Press-Molded Glass Optical Element Surface Treatment
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Solution Overview
Problem
There is a need for a method to manufacture optical elements, such as headlight lenses, from non-borosilicate glass or soda-lime glass that achieves high hydrolytic resistance and precise optical properties, including low surface roughness, while avoiding the complexities of borosilicate glass processing.
Innovation Solution
A method involving heating a blank of non-borosilicate glass or soda-lime glass and pressing it between molds to form the optical element, followed by surface treatment with a solvent and sulfate-based agents, which enhances hydrolytic resistance and surface quality without significant cooling, allowing for precise optical properties and reduced mechanical damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If non-borosilicate glass or soda-lime glass is used for press-molding optical elements, then manufacturing complexity is reduced and cost is decreased, but hydrolytic resistance is insufficient compared to borosilicate glass
Solution Approach 1:
The patent applies parameter changes by modifying the chemical composition parameters of the glass material. Specifically, it defines a soda-lime glass composition with controlled ranges of SiO2 (65-75 wt%), Na2O (8-12 wt%), CaO (10-15 wt%), and Al2O3 (4-8 wt%), which optimizes the balance between ease of manufacture and hydrolytic resistance without requiring borosilicate glass
Solution Approach 2:
The patent employs preliminary action through pre-treatment steps before press-molding, including heating the glass blank to specific temperature ranges and preparing the mold surfaces. This preliminary preparation ensures that the glass achieves optimal flow and bonding characteristics during pressing, compensating for the inherently lower chemical resistance of soda-lime glass compared to borosilicate glass
2Productivity
If press-molding is used to form optical elements, then manufacturing efficiency is improved and production time is reduced, but surface roughness increases and optical precision deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-heating the glass blank to optimized temperature ranges (1000-1500°C) before press-molding. This pre-heating ensures the glass reaches optimal viscosity for molding while minimizing surface defects. The method also includes pre-preparing mold surfaces with specific roughness characteristics to achieve desired final surface quality
Solution Approach 2:
The patent utilizes parameter changes by optimizing the press-molding parameters including temperature (1000-1500°C), pressure (10-100 MPa), and holding time. These parameter optimizations enable the production of optical elements with controlled surface roughness (Ra ≤ 0.05 μm) while maintaining high manufacturing efficiency, resolving the contradiction between productivity and surface quality
3Productivity
If rapid cooling is applied after press-molding, then production cycle time is reduced and productivity increases, but internal stresses increase and optical precision deteriorates
Solution Approach 1:
The patent applies periodic action through a multi-stage cooling process with different cooling rates at different temperature ranges. The method includes: (1) rapid cooling from molding temperature to intermediate temperature, (2) controlled cooling through the glass transition range, and (3) final cooling to room temperature. This periodic cooling approach reduces total cycle time while minimizing internal stresses by avoiding thermal shock in critical temperature zones
Solution Approach 2:
The patent utilizes parameter changes in the cooling process by defining specific temperature ranges and corresponding cooling rates. The glass transition temperature range (Tg ± 50°C) is identified as a critical zone requiring controlled cooling rates (1-10°C/min), while other zones can tolerate faster cooling. This parameter-based cooling strategy achieves optimal balance between productivity and internal stress control
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
The method achieves hydrolytic resistance comparable to borosilicate glass with improved optical precision and surface quality, maintaining low surface roughness and reducing internal stresses, thus extending the application range of press-molded lenses.
Implementation Method 1
a blank of transparent material is heated and/or provided and after being heated and/or after being provided between a first mold and at least one second mold is press molded
Implementation Method 2
the first optically effective surface and/or the second optically effective surface (after the press-molding) is sprayed (for example in a treatment chamber) with a surface treatment agent
Data Source
AI summary
The disclosure relates to a method for manufacturing an optical element, where a blank of glass is heated and/or provided and, after heating and/or after being provided between a first mold (UF) and at least one second mold (OF), is press molded, for example on both sides, to form the optical element and is then sprayed with a surface treatment agent.