Lens Chuck Torque Control for Water-Repellent Edge Grinding
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Solution Overview
Problem
Eyeglass lens processing apparatuses face challenges in suppressing 'axis deviation' when processing water-repellant lenses with slippery surfaces, leading to attachment slippage and rotation angle deviations during peripheral edge processing.
Innovation Solution
The apparatus employs a combination of load torque detection, encoder-based rotation angle monitoring, and adaptive control of lens chuck shaft movement and grindstone rotation speed to maintain a predetermined load torque and prevent axis deviation, utilizing a control unit that calculates and adjusts the processing path and speed based on measured lens shape and thickness data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the lens is rotated at a constant speed and the axis-to-axis distance between the lens chuck shafts and grindstone rotating shaft is adjusted to maintain constant cutting amount, then processing efficiency is improved, but axis deviation occurs due to slippage on the slippery water-repellant lens surface
Solution Approach 1:
The patent implements a feedback control mechanism where a monitor unit continuously detects the torque applied to the lens during rotation. The control unit receives this torque information and dynamically adjusts the rotational speed of the lens chuck shafts to maintain torque within a predetermined range, preventing slippage on water-repellant lens surfaces while maintaining processing efficiency
Solution Approach 2:
The system transitions from constant speed rotation to dynamic speed adjustment based on real-time torque conditions. The rotational speed is continuously modified according to the detected torque levels, allowing the system to adapt to varying lens surface conditions and prevent axis deviation while maintaining optimal cutting conditions
2Manufacturing precision
If the lens rotating speed is reduced to maintain load torque within a predetermined value, then axis deviation is suppressed, but processing time increases
Solution Approach 1:
The system employs periodic monitoring of torque at specific intervals during lens rotation. By detecting torque at critical points and making targeted speed adjustments only when necessary, the system maintains precision control while minimizing the impact on overall processing time through selective rather than continuous speed reduction
3Ease of operation
If the cup attachment is used to hold the water-repellant lens, then the lens can be mounted on the lens chuck shaft, but the slippery surface causes attachment slippage and rotation angle deviation
Solution Approach 1:
The monitor unit provides continuous feedback on the torque conditions during lens rotation, allowing the control unit to detect early signs of attachment slippage. When torque exceeds predetermined thresholds indicating potential slippage, the system automatically adjusts rotational speed to maintain secure attachment and prevent axis deviation
Solution Approach 2:
The cup attachment acts as an intermediary between the lens chuck shaft and the water-repellant lens surface. By combining this mechanical interface with torque-based speed control, the system compensates for the low friction characteristics of water-repellant surfaces, ensuring reliable attachment while maintaining rotation precision
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
This approach effectively suppresses axis deviation and enables efficient processing of water-repellant lenses by maintaining precise control over the processing path and speed, reducing the likelihood of slippage and rotation angle deviations.
Implementation Method 1
a load detector that detects a load torque applied to the lens chuck shafts
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
In an eyeglass lens processing apparatus, a roughing tool for roughing a periphery of an eyeglass lens cuts the periphery up to a roughing path without rotating an eyeglass lens in a first stage and the roughing tool moves along the roughing path while rotating the eyeglass lens in a second stage. A calculating unit for obtaining control data of the lens rotating unit at the second stage. The calculating unit obtains a first load torque applied to a lens chuck shaft at every rotation angle of the lens based on condition data, and obtains a rotation speed of the lens at which the first load torque per unit time becomes equal to or lower than a predetermined reference value.