Study Of On-Line Quality Diagnosis Technique In Rail Flash Welding Process

The welding of the steel rail is a key technology in express railway's laying process. The alloy steel rail, which is used widely in the railway engineering in our country, has poor weldability although it has high intensity and excellent wearing capacity, and the means of quality control in rail welding equipment is still not perfect, which leads to the hidden safety trouble in railway. Therefore, it is very important to research on-line quality diagnosis technique in rail flash butt welding process systematically.Aiming at the problems of the K190JIK rail welding machine, that the parameter modification is difficult, the welding process is not enough stability and the welding machine has no on-line diagnosis function, In this paper, the control system of the welding machine was promoted completely adopting the FX2N-64MR programmable logic controller and the PCL-1800 data acquisition card, the DAS(Data Acquisition System) was set up by using LabVIEW and Visual Basic software, the functions of welding voltage stabilizing and adjusting, current controlling and intellectual modification was improved, welding quality diagnosis system was built up, and the assembling and debugging of the control system was completed, including the process experiments.The result shows that the new control system has convenient parameter modification, perfect controlling flexibility, rapid dynamic response speed, stable welding procedure; The DAS of welding parameters has strong ability of anti-disturbance and the data is reliable. The control effect and practicability of the diagnosis system judging the welding quality are both good by using the characteristic values of welding process such as the percentage of the flashing time. Gray-spots flaw in flash welding joints of rail is the least when the pole moves to and fro at the same velocity and the speed is slow.