CA1038037A - Magnetic testing device for detecting defects in elongated objects - Google Patents
Magnetic testing device for detecting defects in elongated objectsInfo
- Publication number
- CA1038037A CA1038037A CA251,932A CA251932A CA1038037A CA 1038037 A CA1038037 A CA 1038037A CA 251932 A CA251932 A CA 251932A CA 1038037 A CA1038037 A CA 1038037A
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- CA
- Canada
- Prior art keywords
- magnetic
- testing device
- flux
- pole
- elongated
- 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.)
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Classifications
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- 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
Abstract
MAGNETIC TESTING DEVICE FOR DETECTING DEFECTS IN ELONGATED OBJECTS
ABSTRACT OF THE DISCLOSURE:
A magnetic testing device for detecting defects in elongated objects is disclosed. The testing device comprises a permanent magnet assembly having poles adapted to be spaced apart in the longitudinal direction of an elongated object for inducing a longitudinal magnetic flux in a section of the object between the poles of the magnet assembly which is strong enough to satu-rate such section of the object, a tubular pole piece substan-tially centered on the elongated object adjacent each pole of the permanent magnet assembly for directing the magnetic flux radial-ly into the object at one pole and out of the object at the other pole, Hall effect devices spaced around at least one pole piece in the path of the magnetic flux for sensing the radial flux en-tering into the elongated object, and means for sensing the va-riations of such magnetic flux as an indication of loss of metal-lic area in the object. The magnetic testing device is also pro-vided with a leakage flux sensor located between the pole pieces for detecting external and internal defects in the object.
ABSTRACT OF THE DISCLOSURE:
A magnetic testing device for detecting defects in elongated objects is disclosed. The testing device comprises a permanent magnet assembly having poles adapted to be spaced apart in the longitudinal direction of an elongated object for inducing a longitudinal magnetic flux in a section of the object between the poles of the magnet assembly which is strong enough to satu-rate such section of the object, a tubular pole piece substan-tially centered on the elongated object adjacent each pole of the permanent magnet assembly for directing the magnetic flux radial-ly into the object at one pole and out of the object at the other pole, Hall effect devices spaced around at least one pole piece in the path of the magnetic flux for sensing the radial flux en-tering into the elongated object, and means for sensing the va-riations of such magnetic flux as an indication of loss of metal-lic area in the object. The magnetic testing device is also pro-vided with a leakage flux sensor located between the pole pieces for detecting external and internal defects in the object.
Description
~Q3~37 This invention relates to a magnetic testing device for detecting defects in elongated magnetically permeable objects, such as wire ropes, rods, steel pipes and similar magnetic ob-jects.
Various magnetic devices have been proposed for detec-ting defects in wire ropes, steel pipes and other elongated ma-gnetic objects. Such devices genexally comprise electromagnets or permanent magnets for setting up a magnetic flux in the elon-gated object to be tested and means for detecting the leakage flux generated by the external and internal defects of such ob-jects. An example og such devices is the one disclosed in U.S.
patent No. 3,~24,976 issued January 28, 1969 to M.S. Jezewski et al. These devices, however, are not well suitecl .Eo.r detecting 109s Oe metallic area due to wear, corrosion or other adverse .
conditions because these defects do not generally cause strong enough localized leakage flux.
It is therefore the object of the present invention to provide a magnetic testing device which is capable of adequately sensing loss of metallic area in elongated objects.
It is a further object of the present invention to pro-vide a magnetic testing device which has the ability to detect loss of metallic area and, at the same time, other defects which cause a leakage flux in the elongated objects being tested.
The magnetic testing device, in accordance with the in-vention, comprises a permanent magnet assembly having poles adap-ted to be spaced apart in the longitudinal direction of~the elon-gated object being tested for inducing a longitudinal magnetic flux in a section of such elongated object between the poles o the magnet assembly which is strong enough to saturate such sec-tion of the object, a tubular pole piece adapted to surround the elongated object adjacent each pole for directing the magnetic flux radially into the elongated object at one pole and out of '~ - 1 - ~
~33~3~
the elongated object a-t the other pole, Hall effect devices spaced around at least one pole piece in the path of the magnetic flux for sensing the reduction of the radial flux entering such elon-gated object due to any reduction of the cross-sectional area of the elongated object between the pole pieces caused by loss of metallic area in the elongated object, and a leakage flux sensor secured to the magnet between the pole pieces for detecting exter-nal and internal defects in the object.
Each tubular pole piece is preferably cut in two parts one of which is fixed to the magnet and the other hingedly mounted to the magnet or positioning the object to be tested.
.-; The leakage flux sensor may comprise a ~irst sellsor ring of magnetic material surrounding the elongated ob~ect, a second sensor ring o~ magnetic material concentrically mounted outside the first sensor ring and having the same axial lenght as the first sensor ring, such second sensor ring having a plurality of projections extending towards the first sensor ring with a prede-termined minimum gap between the projections and the first sensor ring for concentrating the leakage flux through the gap, a Hall effect device located at each projection for sensing the leakage flux passing through the gap, and a flux guiding member of magne-tic material connected to the second ring and extending towards the elongated object for completing the magnetic circuit of the leakage flux. The leakage flux sensor is preferably made in two parts one of which is fixed and the other hingedly connected to the magnet for positioning the object to be tested.
The magnetic testing device preferably includes means for guiding the elongated object substantially along the center line of the pole pieces and leakage flux sensor. Such guiding 3Q means may be made of polyamide material.
The pole pieces are preferably separated from the poles of the permanent magnet assembly by a piece of strong non-magnetic L~ - 2 -~3~3037 and non-conductive material, such as linen base phenolic, for in-troducing a predetermined amount of reluctance in the magnetic circuit.
The invention will now be disclosed, by way of example, with reference to the accompanying drawings in which:
Figure 1 illustrates a perspective view of the magnetic testing device in accordance with the invention;
Figure 2 illustrates an embodiment of the permanent ma-gnet used in the magnetic testing device in accordance with the invention;
Figures 3 and ~ illustrate in more details the loss of metallic area sensor o~ the testing device of Figure l;
Figures 5 and 6 illustrate in more details the flux l~a-kage sensor of the testing device o~ Pigure l;
Figures 7 to 11 show diagrams illustrating the operation of the testing device in accordance with the in~ention; and Figure 12 illustrates a block diagram of the instrumenta-tion used with the testing devi~e in accordance with the invention.
Referring to Figures l and 2, there is shown a perspecti-ve view of an embodiment of a magnetic testing device comprising aU shaped magnet assembly 10 which may be made of analuminum-nickel-cobalt alloy which is enclosed in a zinc casting 12. Thepurpose of the casting is to provide a softer material for drilling holes to attach the other elements of the testing device. The permanent ma-gnet itself is more clearly illustrated in Figure 2 and includes two north poles 13 which are separated by a semi~circular section 1~ and two south poles 15 which are also separated by a semi-circu-lar section 16. Lossof metallic area sensors 17 and 18 are placed in the above semi-circular sections 1~ and 16 respectively. A lea-3Q kage flux sensor 19 is positioned between the north and south po-les of the magnet.
Sensors 17 and 18 are more clearly illustrated in Figures Q3~7 3 and 4. Each sensor is made in two parts one of which is fixed to the magnet and the other openable for positioning the objèct being tèsted. Eachsensor half includes a semi-circular pole piece 20 which is secured inside a semi-circular member 22 of strong non-magnetic and non-conductive material, such as linen base phenolic.
Each fixed member ~2 is secured to a plate 24 itself secured to plates 26 and 28 which are in turn attached to magnet 10. Eachope-nable member 22 is fixed on an outside semi-circular casing 30 which is hinged on plate 28 by hinge 32. Inside each pole piece 20 is secured a replaceable guide 34 for guiding the elongated object along the center axis of the pole piece 20. Suchguides are made of hard plastic material such as polyamide. Ingroove 36 in pole pieces 20, there are regularly spaced ~lall effect de~ices 38. Such devices are shown in Figure 4 as being spaced ~bout 120 apart. It is to be understood that the number and accordingly the spacing o~
such Hall effect devices may vary depending on the magnitude of the signal to be detected. Theoutputs of all the Hall eEfect devices are added up by means of a summing amplifier (not shown) to detect the loss of metallic area at any location on the perimeter of the elongated object and also for compensating for slight misalignment of the object with respect to the central axis of the pole pieces.
Sensor i9 is more clearly shown in Figures 5 and 6. Such sensor is made of two parts, one of which is fixed to the magnet 10 and the other openable for positioning the object to be tested.
Each sensor half consists of a first semi-circular sensor ring 40, a second semi-circular sensor ring 42 concentrically mounted outsi-de the first sensor ring, two flux guiding members 44 one on each side of the second semi-circular ring and a semi-Gircular block of strong non-magnetic and non-conductive material 46 secured inside each flux guiding member and holding the two sensor rings at a pre-determined distance apart. Asillustrated mare clearly in Figure 6, sensor ring 42 has a number of projections 48 thereon extending to-.~
~3~ 7 wards the first sensor ring 40 leaving a predetermined minimum gap between the projections and the first sensor ring so as to concen-trate the leakage flux through the gap. A Hall e~rect device 50 is located at each projection for detecting the leakage flux passing through the gaps. The fixed sensor half is supported between the poles of the magnet 10 by means of a block of hard non-magnetic and non-conductive material 52 which is secured to the magnet 10 by means of aluminum plates 54. The fixed sensor half is secured to aluminum plate 56 which is in turn fixed to block 52. Such plates are made of aluminum so as to prevent distortion of the ma-gnetic flux pattern of the magnet. The openable sensor half is secured to a block of strong non-magnetic and non-conductive ma-terial 58 which is hinged on the magnet by hinge 60 and secured in closed position by clamping device 61. A plate oE aluminum 62 is secured to the outside portion of each op~nable guiding member 44 to prevent distortion of the magnetic flux pattern of the ma-gnet. Semi-circular guides 64 are secured to the fixed and opena-ble sensors to center the elongated object being tested. Such ~ guide may be made of polyamide material.
20 The operation of the above disclosed magnetic testingdevice will now be disclosed with reference to the schematic dia-grams illustrated in Figures 7 to 11 of the drawings. Figure 7 illustrates the magnetic flux generated by magnet 10 in the ab-sence of an elongated object within the pole pieces 20 whereas Figure 8 illustrates the magnetic flux in the presence of an elon-gated object, such as wire rope 66 It will be seen that the ma-jor part of the flux goes radially from the north pole of the ma-gnet into the wire rope, then longitudinally in the wire rope between the poles of the magnet, and radially out of the wire ro-pe at the south pole o~ the magnet. Such flux thus passes through the Hall effect devices 38 which, AS commonly known, produce an ~ ~ .
Il 37 output voltage proportional to the flux passing perpendicularly through them. The magnitude of such voltage will depend on the reluctance of the magnetic circuit and thus on the gap between the magnet and the w;re rope. Such gap will increase at the lo-cation of a loss of metallic area in the wire rope and reduce the flux passing through the wire rope. In addition, the reduced cross-section of the wire rope will also reduce the magnetic flux. The flux will be sensed at the output of the Hall effect devices. It is also very important to note that the amplitude of output signal will be substantially independent of the speed at which the wire rope is passed through the magnet since Hall ef-fect devices provide an output signal which~ is not influenced by the moving velocity of the test material within a wide range o~
velocities.
Figure 9 illustrates the leakage :elux generated due to the presence o a wire break 67. Figure 10 illustrates the out-put voltage V of the Hall effect devices 50 as a function o~ the wire break position. Such output is null when the break is right under the Hall effect devices as the leakage flux passes longitu-dinally through the Hall effect devices. However, when the breakis approaching or getting away from the location of the Hall ef-fect devices, the magnetic leakage 1ux will pass at 90 through the Hall effect devices and the magnitude o~ the voltage detected will pass through maximum and minimum values. Figure 11 shows the magnetic ~lux path 68 as the wire rope is moved through the leakage flux sensor in thè direction of arrow 70.
Figure 12 illustrates a block diagram of the instrumen tation which may ~e used with the magnetic testing device in ac-cordance with the invention. The outputs of the magnetic testing device 70 are fed to an analog signal conditioner 72. Also fed to the analog signal conditioner is the output of a defect loca-tion sensor 74 which may be in the form of a pair of rollers in ~L~3~
contact with the wire rope being tested. Such rollers may be provided with or coupled to suita~le transducers producing an output signal at regular intervals from the st~rting end of the wire being tested. The output of the analog signal conditioner is fed to a two pen analog recorder x,y/y 76 providing,in a first trace,deflectionsgiving an indication of wire breaks detected in the rope and in a second trace the loss of metallic area. The displacement of the recordex is proportional to the displacement of the wire. The output of the analog signal conditioner is also fed to an analog to digital conversion unit and digital signal conditioner 78 providing an output to a digital printer 80 for printing the type and location of the wire breaks and periodical-ly the loss of metallic area. The outputs o cond~tioners 72 and 78 are also fed to a three channel analog FM or digital type re-corder 82 for recording the information detected by magnetic tes-ting device 70.
It is also important to note that the above disclosed testing device allows to maintain a complete history of the wire rope being tested. Indeed, even if the wire rope wears out even-ly, comparisons may be made with previous recordin~s to determinethe loss of metallic area since the previous test.
Although the invention has been disclosed with referen-ce to a preferred embodiment, it is to be understood that various , other arrangements are also envisaged within the scope of the in-vention. For example, the permanent magnet may be any assembly capable of generating magnetic poles o opposite polarity along a section of an elongated object to be tested. Similarly, the de-; tail structure of the loss of metallic area and leakage flux sen-sors could take various forms depending on the particular struc-ture of the magnet assembly and on the shape of the objects to be tested.
Various magnetic devices have been proposed for detec-ting defects in wire ropes, steel pipes and other elongated ma-gnetic objects. Such devices genexally comprise electromagnets or permanent magnets for setting up a magnetic flux in the elon-gated object to be tested and means for detecting the leakage flux generated by the external and internal defects of such ob-jects. An example og such devices is the one disclosed in U.S.
patent No. 3,~24,976 issued January 28, 1969 to M.S. Jezewski et al. These devices, however, are not well suitecl .Eo.r detecting 109s Oe metallic area due to wear, corrosion or other adverse .
conditions because these defects do not generally cause strong enough localized leakage flux.
It is therefore the object of the present invention to provide a magnetic testing device which is capable of adequately sensing loss of metallic area in elongated objects.
It is a further object of the present invention to pro-vide a magnetic testing device which has the ability to detect loss of metallic area and, at the same time, other defects which cause a leakage flux in the elongated objects being tested.
The magnetic testing device, in accordance with the in-vention, comprises a permanent magnet assembly having poles adap-ted to be spaced apart in the longitudinal direction of~the elon-gated object being tested for inducing a longitudinal magnetic flux in a section of such elongated object between the poles o the magnet assembly which is strong enough to saturate such sec-tion of the object, a tubular pole piece adapted to surround the elongated object adjacent each pole for directing the magnetic flux radially into the elongated object at one pole and out of '~ - 1 - ~
~33~3~
the elongated object a-t the other pole, Hall effect devices spaced around at least one pole piece in the path of the magnetic flux for sensing the reduction of the radial flux entering such elon-gated object due to any reduction of the cross-sectional area of the elongated object between the pole pieces caused by loss of metallic area in the elongated object, and a leakage flux sensor secured to the magnet between the pole pieces for detecting exter-nal and internal defects in the object.
Each tubular pole piece is preferably cut in two parts one of which is fixed to the magnet and the other hingedly mounted to the magnet or positioning the object to be tested.
.-; The leakage flux sensor may comprise a ~irst sellsor ring of magnetic material surrounding the elongated ob~ect, a second sensor ring o~ magnetic material concentrically mounted outside the first sensor ring and having the same axial lenght as the first sensor ring, such second sensor ring having a plurality of projections extending towards the first sensor ring with a prede-termined minimum gap between the projections and the first sensor ring for concentrating the leakage flux through the gap, a Hall effect device located at each projection for sensing the leakage flux passing through the gap, and a flux guiding member of magne-tic material connected to the second ring and extending towards the elongated object for completing the magnetic circuit of the leakage flux. The leakage flux sensor is preferably made in two parts one of which is fixed and the other hingedly connected to the magnet for positioning the object to be tested.
The magnetic testing device preferably includes means for guiding the elongated object substantially along the center line of the pole pieces and leakage flux sensor. Such guiding 3Q means may be made of polyamide material.
The pole pieces are preferably separated from the poles of the permanent magnet assembly by a piece of strong non-magnetic L~ - 2 -~3~3037 and non-conductive material, such as linen base phenolic, for in-troducing a predetermined amount of reluctance in the magnetic circuit.
The invention will now be disclosed, by way of example, with reference to the accompanying drawings in which:
Figure 1 illustrates a perspective view of the magnetic testing device in accordance with the invention;
Figure 2 illustrates an embodiment of the permanent ma-gnet used in the magnetic testing device in accordance with the invention;
Figures 3 and ~ illustrate in more details the loss of metallic area sensor o~ the testing device of Figure l;
Figures 5 and 6 illustrate in more details the flux l~a-kage sensor of the testing device o~ Pigure l;
Figures 7 to 11 show diagrams illustrating the operation of the testing device in accordance with the in~ention; and Figure 12 illustrates a block diagram of the instrumenta-tion used with the testing devi~e in accordance with the invention.
Referring to Figures l and 2, there is shown a perspecti-ve view of an embodiment of a magnetic testing device comprising aU shaped magnet assembly 10 which may be made of analuminum-nickel-cobalt alloy which is enclosed in a zinc casting 12. Thepurpose of the casting is to provide a softer material for drilling holes to attach the other elements of the testing device. The permanent ma-gnet itself is more clearly illustrated in Figure 2 and includes two north poles 13 which are separated by a semi~circular section 1~ and two south poles 15 which are also separated by a semi-circu-lar section 16. Lossof metallic area sensors 17 and 18 are placed in the above semi-circular sections 1~ and 16 respectively. A lea-3Q kage flux sensor 19 is positioned between the north and south po-les of the magnet.
Sensors 17 and 18 are more clearly illustrated in Figures Q3~7 3 and 4. Each sensor is made in two parts one of which is fixed to the magnet and the other openable for positioning the objèct being tèsted. Eachsensor half includes a semi-circular pole piece 20 which is secured inside a semi-circular member 22 of strong non-magnetic and non-conductive material, such as linen base phenolic.
Each fixed member ~2 is secured to a plate 24 itself secured to plates 26 and 28 which are in turn attached to magnet 10. Eachope-nable member 22 is fixed on an outside semi-circular casing 30 which is hinged on plate 28 by hinge 32. Inside each pole piece 20 is secured a replaceable guide 34 for guiding the elongated object along the center axis of the pole piece 20. Suchguides are made of hard plastic material such as polyamide. Ingroove 36 in pole pieces 20, there are regularly spaced ~lall effect de~ices 38. Such devices are shown in Figure 4 as being spaced ~bout 120 apart. It is to be understood that the number and accordingly the spacing o~
such Hall effect devices may vary depending on the magnitude of the signal to be detected. Theoutputs of all the Hall eEfect devices are added up by means of a summing amplifier (not shown) to detect the loss of metallic area at any location on the perimeter of the elongated object and also for compensating for slight misalignment of the object with respect to the central axis of the pole pieces.
Sensor i9 is more clearly shown in Figures 5 and 6. Such sensor is made of two parts, one of which is fixed to the magnet 10 and the other openable for positioning the object to be tested.
Each sensor half consists of a first semi-circular sensor ring 40, a second semi-circular sensor ring 42 concentrically mounted outsi-de the first sensor ring, two flux guiding members 44 one on each side of the second semi-circular ring and a semi-Gircular block of strong non-magnetic and non-conductive material 46 secured inside each flux guiding member and holding the two sensor rings at a pre-determined distance apart. Asillustrated mare clearly in Figure 6, sensor ring 42 has a number of projections 48 thereon extending to-.~
~3~ 7 wards the first sensor ring 40 leaving a predetermined minimum gap between the projections and the first sensor ring so as to concen-trate the leakage flux through the gap. A Hall e~rect device 50 is located at each projection for detecting the leakage flux passing through the gaps. The fixed sensor half is supported between the poles of the magnet 10 by means of a block of hard non-magnetic and non-conductive material 52 which is secured to the magnet 10 by means of aluminum plates 54. The fixed sensor half is secured to aluminum plate 56 which is in turn fixed to block 52. Such plates are made of aluminum so as to prevent distortion of the ma-gnetic flux pattern of the magnet. The openable sensor half is secured to a block of strong non-magnetic and non-conductive ma-terial 58 which is hinged on the magnet by hinge 60 and secured in closed position by clamping device 61. A plate oE aluminum 62 is secured to the outside portion of each op~nable guiding member 44 to prevent distortion of the magnetic flux pattern of the ma-gnet. Semi-circular guides 64 are secured to the fixed and opena-ble sensors to center the elongated object being tested. Such ~ guide may be made of polyamide material.
20 The operation of the above disclosed magnetic testingdevice will now be disclosed with reference to the schematic dia-grams illustrated in Figures 7 to 11 of the drawings. Figure 7 illustrates the magnetic flux generated by magnet 10 in the ab-sence of an elongated object within the pole pieces 20 whereas Figure 8 illustrates the magnetic flux in the presence of an elon-gated object, such as wire rope 66 It will be seen that the ma-jor part of the flux goes radially from the north pole of the ma-gnet into the wire rope, then longitudinally in the wire rope between the poles of the magnet, and radially out of the wire ro-pe at the south pole o~ the magnet. Such flux thus passes through the Hall effect devices 38 which, AS commonly known, produce an ~ ~ .
Il 37 output voltage proportional to the flux passing perpendicularly through them. The magnitude of such voltage will depend on the reluctance of the magnetic circuit and thus on the gap between the magnet and the w;re rope. Such gap will increase at the lo-cation of a loss of metallic area in the wire rope and reduce the flux passing through the wire rope. In addition, the reduced cross-section of the wire rope will also reduce the magnetic flux. The flux will be sensed at the output of the Hall effect devices. It is also very important to note that the amplitude of output signal will be substantially independent of the speed at which the wire rope is passed through the magnet since Hall ef-fect devices provide an output signal which~ is not influenced by the moving velocity of the test material within a wide range o~
velocities.
Figure 9 illustrates the leakage :elux generated due to the presence o a wire break 67. Figure 10 illustrates the out-put voltage V of the Hall effect devices 50 as a function o~ the wire break position. Such output is null when the break is right under the Hall effect devices as the leakage flux passes longitu-dinally through the Hall effect devices. However, when the breakis approaching or getting away from the location of the Hall ef-fect devices, the magnetic leakage 1ux will pass at 90 through the Hall effect devices and the magnitude o~ the voltage detected will pass through maximum and minimum values. Figure 11 shows the magnetic ~lux path 68 as the wire rope is moved through the leakage flux sensor in thè direction of arrow 70.
Figure 12 illustrates a block diagram of the instrumen tation which may ~e used with the magnetic testing device in ac-cordance with the invention. The outputs of the magnetic testing device 70 are fed to an analog signal conditioner 72. Also fed to the analog signal conditioner is the output of a defect loca-tion sensor 74 which may be in the form of a pair of rollers in ~L~3~
contact with the wire rope being tested. Such rollers may be provided with or coupled to suita~le transducers producing an output signal at regular intervals from the st~rting end of the wire being tested. The output of the analog signal conditioner is fed to a two pen analog recorder x,y/y 76 providing,in a first trace,deflectionsgiving an indication of wire breaks detected in the rope and in a second trace the loss of metallic area. The displacement of the recordex is proportional to the displacement of the wire. The output of the analog signal conditioner is also fed to an analog to digital conversion unit and digital signal conditioner 78 providing an output to a digital printer 80 for printing the type and location of the wire breaks and periodical-ly the loss of metallic area. The outputs o cond~tioners 72 and 78 are also fed to a three channel analog FM or digital type re-corder 82 for recording the information detected by magnetic tes-ting device 70.
It is also important to note that the above disclosed testing device allows to maintain a complete history of the wire rope being tested. Indeed, even if the wire rope wears out even-ly, comparisons may be made with previous recordin~s to determinethe loss of metallic area since the previous test.
Although the invention has been disclosed with referen-ce to a preferred embodiment, it is to be understood that various , other arrangements are also envisaged within the scope of the in-vention. For example, the permanent magnet may be any assembly capable of generating magnetic poles o opposite polarity along a section of an elongated object to be tested. Similarly, the de-; tail structure of the loss of metallic area and leakage flux sen-sors could take various forms depending on the particular struc-ture of the magnet assembly and on the shape of the objects to be tested.
Claims (14)
1. A magnetic testing device for detecting loss of me-tallic area and internal and external defects in elongated magne-tically permeable objects such as wire ropes and the like, the device comprising:
a) a permanent magnet assembly having poles adapted to be spaced apart in the longitudinal direction of an elongated ob-ject for inducing a longitudinal magnetic flux in a section of said object between the poles of the magnet assembly which is strong enough to saturate said section of the object;
b) a tubular pole piece adapted to surround said elon-gated object adjacent each pole of said permanent magnet assembly for directing said magnetic flux radially into the object at one pole and out of the object at the other pole;
c) Hall effect devices spaced around at least one pole piece in the path of said magnetic flux for sensing the reduction of the radial flux entering said elongated object due to any re-duction of the cross-sectional area of the elongated object bet-ween said pole pieces caused by loss of metallic area in said elongated object; and d) a leakage flux sensor secured to said magnet bet-ween the pole pieces for detecting external and internal defects in said object.
a) a permanent magnet assembly having poles adapted to be spaced apart in the longitudinal direction of an elongated ob-ject for inducing a longitudinal magnetic flux in a section of said object between the poles of the magnet assembly which is strong enough to saturate said section of the object;
b) a tubular pole piece adapted to surround said elon-gated object adjacent each pole of said permanent magnet assembly for directing said magnetic flux radially into the object at one pole and out of the object at the other pole;
c) Hall effect devices spaced around at least one pole piece in the path of said magnetic flux for sensing the reduction of the radial flux entering said elongated object due to any re-duction of the cross-sectional area of the elongated object bet-ween said pole pieces caused by loss of metallic area in said elongated object; and d) a leakage flux sensor secured to said magnet bet-ween the pole pieces for detecting external and internal defects in said object.
2. A magnetic testing device as defined in claim 1, wherein each pole piece is separated in two parts, one of which is fixed to the magnet and the other hingedly mounted to the magnet for positioning along the object to be tested.
3. A magnetic testing device as defined in claim 1, wherein said leakage flux sensor includes a first sensor ring of magnetic material surrounding said elongated object, a second sen-sor ring of magnetic material concentrically mounted outside said first sensor ring and having the same axial length as the first sensor ring, said second sensor ring having a plurality of projec-tions extending towards said first sensor ring with a predetermi-ned minimum gap between said projections and said first sensor ring for concentrating the leakage flux through said gap, a Hall effect device located at each projection for detecting the leaka-ge flux passing through said gap, and a flux guiding member of magnetic material connected to said second ring and extending to-wards said elongated object for completing the magnetic circuit of said leakage flux.
4. A magnetic testing device as defined in claim 3, wherein said leakage flux sensor is in two parts, one of which is fixed to the magnet and the other hingedly mounted to the magnet for positioning the object to be tested.
5. A magnetic testing device as defined in claim 3, further comprising guiding means located within said leakage flux sensor and substantially centered on said elongated object for guiding said elongated object substantially along the center line of said pole pieces and leakage flux sensor.
6. A magnetic testing device as defined in claim 5, wherein said guiding means are polyamide guides.
7. A magnetic testing device as defined in claim 2, wherein said permanent magnet is a U-shaped magnet and wherein the legs of said magnet have semicircular sections into which are positioned each fixed pole piece.
8. A magnetic testing device as defined in claim 7, further comprising a tubular member of strong non-magnetic and non-conductive material separating said pole pieces from the poles of said magnet for providing a predetermined amount of reluctance in the magnetic circuit.
9. A magnetic testing device as defined in claim 8, wherein said material is a linen base phenolic material.
10. A magnetic testing device as defined in claim 3, further comprising means for mounting said first ring with respect to said second ring.
11. A magnetic testing device as defined in claim 10, wherein said means for mounting said first ring with respect to said second ring comprises a tubular member of non-magnetic mate-rial separating said first sensor ring from said second sensor ring and said flux guiding member.
12. A magnetic testing device as defined in claim 1, further comprising guiding means located within said tubular pole piece and substantially centered on said elongated object for guiding said elongated object substantially along the center line of said pole piece.
13. A magnetic testing device as defined in claim 1, further comprising means for adding the outputs of said Hall ef-fect devices for compensating for slight misalignment of the ob-ject with respect to the center axis of the pole piece.
14. A magnetic testing device as defined in claim 13, wherein there are Hall effect devices spaced around both pole pieces.
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA251,932A CA1038037A (en) | 1976-05-06 | 1976-05-06 | Magnetic testing device for detecting defects in elongated objects |
| US05/728,061 US4096437A (en) | 1976-05-06 | 1976-09-30 | Magnetic testing device for detecting loss of metallic area and internal and external defects in elongated objects |
| GB17838/77A GB1539313A (en) | 1976-05-06 | 1977-04-28 | Magnetic testing devices for detecting defects in magnetically permeable elongate objects |
| FR7712997A FR2350600A1 (en) | 1976-05-06 | 1977-04-29 | MAGNETIC TESTING DEVICE TO DETECT FAULTS IN LONG OBJECTS |
| SE7705144A SE424775B (en) | 1976-05-06 | 1977-05-03 | MAGNETIC TESTING DEVICE FOR DETERMINING ERRORS IN LONG-TERM FORMAL |
| AT0317477A AT376805B (en) | 1976-05-06 | 1977-05-04 | MAGNETIC TESTING DEVICE FOR DETECTING SURFACE AND DEPTH ERRORS OF LONGER, MAGNETICALLY PERMEABLE OBJECTS, LIKE WIRE ROPES OR THE LIKE. |
| CH561077A CH615758A5 (en) | 1976-05-06 | 1977-05-05 | |
| IT23296/77A IT1084632B (en) | 1976-05-06 | 1977-05-06 | MAGNETIC TEST DEVICE TO DETECT DEFECTS ON ELONGATED OBJECTS. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA251,932A CA1038037A (en) | 1976-05-06 | 1976-05-06 | Magnetic testing device for detecting defects in elongated objects |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1038037A true CA1038037A (en) | 1978-09-05 |
Family
ID=4105885
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA251,932A Expired CA1038037A (en) | 1976-05-06 | 1976-05-06 | Magnetic testing device for detecting defects in elongated objects |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4096437A (en) |
| AT (1) | AT376805B (en) |
| CA (1) | CA1038037A (en) |
| CH (1) | CH615758A5 (en) |
| FR (1) | FR2350600A1 (en) |
| GB (1) | GB1539313A (en) |
| IT (1) | IT1084632B (en) |
| SE (1) | SE424775B (en) |
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| US4271763A (en) * | 1978-05-15 | 1981-06-09 | Berger Philip H | Proximity detector |
| NZ195142A (en) * | 1979-10-15 | 1984-09-28 | Commw Scient Ind Res Org | Monitoring integrity of longitudinal steel members in conveyor belts and cables |
| DE3017979A1 (en) * | 1980-05-10 | 1981-11-12 | Institut Dr. Friedrich Förster Prüfgerätebau, 7410 Reutlingen | METHOD AND ARRANGEMENT FOR EVALUATING AN ERROR SIGNAL VOLTAGE |
| US4518919A (en) * | 1981-01-16 | 1985-05-21 | Tokyo Shibaura Denki Kabushiki Kaisha | Detecting device for detecting a magnetic strip embedded in a sheet |
| WO1983000561A1 (en) * | 1981-07-28 | 1983-02-17 | Melgui, Mikhail, Aleksandrovich | Method and device for electromagnetic control of mechanical properties of moving ferromagnetic object |
| US4503393A (en) * | 1981-10-05 | 1985-03-05 | Exxon Production Research Co. | Method and apparatus for detecting flaws in the threaded end of an elongate member using electromagnetic excitation and an automated scanning sensor |
| US4510447A (en) * | 1981-10-26 | 1985-04-09 | Exxon Production Research Co. | Inspection apparatus for electromagnetically detecting flaws in the wall of a pipe |
| US4573013A (en) * | 1982-03-29 | 1986-02-25 | The United States Of America As Represented By The Secretary Of Transportation | Magnetic inspection of reinforcing steel rods in prestressed concrete |
| US4449411A (en) * | 1982-04-22 | 1984-05-22 | Magnetic Analysis Corporation | Magnetic and ultrasonic objects testing apparatus |
| US4546316A (en) * | 1982-07-02 | 1985-10-08 | Rotesco Limited | Magnetic testing device for supported objects |
| US4555665A (en) * | 1982-08-04 | 1985-11-26 | Pa Incorporated | Magnetic flux method for measuring tubular wall thickness |
| US4659991A (en) * | 1983-03-31 | 1987-04-21 | Ndt Technologies, Inc. | Method and apparatus for magnetically inspecting elongated objects for structural defects |
| EP0134341A1 (en) * | 1983-08-22 | 1985-03-20 | Rotesco Inc. | Magnetical testing device for supported objects |
| US4715442A (en) * | 1984-04-11 | 1987-12-29 | Pa Incorporated | Apparatus for servicing tubular strings in subterranean wells |
| US4704580A (en) * | 1984-04-11 | 1987-11-03 | Pa Incorporated | Method and apparatus for measuring the depth of local defects in ferromagnetic elements |
| US4792756A (en) * | 1984-04-11 | 1988-12-20 | Pa Incorporated | Method and apparatus for measuring axially extending defects in ferromagnetic elements |
| US4710712A (en) * | 1984-04-11 | 1987-12-01 | Pa Incorporated | Method and apparatus for measuring defects in ferromagnetic elements |
| US4636727A (en) * | 1984-04-11 | 1987-01-13 | Pa Incorporated | Method and apparatus for detecting the location of defects in tubular sections moving past a well head |
| US4629991A (en) * | 1984-04-11 | 1986-12-16 | Pa Incorporated | Methods and apparatus for detecting tubular defects having a plurality of expandable arcuate segments |
| PL148290B1 (en) * | 1985-03-05 | 1989-10-31 | Wyzsza Szkola Pedagog | Magnetic defectograph sensing element for determining changes in cross-sectional areas over substantial length of an object being examined |
| GB2173300B (en) * | 1985-04-06 | 1989-06-28 | Schaudt Maschinenbau Gmbh | Apparatus for optically monitoring the surface finish of ground workpieces |
| DE3535117C1 (en) * | 1985-10-02 | 1986-12-18 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V., 8000 München | Method and device for measuring ferromagnetic objects laid in non-magnetic materials |
| AT389945B (en) * | 1986-02-17 | 1990-02-26 | Evg Entwicklung Verwert Ges | METHOD FOR DETERMINING MEASURING PARAMETERS ON THE DESTRUCTION-FREE, MAGNET-INDUCTIVE WAY FOR THE METALLURGICAL AND / OR MECHANICAL PROPERTIES OF A MAGNETIZABLE TEST, AND DEVICE FOR EXERCISING THIS PROCESS |
| ZA871964B (en) * | 1986-03-25 | 1987-09-07 | ||
| GB2203549B (en) * | 1987-04-15 | 1991-05-01 | Julian Marsden Carroll | Metal corrosion detection |
| GB8714877D0 (en) * | 1987-06-25 | 1987-07-29 | Coal Industry Patents Ltd | Non-destructive testing device |
| DE3723360A1 (en) * | 1987-07-15 | 1989-01-26 | Nukem Gmbh | METHOD AND DEVICE FOR DESTRUCTION-FREE TESTING OF FERROMAGNETIC BODIES BY MEANS OF MAGNETIZATION |
| US5036277A (en) * | 1987-11-23 | 1991-07-30 | Crucible Societe Anonyme | Method of and apparatus for detecting cross sectional area variations in an elongate object by the non-inductive measurement of radial flux variations |
| DE9011478U1 (en) * | 1990-08-07 | 1990-12-20 | Nukem Gmbh, 8755 Alzenau, De | |
| DE9011477U1 (en) * | 1990-08-07 | 1990-12-20 | Nukem Gmbh, 8755 Alzenau, De | |
| GB2250097A (en) * | 1990-11-07 | 1992-05-27 | Anglo Amer Corp South Africa | Testing wire rope for cross section variations and other flaws |
| US5245279A (en) * | 1992-06-18 | 1993-09-14 | Niagara Mohawk Power Corporation | Apparatus and method including flux injector pole position sensors for detecting physical flaws in ferromagnetic objects |
| US5565771A (en) * | 1995-01-18 | 1996-10-15 | Noranda, Inc. | Apparatus for increasing linear resolution of electromagnetic wire rope testing |
| US6057684A (en) * | 1995-10-31 | 2000-05-02 | Yoshihiro Murakami | Magnetic flaw detection apparatus using an E-shaped magnetic sensor and high-pass filter |
| US5828213A (en) * | 1996-10-21 | 1998-10-27 | Hickman; Jack R. | Method and apparatus for magnetically sampling the uniformity of an elongate object |
| US6133731A (en) * | 1996-11-07 | 2000-10-17 | Case Technologies Ltd. | Method and apparatus for the on-line measurement of the strength of metal cables |
| US5804964A (en) * | 1996-11-29 | 1998-09-08 | Noranda Inc. | Wire rope damage index monitoring device |
| US6633159B1 (en) * | 1999-03-29 | 2003-10-14 | Otis Elevator Company | Method and apparatus for magnetic detection of degradation of jacketed elevator rope |
| US6100810A (en) * | 1999-09-24 | 2000-08-08 | Koorsen; John R. | Sensing apparatus for controlling the assembly of rafters by monitoring the position metallic fasteners |
| GB0005945D0 (en) * | 2000-03-14 | 2000-05-03 | British Nuclear Fuels Plc | Improvements in and relating to investigating current |
| GB0005946D0 (en) * | 2000-03-14 | 2000-05-03 | British Nuclear Fuels Plc | Improvements in and relating to investigating corrosion |
| AU2001273765A1 (en) * | 2000-07-13 | 2002-01-30 | Eidgenossische Materialprufungs- Und Forschungsanstalt Empa | Method and device for the non-destructive examination of steel cables in anchorages |
| US6982563B2 (en) | 2000-11-09 | 2006-01-03 | British Nuclear Fuels Plc | Monitoring of corrosion induced loss of material by means of a plurality of electrical resistance measurements (field signature method, electrical resistance tomography) |
| US6990384B2 (en) | 2001-10-09 | 2006-01-24 | Laharco, Inc. | Truss plate detector |
| US6720873B1 (en) * | 2003-03-03 | 2004-04-13 | Brett D. Tressler | Method and apparatus for testing magnetic proximity detectors on ski lifts |
| US7795864B2 (en) * | 2005-03-11 | 2010-09-14 | Baker Hughes Incorporated | Apparatus and method of using multi-component measurements for casing evaluation |
| EP1869478B1 (en) * | 2005-04-08 | 2017-03-01 | Nxp B.V. | Multi-axis accelerometer with magnetic field detectors |
| US20070222438A1 (en) * | 2006-03-23 | 2007-09-27 | Dale Reeves | Electromagnetic flaw detection apparatus for inspection of a tubular |
| KR101154593B1 (en) * | 2007-01-31 | 2012-06-08 | 미쓰비시덴키 가부시키가이샤 | Exciting magnet manufacturing apparatus |
| DE112007003707T5 (en) * | 2007-11-13 | 2010-09-23 | Mitsubishi Electric Corp. | Cable tester |
| US7719266B1 (en) * | 2008-02-29 | 2010-05-18 | Mehrooz Zamanzadeh | Non-destructive testing apparatus for the detection of corrosion |
| JP5035729B2 (en) * | 2008-04-28 | 2012-09-26 | 国立大学法人京都大学 | Tension measuring device |
| US8368395B2 (en) * | 2008-12-17 | 2013-02-05 | Ndt Technologies, Inc. | Magnetic inspection device and method for detecting loss in metallic cross section |
| USH2278H1 (en) * | 2011-03-02 | 2013-07-02 | The United States Of America, As Represented By The Secretary Of The Navy | Onboard data recorder for a nondestructive test wire rope sensor head |
| WO2013023818A1 (en) | 2011-08-18 | 2013-02-21 | Nv Bekaert Sa | Magnetic flux leakage error detection in cords |
| US9651357B1 (en) | 2013-02-07 | 2017-05-16 | University Of South Florida | Systems and methods for determining strand position in a post-tensioned tendon |
| FR3009076B1 (en) * | 2013-07-26 | 2017-03-31 | Michelin & Cie | SYSTEM FOR MEASURING THE THICKNESS OF A GUM LAYER OF A TIRE |
| FI126173B (en) | 2013-11-12 | 2016-07-29 | Konecranes Global Oy | Monitoring the condition of an elongated ferrous object having a longitudinal axis |
| US20170299666A1 (en) * | 2014-11-17 | 2017-10-19 | Halliburton Energy Services, Inc. | Rapid Magnetic Hotspot Detector |
| CN104458895A (en) * | 2014-12-08 | 2015-03-25 | 清华大学 | Three-dimensional pipeline leakage flux imaging detection method and system |
| FR3034201B1 (en) * | 2015-03-25 | 2019-04-19 | Soletanche Freyssinet | METHOD FOR DETECTING A FAULT IN A METAL WIRE OF A SET OF METAL WIRES, ESPECIALLY FOR AN ANCHOR AREA OF A CIVIL ENGINEERING STRUCTURE |
| US10465509B2 (en) | 2016-10-12 | 2019-11-05 | Baker Hughes, A Ge Company, Llc | Collocated multitone acoustic beam and electromagnetic flux leakage evaluation downhole |
| CN109100415A (en) * | 2018-09-03 | 2018-12-28 | 中国石油大学(北京) | The non-destructive testing device of pipe insulating layer can be penetrated |
| US11493319B2 (en) | 2021-03-10 | 2022-11-08 | Roger Dale REEVES | Electromagnetic multifunction inspection apparatus |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3271664A (en) * | 1961-12-04 | 1966-09-06 | Magnaflux Corp | Combined leakage field and eddy current detection system |
| GB1056765A (en) * | 1962-09-15 | 1967-01-25 | Akademia Gorniczo Hutnicza Dzi | A magnetic crack detection device for examining elongated objects such as ropes, rodsand steel pipes |
| US3284701A (en) * | 1962-09-28 | 1966-11-08 | Camco Inc | Magnetic testing apparatus for measuring internal diameter and surface variations in wall casing |
| US3315154A (en) * | 1965-01-18 | 1967-04-18 | United Gas Corp | Method and apparatus for determining the wall thickness of metallic elements utilizing a reciprocal permanent magnet assembly |
| US3443211A (en) * | 1965-04-01 | 1969-05-06 | American Mach & Foundry | Magnetometer inspection apparatus for ferromagnetic objects |
| US3361962A (en) * | 1966-12-19 | 1968-01-02 | Indiana General Corp | Metal detector with adjustable frame assembly |
| US3529236A (en) * | 1967-11-03 | 1970-09-15 | American Mach & Foundry | Magnetic flux sensors having core structure of generally closed configuration for use in nondestructive testing |
| GB1261346A (en) * | 1968-03-13 | 1972-01-26 | Atomic Energy Authority Uk | Improvements in or relating to the detection of magnetic discontinuities |
| US3710236A (en) * | 1970-11-30 | 1973-01-09 | Youngstown Sheet And Tube Co | Magnetic leakage field flaw detector utilizing partially overlapping hall probes |
| US3843923A (en) * | 1973-07-05 | 1974-10-22 | Stewart & Stevenson Inc Jim | Well pipe joint locator using a ring magnet and two sets of hall detectors surrounding the pipe |
-
1976
- 1976-05-06 CA CA251,932A patent/CA1038037A/en not_active Expired
- 1976-09-30 US US05/728,061 patent/US4096437A/en not_active Expired - Lifetime
-
1977
- 1977-04-28 GB GB17838/77A patent/GB1539313A/en not_active Expired
- 1977-04-29 FR FR7712997A patent/FR2350600A1/en active Granted
- 1977-05-03 SE SE7705144A patent/SE424775B/en not_active IP Right Cessation
- 1977-05-04 AT AT0317477A patent/AT376805B/en not_active IP Right Cessation
- 1977-05-05 CH CH561077A patent/CH615758A5/de not_active IP Right Cessation
- 1977-05-06 IT IT23296/77A patent/IT1084632B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| SE7705144L (en) | 1977-11-07 |
| ATA317477A (en) | 1984-05-15 |
| GB1539313A (en) | 1979-01-31 |
| CH615758A5 (en) | 1980-02-15 |
| FR2350600B1 (en) | 1981-02-27 |
| FR2350600A1 (en) | 1977-12-02 |
| SE424775B (en) | 1982-08-09 |
| AT376805B (en) | 1985-01-10 |
| US4096437A (en) | 1978-06-20 |
| IT1084632B (en) | 1985-05-25 |
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