3D Tooth Profile in Strain Wave Gearing to Prevent Interference
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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 limitations in tooth cutting processes, where tooth profiles with varying thickness, pressure angle, and depth along the tooth trace direction are hard to cut, leading to interference issues.
Innovation Solution
The solution involves forming three-dimensional tooth profiles for both internal and external teeth, where the internal teeth have a basic profile at the outer end and a proportionally reduced profile at other positions, and the external teeth have a basic profile at the outer end and a proportionally increased profile along the tooth trace direction, ensuring easy cutting and preventing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a three-dimensional tooth profile with varying thickness, pressure angle, and depth along the tooth trace direction is employed to achieve three-dimensional meshing, then the meshing state is improved, but the tooth cutting process becomes difficult
Solution Approach 1:
The patent applies local quality by making different parts of the tooth profile have different properties. The tooth profile includes varying thickness, pressure angle, and depth at different positions along the tooth trace direction, allowing each local region to be optimized for its specific meshing requirements while remaining manufacturable
Solution Approach 2:
The patent transitions from traditional two-dimensional tooth profiles to three-dimensional tooth profiles by adding variation along the tooth trace direction. This dimensional enhancement enables three-dimensional meshing where external teeth mesh with internal teeth across multiple axially perpendicular cross-sections simultaneously, improving the meshing state
2Reliability
If the external teeth are formed with a three-dimensional profile to achieve continuous meshing at multiple positions, then the meshing continuity is improved, but the complexity of tooth formation increases
Solution Approach 1:
The external teeth are designed with locally varying properties along the tooth trace direction, including different thicknesses, pressure angles, and depths at different positions. This allows the tooth profile to adapt to the flexing state at each location, ensuring continuous meshing across multiple cross-sections while maintaining manufacturability
Solution Approach 2:
The three-dimensional tooth profile design accounts for the dynamic flexing state of the externally toothed gear. The varying tooth parameters along the tooth trace direction enable the teeth to maintain proper meshing engagement during the elastic deformation cycle, ensuring meshing continuity as the gear flexes in and out
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 allows for seamless three-dimensional meshing across the entire tooth trace direction without interference, simplifying the tooth cutting process and enhancing the operational efficiency of the strain wave gearing.
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. The tooth tip circle of an internal-teeth inner-end-side portion of the internal teeth is larger than that of other portions and does not interfere with the external teeth. The external teeth and the internal teeth mesh three-dimensionally, the teeth do not interfere at the internal-teeth inner-end side.