Development of high speed MIG welding process (report 2) - effect of current suppliability between contact tube and welding wire on the occurrence of surface defect

摘要

In order to maintain the optimum welding condition initially set for high speed MIG welding, the effect of current suppliability between contact tube and welding wire was examined by using various types of contact tubes on the occurrence of the pit shaped surface defect. When the current suppliabilty of the experientially bent contact tube was not stable, surface defects sometimes occurred on the weld bead. Under unstable current suppliability, spark occurred between the contact tube and the welding wire, which induced the repetition of short and long arcs due to the adhesion and the release of the wire, and then resulted in the formation of the surface defect. By using a contact tube we developed where the welding wire was forced optimally onto the inner wall of the tube by three pieces of ball plungers, the initially set welding condition was maintained stable and long weld bead with superior appearance was obtained in high speed MIG welding.