Lightning-Resistant Fastener With Mechanical Insulating Cap
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Solution Overview
Problem
Conventional lightning-resistant fasteners for aircraft airframes face challenges in workability, quality stability, and cost due to misalignment issues and labor-intensive adhesive or coating processes, which compromise lightning resistance and reliability.
Innovation Solution
A lightning-resistant fastener system featuring insulating caps with engaging portions and a method for attaching them to fastener members, ensuring precise positioning and reduced manufacturing costs through the use of insulating sealant agents and ergonomic design for easy handling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cap is attached using adhesive agent or rubber coating, then lightning resistance is achieved, but workability deteriorates and manufacturing cost increases
Solution Approach 1:
The patent replaces the chemical bonding method (adhesive agent) and coating method (rubber) with a mechanical engagement system consisting of an engaging portion on the fastener member and a corresponding engaged portion on the cap. This mechanical connection achieves both lightning resistance through proper positioning and improved workability through simplified attachment procedures.
2Reliability
If the cap is attached using adhesive agent or rubber coating, then lightning resistance is achieved, but manufacturing cost increases
Solution Approach 1:
The patent eliminates the need for adhesive agents and rubber coatings by implementing a direct mechanical engagement system. This substitution reduces material costs, simplifies the manufacturing process, and improves ease of manufacture while maintaining lightning resistance through proper cap positioning.
3Ease of operation
If the cap center and fastener member center are misaligned, then workability is improved, but lightning resistance deteriorates
Solution Approach 1:
The patent employs asymmetric positioning features where the engaging portion on the fastener member and the engaged portion on the cap are designed to align specifically with the center of the fastener member. This asymmetric design ensures proper alignment and maintains lightning resistance while keeping the attachment process simple and workable.
Solution Approach 2:
The mechanical engagement system is designed to self-align the cap with the fastener member center through the geometry of the engaging and engaged portions. This self-aligning feature ensures proper positioning for lightning resistance without requiring complex alignment procedures, thereby maintaining ease of operation.
Data Source
AI summary
A lightning-resistant fastener, a cap, a fastener member, and a method for attaching the lightning-resistant fastener are provided, which enhance workability and quality stability besides reliably securing an insulating property, and can lead to enhancement in safety of an airframe and reduction in manufacturing cost. A head portion 25b of a fastener main body 25 includes a head cap 50, and a shaft portion 25s of the fastener main body 25 includes a shaft cap 30, whereby a direct strike of lightning to a fastener member 24, and occurrence of an arc discharge from the fastener member 24 in the case of a lightning strike can be suppressed. A hole 52 is formed in the head cap 50, and a thread groove 52a is formed in the hole 52, whereby the head cap 50 can be reliably and easily positioned and attached to the fastener member 24.