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Method for discriminating locomotive rolling bearing problems
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2 The bearing's faulty bearing is often not caused by a single cause; it is summarized in several aspects; a vicious cycle occurs under bad operating conditions; the bearing is severely burnt; therefore, after the incident, it is often very It is difficult to distinguish what constitutes the reason; it also gives us the necessary difficulties in the formulation of the association; for the convenience of comments; first analyze the causes of bearing problems from several aspects.
(1) Abnormal wear of the bearing
a When the bearing is used for a period of time; the inner ring of the bearing, the rolling element, the cage, the outer ring, the raceway, etc. must have certain defects and scars; the smoothness of the bearing is formed; the heat of the bearing is incurred; the heat of the long time; (1) Dilution of bearing smooth oil. (2) Accelerate the fatigue of raw materials; Reduce the hardness. Because of the above reasons; further constitute a vicious circle; accelerate the overheating and burn the bearing. Severe bearing inner ring displacement; the rolling body is out of round; It is in contact with the heat; the end is welded together. Therefore, when running on the line; if the bearing is found to be severely heated and smoked; do not park; but keep running to the front station; because the overheated bearing is in a molten state; once the parking is cooled After that, you can no longer walk; block the positive line.
b It is very important for the oil supply protection of the locomotive bearings; in particular, the excessive oil supply to the bearing can ensure the bearing has an outstanding smooth effect; the lack of oil and excessive oiling are also very simple to constitute the bearing fault; the oil addition is less simple and the bearing is not smooth. The heat is added; the addition is too simple to constitute the mixing and overheating; therefore, the oil should be properly protected in the protection; the hygiene of the smooth grease of the bearing is also very important; once the oil and other impurities and moisture are dropped, it will affect the normal play and Establish the necessary oil film.
c The bearing is used for too long; it exceeds the service life of the bearing and simply constitutes the fatigue of the raw material; coupled with the fierce impact effect, the material is deformed; the roller and the raceway surface are peeled off and the sheet is crushed; then the smoothness and vibration are formed. Increase.
(2) Influence of the device on the bearing
a The inner clearance of the inner ring of the bearing does not match the interference of the shaft; it is also very simple to form a bearing fault; the interference is large; it is very simple to form the inner ring of the bearing due to excessive tensile stress; the interference is over. Fiji heart.
b Bearing assembly cooperation gap cooperation is not appropriate; also constitutes a bearing fault; small clearance is very simple to form a roller and raceway conflict heat; followed by rising temperature; bearing inner ring, roll body, cage, outer ring, end The temperature of the cover is not the same; there is a temperature difference between them; therefore, the amount of expansion is also slightly different; it also constitutes a further reduction of the cooperative gap; the heat generated by the bearing is added; the gap is too large; the vibration of the roller is increased; The impact of the roller and the raceway; together, it is easy to form an uneven distribution of internal load; the load roller is cut; the center roller load is too large.
c When assembling the bearing, do not follow the process requirements; use the copper hammer to impact the bearing; constitute the deformation of the cage; the traction motor bearing inner and outer ring device is incorrect or other reasons cause the axial traverse amount to disappear; the bearing shaft is squeezed.
3 The detection of bearing faults is currently diagnosed in China. There are roughly methods for measuring temperature, noise and vibration parameters. The method of measuring temperature and noise is simpler; but it lacks useful preventive effect; once the bearing temperature is over during operation High and high noise; usually think that the locomotive bearings have reached a relatively serious degree of damage. The method of measuring vibration parameters is used; when the locomotive is in the middle and small repairs, the bearings are tested; because it is convenient to obtain and collect information in the test. Abbreviation; compared to the application of the middle section to promote the use; is a simple and useful detection method.
There are two main methods for the diagnosis of locomotive bearings:
a simple diagnosis of locomotive bearings.
In the vibration detection, it is usually through the test of certain vibration parameters. æ°¡æ›œ æ‹… æ‹… æ‹— æ‹— â”å†‰ â”å†‰ â”å†‰ ç£ ç£ ç£ ç£ ç£ ç£ ç£ ç£ ç£ ç£ è¯™æ›° è¯™æ›° è¯™æ›° è¯™æ›° è¯™æ›° è¯™æ›° é”’ é”’ é”’ é”’ é”’ é”’ é”’ é”’The target of KV, and the acceleration useful parameter Xrms are used as the discriminant parameters; the kurtosis target KV is a dimensionless parameter; it is sensitive to the early fault of the bearing; and is insensitive to the operating conditions. When the bearing tooth surface operation appearance is faulty; the impact pulse of the running surface defect will occur every revolution; the larger the fault; the larger the impact response amplitude; the faster the KV value rises; but the severe deterioration of the bearing fault later The KV value is reduced; the opposite is the opposite; it is not sensitive to early problems; but it rises with the deterioration of bearing problems; the stability is better. Totally; the credible fruit of simple diagnosis is obtained; It is appropriate to have a degree coefficient and a comparison value; it coordinates the sensitivity and stability of the diagnosis parameters.
Simple diagnosis has a better side; but there are also many shortcomings; when the bearing is easily diagnosed; the following conditions will be presented.
*The bearing parameter value is faulty; but it cannot be determined;
*The bearing itself has no faults but because of the defects in the assembly; (such as rotor dynamic imbalance, shaft misalignment, etc.).
* When the sensor is placed in the machine base; the measured fault signal is strong and weak (the inner ring is the smallest, the roller is strong, and the outer ring is larger); thus the error is judged according to the parameters. The above three conditions are analyzed; the simple diagnosis is made. There is no way to determine the bearing component problem; it can't solve the problem of â€œrepairing according to the situationâ€; therefore, it is impossible to confirm the diagnosis of the bearing only by simple diagnosis; it is necessary to carry out fine diagnosis.
b locomotive bearing resonance demodulation spectrum analysis skills ---- fine diagnosis.
When the bearing is damaged, such as fatigue peeling, partial wear, surface corrosion, etc.; bearing and rolling rotation will take turns to crush these external damage; high-speed inner ring rotation will cause this crushing impact; The longitudinal wave induced by the impact is emitted outward at the speed of sound before the data is deformed; it has a steep frontal waveform and an extremely rich spectrum; followed by the internal damping effect of the data; the longitudinal wave of the impact is sharply attenuated; thus the sensor receives the impact pulse signal.
The impact pulse waveform is approximately rectangular; the error frequency of the rectangular pulse is extremely wide; and the natural frequency of the bearing system and various types of sensors is very low; therefore, the natural frequency of the bearing system and various types of communication chamber sensors are affected by the pulse frequency. Coverage; the frequency of the fault provokes the resonance of the bearing system and various types of sensors; the use of a passband filter to filter out unwanted low- and high-frequency noise (such as various types of noise such as mechanical vibration) only causes the fault shock pulse to provoke the bearing outer ring or The sensor resonance echoes the waveform; and the low frequency fault signal is expanded and progresses to the higher frequency echo attenuation vibration of the vibration system; the envelope demodulation expands the higher frequency response to the open low frequency signal; The instrument is transformed into a low spectrum; that is, the demodulation spectrum.
4 Cases of locomotive bearing diagnosis The following example is the case of the left side axle box bearing detected by the 4th spring wind 7D0034 locomotive on January 27, 2002; the bearing type 752732. It is tested by JL-501 bearing test bench; the speed is 500 rev / Minute.
The time domain waveform detected the diagnostic parameters; the kurtosis coefficient is 6.63, and the high kurtosis is also severely overrun; thus the test results are unqualified.
A detailed spectrum shows that the peak of the demodulation spectrum is 60HZ; and the peak distances of 1, 2, and 3 are 60HZ; the frequency of the bearing fault is calculated according to the hook of the locomotive bearing fault frequency table: 500Ã—0. 12= 60HZ; from the table to find the faulty part of the bearing outer ring; in the subsequent differentiation of the bearing found in the outer ring raceway a little erosion rolling traces.
5 Conclusion The locomotive rolling bearing diagnosis method described in this article; in the last two years of my section; I have JL-201 locomotive bearing diagnosis instrument; JL-501 locomotive bearing diagnosis table two sets of equipment. JL-201 primary use On the traction motor bearing ground detection and the top wheel detection of the locomotive bearing; JL-501 is mainly used for the dynamic detection of the rolling bearing of the middle repair locomotive.
In the past two years, a total of 2,318 sets of bearings have been tested for other sections and this section of the locomotive; a total of 189 sets of unqualified bearings have been detected; during this period, from 2001 to the present, there have been no problems with bearing faults or bearing faults; It is obvious that it is fruitful.
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