Study On The Mechanism Of Activity-welding Based On Visualization Test

Activating welding can greatly improve the weld penetration and thus enhance the process efficiency. But the efficient mechanism of activating welding research is still in the debate. The efficient mechanism of activating welding was studied by using visualization of arc and weld pool in this dissertation.The reasonable test scheme and test system was established. A welding line contains the TIG welding, A-TIG welding, laser assisted A-TIG welding and laser welding auxiliary activity results, which will improve the accuracy of the four welding method contrast. A CCD camera system platform was built by selecting the CCD camera, data acquisition card and the combination of optical lenses and other devices. The weld pool surface flow pattern video, weld pool video and arc video was obtained under the specific parameters, which will provide the raw data in the image information extraction and mechanism analysis.Multiple areas arc weld pool boundaries and boundary information have been obtained by processing arc and weld pool image via MATLAB image processing module.The surface of the weld molten pool flow pattern was studied, making the initial draw conclusions:Surface flow field direction of TIG welding pool as the center to the periphery, while the other active welded pool surface flow field direction for the surrounding to the center. The pool edge of four welding methods for extraction and analysis, because of the width and length of TIG welding pool are greater than the activity of welding, making the area much greater. While laser-assisted activity welding pool area is greater than A-TIG welding and laser-assisted A-TIG welding, the differences in the pool area give rise to the differences in penetration. The special edge extraction and analysis of four kinds of welding arc, making a conclusion that: A-TIG welding and laser-assisted A-TIG welding arc electrical contraction, energy concentration; while TIG welding arc welding and laser-assisted activity compared large energy spread.The experimental results show that arc contraction and changes in surface tension are efficient mechanism of A-TIG welding in the experiment. Efficient mechanism of laser-assisted activity welding is changes in surface tension, not arc contraction. The efficient mechanism of Laser-assisted A-TIG welding and A-TIG welding is arc contraction and changes in surface tension. Arc contraction is caused by activating flux, the changes in surface tension is generated by a laser-oxygenase-active agents and joint action. The mechanism of activating welding can not be explained by a single theory, which can be seen from the experimental results. The different process will lead to the different mechanism of activating welding.