Raceway sound is a kind of steady and continuous noise caused by the rolling object rolling in the raceway when the bearing is rotating. It is noticed only when the sound pressure level or tone is very high.In fact, the sound energy excited by raceway sound is limited. For example, under normal circumstances, the sound of raceway of the high quality 6203 inlet bearing is 25 ~ 27dB.This kind of noise is most typical of single row deep groove ball bearing bearing radial load. It has the following characteristics:
A. Noise and vibration are random;
B. Vibration frequency above 1kHz;
C. No matter how the rotating speed changes, the main frequency of noise is almost unchanged while the sound pressure level increases with the rotating speed;
D. When the radial clearance increases, the sound pressure level increases sharply;
E. With the increase of the rigidity of the inlet bearing seat, the lower the total sound pressure level is, even if the speed increases, the total sound pressure level will not increase much;
F. The higher the lubricant viscosity is, the lower the sound pressure level will be. However, for grease lubrication, its viscosity and the shape and size of soap fiber can all affect the noise value.
The source of raceway sound is the natural vibration of the ring after being loaded.The elastic contact between the ring and the rolling body constitutes a nonlinear vibration system.When the lubrication or machining accuracy is not high, the inherent vibration associated with this elastic characteristic will be excited and transferred to the air will become noise.As is known to all, even if the most advanced manufacturing technology is adopted to process imported bearing parts, there will always be a small degree of geometric error on the working surface of the bearing, so that there will be small fluctuations between the raceway and the rolling body to stimulate the inherent vibration of the vibration system.
Although raceway noise of imported bearings is inevitable, it can be reduced and vibration reduced by adopting high-precision machining parts' working surface, correct selection of imported bearings and accurate use of imported bearings
Fatigue spalling refers to the spalling of the working surface of the bearing due to rolling fatigue.
When the inlet bearing works, the load of the rolling body and the inner ring (or the outer ring) is not constant, but changes with the running cycle of the bearing.This load is an alternating load;And because the contact area between the rolling body and the inner ring (or outer ring) is very small, the contact stress is very large. At a high speed, under the action of huge alternating contact stress for many times, the metal will suffer from fatigue., visible tiny cracks in the area of stress concentration, due to the effect of lubricating oil and the corrosion of the metal, make the crack expanding gradually, when expanded to a certain degree, the surface metal flake will produce, form small pit, similar pitting, we in overhauling bearing, often found in or outer ring and roller surface pitting and flake pieces of metal, this is the phenomenon of metal fatigue spalling.
The fatigue spalling of the inlet bearing shall be regarded as natural damage if it occurs after the bearing has been in operation for a long time, and unnatural spalling if it occurs during the middle or early period of the bearing's use, at which time the cause of spalling shall be identified.
2, non-natural spalling Is caused by human factors in the bearing in the middle or early use of spalling.
The main reasons for the non-natural spalling are improper bearing type selection or improper installation.
(1) Spalling caused by improper bearing type selection. Early spalling may occur if deep groove ball bearings are selected under large axial load.The spalling occurs mainly in the raceway, which makes the rolling track of the rolling body move towards the loading orifice, or even roll over the loading orifice, and finally causes serious spalling damage in the raceway.The measure to prevent this kind of damage is to select bearings rationally according to their working conditions.