WO1984001627A1 - Magnetic testing apparatus - Google Patents

Magnetic testing apparatus Download PDF

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Publication number
WO1984001627A1
WO1984001627A1 PCT/CH1983/000117 CH8300117W WO8401627A1 WO 1984001627 A1 WO1984001627 A1 WO 1984001627A1 CH 8300117 W CH8300117 W CH 8300117W WO 8401627 A1 WO8401627 A1 WO 8401627A1
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WO
WIPO (PCT)
Prior art keywords
magnet
magnetic
pole pieces
disks
sensors
Prior art date
Application number
PCT/CH1983/000117
Other languages
German (de)
French (fr)
Inventor
Marinus Giesselbach
Original Assignee
Gap Ges Auswert Patente
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Gap Ges Auswert Patente filed Critical Gap Ges Auswert Patente
Priority to AU20747/83A priority Critical patent/AU2074783A/en
Publication of WO1984001627A1 publication Critical patent/WO1984001627A1/en
Priority to FI841974A priority patent/FI841974A/en
Priority to DK303084A priority patent/DK303084A/en

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Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/72—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables
    • G01N27/82—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws

Definitions

  • the present invention relates to a magnetic tester for displaying mechanical irregularities on the surface or in the structure of magnetically permeable objects.
  • test device has a permanent magnetic unit and a sensor part.
  • test devices are already known, but they have the disadvantage that there must be a relative speed difference between the test device and the object to be tested.
  • the damaged areas are determined by search or probe coils, whereby it appears to be impossible to check short pieces or carry out tests on the spot without moving the device in the standstill position.
  • the subject matter of the invention is a device which does not have the disadvantages mentioned.
  • the device should be simple and handy and should also be suitable for determining structural errors if there is no speed difference between the object and the device.
  • the device should also be usable if there is any speed difference between the device and the object.
  • the device should be suitable for determining any mechanical faults in any magnetically permeable object.
  • the proposed device is at the beginning described type characterized in that the magnetic unit for generating a relatively strong magnetic field comprises a single or multiple permanent magnet which is enclosed between pole pieces and the sensor part consists of one or more sensors which are arranged in the middle between the two pole pieces and have sensitivity in the axial direction between the poles.
  • the device can expediently have an annular permanent magnet between two disks made of magnetizable material which form the pole shoes, Hall sensors being arranged on the circumference of the magnet and being connected to an amplifier which actuates an acoustic or optical signal transmitter.
  • the ring-shaped magnet can be combined around the two disks by a central screw which has an extension in the form of a rotatable handle.
  • a central screw which has an extension in the form of a rotatable handle.
  • FIG. 1 shows a schematic basic sketch of the device
  • FIG. 2 shows the signal curve
  • Figure 3 shows an axial section through an embodiment of the device
  • FIG. 4 shows a side view of FIG. 3.
  • the test device has a permanent magnet 1 which is U-shaped and has a north pole N and a south pole S.
  • a magnetic field 2 arises between the poles N and S, which is represented by corresponding lines of force.
  • a sensor 3 is arranged between the north and south poles N and S and has a sensitivity only in the axial direction A - A between the poles N and S.
  • the sensor 3 is designed such that it reacts to interruptions in the magnetic field 2.
  • the object to be checked is designated by 4 and has a surface 5.
  • a crack extending from the surface 5 in the structure of the object to be tested is designated by 6.
  • the signal curve 7 shown in FIG. 2 the signals supplied by the sensor 3, shows a strong deflection 8 at the point where the crack 6 is located, which is then perceived acoustically or optically.
  • a Hall probe is suitable as sensor 3, for example is based on the Hall effect.
  • Such a Hall probe consists of small platelets of a semiconductor with high carrier mobility, for example InSb. If a current flows through this plate, a magnetic field-dependent voltage arises perpendicular to this current and perpendicular to the existing magnetic field 2. At the point where the crack or other irregularity is in the material to be tested, the magnetic field changes, causing a change in voltage. This can then be perceived acoustically or optically.
  • FIGS. 3 and 4 show a preferred embodiment of the magnetic test device.
  • the test device has an annular magnet 10, which is enclosed on both sides by a disk 9 made of magnetizable material such as iron.
  • the disks have a ring part which is reinforced with respect to the central part and which form inward-facing, opposing pole pieces 9 'which are magnetized in the direction of the arrow M - S.
  • the magnet 10 is equipped on the circumference with sensors 11 which come to lie between the pole pieces. Both disks 9 and the magnet 10 are combined by a central screw 12, which has a coaxial rotating extension in the form of a handle 13.
  • the magnetic flux is conducted through the pole pieces 9 'of the disks 9 to the surface 14 of the object 15 to be examined.
  • the output of each of the sensors 11 is fed to a sum amplifier (not shown) which adds and amplifies the signals.
  • the resulting signal can be read on a display device or perceived by an audio signal.
  • the device described is suitable for detecting defects in any magnetically permeable metal structure.
  • the structural errors are also determined if there is no speed difference between the object and the device, i.e. if the device is kept motionless over the damaged area.
  • pole pieces When examining elongated objects such as wire structure or the like, it is not necessary to arrange the pole pieces in the longitudinal direction along the object at a distance from one another and to form them in a tubular shape such that they encompass the elongate object on all sides.
  • the device is light and handy and can be used wherever the conventional, heavy and complicated test devices cannot be used.
  • the sensors only react to the relatively narrow magnetic field, which is caused by mechanical errors in the material to be tested.
  • the device is suitable for checking a wide variety of surfaces.
  • the signal generated by the sensors can be treated like a conventional electrical signal and perceived as a buzzer or as a visual display.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)

Abstract

The magnetic testing apparatus has a magnet (10) enclosed between two disks (9). The magnetizable disks (9) form polar parts (9') between which are arranged sensors (11) in the area of the magnet (10). These have a sensitivity in the axial direction between the poles and the polar parts. The signals emitted by the sensors are provided through an amplifier to an optical or acoustical signal emitter.

Description

Magnetisches Prüfgerät Magnetic tester
Die vorliegende Erfindung bezieht sich auf ein magnetisches Prüfgerät zum Anzeigen von mechanischen Unregel mässigkeiten an der Oberfläche oder in der Struktur von magnetisch permeablen Gegenständen.The present invention relates to a magnetic tester for displaying mechanical irregularities on the surface or in the structure of magnetically permeable objects.
Das Prüfgerät weist eine permanent magnetische Einheit und einen Sensorteil auf. Solche Prüfgeräte sind bereits bekannt, die aber den Nachteil aufweisen, dass zwischen dem Prüfgerät und dem zu prüfenden Objekt eine relative Geschwindigkeitsdifferenz vorhanden sein muss. Die schadhaften Stellen werden durch Such-oder Sondenspulen ermittelt, wobei es als unmöglich erscheint, kurze Stücke zu prüfen oder Prüfungen an Ort und Stelle ohne Bewegung des Gerätes in der Stillhaltestellung durchzuführen.The test device has a permanent magnetic unit and a sensor part. Such test devices are already known, but they have the disadvantage that there must be a relative speed difference between the test device and the object to be tested. The damaged areas are determined by search or probe coils, whereby it appears to be impossible to check short pieces or carry out tests on the spot without moving the device in the standstill position.
Den Gegenstand der Erfindung bildet ein Gerät, welches die erwähnten Nachteile nicht aufweist. Insbesondere soll das Gerät einfach und handlich sein und sich zur Ermittlung von Strukturfehlern auch dann eignen, wenn zwischen dem Objekt und dem Gerät keine Geschwindigkeitsdifferenz besteht. Das Gerät soll aber auch dann brauchbar sein, wenn irgendwelche Geschwindigkeitsdifferenz zwischen dem Gerät und Objekt vorhanden ist. Ferner soll sich das Gerät zur Bestimmung von jeglichen mechanischen Fehlern in jedem magnetisch permeablen Objekt eignen.The subject matter of the invention is a device which does not have the disadvantages mentioned. In particular, the device should be simple and handy and should also be suitable for determining structural errors if there is no speed difference between the object and the device. However, the device should also be usable if there is any speed difference between the device and the object. Furthermore, the device should be suitable for determining any mechanical faults in any magnetically permeable object.
Erfindungsgemäss ist das vorgeschlagene Gerät eingangs beschriebener Art dadurch gekennzeichnet, dass die magnetische Einheit, zur Erzeugung eines relativ starken magnetischen Feldes, einen einfachen oder mehrfachen Permanentmagneten umfasst, welcher zwischen Polstücken eingeschlossen ist und der Sensorteil aus einem oder mehreren Sensoren besteht, welche in der Mitte zwischen den beiden Polschuhen angeordnet sind und eine Empfindlichkeit in der Axialrichtung zwischen den Polen aufweisen. Zweckmässigerweise kann das Gerät einen ringförmigen Permanentmagneten zwischen zwei Scheiben aus magnetisierbarem Material aufweisen, welche die Polschuhe bilden, wobei am Umfang des Magneten Hall-Sensoren angeordnet sind, die mit einem Verstärker in Verbindung stehen, der einen akustischen oder optischen Signalgeber betätigt.According to the invention, the proposed device is at the beginning described type characterized in that the magnetic unit for generating a relatively strong magnetic field comprises a single or multiple permanent magnet which is enclosed between pole pieces and the sensor part consists of one or more sensors which are arranged in the middle between the two pole pieces and have sensitivity in the axial direction between the poles. The device can expediently have an annular permanent magnet between two disks made of magnetizable material which form the pole shoes, Hall sensors being arranged on the circumference of the magnet and being connected to an amplifier which actuates an acoustic or optical signal transmitter.
Ein solches Gerät ist klein in der Form und leicht im Gewicht und kann überall eingesetzt werden, wo die konventionellen schweren und komplizierten Testanordnungen nicht gebraucht werden können. Bei einer zweckmässigen Ausführung kann der ringförmige Magnet um die beiden Scheiben durch eine zentrale Schraube zusammengefasst sein, welche eine Verlängerung in der Form eines drehbaren Handgriffes besitzt. Mit so einem Handgerät können die verschiedensten Oberflächen leicht und einfach geprüft werden, wobei die Sensoren sofort reagieren, wenn eine fehlerhafte Stelle im zu prüfenden Objekt zwischen die Polstücke gelangt. Die vorzugsweise verwendeten Hall-Sensoren geben ein Signal, mit welchem ein elektronischer Signalverstärker und ein Ablesegerät gespiesen wird.Such a device is small in shape and light in weight and can be used wherever the conventional, heavy and complicated test arrangements cannot be used. In an expedient embodiment, the ring-shaped magnet can be combined around the two disks by a central screw which has an extension in the form of a rotatable handle. With such a hand-held device, the most varied of surfaces can be checked easily and simply, with the sensors reacting immediately if a faulty point in the object to be checked gets between the pole pieces. The Hall sensors which are preferably used give a signal with which an electronic signal amplifier and a reading device are fed.
Auf beiliegender Zeichnung ist ein Ausführungsbeispiel des Erfindungsgegenstandes dargestellt und zwar zeigen Figur 1 eine schematische Prinzipskizze des Gerätes,On the accompanying drawing an embodiment of the subject of the invention is shown and show FIG. 1 shows a schematic basic sketch of the device,
Figur 2 die Darstellung des Signalverlaufes,FIG. 2 shows the signal curve,
Figur 3 einen Axialschnitt durch eine Ausführung des Gerätes undFigure 3 shows an axial section through an embodiment of the device and
Figur 4 eine Seitenansicht zur Figur 3.FIG. 4 shows a side view of FIG. 3.
In der Figur 1 ist der grundsätzliche Aufbau eines magnetischen Prüfgerätes wie vorgeschlagen dargestellt. Das Prüfgerät weist einen Permanentmagneten 1, welcher ü-förmig ausgebildet ist und einen Nordpol N sowie einen Südpol S besitzt. Zwischen den Polen N und S entsteht ein magnetisches Feld 2, welches durch entsprechende Kraftlinien dargestellt ist. Zwischen dem Nord- und Südpol N und S ist ein Sensor 3 angeordnet, welcher eine Empfindlichkeit nur in der Achsrichtung A - A zwischen den Polen N und S besitzt. Der Sensor 3 ist so ausgebildet, dass er auf Unterbrechungen im magnetischen Feld 2 reagiert. Mit 4 ist das zu prüfende Objekt bezeichnet, welches eine Oberfläche 5 besitzt. Ein sich von der Oberfläche 5 aus erstreckender Riss in der Struktur des zu prüfenden Objektes ist mit 6 bezeichnet. An dieser Stelle wird auch das magnetische Feld 2 unterbrochen. Der in der Figur 2 dargestellte Signalverlauf 7, der vom Sensor 3 gelieferten Signale, zeigt an der Stelle, wo sich der Riss 6 befindet, einen starken Ausschlag 8, welcher dann akustisch oder optisch wahrgenommen wird.1 shows the basic structure of a magnetic test device as proposed. The test device has a permanent magnet 1 which is U-shaped and has a north pole N and a south pole S. A magnetic field 2 arises between the poles N and S, which is represented by corresponding lines of force. A sensor 3 is arranged between the north and south poles N and S and has a sensitivity only in the axial direction A - A between the poles N and S. The sensor 3 is designed such that it reacts to interruptions in the magnetic field 2. The object to be checked is designated by 4 and has a surface 5. A crack extending from the surface 5 in the structure of the object to be tested is designated by 6. At this point the magnetic field 2 is also interrupted. The signal curve 7 shown in FIG. 2, the signals supplied by the sensor 3, shows a strong deflection 8 at the point where the crack 6 is located, which is then perceived acoustically or optically.
Als Sensor 3 eignet sich z.B. eine Hall-Sonde, welcher der Halleffekt zugrunde liegt. Eine solche Hall-Sonde besteht aus kleinen Plättchen eines Halbleiters hoher Trägerbeweglichkeit z.B. InSb. Wenn ein Strom durch dieses Plättchen fliesst, entsteht senkrecht zu diesem Strom und senkrecht zum vorhandenen Magnetfeld 2 eine magnetfeldabhängige Spannung. An der Stelle, wo sich der Riss oder eine andere Unregelmässigkeit im zu prüfenden Material befindet, ändert sich das Magnetfeld, wodurch eine Spannungsänderung stattfindet. Dies kann dann akustisch oder optisch wahrgenommen werden.A Hall probe is suitable as sensor 3, for example is based on the Hall effect. Such a Hall probe consists of small platelets of a semiconductor with high carrier mobility, for example InSb. If a current flows through this plate, a magnetic field-dependent voltage arises perpendicular to this current and perpendicular to the existing magnetic field 2. At the point where the crack or other irregularity is in the material to be tested, the magnetic field changes, causing a change in voltage. This can then be perceived acoustically or optically.
In den Figuren 3 und 4 ist eine bevorzugte Ausführungsform des magnetischen Prüfgerätes dargestellt. Das Prüfgerät weist einen kreisringförmigen Magneten 10 auf, weleher von beiden Seiten von je einer Scheibe 9 aus magnetisierbarem Material wie Eisen umfasst wird. Die Scheiben weisen einen gegenüber dem Mittelteil verstärkten Ringteil auf, welche einwärtsgerichtete einander gegenüberliegende Polstücke 9' bilden, die in der Pfeilrichtung M - S magnetisiert sind.FIGS. 3 and 4 show a preferred embodiment of the magnetic test device. The test device has an annular magnet 10, which is enclosed on both sides by a disk 9 made of magnetizable material such as iron. The disks have a ring part which is reinforced with respect to the central part and which form inward-facing, opposing pole pieces 9 'which are magnetized in the direction of the arrow M - S.
Der Magnet 10 ist am Umfang mit Sensoren 11 bestückt, die zwischen den Polschuhen zu liegen kommen. Beide Scheiben 9 und der Magnet 10 werden durch eine zentrale Schraube 12 zusammengefasst, welche eine gleichachsige drehbare Verlängerung in der Form eines Handgriffes 13 besitzt.The magnet 10 is equipped on the circumference with sensors 11 which come to lie between the pole pieces. Both disks 9 and the magnet 10 are combined by a central screw 12, which has a coaxial rotating extension in the form of a handle 13.
Durch die Polstücke 9' der Scheiben 9 wird der magnetische Fluss an die Oberfläche 14 des zu untersuchenden Objektes 15 geleitet. Der Ausgang jeder der Sensoren 11 wird einem (nicht gezeigten) Summenverstärker zugeführt, welcher die Signale addiert und verstärkt. Das resultierende Signal kann an einem Anzeigegerät abgelesen oder durch ein Audiosignal wahrgenommen werden.The magnetic flux is conducted through the pole pieces 9 'of the disks 9 to the surface 14 of the object 15 to be examined. The output of each of the sensors 11 is fed to a sum amplifier (not shown) which adds and amplifies the signals. The resulting signal can be read on a display device or perceived by an audio signal.
Das beschriebene Gerät ist geeignet Fehler in jeder magnetisch permeablen Metallstruktur zu entdecken. Die Strukturfehler werden auch dann ermittelt, wenn zwischen dem Objekt und dem Gerät keine Geschwindigkeitsdifferenz besteht, d.h. wenn das Gerät über der schadhaften Stelle bewegungslos gehalten wird.The device described is suitable for detecting defects in any magnetically permeable metal structure. The structural errors are also determined if there is no speed difference between the object and the device, i.e. if the device is kept motionless over the damaged area.
Bei der Untersuchung von länglichen Objekten wie Drahtstruktur oder dergleichen ist es nicht notwendig, die Polstücke in Längsrichtung entlang des Objektes in Abstand voneinander anzuordnen und sie so röhrenförmig auszubilden, dass sie das längliche Objekt allseitig umfassen.When examining elongated objects such as wire structure or the like, it is not necessary to arrange the pole pieces in the longitudinal direction along the object at a distance from one another and to form them in a tubular shape such that they encompass the elongate object on all sides.
Das Gerät ist leicht und handlich und kann überall eingesetzt werden, wo die konventionellen schweren und komplizierten Prüfgeräte nicht eingesetzt werden können.The device is light and handy and can be used wherever the conventional, heavy and complicated test devices cannot be used.
Die Sensoren reagieren nur auf das relativ schmale magnetische Feld, welches durch mechanische Fehler im zu prüfenden Material entstehen. Das Gerät ist geeignet die verschiedensten Oberflächen zu überprüfen. Das durch die Sensoren erzeugte Signal kann wie ein konventionelles elektrisches Signal behandelt und als Summton oder als optische Anzeige wahrgenommen werden. The sensors only react to the relatively narrow magnetic field, which is caused by mechanical errors in the material to be tested. The device is suitable for checking a wide variety of surfaces. The signal generated by the sensors can be treated like a conventional electrical signal and perceived as a buzzer or as a visual display.

Claims

Patentansprüche Claims
1. Magnetisches Prüfgerät zum Anzeigen von mechanischen Unregelmässigkeiten an der Oberfläche oder in der Struktur von magnetisch permeablen Gegenständen, welches aus einer permanent magnetischen Einheit und aus einem Sensorteil besteht, dadurch gekennzeichnet, dass die magnetische Einheit, zur Erzeugung eines relativ starken magnetischen Feldes, einen einfachen oder mehrfachen Permanentmagneten (1, 10) umfasst, welcher zwischen Polschuhen (9') eingeschlossen ist und der Sensorteil aus einem oder mehreren Sensoren (11) besteht, welche in der Mitte zwischen den beiden Polschuhen (9') angeordnet sind und eine Empfindlichkeit in der Axialrichtung zwischen den Polen aufweisen.1. Magnetic test device for displaying mechanical irregularities on the surface or in the structure of magnetically permeable objects, which consists of a permanent magnetic unit and a sensor part, characterized in that the magnetic unit for generating a relatively strong magnetic field, a Single or multiple permanent magnet (1, 10), which is enclosed between pole pieces (9 ') and the sensor part consists of one or more sensors (11) which are arranged in the middle between the two pole pieces (9') and a sensitivity have in the axial direction between the poles.
2. Magnetisches Prüfgerät nach Anspruch 1, dadurch gekennzeichnet, dass dasselbe einen ringförmigen Permanentmagneten (10) zwischen zwei Scheiben (9) aus magnetisierbarem Material aufweist, welche die Polschuhe bilden, wobei am Umfang des Magneten (10) Hall-Sensoren (11) angeordnet sind, die mit einem Verstärker in Verbindung stehen, der einen akustischen oder optischen Signalgeber betätigt.2. Magnetic test device according to claim 1, characterized in that the same has an annular permanent magnet (10) between two disks (9) made of magnetizable material, which form the pole pieces, Hall sensors (11) being arranged on the circumference of the magnet (10) are in connection with an amplifier that actuates an acoustic or optical signal transmitter.
3. Magnetisches Prüfgerät nach Ansprüchen 1 und 2, dadurch gekennzeichnet, dass der Magnet (10) und die beiden Scheiben (9) durch eine zentrale Schraube (12) zu sammengefasst sind, welche eine Verlängerung in der Form eines drehbaren Handgriffes (13) besitzt. 3. Magnetic test device according to claims 1 and 2, characterized in that the magnet (10) and the two disks (9) by a central screw (12) are summarized, which has an extension in the form of a rotatable handle (13).
PCT/CH1983/000117 1982-10-22 1983-10-20 Magnetic testing apparatus WO1984001627A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
AU20747/83A AU2074783A (en) 1982-10-22 1983-10-20 Magnetic testing apparatus
FI841974A FI841974A (en) 1982-10-22 1984-05-16 MAGNETIC TESTING MEASUREMENT.
DK303084A DK303084A (en) 1982-10-22 1984-06-21 MAGNETIC TESTING DEVICE

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CH615782 1982-10-22

Publications (1)

Publication Number Publication Date
WO1984001627A1 true WO1984001627A1 (en) 1984-04-26

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Application Number Title Priority Date Filing Date
PCT/CH1983/000117 WO1984001627A1 (en) 1982-10-22 1983-10-20 Magnetic testing apparatus

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Country Link
EP (1) EP0122271A1 (en)
JP (1) JPS59501919A (en)
DK (1) DK303084A (en)
FI (1) FI841974A (en)
NO (1) NO842505L (en)
WO (1) WO1984001627A1 (en)
ZA (1) ZA837891B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3614174A1 (en) * 1986-04-22 1987-10-29 Bruss Polt I MAGNETIZING ARRANGEMENT FOR MAGNETOGRAPHIC TEST
US7990138B2 (en) * 2007-03-20 2011-08-02 Vincent Bongiraud, legal representative Probe for analysis of a string of rods or tubes in a well
US8207730B2 (en) 2006-04-21 2012-06-26 Halliburton Energy Services, Inc. Method and device for determining the existence and location of stress-inducing forces on a rod

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3609530A (en) * 1968-03-13 1971-09-28 Atomic Energy Authority Uk Magnetic leakage field flaw detector with compensation for variation in spacing between magnetizer and test piece
DE1798137A1 (en) * 1968-08-29 1971-11-18 Kaulfersch Helmut Dipl Ing Dr Measuring device for the display of cracks or the like in workpieces made of ferromagnetic material
US3710236A (en) * 1970-11-30 1973-01-09 Youngstown Sheet And Tube Co Magnetic leakage field flaw detector utilizing partially overlapping hall probes
US3899734A (en) * 1973-05-14 1975-08-12 Vetco Offshore Ind Inc Magnetic flux leakage inspection method and apparatus including magnetic diodes
DE2906436A1 (en) * 1979-02-20 1980-08-28 Foerster Inst Dr Friedrich Ferromagnetic material surface examination test method - using induction coil in parallel with surface of test piece and chain of intermediate spacing pieces on roller belt unit

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3609530A (en) * 1968-03-13 1971-09-28 Atomic Energy Authority Uk Magnetic leakage field flaw detector with compensation for variation in spacing between magnetizer and test piece
DE1798137A1 (en) * 1968-08-29 1971-11-18 Kaulfersch Helmut Dipl Ing Dr Measuring device for the display of cracks or the like in workpieces made of ferromagnetic material
US3710236A (en) * 1970-11-30 1973-01-09 Youngstown Sheet And Tube Co Magnetic leakage field flaw detector utilizing partially overlapping hall probes
US3899734A (en) * 1973-05-14 1975-08-12 Vetco Offshore Ind Inc Magnetic flux leakage inspection method and apparatus including magnetic diodes
DE2906436A1 (en) * 1979-02-20 1980-08-28 Foerster Inst Dr Friedrich Ferromagnetic material surface examination test method - using induction coil in parallel with surface of test piece and chain of intermediate spacing pieces on roller belt unit

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3614174A1 (en) * 1986-04-22 1987-10-29 Bruss Polt I MAGNETIZING ARRANGEMENT FOR MAGNETOGRAPHIC TEST
US8207730B2 (en) 2006-04-21 2012-06-26 Halliburton Energy Services, Inc. Method and device for determining the existence and location of stress-inducing forces on a rod
US8933693B2 (en) 2006-04-21 2015-01-13 Jean-Pierre Martin Method and device for determining the existence and location of stress-inducing forces on a rod
US7990138B2 (en) * 2007-03-20 2011-08-02 Vincent Bongiraud, legal representative Probe for analysis of a string of rods or tubes in a well
US8471556B2 (en) 2007-03-20 2013-06-25 Jean-Pierre Martin Magnetic probe and processes of analysis

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Publication number Publication date
ZA837891B (en) 1984-06-27
DK303084D0 (en) 1984-06-21
EP0122271A1 (en) 1984-10-24
FI841974A0 (en) 1984-05-16
FI841974A (en) 1984-05-16
JPS59501919A (en) 1984-11-15
NO842505L (en) 1984-06-21
DK303084A (en) 1984-06-21

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