Research On Holographic Interference Of Ultrasonic Assisted Welding Arc Plasma

With the rapid development of modern industry, reducing production costs and improving the performance of the product has become a hot topic of social concern. TIG welding has been widely used in aerospace, automobile manufacturing, shipbuilding and other fields. However, in the practical application process, there are many defects in TIG welding, the use of ultrasonic assisted TIG welding can effectively improve the defects of TIG welding process, so it has broad prospects for development. In terms of the mechanism of interaction of ultrasound and arc plasma mainly stay in the theoretical study in recent years. The Mach-Zehnder interferometric method and double exposure holographic interferometry is used to study the arc plasma in this paper, the whole field information of the arc plasma was detected and analyzed in the condition of no contact and no influence on the internal state of the arc plasma.By using the Mach-Zehnder test method, the interference experiment of TIG arc plasma under different welding parameters was carried out, and the interference fringes of TIG arc plasma were photographed. With the increase of welding current, arc temperature gradient increases. If the arc length is too long, the protection gas will lose the protection of arc region. Less protective gas flow can’t resist the invasion of the external air to the tungsten electrode, and more protective gas flow can cause instability in the arc space.The effect of ultrasonic on the gas environment was studied by using the two exposure method. After the optical path is improved, the interference fringes are obtained and the data acquisition is easy to be reconstructed. Based on the finite element software COMSOL, the sound pressure distribution of the sound field radiated by different shapes of the emitter is simulated, the concave spherical surface is selected as the optimum emitter shape. The test results are verified by holographic experiments. When the height of the transmitter is deviated from the resonance height, the energy of the sound field will be attenuated. The increase of ultrasonic current will be accompanied by the increase of the energy of the sound field, and the range of the sound field will also increase. After access to the protective gas, the greater the gas flow, the weaker the energy of the ultrasonic wave to the argon gas flow.Holographic experiment of the two exposure method of the flame field was carried out. After processing the fringe patterns, the temperature distribution of the flame field was calculated. By comparing the calculated data with the thermocouple measurement data, the results show that the detection accuracy of the two exposure method is very high, which is suitable for the non-contact diagnosis of arc plasma.The hologram of Ultrasonic-TIG arc was taken to compare the changes of arc plasma under different parameters. Ultrasound can make TIG arc stiffness increases and arc shrinkage is obvious. The greater the ultrasonic current, the smoother the interference fringes and the protective effect of the protective gas is better. When the gas flow rate is too small or too large, the protective effect will be reduced, which is consistent with the experimental results of Mach-Zehnder interference test.