Bearing as the main components of the locomotive, especially the traction motor and axle box NTN bearing, its function plays an important role in transportation safety, locomotive running online, once the NTN bearing failure, will cause the whole trains can not run, blocking transportation trunk line, especially the passenger train fails, the negative impact is bigger, once the locomotive bearing failure occurs at the same time, the locomotive repair is very difficult, so the prevention and decrease of locomotive NTN bearing failure, transportation is very important to the security of locomotive,The key point of this paper is whether the NTN bearing with hidden trouble can be detected before loading and the qualified NTN bearing parts on board.
NTN bearing damage is often not a single reason, but under the effect of several aspects comprehensive, under harsh operating conditions to produce vicious circle, causes severe loss of NTN bearing, so after the accident, it is often difficult to determine is caused by what, also bring some difficulties to our relevant measures, convenient for discussion, first from several aspects to analyze the cause of NTN bearing failure.
When the NTN bearing is used for a period of time, the inner ring, body, cage, outer ring and raceway of the bearing will produce certain defects and scars, resulting in poor lubrication of the NTN bearing and the heating of the NTN bearing. Long-term heating will lead to :(1) the dilution of NTN bearing lubricating oil.(2) Accelerate the material fatigue and decrease the hardness.Due to the above reasons, and further form a vicious cycle, accelerate the overheating and make THE NTN bearing burn.Severe NTN bearing inner ring displacement, body loss of circle, impact heat generation, and eventually weld together.Therefore, when running on the line, if it is found that the NTN bearing is seriously hot, smoking, do not stop, but should maintain the operation to the front station, because at the moment the overheated NTN bearing is in a molten state, once the stop cooling can no longer walk, plug the main line.
For oil for maintenance of locomotive NTN bearing is very important, especially for bearing the right amount of fuel can guarantee good lubrication bearing, too much of the lack of oil and gas, are easy to cause NTN bearing failure, and less likely to cause poor lubrication bearing and fever, and much more likely to cause a stir overheating, so in the maintenance of oil to appropriate, at the same time, NTN bearing lubrication oil clean is also very important, once the fall into the other impurities in the oil and water, will affect the normal clearance and building must be the oil film.
NTN bearing service time is too long, more than the service life of NTN bearing and easy to cause material fatigue, coupled with strong impact effect and material deformation, so that the roller, racetrack surface produced peel, crush, resulting in poor lubrication and increased vibration.
If the interference amount of the inner ring of NTN bearing is inconsistent with that of the shaft, it is also easy to cause the fault of NTN bearing. If the interference amount is large, it is easy to cause the inner ring of NTN bearing to crack due to excessive tensile stress. If the interference amount is too small, it is also easy to cause "relaxation" of the inner ring of NTN bearing.
NTN bearing assembly improper cooperate clearance fit, also easy to cause bearing failure, small clearance is easy to cause the roller and raceway friction heat, with the rising of temperature, NTN bearing inner ring, body, cage, outer ring, the temperature of the end cover is not the same, there is a temperature difference between each other, thus expanding quantity is slightly different, also can make further reduce the tolerance clearance, according to the NTN bearing heating.If the clearance is too large, the vibration of the roller will increase, which will aggravate the impact of the roller and the raceway. At the same time, it is easy to cause uneven distribution of internal load, reducing the bearing roller and overloading the central roller.
When assembling the bearing, the copper hammer is not used to impact the NTN bearing according to the technical requirements, resulting in the deformation of the retainer, incorrect installation of the inner and outer rings of the traction motor bearing or other reasons, resulting in the loss of axial transverse momentum, resulting in the squeezing death of the NTN bearing shaft.