Environmental Adaptability Design of Fastening Systems
- What impact does high-temperature environment have on the performance of fastening systems? How to deal with it?
High-temperature environments can reduce the elasticity of elastic clips, and long-term exposure to high temperatures may cause permanent deformation of elastic clips, reducing clamping force. The anti-loosening glue of bolts is easy to age and fail at high temperatures, leading to loose connections. Countermeasures include using high-temperature resistant spring steel such as 60Si2CrA to make elastic clips, which have better high-temperature resistance than ordinary spring steel; using high-temperature anti-loosening glue for bolts, such as silicon-based anti-loosening glue, which can maintain performance in environments above 150℃; using heat-resistant rubber for under-rail pads to avoid high-temperature aging.
- What special designs are required for fastening systems in alpine regions?
The temperature in alpine regions is extremely low, and elastic clips are prone to brittleness at low temperatures and may break when impacted. The anchoring agent of spikes cures slowly at low temperatures, and may even fail to cure normally. Therefore, elastic clips should be made of materials with good low-temperature toughness, such as 55SiMnVB steel treated by low-temperature tempering; low-temperature curing resin anchoring agents are selected for spike anchoring to ensure normal curing at -20℃; the surface of bolts is treated with low-temperature galvanizing to prevent rust caused by ice and snow erosion.
- What are the key points of anti-corrosion design for fastening systems in coastal humid environments?
Coastal environments have high salt content and humidity, and components of fastening systems are prone to electrochemical corrosion. Key points of anti-corrosion design include: elastic clips are treated with multi-element alloy permeation to form a dense protective film with salt spray resistance of more than 500 hours; bolts are made of 316 stainless steel or treated with dacromet coating to improve corrosion resistance; the contact surface of fishplates is coated with anti-rust primer and topcoat to form double protection; under-rail pads are made of neoprene rubber resistant to seawater corrosion to avoid material deterioration.
- What are the structural design requirements for fastening systems in sandy and windy areas?
Sand and wind can enter the gaps of the fastening system, accelerating component wear and even causing bolts to jam and unable to be disassembled. Structural design requirements: the gap between elastic clips and gauge baffles is controlled within 0.5mm to reduce sand and dust entry; the bolt head is designed with a dust cover to prevent sand and dust accumulation; the edge of the pressure plate is rounded to avoid sand and dust accumulation forming abrasives; the surface of the under-rail pad is added with anti-skid lines to prevent micro-displacement of the rail caused by wind and sand.
- How to enhance the stability of fastening systems in areas with frequent geological vibrations?
Geological vibrations can loosen bolts of the fastening system and reduce the clamping force of elastic clips. Designs to enhance stability include: adopting a double nut anti-loosening structure with friction plates between nuts to improve anti-loosening effect; elastic clips 选用 Type Ⅲ elastic clips with greater clamping force, with initial clamping force ≥13kN, to resist clamping force loss caused by vibration; the anchoring depth of spikes is increased to 120mm, 20mm deeper than conventional, to enhance anchoring force; steel fibers are added to under-rail pads to improve their shear resistance and reduce deformation caused by vibration.