Study On NG-Gmaw Torch With Arc-Swing

A problem of penetration at both groove sides is widespread in the application of Narrow Gap Gas Metal Arc Welding (NG-GMAW). After a study and analysis of lots of research achievements on this issue, it`s found that the penetration at groove sides can be improved to some extent by regulating the angle between welding wire tip and groove sides to decrease the distance between arc and groove sides. So a process of NG welding with arc-swing is proposed as a solution, which utilizes one stepper motor to drive a conductive rod. A part bended in an angle connects the conductive rob and contact tube. Welding wire gets though the tube into the groove and ignites. Because of periodic motion of the conductive rob in clockwise and anticlockwise, the arc swings between groove sides. In order to get proper and uniform penetration and high-adaptive process, MAG welding is applied due to its wide range heat input.Firstly, based on the CAE results, a new NG-GMAW torch with arc -swing is developed. The shielding gas nozzle, cooling water cycle and insulation of conduct tube are taken into consideration. With the assistance of ANSYS Fluent, a proper shielding gas nozzle solution is chosen. Orthogonal test and signal factor test are carried out to study the influence of swing parameters on appearance of weld. The data of welding current and voltage are acquired to study the influence of swinging arc on welding stability. At last a multi-layer single pass welding test is carried out to verify the feasibility of the process.The test results indicate that the shielding gas is sufficient, the cooling system can guarantee the torch for long-time-work, and the insulation is reliable for avoiding arc ignition between torch body and groove side-walls. Swinging velocity and swinging angle are key factors for getting wide weld beam. The swinging velocity and side holding-time should be well-matched in order to get uniform weld, otherwise an S-shape weld will occur. Analysis of welding current and voltage shows that the swinging arc has a little influence on the droplet transfer, but the stability of welding process can be guaranteed. The result of multi-layer with single pass welding test shows that a unified penetration on groove sides can be obtained under condition of accurately controlled wire tip position and proper welding parameters, which lays a certain foundation for further research of the process.