In process monitoring and control of automated TIG welding processes

Abstract:

TIG (Tungsten Inert Gas) welding is utilised in industry as a preferred choice due to its high quality, coupled with the ability to control the shape of the weld bead. In any thermal based material processing, in-process control of the melt zone is essential to achieve optimal process conditions. However, due to the harsh environments during the joining process, including high temperatures and plasma emissions, it remains difficult to monitor the process and react to any conditions which may prove detrimental to the desired properties of the joint. In most cases, the input current and/or arc voltage are monitored during the process to guarantee integrity of the finished joint, backed by destructive testing of sample joints to confirm the output. This research develops a closed-loop adaptive control system based on thermal imaging to address the fluctuations observed during the TIG welding process. The experimental setup comprised of a robotic TIG welding system, single wavelength IR (Infrared) thermal camera, a data acquisition system and an NI (National Instruments) based DAQ controller. The results show that the online monitoring and closed loop control of the TIG welding process can help to minimise defects and the proposed system can be readily adapted to any thermal based manufacturing techniques.

Download PDF