Acoustic Thread Alignment Tool for Aerospace Fasteners

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Solution Overview

Problem

Threaded fasteners often become cross-threaded due to misalignment, leading to thread damage and failure, especially in frangible collar fasteners used in aerospace, where misalignment is common and can result in incomplete assembly and reduced holding force.

Innovation Solution

A thread alignment tool that uses a socket and sensors to detect acoustic signals generated when threads align, allowing for active feedback to ensure proper alignment before threading, reducing the risk of cross-threading by rotating the fastener in a reverse-thread direction and stopping when a thread-fall acoustic signal is detected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If threaded fasteners are installed without alignment detection, then the installation process is simple and fast, but cross-threading and thread damage occur frequently

Engineering Contradiction:
Improvealignment accuracyVSAvoiddetection system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical alignment detection systems with acoustic field-based detection. Acoustic sensors detect the thread-fall signal generated when misaligned threads become aligned during rotation, providing a non-contact, simple method to determine proper alignment without complex mechanical measurement devices

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces acoustic waves as an intermediary to detect thread alignment. The acoustic sensor detects vibrations and sounds generated by the thread-fall event, serving as a mediator between the mechanical threading process and the control system to indicate when alignment is achieved

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If alignment detection is implemented, then cross-threading is prevented, but the installation time increases due to detection and control steps

Engineering Contradiction:
Improvethreading success rateVSAvoidinstallation cycle time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent employs self-service by utilizing the thread-fall acoustic signal naturally generated during the threading process itself. The system detects alignment through the inherent acoustic emissions of the thread-fall event, eliminating the need for separate alignment measurement steps and integrating detection into the installation process

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent implements real-time feedback by continuously monitoring acoustic signals during fastener rotation and immediately stopping the rotation when the thread-fall signal is detected. This feedback mechanism ensures precise alignment control while minimizing unnecessary rotation time, balancing reliability with installation speed

Inventive Principle:
Principle #23Feedback

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 tool effectively prevents cross-threading by ensuring accurate alignment, reducing thread damage and failure, and ensuring a secure fastening process, particularly in applications like aerospace where alignment is critical.

Implementation Method 1

The sensor is to measure acoustic waves near the socket while the socket rotates the fastener

Methodology Applied
Scientific EffectAcoustic wave detection: Acoustic Emission

Data Source

PatentEP3354397B1Methods and apparatus to align threaded fasteners
Publication Date: 2020.06.24 THE BOEING CO
  • EP3354397B1 patent drawingFigure 1A~1B
  • EP3354397B1 patent drawingFigure 2A~2B
  • EP3354397B1 patent drawingFigure 3A~3B

AI summary

Example methods and apparatus to align threaded fasteners are disclosed herein. An example apparatus includes a socket (124) to hold a fastener (102) and a sensor (148,154) disposed adjacent the socket (124). The sensor is to measure acoustic waves near the socket (124) while the socket rotates the threaded fastener (102) in a reverse-thread direction against an end of a threaded pin (104). The example apparatus also includes an electronic control unit to determine whether the fastener and the threaded pin are aligned based on the acoustic waves measured by the sensor (148,154).