Electricity: electrical systems and devices – Control circuits for electromagnetic devices – Systems for magnetizing – demagnetizing – or controlling the...
Patent
1982-02-09
1985-06-11
Rubinson, Gene Z.
Electricity: electrical systems and devices
Control circuits for electromagnetic devices
Systems for magnetizing, demagnetizing, or controlling the...
335289, 361149, H01F 1300
Patent
active
045232504
DESCRIPTION:
BRIEF SUMMARY
The present invention relates generally to magnetic control systems, and more particularly, to a magnetic control system employing novel solid state circuit means for effecting demagnetizing of an object such as a magnetic chuck and associated ferromagnetic work piece or the like.
It is known that in employing a magnetic chuck to hold a ferromagnetic work piece in a machine tool or the like, the chuck and the work piece, upon deenergizing, retain significant residual magnetism which inhibits release of the work piece from the chuck. It is conventional in such cases to demagnetize the magnetic chuck and associated work piece so as to enable release of the work piece. Such demagnetizing is generally accomplished by passing a current through the chuck, and thereby the associated work piece, in alternating opposite directions by reversing the polarity in a series of steps while lowering the voltage potential in each successive step until the voltage potential reaches substantially zero at which time the chuck and work piece are sufficiently demagnetized to allow the work piece to be readily separated from the magnetic chuck.
A general object of the present invention is to provide a novel magnetic control system which finds particular application in controlling magnetic chucks and the like, and which is adapted to effect demagnetizing of the chuck and associated work piece so as to enable an operator to readily remove the work piece from the chuck.
A more particular object of the present invention is to provide a totally solid state magnetic chuck control system employing a power output circuit interfaced with a digital control circuit and digital-to-analog converter circuit so that the power output circuit is adapted to apply output voltage signals to the chuck of successively decreasing magnitude and alternating polarity during a demagnetizing operation.
Still another object of the present invention is to provide a magnetic chuck control system having a power output circuit connected to a DC power supply and interfaced with a digital control circuit and a digital-to-analog converter circuit operative on the power output circuit to establish output voltage signals to the chuck of alternating polarity and successively decreasing magnitude during a demagnitizing operation, the digital control and digital-to-analog circuit being of low voltage operation and isolated from the high voltage power output circuit so as to protect the operator should a fault current occur in the power output circuit.
A feature of the magnetic chuck control system in accordance with the present invention lies in the provision of a visual display adapted to digitally indicate the various cycles of voltage reversal during a demagnetizing operation and thereby inform the operator when demagnetizing has been completed.
Another feature of the magnetic chuck control system in accordance with the present invention lies in the employment of a digital-to-analog converter circuit for controlling the magnitude of the output signals from the power output circuit to the magnetic chuck, the digital-to-analog converter circuit including a variable power adjustment enabling selection of the magnetic chuck holding power to a magnitude less than 100% of full power.
Another feature of the magnetic chuck control system in accordance with the present invention lies in the use of triacs in a reversing circuit portion of the power output circuit, the triacs being connected in a bridge type circuit and having their respective gates interfaced with the digital control circuit through optical couplings so as to isolate the digital control circuit from the substantially higher current controlled by the triacs.
Still another feature of the magnetic chuck control system in accordance with the invention lies in the provision of various control functions such as full power, variable power, residual power and release, and wherein the various functions are digitally interlocked so that an operator must effect full or variable power after a residual power function to in
REFERENCES:
patent: 4370693 (1983-01-01), McDonald
patent: 4402032 (1983-08-01), Wilterdink
Bacchiere Daniel P.
Polinski Stanley F.
Bacchiere Daniel P.
Rubinson Gene Z.
Schroeder L. C.
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