Spectacle Lens Bevel Circumference Calculation with Tool Interference

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Solution Overview

Problem

Conventional methods for beveling spectacle lenses fail to accurately account for interference between the beveling tool and the lens, leading to tapering or strain in the bevel shape, which results in fitting issues with the spectacle frame, as they rely on theoretical circumferences that do not consider actual tool interference, causing size failures and quality defects.

Innovation Solution

A method that calculates a theoretical circumference for the spectacle lens by simulating the expected finish shape considering the interference of the beveling tool, allowing for adjustment of the beveling process to prevent tapering or strain, and using this theoretical circumference as a reference for judging defects and ensuring accurate fitting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional beveling methods are used without considering tool interference, then the beveling process is simple and fast, but the bevel shape exhibits tapering or strain leading to fitting failures

Engineering Contradiction:
Improvebevel shape accuracyVSAvoidbeveling process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by calculating the theoretical circumference before the actual beveling process. This pre-calculated circumference, which accounts for expected tool interference through simulation, serves as a reference standard that guides the beveling operation and enables subsequent quality verification without requiring complex real-time adjustments during beveling.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by measuring the actual bevel circumference after the beveling process and comparing it against the pre-calculated theoretical circumference. This comparison provides feedback on whether the beveling was successful in achieving the expected fit, allowing for quality control and identification of defects such as excessive tapering or strain.

Inventive Principle:
Principle #23Feedback

2Manufacturing precision

If the beveling tool interferes with the lens during beveling, then the bevel shape is distorted with tapering or strain, but the interference cannot be eliminated without complicating the tool path

Engineering Contradiction:
Improvebevel circumference accuracyVSAvoidbeveling operation simplicity
Core Design Contradiction:
Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent uses a simulation model to create a virtual copy of the beveling process before actual manufacturing. This simulation copies the tool interference patterns and calculates the resulting theoretical circumference, allowing operators to understand and compensate for interference effects without physically modifying the tool path or adding complex control mechanisms during the actual beveling operation.

Inventive Principle:
Principle #26Copying

3Measurement precision

If the theoretical circumference is calculated without simulating tool interference, then the calculation is simple and quick, but the calculated circumference does not reflect actual bevel shape leading to fitting errors

Engineering Contradiction:
Improvecircumference measurement accuracyVSAvoidcalculation time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent performs the time-consuming simulation and theoretical circumference calculation before the actual beveling process. This preliminary action allows the complex interference modeling to be completed in advance, so that during the actual manufacturing process, operators only need to measure and compare against the pre-calculated value, minimizing real-time computational delays.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2687329B1Method of calculating circumference, method of manufacturing spectacle lens, circumference calculating device and circumference calculating program
Publication Date: 2022.09.14 HOYA CORPORATION
  • EP2687329B1 patent drawingFigure 1
  • EP2687329B1 patent drawingFigure 2~3
  • EP2687329B1 patent drawingFigure 4

AI summary

There is provided a circumference calculating device including an expected shape specifying part 201b configured to obtain an expected finish shape of a bevel in consideration of an interference amount of a beveling tool when beveling is performed to an uncut spectacle lens; and a theoretical circumference calculating part 201d configured to obtain a bevel circumference of the spectacle lens having the expected finish shape obtained by the expected shape specifying part 201b, as a theoretical circumference of this spectacle lens.