INSPECTION APPARATUS AND METHOD

• US 20100207620A1
• Filed: 10/16/2007
• Published: 08/19/2010
• Est. Priority Date: 10/17/2006
• Status: Active Grant

• Current Assignee: Athena Industrial Technologies, Inc.
• Original Assignee: Athena Industrial Technologies, Inc.
• Inventors: Gies, Paul D.
• Granted Patent: US 8,274,279 B2
• Time in Patent Office: Days
• US Class Current: 324/240
• CPC Class Codes: G01N 27/9006 Details, e.g. in the structure or functioning of sensors

Abstract

An apparatus and method are disclosed for detecting flaws in electrically conductive materials by observing properties of the back-EMF of the eddy current field generated by driving magnetic flux through the object to be examined. The input signal may include sweeps at several frequencies, and may do so at one time under the principle of wave superposition. The sectorial observations of eddy currents summations may be compared to a known datum for a defect free material, the presence of anomalies in eddy field back EMF divergence tending to provide an indication of an irregularity in the underlying eddy field, and hence in the underlying material itself. The portable unit may have a number of different configurations depending on the nature of the object to be examined, be it a flat or large radius plate, a flange, a rail, or some other structural element.

Claims

1-40. -40. (canceled)

41. An anomaly detection apparatus for placement next to an electrically conductive object, said apparatus comprising:

an electromagnetic field emitting member,

a power source connected to said electromagnetic field emitting member, said power source being operable to drive said electromagnetic field emitting member to emit a time varying electromagnetic field;

said power source having at least first and second driving frequencies;

an array of electromagnetic field sensing members, the members of said array being mounted adjacent to said electromagnetic field emitting member;

said array including at least first and second field sensing members, said first and second field sensing members being oriented toward non-coincident regions adjacent to said field emitting member, at least said first member being non-concentric with said field emitting member;

monitoring circuitry connected to the members of said array, said monitoring circuitry being operable to observe differential variation of signals as between members of said array; and

a processor operable to compare signals sensed at said members of said array in response to electromagnetic signals emitted at said first frequency and at said second frequency.

42. A portable anomaly detection apparatus for inspecting an electrically conductive object, the apparatus comprising:

an electromagnetic field emitter operable to pass a time varying magnetic flux field through at least a portion of the electrically conductive object, and thereby to generate an electrical eddy current field in the electrically conductive object;

eddy current monitoring circuitry operable to survey at least first and second portions of the eddy current field, the first and second portions being non-coterminous; and

signal processing apparatus connected to said eddy current monitoring circuitry, said signal processing apparatus being operable to compare data received from said eddy current monitoring circuitry observed at said first and second portions of the eddy current field.

43. A mobile anomaly detector operable to survey an electrically conductive object, said detector comprising:

a shoe, said shoe having a sole for engagement with the object;

an electromagnetic field emitter mounted within said shoe;

a power source connected to drive said emitter, said power source being operable at a plurality of frequencies;

said emitter being operable to induce an eddy current field in the object when said sole is placed adjacent thereto;

a plurality of eddy current sensors arrayed adjacent said electromagnetic field emitter, members of said plurality of eddy current sensors being operable to monitor back EMF from different portions of the eddy current field;

at least one of (a) a recorder operable to store recording data from said current sensors for subsequent signal processing operations; and

(b) a processor operable to interpret data obtained from said eddy current sensors.

44. The anomaly detector of claim 43 wherein said sole has a profile constraining said detector to a single degree of freedom in translation, and one of:

(a) said anomaly detector includes a plurality of said emitters;

(b) said anomaly detector includes a plurality of said emitters, and said sole has a profile conforming to a rail road track rail; and

(c) said anomaly detector includes a plurality of said emitters, and said plurality of emitters includes at least a first emitter and a second emitter, said emitters being movable relative to one another to permit said detector to girdle the object.

45. A hand portable eddy field anomaly detector comprising:

a magnetic field emitter operable to induce an eddy current field in an adjacent electrically conductive object to be examined;

sensing apparatus operable, while said detector is in one location, to sample at first and second sensing regions, back EMF of the eddy current field;

said first region being different from said second region;

at least one of

(a) a recorder operable to store data observed with respect to said first and second regions; and

(b) a signal processor operable to compare at least one of

(i) data observed with respect to said first region and data observed with respect to said second region; and

(ii) data observed with respect to at least one of said first and second regions and a reference datum; and

said first and second regions satisfying at least one condition selected from the set of conditions consisting of

(a) said first region includes at least a portion not covered by said second region, and said first and second regions are non-concentric;

(b) said first region includes at least a portion not covered by said second region, and said second region includes at least another portion not covered by said first region; and

(c) said first and second footprints are non-concentric and at least one of said first and second regions is eccentric relative to said magnetic field emitter.

46. The eddy field anomaly detector of claim 45 wherein said sensing apparatus includes at least one of:

(a) an array of discrete sensors each having a different footprint;

(b) an array of discrete sensors each having a different footprint, said array of discrete sensors extending in a substantially annular pattern;

(c) an array of discrete sensors each having a different footprint, said array of discrete sensors including a plurality of said discrete sensors defining segments of a substantially annular footprint;

(d) an array of discrete sensors each having a different footprint, and said array of discrete sensors includes a plurality of said discrete sensors defining n segments about a central axis, said n segments being spaced on an angular pitch of 360/n degrees about said central axis;

(e) an array of discrete sensors each having a different footprint, and said array of discrete sensors includes a plurality of said discrete sensors defining n segments about a central axis, said n segments each subtending an angular arc of n/360 degrees +/−

20%;

(f) a movable sensor locatable in a plurality of different sampling positions while said detector remains in one place; and

(g) a movable sensor locatable in a plurality of different sampling positions while said detector remains in one place, said emitter includes a magnetically permeable core having a centerline axis, and said movable sensor is angularly displaceable on an arc centered on said centerline axis.

47. The eddy current field anomaly detector of claim 45 wherein said detector includes one of:

(a) a magnetically permeable core having a pole piece and a co-operating peripheral wall spaced from said pole piece;

(b) a magnetically permeable core having a pole piece and a co-operating peripheral wall spaced from said pole piece, and said detector has a foot for placement against an object to be examined, and said foot is selected from the set of feet consisting of

(i) a substantially planar base;

(ii) a chamfered base;

(iii) a chamfered base that includes a first portion and a second portion, each of the first and second portions of said foot including members of said sensing apparatus, and said first and second portions lying to either side of said chamfer;

(iv) a base having a contoured profile;

(v) a base having a profile defining a portion of a cylindrical surface; and

(vii) a base having a profile defining a portion of a circular cylindrical surface.

48. The eddy current anomaly detector of claim 45 comprising a hand held sensing module for passing next to an object to be examined, and a display, and one of:

(a) a processor operable to present anomaly identification indicia on said display;

(b) a processor operable to present anomaly identification indicia on said display, and said display includes an anomaly depth indicator;

(c) a processor operable to present anomaly identification indicia on said display, and said display includes an anomaly position indicator; and

(d) a processor operable to present anomaly identification indicia on said display, and said display includes an anomaly direction indicator.

49. The eddy current anomaly detector of claim 45 further comprising any of:

a photographic recording medium;

an audio recording medium;

telemetry apparatus; and

incremental change of position apparatus.

50. The eddy current anomaly detector of claim 45 wherein said apparatus comprises a chassis having a carrying handle, a power supply mounted to the chassis, a display mounted to the chassis, and a removable hand sensor.

51. The eddy field anomaly detector of claim 45 further comprising any one of:

(a) a controller operable to drive said emitter at more than one frequency.

(b) a controller operable to drive said emitter at more than one frequency, said controller being operable to drive said emitter at a plurality of frequencies simultaneously.

52. The eddy field anomaly detector of claim 45 wherein said apparatus includes any of:

(a) a sensor mounted to measure total emitted magnetic flux from said emitter;

(b) a sensor located to monitor total eddy current back EMF; and

(c) a sensor mounted to measure total emitted magnetic flux from said emitter, a further sensor located to monitor total eddy current back-EMF; and

a processor operable to compare total emitted magnetic flux to total eddy current back EMF.

53. The eddy current anomaly detector of claim 45 wherein one of:

(a) said detector weighs up to 20 lbs.; and

(b) said detector has a sensing module for passing next to an object to be examined, and said sensing module weighs up to 5 lbs.

54. A method of detecting anomalies in an electrically conductive object, said method comprising the steps of:

establishing a time varying eddy current field in the electrically conductive object;

monitoring at least first and second regions of the eddy current field, the first and second regions being non-coterminous and non-concentric; and

comparing at least one of

(a) eddy currents monitored in said first region with eddy currents monitored in said second region; and

(b) eddy currents monitored in both said first region and said second region with a reference standard for said first region and said second region respectively.

55. The method of claim 54 wherein said method includes one of

(a) monitoring total eddy current flux through a zone to be examined, and comparing that total eddy current flux to a sum of eddy current fluxes observed in discrete portions of said zone;

and

(b) employing a magnetic flux emitting apparatus to establish said time varying eddy current field;

monitoring total eddy current flux through a zone adjacent to the object to be examined, and comparing that total eddy current flux with a measured total emitted flux from the flux emitting apparatus.

56. A process of detection of anomalies in an electrically conductive plate, said process comprising:

providing an anomaly detection apparatus having

an electromagnetic field emitting member,

a power source connected for powering said electromagnetic field emitting member,

said power source being operable to cause said electromagnetic field emitting member to emit a time varying electromagnetic field;

said power source having at least a first frequency and a second frequency;

an array of electromagnetic field sensing members, the members of said array being mounted adjacent to said electromagnetic field emitting member;

monitoring circuitry connected to the members of said array, said monitoring circuitry being operable to sense differential variation of signals as between members of said array; and

a processor operable to compare signals sensed at said members of said array in response to electromagnetic signals emitted at said first frequency and at said second frequency;

passing said anomaly detection apparatus adjacent to the electrically conductive plate;

emitting electromagnetic field signals at more than one frequency from said electromagnetic field emitter to cause eddy currents to be generated in the electrically conductive plate;

monitoring the eddy currents at a plurality of positions; and

comparing data monitored at the plurality of positions and at the different frequencies to provide an indication of the location of an anomaly in the plate.