Locomotive rolling bearing fault detection and diagnosis
2023-08-07 12:09:14
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Locomotive rolling bearing fault detection and diagnosis
Source: Bearing network time: 2014-09-28
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2 The bearing's faulty bearing is often not caused by a single cause; it is inductive effect 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.
2.1 The abnormal wear of the bearing 2.1.1 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 the disadvantages and scars; the smoothness of the bearing is formed; The heat of the bearing; the long-term heat; will lead to: (1) the dilution of the bearing smooth oil. (2) accelerate the fatigue of the raw materials; the hardness is reduced. Because of the above reasons; and further constitute a vicious circle; accelerate overheating and burn the bearing. Severe bearing inner ring displacement; roll body out of round; resisting heat generation; end welding together. Therefore, when running on line; if the bearing is found to be severely heated and smoked; do not park; At this time, the overheated bearing is in a molten state; once the parking is cooled, it can no longer walk; blocking the positive line.
2.1.2 is very important for the oil supply protection of the locomotive bearings; especially the excessive oiling of the bearing can ensure the bearing has an outstanding smooth effect; the lack of oil and excessive oiling are also very simple to constitute a bearing fault; the oil is less simplified. The bearing is made of poor smoothness and heat; if it is added, it will simply constitute mixing and overheating; therefore, it is necessary to supply oil in the protection; the hygiene of the smooth grease of the bearing is also very important; once other impurities and moisture are dropped into the grease, it will affect the normal. The clearance and the establishment of the necessary oil film.
2.1.3 bearing is used for too long; beyond the service life of the bearing, it simply constitutes the fatigue of the raw material; coupled with the intense impact effect, the raw material is deformed; the roller and the raceway surface are peeled off and the film is rolled; Smoothness and vibration increase.
2.2 The influence of the device on the bearing 2.1.2 The internal clearance of the bearing inner ring and the shaft is inconsistent with the interference; it also constitutes a simple bearing fault; the interference is large; it is very simple to form the inner ring of the bearing due to excessive tensile stress. And cracked; the amount of over-exposure.
2.2.2 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, The temperature of the outer ring and the end cap are not the same; there is a temperature difference between them; therefore, the amount of expansion is slightly different; that is, the further reduction of the cooperative gap is formed; the heat generation of the bearing is added. The gap is too large; the vibration of the roller Increase; increase the impact of the roller and the raceway; together, it is easy to form uneven distribution of internal load; load roller reduction; central roller load is too large.
2.2.3 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 bearing fault diagnosis and diagnosis Currently, the method of detecting bearing faults in China generally has 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 in 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.
3.1 locomotive bearing diagnosis method There are two main methods of locomotive bearing: (1) simple diagnosis of locomotive bearing; (2) locomotive bearing resonance demodulation spectrum analysis skills ---- fine diagnosis.
3.1.1 Simple diagnosis; in the vibration detection, it is usually to judge the condition of the bearing by comparing the large and small values ​​of certain vibration parameters; in the simple diagnosis of the locomotive bearing; The KV, and acceleration value parameter Xrms of the time domain kurtosis coefficient parameters are used as the discriminant parameters; the kurtosis target KV is a dimensionless parameter; the early fault of the bearing is sensitive; and the operating condition is Insensitive; when the bearing tooth surface operation appearance is faulty; the impact pulse of the working surface defect will occur every revolution; the larger the problem; the larger the impact response amplitude; the faster the KV value rises; Deterioration and KV value is reduced; while the value is opposite; it is not sensitive to early problems; but it is rising with bearing defects; stability is better. Total; to obtain reliable and reliable results; It is appropriate to use the kurtosis coefficient and the comparison value; it co-ordinates 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 occur; (1) bearing parameter value is faulty; but can not determine its fault location; (2 The bearing itself has no faults but because of the defects in the assembly; (such as rotor dynamic imbalance, shaft misalignment, etc.). (3) When the sensor is placed in the machine base; the measured fault signal is strong or weak ( The inner ring is the smallest, the roller is strong, and the outer ring is larger. In this way, the error is judged according to the parameters. The above three conditions are analyzed; the simple diagnosis does not determine the fault of the bearing component; the problem of “repairing the situation†cannot be solved; Therefore, it is impossible to confirm the diagnosis of the bearing only by simple diagnosis. It is necessary to carry out fine diagnosis.
3.1.2 finely diagnosed 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 make this kind of grinding Pressure shock; the longitudinal wave induced by this fault shock 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; 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 bearing system and various types of communication room sense The natural frequency of the device is masked by the frequency of the impact pulse; the frequency of the fault provokes the resonance of the bearing system and various types of sensors; the use of the passband filter to filter out unwanted low and high frequency noise (such as various types of noise such as mechanical vibration) only makes The fault shock pulse stimulates the bearing outer ring or the sensor resonance echo waveform to pass; and the low frequency fault signal is expanded and Step echo higher frequency vibration of the vibration damping system; envelope demodulation of the higher frequency echoes will be further expanded to open the low-frequency signal; by converting a low frequency spectrum analyzing instrument; spectrum is demodulated.
4 locomotive bearing diagnosis case The following example is the case of the fourth left axle box bearing detected by the spring breeze 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 6.6, and the high kurtosis is also severely overrun; thus the test result is unqualified. Together with the refinement spectrum, the peak of the demodulation spectrum is 60HZ; The peak distances of 1, 2, and 3 are 60HZ; the frequency of bearing faults is calculated according to the hook of the locomotive bearing fault frequency table: 500×0. 12=60HZ; the faulty part is found from the table as the bearing outer ring; in the subsequent differentiated bearing Found that the outer ring raceway is a little eroded and crushed.
5 Conclusions 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 The detection of the traction motor bearing ground 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, 2318 sets of bearings have been tested for other sections and the middle repair locomotive of this section; 189 sets of unqualified bearings were detected; during this period, I did not have any bearing problems or bearing defects caused by bearing faults from 2001 to the present; I received obvious results.
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