Helical Thread Insert Nut for Reusable Locking Fasteners
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Solution Overview
Problem
Existing locking fasteners, particularly those using resilient inserts like Vespel™, are expensive, difficult to install, and have limitations such as being easily damaged, non-reusable, and limited in shape flexibility, with inconsistent torque values over cycles and susceptibility to temperature and vibration variations.
Innovation Solution
A new type of nut featuring a helical thread insert and a retained clasp, such as the Lockone clasp, which provides a strong and reusable fastening solution with improved torque consistency and resistance to vibration and temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resilient inserts like Vespel™ are used in locking fasteners, then locking capability is achieved, but cost increases and installation difficulty increases
Solution Approach 1:
The patent extracts the locking insert from being a separate component requiring installation and integrates it as a built-in feature of the nut itself. The nut includes an internal thread structure with locking surfaces that engage directly with the bolt threads, eliminating the need for separate resilient inserts and their complex installation procedures.
Solution Approach 2:
The patent combines the locking function and the fastening function into a single integrated nut structure. The internal threads of the nut incorporate locking surfaces that simultaneously provide both the fastening engagement and the locking action, merging what were previously separate components (nut and locking insert) into one unified element.
2Reliability
If resilient inserts are used for locking, then locking function is provided, but the inserts are easily damaged and cannot be reused
Solution Approach 1:
The patent changes the material parameter from resilient plastic (Vespel™) to metal, fundamentally altering the mechanical properties. The metal construction provides superior strength, damage resistance, and reusability while maintaining the locking function through precisely engineered thread surfaces with locking features that engage mechanically.
Solution Approach 2:
The patent employs a composite thread structure where the internal threads of the nut feature specialized surfaces designed for locking engagement. The metal construction allows for optimized material properties combining strength, wear resistance, and controlled friction characteristics to achieve reliable locking without the fragility of plastic inserts.
3Reliability
If resilient inserts are used, then locking is achieved, but shape flexibility is limited and torque values are inconsistent
Solution Approach 1:
The patent applies local quality by creating specific locking surfaces at critical locations within the internal threads of the nut. These localized features include angled surfaces and engagement points that provide locking action only where needed, while the rest of the thread structure maintains standard geometry for compatibility and flexibility in various applications.
Data Source
AI summary
A fastener system including a nut body and a helical thread insert. The nut body having an internally threaded bore containing a plurality of bore threads, and at least one bore obstruction. The helical thread insert formed to create a plurality of internal HTI threads and a plurality of external HTI threads, with the helical thread insert received in the internally threaded bore and not occupying all of the plurality of bore threads, and having its movement limited by the bore obstruction. The helical thread insert having threads with both circular end profiles and a non-circular end profile. The non-circular end profile including at least three straight segments, and located between circular threads.