Socket-Centered Washer Assembly to Prevent Fastener Skew

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Solution Overview

Problem

In gas turbine engines, the rotation of bolt heads can cause washers to skew, leading to uneven pressure distribution and rotational imbalances due to the lack of effective centering mechanisms in fastener assemblies.

Innovation Solution

A socket device with a centering sleeve and sleeve mount is used to secure a washer axially between the bolt head and the component, ensuring the washer remains coaxial with the bolt during tightening, preventing skewing and maintaining even pressure distribution.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional fastener assembly is used without a centering mechanism, then the fastening process is simple and device complexity is low, but the washer skews during tightening causing uneven pressure distribution and rotational imbalance

Engineering Contradiction:
Improvewasher centering accuracyVSAvoidfastening device structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The centering sleeve is nested within the socket device, with the centering sleeve having an inner surface that receives and centers the washer, while the socket portion engages the fastener element. This nested configuration allows the centering function to be integrated into the existing fastening tool without requiring a separate centering device, thus improving washer centering accuracy while minimizing additional device complexity

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The centering sleeve acts as an intermediary component between the socket device and the washer. The inner surface of the centering sleeve provides a centering interface that guides and centers the washer before and during tightening, ensuring proper alignment without requiring modification to the washer or fastener element themselves

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If the washer is allowed to rotate freely during tightening, then the fastening operation is quick and easy, but the washer skews to the side causing harmful effects on pressure distribution and structural balance

Engineering Contradiction:
Improvefastening operation simplicityVSAvoidwasher skewing and rotational imbalance
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The centering sleeve is positioned in place before the tightening operation begins, with its inner surface already configured to receive and center the washer. This preliminary centering action prevents the washer from skewing during rotation, allowing the fastening operation to proceed smoothly without requiring corrective actions or repositioning

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The centering sleeve provides a counteracting force against the skewing tendency of the washer during tightening. The inner surface of the centering sleeve maintains coaxial alignment by providing radial support that opposes any lateral movement or skewing of the washer, thereby preventing harmful rotational imbalance before it can occur

Inventive Principle:
Principle #9Preliminary anti-action

Data Source

PatentEP4368344A1Centering a washer to a fastener element during installation
Publication Date: 2024.05.15 PRATT & WHITNEY CANADA CORP
  • EP4368344A1 patent drawingFigure 1
  • EP4368344A1 patent drawingFigure 2
  • EP4368344A1 patent drawingFigure 3~5

AI summary

An assembly method is provided during which a first component (22) is arranged with a second component (24). The first component (22) is secured to the second component (24) using a fastener assembly (28). The fastener assembly (28) includes a fastener element (36) and a washer (46). The fastener element (36) includes a wrenching feature (78). The washer (46) has a full-hoop annular body with a cylindrical outer surface (94). The securing includes: mating a socket device (32) with the fastener element (36) and the washer (46), the socket device (32) engaging the wrenching feature (78) and the cylindrical outer surface (94); and rotating the fastener element (36) about an axis (34) using the socket device (32) to tighten the fastener assembly (28) and clamp the washer (46) axially between the first component (22) and the fastener element (36). The socket device (32) centers the washer (46) to the fastener element (36) during the rotating.