Expanding Sleeve Fastener for One-Sided Interference Fit Joining
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Solution Overview
Problem
Current fastener systems require two-sided installation to achieve an interference fit, while those designed for one-sided installation only provide a clearance fit, limiting their effectiveness in joining multiple substrates of a workpiece.
Innovation Solution
The proposed fastener system includes a nut member with internal threads, a sleeve member with a lubricious coating, and a bolt member with a shank portion that radially expands the sleeve member, providing an interference fit within the joining bore of the workpiece during one-sided installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two-sided installation is used to achieve interference fit, then joining reliability is improved, but installation complexity increases
Solution Approach 1:
The fastener system is divided into three separate components: a nut member that remains installed in the blind hole, a sleeve member that is inserted first, and a bolt member that is installed last. This segmentation allows the interference fit to be achieved through sequential one-sided installation rather than requiring simultaneous two-sided assembly, resolving the contradiction between reliability and installation complexity.
Solution Approach 2:
The sleeve member is pre-installed in the blind hole before the bolt member is inserted. This preliminary action prepares the interference fit interface in advance, so that when the bolt is installed, the interference fit is already positioned correctly. This eliminates the need for complex two-sided alignment operations while maintaining joining reliability.
2Ease of operation
If one-sided installation is used to simplify installation process, then ease of operation is improved, but joining reliability deteriorates due to clearance fit
Solution Approach 1:
The sleeve member is designed with elastic or plastic deformability, allowing it to dynamically change its outer diameter. During installation, the sleeve is inserted in a relaxed state (clearance fit), then expands to create an interference fit with the blind hole wall. This dynamic transformation enables one-sided installation while achieving high joining reliability through the final interference fit state.
Solution Approach 2:
The outer diameter parameter of the sleeve member changes during installation. The sleeve is manufactured with a specific diameter that provides clearance for easy insertion, then undergoes expansion (through elastic deformation, plastic deformation, or phase change) to achieve a larger diameter that creates the interference fit. This parameter transformation resolves the contradiction between ease of installation and joining reliability.
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 enables one-sided installation while achieving an interference fit, enhancing the joining efficiency and reliability of multiple substrates in a workpiece.
Implementation Method 1
The sleeve member includes an outer sleeve surface with a lubricious coating
Implementation Method 2
As the bolt member becomes fully engaged with the nut member, the shank portion of the bolt member is configured to cause radial expansion of the sleeve member and the sleeve member is configured to provide an interference fit within the joining bore
Data Source
AI summary
A fastener system for joining substrates of a workpiece with working and blind sides includes a nut member, a sleeve member and a bolt member. The nut member includes a nut bore with internal threads. The nut member is placed with the nut bore over a joining bore through the substrates on the blind side. The sleeve member includes an outer sleeve surface with a lubricious coating. The sleeve member is inserted in the joining bore from the working side. The bolt member includes a head portion, a threaded portion and a shank portion. The bolt member is inserted in a central bore of the sleeve member. The threaded portion engages with the internal threads of the nut member. As the bolt member becomes fully engaged, the shank portion causes radial expansion of the sleeve member, and the sleeve member provides an interference fit within the joining bore.