Spectacle Lens Machining Speed Based on Geometric Complexity
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Solution Overview
Problem
The challenge in machining spectacle lenses lies in finding a balance between productivity and surface conformity, as low speeds ensure conformity but reduce productivity, while high speeds increase productivity at the cost of conformity, and determining optimal machining parameters for complex surfaces is complex.
Innovation Solution
A method is developed to determine a fixed rotational speed for machining spectacle lenses by calculating the greatest difference in mean sphere geometric values and cylinder values, independent of the lens material, using standard optical calculation tools, and creating a correspondence table for intrinsic difficulty levels to select appropriate machining parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a very low machining speed is used, then the conformity of the surface produced with the desired surface is ensured, but the productivity is reduced
Solution Approach 1:
The invention changes the machining parameter (rotational speed) dynamically based on the local geometric complexity of the surface. By calculating the mean sphere geometric value and cylinder geometric value at each point, the system determines an optimal rotational speed that adapts to the local surface characteristics, allowing high speeds in simple areas and low speeds in complex areas, thus resolving the contradiction between productivity and surface conformity.
2Productivity
If a high machining speed is used, then the productivity is increased, but the conformity of the surface produced with the desired surface is affected
Solution Approach 1:
The system dynamically adjusts the rotational speed parameter based on real-time calculation of geometric values. In regions with low geometric complexity (low mean sphere difference and low cylinder value), higher rotational speeds are permitted, maintaining productivity. In regions with high geometric complexity, the rotational speed is reduced to ensure surface conformity, thus resolving the contradiction.
3Manufacturing precision
If tests are carried out to determine the optimum machining speed for complex surfaces, then the surface conformity is improved, but the time and complexity of the process increases
Solution Approach 1:
The invention performs preliminary calculations of the mean sphere geometric value and cylinder geometric value before the actual machining process. By pre-determining the optimal rotational speed based on the surface geometry, the system eliminates the need for time-consuming tests during production, thus improving surface conformity without increasing process complexity.
Solution Approach 2:
The invention replaces physical trial-and-error testing with computational calculation. By using mathematical formulas to calculate geometric values and determine optimal speeds, the system substitutes mechanical testing procedures with intellectual computation, reducing both time and complexity while improving precision.
4Manufacturing precision
If the machining parameters are determined based on lens material and refractive index, then the surface conformity is improved, but the complexity of determining parameters increases
Solution Approach 1:
The invention extracts the material-dependent parameters (refractive index, material properties) from the machining parameter determination process. By formulating the rotational speed calculation based solely on geometric values (mean sphere difference and cylinder value) that are independent of material properties, the system simplifies the parameter determination process while maintaining surface conformity through geometry-based adaptation.
Data Source
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AI summary
The invention relates to a machining method for machining a surface of a spectacle lens at a fixed rotation speed, comprising a step of determining said rotation speed from geometric characteristics of said surface, characterized in that the step of determining the rotation speed comprises the following steps: a value (Maxdiff) representative of the largest difference in geometric value of the mean sphere on said surface is determined; and the rotation speed is deduced from said value (Maxdiff) of the largest difference in geometric values of the mean sphere on said surface and from a geometric value of the cylinder (FV torus) at a predetermined far-vision control point.