Multi-objective optimized design for modified cycloid-pin gear drive mechanism based on load-bearing capacity

Rotate vector (RV) reducers are typical deceleration elements that moderate and increase torsion. They are widely applied in industrial robots and automatic machinery with the superiorities of compact structure, high precision, and overload resistance performance. However, the RV reducers also have disadvantages, such as low bearing capacity and short service life. As the core drive mechanism in an RV reducer, the bearing capacity for a cycloid-pin gear drive system directly affects the performance of the entire deceleration system. Therefore, the bearing capacity of an RV reducer should be improved by increasing the capacity of a cycloid-pin gear. In this paper, the design of a cycloid-pin gear is optimized to improve its bearing capacity. The tooth profile equations for cycloid gear and the meshing gap are derived based on the gear meshing principle. The bearing capacity for cycloid-pin gear is modeled by combining the contact strength theory with the multi-tooth contact bearing analysis. The effects of eccentricity, the radius of pin tooth distribution circle, pin teeth number, pin tooth radius, cycloid thickness, modification value of moved distance and equidistance on total volume, contact stress, and torsional stiffness are systematically researched. Then, a single-, double-, and three-objective optimization model is proposed based on the load-bearing capacity for cycloid-pin gear by taking these three factors as the objective function. Moreover, the parameters are optimized with the genetic algorithm, and the analyses for three optimizations are compared and discussed. The theoretical models are confirmed by the simulation analysis through ANSYS software. The results show that the bearing capacity for the cycloid-pin gear system can be largely enhanced after optimization.