There always exists the vibration and noise problem accompanying with the gear system due to the variation of the contact force between the meshing teeth. To reduce the noise and vibration of running gears, most of the high quality gears are accurately finished by the grinding process, on the other hand, the low quality gears are usually finished by the simple lapping - a self-lapping process of the meshing teeth with lapping powder.
In this study, the vibration and noise reduction effect of simple lapping for low quality gears is investigated, as well as the proper lapping condition and lapping time.
To execute the simple lapping process and to measure the noise and vibration levels of running gears, a gear test rig of the power-circulating type is established in a semi-anechoic room. Five pairs of standard involute spur gears are tested to observe the changes of the tooth profile due to lapping and the noise and vibration levels of variously lapped gears.
As an experimental result, it is found that through the simple lapping the tip and the root of tooth are more lapped than the pitch point, so that the tooth profiles tend to be changed to the form of tooth profile modification. Consequently this tooth profile modification effect reduces the noise and vibration, but the tooth profile errors of over-lapped gears are so much increased that the noise and vibration levels are rather raised up. It is also found that the lapping with sufficient loading is more efficient than that without loading for uniform modification of each tooth profile. The proper amount of lapping with loading is found to be from 1000 to 2000 revolutions in testing pairs and the maximum vibration level reduction is as much as 3-5 dB whereas the noise level, 5-7 dB.
