The manufacturing error of cycloid gear is the key factor affecting the transmission precision and meshing characteristics of cycloidal-pin gear in RV reducer. Taking the RV cycloidal-pin gear pair transmission as the object, a meshing contact analysis method is proposed for RV cycloidal-pin gear transmission considering the influence of manufacturing error. The modified tooth profile of cycloid gear is effectively superimposed and transformed by taking the influence of tooth profile and pitch errors of cycloidal gear into consideration, and the theoretical contact analysis model of cycloidal-pin gear transmission is established. By analyzing and solving the meshing contact model, the characteristic parameters such as the meshing point position, meshing backlash and transmission error of cycloidal-pin gear between the meshing contact surfaces are obtained under the influence of manufacturing error, and the effective pre-control of the tooth profile and the meshing contact performance is realized. The verification analysis results show that the manufacturing error has a great influence on the transmission accuracy of RV cycloidal-pin gear, among which the tooth pitch error has the greatest influence on the transmission error, which is in a positive proportion. And the influence of tooth profile error on transmission error is second. The meshing contact analysis method considers the interactive influence of the manufacturing error and modification shape of tooth profile on the meshing contact status of RV transmission; the cycloidal tooth profile can be obtained which is more suitable for engineering practice. This analysis method can provide the theoretical support and technical means for profile modification design, motion accuracy improvement and load-bearing contact analysis of RV transmission.

The tooth profile modification of cycloidal gears is important in the design and manufacture of precision reducers or rotary vector (RV) reducers for robots. The traditional modification design of cycloidal gears is mainly realized by setting various machining parameters, such as the size and center position of the grinding wheel. The traditional modification design has some disadvantages such as complex modification calculation, uncontrollable tooth profile curve shape and unstable meshing performance. Therefore, a new tooth profile modification method is proposed based on the consideration of the comprehensive influences of pressure angle distribution, meshing backlash, tooth tip and root clearance. Taking the pressure angle and modifications of tooth profile as the parameters of the modification function and the meshing backlash of gear teeth as constraints, the mathematical model for tooth profile modifications is built. The modifications are superimposed on the normal direction of the theoretical profile—the force transmission direction. The mathematical relationship between the modifications and the pressure angle distribution, which determines the force transmission performance, is established. Taking the straight line method, cycloid method and catenary method as examples, by means of the tooth contact analysis technology, the transmission error and minimum meshing backlash, which reflects the lost motion, of the newly modified profile are analyzed and verified. This proposed method can flexibly control the shape change of the modification profile and accurately pre-control the transmission accuracy of the cycloid-pin gear. It avoids the disadvantages of traditional modification methods, such as uncontrollable tooth profile shape and unstable meshing accuracy. The method allows good meshing characteristics, high force transmission performance and more precise tooth profile curve. The study provides a new design method of the modified profile of cycloidal gears.

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