Action Mechanism of Al₂O₃ Abrasive on Gear Wear Behavior under Impact Load

In order to explore the wear characteristics and evolution mechanism of large-scale wind power generation gears under impact load under the three body abrasive wear state, it is necessary to analyze and study the wear characteristics and working state of 45 steel helical gears mixed with initial abrasive particles. An integrated data acquisition test-bed was built, and 800 ml (0.2 mg/ml) Al₂O₃ three body abrasive oil was added to the test gearbox. In the experiment, 32 Caltex White Oil Pharma was used to accelerate the wear process of the test. The lubricating oil had good oxidation stability, a viscosity index of 32 and a flash point of 208 ℃. Oil bath lubrication was used in the test gearbox. This method was fully lubricated. The friction surface affected by the oil bath was covered with an oil film during the whole process of wear. The impact load (40 N·m) applied by the magnetic particle brake was used to simulate the actual working conditions. In addition, the application frequency of the impact load was set to be applied every 30 minutes and completed every two minutes. In the test, 20 ml of oil samples were taken from the test gearbox every 60 minutes. For the obtained oil sample, 5 ml was taken to prepare the spectrum, and the remaining 15 ml was detected by the YJS−170 particle counter to determine the abrasive particles in the oil size and quantity. At 147 h, the vibration and noise of the gear in the experimental group increased, the wear rate continued to rise, and finally there was an impact noise. The gear was taken out and broken. It was judged that the gear was invalid at this time. After the experiment, the tooth surface of the failed gear was sliced by wire cutting. Combined with the oil samples obtained during the experiment, the wear mechanism was studied from four aspects: gear wear, tooth surface wear morphology analysis, oil analysis and vibration analysis. The wear particles in the oil sample and the damage morphology of the gear tooth surface were observed by particle counter, single ferrograph and scanning electron microscope. The results showed that the initial hard particles accelerate the wear of the gear tooth surface, leaded to the gear entering the fatigue wear stage in advance, and caused serious damage to the tooth surface, resulting in large wear particle size. The loading method of applying impact loaded to helical gears intensifies adhesive wear, expanded stress concentration, and caused large abrasive particles on the surface to fall off, resulting in gear fracture and failure. Observe the wear of gear tooth surface. Under the repeated action of impact load, the part above the pitch line of gear tooth surface was seriously worn and deformed; Fatigue wear occurred earlier in the group with hard particles. Based on the oil wedge theory, pitting corrosion was easy to occur during the operation of the gear, resulting in plastic deformation and surface hardening, and finally large pieces of surface material fall off. The research focused on the abnormal condition of wind turbine gear, which was prone to abrasive wear in sandy environment. The research results will provide a theoretical basis for improving the wear state of wind turbine gears under this abnormal condition.