US3579099A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Improved flaw detection apparatus using specially located hall detector elements
Assignee: Individual
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Filing: 1969-06-05
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Granted: 1971-05-18
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Expires: 1989-06-05
Abstract
Abstract A pair of Hall generator elements are symmetrically mounted in the same magnetic plane closely adjacent a material surface of substantially circular cross section, one Hall generator element being mounted on each side of a null plane, to detect the variations in leakage flux emanating from the material surface as the material is spirally rotated past the Hall generator elements. The Hall generator elements are symmetrically mounted on an axis intersecting a line parallel to the longitudinal axis of the material by approximately 5* and a control current provided to each Hall generator element of the same magnitude but different polarity. The Hall generator elements are, alternately, mounted astride the null plane to be substantially nearly aligned with the null plane and the control current to each Hall generator element is of the same magnitude and polarity.
Inventors
- 👤 Takayuki Kanbayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 21:33
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/72; G01N27/82; G01N27/90
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
217 words
Magnetic detection apparatus for detecting flaws in a material, comprising; means for magnetizing the surface of a material of substantially circular cross section with an alternating magnetic flux, said flux being directed transverse to the longitudinal axis of the material, means for spirally rotating the material along its longitudinal axis to expose the entire surface of the material to the magnetizing means, said means for magnetizing the surface causing said magnetic field to have a zero component in a null plane transverse to said field direction and parallel to the longitudinal axis of the material, a pair of Hall generator elements for detecting the leakage flux emanating from a flaw in said material, said Hall generator elements lying adjacent the material surface in a plane parallel to the direction of the magnetic field with the centers of said Hall elements lying on an axis which intersects a line parallel to the longitudinal axis of the material at an angle of substantially 5*, means for adjusting the Hall elements in the direction of the magnetic field so that they are symmetrically mounted one on each side of the null plane, means for detecting the signal outputs from each of said Hall generating elements being differentially connected to the detecting means to eliminate noise and enhance the signal-tonoise ratio.
Claim 2
Dependent Claim
217 words
Magnetic detection apparatus for detecting flaws in a material, comprising; means for magnetizing the surface of a material of substantially circular cross section with an alternating magnetic flux, said flux being directed transverse to the longitudinal axis of the material, means for spirally rotating the material along its longitudinal axis to expose the entire surface of the material to the magnetizing means, said means for magnetizing the surface causing said magnetic field to have a zero component in a null plane transverse to said field direction and parallel to the longitudinal axis of the material, a pair of Hall generator elements for detecting the leakage flux emanating from a flaw in said material, said Hall generator elements lying adjacent the material surface in a plane parallel to the direction of the magnetic field with the centers of said Hall elements lying on an axis which intersects a line parallel to the longitudinal axis of the material at an angle of substantially 5*, means for adjusting the Hall elements in the direction of the magnetic field so that they are symmetrically mounted one on each side of the null plane, means for detecting the signal outputs from each of said Hall generating elements being differentially connected to the detecting means to eliminate noise and enhance the signal-tonoise ratio.
Claim 3
Dependent Claim
39 words
Magnetic detection apparatus according to claim further comprising means for applying a DC bias current to the Hall generator elements and wherein the DC bias current is of the same magnitude by but different polarity for each Hall generator.
Claim 4
Dependent Claim
35 words
Magnetic detection apparatus according to claim 1 further comprising means for mounting each of the Hall generator elements with respect to the material surface to be independently movable in each of three mutually perpendicular directions.
Claim 5
Dependent Claim
91 words
Magnetic detection apparatus according to claim 3 wherein said means for movably mounting said Hall generator elements includes a support structure, means for retaining each of said a Hall generator elements, said means for retaining being movable in a plane normal to the surface of said material, means for moving said retaining means in said normal plane, means for adjusting said means for retaining in a plane parallel to said longitudinal axis of said material, and means for moving said means for retaining in a plane transverse to said longitudinal axis.
Claim 6
Dependent Claim
91 words
Apparatus according to claim 4 wherein said support structure further includes spaced parallelly extending toothed racks, said means for moving said retaining means in said normal plane including rotatable means engaging said toothed racks, said means for retaining are mounted on threAded support members, said threaded support members are rotatable to provide said adjustment, and said means for moving said means for retaining in said transverse plane including threaded means engaging said support structure whereby rotation of said threaded means provides said movement in a plane transverse to said longitudinal axis.
Claim 7
Dependent Claim
28 words
Apparatus according to claim 1 wherein the frequency of said means for magnetizing is at least three times the frequency of the magnetic leakage flux from said flaw.
Claim 8
Dependent Claim
25 words
Magnetic detection apparatus according to claim 6 wherein the means for magnetizing provides a continuous alternating magnetic flux between 50 and 1000 cycles per second.
References Cited (Backward Citations)
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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) | 1974-05-17 | 1974-11-16 | 1975-05-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-17 | 1978-11-16 | 1979-05-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-17 | 1982-11-16 | 1983-05-18 | $7700.00 | Window Closed / Lapsed |