Fishplate Rail Joint Connection and Specification Compatibility Technology
What are the core models of fishplates and applicable rail specifications?
National standard fishplates are divided into four models: 43/50/60/75kg/m, respectively adapting to the same specification national standard rails, with models precisely matching rail head and rail base dimensions, no universal models. 43kg/m fishplates are suitable for light-load tracks, with 4 bolt holes, basic connection meeting low-speed driving needs and the lowest cost. 50/60kg/m fishplates are the main force of ordinary railway/high-speed railway connecting lines, with 6 bolt holes, higher connection strength and better driving smoothness than 43kg/m models. 75kg/m fishplates are suitable for high-speed railway main lines, thickened and widened design, 8 bolt holes, locking force increased by 50%, resisting high-speed driving impact. Foreign standard fishplates are divided into UIC60/BS80A/AREMA136RE models, corresponding to foreign standard rails, hole positions and dimensions designed according to international standards, suitable for cross-border projects.
What are the core materials of fishplates and matching requirements with rails?
Fishplate materials must be the same grade as rails, national standard fishplates are U71Mn/U75V alloy steel, U71Mn for ordinary railways, U75V for high-speed railways/heavy haul, ensuring uniform stress on joints without stress difference. Foreign standard fishplates are UIC900A/Grade335 material, completely matched with foreign standard rail materials, complying with international mechanical standards, avoiding joint first failure. Fishplate tensile strength must be ≥95% of rail tensile strength, yield strength deviation ≤50MPa, hardness deviation ≤20HB, eliminating fracture caused by insufficient strength. Ordinary railway fishplates focus on plasticity and weldability for convenient on-site joint installation, high-speed railway fishplates focus on wear resistance and fatigue resistance to adapt to high-frequency vibration. The material surface shall be hot-dip galvanized for anti-corrosion, coating thickness ≥80μm, salt spray resistance ≥500 hours, avoiding joint corrosion affecting connection strength.
What are the core structural differences between high-speed and ordinary railway fishplates?
High-speed railway fishplates are arc thickened structure, with arc chamfer at the rail head fitting part, avoiding abnormal noise caused by wheel impact on joints, adapting to the smoothness demand of high-speed driving. Ordinary railway fishplates are straight plate conventional structure, thickness 16-18mm, right-angle design with convenient processing, economical cost, meeting the basic connection needs of ordinary railways. High-speed railway fishplates have 8 bolt holes with more uniform locking force; ordinary railway fishplates have 4-6 bolt holes, meeting basic locking only with simpler structure. High-speed railway fishplates are matched with 10.9 grade insulating bolts, joint insulation meets the standard to avoid circuit interference; ordinary railway fishplates are matched with 8.8 grade ordinary bolts without insulation requirements. High-speed railway fishplate joint gap ≤0.1mm, ordinary railway ≤0.2mm, gap accuracy directly affects driving smoothness, with stricter requirements for high-speed railways.
What are the core construction specifications for fishplate installation?
Before installation, clean the rail joint end face and bolt holes, remove rust, burrs and debris to ensure the joint fits without gaps and bolt holes are aligned without offset, avoiding installation jamming. Attach fishplates symmetrically to both sides of the rail joint to ensure centering without skew, the slot fully fits the rail head and rail base without unilateral suspension, preventing local stress concentration. Thread supporting high-strength bolts, install flat washers and lock nuts, pre-tighten in batches in the order of middle to edge and symmetrical locking to avoid uneven stress from single locking. Bolt torque is set according to rail specifications, 600-800N·m for 50/60kg/m rails, 800-1000N·m for 75kg/m rails, torque deviation ≤±5%. After installation, check that the joint gap ≤0.2mm, no edge warping of fishplates, rail joint straightness error ≤0.3mm, and acceptance is allowed only if there is no abnormal noise during trial operation.
What are the common faults and maintenance measures of fishplates?
If fishplate bolt hole wear ≥1mm, it will cause bolt shaking and locking failure, replace with new fishplates immediately, upgrade wear-resistant hole fishplates for heavy-duty lines to reduce wear frequency. Fishplate body cracks are mostly caused by stress concentration or overload, remove cracked fishplates and replace with new ones, and reinforce the track on both sides of the joint to reduce load impact. Joint loosening is torque attenuation or anti-loosening failure, retighten bolts to standard torque, install anti-loosening washers, inspect torque value monthly and retighten in time. Fishplate rust is caused by coating falling off and moisture, derust and re-hot-dip galvanize, replace stainless steel fishplates in coastal areas to extend anti-corrosion life. Rail joint dislocation is due to improper fishplate selection, replace with adapted fishplates, calibrate rail position, re-install and lock according to specifications to avoid driving jolt.