Torque Tube End Fitting Curvature for Crack Prevention
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Solution Overview
Problem
Torque tubes used for power transmission are prone to cracking during the manufacturing process of end fitting engagement, leading to reduced lifespan and potential failure, which necessitates removal from service.
Innovation Solution
The use of end fittings with smooth outer and inner coupling surfaces featuring virtual cross-sections with transverse inflection points, allowing for electromagnetic forming of the torque tube to conform to these surfaces without sharp edges, reducing stress cracking risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If end fittings with angular ridges are inserted into torque tube ends and the tube ends are conformed over them, then torque transfer between end fittings and tube is achieved, but the tube walls become susceptible to cracking
Solution Approach 1:
The patent replaces angular ridges with smooth, curved coupling surfaces on end fittings. The coupling surfaces feature continuous curvature without sharp edges or corners, allowing the torque tube to be formed over them without stress concentration points that would initiate cracks. This curvature principle directly resolves the contradiction by maintaining torque transfer capability while eliminating crack susceptibility.
Solution Approach 2:
The patent changes the geometric parameters of the coupling surfaces from angular to smooth curved profiles. By modifying the surface geometry to have continuous curvature and eliminating sharp features, the stress distribution during tube formation is improved, preventing crack initiation while maintaining the necessary torque transfer function.
2Strength
If the torque tube walls are conformed over angular end fittings, then engagement features are formed for torque transfer, but the tube life is reduced due to cracking
Solution Approach 1:
The smooth curved coupling surfaces eliminate stress concentration points during the tube forming process. The continuous curvature allows uniform stress distribution, preventing crack initiation that would reduce tube life, while still forming adequate engagement features for torque transfer strength.
Solution Approach 2:
The smooth curved geometry of the end fittings serves as a preventive measure before tube formation. By designing the coupling surfaces without sharp edges beforehand, the patent prevents stress concentration and crack initiation during the subsequent tube conforming process, thereby extending tube life while maintaining engagement strength.
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 solution enhances the durability of torque tubes by eliminating sharp edges and stress points, thereby extending their lifespan and preventing premature failure during power transmission applications.
Implementation Method 1
electromagnetically forming the end of the torque tube to conform the torque tube to the outer coupling surface of the first end fitting
Data Source
AI summary
One aspect of the present disclosure relates to an apparatus comprising a first end fitting. The first end fitting comprises a tube engagement portion. The tube engagement portion comprises an outer coupling surface. The outer coupling surface comprises a first virtual cross-section. The first virtual cross-section comprises a first transverse inflection point. Each point along the first virtual cross-section has a first virtual tangent line coplanar with the first virtual cross-section.