Impact Assessment And Numerical Simulation Analysis Of Fume Collection Of Fume Extraction Gun

As a widely used material processing method,GMAW brings not only convenience for production and processing,but also pollution.Welding fume is the most important pollution,which affects the environment and human health.In this paper,we will evaluate the new way of controlling welding fume by means of experiment and numerical simulation,which will lay a foundation for the research of fume generation mechanism and the structure and process design of Fume Extraction Gun in the future.Fume Extraction Gun(FEG)is a device that integrates the fume control device into the welding gun.When the fume generated,it is captured by the extract opening at the upper of the nozzle.The FEG is generally used in conjunction with the Fume Extraction system.When the Fume Extraction system is turned off,the FEG is the same as the ordinary melting electrode arc welding torch.Compared with other similar local fume extraction equipment,the FEG can follow the source of fume in real time as the welding process.This product is suitable for welding in a narrow space and suitable for use with a welding robot.The FEG was first developed in the United States and European countries in the 1980 s.but it not had much influence in China.This article uses a 7XE FEG and a Clear O2 Fume Extraction system to perform carbon dioxide gas shielded arc welding tests.Through the observation of arc morphology and fume diffusion morphology,welding current measurement,high-speed camera analysis of droplet transition,observation of weld and its surface splash,X-ray flaw detection of weld defects and test of weld tensile properties,the impact of using FEG on welding process and weld quality is analyzed,so as to evaluate the smoking effect.Then,using the simple arc model of MIG welding with FEG,the characteristics of arc plasma such as current density distribution,electric potential field,temperature field,velocity field and iron vapor concentration were analyzed by numerical simulation to study the fume extract behavior and its influence on welding arc.Four typical fume extract levels were used to evaluate the extract behavior and its influence on the welding process and welding quality.The results show that the fume diffusion is obviously reduced and the droplet stability is slightly worse by extracting,but the influence of extracting and its level change on the average value of welding current and voltage can be ignored.When the extract function is turned on,the gas flow around the arc will be accelerated,the arc and droplet will be cooled,the arc will contract slightly,and the droplet transition frequency will be accelerated.At the same time,the contraction of the arc also makes the concave at the front of the molten pool increase,and the inclination of the liquid metal surface at the back of the molten pool increase,which shortens the arc length to a certain extent,which also shortens the droplet transition period and slightly increases the droplet transition frequency.Extraction will not produce obvious welding defects,but will make the weld yield strength slightly reduced,tensile strength slightly increased.According to the welding test of different shielding gas flow,the results show that the welding results and extract control can be guaranteed within the selected shielding gas flow range.When extract is applied the shielding gas should be increase slightly,in order to obtain stable welding process and good welding quality.The two-dimensional axisymmetric MIG arc numerical simulation analysis of FEG was carried out by using iron vapor instead of fume.The results show that the plasma characteristics of pure argon arc are changed when the iron vapor is taken into account.In the mixed atmosphere,the current density and potential increase,while the arc temperature increases due to the radiation caused by the static emission coefficient and mole fraction of iron vapor at high temperature,and the arc temperature decreases.When extract is applied,the plasma characteristics in the center of the arc will not be significantly affected,but the air reflux speed in the area below the extract port will be accelerated and the temperature will rise slightly.