Design of a Narrow Gap Oscillating Hot Wire GTAW Seam Tracking System Based on Passive Vision

doi:10.3901/JME.2025.12.164

Abstract

Abstract: Narrow gap oscillating hot-wire gas tungsten arc welding (GTAW) is known for its efficiency, environmental friendliness, and high quality. It has been demonstrated to replace manual arc welding for welding the seams of the inner tank. Taking the example of a LNG storage tank, with individual inner shell seam lengths of approximately 12 meters, deviations in welding position due to beveling and assembly can lead to defects like incomplete fusion on the sidewall. Therefore, skilled welders are still required for real-time adjustment and control of the welding position during actual production. In order to avoid the instability of manual weld tracking and improve the automation of the welding process, a passive visual-based method for detecting bevels and arc positions is proposed. An optical system is established, along with an adaptive image feature enhancement algorithm to obtain high dynamic range images of the welding process. By detecting the stop positions on both sides of the tungsten electrode during oscillation, the central position of the tungsten electrode at the zero point is calculated. This information is then compared in real-time with the detected center position of the narrow gap bevel. Using a developed fuzzy control algorithm, real-time tracking and control of the arc position during the welding process is achieved. Experimental results show that：The established optical system can effectively capture passive visual images of the welding process, and the adaptive algorithm can increase the image grayscale difference from around 40 to approximately 120; By detecting the left and right stop positions during the welding gun oscillation and utilizing a feature extraction algorithm for the arc center position, the center position of the welding gun can be obtained twice within one oscillation cycle (1.13 seconds), with a single accuracy rate of over 80%; By comparing with the detected bevel center position, and using the established fuzzy control rules, real-time tracking and control of the welding process can be achieved in process trials, with an error accuracy controlled within ±0.3 mm.

Key words: weld seam tracking, passive vision, narrow gap, pulsed hot wire GTAW

CLC Number:

TG409

ZHU Ming, WENG Jun, ZHU Zhenwen, YANG Binhui, ZHANG Gang, SHI Yu. Design of a Narrow Gap Oscillating Hot Wire GTAW Seam Tracking System Based on Passive Vision[J]. Journal of Mechanical Engineering, 2025, 61(12): 164-172.

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