US4467388A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electromagnetic chuck power supply and controller
Assignee: Hitachi Metals International Ltd
•
Filing: 1982-07-06
•
Granted: 1984-08-21
•
Expires: 2002-07-06
Abstract
Abstract An electromagnetic chuck power supply and control comprising a magnetic amplifier consisting of a saturable reactor supplying DC power at its output across the electromagnet coils of the electromagnetic chuck. A controllably variable DC current is supplied across the control winding of the magnetic amplifier such that the DC power at the output of the magnetic amplifier is inversely proportional to the DC current flow through the control winding. Variable workpiece holding power is thus obtained at the electromagnetic chuck. At full control current flow, the electromagnetic chuck has no holding power except that due to the residual magnetization of the workpiece. In the event of complete failure of the control current circuit, maximum holding force is applied by the chuck to the workpiece. Automatic de-magnetization of the workpiece is provided by applying a gradually increasing DC voltage across the control winding of the magnetic amplifier and sequentially reversing the current flow at the output of the magnetic amplifier such as to supply alternative current pulses of progressively decreasing amplitude to the chuck electromagnet coils.
Inventors
- 👤 James H. Thoe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:21
CPC Classifications
H; H01; H01F; H01F13/00; H01F29/00; H01F29/14; H01F29/143
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
107 words
A controllable DC power supply for an electromagnetic chuck comprising a magnetic amplifier comprising a saturable reactor having a pair of power windings and a control winding, means for rectifying the electrical current supplied by said power windings, means for connecting said rectified current to said electromagnetic chuck, means for applying a DC current across said control winding for saturating said saturable reactor as a function of the current flow through said control winding whereby the current flowing through said electromagnetic chuck is an inverse function of the current flowing in said control winding, and means for controllably and momentarily reversing current flow through said electromagnetic chuck.
Claim 2
Dependent Claim
107 words
A controllable DC power supply for an electromagnetic chuck comprising a magnetic amplifier comprising a saturable reactor having a pair of power windings and a control winding, means for rectifying the electrical current supplied by said power windings, means for connecting said rectified current to said electromagnetic chuck, means for applying a DC current across said control winding for saturating said saturable reactor as a function of the current flow through said control winding whereby the current flowing through said electromagnetic chuck is an inverse function of the current flowing in said control winding, and means for controllably and momentarily reversing current flow through said electromagnetic chuck.
Claim 3
Dependent Claim
22 words
The controllable DC power supply of claim 1 further comprising means for controllably varying the DC current flow through said control winding.
Claim 4
Dependent Claim
31 words
The controllable DC power supply of claim 1 further comprising means for shutting off current flow through said control winding for providing full power at the output of said power windings.
Claim 5
Dependent Claim
34 words
The controllable DC power supply of claim 1 further comprising means for full current flow through said control winding for fully saturating said saturable reactor for cutting off current flow through said power windings.
Claim 6
Dependent Claim
36 words
The controllable DC power supply of claim 1 further comprising means for applying to said electromagnetic chuck an alternating current progressively variable from a maximum to zero for de-magnetizing a workpiece disposed on said electromagnetic chuck.
Claim 7
Dependent Claim
47 words
The controllable DC power supply of claim 5 wherein said means for supplying an alternating current of progressively decreasing amplitude to said electromagnetic chuck comprises means for progressively increasing the current flow through said control winding while simultaneously reversing periodically the current flow to said electromagnetic chuck.
Claim 8
Dependent Claim
31 words
The controllable DC power supply of claim 2 further comprising means for shutting off current flow through said control winding for providing full power at the output of said power windings.
Claim 9
Dependent Claim
34 words
The controllable DC power supply of claim 2 further comprising means for full current flow through said control winding for fully saturating said saturable reactor for cutting off current flow through said power windings.
Claim 10
Dependent Claim
36 words
The controllable DC power supply of claim 2 further comprising means for applying to said electromagnetic chuck an alternating current progressively variable from a maximum to zero for de-magnetizing a workpiece disposed on said electromagnetic chuck.
Claim 11
Dependent Claim
47 words
The controllable DC power supply of claim 5 wherein said means for supplying an alternating current of progressively decreasing amplitude to said electromagnetic chuck comprises means for progressively increasing the current flow through said control winding while simultaneously reversing periodically the current flow to said electromagnetic chuck.
Claim 12
Dependent Claim
34 words
The controllable DC power supply of claim 3 further comprising means for full current flow through said control winding for fully saturating said saturable reactor for cutting off current flow through said power windings.
Claim 13
Dependent Claim
36 words
The controllable DC power supply of claim 3 further comprising means for applying to said electromagnetic chuck an alternating current progressively variable from a maximum to zero for de-magnetizing a workpiece disposed on said electromagnetic chuck.
Claim 14
Dependent Claim
47 words
The controllable DC power supply of claim 12 wherein said means for supplying an alternating current of progressively decreasing amplitude to said electromagnetic chuck comprises means for progressively increasing the current flow through said control winding while simultaneously reversing periodically the current flow to said electromagnetic chuck.
Claim 15
Dependent Claim
36 words
The controllable DC power supply of claim 4 further comprising means for applying to said electromagnetic chuck an alternating current progressively variable from a maximum to zero for de-magnetizing a workpiece disposed on said electromagnetic chuck.
Claim 16
Dependent Claim
47 words
The controllable DC power supply of claim 14 wherein said means for supplying an alternating current of progressively decreasing amplitude to said electromagnetic chuck comprises means for progressively increasing the current flow through said control winding while simultaneously reversing periodically the current flow to said electromagnetic 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) | 1987-08-21 | 1988-02-20 | 1988-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-08-21 | 1992-02-20 | 1992-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-08-21 | 1996-02-20 | 1996-08-21 | $7700.00 | Window Closed / Lapsed |