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1. 发明专利

JPH1183808A LEAKAGE FLUX FLAW DETECTING METHOD 失效
公开(公告)号：JPH1183808A
公开(公告)日：1999-03-26
申请号：JP24558897
申请日：1997-09-10
申请人： NIPPON KOKAN KK
发明人： KATOU HIROHARU , YOTSUTSUJI JUNICHI
IPC分类号： G01N27/83
摘要： PROBLEM TO BE SOLVED: To enhance defect detecting precision by discriminating whether a flux detected with a magnetic sensor is a leakage flux caused by a defect or a noise magnetic field caused by a noise flux. SOLUTION: When a variation ΔP of a peak value P1 (P2 ) of a detected signal a1 (a2 ) of a magnetic sensor 8a (8b) in the case where the magnetic sensor 8a (8b) is arranged facing to a surface of a ferromagnetic metal specimen 2 in the condition that a magnetic field is applied to the specimen 2 in a moving condition, and where a lift-off L1 (L2 ) of the magnetic sensor from the surface of the specimen 2 is changed is larger than a preset critical value ΔPM, each flux detected by the magnetic sensor 8a (8b) is determined as a leakage flux caused by a defect 6 existing in the surface or inside of the ferromagnetic metal specimen 2 to evaluate the defect 6 based on the leakage flux. On the other hand, when the variation ΔP is the critical value ΔPM or less, each flux detected by the magnetic sensor 8a (8b) is determined as a noise flux.

2. 发明专利

JP2000275219A LEAKAGE FLUX FLAW DETECTING METHOD 失效
公开(公告)号：JP2000275219A
公开(公告)日：2000-10-06
申请号：JP7733299
申请日：1999-03-23
申请人： NIPPON KOKAN KK
发明人： KATO HIROHARU , YOTSUTSUJI JUNICHI , NAGAMUNE AKIO
IPC分类号： G01N27/83
摘要： PROBLEM TO BE SOLVED: To provide a leakage flux flaw detecting method for a ferromagnetic metal specimen capable of detecting a fine flaw with high detection precision. SOLUTION: A magnetic flaw detecting device 4 is installed along a conveyance path of a steel sheet 1. This magnetic flaw detecting device 4 is mainly constituted of magnetizers 5a, 5b, magnetic sensors 6a, 6b and a signal processor 8. The magnetizers 5a, 5b are excited by an AC power supply 7a(frequency f1) and an AC power supply 7b(frequency f2) respectively, where f1

3. 发明专利

JPH09274017A METHOD AND APPARATUS FOR DETECTING FLAW OF METAL ELEMENT 失效
公开(公告)号：JPH09274017A
公开(公告)日：1997-10-21
申请号：JP8350896
申请日：1996-04-05
申请人： NIPPON KOKAN KK
发明人： KATOU HIROHARU , YOTSUTSUJI JUNICHI , NAGAMUNE AKIO
IPC分类号： G01N27/90
摘要： PROBLEM TO BE SOLVED: To detect a minute flaw incapable of being sufficiently detected by a conventional eddy current flaw detection method. SOLUTION: Two eddy current sensors 12a, 12b are provided so as to hold a steel panel 11 therebetween and excited by exciting AC power supplies 20a, 20b. The detection signals from the eddy current sensors are detected in phase by phase detectors 15a, 16b and become eddy current flaw detection signals through band-pass filters 17a, 17b. Two eddy current flaw detection signals are multiplied by a multiplier 18 to be improved in an S/N ratio. A judging circuit 19 judges the presence and grade of a flaw on the basis of the signals improved in the S/N ratio.

4. 发明专利

JPH0989843A METHOD AND APPARATUS FOR EDDY CURRENT FLAW DETECTION 失效
公开(公告)号：JPH0989843A
公开(公告)日：1997-04-04
申请号：JP24622995
申请日：1995-09-25
申请人： NIPPON KOKAN KK
发明人： YOTSUTSUJI JUNICHI , KATOU HIROHARU , NAGAMUNE AKIO
IPC分类号： G01N27/90
摘要： PROBLEM TO BE SOLVED: To provide method and apparatus for eddy current flaw detection in which a flaw extending in same direction as the arranging direction of secondary coil can be detected as well as a single flaw or a flaw extending perpendicularly to the arranging direction of secondary coil while being discriminated. SOLUTION: A plurality of E type eddy current flaw sensors 11-13 are arranged perpendicularly to the arranging direction of poles. The difference signal of outputs from two secondary coils 11b and 11c, 12b and 12c, 13b and 13c in each eddy current flaw sensor and the difference signal of outputs from two secondary coils 11c and 12c, 12c and 13c in different eddy current flaw sensor are detected and the flaw of a material to be inspected is detected based on these difference signals.

5. 发明专利

JP2001296277A MAGNETIC FLAW DETECTION METHOD 失效
公开(公告)号：JP2001296277A
公开(公告)日：2001-10-26
申请号：JP2000111614
申请日：2000-04-13
申请人： NIPPON KOKAN KK
发明人： YOTSUTSUJI JUNICHI , KATO HIROHARU , NAGAMUNE AKIO
IPC分类号： G01N27/83
摘要： PROBLEM TO BE SOLVED: To provide a magnetic flaw detection method, capable of satisfactorily detecting a flaw with S/N ratio, even if an electrical noise is generated or when something other than the defect exerting an influence on a leakage flux exists. SOLUTION: A signal of a magnetic sensor 5a is expressed as V(a), and a signal of a magnetic sensor 5b is expressed as V(b), and respective data are accumulated as much as the moving distance of a thin steel plate 1, corresponding to 1 m×1 m portion. Then, RMSs of the signals in the range are obtained and expressed as Ra, Rb respectively. As Ra and Rb are RMSs of the signals in a wide range, they are supposed to show the mean value of the surface roughness of the thin steel plate 1. Therefore, the signals of the surface roughness cancellation are realized by normalizing the signals of V(a) and V(b) by Ra and Rb and subtracting each other. Namely, V(t) is obtained in each channel by the equation V(t)=Va(t)-V(b)*Ra/Rb, and the range where V(t) exceeds a prescribed threshold is extracted, to thereby extract a defect expectation region D. Then, the defect is determined, based on the width and the length of the defect expectation region D.

6. 发明专利

JP2000227419A LEAKAGE FLUX INSPECTION 失效
公开(公告)号：JP2000227419A
公开(公告)日：2000-08-15
申请号：JP2997799
申请日：1999-02-08
申请人： NIPPON KOKAN KK
发明人： KATO HIROHARU , NAGAMUNE AKIO , YOTSUTSUJI JUNICHI
IPC分类号： G01N27/83
摘要： PROBLEM TO BE SOLVED: To allow defect detection with a high S/N ratio without using plural magnetizers, and without adding a complicated function. SOLUTION: A magnetic inspection equipment 4 is composed of a magnetizer 5 for impressing a magnetic field to a running steel plate 1, magnetic sensors 6a, 6b arranged in a position opposed to the magnetizer 5 to sandwich the steel plate 1, and a signal processor 7 for detecting a defect 8 in the inside or surface of the steel plate 1 based on detection signals from the sensors 6a, 6b. The magnetic sensor 6a is provided in a center position of the magnetizer 5, and detects a leak magnetic flux under a strongly magnetized condition. The magnetic sensor 6b is provided in a position apart from the center position of the magnetizer 5, and detects a leak magnetic flux under a weakly magnetized condition. A noise component contained in two signals in common from the sensors 6a, 6b is cancelled by operating the both signals, so as to realize defect detection excellent is an S/N ratio.

7. 发明专利

JP2000227418A LEAKAGE FLUX INSPECTION 失效
公开(公告)号：JP2000227418A
公开(公告)日：2000-08-15
申请号：JP2978299
申请日：1999-02-08
申请人： NIPPON KOKAN KK
发明人： KATO HIROHARU , YOTSUTSUJI JUNICHI , NAGAMUNE AKIO
IPC分类号： G01N27/83
摘要： PROBLEM TO BE SOLVED: To provide a leakage flux inspecting method for a ferromagnetic metal specimen capable of detecting even a micro defect, with high detection precision. SOLUTION: A magnetic inspection equipment 4 is provided along a conveying passage for a steel plate 1. The equipment 4 is composed mainly of magnetizers 5a, 5b, magnetic sensors 6a, 6b, and a signal processor 7. The sensor 6a measures a leak magnetic flux from the steel plate 1 in a condition magnetized by the magnetizer 5a. The sensor 6b measures a leak magnetic flux from the steel plate 1 in a condition magnetized by the magnetizer 5b. The signal processor 7 operates fellow magnetic signals in the same position of the steel plate 1 detected by the sensors 6a, 6b, so as to reduce noise magnetic fluxes. A defect signal is thereby intensified reletively to enhance an S/N ratio.

8. 发明专利

JP2001296278A METAL BODY INSPECTION DEVICE 失效
公开(公告)号：JP2001296278A
公开(公告)日：2001-10-26
申请号：JP2000111615
申请日：2000-04-13
申请人： NIPPON KOKAN KK
发明人： YOTSUTSUJI JUNICHI , KATO HIROHARU , NAGAMUNE AKIO
IPC分类号： G01N27/83
摘要： PROBLEM TO BE SOLVED: To provide a metal body inspection device, capable of executing stable inspection by keeping a sensor holder at an equal distance and in parallel with a metal test body. SOLUTION: A sensor head 1 follows vertically by a vertical sliding mechanism 8, relative to vertical fluctuation of a steel plate 4. When the steel plate 4 waves in the longitudinal direction, longitudinal direction tracing mechanisms 9a, 9b are rotated around the fulcrum and copy the inclination. When the steel plate 4 waves in the width direction, width direction tracing mechanisms 10a, 10b are rotated about the fulcrum and trace the inclination. The inside of the sensor head 1 has a structure, capable of passing the air. The air is supplied from air supply ports 2a, 2b, passed through the inside of the sensor head 1, jetted out from air exhaust nozzle 3a, 3b toward the steel plate 4, and floats the sensor head 1 by the reaction force.

9. 发明专利

JP2001004596A MAGNETIC LEAKAGE FLUX TESTING METHOD 失效
公开(公告)号：JP2001004596A
公开(公告)日：2001-01-12
申请号：JP17933299
申请日：1999-06-25
申请人： NIPPON KOKAN KK
发明人： YOTSUTSUJI JUNICHI , KATO HIROHARU , NAGAMUNE AKIO
IPC分类号： G01N27/83
摘要： PROBLEM TO BE SOLVED: To realize a magnetic leakage flux testing method capable of reducing a noise signal following to it even in the case of changing a distance between a magnetic sensor and a ferromagnetic element. SOLUTION: A flaw is detected at a magnetizing level different from that of a magnetizer 4a, a magnetic sensor 5a at a thin steel sheet 1 by the magnetizer 4a, the sensor 5a. Outputs of the sensors 5a, 5b are input to a signal processor 6, the processor 6 processes them. The processor 6 obtains a representative value A of a range of the signal outputs from the sensor 5a by a representative value calculator 7a, and obtains a representative value B of the same range as that of the certain range of the output from the sensor 4b by a representative value calculator 7b. A ratio k=A/B of them is obtained by a calculator 8. A flaw detection result calculator 10 calculates an output of the sensor 4a)-k×(an output of the sensor 4b) from the signals from the same positions on the sheet 1 by a flaw detection result calculator 11 by using the ratio, thereby reducing a noise signal to relatively enhance a fault.

10. 发明专利

JPH09274018A METHOD AND APPARATUS FOR DETECTING FLAW OF MAGNETIC METAL ELEMENT 失效
公开(公告)号：JPH09274018A
公开(公告)日：1997-10-21
申请号：JP8350696
申请日：1996-04-05
申请人： NIPPON KOKAN KK
发明人： YOTSUTSUJI JUNICHI , KATOU HIROHARU , NAGAMUNE AKIO
IPC分类号： G01N27/83 , G01N27/90
摘要： PROBLEM TO BE SOLVED: To detect a minute flaw by performing the operation of an eddy current flaw detection signal and a leakage flux flaw detection signal. SOLUTION: A leakage flux signal and an eddy current signal are detected by the center coil 12e of an E-type sensor 12. An eddy current flaw detection signal can be obtained by passing the output of the coil 12e through a phase detector 15 and a band-pass filter 16. Further, a leakage flux flaw detection signal can be obtained by passing the output of the coil 12e through a proper band-pass filter 17. The outputs of the band-pass filters 16, 17 are multiplied by a multiplier 18 and a judging circuit 19 judges the presence and degree of a flaw corresponding to the magnitude of the. output of the multiplier 18. Since flaw signal components are relatively intensified as compared with a noise component by multiplication, even a minute flaw can be detected in a good S/N ratio.

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