Ophthalmic Lens Roughing Speed Control Using Force Feedback
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Solution Overview
Problem
Existing edging machines for ophthalmic lenses operate below their maximum capacity due to the assumption that machining operations are repeatable and tool performance is constant over time, leading to inefficiencies in productivity.
Innovation Solution
A process that measures the force applied during the roughing-out step using a force sensor and adjusts the machining speed continuously to maintain a target value, ensuring the machine operates at its maximum possible speed while preventing quality degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the machining speed is increased to maximize productivity, then the output increases, but the quality of the ophthalmic product deteriorates
Solution Approach 1:
The patent implements a feedback mechanism by continuously measuring the force applied during machining using a force sensor, comparing it to a target value, and adjusting the machining speed accordingly. This closed-loop control allows the system to operate at maximum speed while maintaining quality by reducing speed only when force measurements indicate potential quality issues.
Solution Approach 2:
The patent transitions from static, pre-calculated machining parameters to dynamic, real-time adjustment of machining speed. The system continuously adapts the machining speed based on actual force measurements during the machining process, allowing optimal performance that responds to varying material conditions and tool wear.
2Manufacturing precision
If the machining speed is reduced to maintain constant machining conditions, then the quality is preserved, but the productivity decreases
Solution Approach 1:
The force sensor provides continuous feedback on the actual machining conditions, allowing the system to maintain high speeds when conditions are favorable and only reduce speed when necessary. This eliminates the need for conservative, uniformly reduced speeds while preserving quality.
Solution Approach 2:
The patent dynamically changes the machining speed parameter based on real-time force measurements rather than maintaining a constant speed. This allows the system to exploit favorable conditions for higher productivity while preventing quality degradation through parameter adjustment.
3Productivity
If the target force value is set high to maximize speed, then the productivity increases, but the motor power consumption exceeds maximum values that harm product quality
Solution Approach 1:
The system uses feedback from force measurements to determine when high power consumption is occurring and adjusts the target force value accordingly. This ensures that the motor operates within safe power limits while maintaining the highest possible machining speed that does not compromise quality.
Solution Approach 2:
The patent preemptively reduces the target force value when power consumption approaches harmful levels, preventing quality degradation before it occurs. This anticipatory adjustment allows the system to maintain optimal performance within safe operational boundaries.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Optimizes productivity by allowing the edging machine to operate at its full capacity, reducing machining time without compromising the quality of the ophthalmic products.
Implementation Method 1
a force sensor adapted to measure a force that is related to the force applied by the machining tool to the ophthalmic product
Data Source
AI summary
The invention relates to a process for shaping an ophthalmic product (20) using a machining device (200) equipped with clamping means (202, 203), a machining tool (210) and a force sensor (234) adapted to measure a force that is related to the force applied by the machining tool to the ophthalmic product (20). According to the invention, the process comprising: —a step of clamping the ophthalmic product in said clamping means; and —a step of roughing out the ophthalmic product by means of the machining tool so as to bring the initial outline of the ophthalmic product to a final outline of different shape, wherein, during the step of roughing out: —the value of said force is measured by the force sensor, and —the machining speed is continuously adjusted so as to maintain the measured value equal to a target value.