Wave Generator Tapered Plug Roller Bearing Contact
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional wave generators with roller or ball bearings fail to accurately follow the three-dimensional flexing of cup-shaped or silk-hat-shaped externally toothed gears in strain wave gearing, leading to contact deviations, increased friction, and reduced positioning accuracy and lifetime.
Innovation Solution
A wave generator with a roller bearing is designed to have an elliptical outer peripheral surface with opposing tapered surfaces to match the corning shape of the externally toothed gear, allowing the rollers to contact the inner surface without partial contact, thereby reducing wear and maintaining transmission accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a roller bearing is employed in a wave generator for cup-shaped or silk-hat-shaped externally toothed gear, then the wave generator structure is simplified and ease of manufacture is improved, but the outer peripheral part cannot follow the corning shape of the external-tooth forming portion, causing contact deviation and deterioration of transmission accuracy
Solution Approach 1:
The wave generator employs different bearing types at different locations: roller bearings are used at the major axis position where the externally toothed gear does not contact, while ball bearings are used at the minor axis position where contact occurs. This local differentiation allows the wave generator to maintain manufacturing simplicity while achieving accurate contact following at critical positions
Solution Approach 2:
The wave generator is designed with dynamic adaptability to follow the corning shape of the externally toothed gear during operation. The combination of roller and ball bearings allows the outer peripheral part to dynamically adjust and maintain proper contact alignment as the gear flexes into elliptical shape
2Device complexity
If a roller bearing is employed in a wave generator, then device complexity is reduced, but frictional wear increases and lifetime decreases due to strong contact deviation
Solution Approach 1:
Roller bearings are selectively applied only at positions where they do not cause contact deviation (major axis position), while ball bearings are used at positions where contact occurs (minor axis position). This local optimization reduces overall device complexity while preventing wear and extending lifetime at critical contact points
Solution Approach 2:
The design accepts that roller bearings cannot follow the corning shape at all positions, but converts this potential harm into benefit by strategically placing roller bearings only where they won't cause contact deviation, thereby enjoying their manufacturing simplicity and lower complexity without suffering their harmful effects on lifetime
Data Source
Figure 1(a)~1(b)
Figure 2(a)~2(c)
Figure 3(a)~3(e)
AI summary
A wave generator (4) of a strain wave gearing has a rigid plug (42) provided with an elliptical outer peripheral surface (41), and a roller bearing (43). The outer peripheral surface (41) of the plug (42) is provided with a major-axis-side outer-peripheral surface portion (41a) formed at a major axis position L1, and a minor-axis-side outer-peripheral surface portion (41b) formed at a minor axis position L2. The major-axis-side outer-peripheral surface portion (41a) is a tapered surface that is tapered along a center axis line (42a), and the minor-axis-side outer-peripheral surface portion (41b) is an inverted tapered surface that is tapered in the opposite direction. An externally toothed gear can be supported and flexed into an elliptical shape without partial contact by using the wave generator in which the roller bearing is used.