| With the continuous development of marine resources,the demand for high-quality underwater cutting technology is increasingly urgent.Due to the advantages of simple equipment,high efficiency and low comprehensive cost,the underwater melting electrode flux core cutting method has wide application prospects.When cutting in seawater environment,it is found that the higher conductivity of seawater causes the loss of cutting current through seawater(called leakage current),which will seriously affect the cutting quality and arc stability.Therefore,this thesis studies the leakage current detection and its laws in the seawater cutting environment.First,in order to effectively detect the leakage current of underwater cutting,a leakage current detection system is designed and built.Among them,the detection tank provides an environment for the detection of underwater cutting leakage current.The detection plate is the core component,which is installed at the bottom of the detection tank.It is divided into a cutting area and an uncut area by an insulating sheet.The cutting area is the detection area,which is used for the acquisition of leakage current;the electrode wires are drawn between each area to divide the entire cutting circuit into multiple different cutting circuits.During cutting,the leakage current lost through the seawater flows into the cutting circuit through the detection area.Then it is acquired by the data acquisition module and the detection is completed.Secondly,a data processing and analysis method is proposed: draw the acquired leakage current text data as a waveform diagram,process and extract the characteristic information of the waveform diagram through the combined filtering of "median value +smoothing",calculate the leakage current value of each detection area,and obtain the leakage current value of each detection area.Current distribution histogram,line graph of leakage current in each detection area and decay rate.In addition,the leakage current detection system was tested.Thirdly,in order to eliminate the interference of other parameters,this thesis firstly carried out the research on the leakage current of the underwater non-melting electrode arc,and analyzed the main parameters affecting the leakage current,including seawater concentration,welding current,electrode height and electrode extension length,indicating the influence of different parameters on the leakage current.Finally,the research on the leakage current law of underwater melting electrode flux-cored cutting arc is carried out.The main conclusions are as follows:(1)Using the developed leakage current detection system,the evaluation of the leakage current size and distribution of underwater cutting is realized.(2)The influence of process parameters on the size and distribution of leakage current is clarified,in which the size of leakage current is positively correlated with seawater concentration,cutting current and arc voltage;its distribution has a concentrated growth phenomenon with the increase of cutting current.As the voltage increases,the overall distribution of the leakage current is more uniform,but beyond a certain range,the leakage current in the central detection area decreases;with the increase of the depth of the cut,the leakage current decreases;the leakage current is negatively correlated with the ceramic nozzle,indicating that the ceramic nozzle The installation has a control effect on the leakage current.(3)The linear regression equation of process parameters and leakage current is established,which can accurately predict the leakage current under different process parameters. |
