Development Of Welding Fume Measurement System And The Experiment Of Fume Formation Rate

Arc welding plays an important role in our native aerospace,high-rise building,nuclear energy,ships and so on.Among them,CO₂ gas shielded welding is widely used and developing rapidly in industrial production.However,the welding fume which is harmful to human health during welding process can not be ignored.And the most serious is that the fume emission problem of flux-cored CO₂ gas shielded arc welding.In order to reduce the FFR?Fume Formation Rate?,it is particularly important to study of the influence of welding process parameters on the FFR,discuss the fume generation mechanism of welding fumes,and further study measures to reduce the FFR.It is a crucial step to develop a welding fume measurement system that meets international standards,satisfies the test requirements,and make the FFR measurable.The welding-fume-measure system is divided into the structure of measure device,data acquisition and control system.The structure design of the welding fume measure device includes the filter paper clamping device,the hand hole device,the motion control device,and the pumping system,etc.The filter paper is easily loaded and unloaded during the test.The fume formation rate can be measured in GMAW?Gas Metal Arc Welding?and SMAW?Shielded Metal Arc Welding?.The data acquisition and control system can meet the requirement of acquisition precision.The system can collect the changes of welding parameters in real time and record and store the data.The measurement of fume formation rate is fully automated in GMAW.Based on the developed testing device for welding FFR,the effect of welding parameters on the FFR is discussed through orthogonal test and single factor test on automatic CO₂ gas shielded welding with flux cored wire.The test scheme is aimed at four kinds of technological factors,which are welding current,welding voltage,welding speed and shielding gas flow.The orthogonal test results show that the most significant factor affecting the welding dust rate is the welding current.At the same time,the welding process scheme with the lowest FFR is obtained by intuitionistic analysis of the test results.Based on the optimal process scheme,through the single factor test,the results show that the welding FFR increases with the increase of welding current and welding voltage,and the increase of welding speed usually makes the welding FFR decrease.With the increase of wire feeding speed,the welding FFR is also increasing.Based on the welding fume collected under the above different welding conditions,the two groups of fume particles with the maximum and minimum welding current were detected by two methods of TEM and SEM-EDS,respectively.The appearance,particle size distribution and composition of the welding fume were observed.The results show that the particle size distribution of welding fume is generally in the range of10nm¹61nm,mainly composed of spherical,chained,and ring structures.The results of fume composition test showed that most of welding fumes existed in the form of metal oxides,of which the most content was Fe,followed by Mn.Through three aspects of the formation process,the metal evaporation mechanism of welding fume and the analysis of the condensation of welding fume,the generation mechanism of the welding fume is discussed,and the existence of most of the oxides of metal such as Fe2O3 and Mn₃O₄ is expounded.By analyzing the influence of welding process parameters on the welding FFR,the measures to reduce the FFR are discussed,which can effectively control the generation of welding fume and lay a foundation for the development of low fume and environmental protection welding materials.