Design reason and countermeasure of gear transmission noise formation

Design reasons and countermeasures

1. Gear accuracy level
In the design of gear transmission system, the designer often considers the economic factors and determines the precision level of the gear as economically as possible, but the precision level is the mark of the noise level and backlash of the gear. The American Gear Manufacturing Association has conducted a large number of gear studies and determined that high-precision gears produce much less noise than low-precision gears. Therefore, if conditions permit, the accuracy level of the gear should be improved as much as possible to reduce gear noise and reduce transmission errors.

2. Gear width
When the gear drive system allows, increasing the tooth width can reduce the unit load at constant torque. Reduce tooth deflection, reduce noise excitation, and thus reduce transmission noise. The study of H. Opaz of Germany shows that when the torque is constant, the noise curve gradient of small tooth width is higher than that of large tooth width. At the same time, increasing the tooth width can increase the bearing capacity of the gear.

3. Pitch and pressure Angle
Small tooth pitch can ensure that more teeth contact at the same time, increase gear overlap, reduce single gear deflection, reduce transmission noise, improve transmission accuracy. Small pressure Angle because the gear contact Angle and lateral overlap ratio are relatively large, so the running noise is small and the precision is high.

4. Running speed
According to the experimental study of H Opaz in Germany, the noise level increases with the increase of gear operating speed.

5. Gear box structure
The test results show that the cylindrical box is beneficial to shock absorption, and the noise level of the ordinary gear box is 6dB higher than that of the cylindrical box under the same other conditions. The vibration and noise can be significantly reduced by conducting resonance test on the gear box, finding out the resonance position and adding appropriate bar (plate). Multistage gear transmission requires the change of instantaneous transmission ratio as small as possible, which ensures smooth transmission, small impact and vibration, and low noise.

6. Analysis of gear acoustic radiation characteristics
When selecting gears with different structure forms, the sound radiation model is established for the specific structure, the dynamic analysis is carried out, and the noise of the gear transmission system is evaluated in advance. In order to meet the different requirements of users (place of use, whether it is unmanned, whether it is in the urban area, whether there are specific requirements for above-ground and underground buildings, whether there is noise protection, or no other specific requirements).

Source: Sound House