Drop short control of electrode gap
- Albuquerque, NM
- Sandia Park, NM
During vacuum consumable arc remelting the electrode gap between a consumable electrode and a pool of molten metal is difficult to control. The present invention monitors drop shorts by detecting a decrease in the voltage between the consumable electrode and molten pool. The drop shorts and their associated voltage reductions occur as repetitive pulses which are closely correlated to the electrode gap. Thus, the method and apparatus of the present invention controls electrode gap based upon drop shorts detected from the monitored anode-cathode voltage. The number of drop shorts are accumulated, and each time the number of drop shorts reach a predetermined number, the average period between drop shorts is calculated from this predetermined number and the time in which this number is accumulated. This average drop short period is used in a drop short period electrode gap model which determines the actual electrode gap from the drop short. The actual electrode gap is then compared with a desired electrode gap which is selected to produce optimum operating conditions and the velocity of the consumable error is varied based upon the gap error. The consumable electrode is driven according to any prior art system at this velocity. In the preferred embodiment, a microprocessor system is utilized to perform the necessary calculations and further to monitor the duration of each drop short. If any drop short exceeds a preset duration period, the consumable electrode is rapidly retracted a predetermined distance to prevent bonding of the consumable electrode to the molten remelt.
- Research Organization:
- AT&T
- DOE Contract Number:
- AC04-76DP00789
- Assignee:
- United States of America as represented by United States (Washington, DC)
- Patent Number(s):
- US 4578795
- OSTI ID:
- 865797
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
control
electrode
gap
vacuum
consumable
remelting
pool
molten
metal
difficult
monitors
shorts
detecting
decrease
voltage
associated
reductions
occur
repetitive
pulses
closely
correlated
method
apparatus
controls
based
detected
monitored
anode-cathode
accumulated
time
reach
predetermined
average
period
calculated
model
determines
compared
desired
selected
produce
optimum
operating
conditions
velocity
error
varied
driven
according
prior
preferred
embodiment
microprocessor
utilized
perform
calculations
monitor
duration
exceeds
preset
rapidly
retracted
distance
prevent
bonding
remelt
electrode gap
operating conditions
molten metal
preferred embodiment
predetermined distance
consumable electrode
operating condition
molten pool
repetitive pulses
desired electrode
gap based
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