Asymmetric Threaded Positioning Mechanism for Bolt Stability
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Solution Overview
Problem
Existing threaded connections often experience undesired bolt movement and axial displacement during nut tightening due to differential torsional friction, which current solutions like SPIRALOCK threads do not adequately address.
Innovation Solution
The use of threaded installations with specific flank angle configurations, where the product of the cosine of the flank angles at the bolt-nut connection and the bolt-housing connection is greater than 1.0, allowing for asymmetric threading that distributes load effectively to minimize rotational and axial displacement without external securing of the bolt.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard threaded connections are used, then the structure is simple and easy to manufacture, but the bolt experiences rotational and axial displacement during nut tightening due to differential torsional friction
Solution Approach 1:
The patent applies asymmetry by configuring the threaded connection with different flank angles on opposite sides of the thread. Specifically, one flank angle is designed to be larger than the other, creating an asymmetric thread profile that generates differential torsional friction. This asymmetry causes the bolt to rotate in a controlled direction during nut tightening, preventing unwanted axial displacement and improving positioning reliability without requiring additional external securing mechanisms.
2Reliability
If external securing of the bolt is used during nut tightening, then bolt position stability is improved, but the operation becomes more complex and time-consuming
Solution Approach 1:
The asymmetric threaded connection design enables the bolt to self-regulate its position during tightening. The differential torsional friction generated by the asymmetric flanks automatically guides the bolt's rotation, eliminating the need for external securing devices or additional operational steps. The system serves itself by using the tightening action to maintain bolt stability, thereby simplifying the overall operation while ensuring reliable positioning.
3Reliability
If SPIRALOCK threads are used, then loosening due to vibrations is prevented, but the specific issue of bolt movement during tightening is not adequately addressed
Solution Approach 1:
The patent applies local quality by differentiating the flank angles at specific locations on the thread. Rather than using a uniform thread profile, the asymmetric design creates localized variations in friction characteristics at different flanks. This local differentiation allows the thread to simultaneously provide vibration resistance (through the locking action) and control bolt movement during tightening (through the differential torsional friction), thereby achieving both reliability and positioning precision.
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 configuration reduces rotational and axial displacement of the bolt during nut tightening, enabling precise positioning of components without the need for external bolt securing, thus improving the accuracy and reliability of threaded connections.
Implementation Method 1
differential in the torsional friction at the threaded connection between the bolt and the component relative to the torsional friction at the threaded connection between the nut and the bolt
Data Source
AI summary
A threaded installation is provided. The threaded installation includes a nut, a bolt, and a housing. The housing includes a threaded hole. A first threaded connection is formed where the bolt is threadably coupled with the nut, and a second threaded connection is formed where the bolt is threadably coupled with the threaded hole. The first threaded connection is characterized by a first flank angle, Θ2A, of threads of the bolt or threads of the nut. The second threaded connection is characterized by a second flank angle, Θ3B, of threads of the bolt or threads of the housing. The flank angles, Θ2A and Θ3B, satisfy the following equation:k2=cos(θ2A)cos(θ3B)>1.00.