50kg Track Section
The track section is a key part of the track structure, which directly determines the stability of train travel and the service life of the track. 50kg track refers to a steel rail with a weight of 50 kilograms per meter, which is commonly found in ordinary railway trunk lines, station lines and special lines for industrial and mining enterprises. This type of track has achieved a balance between load-bearing capacity, wear resistance and economy, and has a wide range of applications.
The track section shape adopts an I-shaped design, which is divided into three parts: rail head, rail waist and rail bottom. The rail head width is 72 mm, and the part that directly contacts the wheel is designed to be an arc shape, which can effectively disperse the wheel pressure. The rail waist is 152 mm high and 16.5 mm thick. The internal structure adopts a gradual thickening structure to ensure strength while reducing the overall weight. The rail bottom width is 150 mm, with bolt holes and fixing grooves, which is convenient for firm connection with the rail.
The steel material is U71Mn high-strength low-alloy steel, with a carbon content controlled at 0.65%-0.75% and a manganese content of 0.7%-1.0%. This material is rolled and formed three times, and the surface of the rail head is subjected to residual heat quenching treatment. The surface hardness reaches HB320-380, and the internal toughness is maintained. Trace vanadium elements are also added to the rails used in the severe cold areas of Northeast China to improve the ability to resist low-temperature brittle cracking.
The manufacturing process includes four stages: raw material pretreatment, billet heating, profile rolling, and slow cooling treatment. The billet needs to be evenly heated to 1250℃ in a step-type heating furnace and rolled in 11 passes using a universal rolling mill, of which the 7th pass is specifically used for arc forming of the rail head. The slow cooling work lasts for 72 hours, and the temperature gradually drops from 800℃C to room temperature to eliminate internal stress.
Daily maintenance needs to focus on three parts. The wear amount of the working surface of the rail head is measured monthly with a contour detector, and the maximum vertical wear amount allowed is no more than 9 mm. Check the rust condition on both sides of the rail waist every quarter. If rust spots are found, they need to be cleaned with a wire brush and painted with anti-rust paint. The contact surface between the rail bottom and the pad is opened and inspected twice a year, and the bolt tightening torque must be maintained in the range of 900-1100N-m.
When used on heavy-load lines, it is recommended to set rail gap expansion and contraction adjusters every 3 kilometers to prevent track deformation caused by thermal expansion and contraction. For sections with a curve radius of less than 600 meters, a group of sleepers must be arranged every 5 sleepers. The turnout area uses a reinforced rail waist with a special cross-section, the thickness is increased to 20 mm, and a reinforcement is installed on the inner side of the track. Gauge rods and plates.
