Rollable enveloped worm with two curve profile

摘要

A drive gear engages a driven gear with non-intersecting axes of rotation making an angle of approximately 90° with respect to one another. A shaft has a first portion with a predetermined diameter, and a second portion has an enveloped worm gear with at least one roll-formed helical tooth formed thereon with an outer diameter greater than the diameter of the first portion of the shaft. The extra envelopment achieves an overall smaller package size for competitive advantage. When the shaft is rolled, the outside teeth exceed the shaft diameter by a predetermined amount allowing more teeth to be in contact with the driven gear. An outer bearing can be placed at the end of the shaft to allow the teeth to be of a larger diameter than the shaft. The pitch of the teeth can vary. Preferably, the bearing groove is roll formed simultaneously with the teeth of the worm gear since the centroid of the enveloped teeth must be located with the gear center line.