US3897990A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for inspection of ferro-magnetic billets
Assignee: Elkem ASA
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Filing: 1974-07-29
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Granted: 1975-08-05
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Expires: 1994-07-29
Abstract
Abstract An apparatus for the detection of hairline cracks in ferromagnetic billets is disclosed. Alternating current is used to heat the surface of the billet whereby magnetic powder on the surface of the billet melts to show imperfections in the surface of the billet.
Inventors
- 👤 Harald Chr Bjerke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:01
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/72; G01N27/82; G01N27/83; G01N27/84
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
116 words
In an apparatus for the inspection of elongated ferromagnetic objects: a. a conical chuck disposed to bear against the elongated ferromagnetic object; b. means for supplying electric current through the conical chuck to the elongated ferro-magnetic object whereby the elongated ferro-magnetic object is magnetized; c. means for applying to the magnetized elongated ferro-magnetic object a powder comprising finely divided iron or iron alloys and a coloring agent in powder form which, upon heating, will adhere to the surface of the elongated ferro-magnetic object; and d. means for supplying to the elongated ferro-magnetic object through the conical chuck an alternating electric current of sufficient intensity to cause the coloring agent to adhere to the elongated ferro-magnetic object.
Claim 2
Dependent Claim
116 words
In an apparatus for the inspection of elongated ferromagnetic objects: a. a conical chuck disposed to bear against the elongated ferromagnetic object; b. means for supplying electric current through the conical chuck to the elongated ferro-magnetic object whereby the elongated ferro-magnetic object is magnetized; c. means for applying to the magnetized elongated ferro-magnetic object a powder comprising finely divided iron or iron alloys and a coloring agent in powder form which, upon heating, will adhere to the surface of the elongated ferro-magnetic object; and d. means for supplying to the elongated ferro-magnetic object through the conical chuck an alternating electric current of sufficient intensity to cause the coloring agent to adhere to the elongated ferro-magnetic object.
Claim 3
Dependent Claim
18 words
The apparatus of claim 1 wherein the conical chuck is cooled during application of the alternating electric current.
Claim 4
Dependent Claim
27 words
The apparatus of claim 2 wherein the cooling is by means of water which passes through an enclosed space on the rear surface of the conical chuck.
Claim 5
Dependent Claim
45 words
The apparatus of claim 1 wherein the conical chuck is movable in axial direction and wherein the alternating current is supplied to the conical chuck by means comprising a bus bar and a clamp which can be brought into pressurized contact with the bus bar.
Claim 6
Dependent Claim
12 words
The apparatus of claim 4 wherein the conical chuck is rotatably moveable.
Claim 7
Dependent Claim
25 words
The apparatus of claim 5 wherein electric current is supplied to the conical chuck by means comprising carbon brushes when the conical chuck is rotating.
Claim 8
Dependent Claim
23 words
The apparatus of claim 1 wherein current is supplied to the conical chuck by means comprising an axially movable but non-rotatable contact element.
Claim 9
Dependent Claim
37 words
The apparatus of claim 7 wherein the contact element is selectively in pressurized contact with the conical chuck by means comprising a bearing plate and a bearing arm, the bearing arm being connected to a pressure cylinder.
Claim 10
Dependent Claim
34 words
In an apparatus for the inspection of elongated ferro-magnetic objects by supplying an electric current through a conical chuck, the improvement comprising at least one said conical chuck being composed of an austenitic steel.
Claim 11
Dependent Claim
34 words
In an apparatus for the inspection of elongated ferro-magnetic objects by supplying an electric current through a conical chuck, the improvement comprising at least one said conical chuck being composed of an austenitic steel.
Claim 12
Dependent Claim
20 words
The apparatus of claim 9 further comprising a source of alternating current to provide the current to the conical chuck.
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) | 1978-08-04 | 1979-02-03 | 1979-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-04 | 1983-02-03 | 1983-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-04 | 1987-02-03 | 1987-08-05 | $7700.00 | Window Closed / Lapsed |