Ophthalmic Lens Mandrel Trench for Precise Blank Alignment

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Solution Overview

Problem

Current machining techniques for ophthalmic lenses, particularly contact lenses, face challenges in achieving accurate and precise placement of lens blanks on mandrels due to issues with wax placement and consistency, leading to machining errors and suboptimal optical performance.

Innovation Solution

A mandrel with a planar surface region, a curved surface region, and a tool trench between them is used to mount and machine ophthalmic lens blanks, featuring a drainage channel to prevent wax contamination and improve alignment, allowing for more precise machining and reduced errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a block of wax is provided on a front surface of the mandrel to hold the lens blank, then the lens blank can be mounted on the mandrel, but accurate placement of the lens blank and consistent thickness of the wax are difficult to obtain, leading to machining errors

Engineering Contradiction:

Improvemounting reliabilityVSAvoidlens blank placement accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The front surface of the mandrel is segmented into distinct functional zones: a planar region for precise positioning, a curved region for optical contact, and a tool trench for cutting operations. This segmentation allows each region to perform its specific function optimally, with the planar region ensuring accurate lens blank placement while the curved region maintains optical contact during machining.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The tool trench acts as an intermediary feature that receives the cutting tool during machining operations. By providing this dedicated receiving space, the design separates the mounting function (handled by the planar and curved regions) from the machining function, allowing the cutting tool to be precisely positioned without interfering with the lens blank placement accuracy.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If machining techniques are improved for lens members with planar regions and flanges (carrier type), then accuracy and precision are increased, but the same techniques are not effective for lens members without planar regions or flanges (cap type)

Engineering Contradiction:

Improvemachining accuracy for carrier typeVSAvoidapplicability to cap type lens members

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The mandrel design with the planar region, curved region, and tool trench is universally applicable to both carrier type lens members (with flanges) and cap type lens members (without flanges). The planar region provides a consistent reference surface for positioning various lens types, while the curved region adapts to different lens curvatures, making the same mandrel design effective for machining diverse lens member geometries.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS20240359238A1Methods and apparatus relating to the machining of ophthalmic lenses

Publication Date: 2024.10.31 COOPERVISION INT LTD

AI summary

A method of producing an ophthalmic lens member is disclosed. The method comprises mounting an ophthalmic lens member blank 16 on a mandrel 1 for machining. The mandrel 1 has a front surface 6 comprising a planar surface region 10, a curved surface region 8 and a tool trench 12 located between the curved surface region 8 and the planar surface region 10. The method comprises mounting the mandrel 1 on a machine tool; and then severing a portion of the ophthalmic lens member blank 16 by passing a cutting tool 70 through the ophthalmic lens member blank 16 until a portion of the cutting tool 70 is received in the tool trench 12. A mandrel 1 suitable for use in the method is also disclosed.