Noise is an important performance index of the product quality for planetary reducer. We must study from the aspects of design, maintenance and installation of planetary reducer to analyze the source of noise.
1. The parameters and structure of the gear of the planetary reducer will affect the noise. When a pair of gears are in transmission, the greater their overlap, the lower the noise; and of course, the smaller the overlap, the higher the noise. It means that the number of tooth pairs participating in the meshing at the same time increases, which is of great significance for improving the smoothness of gear transmission, reducing noise and improving load-carrying capacity.
2. The precision of gear is an important indicator of noise level. For the standard series planetary reducer, the manufacturing accuracy of the gear determines its noise value. The higher the gear accuracy, the denser the contact spots on the meshing tooth surface; there are contact spots on the entire tooth surface, noise will be less. On the contrary, the lower the gear accuracy, the smaller the contact spots on the meshing tooth surface, and the gear cannot be completely meshed in its contact width, the operation will be unstable, and even cause impact, which will increase the noise value.
3. Impact and noise caused by pitting on the tooth surface. After the transmission gear is loaded and operated for a period of time, small pieces of metal often fall off near the pitch line of the tooth surface forming pitting corrosion. Because the hard tooth surface gear has the advantages of large bearing capacity, small volume, light weight, and good transmission quality, it is widely used in many fields. Although hard-faced gears are not prone to pitting, it is not easy to run-in once pitting occurs, which will damage the tooth profiles and increase the working noise and impact. The metal chips dropped by the impact accelerate the wear of the tooth surface, which makes the gear transmission unstable and generates noise.
4. Gear machining errors can easily cause noise. The noise caused by errors in gear processing is mainly caused by the cumulative error of the tooth pitch and the error of the tooth profile. The cumulative error of the tooth pitch is due to the uneven gear tooth thickness due to the non-coincidence of the rotation axis of the tooth blank and the rotation axis of the gear during gear production. Tooth profile error is mainly caused by errors in the manufacturing, sharpening and installation of the hob, which cause the tooth surface to be edged, tooth profile asymmetry, undercut and subsequent processing are not fully corrected, which makes the gear transmission unstable. The pulsation, undercutting and tooth punching occurs and then noise is generated.
5. The machining error of the inner gear ring and planet carrier causes noise. The radial run-out error of the inner ring gear has a great influence on the floating amount of the floating parts, so the radial run-out of the inner ring gear should be strictly controlled. Due to the improper selection of processing and heat treatment processes for the inner gear ring, changes in parameters such as tooth profile, tooth direction and pitch after heat treatment are also important reasons for noise. The position deviation of the planetary wheel shaft during the processing of the planetary carrier directly affects the backlash of the gear pair. The necessary backlash is very important to ensure the normal operation, lubrication, thermal expansion and contraction of the reducer without blocking. But if the backlash is too large, when the reverse direction is changed an impact is generated then noise occurs.
6. The elastic deformation of the tooth surface of the heavy-duty gear drive causes noise. Heavy-duty gears, especially hard-toothed gears, have large elastic deformations and extremely poor running-in performance. Noise is generated by the impact of gears under load.
7. Assembly errors cause noise. The geometric accuracy during assembly doesn’t meet the design requirements, resulting in vibration and noise in the transmission system. Or, due to the loosening individual parts during assembly, the system is not positioned correctly, meshed in abnormal position, and the shaft system moves then vibration and noise generate.
8. Improper maintenance of the whole machine causes noise. The tooth surface is worn when the gear is meshed. During the long-term use of the reducer, the insufficient lubrication and cooling and the poorly clean lubricating oil will accelerate wear. The gear accuracy will be damaged, and the noise become louder when the wear is severe.