Lens Blank Surfacing Compensation for Cutting Tool Wear
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Solution Overview
Problem
Existing methods fail to address surface irregularities in lens manufacturing due to non-equal wear of the surfacing tool edge, leading to defects such as wrong power, rings, and center irregularities, which are critical to achieve micron-level precision.
Innovation Solution
A computer-implemented method to determine compensated surface description data by generating a compensation map using a transfer function that accounts for the cutting tool's waviness, material interaction, and cutting conditions, recalculating the tool's position to compensate for errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a cutting tool is used for surfacing the lens blank, then the lens surface can be shaped to produce desired optical properties, but non-equal wear along the cutting tool edge introduces surface irregularities such as wrong power, rings, and center irregularities
Solution Approach 1:
The patent applies preliminary action by pre-characterizing the cutting tool edge geometry before surfacing operations. The method includes steps of measuring the actual cutting edge geometry, creating a digital model of the tool, and using this model to compensate for known tool imperfections during the surfacing process. This preliminary characterization allows the system to anticipate and correct for non-equal wear patterns before they manifest as surface irregularities on the lens.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting surfacing parameters based on the characterized cutting tool geometry. The system modifies cutting depth, feed rate, and tool path parameters according to the measured tool edge variations. This adaptive parameter adjustment compensates for non-equal wear along the cutting edge, maintaining consistent surface quality despite tool degradation.
2Duration of action of stationary object
If the cutting tool edge has non-equal wear, then the tool can continue to be used, but surface irregularities are replicated to the lens surface
Solution Approach 1:
The patent implements feedback by continuously monitoring the cutting tool edge geometry during its service life. The system periodically remeasures the tool edge, updates the digital tool model to reflect current wear patterns, and adjusts surfacing parameters accordingly. This closed-loop feedback mechanism allows the tool to be used for extended periods while automatically compensating for wear-induced surface irregularities.
Solution Approach 2:
The patent applies preliminary action by establishing a baseline characterization of the cutting tool edge at the beginning of its service life. This initial characterization creates a reference model that is used throughout the tool's operational life. By having this preliminary data, the system can detect deviations from the original tool geometry and adjust parameters proactively before significant surface defects occur.
3Manufacturing precision
If micron-level precision is required to eliminate surface irregularities, then lens quality improves, but the complexity of the surfacing process increases
Solution Approach 1:
The patent replaces complex mechanical precision requirements with computational methods. Instead of relying solely on mechanical precision of the surfacing machine, the system uses digital modeling and software-based compensation algorithms to achieve micron-level precision. The physical surfacing process remains relatively simple, while the complexity is shifted to the computational domain where it can be more effectively managed and adjusted.
Solution Approach 2:
The patent achieves micron-level precision through parameter changes in the digital model rather than through complex mechanical adjustments. By modifying the digital representation of the cutting tool geometry and adjusting virtual surfacing parameters, the system attains high precision without proportionally increasing physical device complexity. The compensation is achieved through data processing rather than mechanical complexity.
Data Source
AI summary
A method for surfacing a lens blank with a cutting tool A computer-implemented method for determining a compensated surface description data intended to be loaded into a surfacing machine to obtain a surface of an optical element by cutting a blank with a cutting tool of the surfacing machine, the method comprising:—providing a surface description data,—providing contact data from the surface description data,—generating a compensation map by using a transfer function,—determining a compensated surface description data from the generated compensation map and the surface description data.