Decentered Lens Cutting via Tool Geometry Compensation

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Solution Overview

Problem

Existing methods for manufacturing lenses and lens molds with decentered axes are inefficient, requiring multiple re-chucking operations and failing to accurately compensate for tool geometry, especially when using oscillating tools.

Innovation Solution

A method that involves creating a spiral representation of the part surface, calculating X and Z values, compensating for the diamond tool's radius, and generating recalculated points to determine the proper tool position, thereby creating a geometry-compensated zero meridian path for the oscillating tool to follow, minimizing re-chucking and ensuring accurate cutting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional lathing methods are used for decentered lenses, then multiple re-chucking operations are required, but this increases manufacturing time and reduces productivity

Engineering Contradiction:
Improvemanufacturing efficiencyVSAvoidre-chucking time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The method pre-calculates the decentered toolpath and compensates for tool geometry before machining begins. By preparing the compensated toolpath in advance, the system eliminates the need for multiple re-chucking operations during manufacturing, thereby improving productivity and reducing time loss.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention enables a single chucking operation to handle both centered and decentered lens machining through software-based toolpath compensation. This multi-functional capability allows the same setup to produce various lens types without requiring additional re-chucking steps, thus improving manufacturing efficiency.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Manufacturing precision

If simple toolpath generation is used, then programming is easier, but manufacturing precision is insufficient for decentered lenses

Engineering Contradiction:
Improvecutting accuracyVSAvoidtoolpath calculation complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention replaces complex mechanical adjustment systems with a software-based compensation method. Instead of physically adjusting the tool or workpiece to achieve decentered machining, the system uses computational geometry to calculate compensated toolpaths, maintaining precision while simplifying the physical setup.

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

Solution Approach 2:

The method transforms the complex decentered machining problem into a parameter-based solution by calculating compensated coordinates based on lens decentering amount, lens curvature radius, and tool radius. This parametric approach enables precise control of cutting accuracy through mathematical calculations rather than complex mechanical systems.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If tool geometry is not compensated, then the cutting process is simpler, but the resulting lens surface precision is insufficient

Engineering Contradiction:
Improvesurface accuracyVSAvoidcompensation calculation complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention replaces physical tool geometry adjustments with computational compensation. Instead of mechanically modifying the tool or workpiece setup to account for tool radius and lens decentering, the system calculates compensated toolpaths that automatically account for these geometric factors, achieving high surface accuracy through software rather than mechanical complexity.

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

4Reliability

If multiple re-chucking operations are performed, then complex lens geometries can be achieved, but tool wear increases and reliability decreases

Engineering Contradiction:
Improveprocess stabilityVSAvoidmulti-step machining complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The method pre-calculates the complete compensated toolpath for the entire decentered lens geometry before machining begins. This preliminary preparation enables the system to machine complex decentered lenses in a single continuous operation without intermediate re-chucking, thereby improving process reliability and reducing tool wear while maintaining the ability to create complex geometries.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP2089781B1Method of surface manufacture with an apex decentered from a spindle axis
Publication Date: 2018.02.28 NOVARTIS AG
  • EP2089781B1 patent drawingFigure 1~2
  • EP2089781B1 patent drawingFigure 3~4
  • EP2089781B1 patent drawingFigure 5

AI summary

The present invention is related to manufacturing surfaces with an axis decentered from the spindle axis. In particular, the present invention is related to compensating for tool geometry in cutting processes that involve an oscillating tool.