Strain Wave Gearing 3D Tooth Profiles for Easier Tooth Cutting
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Solution Overview
Problem
Existing cup-shaped or top-hat-shaped strain wave gearing technologies face difficulties in achieving three-dimensional meshing due to restrictions in tooth cutting processes, particularly in forming tooth profiles with varying tooth thickness, pressure angle, and tooth depth along the tooth trace direction.
Innovation Solution
Both the internal and external teeth of the strain wave gearing are set with three-dimensional tooth profiles, where the internal teeth are proportionally reduced and external teeth are proportionally increased in thickness along the tooth trace direction, allowing for easier tooth cutting and achieving three-dimensional meshing across the entire tooth trace direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a three-dimensional tooth profile with varying tooth thickness, pressure angle, and tooth depth is used to achieve three-dimensional meshing, then the meshing capability is improved, but the difficulty of tooth cutting process increases
Solution Approach 1:
The patent applies local quality by making the tooth profile parameters (tooth thickness, pressure angle, tooth depth) vary along the tooth trace direction. Each position along the tooth trace has locally optimized parameters that enable three-dimensional meshing, while the overall gear structure remains manufacturable through systematic variation of these local properties.
Solution Approach 2:
The patent transitions from traditional two-dimensional tooth profiles to three-dimensional tooth profiles by introducing variation along the tooth trace direction. This dimensional extension allows the tooth profile to adapt to the three-dimensional meshing requirements while maintaining compatibility with manufacturing processes through controlled parameter variation.
2Reliability
If the tooth profile varies along the tooth trace direction to prevent interference, then the reliability of meshing is improved, but the manufacturing complexity increases
Solution Approach 1:
The tooth profile is designed with locally varying parameters along the tooth trace direction, where each position has optimized characteristics to prevent interference and ensure reliable meshing. This local optimization approach improves reliability without requiring complete redesign of the entire gear system.
Solution Approach 2:
The tooth profile transitions from static, uniform dimensions to dynamic, position-dependent parameters that vary along the tooth trace. This dynamic variation allows the profile to adapt to changing meshing conditions at different positions, improving reliability while the variation follows systematic patterns that control manufacturing complexity.
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 approach alleviates the limitations of tooth cutting processes, enabling efficient three-dimensional meshing between the internal and external teeth, making it easier to manufacture strain wave gearings with wide-ranging three-dimensional meshing capabilities.
Implementation Method 1
The externally toothed gear is ellipsoidally flexed by the wave generator and meshes with the internally toothed gear at both long-axis-direction end parts of the ellipsoidal shape
Data Source
AI summary
A three-dimensional tooth profile of internal teeth in a strain wave gearing is a basic internal-teeth tooth profile at an internal-teeth outer end, and is a reduced tooth profile, in which the basic internal-teeth tooth profile is proportionally reduced only in the lateral direction, at other tooth-trace-direction positions. A three-dimensional tooth profile of external teeth is a basic external-teeth tooth profile at an external-teeth outer end, and is an increased tooth profile, in which the basic external-teeth tooth profile is proportionally increased only in the lateral direction, at other tooth-trace-direction positions. Tooth cutting process becomes easier than when only the external teeth employ a three-dimensional tooth profile. Since the tooth profiles, which are proportionally reduced and increased only in the lateral direction along the tooth trace direction, are employed, it is further easier in tooth cutting process.