Lightweight Design of Fishplates and Adaptation Technology for Different Rail Joints
What are the structural design points of lightweight fish plates for national standard 60kg/m rails?
The core of designing lightweight fish plates for national standard 60kg/m rails is to optimize the cross-sectional shape on the premise of ensuring tensile strength. First, a variable cross-section design is adopted, reducing the middle thickness of the fish plate from the traditional 28mm to 22mm while keeping the thickness at both ends at 28mm, which not only reduces weight but also ensures the strength of the stressed parts of the joint. Second, weight reduction holes are opened in the non-stressed areas of the fish plate. The diameter of the weight reduction holes is 30mm, and 4 symmetrical weight reduction holes are opened on each fish plate, which can reduce material consumption by more than 15%. The position of the bolt holes of the fish plate must be precisely matched with the joint bolt holes of the national standard 60kg/m rail, with the hole spacing deviation controlled within ±0.2mm to ensure installation accuracy. Q345B alloy steel is selected as the material, with a tensile strength ≥510MPa and yield strength ≥345MPa after quenching and tempering, meeting the stress requirements of the joint. In addition, the surface of the fish plate should be chamfered with a chamfer radius of 5mm to avoid scratching the rail joint surface with sharp edges and improve operational safety during installation.
What are the special adaptation requirements of lightweight fish plates for foreign standard UIC60 rails?
The adaptation core of lightweight fish plates for foreign standard UIC60 rails is to match the cross-sectional size and bolt layout standard of its joints. First, the length of the fish plate should be designed as 800mm according to UIC standards, 50mm longer than the fish plate for national standard 60kg/m rails, to adapt to the joint overlap length of UIC60 rails. Second, the number and spacing of bolt holes must comply with UIC standards. Each fish plate is provided with 6 bolt holes with a hole spacing of 140mm to ensure installation matching with UIC standard bolts. For lightweight design, a hollow structure is adopted instead of the traditional solid structure. The width of the hollow area is 40mm and the length is 300mm, which can reduce weight by more than 20%. The material is European standard S355JR weathering steel, adapting to the humid climate in some parts of Europe and preventing the fish plate from rusting and affecting joint strength. In addition, the contact surface between the fish plate and the rail should be toothed, with a tooth depth of 0.5mm and a spacing of 2mm, increasing the friction force of the contact surface and improving the anti-slip performance of the joint, with an anti-slip coefficient ≥0.4.
What are the strength guarantee measures for lightweight fish plates in heavy-haul line rail joints?
Rail joints in heavy-haul lines bear large loads, and the strength guarantee of lightweight fish plates needs to start from both structure and process. First, high-strength material is selected, using 42CrMo alloy steel. After quenching and tempering, its tensile strength is ≥1080MPa and yield strength is ≥930MPa, which is more than 1 time higher than that of ordinary fish plate materials. Second, reinforcing ribs are added around the bolt holes of the fish plate, with a rib height of 8mm and a width of 10mm, which can improve the anti-extrusion strength of the bolt hole area and avoid bolt hole deformation under heavy-haul loads. For lightweight design, local thinning is adopted instead of opening weight reduction holes: the thickness of the non-stressed area of the fish plate is reduced to 18mm, and the thickness of the stressed area is kept at 30mm to ensure that the strength is not affected. In addition, the surface of the fish plate should be carburized, with a carburized layer thickness of 0.8-1.2mm and surface hardness reaching HRC55-60, improving wear resistance and avoiding thickness reduction caused by joint friction. During installation, high-strength bolts of grade 10.9 must be used to ensure that the overall tensile strength of the joint meets the requirements of heavy-haul lines.
What is the expansion adaptation technology of lightweight fish plates for rail joints in continuously welded rails?
Rail joints in continuously welded rails have temperature expansion and contraction deformation, and the core of expansion adaptation of lightweight fish plates is to adopt elastic structural design. First, elastic expansion sections are set at both ends of the fish plate, with a thickness of 15mm and a length of 100mm, which have a certain elastic deformation capacity and can adapt to the expansion and contraction of ±5mm of rail joints. Second, elastic rubber gaskets with a thickness of 3mm and made of nitrile rubber are installed on the contact surface between the fish plate and the rail, which not only enhance the sealing performance of the joint but also buffer the impact load caused by temperature expansion and contraction. For lightweight design, a honeycomb internal structure is adopted, with a honeycomb hole diameter of 10mm, which can reduce weight by more than 25% while ensuring the overall stiffness of the fish plate. In addition, elastic anti-loosening nuts are used for the fish plate bolts to ensure that the bolts do not loosen during the expansion and contraction deformation of the rail, ensuring the connection stability of the joint. During installation, the preload of the fish plate should be controlled at 25-30kN, which not only ensures the anti-slip performance of the joint but also reserves space for the expansion and contraction deformation of the rail.
What are the performance detection indicators and acceptance standards for lightweight fish plates?
The performance detection indicators of lightweight fish plates mainly include tensile strength, anti-slip coefficient, weight reduction rate and fatigue life. Tensile strength is detected by a tensile testing machine: the tensile strength of fish plates for heavy-haul lines should be ≥1080MPa, and for ordinary-speed lines ≥510MPa; the anti-slip coefficient is detected by a shear testing machine: the anti-slip coefficient of the contact surface between the fish plate and the rail should be ≥0.4; the weight reduction rate is calculated by weighing: the weight of lightweight fish plates should be 15%-25% lighter than that of traditional fish plates; fatigue life is detected by a pulsating fatigue testing machine: the number of fatigue cycles under simulated heavy-haul loads should be ≥2×10⁶ times. The acceptance standard is: 10 fish plates are sampled from each batch for testing, and all indicators must meet the standards. If 1 fish plate is unqualified, double sampling is required; if there are still unqualified products in double sampling, the batch is judged to be unqualified. After passing the acceptance, the product model, material and testing batch should be marked on the surface of the fish plate to facilitate subsequent quality traceability.