Abstract: A short circuit arc welding system is disclosed. The control scheme uses a current command signal to drive the output current. The command signal is comprised of a long-term current command that sets the long-term current command level and a real-time or short-by-short current command. Arc voltage feedback is used to determine if the desired arc length is present and to adjust the long-term command. The short-by-short current command is derived from real-time arc current feedback and is used to control the burn-off rate by an instantaneous, or short-by-short, adjustment of the current command. A function of the time derivative of arc power, less the time derivative of arc current, is used to detect, in real time, when the short is about to clear. A stop algorithm is employed that monitors the arc on a short-by-short basis. When the process is ending a very low current level is provided to avoid forming a ball.
Type:
Grant
Filed:
November 5, 2001
Date of Patent:
November 25, 2003
Assignee:
Illinois Tool Works Inc.
Inventors:
Richard Hutchison, Todd Holverson, James Uecker