Fishplate Machining Precision and Connection Stability
- What aspects are included in the machining accuracy of fishplates?
It includes dimensional accuracy, such as the length, width, thickness of the fishplate and the position and diameter of the bolt holes, which must be strictly controlled within the design tolerance range. Surface accuracy is also important. The surface roughness must meet the specified requirements, generally the Ra value is not greater than 6.3μm, to ensure good contact with the rail. Shape accuracy, such as the flatness and perpendicularity of the fishplate, to avoid warping, bending and other deformations that affect the fit with the rail.
- What impact will insufficient machining accuracy have on fishplate connections?
Insufficient dimensional accuracy will lead to a gap between the fishplate and the rail, resulting in impact and vibration when the train passes, aggravating the wear of the connection part and shortening the service life. Excessive surface roughness will increase the frictional resistance between the fishplate and the rail, and at the same time cause stress concentration, which is prone to cracks. Insufficient shape accuracy, such as poor flatness, will make the contact between the fishplate and the rail uneven, unbalanced load distribution, and may cause local damage to the fishplate or rail.
- How to ensure the machining accuracy of fishplates?
Use high - precision processing equipment, such as CNC milling machines and boring machines, to ensure the accuracy of size and shape during processing. Formulate a reasonable processing technology, such as reasonably arranging the processing sequence, first performing rough processing to remove most of the allowance, then performing finish processing to ensure accuracy, and avoiding excessive stress and deformation during processing. Strengthen the inspection during processing, use precision measuring tools such as vernier calipers and micrometers to measure key dimensions in real time, and adjust processing parameters in time.
- What are the requirements for the fitting accuracy between fishplates and rails?
The fitting gap between the fishplate and the rail must be controlled within 0.3mm to ensure that the two are closely fitted and reduce relative sliding. The position accuracy of the bolt holes is high, and the concentricity error between the fishplate bolt holes and the rail bolt holes does not exceed 0.5mm to ensure that the bolts can be smoothly inserted and tightened. The fit between the working surface of the fishplate and the rail head and web must reach more than 80%, so that the load can be evenly transmitted.
- What are the differences in machining accuracy between fishplates of different materials?
Alloy steel fishplates have high material hardness, are difficult to process, and have higher requirements for processing equipment and tools, but their machining accuracy is easy to maintain, especially dimensional accuracy and shape accuracy. Ordinary carbon steel fishplates are relatively easy to process, but the material has good toughness and is prone to deformation during processing, so measures must be taken to control the shape accuracy. Stainless steel fishplates have high requirements for surface accuracy, and attention must be paid to avoiding surface scratches during processing to ensure that the surface roughness meets the requirements.