Spring Fastener Retainer for Reusable Bolted Joint Locking

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Solution Overview

Problem

Existing solutions for securing bolted joints, such as anchor nuts and threaded inserts, have limited use cycles and fail to maintain locking functionality after the bolt is removed, requiring frequent replacement.

Innovation Solution

A spring device with ring-shaped portions and a unique material composition that provides sustained frictional engagement with the threaded fastener, allowing for multiple loosening cycles without performance degradation, featuring a slit for easy positioning and elastic deformation to maintain stability and friction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional anchor nuts or threaded inserts are used to secure bolted joints, then the locking functionality is provided, but the number of use cycles is limited and functionality is lost after bolt removal

Engineering Contradiction:
Improvelocking functionalityVSAvoidnumber of use cycles
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the physical state and material properties of the securing device by using a spring element with elastic properties. The spring constant and material composition are specifically selected to enable the device to withstand repeated compression and expansion cycles while maintaining locking functionality, thereby increasing the number of usable cycles from limited to at least 10, 50, or 100 cycles

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces dynamic characteristics to the securing device through the spring element that can compress and expand. The spring device adapts its shape and friction force dynamically during each assembly-disassembly cycle, allowing it to maintain reliable locking functionality across multiple use cycles unlike static conventional solutions

Inventive Principle:
Principle #15Dynamics

2Reliability

If anchor nuts or threaded inserts are used to prevent self-unscrewing, then the fastener is secured, but frequent replacement is required due to limited loosening cycles

Engineering Contradiction:
Improvefastener securityVSAvoidreplacement frequency
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The spring device maintains its own locking functionality through its elastic properties without requiring replacement. The spring element automatically restores its shape and friction force after each compression cycle, enabling the device to serve itself across multiple loosening cycles (at least 10, 50, or 100 cycles) without degradation that would necessitate replacement

Inventive Principle:
Principle #25Self-service

3Reliability

If friction force is increased to keep the fastener head from rotating, then the fastener stays in place, but the device complexity increases

Engineering Contradiction:
Improvefastener position stabilityVSAvoidspring device structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses a flexible spring element with a specific geometric configuration (including ring-shaped portions and inner peripheral surfaces) that generates the required friction force through elastic deformation. This flexible structure achieves reliable fastener positioning without requiring complex mechanical locking mechanisms, thereby maintaining relatively simple device structure while ensuring stability

Inventive Principle:
Principle #30Flexible shells and thin films

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 spring device ensures the threaded fastener remains securely in place through multiple cycles without the need for replacement, offering enhanced stability and longevity in applications where frequent loosening is required.

Implementation Method 1

the inner peripheral surface of each spring element exerts a friction force against the head of the threaded fastener to keep the head of the threaded fastener from rotating relative the spring device and the fastener arrangement

Methodology Applied
Scientific EffectFriction: Friction

Implementation Method 2

A spring device with ring-shaped portions and a unique material composition that provides sustained frictional engagement with the threaded fastener, allowing for multiple loosening cycles without performance degradation, featuring a slit for easy positioning and elastic deformation to maintain stability and friction

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4177482B1A spring device for securing a threaded fastener of a bolted joint and a system for securing a bolted joint
Publication Date: 2024.11.06 SAAB AB
  • EP4177482B1 patent drawingFigure 1
  • EP4177482B1 patent drawingFigure 2a~2c

AI summary

A spring device (100) for securing a threaded fastener of a bolted joint. The spring device (100) comprises at least one ring-shaped portion (102, 104), and a plurality of elongate spring elements (106). Each spring element (106) is attached at least in a first end to the at least one ring-shaped portion (102, 104). The at least one ring-shaped portion (102, 104) and a body formed by the plurality of spring elements have a common centre axis. Each spring element (106) comprises an inner peripheral surface (108) directed towards the centre axis, and wherein a first portion (108a) of said inner peripheral surface (108) is closer to the centre axis than are other portions (108b) of said inner peripheral surface (108) and closer to the centre axis than an inner peripheral surface (102a) of the at least one ring-shaped portion (102, 104). The disclosure further relates to a system (200) for securing a bolted joint.