| Abstrakt: |
A review of investigations devoted to the processes of inert-gas nonconsumable electrode welding with welding current modulation was performed. The third part of the review is devoted to analysis of the works, dealing with theoretical study and mathematical modeling of the processes of heat-, mass- and electric transfer in arc plasma and welded metal in TIG welding by modulated current. Different approaches to theoretical study of the above-mentioned processes are described, as well as respective mathematical models, allowing for the conditions of nonconsumable electrode welding with low-frequency (up to 10 Hz) and high-frequency (above 10 kHz) pulsed modulation of welding current. Results of numerical analysis of the distributed and integral characteristics of an argon arc with refractory cathode at pulse variation of current are given. It was performed on the base of models of a non-stationary arc with distributed and concentrated parameters. Results of computer modeling of thermal, hydrodynamic and electromagnetic processes in the welded metal (also at self-consistent accounting of the processes that proceed in arc plasma) were analyzed for the case of spot TIG welding with low-frequency pulse modulation of current. Presented are the analytical dependencies that describe the impact of the shape and parameters of welding current pulses on the characteristics of dynamic action of an arc with a refractory cathode on weld pool metal. [ABSTRACT FROM AUTHOR] |
