Research On Electromagnetic Induction Heating For Online Residual Heat Air Cooling Quenching Of 100m Rail

The rail is an important part of the rail system.With the continuous increase of the axle load and running speed of the train,more stringent requirements are put forward for the performance of the rail.On-line waste heat air cooling quenching is currently the most advanced heat treatment process for 100-meter rail.The quenching temperature has a significant impact on the performance of the rail after quenching.Due to the long length of the 100-meter rail,the natural air cooling time experienced by each part of the rail before entering the quenching unit is different,resulting in the difference in the quenching temperature,resulting in the difference between the front end and the rear end of the rail after quenching.The structure,hardness and mechanical properties are quite different,which affects the performance uniformity of the rail.In order to reduce the difference in the quenching temperature of the100-meter rails,the method of electromagnetic induction supplementary heating is adopted to achieve the goal of basically the same quenching temperature of the100-meter rails.Therefore,the research on electromagnetic induction supplementary heating of the rails is carried out.The effects of induction coil design parameters(coil turns,shape,and geometric dimensions)and supplementary heating process parameters(current density,current frequency,and spacing)on the temperature field uniformity and heating efficiency of rails after supplementary heating were studied.According to the outer contour of the rail head,the profiling induction coil model was preliminarily established,and the electromagnetic-thermal coupling heating model of the rail was established based on the finite element analysis software,and the heating process of the rail was simulated,and the effect of the induction coil design parameters on the heating was studied.The influence of the temperature field uniformity and the heat supplement efficiency,the optimal design parameters of the induction coil are obtained;on this basis,the influence of the heat supplement process parameters on the temperature field uniformity after the supplement heat is studied,and the optimal heat supplement process parameters are obtained.;Finally,the uniformity of the temperature field of the moving rail after electromagnetic induction heating is studied under the conditions of optimal induction coil design parameters and optimal heating process parameters.The results show that the temperature difference between the front end and the rear end of the rail head after supplementary heating is about 20 °C,and the temperature difference is reduced by 60% compared with that before no supplementary heating.The temperature difference of the cross section is controlled at about 22 °C,and the temperature difference is relatively reduced by 46%.Significantly improved the problem of non-uniform temperature in the longitudinal and cross-section of the rail before quenching.Finally,the induction coil was fabricated according to the optimal design parameters of the induction coil,and the rail electromagnetic induction heating experiment was carried out.The experimental results were basically consistent with the simulation,which verified the accuracy of the simulation.This research can provide a reference for the design of the induction coil for on-line residual heat air-cooled quenching of the 100-meter rail and the formulation of the supplementary heat process parameters.