Hypoid Gear Hard Hobbing After Heat Treatment
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Solution Overview
Problem
The manufacturing of hypoid gears is costly and environmentally impactful due to expensive grinding and lapping processes, which also require matched sets of gears for replacement, increasing inventory and repair costs.
Innovation Solution
A method involving face hobbing to form a green hypoid gear, heat treating to create a hard black gear, and hard hobbing to finish the gear teeth, which can include carburizing or induction hardening, shot peening, and using a twin-blade cutting tool design to remove material uniformly across the gear teeth, allowing for independent formation of hypoid ring and pinion gears without the need for matching sets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If grinding and lapping processes are used for hard finishing, then manufacturing precision and surface finish are improved, but manufacturing cost and environmental impact increase
Solution Approach 1:
The patent replaces the traditional mechanical grinding and lapping processes with a hard hobbing process that uses a hardened cutting tool to machine the heat-treated gear blank. This substitution eliminates the need for expensive grinding and lapping operations while achieving the required surface finish and dimensional accuracy, directly resolving the contradiction between manufacturing precision and manufacturing cost.
2Manufacturing precision
If lapping process is used to produce matched sets of hypoid gears, then gear meshing accuracy is improved, but inventory costs and repair costs increase
Solution Approach 1:
The patent applies segmentation by treating each gear (ring gear and pinion gear) as an independent component that can be manufactured separately through hard hobbing. Each gear is hardened and finished independently, allowing them to be produced as individual units rather than as matched sets. This enables separate replacement of gears when needed, reducing inventory costs while maintaining gear meshing accuracy through the precision of the hard hobbing process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method reduces costs and environmental impact by providing hard finished hypoid gears that meet accuracy standards, eliminates the need for matched sets, and minimizes heat distortion, while enhancing wear resistance and fatigue resistance through surface hardening and peening.
Implementation Method 1
the heat treating includes carburizing and/or induction hardening the green hypoid gear
Implementation Method 2
the heat treating includes carburizing and/or induction hardening the green hypoid gear
Implementation Method 3
the black hypoid gear is shot peened prior to or after hard hobbing the black gear teeth
Data Source
AI summary
A method of manufacturing a hypoid gear includes face hobbing a gear blank and forming a green hypoid gear with gear teeth, heat treating the green hypoid gear to form a heat treated hypoid gear with heat treated gear teeth, and hard hobbing the heat treated gear teeth to form a hard finished hypoid gear. Critical non-tooth features on the heat treated hypoid gear are hard finished. Also, the critical non-tooth features on the heat treated hypoid gear can be hard finished prior to hard hobbing the heat treated gear teeth. The heat treating includes at least one of carburizing and induction hardening the green hypoid gear, a surface of the heat treated gear teeth has a hardness greater than or equal to 58 HRC, and the hard hobbing removes heat distortion from the heat treated gear teeth.