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Reduction gear modification and MASTA simulation

Release time:

2021-04-29

1. Profile modification of reduction gear

The elastic mechanics of materials makes the gear set meshing, the main and passive gears can be simplified to a cantilever beam model rotating around the axis line, which will produce bending deformation under load, and there is elastic deformation in the contact area of the tooth surface. In addition, the objective influence of various errors such as gear manufacturing error, shell processing error, assembly, etc., causes the actual meshing point of the gear to deviate from the theoretical meshing area, resulting in meshing impact excitation. In order to reduce the error of gear meshing, the NVH of the gear should be simulated and predicted at the early stage of design. Tooth profile modification is an effective method to optimize the contact position and stress size of gears, micro-modification can be aimed at a pair of meshing gears, or only single gear modification optimization, in engineering practice is usually more to take a single gear modification, which has higher production efficiency and lower production costs.

Usually the key influencing factors of profile modification are profile modification, width, tooth root and tooth top modification, in which the determination of tooth root modification parameters needs to take into account the selection of modification parameters while considering the safety factor of the tooth shaft, so as to avoid the reduction of the bending strength of the gear tooth root caused by excessive root modification. The regular forms of tooth profile modification are shown, including left and right end straight line modification, spiral modification and drum modification. The selection of the specific profile modification scheme needs to consider the size of the input load excitation, the stiffness of the transmission path and the ease of processing, and combine the NVH simulation tool to optimize the profile modification scheme.

2. The direction of the reduction gear is modified

Under the condition of bearing load, the gear shaft material produces the corresponding deformation around the axis of rotation, and the objective existence of gear processing error and reducer assembly error, which produces the deviation of the tooth upward and the theoretical meshing area. By optimizing the modification of the tooth direction, the contact position and size of the tooth surface can be reasonably distributed. Generally, there are two forms of tooth direction modification: straight line modification and drum modification.

Comprehensive engineering development experience, gear design optimization micro-modification should achieve the following objectives:

(1) It is preferable to contact at the center of the tooth surface, make full use of the tooth width, and avoid the load on the edge and the tooth top;

(2) The speed of the input stage gear of the electric vehicle (EV) reducer is very high, and its peak-to-peak TE value should be less than 2μm;

(3) smaller larger contact stress and tooth surface load distribution coefficient;

(4) transmission error and tooth surface contact stress as the basis for modification design and adjustment.

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