Asymmetric Trapezoidal Thread Profile for Vibration-Resistant Fasteners
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Solution Overview
Problem
Existing threaded fasteners with trapezoidal thread forms often loosen under vibration in applications with high forces and large diameters, requiring additional materials or components for vibration mitigation, which can lead to deformation and reduced reusability.
Innovation Solution
The development of new thread profiles with specific angular orientations for crest, leading, root, and trailing flanks, allowing for point contact between threads, which enhances vibration resistance and enables the fasteners to spin freely and be reused multiple times without the need for anti-vibration patches or pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional trapezoidal thread forms are used in large diameter fasteners subjected to high forces, then the fasteners can handle large loads, but they loosen under vibration
Solution Approach 1:
The patent applies asymmetry by creating an asymmetric thread profile where the load-bearing surface and vibration-resisting surface are differently oriented. The thread form includes a load-bearing flank at a first angle to the thread axis and a vibration-resisting flank at a second angle, allowing the same thread structure to optimize for both force transmission and vibration resistance simultaneously
Solution Approach 2:
The patent changes the geometric parameters of the thread form by specifying precise angular orientations for different thread surfaces. The load-bearing surface is oriented at a first angle (e.g., 15-30 degrees) while the vibration-resisting surface is oriented at a second angle (e.g., 0-10 degrees), creating a multi-angle thread profile that optimizes both force handling and vibration resistance
2Reliability
If fastener coatings such as thread-sealing adhesives, thread lubricants, anti-vibration coatings, and patches are applied, then vibration resistance is improved, but material cost and application cost increase significantly
Solution Approach 1:
The patent extracts the vibration resistance function from external coatings and additives, embedding it directly into the thread geometry itself. The asymmetric thread form inherently provides vibration resistance through its geometric configuration, eliminating the need for separate coating materials and their associated costs
Solution Approach 2:
The thread form serves itself by providing both load-bearing and vibration-resisting functions through its own geometric structure. The asymmetric profile enables the thread to resist vibration through its inherent shape without requiring external materials or additives, making the system self-sufficient
3Reliability
If excessive force is applied to force a nut onto a threaded connection, then the connection is secured, but deformation occurs preventing reuse of the nut
Solution Approach 1:
The patent changes the geometric parameters of the thread form to include optimized angular orientations that distribute loading more evenly. The asymmetric profile with specific angle ranges creates more uniform stress distribution during installation, reducing peak stresses that cause deformation and enabling nut reuse
4Reliability
If separate components such as pins are used to restrict movement of the nut, then vibration resistance is improved, but device complexity increases
Solution Approach 1:
The patent merges the vibration resistance function into the thread form itself, combining multiple functions (load-bearing and vibration-resisting) into a single integrated geometric structure. This eliminates the need for separate vibration-resisting components like pins or lock nuts
Solution Approach 2:
The asymmetric thread form serves multiple functions simultaneously: it provides load-bearing capability through one surface orientation and vibration resistance through another surface orientation. This multi-functional design replaces the need for multiple separate components
Data Source
Figure 1A~1B
Figure 2
Figure 3
AI summary
A threaded fastener having a thread defined by a crest portion, a leading flank, a first root portion, a second root portion, and a trailing flank, configured to engage an externally threaded trapezoidal threadform. The thread may alternatively be defined by a foot portion, a leading flank, a first crest portion, a second crest portion, and a trailing flank, configured to engage an internally threaded trapezoidal threadform.