The Techniques Of Pipe Welding Arc Length Control Based On Controlling Network

As the usage amount of submarine pipe increasing, the requirement of quality improves. High quality and efficient welding operation, used in submarine pipe laying, is important to ensure the submarine pipe system safe. Arc length fluctuations of welding process are caused by pipe ovality, orbital deformation of welding car, and unsmooth filler course of multilayer weld filler, and led to the decrease in the quality of welding. In the actual welding process, instability of the welding current results from fluctuations in the level of welding torch position, and contains a large lag which increases the difficulty of control.The linear relationship between the welding current and arc length is concluded, through the analysis of arc static characteristic and dynamic characteristic of constant voltage and ramp down characteristics of welding power source. The proportionality factor of linearity is got by fitting the data of current and arc length collected in the flat welding experiment. According to the structure of the mathematical model of the arc length, the hysteresis control selects lag time disrupters. Welding torch height servo motor system model is deduced by theoretical analysis of the motor ontology and servo drive system. The whole model of pipe welding arc length control system is set up, and experiment on digital simulation. The control algorithm is applied to the actual pipeline welding arc length control system platform, which is based on CAN bus is constituted by welding torch, welding carriage, main control system, welding power supply system and level servo motion systems.Simulation experiments show that appropriate lag factor can weaken the influence of the lag, current overshoot amount of pipeline welding arc length control is reduced to10%, and adjust the time is less than2s. Welding current closed-loop control adopts segmented regulation strategy based on feedback or input bias, by comparing with traditional PID regulation, thereinto PID segmented control method according to the feedback value can further reduce the overshoot of the welding current, and speed the adjustment time. X-Y platform experiments show that Welding torch height device is driven by the measured current fluctuating in the range of less than±0.5mm. Pipeline welding arc length control system is proved to have good dynamic characteristics and steady state characteristics.