Proposal of a Method of Observing Cathode Spots in AC Tungsten Inert Gas Welding

Abstract

We propose a method of observing the generation of cathode spots at arbitrary times during AC tungsten inert gas (TIG) welding. The observation system includes a high-speed video camera and multi-data acquisition system. First, to accurately observe cathode spots generated during AC TIG welding, we synchronized the data logger and high-speed video camera. Next, in setting the start time for photography by the high-speed video camera, a time delay was set. The observation of cathode spots in the AC TIG welding of pure aluminum confirmed that we could accurately observe the cathode spots generated only during the tungsten electrode-positive polarity. In addition, we attached a timer immediately before the data logger in the system, and set a specific delay time because the system only allowed us to observe cathode spots during the early stage of the AC TIG welding process. The improved system allowed us to observe the generation status of cathode spots at any time during the welding process. The usefulness of the proposed cathode spots observation system was thus verified.