US3617874A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic leakage field flaw detector utilizing two ring core sensors
Assignee: Individual
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Filing: 1970-04-13
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Granted: 1971-11-02
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Expires: 1990-04-13
Abstract
Abstract This invention is concerned with magnetic flaw detection. A magnetic field is impressed upon a workpiece, which field is distorted in the region of a flaw. The flaw detector employed consists of a ring core of magnetic material. An energizing coil is wound upon the core to create a magnetic field totally within the core. A pickup winding is wound diametrically about said core. When the core is scanned across the workpiece the core intercepts the leakage field of the flaw. The interaction of the leakage field and the energized field in the core create an output signed on the pickup winding. Two cores can be used together to yield a signal indicative of the gradient of the stray field.
Inventors
- 👤 Friedrick M O Forster
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 04:33
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/72; G01N27/82
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
236 words
A nondestructive testing system for locating a discontinuity in a workpiece, said system including the combination of magnetic means for magnetizing said workpiece and producing a stray magnetic field adjacent the surface thereof in the area of said discontinuity, a search unit for being positioned adjacent the surface of the workpiece for scanning across said surface and through at least a portion of said stray field, a pair of juxtaposed magnetic cores in said search unit, scan means coupled to said search unit for scanning said search unit across the surface of said workpiece whereby said cores pass through said stray fields, each of said cores forming a closed circular magnetic path with a high permeability and a low saturation whereby at least a portion of said stray field extend through at least a portion of each of said cores, a primary winding on each of said cores for producing a flux field that extends therearound and combines with the separate resultant fields in each of said sides, a signal generator coupled to said primary windings for circulating driving currents through said winding, a secondary winding on each of said cores coupled to said sides and responsive to the separate resultant fields to thereby produce an output signal whenever said core passes through a stray field, and said cores being positioned so that said output signal is a function of the gradient of said stray field.
Claim 2
Dependent Claim
236 words
A nondestructive testing system for locating a discontinuity in a workpiece, said system including the combination of magnetic means for magnetizing said workpiece and producing a stray magnetic field adjacent the surface thereof in the area of said discontinuity, a search unit for being positioned adjacent the surface of the workpiece for scanning across said surface and through at least a portion of said stray field, a pair of juxtaposed magnetic cores in said search unit, scan means coupled to said search unit for scanning said search unit across the surface of said workpiece whereby said cores pass through said stray fields, each of said cores forming a closed circular magnetic path with a high permeability and a low saturation whereby at least a portion of said stray field extend through at least a portion of each of said cores, a primary winding on each of said cores for producing a flux field that extends therearound and combines with the separate resultant fields in each of said sides, a signal generator coupled to said primary windings for circulating driving currents through said winding, a secondary winding on each of said cores coupled to said sides and responsive to the separate resultant fields to thereby produce an output signal whenever said core passes through a stray field, and said cores being positioned so that said output signal is a function of the gradient of said stray field.
Claim 3
Dependent Claim
38 words
The nondestructive testing system of claim 1 wherein said cores are aligned and spaced in a direction normal to the surface of the workpiece whereby the output signal is a function of the field gradient in said direction.
Claim 4
Dependent Claim
33 words
The nondestructive testing system of claim 1 wherein said cores are aligned and spaced in the direction of said scan whereby the output signal is a function of the gradient in that direction.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-11-01 | 1975-05-03 | 1975-11-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-11-01 | 1979-05-03 | 1979-11-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-11-01 | 1983-05-03 | 1983-11-02 | $7700.00 | Window Closed / Lapsed |