Design and application of new connection structure of fishplate
- What is the design principle of the wavy fishplate?
The wavy fishplate adopts a wavy curved surface design with alternating concave and convex shapes, which forms multiple points of contact when it fits with the rail. Compared with the flat fishplate, the contact area is increased by 30% - 40%. When the train passes, the wave structure can disperse the stress, reduce the stress concentration factor at the joint by 25%, and reduce the occurrence of cracks. At the same time, the wavy edge can effectively prevent rainwater and mud from entering the joint gap, prevent bolt rust and pad wear. After using this fishplate on a certain line, the joint maintenance cycle was extended from 1 year to 3 years.
- How does the self-locking fishplate achieve the anti-loosening function?
The self-locking fishplate is equipped with a wedge-shaped lock and a spring pin on both sides. During installation, the wedge-shaped lock is inserted into the reserved groove of the rail, and the spring pin automatically pops into the slot to form a mechanical lock. When the train vibrates, the lock becomes tighter and tighter under the action of the wedge-shaped inclined surface, and the preload loss is less than 3%. Experiments show that after simulating millions of vibrations, the bolt torque retention rate of the self-locking fishplate reaches 98%, while the traditional fishplate is only 65%, effectively avoiding the problem of rail misalignment caused by looseness.
- How to achieve the waterproof performance of the sealed fishplate?
The sealed fishplate is equipped with an annular rubber seal ring on the contact surface with the rail. The material is EPDM, which has excellent aging resistance and a service life of more than 15 years. The seal ring is embedded in the groove of the fishplate, and the compression rate is controlled at 20% - 30% to form a sealing pressure. The water spray test verified that under heavy rain conditions (rainfall 100mm/h), there is no water seepage inside the joint, which prevents corrosion at the bottom of the rail. It is particularly suitable for railways in humid environments such as tunnels and coastal areas.
- What are the characteristics of the material selection of the new fishplate?
In addition to the traditional Q235 steel, the new fishplate uses high-strength alloy steel (such as 40Cr) or ductile iron (QT450 - 10). After quenching and tempering, the tensile strength of 40Cr alloy steel reaches 980MPa, which is 40% higher than that of ordinary steel and is suitable for heavy-duty railways; ductile iron has good shock absorption and wear resistance, and its impact absorption energy is 50% higher than that of ordinary cast iron, which reduces the noise when the train passes. The surface of some fishplates is treated with Dacromet coating, and the salt spray resistance time exceeds 1000 hours, which enhances the anti-corrosion ability.
- What improvements have been made to the construction and installation of the new fishplate?
The design of the new fishplate takes into account the convenience of installation, adopts a modular structure, and reduces the number of bolts. For example, a certain model of fishplate reduces the number of bolts from 6 to 4, and the installation time is shortened by 40%. At the same time, the position and size of the bolt holes are optimized to make the bolt tightening torque more uniform and avoid excessive local force. Equipped with special installation tools (such as hydraulic fasteners), the bolt preload can be accurately controlled, and the installation error is controlled within ±5%, which improves construction efficiency and installation quality.