Cryogenic Lens Blank Mandrel for Precise Haptic Centering
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Solution Overview
Problem
Conventional techniques for machining intraocular lenses, particularly hydrophobic materials, face challenges in ensuring accurate alignment and centering of the haptic during the milling process, especially when using cryogenic methods.
Innovation Solution
A mandrel with a central cavity and projections to support the lens blank, combined with a ring that fits within the periphery and an interference fit, allows for precise positioning and stabilization using a frozen liquid, such as water, to maintain the lens blank's alignment during machining.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cryogenic methods are used to machine hydrophobic lens materials, then the lens blank can be machined at room temperature, but accurate alignment and centering of the haptic during milling becomes difficult to achieve
Solution Approach 1:
The patent changes the temperature parameter by using a refrigerated chamber to cool the mandrel and lens blank assembly to cryogenic temperatures (e.g., -70°C or lower). This allows hydrophobic lens materials to be machined at temperatures where they maintain dimensional stability and can be precisely aligned and centered during the milling process, resolving the contradiction between machining temperature and manufacturing precision
Solution Approach 2:
The patent introduces a mandrel as an intermediary device that holds and positions the lens blank during machining. The mandrel provides reference surfaces and alignment features that enable precise centering of the haptic relative to the optic, solving the alignment and centering precision problem while working in conjunction with the refrigerated chamber to maintain cryogenic temperatures throughout the process
2Strength
If wax or water (ice) is used to hold the lens blank during machining, then the lens blank can be secured for milling, but ensuring accurate centering of the optic and haptic becomes challenging
Solution Approach 1:
The mandrel serves as an intermediary between the holding medium (wax or ice) and the lens blank. It provides precise mechanical reference surfaces and alignment features that ensure the optic and haptic are accurately centered during machining, overcoming the centering accuracy limitations of using wax or ice alone while maintaining the necessary holding strength
Solution Approach 2:
The patent creates equipotential conditions by providing a refrigerated chamber that uniformly cools the entire mandrel and lens blank assembly. This uniform temperature distribution prevents thermal gradients that could cause distortion or misalignment, thereby maintaining centering accuracy while the mandrel holds the lens blank securely during machining
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 solution ensures precise alignment and stability of the lens blank, facilitating accurate machining and centering of the haptic, even with hydrophobic materials, and allows for prolonged storage and transportation of partially completed lenses before final manufacturing.
Implementation Method 1
The water may be frozen to support the lens blank as it is milled and/or machined
Data Source
AI summary
A mandrel for holding and positioning an intraocular lens blank during manufacturing includes a shank portion having a central axis and a lens blank holding section configured to hold the lens blank. The holding section includes a central cavity formed concentrically with the central axis of the mandrel. Projections are formed on a surface of the central cavity and are configured to support a first surface of the lens blank at a fixed distance from the surface of the central cavity. A ring fits within a peripheral portion of the central cavity to hold a second opposing surface of the lens blank. A method for making an intraocular lens using the mandrel includes filling the space formed under the first surface of the lens with a liquid, such as water, freezing the liquid, and then machining and/or milling the second surface of the lens blank.