Optical Fiber Cooling and Coating with CO2 Sealing
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Solution Overview
Problem
Conventional optical fiber manufacturing methods face challenges in reducing helium gas usage while maintaining cooling efficiency, leading to unstable cooling and coating processes due to mixed gas flows and varying drawing speeds, which affect the thickness and stability of the protective coating layer.
Innovation Solution
The method involves a cooling unit where helium gas and carbon dioxide gas flow vertically upwards, with the carbon dioxide gas introduced from a position below the helium gas supply, and their flow rates adjusted to optimize cooling ability and prevent bubble incorporation in the coating layer, allowing for reduced helium gas usage and stable coating thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If helium gas is used as cooling gas to maintain high cooling efficiency, then cooling ability is improved, but manufacturing cost increases due to expensive helium gas
Solution Approach 1:
The patent replaces expensive helium gas with cheaper carbon dioxide gas as the cooling medium. CO2 is introduced into the cooling tube to cool the drawn optical fiber, significantly reducing manufacturing costs while maintaining adequate cooling efficiency. The system accepts that CO2 has lower thermal conductivity than helium but compensates through optimized flow control and sealing mechanisms.
Solution Approach 2:
The patent changes the physical parameters of the cooling system by substituting the cooling gas type from helium to carbon dioxide. This parameter change is accompanied by adjustments in gas flow rate, pressure, and sealing mechanisms to optimize the cooling performance with the new gas, achieving cost reduction while maintaining process stability.
2Reliability
If carbon dioxide gas is introduced to seal and prevent helium dilution, then cooling gas dilution is reduced, but gas flow stability deteriorates due to mixed gas flows
Solution Approach 1:
The patent extracts the sealing function from the cooling gas flow system by introducing a separate carbon dioxide gas supply. The CO2 gas is specifically tasked with sealing the lower end of the cooling tube and preventing air infiltration, while the helium (or reduced CO2) flow focuses on cooling. This separation of functions stabilizes the overall gas flow despite the presence of multiple gases.
Solution Approach 2:
Carbon dioxide gas serves as an intermediary substance with dual functionality: it acts as both the primary cooling medium and the sealing gas. By using CO2 in both roles with controlled flow rates, the patent eliminates the need for separate helium and sealing gas systems, simplifying the gas flow dynamics and improving stability while reducing costs.
3Productivity
If drawing speed is increased to improve productivity, then manufacturing efficiency is improved, but coating thickness uniformity deteriorates due to unstable cooling
Solution Approach 1:
The patent ensures continuous and stable cooling gas flow through optimized sealing mechanisms and flow control. By preventing air infiltration and maintaining consistent CO2 (or helium) flow rates, the cooling action remains continuous and uniform even at high drawing speeds. This stability in cooling ensures uniform fiber temperature and consistent coating thickness application throughout the drawing process.
Solution Approach 2:
The patent implements flow rate adjustment mechanisms that can respond to changes in drawing speed. By monitoring and adjusting the cooling gas flow rate in response to varying drawing conditions, the system maintains optimal cooling efficiency and temperature control across different productivity levels, ensuring consistent coating quality regardless of drawing speed variations.
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 significantly reduces helium gas consumption, stabilizes gas flows, and maintains consistent coating thickness across the optical fiber, enhancing manufacturing stability and reducing costs.
Implementation Method 1
a cooling unit 104 that extends longitudinally in a vertical direction is provided. Inside the cooling tube 104A, a cooling gas such as helium gas is supplied from a side portion 104a of the cooling tube 104A at the longitudinal center position... the bare optical fiber 103 pulled out of the heating furnace 102 is cooled by the cooling gas
Implementation Method 2
The cooling gas flowing toward a vertically lower end of the flow channel is blocked by the molten resin used to form the protective coating layer
Data Source
AI summary
An optical fiber apparatus and manufacturing method thereof includes: forming a bare optical fiber by melting and deforming an optical fiber preform; cooling the bare optical fiber after the bare optical fiber forming step by passing it through a flow channel of a cooling unit through which cooling gas flows; and forming a protective coating layer by supplying a molten resin to a periphery of the bare optical fiber after the cooling step thereby forming an optical fiber. The cooling gas flowing toward a vertically lower end of the flow channel is blocked by the molten resin used to form the protective coating layer, and carbon dioxide gas is supplied toward the flow channel from a position which is vertically below the supply position of the cooling gas and vertically above the blocking position of the molten resin.