Flexible External Gear Surface Finishing for Longer Robot Drive Life
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Solution Overview
Problem
Existing gear devices for robots, such as those used in robot arms, do not adequately extend the life of the flexible external gear due to lack of machining and treatment on the inner surface, which affects the overall performance and longevity.
Innovation Solution
A gear device configuration that includes an internal gear, a flexible external gear with a cylindrical section, and a wave generator that moves the meshing position of the internal and external gears, where the inner circumferential surface of the external gear features a polished surface at one end and a lathe-cut surface at the other, enhancing flexibility and deformation resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If no machining or treatment is applied to the inner surface of the flexible external gear, then manufacturing complexity is reduced, but the life of the gear device is insufficient due to fatigue fractures
Solution Approach 1:
The patent applies different surface treatments to different regions of the inner circumferential surface. The first end portion (where the wave generator contacts) receives polishing to reduce fatigue fractures, while the second end portion maintains lathe-cut surface characteristics. This localized differentiation extends gear device life without unnecessarily complicating the entire manufacturing process.
2Reliability
If the entire inner circumferential surface is polished, then fatigue resistance is improved, but manufacturing time and cost increase
Solution Approach 1:
The patent selectively polishes only the first end portion of the inner circumferential surface where the wave generator makes contact, rather than polishing the entire surface. This localized approach improves fatigue resistance at the critical contact area while reducing overall manufacturing time and cost compared to full-surface polishing.
Solution Approach 2:
The patent applies polishing action only to the extent necessary - specifically the first end portion that contacts the wave generator - rather than applying it to the entire inner circumferential surface. This partial action achieves sufficient fatigue resistance where needed without the excessive time and cost of complete surface treatment.
Data Source
AI summary
A gear device includes an internal gear, an external gear having flexibility configured to partially mesh with the internal gear and rotate around a rotation axis relatively to the internal gear, and a wave generator configured to come into contact with an inner circumferential surface of the external gear and move a meshing position of the internal gear and the external gear in a circumferential direction around the rotation axis. The external gear includes a cylindrical section including a first end portion with which the wave generator is in contact and a second end portion adjacent to the first end portion along the rotation axis. An inner circumferential surface of the first end portion includes a polished surface. An inner circumferential surface of the second end portion includes a lathe-cut surface.