Cap with Opposite Helical Threads for Fastener Securing
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Solution Overview
Problem
Existing cap securing structures for aircraft fasteners are prone to loosening and increased manufacturing costs due to the need for special fasteners and adhesives, and pose risks of interference and filler leakage into fuel tanks.
Innovation Solution
A cap design with a female threaded helical filler engaging part that includes a first and second helical engagement part with opposite helical directions, allowing mechanical connection without direct screwing to the fastener, using an existing short fastener and preventing filler protrusion with a masking member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cap is secured by directly screwing the cap to the tip part of the fastener, then the cap is favorably secured to the fastener, but it is necessary to extend the tip part of the fastener and use a fastener having a special size which is longer than the length of an existing fastener, and a cost increases
Solution Approach 1:
The invention divides the securing function into two parts: the standard fastener provides the basic securing function, while the cap with its integrated thread portion provides the threading engagement. This segmentation allows the use of standard fasteners without extension, reducing manufacturing cost while maintaining securing reliability.
Solution Approach 2:
The cap is designed to surround and enclose the tip part of the fastener, with the thread portion nested within the cap body. This nesting arrangement allows the cap to provide threading engagement without requiring the fastener itself to be extended, thus avoiding the need for special long fasteners and reducing costs.
2Reliability
If the tip part of the fastener is extended to screw the cap, then the cap can be secured, but a dimension in an axis direction of the cap covering the tip part increases, and the risk of interference between the cap and the structure element around the cap increases
Solution Approach 1:
Instead of extending the fastener to provide threading engagement, the invention inverts the approach by providing the thread portion on the cap itself. This allows the cap to engage with the fastener tip without requiring the fastener to be longer, thus reducing the overall assembly length and eliminating interference risks with surrounding structure elements.
3Reliability
If the cap is secured by directly screwing the cap to the tip part of the fastener, then the cap is favorably secured, but the cap weight increases
Solution Approach 1:
The invention merges the threading function and the cap body into a single integrated component. The thread portion is formed as an integral part of the cap, eliminating the need for a separate extended fastener. This merging reduces the total weight of the cap assembly while maintaining secure attachment through threading engagement.
4Reliability
If a fastener having a special size which is longer than the length of an existing fastener is used, then the cap can be screwed to the fastener, but a cost increases
Solution Approach 1:
The cap is designed with a universal thread portion that can engage with standard fastener tips without requiring special long fasteners. This multi-functional design allows the cap to provide both the sealing function and the threading engagement function, enabling the use of standard fasteners and reducing manufacturing costs while maintaining reliable screw connection.
Data Source
AI summary
A cap is applied to a securing structure part for securing structure elements using a fastener passed through through-holes formed in the structure elements, and a collar fastened to the tip part of the fastener. A filler engaging part for engaging a cured filler, configured with a female thread that turns about a center axis, is formed on the inner peripheral surface of the cap. The filler engaging part includes a first helical engagement part formed in the region near the cap inner part of the inner peripheral surface in the center axis direction; and a second helical engagement part formed in the region near the cap opening-end part in the center axis direction, the inner diameter of the second helical engagement part being greater than that of the first helical engagement part, and having a helical direction that is opposite to that of the first helical engagement part.