Use of miniature magnetic sensors for real-time control of the induction heating process

Patent · Tue Jan 01 00:00:00 EST 2002

OSTI ID:874760

Bentley, Anthony E ^[1]; Kelley, John Bruce ^[2]; Zutavern, Fred J ^[2]

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1. Tijeras, NM
2. Albuquerque, NM

A method of monitoring the process of induction heating a workpiece. A miniature magnetic sensor located near the outer surface of the workpiece measures changes in the surface magnetic field caused by changes in the magnetic properties of the workpiece as it heats up during induction heating (or cools down during quenching). A passive miniature magnetic sensor detects a distinct magnetic spike that appears when the saturation field, B.sub.sat, of the workpiece has been exceeded. This distinct magnetic spike disappears when the workpiece's surface temperature exceeds its Curie temperature, due to the sudden decrease in its magnetic permeability. Alternatively, an active magnetic sensor can also be used to measure changes in the resonance response of the monitor coil when the excitation coil is linearly swept over 0-10 MHz, due to changes in the magnetic permeability and electrical resistivity of the workpiece as its temperature increases (or decreases).

• Research Organization: Sandia National Laboratories (SNL), Albuquerque, NM, and Livermore, CA (United States)
• DOE Contract Number: AC04-94AL85000
• Assignee: Sandia Corporation (Albuquerque, NM)
• Patent Number(s): US 6455825
• OSTI ID: 874760
• Country of Publication: United States
• Language: English

Related Subjects

miniature
magnetic
sensors
real-time
control
induction
heating
process
method
monitoring
workpiece
sensor
located
near
outer
surface
measures
changes
field
caused
properties
heats
cools
quenching
passive
detects
distinct
spike
appears
saturation
bsubsat
exceeded
disappears
workpieces
temperature
exceeds
curie
due
sudden
decrease
permeability
alternatively
active
measure
resonance
response
monitor
coil
excitation
linearly
swept
0-10
mhz
electrical
resistivity
increases
decreases
magnetic field
surface temperature
located near
heating process
induction heating
magnetic sensor
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