Blind Fastener Removal with Minimal Backside Clearance

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Solution Overview

Problem

Existing methods for removing blind fasteners require increased backside clearance, leading to larger structural assemblies, increased weight, and reduced usable space, particularly in aircraft and other structures where minimal clearance is necessary for installation.

Innovation Solution

A method and apparatus for removing blind fasteners that involves removing the head portion of the core bolt, driving the remaining core bolt through the body, and extracting the body from the bore using a specialized tool, allowing for minimal backside clearance during installation while enabling efficient removal without increasing structural size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If existing methods for removing blind fasteners are used, then the fastener can be removed, but increased backside clearance is required leading to larger structural assemblies

Engineering Contradiction:

Improvefastener removal capabilityVSAvoidstructural assembly size

Core Design Contradiction:

Ease of operationVSVolume of stationary object

Solution Approach 1:

Instead of driving the core bolt out from the front (conventional method), the invention drives the core bolt through the body from the front and extracts it from the backside. This inverted extraction approach allows removal without requiring excessive backside clearance, as the core bolt is pushed through rather than pulled out from the constrained backside area.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention extracts only the necessary portion (core bolt) from the fastener assembly while leaving the body in place during the initial extraction phase. By separating the removal of the core bolt from the removal of the body, the method enables fastener removal without requiring increased backside clearance for the entire assembly.

Inventive Principle:

Principle #2Taking out (Extraction)

2Ease of operation

If existing removal methods are used, then the fastener can be removed, but structural weight increases due to larger assemblies

Engineering Contradiction:

Improvefastener removal capabilityVSAvoidstructural assembly weight

Core Design Contradiction:

Ease of operationVSWeight of stationary object

Solution Approach 1:

The inverted extraction method allows the structural assembly to maintain its original compact dimensions, thereby preserving the intended weight savings. By not requiring increased backside clearance, the structural assembly doesn't need to be enlarged, and thus doesn't gain unnecessary weight.

Inventive Principle:

Principle #13The other way round (Inversion)

3Ease of operation

If existing removal methods are used, then the fastener can be removed, but usable space decreases due to larger structural assemblies

Engineering Contradiction:

Improvefastener removal capabilityVSAvoidusable space

Core Design Contradiction:

Ease of operationVSVolume of moving object

Solution Approach 1:

By inverting the extraction direction and pushing the core bolt through from front to back, the method enables removal without increasing the overall structural assembly dimensions. This preserves the original usable space within the structure that would otherwise be reduced by enlarged clearance requirements.

Inventive Principle:

Principle #13The other way round (Inversion)

4Volume of stationary object

If minimal backside clearance is maintained for installation, then space efficiency is optimized, but conventional removal methods cannot be used

Engineering Contradiction:

Improvestructural assembly sizeVSAvoidfastener removal capability

Core Design Contradiction:

Volume of stationary objectVSEase of operation

Solution Approach 1:

The invention specifically addresses this contradiction by inverting the removal approach: instead of attempting to pull the core bolt out from the constrained backside (which fails with minimal clearance), the method pushes the core bolt through the body from the front and extracts it from the backside, enabling removal with minimal backside clearance maintained.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The removal process is segmented into distinct phases: first driving the core bolt through the body, then extracting it from the backside. This segmentation allows the removal operation to proceed in a manner compatible with minimal backside clearance, unlike conventional single-phase removal methods.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS7555820B2Methods for removing blind fasteners

Publication Date: 2009.07.07 THE BOEING CO

AI summary

Various methods and apparatuses for removing blind fasteners, portions of blind fasteners, and/or other fasteners from structural assemblies are described herein. In one embodiment, a blind fastener can have a core bolt extending through a passage in a body. One method for removing the blind fastener from a structural assembly in accordance with one aspect of the invention can include removing a head portion from the core bolt, and driving the remaining portion of the core bolt at least partially through the body in a first direction. The method can further include extracting the body from the bore in a second direction opposite to the first direction. In one embodiment, the body can be extracted from the bore by inserting a tool into the passage and engaging the body, and then pulling the body in the second direction with the tool.