Patent US3567045A successfully refreshed from Google Patents.
US3567045A
Expired / Lapsed
US
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Magnetic can handling apparatus with demagnetization
Assignee: FMC Corp
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Filing: 1969-07-28
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Granted: 1971-03-02
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Expires: 1989-07-28
Abstract
Abstract Apparatus for transferring cans between a pallet and a conveyor picks up and deposits the cans by means of carriage mounted electromagnets. The DC source for the electromagnets is a bridge embodying silicon controlled rectifiers. A silicon controlled clamping rectifier is connected across the DC source and gated for passing current through the magnets only in the direction of the magnetic field collapsed current. When the magnets are deenergized the clamping silicon controlled rectifier is fired to short out the current generated by collapse of the magnetic field. This isolates the magnets from the rectifier bridge and permits it to operate under remote control of the switch for energizing and deenergizing the magnets. An incandescent lamp heated by AC is connected across the magnets when the clamping silicon control rectifier is cut off. Energization of the electric lamp demagnetizes the magnets within a few cycles after the AC is applied to the lamp.
Inventors
- 👤 William G Albright
- 👤 Charles F Kiser Jr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:15
CPC Classifications
B; B65; B65G; B65G59/00; B65G59/02; B65G59/04; B65G59/045; H; H01; H01F; H01F29/00; H01F29/14; H01F29/143; H01F7/00; H01F7/06; H01F7/08; H01F7/18; H01F7/20; H01F7/206
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
176 words
Apparatus for transferring paramagnetic articles such as cans between a pallet or the like and a conveyor, said apparatus comprising the conveyor and means for supporting the pallet, a carriage, means for moving said carriage between positions overlying said pallet support means and said conveyor, electromagnets on said carriage, a DC source for said magnets, a silicon controlled clamping rectifier connected across said DC source and gated for passing current through said magnets only in the direction of the magnetic field collapse current, an AC source of demagnetizing current connected across said DC source; switch means for energizing said magnets through said DC source to pick up articles, for firing said clamping rectifier and for opening said AC demagnetizing source when said carriage is in one of its positions; switch means for deenergizing said magnets to release the articles, for cutting off said clamping rectifier and for energizing said AC demagnetizing source when the carriage is in its other position; said AC demagnetizing source including a rapidly heating resistance element for tapering off the demagnetizing AC.
Claim 2
Dependent Claim
176 words
Apparatus for transferring paramagnetic articles such as cans between a pallet or the like and a conveyor, said apparatus comprising the conveyor and means for supporting the pallet, a carriage, means for moving said carriage between positions overlying said pallet support means and said conveyor, electromagnets on said carriage, a DC source for said magnets, a silicon controlled clamping rectifier connected across said DC source and gated for passing current through said magnets only in the direction of the magnetic field collapse current, an AC source of demagnetizing current connected across said DC source; switch means for energizing said magnets through said DC source to pick up articles, for firing said clamping rectifier and for opening said AC demagnetizing source when said carriage is in one of its positions; switch means for deenergizing said magnets to release the articles, for cutting off said clamping rectifier and for energizing said AC demagnetizing source when the carriage is in its other position; said AC demagnetizing source including a rapidly heating resistance element for tapering off the demagnetizing AC.
Claim 3
Dependent Claim
45 words
The apparatus of claim 1, wherein said resistant element has sufficient cold current capacity so that the initial demagnetizing current surge through said resistance element is sufficient to bring the remaining flux density of the magnets through the remanence point of the magnetic hysteresis curve.
Claim 4
Dependent Claim
17 words
The apparatus of claim 2, wherein said resistance element comprises a hermetically sealed tungsten-type filament electric lamp.
Claim 5
Dependent Claim
39 words
The apparatus of claim 1, wherein said DC source comprises a rectifier bridge embodying silicon controlled rectifiers, an AC source for said bridge and a DC firing control circuit for said bridge operated by said magnet energizing switch means.
Claim 6
Dependent Claim
23 words
The apparatus of claim 4, wherein said AC demagnetizing source is derived from the AC source for said bridge by an isolation transformer.
Claim 7
Dependent Claim
39 words
The apparatus of claim 4, wherein said DC firing control circuit derives its energy from a stepdown transformer connected across said AC source for the rectifier bridge, and said clamping rectifier is triggered from said DC firing control circuit.
Claim 8
Dependent Claim
35 words
The apparatus of claim 1, wherein said magnet energizing switch means comprises an article-operated switch mounted on the magnets with a switch operator projecting below the magnets for switch closure when articles engage the magnets.
Claim 9
Dependent Claim
57 words
The apparatus of claim 7, wherein said switch means for firing said clamping rectifier is in series with said article-operated switch and is normally closed for firing the clamping recTifier, said clamping rectifier switch being positioned to be opened by said carriage when the latter is disposed for deenergizing the magnets and cutting off the clamping rectifier.
Claim 10
Dependent Claim
36 words
The apparatus of claim 1, wherein said switch means for said AC demagnetizing source includes timer contacts which energize the AC demagnetizing source soon after said switch means for the clamping rectifier cuts off the latter.
Claim 11
Independent Claim
85 words
The method of magnetically conveying paramagnetic articles such as cans comprising the steps of energizing an electromagnet assembly with a rectified AC source for picking up the articles, shorting the magnets while energized in the direction of current flow caused by magnetic field collapse, deenergizing the magnets for releasing the articles while continuing the short across the magnets for dissipating the field collapse current, removing the short across the magnets and applying a rapidly tapering AC across the magnets for removing the residual magnetic field.
Claim 12
Independent Claim
85 words
The method of magnetically conveying paramagnetic articles such as cans comprising the steps of energizing an electromagnet assembly with a rectified AC source for picking up the articles, shorting the magnets while energized in the direction of current flow caused by magnetic field collapse, deenergizing the magnets for releasing the articles while continuing the short across the magnets for dissipating the field collapse current, removing the short across the magnets and applying a rapidly tapering AC across the magnets for removing the residual magnetic field.
Claim 13
Dependent Claim
35 words
The method of claim 10, wherein said tapering AC is applied through a rapidly heating resistance of a value which initially passes enough current to demagnetize the magnets over a few cycles of the AC.
Claim 14
Dependent Claim
41 words
The method of claim 10, wherein said rectified AC source is developed from a silicon controlled rectifier bridge, and said magnets are shorted by a silicon controlled rectifier which is gated to fire in the direction of magnetic field collapse current.
Claim 15
Independent Claim
111 words
The method of magnetically conveying articles such as cans comprising the steps of energizing an electromagnet assembly with a rectified AC source for picking up the articles, shorting the magnets while energized in the direction of current flow caused by magnetic field collapse, deenergizing the magnets for releasing the articles while continuing the short across the magnets for dissipating the field collapse current, removing the short across the magnets and applying a rapidly tapering AC across the magnets for removing the residual magnetic field, the first negative-going cycle of said AC applying sufficient current to cause the current-flux density curve to pass through the remanence point of the residual magnetic field.
Claim 16
Independent Claim
111 words
The method of magnetically conveying articles such as cans comprising the steps of energizing an electromagnet assembly with a rectified AC source for picking up the articles, shorting the magnets while energized in the direction of current flow caused by magnetic field collapse, deenergizing the magnets for releasing the articles while continuing the short across the magnets for dissipating the field collapse current, removing the short across the magnets and applying a rapidly tapering AC across the magnets for removing the residual magnetic field, the first negative-going cycle of said AC applying sufficient current to cause the current-flux density curve to pass through the remanence point of the residual magnetic field.
Claim 17
Dependent Claim
20 words
The method of claim 13, wherein said rapidly tapering AC is applied through a hermetically sealed tungsten-type filament incandescent lamp.
References Cited (Backward Citations)
US2143026A
Cited
US2071859A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |