Research On Key Technologies Of Welding Repair Of Groove Rail

To make modern tramcars can run with other vehicles on the same way,engineers usually using the special groove rails to lay the embedded track in the street.It is complicated and expensive to repair the abrasion and surface contact damage appeared on in-service rails by by replacing rails.This plan will severely impact day-to-day operations of modern tramcars,so it is significative to study high quality and efficient solution of welding repair of groove rails,develop automatic welding repair equipment and explore the welding repair process which are suitable for conditions of construction site.In this paper,after investigating the service conditions on existing lines and summarizing the operating experience of foreigner lines,on-site welding repair plan were put forward to solve the 6mm deep abrasion or less than 6mm deep surface contact fatigue by choosing the Rong second line as the research object.According to the requirements of the equipment function,the prototype of automatic welding repair equipment was developed,and the mechanical structure and electrical control system of the equipment were improved after the initial debugging.The welding repair process test was carried out by using this prototype.By contrast and orthogonal test,the best pre-welding and single-layer surfacing technology were determined.And then,the process of multi-layer surfacing was summarized and its feasibility was discussed.During the test,the influence of thermal effect on the performance of polymer damping materials was also assessed by monitoring the change of temperature of rail's jaw.The result shows that,the program proposed by this paper is more efficient with lower cost.The welding repair equipment can automatically finish the pre-welding and surfacing repair process,and the equipment control system is accurate so that the quality is good and stable.The welding repair process of this paper has good technical feasibility.Frist,the dimension of grooves processed by pre-welding processing are stable and uniform,and there are no cracks on the groove surface.Second,the 6mm deep abrasion or less than 6mm deep surface contact fatigue can be repaired by using the optimum single layer surfacing process parameters and multi-layer surfacing method.Welds are well formed,and the seams are tight,there are not unbonded,crack or stoma in the weld.The microstructure is respectively austenite and pearlite in the weld and heat affected zone.Third,hardness value ratios of weld and base metal are 1.10~1.25,hardness value ratios of heat affected zone and base metal are 1.10~1.23.Both of them are well matched to the parent material.Finally,the performance of polymer damping materials will not be destroyed during the welding repair.