Fishplate Connection Methods and Performance Requirements
- What are the common connection methods of fishplates?
The common connection method of fishplates is bolt connection, which fixes two fishplates on both sides of the rail joint through bolts to realize the splicing of rails. In ordinary railways, 4-hole or 6-hole fishplates are mostly used, and the bolts are evenly distributed to ensure uniform connection stress. For heavy-haul railways, to enhance the connection strength, fishplates with more bolt holes or high-strength bolts are used to improve the anti-loosening and anti-fatigue capabilities of the connection. In addition, in some temporary lines or special scenarios, welding is also used to assist the bolt connection method to further strengthen the integrity of the rail joint.
- What impact does the material strength of fishplates have on the connection performance?
The material strength of fishplates directly determines the bearing capacity of the connection. If the material strength is insufficient, the fishplate is prone to deformation or fracture under the train load, leading to loose rail joints and affecting track safety. Common fishplate materials are carbon structural steels or low-alloy steels such as Q235 and Q345. Q345 fishplates have higher tensile strength and yield strength, suitable for heavy-haul railways and busy trunk lines, and can withstand greater impact forces and alternating loads; Q235 fishplates are suitable for branch railways with small traffic volume to meet basic connection needs.
- What are the flatness requirements for fishplates?
Fishplates have high flatness requirements, and the surface in contact with the rail must be smooth and flat, with a deviation not exceeding 0.3mm/m. If the flatness does not meet the standard, the fishplate and the rail are not in close contact, which will cause stress concentration, accelerate the wear of the fishplate and the rail, and may also cause vibration and noise when the train passes. During the production process, the flatness of the fishplate is ensured through precision processing and grinding, and flatness testing is required before leaving the factory, and it can be used only after passing the test.
- What are the differences in fishplate specifications corresponding to different types of rails?
Different types of rails need to be matched with corresponding fishplate specifications to ensure connection adaptability. For example, 43kg/m rails correspond to 43kg/m fishplates, whose length, width, and bolt hole positions are all matched with the rails; 50kg/m and 60kg/m rails also have their own dedicated fishplates. The height of the fishplate must be consistent with the height of the rail to ensure close contact with the rail. The position and diameter of the bolt holes must correspond to the bolt holes on the rail to avoid installation difficulties or loose connections. Fishplates of different specifications cannot be mixed.
- How to detect the connection quality of fishplates?
When detecting the connection quality of fishplates, first check whether the bolts are tightened, and use a torque wrench to measure the bolt torque to ensure it meets the design requirements; second, check the fit between the fishplate and the rail, and use a feeler gauge to measure the gap between them, which should be less than 0.3mm; observe whether the fishplate has defects such as deformation and cracks, which can be detected by visual inspection or magnetic particle inspection; it is also necessary to measure the size of the rail gap, which should be within the specified range (not more than 18mm in winter and not less than 10mm in summer for ordinary lines) to avoid improper rail gaps affecting the stress on the fishplate.