Abstract: The choosing fields of top face temperature measured points to control back face wide is quantificationally obtained making use of the relativity theory and the sensitivity on the base of the established three-dimentional analytical model in a plate of finite size with a Gaussian distributed moving heat source, and the general principle of the choosing fields is provided , so the next penetration control will be based on the principle. The penetration control methods are discussed on the GTAW on the base of the established three dimentional analytical model and the choosed fields of top face temperature measured points to control back face wide, and the PID control parameters are optimizedly designed with the emulated means. The experiment results show that the combined method of PID and Fuzzy control is effective.

Key words: GTAW, Penetration control, Temperature field