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Apr 12, 2017

The main performance characteristics of fasteners

1.Pressure and prevent creep resistance

The size of the button fastener of pressure is the key to guarantee the stability of the rail, it with the vehicle axle load, speed and whether the use of the cushion performance and and rail. When the vehicle axle load, high speed, using the general line, the requirements of rail fastener clasp pressure is big; Light axle load, low speed, the use of the seamless line, pressure can be smaller. Buckles shall ensure that the size of the pressure in the fastener, when train braking, the permanent displacement of the rail will not occur.For urban light rail, axle load is less than 160 kn commonly, no more than 100 km/h speed, therefore, is not very tall to the requirement of the button fastener pressure, theory calculation and practice show that the single button withhold pieces of pressure in 6 ~ 8 kn can meet the requirements. It is worth noting: the button too much pressure is not good, the resilient pad to this will lead to the initial amount of compression, vibration elastic.

2.Gauge and adjust performance level

Gauge is mainly to solve the construction error adjustment quantity and abrasion of grinding and the problem that the gauge to overrun, the adjustment quantity of reason for negative. Consider urban rail transit works overhaul cycle is long, daily maintenance condition is poor, the requirements of fastener track adjustment amount is bigger than wang, the track fasteners can generally be designed to track adjustment. + 8, and 12 mm.

Structure settlement, for the most part, are considered in structure design and take measures, but still need to rail fastener to adjust small amount of change. The current structure and construction technology, the requirements for underground line rail fastener have 20 ~ 30 mm level adjustment quantity. Level adjustment is closely related to the geological conditions, the size of the amount of the bad geological condition, need fasteners have large amount of level adjustment. For elevated line, the rail fastener has 30 ~ 40 mm level adjustment quantity, mainly to solve poor due to the settlement of adjacent piers falling value and beam caused by creep and shrinkage of the beam on the arch.

3.Fastener stiffness

Of a node is examination fastener stiffness elastic fasteners indicators, including static stiffness, dynamic stiffness value and action than, should be determined by laboratory test. Fasteners vertical static stiffness value is take fastener compression deformation curve of a certain period of secant slope to determine, generally 20 ~ 40 kn/mm more appropriate; Dynamic stiffness value is the important index of the fasteners that buckle under dynamic load of elasticity, the vibration reduction performance; Design fasteners activity ratio should be controlled in 1.4 below.

4.Insulating property

Insulation performance requirements of rail fastening in urban rail transit is very high, on the one hand is to walk as the requirement of the power supply return rail line rail, on the other hand, it is the demand of mobile block signal. Fasteners insulation performance is bad, in the long term, besides, resulting in a large number of current leakage and waste of electricity, also because of the stray current corrosion of reinforcing steel bar and municipal pipeline structure.

In the design of urban rail, power supply, signal and other professional insulation performance of rail fastener will put forward specific requirements. The current material technology, meet these requirements is completely feasible. Usually fasteners in a single insulating parts normal insulation resistance can be achieved above 108 Ω, can satisfy the requirements for the insulation of the fasteners.

The durability of fasteners is through fatigue test to verify, fatigue test to verify the fastener repeated load resistance performance, our country is usually taken fasteners on the small radius curve of maximum load to test. When designing fasteners, depending on the subway the measured 200 m small radius curve section fastener by force, and with reference to domestic and foreign similar fastener design load. Requirements take vertical 50 kn general assembly fasteners fatigue load, transverse 30 kn, can withstand the fatigue load cycling test 3 million times, not damage parts.

Import national standard fastener troubleshooting and maintenance necessary measures: when institutions, install fasteners parts allowed to have a certain temperature, when the hand touch body shell, should not feel hot as normal, and suggests that national standard fastener temperature too high.

Fasteners reasons: higher temperature lubricating oil quality does not conform to the requirements or metamorphism, lubricating oil viscosity is too high; The assemble tight (inadequate clearance); Import fastener assembly too tight; Fastener seat in internal rotation shaft or housing; Too much load; Fasteners cage or rolling body fracture, etc.

Imported fasteners allow running noise slightly in the work, if you have any abnormal noise or excessive noise or sound, suggests that the fastener has fault.

Scroll fastener complicated causes of noise, one is the fastener inner and outer surface wear. Due to the wear and tear, spoiled, fasteners and fasteners and shell shaft cooperate relationship, lead to axis deviation from the correct position, when axis at high speed movement produces sound. When fastener fatigue, its surface metal flake, also can make the fastener radial clearance increases produce sound. National standard fasteners, moreover, lubrication, formation of dry friction, and buckle broken etc all make abnormal noise. Loose fasteners wear loose after kuang, cage damage, also can produce sound.rail fastening system.png

(1)Fasteners maintenance: for as long as possible in good condition to maintain the performance of the fastener was, maintenance, repair, in order to prevent accident arrangement to ensure the reliability of operation, improve the productivity and economy.

To maintain the best conditions of mechanical operation of the corresponding operation standard, on a regular basis. Content includes monitor running status, supplement or replacement of lubricants, remove the check on a regular basis. Points for maintenance operation, with the rotation of the national standard fastener sound, vibration, temperature, the state of the lubricants and so on.

(2)Fasteners maintenance: fasteners to clean: remove the fastener overhaul, the first record the appearance of the imported fasteners, confirm the residual stock of lubricant, sampling inspection with lubricant, wash the fasteners. Common use gasoline, kerosene as a cleaning agent.

Tear open come down to the fastener of cleaning, rough washing and fine washing, respectively in the container, put a metal mesh bottom first, make the fastener is not direct contact with dirt from the container. Coarse when cleaning, if make the fastener with dirt, can injure the rolling surface of the fasteners, should be pay attention to. In coarse clean oil, use a brush to remove grease, adhesive, after clean, roughly into fine cleaning.

Fine cleaning, fasteners in the cleaning of oil side spin, side carefully cleaned. In addition, the clean oil is always kept clean.

(3)For the maintenance of fasteners and judgment: in order to judge whether the fastener of the removed can use, check fasteners in clean water after. Check the raceway surface, rolling surface, cooperate with the state, the abrasion of cage, the increase of the national standard fastener clearance and has nothing to do with dimension precision falling damage, abnormal. Non separation of small ball fasteners, with one hand will support level, the inner ring spinning confirm whether smooth outer ring.