Real-time Feedback Control for Uniform Weld Bead using Adaptive PID Controller with Infrared Image Processing in Fiber Laser Welding of Low Carbon Steel

DOI: 10.14416/j.ind.tech.2023.12.003

Abstract

Fiber laser has considerable advantages; that is, high melting efficiency, high power, and power density. However, during the welding process, if the thickness of the steel sheet is not stable or the process has a defect, this could affect the control. To make the continuity in welds, the research is intended to propose a quality control system for the real-time weld beads. The process involves the welding of the low-carbon steel sheet by laser fiber of varying thicknesses of 0.5 to 1.0 mm. The infrared image processing is used to determine the molten pool during the welding process. Then, this data is input to the adaptive PID feedback control system in order to control the width of the weld bead quality (Uniform Weld Bead). In this regard, the width of the molten pool is used as the main input parameter for controlling the power of the fiber laser in accordance with the steel sheet thickness. The research results indicate that the adaptive PID can control the power of the fiber laser so that the molten pool width is maintained within ±1.0 mm. accuracy from the setting point. Moreover, the experiment shows that the weld beads have full penetration and continuity. The standard deviations of the thickness adjustment in the 0.5-1.0 mm. and 1.0-0.5 mm directions are 0.22 and 0.23 respectively. Therefore, the feedback control technique is appropriate for the automatic laser welding of the worksheets with a thickness of 0.5-1.0 mm.