Geometric contact pattern estimation for gear drives

This paper presents a novel approach to estimate the contact pattern for gear drives. The proposed method is based on the geometric properties of the generated surfaces of the pinion and the gear and it neglects the mechanical characteristics of the mating members. The key feature of the method is the superimposition of a virtual marking compound over the gear surface that mimics the industrial practice of contact pattern inspection. For each meshing condition the instantaneous contact area is estimated as the intersection of the pinion surface with the marking compound gear surface. Finally, the contact pattern is estimated by the convex envelope of all the instantaneous contact areas in the zr-plane. The marking compound shape is identified through an optimization process to match a target contact pattern obtained, e.g. with an accurate loaded tooth contact analysis tool. oposed method has been tested with a dedicated FEM software package capable of producing a very accurate contact pattern estimation of the contact pattern under load. Extensive simulations have shown that, once the optimal marking compound shape has been identified, the proposed method computes a reliable contact pattern even for very different surface geometries (e.g. an ease-off on the pinion surface) and assembly errors. The computational cost of the entire procedure is about two orders of magnitude lower than that required to run the full FEM analysis.