Influence mechanism of tooth surface forming methods on the tooth profile and contact performance of crown gear coupling

Crown gear couplings are primarily manufactured using two tooth surface forming methods. In Forming Method Ⅰ, the hob centre makes circular motion around the displacement circle center, while in Forming Method Ⅱ, the gear shaper centre follows the same motion. However, the differences in tooth profiles and the mechanisms influencing their contact performance between these two methods remain unclear. To address this, simulations of the tooth surface machining processes for both forming methods were conducted, and the resulting hub tooth surfaces were modeled. Geometric tooth contact analysis and loaded tooth contact analysis models were established using meshing theory and the finite element method. Comparative analyses of tooth profiles, unloaded, and loaded contact characteristics were performed. Results show that, under identical displacement circle radii, the tooth profile deviations between the two forming methods gradually decreases as the radius increases, with a maximum deviation of 251 μm. Moreover, load sharing among teeth is notably less uniform in Forming Method Ⅰ than in Forming Method Ⅱ, with maximum loads exceeding minimum loads by 702.8% and 451.2%, respectively. For equal crowning amounts, Forming Method Ⅱ requires a larger displacement circle radius than Method Ⅰ, with a difference of 200 mm. Despite this, the load-sharing performance of both methods becomes comparable under these conditions.