Fishplate Processing and Connection Accuracy
- What are the main processing technologies of fishplates?
Fishplate processing mainly includes forging, cutting, heat treatment and surface treatment. Forging forms the basic shape of the fishplate through high-temperature forging, improving material density and mechanical properties; cutting processes the forged blank through milling and drilling to ensure dimensional accuracy and surface finish; heat treatment enhances the hardness and toughness of the fishplate through quenching and tempering, making it not easy to deform under stress; surface treatment mostly uses painting or galvanizing to enhance corrosion resistance and extend service life.
- What are the precision requirements for the bolt hole processing of fishplates?
The diameter deviation of the bolt hole must be controlled within ±0.2mm to ensure that the bolt can pass through smoothly and fit tightly; the hole spacing deviation does not exceed ±0.3mm to ensure accurate alignment with the rail bolt hole and avoid misalignment during installation; the perpendicularity deviation of the hole is ≤0.5° to prevent the bolt from being stressed and skewed after installation, affecting the connection strength. In addition, the edge of the bolt hole must be chamfered to remove burrs, avoiding scratching the bolt and installers.
- How to ensure the fitting accuracy between the fishplate and the rail?
During processing, the flatness of the contact surface between the fishplate and the rail must be strictly controlled, with a deviation of ≤0.1mm/m to ensure close fitting; the roughness of the contact surface must reach below Ra12.5μm to reduce contact gaps; before installation, rust and oil on the contact surface must be cleaned, and 打磨 if necessary; during installation, bolts are tightened symmetrically to make the fishplate fit the rail evenly under force, avoiding excessive local gaps.
- What impact does the heat treatment of fishplates have on their performance?
The hardness of the fishplate after heat treatment can reach HB220-260, which can withstand large impact force and friction and is not easy to wear; tempering can eliminate quenching stress, improve toughness, and avoid cracks under repeated loads; reasonable heat treatment can also make the internal structure of the fishplate uniform, reduce performance attenuation during use, and ensure long-term stable work. Especially in heavy-haul railways, heat treatment quality directly affects the service life of fishplates.
- What are the differences in processing technologies of fishplates with different materials?
Ordinary carbon steel fishplates have a lower forging temperature (about 1100℃), and are easy to cut, but the hardness increase after heat treatment is limited; alloy structural steel fishplates require a higher forging temperature (1200-1250℃) to ensure forging quality, need more wear-resistant tools for cutting, and can obtain higher strength and hardness after heat treatment; stainless steel fishplates need special cutting fluids and processing tools to avoid rust during processing, and surface treatment mostly uses passivation instead of painting or galvanizing.