Helical Relief Pin for Rimless Spectacle Lens Fixing

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Solution Overview

Problem

Existing fixing devices for rimless spectacles often distribute clamping stresses unevenly, leading to potential lens breakage due to excessive tension, especially when materials with different mechanical characteristics are used.

Innovation Solution

The device employs pin-type appendages with helical reliefs and bush members with annular channels and grooves to distribute pressure obliquely, reducing tension on the lens and enhancing retention through a gripping action between the pin, bush, and lens surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pin-type appendages are inserted into through holes with bush members to fix mount members to lenses, then adequate and stable coupling is obtained, but clamping stresses are unevenly distributed which may lead to lens breakage

Engineering Contradiction:

Improvecoupling stabilityVSAvoidlens strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The pin-type appendage features a helical relief that creates localized gripping zones at specific angular positions. This concentrates the locking action at discrete points along the pin-bush interface, improving coupling stability while distributing stresses more favorably compared to uniform circumferential contact. The helical geometry provides progressive engagement that enhances reliability without requiring excessive clamping force on the lens.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The helical relief introduces a curved, spiral geometry to the pin surface that engages with the bush interior. This curved configuration allows for gradual stress distribution along the helical path rather than concentrated radial loading. The spiral engagement pattern transforms the stress distribution from uniform radial compression to a more favorable gradient, reducing peak stresses on the lens while maintaining secure coupling.

Inventive Principle:

Principle #14Spheroidality (Curvature)

2Adaptability or versatility

If materials with different mechanical characteristics are used for lens and frame, then functional requirements are met, but stress distribution becomes uneven leading to potential lens failure

Engineering Contradiction:

Improvematerial compatibilityVSAvoidstress distribution

Core Design Contradiction:

Adaptability or versatilityVSStress or pressure

Solution Approach 1:

The bush member acts as an intermediary element between the mount member and lens, providing a compliant interface that accommodates differences in mechanical characteristics between frame and lens materials. The helical relief on the pin-type appendage works in conjunction with the bush to create a gradual stress transition zone, mediating the stress transfer and preventing sudden stress concentrations that would occur with direct rigid coupling of dissimilar materials.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The helical relief geometry changes the stress transfer parameters by introducing a spiral engagement path. This transforms the stress distribution from direct radial loading to a progressive angular engagement, modifying how forces are transmitted through the bush member. The helical configuration effectively changes the mechanical interaction parameters to accommodate material mismatches between frame and lens while maintaining acceptable stress levels.

Inventive Principle:

Principle #35Parameter changes

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

This configuration improves the grip and pressure distribution, reducing the risk of lens breakage by evenly distributing forces and ensuring secure locking without excessive tension.

Implementation Method 1

The pin-type appendage (11) is provided with a relief (13) protruding from the outer wall and extending on a helical course in the axial direction of the pin-type appendage

Methodology Applied

Scientific EffectHelical relief: Helix

Implementation Method 2

capable of impinging on the inner surface of the bush for mutual coupling in order to guarantee, by means of localised deformation of the bush itself, the relative locking with same

Methodology Applied

Scientific EffectLocalised deformation: Deformation

Data Source

PatentUS7832854B2Device for fixing mount members to spectacle lenses, and spectacles, particularly of the type devoid of lens-holding rims, including said fixing device

Publication Date: 2010.11.16 SAFILO SPA

AI summary

A device for spectacles, such as a lug for the articulation of a spectacle arm or a central nasal support bridge, to a lens, the lens has a pair of holes for the locking of the mount member, has a pair of bush members rigidly connected to each other and has respective axial holes, there being provided in the mount member a pair of pin-type appendages capable of being inserted into the respective holes subject to the introduction of these latter into the corresponding lens holes, such that each bush member is interposed between an inner surface of the lens hole and a corresponding outer surface of appendage. Each pin-type appendage has localized protuberances that deform the corresponding coupling surface. The fixing device has at least one relief protruding from the outer wall of each appendage and extending on a helical course in the axial direction of the appendage.