Rail Types and Selection
- How to choose different weight rails (such as 38kg/m, 50kg/m, 60kg/m) in practical applications, and what is the basis?
38kg/m rails are mostly used in the narrow - gauge railways inside factories, mines and enterprises or branch railways with small traffic volume. Because of their light weight and relatively low cost, they can meet the needs of low - traffic - volume scenarios. 50kg/m rails are suitable for ordinary railway trunk lines, such as some regional passenger - freight mixed - running lines. Their bearing capacity is moderate and can withstand a certain train load and running speed. 60kg/m rails are mainly used in high - speed railways and busy heavy - haul freight railways. On these lines, the train axle load is large and the running speed is fast. 60kg/m rails have high strength and good stability, which can effectively ensure driving safety and the long - term stability of the track. The selection basis mainly includes factors such as the designed traffic volume of the line, train axle load, running speed and economy. A comprehensive consideration is required to ensure that the rails match the line requirements.
- How does the material of the rail affect its performance, and how to choose the appropriate material of the rail in different environments?
Carbon - steel - material rails have a relatively low cost and certain strength and toughness, which are suitable for railway lines in general environments. Copper - containing carbon - steel rails, due to the addition of copper elements, have enhanced weather resistance and can effectively resist atmospheric corrosion, making them suitable for use in humid, marine - climate and other environments. High - silicon and copper - containing steel rails further improve wear resistance and corrosion resistance and are often used in sections with large traffic volume, complex line conditions and high requirements for rail life, such as the curve sections of heavy - haul railways. In alpine regions, rail materials with good low - temperature toughness should be selected to prevent brittle fracture at low temperatures; in chemically polluted areas, alloy - steel rails with strong corrosion resistance should be used to avoid the erosion of rails by chemical substances.
- What are the requirements for the appearance quality of rails, and how to judge whether the rails are qualified through appearance inspection?
In appearance, the rolled rails should be straight without significant bending and torsion, and the local bending and torsion and their correction deformation should meet the standard requirements. The surface of the rail should be clean and smooth without defects such as cracks, scabs and scratches, and there should be no shrink - hole marks and interlayers at the end face. Through visual inspection, observe whether there are the above - mentioned defects on the surface of the rail, measure whether the bending degree and torsion degree exceed the standard, and use tools such as calipers to detect whether the geometric dimensions of the rail meet the standards, such as the allowable deviation of rail height, bottom width, head width, waist thickness and other dimensions, so as to judge whether the rail is qualified.
- What are the requirements for the setting of rail gaps during the rail laying process, and what problems will unreasonable rail gaps bring?
When laying rails in non - high - temperature seasons, the reserved rail gap needs to be calculated according to the local maximum and minimum temperatures to ensure that the rails have expansion and contraction space when the temperature changes. The formula is: reserved rail gap = 0.0118×(local maximum temperature - laying temperature)×rail length + structural rail gap (generally 2mm). If the rail gap is too large, when the train passes, there will be a strong impact noise, which will intensify the wear at the rail joint, lead to more joint diseases, and at the same time increase the vibration of the track, affecting the running stability of the train; if the rail gap is too small, in the high - temperature season, the rail expands when heated and cannot expand and contract freely, which may generate huge temperature stress and cause rail buckling, seriously threatening driving safety.
- What are the common diseases of rails during use, and how to prevent and rectify them?
Common diseases include rail wear (including side wear, wavy wear, etc.), rail - head peeling, and cracks in the bolt holes of the rail waist. Preventive measures include reasonably selecting the rail material and type, optimizing the track structure, such as using continuous welded rails to reduce joints; strengthening track maintenance, regularly adjusting the gauge and level, and timely replacing fasteners with excessive wear. Rectification methods: for rail wear, grinding and repair can be used, and when the wear exceeds a certain limit, the rail needs to be replaced; for rail - head peeling, it can be treated by welding and grinding; for cracks in the bolt holes of the rail waist, when they are relatively light, drilling to stop the crack can be carried out, and when they are serious, the rail needs to be replaced.