What to do when the motor bearings get hot on a hot day?
Author: hongyuanTime:
The bearing system is a very critical part of the motor product. After the summer, the weather is gradually hot, and the high temperature environment may bring excessive burden to the bearings, when the bearings have problems, the bearings will wear out prematurely and fall apart because of the heat, which must be given prevention and attention.
Small motors generally use ball bearings at the front and rear ends, while medium-sized motors use roller bearings at the drive end and ball draw bearings at the other end. In the failure of the asynchronous motor, the damage of the bearing also occupies a certain proportion, so the maintenance and repair of the bearing is also very important.
The causes and treatment of motor bearing heating
If a bearing fails to heat up, the grease may melt and leak out, or the bearing may burn up! The causes of bearing heat failure are generally as follows.
(1) Bearing cover and shaft friction
Due to the eccentricity of the inner circle of the bearing cover or the assembly was knocked out burr, resulting in partial friction with the shaft to make the shaft hot.
The burr on the bearing cover can be repaired by fine sitting, such as the inner circle of the bearing cover is eccentric, can be reworked on the lathe to repair. If the bearing cover and shaft have been worn, the shaft can be re-sharpened and the bearing cover generally needs to be replaced with a new one.
(2)The inner and outer circle of rolling bearing is not flat
Due to the processing error, may make the assembly of the two end caps on the bearing hole different heart, resulting in bearing inner and outer circle is not parallel. Ball bearings have a certain adaptability to non-parallelism.
Roller bearings due to roller and inner and outer ring contact non-parallel, increasing the friction loss, so that the bearing heat.
If the concentricity error is not large, the motor will disappear on its own after a period of no-load operation. If the concentricity error is large, the roller bearing will often get hot and burn out. At this time, the concentricity of the housing and the end cover should be carefully checked and corrected.
(3) The grease is not clean or the amount is not appropriate
If the stream slip grease mixed with sand and iron chips and other foreign matter, easy to cause bearing heat and damage.
The bearing in operation can be heard in the following way: the sound of rustling, the end of the screwdriver (open the cap, unscrew the screws and other tools) is close to the outer cover of the bearing, and the ear is pressed against the handle of the screwdriver can hear this sound.
If this is the case, the bearing cover should be removed and the bearing cleaned and replaced with a clean, compliant grease. If the grease is too much, the motor will be hot when it starts to run, and some of the grease will be squeezed out from the bearing cover gap, and the heat phenomenon will be eliminated soon.
If the grease is too little, you can hear “rubbing” or a slight “clucking” sound, causing the bearing temperature to increase, then you should add the same grease as the original specification, the temperature can drop.
General underground scraper conveyor, tape conveyor motor should be regular small repair, clear the motor fan on the coal dust and debris, bearing should be filled with grease once a month, every 3 months cleaning and oil change to maintain a good lubrication status.
(3) Bearing clearance is too small or too large
Bearing clearance is too small, due to the oil flow in the gap shear friction loss is too large, will also cause bearing heating; at the same time, the gap is too small, the oil volume will be reduced, too late to take away the heat generated by friction, will further increase the bearing temperature rise.
However, too large a clearance will change the dynamic characteristics of the bearing and cause the rotor to run unstably. Therefore, it is necessary to select the verified bearing clearance for different equipment and use conditions.
In addition, motor body vibration and poor mechanical alignment can also cause high shaft tile temperatures.
When the motor bearing is found to be overheated, the following methods can be referred to for treatment.
( 1 ) Bearing damage. Replace the bearings.
( 2 ) Too much or too little lubricating grease, bad oil quality, impurities. Check the oil volume: it should be 1/3-2/3 of the bearing volume as appropriate, and replace the qualified lubricating oil.
( 3 ) bearing and journal or end cover with too tight or too loose. Too tight should be grinding journal or end cover bore. Too loose available adhesive or low temperature iron plating treatment.
( 4 ) bearing cover bore eccentric, and shaft friction. Repair the bearing cover so that the clearance between it and the shaft is suitable and even.
( 5 ) The end cover or bearing cover is not installed flat. Reassemble.
( 6 ) The coupling between the motor and the load is not corrected, or the belt is too tight. Re-correct the coupling and adjust the belt tension.
( 7 ) Bearing clearance is too large or too small. Replace with new bearings.
( 8 ) The shaft is bent. Straighten the shaft or replace the rotor.
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