Optical Fiber Cooling Gas Flow Control for Coating Diameter Stability

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Solution Overview

Problem

Conventional optical fiber manufacturing methods face challenges in maintaining a constant coating diameter and cooling capacity across a wide range of drawing velocities, leading to increased faulty portions, reduced yield, and higher manufacturing costs due to excessive helium gas usage and unstable gas flow.

Innovation Solution

The method involves connecting the cooling device and coating device airtightly, controlling the flow rates of helium and carbon dioxide gases independently using signals for drawing velocity and coating diameter, and directing the gas flow as an upward stream to prevent outside gas entry, thereby reducing helium usage and stabilizing the cooling capacity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the drawing velocity is increased to enhance productivity, then the manufacturing speed improves, but the drawing velocity fluctuation range increases making it difficult to maintain constant coating diameter

Engineering Contradiction:

Improvedrawing velocityVSAvoidcoating diameter consistency

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The cooling gas flow rate is dynamically adjusted based on the actual drawing velocity to compensate for fluctuations. The control system modifies the cooling intensity in real-time, ensuring that the bare optical fiber temperature remains stable despite variations in drawing speed, thereby maintaining constant coating diameter across a wide velocity range

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system uses feedback control where the drawing velocity is monitored and the cooling gas flow rate is automatically adjusted accordingly. This closed-loop control ensures that even when drawing velocity fluctuates within a wide range, the cooling capacity adapts to maintain stable coating conditions and consistent coating diameter

Inventive Principle:

Principle #23Feedback

2Stability of the object's composition

If helium gas flow rate is increased to maintain cooling capacity across wide velocity range, then cooling stability improves, but manufacturing cost increases due to excessive helium usage

Engineering Contradiction:

Improvecooling capacity stabilityVSAvoidhelium gas consumption

Core Design Contradiction:

Stability of the object's compositionVSLoss of substance

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the operating parameters of the cooling gas flow rate according to the drawing velocity conditions. By adjusting the flow rate parameter dynamically rather than maintaining a constant high flow rate, the system achieves stable cooling capacity while significantly reducing helium gas consumption and manufacturing costs

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the cooling device and coating device are connected airtightly with upward gas stream, then outside gas entry is prevented, but device complexity increases

Engineering Contradiction:

Improveprevention of bubble mixingVSAvoidairtight connection structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system uses pneumatic principles by creating an upward flowing gas stream that acts as a barrier to prevent outside gas and bubbles from entering the coating device. The gas flow itself serves as the sealing mechanism, eliminating the need for complex mechanical seals or valves while maintaining reliability

Inventive Principle:

Principle #29Pneumatics and hydraulics

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 reduces helium gas flow rates by 5-50%, maintains a stable upward gas stream, prevents bubble mixing, and ensures a constant coating diameter across a wide velocity range, enhancing yield and reducing manufacturing costs.

Implementation Method 1

A cooling gas (helium gas (He) or the like) is supplied to the inside of the cooling tube from a side portion of the cooling tube. The cooling gas flows upward and downward inside the cooling tube.

Methodology Applied

Scientific EffectForced Convection: Forced Convection

Implementation Method 2

the drawn bare optical fiber 103 is sufficiently cooled down to the temperature at which the bare optical fiber 103 can be coated by the coating resin

Methodology Applied

Scientific EffectThermal Conduction: Conduction (thermal)

Implementation Method 3

The coating resin is thermally cured by a curing device 108 or is ultraviolet-cured.

Methodology Applied

Scientific EffectPhotopolymerisation: Photopolymerisation

Data Source

PatentUS8661856B2Manufacturing method of optical fiber

Publication Date: 2014.03.04 FUJIKURA LTD

AI summary

In an optical fiber manufacturing method, the cooling device and the coating device are connected in an airtight manner and by preventing a cooling gas, flowing inside the cooling device, from flowing into the coating device by a meniscus of resin inside of the coating device, a flow of the cooling gas inside the cooling device is discharged to an outside of an upper end of the cooling device as an upward stream; helium gas as the cooling gas flows into a lower portion of the cooling device and carbon dioxide gas as the cooling gas which is separated from the helium gas flows into a side lower than a position where the helium gas flows in, during the forcible cooling; and a flow rate of the helium gas and a flow rate of the carbon dioxide gas are individually controlled.