During the work of the bearing, due to the influence of external or internal factors, the original fit clearance is changed, the precision is reduced, and even "seizure" is called clearance change failure. External factors such as excessive interference, improper installation, expansion caused by temperature rise, instantaneous overload, etc., and internal factors such as retained austenite and residual stress in an unstable state are the main reasons for the failure of clearance changes.
1. Turn the outer ring, and carefully rinse the cage, rolling element and raceway junction, to thoroughly clean any previously hidden parts of oil residue. Bearings should be rinsed clean and dry-cleaned after being attached, and the clean lined neutral table supports are dried, or slowly dried in a far-infrared drying oven. Since even dry cleaning and drying or drying, the entire process should not put the bearing rings, adhere to any frame or rolling elements. Universal joint bearing oil can be removed from the oil-sealed packaging before delivery for testing in practice, and immersed in acid-free 3% kerosene or gasoline for cleaning.
2. Check on request for drip lubricating oil and immediate delivery, dry or dry bearings. At this time, there is no oil film to protect the outer surface of the bearing. The inspectors are not allowed to directly touch the skin during the whole process. The operator should wear clean gloves and paint with rust by hand, but must avoid mixing the antirust agent on the appearance of the rolling bearing. hands, otherwise the measurement results will be biased.
3. The bearings should be inspected immediately after being served or treated with rusted stock, and the entire inspection process should be completed. Too long to avoid corrosion. Pay attention to the use of clean and oil-free pure gasoline, which can also cause corrosion.
4. If the bearing is dry or dry, the outer surface without bearing oil film protection should be inspected according to the regulations for dripping lubricating oil and immediate delivery. At this time, during the entire inspection process, manpower that directly touches the skin is not allowed, and the operator should wear clean gloves. , hand-painted with rust, but must avoid mixing hands with anti-rust agent on the rolling surface of universal joint bearings, otherwise it will cause deviations in the measurement results.
5. The inspection of the bearings is completed immediately after delivery or during the rusty inventory process, and the entire inspection process should be seized as far as possible not to last too long to cause corrosion. Pay attention to the use of clean and oil-free pure gasoline, which can also cause corrosion.
The influence of grinding quality on bearing premature failure From the above test results, it can be concluded that grinding cracks and grinding burns on one side of the raceway are a direct cause of ring cracking and premature bearing failure. The distribution characteristics of the crack macroscopic shape and grinding burn show that the original position of the raceway is too biased or the R of the raceway is not round, which increases the grinding allowance on one side of the raceway. When the cutting speed is fast, the entire raceway will produce uneven grinding. If the grinding wheel is not trimmed in time, it will cause the grinding debris to embed or stick to cause the pores of the grinding wheel to be blocked and passivated, which will cause the unbalance of the grinding wheel to increase, the vibration of the spindle will intensify, and even the vibration of the machine tool will cause grinding chatter. Obviously, the grinding force changes periodically, forming intermittent burn bands.
In order to further understand the hardness distribution of the ferrule and the microstructure of quenching and tempering and the microstructure of the surface layer, the partially cracked inner ring and its fragments are selected, and the macroscopic hardness is determined on the end face, and the wire cutting method is used to crack the inner ring. Cut longitudinal metallographic samples near the center.