Novel variable-tooth-thickness hob for longitudinal crowning in the gear-hobbing process

In the gear-hobbing process, the work gear tooth flank is usually longitudinally crowned by varying the center distance between the hob and the work gear. Without crossed angle compensation, however, this center distance variation produces a twisted tooth flank on the workgear. This paper therefore proposes a methodology to reduce this tooth flank twist in longitudinal crowning by modifying the hob tooth thickness and hob tangential feed without varying the center distance.

► The longitudinal crowning is usually caused a twisted tooth flank on a hobbed gear.
► This paper proposes a methodology to reduce the tooth flank twist on the gear.
► The methodology is using a variable tooth thickness (VVT) hob in gear hobbing.
► Besides, the VVT hob should be shifted diagonally in the hobbing process.
► This methodology will reduce the tooth flank twist on the gear effectively.