Gear box noise classification:
For the reasons of the gearbox vibration noise, is thought to be due to the gear transmission system in the process of transmission, due to the change of tooth mesh stiffness, the manufacture or assembly error and mesh impact factors cause the vibration of the gear teeth, and through the shaft, bearings and to the body.
Generally speaking, the noise sources of the gear system include the dynamic excitation of the gear system itself, the vibration of the original motive and the vibration and load change of the working mechanism. The noise is mainly caused by the dynamic excitation of gear meshing.
The noise of gearbox can be discussed in two cases.
1. Open gear box, this kind of gearbox noise, when is mainly due to the gear meshing is impacted by the meshing and the action of alternating load produces vibration, the vibration transmission, on the basis of solid sound in sequence by gear, shaft, bearing, box, the radiate noise due to the vibration of the box body, and the gear, shaft, bearing itself as the noise of gear box opening transmission noise.
2. Closed gear box, mostly used in engineering is closed gear box, for closed gearbox noise can be considered to be caused by the transmission in the process of dynamic incentive gear vibration, vibration caused by shaft bearing, thus through the vibration and radiation noise of gearbox housing.
The noise of gearbox system can be divided into two kinds, namely structural noise and air noise. Structural noise refers to the form of gear vibration transmitted by solid sound, which is transmitted to the box by gear, transmission shaft and bearing. Finally, the noise is emitted by vibration of the box wall. Air noise is caused by gears, shafts and bearings themselves as noise sources, and the noise generated by vibration is transmitted from the opening of the gearbox. The closed gear box can ignore the air noise and only consider the structural noise.
Conventional noise reduction method for gearbox [35-36] :
1) structural optimization, including the selection of structural materials, aiming at noise reduction of the structural parameters optimization design, change the machine's working principle to reduce the input of energy, improve the machining accuracy and surface quality, etc.
2) active noise reduction, setting additional sound sources, to counteract the energy of noise by generating sound energy corresponding to the noise source.
3) sound insulation, sound absorption and vibration isolation. Sound insulation, the use of high density materials to close the sound source, to achieve the goal of noise reduction. Sound absorption, through the addition of sound absorption material, causes the sound energy loss, converts to heat energy, and avoids the occurrence of reverberation to produce a long time, thus achieves good noise reduction effect. Vibration isolation, vibration energy transmitted from source to add some about the path of the structure of the intermediate links, to reflect most of the vibrational energy, and part of the vibration energy consumption by the vibration source, the noise control structure.