of leakage-flux flaw detectors provided at positions not in contact with a steel strip and arranged in a width direction of the steel strip, wherein the leakage-flux flaw detectors each include a rotating disk that faces a surface subjected to flaw detection of the steel strip and that rotates, and a plurality of defect detection heads installed at different positions in a circumferential direction on the rotating disk, that perform direct-current magnetization of the steel strip, and detect leakage flux leaking from a linear defect due to the direct-current magnetization, wherein at least one of the plurality of defect detection heads has an inclination angle different from inclination angles of other defect detection heads, the inclination angle being defined by a tangent line of a rotation trajectory and the magnetization direction at an installation position of the defect detection head.

Leakage-flux flaw detection device

Method and apparatus for magnetically detecting defects in an object

A magnetic inspection apparatus includes a magnetizer which generates a magnetic field in an object to be inspected, the object running in a predetermined direction, the magnetizer including a pair of magnetic poles provided in facing relation to the object, the pair of magnetic poles being arranged in the predetermined direction; a plurality of magnetic sensors arranged at small intervals in a widthwise direction of the object perpendicular to the predetermined direction, for detecting a leakage magnetic flux due to a defect of the object at locations in the widthwise direction, each magnetic sensor having sides which face the magnetic poles; a plurality of subtraction circuits, each calculating a difference signal between output signals from those ones of the magnetic sensors which are separated by a predetermined distance; a plurality of absolute value circuits, each calculating an absolute value of each difference signal output from each subtraction circuit; and an arithmetic operation circuit which evaluates the defect of the object on the basis of the absolute value signal output from each absolute value circuit, with the relationship between a distance E (unit=mm) between the magnetic sensors associated with the output signals subjected to subtraction in each subtraction circuit and a distance L (unit=mm) between each magnetic sensor and the object being defined by 17&lt;EL&lt;78.

Apparatus for magnetic inspection using magnetic shield, with specific

Apparatus for magnetic inspection using magnetic shield

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Tokyo, Japan

Yasuhiro Matsufuji