Jfe Steel Corporation

Takahiro Koshihara

Hiroaki Ono

Akihiro Ogawa

Yukinori Iizuka

Toshifumi Kodama

Akio Nagamune

Hiroharu Kato

Kunihiro Senda

Takeshi Omura

Takahiko Oshige

Yasuhiro Matsufuji

Yoshihisa Ichihara

Yoshiyuki Umegaki

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 learned model generation method includes: using a teacher image including a defect map that is an image indicating a distribution of a defect portion of a surface of steel and having an equal image size, and presence/absence of periodic defects assigned in advance to the defect map; and generating a learned model by machine learning, the learned model for which: an input value is a defect map that is an image indicating a distribution of a defect portion of a surface of steel and having an image size of the equal image size; and an output value is a value concerning presence/absence of periodic defects in the defect map.

Learned model generation method, learned model, surface defect inspection method, steel manufacturing method, pass/fail determination method, grade determination method, surface defect determination program, pass/fail determination program, determination system, and steel manufacturing equipment

Disclosed is a grain-oriented electrical steel sheet with extremely low iron loss by means of a magnetic domain refining technique. In a grain-oriented electrical steel sheet having a plurality of magnetic domains refined via a local strain introduction portion, when a direct-current external magnetic field is applied to the steel sheet in a rolling direction, for a magnetic flux leaked from the local strain introduction portion at a position 1.0 mm away from a surface of the steel sheet at a side of the local strain introduction portion, a value obtained by dividing an intensity level of a total leakage magnetic flux by an intensity level of a magnetic flux leaked due to causes other than strain is more than 1.2.

Grain-oriented electrical steel sheet and method of producing same

A surface defect inspection method includes: acquiring an original image by capturing an image of a subject of an inspection; generating texture feature images by applying a filtering process using spatial filters to the original image; generating a feature vector at each position of the original image, by extracting a value at a corresponding position from each of the texture feature images, for each of the positions of the original image; generating an abnormality level image representing an abnormality level for each position of the original image, by calculating, for each of the feature vectors, an abnormality level in a multi-dimensional distribution formed by the feature vectors; and detecting a part having the abnormality level that is higher than a predetermined level in the abnormality level image as a defect portion or a defect candidate portion.

Surface defect inspection method and surface defect inspection apparatus

A detecting method of optically detecting a surface defect of a moving steel material includes an irradiation step of irradiating an examination target part with illumination light beams from different directions by two or more distinguishable light sources whose light emission durations are set based on at least an allowable positional displacement of an image, the two or more distinguishable light sources repeatedly emitting light such that their light emission timings thereof do not overlap each other; and a detection step of obtaining images by reflected light beams of the respective illumination light beams and detecting a surface defect in the examination target part by executing subtraction processing between the obtained images.

Surface defect detecting method and surface defect detecting apparatus

A surface defect detecting method of optically detecting a surface defect of a steel material includes: an irradiation step of irradiating an examination target part with illumination light beams from different directions by using two or more distinguishable light sources; and a detection step of obtaining images by reflected light beams of the respective illumination light beams and detecting a surface defect in the examination target part by executing subtraction processing between the obtained images.

An apparatus for detecting periodic defects includes a sensor that obtains signals to evaluate properties of an area having a length longer than an expected defect period; a small area selector that separates small areas whose area length is shorter than that of the area so that all adjacent distance intervals are equal in a periodic defect arrangement direction, and selecting signals corresponding to the positions of the plurality of small areas from outputs from the sensor; an evaluation index calculator that calculates a similarity evaluation index between signal patterns among signals selected by the small area selector; a set value changer that changes the positions of the small areas and the distance interval, and repeating computational processings of the small area selector and the evaluation index calculator; and a period judgment device that judges the distance interval as a period when the evaluation index is higher than a value.

Apparatus for detecting periodic defect and method therefor

A detection method for detecting a concavo-convex shape surface defect existing on a ferromagnetic metal object including sensing a signal attributed to strain of the concavo-convex shape surface defect having a size in a range of 0.5 to 6 &#x3bc;m. The signal is magnetic flux leaking from the ferromagnetic metal to which magnetic flux is applied. A detecting apparatus incorporates a magnetizer for magnetizing a ferromagnetic metal and a plurality of magnetic sensors arranged in the direction perpendicular to a traveling direction of the ferromagnetic metal to sense a signal attributed to strain of a concavo-convex shape surface defect having a size in a range of 0.5 to 6 &#x3bc;m.

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Tokyo, Japan

Takahiro Koshihara