Reconstruction Of Control System And Research On Welding Process Of κ190Πκ Rail AC Flash Butt Weiding Machine

K190ΠK rail AC flash butt welding machine is still be used for their simple structures, convenient maintenance and low maintenance charges. It belongs to fixed continuous flash welding set which was imported from Former Soviet Union.Welding Research Institute of Southwest Jiaotong University made the former reconstruction of the control system of the machine since it couldn't meet the demand of welding production. The control system was composed of PLC to control the welding progress and computer to monitor and control the welding parameters.But the system still had shortages through applications as follows: 1) Practicable process rang was narrow when using a set of thyristors to regulate welding voltage. 2) The welding period signal was discriminated through the encoding mode of relays, which was easy to be interfered. 3) The welding process was controlled by time, which made welding quality fluctuation due to flashing allowance unstable in each period. 4) The supervisory control system and the parameter modification system were not compatible because they were developped by different software. New control system was designed as follows: 1) The main loop voltage of High Voltage Stage and Low Voltage Stage is controlled separately by double sets of thyristors. 2) The welding period signal comes from the PLC directly by RS-422. 3) The welding process is controlled by flashing allowance, which made flashing allowance stable. 4) New Human-Computer Interaction desktop application program was developped by Visual Basic to unify modification of welding parameter and running platform of supervisory control program. After finished reconstruction of the welding machine according to above project, the weld which was welded by using method combined proportional control and ON-OFF control to control feeding speed and process of highest output power wasapproved by Drop Weight Test according to TB/T1632-91.After a year of application, the results show that the new control system enhance thermal input power and production efficiency greatly and economize great quantity of electric power with large adjustable voltage range, high precision, high anti-jamming ability and auto compensation on mains voltage.