Eccentric Blind Fastener Assembly for One-Sided Structural Clamping
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Solution Overview
Problem
Current blind fastener systems face issues with material weakness under structural load, complex installation methods, difficulty in manufacturing, and challenges with installation at varying angles or where sealant adherence is a concern, particularly in applications where access to one side of a structural assembly is difficult.
Innovation Solution
A blind fastener system featuring a sleeve with an eccentric through-bore and a core bolt, including a stop to prevent full rotation of the eccentric nut, allowing for one-sided installation and clamping of components without the need for softened materials, using a core bolt and eccentric nut that engages a stop after a specific rotation, enabling axial movement and secure clamping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If current tooling and installation methods use materials that change shape to form a nut or bulb, then installation is simplified, but the materials become weak under structural load leading to fastener failure
Solution Approach 1:
The fastener system is divided into separate components: a core bolt and a sleeve, where the sleeve contains an eccentric through-bore. This segmentation allows the core bolt to be inserted through the sleeve without requiring the sleeve material to deform, thereby maintaining structural integrity while simplifying installation.
Solution Approach 2:
An eccentric nut is introduced as an intermediary component that engages with the core bolt and interacts with the stop feature on the sleeve. This mediator enables the fastening action without requiring the sleeve material itself to deform or weaken, resolving the contradiction between ease of installation and fastener strength.
2Reliability
If complex tooling and installation methods are used for blind fastener systems, then secure fastening is achieved, but manufacturing complexity and difficulty increase
Solution Approach 1:
The fastener system is designed to be self-contained and self-actuating. The core bolt, when rotated, directly drives the eccentric nut which engages with the stop on the sleeve to create the fastening action. This eliminates the need for complex external tooling or multi-step installation procedures, thereby reducing device complexity while maintaining fastening security.
3Ease of manufacture
If blind fastener systems are designed for standard installation, then manufacturing is simplified, but installation at varying angles becomes difficult
Solution Approach 1:
The sleeve is designed with an asymmetric stop feature that is positioned eccentrically relative to the through-bore. This asymmetric geometry allows the fastener to be installed at various angles while maintaining proper engagement between the eccentric nut and the stop, thereby providing installation angle flexibility without complicating manufacturing.
4Reliability
If sealant is used in blind fastener installation, then sealing is improved, but the sealant may adhere to and jam the internal drive mechanism of the nose piece
Solution Approach 1:
The internal drive mechanism of the nose piece is extracted or removed from the fastener system. Instead of relying on a complex internal drive mechanism that could be jammed by sealant, the design uses a simpler core bolt and eccentric nut arrangement that does not require protected internal mechanisms, thereby eliminating the risk of sealant adhesion and jamming while maintaining sealing effectiveness.
Data Source
AI summary
A blind fastener includes a sleeve defining a sleeve central axis and having a sleeve shank having a distal end portion and a proximal end portion axially opposed from the distal end portion and a stop connected to the distal end portion of the sleeve shank. The sleeve defines an eccentric through-bore that extends along a through-bore axis from the proximal end portion to the distal end portion. The blind fastener includes a core bolt at least partially received in the eccentric through-bore of the sleeve, defining a core bolt central axis. A core bolt shank has a distal end portion, a proximal end portion axially opposed from the distal end portion, and a threaded portion. A core bolt head is connected to the proximal end portion of the core bolt shank. An eccentric nut is threaded into engagement with the threaded portion of the core bolt shank.