Optical Fiber Cooling Tube Dew Point Control
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Solution Overview
Problem
In optical fiber manufacturing, the formation of frost or condensation in the cooling tube's fiber path leads to glass fiber breakage due to inappropriate dew point measurement positions, allowing excess water vapor to be carried into the path, which is exacerbated by increased drawing speeds and exposure to outside air containing higher water vapor.
Innovation Solution
Implementing a method where a dry gas with a dew point lower than the cooling tube's temperature is supplied between the casing and cooling tube, with dew point measurement at the inlet and outlet of the fiber path to control the coolant temperature and gas flow rate, ensuring the cooling tube's temperature is higher than the measured dew point, thereby reducing frost and condensation formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the glass fiber is exposed to outside air between the drawing furnace and cooling device, then the cooling performance is maintained, but water vapor from outside air is carried into the casing causing frost or condensation formation
Solution Approach 1:
The patent introduces a dry gas supply device that supplies dry gas (such as nitrogen or dry air) into the casing to create a dry atmosphere environment. This inert/dry atmosphere prevents water vapor from outside air from condensing on the cooling tube surface, while still allowing the cooling function to operate effectively. The dry gas flow rate is controlled to maintain the dew point below the cooling tube temperature.
2Measurement precision
If the dew point measurement position is not appropriate, then the dew point measurement may not reflect the actual water vapor conditions in the fiber path, but increasing measurement positions increases device complexity
Solution Approach 1:
The patent places the dew point measurement position specifically at the outlet of the fiber path where the glass fiber exits the casing. This location is critical because it is where outside air is most likely to be carried in and where condensation is most probable. By focusing measurement at this specific local position, the system achieves accurate monitoring of the most critical area without needing multiple measurement points throughout the entire casing.
3Productivity
If the drawing speed of the glass fiber is increased, then productivity is improved, but outside air is more readily carried into the casing increasing frost or condensation risk
Solution Approach 1:
The patent implements a feedback control system where the dew point measurement results from the outlet position are continuously monitored and fed back to adjust the dry gas supply flow rate. When drawing speed increases and more outside air is carried in, the dew point measurement detects this change and the control device increases the dry gas supply to maintain the dry atmosphere, preventing condensation even at high drawing speeds.
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 effectively reduces the formation of frost and condensation in the fiber path, minimizing glass fiber breakage by accurately measuring and controlling the dew point and gas flow, even at high drawing speeds, ensuring consistent cooling and resin application conditions.
Implementation Method 1
a cooling tube cooled by a coolant... the glass fiber is cooled when passing through a fiber path that extends through the cooling tube
Implementation Method 2
the dew point of outside air is higher than the temperature of a cooling tube. In the related-art, the formation of frost or condensation may occur... controlling the temperature of the coolant in the cooling tube such that the temperature of the cooling tube is higher than the second dew point
Data Source
AI summary
An optical fiber manufacturing method includes a process of passing a glass fiber through a fiber path before applying a resin. The glass fiber is drawn from a glass preform, the fiber path is formed through a cooling tube, and the cooling tube is housed in a casing and is cooled by a coolant. The process includes supplying a dry gas into a dry space formed between the casing and the cooling tube. The dry gas has a first dew point lower than the temperature of the cooling tube. The process includes measuring, by a dew point meter, a second dew point at one or both of an inlet and an outlet of the fiber path. The process includes controlling the temperature of the coolant in the cooling tube such that the temperature of the cooling tube is higher than the second dew point measured by the dew point meter.