Study On Manufacturing Techologies Of Switch Rail Of High-Speed Turnout

High smoothness is the basic of increasing train’s speed when passing through turnout, of improving the passengers’ comfort and of ensuring the train’s safety. So the manufacturing accuracy of high speed turnouts is very highly required. The switch rail is the key component having great effect on the smoothness and security of turnout, the manufacture of which involves forging, heat treatment, machining and other aspects. The negotiation speed of the traditional switch was too low, so the accuracy of switch rail was not high. The manufacturing technology of it was relatively backward and has been already unable to meet the manufacturing requirements. In this paper, according to the lack of manufacturing technology of switch rail, based on the manufacturing experience of turnouts at home and abroad and analysis of the key processes, the manufacturing process and the quality control measures of the high-speed switch rail are put forward. The research work is divided into the following areas:(1) Through analyzing the influence of the heating time, the heating temperature and the forging temperature in the process of forging rail heel-end on the decarburized layer of rail head and fracture surface, combined with the gas composition in furnace, the beginning and final forging temperature of switch rail heel-end of the high-speed turnout, heating method and forging process of the heated three-step molding are put forward.(2) This paper analyzes the reason that the existing switch rail quenching process is likely to cause abnormal microstructure, the uneven end hardness and the warpage after quenching. Through experiment and comparison, some process are proposed, which include the simple blowing process of the switch rail quenching, reducing the cooling rate during the quenching heel-end process, as well as to impose preflex anti-deformation process.(3) Based on the analysis of the impact of temperature, tension and measurement state on the rail length, it is not suitable for high-speed turnouts length accuracy requirements to measure manually rail length. In accordance with the principle of temperature compensation, the program about the digital control of the rail is proposed, which measure on the temperature of reference rail.(4) Based on the study on the effect of cutting force, the contour of rail head, milling knife point on the smoothness of switch rail in the milling process, the paper proposes reasonable cutting parameters, tools, frocks, process improvement methods and knife point circular interpolation methods, which control the contour of rail head.