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  • 1月 24, 2021
  • News

The noise of the planetary gearbox has a great influence on the smoothness, contact accuracy, motion accuracy and assembly accuracy of the work piece. To reduce the noise of the gearbox, it is important to understand the cause of the noise. Noise is caused by vibrations caused by force changes in bearings and bearing housings while the inner gears are running. The main criterion for rating the quality of the gear reducer is the noise value. Noise-cancelling planetary gearboxes have noise dedes less than 45dB.
Factors that cause too much noise in the gearbox:
1. The influence of the parameters and structural design of the gears of the planetary gear reducer on the noise: the greater the re-fit of a pair of gears in the transmission, the less the noise will be. To be sure, the smaller the fit, the greater the noise. It is of great significance to improve the smoothness of gear transmission, reduce noise and improve carrying capacity to increase the number of teeth involved in meshing.
2, the accuracy level of the gear is an important sign of the noise level: for the standard series of planetary reducers, the noise value depends on the accuracy of the gear manufacturing. The higher the flank accuracy, the denser the contact marks on the meshed flank, and the less noise there is on the entire flank. In contrast, the lower the gear accuracy, the smaller the contact marks on its meshed flanks, the more the gears cannot fully engage in their contact width, the operation is not smooth, and even will produce collisions, so that the noise value increases.
3, the impact and noise generated by the pitting of the flank: after a certain period of time, the transmission gear carrier running wheel often appears near the flank joint line small pieces of metal shedding, forming pitting, due to the hard flank gear has the advantages of large carrying capacity, small size, light weight, good transmission quality and so on. Although hard wheel is not easy to corrode, it is widely used. But it’s not easy to run after pitting. The pitting of the tooth surface increases rapidly as the working time increases. Evolution into diffuse corrosion causes mutual damage between teeth, increasing working noise and shock. At the same time, the metal debris falling after impact will also accelerate the wear of the flanks, making the gear transmission uneven and making noise.
4, gear processing error is easy to cause noise: the main reason for noise caused by gear processing error is the gap accumulation error and profile error. The uneven thickness of the teeth is caused by the non-fit of the blank swing shaft when the teeth are made and the swing shaft when the gears are working. The profile error of the roller is mainly due to the error in manufacture, blade grinding and installation of the roller, resulting in the tooth prism, profile asymmetry, root cutting and subsequent processing correction, resulting in uneven transmission. Pulsation, root cutting, and teething are produced, resulting in noise.
5, the noise is caused by the inner ring gear and planetary frame processing error: the radial run-out error of the inner ring gear has a great influence on the floating amount of floating parts. Therefore, the radial run-out of the inner ring gear should be strictly controlled. Damage to the inner ring gear due to improper selection of the machining and heat treatment process. In the heat treatment process, the change of the parameters such as profile, lead orientation and pitch is also one of the important reasons for noise. In the process of processing the planetary wheel frame, the position deviation of the planetary axle directly affects the side gap of the gear sub. The necessary side gaps are important for the normal operation, lubrication, thermal expansion and cold contraction of the gearbox without blocking, but the side gaps pass through the assembly and produce shocks and noise during positive and reverse conversions.
6, heavy-duty gear transmission, flank elastic variant caused noise: heavy-duty gear, especially hard-flank gear, elastic deformation, running performance is very poor, gear by load deformation caused by meshing impact, resulting in noise.
7, assembly error caused by noise: the geometry accuracy of assembly did not meet the design requirements. Noise caused by vibration of the drive system, or by loose individual parts during assembly. This caused the system to be incorrectly located. Engage in an abnormal position. The motion of the shaft system produces vibration and noise.
8, improper maintenance of the whole machine caused noise: gear meshing, resulting in flank wear. In the long-term use of the process, if lubrication, cooling is not sufficient, poor oil cleaning, will accelerate wear. In severe wear, the accuracy of the gears decreases. The opportunity to decelerate increases noise.
Ways to reduce planetary gearbox noise:
First, to choose a high vibration rate of materials: light load, slow rotation of gears, the use of plastic gear is a good choice, but pay attention to the problem of temperature rise.
Second, casting gears have a significant noise reduction effect than steel gears. Proper lubrication: Should be fully lubricated, so that high viscosity oil noise is small.
Third, low-speed operation and low load: try to maintain decompression, load minimization, to reduce noise.
Select a gear with high accuracy: the pitch error, profile error, tooth groove error, tooth rib error is reduced, and the noise is smaller. While improving the gear and the accuracy of each gear, the coarseness of the gear can be improved by grinding the teeth on the flanks. Therefore, it has a good effect on reducing noise. 5. The flanks use smooth: research, friction, grinding can achieve a very ideal flank weight, in addition to warm-up refueling operation for a period of time can also improve the flank weight, which has a certain reduction in noise. 6. Correct flank contact: the implementation of flank drum processing or cutting end face machining, to avoid single-piece contact, natural noise is low. Reasonable profile adjustments can also help reduce noise. Remove scratches or scratches from the flanks. 7. Suitable tooth gap: the load is generally more balanced, the tooth gap is slightly larger can also effectively reduce noise.

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