Contact form between the pressure plate and the bottom of the rail
- What are the types of contact between the pressure plate and the bottom of the rail?
Plane contact: The contact surface of the pressure plate is flat, suitable for ordinary railway 60kg/m rails, and simple processing; arc contact: The contact surface is consistent with the arc of the rail bottom (radius 50mm~60mm), which is used for high-speed rails and has more uniform force; point contact: through the raised small point contact, it is suitable for small radius curve sections to reduce the wear of the rails by lateral force.
- What are the effects of different contact forms on force?
Plane contact is prone to sliding under the action of lateral force, and the local pressure is twice that of arc contact; arc contact can disperse the load, reduce the pressure by 30%, and reduce the wear by 50%; the protrusion of point contact can increase friction, and the lateral force resistance is 40% stronger than that of plane contact.
- What are the applicable scenarios of different contact forms?
Straight sections use flat contact, which is low-cost and meets the needs; curved sections (radius ≤ 800m) use arc contact to reduce rail eccentric wear; urban rail transit (frequent train starts and stops) use point contact to enhance lateral constraints and reduce maintenance frequency.
- How to detect the fit of the contact form?
Use a pressure-sensitive test paper to clamp between the pressure plate and the rail bottom, apply a standard preload and observe the color change area of the test paper. The flat contact must be ≥80%, the arc contact must be ≥90%, and each protrusion of the point contact must change color (indicating effective contact).
- How to optimize the contact form of the pressure plate?
For the pressure plate with flat contact, the edge is rounded (radius 3mm) to reduce stress concentration; the pressure plate with arc contact must match the actual measured curvature of the rail bottom, with an error of ≤0.1mm; the height of the protrusion of the point contact is set to 1mm~1.5mm. If it is too high, it is easy to damage the rail bottom, and if it is too low, the friction is insufficient.