US4495983A — Determination of liquid-solid interface and head …

Claim 1

Independent Claim 212 words

In an electromagnetic casting system for casting material comprising: means for electromagnetically containing molten material and for forming said molten material during a casting run into a casting of desired shape, said casting including during said casting run a liquid-solid interface defining molten material head and solid material portions of said casting, said electromagnetic containing and forming means including an inductor for applying a magnetic field to said molten material, said magnetic field defining a containment zone for said molten material and a gap between said molten material and said inductor, means for applying an alternating current to said inductor to generate said magnetic field, means for controlling the current applied to said inductor whereby said gap remains substantially constant, a non-magnetic shield for attenuating and shaping said magnetic field, the improvement comprising: means for monitoring the location of said liquid-solid interface, said liquid-solid interface monitoring means including first means for determining at least a first electrical parameter of said electromagnetic casting system which varies with variations in the location of the liquid-solid interface, wherein said first electrical parameter substantially corresponds to the equivalent series resistance of the electromagnetic casting system; and means responsive to said first determining means for generating a readout signal representative of the location of said liquid-solid interface.

Claim 2

Dependent Claim 212 words

In an electromagnetic casting system for casting material comprising: means for electromagnetically containing molten material and for forming said molten material during a casting run into a casting of desired shape, said casting including during said casting run a liquid-solid interface defining molten material head and solid material portions of said casting, said electromagnetic containing and forming means including an inductor for applying a magnetic field to said molten material, said magnetic field defining a containment zone for said molten material and a gap between said molten material and said inductor, means for applying an alternating current to said inductor to generate said magnetic field, means for controlling the current applied to said inductor whereby said gap remains substantially constant, a non-magnetic shield for attenuating and shaping said magnetic field, the improvement comprising: means for monitoring the location of said liquid-solid interface, said liquid-solid interface monitoring means including first means for determining at least a first electrical parameter of said electromagnetic casting system which varies with variations in the location of the liquid-solid interface, wherein said first electrical parameter substantially corresponds to the equivalent series resistance of the electromagnetic casting system; and means responsive to said first determining means for generating a readout signal representative of the location of said liquid-solid interface.

Claim 3

Dependent Claim 83 words

An electromagnetic casting system as in claim 1 wherein said first means for determining includes means for sensing both the current in said inductor and the voltage across said inductor and generating first and second signals corresponding to the in-phase current in said inductor and the in-phase voltage across said inductor, respectively, said first determining means further includes means responsive to the first and second signals for generating an output signal substantially corresponding to the equivalent series resistance of said electromagnetic casting system.

Claim 4

Dependent Claim 49 words

An electromagnetic casting system as in claim 2 wherein said first means for determining said at least one electrical parameter further includes means for comparing said output signal to a preprogrammed table establishing the relationship between different values of said output signal and different locations of the liquid-solid interface.

Claim 5

Dependent Claim 98 words

An electromagnetic casting system as in claim 2 wherein said means for determining said first electrical parameter further includes: means for generating a 0° phase reference output signal; first phase-sensitive voltage rectifier means receiving said 0° phase reference output signal and a voltage signal corresponding to the current in the inductor for generating a voltage signal corresponding to the in-phase (0°) current in said inductor; and second phase-sensitive voltage rectifier means receiving said 0° phase reference output signal and said voltage across said inductor for generating a voltage signal corresponding to the in-phase (0°) voltage across said inductor.

Claim 6

Dependent Claim 24 words

An electromagnetic casting system as in claim 4 wherein said means for generating said 0° phase reference output signal comprises a phase-locked loop circuit.

Claim 7

Dependent Claim 46 words

An electromagnetic casting system as in claim 5 further including means for converting the sensed current in said inductor to a properly scaled voltage to provide a current signal in voltage form for application to said phase-locked loop circuit and said first phase-sensitive voltage rectifier means.

Claim 8

Dependent Claim 55 words

An electromagnetic casting system as in claim 5 further including voltage divider means for dividing said voltage signal corresponding to said in-phase current in said inductor by said voltage signal corresponding to said in-phase voltage across said inductor to obtain said output signal substantially corresponding to the equivalent series resistance of said electromagnetic casting system.

Claim 9

Dependent Claim 213 words

In a process for continuously and semi-continuously electromagnetically containing and forming molten material during a casting run into a casting of desired shape, said casting having during said casting run a liquid-solid interface defining a head of molten material and a solid material portion of said casting, said electromagnetic containing and forming including the steps of: providing an inductor, applying a current in and a voltage across said inductor to generate and apply a magnetic field to said molten material; and applying said magnetic field to said molten material to define a containment zone of said molten material and a gap between said molten material and said inductor; controlling the current to the inductor so that the gap remains substantially constant; providing a non-magnetic shield for attenuating and shaping said magnetic field; the improvement comprising the steps of: monitoring the location of the liquid-solid interface by determining at least a first electrical parameter of the electromagnetic casting system during said run, said at least first electrical parameter varying with variations in the location of the liquid-solid interface, wherein said first electrical parameter substantially corresponds to the equivalent series resistance of the electromagnetic casting system; and responsive to said step of determining, generating a readout signal representative of the magnitude of the liquid-solid interface.

Claim 10

Dependent Claim 213 words

In a process for continuously and semi-continuously electromagnetically containing and forming molten material during a casting run into a casting of desired shape, said casting having during said casting run a liquid-solid interface defining a head of molten material and a solid material portion of said casting, said electromagnetic containing and forming including the steps of: providing an inductor, applying a current in and a voltage across said inductor to generate and apply a magnetic field to said molten material; and applying said magnetic field to said molten material to define a containment zone of said molten material and a gap between said molten material and said inductor; controlling the current to the inductor so that the gap remains substantially constant; providing a non-magnetic shield for attenuating and shaping said magnetic field; the improvement comprising the steps of: monitoring the location of the liquid-solid interface by determining at least a first electrical parameter of the electromagnetic casting system during said run, said at least first electrical parameter varying with variations in the location of the liquid-solid interface, wherein said first electrical parameter substantially corresponds to the equivalent series resistance of the electromagnetic casting system; and responsive to said step of determining, generating a readout signal representative of the magnitude of the liquid-solid interface.

Claim 11

Dependent Claim 87 words

A process as in claim 8 wherein said step of determining said at least first electrical parameter comprises sensing the current in said inductor and the voltage across said inductor and generating first and second signals corresponding to the in-phase current in said inductor and the in-phase voltage across said inductor, respectively, and said step of determining said first electrical parameter further comprises generating an output signal substantially corresponding to the equivalent series resistance of said electromagnetic casting system in response to said first and second signals.

Claim 12

Dependent Claim 49 words

A process as in claim 9 wherein said determining step further includes the step of: comparing said output signal to a preprogrammed table establishing at least the relationship between different values of said output signal and different locations of said liquid-solid interface for the particular casting system being monitored.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1988-01-29	1988-07-30	1989-01-29	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1992-01-29	1992-07-30	1993-01-29	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1996-01-29	1996-07-30	1997-01-29	$7700.00	Window Closed / Lapsed

Determination of liquid-solid interface and head in electromagnetic casting

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