Washer-Ring Tension Indicator for Bolt Loosening Detection

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Solution Overview

Problem

Existing devices for visualizing nut tightening in assembled structures, such as cranes and pylon structures, fail to provide a reliable and long-term solution for detecting tension loss and untimely loosening, as they are inefficient or prone to premature wear, especially under extreme conditions.

Innovation Solution

A display device comprising non-deformable washers and a diametrically deformable metal ring with rolling balls, which protrudes during tightening and retracts upon loosening, allowing visual verification of nut tension, and includes a spring element for axial thrust and positioning, ensuring reliable operation under various conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If elastomer is used in tightening display devices, then visualization of tightening is achieved, but reliability and durability deteriorate due to premature wear and inefficiency under extreme conditions

Engineering Contradiction:
Improvevisualization capabilityVSAvoidoperation reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the material parameter from elastomer to metal, transforming the deformable ring into a durable metallic component that maintains reliability under extreme conditions while still providing visualization capability through controlled deformation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent replaces the disposable elastomer component with a reusable metal ring that can withstand multiple tightening cycles and extreme conditions, eliminating the need for frequent replacement while maintaining visualization function

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

2Device complexity

If non-protruding visible elements are used in tightening devices, then device simplicity is maintained, but measurement precision deteriorates because loosening cannot be clearly visualized

Engineering Contradiction:
Improvedevice simplicityVSAvoidloosening detection accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent utilizes the radial dimension by designing the metal ring to protrude from the washer periphery when tightened and retract when loosened, providing clear visual indication of tension status without adding complex multi-component structures

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of manufacture

If display elements that do not return to original position are used, then tightening visualization is achieved, but adaptability deteriorates because subsequent loosening and re-tightening cannot be observed

Engineering Contradiction:
Improvetightening indication capabilityVSAvoidmultiple operation cycles capability
Core Design Contradiction:
Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

The patent creates a dynamic system where the metal ring can reversibly deform - protruding when tightened and retracting when loosened - allowing the device to adapt to multiple tightening and loosening cycles while providing continuous visual feedback on tension status

Inventive Principle:
Principle #15Dynamics

4Manufacturing precision

If torque wrenches are used for determined tightening, then tightening precision is improved, but information feedback deteriorates because visual verification of tension loss is not possible

Engineering Contradiction:
Improvetightening precisionVSAvoidtension status information
Core Design Contradiction:
Manufacturing precisionVSLoss of information

Solution Approach 1:

The patent introduces visual feedback through the metal ring indicator that protrudes when properly tightened and retracts when loosened, providing continuous information about tension status and enabling immediate detection of loosening without requiring additional measurement tools

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 device provides a simple, inexpensive, and reliable method for visualizing nut tightening and loosening, ensuring secure assembly and preventing dangerous untimely loosening, with the deformable ring made of durable materials resistant to wear and stress, facilitating easy detection of tension status.

Implementation Method 1

a diametrically deformable viewing ring (3) sandwiched between the two non-deformable washers (2a, 2b)... the deformable ring (3) is made of metal... It can therefore be produced by a toroidal spring of the helical type

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

so that an axial thrust is ensured, forcing the separation in the event of loosening of the device, it comprises a spring element disposed between the non-deformable washers

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 3

The display device according to the invention comprises rolling balls arranged on the surfaces of the ring and intended to be in sliding contact with the internal faces of the non-deformable washers, thus facilitating the movement of said ring

Methodology Applied
Scientific EffectRolling friction: Ball Bearing

Data Source

PatentEP3927982B1Device for viewing tension loss in an assembly
Publication Date: 2023.06.07 UTILLE LIONEL
  • EP3927982B1 patent drawingFigure 1
  • EP3927982B1 patent drawingFigure 2
  • EP3927982B1 patent drawingFigure 3~4

AI summary

The invention relates to a device (1) for viewing tension loss in a structure, by engagement with a threaded rod, being carried out, for example, by a bolt (5) made up of a screw (60), a nut (70), and consisting of two non-deformable washers (2a, 2b) comprising an inner face (20a, 20b), an outer face (21a, 21b), an outer peripheral wall (22a, 22b) and an inner peripheral wall (23a, 23b) delimiting a central opening (24) and a diametrically deformable viewing ring (3) sandwiched between the two non-deformable washers (2a, 2b), characterised in that the ring is crush-resistant and the thickness (e) of at least one of the washers decreases from the centre of the washer towards the peripheral end (25) thereof, the smallest thickness thus being located towards the peripheral end of at least one washer (2a, 2b).