Eccentric Blind Fastener Structure for Non-Normal Installation
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Solution Overview
Problem
Current blind fastener systems face challenges with material weakness under structural load, complex manufacturing, and difficulty in installation at non-normal angles or with sealants, which can jam the internal drive mechanism, and high costs.
Innovation Solution
The design incorporates an eccentric nut and sleeve with a stop, allowing the nut to rotate with the core bolt initially and then move axially after engaging the stop, eliminating the need for softened materials and simplifying installation by using a tool to apply torque and axial force, enabling secure clamping at varying angles without jamming.
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 the blind fastener can be installed from one side, but the materials become weak under structural load leading to failure
Solution Approach 1:
The fastener system is divided into distinct components: a core bolt that remains intact and an eccentric nut that provides the forming action. The core bolt maintains full strength while the eccentric nut, which undergoes deformation, is a separate replaceable component. This segmentation allows the load-bearing element to remain strong while still enabling one-sided installation through the eccentric nut's forming action.
2Reliability
If complex tooling and installation methods are used for blind fastener systems, then the fastening function can be achieved, but the systems become difficult to manufacture and integrate with robotics
Solution Approach 1:
The eccentric nut performs the forming action automatically through its eccentric geometry during installation. As the core bolt rotates, the eccentric nut's offset center causes it to be pulled into engagement and form the bulb automatically without requiring complex external tooling. This self-forming mechanism simplifies the installation process and enables integration with robotic systems.
3Reliability
If sealant is applied during installation, then sealing function is achieved, but the sealant adheres to and jams the internal drive mechanism of the nose piece
Solution Approach 1:
The sealing function is extracted from the internal drive mechanism and placed at the interface between the fastener components and the workpiece. The eccentric nut forms a bulb that creates a seal at the installation interface, separating the sealing function from the drive mechanism. This prevents sealant from adhering to and jamming the internal drive components while still achieving the required sealing function.
4Adaptability or versatility
If installation is performed at varying non-normal angles, then adaptability is improved, but the internal drive mechanism becomes prone to jamming
Solution Approach 1:
The eccentric nut's asymmetric geometry with its offset center allows it to accommodate installation at varying angles. The eccentric design creates a natural alignment path that guides the nut into proper engagement regardless of the initial insertion angle, enabling adaptability while preventing jamming of the drive mechanism through controlled engagement geometry.
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.