US Patent 6995338 Method and apparatus for short circuit welding

A method and apparatus for short circuit welding includes providing welding power suitable for short circuit welding, sensing the stick out length, and adjusting the welding speed, such as wire feed speed or travel speed, adjusting a welding parameter, or adjusting thee gas mixture in response thereto. Stick out is preferably determined by measuring a welding parameter, and performing an FFT on the parameter, and then calculating stick out, in one embodiment. Stick out can be either CTTWD or CPTPD. The system can determine when a short is about to clear by calculating a value Vc defined by Vc=d/dt(kl*dp/dt), and comparing Vc to a Vthreshhold, which varies in response to welding cycle history.