Fishplate Classification and Connection Performance Requirements
What are the core classification methods and corresponding models of fish plates?
Fish plates are mainly classified by three dimensions: rail model, hole number and execution standard, with clear classification and strong adaptability. According to rail models, they are divided into light rail, heavy rail and lifting rail fish plates, light rail models are suitable for 8-30kg/m rails, heavy rail models for 38-60kg/m rails, and lifting rail models for QU70-QU120 rails. According to the number of holes, they are divided into four-hole and six-hole fish plates, four-hole models are suitable for low-speed ordinary lines with moderate connection strength, and six-hole models for high-speed/heavy-haul lines with stronger fastening force. According to standards, they are divided into national standard, UIC and BS fish plates, national standard models match national standard rails, and UIC/BS models match corresponding foreign standard rails to meet different project needs. Fish plates of different classifications have dimensions accurately matching rail joints, which are the core basis for selection.
What are the core material requirements and performance indicators of fish plates?
The core materials of fish plates are divided into four categories: Q235 carbon steel, ductile iron, forged alloy steel and bainitic steel, which are adapted to different line working conditions as needed. Q235 steel fish plates have low cost and a tensile strength of ≥375MPa, suitable for low-speed light rail lines to meet basic connection needs. Ductile iron fish plates have a tensile strength of ≥780MPa, wear resistance and fatigue resistance, suitable for medium and heavy-duty lines with longer service life. Forged alloy steel fish plates have a tensile strength of ≥900MPa, high toughness and impact resistance, which are the main materials for high-speed railways and heavy-haul dedicated lines. Bainitic steel fish plates have excellent low-temperature toughness, no brittle fracture at -30℃, suitable for lines in severe cold areas. All fish plates need to meet the rail head fit ≤0.2mm and bolt hole coaxiality ≤0.3mm to ensure connection precision.
What is the application difference between six-hole and four-hole fish plates?
Six-hole fish plates have 2 more bolt holes than four-hole ones, with a larger connection contact area and a fastening force increase of more than 40%, suitable for high-speed, heavy-haul and curve section lines. Four-hole fish plates have fewer bolt holes, moderate connection strength, convenient installation, suitable for ordinary speed branch lines and industrial and mining low-speed lines with more economical cost. Six-hole fish plates bear more uniform force, can effectively disperse the joint impact when the train passes, reduce rail joint wear and extend joint service life. The force of four-hole fish plates is concentrated on the side bolts, and the joint elasticity is slightly weak, suitable for scenes with small load and low speed. High-speed railway and heavy-haul lines compulsorily use six-hole fish plates, and ordinary speed branch lines can use four-hole fish plates, which must be strictly selected according to line grade.
What is the adaptation difference between national and foreign standard fish plates?
National standard fish plates are produced according to GB/T11265 standard, with dimensions matching 50/60kg/m national standard rails, and the bolt hole spacing and aperture are unified domestic specifications, suitable for national standard fish bolts. Foreign standard UIC fish plates are produced according to UIC860 standard, matching UIC60/UIC54 rails, with more compact hole position design and suitable for European standard high-strength bolts. BS fish plates are British standard, matching BS80A rails, with higher fit between the shape arc and rail joint, reducing joint gap. The material of foreign standard fish plates is mostly forged alloy steel, and national standard fish plates can use Q235 or alloy steel, with performance indicators adjusted as needed. The dimensions, hole positions and bolt specifications of national and foreign standard fish plates are not interchangeable, and cross-standard mixing will lead to joint loosening and potential safety hazards.
What are the core points of fish plate installation and maintenance?
Before installing the fish plate, it is necessary to clean the rust and debris on the contact surface between the rail joint and the fish plate to ensure tight fit and avoid excessive gap affecting the connection effect. During installation, the bolts must be tightened in a diagonal order with the torque controlled at 400-500N·m to ensure uniform force and prevent one-sided loosening. The fit gap between the fish plate and the rail shall be ≤0.2mm, and the alignment deviation of bolt holes ≤0.5mm to avoid cracking caused by uneven force. During maintenance, check whether the fish plate is deformed or rusted and whether the bolts are loose every month, and replace them in time if the wear is ≥3mm. In coastal and humid areas, anti-corrosion paint shall be brushed regularly with a coating thickness of ≥80μm to prevent corrosion failure of fish plates and extend joint service life, and the installation and maintenance quality directly determine joint safety.