模拟服役条件下脂润滑滚动轴承电特性变化规律研究OA

With the widespread application of power electronics technology in modern variable-frequency drive systems,bearing electrical erosion damage caused by motor bearing voltage and bearing current induced by frequency converters has become one of the primary causes of bearing failure.Currently,the assessment of bearing electrical erosion severity still heavily relies on vibration data.However,the correlation between vibration data and the extent of electrical erosion damage is weak,often requiring the presence of significant damage such as grooves on the bearing for effective detection,making early warning challenging.In contrast,electrical characteristic parameters such as bearing impedance,breakdown voltage threshold,and breakdown resistance can directly reflect the internal insulation condition and electrical performance of the bearing,exhibiting high sensitivity to micro-level changes such as lubricant degradation,oil film thinning,and initial-stage electrical erosion.Nevertheless,current research on bearing electrical characteristics remains in its preliminary stages,and the variation patterns of these parameters have yet to be systematically analyzed. This study established an experimental platform for measuring the electrical characteristics of rolling bearings.The variations in electrical characteristics of two SKF 6007-2Z grease-lubricated bearings under different operating parameters,including voltage amplitude,power frequency,rotational speed,and temperature,were measured,and the underlying causes were analyzed.The research findings are as follows:In terms of steady-state electrical characteristics,when the bearing voltage is below the breakdown voltage threshold,voltage variations have a minimal effect on bearing impedance.At low speeds,the lubricating oil film is thin,resulting in lower impedance amplitude.As the rotational speed increases,the oil film thickness increases and stabilizes,leading to a corresponding rise in impedance which gradually plateaus.At high speeds,impedance slightly decreases due to the weakening effect of shear forces on the oil film.An increase in temperature reduces grease viscosity and thins the oil film,resulting in lower impedance and potentially triggering breakdown discharge under low-speed conditions.Regarding dynamic electrical characteristics,the breakdown voltage threshold increases with higher rotational speed and decreases with rising temperature.An increase in bearing voltage intensifies the local ionization of the lubricating grease,leading to a reduction in breakdown resistance.At low rotational speeds,the oil film is thin and unevenly distributed,with weaker insulating properties,resulting in lower breakdown resistance.As rotational speed increases,a stable lubricating oil film forms,leading to higher breakdown resistance.When rotational speed increases further,frictional heating may cause localized temperature rise in the oil film,reducing viscosity and thinning the film,which results in a slight decrease in breakdown resistance.For a single bearing,the influence of power frequency on its breakdown resistance is negligible.When the bearing voltage exceeds the oil film breakdown voltage threshold,higher operating temperatures prolong the time the bearing remains in a resistive state,impairing its ability to recover capacitance.In summary,when the oil film is well-established,an increase in temperature increases the risk of electrical erosion of the bearing. This study systematically reveals the influence patterns of operating parameters on bearing impedance,laying a theoretical foundation for constructing electrical characteristic-based diagnostic and predictive methods for electrical erosion faults in grease-lubricated bearings.