Selective-Hardening Sleeve Nut for Reliable Blind Fastening
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Solution Overview
Problem
Existing blind fasteners face challenges in restricted access environments, where failure on the blind side can make it difficult and time-consuming to remove and replace failed fasteners, and the two-piece construction of nut and sleeve structures can lead to slippage and incomplete installations due to differing material performance requirements.
Innovation Solution
A deformable sleeve nut is manufactured by selectively strain hardening a single piece of material to combine the functions of the nut and sleeve in a unitary structure, with the nut portion being hardened and the sleeve portion remaining ductile, reducing failure modes and improving installation reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a two-piece construction of nut and sleeve is used, then the fastener can be installed from one side, but slippage and incomplete installations occur due to differing material performance requirements
Solution Approach 1:
The patent combines the nut and sleeve into a single unitary deformable sleeve nut structure. This eliminates the interface between two separate components, preventing slippage between nut and sleeve during installation. The unified structure ensures that the fastening force is transmitted directly from the sleeve to the workpiece without loss through component interfaces.
Solution Approach 2:
The deformable sleeve nut incorporates different material properties in different regions: the distal end portion is made ductile for deformation and forming the clamping surface, while the proximal end portion is made harder for engaging with the blind side clamping surface. This local differentiation of material properties optimizes each region's function while maintaining structural unity.
2Ease of operation
If access to both sides of the fastener is restricted, then blind fastener installation is enabled, but removal and replacement of failed fasteners becomes difficult and time-consuming
Solution Approach 1:
The deformable sleeve nut is designed to be dynamically removable through deformation. By applying force to deform the sleeve portion, the fastener can be collapsed or compressed to reduce its profile, enabling removal through the same restricted opening used for installation. This dynamic transformation from extended to compressed state facilitates both installation and removal in confined spaces.
3Shape
If the sleeve portion is made ductile for deformation, then the clamping surface can be formed, but the nut portion may slip relative to the sleeve
Solution Approach 1:
The patent merges the nut and sleeve into a single monolithic structure where the distal end portion and proximal end portion are integral. This eliminates the relative slippage problem between separate components while maintaining the ductility needed for clamping surface formation. The unified structure ensures force transmission without interface failure.
Solution Approach 2:
The deformable sleeve nut incorporates different material properties in different regions: the distal end portion is made ductile for deformation and forming the clamping surface, while the proximal end portion is made harder for engaging with the blind side clamping surface. This local differentiation of material properties optimizes each region's function while maintaining structural unity.
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
The deformable sleeve nut reduces slippage and failure modes by ensuring a secure, reliable installation process, allowing for easier removal and replacement of fasteners, and optimizing material properties for enhanced performance.
Implementation Method 1
selectively strain hardening a single piece of material to combine the functions of the nut and sleeve in a unitary structure, with the nut portion being hardened and the sleeve portion remaining ductile
Data Source
AI summary
Disclosed is a method of manufacturing a deformable sleeve nut that includes selectively strain hardening only a first portion of a material blank while not strain hardening a second portion of the material blank, then, after strain hardening the first portion of the material blank, internally threading the first portion of the material blank to define a nut portion and machining the second portion of the material blank to define a deformable sleeve portion that includes an end portion and a bulbing portion positioned between the end portion and the nut portion, where the bulbing portion is constructed to bulb outwardly and form a load bearing flange when the bulbing portion is compressed between the end portion and the nut portion. Also disclosed is a deformable sleeve nut made with this process.