Research On Attitude Adjustment And Positioning System Of Welding Gun In Ultra-narrow Gap Welding Of Rails

With the extensive laying and long service of seamless railway,the frequency of rail damage increases.Damaged rails are treated differently according to the severity of the damage.For general surface wear and deformation,etc.,it can extend the service life of 50-100% by grinding to correct and control;For more serious fracture,internal nuclear injury etc.,it is necessary to replace the rail directly or to cut it in situ and stretch it before welding.The system of rail welding has problems such as large equipment,low efficiency,and poor joint quality.Ultra-narrow gap welding has attracted attention due to its low line energy,high production efficiency and good joint strength.Therefore,based on the flux-constrained arc ultra-narrow gap welding method,a set of rail in-situ welding automation equipment was developed.The harsh environmental conditions on the rail laying site put forward higher requirements for the mechanical structure design of the device.After a variety of schemes demonstrations,the article finally adopts a cantilever beam structure and mounts the equipment on the rail pillow.The advantage of this structure and installation method is that the device is small in size and easy to move,and after use,the mechanical arm can be rotated to the outside of the rail through the rotating mechanism,and leaves more space and time for post-welding grinding,slag removal and other work.The basic control idea of the equipment is to improve the efficiency of parameter setting with the help of PLC controller on the basis of the original simulated welding machine,so as to improve the welding efficiency.Around this core idea,this paper improves the original simulated welding machine.The manual continuous adjustment of preset parameters is replaced by automatic discrete adjustment,and the influence on the characteristics of welding machine is minimized.In the aspect of hardware,the key input circuit and output control circuit are designed;In software aspect,the program design of key input,parameter switching,welding torch trajectory and overall PLC program design have been completed.It is initially realized that the operator only needs to input the groove width value,and the preset voltage,current and welding speed parameters will be “followed” automatically,which greatly reduce the technical level requirements for the operator.Through sensors,data acquisition card and computer software,real-time acquisition and storage of welding process data is also realized,which lays a foundation for subsequent analysis of welding quality and finding the best welding matching parameters.After the problems found in the previous tests,this article also improved the design of the rail ultra-narrow gap welding plate arc welding gun,improving it's stress and insulation performance.After the assembly of the equipment was completed,the commissioning and welding tests were carried out.Combined with the weld profile,quality and data analysis,the welding procedure specifications applicable to the equipment were found.The welding data was further analyzed,and the relationship between the metal transfer mode and its electrical parameters in the ultra-narrow gap welding process was discussed.