Influence of tooth surface modification on vibration characteristics of high speed helical gear transmission

Vibration and noise reduction of electric vehicle reducer is an important part of vehicle design, and reasonable tooth surface modification design is one of the effective measures widely used in gear transmission system. For this purpose, this chapter uses romax designer The dynamic simulation software is used to modify the tooth surface of two pairs of helical gear transmission of an electric vehicle reducer; the load transmission error of the modified gear is calculated, and then the time-varying meshing stiffness of the modified gear is obtained; the vibration reduction effect of the two-stage helical gear transmission is compared and analyzed by only modifying the input and output helical gears.

Tooth surface modification refers to the process of removing the gear tooth surface material according to the predetermined optimized modification amount, so that the actual tooth surface deviates from the theoretical tooth surface. The process methods generally include shaving and grinding. Generally, there are two kinds of tooth profile modification and tooth profile modification. As shown in Fig. 1 is the schematic diagram of tooth surface modification.

Tooth profile modification (tooth height modification) is a process of micro removal of gear profile material. The tooth profile modification can effectively reduce the meshing impact caused by the manufacturing error of the tooth top and root and the load deformation, and can slow down the change range of the load transmission error; the tooth profile modification is a process of micro trimming the tooth surface along the tooth line direction, mainly including tooth end trimming, spiral angle trimming, drum shaped dressing and surface dressing. The tooth profile modification can effectively improve the uneven distribution of load along the tooth direction, thus increasing the service life of the gear. In practical tooth surface modification design, tooth profile modification and tooth alignment modification are not used alone, but are combined together. In order to consider the cost of gear processing, generally only the small gear is modified, and only a small amount of gear modification is carried out when necessary.

The two most important factors of tooth surface modification are the modification amount and the modification curve. At present, there are many studies on the basic principle of the selection of the amount of modification. When the requirement is not high, the empirical formula can be used to calculate. In the high-precision gear transmission system, the optimization design model can be established and the optimal modification amount can be obtained by using the optimization algorithm such as genetic algorithm. Moreover, the selection of the modification amount is closely related to the specific working conditions such as speed and load The modified curve can only play a good role in vibration and noise reduction under this condition, but not necessarily in another condition. The commonly used modification curves are straight line, quadratic parabola, high-order complex curve, etc., and there are many researches on the optimal tooth surface modification curve under different working conditions.

Only the influence of tooth surface modification on the vibration characteristics of high-speed helical gear transmission is studied. The research focuses on the vibration reduction effect of single-stage high-speed helical gear transmission by tooth surface modification, and the difference of vibration reduction effect of two-stage high-speed helical gear transmission under two different modification conditions, i.e. only modifying the input gear pair and only modifying the output tooth pair. However, there is no specific research on the selection of the optimal modification amount and the optimal modification curve.

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