The Research Of The Influence Of Pulse Waveforms On ARC Shape And Metal Transfer

Pulsed metal inert gas welding (P-MIG) welding have been widely usedin welding carbon steel, stainless steel, aluminium and aluminium alloysbecause of its good welding quality, high efficiency and good controllabilityof metal transfer. As the energy conversion medium, arc can effectivelyconvert the electrical energy to thermal and mechanical energy in the weldingprocess. Forming by the wire , leaving the electrode and falling in pool,Droplets play an important role in the welding process. They take the energyfrom electrode to pool and have a major impact on arc shape and weld joint.By using high-speed camera system and LabView signal acquisition system,this paper is studying the variation of arc shape and metal transfer behaviourin the different pulse parameters.This paper do some researches on the rules of arc length, arc width andarc area affected by current waveform. Based on BP neural network, thethesis set up the mathematic prediction model between pulse parameters and arc shape parameters. The results showed that the peak phase of the arclength, width and arc-arc area are increasing with the increase of peak time orpulse frequency, but decreasing with the increase of peak current. However,the base current does not significant influent the arc shape in peak phase.Based on the pulse energy, the paper find the variation of droplettransfer behavior under different pulse parameters. We set up themathematical relationship between peak current and peak time when thedroplet transfer behavior is ODPP. The paper adds droplet transfer platformin the falling edge of peak current, and the platform current and time increasedroplet transfer. Comparing with the electrical signal and the images, dropletstransfer in peak or base phase when there is no transitional platform, and inthe former condition, droplet speed and great momentum are large, givinggreat impact on the pool; in latter one, droplets are not controllable.Meanwhile, when adds droplet transfer platform, droplets transfer in platformphase, which have good controllability and less impact on the pool.