The experimental system consists of three-stage planetary gearbox, motor, brake and its switch, sensors (acceleration sensor, eddy current sensor, etc.) for data acquisition. The acceleration sensor is placed to collect vibration data. Among them, measuring point 1 collects the vibration signal of the second stage of planetary gearbox. Measuring point 2 collects the vibration signal of the third level horizontal position of the planetary gearbox. The vibration signal of the third stage vertical position of the planetary gearbox is collected by measuring point 3. The real-time speed of the output shaft can be obtained by placing eddy current sensor at measuring point 4.

The data analyzed by ZHY gear adopts the vibration signal of the third level horizontal position of planetary gear box collected by measuring point 2; the sampling frequency is set at 20 480HZ, the sampling time is 10 s, and the sampling interval is 10 min; the total transmission ratio of planetary gear box is 77.3, the rotation frequency of high-speed shaft is 600 R / min; the torque of magnetic powder brake is set at 8.33 n · M.

The experiment lasted for 9 300 minutes. The experimental results show that the third stage of planetary gear box is severely worn.

The life cycle test bench of planetary gearbox is shown in the figure.

In order to speed up the experiment process, two methods are used to accelerate the process of fatigue life test

(1) the brake is used to load the planetary gearbox to accelerate the wear process of the gear;

(2) a planetary gear of the third gear train is replaced with a gear without surface heat treatment, so that the gear has a lower surface hardness and accelerates the wear process of the gear.