CA1195385A - Non-destructive testing of ferromagnetic materials - Google Patents
Non-destructive testing of ferromagnetic materialsInfo
- Publication number
- CA1195385A CA1195385A CA000407616A CA407616A CA1195385A CA 1195385 A CA1195385 A CA 1195385A CA 000407616 A CA000407616 A CA 000407616A CA 407616 A CA407616 A CA 407616A CA 1195385 A CA1195385 A CA 1195385A
- Authority
- CA
- Canada
- Prior art keywords
- test piece
- probes
- eddy current
- magnetic field
- pole shoes
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired
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Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/24—Probes
- G01N29/2412—Probes using the magnetostrictive properties of the material to be examined, e.g. electromagnetic acoustic transducers [EMAT]
-
- 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
- G01N27/83—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating magnetic variables for investigating the presence of flaws by investigating stray magnetic fields
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/02—Indexing codes associated with the analysed material
- G01N2291/028—Material parameters
- G01N2291/02854—Length, thickness
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/042—Wave modes
- G01N2291/0422—Shear waves, transverse waves, horizontally polarised waves
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/04—Wave modes and trajectories
- G01N2291/042—Wave modes
- G01N2291/0423—Surface waves, e.g. Rayleigh waves, Love waves
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- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- Biochemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Electromagnetism (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In order to be able to make a non-destructive testing of ferromagnetic test pieces like tube or bars, being surrounded by a rotating magnet having two pole shoes in such a manner that at the same time longitudinal flaws, holes transversal flaws and dimensions can be detected the magnetic field gen-erated by the magnet is used simultaneously for the electro-dynamic excitation of ultrasonics in the test piece as well as for measuring the stray flux.
In order to be able to make a non-destructive testing of ferromagnetic test pieces like tube or bars, being surrounded by a rotating magnet having two pole shoes in such a manner that at the same time longitudinal flaws, holes transversal flaws and dimensions can be detected the magnetic field gen-erated by the magnet is used simultaneously for the electro-dynamic excitation of ultrasonics in the test piece as well as for measuring the stray flux.
Description
~'3S38~
The present invention relates to a method for the non-~estructive testing of ferromagnetic material, preferably of cylindrical test pieces such as tubes or bars, as well as to an apparatus for effecting the method.
The non-destructive testing of materials can be effected by means of ultrasonics, where piezoelectric trans-ducers are used emitting ultrasonic waves that are passed into the sub~ect by means of a coupling medium, e.g. water.
In addition, there is an electrodynamic generation of ultra sonics in electroconductive ferromagnetic workpieces. By the electrodynamic system ultrasonic waves are generated by use of a coil which generates high-frequency pulsed eddy cur-rents into the workpiece. A magnetic field acting in this region at the same time, together with the eddy currents - leads to the generation of Lorentz forces acting on the grid system of the workpiece and causes sound waves. This prin-ciple illustrating the generation is reversible for the receptio~. The testing of workpieces of ferromagnetic mate-rials, e.g. tubes or bars, can also take place in a stray-flux rotary system where a magnetic flux is generated in the test piece, and flaws in the test piece can lead to stray fields being detected by means of magnetic field probes.
~s to prior art, reference is made to DE.OS 25 59 125, published August 15, 1976 to Institutul National Pentru Creatie Stiintifica si Techmca - INCREST, DE.PS 26 21 684 issued July 12, 1979 to ~oesch Werke AG, Sumitomo Search No.
17, May 1977, pages 73 to 79.
Stray flux measurings are carried out in order to locate longitudinal flaws or holes in cylindrically-shaped test pieces. However, this technique makes it impossible or hardly possible to supply data on sensed longitudinal flaws and measured data on the dimensions of tubes or bars such as wall thickness. ~herefore, in order to ascertain these ~b ,.~
S3~5 values one will normally fall back on ultrasonic-rotation systems, which are not only essentially more expensive but also due to the required ultrasonic coupling via e.g. a water course, of a rather complicated construction.
The present invention provides a method and an apparatus for simultaneously sensing longitudinal flaws, holes, transverse flaws as well as for determining dimensions by taking advantage of the magnetic field generated by the magnet rotating around the test piece.
In accordance with the present invention the mag-netic field generated by the magnet is used simultaneously for the electro-dynamic excitation of ultrasonics and for measuring the stray flux. Consequently the method according to the invention is a combination of conventional testing techniques of which each can be separately and optimally used for the detection of longitudinal flaws and holes or, trans-verse flaws and the measuring of dimensions. Thereby it is especially emphasized that for the testing no coupling med-ium is required so that in particular the cost-saving pro-perties of the stray flux-rotation systems are retained.
The method according to the invention, i.e. the combination stray flux measuring and electrodynamic excita-tion techniques can be applied by an apparatus where the test piece is surrounded by a rotating magnet having two pole shoes; at least one magnetic field probe is provided on the circumferential surface of the test piece rotating synchronously to the magnet, and eddy current exciters' and reception probes are arranged in the ranges of the pole shoes facing the test piece and/or within the range of the magnetic field probe facing the test piece. In other words, some conventional features of an apparatus referring to stray flux-rotation testing systems are integrated into the concept according to the invention. Essentially these are rotating ~s
The present invention relates to a method for the non-~estructive testing of ferromagnetic material, preferably of cylindrical test pieces such as tubes or bars, as well as to an apparatus for effecting the method.
The non-destructive testing of materials can be effected by means of ultrasonics, where piezoelectric trans-ducers are used emitting ultrasonic waves that are passed into the sub~ect by means of a coupling medium, e.g. water.
In addition, there is an electrodynamic generation of ultra sonics in electroconductive ferromagnetic workpieces. By the electrodynamic system ultrasonic waves are generated by use of a coil which generates high-frequency pulsed eddy cur-rents into the workpiece. A magnetic field acting in this region at the same time, together with the eddy currents - leads to the generation of Lorentz forces acting on the grid system of the workpiece and causes sound waves. This prin-ciple illustrating the generation is reversible for the receptio~. The testing of workpieces of ferromagnetic mate-rials, e.g. tubes or bars, can also take place in a stray-flux rotary system where a magnetic flux is generated in the test piece, and flaws in the test piece can lead to stray fields being detected by means of magnetic field probes.
~s to prior art, reference is made to DE.OS 25 59 125, published August 15, 1976 to Institutul National Pentru Creatie Stiintifica si Techmca - INCREST, DE.PS 26 21 684 issued July 12, 1979 to ~oesch Werke AG, Sumitomo Search No.
17, May 1977, pages 73 to 79.
Stray flux measurings are carried out in order to locate longitudinal flaws or holes in cylindrically-shaped test pieces. However, this technique makes it impossible or hardly possible to supply data on sensed longitudinal flaws and measured data on the dimensions of tubes or bars such as wall thickness. ~herefore, in order to ascertain these ~b ,.~
S3~5 values one will normally fall back on ultrasonic-rotation systems, which are not only essentially more expensive but also due to the required ultrasonic coupling via e.g. a water course, of a rather complicated construction.
The present invention provides a method and an apparatus for simultaneously sensing longitudinal flaws, holes, transverse flaws as well as for determining dimensions by taking advantage of the magnetic field generated by the magnet rotating around the test piece.
In accordance with the present invention the mag-netic field generated by the magnet is used simultaneously for the electro-dynamic excitation of ultrasonics and for measuring the stray flux. Consequently the method according to the invention is a combination of conventional testing techniques of which each can be separately and optimally used for the detection of longitudinal flaws and holes or, trans-verse flaws and the measuring of dimensions. Thereby it is especially emphasized that for the testing no coupling med-ium is required so that in particular the cost-saving pro-perties of the stray flux-rotation systems are retained.
The method according to the invention, i.e. the combination stray flux measuring and electrodynamic excita-tion techniques can be applied by an apparatus where the test piece is surrounded by a rotating magnet having two pole shoes; at least one magnetic field probe is provided on the circumferential surface of the test piece rotating synchronously to the magnet, and eddy current exciters' and reception probes are arranged in the ranges of the pole shoes facing the test piece and/or within the range of the magnetic field probe facing the test piece. In other words, some conventional features of an apparatus referring to stray flux-rotation testing systems are integrated into the concept according to the invention. Essentially these are rotating ~s
- 2-i385 pole shoes of a magnet generating a magnetic flux in the test piece. If the field strength is increased to a value where the test piece material reaches magnetic saturation, then defects such as cracks or cross section reductions will lead to relatively strong stray fields that can be detected by means of magnetic field probes rotating synchronously with the magnet around the test piece. In a preferred embodiment two groups of magnetic field probes are provided, which being disposed 90 to the pole shoes, synchronously rotate around the test piece. By an appropriate measuring of the stray flux and utilization of the described arrangement of pole shoes and magnetic field probes, outer defects up to 10% of the wall thickness can be pexfectly determined.
In order to enable the measuring of dimensions and the location of cross flaws, an electrodynamic excitation of ultrasonic signals takes place according to the present in-vention. The magnetic field required for this is generated by the rotating magnet yoke having two pole shoes, so that those elements can be used which are already required for the stray flux measuring. Thus, one uses especially those magnetic fields generated by the rotating magnet and appear-ing vertical and parallel relative to the surface of the test piece. The parallel fields appear within the range of the magnetic field probes being arranged in a region of 90 to the pole shoes, whereas the vertical ones appear in the region of the pole shoes. The ultrasonic waves generated together with the magnetic field and the eddy current pulses can be transverse of surface waves, depending upon the arr-angement of the eddy current exciting probes and the recep-tion probes. The transverse waves are then used to determine dimension values, thus e.g. wall thickness, and the surface waves for the detection of cross flaws.
In an especially preferred embodiment of the inven-tion, for the generation of transverse waves the eddy current exciting sondes and the reception probes are arranged in the free ends of the pole shoes facing the test piece, wherein a further embodiment several exciting and receiving probes are arranged side by side so as to be able to scan several traces at the same time.
An optimum excitation of surface waves takes place in the range of the magnetic field probes arranged in regions of 90 with respect to the pole shoe s, so that in a further embodiment the eddy current exciting probes and the reception probes simultaneously are arranged on the magnetic field probes. In a preferred embodiment of the invention -these probes are flat coils of which the windings are meander-like.
Thus, for an optimum utilization of the transmitted measured values, the main axes of the meander wire arranged windings can run parallel or almost parallel to each other or can describe a right angle or substantially a right angle with respect to each other.
A main advantage of the method according to the in-vention is that by a combination of the conventional stray flux method and the conventional electrodynamic excitation of ultrasonics, without using any coupling medium one can measure not only wall thicknesses but also make locations of transverse and longitudinal flaws or holes, where for generating the re-quired magnetic fields that of the rotating magnet is utili-zed.
The present invention will be further described by
In order to enable the measuring of dimensions and the location of cross flaws, an electrodynamic excitation of ultrasonic signals takes place according to the present in-vention. The magnetic field required for this is generated by the rotating magnet yoke having two pole shoes, so that those elements can be used which are already required for the stray flux measuring. Thus, one uses especially those magnetic fields generated by the rotating magnet and appear-ing vertical and parallel relative to the surface of the test piece. The parallel fields appear within the range of the magnetic field probes being arranged in a region of 90 to the pole shoes, whereas the vertical ones appear in the region of the pole shoes. The ultrasonic waves generated together with the magnetic field and the eddy current pulses can be transverse of surface waves, depending upon the arr-angement of the eddy current exciting probes and the recep-tion probes. The transverse waves are then used to determine dimension values, thus e.g. wall thickness, and the surface waves for the detection of cross flaws.
In an especially preferred embodiment of the inven-tion, for the generation of transverse waves the eddy current exciting sondes and the reception probes are arranged in the free ends of the pole shoes facing the test piece, wherein a further embodiment several exciting and receiving probes are arranged side by side so as to be able to scan several traces at the same time.
An optimum excitation of surface waves takes place in the range of the magnetic field probes arranged in regions of 90 with respect to the pole shoe s, so that in a further embodiment the eddy current exciting probes and the reception probes simultaneously are arranged on the magnetic field probes. In a preferred embodiment of the invention -these probes are flat coils of which the windings are meander-like.
Thus, for an optimum utilization of the transmitted measured values, the main axes of the meander wire arranged windings can run parallel or almost parallel to each other or can describe a right angle or substantially a right angle with respect to each other.
A main advantage of the method according to the in-vention is that by a combination of the conventional stray flux method and the conventional electrodynamic excitation of ultrasonics, without using any coupling medium one can measure not only wall thicknesses but also make locations of transverse and longitudinal flaws or holes, where for generating the re-quired magnetic fields that of the rotating magnet is utili-zed.
The present invention will be further described by
3~ way of the accompanying drawings in which:-Figure 1 is a sectional view of a rotation testingarrangement in accordance with one embodiment of the present invention; - -, Figure 2~illu~trates an arrangeme~t of eddy currentexciting probes an~ reception prcbes; and , S3~3~
Figures 3 and 4 show preferred arrangements of mag-netic field prohes and eddy current exciting and receiving probes, arranged on a common support.
Fig. 1 ~trictly schematically presents a section of a rotation testing unit, including essential elements of stray flux rotation testingsystems known per se, as they are also described in literature, like e.g. ASME, September 18 to 23, 1977, Houston, Texas, Nondestructive Inspection of Oil Country Tubular Goods, pages 1 to 13; The Sumitomo Search No. 17, May 1977, pages 73 to 79; Materials Evaluation, July 1977, pages 52 to 56.
Such stray flux rotation systems essentially com-prise a magnet having two pole shoes 12 and 14, which con-15^ cen-trically s~rround and rotate about a tube 16. A magnetic - flux is thus generated in the test piece 16 due to the mag-netic field between the pole shoes 12 and 14. If the field strength of the magnet is increased to a value causing mag-netic saturation in the material of the test piece 16, then in case of cross sectional reductions caused by defects such as longitudinal flaws of holes, relatively strong stray fields will appear over these defects. These stray fields are then detected by means of ma~netic field probes 18 and 20, which arranged in regions 90 to the pole shoes 12 and 14, are synchronously rotating around the test piece 16 at the fre-quency w. The magnetic field probes 18 and 20 are eachsupported by carriers 22 and 24 respectively. By means of such stray flux measurings one can exactly detect external flaws up to 5% of the wall thickness and internal flaws up to 10% of the wall thickness.
By means of these stray flux measurings, however, one cannot find transverse flaws and measuring data on e.g.
the dimensions of tubes or bars, such as wall thicknesses of tubes. According to the present inven~ion, however, 3~
these are detected in the same rotation system by means of the conventional electrodynamic excitation method for ultra-sonics. For that purpose it is necessary that a maynetic field appears parallel or vertical to the surface of the test piece -together with an eddy current pulse generated in the surface of the test piece, in order to generate different force pulses on account of the appearing Lorentz forces on the surface of the test piece resulting in ultrasonic waves.
Depending on the magnetic field direction, transverse, longi-tudinal or surface waves can be generated as ultrasonics.For measuring the wall thickness one uses generally trans-verse waves whereas the detection of transverse flaws takes place by means of surface waves.
The electromagnet or permanent magnet having the - pole shoes 12 and 14, while rotating now generates a magnetic ~ield, extending underneath from the pole shoes vertically to the surface of the test piece and staggered through 90, thus within the range of the magnetic field probes 18 and 20 parallel to the surface. This means that in one operation with the stray flux measuring one can also effect an electro-dynamic excitation of ultrasonic signal waves by means of the rotating magnet.
In order to be able to measure the wall thickness of the test piece 16, eddy current exciting probes and re-ceiving probes are arranged in the free ends of the pole shoes 12 and 14 facing the test piece. In Fig. 1 these probes 26, 28 or, 30, 32 respectively, are schematically shown. Consequently the eddy current pulses generated by the probe 26 or 30 are sensed by the eddy current receiving probe 28 or 32, respectively bein~ arranged in the same pGle-shoes 12 or 14, respectively in order to be evaluated in conventional electronic systems (not shown). In this con-nection reference is made to l'Ultrasonic Testing of Half-wrough~ Material by Using Electrodynamic Instrument Trans-.~
a53~35 Eormers", Hoesch Huettenwerke AG, Dortmund, January 25, 1980 or the German Patent Specification No. 26 21 684 issued July 12, 1979 to Hoesch Werke AG and the German Disclosure No.
29 24 819 published January 15, 1981 to M.A.N. Masc~inenfabrik Augsburg-Nurnberg.
By the arrangement of the eddy current excitïng probes and reception probes 26, 28 or 30, 32, respectively within the ranges of the pole shoes 12 and 14 wall thicknesses at an accuracy of + 5/100 mm can be determined.
The optimum excitation of surface waves takes place within the range of the magnetic field probes 18 and 20 so that consequently at the same place there are also arranged eddy current exciting probes and receiving probes 34, 36 or - 38, 40, respectively. These probes are preferably placed in the holdiny device 22 or 24, respectively serving as supports for the magnetic field probes 18 and 20. For an optimum detection of measuring data, the eddy current exciting pro-bes and receiving probes 34, 36 or 38, 40, respectively should be flat coils of which the windings are meander-sha-ped, as shown in Figures 3 and 4. By the wave extending in the surface area, portions thereof are reflected to the receiver preferably if these are positioned diagonally to the direction of propagation and in the surface area. There-by different sensor arrangements can be achieved. According to Fig. 3 the main axes of the meander-like configured coils 34 and 36 extend parallel to each other and are arranged next to the magnetic field probes 18. According to Fig. 3 several magnetic field probes are simultaneously arranged side by side in order to simultaneously scan a larger surface area of the test piece 16. The magnetic field probe 18 as well as the meander-shaped coils 34 and 36 are carried by the same support 22.
Fig. 4 is a top view of the holding device 24, ~, 7 _ ~S~53~i where several magnetic field probes 20 are provided side by side. The eddy current exciting or receiving probe 38 or 40, respectively is likewise of meander-like configuration, where the axes of them are defining an angle of preferably 90 degrees relative to each other.
By the special arrangement of the eddy current exciting or receiving probes 34, 36 or 38, 40, respectively defects close to the surface, can be detected, of which the extension is smaller than 10% of the respective wall thick-ness. In the sensing of transverse notches it has been found that defects of 7% of the wall thickness can still be clearly detected.
In order to engage a larger surface area of the test piece 16 during a rotation also in regard to the eddy current exciting and receiving probes 26, 28 or 30 and 32, respectively arranged in the pole shoes 12 and 14, arrange several probes can be disposed side by side, as shown in Fig. 2.
, ,:..
Figures 3 and 4 show preferred arrangements of mag-netic field prohes and eddy current exciting and receiving probes, arranged on a common support.
Fig. 1 ~trictly schematically presents a section of a rotation testing unit, including essential elements of stray flux rotation testingsystems known per se, as they are also described in literature, like e.g. ASME, September 18 to 23, 1977, Houston, Texas, Nondestructive Inspection of Oil Country Tubular Goods, pages 1 to 13; The Sumitomo Search No. 17, May 1977, pages 73 to 79; Materials Evaluation, July 1977, pages 52 to 56.
Such stray flux rotation systems essentially com-prise a magnet having two pole shoes 12 and 14, which con-15^ cen-trically s~rround and rotate about a tube 16. A magnetic - flux is thus generated in the test piece 16 due to the mag-netic field between the pole shoes 12 and 14. If the field strength of the magnet is increased to a value causing mag-netic saturation in the material of the test piece 16, then in case of cross sectional reductions caused by defects such as longitudinal flaws of holes, relatively strong stray fields will appear over these defects. These stray fields are then detected by means of ma~netic field probes 18 and 20, which arranged in regions 90 to the pole shoes 12 and 14, are synchronously rotating around the test piece 16 at the fre-quency w. The magnetic field probes 18 and 20 are eachsupported by carriers 22 and 24 respectively. By means of such stray flux measurings one can exactly detect external flaws up to 5% of the wall thickness and internal flaws up to 10% of the wall thickness.
By means of these stray flux measurings, however, one cannot find transverse flaws and measuring data on e.g.
the dimensions of tubes or bars, such as wall thicknesses of tubes. According to the present inven~ion, however, 3~
these are detected in the same rotation system by means of the conventional electrodynamic excitation method for ultra-sonics. For that purpose it is necessary that a maynetic field appears parallel or vertical to the surface of the test piece -together with an eddy current pulse generated in the surface of the test piece, in order to generate different force pulses on account of the appearing Lorentz forces on the surface of the test piece resulting in ultrasonic waves.
Depending on the magnetic field direction, transverse, longi-tudinal or surface waves can be generated as ultrasonics.For measuring the wall thickness one uses generally trans-verse waves whereas the detection of transverse flaws takes place by means of surface waves.
The electromagnet or permanent magnet having the - pole shoes 12 and 14, while rotating now generates a magnetic ~ield, extending underneath from the pole shoes vertically to the surface of the test piece and staggered through 90, thus within the range of the magnetic field probes 18 and 20 parallel to the surface. This means that in one operation with the stray flux measuring one can also effect an electro-dynamic excitation of ultrasonic signal waves by means of the rotating magnet.
In order to be able to measure the wall thickness of the test piece 16, eddy current exciting probes and re-ceiving probes are arranged in the free ends of the pole shoes 12 and 14 facing the test piece. In Fig. 1 these probes 26, 28 or, 30, 32 respectively, are schematically shown. Consequently the eddy current pulses generated by the probe 26 or 30 are sensed by the eddy current receiving probe 28 or 32, respectively bein~ arranged in the same pGle-shoes 12 or 14, respectively in order to be evaluated in conventional electronic systems (not shown). In this con-nection reference is made to l'Ultrasonic Testing of Half-wrough~ Material by Using Electrodynamic Instrument Trans-.~
a53~35 Eormers", Hoesch Huettenwerke AG, Dortmund, January 25, 1980 or the German Patent Specification No. 26 21 684 issued July 12, 1979 to Hoesch Werke AG and the German Disclosure No.
29 24 819 published January 15, 1981 to M.A.N. Masc~inenfabrik Augsburg-Nurnberg.
By the arrangement of the eddy current excitïng probes and reception probes 26, 28 or 30, 32, respectively within the ranges of the pole shoes 12 and 14 wall thicknesses at an accuracy of + 5/100 mm can be determined.
The optimum excitation of surface waves takes place within the range of the magnetic field probes 18 and 20 so that consequently at the same place there are also arranged eddy current exciting probes and receiving probes 34, 36 or - 38, 40, respectively. These probes are preferably placed in the holdiny device 22 or 24, respectively serving as supports for the magnetic field probes 18 and 20. For an optimum detection of measuring data, the eddy current exciting pro-bes and receiving probes 34, 36 or 38, 40, respectively should be flat coils of which the windings are meander-sha-ped, as shown in Figures 3 and 4. By the wave extending in the surface area, portions thereof are reflected to the receiver preferably if these are positioned diagonally to the direction of propagation and in the surface area. There-by different sensor arrangements can be achieved. According to Fig. 3 the main axes of the meander-like configured coils 34 and 36 extend parallel to each other and are arranged next to the magnetic field probes 18. According to Fig. 3 several magnetic field probes are simultaneously arranged side by side in order to simultaneously scan a larger surface area of the test piece 16. The magnetic field probe 18 as well as the meander-shaped coils 34 and 36 are carried by the same support 22.
Fig. 4 is a top view of the holding device 24, ~, 7 _ ~S~53~i where several magnetic field probes 20 are provided side by side. The eddy current exciting or receiving probe 38 or 40, respectively is likewise of meander-like configuration, where the axes of them are defining an angle of preferably 90 degrees relative to each other.
By the special arrangement of the eddy current exciting or receiving probes 34, 36 or 38, 40, respectively defects close to the surface, can be detected, of which the extension is smaller than 10% of the respective wall thick-ness. In the sensing of transverse notches it has been found that defects of 7% of the wall thickness can still be clearly detected.
In order to engage a larger surface area of the test piece 16 during a rotation also in regard to the eddy current exciting and receiving probes 26, 28 or 30 and 32, respectively arranged in the pole shoes 12 and 14, arrange several probes can be disposed side by side, as shown in Fig. 2.
, ,:..
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for the non-destructive testing of ferro-magnetic materials, where the test piece is surrounded by a rotating magnet provided with two pole shoes, the magnetic field generated by the magnet being used simultaneously for the electrodynamic excitation of ultrasonics in the test piece as well as for measuring the stray flux.
2. A method according to claim 1, in which the test piece is a cylindrical test piece.
3. A method according to claim 1, in which the test piece is a tube or bar.
4. An apparatus for the non-destructive testing of ferromagnetic material comprising a test piece, a rotatable magnet having two pole shoes arranged to surround the test piece, at least one magnetic field probe adapted to synchron-ously rotate to the magnet disposed on the circumferential surface of the test piece, and eddy current exciting and receiving probes being arranged in the areas of the pole shoes facing the test piece and/or in the area of the magne-tic field probe facing the test piece.
5. An apparatus according to claim 4, in which two magnetic field probes are provided, each being arranged in regions of 90° with respect to one of the pole shoes.
6. An apparatus according to claim 4, in which the magnetic field probes are carried by a holding device, on which the eddy current exciting and receiving probes are simultaneously mounted.
7. An apparatus according to claim 6, in which the eddy current exciting and receiving probes are flat coils with meander-like arranged windings.
8. An apparatus according to claim 7, in which the main axes of the meander-like arranged windings of the eddy current exciting and receiving probes are arranged parallel or al-most parallel to each other.
9. An apparatus according to claim 7, in which the main axes of the meander-like arranged windings of the eddy current exciting and receiving probes are describing a right angle or almost right angle relative to each other.
10. An apparatus according to claim 4, in which the eddy current exciting and receiving probes arranged in the pole shoe ends are coils being concentrically arranged with respect to each other.
11. An apparatus according to claim 10, in which several eddy current exciting and receiving coils are arranged side by side in the ends of the pole shoes.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE3128825A DE3128825C2 (en) | 1981-07-21 | 1981-07-21 | Device for the non-destructive testing of ferromagnetic materials |
| DEP3128825.1 | 1981-07-21 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1195385A true CA1195385A (en) | 1985-10-15 |
Family
ID=6137399
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000407616A Expired CA1195385A (en) | 1981-07-21 | 1982-07-20 | Non-destructive testing of ferromagnetic materials |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0071147B1 (en) |
| JP (1) | JPS5870157A (en) |
| CA (1) | CA1195385A (en) |
| DE (1) | DE3128825C2 (en) |
| ZA (1) | ZA825159B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2519442A (en) * | 2013-10-14 | 2015-04-22 | Advanced Eng Solutions Ltd | Pipeline condition detecting apparatus and method |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4449411A (en) * | 1982-04-22 | 1984-05-22 | Magnetic Analysis Corporation | Magnetic and ultrasonic objects testing apparatus |
| JPS59226857A (en) * | 1983-06-07 | 1984-12-20 | Sumitomo Metal Ind Ltd | Flaw detection equipment |
| US4492115A (en) * | 1984-04-11 | 1985-01-08 | Pa Incorporated | Method and apparatus for measuring defects in ferromagnetic tubing |
| DE3515977A1 (en) * | 1985-05-03 | 1986-11-06 | Nukem Gmbh, 6450 Hanau | METHOD AND DEVICE FOR DESTRUCTION-FREE TESTING OF FERROMAGNETIC BODIES |
| DE3530525C2 (en) * | 1985-08-27 | 1994-05-11 | Foerster Inst Dr Friedrich | Device for non-destructive material testing |
| JPH01134253U (en) * | 1988-03-09 | 1989-09-13 | ||
| DE9011477U1 (en) * | 1990-08-07 | 1990-12-20 | Nukem GmbH, 63755 Alzenau | Arrangement for non-destructive material testing |
| FR2665768B1 (en) * | 1990-08-07 | 1993-08-13 | Nukem Gmbh | NON-DESTRUCTIVE TEST INSTALLATION OF MATERIAL, PARTICULARLY OF CYLINDRICAL PARTS, SLEEVE TUBES AND THE LIKE. |
| DE9011478U1 (en) * | 1990-08-07 | 1990-12-20 | Nukem GmbH, 63755 Alzenau | Arrangement for non-destructive material testing |
| DE4116208A1 (en) * | 1991-05-17 | 1992-11-19 | Karlheinz Dr Ing Schiebold | Non-destructive testing of material at structural parts of cast iron@ - using ultrasonic speed and magnetic coercivity field strength measurement with condition that speed is determined during magnetisation of workpiece |
| DE4301622C1 (en) * | 1993-01-22 | 1994-02-24 | Fraunhofer Ges Forschung | Ultrasonic appts., for metal structure determn. - has two ultrasonic transducers, useful in quality control of hot extruded powder metallurgical alloy |
| DE4328712A1 (en) * | 1993-08-26 | 1995-03-02 | Foerster Inst Dr Friedrich | Method and device for testing elongated objects, optionally with cross-section deviating from circularity |
| DE19543481C2 (en) * | 1995-11-22 | 1997-10-23 | Pipetronix Gmbh | Device for testing ferromagnetic materials |
| DE102005060582A1 (en) * | 2005-12-17 | 2007-07-05 | Ndt Systems & Services Ag | Method and system for nondestructive testing of a metallic workpiece |
| CN103225876B (en) * | 2013-05-13 | 2015-09-09 | 山东大学 | Self-heating plumbing fixture |
| DE102013018114A1 (en) * | 2013-11-28 | 2015-05-28 | Otto Alfred Barbian | Device for nondestructive testing of a test specimen |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3237446A (en) | 1964-04-24 | 1966-03-01 | American Mach & Foundry | Selective defect detection and thickness measuring method and apparatus |
| DE1938107C3 (en) * | 1969-07-26 | 1979-09-06 | Werkstoffpruefgeraetebau Dipl.-Ing. Walter Kaule Gmbh, 5074 Heidberg | Leakage flux test method for magnetizable material |
| DE2211133C3 (en) * | 1972-03-08 | 1975-12-18 | Friedrich Dr.Phil. 7410 Reutlingen Foerster | Arrangement for examining a magnetized pipe |
| US3854085A (en) * | 1973-06-07 | 1974-12-10 | Magnetics Analysis Corp | Multi-probe flux leakage testing apparatus producing bipolar signals from the largest simultaneously occurring signals of each polarity |
| DE2621684C3 (en) * | 1976-05-15 | 1979-07-12 | Hoesch Werke Ag, 4600 Dortmund | Electrodynamic sound transducer |
| DE2652085A1 (en) | 1976-11-16 | 1978-05-18 | Hoesch Werke Ag | DEVICE FOR NON-DESTRUCTIVE MATERIAL TESTING |
| IE47295B1 (en) * | 1977-10-20 | 1984-02-08 | Ti Group Services Ltd | Ultrasonic testing |
| US4184374A (en) * | 1978-06-22 | 1980-01-22 | Rockwell International Corporation | Ultrasonic inspection of a cylindrical object |
| JPS55129749A (en) * | 1979-03-28 | 1980-10-07 | Sumitomo Metal Ind Ltd | Sensitivity correction method for electromagnetic ultrasonic wave probe |
-
1981
- 1981-07-21 DE DE3128825A patent/DE3128825C2/en not_active Expired
-
1982
- 1982-07-19 EP EP82106490A patent/EP0071147B1/en not_active Expired
- 1982-07-20 ZA ZA825159A patent/ZA825159B/en unknown
- 1982-07-20 CA CA000407616A patent/CA1195385A/en not_active Expired
- 1982-07-21 JP JP57127437A patent/JPS5870157A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2519442A (en) * | 2013-10-14 | 2015-04-22 | Advanced Eng Solutions Ltd | Pipeline condition detecting apparatus and method |
| AU2014335928B2 (en) * | 2013-10-14 | 2017-09-07 | Advanced Engineering Solutions Ltd | Pipeline condition detecting apparatus and method |
| GB2519442B (en) * | 2013-10-14 | 2019-05-29 | Advanced Eng Solutions Ltd | Pipeline condition detecting apparatus and method |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3128825C2 (en) | 1985-04-18 |
| ZA825159B (en) | 1983-05-25 |
| DE3128825A1 (en) | 1983-03-17 |
| EP0071147A1 (en) | 1983-02-09 |
| EP0071147B1 (en) | 1985-04-03 |
| JPS5870157A (en) | 1983-04-26 |
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