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On the mill reducer fault diagnosis using vibration monitoring

Number of visits: Date:2015-04-28
The reducer is a key part of the mill, its running state directly affects the safe operation of the mill. Vibration value judgment is reducer running quality and the main parameters of whether there is a fault. In the operation of the vibration of gear reducer for monitoring, and according to the value of monitoring the running state of the analysis judgment and fault, is an advanced method of modern predictive maintenance management. Analysis and treatment of vibration monitoring and fault based on the two series of MBY type edge mill drives the reducer, summarizes the factors which cause the vibration of the speed reducer, and through the method of practical experience and mathematical statistics to determine the series reducer vibration limit value.
1 evaluation parameters and the selection of vibration monitor
Three parameters for evaluation of vibration size displacement, velocity and acceleration respectively. The ultimate peak or peak displacement reflect the equipment position change value, effective value of speed (RMS) circulation velocity reflects the deformation energy and load equipment parts, namely, fatigue life, reflects the effect of acceleration caused by inertial force. Because of the speed reducer is low, the effective value of vibration velocity (RMS) is more reasonable and effective value of vibration and the international standard and national standard of China is the preferred as evaluation parameters of vibration velocity of vibration of rotating equipment, the choice of the effective value of vibration speed evaluation. Measuring device selection handheld vibrometer, the peak to peak value and the effective acceleration, vibration measurement of vibration displacement, and the price is cheap, easy to carry.
2 monitoring and periodic location selection
Because of the high speed gear shaft gear and bearing fault of gear reducer, the choice of bearing at both ends of the high speed gear shaft gear device as the monitor position, respectively, the horizontal and vertical vibration and axial measurement; at the same time, the bearing of mill pinion at both ends of the aided measurement for comparison and analysis. The measurement cycle is generally a week or two on Monday, but the vibration increases or the replacement of parts to increase the number of measurements.
The 3 main factors that cause the vibration of the speed reducer.
Mesh size caused by vibration mill gear 3.1
3.1.1 vibration mill gear oil shortage caused by size
Lubrication of gear grinding size should be good, to form a lubricating oil film to reduce wear and vibration absorption and noise reduction of temperature, when the size of the gear oil less or lack of oil, the size of gear meshing surface will be dry friction, which increases the size of the gear vibration, bearing vibration noise increases, the increased by coupling to the reducer the vibration of reducer, the increase of. Table 1 the number from 1 to 4 2.6m in diameter and 13m (cement mill reducer model for MBY710-4.5-IR power transmission input speed, 1000kW, 740r/min) the size of gear oil when the bearing block of the small gear and reducer high speed gear shaft bearing vibration monitoring value. Table 1 data shows, the size of the gear oil shortage caused by the bearing block of the small gear and reducer bearing grinding vibration value increases a lot, especially vibration in horizontal direction increases more, greater deceleration clutch bearings and gear effect.
The vibration caused by the size of the 3.1.2 mill gear wear
The size of the mill gear wear and backlash meshing gear overlap coefficient increases, decreases, resulting in larger vibration. Table 2. 3.2 x 5.8m mill (reducer model MBY800-6.3-IR, transmitting power 780kW, input speed 980r/min) because of the small gear wear is large and small gear replacement value before and after vibration monitoring. From the data in Table 2 that in large size gear, wear, vibration direction of pinion bearing the axial bearing vibration increases greatly, and the vertical direction caused by the speed reducer gear shaft increases more, in replacement of the small gear, the size of gear tooth surface in the running in period, because the tooth surface contact bad, even greater than the initial value of vibration replacement of small vibration gear before, but after a period of time after the run, the vibration value is reduced, finally achieve better state.
3.2 reducer itself bearing fault or gear meshing vibration caused by bad quality
The bearing of the high speed gear shaft reducer operation with diameter of 2.6m * 13m cement mill (model 23236CC/W33) repeated failure, mainly for the bearing outer ring, inner ring and run run bearing etc.. Reducer bearing wear, vibration reducer increased significantly, from table 1, number 4 and number 5, 6 data comparison can be seen, horizontal, vertical and axial vibration increase more, at least 1.6 times the normal value is increased. From table 1, No. 7, 8, 9 can be seen, the replacement of the reducer gear shaft, bearing and corrected, as the new high speed gear shaft gear has a run in period, and low speed gear reducer so early, the replacement, the vibration is increased, then decreased slowly.
3.3 vibration reducer and motor or the pinion shaft misalignment
It is seen from table 1 the number of 1 to 7 of the gearbox vibration data can be greater than the horizontal vibration, axial vibration, on the one hand, due to the presence of misalignment problem during installation, on the other hand, bearing wear, but also exacerbated the reducer high speed gear shaft and the motor shaft misalignment, in the high speed gear shaft of the reducer reducer the low speed shaft and pinion shaft on the motor shaft, and the corrected value is greater than the level of vibration, axial vibration value, then, due to the electric motor bearing heating, we found out the bearing, and bearing wear up to 0.3 ~ 0.5mm, finally, we replace the bearing, in the premise of the position adjustment speed reducer, two basic on the. For the bearing, reducer vibration decreases a lot, especially the axial vibration decreases a lot

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