Rail size tolerances and heat treated rails Introduction

Rail section size and flatness deviation is single girder  overhead gantry crane  rail an important indicator of quality. Such as the use-sectional dimension deviation is too large, poor flatness rail, then it is difficult to lay railway track quality. To ensure the smooth running of trains is required track geometry is stable, the wheel-rail contact rail head position and the width of the band of light stability, and to achieve this, a high-precision dimensions and flatness is essential rail indispensable.

    Because rail weld materials, microstructure, hardness, toughness, etc. The difference with the rail base metal, welding equipment, precision level of technical proficiency operating workers, etc., will result in single girder  bridge gantry crane  rail welding rail joints surface is not flat. Rail welded joints in three, contact welding, pressure welding and thermite welding. Three kinds of welding methods there are differences in the quality of welded joints, thermite welding rail joints worst quality. So rail joints are welded rail track single source of irregularity. To ensure high-speed high-speed trains, smooth run and reduce the role of power between wheel and rail, the rail welded joints welding quality, flatness and put forward higher requirements. So rail is welded joint control of the track surface is not flat parts.

     The hardness of the rail single girder gantry crane is an important indicator of the high hardness of the rail are generally more resistant (to match the hardness of the wheel), and its life is also increased accordingly. For the ordinary high-carbon steel rail, generally Brinell hardness of 280 ~ 300HB, but there are also low 260HB. For some special requirements for rail, such as the curve of the rail when the rail at above 800 ° C, the use of water mist cooling, so that the rail hardness 355 ~ 390HB.

     Current single girder hoist gantry crane  rails heat two, one is the railway works department head hardened rail track, one is iron and steel plant in the factory rails railway works departments according to the requirements of the rail hardening heat treatment, general hardened steel mills on the rail better quality. Rail plant significantly reduces the heat treatment pearlite steel body sheet spacing maximum hardness of the rail up to 400HB.