In this paper

the causes of the incompletely filled groove of the butt welds in the fully mechanized welded underframe of the standard EMU at a speed of 350 km per hour were analyzed from the aspects of design structure and technological methods. In the aspects of design structure

intermittent welding technology

welding sequence

welding process parameters and so on

an optimization program has been developed and implemented in the project to completely solve the problem of incompletely filled groove during fully mechanized welding. As a result

weld repair amount dropped observably

which greatly improved the flatness after welding improved greatly

effectively reduce the work amount

suitable for mass production of plug-in aluminum alloy underframe to be fully mechanized welded.