A study on hourglass-worm gearings designed to concentrate surface normals. A gear disign using an hourglass-worm gearing with an arcuate tooth profile.

Abstract

In order to avoid the influence of the displacement of gear axes under load upon tooth contact, the authors propose that a projective group of the surface normals should be concentrated upon the intersection point of the plane perpendicular to the wheel axis and the axis about which the worm axis rotates, displacing its position relative to the wheel. This idea was applied to the gear design using an hourglass-worm gearing with an arcuate tooth profile. A numerical analysis indicated that as much as 70∼80 % of the theoretical area of the utilized gear contributed to meshing at their estimated displacement positions.