Abstract: For pure aluminum of middle-thickness, by means of comparing experiments of one-sided TIG and MIG arc welding with experiment of double-sided TIG-MIG symmetrical arc welding, and using ANSYS finite element calculation software to simulate weld pool, characteristics of welding pool and regularity of weld shaping for TIG-MIG double-sided symmetrical arc welding are investigated. Research results show that static accumulation effect and dynamic positive heat resistance effect of thermal source for TIG-MIG double-sided symmetrical arc welding can greatly increase depth of fusion. With welding process crossing of weld pool of TIG and MIG will appear. This pool will achieve balance under acting of arc force, surface tension and gravity, and inverse weld shaping is obtained. Stability of cross pool decides inverse shaping of TIG-MIG weld.

Key words: Aluminum, Double-sided symmetrical arc welding, Mechanism of shaping, Numerical simulation, TIG-MIG, additional load losses, additional load losses coefficient, CNC machine tools, spindle system