1. Influence of Gear Errors in the Gearbox
Gear form errors, base pitch deviations, tooth alignment errors, and radial runout errors of the gear ring during the gear manufacturing process are the main errors that cause noise in planetary gearboxes. They also affect the efficiency of the gearbox. Let's briefly discuss gear form errors and tooth alignment errors.Gears with small gear form errors and low surface roughness have noise levels 10 dB lower than ordinary gears under the same test conditions. Gears with small tooth pitch errors have noise levels 6-12 dB lower than ordinary gears under the same test conditions.
However, if there is tooth pitch error, the impact of the load on gear noise will be reduced.Tooth alignment errors result in the transmission of power not being fully transmitted across the entire tooth width. This leads to increased noise levels due to increased local stress and gear deflection at the contacting tooth surfaces. However, under high loads, tooth deformation can partially compensate for tooth alignment errors.
2. Assembly Concentricity and Dynamic Balancing
Non-concentric assembly leads to imbalance in the shaft system, and the loose-tight meshing of the gear teeth contributes to increased noise. The lack of balance during assembly of high-precision gear transmissions significantly affects the accuracy of the transmission system.
3. Gear Surface Hardness in the Gearbox
With the development of gear hardening technology, gears with hard tooth surfaces have been widely used due to their high load-carrying capacity, compact size, light weight, and high transmission accuracy.However, the deformation of gears caused by carburizing and quenching to achieve hard tooth surfaces leads to increased gear transmission noise and reduced lifespan. To reduce noise, precision machining of the gear surface is necessary.
Currently, in addition to traditional gear grinding methods, a hard gear shaving method has been developed. This method reduces gear meshing impact by modifying the tooth top and tooth root or reducing the tooth profiles of both the driving and driven gears, thereby reducing gear transmission noise.
4. Verification of Gearbox System Specifications
The accuracy of component processing and the selection method for components (complete interchangeability, grouping selection, individual selection, etc.) before assembly will affect the accuracy level of the system after assembly, including the noise level. Therefore, verifying (or calibrating) various system indicators after assembly is crucial for controlling system noise.