Figure 1 shows the profile deviation measurement curve of aa-1 gear working tooth surface (left tooth surface) after running for 4 million times. It can be seen in the figure that the gear deviation value slightly floats at the lower side near the pitch line. The measurement results show that the maximum total profile deviation is 3.7 μ m and the maximum profile shape deviation is 2.4 μ M. By observing the tooth surface characteristics recorded in the photos, the naked eye can see that there is a slight local gray spot belt phenomenon in the corresponding parts, and the gray spot belt along the tooth profile direction is narrow. This phenomenon may be caused by the uneven wear of the tooth surface after the gear running in and the load change when the single and double teeth alternate near the lower side of the pitch line. At the same time, from the tooth surface measurement deviation value, the deviation value is small, it can be seen that the gear is still in the state of tooth surface integrity at this time.

The vibration acceleration value of the bearing pedestal measured at the interval of 1 million cycles is selected to study and analyze the dynamic response characteristics of the system. Because of the huge data recorded by 1 million cycles, it is convenient to process the data signal without losing the evolution process of the signal, the time domain signal truncation method is used for data processing and analysis. The data of three stages of equal interval cycle times in the early stage (200000-300000 times), the middle stage (600000-700000 times) and the late stage (900000-1000000 times) are selected respectively to compare the performance of time-domain signal and different statistical indexes after data processing, so as to elaborate the dynamic response characteristics of gear in this 1000000 cycle times. The time domain response signals of vibration acceleration along X vector and Y vector in the early stage, middle stage and late stage are shown in Figure 2.

In Figure 2, the vibration acceleration time domain signals along X vector and Y vector show a steady change phenomenon in different cycles. Among them, there are the increase or decrease of local acceleration in 220-230000 times and 250-260000 times in Fig. 2 (a), and the increase of acceleration along y vector in 650-670000 times in Fig. 2 (b). The calculation parameters of the statistical indexes in the table are shown in the range of the number of cycles intercepted by the three sections. The data values of the corresponding statistical indexes g, G2, G4, G3 and G7 are almost the same no matter along the X vector or Y vector. It also indirectly reflects that the dynamic response of the gear system is in a stable state within the 1 million cycles, and the gear system is stable The feature of tooth surface belongs to normal wear feature. From the skewness index GW, except that the value along the X vector within 200000-300000 cycles is – 0.225 less than 0, the other values are greater than 0, which indicates that most of the vibration acceleration distribution within the cycle times presents a positive skew (right skew) state. According to the macro statistical method, the dynamic response of the system within the 1 million cycle times is in a positive skew state. Similarly, from the kurtosis index point of view, the kurtosis value within the cycle number is greater than 0, and the maximum value is 3.969. The results show that the distribution of vibration acceleration value is concentrated in the range of each interception cycle number, showing a peak state, and the larger the value is, the more obvious the peak is. Based on the above discussion and analysis of the vibration acceleration in Fig. 2, it is shown that the system is in a good running state within 1 million cycles of gear operation, and the tooth surface features are relatively complete, which is in the normal wear stage.