Tetherable Cavity Washer Prevents Fastener Loss
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Solution Overview
Problem
Existing tethering methods for fasteners are either costly, compromise the integrity of the fastener, or result in weak and inconvenient solutions that can lead to loss or damage, particularly in critical environments like space stations and construction sites, due to modifications required for manufacturing or the inherent weaknesses of makeshift washers.
Innovation Solution
A fastening system featuring a penetrating fastener with a longitudinally separated head and tip, paired with a tetherable cavity washer having a concave fastener cavity and rotationally asymmetric tether apertures, which prevents the fastener head from exiting by using an elongate tether extending through both apertures, ensuring secure attachment without modifying the fastener.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the fastener is modified (e.g., groove creation) to enable tethering, then the fastener can be securely tethered, but the manufacturing cost increases and the fastener's strength is compromised
Solution Approach 1:
The invention separates the tethering function from the fastener by introducing a distinct cavity washer component. The fastener remains unmodified while the washer provides the tethering mechanism through its tether aperture, thus resolving the contradiction by segmenting the functional requirements into separate components.
Solution Approach 2:
The cavity washer acts as an intermediary component between the fastener and the tether. Instead of modifying the fastener directly, the washer mediates the tethering function by receiving the fastener in its cavity and providing the tether aperture, thereby preserving fastener strength while enabling secure tethering.
2Reliability
If a C-shaped bracket is used to tether the fastener, then the fastener can be prevented from escaping, but the bracket is weak and prone to accidental bending or breaking
Solution Approach 1:
The invention replaces the single-piece C-shaped bracket with a segmented structure consisting of a cavity washer and a separate tether. The cavity washer provides a rigid, stable base while the tether provides the retention function, eliminating the weakness of the monolithic bracket design.
Solution Approach 2:
The solution combines different structural elements (cavity washer + tether) to achieve both strength and retention functionality. The cavity washer provides structural integrity while the tether provides the retention mechanism, creating a composite system that overcomes the limitations of the single-material bracket.
3Reliability
If the C-shaped bracket is used for tethering, then the fastener is secured, but the bracket snags on nearby structures causing damage and is difficult to reuse
Solution Approach 1:
By separating the tethering function into a distinct tether component, the invention eliminates the snagging problem associated with the C-shaped bracket's geometry. The tether can be routed through the washer without creating protruding edges that catch on nearby structures, improving ease of operation and reusability.
4Reliability
If specialty tethered fasteners are used, then proper tethering is achieved, but manufacturing delays occur and additional costs are incurred
Solution Approach 1:
The cavity washer serves multiple functions: it distributes load, prevents fastener rotation, and provides tethering capability. This multi-functionality eliminates the need for specialty tethered fasteners, allowing use of standard fasteners and improving assembly productivity while maintaining tethering effectiveness.
Data Source
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AI summary
A penetrating fastener 102 has a fastener head 104 and fastener tip 106 spaced apart by a longitudinally oriented fastener shaft 108. A tetherable washer 114 has a substantially planar base surface 532 having a fastener aperture 534 extending therethrough. A longitudinally oriented wall 338 extends longitudinally upward from at least a portion of the base surface to form a concave fastener cavity 640 configured to receive at least a portion of the fastener head. Two tether apertures 126 extend laterally through the wall and are laterally spaced apart along the wall. Both of the tether apertures are laterally arranged along the wall in a rotationally asymmetric configuration. A first one of the tether apertures is located a second longitudinal distance from the base surface and a second one of the tether apertures is located a third longitudinal distance from the base surface. The tether apertures are configured to simultaneously accept a tether 116 extending through both of the tether apertures.