Research On The Forming Technology And Mechanism Of Underwater Flux-cored Wire Arc Transverse Cutting

Underwater flux-cored wire arc cutting method has broad application prospects in the field of underwater cutting because of its advantages of simple equipment,low cost and high efficiency.At present,the research on this method mainly focuses on the cutting posture of underwater flat cutting.Due to the inevitable occurrence of transverse cutting and other cutting postures in practical applications,and the change in cutting posture will have an impact on its cutting mechanism and kerf morphology,its forming mechanism is still unclear.Therefore,this article establishes an underwater flux-cored wire arc transverse cutting platform to study its cutting process.Using high-speed photography to observe the cutting process to analyze the formation mechanism of underwater arc transverse cutting.Firstly,in order to study the influence of cutting parameters on kerf morphology and cutting stability,this thesis designed and established an underwater flux-cored wire arc transverse cutting device.The arc sensing system was used to monitor the cutting process,and the stability of the cutting process was judged through the current voltage waveform and distribution histogram.The results showed that changes in cutting parameters could cause changes in the average position of the arc,thereby affecting the kerf morphology.Among them,an increase in cutting current and cutting speed would reduce the width of the reverse kerf,while an increase in cutting voltage would increase the width of the front kerf.When the current and voltage were increased,the arc extinguishing rate during the cutting process increased,and the cutting stability deteriorated.Increasing the cutting speed could reduce the arc extinguishing rate,but excessive cutting speed could lead to a decrease in the quality of the kerf morphology.Compared with underwater flat cutting,smaller cutting parameters at the transverse cutting position could obtain better quality cuts.Under the same parameters,the perforation time of transverse cutting is shorter and the cutting process is more stable.Secondly,in order to explore the formation mechanism of underwater arc transverse cutting,two high-speed camera observation methods were designed to observe the cutting process.The analysis results indicated that due to the aggregation of molten metal on the lower side of the kerf and the influence of airflow and flame on the upper side of the kerf,the arc heat effect was asymmetric on both sides of the cutting wire,making the upper half of the kerf wider than the lower half.During the cutting process,the molten metal could not be discharged in a timely manner due to the constraint of bubbles,and always flowed out of the bubbles with the upward separation of the bubbles.The discharge direction was consistent with the main overflow direction of the bubbles.The main form of droplet transfer was fine droplet transfer,accompanied by a small number of large droplet rejection transfer.Fine droplet transfer was beneficial for the stability of the cutting process,while large-sized droplets could have adverse effects on arc stability.During the cutting process,the arc not only moved in a circular motion in the direction of the workpiece thickness,but also swung up and down under its own adjustment,increasing the width of the kerf and promoting its formation.This article studies the forming process and mechanism of underwater flux-cored wire arc transverse cutting,which helps to promote the wider application of this method in the field of underwater cutting.