关键词: 钢轨焊接, 焊接电流, 焊接速度控制, 弧长控制

Abstract: An automatic rail narrow-gap arc welding system is developed for in-situ welding of seamless railroad. It is found in the welding process that the welding current and voltage are unstable, and which is adverse to welding quality. Considering the technological features of rail narrow-gap arc welding, the reason of the problem can be related with some aspects, including anomalous shape narrow-gap seam of rail with ceramic backing, protruding angle of welding wire, anomalistic welding track and welding speed and so on. Besides the controllable parameters, i.e. welding current and voltage, experiments show that the variation of welding speed is also a controllable parameter which has an effect on the actual welding current. By using welding current feedback to control the welding speed and torch altitude, the arc length control system is established. With real-time welding current feedback, segment PID control is adopted to drive the welding torch in different aspects with different speed. The welding experiments show that the realized system can smooth the fluctuation of welding current and voltage, and at the same time it stabilizes the arc burning and reduces metal spattering. And it works well especially in avoiding arc faults during the backing welding.

Key words: Arc-length control, Rail welding, Welding current, Welding speed control