Fastening Socket Assembly With Internal Flats for High-Torque Locking

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Solution Overview

Problem

Temporary fasteners in the aeronautical industry face issues with secure locking during high torque applications and inadequate gripping by automation, leading to insufficient blocking and handling challenges, especially when putty has polymerized in through-holes.

Innovation Solution

A fixing sleeve with radially projecting flats on its internal surface and an elongated element with a threaded rod and hooking mechanism, combined with a nose piece that allows axial locking and easy transport, ensures secure rotation and removal of fasteners even with polymerized putty.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cross-shaped notches are made in the socket head, then the sleeve can be locked in rotation, but the blocking is insufficient when high torque is exerted on the screw

Engineering Contradiction:
Improvelocking reliabilityVSAvoidtorque resistance
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent replaces the symmetric cross-shaped notches with asymmetric radially projecting flats on the internal cylindrical surface. These flats are positioned at specific angles and depths to provide asymmetric engagement with the elongated element, creating more effective mechanical interlocking that resists high torque loads while maintaining rotational locking capability.

Inventive Principle:
Principle #4Asymmetry

Solution Approach 2:

The patent utilizes the cylindrical curvature of the internal surface and the radially projecting flats to create a geometric engagement system. The curved cylindrical geometry provides continuous contact surfaces that better distribute stress and resist torque compared to the sharp edges of cross-shaped notches, improving both locking reliability and torque resistance.

Inventive Principle:
Principle #14Spheroidality (Curvature)

2Reliability

If cross-shaped notches are made in the socket head, then the sleeve can be locked in rotation, but the gripping by automaton is insufficient

Engineering Contradiction:
Improvelocking reliabilityVSAvoidautomaton gripping
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The radially projecting flats serve multiple functions simultaneously: they provide rotational locking engagement with the elongated element, resist high torque loads through their geometric configuration, and create accessible external features that facilitate gripping by automation systems. This multi-functionality eliminates the need for separate gripping mechanisms.

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

Solution Approach 2:

The patent creates external gripping features on the socket body that replicate the engagement geometry of the internal flats, allowing automation systems to grip and manipulate the fastener through the same geometric principles that provide internal locking, simplifying the automation design.

Inventive Principle:
Principle #26Copying

3Strength

If the fastener is designed for secure locking, then high torque can be withstood, but the removal from through-holes with polymerized putty becomes difficult

Engineering Contradiction:
Improvetorque resistanceVSAvoidremoval ease
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The patent designs the engagement between the radially projecting flats and the elongated element to be dynamically adjustable. The geometric configuration allows the flats to flex and adapt during insertion and removal, providing strong mechanical interlocking during torque application while enabling easy extraction when the fastener needs to be removed, even from holes with polymerized putty.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3684549B1Fastening socket for assembling structures and associated attachment
Publication Date: 2021.12.08 LISI AEROSPACE
  • EP3684549B1 patent drawingFigure 1~3
  • EP3684549B1 patent drawingFigure 4~6
  • EP3684549B1 patent drawingFigure 7~10

AI summary

The present invention concerns a fastening socket (112) for assembling at least two previously drilled structures, said socket comprising a substantially cylindrical body (34) and an enlarged head (35); said enlarged head comprising first mounting surfaces (42, 46) suitable for being assembled to a first installation component and for preventing said first installation component from rotating about the main axis. The socket comprises a first substantially cylindrical recess (40) extending along the main axis from the first end, said first recess ending at a planar shoulder (44) substantially perpendicular to said main axis, the first recess and the planar shoulder being received inside the enlarged head, the first mounting surfaces (42, 46) being formed by an inner surface of the first recess.