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Title: Method and apparatus for controlling electrode gap during vacuum consumable arc remelting

Abstract

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 preferredmore » 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.« less

Inventors:
; ; ;
OSTI Identifier:
5437924
Application Number:
ON: DE84005995
Assignee:
SNL; EDB-84-030589
DOE Contract Number:  
AC04-76DP00789
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; ARC WELDING; ELECTRODES; CONTROL; ELECTRICAL FAULTS; POSITIONING; FABRICATION; JOINING; WELDING; 420100* - Engineering- General Engineering- (-1987)

Citation Formats

Fisher, R.W., Maroone, J.P., Tipping, D.W., and Zanner, F.J. Method and apparatus for controlling electrode gap during vacuum consumable arc remelting. United States: N. p., Web.
Fisher, R.W., Maroone, J.P., Tipping, D.W., & Zanner, F.J. Method and apparatus for controlling electrode gap during vacuum consumable arc remelting. United States.
Fisher, R.W., Maroone, J.P., Tipping, D.W., and Zanner, F.J. . "Method and apparatus for controlling electrode gap during vacuum consumable arc remelting". United States.
@article{osti_5437924,
title = {Method and apparatus for controlling electrode gap during vacuum consumable arc remelting},
author = {Fisher, R.W. and Maroone, J.P. and Tipping, D.W. and Zanner, F.J.},
abstractNote = {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.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {},
month = {}
}