Simulation Of Physical Properties Of Droplet Transfer In Ultrasonic Assisted MIG Welding

Ultrasonic is a kind of mechanical vibration,and it is also an energy carrier.The use of ultrasonic mechanical vibration,energy,acoustic cavitation,acoustic flow and other nonlinear effects in the welding process can effectively improve the welding efficiency and welding quality.The welding process involves chemistry,physics,materials,heat transfer and other aspects,which is a very complex process,and it is difficult to analyze it in the actual welding.Therefore,this paper uses the calculation simulation software FLUENT to simulate the physical properties of droplet transfer in ultrasonic assisted MIG welding,and analyzes the differences in physical properties between conventional MIG welding and ultrasonic assisted MIG welding,so as to provide a theoretical basis for further tensile ultrasonic hybrid welding technology.In this paper,a two-dimensional asymmetric mathematical model of ultrasonic assisted MIG welding droplet transfer is established based on the theory of hydrodynamics,electromagnetism and the force in the process of droplet transfer.The model is redeveloped by using the user-defined equation UDF,and the ultrasonic vibration is introduced through the moving grid module in the software.The droplet transfer process of conventional MIG welding and ultrasonic assisted MIG welding under different current conditions is simulated and analyzed.The results show that the transverse vibration frequency of the welding wire can be effectively improved by adding ultrasonic drops at the welding end;The droplet height when it falls off is less than that of conventional MIG welding.The velocity field and dynamic pressure field in droplet transfer are analyzed.The results show that eddy currents will occur on both sides of the droplet transfer process,and the velocity and dynamic pressure of the central axis droplet are lower than those on both sides of the droplet affected by surface tension;The speed and dynamic pressure of ultrasonic assisted MIG welding are significantly higher than those of conventional MIG welding,and the transverse shear force brought by ultrasonic will make the droplet produce centrifugal movement.It shows that ultrasonic has a positive effect on MIG welding.In order to verify the reliability of the mathematical model established in this paper,an experimental verification platform of ultrasonic assisted MIG welding is built in this paper.The droplet transition process was photographed by high-speed camera,and the transition processes of conventional MIG welding and ultrasonic assisted MIG welding were compared and analyzed in the experiment and simulation.The results show that the addition of ultrasonic transverse vibration promotes the droplet transfer,and the radial radius of the droplet is reduced under the action of transverse ultrasonic.Finally,the shape and contour of the droplet are roughly the same as the simulation results through image processing,which verifies the accuracy and reliability of the droplet transfer mathematical model of ultrasonic assisted MIG welding established in this paper.