Process And Device Of Wire Filling Fiber Laser Overlaying Welding For U71Mn Rail

This paper studied the damage mechanism rail, electric arc welding on the advantages and disadvantages of rail line repair techniques were compared, and then low absorption rate and laser power shortage of the rail surface wire filling repair technology of CO2 laser as heat source was carried on the detailed analysis.A set of independent laser wire filling welding test platform was built up with lasers, robotics and wire feeder. Single pass welding experiments were performed and the wire was fed by side. The optimal parameters of wire filling repairing in worn rail was determined by the study of microstructure and weld surface formation of the repaired rail steel.Moreover, multi-layer and multi pass welding experiments were performed on the rail surface by the optimal parameters of wire filling repairing. The optimal overlap rate and repair method of wire filling repairing in worn rail were determined by the study of microstructure and weld surface formation of the repaired rail steel.Then, hardness testing of the repairing layers of the three groups experiments was made. And the tempering of the welding bead could grain refining size and improve the microstructure of the weld zone. In this thesis, the tempering at different temperatures were used to rapidly remove the remain martensites in the worn rail, which ensured the low hardness of tissue hardness and high quality of the repaired rail steel.In the end, according to the repair process, many designs of the rail online repairing device were proposed. The optimal design is the monorail repair machinery in four-wheel staggered type.