Connection and maintenance of fishplates
- What are the connection methods of fishplates? What are their characteristics?
The common connection methods of fishplates are ordinary bolt connection and high - strength bolt connection. Ordinary bolt connection is simple to operate and has a low cost. During installation, only a wrench is needed to tighten the bolts, which is suitable for some railway branch lines or temporary lines with low requirements for connection strength and small traffic volume. However, with the long - term vibration of trains, the bolts in this connection method are prone to loosening, requiring frequent inspection and tightening. High - strength bolt connection applies a large pre - tightening force to make the fishplate closely fit the rail. It has high connection strength and reliability, and can withstand the impact and vibration of heavy - haul and high - speed trains, so it is often used in railway main lines and important lines. However, high - strength bolt connection requires high construction technology. Special torque wrenches are needed during installation to control the pre - tightening force, and the cost of bolts is relatively high.
- How to select fishplates in different railway environments?
In ordinary railway main lines, medium - carbon steel fishplates that meet national standards are usually selected. Their strength and toughness can meet the load requirements of general train operations, and they have a high cost - performance ratio. In heavy - haul railways, due to the large axle load of trains, high - strength alloy steel fishplates are required. These fishplates have higher tensile strength and fatigue resistance, which can effectively avoid the fracture or deformation of fishplates caused by the frequent rolling of heavy - haul trains. In coastal railways or railways near chemical parks where the corrosion environment is relatively severe, fishplates with special anti - corrosion treatment should be selected, such as those processed by hot - dip galvanizing, Dacromet coating and other processes to enhance the anti - corrosion ability of fishplates and extend their service life. In addition, in alpine regions, the material of fishplates also needs to have good low - temperature toughness to prevent brittle fracture in low - temperature environments.
- What are the common causes of damage to fishplates during use?
The impact force generated when the train passes through the rail joint is one of the main causes of fishplate damage. Frequent impacts will cause wear on the contact part between the fishplate and the rail. Long - term accumulation may result in the thinning of the fishplate thickness and surface cracks. In addition, loose bolts are also a common problem. When the bolts are loose, the fishplate cannot effectively transfer the load, which will exacerbate the uneven force on itself and accelerate the damage. Material defects or poor manufacturing processes of fishplates, such as internal pores and slag inclusions, are also prone to cause crack propagation and fracture under the action of train loads. Environmental factors, such as humidity and acid - base corrosion, will also weaken the strength of fishplates and reduce their bearing capacity.
- What are the key points of daily maintenance and inspection of fishplates?
During daily maintenance, first, regularly check the appearance of fishplates to see if there are cracks, deformations, wear, etc., especially around the edges of fishplates and bolt holes, where stress concentration is likely to cause cracks. Use a torque wrench to check the tightness of the bolts and tighten them according to the specified torque value to prevent the bolts from loosening. Clean the debris and rust on the surface of the fishplates to avoid impurities affecting the fit between the fishplates and the rails. During the inspection process, fishplates with wear exceeding the specified standard must be replaced in a timely manner; if cracks are found on the fishplates, regardless of the size of the cracks, they should be replaced immediately to ensure driving safety. At the same time, analyze the replaced fishplates to find out the causes of damage, so as to take targeted improvement measures.
- What are the technological innovations of new - type fishplates?
New - type fishplates are constantly innovating in materials. Nano - composite materials, high - performance alloy steel, etc. are used. These materials have higher strength, toughness and wear resistance. Compared with traditional materials, they can significantly extend the service life of fishplates. In terms of structural design, some new - type fishplates optimize the layout of bolt holes and the shape of the plate surface, making the force more uniform and reducing stress concentration. Some fishplates are integrated with intelligent monitoring functions. Through built - in sensors, they can real - time monitor parameters such as the force, deformation and temperature of fishplates. Once an abnormality occurs, an alarm can be issued in time, which is convenient for railway maintenance personnel to handle quickly. In addition, new - type fishplates also have breakthroughs in anti - corrosion technology. New technologies such as self - healing anti - corrosion coatings are used, which can automatically repair when the coating is damaged, further improving the anti - corrosion performance.