Multipass mig butt welding thick plates - using constant height for nozzle through which consumable electrode wire passes

摘要

The length of the wire projecting downwards from the nozzle is initially longer than the thickness of the plates, and becomes shorter as the number of deposited layers increases. As the length decreases the voltage fed to nozzle the wire speed; and the speed of welding along the gap are all decreased. Productivity is increased without the need to adjust the height of nozzle after each pass; and only a simple butt joint need be used, i.e. V- or X- butt joints are not necessary.