Arc-swing NG-GMAW Torch And It’s Technological Properties

The poor sidewall fusion defects generally appear in welding processof thick plate with narrow gap gas metal arc welding (NG-GMAW), andit’s believed that increasing the sidewall heat input by controlling themovement of the arc within the narrow gap groove is one of the effectiveways to solve this problem. The arc-swing NG-GMAW welding torch canrightly drive the arc to swing by controlling the contact tube, and the flatstructure torch body can stretch into deep narrow gap groove, whichgreatly enhance the welding efficiency of thick plate.The technological properties of a new arc-swing NG-GMAW torchwere studied in this paper. First, a complete welding system whichincludes welding torch, welding power, arc-swing control mechanism,cooling water and gas protection unit was established. Thereafter the actualperformances of its electricity circuit, cooling water and gas protectionwere tested, meanwhile an optimization of gas channel structure wasimplemented. Then, a series orthogonal and signal factor welding testexperiments were carried out with the optimized welding torch to study thefactors of influence and laws on the weld formation and sidewall fusionquality. The narrow gap single pass multi-layer welding experiment wasimplemented with suitable welding technological parameter, and followedwith metallographic structure feature analysis of the weld joint. At last, thewelding arc and pool images were captured and collected using high speedcamera, and data of welding current and voltage were acquired and analyzedby LabVIEW, aiming to study the influence of swinging arc on weldingstability.The result shows that the technological properties of the new arc-swing NG-GMAW torch are quite satisfying to welding process. Thetorch can be applied to the multi-layer welding of narrow gap groove over30mm depth with stable welding process, and the weld joint with goodsidewall fusion can be got. The swing-arc welding seam presents unique"S-type"， and the interlayer weld microstructure was normalizedsignificantly. It’s also proved that the arc swing will not reduce the weldingstability, nor interfere the droplet transfer mode or deposition rate. Throughthe torch technological properties research, the practical application of thearc-swing NG-GMAW welding technology was promoted.