Development Of Elliptic Track Monitoring Mechanism And The Control System

In order to ensure the stability of tanks, the cross‐section of the oil tanks and other liquid tankers are designed as elliptical track. In the welding process of elliptical joint, it is difficult to fulfill the motion trajectory control of the torch. With the improvement of automation control technology, developing automatic welding equipments for irregular tracks with low costs and high welding quality has become the goal of many investigators.The torch path planning is proposed based on the elliptical model of the oil tanks in this paper. The track detection mechanism is composed of detecting wheels,2encoders, connecting rod, fixed plate, torch connection mechanism and pressure spring. During the welding process, the detecting wheels rolled along the welding joint, the change of trajectory parameters were analyzed based on the output signals of the encoders, which provided reliable inputs for the control system. The paper chooses S7‐200PLC from Siemens Corporation as the core of the control system. The control system consists of PLC (CPU224XP), encoders’ signal acquisition circuit, three sets of AC servo drive and related welding control circuits. The system could realize the collection of welding tracks signal and the real‐time control of the torch action.Finally, series of experiments were conducted to verify the performance of the track monitoring mechanism. According to the experiments, the track monitoring mechanism could detect the welding track with high accuracy and stability. The compensation for the torch orientation acquired from the monitoring mechanism could meet the requirements of general welding, which optimize the design of the torch drive mechanism and reduce the equipment costs effectively. In addition, the motion parameters of the torch were obtained during the welding process and provided guidance for further control of the welding torch.