US3694740A
Expired / Lapsed
US
⏱️ 0.0 years remaining
System for the magnetic non-destructive testing of materials for long and short defects
Assignee: ESSEM METOTEST AB
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Filing: 1971-01-19
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Granted: 1972-09-26
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Expires: 1991-01-19
Abstract
Abstract A system for electroinductively testing elongated products comprising; a coil system for detecting short defects as seen in the longitudinal direction of the product and inducing a magnetic field in the product to be tested; and a sensing means, e.g. including induction coils, Hall elements or the like, rotating around the product and cooperating with said magnetic field for detecting long defects as seen in the longitudinal direction of the product.
Inventors
- 👤 Karl Gunnar Bergstrand
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 05:11
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/72; G01N27/82; G01N27/90; G01N27/9013; G01N27/902; G01N27/904; G01N27/9046
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
178 words
A system for electroinductively testing the quality of elongated products having a practically constant cross section, said system for the purpose of detecting relatively short defects in the sample in the longitudinal direction thereof and also relatively extended defects in the longitudinal direction thereof comprising; two coils extending co-axially about the sample and spaced longitudinally thereof and being non-rotatable relative to said sample being tested, said sample being longitudinally movable relative to said coils; an AC current source feeding said coils and inducing an electromagnetic field therein, and eddy currents being induced in said sample, said coils being connected in a bridge arrangement adapted to, upon passing short defects, indicate said defects as unbalances in the bridge arrangement; sensing means rotatable relative to said coils and about the sample for detecting relatively extended defects in the sample; and means for rotating the sensing means around the sample, said sensing means being cooperative with the electromagnetic field generated by the coils and sensing variations in the field caused by an extended defect in the sample and indicating said defect.
Claim 2
Independent Claim
178 words
A system for electroinductively testing the quality of elongated products having a practically constant cross section, said system for the purpose of detecting relatively short defects in the sample in the longitudinal direction thereof and also relatively extended defects in the longitudinal direction thereof comprising; two coils extending co-axially about the sample and spaced longitudinally thereof and being non-rotatable relative to said sample being tested, said sample being longitudinally movable relative to said coils; an AC current source feeding said coils and inducing an electromagnetic field therein, and eddy currents being induced in said sample, said coils being connected in a bridge arrangement adapted to, upon passing short defects, indicate said defects as unbalances in the bridge arrangement; sensing means rotatable relative to said coils and about the sample for detecting relatively extended defects in the sample; and means for rotating the sensing means around the sample, said sensing means being cooperative with the electromagnetic field generated by the coils and sensing variations in the field caused by an extended defect in the sample and indicating said defect.
Claim 3
Dependent Claim
28 words
A system according to claim 1, characterized in that the sensing means is positioned externally of the two coils, when seen in the longitudinal direction of the sample.
Claim 4
Dependent Claim
37 words
A system according to claim 1, characterized in that said sensing means is rotatable relative to said sample, said sensing means being in spaced relationship with said sample during at least the major portion of rotation thereabout.
Claim 5
Dependent Claim
27 words
A system according to claim 1, characterized in that the sensing means comprises two induction coils offset in relation to each other in the direction of rotation.
Claim 6
Dependent Claim
28 words
A system according to claim 1, characterized in that the sensing means comprises two Hall effect elements offset in relation to each other in the direction of rotation.
Claim 7
Dependent Claim
34 words
A system according to claim 4, characterized in that the signals from the units offset in relation to each other and incorporated in the sensing means are connected so as to counteract each other.
Claim 8
Dependent Claim
25 words
A system according to claim 6, characterized in that the output signals from the bridge arrangement and sensing means are connected to a differential amplifier.
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) | 1975-09-26 | 1976-03-27 | 1976-09-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-26 | 1980-03-27 | 1980-09-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-26 | 1984-03-27 | 1984-09-26 | $7700.00 | Window Closed / Lapsed |