Gear tooth smoothing and shaping process
AssigneeGeneral Motors Corporation
InventorsLeonid Charles Lev, Anita Miriam Weiner, Stephen Joel Harris
Life of this patent
Estimating the term…
Abstract
The fatigue life of gears, for example, the gears in a sun gear-planetary gear set, is markedly improved by forming the respective gears by ordinary manufacturing practices and then running each new gear against a durable, but expendable, dummy of its counter-gear. The teeth of a dummy sun gear may be suitably hardened and used under suitable loads to minimally reshape the teeth of a plurality of newly-made pinions so that they are smoothed and better fit an intended sun gear. Similarly, the roughened teeth of a hardened or hard coated sun gear can be smoothed by running it for a few rotations against an expendable pinion.
Claims6
A method of making a gear wheel intended to operate under a power transmitting load in rolling contact against a complementary counter-gear, said gear wheel having evenly spaced teeth formed on a round surface of the gear wheel for said rolling contact, said method comprising
- forming said gear wheel to an initial shape for assembly in a power transmission device with at least one said counter-gear,
- rolling said gear wheel under a power transmitting load against an expendable said counter-gear for a period of time sufficient to alter said initial shape of said gear wheel teeth to improve their rolling contact with a said counter-gear, and thereafter
- assembling the altered gear wheel in a said transmission device with a said counter-gear other than said expendable gear.
A method of making a sun gear intended to operate in rolling contact against a complementary planetary pinion gear, said sun gear having evenly spaced teeth formed on a round surface for said rolling contact with teeth of a said pinion gear, said method comprising
- forming said sun gear to an initial shape for assembly in a power transmission device for rolling contact against a plurality of pinion gears,
- forming a coating, one to four micrometers thick, on the teeth of said sun gear, said coating having a hardness greater than the hardness of the teeth of said pinion gears, said coating being characterized by abrasive asperities,
- rolling said coated sun gear under a power transmitting load against one or more expendable pinion gears for a period of time sufficient to smoothen said asperities, and thereafter
- assembling the smoothened sun gear in a said transmission device with said pinion gears other than said expendable gears.
A method of making a planetary pinion gear intended to operate in rolling contact against a complementary sun gear, said pinion gear having evenly-spaced teeth formed on a round surface for said rolling contact with teeth of a said sun gear, said method comprising
- forming said pinion gear to an initial shape for assembly in a power transmission device for rolling contact against a sun gear,
- rolling a group of said pinion gears under a power transmitting load against an expendable said sun gear with surface hardened teeth for a period of time sufficient to alter the initial shape of the teeth of said pinion gears to improve their rolling contact with the teeth of an operating said sun gear, and thereafter
- assembling the altered pinion gears in a said transmission device with a said sun gear other than said expendable gear.
Dependencies are inferred from the claim text.