Optical Fiber Glass Preform Sintering for Transparency and Diameter Stability
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Solution Overview
Problem
Existing methods for producing glass base material for optical fiber suffer from issues such as opaque glass portions and elongation due to complex parameter adjustments, which are difficult to manage across different sintering apparatuses, leading to fiber breakage and diameter fluctuations.
Innovation Solution
A manufacturing method involving the controlled reduction of halogen-containing gas concentration, specifically chlorine, during the sintering process by adjusting the relative movement of the heater and gas flow rates, to suppress opaque glass portions and outer diameter differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the heating temperature is raised excessively to promote transparent vitrification, then the transparency of glass base material is improved, but softening occurs due to heating causing elongation and diameter variation
Solution Approach 1:
The patent applies dynamic control by moving the heating position from the bottom end to the top end of the base material during sintering, and dynamically adjusting both the vitrification temperature and helium gas flow rate at different stages. This dynamic approach allows the system to achieve transparent vitrification while preventing excessive softening and elongation that would occur with static high-temperature heating.
Solution Approach 2:
The patent changes multiple parameters during the sintering process: (1) vitrification temperature is decreased as heating progresses, (2) helium gas flow rate is decreased to control gas pressure, and (3) heating position moves along the base material. These coordinated parameter changes enable transparent vitrification while maintaining dimensional stability and preventing elongation.
2Manufacturing precision
If a combination of several parameters (vitrification temperature, heating position movement speed, gas flow rate) is adjusted to suppress opaque glass portion and elongation, then the quality of glass base material is improved, but the complexity of optimization and management increases
Solution Approach 1:
The patent establishes predetermined relationships between parameters before the sintering process begins. Specifically, it defines that the helium gas flow rate should be decreased in conjunction with heating position movement, and that vitrification temperature should follow a specific decreasing pattern. These preliminary prescriptions simplify the complex multi-parameter optimization into a manageable coordinated control scheme.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the sintering process and adjusting parameters based on the state of the base material. The heating position movement speed, gas flow rate, and temperature are adjusted based on feedback from the dehydration and vitrification progress, enabling automatic coordination of multiple parameters without requiring complex manual optimization.
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 effectively reduces opaque glass portions and outer diameter variations by simple parameter adjustments, ensuring consistent fiber quality and performance.
Implementation Method 1
a glass base material for optical fiber is produced by dehydrating and sintering a porous base material for optical fiber
Implementation Method 2
the manufactured porous base material for optical fiber is hung and heated in a sintering apparatus to manufacture the glass base material for optical fiber
Implementation Method 3
heating the porous base material for optical fiber while moving the heater relative to the porous base material for optical fiber
Data Source
AI summary
A manufacturing method of glass base material for optical fiber in which occurrence of opaque glass portion and elongation can be suppressed is provided. A preparation step of porous base material for optical fiber in which a porous glass layer is formed around the periphery of a core rod; a sintering preparation step, in which the porous base material for optical fiber is hung in a furnace core tube of a sintering apparatus; and a sintering step in which a mixture of halogen-containing gas and inert gas is flowing into the furnace core tube and the porous base material for optical fiber is made into transparent glass by heating the porous base material for optical fiber while moving the heater relative to the porous base material for optical fiber from one end of the core rod to the other end, to obtain glass base material for optical fiber, are performed.