Patent US3821613A successfully refreshed from Google Patents.
US3821613A
Expired / Lapsed
US
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Method and apparatus for demagnetizing mechanical parts
Assignee: SKF Compagnie dApplications Mecaniques SA
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Filing: 1972-10-16
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Granted: 1974-06-28
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Expires: 1992-10-16
Abstract
Abstract Mechanical parts are demagnetized by passing them by the end of an induction coil, perpendicular to the lines of force of the magnetic field induced by the coil. The coil forms part of a resonant circuit the parameters of which are so selected that resonance is achieved only when a part to be demagnetized is within the magnetic field.
Inventors
- 👤 J Fauve
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 04:44
CPC Classifications
H; H01; H01F; H01F13/00; H01F13/006
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
242 words
A device for demagnetizing ferromagnetic parts which have acquired magnetization during machining in a machine tool, said device comprising a resonant circuit having an induction coil mounted in series with a variable capacitor and means for energizing said resonant circuit with alternating current to create a magnetic field, the values of said induction coil and said capacitor being such that the amplitude of said magnetic field is substantially zero when there is no part to be demagnetized in front of said induction coil and the amplitude of said magnetic field corresponds to the saturization magnetization of the part to be demagnetized when said part is in front of said induction coil, and means for advancing the part to be demagnetized past one end of said coil perpendicularly to the axis of said coil at a substantially constant rate of speed, whereby a sharp resonance is obtained and at least one complete hysteresis loop is traversed while the area of said loop decreases from a maximum value to a value substantially equal to zero, said means for advancing the part at a constant speed comprising: 1. hydraulic means for restarting said part advancing means after demagnetization of each part when a subsequent part is fed into said machine tool, said hydraulic means comprising a mechanical member acting directly on thE part to be demagnetized, and 2. means for retaining said part perpendicularly to the axis of said induction coil as said part advances.
Claim 2
Independent Claim
242 words
A device for demagnetizing ferromagnetic parts which have acquired magnetization during machining in a machine tool, said device comprising a resonant circuit having an induction coil mounted in series with a variable capacitor and means for energizing said resonant circuit with alternating current to create a magnetic field, the values of said induction coil and said capacitor being such that the amplitude of said magnetic field is substantially zero when there is no part to be demagnetized in front of said induction coil and the amplitude of said magnetic field corresponds to the saturization magnetization of the part to be demagnetized when said part is in front of said induction coil, and means for advancing the part to be demagnetized past one end of said coil perpendicularly to the axis of said coil at a substantially constant rate of speed, whereby a sharp resonance is obtained and at least one complete hysteresis loop is traversed while the area of said loop decreases from a maximum value to a value substantially equal to zero, said means for advancing the part at a constant speed comprising: 1. hydraulic means for restarting said part advancing means after demagnetization of each part when a subsequent part is fed into said machine tool, said hydraulic means comprising a mechanical member acting directly on thE part to be demagnetized, and 2. means for retaining said part perpendicularly to the axis of said induction coil as said part advances.
Claim 3
Dependent Claim
165 words
A device as claimed in claim 1 in which said hydraulic device comprises a hydraulic cylinder connected directly to the feed means of said machine tool so as to cause rotation of a retaining arm and of a pressure arm, which arms are substantially perpendicular to each other, and in which said demagnetizing device comprises an inclined gutter in which the part to be demagnetized slides as a consequence of its own weight, said retaining and pressure arms cooperating with said gutter to first immobilize the part to be demagnetized is by contact with said retaining arm, in a position in which the amplitude of said magnetic field is substantially zero, and then causes said part to travel perpendicularly to the axis of said induction coil by contact with said pressure arm, whereby a sharp resonance is obtained and at least one complete hysteresis loop is traversed while the area of said loop decreases from a maximum value to a value substantially equal to zero.
Claim 4
Dependent Claim
17 words
means for retaining said part perpendicularly to the axis of said induction coil as said part advances.
Claim 5
Dependent Claim
17 words
means for retaining said part perpendicularly to the axis of said induction coil as said part advances.
Claim 6
Dependent Claim
49 words
A device as claimed in claim 2 which comprises a voltage detector positioned in the resonant circuit and connected to the electrical supply of said machine tool to stop the operation of the demagnetizing device if the voltage detector indicates a defect in the functioning of the resonant circuit.
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) | 1977-06-27 | 1977-12-27 | 1978-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-27 | 1981-12-27 | 1982-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-27 | 1985-12-27 | 1986-06-28 | $7700.00 | Window Closed / Lapsed |