US3603874A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Eddy current inspection device for elongated material with means to eliminate the end effect
Assignee: United States Steel Corp
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Filing: 1969-06-09
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Granted: 1971-09-07
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Expires: 1989-06-09
Abstract
Abstract A control circuit for eddy current inspection of moving lengths of steel pipe has continuously energized primary encircling coils inducing eddy currents in the pipe. When a length of pipe enters the two encircling sensing coils, which detect differences in eddy currents as material discontinuities, the first sensing signals are attenuated. A defect-marking system, which marks according to the location of sensed material discontinuities, excludes the signals resulting from the entrance and exit of the pipe through the coils.
Inventors
- 👤 William L Posey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 10:05
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/72; G01N27/82; G01N27/90; G01N27/9046; G01N27/9006; G01N27/9093
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
208 words
In apparatus for the nondestructive eddy current inspection of elongated ferromagnetic material including an enerGized primary encircling coil through which lengths of material pass with eddy currents being induced in the material, two spacedapart encircling sensing coils through which said lengths of material pass whereby said sensing coils sense differences in eddy currents as material discontinuities caused by material defects and the material ends pass through the sensing coils, an indicator and means connected to said sensing coils and responsive to said differences for providing a signal to said indicator; an improved control circuit comprising means adjacent said encircling coils for detecting the presence of said material prior to the entrance of said material into said encircling coils and generating a signal indicative of said presence, and means connected to said detecting means and said signal providing means and responsive to the signal indicative of the entrance end of a length of material passing said detecting means and also responsive to the signal caused by said end entering said sensing coils and the combined reception of said signals for disconnecting the signal providing means from said indicator for only the next subsequent sensing of the sensing coils after the entrance end has been detected by said detecting means.
Claim 2
Dependent Claim
208 words
In apparatus for the nondestructive eddy current inspection of elongated ferromagnetic material including an enerGized primary encircling coil through which lengths of material pass with eddy currents being induced in the material, two spacedapart encircling sensing coils through which said lengths of material pass whereby said sensing coils sense differences in eddy currents as material discontinuities caused by material defects and the material ends pass through the sensing coils, an indicator and means connected to said sensing coils and responsive to said differences for providing a signal to said indicator; an improved control circuit comprising means adjacent said encircling coils for detecting the presence of said material prior to the entrance of said material into said encircling coils and generating a signal indicative of said presence, and means connected to said detecting means and said signal providing means and responsive to the signal indicative of the entrance end of a length of material passing said detecting means and also responsive to the signal caused by said end entering said sensing coils and the combined reception of said signals for disconnecting the signal providing means from said indicator for only the next subsequent sensing of the sensing coils after the entrance end has been detected by said detecting means.
Claim 3
Dependent Claim
67 words
Apparatus according to claim 1 which includes means connected to said detecting means and said signal providing means and responsive to the signal generated by the exit end of a length of material passing said detecting means for disconnecting the signal providing means from said indicator for only the next subsequent sensing of the sensing coils after said exit end has been detected by said detecting means.
Claim 4
Dependent Claim
29 words
Apparatus according to claim 2 which includes means connected to said signal providing means for providing only a single signal when said coils sense an end of tubular material.
Claim 5
Dependent Claim
43 words
Apparatus according to claim 2 which includes means connected to said detecting means and responsive to the entrance end of a length of material passing said detecting means for diminishing the magnitude of only the next subsequent single sensing of each sensing coil.
Claim 6
Dependent Claim
36 words
Apparatus according to claim 4 in which the means for diminishing the magnitude of only the next subsequent single sensing of each sensing coil includes circuit means connected to said sensing coils for clipping said sensings.
Claim 7
Dependent Claim
67 words
Apparatus according to claim 4 in which the means for diminishing the magnitude of said sensings includes a first resistance, a second resistance, means for connecting the first resistance to one sensing coil and the second resistance to the other sensing coil before material enters the sensing coils, and means responsive to the end of said sensings for disconnecting said resistance whereby said resistances attenuate said sensings.
Claim 8
Dependent Claim
46 words
Apparatus according to claim 6 which includes means connected to said signal providing means and spaced from said coils adjacent the travel path of said lengths of material for placing a longitudinal mark on said length centered on the location on which the differences were sensed.
Claim 9
Dependent Claim
40 words
Apparatus according to claim 7 which includes means connected to said signal providing means for disconnecting the signal providing means from the marking means upon the occurrence of each subsequent sensing while a mark is being placed on said material.
Claim 10
Dependent Claim
56 words
Apparatus according to claim 8 which includes means for extending the length of said mark a distance equal to the spacing between said sensing coils and the center of said marking means upon the subsequent occurrence of a sensing occurring during the time from the occurrence of a sensing to the completion of its associated mark.
Claim 11
Dependent Claim
87 words
Apparatus according to claim 9 which includes means responsive to the signal resulting from the entrance end of a length of material passing through the sensing coils for marking the entrance end of said length of material with a longitudinal mark, an indicating lamp, a power source, means responsive to the marking of a length of material for connecting said power source to said indicating lamp, a counter, and manual reset means to disconnect said lamp from said power source and record a count in said counter.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-06 | 1975-03-08 | 1975-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-06 | 1979-03-08 | 1979-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-06 | 1983-03-08 | 1983-09-07 | $7700.00 | Window Closed / Lapsed |