Self-Aligning Washer-Nut Assembly for Offset Angle Fasteners

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Solution Overview

Problem

Existing nut and washer assemblies in manufacturing require manual alignment and handling of multiple components, which is time-consuming and costly, especially when dealing with offset angle fasteners, and existing solutions like concave washers, convex nuts, or tapered fillers complicate the process and require additional tooling or steps.

Innovation Solution

A self-retaining washer and nut assembly with a retaining flange and positioning cavity, manufactured using additive manufacturing, allowing for offset angle positioning with spherical engagement surfaces and a blocking surface to maintain contact at maximum angles, ensuring consistent part dimensions and quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If manual alignment of separate nuts and washers is used, then alignment of offset angle fasteners can be achieved, but assembly time increases and risk of mishandling or loss increases

Engineering Contradiction:
Improvealignment accuracyVSAvoidassembly time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent combines the washer and nut into a single integrated assembly where the nut is retained within the washer structure. The washer includes a recess that receives and retains the nut, eliminating the need for separate handling and manual alignment of two distinct components. This merging resolves the contradiction by maintaining alignment accuracy while significantly reducing assembly time and handling complexity.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If concave washer and convex nut combination is used, then offset angle alignment is achieved, but device complexity and number of components increases

Engineering Contradiction:
Improveoffset angle accommodationVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent integrates the nut within the washer structure, creating a single-component assembly that provides offset angle accommodation. The washer includes a recess with engagement surfaces that work with corresponding surfaces on the nut to accommodate offset angles, eliminating the need for separate concave washer and convex nut components while maintaining the same functional capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated washer-nut assembly serves multiple functions within a single structure: the washer provides the base mounting surface, the recess retains the nut, and the engagement surfaces between the recess and nut accommodate offset angle fasteners. This multi-functionality reduces device complexity while maintaining offset angle accommodation capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If tapered filler is added, then offset angle alignment is achieved, but device complexity and number of manufacturing steps increases

Engineering Contradiction:
Improveoffset angle accommodationVSAvoidmanufacturing steps
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent combines the filler function into the integrated washer-nut structure. The recess in the washer and the corresponding engagement surfaces on the nut work together to provide the offset angle accommodation that would otherwise require a separate tapered filler. This merging eliminates the need for additional manufacturing steps such as drilling holes through separate fillers.

Inventive Principle:
Principle #5Merging (Combining)

4Manufacturing precision

If spot-facing is performed, then surface perpendicularity is improved, but additional tooling and manufacturing time is required

Engineering Contradiction:
Improvesurface perpendicularityVSAvoidtooling requirements
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent incorporates the alignment and perpendicularity functions into the pre-manufactured integrated washer-nut assembly. The engagement surfaces between the recess and nut are designed with precise geometries that automatically provide the necessary alignment and perpendicularity when assembled, eliminating the need for post-assembly spot-facing operations and additional tooling.

Inventive Principle:
Principle #10Preliminary action

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 solution enables efficient and cost-effective assembly of nut and washer combinations that can handle offset angle fasteners with full circumferential contact, reducing handling complexities and tooling requirements while ensuring reliable retention and alignment.

Implementation Method 1

manufactured using additive manufacturing

Methodology Applied
Scientific EffectAdditive manufacturing: 3D Printing

Implementation Method 2

The binder is cured to solidify a metal matrix in the structure of the washer and nut

Methodology Applied
Scientific EffectBinder curing: Photopolymerisation

Implementation Method 3

The metal matrix is then sintered

Methodology Applied
Scientific EffectSintering: Sintering

Implementation Method 4

The binder is removed by solvent wash or heat vaporization

Methodology Applied
Scientific EffectSolvent wash:

Implementation Method 5

The binder is removed by solvent wash or heat vaporization

Methodology Applied
Scientific EffectHeat vaporization: Evaporation

Implementation Method 6

The ceramic intermediary is vaporized in an oven cure leaving the consolidated metal washer and retained nut

Methodology Applied
Scientific EffectVaporization: Evaporation

Data Source

PatentEP3584454B1Retained self-aligning washer and nut assembly and method for fabrication by additive manufacturing
Publication Date: 2021.11.10 THE BOEING CO
  • EP3584454B1 patent drawingFigure 1A
  • EP3584454B1 patent drawingFigure 1B
  • EP3584454B1 patent drawingFigure 2

AI summary

A washer and retained nut assembly (8) has a washer (12) with a retaining flange (38) and a positioning cavity (44) and a nut (10) received in the washer. The nut has a shoulder (36) received in the positioning cavity with a top surface (42) of the shoulder engaging a lower surface (40) of the retaining flange in a loose condition of the washer and nut. The nut further has an engagement surface (24) contacting a receiving surface (26) in the washer in an engaged position of the washer and nut. The nut further has a peripheral surface (28) engaging a blocking surface (70) in the washer with the nut and washer in a maximum offset angle orientation between the washer and nut in the engaged position.