The inspection items for thin-walled bearings in rolling bearings include sound, vibration, temperature, and lubrication condition, as follows:
1. Bearing Rolling Sound: Using sound equipment to check the operation of thin-walled bearings, the volume and quality of the sound will distinguish even slight peeling and other damage. Abnormal tones and irregular sounds emitted by the measuring device will be detected.
2. Bearing Vibration: Bearing vibration is very sensitive to bearing damage. For example, peeling, indentation, corrosion, cracks, and wear will be reflected in bearing vibration measurements. Therefore, by using special thin-walled bearing vibration measurement (frequency analyzer, etc.), the magnitude and frequency of vibration can be measured to infer abnormal conditions. The measured values for bearing conditions or sensor locations will differ, so each machine requires pre-determined standard measurement values for analysis and comparison.
3. Bearing Temperature: The bearing temperature can generally be inferred from the temperature outside the bearing housing. If there is a bore, direct measurement of the bearing outer ring temperature is more suitable. Typically, INA bearings operate for 1-2 hours to gradually reach a stable state. The bearing's heat capacity is related to the normal operating temperature of the machine, and changes in heat capacity, speed, and load will affect its temperature. If the lubrication of a thin-walled bearing is not properly maintained during inspection and troubleshooting, and the bearing temperature rises suddenly, abnormally high temperatures may occur. In such cases, operation should be stopped and necessary preventative measures taken.
Increasing rigidity lowers the overall sound pressure level. Therefore, for this type of bearing, increasing speed does not necessarily increase the overall sound pressure level. Higher lubricant viscosity, however, results in a lower sound pressure level for grease lubrication. The shape and size of the soap fibers affect the viscosity and noise level. Regardless of speed changes in the bearing, the main frequency noise sound pressure level remains almost constant with increasing speed. Although raceway noise in thin-walled bearings is unavoidable, it can be mitigated by using high-precision machined parts, proper selection and use of components, and minimizing bearing vibration.
The sound from the raceway is naturally generated by the vibration load on the raceway of a thin-walled bearing. When lubrication or machining precision is low, this will stimulate the bearing to vibrate in the air due to its inherent flexibility, which is then transmitted as noise. Since the raceway and rolling elements constitute a non-linear elastic contact vibration system, the sound pressure level increases significantly with increasing radial clearance.