US4234848A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Test head for inductive surface testing having plural resonant coils held in conductive holder
Assignee: SKF GmbH
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Filing: 1978-05-24
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Granted: 1980-11-18
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Expires: 1998-05-24
Abstract
Abstract A test head for the inductive surface testing of metallic workpieces is provided with eddy-current probes respectively disposed in a plurality of holes in a holder. Each eddy-current probe is part of an individual resonant circuit and formed of coil with a ferrite core, the axis of the coil extending substantially at right angles to the workpiece surface. The holder comprises an electrically or magnetically conductive material, thereby increasing the area over which the field of each said probe is effective.
Inventors
- 👤 Rudolf Diem
- 👤 Hans-Jurgen Hentrich
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:03
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/72; G01N27/82; G01N27/90; G01N27/9006
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
153 words
A test head for the inductive surface testing of metallic workpieces brought into proximity with said test head for areal scanning of the surface of such workpieces, comprising a holder of an electrically conductive material, a plurality of parallel spaced holes extending through said holder, a plurality of resonant circuits each including a coil having a ferrite core and each of said plurality of resonant circuits being mounted in each of said holes and coaxially therewith so that the axes of said coils extend at right angles to the workpiece surface, whereby the resonant frequencies are increased, thereby increasing sensitivity of said testing, the distance between adjacent said holes in said holder being less than the diameter of each said ferrite core so that the magnetic field built up under the test head loses little in intensity between adjacent holes, thereby maximizing accuracy in indicating longitudinal and transverse flaws of the workpiece surface.
Claim 2
Dependent Claim
153 words
A test head for the inductive surface testing of metallic workpieces brought into proximity with said test head for areal scanning of the surface of such workpieces, comprising a holder of an electrically conductive material, a plurality of parallel spaced holes extending through said holder, a plurality of resonant circuits each including a coil having a ferrite core and each of said plurality of resonant circuits being mounted in each of said holes and coaxially therewith so that the axes of said coils extend at right angles to the workpiece surface, whereby the resonant frequencies are increased, thereby increasing sensitivity of said testing, the distance between adjacent said holes in said holder being less than the diameter of each said ferrite core so that the magnetic field built up under the test head loses little in intensity between adjacent holes, thereby maximizing accuracy in indicating longitudinal and transverse flaws of the workpiece surface.
Claim 3
Dependent Claim
13 words
The test head of claim l, wherein said holder is made of brass.
Claim 4
Dependent Claim
16 words
The test head of claim 1, wherein said holder is made of an antifriction bearing steel.
Claim 5
Dependent Claim
31 words
The test head of claim 1, wherein the ends of said ferrite cores facing said workpiece, and the front of said holder facing said workpiece, are disposed in a common plane.
Claim 6
Dependent Claim
28 words
The test head of claim 1, said holder being provided adjacent said eddy-current probes, with slot like notches extending at right angles to said surface of said workpiece.
Claim 7
Dependent Claim
25 words
A test head as defined in claim 5, wherein said notches extend in the direction of movement of said workpiece surface relative to the holder.
Claim 8
Dependent Claim
20 words
A test head as defined in claim 5, wherein said notches merge into the respective holes accommodating the eddy-current probes.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-11-18 | 1984-05-19 | 1984-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-11-18 | 1988-05-19 | 1988-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-11-18 | 1992-05-19 | 1992-11-18 | $7700.00 | Window Closed / Lapsed |