Apparatus and method for precision gear finishing by controlled deformation
AssigneeThe Penn State Research Foundation
InventorsMaurice F. Amateau, Nagesh Sonti
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Abstract
An apparatus and method are provided for the thermomechanical net shape finishing of precision gear tooth surfaces by controlled deformation into metastable austenitic condition. To this end, an arrangement of a fixed axis through-feed motion of workpiece and moving axes in-feed motion of two opposed rolling dies are utilized. By means of process control methods and architecture for accomplishing precision mechanical motions, thermal and environmental control and timely and automatic transfer of workpiece, high strength and high accuracy gear tooth contact surfaces are produced.
Claims11
A method of shaping gear teeth of a high performance gear comprising the steps of:
- (a) providing an inert atmosphere during the performance of all subsequent steps;
- (b) heating a workpiece in the form of a near net shaped gear blank having carburized gear teeth surfaces above its critical temperature to obtain an austenitic structure throughout its carburized surfaces;
- (c) isothermally quenching the gear blank at a rate greater than the critical cooling rate of its carburized surfaces to a uniform metastable austenitic temperature just above the martensitic transformation temperature;
- (d) holding the temperature of the gear blank at said uniform temperature while rolling the gear teeth surfaces between a pair of diametrically opposed rolling gear dies to a desired shape before martensitic transformation occurs;
- and
- (e) cooling the gear through the martensitic range for the carburized gear surfaces to harden the gear surfaces.
A method of net shaping gear teeth of a high performance gear comprising the steps of:
- (a) rotatably supporting on its axis a workpiece in the form of a near net shaped gear blank having carburized gear teeth surfaces;
- (b) while rotating the workpiece, heating it within an inert atmosphere above its critical temperature in toroidal shaped induction heater means for a sufficient time to obtain an austenitic structure throughout its carburized surfaces;
- (c) rapidly stopping rotation of the workpiece;
- (d) rapidly withdrawing the workpiece from the induction heater after said sufficient time and, in a continuing movement, rapidly quenching the workpiece at a rate greater than the critical cooling rate of its carburized surfaces to a uniform metastable austenitic temperature just above the martensitic transformation temperature;
- (e) holding the temperature of the workpiece at said uniform temperature while rolling the gear teeth surfaces between a pair of diametrically opposed rolling gear dies to a desired shape before martensitic transformation occurs;
- and
- (f) cooling the gear through the martensitic range for the carburized gear surfaces to harden the gear surfaces.
Dependencies are inferred from the claim text.