- Single tooth pitch error
(1) Time domain characteristics
The existence of single tooth pitch error will lead to the problem of local impact during the rotation of one circle gear. When the local impact energy is significantly higher than that of the other teeth, it shows the instantaneous pulse characteristics with the rotation frequency as the period in the time domain, as shown in Fig. 1.
(2) Frequency domain characteristics
The gear vibration signal is mainly divided into two parts: tooth frequency carrier wave and frequency modulation wave. Due to the instantaneous pulse characteristics with the period of turn frequency, there is a certain effect of frequency modulation and amplitude modulation on the carrier in the time domain. Therefore, after entering the frequency domain through Fourier transform, the side band is evenly distributed around the tooth frequency, and the frequency interval is called frequency conversion, as shown in Fig. 2.
- Cumulative pitch error
(1) Time domain characteristics
The cumulative pitch error in the angle domain is a gradual error of quasi sinusoidal function. Therefore, the characteristic of vibration signal in time domain is also a gradual amplitude fluctuation, which is a typical amplitude modulation phenomenon. Its essence is the amplitude modulation effect of the frequency conversion signal on the tooth frequency signal. It can be understood that during the meshing process of one circle, due to the influence of accumulated pitch error, the meshing energy of gear teeth fluctuates periodically, as shown in Fig. 3.
(2) Frequency domain characteristics
It has been pointed out in the previous paper that after Fourier transform, the time-domain amplitude modulation problem shows that the side band is evenly distributed around the tooth frequency in the frequency domain, and the frequency interval is the frequency conversion, as shown in Fig. 4.
