Cleaning Head Precession Motion for Ophthalmic Lens Mold Maintenance

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Solution Overview

Problem

Existing methods for cleaning deposited material from ophthalmic lens molds, particularly contact lens molds, are inadequate as they either fail to completely remove residues or risk damaging the molding surface, leading to defective lenses due to accumulated deposits.

Innovation Solution

A method and device utilizing a cleaning head with a rotational axis that moves in a precession motion with an inclination angle, pressed against the molding surface with a controlled force, and optionally using a cleaning liquid, to effectively remove deposits without damaging the surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If abrasive cleaning methods are used to remove deposits from the molding surface, then the deposits are removed, but the molding surface gets damaged

Engineering Contradiction:
Improvedeposit removal reliabilityVSAvoidmolding surface quality
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent replaces abrasive mechanical cleaning with a non-contact ultrasonic cleaning system. Ultrasonic waves are generated in a cleaning liquid, creating cavitation bubbles that implode to remove deposits without mechanical contact, thus eliminating surface damage while maintaining effective deposit removal

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

Solution Approach 2:

The invention uses a jet of cleaning liquid under pressure to pre-loosen deposits on the molding surface before ultrasonic cleaning. This hydraulic pre-treatment reduces the energy required for ultrasonic cleaning and improves overall cleaning effectiveness without requiring direct mechanical contact

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Manufacturing precision

If cleaning is performed frequently to prevent deposit accumulation, then lens quality is maintained, but production time is reduced

Engineering Contradiction:
Improvelens optical qualityVSAvoidproduction cycle time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The cleaning system is designed to be integrated into the production line, allowing continuous or near-continuous cleaning operation. The automated ultrasonic cleaning can be performed quickly and repeatedly without significant interruption to production flow, maintaining lens quality while minimizing impact on productivity

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The system performs a preliminary jet cleaning step before ultrasonic cleaning, which loosens and removes loose deposits. This pre-treatment reduces the time required for the main ultrasonic cleaning phase, making the overall cleaning process faster and less intrusive to production timing

Inventive Principle:
Principle #10Preliminary action

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 method reliably removes deposits from the molding surface, preventing the production of defective lenses by maintaining the optical quality and longevity of the mold, allowing for continuous production within specifications.

Implementation Method 1

bringing a cleaning head (2) having a rotational axis (22) into contact with the molding surface (10)... while maintaining the contact between the cleaning head (2) and the molding surface (10)

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3229982B1Method and device for cleaning deposited material from a molding surface of a mold for forming ophthalmic lenses
Publication Date: 2021.11.03 ALCON INC
  • EP3229982B1 patent drawingFigure 1~2

AI summary

A method of cleaning deposited material from a molding surface (10) of a mold (1) for forming ophthalmic lenses comprises the steps of: - bringing a cleaning head (20) into contact with the molding surface (10), the rotational axis (22) of the cleaning head (20) being arranged normal to the molding surface (10), - rotating (220) the cleaning head (20) around the rotational axis (22) while maintaining the contact between the cleaning head (20) and the molding surface (10), - moving the cleaning head (20) to perform a precession motion (110) around a central normal (11) on the molding surface (10), while rotating (220) the cleaning head (20) around the rotational axis (22) and while maintaining the contact between the cleaning head (20) and the molding surface (10). During the precession motion (110) the rotational axis (22) includes an inclination angle (α1,α2) with the central normal (11) on the molding surface (10).