Design Of Water-cooled Ultrasonic-TIG Welding Torch And Numerical Simulation Of Acoustic Distribution In Molten Pool

The method of Ultrasonic TIG hybrid welding(U-TIG) has advantages inimproving the microstructure and properties of weld, as well as increasing weldingefficiency. This project conducts water-cooled design based on the existing UltrasonicTIG hybrid welding system and solves the problem of instability in welding processcaused by easy overheating of the ultrasonic horn. The capability of bearing largewelding current and single-channel welding length by U-TIG welding are enhanced.Welding efficiency is increased. Meanwhile, with ultrasonic vibration included in theprocess of welding, this project adopts numerical simulation to study the distribution ofultrasonic field in welding temperature field.Practical design has been done to the existing Ultrasonic TIG hybrid welding.Firstly, cooling design is conducted for ultrasonic horn. The shape and design proposalof horn are selected. ANSYS software is employed to determine the reasonable size ofthe horn with cooling water, so that the reliability of horn’s resonant frequency isguaranteed. It’ has been proved the cooling water reduces the ultrasonic effect slightlyby4%, while the cooling effect of ultrasonic horn is obvious. Then tungsten clip isdesigned to guarantee the flexibility of tungsten electrode, and meet the needs of electricand heat conduction in the process of welding. In the meantime, tungsten coolingsystem is designed. According to temperature measuring experiment, the cooling effectis obvious when the tungsten clip approaches arc, with temperature reducing by onethird.Experiment is conducted on the Ultrasonic TIG hybrid welding torch. When largecurrent is applied, the cooling effect of horn is fine, welding process stable and lengthfor welding apparently improves. The compound welding torch’ s bearing capability oflarge current are explored: stable welding of single-channel continuous weld stablewelding lasts for3min in160A,2min in180A and50s in200A, which reaches thebearing limit. After that, large current’s influence on ultrasonic effect is researched. It’sindicated that ultrasonic effect decreases with the increase of current.Finally, ANSYS software is applied to study the distribution of sound field in basemetal and in molten pool. By comparison, it is shown that the sound field mainlyconcentrated in the molten pool through the solid-liquid coupling surface reflectanceand temperature interface reflectance。The overall distribution of sound field intemperature field is in close agreement with temperature field, and varies periodicallywith ultrasonic vibration. It’s shown that in temperature field, the strongest effect ofsonic wave exists at the bottom of sound field through transmission focus. Besides, sonic wave declines gradually along the direction of temperature field’s surface gradient.Gradient distribution takes on periodic variation with ultrasonic vibration. Temperaturefield has a great effect on the distribution of sound field. The overall distribution ofsound field in temperature field is in close agreement with temperature field, and variesperiodically with ultrasonic vibration.