Compact Fastener With Spring Fingers to Prevent Creep Back-Out
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Solution Overview
Problem
Ruggedized products face challenges with plastic creep and fastener back-out in high-temperature and high-shock environments, where metals are heavy and low-creep plastics lack desirable characteristics like high yield strength and low thermal expansion, leading to issues with clamping pressure and component alignment in devices like VR/AR devices.
Innovation Solution
An anti-creep anti-back-out fastener design integrating a compression spring and optional serrations into a compact design, allowing for direct application of compressive force and preventing loosening, which reduces the need for additional parts and maintains alignment under vibration and temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If metals are used for fasteners to maintain clamping pressure, then creep resistance is improved, but weight increases
Solution Approach 1:
The patent combines a spring mechanism and anti-backout features into a single integrated fastener component, eliminating the need for separate metal spring washers and reducing overall weight while maintaining creep resistance through the spring fingers that continuously apply clamping force
Solution Approach 2:
The patent changes the material parameter from heavy metal to lightweight plastic, and modifies the structural parameters by incorporating integrated spring fingers and anti-backout features, achieving comparable creep resistance and anti-loosening performance without the weight penalty of traditional metal fasteners
2Weight of moving object
If low-creep plastics are used for fasteners, then weight is reduced, but yield strength and thermal expansion properties deteriorate
Solution Approach 1:
The fastener is segmented into functional zones: the spring fingers provide elastic compliance and continuous clamping force, the serrated portions provide anti-backout capability, and the threaded portion provides fastening function. This segmentation allows each zone to be optimized for its specific function, compensating for the lower yield strength of plastic through intelligent structural design
Solution Approach 2:
The patent employs composite material strategies by integrating multiple functional features (spring fingers, serrations, threads) into a single plastic fastener, creating a composite structure that combines the benefits of elasticity, friction-based locking, and threaded fastening to achieve overall performance comparable to metal fasteners
3Stability of the object's composition
If separate spring washers are used for anti-creep, then device complexity increases, but handling and assembly difficulty increases
Solution Approach 1:
The patent merges the spring washer function, anti-backout feature, and fastener head into a single integrated component. The spring fingers are directly formed as part of the fastener body, eliminating the need for separate spring washers and simplifying assembly to a single fastening operation
Solution Approach 2:
The integrated fastener performs multiple functions simultaneously: it provides clamping force through spring fingers, prevents back-out through serrated features, and secures the connection through threading. This multi-functionality in a single component reduces the number of parts and simplifies the overall fastening system
4Stability of the object's composition
If thicker wall sections are used for injection molding low-creep plastics, then creep resistance is improved, but part weight increases
Solution Approach 1:
Instead of increasing wall thickness to improve creep resistance, the patent changes the structural parameters by incorporating spring fingers with optimized geometry and material properties. The spring fingers are designed with specific thickness and curvature to provide the required elastic compliance and clamping force without requiring excessive material, thereby maintaining low weight
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
The integrated fastener design effectively maintains compressive load and prevents back-out, ensuring reliable operation in harsh environments by applying compressive force through spring fingers and serrations, reducing the risk of component loosening and alignment issues.
Implementation Method 1
an anti-creep anti-back-out fastener design which integrates a compression spring and optionally an anti-back-out mechanism (e.g., serration) into one compact design
Implementation Method 2
optional an anti-back-out mechanism (e.g., serration) into one compact design
Data Source
AI summary
An integrated fastener includes a threaded portion, a fastener head, and one or more spring fingers integrated into the fastener head, wherein the spring fingers are configured to apply a compressive load when the fastener is inserted and secured to a receiving assembly.