Optimization Of Process Parameters For Laser Wobbling Welding Of Aluminum Sheet For Low Carbon Manufacturing

Aluminum alloy has the advantages of light weight,high specific strength,good formability and corrosion resistance.As an excellent lightweight material,aluminum alloy has been widely used in the field of automobile manufacturing.However,due to the special physical and chemical properties of aluminum alloy,the welding seam is prone to weld porosity defects.As a new type of laser welding technology,laser wobbling welding can improve the stability of the keyhole and promote the flow of the molten pool through the wobbling effect of the beam,which is helpful to improve the quality of the weld forming and suppress the welding porosity defects.It provides a new technical means for the lap welding of aluminum alloy sheet.In recent years,the environmental situation has become increasingly serious,and it has become a global consensus to reduce the carbon emissions from manufacturing.However,the carbon emission characteristics of laser welding process have not been deeply understood,and there are few studies on the optimization of laser welding process parameters for low-carbon manufacturing.This paper constructs the 6061 aluminum alloy sheet wobble lap laser welding carbon quantitative method,approximate modeling method based on gaussian process output was used to construct aluminum alloy laser wobbling welding of low carbon manufacturing model,on the basis of the NSGA-II to approximate model of the optimal process parameters combination of expectations,aims to ensure welding quality and reduce carbon emissions,It has a certain guiding significance for the optimization of laser welding process parameters for low-carbon manufacturing.The main work of this paper is as follows:(1)A low carbon manufacturing problem model for laser wobbling welding of aluminum alloy based on multi-output Gaussian process(MOGP)was established.(1)A quantitative method for the emission of laser wobbling welding of aluminum alloy was established.The characteristics of energy consumption and material consumption in the laser wobbling welding of aluminum alloy were analyzed,and then the quantitative formula for carbon emission in the laser wobbling welding of aluminum alloy was deduced.(2)A low carbon manufacturing problem model for laser wobbling welding of aluminum alloy was constructed based on MOGP: Port correlation analysis shows that there is a certain correlation between laser wobbling welding results(penetration depth,lap surface width,maximum bearing capacity and carbon emission).Therefore,the relationship between laser wobbling welding process parameters and welding results is accurately characterized by using the MOGP approximate modeling method.The relative errors of the approximate model at random sample points for the prediction of penetration depth,weld width of lap joint,maximum joint bearing capacity and carbon emission are5.24%,5.51%,5.86% and 2.69%,respectively,and the average relative errors are 3.86%,and the prediction accuracy is higher than that of the approximate modeling method based on SOGP.It is proved that the proposed approximation model has high precision prediction ability,and has some advantages over the SOGP-based approximation modeling method.(2)Based on NSGA-II,the low carbon manufacturing problem of laser wobbling welding of aluminum alloy was solved,the prediction accuracy of the model was verified,and the welding joint performance and process parameter factors of the optimized results were analyzed.(1)In the optimization results,the maximum error of melting depth is3.7%,the maximum error of melting width of lap joint is 15.2%,the maximum error of maximum carrying capacity is 7.5%,and the maximum error of carbon emission is 2.0%.The relative errors of the four targets are all less than 20%,and the average relative error is 5.1%.It is proved that the optimal parameter combination obtained by the multi-objective process parameter optimization method for low carbon manufacturing problem of laser wobbling welding of aluminum alloy based on the approximate MOGP model has high precision.(2)Compared with the random process parameters,the optimized process parameters can effectively improve the forming quality of the weld,inhibit the surface porosity,pool collapse,concave,porosity and other welding defects,effectively improve the microstructure and strength of the weld,carbon emission is reduced by 8.4%,and the maximum bearing capacity of the joint is increased by 7.1%.(3)The micro-hardness of the weld fusion zone is the smallest,and there is obvious softening phenomenon between the weld fusion zone and the heat-affected zone;The grain in the fusion zone of the optimized group was refined.(4)The laser power has a significant promoting effect on the penetration depth;The cross factor of laser power and wobbling amplitude has a significant promoting effect on the fusion width of lap interface.The laser power-wobbling frequency cross factor and the laser power-wobbling amplitude cross factor can promote the maximum bearing capacity of the joint to some extent.Welding speed has a significant negative contribution to carbon emission.