Structural Blind Sleeve Clamping via Buckling Bulb Formation

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Solution Overview

Problem

Current blind fastener systems lack clamping support, are complex to manufacture and integrate with robotics, and struggle with installations at non-normal angles and with sealants that can jam the internal drive mechanism.

Innovation Solution

The development of structural blind sleeves with a monolithic body featuring a sleeve shank with a structural portion, a threaded portion, and a softened portion, along with a sleeve head and a tool for installing the sleeve, which forms a bulb in the sleeve shank to provide clamping support.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If current blind fastener systems use simple sleeve components for retaining bolts, then the fastening function is achieved, but clamping support for the structures being fastened together is not provided

Engineering Contradiction:

Improveclamping supportVSAvoidsleeve component structure

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The sleeve is divided into distinct functional segments: a structural portion for clamping support, a softened portion for deformation, and a threaded portion for bolt retention. This segmentation allows each portion to perform its specific function optimally while maintaining overall system simplicity

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The sleeve material properties are changed along its length, with the softened portion having different material characteristics than the structural portion. This parameter change enables the softened portion to deform and form a bulb under compressive load while the structural portion maintains rigidity for clamping support

Inventive Principle:

Principle #35Parameter changes

2Reliability

If complex tooling and installation methods are used for blind fastener systems, then fastening functionality is achieved, but manufacturing complexity and difficulty of integration with robotics increase

Engineering Contradiction:

Improvefastening functionalityVSAvoidtooling manufacturing

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The installation tool combines multiple functions into a single device: the bearing member provides axial retention while the threaded shaft engages the sleeve threads and applies compressive load. This merging of functions simplifies the tool design and reduces manufacturing complexity compared to multi-component systems

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The sleeve's threaded portion is designed to engage directly with the tool's threaded shaft, allowing the tool to automatically apply the correct compressive load to form the bulb. The system self-regulates the installation process without requiring complex control mechanisms or multiple adjustment steps

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If current blind fastener installation methods are used, then normal angle installations are achieved, but installations at varying (non-normal) angles and with sealants are problematic due to jamming of the internal drive mechanism

Engineering Contradiction:

Improveinstallation angle flexibilityVSAvoidinstallation operation

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The bearing member is designed to dynamically adjust its position and orientation during installation, accommodating varying angles between the structures. The axial bearing force is applied in a direction that adapts to the relative orientation of the structures being joined

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The bearing member acts as an intermediary between the tool and the sleeve head, providing a contact interface that can accommodate sealants and varying installation angles. The bearing member's geometry and material properties allow it to function effectively even when sealants are present at the interface

Inventive Principle:

Principle #24Intermediary (Mediator)

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 structural blind sleeves effectively provide clamping support, simplify manufacturing and integration with robotics, and improve installation capabilities at varying angles and with sealants, reducing costs and complexity.

Implementation Method 1

axial pulling of the threaded portion provides compressive loading on the structural blind sleeve to yield buckling of the sleeve shank

Methodology Applied

Scientific EffectBuckling:

Data Source

PatentUS12292065B2Structural blind sleeves and associated systems and methods for clamping a first structure relative to a second structure to yield a clamped-up structure

Publication Date: 2025.05.06 THE BOEING CO

AI summary

A structural blind sleeve includes a monolithic body. The monolithic body has a sleeve shank having an elongated tubular structure defining a proximal portion and a distal portion, the sleeve shank having a structural portion proximate the proximal portion, a threaded portion proximate the distal portion, and a softened portion between the structural portion and the threaded portion. The structural portion is capable of carrying a clamp-up structural load. The monolithic body further includes a sleeve head connected to the proximal portion of the sleeve shank.