Plastic Lens Casting Mold Positioning for Optical Quality
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Solution Overview
Problem
Manufacturing high-quality plastic lenses from highly viscous starting materials with rapid initial polymerization rates is challenging due to issues like striae and bubble formation when using a movable casting mold, which leads to optical defects.
Innovation Solution
The method involves changing the posture of the casting mold to secure it before the starting material liquid enters the cavity, maintaining this state until the cavity is filled, which reduces flow and entrainment of bubbles within the cavity, thereby minimizing striae and bubble formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the casting mold is moved during casting of highly viscous starting material liquid with rapid polymerization, then operating efficiency is improved, but striae and bubbles are generated causing optical defects
Solution Approach 1:
The casting mold is pre-positioned and secured in the optimal position before the starting material liquid is discharged. This preliminary positioning ensures that the mold is stationary during the critical filling phase, preventing striae and bubble formation, while still allowing the overall casting process to be efficient through automated positioning systems
2Ease of operation
If a flexible tube is used to guide starting material liquid, then freedom of operation is improved, but viscosity increases and adhesion to tube walls occurs
Solution Approach 1:
The flexible tube is completely removed from the casting system. Instead of guiding the starting material liquid through a tube, the mold is directly positioned to receive the liquid discharge. This eliminates the tube wall adhesion problem and viscosity increase issues while maintaining operational flexibility through direct mold positioning
Solution Approach 2:
A guide rail system serves as an intermediary structure that constrains the casting mold's movement path without contacting the starting material liquid. This allows the mold to be moved efficiently to the correct position while preventing direct contact between the liquid and moving components, avoiding adhesion and contamination
3Manufacturing precision
If the casting mold is secured in a vertical state throughout casting, then optical defects are reduced, but operating efficiency decreases
Solution Approach 1:
The casting mold transitions from a dynamic state (movable during positioning) to a static state (secured during filling). The mold can be efficiently repositioned between casts, then securely fixed in the vertical position during the filling operation to prevent defects, combining operational efficiency with manufacturing 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 enables the production of high-quality plastic lenses with reduced optical defects by controlling the flow of the starting material liquid during the casting process, even with highly viscous materials and rapid polymerization rates.
Implementation Method 1
a polymerizable plastic lens starting material liquid... with a rapid initial rate of polymerization... polymerization continues while the mixed starting material liquid is moving through the flexible tube
Data Source
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AI summary
The present invention relates to a method of manufacturing a plastic lens comprising discharging a plastic lens starting material liquid from a tip opening of a discharge hole of a mixing and discharging part, the mixing and discharging part comprising a mixing chamber comprising a stirring means that stirs a plastic lens starting material liquid and the discharge hole communicating with the mixing chamber; casting the plastic lens starting material liquid that has been discharged into a casting mold, the casting mold comprising a cavity and a casting hole for introducing the plastic lens starting material into the cavity, and the plastic lens starting material being cast into the casting mold through a tip opening of the casting hole; and polymerizing the plastic lens starting material that has been cast within the casting mold to obtain a polymerized product. Before the plastic lens starting material liquid that has been cast into the casting hole reaches an interior of the cavity, the tip opening of the casting hole and the tip opening of the discharge hole are connected to secure the casting mold, and the secured state is maintained until the cavity is filled with the plastic lens starting material liquid.