Blind Fastener Sleeve Deformation for Cross-Threading Prevention
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Solution Overview
Problem
The installation of threaded fasteners into threaded bores is challenging due to the need for precise alignment and torque control, which can lead to cross-threading and improper securing, resulting in structural joint failures and increased installation time.
Innovation Solution
A blind fastener system comprising a sleeve and a mandrel, where the mandrel's enlarged portion deforms the sleeve to match the threaded bore's threads, allowing for secure installation without requiring precise alignment or torque gauges, and can be easily removed by rotating the fastener.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If threaded fasteners are installed into threaded bores using conventional methods, then secure fastening can be achieved, but precise alignment and torque control are required, leading to cross-threading and improper securing
Solution Approach 1:
The blind fastener system is self-aligning through its geometry. The mandrel with enlarged portion automatically centers itself in the threaded bore during insertion, and the sleeve deforms to match the threads without requiring external torque control or precise alignment tools, making the system self-servicing during installation
Solution Approach 2:
The sleeve undergoes parameter change through deformation. The elongate portion of the sleeve is configured to deform plastically under the force from the mandrel's enlarged portion, transforming from a cylindrical shape to a threaded shape that matches the bore, eliminating the need for precise torque control
2Reliability
If threaded fasteners are installed with precise alignment and torque control, then cross-threading and improper securing are reduced, but installation time increases
Solution Approach 1:
The sleeve is pre-configured with an elongate portion that is designed to deform into threads. This preliminary preparation allows the fastener to automatically form the correct thread engagement during insertion without requiring slow, controlled torque application, thus maintaining reliability while increasing installation speed
Solution Approach 2:
The system performs its own thread formation function through the mandrel's enlarged portion forcing the sleeve to deform. This self-service mechanism eliminates the need for operators to carefully control torque and alignment, dramatically reducing installation time while ensuring proper thread engagement
3Strength
If conventional threaded fasteners are used, then secure fastening can be achieved, but cross-threading and improper securing result in structural joint failures
Solution Approach 1:
The sleeve's physical state changes from undeformed to deformed through the forcing action of the mandrel. This parameter change ensures the sleeve material flows to match the exact thread geometry of the bore, creating a perfect fit that prevents cross-threading and ensures maximum joint strength
Solution Approach 2:
The fastener system self-corrects any alignment issues through the deformation process. The mandrel's enlarged portion forces the sleeve to conform to the bore's thread geometry regardless of initial misalignment, eliminating cross-threading and ensuring proper engagement for maximum joint strength
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
This solution simplifies the installation process, increases the reliability of structural joints, and reduces the risk of damage by allowing for quick and secure fastening and easy removal, thereby enhancing the speed and reliability of the fastening process.
Implementation Method 1
The elongate portion is configured to at least partially deform into threads of the threaded bore responsive to forcible contact between the enlarged portion and the sleeve
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
Blind fasteners and methods of fastening are provided. A blind fastener comprises a sleeve and a mandrel. The sleeve is adapted for installation into a threaded bore in a structure. The sleeve comprises a head portion configured to receive a torque, a first sleeve end, a second sleeve end, an elongate portion extending intermediate the first sleeve end and the second sleeve end, and a cavity extending from the first sleeve end to the second sleeve end. The mandrel is at least partially disposed through the cavity of the sleeve. The mandrel comprises a first mandrel end disposed adjacent to the first sleeve end. The first mandrel end comprises an enlarged portion having a diameter greater than a diameter of the cavity. The elongate portion is configured to at least partially deform into threads of the threaded bore responsive to forcible contact between the enlarged portion and the sleeve.