Refined Assembly Technology of Railway Turnouts and Adaptation Solutions for Different Operating Scenarios
What is the core technology of refined assembly for high-speed railway turnouts?
The core of refined assembly for high-speed railway turnouts is to achieve high-precision positioning and seamless connection of turnout components. First, adopt a 3D laser positioning and measurement system with a measurement accuracy of ±0.1mm, which can real-time monitor the spatial position of key components such as point switches, frogs and guard rails, ensuring that the gauge deviation ≤±1mm and the horizontal deviation ≤0.5mm/m. The assembly of point switches adopts CNC hydraulic point machines, the switching force of turnouts is controlled at 30-40kN, and the switching time ≤3.8s, meeting the requirements of high-speed trains passing through turnouts at high speed. The frog part adopts a high-manganese steel integral cast frog and is quenched and strengthened. The tread hardness reaches HRC55-60, and the wear resistance is improved by 40%. At the same time, profile grinding is carried out on the throat part of the frog with a grinding accuracy ≤0.1mm to reduce wheel-rail impact. The fastener system of the turnout adopts adjustable elastic fasteners, the vertical stiffness of the fasteners is controlled at 35kN/mm, and the track settlement can be compensated by adjusting the height adjustment amount of the fasteners, with a height adjustment range of 0-20mm. After assembly, conduct a dynamic smoothness test, use a high-speed inspection train to pass through the turnout at a speed of 160km/h, test the wheel-rail force and vibration amplitude, and ensure that all indicators meet the high-speed railway operation standards.
What are the key points of impact-resistant assembly design for heavy-haul freight turnouts?
The core of impact-resistant assembly design for heavy-haul freight turnouts is to improve the bearing capacity and fatigue resistance of turnout components. First, the frog selects an alloy steel composite frog, the frog center is made of high-strength alloy steel with a tensile strength ≥1200MPa, which is 50% higher than that of high-manganese steel frogs, and can adapt to axle load above 30t. The fitting surface between the point rail and the stock rail of the point switch is subjected to high-frequency quenching treatment with a quenching depth of 3-5mm and a surface hardness ≥HRC58, enhancing the wear resistance of the fitting surface and preventing poor fit caused by point rail wear. The under-rail foundation of the turnout adopts concrete turnout sleepers, the reinforcement ratio of the sleepers is increased to 2.5%, and the bending strength ≥60MPa, which can withstand the huge impact load of heavy-haul trains. During assembly, adopt high-strength bolt fastening, the preload of the bolts is controlled at 45-50kN, which is 30% higher than that of ordinary turnouts, preventing component displacement caused by bolt loosening. In addition, install buffer pads between the wing rails and guard rails of the frog. The pad is made of polyurethane with a thickness of 10mm, which can absorb the impact energy when the train passes through the turnout and reduce the vibration amplitude of the frog by ≥25%.
What are the compatibility assembly adjustment measures for turnouts in mixed passenger and freight lines?
The core of compatibility assembly for turnouts in mixed passenger and freight lines is to balance the smoothness of passenger trains and the bearing capacity of freight trains. First, the gauge of the turnout adopts a 1435mm standard gauge, and the gauge widening value is controlled at 0-2mm, which not only meets the smoothness requirements of passenger trains passing through turnouts at high speed, but also avoids the jamming risk of freight train wheel sets. The switching system of the point switch adopts a dual-machine traction scheme, two point machines act synchronously, the switching force is increased to 50kN, which can adapt to the large traction demand of freight trains, and ensure that the fit accuracy of the point rail ≤0.2mm. The fastener system of the turnout adopts a graded stiffness design, high-stiffness fasteners (stiffness 40kN/mm) are used in key parts such as point switches and frogs to improve bearing capacity; medium-stiffness fasteners (stiffness 30kN/mm) are used in connection parts to balance the vibration damping effect. In view of the wheel diameter difference between passenger and freight trains, carry out optimized grinding on the tread of the frog, the fitting rate between the ground tread and wheels of different diameters ≥95%, reducing wheel-rail contact stress. In addition, the assembly gap of the turnout is controlled at 0.5-1mm, which not only ensures the free expansion and contraction of components, but also avoids train shaking caused by excessive gaps.
What are the inspection and acceptance standards and testing methods for turnout assembly quality?
The inspection and acceptance standards for turnout assembly quality are divided into static testing and dynamic testing. The core indicators of static testing include gauge, level, alignment and verticality. The gauge deviation ≤±1mm, level deviation ≤0.5mm/m, alignment deviation ≤1mm/m, verticality deviation ≤1mm/m. A track geometry state detector is used for testing with a detection accuracy of ±0.1mm. The fit performance test of the point switch adopts feeler gauge measurement, the fit gap between the point rail and the stock rail ≤0.2mm, and a gap of 0.5mm is allowed at the tip of the point rail. The switching force and switching time of the point machine must meet the design requirements. The flaw detection of the frog adopts an ultrasonic flaw detector to detect internal defects of the frog center and wing rails. The defect equivalent ≤φ2mm, and the surface crack length ≤1mm, ensuring that the frog has no fatal defects. Dynamic testing adopts a comprehensive inspection train to pass through the turnout at 110% of the design speed, test the vertical and lateral wheel-rail forces, the peak vertical force ≤1.2 times the axle load, the peak lateral force ≤0.8 times the axle load, and test the derailment coefficient and wheel load reduction rate of the train at the same time, the derailment coefficient ≤0.8, and the wheel load reduction rate ≤0.6. Only after both static and dynamic tests are qualified can the turnout be put into operation.
What are the maintenance strategies for turnouts in different operation scenarios?
The maintenance of turnouts in different operation scenarios needs to formulate targeted strategies. High-speed railway turnouts adopt refined maintenance, conduct a static geometric dimension test every month, a dynamic smoothness test every quarter, and a frog flaw detection every year. When the geometric dimension deviation exceeds the limit, use a CNC grinding machine for precise adjustment with an adjustment accuracy ≤0.1mm. Heavy-haul freight turnouts adopt wear-resistant maintenance, check the wear of point rails and frogs every two months, replace them in time when the wear amount exceeds 3mm, and re-tighten the fastener bolts every six months to prevent bolt loosening. Turnouts in mixed passenger and freight lines adopt balanced maintenance, taking into account the maintenance needs of both passenger and freight transport, test the fit performance of point switches every quarter, test the stiffness attenuation of fasteners every six months, and handle problems in time. Establish a turnout maintenance file to record the test data and treatment measures of each maintenance, predict the failure cycle of turnouts through big data analysis. For key components of high-speed railway turnouts, such as point machines and frogs, adopt condition-based maintenance instead of scheduled maintenance, formulate maintenance plans according to the actual state of components, reduce maintenance costs, and improve the service reliability of turnouts.