Optical Object Machining with Constant Tool Angle
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Solution Overview
Problem
Machining of optical objects, such as ophthalmic lenses, often faces challenges with precision and regularity due to tool wear and the need for complex, expensive machinery, which can result in shape deviations and uneven tool durability.
Innovation Solution
A method involving a machining machine with a turntable and a machining tool that maintains a constant angle between the tool's axis of rotation and the normal to the machined surface, allowing the tool to move in translation parallel or perpendicular to the surface, ensuring consistent contact along a predetermined parallel and reducing acceleration levels and trajectory inversion issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional complex machining machines are used, then machining precision can be maintained, but device complexity and cost increase significantly
Solution Approach 1:
The machining system is segmented into independent functional modules: a simple turntable for workpiece positioning, a linear translation mechanism for tool movement, and a separate angular orientation mechanism. This segmentation allows each component to perform its function with simple mechanics, avoiding the need for complex integrated machines while maintaining machining precision through coordinated operation of the segmented components.
Solution Approach 2:
The invention introduces angular orientation of the turntable as an additional degree of freedom, allowing the machining tool to maintain a constant angle with the workpiece surface during translation. This dimensional approach enables precise control of tool-surface geometry without requiring complex multi-axis coordination found in conventional machines.
2Manufacturing precision
If conventional spiral machining paths are used, then complete lens coverage is achieved, but acceleration levels increase and trajectory inversion problems occur
Solution Approach 1:
Instead of using a spiral path that starts from the center and moves outward, the invention inverts the approach by using parallel linear trajectories that scan across the lens surface. This inversion eliminates the singularity at the center where velocity is zero in spiral paths, resulting in more uniform acceleration and no trajectory inversion problems.
Solution Approach 2:
The machining parameters are changed from a continuous spiral trajectory to discrete parallel linear passes with constant translation speed. The angular orientation of the turntable is adjusted between passes rather than during each pass, maintaining constant speed and avoiding acceleration spikes associated with spiral path transitions.
3Manufacturing precision
If oversized machine axes are used, then trajectory precision is improved, but machine complexity and cost increase
Solution Approach 1:
The invention applies local quality by ensuring the machining tool maintains contact with the workpiece along the same predetermined parallel throughout the process. This localized consistent contact geometry, combined with the constant angle between tool axis and surface normal, achieves high trajectory precision without requiring oversized machine axes with complex control systems.
Data Source
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AI summary
Method for machining a face (1) of an optical object (6), comprising a step of providing a machine tool which itself comprises: a bed (1) for locating an object to be machined, this bed (1), which has a receiving surface (3), being angularly adjustable about an axis perpendicular to the receiving surface (3); a spindle (8) suitable for rotating a machining tool (9) about an axis essentially parallel to the receiving surface (3) of the bed (1) and suitable for moving this machining tool (9) translationally in a plane essentially parallel or perpendicular to the receiving surface (3) of the bed (1).