Electricity: measuring and testing – Magnetic – With means to create magnetic field to test material
Patent
1991-10-17
1993-08-10
Strecker, Gerard R.
Electricity: measuring and testing
Magnetic
With means to create magnetic field to test material
324242, 324255, 324261, 324262, G01N 2783, G01R 3304, G01R 3312
Patent
active
052352757
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a magnetic inspection apparatus for a thin steel strip which detects a defect present in the interior or on the surface of a thin steel strip in a traveling state and, more particularly, to a magnetic inspection apparatus for a thin steel strip which urges a hollow roller, rotatably supported on a stationary shaft perpendicular to a travel path of the thin steel strip, against the steel strip. The magnetic inspection apparatus houses a magnetizer in the hollow roller, and detects by a magnetic sensor magnetic flux leakage occurring due to a defect.
BACKGROUND ART
A magnetic inspection apparatus detects a defect, e.g., a flaw or an inclusion, in the interior or on the surface of a thin steel strip by utilizing magnetism. A magnetic inspection apparatus for a thin steel strip which can not only examine a thin steel strip as an object to be examined in a still state but which also can continuously detect defects present in a thin steel strip traveling along, e.g., a manufacture, line of a factory and the like, has been disclosed in Published Unexamined Japanese Utility Model Application No. 63-107849.
FIGS. 31 and 32 are sectional views taken along different directions, respectively, of an above-described magnetic inspection apparatus for a thin steel strip which continuously detects defects of a traveling thin steel strip.
A hollow roller 1 is made of a non-magnetic material. One end of a stationary shaft 2 extends along the axis of the hollow roller 1. The other end of the stationary shaft 2 is fixed on the frame of a base (not shown). The stationary shaft 2 is supported on the inner circumferential surfaces of the two ends of the hollow roller 1 by a pair of rolling bearings 3a and 3b so that it is located along the axis of the hollow roller 1. Hence, the hollow roller 1 freely rotates about the stationary shaft 2 as the central axis of rotation.
Inside the hollow roller 1, a magnetization core 4c having a substantially U-shaped section is fixed on the stationary shaft 2 through a support member 5 such that the magnetization core 4c's magnetic poles 4a and 4b, which constitute a magnetic path, are close to the inner circumferential surface of the hollow roller 1. A magnetization coil 6 is wound around the magnetization core 4c. Hence, the magnetization core 4c with the magnetic poles 4a and 4b, and the magnetization coil 6 constitute a magnetizer 4. A plurality of magnetic sensors 7 are arranged between the magnetic poles 4a and 4b of the magnetization core 4c of the magnetizer 4 in the axial direction. Each magnetic sensor 7 is fixed on the stationary shaft 2.
A power cable 8 for supplying an excitation current to the magnetization coil 6 and a signal cable 9 for deriving the respective detection signals output from the respective magnetic sensors 7 extend to the outside through the interior of the stationary shaft 2. Hence, the positions of the magnetization core 4 and the respective magnetic sensors 7 are fixed, and the hollow roller 1 rotates at a small gap to the outer surfaces of the magnetizer 4 and the respective magnetic sensors 7.
When the outer circumferential surface of the hollow roller 1 of the magnetic inspection apparatus having such an arrangement is urged against one surface of a thin steel strip 10, traveling in the direction of an arrow A, at a predetermined pressure, the hollow roller rotates in the direction of an arrow B as the stationary shaft 2 is fixed on the frame of the base.
When an excitation current is supplied to the magnetization coil 6, a closed magnetic path is constituted by the magnetization core 4c and the traveling thin steel strip 10. Therefore, if a defect described above is present in the interior or on the surface of the thin steel strip 10, the magnetic path within the thin steel strip 10 is disturbed, and magnetic flux leakage occurs. The magnetic flux leakage is sensed by a magnetic sensor 7 at a corresponding position and is detected as a defect signal.
The signal level of the detected defect signal correspo
REFERENCES:
patent: 2938164 (1960-05-01), Hansburg
patent: 3662576 (1972-05-01), Girlatschek
patent: 3748575 (1973-07-01), Lapper
patent: 3781662 (1973-12-01), Davis
patent: 3886445 (1975-05-01), Chiba et al.
patent: 4107606 (1978-08-01), Typpo et al.
patent: 4305035 (1981-12-01), Mach et al.
patent: 4518919 (1985-05-01), Ishida
patent: 4519249 (1985-05-01), Hunt
patent: 4767987 (1988-08-01), Montgomery
patent: 5089776 (1992-02-01), Furukawa et al.
Patent Abstracts of Japan, vol. 10, No. 344, Nov. 20, 1986, Nippon Steel Corp., Defect Detecting Device for Strip.
Ando Seigo
Furukawa Takato
Iwanaga Kenichi
Takekoshi Atsuhisa
Takenaka Masaki
NKK Corporation
Strecker Gerard R.
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