Influence of manufacturing error tolerances on contact pressure in gears

Abstract

Gear manufacturing always results in some degree of manufacturing errors, i.e. deviations from the desired gear geometry. These errors alter how the gears mesh, typically causing increased contact pressure which in turn shortens service life. It is therefore crucial to choose tolerances such that excessive contact pressure, and especially tip contact, is avoided. With increasing demands due to electrification, this becomes even more important. The aim of this paper is to study how pitch error and profile slope error affect the contact pressure in spur gears sets. The meshing is simulated using a novel simulation approach that uses a parametric description of the reference profile and gear geometry, and a hybrid model for the compliance. The method includes tooth modifications such as tip relief, and uses the true geometry to find contacts. Thus, it also handles contact outside the nominal line of action, including tip contact. The study includes cases where a gear is subjected to both pitch error and profile slope error simultaneously. Numerical examples, relevant to the automotive industry, show the outcome of the simulations. It is shown how simulation-based tolerances for relevant industrial applications can be used to improve manufacturing outcome.

Reducing scrapping of gears by assessment of tip contact threshold torque

“…Contact pressure for gear sets with manufacturing errors has also been treated by several authors. Hjelm et al 13 performed a loaded tooth contact analysis, LTCA, of gear sets subjected to pitch error and profile slope error using a parametric model hybrid compliance. The finite element method was used by Wei 14 for gear sets with pitch error as well as profile and helix slope and form error, and by Luo 15 for cases of helix slope and form error.…”