Coordination Mechanism of Core Components in the Fastening System
What impacts do the clamping force parameters of spring clips have on line safety?
The clamping force of spring clips directly determines the fixing stability of rails. High-speed railway lines require a spring clip clamping force of ≥16kN, while conventional speed lines usually require ≥12kN. Insufficient clamping force will cause the rail to displace under train vibration, leading to gauge deviation and increasing the risk of derailment. Excessive clamping force will exacerbate fatigue damage of the spring clip, shorten its service life, and may also cause wear on the rail shoulder. Different types of spring clips have different clamping force designs, such as Type V spring clips for high-speed railways and Type I spring clips for conventional speed railways. In practical applications, spring clips should be selected according to line standards, and the bolt preload should be controlled with a torque wrench to ensure the clamping force meets the requirements.
Why is the anti-corrosion coating system of bolts a key indicator of the fastening system?
Bolts are exposed to outdoor environments for a long time, facing corrosion from wind, rain, salt, humidity, etc. The anti-corrosion coating can effectively extend their service life. The national standard requires bolts to adopt a double-layer protection of Dacromet + epoxy resin, with no red rust after 3000 hours of salt spray test. If the anti-corrosion coating fails, the bolts are prone to rust and corrosion, leading to a decrease in preload, which in turn affects the clamping force of the spring clip and causes track loosening. Bolts on heavy-haul lines are subjected to greater forces and have higher requirements for anti-corrosion performance, requiring additional coating thickness. Regularly inspecting the state of the bolt's anti-corrosion coating and promptly replacing rusted bolts is an important part of line maintenance.
How does the anchoring method of rail spikes adapt to different sleeper types?
There are two main anchoring methods for rail spikes: sulfur anchoring and resin anchoring, which are respectively suitable for different sleeper materials and line requirements. Sulfur anchoring is suitable for traditional concrete sleepers, fixing the spike through the adhesion of sulfur mortar, with a mature construction process and low cost. Resin anchoring is suitable for prestressed concrete sleepers and ballastless tracks, with higher anchoring strength and better durability, capable of resisting greater lateral loads. High-speed railway ballastless tracks prioritize resin-anchored rail spikes to ensure long-term stability and reduce maintenance frequency. Rail spike anchoring needs to control drilling accuracy and anchoring agent filling quality to avoid insufficient anchoring force.
How does the structural design of the clamping plate affect the force transmission of the rail?
The clamping plate is fixed on the sleeper by bolts, and its contact area and shape design directly affect the distribution of rail pressure. A reasonable clamping plate structure can evenly transmit the longitudinal and lateral forces of the rail to the sleeper, avoiding local stress concentration. Clamping plates for high-speed railways usually adopt an arc contact design, fitting closely with the rail bottom to reduce gaps caused by vibration. Clamping plates for heavy-haul lines will increase thickness and contact area to withstand greater load impacts. The clamping plate material should be high-strength alloy steel, heat-treated to improve hardness and wear resistance, ensuring no deformation during long-term use.
Why is the three-dimensional adjustment function of the fastening system crucial for line maintenance?
The height adjustment and gauge adjustment functions of the fastening system can achieve precise adjustment of gauge ±10mm and rail surface height ±30mm, adapting to line settlement and geometric deviation. Long-term train operation will cause sleeper settlement and rail wear, and the track accuracy can be quickly restored by adjusting the fasteners without replacing a large number of components. Urban rail transit has short station spacing and frequent starts and stops, leading to faster track deformation. The three-dimensional adjustment function can significantly reduce maintenance costs. High-speed railway lines have extremely high requirements for track smoothness, and the fine-tuning function can effectively control wheel-rail dynamic effects and improve ride comfort. Different fastener systems have different adjustment ranges, and the selection should be determined based on line maintenance needs.