Manufacturing helical gears with double-crowning and twist-free tooth flanks using a variable pressure angle shaving cutter

For a parallel gear shaving process, the tooth flanks of a shaved work gear surface are longitudinally crowned using an auxiliary crowning mechanism. However, the flanks are only crowned in the longitudinal direction and not in the cross-profile direction so there is a natural twist on the shaved work gear surfaces. A new shaving method for double-crowning that has no natural twist in the tooth flanks on the work gear surfaces is proposed, which uses a variable pressure angle shaving cutter in a parallel gear shaving process. Three numerical examples are presented to verify the merits of the proposed shaving method. The tooth flanks are crowned in both the cross-profile and the longitudinal directions, and natural twists in the shaved tooth flanks are reduced significantly.