The analysis of the causes of rolling bearing premature aging

Rolling bearing analysis of the causes of premature aging source: bearing | last updated: - 2020 04 - 02 rolling bearing premature aging can cause equipment downtime, now motor maintenance practice, the author introduces experience to prevent premature aging of the rolling bearing. Rolling bearing premature aging of the reasons are: cooperate with tight, not for the installation, poor lubrication, strong vibration, material fatigue, pollution, corrosion, etc. 1. Fit too tight when the bearing inner ring compulsory set into the shaft neck, light person will lead to severe wear at the bottom of the raceway circular trajectory, the person that weigh in the way, there will be split on the outer ring and ball or peeling. Reason: the ball and slide clearance is too small, increase torque, friction increases, bearing operating temperature is too high, causes the bearing wear and fatigue and failure. Prevent method: the restoration of bearing radial clearance, decrease interference. Bearing assembly quality inspection method has two kinds: visual observation: after the motor end cover bearing chamber with bearing, turn the end cover by hand, if freely rotary bearing, flexible, no vibration and shaking up and down phenomenon, as a qualified. Feeler gauge method: put the bearing motor end cover assembly on the base check mouth, with 0. 3 mm thick feeler to check bearing radial clearance of the week, if the largest gap position just right in the middle of above ( Motor horizontal installation) , it is assembled correctly, reliable, otherwise, bad installation. Should be appropriate to adjust the end cover position, repackaging, until qualified. 2. Cause poor lubrication is a serious lack of grease or oil dry aging. Due to the high speed motor friction heat production, high bearing temperature and oxidation discoloration, show the bearing ball, cage and inner ring and shaft neck place such as brown or blue. Prevent method: according to the running time of the motor, environment temperature, load conditions, good or bad grease and other four factors, determine the oil and oil change time. In general, the motor running 6000 ~ 10000 h should fill oil once; Running 10000 ~ 20000 h the oil should be replaced once, in a minimum of 2 or 4 pole motor oil in bearing chamber volume of 1/2 ~ 2/3, and should adopt high quality lithium grease ( Code ZL - 2) 。 3. If not for the installation to, is not only the bearing slide usu mark, uneven and ball bearing wear trace, also produce deviation, with feeler check bearing radial clearance on either side of the range, and large difference. The reason may be directly with the iron hammer percussion bearing outer ring; Belt is pulled ( Gear wheels) Too tight; The driving wheel and driven wheel centerline is not parallel. When the deviation is greater than 1/1000, will cause the bearing operating temperature is exorbitant, slide and ball bearing severe wear, shaft bending and end cover bolt clamping surface and bolt axis is not perpendicular. The correct installation method: use the end surface smooth level off, and the thickness of bearing inner ring of steel pipe sleeve is almost equal, the bearing pressure on the clean and correct position of the journal. Pressure is fashionable force should be homogeneous, not too hard. Then according to the motor rotation speed check shaft end radial deflection of allowed value. 4. Strong vibration when malfunction with the motor iron core, bearing strong vibration. The reasons are: core thermal deformation; Motor bearing aging; Shaft bending deformation; Loose end cover check mouth tighten bolts for vibration; Foundation is not solid bearing vibration. Small car, preventing methods: core soaking with silicone varnish 1052 silicon steel sheet surface and the gap of open; Replace the same model of the new bearing; Exit the rotor core straightening shaft bending part; With 180 ° symmetric method; Tighten the cover through bolts; Strengthening the foundation, and tighten the anchor bolts. 5. Material fatigue due to metal material, bearing raceway and the ball off the surface of the irregular fragments if mixed in lubricating grease, it will make noise increases, the ball was in sliding state, lead to bearing radial clearance increases, and the deflection of shaft end allowed radial value increases 2 ~ 3 times. Bearing fatigue degree of decision factors include: the motor load, speed, air gap, end cover type, the toughness of the material, the quality of grease grease add quantity. Prevent method: according to the motor running records, when light load current work for more than 60% of the rating, running to 2000 ~ 25000 h, medium load working current for rating of 60% ~ 80% run to 15000 ~ 20000 h, heavy work load for current rating of 80% ~ 100% to 10000 ~ 15000 h after operation, all should consider normal bearing material fatigue, replace new bearing the same model. 6. Pollution corrosion at this point, the raceway and ball appears on the surface of the red and brown punctate, corrosion, compared with the new bearing noise work noise increases. Reason is that the assembly place is clean, such as the presence of moisture, acid, alkali, and toxic gases; Hand tools and pollution; USES the lubrication of the inferior quality goods. Prevent methods: bearing assembly must keep the environment, tools, and the clean; Clean the bearing thoroughly; Change the quality of lithium grease.