Research On Welding Characteristics Of Quasi-continuous Fiber Laser Bridge Wire Cladding

Traditional laser bridge wire welding is usually carried out by using xenon lamp-pumped Nd:YAG solid-state lasers.However,due to its low electro-optical conversion efficiency,complex optical structure debugging,high sensitivity to external influences on beam quality,poor stability of output power during continuous use,and low repetition frequency,it cannot meet the requirements of the pyrotechnic industry for high-quality bridge wire welding in the range of micrometers and sub-micrometers.Based on the problems in traditional laser bridge wire welding technology,this article established a numerical model of fusion welding,and researched the influence of laser parameters on the characteristics of molten pool.Obtained the key factors and welding parameter range that affect the quality of laser bridge wire welding.On this basis,constructing a new laser bridge wire fusion welding system based on quasi-continuous fiber laser source,and checked the theoretical parameters,which achieves good welding quality.Firstly,based on the theory of laser irradiation characteristics,established a two-dimensional numerical model of laser fusion welding.By studying the influence of surface tension coefficient on the morphology of fusion welds on the molten pool surface,it is found that when the surface tension coefficient is less than zero,the molten pool is easy to flow and forming better fusion weld points.By studying the absorption coefficient of different substrate materials,different laser pulse waveforms,different laser powers,and pulse widths on the molten pool temperature,it is found that when the laser power is in the range of 140 W-160 W and the pulse width is in the range of 1.0 ms-2.0 ms,the laser can achieve suitable temperature conditions for the fusion powder,substrate material,and bridge wire laser fusion welding points.To avoid some problems such as bridge wire pneumatolysis and broken due to excessively high molten pool temperature,or incomplete fusion due to excessively low molten pool temperature.As a result,obtained a parameter range suitable for the fusion welding of new quasi continuous fiber laser bridge wires.By constructing a quasi continuous fiber laser bridge wire fusion welding system,combined with numerical calculation results,and studying the influence of fusion powder on welding characteristics.Choose 300-mesh Ni60 alloy powder as laser fusion powder.By conducting laser fusion welding experiments on different substrates(304 stainless steel,1060 pure aluminum,H62 brass)and different wire diameters(20 μm,60 μm,100 μm),according to analysis the welding results,obtained the optimal fusion welding parameters for different wire diameters and substrate materials,ensuring that the bridge wire is not damaged due to pneumatolysis,obtained a good weld effect between the bridge wire and the substrate.This paper researched on the molten pool characteristics and welding parameters in quasi-continuous laser bridge wire fusion welding models,provided a theoretical reference for the optimization of laser bridge wire fusion welding areas.This research can improving the process quality of new micron and sub-micron bridge wire pyrotechnic products.