MESHING CONTROL OF CYCLOID GEAR WITH HIGH PRECISION IN MECHANICAL MOVEMENT

摘要

Watch is a precise machine with long history, in which gear train is one of the most important mechanisms and plays a vital role in timekeeping. The research focuses on gear sets in watch main train, the requirement of which is the transmitted torque should be stable and the transmission should not be sensitive to misalignment errors. As we all know, the misalignment errors are inevitable in practical condition, the influence of which is obvious due to the module of gear in main train is small. All possible misalignment errors in gear pair are categorized and analyzed. By means of Loaded Tooth Contact Analysis (LTCA), the effects of misalignment errors on the contact zone are illustrated. Meanwhile the algorithm for computing transmitted torque of gear sets in main train is presented. Aiming at reducing the influence of misalignment errors on the contact zone and achieving the precision transmission, combined wheel tooth modification strategy is put forward. Analysis results show that with longitudinal modification gear pair could be in better contact pattern than that without modification when the misalignment errors exist. At the same time wheel tooth profile modification will reduce the fluctuation of the torque transmission in the gear pair. Thus the meshing control of gear sets in the watch main train could be achieved prior to the actual manufacturing process.